JPH04366148A - Thermoplastic elastomer composition - Google Patents

Abstract

PURPOSE:To prepare the title compsn. having characteristics of both an olefin polymer and a siloxane polymer in a good balance by dynamically cross-linking a mixture comprising a polyolefin resin, an olefinic elastomer, and a silicone rubber. CONSTITUTION:The title compsn. is prepd. by dynamically cross-linking a mixture comprising 100 pts.wt. the sum of 1-99wt.% polyolefin resin and 99-1wt.% olefinic elastomer and 1-300 pts.wt. silicone rubber. The dynamic cross-linking is carried out by melt mixing the three polymers with a cross-linking component which can cross-link both the olefinic elastomer and the silicone rubber. The component consisting of an org. peroxide and a cross-linking aid and contg. little contaminants is pref. for the use of the compsn.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides polyolefin resins,
A thermoplastic elastomer composition obtained by melt-mixing a mixture of an olefin elastomer and a silicone rubber in the presence of a component capable of crosslinking both the olefin elastomer and the silicone rubber. The present invention relates to a thermoplastic elastomer composition that has a well-balanced combination of drug properties, silicone rubber surface properties, gas permeability, etc., and is particularly suitable for use in medical and food applications.

0002

[Prior Art] A thermoplastic elastomer that exhibits excellent elastomer performance is produced by dynamically processing a mixture of a polyolefin resin and an olefin elastomer in the presence of a component (crosslinking agent) capable of crosslinking the olefin elastomer. Methods for obtaining are known.

The thermoplastic elastomer containing olefin as a main component is called thermoplastic olefin (TPO) and is widely used industrially. That is, since TPO has an olefin component as its basic skeleton, it has excellent chemical resistance and also has elastomer elasticity, so it is applied to, for example, the gasket part of a medical syringe.

[0004] However, since TPO lacks surface slipperiness, it is necessary to apply silicone oil to the gasket molded product before installation, and elution of the applied silicone oil may pose a problem. Therefore, it is desired to develop a new material that exhibits sufficient slipperiness without the need for applying silicone oil.

On the other hand, silicone rubber has excellent properties such as good slipperiness, mold releasability, easy oxygen permeability, water repellency, and electrical insulation, and is widely used industrially. In particular, since it is a material that is harmless to the human body, it is often used in the hygiene and medical fields.

[0006] However, when silicone rubber is molded, it is usually necessary to perform vulcanization. However, in the rubber vulcanization process, it is generally necessary to follow a complicated compounding recipe and control the vulcanization temperature, which requires skill. Moreover, there is a problem in that it is difficult to recycle defective products.

[0007] Therefore, in the application of silicone rubber, there is a desire for the emergence of a so-called thermoplastic silicone material that does not require a complicated vulcanization process and can be easily molded using an injection molding machine in the same way as ordinary resins. .

[0008] JP-A-2-150441 and JP-A-2
JP-A-55752 discloses a thermoplastic material in which organopolysiloxane is chemically bonded to an ethylene polymer, which exhibits useful performance as a thermoplastic silicone material.

However, these thermoplastic silicone materials have the disadvantage that they have poor heat resistance and are limited in use because the partner to which the silicone component is bonded is an ethylene polymer, and their performance as elastomers is insufficient. Not considered.

0010

[Problems to be Solved by the Invention] The present invention has been made against the background of the above-mentioned conventional technical problems, and it is possible to create an olefin polymer by highly complexing a polyolefin resin, an olefin elastomer, and a silicone rubber. The object of the present invention is to provide a thermoplastic elastomer composition that has a well-balanced combination of the characteristics of siloxane-based polymers and siloxane-based polymers.

[0011]

[Means for Solving the Problems] The present invention provides that (c) silicone The present invention provides a thermoplastic elastomer composition obtained by dynamically crosslinking a composition containing 1 to 300 parts by weight of rubber.

