JP2008260790A - Silicone rubber composition for fire-resistant construction gasket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicone rubber composition for a fire-resistant construction gasket for forming a silicone rubber for construction gasket having excellent workability, assembly processability and fire resistance. <P>SOLUTION: The silicone rubber composition for fire-resistant construction gasket comprises (A) 100 parts by mass of an alkenyl group-containing organopolysiloxane crude rubber containing two or more alkenyl groups on the average in one molecule, (B) 0.1-10 parts by mass of organohydrogenpolysiloxane having at least two hydrogen atoms bonded with silicon atoms in one molecule, (C) 30-100 parts by mass of surface-hydrophobized silica having a specific surface area of ≥100 m<SP>2</SP>/g, (D) 10-200 parts by mass of a calcium silicate filler, (E) a catalytic amount of a hydrosilylation reaction catalyst and (F) 0.01-3 parts by mass of a dialkyl peroxide, and has Williams plasticity in an uncured state of 300-700. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a silicone rubber composition for a fire-resistant building gasket, and more particularly to a heat-cured silicone rubber composition for a fire-resistant building gasket that can form a fire-resistant building gasket having good assembly workability due to high physical properties. About.

As the refractory silicone rubber composition, a silicone rubber composition comprising an organopolysiloxane raw rubber, fine silica powder, a platinum compound, and a ceramic material is known (see Patent Documents 1 to 6). However, for fireproof architectural gasket applications, further improvements have been required in terms of workability at the time of manufacturing gaskets, physical properties of fireproof gaskets, and fireproof properties. In particular, because the tear strength of silicone rubber is reduced due to the ceramicized material added in large quantities to improve fire resistance, the gasket is damaged when the fire resistant building gasket is assembled between glass and aluminum sash. There was a problem that it was easy to do. In addition, since the compression set is poor, there is also a problem that the glass retainability tends to be lowered over time.

Japanese Patent Publication No.53-15901 Japanese Patent Laid-Open No. 5-287086 JP-A-8-127716 JP 2000-169706 A JP 2001-31815 A Special table 2002-536504 gazette

An object of the present invention is to provide a silicone rubber composition for a fire-resistant building gasket that has a good workability and can form a fire-resistant building gasket having good assembly workability and fire resistance.

The present invention includes (A) 100 parts by mass of an alkenyl group-containing organopolysiloxane raw rubber having an average of two or more alkenyl groups in one molecule, and (B) an organo having at least two silicon-bonded hydrogen atoms in one molecule. 0.1 to 10 parts by mass of hydrogen polysiloxane, (C) 30 to 100 parts by mass of surface hydrophobized silica having a specific surface area of 100 m ² / g or more, (D) 10 to 200 parts by mass of calcium silicate filler, ( E) Hydrosilylation reaction catalyst (F) For fireproof construction gaskets, comprising 0.01 to 3 parts by weight of dialkyl peroxide, and having a Williams plasticity of 300 to 700 in an uncured state The present invention relates to a silicone rubber composition.

(A) The alkenyl group-containing organopolysiloxane raw rubber is the main component of the composition of the present invention, and has at least two silicon atom-bonded alkenyl groups on average in one molecule. Examples of the alkenyl group include a vinyl group, an allyl group, and a propenyl group. Examples of the organic group other than the alkenyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, and a dodecyl group. Alkyl groups such as phenyl groups; aryl groups such as phenyl groups and tolyl groups; aralkyl groups such as β-phenylethyl groups; halogen-substituted alkyl groups such as 3,3,3-trifluoropropyl groups and 3-chloropropyl groups. It is done. Moreover, you may have a small amount of hydroxyl groups at the molecular chain end. The molecular structure of the component (A) is preferably linear, but may be linear including a branch. Two or more alkenyl group-containing organopolysiloxanes may be used in combination. The property of the component (A) is raw rubber, and the molecular weight of the component (A) is preferably in the range of 200,000 to 700,000 in terms of polystyrene-reduced number average molecular weight by gel permeation chromatography (GPC). .

