CA1131384A - Curable blends of chloroprene polymer and ethylene copolymer - Google Patents
Curable blends of chloroprene polymer and ethylene copolymerInfo
- Publication number
- CA1131384A CA1131384A CA334,515A CA334515A CA1131384A CA 1131384 A CA1131384 A CA 1131384A CA 334515 A CA334515 A CA 334515A CA 1131384 A CA1131384 A CA 1131384A
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- Canada
- Prior art keywords
- ethylene
- curable blend
- weight
- carbon monoxide
- parts
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L11/00—Compositions of homopolymers or copolymers of chloroprene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L81/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur with or without nitrogen, oxygen or carbon only; Compositions of polysulfones; Compositions of derivatives of such polymers
- C08L81/06—Polysulfones; Polyethersulfones
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/08—Copolymers of ethene
- C08L23/0846—Copolymers of ethene with unsaturated hydrocarbons containing atoms other than carbon or hydrogen
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Polyethers (AREA)
- Polymers With Sulfur, Phosphorus Or Metals In The Main Chain (AREA)
Abstract
TITLE
Curable Blends of Chloroprene Polymer and Ethylene Copolymer ABSTRACT OF THE DISCLOSURE
Curable blends of chloroprene polymers are obtained by modification with ethylene/carbon monoxide or sulfur dioxide copolymers containing an additional softening copolymerizable comonomer such as vinyl esters, alkyl acrylates and methacrylates, alkyl vinyl ether, acrylonitrile, methacrylonitrile etc. Modification with the ethylene copolymers results in improved pro-cessing, increased resistance-to-ozone and reduced cost.
Curable Blends of Chloroprene Polymer and Ethylene Copolymer ABSTRACT OF THE DISCLOSURE
Curable blends of chloroprene polymers are obtained by modification with ethylene/carbon monoxide or sulfur dioxide copolymers containing an additional softening copolymerizable comonomer such as vinyl esters, alkyl acrylates and methacrylates, alkyl vinyl ether, acrylonitrile, methacrylonitrile etc. Modification with the ethylene copolymers results in improved pro-cessing, increased resistance-to-ozone and reduced cost.
Description
11~13~4 _ TITLE
Curable Blends of Chloroprene Polymer and Ethylene Copolymer BACKGROUND OF THE INVENTION
Field Of The Invention ... . . . ..... . . , ., _ . _ .. _ .. ... . .
This invention relates to curable blends and more specifically, it relates to improved curable blends of chloroprene polymer and eth~lene copolymer.
.. . , . . . , .. ., _, . . . . . ,, , . , ~ , ~ , . . . ,, . . . . _ . _ _ _ . . .
~escrlpl on O~ Tne Prlor Art Elastomers are frequently compounded with softeners and plasticizers to extend their applicability to different end uses. ~any of these softeners are liquids which can volatilize on exposure of the compound to elevated temperatures or can be extracted when the compound is exposed to solvents or oils. More permanent polymeric liquid plasticizers are relatively expensive.
Research Disclosure No. 13816, dated October, 1975, discloses that the oil resistance of chlorQsul-fonated polyethylene was found to be significantly improved for blends in which a terpolymer (30-45 wt. %
terpolymer based on the elastomer) of ethylene/carbon monoxide/vinyl acetate was used in place of ethylene/
vinyl acetate copolymer. It is also stated therein that sealants with excellent tac~ and rubberiness wereobtained with blends of an ethylene/carbon monoxide/vinyl acetate terpolymer with buty; rubber.
U.S. 3,780,140 discloses terpol~mers of ~' 3~34 ethylene/carbon monoxide/termonomer and ~lends of same with a compatible amount of at least one solid organic polymer. Various termonomers are disclosed, such as unsaturated mono- and dicarboxylic acids, esters of such acids, vinyl esters of saturated carboxylic acids, vinyl alkyl ethers, acrylonitrile, etc. Solid organic polymers are disclosed to have preferably polar charac-teristics in order to obtain compatibility on a molecular scale. Such polymers can be polyamides, cellulose derived polymers; vinyl halide polymers;
alpha-olefin based polymers such as polyethylene, poly-propylene, chlorosulfonated polyethylene; ethylene-vinyl ester copolymers; polymers of styrene; polymers of acrylonitrile and copolymers of at least 40% acrylonitrile and other ethylenically unsaturated comonomers such as vinyl acetate, vinyl chloride and isobutylene; acrylics, polyesters; polyurethanes; polycarbonates; phenolics;
polysulfones; epoxy resin; chlorinated polyethers; alkyd resins; acetal resins; ABS resins; silicone resins;
tars; waxes; etc.
U.S. 2,495,286 discloses copolymers of ethy-lene and carbon monoxide with one or more additional polymerizable organic compound such as other olefins, butadienes, vinyl and vinylidene compounds, vinyl esters, styrene, acrylic and methacrylic acids and their esters, etc.
U.S. 3,873,494 discloses curable blends and vulcanizates of 100 parts of an ethylene/alkyl acrylate or alkyl methacrylate copolymer or an ethylene/alkyl acrylate or methacrylate terpolymer wherein the termon-omer among others can be carbon monoxide, with 1-30 parts of a butadiene/acrylonitrile polymer. The termonomer is present in an amount not higher than about 10 wt. percent of the terpolymer.
SUMMARY OF THE INVENTION
-According to the present invention there is provided a curable blend of ta) 100 parts of a 11313~34 chloroprene polymer and (b) about 3-100 parts of an ethylene copolymer selected from the group consisting of ethylene/carbon monoxide/X and ethylene/sulfur dioxide/
X copolymers, wherein comonomer X is (I) a vinyl ester of an alkanoic acid, the acid having 1 to 18 C atoms, (II) an alkyl acrylate or methacrylate, the alkyl group having 1 to 18 C atoms~(III)analkyl vinyl ether, the alkyl group having 1 to 4 C atoms, (IV) acrylonitrile or methacrylonitrile, or combinations of the above comonomers, the ethylene copolymer containing about 3-25 weight % of carbon monoxide or sulfur dioxide, about 10-65 weight ~ o~ comonomerX, and about 30-75 weight % of ethylene.
