JPH073566A - Polyester multifilament yarn for rubber reinforcement - Google Patents

Abstract

PURPOSE:To provide the multifilament yarns of high mechanical strength and high modulus, causing no tearing or splitting in the fiber axial direction, also improved in adhesion to rubber, thus suitable for rubber reinforcement. CONSTITUTION:The objective multifilament yarns have the following characteristics: (1) consisting of a polyester with ethylene terephthalate units accounting for >=75mol% of the total recurring units, (2) single fiber fineness: 1-500 denier, (3) yarn tenacity: >=70g/de, (4) being in the form of flat-shaped yarns imparted with 4-20wt.%, based on the yarn weight, of a pre-treating agent plus adhesive in a twistless or twisted (at a twist multiplier of <=1200) state, and (5) section flatness coefficient alpha: >=1.5.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to polyester multifilament yarns suitable for rubber reinforcement. More specifically, it relates to a polyester multifilament yarn having excellent mechanical properties and improved adhesion to rubber.

[0002]

2. Description of the Related Art Polyester fiber typified by polyethylene terephthalate is widely used as a rubber reinforcing material for tires, transmission belts, conveyor belts, etc., due to its characteristics such as high strength and high elasticity. Conventionally, a multifilament is often used as a rubber reinforcing material, but in the case of a multifilament, it is necessary to apply a twist of about 1500 to 2400 as a twisting coefficient in order to improve the focusing property and the fatigue resistance. Since the strength and elastic modulus decrease with twisting, there is a problem that the characteristics possessed by these multifilaments cannot be fully exhibited.

In order to solve such a problem, Japanese Patent Laid-Open No. 1-1
In Japanese Patent No. 48828, by using a non-twisted polyamide monofilament as a carcass cord of a radial tire, high strength and high elasticity can be achieved, the amount of cord and rubber used can be reduced by 20 to 40%, and at the time of running the tire. Although it is disclosed that the heat generation can be reduced, the polyamide fiber has a fatal defect that a flat spot occurs.

On the other hand, Japanese Patent Application Laid-Open No. 51-15021 discloses that a polyester monofilament which does not cause a flat spot is used as a rubber reinforcing material.

However, since polyester has a weaker molecular bonding force in the direction perpendicular to the fiber axis than polyamide,
In the case of a monofilament that has a large single fiber fineness and is further oriented and crystallized, there is a problem that the monofilament is easily torn or broken in the fiber axis direction.

Polyester has less functional groups with high hydrogen bonding ability in the molecular chain, as compared with polyamide,
Further, the monofilament also has a problem that the polyester monofilament has insufficient adhesiveness to rubber because the contact area of the monofilament with the multifilament is small.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and its purpose is to:
To provide a polyester multi-filament yarn suitable for rubber reinforcement, which has high strength and high elasticity, has no problem of filament tearing or cracking in the fiber axis direction, and has improved adhesiveness with rubber. is there.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, made the polyester multifilament yarn flat, and made the polyester multifilament yarn behave like a monofilament by holding the shape with an adhesive. ,
It was clarified that a polyester multi-filament cord having high strength and high elasticity, no filament tearing or cracking, and excellent adhesiveness with rubber can be obtained.

Thus, according to the present invention, a polyester multifilament comprising a polyester in which 75 mol% or more of the repeating unit is an ethylene terephthalate unit and having a single fiber fineness of 1 to 500 denier and a yarn strength of 7.0 g / denier or more. In the yarn, the yarn is a flat yarn in which a pretreatment agent and an adhesive are applied in an untwisted state or a twisted state with a twist coefficient of 1200 or less to 4 to 20% by weight based on the weight of the yarn. Provided is a polyester multifilament yarn for rubber reinforcement, which has a cross-sectional flattening coefficient α of 1.5 or more.

The present invention will be described in detail below. The polyester referred to in the present invention is a polyester whose main repeating unit is ethylene terephthalate. Further, it may be a polyester obtained by copolymerizing a third component as long as the characteristics of the polyester are not impaired.

