JP5734567B2 - Room temperature curable polyorganosiloxane composition - Google Patents

Description

  The present invention relates to a room temperature curable polyorganosiloxane composition. More specifically, the present invention is stable under a sealed condition in the absence of moisture, and cures at room temperature by contact with moisture in the air to form a rubber-like elastic body. The present invention relates to a polyorganosiloxane composition which is useful as an elastic adhesive or a sealing material.

  Conventionally, a polyorganosiloxane having a hydroxyl group at the end of the molecular chain is blended with a mixture or reaction product of an alkoxysilane having an alkoxy group and an alkoxysilane having an aminoalkyl group, and a curing catalyst. A polyorganosiloxane composition having adhesion to various substrates is known (for example, see Patent Document 1). However, the silicone rubber obtained by curing this composition has a low water-resistant adhesive property, and has a drawback that the adhesive property is lowered particularly in a severe environment such as hot water immersion in float glass.

  In order to improve the strength of the cured product, a composition in which calcium carbonate surface-treated with a fatty acid using hydrogenated castor oil as a raw material is blended with a polyorganosiloxane having a hydroxyl group at the molecular chain end has been proposed. (For example, refer to Patent Document 2), but the demand for durability could not be satisfied sufficiently. Moreover, although the composition which improved durability by mix | blending the calcium carbonate surface-treated with rosin acid is proposed (for example, refer patent document 3), this composition is dischargeability etc. from high viscosity. However, it was difficult to satisfy the requirements in terms of adhesiveness. Furthermore, it has been proposed to blend calcium carbonate surface-treated with both fatty acid and rosin acid (see, for example, Patent Document 4), but the current situation is that the problem of improving water resistance has not been solved. It was.

Japanese Patent Publication No. 63-23226 Patent registration 2675626 Patent registration 2784045 JP 11-302544 A

  The present invention has been made to solve such problems, and provides a room temperature curable polyorganosiloxane composition having excellent water resistance and particularly improved adhesion and mechanical strength reduction due to immersion in hot water. For the purpose.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have achieved excellent room temperature curing by blending calcium carbonate surface-treated with a fatty acid having a branched alkyl group as a filler. The present invention was completed by finding that a functional organopolysiloxane composition can be obtained.

The room temperature curable polyorganosiloxane composition of the present invention has (A) a polyorganosiloxane 100 in which the molecular chain terminal is blocked with a hydroxyl group or a hydrolyzable group, and the viscosity at 23 ° C. is 20 to 1,000,000 mPa · s. 1 part by weight of calcium carbonate surface-treated with a fatty acid having a branched alkyl group or a salt thereof as (B) a filler, (C) 0.001 to 10 parts by weight of a curing catalyst, (D) amino 0.05 to 10 parts by weight of an alkylalkoxysilane, 10 parts by weight or less of an alkoxysilane having an epoxy group, 0.1 to 20 parts by weight of 2-ethylhexyltrimethoxysilane and / or 0.1 to 20 of 2-octyldecyltrimethoxysilane Each part includes a weight part .

  The room temperature curable polyorganosiloxane composition of the present invention is excellent in ejection properties, and has good slump resistance (anti-sagging) and thixotropy. And according to this composition, the hardened | cured material which shows favorable adhesiveness with respect to various base materials, is excellent in mechanical strength, and was excellent in warm water resistance.

  Embodiments of the present invention will be described below. The room temperature curable polyorganosiloxane composition of the embodiment includes (A) a polyorganosiloxane having a molecular chain terminal blocked with a hydroxyl group or a hydrolyzable group, and a viscosity at 23 ° C. of 20 to 1,000,000 mPa · s. And (B) calcium carbonate surface-treated with a fatty acid having a branched alkyl group or a salt thereof as a filler, and (C) a curing catalyst, respectively, and (B) component with respect to 100 parts by weight of component (A) 1 to 400 parts by weight and (C) component 0.001 to 10 parts by weight are blended. Hereinafter, each component of the room temperature curable polyorganosiloxane composition of the embodiment will be described.