Further provided according to the present invention are compositions comprising the above curable blends combined with peroxide or sulfur curing system.
Still further provided according to the present invention are vulcanized products obtained by heating the combination of the above indicated curable blends and peroxide or sulfur curing systems.
Detailed Description Of The Invention It has been found that the modification of curable blend~ of chl~r~prene polymers wlth an ethylene/
carbon monoxide or sulfur dioxide copolymer containing at least one additional softening copolymerizable comonomer such as a vinyl ester, alkyl acrylate or methacrylate, acrylonitrile, etc., results in vulcanizates with improved processing, increased resistance to ozone, and reduced cost.
As a result of the above indicated improved characteristics, these modified vulcanizates can be employed in extruded shapes, such as tubing, gasketing, and electrical cable coverings; in composite structures such as fabric-reinforced hose, belting, and coated sheet; in shoe soling compounds, including cellular materials; and miscellaneous molded goods such as seals and O-rings.
1~313~4 The solid chloroprene polymer (neoprene) which is the main component of the blends of the present invention is a well known material. It can be made, for example, by emulsion polymerization using a free-radical catalyst. Several publications give extensive discussions of this technology, including see article titled "Polychloroprene Rubber," by P. R. Johnson, in "Rubber Chemistry and Technology," Vol. 49, No. 3, July-August, 1976; "Encyclopedia of Polymer Science and Technology," Vol. 3; "The Neoprenes," by R. M. Murray and D. C. Thompson (Elastomer Chemicals Department, Du Pont Company, trade literature). In addition to homo-polymers of chloroprene, copolymers, particularly those with 2,3-dichloro-1,3-butadiene, are useful in the compositions of this invention. For practical purposes, suitable chloroprene polymers are available commercially.
The ethylene copolymer modifier of the present invention is an ethylene carbon monoxide or sulfur dioxide copolymer containing at least one additional softening copolymerizable comonomer such as (a) vinyl esters of an alkanoic acid, the acid having 1 to 18 carbon atoms, e.g., vinyl formate, vinyl acetate, and vinyl stearate,(b) alkyl aerylates or methacrylates, the alkyl group having 1 to 18 carbon atoms, e.g., methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methaerylate, ethylhexyl acrylate, and steary]
aerylate, (e~ an alkyl vinyl ether, the alkyl group having 1 to 4 carbon atoms, (d) acrylonitrile, meth-acrylonitrile or eombinations of the above eomonomers.
The earbon monoxide or sulfur dioxide component of the ethylene copolymer of the present invention should be present in the amount of about 3-25 wt. %, preferably about 6-15 wt. %.
The additional softening copolymerizable comonomer component of the ethylene copolymer of the ~, 3~4 present invention can be present in about 10-65 wt. %, preferably about 20-35 wt. %.
The amount of ethylene in the copolymer should be about 30-75 weight %, preferably about 50 to 70 weight ~.
In these copolymers, copolymerized carbon monoxide or sulfur dioxide confers a high degree of polarity to the polymer without unduly reducing the ethylene content of the polymer. For instance, 1 weight % of copolymerized carbon monoxide confers polarity to the polymer equivalent to 3 to 5 weight % of a repre-sentative comonomer X, e.g., vinyl acetate, methyl acrylate, or 2-ethylhexyl acrylate. This property is important for several reasons: (a) at relatively high ethylene content, such pol~ers have sufficient polarity to be compatible with the neoprene rubber,and (b) at a given level of polarity, copolymers containing co~olymerized CO or SO2 are less sticky than those which contain only ethylene and comonomer X and are thus more easily processed because of reduced sticking to the surfaces of processing equipment.
The amount of ethylene copolymer in the blends of the present invention is about 3-100 partsjpreferably about 5-50 parts, per 100 parts of chloroprene polymer.
The chloroprene polymer and the ethylene copolymer can be mixed uniformly with any of the usual mixing devices such as a roll mill, extruder, Banbury mixer, or other internal mixing device which is capable of mixing the materials without undue heating of the mixture. Other compounding ingredients well-known and used in elastomer compounds can also be added. Solid additives include reinforcing agents, fillers,pigments, andresins. Examples of such materials are carbon black, silica, calcium carbonate and titanium dioxide, hydro-~5 carbon resins, and phenolic resins. Liquid additives `" 1~;~131~34 include processing oils and plasticizers, both monomericand polymeric, and liquid neoprene rubber.
Other materials such as stabilizers, anti-oxidants, antiozonants, lubricants, release agents, and additives that improve certain properties of the compound can be added in minor proportions.
Vulcanization of the blends is accomplished by known means. The chemical vulcanizing agents can be added in a Banbury mixer, a roll mill, or other mixing device under conditions which avoid premature curing ! of the compound. While co-curing of the chloroprene polymer and the ethylene/carbon monoxide or sulfur dioxide copolymer ingredient of this composition may give superior properties, it is not an essential part of this invention.
Chemical agents usually employed for vulcaniza-tion of chloroprene polymers are satisfactory for curing the blends of the present invention.
Typical curing agents include combinations of zinc and magnesium oxides, alone or with organic accelerators; sulfur donor or sulfur/accelerator systems;
and peroxides. Curing of neoprene rubber is known in the art. Previously cited references, plus Chapter 13 of "Rubber Technology," by Maurice Morton, second edition, contain discussions of this subject. In addi-tion, commercial literature from the Elastomer Chemicals Department of Du Pont Company provide more detailed information. Pertinent bulletins include: "Curing Systems for Neoprene," Bulletin No. SD-235, December 13, 1976; "Hexamethylenetetramine/TMTD/Polyethylene Glycol -A Nonthiourea Cure System for Neoprene," Bulletin SD-234, Nov. 1976; "NA-22F - An Accelerator for Polychloroprene Rubber," No. 69, Bulletin E-17790.
