JPH02210074A - Method for improving adhesion of aramid-based synthetic fiber material - Google Patents

Abstract

PURPOSE:To improve adhesion to rubbers by applying an epoxy compound and aminoalkylvinyl polymer as an epoxy curing agent to an aramid-based synthetic fiber material, heat-treating the resultant fiber material and treating the heat-treated material with a specific adhesive solution. CONSTITUTION:An epoxy compound having >=2 epoxy groups, preferably polyglycidyl ether of a polyhydric alcohol and an aminoalkylvinyl polymer expressed by formula I (R<1> and R<2> are selected from H and 1-4C lower alkyl group; n is 1-3) as an epoxy curing agent are applied to an aramid-based syn thetic fiber material and the resultant fiber material is then heat-treated at 150-260 deg.C, subsequently treated with an adhesive containing an ethyleneurea compound expressed by formula II (R3 is aromatic hydrocarbon; p is 0, 1 or 2) or/and blocked polyisocyanate and RFL and further heat-treated at 150-260 deg.C to increase sticking ratio of the above-mentioned fiber to rubbers and remark ably improve adhesion thereof to the rubbers.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for improving the adhesion between an aramid synthetic fiber material and rubber. In particular, the present invention relates to a method for improving adhesion that provides an aramid synthetic fiber material with high adhesive strength and excellent rubber adhesion rate from a rubber composite molded product to an aramid synthetic fiber material.

[Prior art] Aramid synthetic fibers generally have excellent properties such as tensile strength, heat resistance, impact resistance, and dimensional stability, so they are used in tires, conduction belts, belts, hoses, etc. that are used under harsh conditions. Suitable as a reinforcement material for rubber products.

However, aramid synthetic fiber materials are inert in their molecular structure and highly crystalline, so they have poor adhesion to rubber and are usually used as adhesives between aramid synthetic fiber materials and rubber. If the existing resorcinol formalin latex (RFL) was used as is, it had the disadvantage that it could not form strong adhesion to rubber.

In the past, many proposals have been made to improve the adhesion between aramid synthetic fibers and rubber.
For example, some methods using plasma show good adhesion, but these methods are considered to have industrial problems in terms of reproducibility and uniformity. On the other hand, there are examples in which adhesiveness has been improved by the chemical bonding force between the epoxy groups formed on the surface of aramid synthetic fiber materials and the matrix resin through chemical treatment (JP-A-57-195136; Publication No. 59-74157 and Japanese Patent Publication No. 59-74157
9-184234), the improvement of adhesion by these methods is not necessarily satisfactory, and due to the low reactivity of aramid synthetic fiber materials, harsh reaction conditions are required, resulting in poor quality of the molded product. They often destroy higher-order structures or cause molecular chain cleavage, resulting in a decrease in mechanical performance.

In addition, we have also developed a method for improving adhesion using acrylate compounds such as epoxy acrylate and urethane acrylate (Unexamined Japanese Patent Publication No. 6
3-165583), molecular weight 1000-6000
Method for improving adhesion using liquid rubber (Japanese Patent Application Laid-Open No. 63-663
82 Publication), these aramid synthetic fibers treated by conventional methods have a low rate of rubber adhesion to the fiber material when the fiber material is peeled from the rubber composite molded product, and the aramid synthetic fiber material This has been a major obstacle to the use of aramid synthetic fibers for rubber reinforcement, as the adhesion between aramid and rubber is insufficient, and sufficient adhesive strength cannot be obtained.

[Problems to be Solved by the Invention] The present invention relates to a method for improving the adhesion of an aramid synthetic fiber material that has sufficient adhesion to rubber compared to conventional methods for improving the adhesion of an aramid synthetic fiber material. It is.