  The component (A) is a polyorganosiloxane whose molecular chain end is blocked with a hydroxyl group (hydroxyl group) or a hydrolyzable group, and is a base component of the room temperature curable composition of the present invention. If the viscosity of the component (A) is too low, the rubber elasticity after curing becomes poor, and if it is too high, the workability decreases, so the viscosity at 23 ° C. is preferably in the range of 20 to 1,000,000 mPa · s. A range of 100 to 100,000 mPa · s is preferable.

The molecular structure of the polyorganosiloxane is preferably a straight chain represented by the following general formula (1), but may have a partially branched structure.

In formula (1), R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different from each other, and R ² is _a monovalent organic group represented by —ZSiR ³ _3-a Xa. Represents a group. Here, Z represents oxygen (oxo group) or a divalent hydrocarbon group, and R ³ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same as or different from each other. X represents a hydroxyl group (hydroxyl group) or a hydrolyzable group, and a is an integer of 1 to 3. Moreover, n is a number which makes the viscosity at 23 degreeC of the said (A) component the range of 20-1,000,000 mPa * s.

R ¹ includes methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, alkyl group such as dodecyl group; alkenyl group such as vinyl group and allyl group; phenyl group And aryl groups such as tolyl group and xylyl group; and aralkyl groups such as 2-phenylethyl group and 2-phenylpropyl group. In addition, hydrogen atoms of these hydrocarbon groups are substituted with other atoms or groups, that is, halogens such as chloromethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group A substituted hydrocarbon group such as a cyanoalkyl group such as a 3-cyanopropyl group. It is easy to synthesize, and the component (A) has a low viscosity with respect to the molecular weight, gives good extrudability to the composition before curing, and gives good physical properties to the composition after curing. it from is preferably 85% or more of the total R ¹ is a methyl group, and more preferably substantially all R ¹ is a methyl group.

In particular, when imparting heat resistance, radiation resistance, cold resistance or transparency to the composition, a necessary amount of phenyl groups as part of R ¹ , when imparting oil resistance and solvent resistance, When a 3,3,3-trifluoropropyl group or 3-cyanopropyl group is provided as a part of R ¹ or a surface having paintability is provided, a long chain alkyl group or an aralkyl group is provided as a part of R ^1. Can be arbitrarily selected depending on the purpose, for example, in combination with a methyl group.

The terminal group R ^{2 of the} component (A) is represented by the formula: —ZSiR ³ _3-a X _a and is a silicon functional siloxy having at least one hydroxyl group (hydroxyl group) or hydrolyzable group X which is a silicon functional group. Unit. Therefore, the component (A) of the embodiment has at least one hydroxyl group (hydroxyl group) or hydrolyzable group X at both ends of the molecule.

In the terminal group R ² , R ³ bonded to the silicon atom is a substituted or unsubstituted monovalent hydrocarbon group which may be the same as or different from each other, and examples thereof are the same as those described above for R ¹ . It may be the same as or different from R ¹ . A methyl group or a vinyl group is preferred because synthesis is easy and the reactivity of the hydrolyzable group X is excellent. Z is a divalent oxygen (oxy group) or a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include an alkylene group such as a methylene group, an ethylene group and a trimethylene group; a phenylene group and the like. Is done. From the viewpoint of easy synthesis, an oxy group or an ethylene group is preferable, and an oxy group is particularly preferable.

X is a hydroxyl group (hydroxyl group) or hydrolyzable group which is a silicon functional group present in at least one R ² which is a terminal group. Examples of the hydrolyzable group include an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group; a substituted alkoxy group such as a 2-methoxyethoxy group and a 2-ethoxyethoxy group; an enoxy group such as an isopropenoxy group, Examples thereof include a ketoximato group such as a methyl ethyl ketoxime group and an acetoxy group. The plurality of hydroxyl groups or hydrolyzable groups may be the same or different. An alkoxy group or a ketoximato group is preferred because it is easily synthesized, has physical properties before being cured, is stable during storage, is curable, is economical, and is used in a wide range of applications.

