JPS6055632B2 - Method for producing polyester fiber material with improved adhesion to rubber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a polyester fiber material for rubber reinforcement that has improved adhesion to rubber compounds, especially when exposed to high temperatures for a long time while embedded in a rubber compound. The present invention relates to a method for producing a polyester fiber material for rubber reinforcement with significantly improved strength reduction.

Although polyester fiber has high tensile strength, heat resistance, fatigue resistance, and dimensional stability, its practical application has been delayed because it has difficulty adhering to rubber.
Polyethylene terephthalate (typified by polyethylene terephthalate) has improved its adhesion to rubber through the development of adhesive treatment methods using adhesives such as epoxy resins, isocyanate resins, ethylene urea resins, and chlorophenol resins, and today it is used in automobile tires. It has come to be widely used as a reinforcing material for rubber products such as hoses, belts, etc. However, conventionally known adhesive-treated polyester fibers have the disadvantage that their adhesive strength with rubber compounds decreases significantly when they are exposed to high temperatures for long periods of time in rubber compounds. Conditions and uses are limited.

It is said that the cause of this decrease in adhesive strength in rubber compounds is the deterioration of polyester fibers due to the action of amines and moisture in the rubber compound. proposals have been made.

For example, rubber compounds contain chlortriazine compounds (French Patent No. 2066198), isatoic anhydride (Japanese Patent Publication No. 36276/1982), and quicklime (Japanese Patent Publication No. 47/1989).
29471), etc., to prevent the utilization of amines and water in the rubber, and methods using polyester fibers that are less susceptible to deterioration by reducing the amount of carboxyl terminal groups (
Japanese Patent Publication No. 44-27911, Japanese Patent Publication No. 51-7039
Publication No. 4) etc. have been proposed. However, the method of adding these agents to the rubber compound causes undesirable drawbacks such as blooming and deterioration of the physical properties of the vulcanized comb, and the method of using polyester fibers with a low amount of carboxyl end groups already has polar groups and Since polyester fibers with fewer functional groups are made more non-polarized and have lower functional groups, they have the disadvantage that adhesion to rubber becomes more difficult, and it must be said that all of these proposals have little practical use. I don't get it. Furthermore, JP-A-51-70394 proposes a method in which polyester fibers having a carboxyl terminal group content of 10ep/1σf or less are subjected to epoxy compound treatment, polyisocyanate compound treatment, and resorcinol-formalin-rubber latex treatment. Since the polyisocyanate treatment is performed in an organic solvent system and is a three-stage dipping treatment, it is not important. The present inventors have already reported in Japanese Patent Publication No. 47-49768 (Japanese Patent No. 69276) that polyester fibers are treated with epoxy in the form of yarn before or after stretching, and then blocked in the subsequent process. We propose that polyester fibers for rubber reinforcement with excellent adhesive strength and adhesive fatigue resistance during high-temperature vulcanization can be obtained by treating with a resorcinol-formalin-rubber latex mixture containing an isocyanate or/and ethylene urea compound. However, as a result of further investigation, it was discovered that by using a specific blocked isocyanate, polyester fibers with improved adhesive strength when exposed to high temperatures for long periods in rubber can be obtained. This led to the invention. That is, the present invention provides a polyester that does not require the use of polyester fibers having a particularly low amount of carboxyl terminal groups, and that has significantly improved adhesion strength in rubber even when applied to commonly used rubber compounds. A method for producing fiber materials, commonly used as polyester fibers for rubber reinforcement. A yarn obtained by treating polyethylene terephthalate fiber used in a spinning or drawing process with a treatment liquid containing an epoxy compound having two or more epoxy groups, and then heat-treating it at 150 to 26 CfC, which is then twisted into yarn. The cord, or the fabric woven from the same, is treated with an aqueous dispersion of blocked isocyanate, which is obtained by blocking a polyisocyanate containing at least a portion of molecules having three or more isocyanate groups in one molecule with a lactam or oxime. By treating with a mixed treatment solution of resorcinol-formalin-rubber latex mixture (hereinafter abbreviated as ZRFL liquid), rubber reinforcement has significantly improved adhesive strength reduction when exposed to high temperatures for a long time in rubber. This is a method of obtaining polyester fiber material for use in polyester fibers.

The present invention will be explained in more detail below.

