JP2000186210A - Hollow-filler-containing silicone rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a silicone rubber composition which can give a cured product having high shock absorptivity as well as weather resistance, low- temperature resistance, and heat resistance inherent in a silicone rubber by adding a hollow filter to a curable organopolysiloxane composition. SOLUTION: This composition-comprises 100 pts.wt. (A) curable organopolysiloxane composition and 0.1-20 pts.wt. (B) hollow filler having a mean particle diameter of 200 μm or below and an elastic characteristic of 10% or above. Component B is desirably one made from a thermoplastic resin. Component A is desirably an addition-curable silicone rubber composition comprising 100 pts.wt. organopolysiloxane having at least two alkenyl groups on the average per molecule and having an average degree of polymerization of 1,200 or below, 0.1-50 pts.wt. organohydrogenpolysiloxane having at least two Si-bonded hydrogen atoms in the molecule and represented by the average compositional formula: RbHcSiO(4-b-c)/2 (wherein R is a 1-10C monovalent hydrocarbon group), and a catalytically effective amount of an addition reaction catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone rubber composition containing a hollow filler, which is suitable as a rubber material in various fields such as transport equipment, OA equipment, and home appliances, which are becoming lighter.

[0002]

2. Description of the Related Art Rubber materials generally have a higher shock absorbing power than metals, plastics and the like. Among them, silicone rubber has a good heat resistance, weather resistance and electrical insulation. It can be used in various fields. However, the rubber material mainly absorbs impact energy due to distortion due to viscoelasticity, and therefore requires a material thickness in the direction of the impact force and a weight. In the field of lightening in various fields such as transport machines, OA equipment, and home appliances, there has been a demand for a material that is lightweight, has sufficient elasticity, and can produce a large number of molded products.

As such a material, there is a silicone rubber foam, and there are a method of adding a pyrolytic foaming agent and a method of molding the foam with hydrogen gas by-produced during curing. However, the method of adding a thermal decomposition type foaming agent has been considered to be problematic in terms of toxicity and odor of the decomposed gas, and in the case of using a platinum catalyst as a curing catalyst, there is a problem of inhibition of curing by the foaming agent. I was Further, the method using hydrogen gas by-produced during curing has problems such as the explosiveness of hydrogen gas and the need to be careful in handling uncured products during storage.

Further, there is a molding method such as injection molding in which foam is formed in a mold. However, this method has a problem that it is difficult to obtain a silicone rubber foam having minute and uniform cells.

[0005] Accordingly, the present invention is directed to a silicone containing a hollow filler, which has the characteristics of silicone rubber, such as weather resistance, cold resistance, heat resistance, etc., and has a high shock absorption and provides a cured product having excellent compression characteristics. It is intended to provide a rubber composition.

Another object of the present invention is to provide a silicone rubber containing a hollow filler, which is capable of providing a cured product having a good impact resistance, capable of sufficiently reducing the weight, and having little breakage of the hollow filler during molding. It is to provide a composition.

[0007]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above object, the present inventors have found that the average particle size is 100 parts by weight of the curable organopolysiloxane composition. By mixing 0.1 to 20 parts by weight of a hollow filler having a thickness of 200 μm or less and an elastic property of 10% or more, it is excellent in various characteristics inherent in silicone rubber, and has high shock absorption and excellent compression characteristics. It has been found that a silicone rubber composition containing a hollow filler can be obtained.

That is, the inventor of the present invention has a specific particle size containing a gas therein and having an elastic property of 10% measured by the following method.
By blending the above minute hollow filler, particularly a material whose material is made of a thermoplastic resin, into the curable silicone rubber composition, the silicone rubber's original weather resistance, cold resistance, heat resistance is not impaired, and quickly. A material that can harden and absorb shock by deformation of the balloon even with a small force, and can absorb shock by the internal gas even if the balloon is broken by a large force, and this material can sufficiently cope with weight reduction Was found.

Accordingly, the present invention firstly provides a hollow filler having an average particle size of 200 μm or less and an elastic property of 10% or more per 100 parts by weight of the curable organopolysiloxane composition. Provided is a silicone rubber composition containing a hollow filler, characterized by being blended in an amount of from 20 to 20 parts by weight.

The present inventor has also proposed an organopolysiloxane having an average of two or more alkenyl groups in one molecule and an average degree of polymerization of 1200 or less, and an average composition formula (1)
An organohydrogenpolysiloxane represented by
By adding a fine hollow filler having an average particle diameter of 20 to 60 μm to an addition-curable silicone rubber composition containing an addition reaction catalyst, sufficient weight reduction is possible, and lightweight and good elasticity is obtained. Hollow filler-containing silicone rubber that can be molded satisfactorily with almost no breakage during molding and gives a cured product with excellent impact resistance, and can be a material that can sufficiently cope with weight reduction in various fields such as transport equipment, OA equipment, home appliances, etc. It has been found that a composition is obtained.

Accordingly, the present invention provides: (1) 100 parts by weight of an organopolysiloxane having an average of two or more alkenyl groups in one molecule and an average degree of polymerization of 1200 or less; Average composition formula (1) R _b H _c SiO _{(4-bc) / 2} (1) (wherein, R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms. 0.7 to 2.1, c is 0.001 to 1.0, and b + c is a positive number that satisfies 0.8 to 3.0.) 0.1 to 50 parts by weight of an organohydrogenpolysiloxane having at least two hydrogen atoms obtained (3) Addition reaction catalyst Catalyst amount (4) 0.5 to 10 parts by weight of fine hollow filler having an average particle diameter of 20 to 60 μm Containing a hollow filler-containing silicone rubber composition characterized by comprising provide.

