HK1181798A - Sealant composition comprising polythioether - Google Patents

Description

Sealant compositions comprising polythioethers

The present application is a divisional application of chinese patent application having an application date of 28/2008, application number of 200880019065.3, entitled "sealant composition comprising polythioether".

Cross Reference to Related Applications

This application is a continuation-in-part of U.S. patent application serial No. 11/369,490, which is a continuation-in-part of U.S. patent application serial No. 10/617,582, both of which are incorporated herein by reference. Priority is also claimed from U.S. provisional patent application serial No. 60/915,166, filed on 5/1/2007, which is incorporated herein by reference.

Technical Field

The present invention generally relates to epoxy-terminated polythioethers (polythioethers), hydroxyl/amine-terminated polythioethers, and curable compositions of the polythioethers.

Background

Sealants, coatings and adhesives for use in flight and aerospace applications are expected to exhibit flexibility, oil resistance (fuel resistance) and high temperature resistance. In general, these properties can be achieved by introducing polysulfide linkages into the polymer resin backbone.

Flexible, oil resistant epoxy-terminated polysulfides have been developed that exhibit good oil resistance. These compounds are typically formed using epichlorohydrin as the reactant. Epichlorohydrin is extremely toxic and the synthesis of epoxy-terminated polysulfides using epichlorohydrin produces corrosive hydrolyzable chlorine ("HYC") as an undesirable by-product. In addition, the use of epichlorohydrin-forming compounds introduces unreacted epichlorohydrin, which must be removed by thorough washing. Such epoxy-terminated polysulfides typically exhibit a relatively high viscosity of about 30 poise at 25 ℃ and a broad epoxy equivalent weight range.

There is a need for improved flexible, oil and high temperature resistant epoxy-capped polythioethers and compositions of epoxy-capped polythioethers synthesized by processes that are environmentally compatible and do not produce toxic by-products. In addition, it is desirable to prepare epoxy-capped polythioethers having a controlled and narrow range of epoxy equivalents.

The epoxy-terminated polythioethers of the present invention formed by the addition of thiols to the double bonds of monoepoxides containing olefinic groups are flexible, oil resistant, and the high conversion synthesis does not produce hydrolyzable chlorine and avoids the use of epichlorohydrin. The epoxy-capped polythioethers of the present invention exhibit a controlled and narrow distribution of epoxy equivalent weights.

The present invention also relates to amine/hydroxyl-terminated polythioethers formed from the epoxy-terminated polythioethers.

Summary of The Invention

To address the shortcomings of known epoxides for flight and aerospace applications, epoxy-capped polythioethers and curable compositions of epoxy-capped polythioethers are provided.

One aspect of the present invention provides an epoxy-terminated polythioether (polythioether) having the structure of formula I:

wherein

R¹Is selected from C_2-6N-alkylene group, C_3-6BranchingAlkylene radical, C_6-8Cycloalkylene radical, C_6-10Alkylcycloalkylene, - [ - (CHR)³)_p-X-]_q-(CHR³)_r-；

Wherein

Each R³Independently selected from H and CH₃；

Each X is independently selected from the group consisting of O, S, -NH-and-NR⁴-；

R⁴Is selected from H and-CH₃；

p is an integer from 2 to 6;

q is an integer of 1 to 5; and

r is an integer from 2 to 10;

and each R²Is a divalent linking group.

A second aspect of the invention provides a process for preparing a compound having the structure of formula II, wherein R is obtained by reacting n moles of a compound having the structure of formula II¹Has the above-mentioned meanings:

HS-R¹-SH Ⅱ，

An epoxy-terminated polythioether formed by reacting with n +1 moles of a compound having the structure of formula III, wherein R is²Forming a divalent linking group

A third aspect of the invention provides a curable composition of an epoxy-capped polythioether of the invention. In a fourth aspect of the invention, there is provided an amine/hydroxyl-terminated polythioether having the structure:

wherein

Each R²¹Independently represent C_2-10An n-alkylene group; c_2-6A branched alkylene group; an alkyleneoxy group; c_6-8A cycloalkylene group; c_6-10An alkylcycloalkylene group; a heterocyclic group; or- [ (-CHR)³-)_s-X-]_q-(-CHR³-)_r-, where s is an integer from 2 to 6, q is an integer from 1 to 5, R is an integer from 2 to 10, R³Is hydrogen or methyl, and X represents O, S or-NR₂-, wherein R represents an alkyl group;

each R²²Independently is a divalent linking group;

p is an integer from 2 to 6;

m is a rational number from 0 to 50;

each R²³Is a divalent linking group; and

n is an integer of 1 to 60.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.

