JPH0873682A - Crosslinked butyl rubber composition - Google Patents

Abstract

PURPOSE: To obtain a new composition having excellent rubber elasticity in a wide temperature range, moldability, processability, resistance to change in color and toning properties by blending butyl rubber with an organic organosiloxane-based crosslinking agent and a hydrosilylating catalyst and dynamically cross-linking. CONSTITUTION: This composition is obtained by blending (A) 100 pts.wt. of butyl rubber preferably prepared by bonding divinylbenzene to a copolymer of isoprene rubber and isobutylene rubber with (B) 0.5-30 pts.wt. of an organic organosiloxane-based crosslinking agent containing plural SiH groups in the molecule and (C) 0.001-20 pts.wt. of a hydrosilylating catalyst composed of preferably a heavy metal-based catalyst and/or a peroxide-based catalyst and dynamically crosslinking. When the component C is dissolved in a solvent or supported on a solid component such as silica, preferably it is highly dispersed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel crosslinked butyl rubber composition. More specifically, it has excellent rubber elasticity and molding processability over a wide temperature range, good light discoloration resistance, very good toning property, and excellent biocompatibility. It is also a material for various molded products including food and medical applications. The present invention relates to a novel crosslinked butyl rubber composition that can be used as

[0002]

BACKGROUND OF THE INVENTION Butyl rubber is a rubber that has a number of excellent properties such as low unsaturation, physiologically inertness, hydrophobicity, acid resistance, alkali resistance, weather resistance, and low gas permeability. Used in adhesives, adhesives, sealing materials, medical rubber stoppers, etc. In practical use, it is necessary to lose the plasticity of butyl rubber to improve the tensile strength, tear strength and elasticity, and to reduce the thermal change and wear of the rubber. Crosslink with the agent. Examples of the crosslinking agent include sulfur-based (including accelerator) crosslinking agents, peroxide-based crosslinking agents, resin-based crosslinking agents, oxime-based crosslinking agents, metal oxide-based crosslinking agents, amine-based crosslinking agents, ionic-based crosslinking agents, etc. Among these, sulfur-based crosslinking agents and peroxide-based crosslinking agents are common. Sulfur-based cross-linking agents are the most common, but butyl rubber is a sulfur- and organic-sulfur-containing cross-linking agent, and cross-linking accelerators have a slow cross-linking rate and a large amount of cross-linking agents,
A cross-linking accelerator must be used, resulting in a long cross-linking time and poor workability due to the rubber's tackiness even after cross-linking. There is a problem that the appearance and aging resistance of the product are deteriorated. Furthermore, there is no degree of freedom in coloring, and it is difficult to use it for food applications and medical applications that require biocompatibility. On the other hand, peroxide crosslinking agents are used as a method for crosslinking saturated rubber that cannot be sulfur-crosslinked, and are intended to improve mechanical properties, heat resistance, and electrical properties. This crosslinking method is extremely hygienic and can be used for food applications. However, since it is partially crosslinked, its shape recovery property at high temperature is insufficient, and since it uses an organic peroxide, in the case of butyl rubber, the radicals caused by the organic peroxide are simultaneously generated when the butyl rubber is crosslinked. Due to this, the polymer main chain is cleaved and the mechanical strength is also reduced, which is also a drawback. From the above, according to the prior art, rubber elasticity over a wide temperature range, excellent moldability, good light discoloration resistance and very good toning property, further excellent in biocompatibility, various food applications, medical applications, etc. At present, a crosslinked butyl rubber composition that can be used as a material for molded articles has not been obtained.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems that were difficult with the conventional cross-linked butyl rubber composition, and maintains good rubber properties over a wide temperature range while achieving wide coloring. Since it has characteristics such as flexibility and low residue concentration, it can be used for a wide variety of applications including those requiring toning, hygiene, and long-term reliability. The present invention relates to a crosslinked butyl rubber composition.

[0004]

[Means for Solving the Problems] As a result of searching a compound having excellent heat resistance, photochromic resistance and biocompatibility as a cross-linking agent and having a property of selectively cross-linking butyl rubber, as a result, two or more SiH groups are present in the molecule. The organoorganosiloxane compound possesses the above-mentioned purpose, and by cross-linking the butyl rubber with a hydrosilylation catalyst in order to cause a crosslinking reaction at a practical reaction rate, applications requiring color matching, hygiene, and long-term It has been found that it can be used in a wide variety of applications including those requiring reliability. As a result of further development of various researches, we have found that while having good rubber properties over a wide temperature range, it can be applied to a wide range of various applications including those requiring toning and good molding appearance. The present invention has been completed, and based on the findings, further researches have been conducted to complete the present invention. That is, the present invention is obtained by dynamically adding butyl rubber (a) with an organic organosiloxane-based cross-linking agent (b) having two or more SiH groups in the molecule and a hydrosilylation catalyst (c) to dynamically cross-link it. And a crosslinked butyl rubber composition.