Specific examples of the polyolefin resin (a) include homo- and random block (co)polymers such as propylene, ethylene, methylpentene, and butene-1, which may be used alone or in combination. However, polypropylene alone, a random or block copolymer containing propylene as a main component, or polymethylpentene is preferred.

Also preferably used are modified polypropylene resins obtained by grafting compounds having functional groups such as acid anhydride groups, carboxyl groups, epoxy groups, and hydroxyl groups onto these polymers.

The above olefin elastomer (b) is
Preferably, it is an elastic polymer whose main constituent is an α-monoolefin having 2 to 8 carbon atoms. Specific examples include ethylene-propylene-(diene) copolymer rubber, ethylene-butene-(diene) copolymer rubber, chlorinated polyethylene, chlorosulfonated polyethylene, and conjugated diene-based (
Examples include hydrogenated products of co-)polymer rubber.

The hydrogenated product of the conjugated diene-based (co)polymer rubber mentioned above is a conjugated diene having 4 to 12 carbon atoms, such as 1,3
-butadiene, isoprene, 2,3-dimethyl-1,3
-butadiene, 1,3-pentadiene, 2-methyl-1
, 3-pentadiene, 1,3-hexadiene, 4,5-
diethyl-1,3-octadiene, 3-butyl-1,3
- A polymer in which 80% or more of the residual unsaturated bonds of a homopolymer, random copolymer, block polymer, or graft polymer containing octadiene, chloroprene, etc. as a main component are hydrogenated.

Specifically, hydrogenated products of aromatic vinyl compound-conjugated diene copolymer, hydrogenated product of aromatic vinyl compound-conjugated diene block polymer, α,β-unsaturated nitrile-conjugated diene copolymer Hydrogenated rubber, hydrogenated acrylic acid ester-conjugated diene copolymer rubber, α,
Examples include hydrogenated products of β-unsaturated nitrile-acrylic acid ester-conjugated diene copolymer rubber, hydrogenated products of conjugated diene block polymers, and hydrogenated products of conjugated diene stereoblock polymers.

Examples of the aromatic vinyl compounds include styrene, t-butylstyrene, α-methylstyrene, P-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-P-aminoethylstyrene, N,N-diethyl-P-aminoethylstyrene, vinylpyridine, etc., especially styrene and α-
Methylstyrene is preferred.

[0018] Examples of the α,β-unsaturated nitrile include acrylonitrile, methacrylonitrile, etc.
Acrylonitrile is particularly preferred. Examples of the acrylic ester include methyl acrylate, ethyl acrylate, butyl acrylate, and ethyl acrylate and butyl acrylate are particularly preferred.

The content of the aromatic vinyl compound in the conjugated diene (co)polymer rubber is usually 1 to 80% by weight, preferably 2 to 70% by weight, particularly preferably 5 to 60% by weight.
It is. Aromatic vinyl compounds have the effect of reducing the adhesion of hydrogenated rubber and improving production processability, but 1
If the amount is less than 80% by weight, the effect is poor, and if it is used in excess of 80% by weight, the glass transition temperature of the hydrogenated rubber increases and the elasticity of the elastomer is significantly impaired.

The above α,β-unsaturated nitriles, acrylic esters, and the like are used for the purpose of introducing polar groups into hydrogenated rubber and improving oil resistance. Its content is usually 1 to 60% by weight, preferably 2 to 50% by weight,
Particularly preferred is 5 to 40% by weight. If it is less than 1% by weight, no effect can be expected from the copolymerization, and if it exceeds 60% by weight, problems such as a decrease in elastomer elasticity and an increase in surface tackiness will occur, depending on the properties of the compound used. Become.

The above-mentioned conjugated diene (co)polymer can be obtained, for example, by anionic living polymerization in a hydrocarbon solvent using an organolithium initiator. Also, at the end of polymerization, 2
The coupling reaction may be carried out by adding a required amount of a functional or more functional coupling agent.