Hereinafter, the present invention will be described in more detail.
In the first invention and the second invention of the present invention, the hollow filler compounded in the hollow filler-containing silicone rubber composition,
By having a gas portion in the cured product, it is possible to absorb shock like a sponge rubber. Examples of such a hollow filler material include various materials such as a glass balloon, a silica balloon, a carbon balloon, an alumina balloon, a zirconia balloon, a shirasu balloon or a plastic balloon such as a phenol resin balloon and a vinylidene chloride resin balloon.

As the material of such a hollow filler,
In particular, the hollow filler itself has elasticity, that is, a hollow balloon made of a thermoplastic resin, particularly, vinylidene chloride, acrylonitrile, methacrylonitrile, acrylate,
A methacrylic acid ester polymer or a copolymer of two or more of these is preferred. By using these, effective shock absorbing power can be obtained. this is,
This is because the hollow filler itself can be deformed by a small force due to its elasticity and can absorb an impact.

The average particle diameter of the hollow filler is 200 μm.
m, usually 10 to 200 μm, preferably 10 to 10 μm
0 μm, more preferably 20 to 60 μm.
In the present invention, those having a large average particle size exceeding 60 μm are preferably used. If the average particle size exceeds 200 μm, the hollow filler will be broken at the time of molding, and the impact absorbing ability will be insufficient. If the average particle size is less than 10 μm, the size of the bubbles is too small, and the impact absorbing ability may be insufficient. On the other hand, from the viewpoint of providing a cured product having excellent impact resistance without being destroyed during molding such as injection molding, which is the object of the second invention, the average particle size is preferably 20 to 60 μm, and more preferably Is 2
It is necessary to select and use a fine hollow filler having a diameter of 5 to 50 μm, more preferably 30 to 40 μm. If the average particle diameter is less than 20 μm, the impact absorption performance becomes insufficient because the average particle diameter is too small. Under such high pressure conditions, the hollow filler is easily broken. The average particle diameter can be determined as a weight average value (or median diameter) using, for example, a particle size distribution measuring device such as a laser light diffraction method.

In the first invention of the present invention, a hollow filler having an elastic property measured by the following method of 10% or more, preferably 15% or more is used. 10 elastic properties
%, The hollow filler itself is rigid, so that sufficient impact absorption characteristics cannot be obtained. The upper limit of this elastic property is usually 50%, preferably about 45%.

Method for measuring elastic characteristics: Elastic characteristics refers to a range in which a balloon can be reversibly or repeatedly deformed without being destroyed, and is measured as follows.

The hollow filler has a viscosity of 1000 at 25.degree.
cs silicone oil (dimethylpolysiloxane) was mixed in a volume ratio of 50:50, and the mixture was added to a 5.0 cc syringe (cross-sectional area: 1 cm ² ) by 3.0 c
c) After the injection, the tip was closed and a force of 20 kgf (ie, 20 kgf) was applied.
kgf / cm ² ) is measured. For example, the deformation rate when 3.0 cc → 2.4 cc is set to (1-2.4 / 3.0) × 100 = 20%. However, when the force of 20 kgf is removed, it must be restored to 3.0 cc.

Further, in order to sufficiently exhibit such an impact absorbing ability, the true specific gravity of the hollow filler is 0.01 to 0.5.
2, particularly preferably 0.015 to 0.1. If the true specific gravity is less than 0.01, not only is it difficult to mix and handle, but also the strength of the hollow filler is inadequate, causing breakage during molding, which may result in insufficient shock absorbing ability. If it is large, the proportion of the material portion of the hollow filler (that is, the wall material portion) becomes large, and the impact absorbing ability may be insufficient or the physical properties of the cured silicone rubber may be adversely affected.

These hollow fillers have an increased strength, an improved heat resistance, and a range in which the elasticity is not significantly impaired.
For the purpose of improving dispersibility, the surface is made of calcium carbonate,
It may be treated with talc, titanium oxide, or the like.

In the first invention of the present invention, the hollow filler is used in an amount of 0.1 to 20 parts, preferably 0.2 to 15 parts, per 100 parts (parts by weight, hereinafter the same) of the curable organopolysiloxane composition. , More preferably 0.5 to 10 parts. If the compounding amount is less than 0.1 part, the impact absorbing power is insufficient, and the weight and the moldability are deteriorated.
If it exceeds 0 parts, the compounding is difficult and the rubber strength of the cured product becomes insufficient.

In this case, the compounding amount of the hollow filler is as follows: for those having a true specific gravity of 0.1 to 0.2, the curable organopolysiloxane composition (excluding the hollow filler)
1 to 20 parts relative to 0 part, 0.5 to 10 parts for those having a true specific gravity of 0.05 to 0.1, and a true specific gravity of 0.01 to
For 0.05, the content is preferably 0.1 to 5 parts. That is, a volume ratio of 1 to the rubber material (that is, the whole organopolysiloxane composition containing the hollow filler).
It is good to be 0-80 volume%, especially 15-75 volume%.
If the amount is less than 10% by volume, the impact absorbing power may be insufficient. If the amount exceeds 80% by volume, the compounding is difficult and the rubber strength of the cured product is also insufficient. In some cases.

