JPH1081862A - Method for bonding polyester fiber to rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bonding method whereby an excellent adhesion of a rubber to hardly bondable polyester fibers, which formerly needed a two-bath treatment, can be obtd. by a one-bath treatment without the necessity for using easily bondable threads, etc., by using a specific adhesive compsn. SOLUTION: In this method, polyester fiber cords are impregnated with an adhesive compsn., subjected to dry heat treatment, then buried in an unvulcanized rubber, and united to the rubber by vulcanization. The adhesive compsn. is prepd. by mixing a water-base liq. mixture (A) comprising a resorcinol (R)- formaldehyde (F) pecondensate (RF) and at least one latex (L) of at least either a styrene-butadiene-vinylpyridine terpolymer or a styrene-butadiene copolymer with a water-base dispersion (B) of a substantially water-insolub1e epoxy resin having an epoxy equivalent of 300 or lower. The molar ratio of F to R 1.5-2.8; the wt. ratio (solid basis) of RF to L, is 0.075-0.25; and the wt. ratio of mixture A to dispersion B is 0.15-1.20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bonding a polyester fiber and a rubber used for producing a rubber composite product obtained by reinforcing a rubber such as a tire or a conveyor belt hose with a polyester fiber.

[0002]

2. Description of the Related Art Conventionally, polyester fibers are bonded to rubber by treating the fibers in advance with epoxy or blocked isocyanate, and then treating with an aqueous mixture (RFL) of a resorcinol-formaldehyde precondensate and rubber latex. Or an aqueous solution containing p-chlorophenol / resorcin / formaldehyde condensate (for example, Denabond (trademark) manufactured by Nagase Kasei Kogyo Co., Ltd.) or allyl hydroxyphenyl ether / resorcin / formaldehyde condensate, followed by RFL treatment. Although the so-called two-bath treatment is applied, such a bonding method has problems that the productivity is low and the bonding strength is not always high.

[0003] From the viewpoint of productivity, the above-mentioned p
A chlorophenol-resorcin-formaldehyde condensate (eg, Denabond R manufactured by Nagase Kasei Kogyo Co., Ltd.) or an allylhydroxyphenyl ether-formaldehyde condensate is added to an aqueous mixture (RFL) of a resorcinol-formaldehyde initial condensate and a rubber latex; Although there is a method of treating in a bath, these condensates are aqueous ammonia solutions, and have environmental problems such as odor problems, and also have a problem that the adhesive strength is not sufficient. As a method for solving this problem, we have filed Japanese Patent Application No. 7-109704 (Heisei 7-109704).
(Filed on May 8, 2010), a single bath treatment method using a water-based adhesive agent composed of a mixed solution of an epoxy resin and RFL was proposed.

[0004]

Accordingly, the present invention provides an excellent adhesiveness between a poorly-adhesive polyester fiber and a rubber which conventionally required a two-bath treatment for adhesion to the rubber due to its poor adhesion. It is an object of the present invention to provide an adhesive composition capable of performing a single-bath treatment without using the above-mentioned easily adhesive yarn or the like.

Further, the present invention provides a cord / rubber which simplifies heat treatment, saves energy, has high productivity, and further improves the working environment without using ammonia water or the like unlike the conventional method. It is intended to provide a complex.

Further, the present invention relates to the above-mentioned Japanese Patent Application No. 7-1097.
As a result of further study on the invention of the No. 04 application,
It has been found that a more preferable range exists for the RFL composition ratio and the latex composition ratio, and it is an object of the present invention to obtain higher adhesion in bonding rubber and polyester fiber.