As the organolithium initiator, n-butyllithium, sec-butyllithium, tert-butyllithium, etc. are used. The hydrocarbon solvents mentioned above include hexane, heptane, methylcyclopentane, cyclohexane, benzene, toluene, xylene,
-Methylbutene-1,2-methylbutene-2, etc. are used.

The polymerization of the above-mentioned conjugated diene (co)polymer may be carried out by a batch method or a continuous method, and the polymerization temperature is usually 0 to 12
Polymerization is carried out at 0°C for a polymerization time of 5 minutes to 12 hours. The monomers may be added all at once or may be added continuously. It is also possible to obtain a block polymer by dividing the polymerization into multiple stages and, after completing the polymerization of each stage, charging the monomer for the next stage and continuing the polymerization.

The above conjugated diene (co)polymer has a terminal modified with a polar group during living anionic polymerization.
Modified with polar groups by polymers or other means (
Co)polymers are also included.

Examples of the polar groups include hydroxyl groups, carboxyl groups, ester groups, isocyanate groups, urethane groups, amide groups, urea groups, thiourethane groups, and acid anhydride groups.

The hydrogenation reaction of the above conjugated diene (co)polymer is usually carried out by dissolving the (co)polymer in a hydrocarbon solvent, at a temperature of 20 to 150°C, and under a pressure of hydrogen of 1 to 100 kg/cm2. , carried out in the presence of a hydrogenation catalyst.

Examples of the hydrogenation catalyst include catalysts in which noble metals such as palladium, ruthenium, rhodium, and platinum are supported on silica, carbon, diatomaceous earth, etc., complex catalysts such as rhodium, ruthenium, and platinum, and organic carbon atoms such as cobalt and nickel. Catalysts consisting of acid and organoaluminum or organolithium, titanium compounds such as dicyclopentadienyl titanium dichloride, dicyclopentadienyl diphenyl titanium, dicyclopentadienyl titanium ditrile, dicyclopentadienyl titanium dibenzyl, and lithium. An organometallic compound catalyst containing aluminum, magnesium, or the like is used.

[0028] The olefin elastomer (b) is
Since it is necessary to have appropriate co-crosslinkability with silicone rubber (c), it is preferable to have an appropriate amount of unsaturated bonds in the molecular structure.

The degree of unsaturation of the elastomer is indicated by the iodine value, and the iodine value of the olefin elastomer (b) is usually 2 to 40, preferably 3 to 30, particularly preferably 5 to 2.
It is 5. If the iodine value of the olefin elastomer (b) is less than 2, the co-crosslinkability with the silicone rubber (c) will not be sufficient, and if it exceeds 40, the weather resistance may deteriorate.

The molecular weight of the olefin elastomer (b) is usually 50,000 to 2,500,000, preferably 60,000 to 2,000,000,
Particularly preferably 100,000 to 1,800,000. If it is less than 50,000, the mechanical strength may be poor, and if it exceeds 2,500,000, the workability may be poor.

The olefinic elastomer (b) may also contain an appropriate amount of a softening agent, such as mineral oil (paraffinic process oil, naphthenic process oil, etc.). In particular, when using a high molecular weight olefin elastomer (b), it is preferable to contain a softener from the viewpoint of improving processability and imparting flexibility.

The silicone rubber (c) preferably has an average compositional formula (I) Ra SiO4-a/2 (I) (
In the formula, R is a substituted or unsubstituted monovalent organic group, and a
represents a number from 1.900 to 2.004. ) and the degree of polymerization is preferably 500 to 50,000.

The molecular structure of the silicone rubber (c) may be chain-like, branched-chain, cyclic, network-like, or three-dimensional network-like. Moreover, these may be homopolymers, copolymers or mixtures thereof.

Examples of the substituted or unsubstituted monovalent organic group include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, and decyl group, and 2-phenylethyl group. , aralkyl groups such as 2-phenylpropyl group, and aryl groups such as phenyl group.

