JPS6367587B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a polyester fiber material for rubber reinforcement that has improved adhesion to rubber, and particularly an adhesion of a polyester fiber material that has significantly improved adhesive strength when exposed to high temperatures for a long time while embedded in rubber. Regarding processing method. Polyester fibers whose main component is polyethylene terephthalate have excellent physical and chemical properties and are useful as reinforcing materials for rubber products such as tires and conveyor belts. It is difficult to achieve sufficient adhesion to rubber using only a mixture of RFL (hereinafter referred to as RFL). Therefore, adhesive formulations using epoxy compounds, isocyanate compounds, halogenated phenol compounds, etc. have been developed and have come to be widely used as reinforcing materials for rubber products such as automobile tires, hoses, and belts. However, the conventionally known polyester fibers subjected to adhesive treatment have the following problems when considering the development of new uses for them. That is, when a rubber product is exposed to high temperatures for a long period of time, the adhesive strength between the rubber and polyester fibers is significantly reduced (hereinafter referred to as heat-resistant adhesiveness).
Such poor heat-resistant adhesion properties have made it impossible to apply polyester fibers to tires for large vehicles, which generate a large amount of heat during running. The cause of such poor heat-resistant adhesion is that when polyester fiber-reinforced rubber products are exposed to high temperatures, ammonia, amines, and moisture generated from the rubber compound cause deterioration of the polyester fiber itself and deterioration of the adhesive bond. It is said that there is
Various proposals have been made for improvement. Most of these proposals concern additives to rubber, such as the addition of aldehydes, lactones, etc. to rubber compounds (Japanese Patent Publication No. 1986-21814), and the addition of quinones and hydroquinones (Japanese Patent Publication No. 1973-21814).
34589), and the addition of quicklime (Japanese Patent Application Laid-Open No. 1983-29471). However, the method of adding these chemicals into rubber has drawbacks such as deterioration of the physical properties of the rubber and little effect. In addition, a method has been proposed in which isocyanate, polycarbonate, and a specific metal complex are added during spinning of polyester, and mixed spinning is carried out. However, when polyfunctional isocyanates are added to the polymer, gelation tends to occur in some areas, and when metal complexes are added, foreign matter is likely to be generated, which affects the physical properties of polyester fibers. This made it difficult to apply it to actual production. The present inventors conducted various studies to solve this problem by optimizing the adhesive processing method. The heat-resistant adhesive properties of various conventionally known adhesive treatment methods are as follows. As a typical adhesive treatment agent, a reaction product of halogenated phenol, resorcinol, and formaldehyde, such as 2,6-bis(2',4'-dihydroxyphenylmethyl)-4-chlorophenol, is added to RFL. , a method using a mixture (Japanese Patent Publication No. 46-11251) is known. According to this method, the adhesive strength under normal temperature conditions (hereinafter referred to as initial adhesive strength) is excellent, but
However, depending on the mixing operation conditions of 2,6-bis(2',4'-dihydroxyphenylmethyl)-4-chlorophenol and RFL, it may not be possible to obtain effective adhesive strength, and this may be difficult to achieve in industrial production. Another problem is that it lacks stability when considering the above, and furthermore, its adhesive strength when exposed to high temperatures for a long time in rubber (hereinafter referred to as heat-resistant adhesive strength) is extremely low. On the other hand, in the method of applying blocked isocyanate in the first stage and RFL in the second stage, as disclosed in Japanese Patent Publication No. 52-19874 and Japanese Patent Application Publication No. 49-67959, the adhesive strength when exposed to high temperature is I learned that the retention rate is relatively high. However, with this method, the initial adhesive strength was low and the heat-resistant adhesive strength was not sufficient. Furthermore, in order to improve such heat-resistant adhesive strength, a method is disclosed in which 0-phenylphenol or the like is used as a carrier in the first stage, blocked isocyanate is applied in the first and/or second stage, and RFL is applied in the second stage. (Japanese Patent Application Laid-open No. 56-2155). However, although this treatment method also considerably improved the heat-resistant adhesive strength, it was still insufficient, and the resulting cords were hard. In addition, when applying blocked isocyanate using a known method to improve adhesion,
A major problem is that the adhesive-treated fibers become hard and difficult to handle when used as a rubber reinforcing material. Therefore, adhesive-treated fibers to which blocked isocyanates have been applied by known methods have not been of much practical use. In view of the above-mentioned situation, the inventors of the present invention have made extensive studies and found that a mixed solution of a resorcinol-formaldehyde initial condensate and rubber latex is used as a first-stage treatment liquid when imparting adhesiveness to rubber to polyester fibers. Add the compound shown in the following formula () to this and heat at least at 15 to 35℃.