The butyl rubber (a) used in the present invention is not particularly limited and is generally commercially available. It is an unsaturated rubber (IIR) obtained by copolymerizing isobutylene and a small amount of isoprene. Examples of the butyl rubber include halogenated butyl rubber such as chlorinated butyl rubber and brominated butyl rubber, and those bonded with a vinyl aromatic compound in order to accelerate the crosslinking rate. Among these, a butyl rubber obtained by copolymerizing isobutylene and a small amount of isoprene and having divinylbenzene bonded (DVIIR) is more preferably used.

Next, the crosslinking agent (b) for butyl rubber used in the present invention is an organic organosiloxane compound having two or more SiH groups. This crosslinking method utilizes a selective addition reaction (hydrosilylation) of an SiH group to an unsaturated hydrocarbon in a butyl rubber component. In order to be a cross-linking agent, addition to two or more molecules of rubber is a necessary condition, so it is necessary to have two or more SiH groups in the molecule. Typical examples of specific compounds are compounds having structures of cyclic polysiloxanes, linear polysiloxanes, and tetrahedral siloxanes as shown below. Moreover, you may use the compound and / or polymer derived from this compound.

[0007] (M is an integer of 3 to 30, n is an integer of 0 to 200,
R is hydrogen, an alkyl group, an alkoxy group, an aryl group or an aryloxy group, and at least one R bonded to a silicon atom is hydrogen, and two or more silicon atoms are present in the molecule. is there. ) The organic organosiloxane having the above structure can selectively crosslink butyl rubber.

The crosslinking reaction catalyst (c) used in the present invention refers to all catalysts that accelerate the hydrosilylation reaction. Examples of the catalyst include group transition metals such as palladium, rhodium and platinum, or compounds and complexes thereof.
Further, peroxides, amines and phosphines are also used. The most common catalysts include dicuclobis (acetonitrile) palladium (II), chlorotris (triphenylphosphine) rhodium (I), chloroplatinic acid and the like. An organic peroxide catalyst can be preferably used as the crosslinking reaction catalyst (c) used in the present invention. An example of organic peroxide is 2,5-dimethyl 2,5-di (t
-Butylperoxy) hexane, 2,5 dimethyl 2,5
-Di (t-butylperoxy) hexyne-3,1,3-
Bis (t-butylperoxyisopropyl) benzene,
1,1-di (t-butylperoxy) 3,5,5 trimethylcyclohexane, 2,5 dimethyl 2,5 di (peroxybenzoyl) hexyne 3, and dicumyl peroxide. Furthermore, a system in which an organic peroxide is used in combination with a co-catalyst bismaleimide compound may be used as a catalyst.
The bismaleimide compound used in the present invention includes N, N'-
Examples include m-phenylene bismaleimide and toluylene bismaleimide. As N, N'-m-phenylene bismaleimide, commercially available products such as HVA-2 (manufactured by DuPont) and Succinol BM (manufactured by Sumitomo Chemical Co., Ltd.) can be used. The temperature at which the catalyst performance of the peroxide-based catalyst develops can be freely controlled between 100 ° C and 250 ° C by examining the catalyst species. That is, by performing the raw material dispersion step and the molding step at a temperature at which the catalyst activity is exhibited or lower, and the crosslinking step at a temperature at which the catalyst ability is exhibited or higher, molding can be carried out in the same manner as in ordinary crosslinked rubber. The cured rubber composition obtained by using this peroxide catalyst can be suitably used in applications where residual heavy metals pose a problem-for example, in the medical field.

In order to disperse the catalyst in a higher degree, the hydrosilylation catalyst (c) can be dissolved or supported in one or more solvents selected from liquid components and solid components. That is, it is a method of dissolving it in a solvent, supporting it on an inorganic filler, or a combination of both. The solvent used here is not particularly limited, but needs to be relatively inert to the hydrosilylation reaction. Examples of the solvent type include hydrocarbon type, alcohol type, ketone type, ester type and the like. The concentration of the solution to be prepared is not particularly limited. Further, the inorganic filler is required to have adsorption ability, and examples thereof include calcium carbonate, carbon black, talc, magnesium hydroxide, mica, barium sulfate, natural silicic acid, synthetic silicic acid (white carbon), titanium oxide and the like. . A known method can be used to prepare the supported catalyst.

