JP2003073553A - Room temperature-curable organopolysiloxane composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an elastomeric cured material having excellent storage stability under sealed conditions and approximately slight change of physical properties even under severe conditions around automobile engines. SOLUTION: This room temperature-curable organopolysiloxane composition comprises (A) a straight-chain organopolysiloxane represented by general formula (R<1> is a monofunctional hydrocarbon group; R<2> is a monofunctional hydrocarbon group or an alkoxy group-substituted monofunctional hydrocarbon group; R<3> is a monofunctional hydrocarbon group; Y is an oxygen atom or a bifunctional hydrocarbon group; b is an integer of 1-3; n is an integer to make viscosity at 25 deg.C 20-1,000,000 centipoise), (B) carbon black and (C) an organosiloxane represented by general formula R<1> a Si(OR<2> )4-a (R<1> is a monofunctional hydrocarbon group; R<2> is a monofunctional hydrocarbon group or an alkoxy group-substituted monofunctional hydrocarbon group; a is 0 or 1) as essential components.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a room-temperature-curable organopolysiloxane composition, and particularly to a room-temperature-curable organopolysiloxane composition which is used around an automobile engine and gives a cured product excellent in oil resistance and LLC resistance. Regarding things.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Various types of room-temperature-curable organopolysiloxane compositions that cure into an elastomer at room temperature when contacted with moisture in the air are known, but those of the type that cures by releasing alcohol release an unpleasant odor. It is characterized by its lack of corrosion and corrosion of metals, and is favorably used for sealing, bonding and coating of electric and electronic devices. A typical example of this type is
Japanese Patent Publication No. 39-27643 discloses a composition comprising a hydroxyl-terminated organopolysiloxane, an alkoxysilane and an organic titanium compound. Further, JP-A-55-43119 discloses a composition comprising an alkoxysilyl endblocked organopolysiloxane, an alkoxysilane and an alkoxytitanium. Further, JP-B-7-39547 discloses a composition comprising an alkoxysilyl end-capped organopolysiloxane containing a silethylene group, an alkoxysilane and an alkoxytitanium.

However, these compositions require oil resistance and L resistance, which are required when they are used around automobile engines.
The LC property was insufficient.

The present invention solves the above-mentioned drawbacks, provides an elastomeric cured product with little change in physical properties even under severe conditions such as around an automobile engine, and has room temperature curing which is excellent in storage stability under sealed conditions. The purpose of the present invention is to provide a functional organopolysiloxane composition.

[0005]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above-mentioned object, the present inventor has found that a component serving as a base material is mediated by an oxygen atom or a divalent hydrocarbon group. An organopolysiloxane having at least two silicon atoms bonded with an organooxy group in one molecule is used, and carbon black as a filler, a specific organooxysilane or a partially hydrolyzed condensate thereof, preferably a crosslink density is further improved. organosiloxane consisting essentially of R ⁴ ₃ SiO _1/2 units and SiO _4/2 units as agents,
By using a titanium chelate compound as a catalyst, the storage stability under sealed conditions is superior to the conventional one-pack dealcohol type room temperature curable organopolysiloxane composition, and the severe conditions around the automobile engine The inventors have found that a room-temperature-curable organopolysiloxane composition that gives an elastomer-like cured product with little change in the physical properties even under the above conditions can be obtained, and completed the present invention.

That is, the present invention provides (A) the following general formula (1)