In the end groups R ^2, number a hydroxyl or hydrolyzable group X is a silicon functional group is preferably 1-3. A silicon-functional polydiorganosiloxane in which X is a hydroxyl group is a ring-opening polymerization or ring-opening copolymerization of a cyclic diorganosiloxane low monomer such as octamethylcyclosiloxane in the presence of water using an acidic catalyst or an alkaline catalyst. And by introducing a hydroxyl group bonded to a silicon atom into the terminal of the linear polydiorganosiloxane.

The silicon-functional polydiorganosiloxane in which X is a hydrolyzable group can be synthesized, for example, by condensing a silane having two or more arbitrary hydrolyzable groups to a polyorganosiloxane having a hydroxyl group at the terminal. it can. In this case, since one hydrolyzable group possessed by the silane is consumed by the condensation reaction, the number of X in the terminal group R ² of the polyorganosilosan obtained by the reaction is the hydrolyzable group-containing silane used. One less than the number of hydrolyzable groups possessed by.

  Specific examples of the component (A) include dimethylpolysiloxane, methylethylpolysiloxane, methyloctylpolysiloxane, methylvinylpolysiloxane, methyl group whose molecular chain ends are blocked with a hydroxyl group or a hydrolyzable group (for example, alkoxyl group). Phenylpolysiloxane, methyl (3,3,3-trifluoropropyl) polysiloxane, copolymer of dimethylsiloxane and methylphenylsiloxane, copolymer of dimethylsiloxane and methyl (3,3,3-trifluoropropyl) siloxane Etc.

  Examples of molecular chain ends blocked with a hydroxyl group include dimethylhydroxysiloxy group and methylphenylhydroxysiloxy group. Examples of molecular chain ends blocked with an alkoxy group include vinyldimethoxysiloxy group, methyldimethoxysiloxy group, trimethoxy group. Examples include a siloxy group, a methyldiethoxysiloxy group, and a triethoxysiloxy group. Furthermore, examples of the molecular chain end blocked with a ketoximato group include a methyl ethyl ketoximato group, a dimethyl ketoximato group, a diethyl ketoximato group, a methylbutyl ketoximato group, a methylhexyl ketoximato group, and an ethylpentyl ketoximato group. The

  In an embodiment of the present invention, (B) calcium carbonate surface-treated with a fatty acid having a branched alkyl group or a salt thereof is a reinforcing filler, and has high fluidity and consistency in the composition before curing. Imparts slump resistance and thixotropy. Moreover, high mechanical strength can be provided to hardened | cured material by the mixing | blending of this (B) component.

  As calcium carbonate, both heavy calcium carbonate and synthetic (light) calcium carbonate can be used. The particle size (average particle size) of calcium carbonate is preferably in the range of 0.01 to 50 μm. In addition, although the value of this average particle diameter is a value measured by the image analysis by an electron microscope, the average particle diameter calculated | required from the average particle diameter converted from the specific surface area and the 50% diameter by weight conversion from a particle size distribution. It may be a diameter or an average particle diameter measured by a laser diffraction / scattering method. From the viewpoint of the mechanical strength of the obtained cured product, a more preferable range of the particle size (average particle size) of calcium carbonate is 0.01 to 15 μm as measured by an electron microscope, and the weight of the particle size distribution is 50%. The value from the diameter ranges from 0.01 to 40 μm, the value converted from the BET specific surface area ranges from 0.01 to 20 μm, and the value converted from the air permeation method specific surface area ranges from 0.01 to 25 μm. . When the average particle diameter of calcium carbonate exceeds 50 μm, not only the mechanical properties of the cured product are deteriorated, but also the extensibility of the cured product is not sufficient. On the other hand, when the average particle size is less than 0.01 μm, the viscosity of the composition before curing is remarkably increased and the fluidity is lowered, which is not preferable.

