CN1336939A - Tack free surface cures of polymers by organic peroxides in the presence of air - Google Patents

Abstract

The present invention discloses compositions comprising a mixture of at least one selected from the group consisting of silicone elastomers, di-, tri- or higher polymaleimides and/or di-, tri- or higher polymaleimides and/or di-, tri- or higher and at least one compound selected from the group consisting of p-phenylene-diamine based antiozonants, sulfur-containing compounds capable of promoting sulfur vulcanization of sulfur-crosslinkable polymers Compound, and polysulfide polymer capable of curing substantially tack-free polymer surfaces by decomposition of free radical initiator in the presence of molecular oxygen when mixed with polymer curable by free radical initiator in presence of free radical initiator . The invention also discloses compositions comprising the components described above and at least one free radical initiator, curable compositions comprising said mixtures and their manufacture and use.

Description

Tack-free surface curing of polymers with organic peroxides in the presence of air

This patent application claims priority to Provisional Patent Application 60/164,488, filed November 9,1999.

background of the invention

The present invention relates to compositions classified within the chemical industry as di-, tri- or higher polymaleimides, di-, tri- or higher polycitraconimides, silicone elastomers p-phenylene-diamine based antiozonants, sulfur-containing organic compounds that are accelerators of sulfur curing (crosslinking) of polymers crosslinkable by sulfur, and sulfur-containing organic compounds that are polysulfide polymers compound. The invention also relates to compositions comprising the above components, methods of use thereof and articles made by said methods.

Polymers and copolymers crosslinked with free radical initiators (organic peroxides and/or azo initiators) are known to have good properties, especially polymers crosslinked by sulfur curing. These properties include high heat aging resistance, low compression set, reduced staining of metal or coated metal sheets and ease of manufacture of colored articles with color stability during crosslinking and during long-term use. These properties make the use of peroxide curing especially of great practical importance, since the crosslinking occurs through carbon-carbon bonds rather than through sulfur-containing bonds, and the difference in this bonding improves heat aging resistance and compression permanent out of shape. Free radical curing of polymers from organic peroxides and azo initiators always has the drawback that if air is present on the surface of the material during curing, a tacky surface will form due to molecular oxygen inhibiting the curing.

In order to avoid stickiness on surfaces made with such free radical crosslinked organic peroxide and/or azo initiators, it is common practice to prevent air from contacting the surface during curing to avoid the presence of oxygen in the atmosphere which inhibits curing . Testing to exclude molecular oxygen adds cost and complexity to the curing step, and in the case of steam autoclaves and curing inside tubes, it is sometimes difficult to assure complete exclusion of air and its molecular oxygen constituents. In some cases, producers may prefer to change from sulfur to peroxide curing, using existing hot air oven curing chambers. In these cases, curing with conventional peroxide systems is not feasible due to the formation of tacky surfaces.

To simplify and reduce the cost and complexity of the curing step, various methods have been proposed to prevent molecular oxygen from inhibiting surface curing during radical crosslinking. For various reasons, these methods hardly meet the needs of actual operation or are unsuccessful. Although they offer the best physical properties for peroxide (azo) cure, good compression set at 70 hours at 150°C, they do not provide a tack-free surface, especially compared to the low temperature performance of the prior art at about 100°C.

current technology

US Patent 4983685 discloses the use of compounds selected from the following classes: (a) imidazole compounds, (b) thiourea compounds, (c) thiazole compounds, (d) thiuram compounds, (e) dithiocarbamic acids Ester compounds, (f) phenolic compounds, (g) triazole compounds and (h) amine compounds, which are sulfur vulcanization accelerators for elastomers in the presence of optional antioxidants, antiaging compounds, etc., which can be used in The presence of molecular oxygen in the peroxide cure of elastomers reduces surface tack. In this case, among the optional components suggested as possible components in the formulation, the component that increases crosslinking is N,N'-m-phenylene-bismaleimide.

It is not a preferred optional adjuvant when a dimethacrylate compound is actually used in the examples. The latter bismaleimide compound was not recognized to have an enhancing effect on the ability of certain compounds in (a)-(h) to reduce surface tack during free radical curing in the presence of molecular oxygen. In this document, using various sulfur accelerators especially with peroxides, curing of the polymers results in non-tacky or reduced tacky surfaces, but the important physical properties expected from peroxide cure are also reduced. U.S. Patent No. 4,983,685 fails to recognize that if the silicone elastomers, bismaleimides and dicitraconimides of the present invention are combined with p-phenylenediamine-based antiozonants, Sulfur-containing sulfur vulcanization accelerators mixed with antioxidants and/or polysulfide polymers result in a tack-free surface and improved physical properties, and are not mentioned among all the above crosslinking aids, only these specific types compounds have the effect.

Japanese Published Patent Application No. 9 [1997]-169873 discloses antioxidants of benzimidazole type and 2,2,4-trimethyl-1,2-dihydroquinoline type with standard crosslinking aids For example methacrylate, triallyl cyanurate and maleimide such as the preferred component of this invention N,N'-m-phenylene bismaleimide with standard cross-linked peroxide When used in combination with other compounds, in the presence of air, they form cured peroxide crosslinkable elastomers with a tack-free surface. There is no mention of the inclusion of p-phenylenediamine based antiozonants, silicone elastomers, sulfur accelerators of any type and/or polysulfide polymers.

U.S. Patent No. 4,334,043 suggests surface treatment of curable polymer compositions with organometallic compounds, inorganic metal salts, or lanthanides prior to crosslinking with an organic peroxide crosslinking initiator in air to prevent crosslinking of the surface after crosslinking. sticky. Other than previously known techniques for curing to a tack-free surface by simply excluding air to prevent contact with the rubber surface, no other methods of controlling surface tack have been mentioned.

US Patents 4,814,384 and 4,973,627 disclose the use of sulfur and peroxide combined curing to cure rubber blends for tire treads and sidewalls. Sulfur accelerators are also employed. Auxiliaries of any kind are not mentioned, nor is curing in the presence of air discussed. The use of elemental sulfur is required in the practice of these inventions. We have found, however, that the use of elemental sulfur can adversely affect the final physical properties of cured elastomers to the extent that they are more typically sulfur cured than peroxide cured.

US Patent 4743656 also discusses sulfur/peroxide hybrid curing agents for elastomers, which also contain a sulfur accelerator and elemental sulfur and peroxide. No additives are mentioned, nor are cross-linking in air and surface tack discussed.

The claim of U.S. Patent 4575552 is to use hindered phenolic antioxidant, the metal salt of dithiocarbamate and the specific combination of m-phenylene-bismaleimide to provide Peroxide crosslinked polymer with excellent hydrolytic and thermal stability. There is no mention of the presence of air, prohibition of crosslinking under air, or prohibition of air-formed surface tack.

US Patent 5849214 discloses the use of sulfur compounds, sulfur accelerators and hydroquinone with optional crosslinking assistants in delayed scorch during mixing of free radically crosslinkable polymers in the presence of free radical initiators. Bismaleimides and biscitraconimides are not specifically discussed, nor are their possible effects on surface tack during cure in the presence of molecular oxygen (air) for any of the compositions discussed.

In addition, there are also patents that use various compounds to physically coat the surface of crosslinkable elastomers to exclude air (oxygen). For example, US Patent No. 4,439,388 suggests the use of boric acid and boric anhydride for surface treatment before hot air curing. This surface coating technique is labour-intensive since it must be removed and disposed of after the cross-linking reaction step is complete.

The above documents, alone or in combination, do not propose the applicant's solution and claim the right to exclude air to make the surface non-tacky, while providing the required physical properties of peroxide (azo) curing, for example, the compression set value expected from standard peroxide curing, and at a temperature of about 150 ℃ 70 Hour test compression set.

Overview of the invention

The first aspect of the present invention provides a composition comprising:

(I)其中n是1或2，R是二价或三价，它选自约有2-16个碳原子的非环状脂族基团、约有5-20个碳原子的脂环基团、约有6-18个碳原子的芳基和约有7-24个碳原子的烷芳基，其中这些二价或三价基团可以含有一个或多个选自O、N和S的杂原子代替碳原子(一个或多个)，而且每个R₁相同，是氢或1-18个碳原子烷基；a) at least one compound (A) selected from silicone elastomers and compounds having the following formula (I):

(1) wherein n is 1 or 2, and R is divalent or trivalent, and it is selected from about acyclic aliphatic groups with 2-16 carbon atoms, alicyclic groups with about 5-20 carbon atoms groups, aryl groups with about 6-18 carbon atoms and alkaryl groups with about 7-24 carbon atoms, wherein these divalent or trivalent groups may contain one or more heterogeneous groups selected from O, N and S Atoms replace carbon atom(s), and each R ₁ is the same, hydrogen or 1-18 carbon atom alkyl;

(b) at least one compound (B) selected from the group consisting of p-phenylene-diamine based antiozonants and sulfur-containing organic compounds selected from the group of polymers capable of promoting cross-linking by sulfur Sulphur-cured sulfur-containing organic compounds ("sulfur accelerators"), polysulfide polymers, and mixtures of said sulfur-containing compounds.

The composition of the specific embodiment of the first aspect of the present invention has the intrinsic application property of being a surface hindered inhibitor of free radical initiated curing of polymers in the presence of gaseous molecular oxygen (i.e. oxygen present in the atmosphere), by This allows the polymer to be tack-free cured by free radical curing agents in the presence of air while maintaining the final physical properties of a conventional peroxide cure.

In a sub-aspect of the composition of the first aspect of the present invention there is provided a composition obtained by admixing the essential components thereof, namely at least one compound (A) and at least one compound (B) of the composition of the first aspect of the present invention form.

The second aspect of the present invention provides a composition, which contains the composition described in the first aspect and a free radical initiator selected from organic peroxides and azo initiators.

A specific embodiment of the second aspect of the invention The composition has the inherent application property of being a curing or crosslinking agent for polymers capable of being crosslinked by free radical initiators and capable of The curing is carried out in the presence of air (molecular oxygen) without subjecting the curing of the polymer to surface hindrance due to the presence of air, thereby providing a cured or crosslinked polymer with a surface that is substantially tack-free without the need for an intermediate step during curing. Keep the surface away from air (molecular oxygen).

A sub-aspect of the composition of the second aspect of the invention is that the composition is prepared by mixing in any order at least one compound (A) and at least one compound (B) of the composition of the first aspect of the invention with the second aspect of the invention. Aspect compositions made with free radical initiators.

In a third aspect the invention provides a curable composition comprising a polymer curable with a free radical initiator and a composition according to the second aspect of the invention.

The composition of the third aspect of the present invention has the inherent application property that it can be formed into a shaped article, which can then be cross-linked when the surface of said shaped article comes into contact with air (molecular oxygen), forming a substantially free surface. Viscous shaped cross-linked articles.

A sub-aspect of the composition of the third aspect of the present invention provides a curable composition obtained by mixing in any order at least one compound (A) and at least one compound (B) of the composition of the first aspect of the present invention with the present invention. The composition according to the second aspect of the invention is made of a free radical initiator and a polymer crosslinkable by the free radical initiator.

The first aspect of the present invention also provides a method for preparing the composition of the second aspect of the present invention, which comprises mixing at least one compound (A) and at least one compound (B) of the composition of the first aspect of the present invention and the present invention in any order. The free radical initiator of the composition of the second aspect.

The second aspect of the present invention also provides a method for preparing the composition of the third aspect of the present invention, which comprises mixing in any order at least one compound (A) and at least one compound (B) of the composition of the first aspect of the present invention, the present invention The free radical initiator and the polymer crosslinkable by the free radical initiator of the composition of the second aspect.

Special mention should be made of the embodiments of several aspects of the present invention, wherein said compound (A) is selected from bismaleimide and compound (B) is selected from sulfur accelerators; compound (A) is selected from dicitraconyl Imine and compound (B) are selected from sulfur accelerators; compound (A) is selected from bismaleimides and compound (B) is selected from polysulfide polymers; compound (A) is selected from dicitraconimides and compound (B) is selected from polysulfide polymers; compound (A) is selected from silicone elastomers and compound (B) is selected from polysulfide polymers.

Mention is also made of embodiments of several aspects of the invention wherein, in addition to compounds (A) and (B), chlorinated polyethylene and/or chlorosulfonated polyethylene are contained as optional supplementary components.

Detailed Description of the Invention

Below with reference to specific embodiment, describe in detail the best mode of preparation and use of this invention that the inventor plans, namely:

Using bispentamethylenethiuram tetrasulfide (Sufads), N,N'-m-phenylene bismaleimide (HVA-2) and 1,1-di(tert-butylperoxy)- A mixture of 3,3,5-trimethylcyclohexane (LUPEROX(R) 231XL) cured ethylene-propylene copolymer (VISTALON(R) 504) in hot air.

To prepare a mixture of Sulfads, HVA-2, and LUPEROX 231XL, the components, all in dry powder form (LUPEROX® 231XL is in the form of 40% by weight peroxide dispersed in calcium carbonate), can be mixed in any order, followed by Standard methods (Banbury, mill, extruder, etc.) were used to mix VISTALON(R) polymers. Sufads, HVA-2 and LUPEROX231XL can also be mixed directly into VISTALON simultaneously or sequentially in any order. Any two components of Sulfads, HVA-2 and LUPEROX 231XL can be mixed and mixed into VISTALON separately or simultaneously with the third component. If the mixing is done separately, the components can also be added to the polymer in any order, but the peroxide is preferably added last.

Once mixing with VISTALON is complete, the resulting mixture can be cured simply by placing it in a hot air oven at a suitable temperature. The curing is initiated by the decomposition of the peroxide, in which case it is convenient to heat the mixture at about 365°F (about 185°C). ) is cured long enough to produce the desired degree of crosslinking, in which case it is convenient, for thin samples, to initially cure at room temperature for about 10 minutes.

Those skilled in the industry will recognize that other compounds falling within the scope of formula I of the composition of the first aspect of the present invention are all solid materials, such as trimaleimide, bismaleimide, triciconazole imide or dicitraconimide, and can be mixed with other raw materials contemplated by the present invention by similar conventional methods. The bismaleimides and biscitraconimides intended to be used as starting materials are either commercially available or can be readily synthesized by methods well known in the art. See, eg, US Patent Nos. 5,484,948, 5,616,666 and 5,292,815 and references cited therein for more general synthetic methods.

Trimaleimides and tricitraconimides and higher polymaleimides and citraconimides, if not commercially available, can be prepared by similar techniques. For example, the CAS number of trimaleimide, N, N', N"-(1,3,5-triazine-2,4,6-triyl) trimaleimide is CAS (67460-81 -5).

Some primary amines suitable for the synthesis of di-, tri- and higher polymaleimides and similar citraconimides are polyfunctional primary amines such as melamine and various polyoxypropyleneamines such as polyoxypropylenedi Amines and polyoxypropylene triamines are available from Huntsman Corporation under the tradename JEFFAMINE.