Polychloroprene polymers behave differently from other diene elastomers in curing reactions. The presence of the chlorine atom deactivates the double ~' 11313~34 bonds of the polymer, limiting direct sulfur vulcaniza-tion. Also, allyl chloride structures in the polymer function as major crosslinking sites by reaction with metal oxides, which are a necessary part of cure systems, or with polyfunctional nitrogen compounds such as finely divided hexamethylene tetramine. Thioureas such as tetramethyl thiourea and especially ethylene thiourea are accelerators that permit shorter curing times and often yield vulcanizate properties not otherwise avail-able by increasing curing time or temperature.
To improve processing safety, mercaptobenzo-thiazyl sulfide, tetraethylthiuram disulfide, or poly-(ethylene oxide) glycol can be used asretarder-activators.
The amounts of accelerator and retarder-activator can be varied over a wide range depending on the particular chemical composition, the accelerator, the retarder-activator, and the intended use of the vulcanizate.
Generally, the amounts of accelerator and retarder-activator used will range from 0.2 to 4, preferably 0.5 to 2, parts per 100 parts of chloroprene polymer.
Peroxide curing agents (100% active basis) are also employed in the same ranges of use.
The final composition is shaped by known means, such as extrusion, injection molding, compression molding, transfer molding, or calendering into a sheet or onto a substrate, and cured. Steam, hot fluid, or microwave heating can be used for their curing, generally at temperatures from about 100 to 210C for about 0.5 to 120 minutes.
The following examples are given for the purpose of illustrating the present invention;
all parts and percent~ges are by weight unless otherwise specified.
11;~13~34 Examples 1-3 These examples illustrate the use of nitrogen-containing compounds to accelerate the cure of neoprene rubber compositions modified with E/VA/CO or E/MA/CO
copolymers. Compositions and properties are summarized in Table Io It should be noted that the compound of Example 2, modified with E/MA/CO, has greater scorch safety; and, while the ODR torque does not reach as high a level as that of the compound of Example 1 containing E/VA/CO, the tensile properties are superior and the compound is softer.
11;~1384 TABLE I
-MODIFIED NEOPRENE COMPOUNDS
- ~xample 5 Ingredients (parts_by weight) 1 2 3 "Neoprene" W (1) E/26.6~ MA/6.7% CO, 2.5 MI -- 30 --E/23% VA/ll~ CO, 35 MI 30 -- 30 SRF Black 35 35 35 Aromatic Processing Oil 10 10 --Low Molecular-Weight Polyethylene 2 2 2 Magnesium Oxide 3 3 4 Zinc Oxide 5 5 5 Octylated Diphenylamine 2 2 2 Hexamethylene Tetramine/~inder 1 5 5 dispersion (65/35) 1.5 . 1.
Poly(Ethylene Oxide)Glycol, 2 ~000 Mol. Wt. 2 Tetraethyl Thiuram Disulfide 1 1 --Di-Orthotolyl Guanidine Compound Properties Mooney Scorch @ 121C., 21 30+ 18 Time to 5-Point Rise, Min.
ODR Torque @ 30 Min., 162C., 62 35 74 Lb.-In.
Cured 20 Min. @ 162C.
Tensile Strength, MPa 13.6 14.4 14.5 Elongation, ~ 290 440 300 Modulus @ 100% Stress, MPa 3.4 1.8 4.3 Shore A Hardness,points 72 63 78 (1) polychloroprene availa~le from E- r . ~U Pn~-de Nemours & Company, having a Mooney Viscosity of 50.
11~i1384 Control Example C~ and Example 4 These examples illustrate the utility of E/VA/CO copolymer in the modification of chloroprene~olymer.
The recipes for these examples are as follows, in parts by weight: Binder, 100; SRF carbon black, 80; aromatic process oil, 30; octylated diphenylamine antioxidant, 2; low molecular-weight polyethylene, 2; stearic acid 0.5; di-ortho-tolyl guanidine, 0.75; tetramethyl thiuram monosulfide, 0.75;
sulfur, 1.0; and zinc oxide, 5. In Control E~ample Cl, the binder is 100 parts of chloroprene polymer ("Neoprene"
, . .. . , _ . , _ ................. . .. . _ .. .. _ . .. .
WHV, 120 Mooney viscosity~ and in E~ample 4, the binder is 75 parts of "Neoprene" WHV and 25 parts of the E/VA/CO
. . ,.. _ _ ~ . .......... .. .. .. .
copolymer of Example 1. The properties of the vulcaniz-ates of these two compounds are shown in Table II.Benefits obtained by use of the E~VA/CO copolymer include reduced cost, improved processing, increased resistance to ozone, and reduced compression set. The binder of Example 4 was made up in the form of a masterbatch and an appropriate portion of the masterbatch was then used for ~ach compounding.
TABLE II
NEOPRENE AND NEOPRENE - _~A~CQ
Properties Cl Example 4 M~oney Viscosity, ML - 4 76 56 Mooney Scorch, ~5, Minutes ~30 11 10 Tensile Str~ngth, MPa 19.0 17.2 Elongation, % 330 270 Shore A Hardness, Points 71 79 Compression Set, % 61 52 (22 hrs. @ 100C.) Ozone Resistance Cracked Very Few 15 (Bent Loop, 24 hrs. @ 100 pphm) Small Cracks Molded Surface Rating Good Very Good Tear Stxength, Die "C" N/mm. 42 35 38~
Control Example C~ and Examples 5-6 These examples are, respectively, a control example, a thiourea-accelerated thiuram cure system, and a peroxide cure system. All stocks contain SRF
carbon black, 35 parts; low molecular-weight polyethy-lene luhricant, 2 parts; octylated diphenylamine anti-oxidant, 2 parts; magnesium oxide acid acceptorv 4 parts;
and zinc oxide acid acceptor/activator, 5 parts. The different binder systems and curing agents employed in these examples are shown in Table III.