Adhesion of polyester fibers for rubber reinforcement characterized by using fibers aged for 24 hours and using an aqueous dispersion of blocked isocyanate or an aqueous liquid containing this aqueous dispersion as a main component as the second-stage treatment liquid. It has been found that when the treatment method is applied, the initial and heat-resistant adhesive strength becomes very high, and the hardness of the adhesive-treated fibers is also within a preferable range for handling. However, in the formula (), X is a chlorine or bromine atom, Y and Z are a hydrogen atom, a hydroxyl group, a chlorine atom, a bromine atom, or an alkyl group having 1 to 4 carbon atoms, and n is a 1 to 3 alkyl group. is an integer. The polyester fiber used in the present invention is polyethylene terephthalate, or a high molecular weight linear polyester mainly composed of ethylene terephthalate units, which is melt-spun and further stretched as necessary.
It is a twisted or woven product, and includes various forms such as filament, cord, woven fabric, and non-woven fabric. Naturally, the method of the present invention is also applicable to the use of a mixture of such polyester fibers and other fibers when the polyester fibers are the main component. In addition, as shown in Japanese Patent Publication No. 55-4845, for example, this polyester fiber can be produced by adding an epoxy compound to the surface of the polyester fiber at the undrawn stage and then heating and drawing it, or by further twisting the fiber. It may also be a finely woven cord or a finely woven fabric. In such a case, the effects of the present invention are further exhibited and excellent results can be obtained. In the present invention, polyester fibers are subjected to two-stage treatment, and a reaction mixture obtained by condensing the compound of () and a resorcinol-formaldehyde initial condensate used as the first-stage treatment liquid, and a mixture of rubber latex (formula ()) A reaction mixture of a compound and RFL) can be obtained by adding a compound of formula () at any stage during RFL production and performing condensation ripening, but since high adhesive strength can be obtained more stably, Preferably, the product is obtained by adding a compound of the formula () after producing RFL and aging it at 15 to 35°C for 24 hours or more. If the aging time is less than 24 hours, the condensation reaction between the compound of formula () and the resorcinol-formaldehyde initial condensate will not proceed sufficiently, and the resulting adhesive strength will tend to be low and vary widely. . The amount of the compound of formula () added to RFL is preferably 10 to 60% by weight based on the total solid content after addition. Various kinds of blocked isocyanates can be used for the second-stage treatment liquid. For example, although the adhesion-improving effect is observed even when a block of an aliphatic isocyanate compound is used, a block of an aromatic isocyanate compound is preferable because it has a greater effect for the same amount applied. Further, as the blocking agent, one that easily regenerates isocyanate by heat treatment at 260° C. or lower is preferable. An aqueous dispersion of blocked isocyanate is prepared by dispersing blocked isocyanate, which will be exemplified later, in water in a pulverizer such as a ball mill using auxiliary agents such as a surfactant, a thickener, and an antifoaming agent. It is something. In addition, an epoxy compound,
A small amount of the same reaction mixture as used in RFL and the first bath may be mixed. In this case, it is preferable that the solid content weight ratio of the blocked isocyanate is 60% by weight or more. Furthermore, the treatment referred to in the present invention refers to applying the above-mentioned treatment liquid to polyester fibers by a conventional method such as kiss roll, grid, spray, impregnation, or coating, and then using a slit heater, an oven, a hot plate, or a heating roller. etc. using