Detailed description of the invention

Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Consistent with the invention, one embodiment provides an epoxy-terminated polythioether having the structure of formula I:

wherein

R¹Is selected from C_2-6N-alkylene group, C_3-6Branched alkylene group, C_6-8Cycloalkylene radical, C_6-10Alkylcycloalkylene, - [ - (CHR)³)_p-X-]_q-(CHR³)_r-；

Wherein

Each R³Independently selected from H and-CH₃；

Each X is independently selected from the group consisting of O, S, -NH-and-NR⁴-；

R⁴Is selected from H and-CH₃；

p is an integer from 2 to 6;

q is an integer of 1 to 5; and

r is an integer from 2 to 10;

and each R²Is a divalent linking group, typically alkylene or oxyalkylene, containing from 3 to 20 carbon atoms.

R¹Typically derived from a compound, monomer or polymer having at least two thiol (thiol) groups. In certain embodiments, the polythiol comprises a dithiol having the structure of formula II:

HS-R¹-SH Ⅱ

wherein R is¹May be C_2-6An n-alkylene group; c with one or more pendant groups_3-6Branched alkylene groups, which pendant groups may be, for example, hydroxyl groups, and alkyl groups such as methyl or ethyl groups; an alkyleneoxy group; c_6-8A cycloalkylene group; c_6-10An alkylcycloalkylene group; or- [ (-CHR)³)_p-X-]_q-(-CHR³)_r-a group, p is independently selected from an integer from 2 to 6, q is independently selected from an integer from 1 to 5, and R is independently selected from an integer from 2 to 10, and R³Is hydrogen or methyl.

In other embodiments, the dithiols may contain one or more heteroatom substituents in the carbon backbone, i.e., where X includes a heteroatom such as O, S or other divalent heteroatom group; secondary or tertiary amine groups, i.e. -NR⁴-, wherein R⁴May be hydrogen or methyl; or other substituted trivalent heteroatom dithiols. In certain embodiments, X may be O or S, and thus R¹Is- [ (-CHR)³)_p-O-]_q-(-CHR³)_r-or- [ (CHR)³)_p-S-]_q-(-CHR³)_r-. In certain embodiments, p and r are equal. In certain embodiments, p and r are both 2.

In certain embodiments, dithiols may include dimercaptodiethylsulfide (DMDS) (p =2, r =2, q =1, X = S), dimercaptodioxaoctane (DMDO) (p =2, q =2, r =1, X =0), and 1, 5-dimercapto-3-oxapentane (p =2, r =2, q =1, X = O). In certain embodiments, dithiols may include both heteroatom substituents and pendant alkyl groups in the carbon backbone, such as pendant methyl groups. Examples of dithiols having heteroatom substituents and pendant alkyl groups in the carbon backbone include methyl-substituted DMDS, e.g., HS-CH₂CH(CH₃)-S-CH₂CH₂-SH and HS-CH (CH)₃)CH₂-S-CH₂CH₂-SH, and dimethyl-substituted DMDS, e.g. HS-CH₂CH(CH₃)-S-CH(CH₃)CH₂-SH and HS-CH (CH)₃)CH₂-S-CH₂CH(CH₃)-SH。

In certain embodiments of epoxy-capped polythioethers having the structure of formula I, R¹May be C_2-6N-alkylene radicals, for example 1, 2-ethylenedithiol, 1, 3-propylenedithiol, 1, 4-butylenedithiol, 1, 5-pentylenedithiol or 1, 6-hexylenedithiol. In other embodiments, R¹Can be provided withC of one or more side groups_3-6Branched alkylene groups such as 1, 2-propylenedithiol, 1, 3-butylenedithiol, 2, 3-butylenedithiol, 1, 3-pentylenedithiol and 1, 3-dithio-3-methylbutene (1, 3-dithio-3-methylbutylene). In other embodiments, R¹May be C_6-8Cycloalkylene or C_6-10Alkylcycloalkylene radicals, such as p-menthane-2, 9-dithiol (dipentylenedimerioctaptan) and Ethylcyclohexylenedithiol (ECHDT).