(B) The organohydrogenpolysiloxane having a silicon atom-bonded hydrogen atom is a cross-linking agent of the composition of the present invention, and is subjected to an addition reaction with the component (A) in the presence of the (E) hydrosilylation reaction catalyst described later. It functions to crosslink and cure the inventive composition. Such silicon-bonded hydrogen atom-containing organohydrogenpolysiloxanes include trimethylsiloxy group-capped methylhydrogen polysiloxanes at both ends, trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymers at both ends, and dimethylhydrogensiloxy at both ends. Capped dimethylsiloxane / methylhydrogensiloxane copolymer, dimethylphenylsiloxy group-capped methylphenylsiloxane / methylhydrogensiloxane copolymer, cyclic methylhydrogenpolysiloxane, dimethylhydrogensiloxane unit and SiO _4/2 unit The copolymer which consists of is mentioned. Two or more organohydrogenpolysiloxanes may be used in combination.

(B) The compounding quantity of a component is 0.1-10 mass parts with respect to 100 mass parts of (A) component, Preferably it is the range of 0.3-5 mass parts. The molar ratio between the silicon-bonded hydrogen atom in the component (B) and the alkenyl group in the component (A) is preferably an amount that is (0.5: 1) to (10: 1). 1) to (5: 1) is more preferable.

(C) Surface hydrophobized silica acts to impart excellent mechanical strength to silicone rubber obtained by heat-curing the composition of the present invention. As component (C), the surface of fine powdery reinforcing silica such as dry method silica such as fumed silica or wet method silica such as precipitated silica, organochlorosilane, organoalkoxysilane, hexaorganodisilazane, diorgano The thing hydrophobized surface treatment with the siloxane oligomer etc. is illustrated. Among these, surface-hydrophobized silica obtained by surface-treating dry silica with a cyclic diorganosiloxane oligomer is preferable. The BET specific surface area of (C) component needs to be 100 m < ² > / g or more. When the BET specific surface area of the component (C) is less than 100 m ² / g, the silicone rubber obtained by heat-curing the composition of the present invention does not have the desired physical strength. (C) The compounding quantity of a component is 30-100 mass parts with respect to 100 mass parts of (A) component.

The surface hydrophobized silica obtained by subjecting the dry process silica to a surface treatment with a cyclic diorganosiloxane oligomer is a dry process silica hydrophobized with a cyclic dimethylsiloxane oligomer, and its BET specific surface area is 100 to 400 m ² / g. The bulk density is 70 to 200 kg / m ³ , the carbon atom content is 1.7 to 4.0% by mass, and the water content measured by the Karl Fischer method is 0.30% by mass or less, The hexane extraction rate is preferably 3.0% by mass or less. Furthermore, the bulk density is 80 to 150 kg / m ³ , the carbon atom content is 1.8 to 3.5% by mass, and the water content measured by the Karl Fischer method is 0.25% by mass or less. More preferably, the hexane extraction rate is 2.5% by mass or less.

As for the bulk density, hydrophobized dry process silica is charged into a 1 L (1000 cc) graduated cylinder up to a scale of 1000 cc. At this time, since the dry process silica settles, the dry process silica is replenished so that the volume thereof is maintained at 1000 cc for 3 minutes after the addition. Thereafter, after 3 minutes, the weight (g number) of the dry silica in the graduated cylinder is measured. The measured value is expressed in kg / m ³ to obtain the bulk density.
The carbon atom content is converted to carbon dioxide by thermally decomposing silicon atom-bonded methyl groups of hydrophobized dry silica in an oxygen atmosphere at 1000 ° C, and the amount of carbon in this carbon dioxide is analyzed by trace carbon analysis. Quantify by instrument.

The moisture content measured by the Karl Fischer method is obtained by drying the hydrophobized dry-process silica in an oven at 110 ° C. for 10 hours, and then measuring the moisture content of the dry-process silica after drying by the Karl Fischer method.
The hexane extraction rate was determined by measuring the carbon atom content (b) before hexane extraction and the carbon atom content (a) after hexane extraction of hydrophobized dry silica, and (b−a) / b × Calculated by 100 (unit%). Hydrophobized dry method silica after hexane extraction was placed in a 500 cc flask equipped with a stirrer and a reflux condenser, and hydrophobized dry method silica 20 g and n-hexane 150 g were boiled for 30 minutes and then filtered. It was prepared by.
The carbon atom content indicates the degree of treatment or the degree of hydrophobicity of the dry silica surface hydrophobized with a hydrophobizing agent such as a cyclic dimethylsiloxane oligomer. The hexane extraction rate indicates the content of a hydrophobizing agent such as a cyclic dimethylsiloxane oligomer adhering without being bonded to dry silica. A small hexane extraction rate even though the carbon atom content is large is considered to be a large degree that the cyclic dimethylsiloxane oligomer is chemically bonded to the dry silica.