Heat treatment is performed at 100 to 260°C for 1 second to 10 minutes. More preferable temperature conditions are that the drying temperature after application of the treatment liquid is 100 to 180°C, and the subsequent heat treatment temperature is 220 to 260°C in both the first and second stages. However, it is also possible to carry out the heat treatment following drying only in the first stage or second stage. Specific examples of the block isocyanate compound referred to in the present invention include monoisocyanates such as n-amyl isocyanate, phenyl isocyanate, o- or p-tolyl isocyanate, α- or β-naphthylisocyanate, and nitrophenyl isocyanate; Hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,4-chlorophenylene diisocyanate,
4,4'-diphenylmethane diisocyanate,
1,5-naphthylene diisocyanate, ω,
Diisocyanates such as ω'-(ditrimethylene thiolether) diisocyanate, S-triazine triisocyanate, thiophosphoric acid tris(p-isocyanate phenyl) ester, triphenylmethane triisocyanate, diphenylmethane triisocyanate, butane-1,2, Triisocyanates such as 2-triisocyanate, trimethylolpropane tolylene diisocyanate teradduct, 2,4,4'-diphenyl ether triisocyanate, general formula Polyisocyanate compounds such as polyfunctional isocyanates such as polymethylene polyphenyl isocyanate (including the case of crude diphenylmethane diisocyanate), which is a mixture of n = 0, 1, 2, 3, 4, etc. one or more of the following, and phenols such as phenol, p-chlorophenol, thiophenol, cresol, and resorcinol, tertiary alcohols such as t-butanol, t-pentanol, and t-butanethiol, and diphenylamine. , aromatic amines such as diphenylnaphthylamine and xylidine, imides such as succinimide and phthalic acid imide, active methylene compounds such as acetoacetate, acetylacetone, and malonic acid diester, 2-mercaptobenzothiazole, and t-dodecylmercaptan. Mercaptans such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, lactams such as β-propiolactam, urea, diethylene urea,
Ureas such as thiourea, oximes such as acetoxime, cyclohexanone oxime, benzophenone oxime, methyl ethyl ketone oxime, diaryl compounds such as carbazole, phenylnaphthylamine, N-phenylxylidine, bisulfites, boric acids, It is obtained by reacting one or more isocyanate blocking agents such as α-pyrrolidone by a known method. Preferably, compounds having an isocyanate group bonded to an aromatic nucleus are blocked with the above-mentioned blocking agents, and blocked compounds of phenols, oximes, and lactams are particularly preferable. The reason why compounds having an isocyanate group bonded to an aromatic nucleus are preferred is that these compounds have a high boiling point and good heat resistance, and are useful for improving heat-resistant adhesive properties. Furthermore, the reason why phenols, oximes, and lactams are preferable as blocking agents is that the dissociation temperature of these blocking agents is close to the heat treatment temperature during adhesive treatment, and they can effectively generate a high concentration of isocyanate groups during heat treatment. This seems to be because it allows for Further, in the present invention, specific examples of the compound represented by the formula () include 2,6-bis(2',4'-dihydroxyphenylmethyl)-4-chlorophenol, 2,6-bis(2', 4'-dihydroxyphenylmethyl)-4-bromophenol, 2,6-
Bis(2',4'-dichlorophenylmethyl)-4-
Examples include chlorphenol, 2,6-bis(phenylmethyl)-4-chlorophenol, and the like. These compounds are derived, for example, from halogenated phenols, formaldehyde and phenol derivatives. Furthermore, these compounds do not need to be a single compound, and may be a mixture of two or more of the above-mentioned compounds, or a mixture where n=1 to 3 in formula (). Furthermore, RFL as used in the present invention refers to an initial condensate obtained by reacting resorcin and formalin under an acid or alkali catalyst, styrene-butadiene latex, butadiene latex, acrylonitrile-butadiene latex, chloroprene latex, It is an aqueous liquid made by mixing one or more latexes such as styrene-butadiene-vinylpyridine latex and natural rubber latex, and the molar ratio of resorcin and formalin is 1:1.