In the first invention of the present invention, the curable organopolysiloxane composition may be any of a peroxide-curable type, a condensation-curable type, and an addition-curable type. Curable organopolysiloxane compositions are preferably used. (1) has a 1 molecular average at least two alkenyl groups in an average degree of polymerization of 100 parts by weight of an organopolysiloxane below 1200 following (2) the following average compositional formula _{(1) R b H c SiO} (4- _{bc) / 2} (1) (wherein, R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, b is 0.7 to 2.1, c is 0.001 to 1.0, and b + c is a positive number satisfying 0.8 to 3.0.) An organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule 0.1 to 50 parts by weight (3) Addition reaction catalyst Catalyst amount

Here, as the organopolysiloxane having an average of two or more alkenyl groups in one molecule of the first component, those represented by the following average composition formula (2) can be used. R ¹ _a SiO _{(4-a) / 2} (2) (wherein, R ¹ is the same or different and has 1 to 10 carbon atoms;
It is preferably 1 to 8 unsubstituted or substituted monovalent hydrocarbon groups, and a is 1.5 to 2.8, preferably 1.8 to 2.5,
More preferably, it is a positive number in the range of 1.95 to 2.05. )

Examples of the unsubstituted or substituted monovalent hydrocarbon group bonded to the silicon atom represented by R ¹ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group and a tert-butyl group. , Pentyl group,
Alkyl groups such as neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, phenyl group, tolyl group, xylyl group, aryl group such as naphthyl group, benzyl group, phenylethyl group, phenylpropyl group, etc. Aralkyl groups, vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, cyclohexenyl groups, alkenyl groups such as octenyl groups,
Some or all of the hydrogen atoms of these groups are fluorine, bromine,
Those substituted with a halogen atom such as chlorine, a cyano group, and the like, for example, a chloromethyl group, a chloropropyl group, a bromoethyl group, a trifluoropropyl group, a cyanoethyl group, and the like can be given.

In this case, at least two of R ¹ must be an alkenyl group (especially those having 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms). The content of the alkenyl group is 0.01 to 0.01 in all the organic groups bonded to the silicon atom (that is, in the unsubstituted or substituted monovalent hydrocarbon group as R ¹ in the above average composition formula (2)).
It is preferably 20 mol%, particularly preferably 0.1 to 10 mol%. This alkenyl group may be bonded to a silicon atom at the molecular chain end, may be bonded to a silicon atom in the middle of the molecular chain, or may be bonded to both, but the curing rate of the composition, From the viewpoint of physical properties and the like, the organopolysiloxane used in the present invention preferably contains at least an alkenyl group bonded to a silicon atom at a molecular chain terminal.

The structure of the above-mentioned organopolysiloxane is usually a di-chain having a basically linear structure in which the main chain is composed of repeating diorganosiloxane units and both ends of the molecular chain are blocked with triorganosiloxy groups. Although it is an organopolysiloxane, it may have a partially branched or cyclic structure. Average degree of polymerization (weight average degree of polymerization) is 5
It is preferably a liquid at room temperature (25 ° C.) of 0 or more and 1200 or less, particularly 100 or more and 850 or less, and when it is less than 50, rubber properties as a cured product may be insufficient.
If it exceeds 0, it is not only difficult to mix the hollow balloon,
A problem may occur that the balloon is broken during the compounding.

The organohydrogenpolysiloxane of the second component is represented by the following average compositional formula _{(1) R b H c SiO} (4-bc) / 2 (1), at least two per molecule, preferably Two
It is necessary to have 200, more preferably 3 to 100, silicon-bonded hydrogen atoms (ie, SiH groups).

In the above formula (1), R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R is the same group as R ¹ in the above formula (2). Can be mentioned. B is 0.7 to 2.1, c is 0.001 to
1.0 and b + c is a positive number satisfying 0.8 to 3.0, preferably b is 1.0 to 2.0, and c is 0.01
1.0 and b + c are 1.5 to 2.5.

At least two, preferably three, in one molecule
More than one SiH group may be located at the terminal of the molecular chain, at the middle of the molecular chain, or at both of them. The molecular structure of the organohydrogenpolysiloxane may be any of linear, cyclic, branched, and three-dimensional network structures, but the number of silicon atoms (or degree of polymerization) in one molecule is usually 2 to 300
And preferably about 4 to 150 pieces at room temperature (25 ° C.).

Specific examples of the organohydrogenpolysiloxane of the formula (2) include, for example, 1,1,3,3-
Tetramethyldisiloxane, methyl hydrogen cyclopolysiloxane, methyl hydrogen siloxane
Dimethylsiloxane cyclic copolymer, both ends trimethylsiloxy group-blocked methylhydrogenpolysiloxane, both ends trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both ends dimethylhydrogensiloxy group-blocked dimethylpolysiloxane, both ends Dimethyl hydrogen siloxy group-blocked dimethyl siloxane / methyl hydrogen siloxane copolymer, both ends trimethyl siloxy group-blocked methyl hydrogen siloxane / diphenyl siloxane copolymer, both ends trimethyl siloxy group-blocked methyl hydrogen siloxane / diphenyl siloxane / dimethyl siloxane Copolymer, both ends dimethylhydrogensiloxy group-blocked methylhydrogensiloxane, dimethylsiloxane, diphenylsilane Hexane copolymer, (CH _{3) 2} HSi
Copolymer consisting of O _1/2 units, (CH ₃ ) ₃ SiO _1/2 units and SiO _4/2 units, (CH ₃ ) ₂ HSiO _1/2 units and S
a copolymer composed of iO _4/2 units, (CH ₃ ) ₂ HSiO
Such as _1/2 units and SiO _4/2 units, and the (C ₆ H _{5) 3} consisting of SiO _1/2 units copolymers.