  Examples of the fatty acid having a branched alkyl group that treats the surface of calcium carbonate include fatty acids having a branched alkyl group having 6 to 20 carbon atoms. Specific examples include isostearic acid, 2-ethylbutanoic acid, 2-ethylhexanoic acid, isopalmitic acid, 2-butylhexanoic acid, octyldodecanoic acid, and the like. If the number of carbon atoms in the fatty acid is too large, the surface treatment property is poor, which may cause deterioration. If the number of carbon atoms is too small, it is difficult to obtain desired water resistance. Therefore, it is preferable to use isostearic acid among the fatty acids from the viewpoint of excellent water resistance and good surface treatment. Isostearic acid also has the advantage of being easily available industrially and economically. Metal salts such as sodium salts, potassium salts and calcium salts of the fatty acids can also be used as the surface treatment agent.

  The blending amount of the calcium carbonate surface-treated with the fatty acid (including the salt thereof) having a branched alkyl group as the component (B) is 1 to 400 parts by weight with respect to 100 parts by weight of the component (A). When the blending amount of the component (B) is less than 1 part by weight, the cured product obtained from the composition has remarkably inferior mechanical strength such as hardness and tensile strength, and when it exceeds 400 parts by weight, it has good rubber elasticity. Not only is it difficult to obtain a product, but the viscosity of the composition increases, which may make the operation difficult.

  The curing catalyst that is the component (C) of the embodiment is a catalyst that promotes the condensation reaction of the hydroxyl group (hydroxyl group) and / or the hydrolyzable group of the component (A) and promotes the curing of the composition. Specifically, metal organic acid salts such as iron octoate, iron naphthenate, cobalt octoate, cobalt naphthenate, tin octoate, tin naphthenate, lead octoate, lead naphthenate; dibutyltin diacetate, dibutyltin dilaurate, Alkyltin ester compounds such as dibutyltin octoate; diketonate metal salts such as dibutyltin bis (acetyl acetate), dibutyltin bis (ethylacetylacetate), dibutyltin bis (butylacetylacetate), dibutyltin bis (2-ethylhexylacetylacetate); Metal alcoholates such as tin halide compounds, tin ortho ester compounds, tetrabutyl titanate, tetrabutyl zirconate; diisopropoxybis (acetylacetonate) titanium, diisopropo Shibisu titanium chelate compounds such as (ethyl acetoacetate) titanium; diethylhydroxylamine, dimethylhydroxylamine, amines such as γ- tetramethylguanidylpropyltrimethoxysilane trimethoxysilane can be exemplified. These can be used alone or as a mixture of two or more.

  (C) The compounding quantity of the curing catalyst which is a component shall be 0.001-10 weight part with respect to 100 weight part of (A) component, More preferably, you may be 0.01-5 weight part. When the component (C) is less than 0.001 part by weight, the curing rate is too slow to be suitable for practical use, and it takes a long time to form a tack-free film when the composition is exposed to air, and rubber. Strength development may be deteriorated. On the other hand, when the amount of component (C) exceeds 10 parts by weight, the film formation time is extremely short, such as a few seconds, so that workability is lowered and heat resistance may be lowered.

  In the embodiment of the present invention, it is preferable to blend (D) aminoalkylalkoxysilane together with the components (A) to (C). (D) Aminoalkylalkoxysilane works as a cross-linking agent and promotes the curing of the composition, and is effective in improving adhesion to a substrate, particularly in adhesion durability under severe conditions such as immersion in warm water. Have.

  (D) As aminoalkylalkoxysilane, aminomethyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, N- (2-ethyl) aminopropyltri Methoxysilane, N- (2-aminoethyl) aminomethyltributoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane , 3-anilinopropyltriethoxysilane and the like.

