JPH0655855B2 - Manufacturing method of rubber cross-linked product - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a rubber crosslinked product obtained by crosslinking in a predetermined shape in hot air, and particularly to a method for producing a rubber crosslinked product having high hardness.

[Prior art]

As the rubber cross-linked product, natural rubber, synthetic rubber, 1,2-P
BD and the like are used, and in order to obtain a product having particularly high hardness, a high-hardness crosslinked product (ebonite compound) containing a large amount of sulfur is known. However, most of these are manufactured by a method of crosslinking and molding into a desired shape using a mold.

As a method for producing a high hardness rubber by hot air crosslinking without using a mold, a small amount of natural rubber and synthetic rubber have been tried. However, under the present circumstances, the natural rubber and the synthetic rubber-based hardness rubber obtained by this method are not satisfactory in that the shape at the time of crosslinking is limited to a flat sheet shape.

[Means for solving problems]

The present invention provides (A) a vinyl bond content of 70% or more, a crystallinity of 5% or more, and an intrinsic viscosity [η] (in tolue, 30 ° C.) of 0.5 dl.
/ G or more 1,2-PBD, 40 to 100 wt%, and (B) 0 to 60 wt% of one or more unvulcanized rubber selected from natural rubber, diene-based synthetic rubber and non-diene-based synthetic rubber After molding a composition in which (C) a softening agent for rubber 0 to 100 parts by weight, and (D) a filler 0 to 600 parts by weight per 100 parts by weight of the mixture [(A) + (B)] It is intended to provide a method for producing a rubber crosslinked product by crosslinking in hot air without using a mold.

The component (A) 1,2-PBD used in the present invention is 1,2 in order to obtain appropriate hardness and shape-following property during crosslinking.
The content of 2 bonds is 70% or more, preferably 85% or more, the crystallinity is 5% or more, preferably 10 to 40%, and the molecular weight can be selected over a wide range, but the kneadability and the present invention [Η] (toluene, 30 ° C) is preferably 0.5 dl / g or more in order to obtain a crosslinked product having a high hardness, which is the purpose of.

The unvulcanized rubber which is the component (B) of the present invention is used in the range of 0 to 60% by weight, preferably 0 to 30% by weight for improving the kneading processability and adjusting the hardness. Typical examples thereof include natural rubber (NR) and polyisoprene rubber (I
R), styrene-butadiene rubber (SBR), polybutadiene rubber (BR), acronitrile rubber (NBR),
Diene-based synthetic rubbers such as chloroprene rubber (CR) and non-diene-based synthetic rubbers such as ethylene-propylene rubber (EPR), ethylene-propylene terpolymer (EPDM), acrylic rubber (ACM, ANM), and fluororubber. . Of these, NR and I are preferred.
R, SBR and BR.

The (C) component softening agent for rubber used in the present invention is a mineral oil-based softening agent generally called process oil or extender oil, which is a combination of an aromatic ring, a naphthene ring and a paraffin ring. A mixture is preferable, and a paraffin chain having a carbon number of 50% or more of the total carbon number is called a paraffin type and has a naphthene ring carbon number of 3
Naphthenes are used for 0 to 45%, and aromatics for which the number of aromatic carbons is more than 30%. The mineral oil-based rubber softening agent used as the component (C) of the present invention is preferably a naphthene-based or aromatic-based softening agent in the above category in terms of compatibility with the component (A).

The blending amount of the component (C) softener is the component [(A) + (B)].
0 to 100 parts by weight, preferably 5 to 100 parts by weight
~ 30 parts by weight.

When the amount is 100 parts by weight or more, it is difficult to obtain a crosslinked product having a high hardness, and kneading processability becomes poor.

Examples of the filler as the component (D) used in the present invention include light calcium carbonate, heavy calcium carbonate, various surface-treated calcium carbonates, talc, magnesium hydroxide, mica, clay, barium sulfate, and natural silicic acid. , Synthetic silicic acid, titanium oxide, glass fiber, carbon fiber, cotton floc and various carbon blacks can be used. Among these fillers, heavy calcium carbonate, light calcium carbonate and talc are economically advantageous and preferable.

The amount of the filler compounded is 0 to 600 parts by weight, preferably 400 parts by weight, based on 100 parts by weight of the component [(A) + (B)]. If the amount exceeds 600 parts by weight, the kneading processability is poor, and the mechanical strength of the resulting crosslinked product is significantly reduced.