Polythiols having the structure of formula II can be prepared by reacting, for example, divinyl ether or a mixture of divinyl ethers with an excess of dithiol or a mixture of dithiols. In certain embodiments, n +1 moles of a polythiol or a mixture of at least two polythiols having the structure of formula II is reacted with n moles of a polyvinyl ether having the structure of formula IV:

CM₂＝CH-O-[-R⁵-O-]_m-CH＝CH₂ IV

wherein R is⁵Comprising C_2-6N-alkylene group, C_3-6Branched alkylene group, C_6-8Cycloalkylene radical, C_6-10Alkylcycloalkylene, and [ - (CHR)³)_p-X-]_q-(CHR³)_r-group of which X, R³P, q and r may be as described above, and m may be a rational number from 1 to 10.

The polyvinyl ether may include a compound having at least one alkyleneoxy group, preferably 1 to 4 alkyleneoxy groups, for example, a compound in which m is an integer of 1 to 4. In other embodiments, m is an integer from 2 to 4. In certain embodiments, the polyvinyl ether comprises a mixture of polyvinyl ethers. These mixtures are characterized by a non-integral average value of the number of alkyleneoxy groups per molecule. Thus, m in formula IV may also be a rational number in the range of 0 to 10.0, in other embodiments 1.0 to 10.0, in still other embodiments 1.0 to 4.0, and in still other embodiments 2.0 to 4.0.

The polyvinyl ether monomers may include divinyl ether monomers such as divinyl ether, ethylene glycol divinyl ether (EG-DVE), butanediol divinyl ether (BD-DVE), hexanediol divinyl ether (HD-DVE), diethylene glycol divinyl ether (DEG-DVE), triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, and polytetrahydrofuranyl divinyl ether; trivinyl ether monomers such as trimethylolpropane trivinyl ether; tetrafunctional vinyl ether monomers such as pentaerythritol tetraethylene ether; and mixtures thereof. In certain embodiments, the polyvinyl ether monomer may further comprise one or more pendant groups selected from alkylene groups, hydroxyl groups, alkenyloxy groups (alkeneoxy groups), and amine groups.

Polythiols having the structure of formula II can be prepared by reacting compounds having olefinic groups, such as vinylcyclohexene.

In certain embodiments, wherein R is⁵Is C_2-6Branched alkylene polyvinyl ethers may be prepared by reacting a polyol with acetylene. Exemplary compounds of this class include those wherein R is⁵Is an alkyl-substituted methylene group such as-CH (CH)₃) A compound of (e), e.g.Blends such asE-200 divinyl ether (BASF Corp.), wherein R⁵= ethylene and m =3.8, or is an alkyl-substituted ethylene radical such as-CH₂CH(CH₃) A compound of (e), e.g.A polymer blend comprising-2 and-3(International SpecialtyProducts)。

the reaction between a dithiol and a polyvinyl ether to prepare a polythiol having the structure of formula II is described in U.S. patent No.5,912,319.

The reaction between the dithiol and the polyvinyl ether to prepare the polythiol having the structure of formula II can be carried out in the presence of a catalyst. The catalyst may be a free radical catalyst, an ionic catalyst, or ultraviolet radiation. Preferably, the catalyst does not include an acidic or basic compound, and does not produce an acidic or basic compound when decomposed. Examples of free radical catalysts are azo catalysts, including-57(Du Pont)、-64(Du Pont)、-67(Du Pont)、(Wako Specialty Chemicals) and(Wako specialty Chemicals). Examples of other free radical catalysts are alkyl peroxides, such as tert-butyl peroxide.

R²Is a divalent linking group. In certain embodiments, R²Can be derived from a monoepoxide having the structure of formula III:

wherein R is²Including groups reactive with sulfides, such as olefinic groups. The olefinic group may be an alkenyl (alkylene group) or oxyalkylene (oxyalkylene) group having 3 to 20 carbon atoms and preferably 3 to 5 carbon atoms. In certain embodiments, the deviceMonoepoxides having the structure of formula III include allyl glycidyl ether, 1, 2-epoxy-5-hexene, 1, 2-epoxy-7-octene, 1, 2-epoxy-9-decene, 4-vinyl-1-cyclohexene 1, 2-epoxide, butadiene monoepoxide, isoprene monoepoxide, and limonene monoepoxide.

Consistent with the present invention, another embodiment provides an epoxy-terminated polythioether having the structure of formula V:

wherein R is¹And R²As noted above, B is a multivalent group, and z is a number corresponding to the valence of B.

B is a z-valent group and is derived from a compound B', which represents a polyfunctionalizing agent. Polyfunctionalizing agents refer to compounds having more than two moieties reactive with epoxy groups. In certain embodiments, the polyfunctionalizing agent comprises 3-6 such reactive moieties. Typically, B is represented as a "z-valent" polyfunctionalizing agent, where z is the number of reactive moieties, and is the number of individual branches that therefore constitute the multifunctional epoxy-terminated polythioether.