The polyester fiber of the present invention is a fiber obtained by melt-spinning polyethylene terephthalate or a high molecular weight linear polyester mainly composed of ethylene terephthalate units, and has an intrinsic viscosity (in a mixed solvent of 3:2 of phenol, nitrate, and chlorethane). , measured at 30C) is usually 0.
65 or more, and the amount of carboxyl terminal group is 35 eq/l
σy or less, usually 15 to 30 eq/lσ'.

The melt-spun polyester fibers are usually drawn,
After being twisted, woven, and treated with adhesives, it is used, for example, as a reinforcing material for rubber products such as automobile tires. The first feature of the present invention is that the melt-spun polyester fibers are treated with a treatment liquid containing a polyester-poxy compound during the spinning or drawing process, and then heat-treated at 150 to 260°C.

Treatment with a treatment liquid containing the epoxy compound is essential to be carried out during the spinning or drawing process, and it is not necessary to treat yarns after drawing, cords after twisting, or textiles after weaving. The purpose of the invention is not achieved.The reason is not clear, but it is believed that the epoxy compound is more strongly bonded to the polyester fibers in the unstretched state, where the degree of orientation of the polyester molecular chains is low, than in the highly oriented state after stretching. Furthermore, even if the blocked isocyanate RFL adhesive treatment of the present invention is applied to ordinary polyester fibers that are not treated with a treatment solution containing an epoxy compound in the spinning or drawing process, the object of the present invention will not be achieved at all. In order to treat with a treatment liquid containing an epoxy compound in the stretching process, for example, the epoxy compound is emulsified and dispersed in a spinning oil.
A method of applying this to a polyester yarn spun from a spinneret using an oiling roller as in the conventional method, or, for example, a method of applying this to an undrawn yarn treated with an oil agent by a conventional method using an ordinary oil agent that does not contain an epoxy compound. At the introduction of the stretching process,
There are methods such as applying a treatment liquid containing an epoxy compound by a dipping method or a roller method and then stretching the film. The processing liquid containing such an epoxy compound may contain compounds such as a curing agent, a stabilizer, an adhesion aid, etc.
Compounds such as thiourea compounds, mercaptobenzimidazole compounds, or polyester fibers proposed in Japanese Patent No. 4345 (Japanese Patent No. 748510) and Japanese Patent Publication No. 41451 (Japanese Patent No. 731981) may be added. Heat treatment at 150 to 260°C after treatment with a treatment liquid containing an epoxy compound in the spinning or stretching process
After the stretching process, the stretching may be carried out using, for example, a slit heater, an open or heated roller, but the stretching is generally carried out on a stretching pin, hot plate, roller, etc. heated to 80 to 260°C. The process can also serve as the heat treatment.

The epoxy compound used in the present invention has two or more epoxy groups in its molecule, and preferred examples include glycerin, propylene glycol, ethylene glycol, hexanetriol, sorbitol, trimethylolpropane, - methylpentanetriol,
Reaction products of aliphatic polyhydric alcohols such as polyethylene glycol and polypropylene glycol with halohydrins such as epic rehydrin, resorcinol, catechol, hydroquinone, 1,3,5-trihydroxybenzene, bis(4-hydroxyphenyl)methane , screw (4
-hydroxyphenyl)dimethylmethane, reaction products of aromatic polyhydric alcohols such as 4,4-pihydroxyphenyl and halohydrins such as epichlorohydrin, diglycidyl ether, vinylcyclohexene diepoxide, 3,4-epoxy 6- Examples include epoxy compounds obtained by oxidizing unsaturated bonds with peracetic acid, such as methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate; Particularly preferred is triepoxide.

The amount of the epoxy compound attached to the polyester fiber is 0.1 to 2. % weight is preferred. The polyester drawn yarn treated with a treatment solution containing an epoxy compound and heat-treated at 150 to 260°C, or a cord made by twisting the same in a conventional manner, or a fabric woven from the cord is then used in the present invention. The second component of the adhesive treatment is the aqueous dispersion of blocked isocyanate in which a polyisocyanate containing at least a portion of molecules having three or more isocyanate groups in one molecule is blocked with latam or oxime. and RFL. The adhesive treatment here refers to applying an adhesive treatment liquid to the fiber material by a conventional method such as spraying, dipping, or coating, and then subjecting it to heat treatment by a conventional method such as passing it through hot air. is 1~ at 120~260℃
It is preferable to do it once.

