JPS62288647A - Crosslinked polymer - Google Patents

Abstract

PURPOSE:To obtain a crosslinked material having high hardness and excellent shape-following performance in crosslinking, by crosslinking a composition containing a specific block copolymer and/or ethylene-vinyl acetate copolymer and optionally an unvulcanized rubber, etc., in a heat medium. CONSTITUTION:(A) 0-100pts.wt. of a rubber softener, (B) 0-600pts. of a filler and preferably (C) sulfur or an organic peroxide are compounded to 100pts. of a mixture composed of (D) 40-100wt% block copolymer of an aromatic vinyl compound (preferably styrene) and a conjugated diolefin (preferably 1,3-bu tadiene or isoprene) and/or an ethylene-vinyl acetate copolymer having a vinyl acetate content of preferably 5-45% and a melt flow index of preferably 0.2-50g/10min and (E) 0-60% unvulcanized rubber, preferably NR, IR, SBR, etc. The obtained composition is crosslinked in a heat medium to obtain the titled crosslinked product.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a crosslinked product formed by crosslinking into a predetermined shape in a heat medium, and particularly relates to a crosslinked product that has excellent shape followability during crosslinking. Concerning high hardness crosslinked products.

[Prior art]

Examples of rubber-based crosslinked products include natural rubber, synthetic rubber, 1.2-
PBD and the like are used, and in order to obtain particularly high hardness, high hardness crosslinked products (ebonite compounds) containing a large amount of sulfur are known. However, most of these are manufactured by a method of crosslinking molding into a desired shape using a mold.

A method of manufacturing high hardness rubber by heat medium crosslinking without using a mold has been attempted with natural rubber and synthetic rubber.

[Problem that the invention seeks to solve]

However, the natural rubber and synthetic rubber-based high hardness rubbers obtained by this method are currently unsatisfactory in that the shape upon crosslinking is limited to a flat sheet shape.

[Means for solving problems]

The present invention comprises (A) a block copolymer of an aromatic vinyl compound and a conjugated diolefin, and/or 40 to 100% by weight of an ethylene-vinyl acetate copolymer, and (B) natural rubber, diene-based synthetic rubber, and non-alcoholic rubber. A mixture consisting of 0 to 60% by weight of one or more unvulcanized rubbers selected from diene synthetic rubbers [(A)+
(B)] 100 parts by weight, (C) 0 to 100 parts by weight of a rubber softener (D) O to 600 parts by weight of a filler, and the composition is crosslinked in a heat medium. It provides a crosslinked product.

The aromatic vinyl/L/compound-conjugated diene block copolymer of component (A) used in the present invention is a polymer block of at least one aromatic vinyl compound and at least one conjugated diene compound. block, and may be of a linear type or a radial type.

Further, the conjugated diene block may be a random copolymer with a small amount of an aromatic vinyl compound.

It may also be a so-called tapered block in which the aromatic vinyl compound content gradually increases.

There are no particular restrictions on the structure of the block copolymer;
(A-B) n-type, (A-B) n-A type or (A, B)
Any of the n-C types can be used. In the formula, A is a polymer block of an aromatic vinyl compound, B is a conjugated diene polymer block, C is a coupling agent residue, and n represents an integer of 1 or more. Of course, in the above block copolymer, it is also possible to use a block copolymer in which the conjugated diene portion is hydrogenated.

Examples of the aromatic vinyl compound of the aromatic vinyl compound-conjugated diene block copolymer used in the present invention include styrene, α-methylstyrene, 〇-methylstyrene, m-methylstyrene, p-methylstyrene, or vinylnaphthalene. are used, with styrene being particularly preferred. Also, as the conjugated diene, 1,3-butadiene, isoprene, piperylene, etc. are used, and among these, 1,3-butadiene and isoprene are particularly preferred.

The weight average molecular weight of the block copolymer is ・10000~5
ooooo is preferable, more preferably 50,000 to 5
It is 00000. The content of the aromatic vinyl compound in the block copolymer is preferably 5 to 60% by weight, more preferably 20 to 50% by weight.