In order to obtain the crosslinked butyl rubber composition, the compounding amount of the organic organosiloxane crosslinking agent b is 100 g of the component a100.
0.5 to 30 parts by weight, preferably 1 to 2 parts by weight
It can be suitably selected from 0 parts by weight and its gel content can be adjusted. Here, the gel content means that 1 g of a butyl rubber composition is refluxed for 10 hours with a Soxhlet extractor using boiling xylene, the residue is filtered through a wire mesh of 80 mesh, and the dry weight (g) of the insoluble matter remaining on the mesh It is determined by multiplying the weight ratio of the component a contained in 1 g of butyl rubber composition by 100 times, and the gel content of the crosslinked butyl rubber composition is at least 80%, preferably 90% or more (however, the content of the inorganic filler, etc. The insoluble component is not included in this) and is crosslinked. The amount of catalyst c added is 0.00 with respect to 100 parts by weight of the rubber component.
1 to 20 parts by weight of catalyst can be optionally added.
The addition amount of the heavy metal catalyst as a catalyst is preferably 0.005 to 5 parts by weight, more preferably 0.01 to 2 parts by weight. In addition, the addition amount of peroxide catalyst is 0.01
It is preferably from 15 parts by weight to 15 parts by weight, more preferably from 0.
It is 1 to 10 parts by weight. When the amount is less than 0.001 part by weight, the crosslinking does not proceed at a practical speed. Further, if it exceeds 20 parts by weight, not only is there no effect of increasing the amount, but also the deactivated catalyst becomes black-colored lumps and the appearance is poor, and heat treatment tends to cause undesirable side reactions (decomposition of unreacted SiH groups, etc.). is there.

In addition to the above components, the crosslinked butyl rubber composition of the present invention may further contain a process oil, a thermoplastic elastomer and an inorganic filler, if necessary. This inorganic filler has not only the advantage of reducing the product cost as an extender but also an advantage of imparting a positive effect to quality improvement (heat-resistant shape retention, flame retardancy impartation, etc.). Examples of the inorganic filler include calcium carbonate, carbon black, talc, magnesium hydroxide, mica, barium sulfate, natural silicic acid, synthetic silicic acid (white carbon), titanium oxide, etc., and carbon black includes channel black, Furnace black etc. can be used. Among these inorganic fillers, talc and calcium carbonate are economically advantageous and preferable. Further, if necessary, an external lubricant, an internal lubricant, a hindered amine-based light stabilizer, a hindered phenol-based antioxidant, a colorant, silicone oil and the like may be added.

The method for producing a crosslinked butyl rubber composition using the above-mentioned components (a), (b) and (c) is not particularly limited, and an ordinary thermosetting resin composition or thermosetting rubber composition is used. All common methods used for the manufacture of Basically, it is a mechanical melt-kneading method, and a single-screw extruder, a twin-screw extruder, a Banbury mixer, various kneaders, brabenders, rolls and the like are used for these. Also,
At this time, the temperature for melt-kneading is usually 50 ° C to 220 ° C, preferably 100 ° C to 200 ° C, and the shear rate is 100 to 100.
It can be suitably selected from 0 [1 / sec]. The partially cross-linked butyl rubber composition thus obtained is thermosetting and can be molded using a commonly used thermosetting resin molding machine, such as injection molding, compression molding and transfer molding. Various molding methods can be applied. After molding, the partially cross-linked butyl rubber composition is subjected to a cross-linking treatment, whereby unreacted cross-linking points react and a completely cross-linked butyl rubber product can be obtained. Here, the crosslinking conditions are 100 to 2 under a pressure of 50 to 200 kg / cm 2.
After performing primary crosslinking for several minutes to several hours at 00 ° C., if necessary, secondary crosslinking is performed for one hour to several hours at 100 to 200 ° C. The crosslinked butyl rubber composition thus obtained,
It has excellent rubber elasticity and light resistance to discoloration, is extremely excellent in toning property, and is also excellent in biocompatibility.

[0013]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The components blended in the examples and comparative examples shown below are as follows. <Ingredient a (1)> Polysar But made by Polycer
yl XL-20 (DVIIR) <Component a (2)> Butyl rubber JSR I made by Japan Synthetic Rubber
IR 268 [unsaturation: 1.5 mol% Mooney viscosity ML
1 + 4 (125 ° C): 51] <Component b (1)> Toray Dow Corning Silicone Co., Ltd. 1,3,5,7-tetramethylcyclotetrasiloxane <Component b (2)> Toray Dow Corning・ 1,1,3,3-Tetramethylditetrasiloxane manufactured by Silicone Co., Ltd. <Component c (1)> Chloroplatinic acid hexahydrate manufactured by Yasuda Pharmaceutical Co., Ltd. <Component c (2)> Dicumyl peroxide Park mill manufactured by NOF CORPORATION D <Component c (3)> A 1 wt% 2-propanol solution of the component c (1) was prepared, and 1 g of this solution was loaded on 100 g of silica (Nipsil VN3 manufactured by Nippon Silica).