The polyisocyanate used here at least partially contains molecules having three or more isocyanate groups in one molecule means (4) a single polyfunctional isocyanate compound of triisocyanate or more, or (B) a polyfunctional isocyanate compound of triisocyanate or more. A mixture of a functional isocyanate compound and a di- or monoisocyanate, examples of (4) include triphenylmethane-4,4'',4''-triisocyanate, butane-1,2,2-triisocyanate or Examples of triisocyanates include trimethylolpropane tolylene diisocyanate teradduct (DesmOdurL) and 2,4,4-diphenyl ether triisocyanate. , 1, 2, 3, 4, etc. Polymethylene polyphenylisocyanate (commonly known as cylindrical) is used.Lactams and oximes used to block the polyisocyanate include proviolactam, butyrolactam, Lacta such as prolactam and valerolactam,
and oximes such as acetoxime, methyl ethyl ketone oxime, cyclohexanone oxime, and benzophenone oxime. The blocked isocyanate of the present invention is one of these lactams or oximes.
It is produced by reacting a species or two or more species with one or more of the above polyisocyanates by a known method. The RFL liquid used in the present invention is an initial condensate obtained by reacting resorcin and formalin under an acid or alkali catalyst, styrene-butadiene latex, carboxyl group-containing styrene-butadiene latex, styrene-butadiene-vinylpyridine. It is an aqueous liquid mixed with one or more types of latices such as latex, acrylonitrile-butadiene latex, polychloroprene latex, polybutadiene latex, and natural rubber latex, and the molar ratio of resorcinol and formalin is 1:0.5.
The solid content ratio of the resorcinol-formalin initial condensate to the latex is preferably in the range of 5:95 to 5(7)60 by weight.

In the adhesive treatment of the present invention, the isocyanate component of the blocked isocyanate is particularly important, and it is essential that the polyisocyanate at least partially contain molecules having three or more isocyanate groups in one molecule.

Diisocyanates such as diphenylmethane diisocyanate, tolylene diisocyanate, or hexamethylene diisocyanate, which are isocyanate compounds having only two or less isocyanate groups in one molecule, or monoisocyanates such as phenyl isocyanate do not meet the objectives of the present invention. Unachievable.

Although the reason for this is not clear, it seems that the formation of a three-dimensional network structure by trifunctional or higher functional polyisocyanate molecules is effective in improving the heat resistance of adhesive strength. In addition to the lactams and oximes of the present invention, phenols, aliphatic alcohols, and amines are generally known as blocking agents for blocked isocyanates. This is undesirable because the dissociation temperature is unsuitably high and the polyester is damaged after dissociation. In the adhesive treatment of the present invention, the mixing ratio of blocked isocyanate and RFL is also important.
It is preferably in the range of 95 to 8 (7) 20.
Protected isocyanate is 5 to 95 to RFL
If the amount is less than 8 (7), the effect is insufficient, and 8 (7)
When the number is more than 20, the affinity with the rubber compound is low and sufficient adhesive strength cannot be obtained, so it is not preferable. stomach.

In order to clarify this situation, E-caprolactam block body of polymethylene polyphenylisocyanate and RF
Figure 1 shows the adhesive strength when the mixing ratio with L was changed. The amount of the mixed adhesive of blocked isocyanate and RFL applied to the polyester fiber material is preferably 3 to 15% by dry weight.

Although the polyester fiber material of the present invention thus obtained has a simple one-step adhesive treatment process, it exhibits less adhesive strength than conventional polyester fiber materials when exposed to high temperatures for a long time in rubber. This is an epoch-making product that can be applied to reinforcing materials for rubber products such as large tires that require long-term vulcanization at high temperatures and belts that are used under harsh conditions.

The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto.

In addition, parts in the examples mean parts by weight. Example 1 Kohon 812 (manufactured by Schiel Chemical Co., Ltd., glycerin, epichlorohydrin, and A spinning oil treatment solution containing an epoxy compound was prepared by dispersing the reaction product 3).

On the other hand, a polyethylene terephthalate chip with an intrinsic viscosity of 1.03 (measured at 30C in a mixed solvent of phenolnitetrachloroethane and 3:2) was spun at a spinning temperature of 305°C with a pore size of 0.
4WfL, 250V/Min from a spinneret with 192 holes
The undrawn yarn thus obtained is cooled to a temperature below the secondary transition point of the polymer, and then the above-mentioned epoxy compound-containing spinning oil treatment liquid is applied using an oiling roller in the usual manner. , and was wound at a speed of 380 Tn/Min.