As the cyclic diorganosiloxane oligomer used for the hydrophobization treatment of the dry silica, a cyclic dimethylsiloxane oligomer is preferable, and octamethylcyclotetrasiloxane, decamethylpentasiloxane, dodecamethylcyclohexasiloxane, tetradecamethylcycloheptasiloxane, hexa Examples thereof include methylcyclotrisiloxane and a mixture thereof. The upper limit of the degree of polymerization is preferably a 20-mer, more preferably a 10-mer. A method of hydrophobizing a dry process silica with a cyclic diorganosiloxane oligomer is known (for example, Japanese Patent Publication No. 36-15938, US Patent Publication No. 2930809, Japanese Patent Publication No. 5-25893), and a dry process silica. Is heated with a liquid cyclic dimethylsiloxane oligomer for a predetermined time. In Japanese Patent Publication No. 5-25893, a bulk density increasing process is also performed.

The (D) component calcium silicate filler used in the present invention functions to impart fire resistance to the silicone rubber obtained by heat-curing the composition of the present invention. Such calcium silicate fillers are commercially available as wollastonite, zonotolite, tobermorite, etc., and typically have an aspect ratio of 2: 1 or more, but if the aspect ratio is too high, the surface smoothness of the molded product is reduced. Since it may be lost, the aspect ratio is preferably in the range of 2: 1 to 5: 1. The average particle length of the component (D) is preferably 1 to 100 μm, more preferably 5 to 50 μm, and wollastonite is particularly preferable. This is because the silicone rubber obtained by curing the composition of the present invention has good fire resistance and physical properties. Wollastonite is available from NYCO® Minerals, Inc. Supplied by Willsboro NY or JFE Minerals. (D) The compounding quantity of a component is 10-200 mass parts with respect to 100 mass parts of (A) component, Preferably it is 30-100 mass parts.

(E) The hydrosilylation reaction catalyst is an addition reaction catalyst for crosslinking the component (A) and the component (B) by an addition reaction to cure the composition of the present invention. As such a hydrosilylation reaction catalyst, a conventionally known hydrosilylation reaction catalyst can be used. For example, chloroplatinic acid, an alcohol solution of chloroplatinic acid, chloroplatinic acid and olefins, vinylsiloxane or acetylene compound Complex catalysts, platinum black, platinum catalysts such as platinum supported on a solid surface; palladium catalysts such as tetrakis (triphenylphosphine) palladium; rhodium catalysts such as chlorotris (triphenylphosphine) rhodium; Examples are microcapsules in which the hydrosilylation reaction catalyst is encapsulated in a thermoplastic resin such as a silicone resin having a softening point or a melting point. Among these, a platinum-based catalyst is preferable, and since the storage stability is improved, a microcapsule in which the platinum-based catalyst is sealed in a silicone resin having a softening point or a melting point is particularly preferable. (E) The compounding quantity of a component should just be an amount required in order to harden this invention composition, ie, a catalyst amount, and is the range of 1-500 ppm as a metal amount with respect to 100 mass parts of (A) component. Is preferable, and the range of 10 to 100 ppm is particularly preferable.

(F) Dialkyl peroxide functions to improve mechanical physical properties such as compression set and tear strength of silicone rubber obtained by curing the composition of the present invention. Examples of the dialkyl peroxide include dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and t-butylperbenzoate. (F) The compounding quantity of a component is 0.01-3 mass parts, and it is preferable that it is the range of 0.1-2 mass parts.

The Williams plasticity specified in JIS K6249 in the uncured state of the composition of the present invention needs to be in the range of 300 to 700. If the Williams plasticity is less than 300, when a gasket having a complicated shape is formed, the gasket is deformed before being cured in the vulcanizing tank after being discharged from the die of the extruder, and a desired shape is obtained. This is because the surface of the molded product may be roughened. On the other hand, if the Williams plasticity exceeds 700, pulsation may occur during extrusion and the discharge processability may deteriorate, resulting in a decrease in production efficiency.