Means for Solving Problem C] As a result of intensive research into a method for treating aramid synthetic fibers that have sufficient adhesion to rubber, the present inventors found that a specific aminoalkylated vinyl polymer was used as an epoxy curing agent. The present invention was achieved by discovering that when coalescence is used, the adhesive performance is dramatically improved without causing any hardening of the fiber material. That is, the present invention provides an aramid synthetic fiber material with at least 2
As an epoxy compound and an epoxy curing agent having 1 or more epoxy groups, general formula (I) C-C- C=O 0-(CH-CHNI+) 11 ...
(I>1 R2 (wherein R and R2 are selected from the group consisting of hydrogen and lower alkyl groups of 1 to 4 carbon atoms, and the average value of n is 1 to 3) After the polymer is attached, it is heat-treated at 150 to 260°C, and in the subsequent step, the general formula (n) HO CH2Ill Ill CH2>
N-C-N-R3-(N-C-N <1>.

CH2CH2 ... (I[) (in the formula, R3 is an aromatic hydrocarbon group, p is 0.1 or 2
) An aramid-based synthetic fiber material characterized by being treated with an adhesive liquid containing an ethylene urea compound and/or a blocked polyisocyanate compound and resorcin formaldehyde latex (RFL), and heat-treated at 150 to 260°C. This invention relates to a method for improving adhesion.

Examples of the aramid synthetic fiber used in the present invention include poly-P-phenylene terephthalamide (PP'l''A), which is a loosely oriented aramid synthetic fiber.
It is marketed as Evlar (trade name) manufactured by Pont and Twaron (trade name) manufactured by Enka.

In addition, poly P-7 enylene-3,4-diphenyl ether terephthalamide, which is produced by introducing a diamine having an ether bond as a third component into poly P-phinidine terephthalamide, is marketed as a product manufactured by Teijin under the trade name Technora ■. ing.

The epoxy compound used in the present invention is a compound containing at least two or more epoxy groups in one molecule in an amount of 0.2 g equivalent or more per 100 g of the compound, and contains polyethylene glycol, glycerol, sorbitol, pentaerythritol, polyethylene glycol, etc. Reaction products of alcohols with halogen-containing epoxies such as epichlorohydrin, polyhydric phenols such as resorcinol, bis(4-hydroxyphenyl)dimethylmethane, phenol/formaldehyde resin, resorcinol/formaldehyde resin, and the above halogen-containing epoxies. Epoxy compounds obtained by oxidizing unsaturated bonds with peracetic acid or hydrogen peroxide, i.e., 1.4-epoxycyclohexene epoxide, 1.4-epoxycyclohexylmethyl 3.4-epoxycyclohexene Examples include carboxylate, bis(3,4-epoxy-6-methyl-cyclohexylmethyl)adipate, and the like. Among these, reaction products of polyhydric alcohols and epichlorohydrin, that is, polyglycysilyl ether compounds of polyhydric alcohols, are particularly preferred because they exhibit excellent performance.
Such epoxy compounds are usually used in the form of emulsions or solutions. To make emulsions or solutions, for example, such epoxy compounds may be used as they are, or dissolved in a small amount of solution depending on the quality, using known methods. It can be emulsified or dissolved using an emulsifier such as sodium alkylbenzenesulfonate, dioctylsulfosuccinate sodium salt, nonylphenol ethylene oxide adduct, and the like.

The epoxy curing agent used in the present invention has the following general formula (
I) -C-C- C=0 O-(CH-CHNH) H O RI R2 (wherein R1, R2 are selected from the group consisting of hydrogen and lower alkyl groups of 1 to 4 carbon atoms, n average, Value is 1~
It is 3. ) is an aminoalkylated vinyl polymer represented by:

A specific method for producing an aminoalkylated vinyl polymer is to copolymerize an unsaturated monomer containing a carboxyl group with another polymerizable unsaturated monomer, and convert the carboxyl group into an alkylene polymer. It is an aminoalkylated vinyl polymer made by reacting with imine.

More specifically, the carboxyl group-containing unsaturated monomers used in the production of the epoxy curing agent of the present invention include, for example, unsaturated monocarboxylic acids such as (meth)acrylic acid, geriatric acid, and crotonic acid; unsaturated dicarbonates such as maleic acid, itaconic acid and fumaric acid, or
Examples include monoesters thereof, and one type or a mixture of two or more types selected from these groups can be used.