The amount of the organohydrogenpolysiloxane to be used is as follows.
The amount is preferably 0.1 to 50 parts, particularly 0.3 to 20 parts with respect to 0 parts. The organohydrogenpolysiloxane of the second component has an amount of hydrogen atoms (SiH groups) bonded to silicon atoms in the second component per mole of alkenyl groups bonded to silicon atoms in the first component. 0.5 ~
It can be blended in an amount of about 5 mol, especially about 0.8 to 2.5 mol.

Examples of the third component addition reaction catalyst include platinum black, chloroplatinic acid, chloroplatinic acid, a reaction product of chloroplatinic acid with a monohydric alcohol, a complex of chloroplatinic acid with an olefin, platinum bisacetate. Platinum group metal catalysts such as platinum catalysts such as acetate, palladium catalysts, and rhodium catalysts are exemplified. The amount of the addition reaction catalyst can be a catalytic amount, and is usually 0.5 to 10 as a platinum group metal.
The concentration may be set to 00 ppm, particularly about 1 to 500 ppm.

The second invention of the present invention provides the above (1) to (3)
The above-mentioned hollow filler is blended with the addition reaction-curable silicone rubber composition containing the component as an essential component. In this case, the average particle size is particularly 20 to 60 μm, preferably 25.
It is preferable to select a fine hollow filler having a size of from 50 to 50 μm, more preferably from 30 to 40 μm, and to blend 0.5 to 10 parts, preferably from 1 to 8 parts with respect to 100 parts of the first component organopolysiloxane. It is possible to provide a cured product that can be sufficiently reduced in weight, has little breakage during molding, and has good impact resistance. In this case, from the viewpoint that there is no breakage of the hollow filler during molding, if the hollow filler has an average particle diameter of 20 to 60 μm, the elastic property of the hollow filler is 10% or more as in the case of the first invention. It does not have to be.

The compositions according to the first and second aspects of the present invention preferably contain a thixotropic (ie, thixotropic) imparting agent. As the thixotropy imparting agent, any substance can be used as long as it can suppress the flowability of the material and impart thixotropy (thixotropic property) to the composition. Generally, fumed silica is used as a solid material. , Fumed titanium oxide, carbon and the like are exemplified,
These may be used as they are or may be surface-treated with an organosilicon compound such as hexamethylsilazane, trimethylchlorosilane or polymethylsiloxane. As the material that is liquid at room temperature (25 ° C.), any material may be used as long as it is incompatible with the composition, and polyethers such as polyethylene oxide, polypropylene oxide, polyethylene glycol, and polypropylene glycol, and A block polymer of dimethylsiloxane and siloxane, a copolymer of dimethylsiloxane and diphenylsiloxane, and the like are mainly used.

The thixotropic agent may be used alone or in combination of two or more. The amount of the thixotropic agent is 0.1 to 100 parts of the first component organopolysiloxane. The amount is preferably from 01 to 30 parts, particularly preferably from 0.03 to 20 parts. If the amount is less than 0.01 part, sufficient thixotropy may not be obtained, and if it exceeds 30 parts, moldability, rubber properties and the like may be adversely affected.

The silicone rubber composition of the second invention of the present invention has a sagging of the material after 1 minute of 1 inch or less, especially 0 to 0. 0, according to a Boeing Flow Jig test shown below.
It preferably has an 8-inch thixotropic property (thixotropic property). If the thixotropy exceeds 1 inch, the hollow filler tends to float during storage and separate over time,
The cured product may become a rubber having a different specific gravity depending on the portion.

Boeing Flow Jig Test: A test to determine the amount of sag control of a composition, in which the composition is placed in a bowl portion of a Boeing Flow jig and then
Take a horizontal test jig and stand it one end down so that the composition flows vertically down from the bowl on the scale. The amount flowing down by the action of gravity is measured as the length of flow (in inches) after 60 seconds. Usually, the measurement is performed after 35 seconds, but in the present material, the measurement is performed after 60 seconds to clarify the difference.

In the silicone rubber compositions according to the first and second aspects of the present invention, in addition to the above essential components, in order to improve the mechanical strength of the molded article, to improve the heat resistance, and to improve the flame retardancy. A filler may be blended for such reasons as not to impair the effects of the present invention. As the filler, for example, precipitated silica, reinforcing fillers such as calcined silica, ground quartz, diatomaceous earth, asbestos, aminosilicic acid,
Non-reinforcing fillers such as iron oxide, zinc oxide, calcium carbonate, magnesium carbonate, cerium oxide are exemplified,
As it is, it may be surface-treated with an organosilicon compound such as hexamethylsilazane, trimethylchlorosilane or polymethylsiloxane.

In the silicone rubber compositions according to the first and second aspects of the present invention, in addition to the above essential components, optional components such as a flame retardant, a fire resistance improver, a sensitizer, a colorant, Various additives such as a heat resistance improver and a reducing agent, a reaction control agent such as ethynylcyclohexanol, a release agent and a dispersant for a filler can be added. In addition, it is preferable that the amount of various alkoxysilanes, carbon functional silanes, low molecular weight siloxanes containing silanol groups, and the like used as the filler dispersant be minimized so as not to impair the effects of the present invention.