The crescent-type tear strength defined in JIS K6252 of the silicone rubber obtained by curing the composition of the present invention is preferably 20 N / mm or more, and particularly preferably 25 N / mm or more. This is because when the composition of the present invention is molded into a fireproof architectural gasket and incorporated into glass and an aluminum sash, the gasket is less likely to break, and the gasket can be made thinner. Moreover, it is preferable that the compression set prescribed | regulated to JISK6262 of the silicone rubber obtained by hardening | curing this invention composition is 30% or less. This is because the gasket can be prevented from being deformed when the composition of the present invention is molded and stored in a fireproof architectural gasket, and when the gasket is incorporated into glass and an aluminum sash, it can be used for a long period of time. This is because it can be expected to maintain good glass retention and prevent formation of a gap between the glass and maintain good fire resistance for a long period of time.

The composition of the present invention comprises the components (A) to (F) as described above, but in addition to these, various additives that are known to be added to and blended with ordinary silicone rubber compositions are added. Doing so does not interfere with the object of the present invention. Examples of such additives include inorganic fillers such as diatomaceous earth, quartz powder, lime powder, titanium oxide, carbon black, and petal; heat-resistant agents such as rare earth oxides, cerium silanolate, and cerium fatty acid salts; acetylene alcohol Compounds, phenyl alcohol compounds, benzotriazole, methyltris (methylisobutynoxy) silane and other hydrosilylation reaction curing retarders; both-end silanol-blocked dimethylsiloxane oligomer, both-end silanol-blocked dimethylsiloxane / methylvinylsiloxane oligomer, both Examples include silicone rubber plasticizers that act as silica dispersants such as terminal silanol-blocked methylphenylsiloxane oligomers and single-end silanol-blocked long-chain alkylsilane coupling agents.

The composition of the present invention can be produced by uniformly kneading and blending predetermined amounts of the above components (A) to (F) with a two-roll, kneader, Banbury mixer or the like. Next, a fireproof silicone rubber building gasket can be obtained by extruding the composition of the present invention into a gasket shape through an extruder provided with a predetermined die and passing it through a hot air vulcanizer heated to 200 to 500 ° C.

EXAMPLES Next, although an Example demonstrates this invention, this invention is not limited to this. In the examples, parts are parts by mass, and the viscosity is a measured value at 25 ° C. Moreover, the Williams plasticity at the time of non-hardening of the silicone rubber composition for fireproof building gaskets was measured according to JIS K6249, and the tear strength crescent type was measured according to JIS K6252. The compression set was measured under the condition of 25% compression at 180 ° C. for 22 hours in accordance with JIS K6262 using a test piece in which 6 sheets each having a thickness of 2 mm were stacked.
[Roll workability]
When the silicone rubber composition is kneaded with two rolls, the case where there is no stickiness and the workability is good is ○, the case where there is a sticky feeling and the workability is slightly inferior, the stickiness is extremely difficult and the normal work is difficult The case of x was evaluated as x.
[Assembly processability]
When a fireproof silicone rubber building gasket is assembled between a glass plate and an aluminum sash and a simulated glass window is assembled in combination with a concrete frame, ○ if the simulated glass window is successfully assembled, cracks in part of the gasket Assembling workability was evaluated by △ when the case was recognized, and x when the gasket was broken and could not be assembled.
[Fire resistance]
Using a test apparatus in accordance with JIS-A-1304 (fire resistance test method for building structure part), a 20-minute heat resistance test is conducted. A case where the fireproof performance was insufficient such as penetration or a gasket falling off was evaluated as x.

[Example 1]
A kneader mixer containing 99.63 mol% of dimethylsiloxane units and 0.37 mol% of methylvinylsiloxane units, and a dimethylsiloxane / methylvinylsiloxane copolymer raw rubber having several molecular chain ends blocked with dimethylvinylsiloxy groups (several Hydrophobic surface-hydrophobic surface obtained by hydrophobizing 100 parts of an average molecular weight of 320,000), 2.0 parts of silanol-group-blocked dimethylsiloxane oligomer with a viscosity of 40 mPa · s, and a dry process silica having a specific surface area of 200 m ² / g with a cyclic organosiloxane oligomer. Treated silica (manufactured by silica manufacturer, BET specific surface area 160 m ² / g, carbon atom content 2.0 mass%, bulk density 100 kg / m ³ , moisture content 0.10 mass%, hexane extraction rate 1.8 mass% ) 50 parts, 50 parts of wollastonite (average particle length 30 μm, aspect ratio 2.9) To obtain a 1 hour mixing silicone rubber base was. Next, the obtained silicone rubber base was prepared by using two rolls and a methyl hydrogen polysiloxane having a viscosity of 7 Pa · s and having a molecular chain terminal blocked with a trimethylsiloxy group (silicon-bonded hydrogen atom content 1.5 (Mass%) 2.0 parts, a platinum catalyst obtained by microencapsulating a complex of chloroplatinic acid and divinyltetramethyldisiloxane with a silicone resin having a softening point of 110 ° C. to give 30 ppm as the amount of platinum metal, 3-methyl- 100 parts of 1-butyn-3-ol and 0.3 parts by mass of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as a dialkyl peroxide were mixed to obtain a silicone rubber composition. The roll workability at the time of mixing the obtained silicone rubber composition with two rolls was determined, and Williams plasticity was measured.