[Chemical 2] (In the formula, R ¹ is a monovalent hydrocarbon group, R ² is a monovalent hydrocarbon group or an alkoxy group-substituted monovalent hydrocarbon group, R ³ is an unsubstituted or substituted monovalent hydrocarbon group, Y is an oxygen atom or Divalent hydrocarbon group, b is an integer of 1 to 3, preferably 2 or 3, n is 25 ° C.
Is an integer such that the viscosity at 20 to 1,000,000 centipoise. ) Organooxysilyl group-terminated linear organopolysiloxane 100 parts by weight (B) Carbon black 0.5 to 50 parts by weight (C) The following general formula (2) R ¹ _a Si (OR ² ) _4-a (2) (in the formula, R ¹ is a monovalent hydrocarbon group, R ² is a monovalent hydrocarbon group or an alkoxy group-substituted monovalent hydrocarbon group, and a is 0 or 1). Organooxysilane or its partial hydrolysis-condensation product 0.5 to 15 parts by weight, preferably (D)
R ⁴ ₃ SiO _1/2 units (wherein, R ⁴ is. Represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms) consisting essentially of and SiO _4/2 units, SiO _{4 /} R ⁴ ₃ Si for ₂ units
1 to 50 parts by weight of organosiloxane having a molar ratio of O _1/2 units of 0.6 to 1.2 and a hydroxysilyl group content of less than 0.7% by weight, (E) titanium chelate catalyst 0 A room temperature curable organopolysiloxane composition containing 1 to 10 parts by weight is provided.

The present invention will be described in more detail below.
The component (A) used in the present invention serves as a base material of the present composition, and in order to obtain improved storage stability, an organooxy group is introduced through an oxygen atom or a divalent hydrocarbon group. In particular, it is necessary that the organopolysiloxane has at least two silicon atoms bonded with an alkoxy group in one molecule, and the component (A) is represented by the following general formula (1):

[Chemical 3] (In the formula, R ¹ is a monovalent hydrocarbon group, R ² is a monovalent hydrocarbon group or an alkoxy group-substituted monovalent hydrocarbon group, R ³ is an unsubstituted or substituted monovalent hydrocarbon group, Y is an oxygen atom or Divalent hydrocarbon group, b is an integer of 1 to 3, preferably 2 or 3, n is 25 ° C.
Is an integer such that the viscosity at 20 to 1,000,000 centipoise. ) Is a linear organopolysiloxane having an organooxysilyl group at the end. In addition, a linear structure is used as a basic structure, and a branched structure is
Organopolysiloxanes having a cyclic or network portion can also be used.

In the organopolysiloxane represented by the general formula (1), examples of the monovalent hydrocarbon group of R ¹ and R ³ are those having 1 to 12 carbon atoms, particularly 1 to 10 carbon atoms, such as methyl, Alkyl groups such as ethyl, propyl, butyl, hexyl, octyl, decyl and octadecyl, cycloalkyl groups such as cyclopentyl and cyclohexyl,
Substitution of alkenyl groups such as vinyl and allyl, aryl groups such as phenyl, tolyl and naphthyl, aralkyl groups such as benzyl, phenylethyl and phenylpropyl, and some or all of the hydrogen atoms of these groups with halogen atoms or cyano groups. Examples of the halogenated hydrocarbon group include chloromethyl, trifluoromethyl, chloropropyl, 3,3,3-trifluoropropyl, chlorophenyl, dibromophenyl, tetrachlorophenyl and difluorophenyl groups. Examples of the cyanoalkyl group include β-cyanoethyl, γ-cyanopropyl and β-cyanopropyl groups. R ² preferably has 1 to 8 carbon atoms, and an alkyl group such as methyl, ethyl, propyl, butyl, hexyl, octyl,
Methoxyethyl, ethoxyethyl, methoxypropyl,
An alkoxy group-substituted alkyl group such as methoxybutyl is exemplified. R ¹ , R ² and R ³ each have 1 to 3 carbon atoms
Is preferred, and more preferred is a methyl group. Y is an oxygen atom or a divalent hydrocarbon radical, divalent hydrocarbon radical _{-CH 2 CH 2 -, - CH} 2 CH 2 CH
_{2 -, - CH 2 C (} CH 3) H- carbon atoms such as 1-8, is illustrated in particular 2-6 alkylene group, -CH ₂ CH ₂ - is preferred.