Examples of the copolymerization component include dicarboxylic acids such as adipic acid, isophthalic acid, naphthalene dicarboxylic acid and diphenyl dicarboxylic acid, and diol components such as propylene glycol, butylene glycol and diethylene glycol. The proportion is 25 mol% or less, preferably 10 mol% or less, based on the terephthalic acid component. In addition, the polyester, a stabilizer, a plasticizer, within a range not impairing the object of the present invention,
Additives such as matting agents, lubricants, and flame retardants can also be included.

The polyester multifilament yarn of the present invention comprises a multifilament having a single fiber fineness of 1 to 500 denier, which is obtained by melt spinning the above polyester by a conventional method.

The monofilament fineness of the multifilament is 50.
When it exceeds 0 denier, the single fiber is likely to be split or broken in the fiber axis direction, while when the single fiber fineness is less than 1 denier, fluff occurs when the adhesive is applied. Not preferable. A particularly preferred single fiber fineness range is 20 to 200 denier.

Further, the polyester multifilament yarn of the present invention must be untwisted or twisted with a twist coefficient of 1200 or less. Twisting coefficient is 1200
If it exceeds the above range, not only a high-strength and high-elasticity cord cannot be obtained, but also it becomes difficult to make the cross-sectional flatness coefficient of the cord, which will be described later, 1.5 or more. There is a problem of low.

Next, the twisted polyester multifilament is provided with a pretreatment agent and an adhesive agent in an amount of 4 to 20% based on the weight of the fiber. As the adhesive, a mixture of an initial polycondensate of resorcinformaldehyde and a dispersion of styrene, butadiene, and vinylpyridine copolymerized latex, which is usually used as an adhesive for polyester fibers (hereinafter referred to as RFL mixture), can be used. Practical adhesion is obtained.

However, polyester has less polar groups or functional groups in the molecule than polyamide and the like, and therefore, a usual RFL mixed liquid cannot provide sufficient adhesion with rubber. Therefore, in order to improve the adhesiveness of the polyester, it is necessary to pretreat the surface of the polyester fiber with a highly reactive treating agent before applying the RFL mixed solution.

Examples of the pretreatment agent include an isocyanate compound, a blocked isocyanate compound, an isocyanurate compound, an epoxy compound, a polyazirinyl compound and a polyamide resin, and the epoxy compound is preferable from the viewpoint of handleability.

As a method of applying the above-mentioned adhesive or pretreatment agent, a method of immersing in an aqueous dispersion or a solution of a solvent, followed by drying and curing is generally used. Any method such as a so-called plutrusion method in which the polyester multifilament cord is melted to coat the polyester multifilament cord may be used. When melting and adhering the resin, it is necessary to select a resin having a low melting point or a low molding temperature so as not to deteriorate the characteristics of the polyester fiber.

The amount of the pretreatment agent and the adhesive to be attached must be 4 to 20% based on the weight of the fiber. Adhesion amount is 4%
When it is less than the above, sufficient adhesion with rubber cannot be obtained, and when the number of twists of the multifilament is small, filaments are poorly bundled and cannot be molded into a desired flat shape.

On the other hand, when the adhesion amount exceeds 20%, the adhesiveness between the multifilaments becomes large and the yarn becomes difficult to handle.

Rubber may be further added to the multifilament. The addition of rubber makes it easier to maintain the flat shape. The rubber used is natural rubber,
Butadiene rubber, isoprene rubber, chloroprene rubber,
Examples thereof include styrene-butadiene rubber, acrylonitrile-butadiene rubber, and the like, and the amount of adhesion is preferably 30% by weight or less.

The polyester multifilament yarn to which the adhesive is applied has a sectional flatness coefficient α in its cross section.
Must be 1.5 or higher. The section flattening coefficient α is the ratio of the major axis a to the minor axis b of the section, and is represented by α = a / b. When α is less than 1.5, sufficient adhesion with rubber cannot be obtained, but when it is too large, the handleability of the yarn deteriorates, so it is preferably 10 or less.