In addition to the above specifically mentioned N, N'-m-phenylene-bismaleimide, other dimaleimides applicable to the present invention and not limiting the generality of the above formula (I) described in the above-mentioned patents The imides are:

N,N'-ethylene dimaleimide, N,N'-hexamethylene dimaleimide, N,N'-dodecamethylene dimaleimide, N, N'-(2,2,4-trimethylhexamethylene)bismaleimide, N,N'-(oxygen-dipropylene)bismaleimide, N,N'- (Aminodipropylene)bismaleimide, N,N'-(ethylenedioxy-dipropylene)bismaleimide, N,N'-(1,4-cyclo Hexyl) dimaleimide, N, N'-(1,3-cyclohexylene) dimaleimide, N, N'-(methylene-1,4-dicyclohexylene) di Maleimide, N, N'-(isopropylidene-1,4-dicyclohexylene) bismaleimide, N,N'-(oxygen-1,4-dicyclohexylene) Bismaleimide, N, N'-p-(phenylene) bismaleimide, N, N'-(o-phenylene) bismaleimide, N, N'- (1,3-naphthylene)bismaleimide, N,N'-(1,4-naphthylene)bismaleimide, N,N'-(1,5-naphthylene ) bismaleimide, N, N'-(3,3'-dimethyl-4,4'-phenylene) bismaleimide, N, N'-(3,3-di Chloro-4,4'-diphenylene)bismaleimide, N,N'-(2,4-pyridyl)bismaleimide, N,N'-(2,6-pyridine base) bismaleimide, N, N'-(1,4-anthraquinone group) bismaleimide, N, N'-(m-tolyl) bismaleimide, N , N'-(p-tolyl)bismaleimide, N,N'-(4,6-dimethyl-1,3-phenylene)bismaleimide, N,N' -(2,3-Dimethyl-1,4-phenylene)bismaleimide, N,N'-(4,6-dichloro-1,3-phenylene)bismaleimide Imine, N,N'-(5-chloro-1,3-phenylene)bismaleimide, N,N'-(5-hydroxy-1,3-phenylene)bismaleimide Imine, N, N'-(5-methoxy-1,3-phenylene) bismaleimide, N, N'-(m-xylylene) bismaleimide, N, N'-(p-xylylene) bismaleimide, N, N'-(methylene bis-p-phenylene) bismaleimide, N, N'-( Oxygen bis-p-phenylene) bismaleimide, N,N'-(thiobis-p-phenylene)bismaleimide, N,N'-(dithiobis- p-phenylene) bismaleimide, N,N'-(sulfobis-p-phenylene)bismaleimide, N,N'-(carbonyl bis-p-phenylene ) Dimaleimide, α, α-bis-(4-maleimidophenyl)-m-diisopropylbenzene, α,α-bis-(4-p-phenylene) di Maleimide and α,α-bis-(4-maleimidophenyl)-p-diisopropylbenzene.

Combinations of two or more bismaleimides, or bismaleimides with trimaleimides and with higher polymaleimides are also used in the compositions and methods of the present invention. These tri- and higher polymaleimides, and substitutions for these maleimides in the compounds and methods described herein for practicing the invention will be apparent to those skilled in the art, considering equivalents Equivalents are also considered within the scope of the present invention.

With reference to the above-mentioned N, N-m-phenylene bismaleimides, dicitraconimides that may be fully or partially substituted include the following representative examples:

1,2-N,N'-dimethylene dicitraconimide;

1,2-N,N'-trimethylene dicitraconimide;

1,5-N,N'-(2-methyl-pentamethylene)-dicitraconimide; and

N,N'-methylphenylene dicitraconimide.

Mixtures of biscitraconimides and mixtures of bismaleimides and biscitraconimides as well as mixtures of the above including trimaleimides are also considered equivalents of the invention.

The dicitraconimides considered are all well known compounds and, where not commercially available, they are readily synthesized by methods well specified in the art. Column 4 of US Patent 5,292,815 provides a detailed list of these methods. As mentioned above, three or higher polycitraconimides can be prepared by similar methods, and they can also be substituted in whole or in part in the composition of the present invention, and these compounds and substituents are understood by those skilled in the art, Equivalents of the compounds specified herein are also considered to be equivalents within the scope of the present invention.

Silicone elastomers considered useful in various aspects of the invention are peroxide crosslinkable dimethylvinyl substituted silicone derivative elastomers, which are well known in the art. See e.g. "Kirk Othmer Eneyclopedia of Chemical Technology", Vol. 20, p. 43-, John Wiley & Sons, @1982.

Sulfur-containing organic compounds that accelerate sulfur vulcanization of polymers are also well known in the art, and these polymers can be considered for sulfur crosslinking in the present invention. Many different types of these compounds are known, all of which are considered equivalents.

Many types are listed in "The Vanderbilt Rubber Handboot (13th Edition, 1990, R.T. Vanderbilt Company, Inc,)". Examples of these types are derivatives of benzothiazoles, thiadiazoles, sulfenamides, sulfenimides, dithiocarbamates, thiurams, imidazoles, xanthates and thioureas . Sulfur accelerators also included in this class of sulfur compounds are sulfides, disulfides (such as diallyl disulfide), polysulfides and aryl polysulfides, such as amylphenol polysulfide such as commercially available from VULTAC® products of ATOFINA Chemicals Inc., and other sulfides, such as disulfides and/or other known sulfur-promoted polysulfide phosphates, dithiophosphates, and/or phosphorus and sulfur-containing compounds . Other sulfur-containing organic compounds that are known but are not currently used in this type of reaction for cost reasons and are able to contribute sulfur at the vulcanization temperature are also considered equivalents. An example of them is the compound 2-(2,4-cyclopentadien-1-ylidene)-1,3-dithiolane.

More specifically, one class of sulfur accelerators suitable for use in the practice of this invention are the salts of disubstituted dithiocarbamic acids.

These salts have the following general structure: where X is an ion formed from a metal selected from nickel, cobalt, iron, chromium, tin, zinc, copper, lead, bismuth, cadmium, selenium, and tellurium, or X is a quaternary ammonium ion, and n can vary between 1-6 , which is equal to the positive charge on the X ion, and _R1 and _R2 are each an alkyl group of 1-7 carbon atoms.

Examples of salts of disubstituted dithiocarbamic acids are:

Bismuth dimethyldithiocarbamate;

Cadmium diethyldithiocarbamate;

Cadmium Diamyl Dithiocarbamate;

Copper dimethyldithiocarbamate;

Lead diamyl dithiocarbamate;

Lead dimethyl dithiocarbamate;

Selenium diethyldithiocarbamate;

Selenium dimethyldithiocarbamate;

Tellurium diethyldithiocarbamate;

Pentamethylenedithiocarbamate piperidinium;

Zinc Diamyl Dithiocarbamate;

Zinc diisobutyldithiocarbamate;

Zinc dimethyldithiocarbamate;

Zinc diethyldithiocarbamate;

Copper dibutyldithiocarbamate;

Sodium dimethyldithiocarbamate;

Sodium diethyldithiocarbamate;

Sodium dibutyldithiocarbamate;

Zinc di-n-butyldithiocarbamate;

Zinc dibenzyldithiocarbamate;

其中R₃是1至约7个碳原子的烷基，或每个特定氮原子上的R₃基团可以连接起来，和与它们连接的氮原子一同形成分别含有4、5或6个碳原子的5、6或7元杂环，而且n可以是0以上至高达6的正值。A second class of sulfur accelerators suitable for use in the present invention includes thiurams. They are made from secondary amines and carbon disulfide and have the general structure:

wherein _R3 is an alkyl group of 1 to about 7 carbon atoms, or the _R3 groups on each particular nitrogen atom may be linked together to form, with the nitrogen atom to which they are attached, a group containing 4, 5 or 6 carbon atoms, respectively 5, 6 or 7-membered heterocyclic ring, and n can be a positive value of 0 or more up to 6.

General examples of thiuram sulfur accelerators are:

Bispentamethylenethiuram tetrasulfide and hexasulfide;

Tetrabutylthiuram disulfide;

Tetramethylthiuram disulfide;

Tetraethylthiuram disulfide;

Tetramethylthiuram monosulfide;

Isobutylthiuram disulfide;

Dibenzylthiuram disulfide;

Tetrabenzylthiuram disulfide;

Tetraisobutylthiuram disulfide;

Isobutylthiuram monosulfide;

Dibenzylthiuram monosulfide;

Tetrabenzylthiuram monosulfide;

Tetraisobutylthiuram monosulfide.

The higher polysulfides of various thiurams are also sulfur donors.

Thiadiazole derivatives are, but are not limited to, monobenzoyl derivatives of dimercaptothiadiazole (2,5-dimethyl-1,3,4-thiadiazole); proprietary to Vanderbilt Rubber Company 1,2,4-thiadiazole, 5-ethoxy-3-(trichloromethyl)thiadiazole; and alkylmercaptothiadiazoles such as methylmercapto Thiadiazoles.

Derivatives of benzothiazole have the following general structure: wherein M is a direct bond between two sulfur atoms, H, or an ion formed from a metal selected from the group consisting of nickel, cobalt, iron, chromium, tin, zinc, copper, lead, bismuth, cadmium, selenium, and tellurium; when When M is H, x is 1; when M is a bond directly connected between two sulfur atoms, x is 1 or 2; when M is an ion formed by a metal, x is equal to the positive valence of the metal ion; if M is a direct bond between two sulfur atoms, and x is 1, then the second sulfur atom bonded to M is also bonded to 4-morpholinyl.

Exemplary compounds are:

2-(4-morpholinodithio)benzothiazole, benzothiazole disulfide, 2-mercapto-benzothiazole, 2-mercaptobenzothiazole disulfide, sodium 2-mercaptobenzothiazole (sodium-2- mercaptobenzothiazolate), 2-mercapto-benzothiazole zinc, 2-mercapto-benzothiazole copper, 2-N-cyclohexylaminobenzothiazolate, polysulfide N-cyclohexylamino-2-benzothiazole, 2-diphenyl Thiazole-2,2-polysulfide and 2-dibenzothiazole-2,2-disulfide, bis(2,2'-benzothiazolyl disulfide).

Sulfenamide accelerators are also well known. Exemplary examples are: N-oxydiethylene-2-benzothiazole sulfenamide, N-oxydiethylenethiocarbamoyl-N-oxydiethylene sulfenamide, N-cyclohexyl -2-Benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, N-cyclohexyl-2-benzothiazyl sulfenamide, N,N-dicyclohexylbenzothiazole sulfinamide, N-tert-butyl-2-benzothiazole sulfenamide. There are also sulfinimide compounds such as N-tert-butylbenzothiazole-2-sulfinimide.

General imidazoles are: 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptobenzimidazole.

Zinc isopropyl xanthate is a general xanthate sulfur accelerator.

Common thioureas are: trimethylthiourea, 1,3-diethylthiourea and 1,3-dibutylthiourea, a blend of ethylenethiourea, dialkylthiourea, diphenyl thiourea, di-o-tolylthiourea, dimethylthiourea, diethylthiourea, dibutylthiourea.

Illustrative of sulfur accelerators of the alkylphenol disulfide type are the compounds available from ATOFINA Chemicals Inc. under the tradenames VULTAC(R) 2, VULTAC3 and VULTAC5.

Examples of thiophosphate sulfur accelerators are copper dialkyldithiophosphate, zinc dialkyldithiophosphate, zinc amine dithiophosphate, zinc dibutyldithiophosphate, O,O-diiso Propyl-copper dithiophosphate, O,O-diisopropyl-zinc dithiophosphate.

Various other sulfur accelerators include 4,4-dithiodimorpholine, N,N'-caprolactam disulfide, dibutylxanthogen disulfide.

Polymers capable of curing (crosslinking) in the presence of molecular oxygen include all natural and synthetic polymers capable of crosslinking by abstraction of hydrogen (or other extractable atoms such as fluoroelastomers substituted with iodine and bromine) or by double bond polymerization thing.

At present, it is believed that the polymerization cannot be crosslinked by these mechanisms, and will degrade in the presence of free radicals generated by organic peroxides and azo initiators, which should be substantially absent in the curable compositions of the present invention. Examples include: polyvinyl chloride, polypropylene, butyl rubber, epichlorohydrin polymers, and epichlorohydrin ethylene oxide polymers. In this document and in the appended claims, when referring to suitable polymers for use in connection with the present invention, the terms "comprising", "substantially The terms "consisting of" and "consisting of" are meant to exclude more than a small amount (1% by weight or less) of non-radically cross-linked polymer.

Polymers that can be cross-linked by free radicals formed by the following organic peroxides and azo initiators include ethylene-propylene terpolymers (EPDM), ethylene-propylene copolymers (EPM), natural polyisoprene Rubber (NR), styrene-butadiene rubber (SBR), polybutadiene rubber (BR), synthetic polyisoprene rubber (IR), polyethylene (PE), ethylene-vinyl acetate (EVA ), acrylonitrile-butadiene-styrene (ABS), unsaturated polyester, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), chloroprene rubber (CR), nitrile rubber (NBR), polysulfide rubber (T), chlorinated polyethylene (CM), polyurethane (AU, EU), 1,1-difluoroethylene copolymer (CFM), silicone rubber (PMQ), vinyl silicone rubber (VMQ, PVMQ), polyacrylate (ACM), chlorosulfonated polyethylene (CSM) and fluorosilicone rubber (FVMQ).

Free radical initiators (organic peroxides and azo initiators) suitable for use in the present invention include all organic peroxide and azo initiator classes suitable for curing (crosslinking) polymers of both thermoplastics and elastomers. Initiator.

Azo initiators are known in the industry to generate free radicals capable of initiating the desired curing (crosslinking) reaction from thermal decomposition, such as 2,2'-azobis-(2-acetoxypropane ). Also suitable are the azo initiators of US Patent Nos. 3,862,107 and 4,129,531, incorporated herein by reference.

In addition to hydroperoxides and liquid peroxydicarbonates, all organic peroxides known to thermally decompose to generate free radicals capable of initiating the desired curing (crosslinking) reaction are considered suitable for use in the present invention. Dialkyl peroxides, diperoxyketals, monoperoxycarbonates, cyclic ketone peroxides, diacyl peroxides, organic sulfonyl peroxides, peroxyesters and solid, room temperature stable peroxydi Carbonates are preferred initiators. The most preferred initiators are dialkyl peroxides, peroxyketals, cyclic ketone peroxides and diacyl peroxides.

Good literature can be found in the article "Organic peroxides" by Jose Sanchez and Terry N, Myers in the "Kerke-Osmer Encyclopedia of Chemical Technology" (1996, Vol. 18, Fourth Edition), Important peroxide names and physical properties are available for all of these organic peroxide types.

