KR20060077203A - Adhesives composition of dipped polyester for rubber reinforcement - Google Patents

Abstract

The present invention relates to an adhesive composition of a deep reinforced polyester fiber for rubber reinforcement that exhibits excellent heat resistance and coating property with rubber when the polyester (PET) fiber is exposed at a high temperature.

Polyester, Epoxy, RFL, Dipping, Heat Resistance, Coating

Description

Adhesive composition of deep polyester fiber for rubber reinforcement {Adhesives composition of dipped polyester for rubber reinforcement}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to adhesive compositions of dipped polyester fibers for rubber reinforcement, and more particularly to adhesive compositions for improving heat resistance to rubber when the reinforcing fibers are exposed to high temperatures.

PET fibers represented by polyethylene terephthalate are used as rubber reinforcing fibers such as tires, hoses and belts because they exhibit excellent physical properties such as high strength and high modulus. However, since the surface of the PET fiber is relatively inert, the adhesive force with the rubber is insufficient, and thus the physical properties of the PET fiber cannot be fully exhibited.

For this reason, Japanese Patent Application Laid-Open No. 54-73994 discloses a chemical treatment method that treats the surface of PET fibers with various compounds, such as aliphatic epoxy compounds and blocked isocyanate compounds, which are treated with highly reactive chemicals to impart adhesion. The so-called two-bath treatment method which processes with normal resorcin formatin latex (RFL) is proposed. However, the tire cords treated in this way have sufficient initial adhesive strength but hardly obtain sufficient adhesive strength at high temperatures. Therefore, in order to develop sufficient heat resistance, the concentration of the dip solution should be high and the dip pick up (hereinafter referred to as "DPU") should be increased. However, in this case, the frequency of inspection (Gum-Up) is high, resulting in a shortened cleaning cycle, resulting in a decrease in productivity. As a one-bath treatment method, a method presented in Japanese Patent Application No. 46-11251 is proposed. The method comprises a reaction product of a halogenated phenol (typically PEXUL) with a reaction product of resorcinol / formaldehyde and rubber latex (hereinafter referred to as "RFL"). Was treated by mixing. However, such a treatment method has a disadvantage that the DPU should be increased to express sufficient adhesive strength, and the problem of environmental pollution by phenolic compounds may occur. Another method for treating PET fibers is shown in US Pat. No. 3,234,067. In this method, it is treated with one bath made of a mixture of epoxy / isocyanate, followed by conventional RFL. However, the US patent method uses an excess of alkali compounds to increase the stability of the RFL. This alkali compound causes hydrolysis by alkali, which acts as a catalyst for amine decomposition by amine compounds used as a vulcanization accelerator, which is part of the rubber composition, leading to a decrease in the inherent physical properties and a decrease in adhesion. do. In addition, PET fibers treated by these methods are poor in heat resistance, and the amount of adhesion must be excessive to obtain sufficient adhesion. However, if the amount of adhesion is increased, the dip fluid penetrates excessively into the fiber, which increases the rigidity of the fiber, thereby reducing the fatigue resistance.

 SUMMARY OF THE INVENTION The present invention has been made in an effort to provide an adhesive composition of deep PET fibers having excellent adhesive strength retention at high temperatures. The present invention also provides an adhesive composition of deep reinforced PET fiber for rubber reinforcement, which shows excellent adhesion to rubber and excellent coverage even when exposed to rubber at high temperature while maintaining the original properties of PET fiber.

The present invention is described in detail as follows.

Generally, an epoxy compound has at least two epoxy groups in one molecule, and a halogenated compound such as epichlorohydrin and a polyhydric alcohol such as glycerol, ethylene glycerol, diethylene glycol, sorbitol, propylene glycol, polyethylene glycol, or denacol, or It is a substance formed by reaction with polyhydric phenol.

