JPS6046020B2 - Composite of rubber and fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to composites of rubber and fibers that are strongly adhered to each other.

Currently, fibers are used as materials in the rubber industry in large quantities and in a wide variety of applications, from industrial products such as tires, belts, and hoses to everyday products such as rubber cloth and cloth shoes.

Furthermore, the fibers used are used in a variety of ways, from functions as reinforcing materials in industrial products to functions as cloth for combs, shoes, and the like. However, in these composites, the fibers and rubber must be sufficiently bonded, but in most cases the adhesive force between them is insufficient, and the reinforcing effect of the fibers used is not fully realized. Therefore, the value as a product would be lost. In order to solve the above-mentioned problems, the inventors of the present invention have made extensive studies and have discovered that rubber and fibers have excellent adhesion to each other and form an excellent composite, and have completed the present invention. I came to the conclusion.

That is, according to the present invention, maleic anhydride or a derivative thereof is added to a liquid polyisoprene rubber having a cis-1,4 bond content of 70% or more and a molecular weight of 8,000 to 100,000 in the rubber-fiber composite. 0.1 per isoprene monomer unit of polyisoprene rubber
Contains a modified liquid rubber added with ~15 mol% and a solid diene rubber in a weight ratio of (the modified liquid rubber)/(the solid diene rubber) in the range of 5/95 to 60/40. By using rubber mixtures, excellent composites can be obtained due to the excellent adhesion of the rubber to the fibers. The modified liquid rubber used in the rubber mixture in the present invention is an adduct obtained by reacting a specific liquid polyisoprene rubber with maleic anhydride, and the maleic anhydride group introduced in this way is mixed with methanol, ethanol, n- Monoesters are produced by reacting alcohols such as butanol, or amines such as ammonia, n-butylamine, n-propylamine, and ethanolamine.
It means those in the form of diester, ammonium salt, amide, imide, and those to which maleic anhydride derivatives such as maleic acid, maleic ester, maleimide, maleinamide, etc. are added.

Among these, from the viewpoint of the stability of the modified liquid rubber during long-term storage, modified liquid rubbers containing or in the form of maleic anhydride derivatives modified with alcohols, amines, etc. are preferred. Such modified liquid rubber can be obtained by mixing a specific liquid polyisoprene comb with maleic anhydride or a derivative thereof in the presence or absence of a solvent and heating the mixture.

As the solvent used, aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, etc. are used, and inert solvents such as n-hexane, n-heptane, benzene, toluene xylene, etc. are preferably used. It is also possible to use a radical catalyst during the reaction. In the modified liquid rubber used in the present invention, the molecular weight and the amount of cis-1/4 bonds of the liquid polyisoprene that is the base thereof, as well as the amount of maleic anhydride or its derivative added therein, have a large effect on the performance of the composite. Therefore, you must keep this in mind.

That is, such liquid polyisoprene rubber has a molecular weight of 8,000 to 100,000, preferably 15,000.
~55,000 and the amount of cis-1.4 bonds must be 70% or more, preferably 80% or more. If the molecular weight of the liquid polyisoprene rubber is too small than the above range, the degree of improvement in adhesion will be small and the strength of the vulcanizate will decrease too much, whereas if the molecular weight is too large than the above range, In making a composite, the processability is significantly reduced and the effect of improving adhesive strength is not sufficient, which is not preferable. In addition, if the amount of cis-1,4 bonds is less than the above amount, the processability when making a composite will be poor, and the vulcanization efficiency will be poor when vulcanizing. This causes the negative effect of not being able to obtain things. The molecular weight here means the viscosity average molecular weight (Mv), and by measuring the intrinsic viscosity ([η]) in toluene at 30°C, the formula [η] = 1.21 × 10 -4My0.
77. Further, the amount of cis-1.4 bond is a value determined by infrared absorption spectroscopy. Such liquid polyisoprene rubber is produced by anionic polymerization of isoprene monomer, natural rubber, Ziegler catalyst,
It is obtained by thermally decomposing a high molecular weight polyisoprene rubber obtained by polymerizing isoprene monomers using an anionic catalyst.

Among these, from the viewpoint of molecular weight control and quality stability, the most suitable method is direct polymerization without stuttering using a thermal decomposition method, and in particular, anionic polymerization using a lithium-based catalyst that produces many cis-1 and 4 bonds. preferable. In addition, the amount of maleic anhydride or its derivative added to the liquid polyisoprene rubber has a large effect on the performance of the composite, and is 0.00% relative to the isoprene monomer unit in the liquid polyisoprene rubber. 1-15 mol% preferably 0.5
It should be in the range of ~10 mol% da. If the amount added is too small than the above range, the improvement in adhesion that is the objective of the present invention cannot be achieved, and if it is too large, the processability when making a composite will deteriorate, and furthermore, it will deteriorate after vulcanization. Physical properties such as strength deteriorate, which is inappropriate. The solid diene rubber that is one of the constituent components of the rubber mixture used in the present invention is a solid rubber having a double bond in its molecular chain and a molecular weight of at least 300,000, such as natural rubber S (NR). Sisu 1●4-Polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), styrene-isoprene copolymer rubber (SIR), nitrile rubber,
Chloroprene rubber (CR), butyl rubber (IIR), ethylene-propylene-diene copolymer rubber (EPDM)
) etc.