Examples of dialkyl peroxide initiators are:

Di-tert-butyl peroxide;

tert-butyl cumyl peroxide;

2,5-bis(cumylperoxy)-2,5-dimethylhexane;

2,5-bis(cumylperoxy)-2,5-dimethylhexyne-3;

4-methyl-4-(tert-butylperoxy)-2-pentanol;

4-Methyl-4-(tert-amylperoxy)-2-pentanol;

4-Methyl-4-(cumylperoxy)-2-pentanol;

4-methyl-4-(tert-butylperoxy)-2-pentanone;

4-Methyl-4-(tert-amylperoxy)-2-pentanone;

4-Methyl-4-(cumylperoxy)-2-pentanone;

2,5-Dimethyl-2,5-bis(tert-butylperoxy)hexane;

2,5-Dimethyl-2,5-bis(tert-amylperoxy)hexane;

2,5-Dimethyl-2,5-bis(tert-butylperoxy)hexyne-3;

2,5-Dimethyl-2,5-bis(tert-amylperoxy)hexyne-3;

2,5-Dimethyl-2-tert-butylperoxy-5-hydroperoxyhexane;

2,5-Dimethyl-2-cumylperoxy-5-hydroperoxyhexane;

2,5-Dimethyl-2-tert-amylperoxy-5-hydroperoxyhexane;

m/p-α,α-bis[(tert-butylperoxy)-isopropyl]benzene;

1,3,5-tris(tert-butylperoxyisopropyl)benzene;

1,3,5-tris(tert-amylperoxyisopropyl)benzene;

1,3,5-tris(cumylperoxyisopropyl)benzene;

Bis[1,3-dimethyl-3-(tert-butylperoxy)butyl]carbonate;

Bis[1,3-dimethyl-3-(tert-amylperoxy)butyl]carbonate;

Bis[1,3-dimethyl-3-(cumylperoxy)butyl]carbonate;

Di-tert-amyl-peroxide;

tert-amylcumyl peroxide;

2,4,6-tri(butylperoxy)-S-triazine (2,4,6-tri(butylperoxy)-s-triazine);

1,3,5-tris[1-(tert-butylperoxy)-1-methylethyl]benzene;

1,3,5-tris-[(tert-butylperoxy)-isopropyl]benzene;

1,3-Dimethyl-3-(tert-butylperoxy)butanol;

1,3-Dimethyl-3-(t-amylperoxy)butanol, and mixtures thereof.

Exemplary solid, room temperature stable peroxydicarbonates are, but are not limited to:

Bis(2-phenoxyethyl)peroxydicarbonate; bis(4-tert-butylcyclohexyl)peroxydicarbonate; dimyristyl peroxydicarbonate; dibenzyl peroxydicarbonate; bis( isobornyl) peroxydicarbonate.

其中R₄和R₅可以各自在间位或对位上，可以相同或不同，而且选自氢或1-6个碳原子的直链或支链烷基。二枯基过氧化物和异丙基枯基枯基过氧化物是示范性例子。Another preferred class of dialkyl peroxides which may be used alone or in combination with other free radical initiators contemplated by the present invention are selected from the compounds represented by the formula:

Wherein R ₄ and R ₅ can each be at the meta-position or para-position, can be the same or different, and are selected from hydrogen or straight-chain or branched-chain alkyl groups with 1-6 carbon atoms. Dicumyl peroxide and isopropyl cumyl peroxide are illustrative examples.

Other dialkyl peroxides are:

3-cumylperoxy-1,3-dimethylbutyl methacrylate;

3-tert-butylperoxy-1,3-dimethylbutyl methacrylate;

3-tert-amylperoxy-1,3-dimethylbutyl methacrylate;

Tris(1,3-dimethyl-3-tert-butylperoxybutoxy)vinylsilane;

1,3-Dimethyl-3-(tert-butylperoxy)butyl N-[1-{3-(1-methylvinyl)-phenyl}-1-methylethyl]carbamate ester;

1,3-Dimethyl-3-(tert-amylperoxy)butyl N-[1-{3-(1-methylvinyl)-phenyl}-1-methylethyl]carbamate ester;

1,3-Dimethyl-3-(cumylperoxy)butyl N-[1-{3-(1-methylvinyl)-phenyl}-1-methylethyl]carbamate .

Within the group of diperoxyketal initiators, the preferred initiators are:

1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane;

1,1-bis(tert-butylperoxy)cyclohexane;

4,4-Di(tert-amylperoxy)pentanoic acid n-butyl ester;

3,3-Di(tert-butylperoxy)ethyl butyrate;

2,2-bis(tert-amylperoxy)propane;

3,6,6,9,9-pentamethyl-3-ethoxycarbonylmethyl-1,2,4,5-tetraoxacyclononane;

4,4-Di(tert-butylperoxy)-n-butyl valerate;

ethyl 3,3-bis(tert-amylperoxy)butyrate; and mixtures thereof.

Other peroxides falling into the general class described herein include benzoyl peroxide; OO-tert-butyl-O-hydro-monoperoxy-succinate and OO-tert-amyl-O-hydro- Monoperoxy-succinate.

(II)

(III)(IV)其中R₁-R₁₀各自选自氢、C₁-C₂₀烷基、C₃-C₂₀环烷基、C₆-C₂₀芳基、C₇-C₂₀芳烷基和C₇-C₂₀烷芳基，这些基团可以包括线型或支链烷基，而且每个R₁-R₁₀可以用一个或多个选自羟基、C₁-C₂₀烷氧基、线型或支链C₁-C₂₀烷基、C₆-C₂₀芳氧基、卤原子、酯、羧基、氮化物和酰胺基的基团取代，用于交联反应的过氧化物混合物的活性氧总量中优选至少20％来自于具有式(II)、(III)和/或(IV)的化合物。Exemplary cyclic ketone peroxides are compounds having the following general formulas (II), (III) and/or (IV).

(II)

(III) (IV) wherein R ₁ -R ₁₀ are each selected from hydrogen, C ₁ -C ₂₀ alkyl, C ₃ -C ₂₀ cycloalkyl, C ₆ -C ₂₀ aryl, C ₇ -C ₂₀ aralkyl and C ₇ -C ₂₀ alkaryl, these groups can include linear or branched chain alkyl, and each R ₁ -R ₁₀ can be selected from one or more of hydroxyl, C ₁ -C ₂₀ alkoxy, linear or Branched C ₁ -C ₂₀ alkyl group, C ₆ -C ₂₀ aryloxy group, halogen atom, ester, carboxyl group, nitride and amido group substitution, the total amount of active oxygen in the peroxide mixture used for crosslinking reaction Preferably at least 20% of the amount originates from compounds of formula (II), (III) and/or (IV).

Some examples of suitable cyclic ketone peroxides are:

3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane (or methyl ethyl ketone peroxide cyclic trimer) and methyl Ethyl ketone peroxide cyclic dimer;

3,3,6,6,9,9-hexamethyl-1,2,4,5-tetraoxacyclononane (tetraoxacyclononane);

Examples of suitable peroxyesters are:

2,5-Dimethyl-2,5-di(benzoylperoxy)hexane;

tert-butyl perbenzoate;

tert-butyl peracetate;

tert-butylperoxy-2-ethylhexanoate;

tert-amyl perbenzoate;

tert-amyl peracetate;

Tert-butyl perisobutyrate;

3-Hydroxy-1,1-dimethyl-tert-butylperoxy-2-ethylhexanoate;

OO-tert-amyl-O-hydrogen-monoperoxysuccinate;

OO-tert-butyl-O-hydrogen-monoperoxysuccinate;

Di-tert-butyl diperoxyphthalate;

tert-butylperoxy (3,3,5-trimethylhexanoate);

1,4-bis(tert-butylperoxycarbonyl)cyclohexane;

tert-butylperoxy-3,5,5-trimethylhexanoate;

tert-butylperoxy-(cis-3-carboxy)propionate;

Allyl 3-methyl-3-tert-butylperoxybutyrate.

Examples of monoperoxycarbonates are:

OO-tert-butyl-O-isopropyl monoperoxycarbonate;

OO-tert-butyl-O-(2-ethylhexyl) monoperoxycarbonate;

1,1,1-tris[2-(tert-butylperoxy-carbonyloxy)ethoxymethyl]propane;

1,1,1-tris[2-(tert-amylperoxy-carbonyloxy)ethoxymethyl]propane;

1,1,1-tris[2-(cumylperoxy-carbonyloxy)ethoxymethyl]propane;

OO-tert-amyl-O-isopropyl monoperoxycarbonate;

Examples of diacyl peroxides are:

Bis(4-methylbenzoyl) peroxide;

Bis(3-methylbenzoyl) peroxide;

Bis(2-methylbenzoyl) peroxide;

Dicaproyl peroxide; Dilauroyl peroxide;

2,4-dibromo-benzoyl peroxide;

Succinic acid peroxide;

Dibenzoyl peroxide;

Bis(2,4-dichloro-benzoyl) peroxide.

The types of iminoperoxides described in PCT Patent Application WO9703961A1 (February 6, 1997) are also considered suitable for use in the present invention.

Those skilled in the art can easily select various suitable components for the present invention, and through a series of small-scale experiments, in the polymer sample to be cured (crosslinked), increase the component content, just can Concentrations are quickly and easily optimized. The optimum processing (mixing) time and temperature, etc. can also be determined from the same test as the optimum curing time and temperature.

Generally, the compound of formula (a) (bismaleimide and dicitraconimide) is used in the composition of the present invention, and the consumption is about 0.2-10.0 parts (weight), based on 100 parts (weight) of polymer Basis (phr), preferably about 1.0-5.0 phr, most preferably about 1.5-3.0 phr.

Sulfur-containing organic compounds capable of promoting sulfur vulcanization of polymers crosslinkable by sulfur are generally employed in the compositions of the present invention. The amount used is about 0.01-20 phr, preferably about 0.1-1.0 phr, most preferably about 0.1-0.5 phr. Those skilled in the art will understand that these compounds are of two types. These are compounds that contribute sulfur to vulcanization and compounds that only promote sulfur vulcanization. Each class of compounds or mixtures thereof are considered equivalents of the present invention.

Alkylphenol disulfide polymers of the VULTAC(R) type are preferably used in amounts of about 0.5-20 phr when used alone or in combination with other sulfur accelerators in amounts of about 0.1-10 phr.

Generally, free radical initiators (organic peroxides and/or azo initiators) are used in an amount of about 0.04-10 phr, preferably about 1-4 phr.

The time-temperature conditions required for curing depend greatly on the structure of the free radical curing agent. For azo initiators, suitable conditions are described in US Pat. Nos. 3,632,107 and 4,129,531.

For the compositions of the present invention, suitable time and temperature conditions for crosslinking a particular polymer composition can be determined by performing a small number of well-controlled rheological studies, and selecting values from the results of these studies, where time/temperature The relationship is 5-15 times the half-life of the free radical initiator in this system.

Other conventional additives such as antioxidants (preferably hindered phenol and quinoline derivative polymers), aliphatic processing oils and other processing aids, pigments, dyes, tackifiers, waxes, reinforcing agents, UV Stabilizers, blowing agents, activators and antiozonants may also be present in the composition during and before and after the curing step.

The polysulfide polymers contemplated by the present invention are known polysulfide polymers prepared by reaction of α,ω-dihaloalkyl (or dihaloheteroalkyl) compounds with metal, preferably alkali metal polysulfides. Common commercially available polysulfide polymers are liquid or solid, thiol- or hydroxyl-terminated, derived from 1,2-dichloroethane, 2,2′-dichloro-diethyl ether or bis(2- Chloroethyl) formal and alkali metal polysulfide (MSxx _x ), M in MSxx _x is an alkali metal ion, preferably formed by sodium, and x is a number of 1 or more up to about 6.

The present invention contemplates that polysulfide polymers may be used instead of or mixed with other compounds (B) in amounts equal to the aforementioned amounts of these compounds. Since it is believed that excess polysulfide polymers are not detrimental to the practice of the present invention, it is also contemplated that they may be preformed with compound (A)(s) and optionally with free radical initiator(s). Mix to form solid or liquid masterbatches. The polysulfide polymer may also be premixed into the polymer to be cured, and the operator may also choose to mix compound (A)(s) and free radical initiator(s) simultaneously or subsequently. The use of polysulfide polymers in combination with other sulfur accelerators contemplated by the present invention reduces the amount of sulfur accelerator required for the present invention.

Similarly, it will be understood by those skilled in the art that if compound (A) is present in a curable composition, even if the other compound (B) is not present, the polysulfide polymer itself will be freed in the presence of molecular oxygen. The base initiator cures to a tack-free surface. Accordingly, the present invention considers such curable compositions to be equivalent to the compositions described in the second aspect of the present invention.

Crosslinkable elastomeric compositions filled with high amounts of oil and/or carbon black (commonly referred to as high compatibilization elastomeric formulations) are usually cured with sulfur vulcanization rather than free radical initiators. Free radical curing is more difficult because the free radicals formed are less specific and react with fillers and oils as well as with elastomers. This reduces the efficiency of the free radical initiator.

It has been found that the use of chlorinated polyethylene and/or chlorosulfonated polyethylene as a supplementary component of the compositions of various aspects of the present invention unexpectedly increases the efficiency of free radical cure in highly compatibilized elastomer formulations and makes free radical cure systems Reduced or no stickiness on the surface. The amount of chlorinated and/or chlorosulfonated polyethylene used as a supplementary component in the composition of the first aspect of the present invention may be about 1-50% by weight, preferably 15-40% by weight, more preferably 20% by weight. -35% by weight.

In some cases, in the formulation of the composition of the second aspect of the present invention, the use concentration of the composition of the first aspect of the present invention can be reduced by including such two polymers as supplementary components.

The following examples further illustrate the best mode of carrying out the invention contemplated by the inventors and are to be construed as exemplary and not as limiting.

Example

Example 1

Evaluation of prior art compositions for crosslinking EPM in the presence of air and its effect on surface tack and degree of crosslinking

In this example, various known curing aids in curing with organic peroxides, such as crosslinking aids for unsaturated monomers, elemental sulfur or sulfur donating compounds, were evaluated. The elastomer used in this example was an ethylene-propylene copolymer (EPM) available under the tradename Exxon VISTALON(R) 504. The prior art (US Pat. No. 4,983,685) claims the use of high levels (2.5-20 parts) of specific sulfur-containing compounds, with or without optional unsaturated monomers, for transfection with peroxides in the presence of air. Combines with elastomers and creates a non-stick surface. Other references use sulfur. In this example, low sulfur or sulfur donating compounds were evaluated alone or in the presence of some monomer builders. The data in Table 1 illustrate that these formulations form tacky surfaces, but also form cross-linked products with superior physical properties (higher M _H torque). Mixtures of optional monomer builders, high levels of sulfur compounds and peroxides (as taught by the prior art) were also evaluated. When the elastomer was crosslinked in the presence of air, it formed a non-tacky surface, but the physical properties were unacceptable compared to conventional peroxide monomer crosslinked formulations.