As the blocked isocyanate compound, a compound blocked with -caprolactam is used, and a representative example thereof is a product named IL-6 under the trade name. Representative blocking derivatives are ketoxime, -caprolactam, phenol, toluene, etc. Among them, it is advantageous to block with toluene to express adhesive force, but its use is limited due to environmental problems, and -capro in terms of versatility and stability Compounds blocked with lactams are the most widely used. These isocyanate compounds act as adhesives by dissociating the blocking derivatives by heat and polymerizing through crosslinking with the epoxy by heat.

On the other hand, the general latex (VP) latex is made of vinyl pyridine / styrene / butadiene rubber latex in a 15/70/15 weight ratio, and has good affinity with rubber, and contributes to improving initial adhesion and coating properties of rubber. do. Typical VP latexes include 2518FS, which is commercially available from Xeon, Japan, and VP 106, which is commercially available from Hyundai Petrochemical.

It is also preferable to add some isocyanate compounds to the secondary dip liquid to promote crosslinking, and it is also preferable to add resorcinformalin (RF) initial condensates. Typical RF initial condensates include compounds such as PEXUL or Denabond E, which are representative compounds obtained by dissolving halogenated phenols such as 2,6-bis (2,4-dihydroxy phenylmethyl) -4-chlorophenyl in 5N ammonia water. It is possible to use

Hereinafter, the present invention will be described in more detail.

The composition of the primary dip solution is as follows.

The epoxy used in the present invention is characterized by the use of a water-insoluble epoxy, and is also characterized by the sorbitol polyglycidyl ether type. In general, the water-soluble epoxy compound has a small number of epoxy rings, which leads to a decrease in adhesion. On the contrary, the water-insoluble epoxy has a high number of epoxy rings and at the same time, is advantageous for the development of adhesion due to the high viscosity characteristic of the aliphatic compound. Epoxy and blocked isocyanate compounds should be in the weight ratio of epoxy / isocyanate = 1 / 0.5-1 / 8. If it is out of this range, not only sufficient adhesive force is developed but also the rigidity is so high that fatigue resistance, which is one of the main required characteristics of the tire cord, is reduced, resulting in deterioration of tire durability. In addition, it is possible to select a suitable emulsifier to emulsify the epoxy and the dosage is in the range of 10 ~ 100wt% based on the weight of epoxy. If more than 100wt% has an adverse effect on the expression of adhesive force, less than 10wt% will result in the emulsification stability is insufficient because the emulsification power is not enough.

Latex can also be used with VP Latex, and can be mixed with SBR latex. However, when SBR latex alone is used, it is difficult to obtain satisfactory adhesion level. The dosage is 10-50 wt% based on the total weight ratio. If it is less than 10 wt%, the compatibility and affinity with the rubber is insufficient, the adhesive force is not sufficient, and if it exceeds 50 wt%, it causes a decrease in productivity due to the inspection phenomenon on the roller.

The adhesive amount is preferably 1 wt% to 5 wt% based on the weight of the fiber based on the solid content. If the adhesive adhesion amount exceeds 5wt%, the hardness of the adhesive liquid is increased, resulting in a decrease in the fatigue resistance of the cord. If the adhesive adhesion amount is less than 1wt%, the adhesive strength between the rubber and the fiber decreases and at the same time after high temperature vulcanization This results in a lack of sufficient adhesion.

The composition of the second dip liquid is as follows.

In the case of reacting resorcin with formalin, the molar ratio should be adjusted in the range of resorcin / formalin = 1/1 to 1/3. As the reaction catalyst, any of caustic soda and aqueous ammonia solution may be used. In addition, the compound and rubber latex having completed the RF reaction should be adjusted in the range of 1/1 to 1/15, more preferably 1/3 to 1/12 based on solids. When the amount of the rubber latex is below the above range, the cord becomes hard and the adhesive strength drops. On the contrary, if it is more than the above range, the adhesiveness of the treated cord is increased, the roller cleaning cycle is shortened, the productivity is lowered, and a problem of not being able to obtain a satisfactory adhesive force occurs.