As shown by the data in Table III, the use of the E/VA/CO terpolymer in a neoprene compound gives a lower processing viscosity and a vulcanizate with lower tensile strength and higher hardness. With peroxide curing, scorch time is double that of a sulfur cure system for the modified compounds and is thus safer.
The tensile strength, percent elongation, and compression set of the peroxide vulcanizate are superior to that of the sulfur vulcanizate.
1~313~
TABI,E III
COMPARISON OF SULFUR AND PEROXIDE CURE
Example Ingredients (parts by weight) C2 5 6 "Neoprene" W 100 70 70 E/23.5%VA/11% CO, 35 MI - 30 30
Curable Blends of Chloroprene Polymer and Ethylene Copolymer BACKGROUND OF THE INVENTION
Field Of The Invention ... . . . ..... . . , ., _ . _ .. _ .. ... . .
This invention relates to curable blends and more specifically, it relates to improved curable blends of chloroprene polymer and eth~lene copolymer.
.. . , . . . , .. ., _, . . . . . ,, , . , ~ , ~ , . . . ,, . . . . _ . _ _ _ . . .
~escrlpl on O~ Tne Prlor Art Elastomers are frequently compounded with softeners and plasticizers to extend their applicability to different end uses. ~any of these softeners are liquids which can volatilize on exposure of the compound to elevated temperatures or can be extracted when the compound is exposed to solvents or oils. More permanent polymeric liquid plasticizers are relatively expensive.
Research Disclosure No. 13816, dated October, 1975, discloses that the oil resistance of chlorQsul-fonated polyethylene was found to be significantly improved for blends in which a terpolymer (30-45 wt. %
terpolymer based on the elastomer) of ethylene/carbon monoxide/vinyl acetate was used in place of ethylene/
vinyl acetate copolymer. It is also stated therein that sealants with excellent tac~ and rubberiness wereobtained with blends of an ethylene/carbon monoxide/vinyl acetate terpolymer with buty; rubber.
U.S. 3,780,140 discloses terpol~mers of ~' 3~34 ethylene/carbon monoxide/termonomer and ~lends of same with a compatible amount of at least one solid organic polymer. Various termonomers are disclosed, such as unsaturated mono- and dicarboxylic acids, esters of such acids, vinyl esters of saturated carboxylic acids, vinyl alkyl ethers, acrylonitrile, etc. Solid organic polymers are disclosed to have preferably polar charac-teristics in order to obtain compatibility on a molecular scale. Such polymers can be polyamides, cellulose derived polymers; vinyl halide polymers;
alpha-olefin based polymers such as polyethylene, poly-propylene, chlorosulfonated polyethylene; ethylene-vinyl ester copolymers; polymers of styrene; polymers of acrylonitrile and copolymers of at least 40% acrylonitrile and other ethylenically unsaturated comonomers such as vinyl acetate, vinyl chloride and isobutylene; acrylics, polyesters; polyurethanes; polycarbonates; phenolics;
polysulfones; epoxy resin; chlorinated polyethers; alkyd resins; acetal resins; ABS resins; silicone resins;
tars; waxes; etc.
U.S. 2,495,286 discloses copolymers of ethy-lene and carbon monoxide with one or more additional polymerizable organic compound such as other olefins, butadienes, vinyl and vinylidene compounds, vinyl esters, styrene, acrylic and methacrylic acids and their esters, etc.
U.S. 3,873,494 discloses curable blends and vulcanizates of 100 parts of an ethylene/alkyl acrylate or alkyl methacrylate copolymer or an ethylene/alkyl acrylate or methacrylate terpolymer wherein the termon-omer among others can be carbon monoxide, with 1-30 parts of a butadiene/acrylonitrile polymer. The termonomer is present in an amount not higher than about 10 wt. percent of the terpolymer.
SUMMARY OF THE INVENTION
-According to the present invention there is provided a curable blend of ta) 100 parts of a 11313~34 chloroprene polymer and (b) about 3-100 parts of an ethylene copolymer selected from the group consisting of ethylene/carbon monoxide/X and ethylene/sulfur dioxide/
X copolymers, wherein comonomer X is (I) a vinyl ester of an alkanoic acid, the acid having 1 to 18 C atoms, (II) an alkyl acrylate or methacrylate, the alkyl group having 1 to 18 C atoms~(III)analkyl vinyl ether, the alkyl group having 1 to 4 C atoms, (IV) acrylonitrile or methacrylonitrile, or combinations of the above comonomers, the ethylene copolymer containing about 3-25 weight % of carbon monoxide or sulfur dioxide, about 10-65 weight ~ o~ comonomerX, and about 30-75 weight % of ethylene.
Further provided according to the present invention are compositions comprising the above curable blends combined with peroxide or sulfur curing system.
Still further provided according to the present invention are vulcanized products obtained by heating the combination of the above indicated curable blends and peroxide or sulfur curing systems.
Detailed Description Of The Invention It has been found that the modification of curable blend~ of chl~r~prene polymers wlth an ethylene/
carbon monoxide or sulfur dioxide copolymer containing at least one additional softening copolymerizable comonomer such as a vinyl ester, alkyl acrylate or methacrylate, acrylonitrile, etc., results in vulcanizates with improved processing, increased resistance to ozone, and reduced cost.
As a result of the above indicated improved characteristics, these modified vulcanizates can be employed in extruded shapes, such as tubing, gasketing, and electrical cable coverings; in composite structures such as fabric-reinforced hose, belting, and coated sheet; in shoe soling compounds, including cellular materials; and miscellaneous molded goods such as seals and O-rings.
1~313~4 The solid chloroprene polymer (neoprene) which is the main component of the blends of the present invention is a well known material. It can be made, for example, by emulsion polymerization using a free-radical catalyst. Several publications give extensive discussions of this technology, including see article titled "Polychloroprene Rubber," by P. R. Johnson, in "Rubber Chemistry and Technology," Vol. 49, No. 3, July-August, 1976; "Encyclopedia of Polymer Science and Technology," Vol. 3; "The Neoprenes," by R. M. Murray and D. C. Thompson (Elastomer Chemicals Department, Du Pont Company, trade literature). In addition to homo-polymers of chloroprene, copolymers, particularly those with 2,3-dichloro-1,3-butadiene, are useful in the compositions of this invention. For practical purposes, suitable chloroprene polymers are available commercially.