Among these organic groups, methyl groups are preferably used from the viewpoint of heat resistance, weather resistance, cold resistance, etc., and when special properties such as cold resistance or radiation resistance are required, some methyl groups are used. A phenyl group or the like is used.

In addition to the above-mentioned organic groups, the silicone rubber (c) contains a vinyl group, an allyl group, an ethylidene norbornyl group, a methylene norbornyl group, and a dicyclopentenyl group so that it can be easily crosslinked with an organic peroxide or the like. 0.02 to 20 mol%, especially 0.05 to 5 mol% of monovalent aliphatic unsaturated hydrocarbon groups such as cyclooctenyl group, 4-pentenyl group, 4-hexenyl group, etc. based on the above organic group.
It is preferable to include it in a proportion of .

Among these monovalent aliphatic unsaturated hydrocarbon groups, vinyl groups are preferred because they are easy to synthesize and can be easily crosslinked with organic peroxides.

[0038] The content of monovalent aliphatic unsaturated hydrocarbon is 0.
．． If the amount is less than 0.02 mol%, the co-crosslinkability with the olefin elastomer (b) will not be sufficient, and if it exceeds 20 mol%, the heat resistance may decrease.

The molecular terminal of the silicone rubber (c) may be blocked with a triorganosilyl group such as a trimethylsilyl group, a dimethylvinylsilyl group, or a dimethylphenylsilyl group, or a hydroxyl group, a methoxy group, or an ethoxy group bonded to a silicon atom. A group or the like may be present.

The silicone rubber (c) is a polysiloxane obtained by absorbing an alkoxysilane into organic polymer particles dispersed in an aqueous dispersion medium and then proceeding with a condensation reaction of the alkoxysilane. Composite polymer particles are also preferred. The amount of silicone rubber in this silicone rubber (c) is the amount of polysiloxane in the polymer particles.

The amount of each of the above-mentioned components ((a) to (c) components) used in the thermoplastic elastomer composition of the present invention is 1 to 99% by weight of the polyolefin resin (a), preferably 1% by weight.
0 to 90% by weight, particularly preferably 20 to 80% by weight, and 99 to 1% by weight of olefin elastomer (b), preferably 90 to 10% by weight, particularly preferably 80 to 20% by weight, and the total amount is 100 parts by weight. In contrast, silicone rubber (
c) 1 to 300 parts by weight, preferably 2 to 200 parts by weight,
Particularly preferably 5 to 150 parts by weight.

When the polyolefin resin (a) is less than 1% by weight and the olefin elastomer (b) is more than 99% by weight, it is difficult to impart thermoplasticity and processability is extremely poor. In addition, the polyolefin resin (a) is more than 99% by weight, and the olefin elastomer (b) is 1% by weight.
If it is less than that, the mechanical properties are poor.

[0043] Also, the amount of silicone rubber (c) used is 1
If the amount is less than 1 part by weight, no effect of silicone inclusion will be observed. On the other hand, when the amount of silicone rubber (c) used exceeds 300 parts by weight, thermoplasticity decreases and mechanical strength etc. decrease significantly.

The thermoplastic elastomer composition of the present invention comprises:
Obtained by dynamic crosslinking. In the present invention,
“Dynamically crosslinked” refers to polyolefin resin (a),
When melt-mixing the olefin elastomer (b), silicone rubber (c), and other components, add a crosslinking component that can crosslink both the olefin elastomer (b) and silicone rubber (c), It means to knead.

The crosslinking component capable of crosslinking both the olefin elastomer (b) and the silicone rubber (c) above corresponds to a normal rubber vulcanizing agent, and is a sulfur vulcanizing agent that uses sulfur as the main crosslinking agent. There are vulcanized types and types consisting of organic peroxides and crosslinking aids.

[0046] The crosslinking component used in the present invention is as follows:
From the viewpoint of the intended use of the composition, it is desirable that the composition contains few impurities, and a composition consisting of an organic peroxide and a crosslinking aid is preferred.