In the production of the crosslinked product of the present invention, the above compositions (A) to (D) may be irradiated with radiation such as ultraviolet rays or X-rays for crosslinking, but sulfur or an organic peroxide is added. It is preferable.

In the present invention, the amount of the cross-linking agent such as sulfur or organic peroxide is not particularly limited, but by increasing the blending amount of these cross-linking agents, high hardness (for example, JIS K-6301, J
It is possible to produce a crosslinked product having an IS-C hardness meter of 65 or more).

In the case of sulfur crosslinking, powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur and the like can be used. The compounding amount of sulfur is 0.1 to 100 parts by weight with respect to 100 parts by weight of the component [(A) + (B)], but 5 to 100 parts by weight is preferable in order to obtain a crosslinked product having high hardness. , More preferably 15 to 100 parts by weight, particularly preferably 20 to 600.
Parts by weight. If the amount of sulfur is small, a crosslinked product having a high hardness cannot be obtained (ebonite is not sufficiently formed), and 100
If it is more than parts by weight, the heat of reaction during crosslinking will cause deformation of the crosslinked product,
There is a high possibility of causing phenomena such as destruction.

In the case of sulfur crosslinking, it is preferable to add various vulcanization accelerators at the same time for crosslinking. As a specific example of the vulcanization accelerator, tetramethylthiuram disulfide (TMT
D), tetramethylthiuram monosulfide (TMT
M), N-oxydiethylene-2-benzothiazolyl
Sulfenamide (OBS), N-cyclohexyl-2
-Benzothiazole sulfenamide (CBS), dibenzothiazyl disulfide (MBTS), 2-methylcaptobenzothiazole (MBT), zinc di-n-butyldithiocarbamate (ZnBDC), zinc dimethyldithiocarbamate (ZnMDC) and the like.

In the case of blending with organic peroxide, dicumyl peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, α, α′-di-t-butylperoxydi p-diisopyropyr Benzene, n-butyl-4,4
-Bis-t-butylperoxyvalerate, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and the like can be used. .
The blending amount of the organic peroxide is the component [(A) + (B)] 10
It is 0.1 to 15 parts by weight with respect to 0 parts by weight, but 0.5 to 15 parts by weight is preferable in order to obtain a crosslinked product having high hardness,
More preferably 2 to 15 parts by weight, particularly preferably 4 to 1
0 parts by weight. If the amount of the organic peroxide is small, a crosslinked product having a high hardness cannot be obtained, and if it is more than 15 parts by weight, there is a high possibility that phenomena such as deformation and destruction will occur during the crosslinking.

In the case of peroxide crosslinking, various polyfunctional monomers may be added at the same time.

Specific examples of the polyfunctional monomer include trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, triallyl isocyanurate, diallyl phthalate and the like.

Further, if necessary, in addition to the above-mentioned additives, various additives such as an activator, an anti-aging agent and a processing aid may be appropriately added to the sulfur crosslinking composition and the peroxide crosslinking composition.

The method of mixing the above-mentioned (A) to (D) and other compounding agents is not particularly limited, and can be a mixing method used for general rubber compounds such as Banbury type mixer, pressure kneader and open roll. Is. The uncrosslinked compound thus obtained is subjected to cross-linking in hot air after being formed into, for example, a sheet shape using a calendar roll, an extruder or the like. The crosslinking temperature is 120 to 250 ° C., preferably 140 to 180 ° C. in the hot air for crosslinking. At this time, it is not necessary to pressurize, and it is possible to perform crosslinking under atmospheric pressure. At the time of this bridge, wooden type, viscosity type,
Make a desired shape with a mold, etc., and put an uncrosslinked sheet on the mold, the uncrosslinked sheet softens by heat and follows the shape of the back surface of the mold to obtain the desired shape. It is possible. It is also possible to firmly crosslink and adhere to the mold by using an adhesive, a pressure-sensitive adhesive or the like at the time of crosslinking.

The crosslinked product according to the present invention has a good shape following property despite hot air crosslinking under atmospheric pressure, and a rubber crosslinked product having a high hardness can be obtained.

Since vulcanization is performed by hot air, expensive dies and press equipment are not particularly required, and it is possible to cross-link long products that were not possible with conventional vulcanization of dies.