As a method for forming a flat shape, a method in which an adhesive is applied and then wound while applying pressure with a nip roller, or a method in which an adhesive-added cord is formed and formed through a flat die is used. Any method can be used.

The polyester multifilament yarn should have a strength of 7 g / d or more. If the strength is less than 7 g / d, the effect of rubber reinforcement is not sufficient and the amount of yarn used increases, which is not preferable.

[0025]

The polyester multifilament yarn of the present invention has a smaller number of twists than the conventional polyester multifilament, so that it is possible to increase the strength and elasticity.

Generally, when the number of twists of a polyester multifilament yarn is reduced, the elongation properties such as strength and elastic modulus are improved, but if the number of twists is simply reduced, the bundles between filaments are deteriorated, which causes fluffing. Not only does it reduce fatigue resistance and adhesion to rubber.

That is, the binding force between filaments weakens as the number of twists decreases, so that, for example, in the step of applying an adhesive, monofilaments wind around a roller, fluffing occurs, and stress distribution due to twisting hardly occurs. Therefore, fatigue resistance is reduced. Further, as the number of twists decreases, the unevenness of the fiber surface decreases, so that the adhesiveness also decreases.

In the present invention, when the adhesive is applied, the cross section is made flat so as to prevent the generation of the fluff and the deterioration of the fatigue resistance and to increase the contact area between the cord and the rubber to improve the adhesiveness with the rubber. Improve.

The present invention will be described in more detail below with reference to examples. In addition, each physical property in an Example is measured by the following method.

(1) Physical properties of cord The physical properties of the multifilament cord were measured according to JIS L 1013.

(2) Twist coefficient K The twist coefficient K is expressed by the following equation, where T is the number of twists per 10 cm of cord length and D is the total fineness of the fibers constituting the cord. K = T × D ^1/2

(3) Sectional flatness coefficient α A code was cut at 30 locations at intervals of 1 m and a section photograph was taken. The major axes a and b of the section were read from the photograph, and the average value at 30 locations was calculated by the following formula. α = a / b

(4) Bonding strength The cord after the bonding treatment is thickened with natural rubber as a main component.
Align them in parallel on a sheet of unvulcanized rubber at a density of 7 / inch, sandwich them with the same unvulcanized rubber sheet, and vulcanize on a heat plate plate at 150 ° C for 30 minutes. This sheet 20
After leaving it for 48 hours at 65 ° C and 65% RH, the five cords excluding both ends were simultaneously peeled from the rubber, and the force required for peeling at this time was defined as the adhesive strength.

[0034]

Examples 1 to 5 and Comparative Example 1 Polyethylene terephthalate having an intrinsic viscosity of 0.95 was melt-spun and drawn by a conventional method to have a single fiber fineness shown in Table 1 and a yarn denier of 1500 denier. Got

Next, using a tire cord twisting machine, the polyester multifilament is subjected to 100 T / M undertwisting, and two of the undertwisted cords are aligned to obtain 100 T / M overtwisting (twisting factor 548). I got a raw code.

As a pretreatment agent, Denacol EX-
611 (sorbitol polyglycidyl ether manufactured by Nagase Kasei Co., Ltd.) 9.0 g as a surfactant Neocor SW
-30 (Dioctyl sulfosuccinate sodium salt 30% aqueous solution manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) (13.5 g) was added and uniformly dispersed, and then a dispersion liquid in which water was dispersed in a phenol block of 4,4'diphenylmethane diisocyanate. 755g, and Nipol 2518GL (Nippon Seon
212.5 g of 40% water emulsion of vinylpyridine / styrene / butadiene polymer manufactured by Co., Ltd.) was added to prepare a homogeneous mixture.