[0047] The above organic peroxide is preferably one having a 1-minute half-life temperature of 150°C or higher, such as 2,5-di-methyl-2,5-di-benzoyl-peroxyhexane. , n-butyl-4,4-di-t-
Butyl peroxyvalerate, dicumyl peroxide, t-butyl peroxybenzoate, di-t-butylperoxy-di-isopropylbenzene, t-butylcumyl peroxide, 2,5-di-methyl-2,5- Examples include di-t-butylperoxyhexane, di-t-butylperoxide, 2,5-di-methyl-2,5-di-t-butylperoxyhexine-3, and the like.

The amount of the organic peroxide used is usually 0.01 to 5 parts by weight, preferably 0.01 to 5 parts by weight, based on the total of 100 parts by weight of components (b) and (c) in the composition of the present invention. 0
．． 02 to 4 parts by weight, more preferably 0.03 to 3.5 parts by weight
Parts by weight. If it is less than 0.01 part by weight, crosslinking will be insufficient and the mechanical properties and elastomer elasticity will be poor. If more than 5 parts by weight is used, the mechanical properties will deteriorate due to over-crosslinking of the elastomer component and decomposition of the polyolefin resin (a).

When using a crosslinking component having the organic peroxide as the main crosslinking agent, it is preferable to use a radically polymerizable polyfunctional monomer as a crosslinking aid in order to increase the efficiency of the crosslinking reaction. Specific examples of the radically polymerizable polyfunctional monomer include dimaleimide compounds such as N,N'-m-phenylene dimaleimide, divinylbenzene, trimethylolpropane triacrylate, trimethylolpropane methacrylate, pentaerythritol triacrylate, and aluminum. Acrylate, aluminum methacrylate, zinc methacrylate, zinc acrylate, magnesium acrylate, magnesium methacrylate, triallyl isocyanurate, triallyl cyanurate, triallyl trimellitate, diallyl phthalate, diallyl chlorendate, liquid polybutadiene, liquid poly1,2- Examples include butadiene, which may be used alone or in combination.

[0050] The above-mentioned radically polymerizable polyfunctional monomer has an amount of unsaturated double bonds in the monomer that is equivalent to 1/4 to 40 times the amount of active oxygen in the added organic peroxide. It is desirable to mix them so that If the amount is less than 1/4 equivalent, it is difficult to expect much improvement in crosslinking efficiency due to the addition of the radically polymerizable polyfunctional monomer, and sufficient crosslinking will not occur. On the other hand, even if more than 40 times the equivalent is used, further crosslinking cannot be expected and it is not economical.

In addition to the organic peroxide and crosslinking aid, the crosslinking component has a high reactivity with free radicals, and either traps free radicals and becomes a radical source itself, or becomes relatively stable through decomposition. It is more preferable to use a radical-trapping compound that generates free radicals in combination.

The above-mentioned radical scavenging compound suppresses the decomposition of the polyolefin resin (a), improves the degree of co-crosslinking of the olefin elastomer (b) and silicone rubber (c), and suppresses the decomposition of the polyolefin resin (a) and the olefin elastomer (c).
It has the effect of promoting co-crosslinking with (b) and/or silicone rubber (c), and significantly improves the mechanical properties of the thermoplastic elastomer composition of the present invention.

As the above-mentioned radical-scavenging compound, it is most preferable to use a compound that has a large radical-scavenging ability and generates relatively stable radicals, and a compound that has performance as a so-called monomer polymerization inhibitor or chain transfer agent is preferable. This applies.

Specific examples of the radical scavenging compounds include p-benzoquinone dioxime, p,p'-dibenzoylquinone dioxime, hexafluoroisopropylidene bisphenol, dihydroxybenzophenone, hydroquinone, tetrachloro-p-benzoquinone, and benzoquinone. , 2,4,6-trimercapto-S-triazine,
Examples include dibenzothiazyl disulfide, tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide, α-methylstyrene dimer, and hydroquinone and benzoquinone are preferred. These radical scavenging compounds may be used alone or in combination.