In the Table 1 formulations, standard carbon black formulations were used. Carbon black (N774), Sunpar(R) LW150 processing oil from Sun, zinc oxide, antioxidant (AgeRite MA) were mixed into the EPM. Additionally, all formulations contained 8 parts of 40% organic peroxyketal peroxide, LUPEROX® 231XL [40% 1,1-di(butyl peroxide) dispersed on calcium carbonate sold by ATOFINA Chemicals Inc. Oxygen)-3,3,5-trimethylcyclohexane]. The degree of crosslinking was determined using a Flexsys MDR(R) 2000E live mold rheometer. The samples were also cured in hot air at 365°F for 10 minutes. Immediately after removal from the oven, surface tack was judged by placing a paper towel on the surface with moderate and consistent pressure. Surface stickiness is divided into 1-10 grades, 1: no stickiness, 10: very sticky.

Compositions of peroxide and 0.3 phr (typical EPM cure) of low elemental sulfur (Table 1, entry 1) give a good level of crosslinking (according to M _H ), but are sticky on the surface when cured in hot air . 2 parts HVA-2 (N,N'-phenylene bismaleimide, sold by DuPont) was used in combination with peroxide (Table 1, entry 2) to form the desired level of increased crosslinking (according to M _H ), but unfortunately the surface is sticky, which is poor. Note: 1 part of antioxidant AgeRite MA (polymerized quinoline sold by RTVanderbilt) was used in each case, which is a standard level not to affect the surface. Compositions of 0.3 parts elemental sulfur with 2 parts HVA-2 (Table 1, entry 5) resulted in a further increased level of crosslinking (compared to entry 2 using only HVA-2), but unfortunately also high Surface tackiness (7 out of 10). Thus, mixtures of additives with low levels of elemental sulfur can improve crosslinking, but not surface adhesion. The prior art suggests that 2.5-20 parts of sulfur accelerator or its equivalent is required. The use of HVA-2 additives with peroxides in carbon black EPM formulations containing oils and antioxidants results in good crosslinks when cured in hot air, but unfortunately also a sticky surface. The use of 4 parts monomeric additive SR-350(R) with 0.3 parts elemental sulfur resulted in the highest level of crosslinking, but poor surface tack (see Table 1, entry 4). SR-350 is trimethylolpropane trimethacrylate, sold by Sartomer.

No. 3 in Table 1, 1.2 parts of Sulfads(R) combined with peroxide, gave unacceptable surface tack, 6 out of 10, and poor grade cure, according to _MH . Sufads are 98% bispentamethylenethiuram tetrasulfide, sold by RTVanderbilt; therefore, the actual amount of bispentamethylenethiuram tetrasulfide added is 1.2 x 0.98-1.18 parts. Finally, 1.2 parts of Sulfads combined with 2 parts of HVA-2 and peroxide gives a good surface when cured in the presence of air, unfortunately the physical properties of the desired crosslinking are reduced, as are the resulting low M _H values shown.

This example illustrates that different curing aids such as peroxides, monomeric aids and elemental or sulfur-containing sulfur are not predictable when cured in the presence of air with the objective of maintaining acceptable levels of crosslinking while maintaining low surface tack The mixing effect of compounds. It can be assumed that if the overall level of crosslinking can be increased with various additives and peroxides, then, in the presence of air, the surface adhesion can be improved. However, our data show that curing in the presence of air increases the level of crosslinking without simultaneously improving surface tack.

In addition, overall crosslinking was found to be poor when the surface tack was eventually reduced using the teachings of the prior art. Crosslinking within the sample (excluding air) and surface crosslinking in the presence of air are two separate procedures. Increasing or decreasing the amount of crosslinking aid, or combining different curing aids with peroxides can lead to unpredictable results. Crosslinking aids such as HVA-2 help increase the level of crosslinking for peroxide cure, but, cure in air, give poor surface tack. When using monomeric additives, HVA-2 or SR350 in combination with other curing additives such as elemental sulfur or sulfur donor/accelerator compounds, as described in the prior art, we have found that the final physical properties drop significantly, Therefore, the advantages of monomeric additive-peroxide curing system are negated.

Table 1 serial number 1 2 3 4 5 6 VISTALON® 504EPM elastomer 100 100 100 100 100 100 The following components (Phr) are added in parts (by weight) based on 100 parts of rubber, that is, no correction is required for the determination. N774(phf) carbon black 75 75 75 75 75 75 LW150 oil (phr) 10 10 10 10 10 10 ZnO(phr) 5 5 5 5 5 5 AgeRite MA (Antioxidant) 1 1 1 1 1 1 LUPEROX® 231XL 40% peroxide 8 8 8 8 8 8 SR-350® (phr) - - - 4.0 - - HVA-2 - 2.0 - - 2.0 2.0 sulfur 0.3 - - 0.3 0.3 - Sulfads® (98%) - - 1.2 - - 1.2 150°C cross-linking, MDR2000E living mold rheometer M _H (inch-lbs) 29 39 20 44 43 29 Cure in hot air at 365°F for 10 minutes to determine surface tack Surface tack ^* 7 7 6 10 7 1

^* Surface stickiness rating: 1-10, 10 is very sticky and 1 is not sticky.

Example 2

Comparison of prior art peroxide formulation blends and novel peroxide formulation blends for crosslinked fully saturated (no double bonds within the polymer chain) elastomers

When crosslinked in the presence of air, the novel peroxide formulations form good physical properties typical of conventional peroxide cures, and unexpectedly non-tacky surfaces.

In this example, 40% of the assay dicumyl peroxide dispersed on the clay was used to crosslink EPM (polyethylene propylene copolymer), VISTALON(R) 707 (Exxon). Entry 1 in Table 2 evaluates mixtures of dicumyl peroxide and SR206 (ethylene glycol dimethacrylate) crosslinked in MDR for % compression set and surface tack cured in hot air. To illustrate: the prior art (US Pat. No. 4,983,685) uses SR206 as an optional monomer auxiliary in the examples. This peroxide and additive mixture gave good cure (M _H ) and % compression set when cured in hot air at 400°F, and the surface was tacky. The prior art claims that the addition of 2.5 parts of Sulfads® (98% bispentamethylenethiuram tetrasulfide) to the peroxide SR206 mixture improves the surface, but compromises the overall % compression set, numbered in Table 2 2.

No. 4 in Table 2 uses a mixture of 0.8 parts Sulfads with optional 2.2 parts HVA-2 additive, 5 parts DC40 as described in the prior art US Patent 4983685 specification to form a good surface but poor % compression set. To clarify: Sulfur vulcanization rather than peroxide crosslinking can be expected to achieve compression set values of 100-60%.

No. 3 in Table 2, 5 parts of Vanox ZMTI (93% zinc 2-mercapto-toluimidazole) with optional SR-206 additive as suggested by the prior art improves compression set but forms unacceptable large sticky surface.

Unexpectedly, the low content of bispentamethylene thiuram tetrasulfide No. 5 in Table 2 (0.4 parts content does not fall into the scope of US Patent 4983685), 0.4 parts of Durax (98% N-cyclohexyl-2-benzothiazole sulfenamide) and 5 parts of DC40 (40% dicumyl peroxide), when cured in a hot air oven, formed a tack-free surface with an improved 41% compression set and better crosslinking ratings.

Number 6 in Table 2 shows, unexpectedly, 0.4 parts Durax, 0.4 parts Vanax A (98% 4,4'-dithiodimorpholine), 2.2 parts HVA-2 (monomer builder) and 5 parts DC40 (40% dicumyl peroxide), forming a tack-free surface with 31% compression set. There is no suggestion in the prior art to use Durax and/or Vanax A with peroxide and bismaleimide type additives for curing elastomers in hot air. No. 7 in Table 2, using 0.8 parts of Durax instead of the Durax/Vanax mixture, gave a more surprisingly good compression set of 21% and a tack-free surface when cured in hot air at 400°F.

The last number 8 in Table 2 gave surprisingly good results with a new blend of 2.2 parts HVA-2, 0.4 parts VULTAC5, 0.4 parts Durax and 5 parts DC40, excellent non-stick surface and a very good very low 18% Compression set. The prior art does not suggest the use of VULTAC5 (75% alkylphenol disulfide polymer, ex Elf Atochem) for hot air curing of elastomers with peroxide and bismaleimide type co-agents. To clarify: Since the analysis is 75%, 0.4 parts of VULTAC5 is equivalent to adding 0.3 parts of the alkylphenol disulfide polymer.

This example demonstrates that prior art formulations using a mixture of peroxide and high levels of selected compounds such as bispentamethylenethiuram tetrasulfide with optional monomeric builders result in virtually non-stick surfaces, However, the final physical properties of crosslinked elastomers are poor. For peroxide cured formulations, the use of 0.8 phr of the preferred compound of thiuram as taught in prior art US Patent 4,983,685, but less than the claimed 2.5-20 phr, results in crosslinked elastomers with poor heat aging properties.

High compression set values of 60%+ indicate that prior art crosslinked polymers can set permanently under applied pressure at 150°C for 70 hours, which is a standard test for peroxide cure (ASTM D-395-61) . For unsaturated polymers, tack-free surfaces can be obtained by sulfur vulcanization in hot air, but poor heat aging properties result. If there is no significant difference in physical properties such as low M _H and/or high (poor) percent compression set values, then there is no advantage for a peroxide cure system cured in hot air compared to sulfur vulcanization. Traditionally, peroxide cure has been chosen for most high temperature and high performance applications. Peroxide crosslinks form carbon-carbon bonds, which allow manufacturers of crosslinked polymers to exploit the full range of elastomer engineering capabilities.

Table 2 serial number 1 2 3 4 5 6 7 8 VISTALON707EPM 100 100 100 100 100 100 100 100 The following components are added in parts (by weight) (phr) based on 100 parts of rubber, ie no correction is required for the determination. N774(phr) carbon black 75 75 75 75 75 75 75 75 LW150 processing oil (phr) 30 30 30 30 30 30 30 30 ZnO 5 5 5 5 5 5 5 5 stearic acid 1 1 1 1 1 1 1 1 AgeRite MA 1 1 1 1 1 1 1 1 DC40 8.0 8.0 8.0 5.0 5.0 5.0 5.0 5.0 SR-206 2.0 2.0 2.0 - - - - - HVA-2 - - - 2.2 2.2 2.2 2.2 2.2 Sulfads (98%) - 2.5 - 0.8 0.4 - - - ZMTI (93%) - - 5.0 - - - - - Vanax A (98%) - - - - - 0.4 - - VULTAC5 (75%) - - - - - - - 0.4 Durax (98%) - - - - 0.4 0.4 0.8 0.4 170℃MDR curing M _H (inch-lbs) 17 9 16 17 18 17 16 16 T _S1 min 1.04 1.56 1.06 1.20 1.11 0.61 0.58 0.63 T _C90 minutes 5.8 7.5 5.5 6.6 5.2 5.9 4.1 4.2 Cure in air at 400°F for 12 minutes surface 10 1.5 7 1.5 2 2.5 2.5 2 Compression set at 150°C for 70 hours Compression set% 25 100 35 63 41 31 twenty one 18

Example 3

The novel peroxide-additive compositions form crosslinked elastomeric solids or foams with excellent physical properties such as percent compression set in hot air, while also forming tack-free surfaces when cured in the presence of air.

The elastomer used in this example was Uniroyal(R) X3378 EPDM containing 4% dicyclopentadiene as the third monomer. Peroximon DC40KEP (40% dicumyl peroxide on clay) was used as a peroxide crosslinker. In this example, Sulfads® (98% bispentamethylenethiuram tetrasulfide), VULTAC® 5 (75% alkylphenol disulfide polymer) and Durax® (98% N-cyclohexyl- 2-benzothiazole sulfenamide) content, keep peroxide and HVA-2 auxiliary agent constant (table 3, number 2-6).

To explain: adding 0.5 parts (phr) Sulfads is equivalent to 0.49 parts of bispentamethylene thiuram tetrasulfide, based on 100 parts of rubber. Referring to Nos. 2, 3, 4, it was surprisingly found that when using less than 0.5 phr (based on pure product) bispentamethylene thiuram tetrasulfide with HVA-2 and peroxide, it has excellent compression permanent Deformable and non-stick surfaces.

When varying the concentrations of Sulfads (98% bispentamethylenethiuram tetrasulfide), VULTAC5 and Durax, it was unexpectedly found that a cross-linked elastomeric solid could be formed by hot air curing using our novel peroxide/additive composition and foam materials. When less than 0.5 phr of pure bispentamethylenethiuram tetrasulfide is used together with VULTAC5 or Durax, cross-linked elastomeric foams with non-stick surfaces are obtained, see Table 3, No. 2, 3 and 4. Use of VULTAC5 or a mixture of VULTAC5 and Durax resulted in the formation of cross-linked EPDM solids, numbers 5 and 6 in Table 3. In each case (entries 2-6 in Table 2), surprisingly good % compression set values were obtained, practically equivalent to the conventional peroxide cure, entry 1 in Table 2.

Sulfur vulcanization compression set is measured at temperatures around 100-120°C and rarely measured at 150°C because performance is often poor at high temperatures. The currently better 150°C, 70 hour compression set values demonstrate that these novel peroxide-additive compositions shown in the practice of this invention can form crosslinked EPDMs with surprisingly good heat aging properties. In addition, novel peroxide-additive compositions unexpectedly provide methods for forming solid and foam articles.

While not wanting to be bound, it is believed that in the early stages of cure, the faster scorch times associated with the creation of an unexpected crosslinked network are faster than gas evolution from the curing system to form a solid cured article, unlike closed molds. The low pressure conditions in the oven are more difficult. When the scorch time is delayed, gas evolution occurs simultaneously with the formation of a crosslinked network. Furthermore, in addition to these unexpected processing and technical advantages, these novel peroxide formulations also form completely tack-free surfaces when cured in the presence of air.

table 3 serial number 1 2 3 4 5 6 Uniroyal X3378 EPM 100 100 100 100 100 100 The following components are added in parts (by weight) (phr) based on 100 parts of rubber, ie no correction is required for the determination. N774 carbon black 100 100 100 100 100 100 Sunpar 2280 oil 30 30 30 30 30 30 ZnO 4 4 4 4 4 4 stearic acid 0.5 0.5 0.5 0.5 0.5 0.5 Age Rite D 1 1 1 1 1 1 DC40KEP40% Dicumyl Peroxide 8.0 5.2 5.2 5.2 5.2 5.2 HVA-2 - 2.0 2.0 2.0 2.0 2.0 Sulfads (98%) - 0.5 0.3 0.3 - - VULTAC5 (75%) - - - 0.5 0.8 0.5 Durax (98%) - 0.3 0.5 - - 0.3 170℃MDR M _H (inch-lbs) twenty four 30 30 31 32 31 T _S1 min 0.53 0.83 0.76 0.69 0.55 0.54 T _C90 minutes 7.9 5.9 5.6 5.5 4.9 4.7 Compression set at 150℃ for 70 hours Compression set% twenty one 30 twenty four 27 twenty two 19 Cured in air at 400°F for 10 minutes surface 10 1 1 1 1 1 Deflation none have have have none none

Example 4

Novel peroxide-additive combinations were investigated using a fast curing, higher ethylene EPDM (Royalene 509EPDM) using dicumyl peroxides and HVA-2 from Table 4

The prior art formulations (No. 2 and 3 in Table 4) formed a good surface after hot air curing, but unfortunately the 150°C/70hr compression set physical properties were poor and gave off a bad odor . These 61% and 71% compression set values are similar to those obtainable with sulfur vulcanization, but not peroxide cure. Additionally, Prior Art Samples #2 and 3# used 2.5 parts Sulfads(R), which trapped a large number of air bubbles in the center of the cured article, which was considered an unacceptable cure defect.