Next, the obtained silicone rubber composition was put into a 65 mmφ single screw extruder and extruded into a shape of a bowl shape (height 20 mm, width 30 mm, side thickness 2 mm, bottom thickness 1 mm), This was introduced into a hot air vulcanizing tank (HAV) and cured by heating at 350 ° C. for 2 minutes to obtain a refractory silicone rubber building gasket. This fire-resistant silicone rubber building gasket was assembled between a glass plate and an aluminum sash and combined with a concrete frame to produce a simulated glass window. At this time, assembly workability was evaluated. Furthermore, the fire resistance of the simulated glass window was evaluated. These results are shown in Table 1.

Further, the obtained silicone rubber composition was put into a 65 mmφ single screw extruder and extruded into a sheet shape having a thickness of 2 mm, and this was introduced into a hot air vulcanizing tank (HAV), and the condition for 2 minutes at 350 ° C. A silicone rubber test piece was obtained by heat-curing under. A crescent-type tear strength measurement dumbbell was punched out from the silicone rubber test piece, and the tear strength was measured. Further, compression set was measured using a test piece in which six pieces of this silicone rubber test piece were stacked.

[Comparative Examples 1-4]
In Example 1, a silicone rubber composition (Comparative Example 1) prepared in the same manner except that no dialkyl peroxide was used, and a silicone rubber composition prepared in the same manner except that wollastonite was changed to quartz powder. (Comparative Example 2), a silicone rubber composition (Comparative Example 3) prepared in the same manner except that the wollastonite was changed to mica powder, a dry process silica (BET specific surface area) in which the surface hydrophobized silica was not surface-treated 200 m ² / g), and the silicone rubber composition (Comparative Example 4) prepared in the same manner except that the blending amount of the silanol group-blocked dimethylsiloxane oligomer having a viscosity of 40 mPa · s was changed to 10 parts. Evaluate plasticity, roll workability, crescent tear strength, compression set, assembly workability, fire resistance , I wrote them in Table 1.

The silicone rubber composition for fire-resistant building gaskets of the present invention has good processing workability, and its cured product has good assembly workability and excellent fire resistance. For example, it can be suitably used for fireproof window frame gaskets for construction.

Claims (4)

(A) 100 parts by mass of an alkenyl group-containing organopolysiloxane raw rubber having an average of two or more alkenyl groups in one molecule, (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule 0.1 to 10 parts by mass, (C) 30 to 100 parts by mass of surface hydrophobized silica having a specific surface area of 100 m ² / g or more, (D) 10 to 200 parts by mass of calcium silicate filler, (E) hydrosilylation Reaction catalyst Catalyst amount, 0.01 to 3 parts by mass of (F) dialkyl peroxide, Williams plasticity in uncured state is 300 to 700, Silicone rubber composition for fireproof architectural gasket . The surface hydrophobized silica is a dry process silica hydrophobized by a cyclic diorganosiloxane oligomer, the BET specific surface area is 100 to 400 m ² / g, the bulk density is 70 to 200 kg / m ³ , Hydrophobization having a carbon atom content of 1.7 to 4.0% by mass, a water content measured by Karl Fischer method of 0.30% by mass or less, and a hexane extraction rate of 3.0% by mass or less. 2. The silicone rubber composition for a fire-resistant architectural gasket according to claim 1, which is treated dry silica. 3. The silicone rubber composition for a fire resistant architectural gasket according to claim 1, wherein the calcium silicate filler is wollastonite. The crescent-type tear strength defined by JIS K6252 of silicone rubber obtained by curing the silicone rubber composition for fire-resistant building gaskets is 20 N / mm or more. A silicone rubber composition for a fire-resistant building gasket as described in the above item.