[0007]

According to the present invention, (1)
At least one rubber latex (L) of resorcinol (R) -formaldehyde (F) precondensate (RF), styrene-butadiene-vinylpyridine copolymer (VP) latex and styrene-butadiene copolymer (SBR) latex An aqueous mixture (a) of (a) and (2) an aqueous dispersion of an epoxy resin having an epoxy equivalent of 300 or less and substantially insoluble in water (b) are mixed together to form a polyester fiber. In a method for bonding polyester fiber and rubber, which are impregnated and adhered to a cord, then subjected to a dry heat treatment, embedded in unvulcanized rubber, and vulcanized and integrated, the resorcinol (R) of the aqueous mixed solution (a) and formaldehyde are used. The compounding molar ratio (F / R) of (F) is 1.5 to 2.8, and the solid mixture weight ratio of RF and L (RF / L) is 0.075 to 0.2. Weight ratio is in the range of, and aqueous dispersion (b) an aqueous mixture (a) (b / a) is 0.1
There is provided a method for bonding a polyester fiber and rubber, which is in the range of 5 to 1.20.

According to the present invention, the latex used in the aqueous mixed solution (a) comprises a mixture of a styrene-butadiene / vinylpyridine copolymer latex (VP) and an SBR latex (S), and the solid content ratio (VP /
S) A method for bonding a polyester fiber and rubber having a weight ratio within the range of 80/20 to 20/80 is provided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, a rubber latex comprising a latex of a resorcinol-formaldehyde precondensate and a styrene-butadiene-vinylpyridine copolymer (VP) and / or a styrene-butadiene copolymer (SBR). (A) (hereinafter referred to as "RFL"), a water-insoluble epoxy resin dispersion liquid (b) obtained by dispersing an epoxy resin having an epoxy equivalent of 300 or less in water. The impregnated polyester fiber is impregnated and adhered to the poorly adherent polyester fiber, then subjected to a heat treatment for drying, then embedded in unvulcanized rubber, vulcanized and integrated to obtain a polyester fiber having excellent adhesion. And rubber can be bonded.

[0010] The resorcinol (R) -formaldehyde (F) precondensate (RF) used for RFL is already widely used, and resorcinol and formalin aqueous solution are dissolved in water, and sodium hydroxide, potassium hydroxide or the like is used. There are a resol type in which an alkali metal hydroxide is reacted as a catalyst and a novolak type in which the reaction is performed in the presence of an acidic catalyst such as oxalic acid or hydrochloric acid. In the present invention, any of them can be used. The RFL used in the present invention has a compounding molar ratio (F / R) of resorcinol (R) and formaldehyde (F) of 1.5.
~ 2.8, more preferably 1.8 ~
2.5. When this ratio is less than 1.5, the crosslinking property of the adhesive layer is low, and the adhesive strength is significantly reduced. On the other hand, if it exceeds 2.8, the crosslinking property of the adhesive layer becomes too high, and the adhesive layer becomes brittle, and the adhesive property is reduced. In addition, the stability of the processing solution over time is deteriorated.
As the novolak type precondensate, Sumikanol 700 manufactured by Sumitomo Chemical Co., Ltd. and Adha-RF manufactured by Hodogaya Chemical Industry Co., Ltd. are commercially available. When these novolak type RF resins are used, it is necessary to add a small amount of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide in order to dissolve in water. When these novolak-type RF resins are usually used, it is necessary to add a formalin aqueous solution later.

In the present invention, the rubber latex (L) is a styrene-butadiene-vinylpyridine terpolymer (V
P) It is preferable to use a latex and an SBR latex, and it is particularly preferable to use a styrene / butadiene / vinylpyridine terpolymer latex from the viewpoint of adhesiveness. For this, it is preferable to appropriately mix and use an SBR latex or a natural rubber latex. it can. The resorcinol-formaldehyde precondensate (R) used in the present invention
The compounding ratio (RF / L) of the rubber compound (F) and the rubber latex (L) is 0.075 to 0.25, preferably 0.1 to 0.5, in terms of solids weight ratio.
1 to 0.2. If this value is too large, the adhesive layer becomes brittle, and the adhesiveness also decreases. On the other hand, if the amount is too small, the co-crosslinking property between the rubber and the adhesive layer is reduced, so that the adhesive property is significantly reduced, which is not preferable.