In contrast, all samples (Nos. 5-12) using the novel peroxide-additive compositions taught by the present invention give excellent physical properties, i.e. very low 150°C/70 hour compression set, compared to the samples using peroxides. The control reaction, without auxiliaries or sulfur addition (No. 1 in Table 1), was very similar. In this control reaction, a compression set of 15% was obtained despite the hot air cure having a very tacky surface (10 out of 10). Mixtures of HVA-2 additives with peroxide (code 4) and antioxidant AgeRite D (generally added as standard practice in rubber formulations) give good compression permanent at reduced 120°C/70h test temperature Distortion values, but unfortunately the surface is poor (7 out of 10) when crosslinked in the presence of air. All of the samples Nos. 5-12 included in the present invention, when cured in the presence of air, gave the excellent physical properties of a peroxide cure with a non-tacky surface.

Table 4 1 2 3 4 5 6 7 8 9 10 11 12 Royalene521EPDM 100 100 100 100 100 100 100 100 100 100 100 100 The following components are added in parts (by weight) (phr) based on 100 parts of rubber, ie no correction is required for the determination. N550 50 50 50 50 50 50 50 50 50 50 50 50 N990 25 25 25 25 25 25 25 25 25 25 25 25 LW150 oil 20 20 20 20 20 20 20 20 20 20 20 20 ZnO 4 4 4 4 4 4 4 4 4 4 4 4 stearic acid 1 1 1 1 1 1 1 1 1 1 1 1 Age Rite D 1 1 1 1 1 1 1 1 1 1 1 1 DC40KEP40% 7.2 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 HVA-2 - 2.2 - 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 SR-206 - - 2.2 - - - - - - - - - Sulfads98% - 2.5 2.5 - 0.5 0.3 0.3 - 0.3 0.3 0.3 0.3 Vanax A98% - - - - - - - 0.3 - - - - M. Tuads 98% - - - - - 0.2 - - - - - - Durax98% - - - - - - 0.2 0.2 - - - - Unads98% - - - - - - - - 0.2 - - - M.Zimate98% - - - - - - - - - 0.2 - - M.Niclate98% - - - - - - - - - - 0.2 - M.Cumate98% - - - - - - - - - - - 0.2 170°C, 1° radian MDR M _H 39 43 27 45 40 38 40 42 38 38 41 37 T _S1 0.45 0.68 0.75 0.38 0.60 0.62 0.58 0.42 0.65 0.46 0.56 0.53 T _C90 7.1 4.3 2.5 4.6 4.8 5.3 4.6 4.9 4.8 5.1 4.8 5.2 Cured in air at 400°F for 12 minutes surface 10 1 1 7 1 1 1 1 1 1 1 1 Compression set% at 120℃ for 70 hours Compression set% 11 46 - 8 16 18 14 - 15 - - - Compression set% at 150℃ for 70 hours Compression set% 15 61 71 - - - 19 17 - twenty one 17 twenty one

Example 5

For a generic type of additive that uniquely uses bismaleimide additives with selected additives to provide overall good peroxide type physical properties and the ability to cure rubber surfaces in the presence of air (non-tacky surfaces) evaluation of

Bismaleimides were evaluated in combination with Sulfads(R) and VULTAC(R) 5, used with dicumyl peroxide to crosslink a fast cure type EPDM (Royalene(R) 509 EPDM).

The prior art suggests the use of various coagents, both monomeric and non-monomeric types, to increase crosslinking efficiency, but independently of their action on exposure to air. We found that using these different additives only made it possible to increase the reaction with oxygen and make the rubber surface more sticky after curing in the presence of air compared to the bismaleimide type.

In Table 5, a mixture of HVA-2 (bismaleimide type of additive) together with 0.3 parts of Sulfads and 0.2 parts of VULTAC5 resulted in a non-tacky surface. The use of other additives will form a sticky surface, such as TAC (triallyl cyanurate), SR-350 (trimethylolpropane trimethacrylate), 1.2BR (1,2 liquid butadiene rubber), Santolink XI-100 (allyl glycidyl ether alcohol resin), TAP (triallyl phosphate) and pBQ (p-benzoquinone).

table 5 serial number 1 2 3 4 5 6 7 8 9 Royalene509EPDM 100 100 100 100 100 100 100 100 100 The following components are added in parts (by weight) (phr) based on 100 parts of rubber, ie no correction is required for the determination. N550 50 50 50 50 50 50 50 50 50 N990 25 25 25 25 25 25 25 25 25 LW150 oil 20 20 20 20 20 20 20 20 20 ZnO 4 4 4 4 4 4 4 4 4 stearic acid 1 1 1 1 1 1 1 1 1 Age Rite D 1 1 1 1 1 1 1 1 1 DC40KEP 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 Sulfads98% - 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 VULTAC5 98% - 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 HVA-2 - - 2.0 - - - - - - TAC - - - 3.0 - - - - - SR-350 - - - - 4.0 - - - - 1,2BR - - - - - 6.0 - - - Santolink XI-10 - - - - - - 4.0 - - TAP - - - - - - - 4.0 - QUR - - - - - - - - 1.0 170℃MDR curing M _H inch-pound 32 27 42 26 32 27 19 twenty three twenty two T _C90 minutes 7.7 6.6 4.5 7.6 6.7 8.2 7.0 7.2 9.5 Curing in air at 200°C surface 10 4 1 7 7 4 4 4 4

Example 6

Mixtures of prior art low sulfur accelerators with HVA-2 and dicumyl peroxide did not result in a tack-free surface. When crosslinking fast curing EPDM (Royalene(R) 509) in the presence of air using prior art low level compounds with selected compounds of HVA-2, a non-tacky surface was unexpectedly formed.

Can form poor cure when using 0.2 parts of Methyl Zimate (98% zinc dimethyldithiocarbamate) or 0.2 parts of Unads (98% tetramethylthiuram monosulfide) with HVA-2 in the presence of air surface (sticky surface). Therefore, the combination of very low levels of prior art compounds with HVA-2 (N,N'-phenylene bismaleimide) additives and peroxides crosslinks the elastomer in the presence of air to form The non-stick surface is not noticeable.

When VULTAC® 5 (75% alkylphenol disulfide polymer) or Vanax® A (98% 4,4'-dithiodimorpholine) was mixed with these prior art low content compounds such as Methyl Zimate or Unads , when crosslinked in the presence of air, a tack-free surface is unexpectedly obtained.

Thus, peroxides, HVA-2 additives and low levels of dithiocarbamate or unique blends of thiurams with VULTAC5 or VanaxA form surface-cured crosslinked polymers in the presence of air. In addition, it was noted that no air bubbles were generated, so solid crosslinked parts could be formed with these novel mixtures.

Table 6 serial number 1 2 3 4 5 6 7 8 9 Royalene509EPDM 100 100 100 100 100 100 100 100 100 The following components are added in parts (by weight) (phr) based on 100 parts of rubber, ie no correction is required for the determination. N774 75 75 75 75 75 75 75 75 75 Sunpar 2280 oil 20 20 20 20 20 20 20 20 20 ZnO 5 5 5 5 5 5 5 5 5 stearic acid 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 DC40KEP40% 7.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 HVA-2 - 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 M.Zimate98% - 0.2 0.2 0.2 0.2 - - - - Unads98% - - - - - 0.2 0.2 0.2 0.2 Vanax A98% - - 0.5 - - - 0.5 - - sulfur - - - 0.15 - - - 0.15 - VULTAC 575% - - - - 0.67 - - - 0.67 170℃MDR M _H inch-pound 43 42 41 43 41 43 40 42 41 T _S1 min 0.38 0.34 0.45 .042 0.40 0.47 0.50 0.47 0.49 T _C90 minutes 7.2 4.6 4.8 4.4 4.4 4.5 5.3 4.7 4.5 Cure in air at 420°F for 8 minutes surface 10 7 1 4 1 7 1 4 1 bubbling none none none none none none none none none

Example 7

Using prior art low levels of elemental sulfur with prior art low levels of Sulfads®, with or without the optional HVA-2 monomer builder, gives good surface cure in hot air, but the resulting physical properties Poor (61% and 49% compression set).

Therefore, it is not easy to obtain a good combination of surface curing and desired desired physical properties using the low levels of sulfur compounds known in the prior art with the proposed additives and peroxide concepts.

Table 7 1 2 3 4 Keltan 4906EPDM 100 100 100 100 The following components are added in parts (by weight) (phr) based on 100 parts of rubber, ie no correction is required for the determination. N774 80 80 80 80 N330 20 20 20 20 LW150 oil 40 40 40 40 ZnO 6 6 6 6 stearic acid 1 1 1 1 Age Rite D 1 1 1 1 DC40P (40%) 5 5 5 5 HVA-2 - - 1.8 1.8 sulfur - 0.2 - 0.2 Sulfads98% - 0.4 - 0.4 Cured in air at 420°F for 8 minutes, surface tack (1-10), 10 being tack 10 1 10 1 Compression set at 120°C for 70 hours Compression set% 25 61 12 49

Example 8

In this example, it is demonstrated that the novel peroxide-additive composition works well in filled and unfilled EPDM formulations.

Code #2 contained EPDM only, and a novel peroxide-additive formulated, ie, no oil, carbon black, ZnO, or stearic acid. To illustrate: As suggested by the practice of the present invention, the novel formulations, when cured in the presence of air, form completely tack-free surfaces (1 on a scale of 10), where 10 is tack. Addition of constant amounts of carbon black and oil (Code 4) in the presence of air forms an excellent non-tacky surface. For organic peroxide type cures, the use of very high levels of carbon black (in excess of the amount of EPDM used) and high levels of oil, as indicated by numbers 6 and 8 in Table 8, reduced the degree of crosslinking as expected (M _H ). However, the surface cure in the presence of air was surprisingly good (4 out of 10) as the amount of peroxide-additive mixture was increased, as shown by entry 8. It is well known that high levels of oil and carbon black can adversely affect the cure of peroxides. Peroxide radicals can readily abstract hydrogen from oil and rubber. This significantly reduces the efficiency of peroxide cure as the oil concentration increases. This is illustrated by the decreased _MH of the two peroxide controls with no additives (compare No. 3 constant oil and carbon black with No. 5 high oil and carbon black).

Table 8 serial number 1 2 3 4 5 6 7 8 Royalene509EPDM 100 100 100 100 100 100 100 100 The following components are added in parts (by weight) (phr) based on 100 parts of rubber, ie no correction is required for the determination. N774 carbon black - - 75 75 130 130 130 130 Sunpar 2280 Oil - - 20 20 60 60 60 60 ZnO - - 5.0 5.0 5.0 5.0 5.0 5.0 stearic acid - - 0.5 0.5 0.5 0.5 0.5 0.5 DC40KEP40% 7.00 5.00 7.00 5.00 7.00 5.00 10.5 7.50 HVA-2 - 1.50 - 1.50 - 1.50 - 2.25 VULTAC575% - 0.67 - 0.67 - 0.67 - 1.00 B. Zimate98% - 0.2 - 0.2 - 0.2 - 0.30 Curing of cross-linked MDR at 170°C, 1° radian M _H inch-pound 40 31 43 41 18 twenty four 26 31 T _S1 min 0.45 0.46 0.38 0.40 0.54 0.50 0.43 0.44 T _C90 minutes 8.3 5.8 7.2 4.4 7.0 4.2 6.6 3.8 Cured in air at 375°F for 14 minutes surface 7 1 10 1 10 6 10 4

Example 9

Novel Peroxide-Additive Mixture for Hot Air Curing of Highly Filled EPDM

This highly filled EPDM contains high amounts of carbon black and oil. This formulation is intended for sulfur cure only and generally not for peroxide cure. The successful use in these examples demonstrates the unexpectedly great applicability of these novel peroxide-additive mixtures. In addition, the efficacy of this system is also illustrated by providing examples using 4 different organic peroxides. They are LUPEROX® 231-XL=40% 3,3,5-trimethyl-1,1-bis(tert-butylperoxy)cyclohexane; LUPEROX 230-XL=40% n-butyl-4,4- Di(tert-butylperoxy)valerate; Peroximon DC40KEP=40% dicumyl peroxide and Peroximon F40KEP40% bis(tert-butylperoxy)diisopropylbenzene.

The peroxide controls (Nos. 1, 3, 5, 7 in Table 9) were all tacky when crosslinked in the presence of air due to the uncured surface. There are also some air bubbles inside the sample. The novel peroxide-additive formulations used in the present invention form fully cured surfaces (non-tacky) when crosslinked in the presence of air, see Nos. 2, 4, 6, 8 in Table 9. These formulations are surprisingly curable to a higher degree of crosslinking, to the point of being free of foam (bubbles). Thus the novel peroxide formulations, when cured in hot air, can form solid cross-linked parts with better non-tacky surfaces. Cure times vary due to the peroxide used and the surface is always surprisingly tack-free despite the use of a lot of fillers and oils.

Table 9 serial number 1 2 3 4 5 6 7 8 Nordel 2470EPDM 100 100 100 100 100 100 100 100 The following components are added in parts (by weight) (phr) based on 100 parts of rubber, ie no correction is required for the determination. N762 100 100 100 100 100 100 100 100 N650 100 100 100 100 100 100 100 100 2280 oil 100 100 100 100 100 100 100 100 Lup231KE40% 16.0 10.0 - - - - - - Lup230XL40% - - 16.0 10.0 - - - - Per DC40P40% - - - - 16.0 10.0 - - Per F40P40% - - - - - - 16.0 10.0 HVA-2 - 4.0 - 4.0 - 4.0 - 4.0 Vanax A98% - 0.3 - 0.3 - 0.3 - 0.3 Durax98% - 0.2 - 0.2 - 0.2 - 0.2 VULTAC575% - 1.5 - 1.5 - 1.5 - 1.5 MDR temperature 150°C 165°C 170°C 180°C M _H inch-pound 11 26 11 twenty three 14 26 20 29 T _S1 min 0.50 0.48 0.53 0.49 0.52 0.56 0.38 0.38 T _C90 minutes 4.6 5.4 4.4 4.5 7.0 5.0 5.4 3.1 Cure in air for 14 minutes 360°F 390°F 400°F 415°F surface 10 2 10 1 10 1 10 1 bubbling Very little none a small amount none a small amount none a small amount none

Example 10

ADA (Azodicarbonamide) is a blowing agent used to form foam products

In Table 10, free rise crosslinked EPDM sponges cured in hot air were made using ADA and the novel peroxide-additive formulations of the present invention were used to form tack-free surfaces. Also provided in Table 10 is Peroxide Control No. 1 with no additive or ADA. Note: According to a live mold rheometer (MDR2000E, 200°C, 1° arc), the degree of crosslinking is M _H = 19.8 in-lbs. It should be noted, however, that when crosslinked in the presence of air, the surface is very sticky. The tan delta value for No. 1 (peroxide control) was 0.064, which is the desired low value. MDR measures tan delta, which is determined by dividing the modulus of viscosity by the modulus of elasticity. Cured compounds with low tan δ are elastic and exhibit low hysteresis. A high tan δ indicates that the polymer chains are capable of permanent movement or deformation after stress is applied. No. 2 in Table 10 provides peroxide and ADA, no other additives, M _H = 17.6 in-lbs, ADA appears to reduce the degree of crosslinking, although air pressure can also affect the reading, but compared with No. 1, the formation of sticky surface.