The ratio of the resorcinol-formalin initial condensate to the latex is preferably from 5:95 to 40:60 in solid weight ratio. In the present invention, it is preferable that the amount of the first-stage treatment liquid adhered to the polyester fibers is 1 to 10% by weight in terms of solid content, and the deposition rate of the blocked isocyanate is the same as that of the first-stage treatment liquid. It is preferably 0.01 to 50% by weight, particularly 0.05 to 20% by weight of the attached solid content. The polyester fibers treated according to the invention exhibit high adhesion when embedded in rubber, while having adequate flexibility, and exhibit no loss of adhesion even when exposed to high temperatures for long periods in rubber. It has a good property of extremely low The following may be considered as the reason why such an effect appears. When a blocked isocyanate compound based on a polyfunctional isocyanate compound is used as the first-stage treatment liquid, the blocked isocyanate generates isocyanate during heat treatment, and this isocyanate reacts with the polyester fiber and turns into a hard resin. to harden the polyester fibers. However, in the case of the first-stage treatment liquid defined in the present invention, it does not harden much even by heat treatment and has appropriate flexibility. Incidentally, when a block of a monoisocyanate compound is used in the first stage, no effect of improving adhesive strength is observed. The blocked monoisocyanate compound applied in the second stage is present in the first stage treatment solution and on the surface in the form of a block or as an isocyanate. It is thought that this blocked monoisocyanate or isocyanate promotes the action of the first-stage adhesion treatment liquid on the polyester, and at the same time captures the amine compounds etc. present in the rubber, thereby improving heat-resistant adhesion. Thus, by carrying out the present invention, it is possible to produce a polyester fiber material that exhibits very little loss of adhesive strength even when exposed to high temperatures for long periods of time in rubber, so that it can be used, for example, under high temperature, long-term vulcanization, or under harsh conditions. Polyester fiber materials can also be used as reinforcing materials for large tires and the like that must be used in large-sized tires, and the effects they bring are truly significant. In addition, as a second-stage treatment liquid, an epoxy compound, RFL,
Addition of a reaction mixture of the compound of formula () and RFL, etc. can increase the viscosity of the treatment liquid and increase the uniformity of application of the blocked isocyanate. Hereinafter, the present invention will be explained in more detail based on Examples, but of course the present invention is not limited to the Examples. In addition, in the examples, parts mean parts by weight. The bending hardness of the cord is measured using the Gurley method, and the larger the measured value, the harder it is. Example 1 Resorcinol 18.5 parts 37% formalin aqueous solution 27.2 parts 1% caustic soda aqueous solution 5.0 parts Water 396.6 parts were mixed and dissolved, and aged at 25°C for 90 minutes. “Hiker” 2518FS) 278.8
and 142.0 parts of 40% SBR latex (“Nitsupol” LX110 manufactured by Nippon Zeon Co., Ltd.) and heated at 25°C.
Aged for 6 hours. 2,6-bis(2',4'-dihydroxyphenylmethyl)-4 was added to the RFL solution prepared in this way.
-Aqueous ammonia solution of chlorphenol (“Valkabond-E” manufactured by Varnax Co., Ltd., solid content 20%)
530 parts of were added and further aged at 25°C for 30 hours (hereinafter referred to as liquid A). On the other hand, a 10.0 part phenol block powder of triphenylmethane triisocyanate ("DresmodurR" manufactured by Bayer) "Sanmorin OT" (manufactured by Sanyo Chemical Co., Ltd.) 0.5 part "Maraspers DY" (manufactured by Marathon)
1.0 parts of water and 88.5 parts of the mixture were mixed together and pulverized and dispersed in a ball mill for 24 hours to obtain a 10% aqueous dispersion of blocked isocyanate. (hereinafter referred to as B liquid) Next, three polyethylene terephthalate drawn yarns of 1000 denier 192 filament were twisted downward 40 times/
A cord was made by twisting the yarn 10cm long and twisting it 40 times/10cm. Add this code to liquid A as the first processing liquid.
It was immersed for seconds, and then dried at 150° C. for 3 minutes while keeping the length constant. Furthermore, it was immersed in liquid B as the second stage treatment liquid for 3 seconds, and heated at 150°C for 2 seconds while keeping the length constant.
After drying for a minute, it was heat-treated at 245°C for 90 seconds. The rate of adhesive adhesion to the cord was 5.2% in the first layer and 0.6% in the second layer, based on the weight of the polyester cord. The adhesive-treated cord thus obtained was embedded in a rubber compound having the composition shown in Table 1 below, and was heated at 140°C for 40 minutes under a pressure of 50°C.
Press vulcanization was performed at Kg/cm ² and the H adhesive strength was measured, which was taken as the initial adhesive strength. In addition, in order to know the heat-resistant adhesive strength, we separately prepared 70℃ at 170℃.
Vulcanization was carried out at a pressure of 50 kg/cm ² for 30 minutes, and the H adhesive strength was evaluated. The results are shown in Table 2 below.

[Table] As is clear from Table 2, Example 1 exhibited very high initial and heat-resistant adhesive strength, as well as good flexibility. Comparative Examples 1 and 2 In Example 1, immersion in Solution A without applying Solution B, drying at 150°C for 3 minutes, 245
Comparative Example 1 shows the case of heat treatment at ℃ for 90 seconds.
and VALKABOND E was not added when preparing liquid A,
Comparative Example 2 is a case in which the same procedure as in Example 1 was carried out except that 424 parts of water was added instead, and the results are shown in Table 2 below. It can be seen from Table 2 that a polyester fiber material with high initial adhesive strength and high heat-resistant adhesive strength can only be obtained when a reaction mixture of blocked isocyanate and the compound of formula ()-RFL is used together.