The epoxy resin used in the present invention comprises:
An epoxy resin having an epoxy equivalent of 300 or less and being substantially insoluble in water, which is generally used for bonding between fibers and rubber. For example, a water-soluble epoxy resin obtained from the reaction between a polyol and epichlorohydrin (for example, Denacol EX313, EX61 manufactured by Nagase Kasei Kogyo Co., Ltd.)
4, EX512) are water-soluble and therefore, when added to RFL, the epoxy reacts with the RF resin, causing gelation of the adhesive and lowering of the adhesiveness. Here, “substantially insoluble in water” means that the solubility of 10 parts by weight of epoxy resin in 90 parts by weight of water at room temperature is less than 10%. Even a water-insoluble epoxy resin that is liquid at room temperature or liquid at room temperature having a melting point of less than 40 ° C. cannot be used in the present invention. Further, the epoxy resin used in the present invention must have an epoxy equivalent of 300 or less.

The epoxy resin used in the present invention should preferably be solid at room temperature, for example, have a melting point of 40 ° C. or higher. The reason is that the adhesive composition of the present invention is usually used at room temperature and is exposed to an environment of 5 to 40 ° C. According to the study of the present inventors, the epoxy liquid which is liquid under the temperature atmosphere at the time of use reacts with the RF resin when left mixed with RFL and causes gelation and adhesion of the adhesive, which is not preferable. This is presumed to be because when the RF resin is dissolved in water and the epoxy resin is dispersed in a liquid state, the reaction becomes easier than when the epoxy resin is dispersed in a solid state. Therefore, it is essential to select an epoxy resin that does not cause liquefaction due to thermal softening at a normal use environment temperature, for example, below 40 ° C.

The epoxy resin used in the present invention must have an epoxy equivalent of 300 or less.
Here, the “epoxy equivalent” is a molecular weight per epoxy group of the epoxy resin, and the epoxy equivalent is 30.
If it exceeds 0, sufficient adhesive strength cannot be obtained because the number of epoxy groups that substantially react with the fiber is small. From the viewpoint of adhesiveness, the epoxy equivalent is more preferably 150 to 250. Such epoxy resins include, among polyphenol type epoxy resins, phenol novolak type, cresol novolak type, hydroquinone type, brominated novolak type, xylene-modified novolak type, phenol glyoxal type, trisoxyphenylmethane type,
Trisphenol PA type and bisphenol A novolak type epoxy resins are exemplified. A particularly preferred epoxy resin is a cresol novolak type epoxy resin in terms of adhesiveness and versatility.

Further, in the present invention, it is preferable that the aqueous dispersion of the epoxy resin contains substantially no organic solvent. Usually, in order to disperse these epoxy resins in water, a method of once dissolving the ethoxy resin in an organic solvent such as toluene and dispersing in water using an appropriate dispersant is performed. However, as described above, when dispersed in water in a liquid state, there is a problem that a reaction with the RF resin easily occurs, and the adhesive strength is reduced. When mixed with RFL, the epoxy resin is liable to cause coagulation and precipitation.

In the present invention, a known method can be used to obtain an aqueous dispersion containing substantially no organic solvent. For example, a solid epoxy resin is heated to a temperature equal to or higher than the heat softening temperature at room temperature to be in a molten state, mixed with hot water and a dispersant, stirred, and further passed through a colloid mill to further reduce the average particle diameter, for example, to 5 μm or less. To This method can be applied to an epoxy resin that melts below the boiling point of water. When an epoxy resin having a higher heat softening temperature is used, the epoxy resin is dissolved using an organic solvent in which the epoxy resin is soluble, and water and a dispersing agent are added to a stirrer having a high shearing force. Mixing and stirring to a predetermined degree of dispersion,
Furthermore, an aqueous dispersion of an epoxy resin substantially free of an organic solvent can be obtained by performing distillation under reduced pressure to remove the organic solvent.

As the dispersant used here, a known nonionic dispersant or anionic dispersant is used. It is possible to use a cationic dispersant, but it is not preferred because gelling may occur when added to RFL.