The viscosity of component (A) at 25 ° C. is 20-1,
The range is, 000,000 centipoise, which is 20
This is because if it is less than centipoise, excellent physical properties, especially flexibility and high elongation cannot be imparted to the cured elastomer, and if it is more than 1,000,000 centipoise, the viscosity of the composition becomes high, and the application is difficult. This is because the workability at the time becomes extremely poor. Therefore, it is more preferably in the range of 100 to 500,000 centipoise.

The organopolysiloxane containing an organooxysilyl group, especially an alkoxysilyl group at the terminal via the oxygen atom or divalent hydrocarbon group of the component (A) can be produced by a conventionally known method. For example, a corresponding alkenyl group-terminated organopolysiloxane and the following general formula (3)

[Chemical 4] (In the formula, R ¹ , R ² and b are the same as above.) The alkoxysilane represented by the formula (4) is reacted with the corresponding SiH-terminated organopolysiloxane by addition reaction in the presence of a Pt catalyst.

[Chemical 5] (In the formula, R ⁵ is an alkenyl group, and R ¹ , R ² and b are the same as described above.)
The ingredients can be manufactured.

The carbon black which is the component (B) used in the present invention is the oil resistance and LLC resistance which are the objects of the present invention.
It is an essential ingredient for imparting sex and is the most important ingredient.

Examples of carbon black include acetylene black, furnace black and Ketjen black. Among them, those having an average particle size of 15 to 65 nm, particularly 20 to 55 nm are preferable, and the DBP oil absorption is 80.
~ 300ml / 100g, especially 120-250ml / 1
It is preferably 00 g. Further, these carbon blacks may be treated, and examples of the treatment include surface treatment with silane, oxidation treatment, grafting, granulation / pellet treatment, fluorination treatment, graphitization treatment, amorphization and the like. By this treatment, various properties such as improvement of dispersibility and dispersion stability, improvement of mechanical strength, improvement of water resistance, etc. are observed, and oil resistance, storage stability, moderate viscosity, rubber in the present composition are observed. Effective for improving physical properties.

As the component (B), carbon which has been previously treated may be used, or silane treatment may be carried out when the composition is produced. In this case, in order to maintain the characteristics of the present composition, it is important that substantially no by-products and catalysts during the treatment remain in the present composition.

The amount of component (B) added is 100 parts of component (A).
The amount is usually 0.5 to 50 parts by weight, preferably 5 to 40 parts by weight, based on parts by weight. If it is too large, the viscosity of the composition will be too high and the workability during mixing and construction will be poor, and if it is too small, the physical properties of the rubber after curing will be poor.

The component (C) used in the present invention acts as a cross-linking agent of the present composition and is a component for curing the composition to give a rubber elastic body. This includes the following general formula (2) R ¹ _a Si (OR ² ) _4-a (2) (wherein R ¹ is a monovalent hydrocarbon group, R ² is a monovalent hydrocarbon group or an alkoxy group-substituted monovalent group). The hydrocarbon group, a is 0 or 1. The monovalent hydrocarbon group and the alkoxy group-substituted monovalent hydrocarbon group are exemplified by the same as those mentioned in the description of the component (A). Organooxysilanes, especially alkoxysilanes or their partial hydrolyzed condensates are used.

Specific examples of the component (C) include tetrafunctional alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, methylcellosolvoorthosilicate, methyltrimethoxysilane, methyltriethoxysilane, and the like.
Examples thereof include trifunctional alkoxysilanes such as ethyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, and methyltrimethoxyethoxysilane, and partially hydrolyzed condensates thereof. These may be used alone or in combination of two or more. Further, in order to impart a low modulus property to the rubber elastic body after curing, bifunctional alkoxysilanes such as diphenyldimethoxysilane and dimethyldimethoxysilane may be additionally added.

The amount of component (C) added is 100 parts of component (A).
It is usually in the range of 0.5 to 15 parts by weight,
It is preferably in the range of 1 to 10 parts by weight. If the amount added is too small, the composition may not be sufficiently cured, or the composition may easily thicken or gel during storage in the cartridge. On the other hand, if the amount is too large, the curing may be delayed, the rubber may not have sufficient physical properties, and it may be economically disadvantageous.