In the polymer obtained by copolymerizing the carboxyl group-containing unsaturated monomer used in the production of the epoxy curing agent of the present invention and other polymerizable unsaturated monomers, other polymerizable unsaturated monomers may be used. The monomer is not particularly limited as long as it is a monomer that can be polymerized with the above-mentioned carboxyl group-containing unsaturated monomer, such as (meth)acrylamide, N-methylol (
meth)acrylamide, 2-hydroxyethyl(meth)
Acrylate, 2-hydroxypropyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate
Acrylate, n-propyl (meth)acrylate, inglovir (meth)acrylate, n-butyl (meth)acrylate
acrylate, isobutyl (meth)acrylate, t-
Butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, lauryl (meth)acrylate, 2-methoxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, methoxypolyethylene glycol mono(meth)acrylate Acrylate, (meth)acrylonitrile, styrene, α-methylstyrene, vinyl acetate, vinyl propionate, (meth)acrolein, dimethylaminoethyl (meth)acrylate, vinyl chloride, ethylene, butadiene, N-phenylmaleimide, and diethylaminoethyl (meth) ) acrylate, etc., and one type or a mixture of two or more types selected from these groups can be used.

The precursor carboxyl group-containing polymer for obtaining the epoxy curing agent of the present invention can be obtained by copolymerizing the above-mentioned carboxyl group-containing unsaturated monomer and copolymerizable unsaturated monomer according to a known procedure. Polymerization methods such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization can be employed, but in the present invention, production by solution polymerization or emulsion polymerization is most preferred.

In addition, when employing the solution polymerization method, the aa that can be used includes, for example, toluene, xylene, and other high-boiling aromatic solvents, ester solvents such as ethyl #acid, butyl #acid, and seronlubu acetate, and methyl alcohol. ,
Examples include alcohol solvents such as ethyl alcohol, n-butyl alcohol, ethylene glycol monoethyl ether, propylene glycol monomethyl ether and isobutyl alcohol, ketone solvents such as methyl ethyl ketone and methyl isobutyl getone, etc.; One type or a mixture of two or more types can be used. Examples of polymerization initiators that can be used include azobisisobutyronitrile, benzoyl peroxide, and di-tert-butyl peroxide.

The polymerization temperature of the carboxyl group-containing unsaturated monomer and the copolymerizable unsaturated monomer is room temperature to 200°C, preferably 40 to 1
It is in the range of 20°C.

The aminoalkylated vinyl polymer which is the epoxy curing agent of the present invention is an aminated product obtained by reacting the carboxyl group contained in the above carboxyl group-containing polymer with an alkylene imine.

The amination reaction is carried out at, for example, 40 to 150°C, preferably 5°C.
This can be achieved by mixing and stirring the carboxyl group-containing polymer of the precursor and the alkylene imine under a temperature condition of 0 to 100°C.

, As the alkyleneimine, for example, ethyleneimine,
Propylene imine, butylene imine, etc. can be used.

Also, N-(2-aminoethyl)aziridine, N-(3-
N-(aminoalkyl) such as aminopropyl)aziridine, N-(2-amino-10vyl)propyleneimine, etc.
Substituted alkyleneimines can be used as well.

When employing the emulsion polymerization method, various emulsifiers are used, but anionic and nonionic emulsifiers are preferred;
Protective colloids such as suborivinyl alcohol and the like may also be used.

As the polymerization catalyst, commonly used persulfates, peroxides, persulfate-acidic FiXvi salts, etc. can be used.

The polymerization temperature of the carboxyl group-containing unsaturated monomer and copolymer is in the range of room temperature to 95°C, preferably 40 to 70°C.

The aminoalkylated vinyl polymer which is the epoxy curing agent of the present invention is an aminated product obtained by reacting the carboxyl group contained in the above carboxyl group-containing polymer with an alkylene imine.