In order to obtain appropriate hardness and shape followability during crosslinking, the ethylene-vinyl acetate copolymer (EVA) (A) preferably has a vinyl acetate binding metal content of 5 to 45%, more preferably 10 to 30%. %, melt flow index (190℃
, 2160g) is preferably 0.2 to 50 g/10
m1n, more preferably 0.5-20 g/10m1
It is n.

(A) A block copolymer of an aromatic vinyl compound and a conjugated diolefin and/or an ethylene vinyl acetate copolymer has a weight of 100 to 40 in order to obtain a suitable hardness and excellent shape followability during crosslinking. Used in a range of %. Preferably it is 100-70%. If the weight of (A) is less than 40 weight, shape followability deteriorates, which is not preferable.

The unvulcanized rubber which is component (B) of the present invention is used in an amount of 0 to 60% by weight, preferably 0 to 30% by weight, in order to improve kneading processability and adjust hardness. Representative examples include natural rubber (NR) and polyisoprene rubber (I).
R), styrene-butadiene rubber (SBR), polybutadiene rubber (BR), 1,2-polybutadiene, acrylonitrile rubber (NBR), chloroprene rubber (CR)
) and other diene-based synthetic rubbers, ethylene-propylene rubber (EPR), acrylic rubbers (ACM, ANM),
Examples include non-diene synthetic rubber such as fluororubber. Among these, preferred are NRlIR, SBR, BRll
.

2-polybutadiene.

Furthermore, when 1,2-polybutadiene is used for crosslinking with an organic peroxide, the amount of organic peroxide can be reduced because 1,2-polybutadiene has excellent reactivity.

The rubber softener as component (C) used in the present invention is a mineral oil-based rubber softener generally called process oil or extender oil, and is a mixture of aromatic rings, naphthenic rings, and paraffin rings. Preferably, those in which the number of carbon atoms in the paraffin chain accounts for 50% or more of the total carbon atoms are called paraffin series, and those in which the number of carbon atoms in the naphthene ring is 30
~45% are phthenic, and the number of aromatic carbons is 30
% of the components of the present invention (C
) The mineral oil-based rubber softener used as component (A)
In terms of compatibility with the above-mentioned group, naphthenic and aromatic compounds are preferred.

The blending amount of the softener of component (C) is component [(A) + (B) 3
0 to 100 parts by weight, preferably 5 parts by weight per 100 parts by weight
~30 parts by weight.

If the amount is 100 parts by weight or more, it will be difficult to obtain a crosslinked product with high hardness, and the kneading processability will be poor.

Examples of the filler component (D) used in the present invention include light calcium carbonate, heavy calcium carbonate, and various surface-treated calcium carbonates.

Talc, magnesium hydroxide, mica, clay.

Barium sulfate, natural silicic acid, synthetic silicic acid, titanium oxide,
Glass fibers, carbon fibers, cotton flock and various carbon blacks can be used. Among these fillers, heavy calcium carbonate, light calcium carbonate, and talc are economically advantageous and preferred.

The blending amount of the filler is 0 to 600 parts by weight, preferably up to 400 parts by weight, based on 100 parts by weight of components [(A)+(B)]. When the composition exceeds 600 Jukeibu, the kneading processability is poor and the mechanical strength of the obtained crosslinked product is significantly reduced.

In producing the crosslinked product of the present invention, the above (A
Although the compositions of ) to (D) may be irradiated with radiation such as ultraviolet rays or X-rays, it is preferable to incorporate sulfur or an organic peroxide.

The hardness of the compositions (A) to (D) above before crosslinking is:
The JIS-A hardness is preferably 40 to 95, more preferably 42 to 90.

In the present invention, there is no particular restriction on the amount of crosslinking agents such as sulfur and organic peroxides, but by increasing the amount of these crosslinking agents, high hardness (e.g. JIS K-6301,
It is possible to produce a crosslinked product with a hardness of 55 or higher on a JIS-C type hardness meter.

The preferred hardness of the crosslinked product of the present invention is JIS K2SO3
55 or more, more preferably 65 on the JIS-C type hardness tester.
That's all.