No. 3 in Table 10 used peroxide, ADA and auxiliary agent mixture N, N'-m-phenylene bismaleimide (HVA-2) and 1,3-bis(citraconimide formazan Base) benzene (Perkalink 900) after hot air curing gave improved crosslinking properties according to a higher _MH of 24.9 in-lbs, but the surface was very tacky (7 out of 10). Additives, along with peroxides, help to improve cure, but again create a poor surface due to air inhibition.

No. 4 in Table 10, certain low levels of additives, ADA, no additives, cured in hot air with peroxides improved the surface (4-5 out of 10) but had very low crosslinking (M _H = 14.9 in-lbs) with a bad tan delta value of 0.095.

Excellent crosslink density (M _H of 22.2 inch-pounds) and very good finish (2 out of 10) (No. 5 in Table 10). Description: A homogeneous foam EPDM with a density of 30 lb/ ^ft3 was produced.

No. 7 in Table 10, as suggested by the prior art, when cured in hot air using Vanox ZMTI (93% Zinc 2-Mercapto-Mebendazole (toluimidazole)) with ADA at 5 phr peroxide, gave a tack-free surface , but compared to No. 5, unfortunately, the M _H value is low, only 16.9 in-lbs, and the corresponding tan δ is poor.

Using Captax (98% 2-Mercaptobenzothiazole) for No. 8 in Table 10 according to the prior art can also form a tack-free surface, but the final physical properties (M _H and tan δ) of crosslinking will be further reduced.

Table 10 serial number 1 2 3 4 5 6 7 8 Royalene X3378EPDM 100 100 100 100 100 100 100 100 The following components are added in parts (weight) (phr) based on 100 parts of rubber, that is, no correction is required for analytical purity. N774 carbon black 100 100 100 100 100 100 100 100 Sunpar 228 oil 40 40 40 40 40 40 40 40 ZnO 2 2 2 2 2 2 2 2 stearic acid 2 2 2 2 2 2 2 2 DC40KEP40% 9.0 9.0 9.0 9.0 9.0 4.5 9.0 9.0 HVA-2 - - 0.5 - 0.5 2.0 - - Perkalink900 - - 1.5 - 1.5 - - - Sulfads98% - - - 0.3 0.3 0.3 - - Unads98% - - - 0.2 0.2 0.2 - - Vanox ZMTI93% - - - - - - 5.0 - Captax98% - - - - - - - 5.0 Azodicarbonamide ADA - 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Cross-linking in MDR at 200°C, 1° arc M _H inch-pound 19.8 17.6 24.9 14.9 22.2 19.6 16.9 6.7 tanδ 0.064 0.068 0.037 0.095 0.046 0.64 0.093 0.247 T _S5 minutes 0.34 0.36 0.26 0.39 0.33 0.38 0.39 - T _C90 minutes 0.78 0.78 0.57 0.69 0.60 0.61 0.75 0.98 Cured at 400°F for 7 minutes in hot air surface 10 5 7 4 1 1 1 4 Density (lb/ ^ft3 ) 74 twenty one 48 twenty two 30 26 29 43 Cured in hot air @400°F for 12 minutes surface 9 9 9 5 2 1 1 1 Density (lb/ ^ft3 ) 71 twenty four 54 twenty two 30 28 29 41

Example 11

Common additives were evaluated with LUPEROX® 101-XL [45% 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane] added to the sulfur donor-accelerator mixture

These peroxide-adjuvant-accelerator mixtures were used to cure standard EPDM, indicating that maleimide-type additives, HVA-2 or Vanax MBM were the only ones tested capable of crosslinking EPDM in the presence of air A blend of all major properties that give a good cure when forming a tack-free surface.

Overall, the adjuvant was more effective in Royalene(R) 521 EPDM than Royalene 509 in Example 4/Table 4. Referring to Table 11, No. 5 has only HVA-2, which when used in the practice of the present invention forms a tack-free surface and has a higher MDR torque than the peroxide control No. 1 in Table 11. While a small number of additives can provide some poorly repeatable improvements, only the bismaleimide type of additives together with selected low levels of additives can surprisingly result in a good combination of surface cure and physical properties.

In addition, the foregoing data in Tables 5 and 11 demonstrate that HVA-2 has the fastest cure time of all additives, while also functioning well with low levels of additives in the practice of the present invention, shortening the time to cure in air. Time to cure, forming a tack-free surface with excellent final physical properties. The reduced cure time should help producers increase productivity and make better products.

For the various components in Table 11

LUPEROX101-XL (45% 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane)

Sufads (98% bispentamethylenethiuram tetrasulfide)

SantocureTBSI (N-tert-butyl-2-benzothiazole sulfenamide)

TAIC (triallyl isocyanurate)

SR-350 (trimethylolpropane trimethacrylate)

HVA-2 (N, N'-m-phenylene bismaleimide)

DAM (diallyl mellitic acid)

Table 11 serial number 1 2 3 4 5 6 7 8 9 10 Royalene521EPDM 100 100 100 100 100 100 100 100 100 100 The following components are added in parts (by weight) (phr) based on 100 parts of rubber, ie no correction is required for the determination. N660 80 80 80 80 80 80 80 80 80 80 2280 oil 10 10 10 10 10 10 10 10 10 10 stearic acid 1 1 1 1 1 1 1 1 1 1 Lup101XL45% 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 Sulfads98% - 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 TBSI - 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 TAIC - - 2.00 - - - - - - - SR-350 - - - 2.00 - - - - - - HVA-2 - - - - 2.00 - - - - - ZnDMA - - - - - 2.00 - - - - DAM - - - - - - 2.00 - - - SR-206 - - - - - - - 2.00 - - Perkalink900 - - - - - - - - 2.00 - sulfur - - - - - - - - - 0.20 185℃MDR M _H 37 27 32 35 41 27 32 33 31 28 T _S1 0.34 0.40 0.39 0.41 0.37 0.31 0.40 0.44 0.41 0.42 T _C90 4.2 3.7 4.3 3.4 2.4 3.7 4.2 4.0 3.6 3.5 Cured in air at 420°F for 8 minutes surface 10 5 4 2 1 1 4 4 4 1

Example 12

The surface tack (mass) and percent compression set, cured in air, of various peroxide-sulfur cure mixtures for other applications were rated in comparison to the novel mixture of the present invention and standard peroxide and sulfur cure .

The novel peroxide cure system No. 2 in Table 12 unexpectedly formed an excellent tack-free surface (1 out of 10) in air with significant compression set, comparable to Nos. 1, 3 and 6 in Table 12. Peroxides that are very viscous (10 out of 10) when cured in air are equally cured. Sulfur additives Nos. 4 and 5 in Table 12, without HVA-2, resulted in poor surfaces and higher unfavorable compression set values. Entries 7 and 8 in Table 12 employ a half-EV (half-efficiency sulfur vulcanization system) with low levels of elemental sulfur, resulting in the expected improved surface (non-tacky), but exhibiting poor compression set for this EV sulfur cure . The poor compression set values of 77% and 71% for the standard sulfur vulcanization system, Nos. 9 and 10 in Table 12, formed a good tack-free surface, which was compared to the excellent 14-16% compression set but very sticky surface. The peroxide controls Nos. 1, 3 and 6 in Table 12 were different.

Table 12

The novel mixture of the present invention (No. 2) with various peroxide-sulfur curing systems (No. 4, 5, 7 and 8) and standard peroxide (No. 1, 3 and 6) and standard sulfur curing (No. 9 Comparison with 10)

Royalene 521EPDM 100

N660Black 75

2280 Oil 20

stearic acid 1 serial number 1 2 3 4 5 6 7 8 9 10 ZnO 1.00 1.00 1.00 1.00 1.00 3.00 3.00 3.00 3.00 3.00 DC40KEP 6.00 6.00 7.50 7.50 7.50 8.00 6.00 4.00 - - SR-206 2.00 - - - - - - - - - HVA-2 - 2.00 - - - - - - - - Sulfads98% - 0.24 - - - - 0.70 1.40 - 2.80 M.Niclate98% - 0.24 - - - - - - - - Altax - - - - - - 0.40 0.80 1.00 1.60 Unads - - - - - - 0.40 0.80 1.50 1.60 Durax - - - 0.10 0.20 - - - - - sulfur - - - 0.20 0.40 - 0.10 0.20 2.00 0.40 170℃MDR M _H (inch pounds) 26 31 26 25 25 27 twenty one 26 31 29 T _S (minutes) 0.74 0.50 0.47 0.45 0.50 0.47 0.85 0.99 1.02 0.93 T _CSO (minutes) 7.1 4.1 7.2 5.3 5.1 7.1 4.3 3.4 3.0 2.6 Compression set at 150°F for 70 hours Compression set% 14 16 16 28 42 15 62 73 77 71 Cure in air at 400°F for 8-12 minutes surface 10 1 10 10 7 10 2 1 1 1

Example 13

Storage stability of new peroxide formulations

These powder compositions can be premixed and stored for later use without loss of activity. In Table 13, Nos. 3 and 5 are Mixture 1 and Mixture 2 aged at room temperature for 3 months, respectively. These aged mixtures were compared to freshly prepared peroxide mixtures (shown as entries 2 and 4 in Table 13). Within experimental error, the rheometer torque versus time curves and the mass of the crosslinked surface cured in hot air were identical for the two mixtures. If the components react during aging, the MDR torque, time and surface are closer to the control (No. 1). In the practice of the present invention, it is possible to add the various components followed by the peroxide, but pre-mixing the various additives may make this more feasible and/or easier to apply.

Table 13

The novel peroxide compositions can be premixed and stored for later use without loss of activity or performance. Two different peroxide formulations were stored for 3 months.

Mixture 1 Mixture 2

                                                                                                                                      

HVA-2 27.8% 22.8%

Sulfads 3.8 -

Unads 3.8 -

VULTAC5 - 8.8

Durax - 3.8

Keltan 4506EPDM 100

N660Black 50

N550Black 50

                                                                                                                                                   , 

ZnO 3.0

Stearic acid 1.5 serial number 1 2 3 4 5 Aging of the mixture 0 0 3 months 0 3 months DC40P 8.0 - - - - Mixture 1 - 7.9 - - - Mixture 1 - - 7.9 - - mixture 2 - - - 7.9 - mixture 2 - - - - 7.9 Using MDR@170℃, 1° radian cross-linking M _H (inch-lbs) 21.3 25.0 24.6 25.6 25.2 T _S4 (minutes) 0.38 0.56 0.55 0.38 0.39 T _C90 (minutes) 6.8 4.6 4.5 4.4 4.3 Cured in air at 400°F for 14 minutes surface 10 2 1.5 3 2

Example 14

Low levels of antioxidants (phenols, metal salts of dimethyl dithiocarbamic acid) combined with bismaleimide additives and low levels of sulfur donors, when curing elastomers in the presence of air, form Excellent non-stick surface also results in better final physical properties (i.e. low compression set)

Novel peroxide air-cure formulations consisting of peroxide(s), bismaleimide builder(s), sulfur donor-sulfur accelerator system can also contain Low content of antioxidants. In above-mentioned embodiment 4, number 11 (M.Niclate, i.e. Methyl Niclate) nickel dimethyl dithiocarbamate in table 4 is used with the low consumption of 0.2phr, uses other such as zinc (M.Zimate) and Copper (M. Cumate) type dimethyl dithiocarbamate and Sulfads(R) successfully produced non-stick surfaces with good physical properties (compression set). The Methyl Niclate, whose chemical name is nickel dimethyldithiocarbamate, is sold as an antioxidant.

In this embodiment 14 and table 14, number 3 uses the low content Methyl Niclate of 0.28phr, has been contrasted with phenolic antioxidant and sulfenamide accelerator; See the MBPC of number 6 (2,2'-methylene Di-4-methyl-6-tert-butylphenol), and Santocure TBSI No. 7 (N-tert-butyl-2-benzothiazole sulfenimide). According to the invention, HVA-2 and Sulfads are also contained in the formulation in each case.

According to No. 2, 3 and 4 in Table 14, Methyl Niclate (nickel dimethyl dithiocarbamate) and Sulfads (98% bispentamethylene thiuram tetrasulfide) or Morfax (98% 4-mol Linyl-2-benzothiazole) is an acceptable composition. MBPC (2,2′-methylenebis-4-methyl-6-butylphenol) or SantocureTBSI (N-tert-butyl-2-benzothiazole sulfenimide) instead of Niclate (dimethyldi Nickel thiocarbamate) can form a good surface and have better low compression set physical properties. Thus, low levels of phenolic antioxidants and sulfenamide accelerators work well with HVA-2 and low levels of other sulfur accelerators in the novel peroxide compositions of the present invention. It is not obvious from the teachings of the prior art that these low levels of compounds are effective. Examples of prior art formulations using the acrylic builder SR-206 (ethylene glycol dimethacrylate) are shown in Table 14, entries 9 and 10, which contained much higher levels of antioxidants , Vanox MBPC (99% 2,2′-methylenebis-4-methyl-6-tert-butylphenol) and Vanox ZMTI (93% 2-mercapto-mebendazole (toluimidazole) zinc) appear to be As a bad effect, it also has a badly high compression set value, especially number 10.

Table 14

Royalene 521EPDM 100

N660Black 75

2280 Oil 20

ZnO ZnO 1

stearic acid 1 serial number 1 2 3 4 5 6 7 8 9 10 DC40KEP 7.5 6.0 5.0 5.0 5.0 5.0 5.0 6.0 6.0 6.0 SR-206 - - - - - - - 2.0 2.0 2.0 HVA-2 - 2.0 2.0 2.0 2.0 2.0 2.0 - - - Sulfads - 0.24 0.20 - - 0.20 0.20 - - - Methyl Niclate - 0.24 0.28 0.28 - - - - - - Morfax - - - 0.20 0.48 - - - - - TBSI - - - - - - 0.28 - - - MBPC - - - - - 0.28 - - - 2.5 ZMTI - - - - - - - - 2.5 - 170℃MDR M _H 26 31 29 28 28 29 30 26 26 13 T _S1 0.47 0.50 0.51 0.42 0.43 0.55 0.54 0.74 0.73 1.44 T _C90 7.2 4.1 3.7 3.8 3.9 3.9 4.1 7.1 6.7 11.6 Cured in air at 400°F for 12 minutes surface 10 1.5 2 2 4 1 1 10 8 10 Compression set at 150°C for 70 hours Compression set% 16 16 16 15 19 17 19 14 twenty two 49

Example 15

Cross-linked fully saturated elastomer (ethylene-octene copolymer)

Ethylene-octene (24%) copolymer G8100 from Dupont dow cured in a rheometer with 2 levels of dicumyl peroxide with and without HVA-2-VULTAC® 5-Butyl Zimate , thin samples were cured in hot air. The compatibilized formulation is rubbery but slightly thermoplastic and cannot be vulcanized.