The amination reaction is carried out at, for example, 40 to 95°C, preferably 45°C.
This can be achieved by mixing and stirring the carboxyl group-containing polymer of the precursor and the alkylene imine at a temperature of ~70°C.

As the alkylene imine, for example, ethyleneimine, propylene imine, butylene imine, etc. can be used. Further, N-(aminoalkyl)-substituted alkyleneimines such as N-(2-aminoethyl)aziridine, N-(3-aminopropyl)aziridine, N-(2-aminopropyl)propyleneimine, etc. can be used similarly.

The composition used in the present invention contains resorcinol/formalin/rubber latex, and the resorcinol/formalin/rubber latex used here is usually called RF L, and the molar ratio of resorcinol and formaldehyde is 1. =0°1 to 1:8, preferably 1:0°5 to 1:6.

Examples of the rubber latex used in the present invention include natural rubber latex, styrene-butidiene copolymer latex, vinylpyridine-styrene-butadiene terpolymer latex, nitrile rubber latex, chloroprene latex, etc., and these may be used alone or in combination. and use it. Among these, vinyl-pyridine-styrene-butadiene terpolymer latex shows the best performance when used alone or in combination in half or more.

The blending ratio of resorcinol/formalin and rubber latex is 1=1 to 1:15, preferably 1:3 in solid weight ratio.
It is desirable that the ratio is in the range of 1:12 to 1:12.

If the ratio of rubber latex is too small, the treated aramid synthetic fibers will become hard and have poor fatigue resistance, whereas if the ratio is too large, satisfactory adhesive strength and rubber adhesion rate will not be obtained.

The ethylene urea compound used in the present invention has the general formula % (wherein R3 is an aromatic hydrocarbon group, p is 0.1 or 2
) Ethylene urea compounds represented by:

Typical compounds include aromatic and aliphatic incyanates such as octadecyl isocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, metaxylylene diisocyanate, diphenylmethane diisocyanate, naphthylene diisocyanate, triphenylmethane triisocyanate, and ethyleneimine. In particular, aromatic ethylene urea compounds such as diphenylmethane diethylene urea give good results.

Next, the blocked polyisocyanate compound used in the present invention is an addition compound of a polyisocyanate compound and a blocking agent, and the blocking component is liberated by heating to produce an active polyisocyanate compound. Examples of the polyisocyanate compound include polyisocyanates such as tolylene diisocyanate, metaphenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, polymethylene polyphenylisocyanate, and triphenylmethane triisocyanate, or these polyisocyanates, trimethylolpropane, and pentaerythritol. A compound having two or more active hydrogen atoms such as N
Examples include terminal NCO group-containing polyalkylene glycol adduct polyisocyanates obtained by reacting at a molar ratio such that GOloH>1. In particular, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenylisocyanate are preferred because they exhibit excellent performance.

Examples of blocking agents include phenols such as phenol, thiophenol, cresol, and resorcinol;
Tertiary alcohols such as t-butanol and t-pentanol, aromatic secondary amines such as diphenylamine and xylidine, imides such as phthalic acid imide, lactams such as caprolactam and valerolactam, acetoxyme, methyl ethyl ketone oxime , oximes such as cyclohexane oxime, and acidic sodium sulfite.

[Examples] The present invention will be described below with reference to Examples, but the present invention is not limited to these in any way.

In addition, parts in the examples mean parts by weight unless otherwise specified. % in the examples means % by weight unless otherwise specified.

Reference Example 1 An aminoalkylated vinyl polymer (A) was produced as follows.