The amount of the radical scavenging compound used is usually 1/2 of the amount of active oxygen in the organic peroxide used.
It is 0 to 2 times equivalent. If the amount is less than 1/20 times equivalent, no effect can be expected. On the other hand, if more than 2 times the equivalent amount is used, the radical-trapping compound basically has the properties of a polymerization inhibitor, so crosslinking is prevented. This tends to cause a significant decrease in efficiency, and crosslinking of only the polyolefin resin (a) may progress locally.

The thermoplastic elastomer composition of the present invention comprises:
As described above, by dynamically crosslinking the elastomer components (components (b) and (c)) while melt-mixing, thermoplasticity is maintained and excellent elastomer elasticity is obtained.

The degree of crosslinking in the composition of the present invention can be judged by the amount of gel present in the composition that cannot be extracted by organic solvents or the like.

The amount of gel is usually 50% by weight or more, preferably 60% by weight or more, particularly preferably 70% by weight or more, based on the total amount of components (2) and (3). 50% by weight
If it is less than 20%, the degree of crosslinking of the elastomer component may be low, and the elasticity of the elastomer may be poor.

The higher the amount of gel, the better the elasticity of the elastomer, and the upper limit is not particularly limited. In the composition of the present invention, the radical-trapping compound used to increase the reactivity (co-crosslinkability) of the polyolefin resin (a) and the olefin elastomer (b) forms a gel in which polyolefins are bonded. Therefore, although the amount of gel may exceed 100% by weight in some cases, such compositions exhibit particularly excellent elastomer elasticity and mechanical strength.

[0060] The amount of gel can be measured, for example, by the following method. (1) First, approximately 2 g of a sample (composition) is accurately weighed and extracted using a Soxhlet extraction device using tetrahydrofuran as a solvent for 4 hours. This operation is repeated three times by changing the solvent. This operation extracts the softener, additives, uncrosslinked silicone rubber, etc. in the composition. ■ After drying the sample, it was accurately weighed and heated again at approximately 160°C using O-xylene as a solvent using a Soxhlet extraction device.
Extraction is carried out for 4 hours, and this operation is repeated three times by changing the solvent. Through this extraction process, the polyolefin resin in the composition,
The uncrosslinked olefinic elastomer is extracted and the residue represents the total amount of the crosslinked rubber and the various components bonded to the crosslinked rubber. In the specification, "gel amount" is a value expressed as a percentage of the weight of the dried residual gel after the completion of the extraction in (2) above, of the weight of the elastomer component (the sum of components (b) and (c)).

The thermoplastic elastomer composition of the present invention is
It can be produced using conventional kneading equipment such as a rubber mill, Brabender mixer, Banbury mixer, pressure kneader, single screw extruder, twin screw extruder, etc.

When considering the productivity of the composition of the present invention, it is most preferable to employ a continuous manufacturing process using a twin-screw extruder. When producing the composition of the present invention using a twin-screw extruder, the longer the extruder, the higher the productivity, but a combination of twin-screw extruders with shorter shafts may be used.

If the silicone rubber (c) is clay-like and it is difficult to feed it directly into an extruder, use a batch-type mixing tank such as a Banbury mixer or kneader (b).
The advantages of a continuous process can be maintained by mixing the components (b) and (c) and feeding the mixture in a molten state to a twin-screw extruder using a feeder ruder or the like.

The thermoplastic elastomer composition of the present invention includes:
For example, a polyolefin resin (a), an olefin elastomer (b), and a silicone rubber (c) are fed to a twin-screw extruder, and a crosslinking component consisting of an organic peroxide, a crosslinking aid, etc. is added to the twin-screw extruder. It can be produced by a method in which pellets are added, kneading is continued to advance the crosslinking reaction, and pellets are taken out from the end of the extruder.