The adhesive amount is preferably 1 wt% to 5 wt% based on the weight of the fiber based on the solid content. If the adhesive adhesion amount exceeds 5wt%, the hardness of the adhesive liquid is increased, resulting in a decrease in the fatigue resistance of the cord. If the adhesive adhesion amount is less than 1wt%, the adhesive strength between the rubber and the fiber decreases and at the same time after high temperature vulcanization This results in a lack of sufficient adhesion.

Deep fiber of the present invention can be produced in the following order. The untreated polyester fibers are transferred to a dipping process and the treatment liquid is imparted to the fibers. The treatment liquid applying method can be any of dipping, coating and spraying methods, and generally a dipping method is used. The tension of the fiber is appropriately 0.05 to 0.20 g / d, and after the treatment liquid is added, it goes through a drying step. The temperature at this time is 110-160 degreeC, and processing time is 20 to 150 second process. Subsequently, a dipped PET cord may be manufactured by heat treatment at 200 to 250 ° C. for 20 to 150 seconds.

The PET fiber produced as described above exhibits a high initial adhesive force and is useful as an excellent rubber reinforcement PET fiber because it exhibits excellent adhesive strength retention at high temperature and excellent coating property with rubber.

<Example 1>

The polyester cord 1500 denier / 2-ply for tire reinforcement was combusted at 390 TPM, and the upper and lower lead were twisted under the same conditions.

The obtained PET cord was passed through the adhesive liquid prepared by the following method to give an adhesive liquid. After the addition of the heat treatment solution, the mixture was dried at 150 ° C. for 120 seconds and then heat treated at 240 ° C. for 2 minutes to complete the adhesive treatment.

Primary immersion composition

                              Wet (g) Dry (g)

Insoluble Aliphatic Epoxy 3 3

    Emulsifier 1 1

Isocyanate 30 15

VP Latex 227.5 90

       Water 850-

       Revelation 1111.5 109

Conc. 10

Secondary immersion composition

                              Wet (g) Dry (g)

29,4 wt% resorcinol 45.6 13.4

Pure 255.5-

37% formalin 20 7.4

10wt% sodium hydroxide 3.8 0.3                     

After preparing the solution, the reaction was stirred at 25 ° C. for 5 hours, and then the following components were added.

VP Latex 300 120

Pure 129-

28% ammonia water 23.8 6.7

     Total 777.7 147.8

After the ingredient is added, the mixture is aged at 25 ° C. for 20 hours to maintain a solid concentration of 19.0 wt%.

H-test to measure the initial adhesion to the rubber of the deep cord prepared in this way and the heat-resistant adhesion at high temperature, CRA-S Test to check the rubber coverage at high temperature exposure ) Was performed. H-test ensures that both ends of the deep cord are embedded in a 9.5mm rubber block, and the gap between the rubber blocks at both ends is 9mm and the rubber is pulled on both sides to measure the maximum load at which the rubber-cord separation occurs. How to evaluate. CRA-S Test is a method to check the peel adhesion between the cord and the rubber and the rubber coating property. After the five cords are inserted and vulcanized side by side in the rubber sheet surface layer, the five cords are moved at a speed of 200 mm / min from the rubber sheet. Peel off. In this case, the force required for peeling is expressed in Kg / 5. Moreover, the coating | covering degree of rubber | gum can be evaluated from this peeled test piece.

In addition, sufficient strength is given to a rubber | gum by measuring at 150 degreeC and the pressure of 25 kgf / cm for 30 minutes before adhesive force evaluation. The adhesive force between the rubber and the cord at that time was called initial adhesive force, and the heat-resistant adhesive strength was measured by vulcanization at a pressure of 25 kgf / cm 2 for 170 minutes at 170 ° C., and then the adhesive force between the cord and the rubber was named as heat-resistant adhesive force. .