500 parts of ethylene glycol monoethyl ether was charged as a solvent into a four-bottle flask equipped with a stirrer, a thermometer, a condenser, a dropping funnel, and a nitrogen gas introduction tube, and the temperature was raised to 80°C, and nitrogen gas was blown into it. Meanwhile, a mixture consisting of 30 parts of methacrylic acid, 35 parts of methyl methacrylate, 135 parts of butyl methacrylate, 300 parts of butyl acrylate, and 10 parts of benzoyl peroxide was added dropwise from the dropping funnel over 2 hours, and the mixture was further maintained at 80°C for 6 hours. After that, it was cooled to room temperature to obtain a solution of the polymer containing carboxyl groups.
One hour after the completion of the 0-drop addition, the temperature was raised to 75°C, held at the same temperature for 5 hours, a distillation apparatus was set in a 4-loaf flask, and the mixture was heated under reduced pressure. Unreacted ethyleneimine was distilled off together with ethylene glycol monoethyl ether, and during this time, ethylene glycol monoethyl ether was added in an amount equal to the amount reduced by distillation. Then, it was cooled to room temperature, adjusted to a solid content of 50% with ethylene glycol monoethyl ether, and an aminoalkylated vinyl polymer for epoxy curing (
A) was obtained.

Reference Example 2 An aminoalkylated vinyl polymer (B) was produced as follows.

750 parts of propylene glycol monomethyl ether as a solvent was charged into a four-bottle flask equipped with a stirrer, thermometer, condenser, dropping funnel, and nitrogen gas introduction tube, and the mixture was heated to 80'C.
A mixture consisting of 45 parts of methacrylic acid, 400 parts of butyl acrylate, 55 parts of butyl methacrylate, and 25 parts of azobisisobutyronitrile was added through a dropping funnel over a period of 2 hours while blowing nitrogen gas into the mixture. The mixture was added dropwise and further held at 80°C for 6 hours, and then cooled to room temperature to obtain a solution of the polymer containing carboxyl groups.Next, 50 parts of propyleneimine was added dropwise to the above flask over 30 minutes. One hour after finishing the dripping,
After raising the temperature to 75°C and keeping it at the same temperature for 6 hours, a distillation device was set in the four-roof flask, and heated under reduced pressure to distill off unreacted propylene imine together with propylene glycol monomethyl ether. , half the amount of propylene glycol monomethyl ether reduced by distillation was added. The mixture was then cooled to room temperature and adjusted to a solid content of 60% with propylene glycol monomethyl ether to obtain an aminoalkylated vinyl polymer (B) for curing epoxy.

Reference Example 3 Aminoalkylated vinyl polymer (C) was produced as follows.

Add 460 parts of deionized water and 2 parts of anionic emulsifier to a four-bottle flask equipped with a stirrer, thermometer, condenser, dropping funnel, and nitrogen gas inlet tube, and heat to 70°C.Next, add 2 parts of ammonium persulfate. 60 parts of styrene,
A mixture consisting of 125 parts of butyl acrylate and 15 parts of acrylic acid was added over 1 hour to perform emulsion polymerization, and the mixture was cooled to room temperature to obtain an emulsion polymer containing carboxyl groups.

Next, a mixture consisting of 8 parts of ethyleneimine and 28 parts of deionized water was added to the flask, and after reacting at 50°C for 3 hours, the mixture was neutralized with ammonia to pH 9.0, and an amino acid for curing epoxy with a solid content of 30% was added. An alkylated vinyl polymer (C') was obtained.

Examples 1-5. Comparative Examples 1-2 Aramid synthetic fiber (Kevl manufactured by Du Pont)
Aramid synthetic fiber cord (30,000
/3. 20x20 twists/10cm) was immersed in the blended solution (first treatment solution) listed in Table 1 below, and heated at 200°C.
Cured by heating for minutes.

Next, the treated aramid synthetic fiber cord was immersed in the blended RFL liquid (second treatment liquid) listed in Table 2, the RFL adhesive was applied to the cord surface, and the cord was heated at 16.0°C for 1 minute, then at 250°C. Heat treatment was performed for 2 minutes to dry the adhesive and cause an adhesive reaction.

Next, the following evaluations were performed using the obtained rubber reinforcing fiber cords and the rubber compositions for embedding cords shown in Table 3.