In Table 15, Nos. 3 and 4 were only slightly tacky after curing, which is a big improvement since most thermoplastic ethylene polymers would be tacky in this test simply because these polymers at these temperatures Will melt/soften. Adding oil reduces rigidity, but makes the surface stickier. In the case of said low filler content, no oil can be included. These samples (No. 3 and 4) were not sticky when cooled to room temperature.

Table 15

    Cross-linked fully saturated elastomer (ethylene-octene copolymer)

          EG8100                                          

N660Black 60

2280 oil 5

ZnO 3

                                                        

AgeRite MA 0.5 serial number 1 2 3 4 DC40P 7.0 10.0 4.00 5.72 HVA-2 - - 1.50 2.14 VULTAC5 - - 0.55 0.79 B. Zimate - - 0.25 0.36 170℃MDR M _H (inch-lbs) twenty two 30 30 37 T _S4 (minutes) 0.43 0.39 0.49 0.44 T _C90 (minutes) 7.6 6.9 5.3 5.0 Surface tack grades that cure in air 420°F/8 minutes 10 10 5 5 375°F/18 minutes 10 10 4 4

Example 16

Evaluation of different bismaleimide compounds for novel peroxide formulations capable of crosslinking elastomers with non-stick surfaces in the presence of air

缩写：MPBM1-1′-(亚甲基-二-4，1-亚苯基)二马来酰亚胺缩写：MMBMN，N′-(4-甲基-1，3-亚苯基)二马来酰亚胺用于这些实验的橡胶配制物如下所述：橡胶配制物                           份数Keltan 2506EPDM(DSM共聚物)           100N660碳黑(Huber)                      75Sunpar 2280(Sun Oil)                 15Peroximon DC40KEP                    5助剂                                 相当于2.0phr MBM^*的摩尔数Vanax A(，T.Vanderbilt)            0.2VULTAC5(Elf Atochem)                 0.7Durax(R.T.Vanderbilt)                0.1^*考虑了每种助剂化合物的不饱和基团数目。In Table 16, several different bismaleimide compounds were evaluated in the practice of the present invention. All of these bismaleimide compounds surprisingly provided good crosslinking efficiency and a tack-free surface, tested immediately after removal from a 410°F hot air cure for 8 minutes. Various auxiliaries were evaluated on an equimolar basis (taking into account the amount of unsaturated functionality) compared to 2phr m-phenylene-bismaleimide (MBM). The structures of these various compounds are described below: Abbreviation: MBMN, N′-1,3-phenylene bismaleimide

Abbreviation: MPBM1-1′-(methylene-bis-4,1-phenylene)bismaleimide Abbreviation: MMBMN, N'-(4-methyl-1,3-phenylene)bismaleimide The rubber formulations used in these experiments are as follows: Rubber formulation parts Keltan 2506EPDM (DSM copolymer ) 100N660 Carbon Black (Huber) 75Sunpar 2280(Sun Oil) 15Peroximon DC40KEP 5 Auxiliary Mole equivalent to 2.0phr MBM ^* Vanax A(, T.Vanderbilt) 0.2VULTAC5(Elf Atochem) 0.7Durax(RTVanderbilt) 0.1 ^* Consider The number of unsaturated groups of each additive compound is shown.

Table 16 serial number 1 2 3 4 Auxiliaries used none MBM MPBM MMBM Cross-linked DSM copolymer Keltan 2506EPDM in MDR2000E at 170°C and 1° radian M _L (pound-inch) 2.270 2.280 2.140 2.180 M _H (lb-inch) 34.90 32.47 27.51 30.08 M _H -M _L (pound-inch) 32.63 30.19 25.37 27.90 T _S0.2 (minutes) 0.310 0.330 0.370 0.345 T _S0.4 (minutes) 0.350 0.370 0.430 0.390 T _S1.0 (minutes) 0.440 0.465 0.550 0.490 T _C90 (minutes) 6.850 4.870 5.890 5.260 Crosslink at 410°F for 8 minutes in a hot air oven Surface tack, 1-10 scale (10 worst) 10 1 3 2 @150℃/70 min compression set% -- 27 46 36

Note: When no additives are used, more than 30% dicumyl peroxide is used in the formulation in order to reduce the surface stickiness. However, No. 1 had poor surface adhesion (10 out of 10) even with increased peroxide.

After completing the MDR2000E test, the AIR cured surface tack was tested. All samples were heated in a pressure oven at 410°F for 8 minutes. After 8 minutes, remove the sample and press a paper towel onto the hot sample. After cooling, remove the paper towel at a uniform rate and check for stickiness. Note that the hot air crosslinked samples had very little surface tack after cooling to room temperature (except for the peroxide cured control No. 1), and all samples had very similar low surface tack. All samples also showed their own foam heights, indicating that each AIR-cured sample does indeed foam to some degree internally. This depends in part on the low Mooney viscosity EPDM used.

Example 17

Different bismaleimide compounds were further evaluated for novel peroxide formulations capable of crosslinking elastomers in the presence of air to render their surfaces tack-free

Evaluation of 1,2,1 of N,N'-phenylene bismaleimide for a novel peroxide composition that can crosslink elastomers in the presence of air and form a fully cured, non-tacky surface , 3 and 1,4 (ortho, meta, right) isomers. The elastomer used in this example was Nordel® IP EPDM NDR-4640. This is one of the new Dupont Dow metallocene types of EPDM elastomers.

Various bismaleimide builders according to Nos. 5, 6 and 7 in Table 17 worked well to form a good non-tacky surface when used with low levels of additives selected according to the present invention. All of these novel compositions utilize a unique blend of low levels of sulfur-containing additives (Sulfads(R), VULTAC(R) 5 and Unads(R)) with bismaleimide builders and peroxides.

It was shown that when the individual components of the peroxide formulation were used alone, poor surface cure was obtained, see entries 1, 2, 3, 4 and 8 in Table 17. No. 1 is a single peroxide, No. 2-4 is adjuvant and peroxide, No. 8 is a mixture of peroxide and sulfur accelerator. In each case, the surfaces of these formulations were tacky when cured in hot air at 400°F.

Table 17

Evaluation of various bismaleimide compounds crosslinked Nordel IPNDR-4640EPDM in hot air oven in the practice of the present invention serial number 1 2 3 4 5 6 7 8 DCKEP 7.00 4.20 4.20 4.20 4.20 4.20 4.20 7.00 1,2PDM - 2.10 - - 2.10 - - - 1,3PDM - - 2.10 - - 2.10 - - 1,4PDM - - - 2.10 - - 2.10 - Sulfads - - - - 0.28 0.28 0.28 0.28 VULTAC5 - - - - 0.28 0.28 0.28 0.28 Unads - - - - 0.14 0.14 0.14 0.14 MDR2000E, 175°C, 1° arc M _H (lb-inch) 33.8 27.6 37.2 43.3 24.1 34.5 36.2 24.8 T _S.4 (minutes) 0.29 0.29 0.26 0.27 0.45 0.44 0.44 0.37 T _C90 (minutes) 4.59 5.26 3.06 2.94 4.59 3.26 5.18 4.22 140°C M _L 3.26 3.28 3.32 3.30 3.28 3.29 3.29 3.15 T _S.4 2.01 2.04 1.79 1.99 3.37 3.32 3.29 2.67 T _S.1 3.33 2.91 2.39 2.72 4.85 4.76 4.78 3.97 195°C M _H 30.5 23.5 34.1 39.7 20.5 31.7 34.2 22.7 M _L 2.47 2.45 2.71 2.63 2.14 2.14 2.16 2.19 T _S.4 0.19 0.20 0.17 0.17 0.26 0.25 0.25 0.22 T _C90 1.01 1.08 0.75 0.75 1.00 0.81 1.09 0.96 Cured in hot air @400°F for 12 minutes Surface Adhesive Grade 10 8 8 8 4 1 3 10 hardness 60 60 62 65 60 62 62 58 Formulation: Nordel 4640 100 ^* Surface Adhesion Rating:

N774 80 1: No stickiness; 4: Slight stickiness,

N990 20 7: medium; 10: sticky

Sunpar 2280 25

ZnO 1

Stearic acid 1PDM＝N,N-(1,2 or 1,3 or 1,4)-phenylene bismaleimide

Example 18

Various bismaleimide compounds were further evaluated in the practice of the present invention

Table 18 illustrates the use of four co-agent bismaleimide compounds with peroxides and selected low sulfur accelerators to form tack-free surfaces when cured in a hot air oven, in accordance with the practice of the present invention. Evaluation results of the effect of the elastomer. In this example, Dupont Dow Nordel IPNDR-4640 metallocene EPDM was chosen as the elastomer for evaluation.

缩写：BE1，2-二马来酰亚氨基乙烷The monomer compound is: 1,1'(3,3-dimethyl-1,1'-biphenyl-4,4'-diyl)-bismaleimide, N,N-(1, 1'-biphenyl-4,4'-bismaleimide), 1,2-bismaleimidoethane and 1,6-bismaleimidohexane. In Table 18, they are compared without N,N'-1,3-phenylene bismaleimide or VanaxMBM. Using the preferred formulation of the present invention consisting of Dicumyl Peroxide, Sulfads, VULTAC5 and Unads, we unexpectedly found that various dimaleimide adjuvants No. 2-6 in Table 18 and peroxide control Forms an excellent non-stick surface compared to No. 1, which forms a very sticky surface. Abbreviation: DMBPDB1,1'(3,3-Dimethyl-1,1'-biphenyl-4,4'-diyl)-bismaleimide Abbreviation: BPDBN, N'-(1,1'-biphenyl-4,4'-diyl)-bismaleimide Abbreviation: BH1,6-Bismaleimidohexane

Abbreviation: BE1,2-Bismaleimidoethane

Table 18

Study on Curing of Nordel NDR-4640 by Additive Mixture in Air serial number 1 2 3 4 5 6 DC40KEP 7.00 5.00 5.00 5.00 5.00 5.00 Vanax BM - 1.50 1.00 1.00 1.00 1.00 DMBPDB - - - 0.25 - - BPDP - - - 0.25 - - BE - - - - 0.50 - BH - - - - - 0.50 Sulfads - 0.28 0.28 0.28 0.28 0.28 VULTAC5 - 0.48 0.48 0.48 0.48 0.48 Unads - 0.14 0.14 0.14 0.14 0.14 MDR2000E, 175°C M _H (lb-inch) 44.0 40.8 36.9 40.1 40.2 39.8 T _S.4 (minutes) 0.27 0.38 0.38 0.38 0.39 0.39 T _C90 (minutes) 4.53 3.05 3.15 3.51 3.20 3.07 MDR195℃ M _H 40.2 38.0 34.3 37.0 36.6 36.9 M _L 2.94 2.62 2.55 2.60 2.57 2.60 T _S.4 0.18 0.23 0.23 0.22 0.22 0.23 T _C90 1.02 0.79 0.80 0.83 0.78 0.79 MDR140℃ M _L 3.85 3.95 3.81 3.91 3.90 3.85 T _S.4 1.74 2.86 2.85 2.83 2.82 2.79 Surface evaluation of cross-linked EPDM cured in a hot air oven at 400°F for 8-12 minutes, tack scale 1-10, 10 = tacky surface 8 minutes 10 2.5 4 2.5 3 4 12 minutes 10 1 2.5 1 1 1 Shore hardness 65 67 66 66 66 66

Recipe: Nordel 4640 100

N774 60

N990 60

2280 20

ZnO 1

                               

DMBPDB: 1,1'(3,3-Dimethyl-1,1'-biphenyl-4,4-diyl)-bismaleimide

BPDB: N,N'-(1,1'-biphenyl-4,4'-diyl)-bismaleimide

BE: 1,2-Bismaleimidoethane

BH: 1,6-Bismaleimidohexane

Example 19

Evaluation of 2-(2,4-cyclopentadien-1-ylidene)-1,3-dithiolane as an additive for novel peroxide formulations for use in hot air Oven cross-linked elastomers for good surface cure (tack-free surface) and good physical properties

Unsaturated sulfur compounds were evaluated in combination with bismaleimide builders and peroxides. The compound 2-(2,4-cyclopentadiene-1-ylidene)-1,3-dithiolane replaces the mixture of Durax, Vanax A and VULTAC5, which is mixed with N,N'-m- Combination of phenylene-bismaleimide (HVA-2) additive and dicumyl peroxide. According to the data in Table 19, this unique formulation crosslinks efficiently when cured in hot air at 410°F for 8 minutes and has an excellent non-tacky surface. 2-(2,4-cyclopentadien-1-ylidene)-1,3-dithiolane

In addition to good cross-linking properties in the presence of air, from which the inhibition of air (oxygen) can be resolved, the final cross-linked elastomer was found to have excellent final physical properties, according to the preferred low compression set percentage, which in Obtained after heat aging cross-linked EPDM at 150°C for 70 hours.

Table 19 serial number 1 2 DSM2506EPDM 100 100 N660 carbon black 75 75 Sunpar2280 15 15 Dicumyl Peroxide 40% on Clay 5 5 N,N'-m-phenylene bismaleimide 2 2 Vanax A 0.2 - VULTAC5 0.7 - Durax 0.1 - 2-(2,4-cyclopentadien-1-ylidene)-1,3-dithiolane - 1.0 MDR2000E 170°C, 1° arc M _H -M _L (inch-lb) 32 30 T _S4 minutes 0.36 0.34 T _C90 5.23 5.44 Cures at 400°F in hot air The grade of surface tack 2 1 150℃, 70 hours compression set% 27% 14%

Example 20

Polysulfides are used in combination with selected halogenated polymers or silicone rubbers (used as additives) with peroxides, sulfur accelerators and bismaleimide builders to make tack-free in highly compatibilized EPDM formulations surface

Nordel IP 4520 (Dupont Dow Elastomers) mixed with equal weight carbon black and high oil content is difficult to cure with usual peroxides, it is a typical sulfur curing hose compound formulation. Highly compatibilized EPDM formulations, in which the carbon black and or oil content is nearly equal to the amount of EPDM, are formulations that are difficult to cure well with organic peroxides. When curing highly filled EPDM in the presence of air, the peroxide radicals attack oil and carbon black as well as rubber, so it can be difficult to get a good cure level and maintain a tack-free surface in the presence of air.