In certain embodiments of the epoxy-capped polythioethers having the structure of formula V, the polyfunctionalizing agent is a trifunctionalizing agent wherein z is 3. In certain embodiments of the material of formula V, the functional group of the polyfunctionalizing agent is selected from the group consisting of acid groups, amine groups, anhydride groups, and thiol groups. Polyfunctionalizing agents having mixed functional groups may also be used. Examples of the polyfunctionalizing agent include tricarboxylic acids such as trimellitic acid and tricarballylic acid; such as polythiols described in U.S. patent nos. 4,366,307, 4,609,762, and 5,225,472, as well as triamines such as diethylenetriamine and triethylenetetramine.

Mixtures of polyfunctionalizing agents having a range of functionalities may also be used in the preparation of epoxy-capped polythioethers having the structure of formula V. In certain embodiments, the use of an amount of a trifunctional agent provides an epoxy-terminated polythioether having an average functionality of from 2.05 to 3.0. Other average functionalities may be achieved by using tetrafunctional polyfunctionalizing agents or polyfunctionalizing agents having higher valencies. The average functionality of the resulting epoxy-capped polythioethers is also affected by factors such as stoichiometry, as is known to those skilled in the art.

The difunctional epoxy-terminated polythioethers of the present invention having the structure of formula I can be formed by reacting n moles of a dithiol having the structure of formula II with n +1 moles of a monoepoxide having the structure of formula III. The dithiols and monoepoxides can be reacted at a temperature of from about 40 ℃ to about 100 ℃, typically from about 60 ℃ to 80 ℃. The dithiol and monoepoxide may be allowed to react for about 10 hours to about 36 hours, typically about 12 hours to 24 hours. The dithiol can be any compound, polymer, or monomer having at least two thiol groups, and includes polythiol compounds exemplified by any of the foregoing. In certain embodiments, the monoepoxide having the structure of formula II comprises one epoxy group and one olefinic group. The monoepoxide can be any of the monoepoxides exemplified above.

Optionally, the reaction is carried out in the presence of a catalyst. Examples include free radical catalysts, ionic catalysts, and ultraviolet light. In certain embodiments, the catalyst does not include an acidic or basic compound, and does not produce an acidic or basic compound when decomposed. Preferably, the catalyst may be a free radical catalyst, such as those described above.

Consistent with another embodiment of the present invention, a multifunctional epoxy-terminated polythioether having the structure of formula V can be formed by reacting at least one polythiol, at least one polyepoxide, and at least one polyfunctionalizing agent in suitable stoichiometric amounts. Examples of polythiols, polyepoxides, and polyfunctionalizing agents include those described above. Optionally, the reaction is carried out in the presence of a catalyst as described above.

The epoxy-terminated polythioethers described above can be combined with a curing agent to form a curable composition. The epoxy-terminated polythioethers described above can also be combined with other resins and curing agents to form curable compositions. In certain embodiments, the curable composition of the invention comprises 0.2 to 10 weight percent of at least one epoxy-terminated polythioether as described above, at least one curing agent, and at least one resin, wherein the weight percent is based on the total weight of the curable composition.

The term curing agent refers to a substance that reacts with the epoxy groups of an epoxy-terminated polythioether to form crosslinks. Examples of the curing agent include polyacid curing agents, polyamine curing agents, polyanhydride curing agents, and polythiol curing agents. Polyacid curing agent refers to a compound having two or more acid groups per molecule that can react with an epoxy-terminated polysulfide to form a crosslinked composition. The acid functional group may be a carboxylic acid or a sulfonic acid. Preferably, the polyacid curing agent may be a carboxyl-terminated compound having at least two carboxyl groups per molecule. Examples of polyacid curing agents include carboxylic acid group-containing polymers such as acrylic polymers, polyesters and polyurethanes; and oligomers such as ester group-containing oligomers and monomers.

An example of a carboxylic acid-containing acrylic polymer is a copolymer of (a) an ethylenically unsaturated monomer containing at least one carboxylic acid and (b) a different ethylenically unsaturated monomer that does not contain a carboxylic acid group. In certain embodiments, the amounts of monomer (a) and monomer (b) are selected such that the polyacid acrylic polymer has an acid number of from 30 to 150, preferably from 60 to 120. Examples of carboxylic acid-containing acrylic monomers are acrylic acid, methacrylic acid, maleic acid and partial esters of maleic acid. The other monomer component (b) is characterized by the following groups

And may be styrene, alpha-substituted lower alkyl styrenes such as alpha-methylstyrene, alkyl esters of acrylic and methacrylic acid such as methyl methacrylate, methyl acrylate and ethyl acrylate, and mixtures of these.