  (D) It is preferable that the compounding quantity of aminoalkyl alkoxysilane shall be 0.05-10 weight part with respect to 100 weight part of polyorganosiloxane which is (A) component, More preferably, it is 0.05-5 weight part. And

  The room temperature curable polyorganosiloxane composition of the embodiment may further contain an alkoxysilane containing an epoxy group in an amount of 10 parts by weight or less based on 100 parts by weight of the component (A). When the compounding amount of the epoxy group-containing alkoxysilane exceeds 10 parts by weight, not only the development of curing and adhesiveness is delayed, but also the viscosity of the composition is increased and the workability such as dischargeability is lowered, and further after the curing The rubber may become too hard. Examples of the epoxy group-containing alkoxysilane include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4- Epoxycyclohexyl) ethylmethyldimethoxysilane and the like are exemplified. As will be described later, in the composition containing carbon black as a colorant, by adding an epoxy group-containing alkoxysilane, a slight black fading can be seen, but the adhesion reliability during water immersion can be further improved. There is an effect.

  Furthermore, the composition of the embodiment includes an alkoxysilane different from the epoxy group-containing alkoxysilane or the aminoalkylalkoxysilane as the component (D) as a crosslinking agent in order to adjust curability and rubber strength after curing. Can be added. Examples of such alkoxysilanes include tetrafunctional silanes such as tetramethoxysilane, tetraethoxysilane, methyl cellosolve orthosilicate, and n-propyl orthosilicate; methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, 2 -Ethylhexyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltrimethoxyethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, dodecyltrimethoxysilane, hexadecyltrimethoxysilane, hexyltriethoxysilane, octyltri Trifunctional alkoxysilanes such as ethoxylane and dodecyltriethoxysilane; methyltris (methylethylketoxymato) silane, methyltris ( Tylethyl ketoximato) silane, vinyl tris (methyl ethyl ketoximato) silane, phenyl tris (methyl ethyl ketoximato) silane, methyl tris (methyl butyl ketoximato) silane, vinyl tris (methyl butyl ketoximato) silane, phenyl tris (methyl butyl ketoximato) Examples thereof include ketoxymatosilanes such as silane, tetrakis (methylethylketoxymato) silane, and tetrakis (methylbutylketoxymato) silane. The compounding amount of these alkoxysilanes is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the component (A).

  Furthermore, an organic solvent and a diluent (plasticizer) can be blended with the polyorganosiloxane composition of the embodiment as necessary. As the diluent, polydimethylsiloxane having both ends trimethylsiloxylated, polydimethylsiloxane having both ends dimethylvinylsiloxylated, or the like can be used. In addition, a colorant such as carbon black, a flame retardant, a thixotropic agent, an adhesion improver (adhesion promoter), an antifungal agent, and the like may be added as long as the object of the present invention is not impaired.

  The room temperature curable polyorganosiloxane composition of the present invention is a one-part type room temperature curable by uniformly mixing each component of (A) to (C) and other components described above in a dry atmosphere. It can be obtained as a composition. When this composition is exposed to air, the crosslinking reaction proceeds due to moisture, and the composition is cured into a rubber elastic body. Also, a two-component room temperature curable composition comprising a main agent composed of component (A) and component (B) and a curing agent composed of component (C) and component (D). It can also be prepared as a product. In the two-component composition, the main agent and the curing agent are mixed in the air to cure in the same manner as the one-component room temperature curable composition, and a cured product having rubber elasticity is obtained.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to a following example. In the examples, “parts” means “parts by weight”, and “%” means “% by weight”. Moreover, all physical properties such as viscosity are measured values at 23 ° C. and relative humidity (RH) 50%.

Reference example 1
Synthetic calcium carbonate surface-treated with isostearic acid on 50 parts of α, ω-dihydroxypolydimethylsiloxane (viscosity 10,000 mPa · s) blocked at both ends of the molecular chain with a hydroxyl group. Calfine 500B (trade name; manufactured by Maruo Calcium Co., Ltd.) (average particle diameter 0.05 μm, BET specific surface area 17 m ² / g measured by electron microscopy) is added. And mixed to make the main agent.