By making such a highly hard crosslinked product, it can be effectively used in various linings, industrial products, various vibration damping materials, steel plate reinforcing materials, and alternative uses for thermosetting resins that require high hardness.

In the case of sulfur crosslinking, powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, etc. can be used. The blending amount of sulfur is 0.1 to 100 parts by weight based on 100 parts of component [(A) + (B)], but in order to obtain a crosslinked product with high hardness, 5 to 100 parts by weight is required. It is preferably 15 to 100 parts by weight, particularly preferably 20 to 60 parts by weight. If the amount of sulfur is small, a crosslinked product with high hardness cannot be obtained (ebonite formation is not performed sufficiently), and if it is more than 100 parts by weight, phenomena such as deformation and destruction of the crosslinked product may occur due to the reaction heat during crosslinking. Becomes large.

In the case of sulfur crosslinking, it is preferable to add various vulcanization accelerators at the same time for crosslinking.

Specific examples of the vulcanization accelerator include tetramethylthiuram disulfide (TMTD), tetramethylthiuram monosulfide (TMTM), N-oxydiethylene-2-benzothiazolyl sulfenamide (OBS), and N-cyclohexyl-2-benzothiazyl.・Sulfenamide (CBS), dibenzothiazyl disulfide (MBTS)
), 2-mercaptobenzothiazole (MBT), zinc di-n-butyldithiocarbamate (ZnBDC)
, zinc dimethyl dithiocarbamate (ZnMDC), and the like.

In the case of organic peroxide crosslinking, dicumyl peroxide, di-t-butylperoxy-3゜3.5-trimethylcyclohexane, α,α'-di-t-butylperoxydi-p-diisopropylbenzene, n- Butyl-4,4-
Bis-t-butylperoxyvalerate, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2°5-di(t
-butylperoxy)hexane, etc. can be used. The amount of organic peroxide blended is 0.1 to 15 parts by weight per 100 parts by weight of components [(A) + (B)], but in order to obtain a highly hard crosslinked product, it is 0.5 to 15 parts by weight. 15 parts by weight is preferred, more preferably 2 to 15 parts by weight, particularly preferably 4 to 10 parts by weight.
Parts by weight. If the amount of organic peroxide is small, a crosslinked product with high hardness cannot be obtained, and if it is more than 15 parts by weight, deformation occurs during crosslinking.
There is a high possibility that phenomena such as destruction will occur.

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

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

Furthermore, in addition to the above-mentioned additives, various additives such as activators, anti-aging agents, processing aids, etc. may be appropriately added to both the sulfur crosslinking compound and the peroxide crosslinking compound, if necessary.

There is no particular restriction on the method of mixing the above (A) to (D) and other compounding agents, and a Banbury type mixer, a pressure kneader, etc.
This is possible using open roll mixing methods, which are commonly used for rubber compounds. The uncrosslinked compound thus obtained is formed into, for example, a sheet shape using a calender roll, an extruder, etc., and then subjected to crosslinking in a heat medium. As the heat medium, hot air, hot gas such as hot nitrogen, hot fluid such as hot liquid paraffin, hot fine particles such as fine glass beads, etc. can be used, but among these, hot gas, especially hot air is preferable. . Heating can also be done using microwaves. Crosslinking temperature is 120-250℃,
Crosslinking is preferably carried out by heating in a heating medium in the range of 140 to 180°C. At this time, there is no particular need to apply pressure, and crosslinking can be carried out under atmospheric pressure. During this crosslinking, the wooden mold,
By creating the desired shape with a clay mold, metal mold, etc., and placing an uncrosslinked sheet on top of the mold, the uncrosslinked sheet softens due to heat and follows the surface shape of the mold, forming the desired shape. It is possible to make it into a shape.

Furthermore, by using an adhesive, a pressure-sensitive adhesive, or the like during crosslinking, it is possible to firmly crosslink and bond the mold to the mold.

The crosslinked product according to the present invention has good shape followability despite crosslinking with a heat medium under atmospheric pressure, and does not particularly require a high-hardness press equipment. supplies.

It can be widely used as a restraining layer for various vibration damping materials, as a reinforcing material for steel plates, and as a substitute for other thermosetting resins.