The average dispersed particle size of the epoxy resin in the aqueous epoxy resin dispersion according to the present invention is preferably 5 μm or less, more preferably 0.1 to 4 μm. When the average particle size exceeds 5 μm, the dispersion stability of the aqueous dispersion is poor, and the epoxy resin tends to settle when the adhesive is used, so that sufficient adhesive strength may not be obtained. Therefore, in order to obtain more stable adhesion, the average particle diameter is preferably set to 5 μm or less.

Polyester fibers to which the adhesive composition of the present invention is applied include polyethylene terephthalate fibers,
Polyethylene-2,6 naphthalate fiber and the like can be mentioned.

The solid content ratio (b / a) of the RFL aqueous mixture (a) and the aqueous dispersion of epoxy resin (b) is 0.1% by weight.
It is in the range of 5 to 1.20, preferably 0.2 to 1.0. If this value is too low, good adhesive strength cannot be obtained, while if it is too high, the adhesive strength will decrease and the cord will become hard, which may reduce fatigue and workability.

In the adhesive composition of the present invention, the alkali metal hydroxide contained in the adhesive composition is more preferably 0.05 to 1.0% by weight based on the total solid content of the adhesive. . Usually, when preparing an RFL, an alkali metal hydroxide is used. However, when the alkali metal hydroxide finally contained in the adhesive composition exceeds 1.0% by weight, adhesion to a polyester fiber is particularly increased. In this case, the alkali metal hydroxide acts as a catalyst to easily cause hydrolysis of the polyester fiber, and as a result, the heat-resistant adhesiveness may be unfavorably deteriorated. On the other hand, when the amount of the alkali metal hydroxide is less than 0.05% by weight, the novolak resorcinol-formaldehyde precondensate tends to be particularly difficult to dissolve in water. Is undesirably required because productivity tends to decrease.

The temperature of the drying heat treatment after applying the adhesive composition according to the present invention to the fiber is preferably 220 ° C. or higher, more preferably 230 to 240 ° C. If the heat treatment temperature is lower than 220 ° C., the adhesion tends to decrease, which is not so preferable.

[0023]

EXAMPLES The present invention will be further described with reference to the following examples, but it goes without saying that the scope of the present invention is not limited to these examples.

Examples 1 to 6 and Comparative Examples 1 to 4 Resorcinol / formaldehyde precondensates (RF) having various molar ratios (F / R) of resorcinol (R) and formaldehyde (F) as shown in Table I ) And styrene
Butadiene / vinylpyridine (VP) copolymer latex (Nipol 2518FS, manufactured by Zeon Corporation) (L)
Was used in an aqueous mixture (a) (solid concentration 18% by weight) in which the weight ratio (RF / L) shown in Table I was blended. The resorcinol-formaldehyde precondensate used here was prepared by previously preparing a resorcinol-formaldehyde molar ratio (F / R) =
After dissolving a novolak-type precondensate precondensed under an acidic catalyst at a ratio of 0.6 in water in which a predetermined amount of sodium hydroxide is dissolved, the F / R molar ratio shown in Table I is further obtained. It was adjusted by adding formalin as described above. Further, an aqueous dispersion (b) (solid content concentration: 40% by weight) of an orthocresol novolak type epoxy resin (epoxy equivalent: 230, melting point: 85 ° C.) was prepared.

[0025]

[Table 1]

[0026]

[Table 2]

The above aqueous mixture (a) and aqueous dispersion (b)
Using an adhesive composition having a solid content of 20% by weight blended with b / a (weight ratio) = 0.3, polyethylene terephthalate fibers (1500D / 2 40 × 4
0 (times / 10 cm)). In the treatment, the fiber was immersed in the above-mentioned adhesive composition, adjusted to have an adhesion amount of 5% by weight, dried at 100 ° C. for 1 minute, and then heat-treated at 240 ° C. for 2 minutes.

Next, the adhesion test between the obtained treated polyester fiber and rubber was performed as follows using the unvulcanized rubber composition shown in Table II.