In the silicone rubber compositions according to the first and second aspects of the present invention, the above-mentioned components are uniformly mixed using a rubber kneading machine such as a two-roll mill, a Banbury mixer or a dough mixer (kneader). It can be obtained by performing a heat treatment as needed. In this case, for example, a part or all of the organopolysiloxane of the first component and an inorganic filler such as silica are mixed in advance with a surface treatment agent as needed to prepare a base compound, and the remaining second compound is added thereto. One component organopolysiloxane, the second component organohydrogenpolysiloxane, the third component addition reaction catalyst, the hollow filler and other optional components may be mixed.

The silicone rubber composition thus obtained can be molded into a required silicone rubber by various molding methods such as injection molding, casting molding, mold pressure molding, extrusion molding and the like. However, injection molding can be particularly preferably employed.

The curing conditions can be appropriately adjusted. For example, in the case of press molding, it is preferable to set the temperature at 120 to 220 ° C. for about 5 minutes to 1 hour. In the case of injection molding, it is preferable to set the temperature at 80 to 220 ° C. for about 10 seconds to 10 minutes.

[0043]

The silicone rubber composition containing a hollow filler according to the first invention of the present invention has the weather resistance inherent in silicone rubber,
Gives a cured product with excellent compression properties that can absorb shock by deformation of the balloon with a small force without impairing cold resistance and heat resistance, even if the balloon is destroyed by a large force It is a material that can be widely used in various fields such as transport aircraft, OA equipment, and home appliances. Further, the hollow filler-containing silicone rubber composition of the second invention of the present invention is lightweight, has sufficient elasticity, hardly breaks during molding, has good moldability, and has excellent impact energy absorption. It is a material that can give a cured product and can sufficiently cope with weight reduction in various fields such as transport equipment, OA equipment, and home appliances, similarly to the first invention.

[0044]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In addition, all parts described here represent parts by weight.

[Example 1] The viscosity at 25 ° C was 5000c.
80 parts of dimethylpolysiloxane (average degree of polymerization: about 450) having a vinyldimethylsiloxy group at both ends and having a viscosity of 500 at 25 ° C.
0cs side chain vinyl group-containing dimethylpolysiloxane (average degree of polymerization: about 450, vinyl value 0.0003 mol /
g) 20 parts, hydrophobized fumed silica having a specific surface area of 110 m ² / g (R-9 manufactured by Nippon Aerosil Co., Ltd.)
72) 8 parts, a hollow filler (Expancel 551DE, manufactured by Expancel Co., Ltd.) having a true specific gravity of 0.04, an average particle size of 40 μm, and an elastic property of 38% measured by the above method.
4 parts (copolymer of acrylonitrile / methacrylonitrile / vinylidene chloride) (48% by volume based on the whole composition)
Was placed in a planetary mixer, and stirring was continued for 30 minutes. Then, 4.7 parts of methyl hydrogen polysiloxane represented by the following formula (3) and 0.05 part of ethynylcyclohexanol as a reaction control agent were added, and After stirring for a minute, the resulting composition is converted into a silicone rubber composition (1).
And

[0046]

Embedded image

To 112 parts of the composition, 0.1 part of a 1% isopropyl alcohol solution of chloroplatinic acid was added, and the mixture was stirred and defoamed.
Cut out a test piece of mx 30 mm x 20 mm (thickness)
The thickness one minute after the weight of 20 kg was put thereon was measured, and the value calculated by the following equation was used as the compression characteristic. Further, the rubber hardness (JIS-A hardness) of a sheet having a thickness of 2 mm formed by curing the composition in an oven at 150 ° C. for 30 minutes was measured based on JIS-K6301. Table 1 shows the results of the rubber hardness and the compression characteristics. Compression characteristics (%) = [1−thickness after deformation (mm) / 20 m
m] × 100

Example 2 The viscosity at 25 ° C. was 5000 c
80 parts of dimethylpolysiloxane (average degree of polymerization: about 450) having a vinyldimethylsiloxy group at both ends blocked by s
20 parts of side chain vinyl group-containing dimethylpolysiloxane having a viscosity at 5 ° C of 5000 cs (average degree of polymerization: about 450, vinyl value 0.0003 mol / g), specific surface area 200 m
5 parts of ² / g fumed silica (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.), true specific gravity 0.03, average particle size 70
Hollow filler having an elastic property of 42% according to the above-mentioned measurement method at μm (Expancel 0)
1.5 parts (32% by volume based on the total composition) of 91 DE-80, a copolymer of acrylonitrile, methacrylonitrile, and vinylidene chloride) were placed in a planetary mixer.
After continuing stirring for 30 minutes, 4.7 parts of methyl hydrogen polysiloxane represented by the above formula (3) and 0.05 part of ethynylcyclohexanol as a reaction control agent were added,
The resulting composition was stirred for 15 minutes to obtain a silicone rubber composition (2).

To 107 parts of this composition, 0.1 part of a 1% isopropyl alcohol solution of chloroplatinic acid was added, stirred, defoamed, and cured at 150 ° C. for 30 minutes in the same manner as in Example 1. Rubber hardness and compression properties were measured. Table 1 shows the results.

Example 3 The viscosity at 25 ° C. was 5000 c
30 parts of precipitated silica (Nipsil LP manufactured by Nippon Silica Kogyo Co., Ltd.) was added to 60 parts of dimethylpolysiloxane (average degree of polymerization: about 450) having a vinyldimethylsiloxy group blocked at both ends,
Hexamethyldisilazane (2 parts) and water (1 part) were put into a kneader mixer, and the mixture was stirred at room temperature for 1 hour.
The mixture was heated to 50 ° C., and further stirred for 3 hours. After cooling, a silicone rubber base (1) was obtained.