These diene rubbers can be used alone or in a mixture of two or more. Among these, natural rubber or those mainly composed of natural rubber are preferably used. The usage ratio of modified liquid rubber and solid diene rubber is ((modified liquid rubber)/(solid diene rubber)) weight ratio of 5/9.
It ranges from 5 to 60/40, preferably from 10/90 to 50/50.

If the amount of the modified liquid comb used is less than the above range, the effect of improving adhesion will be poor, and if it is too much, processability will deteriorate, and physical properties such as strength will be significantly reduced when vulcanized. do not have. In addition to the above-mentioned modified liquid rubber and solid diene rubber, compounding chemicals commonly used in the rubber industry are blended into this rubber mixture.

Typical examples include fillers such as carbon black, clay, calcium carbonate, magnesium carbonate, and silica, vulcanizing agents such as sulfur and peroxide, activators such as zinc white, magnesium oxide, and stearic acid, and vulcanized vinyl. accelerator,
These include anti-aging agents, plasticizers for process oils, etc. Furthermore, there is no problem in mixing and using low molecular weight polyisoprene and polybutadiene to the extent that the gist of the present invention is not impaired. Fibers that are another component of the present invention include natural fibers such as cotton and hemp, recycled fibers such as rayon, and synthetic fibers such as vinylon, nylon, polyester, and acrylic.

Among these fiber materials, cotton is preferably used. Note that these fibers may be used alone or in combination of two or more. These fibers are used in the form of stable or filament, corded or woven fabrics. The composite of the present invention is one in which woven fabric and rubber are bonded together, one in which woven fabric or cord-like fibers are embedded in rubber, or one in which short cut fibers are filled in rubber. It can take various forms such as.

These are often used after being vulcanized, but depending on the intended use, they can also be used without being vulcanized by taking advantage of the reactivity of the polar group of maleic anhydride or its derivatives added to the modified liquid rubber. In some cases it is possible. The composite according to the present invention can be applied to industrial products such as retirement belts, belts, rubber-coated cloth, cloth shoes, etc. due to its excellent rubber adhesion properties.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples in any way.

Note that "parts" shown in the examples are "parts by weight" unless otherwise specified. Example 1 and Comparative Example 1 Sec-butyllithium was used as a catalyst in n-heptane,
By polymerizing isoprene monomer, the molecular weight is 39.
000 liquid polyisoprene rubber LIR was obtained.

The amount of cis-1.4-bonds in this liquid polyisoprene rubber was 81% according to infrared absorption spectroscopy. Next, 1 part of maleic anhydride was added to 1 (4) parts of this liquid polyisoprene rubber, and the mixture was heated and reacted at 150°C for 5 hours. After the reaction was completed, the reaction mixture was poured into a large amount of acetone to precipitate the rubber component, and at the same time, unreacted maleic anhydride was removed. Thereafter, it was vacuum dried to remove acetone to obtain a modified liquid polyisoprene rubber (IRCA on MAn). The amount of maleic anhydride added to this product was 1.8 mol%.
Separately, a modified liquid polyisoprene rubber M with 1.6 moles of maleimide added was prepared by using maleimide instead of maleic anhydride and carrying out the above-mentioned modification reaction.
IR on M (A) was obtained.

In addition, I on the above-mentioned modified liquid polyisoprene rubber MAn
R(A) 1ω part was dissolved in hexane, 15 parts of ethanol was added thereto, and the mixture was reacted at 100°C for 5 hours to obtain a modified liquid polyisoprene rubber (IRCA on EMAn) in which maleic anhydride groups were monoethyl esterified. . Using the thus obtained liquid polyisoprene rubber (LIRCA), three modified liquid polyisoprene rubbers (IR on MAn (A), IR on MAI (4) and IRCA on EMAn), the compositions shown in Table 1 were used. The formulation was made by roll.

Among these, blend I-6 had a viscosity so low that it could not be kneaded with a roll. This formulation was then used to conduct an adhesion test with fabric. For the adhesion test, first, the unvulcanized compound was placed on a mold lined with cloth, and the mixture was press-vulcanized for 3 minutes at 145°C to bond.The vulcanized product was then cut into 2d widths and subjected to a 180°C peel test. The adhesive strength was measured using the following method. The fabric used was a plain weave cotton fabric with a cover factor of approximately 40. From Table 1, the composite composition 1-1 does not use liquid polyisoprene rubber as the rubber component, and the composite composition 1-2 uses unmodified liquid polyisoprene rubber even when liquid polyisoprene rubber is used. It can be seen that the composite material according to the method peels off at the interface between the cloth and the rubber, and the cloth and the comb are not strongly adhered to each other. On the other hand, formulations 1-4◆5, 7 and 8 using the modified liquid polyisoprene specified in the present invention
In the composite according to the present invention, the cloth and the comb are strongly adhered to each other before the rubber, which is weak in strength, breaks, and it is found to be a desirable composite. However, even if such modified liquid polyisoprene rubber is used, in the case of formulations 1-3 and I-6 in which the proportion used is outside the range specified by the present invention, it is considered a composite. There are some that do not have sufficient adhesion or have poor workability. Example 2 and Comparative Example 2 Sec-butyllithium was used as a catalyst in n-heptane,
By polymerizing isoprene monomer, the molecular weight is . ”4800
A liquid polyisoprene rubber LIR (B) having a cis-1.4 bond content of 83% was obtained.