[0065] The method of adding each component when producing the composition of the present invention is not particularly limited, and the timing and order of addition can be changed as appropriate.

The kneading temperature is a temperature at which all the components to be mixed are melted, and is usually in the range of 160 to 280°C, preferably 180 to 250°C. Further, the kneading time cannot be discussed unconditionally because it depends on the type and amount of the constituent components and the kneading equipment, but when using a pressure kneader, Banbury mixer, etc. as the kneading equipment, it is usually about 5 ~20 minutes.

Furthermore, when kneading, each component may be kneaded all at once, or a multistage split kneading method may be used in which any component is kneaded and then the remaining components are added and kneaded. .

The thermoplastic elastomer composition of the present invention may contain various additives, such as paraffin oils, naphthenic oils, softeners such as plasticizers, anti-aging agents, heat stabilizers, and ultraviolet absorbers, as necessary. , stabilizers such as copper damage inhibitors, inorganic fillers such as silica, talc, carbon, zinc oxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, glass fiber, wood flour, cork powder, cellulose powder, Organic fillers such as rubber powder, lubricants such as stearic acid, flame retardants, etc. can be blended.

The thermoplastic elastomer composition of the present invention mainly contains a polyolefin resin (a), an olefin elastomer (b), and a silicone rubber (c), but may contain other polymers, such as nylon, if necessary. 6. Polyamide resins such as nylon 6.6 and nylon 4.6, thermoplastic polyamide elastomers, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, thermoplastic polyester elastomers, polyurethanes, thermoplastic polyurethane elastomers, polycarbonates, polyoxymethylene, Polyphenylene ether, A
Thermoplastic resins such as BS resin, AES resin, and AS resin, elastomer components such as butyl rubber, acrylic rubber, and epichlorohydrin rubber can also be blended and used.

[0070] The timing of addition of these additives or other polymers to be blended is not particularly limited, but it is desirably determined in consideration of the purpose of use and the properties of the raw materials (thermal stability, etc.).

For example, various stabilizers such as anti-aging agents, heat stabilizers, and ultraviolet absorbers are used to improve the stability of the resulting composition, and they also inhibit the crosslinking reaction caused by the organic peroxide used as a crosslinking agent. Large amounts should not be added before adding the organic peroxide, as this may inhibit or cause the organic peroxide to lose its effectiveness.

[0072] Since other polymers also undergo decomposition or crosslinking reactions due to organic peroxides, the timing of addition must be determined depending on the purpose of use.

The thermoplastic elastomer composition of the present invention is
Vehicle parts such as automobiles include rack and pinion boots, bellows, vacuum connectors, tubes, side moldings, headrests, regulators, armrests, shift lever boots, weather strips, air spoilers, suspension boots, belt covers, foil covers, knobs, etc. Industrial parts such as bumpers, side shields, and bumper moldings include hydraulic hoses, air tubes, rubber hoses, out covers, various gaskets, containers, O-rings, packing materials, keyboard materials, footwear such as shoes and sandals, and various colors. tile,
Flooring materials, furniture, home appliance surface materials, antistatic materials, sporting goods,
In particular, it can be used for grip skin materials.

Furthermore, the composition of the present invention can be preferably used as gaskets for medical syringes, catheter tubes, sheets, and the like.

[0075]

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited by these Examples unless the gist of the invention is exceeded. In addition, parts and percentages in the examples are based on weight unless otherwise specified.

Example 1: Ethylene-propylene-diene copolymer containing ethylidenenorbornene as a diene component, having an iodine value of 15, and containing 75 parts of paraffinic oil as an extender oil per 100 parts of rubber. 70 parts of rubber (manufactured by Japan Synthetic Rubber Co., Ltd., EP98) (40 parts as rubber), 30 parts of polypropylene, silicone rubber compound (EH5230 manufactured by Japan Synthetic Rubber Co., Ltd.)
), 3.5 parts of zinc oxide, 0.7 parts of stearic acid, and 0.2 parts of Irganox 1010 (antiaging agent manufactured by Ciba Geigy) was melt-kneaded in a Banbury mixer at a bath temperature of 170°C. After forming the mixture into a sheet, it was made into square pellets using a sheet pelletizer (hereinafter, these square pellets are referred to as "mixture A").
.