The ethylene copolymer modifier of the present invention is an ethylene carbon monoxide or sulfur dioxide copolymer containing at least one additional softening copolymerizable comonomer such as (a) vinyl esters of an alkanoic acid, the acid having 1 to 18 carbon atoms, e.g., vinyl formate, vinyl acetate, and vinyl stearate,(b) alkyl aerylates or methacrylates, the alkyl group having 1 to 18 carbon atoms, e.g., methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methaerylate, ethylhexyl acrylate, and steary]
aerylate, (e~ an alkyl vinyl ether, the alkyl group having 1 to 4 carbon atoms, (d) acrylonitrile, meth-acrylonitrile or eombinations of the above eomonomers.
The earbon monoxide or sulfur dioxide component of the ethylene copolymer of the present invention should be present in the amount of about 3-25 wt. %, preferably about 6-15 wt. %.
The additional softening copolymerizable comonomer component of the ethylene copolymer of the ~, 3~4 present invention can be present in about 10-65 wt. %, preferably about 20-35 wt. %.
The amount of ethylene in the copolymer should be about 30-75 weight %, preferably about 50 to 70 weight ~.
In these copolymers, copolymerized carbon monoxide or sulfur dioxide confers a high degree of polarity to the polymer without unduly reducing the ethylene content of the polymer. For instance, 1 weight % of copolymerized carbon monoxide confers polarity to the polymer equivalent to 3 to 5 weight % of a repre-sentative comonomer X, e.g., vinyl acetate, methyl acrylate, or 2-ethylhexyl acrylate. This property is important for several reasons: (a) at relatively high ethylene content, such pol~ers have sufficient polarity to be compatible with the neoprene rubber,and (b) at a given level of polarity, copolymers containing co~olymerized CO or SO2 are less sticky than those which contain only ethylene and comonomer X and are thus more easily processed because of reduced sticking to the surfaces of processing equipment.
The amount of ethylene copolymer in the blends of the present invention is about 3-100 partsjpreferably about 5-50 parts, per 100 parts of chloroprene polymer.
The chloroprene polymer and the ethylene copolymer can be mixed uniformly with any of the usual mixing devices such as a roll mill, extruder, Banbury mixer, or other internal mixing device which is capable of mixing the materials without undue heating of the mixture. Other compounding ingredients well-known and used in elastomer compounds can also be added. Solid additives include reinforcing agents, fillers,pigments, andresins. Examples of such materials are carbon black, silica, calcium carbonate and titanium dioxide, hydro-~5 carbon resins, and phenolic resins. Liquid additives `" 1~;~131~34 include processing oils and plasticizers, both monomericand polymeric, and liquid neoprene rubber.
Other materials such as stabilizers, anti-oxidants, antiozonants, lubricants, release agents, and additives that improve certain properties of the compound can be added in minor proportions.
Vulcanization of the blends is accomplished by known means. The chemical vulcanizing agents can be added in a Banbury mixer, a roll mill, or other mixing device under conditions which avoid premature curing ! of the compound. While co-curing of the chloroprene polymer and the ethylene/carbon monoxide or sulfur dioxide copolymer ingredient of this composition may give superior properties, it is not an essential part of this invention.
Chemical agents usually employed for vulcaniza-tion of chloroprene polymers are satisfactory for curing the blends of the present invention.
Typical curing agents include combinations of zinc and magnesium oxides, alone or with organic accelerators; sulfur donor or sulfur/accelerator systems;
and peroxides. Curing of neoprene rubber is known in the art. Previously cited references, plus Chapter 13 of "Rubber Technology," by Maurice Morton, second edition, contain discussions of this subject. In addi-tion, commercial literature from the Elastomer Chemicals Department of Du Pont Company provide more detailed information. Pertinent bulletins include: "Curing Systems for Neoprene," Bulletin No. SD-235, December 13, 1976; "Hexamethylenetetramine/TMTD/Polyethylene Glycol -A Nonthiourea Cure System for Neoprene," Bulletin SD-234, Nov. 1976; "NA-22F - An Accelerator for Polychloroprene Rubber," No. 69, Bulletin E-17790.
Polychloroprene polymers behave differently from other diene elastomers in curing reactions. The presence of the chlorine atom deactivates the double ~' 11313~34 bonds of the polymer, limiting direct sulfur vulcaniza-tion. Also, allyl chloride structures in the polymer function as major crosslinking sites by reaction with metal oxides, which are a necessary part of cure systems, or with polyfunctional nitrogen compounds such as finely divided hexamethylene tetramine. Thioureas such as tetramethyl thiourea and especially ethylene thiourea are accelerators that permit shorter curing times and often yield vulcanizate properties not otherwise avail-able by increasing curing time or temperature.
To improve processing safety, mercaptobenzo-thiazyl sulfide, tetraethylthiuram disulfide, or poly-(ethylene oxide) glycol can be used asretarder-activators.
The amounts of accelerator and retarder-activator can be varied over a wide range depending on the particular chemical composition, the accelerator, the retarder-activator, and the intended use of the vulcanizate.
Generally, the amounts of accelerator and retarder-activator used will range from 0.2 to 4, preferably 0.5 to 2, parts per 100 parts of chloroprene polymer.
Peroxide curing agents (100% active basis) are also employed in the same ranges of use.
The final composition is shaped by known means, such as extrusion, injection molding, compression molding, transfer molding, or calendering into a sheet or onto a substrate, and cured. Steam, hot fluid, or microwave heating can be used for their curing, generally at temperatures from about 100 to 210C for about 0.5 to 120 minutes.
The following examples are given for the purpose of illustrating the present invention;
all parts and percent~ges are by weight unless otherwise specified.