The crosslinked product of the present invention can be widely used for various linings, industrial products and the like.

Next, the present invention will be described more specifically by showing Examples and Comparative Examples.

In the examples and comparative examples, the sagging test is 80 ×.
An uncrosslinked rubber sheet was placed on an iron plate having a thickness of 1 mm with a hole of 40 mm and the temperature was raised. When the sheet was crosslinked, the deformation distance at which the sheet fell into the hole was measured. The hardness is J
The hardness was measured with a type A and type C hardness meter of IS K-6301.

The bending strength was measured by the method based on JIS K-7203. The maximum deformation represents the deformation distance until the crosslinked sheet breaks when the bending strength is measured.

Example 1 is an example of sulfur cross-linking compounding, 1,2-PBD (Japan Synthetic Rubber Co., Ltd., JSR RB810, vinyl bond content 90%, crystallinity 18% [η] toluene 30 ° C. = 1.2.
5) and other compounding agents were mixed in a mixing ratio shown in Table 1 by a BR Banbury mixer, and the uncrosslinked sheet which was suitted to a thickness of 2 mm by a 10-inch test roll machine was heated at 155 ° C. for 25 minutes. Crosslinked in. The results of the physical property test are shown in Table 1.

Examples 2 and 3 are examples of sulfur cross-linking compounding as in Example 1,
Using 70 parts by weight of 2-PBD (JSR RB810),
A crosslinked product was obtained in the same manner as in Example 1. The results of the physical property test are shown in Table 1.

Examples 4 and 5 Crosslinked products were obtained in the same manner as in Example 1 except that the amount of urisulfur compounded was changed as shown in Table 1 for sulfur crosslinking compounding. The results of the physical property test are shown in Table 1.

Examples 6 and 7 are examples of peroxide cross-linking compounding, which are 1,2-PBD (J
A cross-linked product was obtained in the same manner as in Example 1, except that SR RB810) was used and the type of the filler was changed to heavy calcium carbonate or talc. The results of the physical property test are shown in Table 2.

Example 8 Similarly, it is an example of peroxide cross-linking compounding, and 1,2-PB
80 parts by weight of D (JSR RB810) and SBR (JSR RB810)
1502) A crosslinked product was obtained in the same manner as in Example 1 using 20 parts by weight. The results of the physical property test are shown in Table 2.

Comparative Examples 1 and 2 are comparative examples of sulfur cross-linking compound, and the polymer used is S
A crosslinked product was obtained in the same manner as in Example 1 except that 100 parts by weight of BR (JSR1502) or natural rubber was used. The results of the physical property test are shown in Table 1.

Comparative Examples 3 and 4 Comparative examples of peroxide cross-linking compound, in which SBR (JSR1502) was used as the polymer, and the type of the filler was changed to heavy calcium carbonate or talc. Got The results of the physical property test are shown in Table 2.

Tables 1 and 2 show that Examples 1 to 8 which are compositions of the present invention have a large sag as compared with Comparative Examples 1 to 4 which are outside the scope of the present invention, although the hardness is high. I understand. This means that when the uncrosslinked sheet according to the present invention is placed on the uneven plate-like material and cross-linked at the time of cross-linking, the plate-like material It shows that the conformability to the shape is extremely good.

〔The invention's effect〕

The rubber composition of the present invention does not particularly require a mold at the time of crosslinking,
Even with hot air cross-linking, the shape-following property is good, so a cross-linked product of the desired shape can be obtained, and at the same time, a cross-linked product with high hardness can be obtained, so it can be widely used for various linings, industrial products, etc. .

Claims (1)

[Claims] 1. A vinyl bond content of 70% or more, a crystallinity of 5% or more, and an intrinsic viscosity [η] (in toluene, 30%).
40 to 100% by weight of 1,2-polybutadiene having a temperature of 0.5 dl / g or more and (B) at least one unvulcanized rubber selected from natural rubber, diene-based synthetic rubber and non-diene-based synthetic rubber To 60 wt% of the mixture [(A) + (B)] 100 parts by weight, (C) rubber softening agent 0-100 parts by weight (D) filler 0-600 parts by weight A method for producing a rubber cross-linked product, which comprises cross-linking in hot air without using a mold after molding.