Next, the above-described process was carried out in a twin-screw extruder [manufactured by Nippon Steel Corporation, TEX-44 (L/D=40)] equipped with an oil injection device, an organic peroxide addition device, and a crosslinking aid addition device. Mixture A was added and paraffin oil (
PW-90 manufactured by Idemitsu Petrochemical Co., Ltd. at a ratio of 20 parts per 100 parts of mixture A, and 2,5-dimethyl-2,5-di-t-butylperoxyhexane as a crosslinking agent per 100 parts of mixture A. .0 parts, bismaleimide 88%
Mixture A1:
2.0 parts per 0.00 parts was added, and melt-kneading was continued to pelletize to obtain a thermoplastic elastomer composition. (Example in which 43 parts of silicone rubber compound was blended with 100 parts of a composition of 43% by weight of polypropylene and 57% by weight of ethylene-propylene rubber)

A molded plate of 10 cm x 10 cm was obtained by injection molding the obtained composition, and a JIS No. 3 dumbbell was punched out using a dumbbell cutter to prepare a sample for tensile property testing.

[0079] Further, a compression set test was conducted using a circular cylinder having a diameter of 29 mm, which was punched out from the above-mentioned molded plate, and was stacked to form a right circular column with a thickness of 12.70±0.2 mm.

The hardness was measured using a JIS A spring type hardness tester. Measurement conditions are JIS K63
01-1975 vulcanized rubber physical test method.

Further, the gel content of the composition was measured according to the method described above. The results are shown in Table 1.

Examples 2 to 5, Comparative Examples 1 to 4: Thermoplastic elastomer compositions were obtained in substantially the same manner as in Example 1, except that the ingredients and proportions were changed as shown in Tables 1 to 3. Ta. The obtained composition was molded in the same manner as in Example 1,
Various physical properties were evaluated. The results are shown in Tables 1 to 3.

[0083]

[Table 1]

[Table 2]

[Table 3]

As is clear from Tables 1 to 3, Example 1
Compositions No. 5 to 5 have effective composites of silicone rubber and olefin components, and exhibit excellent mechanical properties and compression set.

On the other hand, the composition of Comparative Example 1 was obtained by simply mixing the constituent components without adding a crosslinking agent, and had poor mechanical properties. In addition, compression set is also poor. Furthermore, the silicone component oozes out on the surface of the molded product, giving a poor surface feel.

The composition of Comparative Example 2 did not use an olefin elastomer and was a composite of only polypropylene and silicone rubber. The miscibility of the silicone component and polypropylene is poor, resulting in poor mechanical strength.

The composition of Comparative Example 3 does not contain polypropylene, has no thermoplasticity, and cannot be molded.

The composition of Comparative Example 4 had a composition ratio of each component outside the range of the present invention, and contained a large amount of silicone component. Therefore, it has poor thermoplasticity and cannot be molded.

[0089]

[Effects of the Invention] The thermoplastic elastomer composition of the present invention is a unique material that combines the characteristics of an olefin polymer and a silicone polymer, and provides a new material that can be called a thermoplastic silicone elastomer. It is.

The composition of the present invention also has the oxygen permeability and safety to the human body of a silicone rubber, and is particularly suitable as a molding material for medical devices, and has great industrial value.

Claims (1)

[Claims] Claim 1: (a) 1 to 99% by weight of polyolefin resin and (b) 99 to 1% by weight of olefin elastomer.
A thermoplastic elastomer composition obtained by dynamically crosslinking a composition comprising (c) 1 to 300 parts by weight of silicone rubber mixed with 100 parts by weight of the total amount of silicone rubber.