11;~13~34 Examples 1-3 These examples illustrate the use of nitrogen-containing compounds to accelerate the cure of neoprene rubber compositions modified with E/VA/CO or E/MA/CO
copolymers. Compositions and properties are summarized in Table Io It should be noted that the compound of Example 2, modified with E/MA/CO, has greater scorch safety; and, while the ODR torque does not reach as high a level as that of the compound of Example 1 containing E/VA/CO, the tensile properties are superior and the compound is softer.
11;~1384 TABLE I
-MODIFIED NEOPRENE COMPOUNDS
- ~xample 5 Ingredients (parts_by weight) 1 2 3 "Neoprene" W (1) E/26.6~ MA/6.7% CO, 2.5 MI -- 30 --E/23% VA/ll~ CO, 35 MI 30 -- 30 SRF Black 35 35 35 Aromatic Processing Oil 10 10 --Low Molecular-Weight Polyethylene 2 2 2 Magnesium Oxide 3 3 4 Zinc Oxide 5 5 5 Octylated Diphenylamine 2 2 2 Hexamethylene Tetramine/~inder 1 5 5 dispersion (65/35) 1.5 . 1.
Poly(Ethylene Oxide)Glycol, 2 ~000 Mol. Wt. 2 Tetraethyl Thiuram Disulfide 1 1 --Di-Orthotolyl Guanidine Compound Properties Mooney Scorch @ 121C., 21 30+ 18 Time to 5-Point Rise, Min.
ODR Torque @ 30 Min., 162C., 62 35 74 Lb.-In.
Cured 20 Min. @ 162C.
Tensile Strength, MPa 13.6 14.4 14.5 Elongation, ~ 290 440 300 Modulus @ 100% Stress, MPa 3.4 1.8 4.3 Shore A Hardness,points 72 63 78 (1) polychloroprene availa~le from E- r . ~U Pn~-de Nemours & Company, having a Mooney Viscosity of 50.
11~i1384 Control Example C~ and Example 4 These examples illustrate the utility of E/VA/CO copolymer in the modification of chloroprene~olymer.
The recipes for these examples are as follows, in parts by weight: Binder, 100; SRF carbon black, 80; aromatic process oil, 30; octylated diphenylamine antioxidant, 2; low molecular-weight polyethylene, 2; stearic acid 0.5; di-ortho-tolyl guanidine, 0.75; tetramethyl thiuram monosulfide, 0.75;
sulfur, 1.0; and zinc oxide, 5. In Control E~ample Cl, the binder is 100 parts of chloroprene polymer ("Neoprene"
, . .. . , _ . , _ ................. . .. . _ .. .. _ . .. .
WHV, 120 Mooney viscosity~ and in E~ample 4, the binder is 75 parts of "Neoprene" WHV and 25 parts of the E/VA/CO
. . ,.. _ _ ~ . .......... .. .. .. .
copolymer of Example 1. The properties of the vulcaniz-ates of these two compounds are shown in Table II.Benefits obtained by use of the E~VA/CO copolymer include reduced cost, improved processing, increased resistance to ozone, and reduced compression set. The binder of Example 4 was made up in the form of a masterbatch and an appropriate portion of the masterbatch was then used for ~ach compounding.
TABLE II
NEOPRENE AND NEOPRENE - _~A~CQ
Properties Cl Example 4 M~oney Viscosity, ML - 4 76 56 Mooney Scorch, ~5, Minutes ~30 11 10 Tensile Str~ngth, MPa 19.0 17.2 Elongation, % 330 270 Shore A Hardness, Points 71 79 Compression Set, % 61 52 (22 hrs. @ 100C.) Ozone Resistance Cracked Very Few 15 (Bent Loop, 24 hrs. @ 100 pphm) Small Cracks Molded Surface Rating Good Very Good Tear Stxength, Die "C" N/mm. 42 35 38~
Control Example C~ and Examples 5-6 These examples are, respectively, a control example, a thiourea-accelerated thiuram cure system, and a peroxide cure system. All stocks contain SRF
carbon black, 35 parts; low molecular-weight polyethy-lene luhricant, 2 parts; octylated diphenylamine anti-oxidant, 2 parts; magnesium oxide acid acceptorv 4 parts;
and zinc oxide acid acceptor/activator, 5 parts. The different binder systems and curing agents employed in these examples are shown in Table III.
As shown by the data in Table III, the use of the E/VA/CO terpolymer in a neoprene compound gives a lower processing viscosity and a vulcanizate with lower tensile strength and higher hardness. With peroxide curing, scorch time is double that of a sulfur cure system for the modified compounds and is thus safer.
The tensile strength, percent elongation, and compression set of the peroxide vulcanizate are superior to that of the sulfur vulcanizate.
1~313~
TABI,E III
COMPARISON OF SULFUR AND PEROXIDE CURE
Example Ingredients (parts by weight) C2 5 6 "Neoprene" W 100 70 70 E/23.5%VA/11% CO, 35 MI - 30 30
2-Mercaptoimidazoline (ethylenethiourea)/Ethy lene/propylene rubber dispersion (75/25) 0,75 0.75 Tetramethylenethiuram Monosulfide 0.75 0.75 bis(butylperoxy) dissopropylbenzene Burgess KE*Clay (40/60) - - 1.5 SRF Black 35 35 35 Low molecular weight polyethylene 2 2 2 Magnesium Oxide 4 4 4 Zinc Oxide 5 5 5 Octylated Diphenylamine 2 2 2 Mooney Scorch, at 121C.
Minimum Viscosity 25 18 18 Time to 5 pt. rise, min.16 20 40 ODR Cure at 162C. (30 min.) Maximum Torque, L~. - In.77 43 44 Time to 90% of max., minutes 3.55 0 5.5 Cured Properties (162C., 15 min.) Tensile Strength, MPa21.4 15.8 16.5 Modules 2.9 3.4 3,1 Elongation % 430 430 470 Shore A Hardness, Points68 77 76 Compression Set (cured 162C., 20 min.) 22 HR. at 100C.