In 80 parts of this silicone rubber base (1), 20 parts of a dimethylpolysiloxane having a side chain vinyl group having a viscosity of 5000 cs at 25 ° C. (average degree of polymerization: about 450, vinyl value 0.0003 mol / g), ratio Surface area is 11
3 parts of fumed silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) having a hydrophobicity of 0 m ² / g, and a true specific gravity of 0.0
2. 2 parts of a hollow filler (microsphere F-80ED manufactured by Matsumoto Yushi-Seiyaku Co., Ltd., copolymer of acrylonitrile / methacrylonitrile / vinylidene chloride) having an average particle size of 90 μm and an elastic property of 40% according to the above-mentioned measurement method ( 52% by volume based on the total composition) was put into a planetary mixer, and stirring was continued for 30 minutes. Then, 4.7 parts of methylhydrogenpolysiloxane represented by the above formula (3) were added, and ethynylcyclohexanol was used as a reaction control agent. 0.05 parts was added, and stirring was continued for 15 minutes to obtain a completed composition, which was designated as a silicone rubber composition (3).

To 106 parts of this composition, 0.1 part of a 1% isopropyl alcohol solution of chloroplatinic acid was added, stirred, defoamed, and then cured at 150 ° C. for 30 minutes in the same manner as in Example 1. Rubber hardness and compression properties were measured.
Table 1 shows the results.

Example 4 The viscosity at 25 ° C. was 5000 c
80 parts of dimethylpolysiloxane (average degree of polymerization: about 450) having a vinyldimethylsiloxy group at both ends blocked by s
20 parts of side chain vinyl group-containing dimethylpolysiloxane having a viscosity at 5 ° C of 5000 cs (average degree of polymerization: about 450, vinyl value 0.0003 mol / g), specific surface area 200 m
² parts / g of fumed silica (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.), true specific gravity 0.13, average particle size 10
Hollow filler (microsphere MFL-100C manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) having a surface of 0 μm and having an elastic property of 35% according to the above-mentioned measurement method treated with calcium carbonate.
A, 8 parts (36% by volume based on the total composition) of an acrylonitrile / methacrylonitrile / vinylidene chloride copolymer) was placed in a planetary mixer, and the mixture was stirred for 30 minutes, and then expressed by the above formula (3). Then, 4.7 parts of methylhydrogenpolysiloxane and 0.05 part of ethynylcyclohexanol as a reaction control agent were added, and the resulting composition was stirred for 15 minutes to obtain a silicone rubber composition (4).

Subsequently, 0.1 part of a 1% isopropyl alcohol solution of chloroplatinic acid was added to 113 parts of the composition, stirred and defoamed, and cured at 150 ° C. for 30 minutes in the same manner as in Example 1. Rubber hardness and compression properties were measured.
Table 1 shows the results.

[Comparative Example 1] The viscosity at 25 ° C was 5000c.
80 parts of dimethylpolysiloxane (average degree of polymerization: about 450) having a vinyldimethylsiloxy group at both ends blocked by s
20 parts of side chain vinyl group-containing dimethylpolysiloxane having a viscosity at 5 ° C of 5000 cs (average degree of polymerization: about 450, vinyl value 0.0003 mol / g), specific surface area 200 m
5 parts of ² / g fumed silica (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.), true specific gravity 1.1, average particle size 10 μm
hollow glass filler (HSC110 manufactured by Toshiba Barotini) having an elastic property of 1% according to the above-mentioned measurement method at m
0 parts (46% by volume based on the whole composition) was put into a planetary mixer, and stirring was continued for 30 minutes.
4.7 of methyl hydrogen polysiloxane represented by
Part, ethynylcyclohexanol 0.1 as a reaction control agent.
05 parts were added and the resulting composition was stirred for 15 minutes to obtain a silicone rubber composition (5).

Subsequently, 0.1 part of a 1% solution of chloroplatinic acid in isopropyl alcohol was added to 205 parts of the composition, and after stirring and defoaming, the composition was cured at 150 ° C. for 30 minutes in the same manner as in Example 1. Rubber hardness and compression characteristics were measured for each of the rubbers. Table 1 shows the results.

COMPARATIVE EXAMPLE 2 A side chain vinyl group-containing dimethylpolysiloxane having a viscosity of 5,000 cs at 25 ° C. (average degree of polymerization: about 450, vinyl number: 0.5) was added to 80 parts of the silicone rubber base (1) of Example 3. 0003 mol / g) 20
Part, hydrophobized fumed silica having a specific surface area of 110 m ² / g (R-972 manufactured by Nippon Aerosil Co., Ltd.) 3
Part, 70 parts of hollow ceramics filler (Microcells SL75 manufactured by Chichibu Onoda Co., Ltd.) having a true specific gravity of 0.70, an average particle diameter of 45 μm, and an elastic property of 0.5% according to the above-described measuring method (52 volumes based on the entire composition) %) In a planetary mixer and continued stirring for 30 minutes, and then 4.7 parts of methyl hydrogen polysiloxane represented by the above formula (3),
Ethynylcyclohexanol 0.05 as a reaction control agent
The resulting composition was stirred for 15 minutes to obtain a silicone rubber composition (6).

Subsequently, 0.1 part of a 1% solution of chloroplatinic acid in isopropyl alcohol was added to 173 parts of the composition, stirred and defoamed, and cured at 150 ° C. for 30 minutes in the same manner as in Example 1. Rubber hardness and compression properties were measured.
Table 1 shows the results.