  Further, 58 parts of α, ω-divinylpolydimethylsiloxane (viscosity 1,000 mPa · s) having vinyldimethylsilyl groups at both ends, 10 parts of N- (2-ethyl) aminopropyltrimethoxysilane, and carbon black VULCAN XC72 (trade name; average particle diameter measured by electron microscopy: 30 nm; manufactured by CABOT) 15 parts, n-propyl orthosilicate 15 parts, and dioctyltin dilaurate 2.0 parts were added and mixed to cure this. An agent was used.

  The main agent and the curing agent thus obtained were mixed at a weight ratio of 100: 10 to obtain a polyorganosiloxane composition.

Reference Example 2, Examples 3 to 9
Main agents and curing agents were prepared in the same manner as in Reference Example 1 except that the types and amounts of the components to be blended were changed as shown in Table 1. In addition, as heavy calcium carbonate surface-treated with isostearic acid, Super 2000B (trade name; manufactured by Maruo Calcium Co., Ltd.) (air permeability method specific surface area 2.0 m ² / g, average particle converted from specific surface area) ESD-2 (trade name; manufactured by Sankyo Flour Milling Co., Ltd.) (air permeation method) is used as a low moisture heavy calcium carbonate having a diameter of 1.1 μm and an average particle size of 1.7 μm from a 50% weight of particle size distribution. A specific surface area of 1.1 m ² / g, an average particle diameter of 2.0 μm converted from the specific surface area, and an average particle diameter of 3.9 μm from a 50% weight of particle size distribution) were used. In addition, in the preparation of the main agent, in Reference Example 2, Examples 3 to 6 and Example 8, α, ω-dihydroxypolydimethylsiloxane was mixed with calcium carbonate surface-treated with isostearic acid and mixed at room temperature. In Example 7 and Example 9, the mixture was heat-treated at 50 ° C. for 24 hours. Subsequently, the main agent and the curing agent were mixed at a weight ratio of 100: 10 to obtain a polyorganosiloxane composition.

Comparative Examples 1-9
Main agents and curing agents were prepared in the same manner as in Reference Example 1 except that the types and amounts of the components to be blended were changed as shown in Table 2. In addition, as calcium carbonate surface-treated with stearic acid, Calfine 500 (trade name; manufactured by Maruo Calcium Co., Ltd.) (average particle diameter 0.05 μm measured by electron microscopy, BET specific surface area 17 m ² / g) ) As calcium carbonate surface-treated with rosin acid, TDD (trade name; manufactured by Shiroishi Kogyo Co., Ltd.) (converted average particle size 0.14 μm from BET specific surface area, BET specific surface area 16.0 m ² / g) ), ESD-2 as the low moisture heavy calcium carbonate, and OMYA-FT (trade name; manufactured by OMYA) as the heavy calcium carbonate surface-treated with stearic acid (50% by weight of particle size distribution) An average particle diameter of 2.3 μm from the diameter, an average particle diameter of 0.9 μm converted from the air permeation method specific surface area, and an air permeation method specific surface area of 2.1 m ² / g) were used. In the preparation of the main agent, in Comparative Examples 1 to 6 and Comparative Example 8, α, ω-dihydroxypolydimethylsiloxane was mixed with calcium carbonate surface-treated with stearic acid as a filler and mixed at room temperature. However, in Comparative Example 7 and Comparative Example 9, the mixture was heat-treated at 50 ° C. for 24 hours. The main agent and the curing agent thus obtained were mixed at a weight ratio of 100: 10 to obtain a polyorganosiloxane composition.