Method B of ASTM D395 % 39 52 40 *Denotes trade mark ~3~3~34 Control Example C3 and Examples 7-8 All stocks contain 35 parts of SRF carbon black, 2 parts of low molecular weight polyethylen~
4 parts of magnesium oxide, 2 parts of octylated diphenylamine, 5 parts of zinc oxide, 1 part of poly(ethylene oxide) glycol, 1 part of tetraethylth~ram disulfide, and 1.5 parts of hexamethylene tetramine/
binder dispersion (65/35). Additional ingredients in each compound are shown in Table IV with data on the properties of the blends and their vulcanizates. The use of E/VA/CO in compounds 7 and 8 shows again the surprising results that ozone resistance and resistance to ASTM #3 oil are improved over the base neoprene compound. The compound of Example 8, modified with dioct~l-sebacate,a low-temperature plasticizer, shows good response. Improvement in both resistance to impact at low temperatures and to stiffening is obtained.
TABLE IV
.... _ .
ESTER PLASTICIZER MODIFICATION
Example Ingredients (parts by weiqht)_ 7 8 "Neoprene" W - 100 70 70 E/23.5~ VA/11% CO, 35 MI - 30 30 Aromatic Processing Oil20 20 Dioctyl Sebacate - - 30 SRF Black 35 35 35 Low molecular wt. polyethylene 2 2 2 Magnesium Oxide 4 4 4 Zinc Oxide 5 5 5 octylated Diphenylamine 2 2 2 Hexamethylene Tetramine/1.51.5 1.5 Binder dispersion (65/35) Poly(Ethylene Oxide)Glycol, 4000 Mol. Wt.
Tetraethyl Thiuram Disul~ide Mooney Scorch, @ 121C.
Minimum Viscosity 12 8 5 Time to 5 pt. rise, min.25 20 32 ODR Cure, 162C. (30 Min.) Maximum Torque,Lb. - In.48 56 39 Time to 90~ of max., minutes 18 20 22 Cured Properties (162C., 20 min.) Tensile Strength, MPa17.913.1 10.3 Modulus@ 100% Stress, MPa 1.5 2.5 2.1 Elongation, % 500 290 280 Shore A Hardness, Points 52 62 56 Comp~es~ion Set (162C., 25 min.) 22 Hr. @ 100C., Method B of AS~M D 395 .
% 29 40 47 Ozone Exposure, lppm O3, 30% Elongation, 4 days no no Surface Appearance cracks cracks cracks TABLE IV (Cont'd.) Properties C3 7 8 Volume Increase,70 Hr. @ 100C., ASTM #3 Oil -% 77 60 54 Oven A~ed, 7 days @ 121C.
Tensile Strength, MPa12.812.8 9.3 Elongation, % 260 85 65 Shore A Hardness, Points 72 84 80 Solenoid Brittleness Test Pass, C. -38 -40 -60 Fail, C. -42 -46 -<-60 Low Temp. Stif.fening,ASTMD1043 Modulus, MPa @ 23.8C.2.3 2.4 2.3 -34.4C.18.6 40.7 6.2 -40.0C.165.5172.4 7.6 -45.5C. - - 10.3 -51.1C. - - 20.7
Minimum Viscosity 25 18 18 Time to 5 pt. rise, min.16 20 40 ODR Cure at 162C. (30 min.) Maximum Torque, L~. - In.77 43 44 Time to 90% of max., minutes 3.55 0 5.5 Cured Properties (162C., 15 min.) Tensile Strength, MPa21.4 15.8 16.5 Modules 2.9 3.4 3,1 Elongation % 430 430 470 Shore A Hardness, Points68 77 76 Compression Set (cured 162C., 20 min.) 22 HR. at 100C.
Method B of ASTM D395 % 39 52 40 *Denotes trade mark ~3~3~34 Control Example C3 and Examples 7-8 All stocks contain 35 parts of SRF carbon black, 2 parts of low molecular weight polyethylen~
4 parts of magnesium oxide, 2 parts of octylated diphenylamine, 5 parts of zinc oxide, 1 part of poly(ethylene oxide) glycol, 1 part of tetraethylth~ram disulfide, and 1.5 parts of hexamethylene tetramine/
binder dispersion (65/35). Additional ingredients in each compound are shown in Table IV with data on the properties of the blends and their vulcanizates. The use of E/VA/CO in compounds 7 and 8 shows again the surprising results that ozone resistance and resistance to ASTM #3 oil are improved over the base neoprene compound. The compound of Example 8, modified with dioct~l-sebacate,a low-temperature plasticizer, shows good response. Improvement in both resistance to impact at low temperatures and to stiffening is obtained.
TABLE IV
.... _ .
ESTER PLASTICIZER MODIFICATION
Example Ingredients (parts by weiqht)_ 7 8 "Neoprene" W - 100 70 70 E/23.5~ VA/11% CO, 35 MI - 30 30 Aromatic Processing Oil20 20 Dioctyl Sebacate - - 30 SRF Black 35 35 35 Low molecular wt. polyethylene 2 2 2 Magnesium Oxide 4 4 4 Zinc Oxide 5 5 5 octylated Diphenylamine 2 2 2 Hexamethylene Tetramine/1.51.5 1.5 Binder dispersion (65/35) Poly(Ethylene Oxide)Glycol, 4000 Mol. Wt.
Tetraethyl Thiuram Disul~ide Mooney Scorch, @ 121C.
Minimum Viscosity 12 8 5 Time to 5 pt. rise, min.25 20 32 ODR Cure, 162C. (30 Min.) Maximum Torque,Lb. - In.48 56 39 Time to 90~ of max., minutes 18 20 22 Cured Properties (162C., 20 min.) Tensile Strength, MPa17.913.1 10.3 Modulus@ 100% Stress, MPa 1.5 2.5 2.1 Elongation, % 500 290 280 Shore A Hardness, Points 52 62 56 Comp~es~ion Set (162C., 25 min.) 22 Hr. @ 100C., Method B of AS~M D 395 .