[0029]

[Table 3]

The pull-out force test was carried out according to T
According to the test, a treated cord was embedded in a predetermined length in an unvulcanized rubber block, and after vulcanization, the cord was pulled out of the rubber block, and the pulling force at this time was measured. In the peeling force test, 30 cords 1 treated as shown in FIG. 1 were aligned as a set of 30 cords each having a width of 25 mm, and embedded in a sheet 2 of an unvulcanized rubber compound shown in Table II. The ply was adhered and vulcanized to obtain a rubber / cord composite 3. Next, the ply was peeled off at a speed of 50 mm / min with a peeling tester as shown in FIG. 1, and the peeling force at this time was measured. The results are shown in Table I as indices with the value of Comparative Example 1 being 100.

As is clear from comparison between Comparative Examples 1 and 2 and Examples 1 to 3, excellent results were obtained when the molar ratio (F / R) of formaldehyde to resorcin was 1.5 to 2.5. Adhesiveness is obtained. Comparative Examples 3 and 4
As is clear from comparison between Examples 4 to 6, excellent adhesion is obtained when the weight ratio (RF / L) of the resorcinol-formaldehyde precondensate to the rubber latex is in the range of 0.1 to 0.25. .

Examples 7 to 12 Among the formulations shown in Example 5, VP latex (Nipol 2518FS manufactured by Zeon Corporation) as a latex component and SBR
Table II shows the latex (Nipol LX112 manufactured by Zeon Corporation)
An aqueous mixed solution (a) composed of components mixed at the compounding weight ratios as shown in I and an aqueous dispersion of an epoxy resin (b) used in the previous example were prepared and evaluated in the same manner as in the previous example. did. The results are shown in Table III.

[0033]

[Table 4]

As is clear from the results of Examples 7 to 12, the more excellent the adhesion, the more the mixture weight ratio of VP latex and SBR latex (VP / SBR) is particularly in the range of 80/20 to 20/80. This is a more preferred range because of its good properties.

[0035]

According to the bonding method according to the present invention, a good adhesive force is exhibited as compared with the conventional method, and the tire durability is further improved in consideration of the reduction of the weight of the tire and environmental measures in the future. Sex is required. Therefore, the load on the adhesive layer becomes larger than before, and further improvement in adhesiveness is required. The polyester fiber cord treated according to the method of the present invention provides good adhesion to a rubber composition composed of natural rubber, SBR rubber, IR, BR or a mixture thereof, particularly used for tires and conveyor belts. Note that SB
R latex has a lower cost than VP latex, and therefore, the greater the ratio of SBR latex, the more effective the cost reduction.

[Brief description of the drawings]

FIG. 1 is a drawing showing a peeling force test method of an example and a comparative example.

[Explanation of symbols]

 1: Cord 2: Uncured rubber compound sheet 3: Cord / rubber composite

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C09J 163: 00)

Claims (2)

[Claims] (1) At least one of resorcinol (R) -formaldehyde (F) precondensate (RF), styrene-butadiene-vinylpyridine copolymer (VP) latex and styrene-butadiene copolymer (SBR) latex Aqueous mixed solution (a) of one type of rubber latex (L)
And (2) an adhesive composition obtained by mixing an aqueous dispersion (b) of an epoxy resin having an epoxy equivalent of 300 or less and being substantially insoluble in water after impregnating and adhering the polyester fiber cord. In a method for bonding a polyester fiber and rubber, which are subjected to a drying heat treatment, embedded in an unvulcanized rubber, and vulcanized and integrated, the mixing molar ratio of resorcinol (R) and formaldehyde (F) in the aqueous mixed solution (a) (F /
R) is in the range of 1.5 to 2.8, the weight ratio of mixed solids of RF and L (RF / L) is in the range of 0.075 to 0.25, and the aqueous dispersion (b) A weight ratio (b / a) of the mixture and the aqueous mixture (a) is in the range of 0.15 to 1.20. 2. The latex used in the aqueous mixed solution (a) is a mixture of a styrene-butadiene / vinylpyridine copolymer latex (VP) and an SBR latex (S), and a solid content ratio (VP / S) ) (Weight ratio)
2. The method according to claim 1, wherein the ratio is in the range of 80/20 to 20/80.