The solid content of the epoxy compound-containing spinning oil treatment solution was 0.8% based on the weight of the yarn. Next, the undrawn yarn obtained by the epoxy treatment was drawn in two stages to a total of 6 times using 9 heated drawing pins and a 200°C slit heater, and then fixed-length heat setting on a 250°C slit heater. I went. The residence time in the slit heater was set to 258 in both cases of stretching and heat setting.

The polyethylene terephthalate drawn yarn of 1000 d/192 filaments thus obtained had a carboxyl terminal group content of 18 eq/1σy and an intrinsic viscosity of 0.85 (measured by the above method). Three of these yarns were twisted together to obtain one cord (number of twists x 41.51'/10 cm). A blocked isocyanate RFL mixed adhesive treatment solution prepared from the thus obtained cord as follows:
That is, an aqueous dispersion of polymethylene polyphenylisocyanate (Millionate ■0 manufactured by Nippon Polyurethane Industries, Ltd.) containing 0.6 parts of methyl cellulose, 0.3 parts of sodium rekylsulfonate, and polyethylene in the water part. Add 0.1 part of glycol monolaurylate and E-caprolactam block polymethylene polyphenyl isocyanate 2CS and mix with a ball mill to 24:1.
5.7 parts of resorcin, 6.3 parts of a 37% formalin aqueous solution, and 3 parts of a 10% caustic soda aqueous solution were added to 185.7 parts of water, and the mixture was heated at 30'C for 6 hours. After completing the time course, 175.7 parts of Nitzpol 2518FS [Nippon Zeon Co., Ltd. butadiene-styrene-vinylpyridine latex (solid content 41%)] and 23 parts of water were added.
．． It was immersed for 5 seconds in a treatment solution mixed with RFL liquid 60% obtained by adding 6 parts, and then heated to 908 °C in heated air at 220 °C.
Heat treated for a while.

The adhesive treated cord thus obtained had an adhesive adhesion rate of 5.5% based on the weight of the polyester cord, and was vulcanized and bonded with the following rubber compound to measure the H-adhesive strength. The results are shown in Table 1. That's right. Rubber compound composition used in the adhesion test Smoked sheet No. 37OJ part SBR-171242 / Broken zinc rate 5. sulfur
2.5 parts stearic acid
2.5 parts N-cyclohexy-2-benzothiazole sulfenamide (accelerator)
1. Probain Tar 5.0m
N-phenyl-N'-isopropyl-P-phenylenediamine (anti-aging agent) 1.5 parts FEF carbon black 5. For comparison, Table 1 shows samples treated under the same conditions as in Example 1, except that an aqueous dispersion of E-caprolactam protease of polymethylene polyphenylsocyanate was not added to the adhesive treatment solution of Example 1. The case is Comparative Example 1, and the case is treated under the same conditions as Example 1 except that RFL liquid is not added to the adhesive treatment liquid of Example 1. Comparative Example 2 is the case where Kohon 812 is not added to the spinning oil treatment liquid. Comparative Example 3 is the case treated under the same conditions as Example 1,
The same as Example 1 except that instead of adding Kohon 812 to the spinning oil treatment solution, the cords were twisted into cords and then treated with a 5% aqueous solution of Kohon 812, and then heat-treated for 9 hours in heated air at 220'C. Comparative Example 4 is a case treated under the same conditions, and Comparative Example is a case treated under the same conditions as Example 1 except that E-caprolactam blocked form of diphenylmethane diisocyanate is used instead of the blocked isocyanate of Example 1. 5. Comparative Example 6, the case where the treatment was carried out under the same conditions as in Example 1 except that ε-caprolactam blocked form of tolylene diisocyanate was used instead of the blocked isocyanate in Example 1. Comparative Example 6, blocked isocyanate in Example 1 Comparative Example 7 is a case in which the treatment was carried out under the same conditions as in Example 1, except that ε-caprolactam block of phenyl isocyanate was used instead of ε-caprolactam. In Comparative Example 8, the treatment was carried out under the same conditions as in Example 1 except that a phenol block of diphenylmethane diisocyanate was used.
shown respectively.