% 29 40 47 Ozone Exposure, lppm O3, 30% Elongation, 4 days no no Surface Appearance cracks cracks cracks TABLE IV (Cont'd.) Properties C3 7 8 Volume Increase,70 Hr. @ 100C., ASTM #3 Oil -% 77 60 54 Oven A~ed, 7 days @ 121C.
Tensile Strength, MPa12.812.8 9.3 Elongation, % 260 85 65 Shore A Hardness, Points 72 84 80 Solenoid Brittleness Test Pass, C. -38 -40 -60 Fail, C. -42 -46 -<-60 Low Temp. Stif.fening,ASTMD1043 Modulus, MPa @ 23.8C.2.3 2.4 2.3 -34.4C.18.6 40.7 6.2 -40.0C.165.5172.4 7.6 -45.5C. - - 10.3 -51.1C. - - 20.7
Claims (15)
1. A curable blend of (a) 100 parts of a chloroprene polymer and (b) about 3-100 parts of an ethylene copolymer selected from the group consisting of ethylene/carbon monoxide/X and ethylene/sulfur dioxide/X copolymers, wherein comonomer X is (I) a vinyl ester of an alkanoic acid, the acid having 1 to 18 C atoms, (II) an alkyl acrylate or methacrylate, the alkyl group having 1 to 18 C atoms, (III) an alkyl vinyl other, the alkyl group having 1 to 4 C
atoms, (IV) acrylonitrile or methacrylonitrile, or combinations of the above comonomers, the ethylene copolymer containing about 3-25 weight % of carbon monoxide or sulfur dioxide, about 10-65 weight % of comonomer X, and about 30-75 weight % of ethylene-
atoms, (IV) acrylonitrile or methacrylonitrile, or combinations of the above comonomers, the ethylene copolymer containing about 3-25 weight % of carbon monoxide or sulfur dioxide, about 10-65 weight % of comonomer X, and about 30-75 weight % of ethylene-
2. The curable blend of Claim 1 wherein the amount of ethylene copolymer is about 5-50 parts.
3. The curable blend of Claim 2 wherein the amount of carbon monoxide or sulfur dioxide is about 6-15 weight %.
4. The curable blend of Claim 3 wherein the amount of comonomer X is about 20-35 weight %.
5. The curable blend of Claim 4 wherein the amount of ethylene is about 50-70 weight %.
6. The curable blend of Claim 5 wherein comonomer X is vinyl acetate.
7. The curable blend of Claim 5 wherein comonomer X is methyl acrylate.
8. The curable blend of Claim 5 wherein the ethylene copolymer is ethylene/vinyl acetate/carbon monoxide terpolymer.
9. The curable blend of Claim 5 wherein the ethylene copolymer is ethylene/methyl acrylate/carbon monoxide terpolymer.
10. A composition comprising the curable blend of Claim 1 and a peroxide or sulfur curing system.
11. A composition comprising the curable blend of Claim 5 and a peroxide or sulfur curing system.
12. A composition comprising the curable blend of Claim 8 and a peroxide or sulfur curing system.
13. A composition comprising the curable blend of Claim 9 and a peroxide or sulfur curing system.
14. A vulcanized product obtained by heating the composition of Claim 10 for about 0.5 to 120 minutes at about 100° to 210°C.
15. A vulcanized product obtained by heating the composition of any one of Claim 11, Claim 12 and Claim 13 for about 0.5 to 120 minutes at about 100° to 210°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US93772678A | 1978-08-29 | 1978-08-29 | |
| US937,726 | 1978-08-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1131384A true CA1131384A (en) | 1982-09-07 |
Family
ID=25470320
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA334,515A Expired CA1131384A (en) | 1978-08-29 | 1979-08-27 | Curable blends of chloroprene polymer and ethylene copolymer |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5531893A (en) |
| BE (1) | BE878474A (en) |
| CA (1) | CA1131384A (en) |
| DE (1) | DE2934961A1 (en) |
| FR (1) | FR2434837A1 (en) |
| GB (1) | GB2028838B (en) |
| IT (1) | IT1122522B (en) |
| NL (1) | NL7906469A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05319535A (en) * | 1991-10-10 | 1993-12-03 | Mass Flow Equipment Bv | Sealing apron device for loaded tank of belt conveyor |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3684778A (en) * | 1970-04-28 | 1972-08-15 | Du Pont | Polymers of ethylene, sulfur dioxide and ethylenic monomers |
| US3780140A (en) * | 1971-08-06 | 1973-12-18 | Du Pont | Ethylene/carbon monoxide polymer compositions |
-
1979
- 1979-08-27 CA CA334,515A patent/CA1131384A/en not_active Expired
- 1979-08-28 BE BE0/196914A patent/BE878474A/en not_active IP Right Cessation
- 1979-08-28 FR FR7921515A patent/FR2434837A1/en active Granted
- 1979-08-28 GB GB7929734A patent/GB2028838B/en not_active Expired
- 1979-08-28 JP JP10872779A patent/JPS5531893A/en active Granted
- 1979-08-28 IT IT25321/79A patent/IT1122522B/en active
- 1979-08-28 NL NL7906469A patent/NL7906469A/en not_active Application Discontinuation
- 1979-08-29 DE DE19792934961 patent/DE2934961A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5531893A (en) | 1980-03-06 |
| GB2028838A (en) | 1980-03-12 |
| FR2434837A1 (en) | 1980-03-28 |
| IT7925321A0 (en) | 1979-08-28 |
| BE878474A (en) | 1980-02-28 |
| FR2434837B1 (en) | 1983-02-25 |
| DE2934961A1 (en) | 1980-03-13 |
| NL7906469A (en) | 1980-03-04 |
| GB2028838B (en) | 1982-10-13 |
| DE2934961C2 (en) | 1987-11-12 |
| IT1122522B (en) | 1986-04-23 |
| JPS6241245B2 (en) | 1987-09-02 |
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