[Table] Examples 2, 3, Comparative Examples 3, 4 The same procedure as in Example 1 was carried out except that the aging time after mixing VALKABOND E and RFL was changed as shown in Table 3. . Table 3 shows the average value and the difference between the highest and lowest values obtained by conducting the experiment three times with different lots of liquid A.

[Table] From Table 3, if the aging time is shorter than 24 hours,
It can be seen that when the condensation reaction between "VALKABOND-E" and RFL is insufficient, the adhesive strength varies greatly and only a low average adhesive strength can be obtained. Examples 4 to 7, Comparative Example 5 Example 4 is a case in which the phenol block of triphenylmethane triisocyanate in Example 1 was not used, and the phenol block of O-tolylisocyanate was used instead.
Example 5 is a case in which a phenol block of diphenylmethane diisocyanate is used, and Example 6 is a case in which a 2-butanone oxime block of triphenylmethane triisocyanate is used.
Example 7 shows the case where an ε-caprolactam block of triphenylmethane triisocyanate is used. Comparative Example 5 shows a case where in Example 1, liquid B was used as the first-stage treatment liquid and liquid A was used as the second-stage treatment liquid.

[Table] Comparative example 5 in which the order of use of treatment liquids was changed from Table 4
It can be seen that the initial adhesive strength is low and the polyester fibers are hardened. Comparative Examples 6 and 7 For comparison, a carrier-containing spinning oil treatment solution was prepared by adding 18 parts of VALKABOND E to a mixture of 42 parts of a spinning oil mainly composed of fatty acid ester and a nonionic surfactant in 540 parts of water. Three polyethylene terephthalate drawn yarns of 1000 denier 192 filament obtained by applying and drawing the yarn were twisted downward 40 times/
A cord was made by twisting the yarn 10cm long and twisting it 40 times/10cm. Add this code to liquid B as the first processing liquid.
After being immersed for 3 seconds at 220°C and heat treated for 3 minutes, immersed in RFL solution as the second treatment solution for 3 seconds and heated at 150°C.
Comparative Example 6 is a case in which 18 parts of glycerin diglycidyl ether was added in place of Vulgabond E added to the spinning oil in Comparative Example 6, and the yarn was spun and twisted. The cord obtained was immersed in the first treatment solution, which was prepared by mixing 10 parts of VALKABOND E and 90 parts of water, and treated at 150°C for 2 minutes, followed by 100 parts of solution B, 6 parts of glycerin diglycidyl ether, and 200 parts of RFL solution. Comparative Example 7
are shown in Table 5 together with Example 1.

[Table] It can be seen from Table 5 that the polyester fiber material obtained by the method of the present invention has high heat-resistant adhesive strength and is highly flexible, making it suitable as a reinforcing material for large tires.

Claims (1)

[Claims] 1. When imparting adhesion to rubber to polyester fibers, a mixed solution of a resorcinol-formaldehyde initial condensate and rubber latex is prepared as a first-stage treatment solution, and the mixture is treated according to the following formula (). The compound shown above is added and aged at 15 to 35°C for at least 24 hours, and the second-stage treatment liquid is an aqueous dispersion of blocked isocyanate or an aqueous liquid containing the dispersion as the main component. A method for adhesion processing of polyester fibers for rubber reinforcement, characterized by: However, in the formula (), X is a chlorine atom or a bromine atom, Y and Z are a hydrogen atom, a hydroxyl group, a chlorine atom, a bromine atom, or an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 3. It is. 2. The polyester fiber for rubber reinforcement according to claim 1, wherein the blocked isocyanate is obtained by blocking an aromatic isocyanate compound having an isocyanate group directly bonded to an aromatic nucleus with phenols, caprolactams, or oximes. Adhesion processing method. 3 The solid content of the first-stage treatment liquid applied to the polyester fiber is 1 to 10% by weight based on the polyester fiber, and the solid content of the second-stage treatment liquid is 0.01 to 50% by weight of the solid content of the first-stage treatment liquid. A method for adhesion treatment of polyester fibers for rubber reinforcement according to claim 1.