Rubber coating evaluation was carried out at 170 ° C. for 30 minutes at a pressure of 25 kgf / cm 2 and visually inspected the specimens subjected to CRA-S test to determine the degree of rubber sticking to the cords of A, B, C, D, and E. Evaluation was made by classifying. Grade A refers to the case where more than 80% of rubber is attached or rubber peeling phenomenon occurs. Grade B is 60 ~ 80%, Grade C is 60-40%, Grade D is 40-20%, Grade E is 20% rubber The state of attachment is as follows. The grading was derived by averaging three judges independently.

The composition of the rubber used is as follows.

ingredient Composition ratio (part by weight)

                  Natural rubber 80

                  SBR Rubber 20

                  Zinc Oxide 5

                   Carbon black 40

                  Stearic acid 2

                 Petroleum emulsifiers 10

                    Pinetar 4.0

                       Sulfur 2.5

                 Diphenyl Guanidine 0.75                     

N-phenyl-naphthylamine 1.5

Adhesive force retention was calculated by the following equation.

The tire cord thus obtained had an initial adhesive force of 19.2 Kgf, a heat resistant adhesive force of 14.3 Kgf, and the rubber coating property of grade A, which is enough to cause rubber peeling.

<Example 2>

The same is true except in the second dip, RF initial condensates were used without reacting the components of resorcin and formalin. The tire cord thus obtained had an initial adhesive force of 19.3 Kgf, a heat resistant adhesive force of 14.0 Kgf, and a rubber coating of A grade.

<Example 3>

In the first dip, the same composition as in Example 1 was carried out except that the amount of the epoxy and emulsifier was increased by twice. The tire cord thus obtained had an initial adhesive force of 19.8 Kgf, a heat resistant adhesive force of 14.6 Kgf, and a rubber coating property of grade A, which is enough to cause rubber peeling.

<Comparative Example 1>

The same procedure as in Example 1 was carried out except that water-soluble epoxy was used. The tire cord thus obtained had an initial adhesion of 16.3 Kgf, a heat resistance of 8.2 Kgf, and a rubber coating of D grade.                     

<Comparative Example 2>

The first dip was performed in the same manner as in Example 1 except that SBR Latex was added instead of VP Latex. The tire cord thus obtained had an initial adhesion of 12.3 Kgf, a heat resistance of 5.8 Kgf, and a rubber coating of C grade.

<Comparative Example 3>

The emulsifier was added to the first dip solution in the same manner as in Example 1 except that 5 times the weight of the epoxy was added. The tire cord thus obtained had an initial adhesion of 14.3 Kgf, a heat resistance of 6.8 Kgf, and a rubber coating of D grade.

The adhesive composition according to the present invention provides a deep PET fiber having excellent adhesion retention at high temperatures. In addition, the present invention is to maintain the original properties of the PET fibers while showing excellent adhesion to the rubber after heat aging and at the same time makes it possible to manufacture a deep reinforced PET fiber for rubber reinforcement of the rubber cord of the tire cord.

Claims (5)

In the adhesive composition for preparing reinforced polyester fibers for rubber reinforcement, the primary dip solution is composed of epoxy, blocked isocyanate and latex, and the secondary dip solution is resorcin / formalin / latex or resorcinformalin (RF) initial condensate / An adhesive composition of dipped polyester fiber for rubber reinforcement, which is made of latex and the epoxy used in the primary dip solution is a water-insoluble aliphatic epoxy. The adhesive composition of the reinforced polyester fiber for rubber reinforcement according to claim 1, wherein the epoxy in the water-insoluble aliphatic is a sorbitol polyglycidyl ether compound. The adhesive composition of the reinforced polyester fiber for rubber reinforcement according to any one of claims 1 to 3, wherein the epoxy is added in an amount of 1 to 15 wt% based on the first dip based on the weight ratio. The adhesive composition of the reinforced polyester fiber for rubber reinforcement according to claim 1 or 2, wherein the proportion of the epoxy emulsifier is 10-100% by weight of the epoxy. 2. The adhesive composition of the reinforced polyester fiber for rubber reinforcement according to claim 1, wherein the latex is a mixture of VP latex alone or SB latex.