On the other hand, 10% caustic soda 4.4 g, 28%
After dissolving 12.8 g of an aqueous ammonia solution in 134.6 g of water, 26.7 g of a resorcin-formalin initial condensation product (40% acetone solution) condensed in advance with an acidic catalyst was added to this aqueous solution and stirred sufficiently. It was designated as the first liquid.
Next, to 314.6 g of water, Nipol 2518GL37
After adding 5.8 g and thoroughly stirring, the first liquid was gradually mixed with stirring, and 37% formalin solution 11.1 was further added.
g was added to obtain an aqueous adhesive. The adhesive is 4 at 20 ° C
It was used after aging for 8 hours.

Next, the raw cord is dipped and passed through the pretreatment liquid using a cord dipping machine to pass 13
After drying at 0 ° C for 2 minutes, heat treatment was performed at 235 ° C for 1 minute. Subsequently, the adhesive solution was dipped and passed therethrough, dried at 130 ° C. for 2 minutes, and then heat-treated at 235 ° C. for 1 minute.

The dip cord was pressed by a nip roller at the time of RFL treatment and molded so that the cross section had a flat shape. The amounts of the pretreatment agent, the adhesive agent, and the rubber attached were calculated from the weights of the raw cord and the dip cord. The properties of the obtained polyester multifilament yarn are shown in Table 1.

[0040]

[Table 1]

[0041]

Examples 6 to 7 and Comparative Examples 2 to 3 In Example 1, the yarn has a single fiber fineness shown in Table 2 and a yarn denier of 3000.
After obtaining the denier polyester multifilament,
It carried out like Example 1 except having used it in the untwisted state.
The properties of the obtained polyester multifilament yarn are shown in Table 2.

[0042]

[Table 2]

[0043]

Examples 8 to 10 and Comparative Example 4 In Example 2,
It carried out like Example 2 except having changed the twist coefficient as shown in Table 3. The properties of the obtained polyester multifilament yarn are shown in Table 3.

[0044]

[Table 3]

[0045]

Examples 11 to 13 and Comparative Example 5 In Example 2, the twist coefficient was changed as shown in Table 4, and the obtained polyester multifilament yarn was dipped and passed through a solution of natural rubber in trichlorethylene, and the mixture was passed at 130 ° C. for 2 minutes. The same procedure as in Example 2 was carried out except that the product was dried and rubber was added.
The properties of the resulting polyester multifilament yarn are shown in Table 4.

[0046]

[Table 4]

[0047]

Examples 14 to 16 and Comparative Examples 6 to 7 The procedure of Example 2 was repeated, except that the amounts of pretreatment agent and adhesive were changed as shown in Table 5. The characteristics of the obtained polyester multifilament yarn are shown in Table 5.

[0048]

[Table 5]

[0049]

Examples 17 to 18 and Comparative Examples 8 to 9 The same procedure as in Example 2 was carried out except that the flatness coefficient in section was changed as shown in Table 6. The properties of the obtained polyester multifilament yarn are shown in Table 6.

[0050]

[Table 6]

[0051]

EFFECTS OF THE INVENTION The rubber-reinforcing polyester multifilament yarn of the present invention has high strength, high elasticity, and good adhesiveness with rubber, and tears in the fiber axial direction even when used by being embedded in rubber. It does not crack or break. Also,
By using the polyester multi-filament yarn for rubber reinforcement of the present invention, it is possible to reduce the amount of cords and rubber used and also reduce heat generation during tire running, so as a reinforcing material for tires, transmission belts, conveyor belts, etc. It can be preferably used.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshinasa Kuroda 3-4-1, Mihara, Ibaraki City, Osaka Prefecture Teijin Limited Osaka Research Center

Claims (1)

[Claims] 1. A repeating unit consisting of polyester in which 75 mol% or more is an ethylene terephthalate unit, has a single fiber fineness of 1 to 500 denier and a yarn strength of 7.
In a polyester multifilament yarn of 0 g / denier or more, the yarn is a non-twisted or twisted yarn having a twist coefficient of 1200 or less, and a pretreatment agent and an adhesive are applied in an amount of 4 to 20% by weight based on the weight of the yarn. A yarn having a cross-sectional flattening coefficient α of 1.
A polyester multifilament yarn for rubber reinforcement, characterized in that the number is 5 or more.