In other embodiments, the polyacid curing agent may be a monomeric polycarboxylic acid having from 5 to 20 carbon atoms, including open-chain, cyclic, saturated, unsaturated, and aromatic acids. Examples of suitable monomeric polycarboxylic acids include succinic acid, adipic acid, azelaic acid, sebacic acid, hexahydrophthalic acid, maleic acid, cyclohexene-1, 2-dicarboxylic acid and phthalic acid.

Polyamine curing agents include primary and secondary diamines or polyamines in which the groups attached to the nitrogen atoms can be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic-substituted aliphatic, aliphatic-substituted aromatic, or heterocyclic. In other embodiments, the polyamine curing agent may include mixed amines in which the groups are different, such as aromatic groups, aliphatic groups, and other non-reactive groups attached to carbon atoms, such as oxygen, sulfur, halogens, or nitro groups. Examples of suitable aliphatic and cycloaliphatic diamines include 1, 2-ethylenediamine, 1, 2-propylenediamine, 1, 8-p-menthanediamine, isophoronediamine, propane-2, 2-cyclohexylamine, and methane-bis- (4-cyclohexylamine), and

H₂N-(-CH₂-(CHCH₃-O-)_x-CH₂-CHCH₃-NH₂

wherein x is 1 to 10.

Polyamine curing agents include phenylenediamine and toluenediamine, such as o-phenylenediamine and p-toluenediamine, and N-alkyl and N-aryl derivatives thereof, such as N, N '-dimethyl-o-phenylenediamine, N' -di-p-tolyl-m-phenylenediamine, and p-amino-diphenylamine.

The polyamine curing agent may be polynuclear aromatic diamines in which aromatic rings are connected by means of valence bonds, such as 4, 4' -biphenyldiamine, methylenedianiline and monochloromethylenedianiline.

The polyamine curing agent can be a sulfur-containing polyamine that includes isomers of phenylenediamine-bis (methylthio) -s, such as 1, 3-phenylenediamine-4-methyl-2, 6-bis (methylthio) -and 1, 3-phenylenediamine-2-methyl-4, 6-bis (methylthio) -, the structures of which are described below:

such sulfur-containing polyamines are commercially available from Albemarle Corporation under the trademark Ethacure 300.

Accordingly, certain embodiments of the present invention are directed to amine/hydroxyl-terminated polythioethers having the structure:

wherein

Each R²¹Independently represent C_2-10An n-alkylene group; c_2-6A branched alkylene group; an alkyleneoxy group; c_6-8A cycloalkylene group; c_6-10An alkylcycloalkylene group; a heterocyclic group; or- [ (-CHR)³-)_s-X-]_q-(-CHR³-)_r-, where s is an integer from 2 to 6, q is an integer from 1 to 5, R is an integer from 2 to 10, R³Is hydrogen or methyl, and X represents O, S or-NR₂-, wherein R represents an alkyl group; each R²²Independently is a divalent linking group; p is an integer from 2 to 6; m is a rational number from 0 to 50; n is an integer from 1 to 60; each R²³Is a divalent linking group; and n is an integer from 1 to 60. In certain embodiments, each Y is independently derived from phenylenediamine-bis (methylthio) -.

The epoxy-capped polythioethers and/or amine/hydroxyl-capped polythioethers of the invention can be used in curable compositions, such as sealants, coatings, and adhesives, alone or in combination with other resins. In certain embodiments, the curable compositions of the present invention may contain fillers and additives suitable for particular applications.

Fillers may be added to the curable compositions of the present invention to impart desired physical properties, for example, for increasing impact strength, controlling viscosity, improving electrical properties, or reducing specific gravity. Fillers useful in the curable compositions of the invention for both aerospace and aviation applications include those commonly used in the art, such as carbon black, calcium carbonate, silica and polymer powders. Exemplary fillers includeD-13 hydrophobic precipitated silicas (Degussa),SPM precipitated calcium carbonate (Solvay Chemicals), TS-270(Cabot corporation), titanium dioxide (DuPont), aluminum hydroxide, and1002D Nat1 ultrafine polyamide powder (Atofina Chemicals). In certain embodiments, the filler comprises 5wt% to 60wt% of the non-volatile components of the curable composition.