[0059]

[Table 1]

[Example 5] The viscosity at 25 ° C was 5000c.
80 parts of dimethylpolysiloxane (average degree of polymerization: about 450) having a vinyldimethylsiloxy group at both ends blocked by s
20 parts of dimethylpolysiloxane having a side chain vinyl group having a viscosity at 5 ° C. of 5000 cs (average degree of polymerization: about 700, vinyl value 0.0007 mol / g), and a specific surface area of 110 m
² / g and is hydrophobicized fumed silica (manufactured by Nippon Aerosil Co. R-972) 8 parts, the true specific gravity of 0.04, a hollow filler having an average particle size of 40 [mu] m (Expancel Inc. E
4 parts of xpancel 551DE, a copolymer of acrylonitrile, methacrylonitrile, and vinylidene chloride) were put into a planetary mixer, and the mixture was stirred for 30 minutes. Then, methyl hydrogen polysiloxane 5.7 represented by the following formula (3) was further added. Parts, a reaction control agent, 0.05 parts of ethynylcyclohexanol and 1 part of polyethylene glycol were added, and the resulting composition was stirred for 15 minutes to obtain a silicone rubber composition (7). The thixotropy of this composition according to the Boeing Flow Jig test was 0.62 inches.

[0061] 1% isopropyl alcohol solution of chloroplatinic acid to the composition 118 parts were added 0.1 parts of post-stirring and degassing, injection molding (material measuring pressure 40 kgf / cm ^2, injection pressure 15 kgf / cm ^2, (At 150 ° C. for 60 seconds) to prepare a 2 mm sheet, and its specific gravity is measured.
It was 4.

On the other hand, a 2 mm sheet was prepared from the same composition by oven curing at 150 ° C. for 15 minutes, and the specific gravity was measured. The result was 0.56, and the difference from the specific gravity at the time of injection molding was 0.08. Because of its small size, the hollow balloon was very slightly destroyed by injection molding, and a cured silicone rubber having a light weight and good elasticity against compression was obtained. The rubber hardness (JIS-A type hardness) of the 2 mm sheet obtained by oven curing was measured in the same manner as in Example 1 based on JIS-K6301. Table 2 shows the results.

[0063]

Embedded image

Example 6 The viscosity at 25 ° C. was 5000 c
80 parts of dimethylpolysiloxane (average degree of polymerization: about 450) having a vinyldimethylsiloxy group at both ends blocked by s
20 parts of side chain vinyl group-containing dimethylpolysiloxane having a viscosity at 5 ° C. of 5000 cs (average degree of polymerization: about 700, vinyl value 0.0007 mol / g), specific surface area 200 m
² parts / g of fumed silica (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.), true specific gravity 0.06, average particle size 30
μm hollow filler (Expancel Corp.
El461DE, 3 parts of a copolymer of acrylonitrile, methacrylonitrile, and vinylidene chloride) were put into a planetary mixer, and stirring was continued for 30 minutes, and then methyl hydrogen polysiloxane 5.7 represented by the above formula (3) was obtained.
Part, ethynylcyclohexanol 0.1 as a reaction control agent.
05 parts and 1 part of polyethylene glycol were added, and the resulting composition was stirred for 15 minutes to obtain a silicone rubber composition (8). The thixotropy of this composition according to the Boeing Flow Jig test was 0.65 inches.

To 114 parts of this composition, 0.1 part of a 1% isopropyl alcohol solution of chloroplatinic acid was added, and after stirring and defoaming, a 2 mm sheet was prepared by injection molding (under the same conditions as in Example 5). Its specific gravity was measured to be 0.79.

On the other hand, a 2 mm sheet was prepared from the same composition by oven curing at 150 ° C. for 15 minutes, and the specific gravity was measured. The result was 0.72, and the difference from the specific gravity at the time of injection molding was as small as 0.07. Because of the above values, the destruction of the hollow balloon by injection molding was very slight, and a cured silicone rubber having a light weight (low specific gravity) and good elasticity against compression was obtained. Note that the rubber hardness (JIS-K
6301 A type) are shown in Table 2.

[Comparative Example 3] The viscosity at 25 ° C was 5000c.
80 parts of dimethylpolysiloxane (average degree of polymerization: about 450) having a vinyldimethylsiloxy group at both ends blocked by s
20 parts of side chain vinyl group-containing dimethylpolysiloxane having a viscosity at 5 ° C. of 5000 cs (average degree of polymerization: about 700, vinyl value 0.0007 mol / g), a true specific gravity of 0.03, and a hollow filler (ex. Pancel E
xpancel 091DE-80, copolymer of acrylonitrile / methacrylonitrile / vinylidene chloride) 3
After stirring for 30 minutes, 5.7 parts of methyl hydrogen polysiloxane represented by the above formula (3), 1 part of polyethylene glycol, and 0.05 part of ethynylcyclohexanol as a reaction control agent were added. Was added and stirring was continued for 15 minutes to give a silicone rubber composition (9). The thixotropy of this composition according to the Boeing Flow Jig test was 0.63 inches.

To 110 parts of the composition, 0.1 part of a 1% isopropyl alcohol solution of chloroplatinic acid was added, and after stirring and defoaming, a 2 mm sheet was prepared by injection molding (under the same conditions as in Example 5). The specific gravity was 0.88.

On the other hand, a 2 mm sheet was prepared from the same composition by oven curing at 150 ° C. for 15 minutes, and the specific gravity was measured. The result was 0.59, and the difference from the specific gravity at the time of injection molding was as large as 0.29. Therefore, the breakage of the balloon due to injection molding was remarkable. In addition, the rubber hardness (JIS-K63) of the sheet obtained by this oven curing was used.
01 A) are shown in Table 2.