With the novel mixture of sulfur accelerator and bismaleimide of the present invention, we also added small amounts of (FA) polysulfide polymer and (SE6160) silicone rubber as novel additives for the present invention. We have found that polysulfide polymers with silicone rubber or chlorinated polyethylene or Hypalon (chlorosulfonated polyethylene) with peroxides, bismaleimide additives and selected low-level sulfur accelerators Mixture that forms a suitable tack-free curing surface in the presence of air. Thus, the novel mixture may provide a means of curing these highly compatibilized EPDM formulations that are typically cured with sulfur vulcanization. It should be noted that the various sulfur cure systems used in the prior art are insensitive to higher concentrations of oil and carbon black and are capable of fully curing highly compatibilized rubber formulations.

We therefore anticipate that it is possible to prepare polymer masterbatches of peroxides, selected sulfur accelerators, bismaleimide builders, polysulfides, into which chlorinated polyethylene and or chlorosulfonated polyethylene can be added as Additional additives are considered part of the invention.

To illustrate, the use of silicone rubber without polysulfide polymers can produce moderately viscous surfaces. The use of fluoroelastomers as additives in the present invention, in combination with polysulfides does not form a suitable surface.

Table 20

Effect of Polymer Additives on Air Curing Nordel IP4520 1 2 3 4 5 6 4520EPDM 100 100 100 100 100 100 N660 100 100 100 100 100 100 N990 60 60 60 60 60 60 LW150 oil 60 60 60 60 60 60 stearic acid 0.50 0.50 0.50 0.50 0.50 0.50 DCKE40% 10.0 8.0 8.0 8.0 8.0 8.0 MBM - 1.35 1.35 1.35 1.35 1.35 Vanax A - 0.15 0.15 0.15 0.15 0.15 VULTAC5 - 0.45 0.45 0.45 0.45 0.45 Durax - 0.05 0.05 0.05 0.05 0.05 polysulfide - - 1 1 1 1 Silicone Rubber - 4.00 4.00 - - - CPE - - 4.00 - - Hypron - - - 4.00 - Fluoroelastomer - - - - 4.00 RPA170C, 0.2° radian, 60cpm Maximum S' (inch-lbs) 4.57 5.66 5.82 6.41 7.61 5.94 T _S.5 0.64 0.46 0.44 0.41 0.35 0.46 T _C90 7.46 4.36 4.69 4.89 3.88 4.63 surface sticky medium slight none none medium

surface:

Tacky: Very sticky; Slightly; Only slightly sticky; None: Not sticky; Moderate: Moderately sticky.

Example 21

In this example we show more data on curing "difficult to cure with peroxide" highly filled EPDM formulations

In this particular formulation, we used more carbon black (180 parts total) than EPDM rubber (100 parts total). Using a novel mixture of peroxide, MBM, and selected sulfur accelerators (listed as mixture 1), crosslinked in the presence of air at a lower total curative rate than standard peroxide (code 1). Concentration, can form a good surface (No. 2). Again, it is very difficult to cure highly filled EPDM formulations with organic peroxides. Those of ordinary skill in the industry would not have thought of such formulations with organic peroxides and would only use sulfur vulcanization cure systems.

Surface curing was further improved using a small amount of chlorosulfonated polyethylene (Hipron, ex Dupont Dow) as a novel additive used in the practice of the present invention (entry 3) when crosslinked in the presence of hot air. A further improvement in surface cure was noted when using a mixture of polysulfides and Hypalon (entry 4) as the novel polymer additive in the practice of this invention.

                          Table 21 uses chlorosulfonated polyethylene and polysulfides as new additives, and uses organic peroxides in

Crosslinks highly filled EPDM in the presence of air to form a tack-free surface 1 2 3 4 DCKEP 15.00 - 4.00 4.00 Mixture 1 - 10.00 8.00 8.00 AgeRite MA - - - - MTBHQ - - - - ^* Hepron 40 - - 5.00 5.00 polysulfide - - - 1.00 RPA cured at 170C, 0.2° arc, 60cpm Maximum S' (inch-lbs) 5.77 6.75 8.72 8.32 T _S.5 minutes 0.42 0.53 0.35 0.35 T _C90 minutes 6.07 4.41 3.46 3.69 Cured at 400°F in hot air for 8-12 minutes surface stickiness sticky slight very slight none

Rubber formulation: Mixture 1:

4570 EPDM 80 ^* DCKE 60%

4770 EPDM 20 MBM 27%

N660 120 Vanax A 3%

N990 60 VULTAC5 9%

LW150 80 Durax 1%

Stearic acid 0.8

^* A small amount of Hepron (dosage as indicated above) replaces the same amount of 4570EPDM

Example 22

In this example, we illustrate several new chemical and polymer additives for the development of peroxide formulations that crosslink elastomers in the presence of hot air

These are in particular: Vanax 6H (N-Cyclohexyl-N'-Phenyl-p-Phenylenediamine) CAS101-87-1, an antiozonant for diene-based polymers, polysulfides (PTE) and silicon Rubber (VMQ). Vanax 6H (RT Vanderbilt)

We illustrate the use of antiozonants in place of sulfur-containing compounds in the practice of this invention. The present invention contemplates such antiozonants and substances having similar structures as full equivalents of other compounds included within the definition of compound (B). In addition, polysulfides (PTE) are also used for the same purpose.

Finally, an unexpected mixture of two polymers, PTE and VMQ, as a polymer additive, with peroxides, was able to make non-stick surfaces in the presence of hot air. Note that no bismaleimide and sulfur compounds or antiozonant additives were used.

Table 22

Crosslinked Royalene 501EPDM uses polysulfide and silicone rubber, also uses antiozonant N-cyclohexyl-N'-phenyl-p-phenylenediamine (Vanax 6H). The basic formula of the elastomer: 100 parts of Royalene 501EPDM, 70 parts of N550 carbon black, 30 parts of N-990 carbon black, 20 parts of Sunpar LW150 oil, 1 part of zinc oxide, 1 part of stearic acid. additive 1 2 3 4 5 6 7 DCP40KE 7.5 4.6 4.6 4.6 4.6 4.6 7.5 MBM - 2.2 2.2 2.2 2.2 2.2 - Vanax A - - 0.7 - - - - Vanax 6H - - - 0.7 - - - polysulfide - - - - 0.7 2.2 3.0 VMQ - - - - - - 7.0 Using MDR2000E, 175°C, 1° arc cross-linking M _H (inch-lbs) 35.6 37.8 40.1 36.1 33.3 36.0 27.7 T _{S. 04} minutes 0.3 0.26 0.29 0.34 0.26 0.26 0.30 T _C90 minutes 4.39 2.98 3.46 3.63 2.51 2.89 3.98 Curing at 400°F in hot air (8-12 minutes) Surface tack (heat test) have have none none none none none

Example 23

Examples using various other dialkyl-type peroxides

In this example we used a different organic peroxide crosslinked metallocene based EPDM (Nordel IP4640). It was stated that in each case peroxides without the various additives failed to form a tack-free surface when crosslinking EPDM elastomer formulations in the presence of hot air. The peroxides listed in Table 23 are:

Peroxide Chemical Name

Lup101 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane

MTBPP 4-Methyl-4-(tert-butylperoxy)-2-pentanone

Luperox F/R Bis(tert-butylperoxy)diisopropylbenzene

DAPDIB Bis(tert-amylperoxy)diisopropylbenzene

This example is used to illustrate that, in addition to the most commonly used dialkyl peroxides and dicumyl peroxides that have been thoroughly evaluated in the preceding examples, other dialkyl peroxides can also be used in the practice of the present invention. middle.

Table 23

Curing of crosslinked Nordel IP4640EPDM in hot air with other dialkyl peroxides 1 2 3 4 5 6 7 8 Nordel4640 100 100 100 100 100 100 100 100 N330 60 60 60 60 60 60 60 60 N990 40 40 40 40 40 40 40 40 LW150 35 35 35 35 35 35 35 35 ZnO 1 1 1 1 1 1 1 1 stearic acid 1 1 1 1 1 1 1 1 Lup10192.8% 3.60 2.20 - - - - - - MTBPP84.4% - - 4.90 3.00 - - - - Luperox F/R - - - - 3.60 2.20 - - DAPDIB79.7% - - - - - - 4.90 3.00 Vanax MBM - 2.40 - 2.40 - 2.40 - 2.40 Sulfads - 0.32 - 0.32 - 0.32 - 0.32 Vultac5 - 0.32 - 0.32 - 0.32 - 0.32 Unads - 0.16 - 0.16 - 0.16 - 0.16 Using MDR2000E@200°C, 1° radian cross-linking M _H 27.4 30.9 21.1 30.7 32.7 34.9 26.3 29.9 T _S.4 0.18 0.24 0.19 0.24 0.17 0.22 0.17 0.21 T _C90 1.07 0.76 1.16 0.85 0.91 0.72 0.79 0.58 Cured in hot air @400°F, surface tack grade Surface tack (heat test) have none have none have none have none

Peroxide: Chemical Name:

Lup101 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane

MTBPP 4-methyl-4-(tert-butylperoxy)-2-pentanone

Luperox F/R Bis(tert-butylperoxy)diisopropylbenzene

DAPDIB Bis(tert-amylperoxy)diisopropylbenzene

Those of ordinary skill in the art will recognize that the compositions of the present invention may also be formulated for ease of processing and blended into polymer masterbatches for crosslinking in the presence of molecular oxygen. Common masterbatch carriers include, for example, microcrystalline wax, polycaprolactone, ethylene-propylene-diene monomer polymer (EPDM), ethylene-propylene monomer polymer (EPM), ethylene-vinyl alcohol polymer ( EVA), polyethylene (PE) or their mixtures.

The subject matter which the applicant regards as his invention is particularly pointed out and distinctly claimed in the appended claims.

Claims (27)

1. composition, it contains:

A) at least a compound (A), it is selected from silicone elastomer and has the compound of following formula (I):

(I) wherein n is 1 or 2, R is divalence or trivalent, it is selected from the non-annularity of 2-16 carbon atom aliphatic group approximately, the alicyclic group of 5-20 carbon atom is arranged approximately, have approximately the aryl peace treaty of 6-18 carbon atom that the alkaryl of 7-24 carbon atom is arranged, wherein these divalence or the trivalent group hetero atom that can contain one or more O of being selected from, N and S replaces one or more carbon atoms, and each R₁Identical, be a hydrogen or 1-18 carbon atom alkyl;

(b) at least a compound (B), it is selected from antiozonant and the organic compounds containing sulfur of p-phenylenediamine base, and this organic compounds containing sulfur is selected from the mixture that can promote to be undertaken by sulphur organic compounds containing sulfur, polysulfide polymer and the described sulfur-containing compound of the sulfur vulcanization of crosslinked polymer.

2. composition as claimed in claim 1, it also contains the radical initiator that is selected from organic peroxide and azo initiator.

3. composition, the polymer that it contains composition as claimed in claim 2 and can be solidified by radical initiator.

4. method, it comprises the goods that composition formation claimed in claim 3 is had shape, then in the presence of molecular oxygen, make it stand to be enough to cause the temperature that radical initiator decomposes, obtain thus the substantially noncohesive cured article with shape in surface.

5. composition, it requires 1 described compound (A) by hybrid right and (B) forms.

6. composition, it by require with the random order hybrid right 1 described compound (A) and (B) and organic peroxide form.

7. composition as claimed in claim 1, wherein said compound (A) is selected from dimaleimide, and compound (B) is selected from sulphur promoter.

8. composition as claimed in claim 1, wherein said compound (A) is selected from two citraconimides, and compound (B) is selected from sulphur promoter.

9. composition as claimed in claim 1, wherein said compound (A) is selected from dimaleimide, and compound (B) is selected from polysulfide polymer.

10. composition as claimed in claim 1, wherein said compound (A) is selected from two citraconimides, and compound (B) is selected from polysulfide polymer.

11. composition as claimed in claim 1, wherein said compound (A) is selected from silicone elastomer, and compound (B) is selected from polysulfide polymer.

12. composition as claimed in claim 1, it also contains the sizing material that is selected from haloflex and chlorosulfonated polyethylene.

13. composition as claimed in claim 2, wherein said radical initiator is selected from organic peroxide.

14. the noncohesive cure polymer in surface, it is cured by decomposing the free radical that produces such as the radical initiator in the described composition of claim 3 in the presence of molecular oxygen.

15. method for preparing surperficial noncohesive cure polymer, described cure polymer is cured by the free radical that the radical initiator decomposition that is contained in wherein produces in the presence of molecular oxygen, the method comprises mixes described polymer with composition claimed in claim 2, and supply with enough heats radical initiator is decomposed, introduce in the polymer thus.

16. one kind prepares the method that can be solidified into the curable compositions of non-adhesive surface in the presence of molecular oxygen by radical initiator, it comprises that can carry out crosslinked polymer by radical initiator mixes with composition claimed in claim 2.

17. one kind prepares the method that can be solidified into the curable compositions of non-adhesive surface in the presence of molecular oxygen by radical initiator, it is included in radical initiator and exists lower mixing energy to carry out crosslinked polymer by the radical initiator that contains the described composition of claim 1.

18. composition as claimed in claim 1, wherein said compound (A) is selected from one or more dimaleimides, and compound (B) is selected from four sulfuration dialkyl group thiurams, four sulfuration diaryl thiurams, curing alkyl phenol, single sulfuration tetraalkyl thiuram, single sulfuration four aryl thiurams and their mixture.

19. composition as claimed in claim 2, wherein said radical initiator is selected from dialkyl peroxide or peroxy ketal.

20. composition as claimed in claim 18, it also contains the radical initiator that is selected from dialkyl peroxide or peroxy ketal.

21. composition as claimed in claim 1, wherein said compound (A) is selected from one or more dimaleimides, compound (B) is selected from 4,4-dithiomorpholine, non-annularity alkyl-2-[4-morpholinodithio sulfenamide, cycloalkyl-2-[4-morpholinodithio sulfenamide, aryl-2-[4-morpholinodithio sulfenamide, curing alkyl phenol and their mixture.

22. composition as claimed in claim 21, it also contains the radical initiator that is selected from dialkyl peroxide or peroxy ketal.

23. composition as claimed in claim 2, it contains dicumyl peroxide, N, N-phenylene dimaleimide, 4,4-dithiomorpholine, curing alkyl phenol and N-cyclohexyl-2-[4-morpholinodithio sulfenamide.

24. composition as claimed in claim 2, it contains dicumyl peroxide, N, N-phenylene dimaleimide, bis-pentamethylenethiuram tetrasulfide, curing alkyl phenol and single sulfuration tetra methylthiuram.

25. composition as claimed in claim 2, it contains dicumyl peroxide, N, N-phenylene dimaleimide, bis-pentamethylenethiuram tetrasulfide, curing alkyl phenol and the N-tert-butyl group-benzothiazole-2-sulfenimide.

26. composition as claimed in claim 1, it is mixed with masterbatch at the carrier that is selected from microwax, polycaprolactone, EPDM, EPM, EVA, PE and composition thereof.

27. composition as claimed in claim 2, it is mixed with masterbatch at the carrier that is selected from microwax, polycaprolactone, EPDM, EPM, EVA, PE and composition thereof.