The curable composition of the invention generally comprises at least one additive selected from the group consisting of: plasticizers, pigments, curing accelerators, adhesion promoters, thixotropic agents, flame retardants, masking agents, antioxidants and surfactants. The additives may be present in the curable composition in an amount of 0.1 to 40wt%, based on the total weight of the curable composition.

The plasticizer may include at least one of: phthalates, chlorinated paraffins and hydrogenated terphenyls. Examples of useful plasticizers includeModified polyphenyl (Solutia, Inc.) and tung oil (Campbell)&Co.). In certain embodiments, the plasticizer comprises from 1wt% to 40wt% of the total weight of the curable composition, more typically from 1wt% to 8wt% of the total weight of the curable composition.

The curable composition of the present invention may comprise at least one pigment. Examples of pigments include at least one of the following: carbon black, metal oxides and calcium carbonate. Pigment grade carbon blacks are generally characterized by low structure and particle size, e.g.660R (Cabot corporation). Brilliant 1500 is an example of a pigment grade, 99.995⁺%, calcium carbonate (Aldrich Chemical). In certain embodiments, the pigment comprises from 0.1wt% to 10wt% of the total weight of the curable composition. In other embodiments, the pigment comprises from 0.1wt% to 5wt% of the total weight of the curable composition.

The curable compositions of the present invention cure according to recommended procedures, and in certain embodiments at ambient temperature. "curable" refers to the ability to undergo one or more chemical reactions to form stable covalent bonds between constituent components. The curable composition is generally curable at a minimum temperature of 50 ℃ to 100 ℃, more typically 60 ℃ to 75 ℃.

Examples

Reference will now be made in detail to specific embodiments of the present invention. While certain embodiments of the present invention will be described in combination with the preferred embodiments, it will be understood that it is not intended to limit the embodiments of the present invention to those preferred embodiments. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the embodiments of the invention as defined by the appended claims.

The following tests were used to characterize certain curable compositions of the present invention:

chemical resistance is measured according to ASTM D1308, 24 hour spot test.

Hardness was measured according to MMS 3324.4.18 and AMS 32774.5.5.

Viscosity was measured according to MMS 3324.4.4 and AMS 32774.5.8.

The odor is determined empirically.

Color was measured according to the Gardner method.

Epoxy equivalent weight was measured according to ASTM 1652.

Tensile strength was measured according to ASTM D412.

Elongation is measured according to ASTM D412.

Example 1

253.4g (1.39 moles) of dimercaptodioxaoctane (DMDO) was charged to a 1 liter 4-necked flask under a nitrogen atmosphere. The contents of the flask were heated to 50 ℃ while stirring, and 146.6g (0.93 moles) of diethylene glycol divinyl ether (DEG-DVE) was added over 1 hour. The temperature of the reaction mixture was increased to 70 ℃ and 0.05g of free radical initiator was added67 (2, 2-azobis (2-methylbutyronitrile), Du Pont). The temperature of the reaction mixture was maintained at 70 ℃ for another 1 hour. The completion of the reaction of DEG-DVE with DMDO is indicated by a thiol equivalent value of 420. Allyl Glycidyl Ether (AGE) (110.87g, 0.97 mol, 2% stoichiometric excess) was added over 1 hour at 70 ℃ and the reaction mixture was heated at 70 ℃ for another 1 hour. Then 10 parts were added at 70 ℃ at 3-hour intervals67 (0.165 g each). In the process of addingAfter 67, the reaction mixture was heated at 70 ℃ for 5 hours. The reaction mixture was then degassed at 70 deg.C/4-5 mm Hg for 3 hours to provide a liquid epoxy-capped polythioether having a pale yellow color, a viscosity of 5.0 poise, and an epoxy equivalent value of 563. The reaction yield was 508.7g (100%).