<< Examples 1 to 12 and Comparative Examples 1 to 6 >>
After sufficiently dry-blending the components a, b, and c, they were melt-kneaded using a kneader under conditions such that the resin temperature was 100 to 150 ° C. This melt-kneaded product is changed to a roll and thinly squeezed, and then the mixture is pressed at 160 ° C. for 10 minutes with a cross-linking molding press.
Compression molding was performed for a minute. The following physical properties were evaluated, and the examples are listed in Tables 1 and 2, and the comparative examples are shown in Table 3.
I put it on. (1) Hardness (JIS K6301 A type) (2) Tensile strength TS [MPa] and elongation Eb [%] (JI
SK6301, No.3 dumbbell) (3) Compression set CS [%] (JIS K6301, 2
5% compression 70 ° C. × 22 Hr) (4) Light discoloration resistance test (a natural composition was measured using a sunshine weatherometer at 88 ° C. × 1000 h
r processing was performed and the color difference was measured. (5) Hygiene test (Test was carried out in accordance with the Japanese Pharmacopoeia 10th revised rubber stopper test method for infusions and the plastic container test method for infusions. Poor was designated as ×, and ○ was designated as acceptable. )

Table 1 Example 1 2 3 4 5 6 Composition (parts by weight) Component a (1) 100 100 100 100 100 100 100 Component b (1) 5 3 7 Component b (2) 5 3 7 Component c (1) 0.5 0 .5 component c (2) 0.2 0.2 component c (3) 10 10 physical property hardness 84 82 85 83 83 86 85 TS (MPa) 29 30 28 28 32 32 31 Eb (%) 470 460 485 475 460 490 CS ( %) 32 33 35 36 30 30 29 Light discoloration resistance 10 9 9 10 9 9 Hygiene test ○ ○ ○ ○ ○ ○ ○

Table 2 Example 7 8 9 10 11 12 Composition (parts by weight) Component a (2) 100 100 100 100 100 100 100 Component b (1) 5 3 7 Component b (2) 5 3 7 Component c (1) 0.5 0 .5 Component c (2) 0.2 0.2 Component c (3) 10 10 Physical Properties Hardness 81 78 78 80 79 84 83 TS (MPa) 25 26 24 24 23 29 29 Eb (%) 520 495 525 510 510 505 515 CS ( %) 37 39 39 41 33 34 Photochromic resistance 8 7 8 8 9 8 Hygienic test ○ ○ ○ ○ ○ ○

Table 3 Comparative Example 1 2 3 4 5 6 Composition (parts by weight) Component a (1) 100 100 100 Component a (2) 100 100 100 Component b (1) 50 3 Component b (2) 0.3 Component c (1) 0.5 Component c (2) 0.2 10 Component c (3) 30 Sulfur-based cross-linking agent 5 Alkylphenol resin 10 Physical properties Hardness 85 73 73 78 59 84 83 TS (MPa) 21 22 22 21 13 13 22 20 Eb (% ) 280 675 225 210 405 320 320 CS (%) 33 55 55 29 78 49 48 48 Light discoloration resistance 16 7 12 18 24 30 Hygiene test × ○ △ × × × In addition, the sulfur-based cross-linking agent in Comparative Examples is zinc oxide. 5 parts by weight,
It is a cross-linking agent master consisting of 1 part by weight of tetraethyl thiuram disulfide, 0.5 part by weight of 2-bis (benzothiazolyl) disulfide and 1.5 part by weight of sulfur. The alkylphenol resin is SP1045 manufactured by Schenectady Chemicals.

[0018]

EFFECTS OF THE INVENTION The crosslinked butyl rubber composition of the present invention is characterized by excellent rubber elasticity over a wide temperature range, moldability, light discoloration resistance, excellent toning property and excellent biocompatibility. Suitable for applications and medical applications.

Claims (5)

[Claims] 1. Obtained by dynamically cross-linking butyl rubber (a) with an organic organosiloxane cross-linking agent (b) having two or more SiH groups in the molecule and a hydrosilylation catalyst (c). Crosslinked butyl rubber composition. 2. The crosslinked butyl rubber composition according to claim 1, wherein the butyl rubber (a) is a rubber obtained by binding divinylbenzene to a copolymer of isoprene rubber and isobutylene rubber. 3. The organic organosiloxane cross-linking agent (b) is added in an amount of 0.5 to 100 parts by weight of butyl rubber (a).
30 parts by weight, 0.001 of hydrosilylation catalyst (c)
The amount of the crosslinked butyl rubber composition according to claim 1 or 2 is about 20 parts by weight. 4. The crosslinked butyl rubber composition according to claim 1, wherein the hydrosilylation catalyst (c) is a heavy metal catalyst and / or a peroxide catalyst. 5. The crosslinked butyl rubber composition according to claim 1, 2, 3 or 4, wherein the hydrosilylation catalyst (c) is dissolved or supported in one or more solvents selected from liquid components or solid components. Stuff.