Next, with respect to the polyorganosiloxane compositions obtained in Reference Examples 1 and 2, Examples 3 to 9 and Comparative Examples 1 to 9, respectively, the appearance (blackness) was initially and heat-promoted deterioration (left at 70 ° C. for 5 days) ) Measured later. In addition, adhesion durability was measured and evaluated. Furthermore, in order to investigate the influence of the type of filler and the presence or absence of surface treatment and the type of surface treatment agent on the dischargeability, the main agent used in Reference Examples 1 and 2, Examples 3 to 9 and Comparative Examples 1 to 9 Was measured at the initial stage and after heat-promoted deterioration (left at 70 ° C. for 5 days). The measurement results are shown in Tables 3 and 4.

  In addition, the external appearance (blackness) observed the difference in the color of the composition obtained by mixing a main ingredient and a hardening | curing agent with the naked eye. The discharge amount and adhesion durability were measured by the following methods.

<Measurement of discharge amount>
The main agent (composition) is filled into a 6 ounce (about 177 ml) Semco cartridge, and the main agent is extruded for 5 seconds at 3 kg / cm ² pressure from a dedicated nozzle (3 mm inner diameter at the tip) attached to the tip of the cartridge. The weight (g) of the extruded main agent was measured.

<Measurement and evaluation of adhesion durability>
In accordance with the method prescribed in JIS K5758 architectural sealant, an adhesion durability test specimen was prepared. That is, after filling the polyorganosiloxane composition obtained by mixing the main agent and the curing agent between two float glass plates (float plate glass defined in JIS R3202), the temperature is 23 ° C. and the humidity is 50%. The composition was allowed to stand for 7 days under the conditions described above to cure. A tensile test was performed on the specimen (H-type specimen) thus obtained, and 50% modulus (M50), maximum tensile stress (Tmax), and elongation at maximum load (Emax) were examined. In addition, the ruptured state of the silicone rubber was observed to examine the adhesion. Further, a tensile test was performed on the same specimens immersed in warm water at 80 ° C. for 14 days and those immersed for 30 days, respectively, and 50% modulus (M50), maximum tensile stress (Tmax), and elongation at maximum load. (Emax) and adhesion were measured respectively. In the fractured state, CF is a cohesive failure (destruction at the silicone rubber layer), TCF is a thin layer failure (destruction leaving a thin layer of silicone rubber at the interface with the glass plate), and AF is an adhesive failure (with glass plate (Removal at the silicone rubber interface).

As can be seen from Tables 3 and 4, the room temperature curable polyorganosiloxane compositions obtained in Reference Examples 1 and 2 and Examples 3 to 9 were compared with the compositions obtained in Comparative Examples 1 to 9, The curability is good, and the cured product has good mechanical strength, excellent extensibility and adhesion, and particularly excellent adhesion durability. In addition, since the main agent is excellent in the discharge property after the initial stage and after the heat-promoting deterioration, the mixing property with the curing agent is good, and the viscosity of the composition after mixing is suppressed, and the discharge property is good. Accordingly, the productivity is high and the desired properties of the cured product can be easily expressed.

Claims (2)

(A) 100 parts by weight of a polyorganosiloxane whose molecular chain terminal is blocked with a hydroxyl group or a hydrolyzable group and whose viscosity at 23 ° C. is 20 to 1,000,000 mPa · s;
(B) As a filler, 1 to 400 parts by weight of calcium carbonate surface-treated with a fatty acid having a branched alkyl group or a salt thereof,
(C) 0.001 to 10 parts by weight of a curing catalyst,
(D) 0.05 to 10 parts by weight of aminoalkylalkoxysilane ,
10 parts by weight or less of alkoxysilane having an epoxy group ,
A room temperature-curable polyorganosiloxane composition comprising 0.1 to 20 parts by weight of 2-ethylhexyltrimethoxysilane and / or 0.1 to 20 parts by weight of 2-octyldodecyltrimethoxysilane , respectively.   The room temperature-curable polyorganosiloxane composition according to claim 1, wherein the (B) calcium carbonate has an average particle diameter of 0.01 to 50 µm.