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

In addition, in the Examples and Comparative Examples, the sag test was conducted at 80X.
An uncrosslinked rubber sheet was placed on a 1-inch-thick iron plate with a 40-inch rectangular hole and heated, and the deformation distance that the sheet fell into the hole when it was cross-linked was measured. Further, the hardness was measured using a type A and type C hardness meter of JIS K-6301.

Bending strength was measured by a method based on JIS K-7203. The maximum deformation represented the deformation distance until the crosslinked sheet broke during bending strength measurement.

The properties of the aromatic vinyl compound-conjugated diene block copolymer (hereinafter referred to as block copolymer) and EVA used in the examples are as follows.

Example 1.2.3.4.5 This is an example of sulfur crosslinking, in which the nine aromatic vinyl compound-conjugated diene block copolymers ■ to ■ and other compounding agents were mixed in the proportions shown in Table 1. It was mixed using a BR type Banbury mixer and rolled to a thickness of 2I using a 10-inch test roll machine. The uncrosslinked sheet sheeted in No. 11 was crosslinked in a heat medium at 155° C. for 25 minutes. The physical property test results are shown in Table 1.

Example 6.8 This is an example of peroxide crosslinking formulation, in which aromatic vinyl compound-conjugated diene block copolymers ■~◎ and ethylene vinyl acetate copolymers ■~■ were used as fillers with heavy carbonic acid. A crosslinked product was obtained in the same manner as in Example 1 except that calcium or talc was used. Table 2 shows the physical property test results.
-3.

Example 7.9 This is also an example of peroxide crosslinking, and 80 parts by weight of aromatic vinyl compound-conjugated diene block copolymer or ethylene-vinyl acetate copolymer ■~■ and SBR (JSR15
02) A crosslinked product was obtained in the same manner as in Example 1 using 20 parts by weight. The physical property test results are shown in Table 2.3.

Comparative Example 1.2 This is a comparative example of sulfur crosslinking formulation, and the polymer used was S.
A crosslinked product was obtained in the same manner as in Example 1, except that 100 parts by weight of BR (JSR1502, manufactured by Japan Synthetic Rubber ■) or natural rubber was used. The physical property test results are shown in Table 1.

Comparative Example 3.4 This is a comparative example of peroxide crosslinking formulation, in which the polymer used was SBR (manufactured by JSR1502 Japan Synthetic Rubber ■), the filler was changed to heavy calcium carbonate or talc, and the composition was the same as in Example 1. A crosslinked product was obtained in the same manner. The physical property test results are shown in Table 2.

Tables 1, 2, and 3 show that Examples 1 to 9, which are compositions according to the present invention, have less sag despite having higher hardness than Comparative Examples 1 to 4, which are outside the scope of the present invention. It turns out it's big. This indicates that when the uncrosslinked sheet according to the present invention is placed on an uneven plate-like material and cross-linked during cross-linking, the shape followability of the plate-like material is extremely good.

〔Effect of the invention〕

The composition of the present invention does not particularly require a mold during crosslinking, and has good shape followability even when crosslinked with a heat medium, so it is possible to obtain a crosslinked product in the desired shape, and at the same time, the crosslinked product has high hardness. Because it can be obtained, it can be widely used in various linings, industrial products, restraining layers for various vibration damping materials, steel plate reinforcement materials, and as a replacement for geothermally curable resins.

Claims (2)

[Claims] (1) (A) block copolymer of aromatic vinyl compound and conjugated diolefin and/or 40 to 100% by weight of ethylene-vinyl acetate copolymer and (B) natural rubber, diene-based synthetic rubber and (C) 0 to 100 parts by weight of a rubber softener to 100 parts by weight of a mixture [(A) + (B)] consisting of 0 to 60% by weight of one or more types of unvulcanized rubber selected from diene synthetic rubbers. Part (D) A crosslinked polymer product obtained by crosslinking a composition containing 0 to 600 parts by weight of a filler in a heat medium. (2) The crosslinked polymer according to claim (1), wherein the crosslinked polymer has a hardness of 55 or more on a JIS C type hardness tester of JIS K-6301.