As is clear from Table 1, the cord treated according to the invention (Example 1) gave better adhesion performance than any of Comparative Examples 1 to 8, especially at 170°C. Extremely high adhesive strength when cured at high temperatures and for long periods of time. Example 2 All the same procedures as Example 1 except that a methyl ethyl ketone oxime block of triphenylmethane-4,4'',4''-triisocyanate was used in place of the ε-caprolactam block of polymethylene polyphenylisocyanate in Example 1. When the cord obtained by processing under the same conditions as 14C) Cl4 powder or 170C16 powder was vulcanized and bonded together with the rubber compound of Example 1, the H-adhesion strength was 16.5k9/1, respectively.
C7l and 10.8k9/CFl, and showed high initial adhesive strength and high heat-resistant adhesive strength.

Example 3 1 (1) of Kohon 812 was added to an aqueous emulsion obtained by dissolving 2 (4) parts of a spinning oil for polyester fibers containing a fatty acid ester and a nonionic activator in 9 (1) parts of water. After dissolving and dispersing the part), 15 parts of mercaptobenzimidazole was added to 9 (1) parts of water to dissolve Nitsusan Larapizole B-3.
An epoxy compound- and mercaptobenzimidazole-containing spinning oil treatment solution was prepared by mixing a dispersion prepared using 1 part of an anionic activator (manufactured by Nissan Chemical Co., Ltd.).

Polyester fibers were spun and drawn under the same conditions as in Example 1, except that this treatment liquid was used in place of the spinning oil treatment liquid in Example 1. 100 obtained here (1X1/1
The carboxyl terminal group content of the 92-filament polyethylene terephthalate drawn yarn was 18 eq/1 Cf'y, and the solid content of the spinning oil treatment solution containing an epoxy compound and mercaptobenzimidazole was 1.0% based on the yarn weight. .

Three of these drawn yarns were twisted together to obtain one cord (number of twists: 38×41.5T/10crf1). The code obtained in this way was used as an E-caprolactam block product of the same polymethylene polyphenylisocyanate as in Example 1.
After being immersed in the mixed adhesive treatment solution for 5 seconds, it was heat treated in heated air at 220° C. for 9 cycles for 2 hours to obtain an adhesive treated cord with an adhesive adhesion rate of 5.6% based on the weight of the polyester cord. When the adhesive treated cord thus obtained was vulcanized and bonded with the rubber compound of Example 1 at 140° C. for 4 minutes or at 170° C. for 6 times, the H-adhesion strength was as shown in Table 2.

For comparison, Table 2 shows cases in which the treatment was carried out under the same conditions as in Example 3, except that an ethyl alcohol block of polymethylene polyphenylisocyanate (Millionate IVR) was used instead of the blocked isocyanate in Example 3. Comparative Example 9 and Comparative Example 10 show cases in which they were treated under the same conditions as in Example 3, except that a phenol block of polymethylene polyphenylisocyanate (Millionate MR) was used instead of the blocked isocyanate in Example 3. Ta.

As is clear from Table 2, the cord treated according to the invention (Example 3) has a much higher initial adhesion strength and a very good adhesive heat resistance than in Comparative Examples 9 and 10. showed that.

In the case of Comparative Example 9, it seems that the initial adhesion is not strong because the dissociation temperature of the blocking agent ethanol is unreasonably high, and in the case of Comparative Example 10, the blocking agent phenol deteriorates the polyester fiber after dissociation. Therefore, the adhesive strength and heat resistance are thought to be poor.

[Brief explanation of the drawing]

Figure 1 shows the ε of polymethylene polyphenylisocyanate.
1 is a graph showing the relationship between solid content mixing ratio and adhesive strength of a caprolactam block and a resorcinol-formalin-rubber latex mixture.

Claims (1)

[Claims] 1 A filament obtained by treating polyester fiber with a treatment liquid containing an epoxy compound having two or more epoxy groups in a spinning or drawing process and then heat-treating it at 150 to 260°C, a cord obtained by twisting the filament, or a cord made by twisting the filament. The woven fabric is mixed with an aqueous dispersion of a blocked isocyanate obtained by blocking a polyisocyanate containing at least a portion of molecules having three or more isocyanate groups in each molecule with a lactam or an oxime, and a resorcinol-formalin-rubber latex mixture. A method for producing a polyester fiber material with improved adhesion to rubber, the method comprising treating it with a mixed treatment liquid.