Example 2

62.17g (moles) of DMDO was added to a 250ml 3-neck flask under nitrogen. The DMDO was heated to 60 ℃ while stirring, and 44.88g (moles) of DEG-DVE was added to the reaction mixture over 50 minutes while maintaining the temperature of the reaction at 60 ℃ to 70 ℃. The reaction mixture was heated at 70 ℃ for another 4 hours. 2 portions were added at 1.5 hour intervals67(0.036g each) were added to the reaction mixture and heated at 70 ℃ for 1.5 hours. The mercaptan equivalent value of the reaction mixture was 890. Adding another part67(0.036g) and the reaction mixture was heated for an additional 1.5 hours. A mercaptan equivalent value of 893 indicated complete reaction of DEG-DVE with DMDO. AGE (13.21g, 0.116 mol, 2% stoichiometric excess) was added in 1 part at 70 ℃ and the reaction mixture was heated for 2 hours. 8 parts were added at 70 ℃ at 3-hour intervals67 (0.035 g each) and heating was continued for an additional 4 hours. At this stage, the mercaptan equivalent value of the reaction mixture was 28,642. To complete the reaction, an additional 4.8g (0.042 mol, 38% stoichiometric excess) of AGE was added and the reaction mixture was heated at 70 ℃ for 1 hour. 2 parts are added at 3-hour intervals67(0.036g each). In the process of addingAfter 67, the reaction mixture was heated at 70 ℃ for 5 hours. The reaction mixture was then degassed at 70 ℃/4-5mm Hg for 2 hours to provide an epoxy-terminated polythioether having a slightly hazy liquid with a pale yellow color, a viscosity of 26 poise, and an epoxy equivalent value of 1,217. The reaction yield was 120.0g (100%).

Curable composition 1 was prepared by combining 12.5 parts by weight of the epoxy-capped polythioether of example 1, 37.5 parts by weight of Epon 828, 28-29 parts by weight of Epi-Cure 3155, and 0.5 parts by weight of DMP 30. Curable composition 1 was cured at a temperature of 68 ° f for 1 week. A summary of the properties of cured composition 1 is shown in table 1.

Table 1: properties of the cured composition 1

When cured, curable composition 1 exhibited excellent chemical resistance, including excellent flight and aerospace fuel resistance.

Curable composition 1 had a 5 poise viscosity 6 times less than the epoxy terminated polysulfide made using epichlorohydrin at a temperature of 25 ℃. The low viscosity of the epoxy-capped polythioethers of the invention in preparing the formulations provides greater freedom compared to comparable compositions prepared using epoxy-capped polysulfides prepared using epichlorohydrin. Other desirable characteristics include a low specific gravity of 1.13, a low epoxy equivalent weight of 530-650, and epoxy-capped polythioethers that are compatible with amines and other epoxy compounds.

Example 3 Synthesis of amine-terminated polythioethers

A3 liter 4-neck flask was charged with 1703.46g (1.51 moles) of the product of example 1 and 647.49g (3.02 moles) of Ethacure 300, a diamine available from Huntsman Inc. The contents were mixed under vacuum (10mmHg) for 0.25 hour. Polycat 8(0.47g, 0.0037 mol) was added and the mixture was heated at 84-92 ℃ for 10 hours. The product was light brown and had a viscosity of 6 poise.

Claims (20)

1. An amine/hydroxyl-terminated polythioether having the structure:

wherein

Each R²¹Independently represent C_2-10An n-alkylene group; c_2-6A branched alkylene group; an alkyleneoxy group; c_6-8A cycloalkylene group; c_6-10An alkylcycloalkylene group; heterocyclic ringsA group; or- [ (-CHR)³-)_s-X-]_q-(-CHR³-)_r-, where s is an integer from 2 to 6, q is an integer from 1 to 5, R is an integer from 2 to 10, R³Is hydrogen or methyl, and X represents O, S or-NR₂-, wherein R represents an alkyl group;

each R²²Independently is a divalent linking group;

p is an integer from 2 to 6;

m is a rational number from 0 to 50;

each R²³Is a divalent linking group; and

n is an integer of 1 to 60,

wherein at least one Y is a primary amine group comprising a moiety containing one or more aromatic rings,

wherein at least one Y is derived from an isomer of phenylenediamine-bis (methylthio) -.

2. The amine/hydroxyl-terminated polythioether of claim 1, wherein the isomer of phenylenediamine-bis (methylthio) -comprises at least one of the following structures:

3. an amine/hydroxyl-terminated polythioether having the structure:

wherein

Each R²¹Independently represent C_2-10An n-alkylene group; c_2-6A branched alkylene group; an alkyleneoxy group; c_6-8A cycloalkylene group; c_6-10An alkylcycloalkylene group; a heterocyclic group; or- [ (-CHR)³-)_s-X-]_q-(-CHR³-)_r-, where s is an integer from 2 to 6, q is an integer from 1 to 5, R is an integer from 2 to 10, R³Is hydrogen or methyl, and X represents O,S or-NR₂-, wherein R represents an alkyl group;

each R²²Independently is a divalent linking group;

p is an integer from 2 to 6;

m is a rational number from 0 to 50;

each R²³Is a divalent linking group; and

n is an integer of 1 to 60,

wherein at least one Y is a primary amine group comprising a moiety containing one or more aromatic rings,

wherein the polythioether is the reaction product of an amine and an epoxy-terminated polythioether that is the reaction product of a dithiol, a diene, and a monoepoxyethylene.