Next, 1 part, w parts, (9) parts of maleic anhydride were added to 1 beaten part of this liquid polyisoprene rubber, and 16 parts of maleic anhydride was added in toluene.
IR (B), MA on modified liquid polyisoprene rubber MAn (0.05) with different amounts of added maleic anhydride were heated at 0 parts C, reacted, and subjected to the same post-treatment as in Example 1.
n(2.1) above IR(B) and M. IR (B) on Arl(19) was obtained. The amounts of maleic anhydride added were 0.05 mol%, 2.1 mol%, and 19.0 mol%, respectively. Using each of these modified liquid polyisoprene rubbers, formulations were prepared according to the formulations shown in Table 2, and the same adhesion test with cotton cloth as in Example 1 was conducted. (1) Cold SBR; JSR#1502 manufactured by Japan Synthetic Rubber Co., Ltd.
(2) *; The vulcanizate is too hard and has poor rubber elasticity. From Table 2, if the amount of maleic anhydride added to the modified liquid polyisoprene rubber used is less than the amount specified in the present invention, the resulting composite will peel off at the interface between the rubber and the fabric (formulation -1), and conversely, when the amount added is too large, the resulting composite becomes hard (formulation 1-4) and does not exhibit rubber elasticity. On the other hand, it has been found that a good composite can be obtained when the amount added is within the range defined by the present invention. Example 3 By polymerizing isoprene monomer in n-hexane by changing the amount of Sec-butyllithium used as a catalyst, the amount of cis-1.4 bonds was 80% and the molecular weight was 5500.
Liquid polyisoprene rubber LIR (C-5500) has a cis-1,4 bond content of 83% and a molecular weight of 48,000 Liquid polyisoprene rubber LIR (D-48,000) has a cis-1,4 bond content of 86% and a molecular weight of 150,000 Polyisoprene rubber LIR (E-150000) was obtained.

W parts of maleic anhydride were added to 1 (4) parts of these polyisoprene rubbers, and the mixture was heated and reacted in toluene at 150°C, so that the amounts of maleic anhydride added were 3.3 mol%, 3.1 mol%, and 2 mol%, respectively. .9 mol% modified polyisoprene rubber MAn
Upper IR (C-5500) MAn upper IR (D-48000
) and IR on MArl (E-150,000) were obtained.
Using these modified polyisoprene rubbers, open roll formulations were prepared according to the formulations shown in Table 3. M
In the case of formulation 1-4 using IR on An (E-150000), the viscosity of the formulation became extremely high during roll kneading, making kneading extremely difficult. The adhesive strength was measured in the same manner as in Example 1 except that a woven fabric made of rayon spun yarn was used as the fiber. At the same time, the strength of the vulcanizate was also measured. The results are shown in Table 3. (1) N-oxydiethylene-2-benzothiazole sulfenamide; manufactured by Ouchi Shinko Co., Ltd. As is clear from Noxel MAS Table 3, the product using modified liquid polyisoprene rubber adheres almost well to rayon woven fabric. ing.

However, the physical properties of the vulcanizate are limited to modified liquid polyisoprene MAn whose molecular weight of the rubber before modification is within the range of the present invention.
When using upper IR (D-48000) (formulation ■-3)
IR (C-
5500) (formulation ■-2), the strength of the vulcanizate decreased significantly, and conversely, when using modified liquid polyisoprene MAn IR (E-150000), which has a too high molecular weight (formulation ■-2), the strength of the vulcanizate decreased significantly. 4) is an unbalanced material, such as one in which the elongation of the vulcanizate is greatly reduced. In other words, when liquid polyisoprene rubber (MAn IR (D-48000)) whose molecular weight is within the range specified in the present invention is used, the peel stress is also excellent in the strength and elongation properties of the vulcanizate. Example 4 In polymerizing isoprene monomer using Sec-butyllithium in n-hexane, by adding varying amounts of ethyl ether,
Three types of liquid polyisoprene rubbers having different amounts of cis-1 and 4 bonds were obtained.

Claims (1)

[Claims] 1 Cis-1.4 bond amount is 70% or more and molecular weight is 800
A modified liquid rubber obtained by adding 0.1 to 15 mol% of maleic anhydride or a derivative thereof per isoprene monomer unit of the liquid polyisoprene rubber to a liquid polyisoprene rubber having a molecular weight of 0 to 100,000, and a solid diene rubber (as described above). The weight ratio of (modified liquid rubber)/(the solid diene rubber) is 5/
A composite consisting of fibers and a rubber mixture containing 95 to 60/40.