[Comparative Example 4] The viscosity at 25 ° C was 5000c.
30 parts of precipitated silica (Nipsil LP manufactured by Nippon Silica Kogyo Co., Ltd.) was added to 60 parts of dimethylpolysiloxane (average degree of polymerization: about 450) having a vinyldimethylsiloxy group blocked at both ends,
Hexamethyldisilazane (2 parts) and water (1 part) were put into a kneader mixer, and the mixture was stirred at room temperature for 1 hour.
The mixture was heated to 50 ° C., and further stirred for 3 hours. After cooling, a silicone rubber base was obtained.

The silicone rubber base (8 parts) was placed at 25 ° C.
Side chain vinyl group-containing dimethylpolysiloxane having a viscosity of 5000 cs (average degree of polymerization: about 450, vinyl value 0.0
003 mol / g) 20 parts, specific surface area 110 m ² / g
3 parts of hydrophobically treated fumed silica (R-972 manufactured by Nippon Aerosil Co., Ltd.), a hollow filler having a true specific gravity of 0.02 and an average particle size of 90 μm (Microsphere F-80ED manufactured by Matsumoto Yushi Seiyaku Co., Ltd., acrylonitrile) 2 parts of a copolymer of methacrylonitrile and vinylidene chloride) were put into a planetary mixer, and stirring was continued for 30 minutes. Then, 4.7 parts of methyl hydrogen polysiloxane represented by the above formula (3) and 1 part of polyethylene glycol were obtained. , 0.05 part of ethynylcyclohexanol as a reaction control agent was added,
The resulting composition was stirred for 15 minutes to obtain a silicone rubber composition (10). The thixotropy of this composition according to the Boeing Flow Jig test was 0.59 inches.

To 110 parts of this composition, 0.1 part of a 1% isopropyl alcohol solution of chloroplatinic acid was added, stirred, defoamed, and injection molded (under the same conditions as in Example 5) to form a 2 mm sheet. The specific gravity was 0.85.

On the other hand, a 2 mm sheet was prepared from the same composition by oven curing at 150 ° C. for 15 minutes, and the specific gravity was measured. The result was 0.57, and the difference from the specific gravity at the time of injection molding was as large as 0.28. Therefore, the breakage of the balloon due to injection molding was remarkable. In addition, the rubber hardness (JIS-K63) of the sheet obtained by this oven curing was used.
01 A) are shown in Table 2.

[0074]

[Table 2]

Claims (11)

[Claims] 1. Curable organopolysiloxane composition 1
With respect to 00 parts by weight, the average particle size is 200 μm or less,
And 0.1% of a hollow filler having an elastic property of 10% or more.
A silicone rubber composition containing a hollow filler, wherein the silicone rubber composition is blended in an amount of up to 20 parts by weight. 2. The silicone rubber composition containing a hollow filler according to claim 1, wherein the hollow filler is made of a thermoplastic resin. 3. The hollow filler is selected from a polymer of vinylidene chloride, acrylonitrile, methacrylonitrile, acrylic acid ester and methacrylic acid ester, and a copolymer of two or more of these. A silicone rubber composition containing a hollow filler. 4. The hollow filler has an average particle size of 10 to 10.
2. The film according to claim 1, wherein the thickness is 0 μm and the true specific gravity is 0.01 to 0.2.
The silicone rubber composition containing a hollow filler according to any one of claims 1 to 3. 5. A curable organopolysiloxane composition comprising: (1) 100 parts by weight of an organopolysiloxane having an average degree of polymerization of 1200 or less having at least two alkenyl groups in one molecule; Average composition formula (1) R _b H _c SiO _{(4-bc) / 2} (1) (wherein, R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms. 0.7 to 2.1, c is 0.001 to 1.0, and b + c is a positive number that satisfies 0.8 to 3.0.) 5. An addition-curable silicone rubber composition comprising 0.1 to 50 parts by weight of an organohydrogenpolysiloxane having at least two hydrogen atoms formed therein. 2. The silicone rubber composition containing a hollow filler according to claim 1. 6. The silicone rubber composition containing a hollow filler according to claim 1, which is cured and molded by injection molding. 7. (1) 100 parts by weight of an organopolysiloxane having an average of two or more alkenyl groups in one molecule and an average degree of polymerization of 1200 or less (2) The following average composition formula (1) R _b H _c SiO _{(4-bc) / 2} (1) (wherein, R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and b is 0.7 to 2.1, c Is 0.001 to 1.0, and b + c is a positive number satisfying 0.8 to 3.0.) An organo having at least two hydrogen atoms bonded to a silicon atom in one molecule. Hydrogenpolysiloxane 0.1 to 50 parts by weight (3) Addition reaction catalyst Catalyst amount (4) 0.5 to 10 parts by weight of a fine hollow filler having an average particle diameter of 20 to 60 μm. A silicone rubber composition containing a hollow filler. 8. The silicone rubber composition containing a hollow filler according to claim 7, wherein the minute hollow filler is made of a thermoplastic resin. 9. The hollow filler-containing silicone rubber composition according to claim 7, wherein the thixotropic agent is contained in an amount of 0.01 to 30 parts by weight based on 100 parts by weight of the organopolysiloxane. 10. The hollow filler-containing silicone rubber composition according to claim 7, which has a thixotropic property of sagging after 1 minute of 1 inch or less in a Boeing Flow Jig test. 11. The hollow filler-containing silicone rubber composition according to claim 7, which is cured and molded by injection molding.