4. An epoxy-capped polythioether, the epoxy-capped polythioether comprising: n moles of a reaction product of (i) a dithiol and a divinyl ether, and n +1 moles of a reaction product of (ii) a monoepoxyethylene, wherein the reaction product of the dithiol and the divinyl ether is prepared by reacting n +1 moles of a compound having HS-R¹Dithiols of the structure-SH and n moles of compounds having CH₂=CH-O-[-R⁵-O-]_m-CH=CH₂A divinyl ether of structure (la) is formed by reaction; wherein R is¹And R⁵Each independently selected from C_2-6N-alkylene radical, C_3-6Branched alkylene radical, C_6-8Cycloalkylene radical, C_6-10Alkylcycloalkylene, and [ - (CHR)³)_p-X-]_q-(CHR³)_r-, wherein each R³Independently selected from H, and-CH₃Each X is independently selected from O, S, -NH-, and-NR⁴-,R⁴Is selected from H, and-CH₃P is an integer of 2 to 6, q is an integer of 1 to 5, r is an integer of 2 to 10, and m is an integer of 1 to 10.

5. The epoxy-capped polythioether of claim 4, wherein the dithiol is selected from the group consisting of dimercaptodioxaoctane, and dimercaptodiethylsulfide.

6. The epoxy-capped polythioether of claim 4, wherein the divinyl ether is selected from the group consisting of alkenyl groups having 3 to 5 carbon atoms, and oxyalkylene groups having 3 to 5 carbon atoms.

7. The epoxy-capped polythioether of claim 4, wherein the divinyl ether comprises at least one alkyleneoxy group.

8. The epoxy-capped polythioether of claim 4, wherein the monoepoxyelene has the structure:

wherein R is²Is an olefinic group.

9. The epoxy-capped polythioether of claim 4, which is free of hydrolyzable chlorine.

10. The epoxy-capped polythioether of claim 4, having an epoxy equivalent weight range of less than 300.

11. The epoxy-terminated polymer of claim 4 wherein the divinyl ether is diethylene glycol divinyl ether.

12. The epoxy-terminated polymer of claim 8, wherein the monoepoxide olefin is selected from the group consisting of allyl glycidyl ether, 1, 2-epoxy-5-hexene, 1, 2-epoxy-7-octene, 1, 2-epoxy-9-decene, 4-vinyl-1-cyclohexene 1, 2-epoxide, butadiene monoepoxide, isoprene monoepoxide, and limonene monoepoxide.

13. The epoxy-terminated polymer of claim 5 wherein the dithiol comprises dimercaptodioxaoctane.

14. The epoxy-terminated polymer of claim 12, wherein the monoepoxyethylene comprises allyl glycidyl ether.

15. A process for preparing the epoxy-capped polythioether of claim 4, comprising: reacting n moles of a reaction product of (i) a dithiol and a divinyl ether, and n +1 moles of a (ii) monoepoxyethylene, wherein the reaction product of the dithiol and the divinyl ether is prepared by reacting n +1 moles of a compound having HS-R¹Dithiols of the structure-SH and n moles of compounds having CH₂=CH-O-[-R⁵-O-]_m-CH=CH₂A divinyl ether of structure (la) is formed by reaction; wherein R is¹And R⁵Each independently selected from C_2-6N-alkylene radical, C_3-6Branched alkylene radical, C_6-8Cycloalkylene radical, C_6-10Alkylcycloalkylene, and [ - (CHR)³)_p-X-]_q-(CHR³)_r-, wherein each R³Independently selected from H, and-CH₃Each X is independently selected from O, S, -NH-, and-NR⁴-,R⁴Is selected from H, and-CH₃P is an integer of 2 to 6, q is an integer of 1 to 5, r is an integer of 2 to 10, and m is an integer of 1 to 10.

16. The process of claim 15 wherein said reaction product of a dithiol and a divinyl ether is formed in the presence of a catalyst selected from the group consisting of free radical catalysts, and ultraviolet radiation.

17. The process of claim 15, wherein the catalyst does not include an acidic or basic compound, and does not produce an acidic or basic compound when decomposed.

18. The process of claim 15, wherein the catalyst comprises a free radical catalyst.

19. The process of claim 18 wherein the free radical catalyst is selected from the group consisting of azo catalysts, and alkyl peroxides.

20. The process of claim 19, wherein the azo catalyst is an azobis (isobutyronitrile) catalyst.