The T-adhesive crab-treated cords were embedded in the rubber blocks listed in Table 3 and vulcanized under pressure at 150°C for 3 minutes, and then each treated cord was pulled out from the rubber block at a speed of 200 mm/min, at which time it was detected. The load is expressed in K g/cm.

Five treated cords listed in Table 3 were embedded near the surface layer of the rubber sheet and vulcanized under pressure at 150'C for 30 minutes, then the five treated cords were inserted from the rubber sheet at a speed of 200 mm/min. ! (The load detected at that time when separated by I is expressed in kg15.

The resultant cord is observed with the naked eye, and the percentage of the cord surface to which rubber is attached is expressed as a percentage.

The results obtained above are shown in Table 4.

Embedded in a carcass compound rubber for automobile tires as a cross-ply (cord density 27 ends/254 cm) of crab 2 Gly treated cords with peeling between plies at a 90 degree angle, 160”C
After vulcanization in a press for 20 minutes, both plies were vulcanized at 200
The force required for peeling at a tensile speed of mm/min is K g
/ 3 cm.

Rubber adhesion rate: Peeled from the rubber during the above inter-ply peel force measurement Table Epoxy 1: Denacol EX-313 water-soluble glycerol diglycidyl ether EE former 41 manufactured by Nagase Chemical Industries, Ltd. Epoxy 2: Nagase Chemical Industries, Ltd. ) Denacol EX-810 water-soluble ethylene glycol diglycidyl ether EEW112
Table 2 N-cyclohexyl-2-benzothiazolesulfenamide Table 2 Styrene/butadiene/vinylpyridine latex (
JSR0650 (Japan Synthetic Rubber Co., Ltd. product) Examples 6 to 8. Comparative Examples 3-4 Aramid synthetic fiber (product KevI manufactured by Du Pont)
Aramid synthetic fiber cord (30000
/3. 20×20 twists/10 cm) was immersed in the blended solution (first treatment solution) listed in Table 5, and heated and cured at 200° C. for 2 minutes.

Next, the above-mentioned treated aramid synthetic fiber cord was immersed in the blended RFL liquid (second treatment liquid) listed in Table 6, the RFL adhesive was applied to the cord surface, and the cord was heated at 160°C for 1 minute and then at 250°C for 2 minutes. Heat treatment was performed to cause dry heat and adhesive reaction of the adhesive.

Next, evaluations similar to those in Example 1 were conducted using the obtained rubber reinforcing fiber cords and the rubber compositions for embedding cords shown in Table 3. The results obtained are shown in Table 7.

Table Epoxy 1: Denacol Eχ-313 water-soluble glycerol diglycidyl ether EEW141 manufactured by Nagase Chemical Industries, Ltd. Epoxy 2: Denacol EX-810 water-soluble ethylene glycol diglycidyl ether EEI411 manufactured by Nagase Chemical Industries, Ltd.
Table 2 Styrene/butadiene/vinylpyridine latex (
JSR0650 Product of Japan Synthetic Rubber Co., Ltd.) [Effects of the invention] The method of improving the adhesion of aramid synthetic fiber materials of the present invention has high adhesive strength, and also reduces the adhesion rate of rubber to aramid synthetic fiber materials from rubber composite molded products. We can provide excellent aramid synthetic fiber materials.

Claims (1)

[Claims] (1) As epoxy compounds and epoxy curing agents having at least two or more epoxy groups for aramid synthetic fiber materials, there are general formulas (I) ▲mathematical formulas, chemical formulas, tables, etc.▼...(I) (R_1 in the formula , R_2 is selected from the group consisting of hydrogen and lower alkyl groups of 1 to 4 carbon atoms, and the average value of n is 1
~3. ) After attaching the aminoalkylated vinyl polymer represented by 150 to ▲ mathematical formulas, chemical formulas, tables, etc. or 2) Aramid-based synthesis characterized by treating with an adhesive liquid containing an ethylene urea compound and/or a blocked polyisocyanate compound and resorcinol formaldehyde latex (RFL), and heat-treating at 150 to 260°C. Method for improving adhesion of fiber materials.