The component (D) used in the present invention acts as a crosslinking density improver for the composition and is an important component for improving the oil resistance together with the component (B). This is R ⁴ ₃ SiO _1/2
Units (in the formula, R ⁴ represents an alkyl group, a halogen-substituted alkyl group, an alkenyl group, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms such as a phenyl group.), And SiO _{4/2
Consisting} essentially of units, R ⁴ ₃ S to SiO _4/2 units
Organosiloxanes with a molar ratio of iO _1/2 units of 0.6 to 1.2 and a hydroxysilyl group content of less than 0.7% by weight are used.

The amount of component (D) added is 100 parts of component (A).
It is usually in the range of 1 to 50 parts by weight, and preferably in the range of 2 to 40 parts by weight, based on parts by weight. If the amount added is too small, the composition has low mechanical strength after oil resistance. On the other hand, if the amount is too large, the curing may be delayed, or the rubber may not have sufficient physical properties.

The component (E) used in the present invention is a catalyst for curing the composition, and a titanium chelate catalyst is necessary for obtaining the improved storage stability of the composition. Is. The titanium chelate catalyst is preferably at least one titanium chelate catalyst selected from the following general formulas (5), (6) and (7).

[0021]

[Chemical 6] (In the formula, X represents a group selected from R ¹ , an alkoxy group having 1 to 6 carbon atoms, an amino group, and an acetyl group, R represents a hydrogen atom or R ¹ , and R ¹ , R ² , and R ³ are the above. Same as m
Is an integer of 1 to 8. In this case, R ¹ and R ³ may be bonded to each other to form a ring having 5 to 8 carbon atoms in total together with C═C to which they are bonded. )

[0022]

[Chemical 7] (In the formula, R ² is a methyl group or an ethyl group, R ³ is a methyl group,
Represents an ethyl group, a phenyl group or a vinyl group, and x is 5 to 3
0 and y are 1-10. )

Specific examples of the component (E) include diisopropoxybis (ethylacetoacetate) titanium, diisopropoxybis (acetylacetone) titanium, dibutoxybis (methylacetoacetate) titanium and those shown below.

[0024]

[Chemical 8]

[0025]

[Chemical 9]

The amount of component (E) added is 100 parts of component (A).
It is in the range of 0.1 to 10 parts by weight, preferably 0.2 to 7 parts by weight, based on parts by weight. If the amount added is too small, the curing of the composition will be delayed, while if it is too large, the curing will be too fast or the storage stability will be poor.

The composition of the present invention comprises the above (A) to
In addition to the component (E), a fine powdery inorganic filler is further added, if necessary, in order to improve the flow characteristics before curing and impart necessary mechanical properties to the rubber-like elastic body after curing. It can also be added. As the inorganic filler, fine quartz powder, calcium carbonate, fumed titanium dioxide, diatomaceous earth, aluminum hydroxide, particulate alumina, magnesia, zinc oxide, zinc carbonate and silanes, silazanes, low-polymerization degree siloxanes of these , Those surface-treated with organic compounds and the like.

Further, an organic solvent, an antifungal agent, a flame retardant, a heat-resistant agent, a plasticizer, a thixotropic agent, an adhesion promoter, a curing accelerator, a pigment and the like can be added to the composition of the present invention.

The composition of the present invention can be obtained by mixing the components (A) to (E) and, if necessary, various additives in a state where moisture is blocked. The obtained composition can be used as a so-called one-pack type room temperature curable organopolysiloxane composition which is stored as it is in a closed container and is cured into a rubber-like elastic body by being exposed to moisture in the air at the time of use.

The composition of the present invention is used as a sealing material for automobiles, as a sealing material for construction, a sealing material for electric / electronic parts, an adhesive or a moisture-proof coating agent, as a textile product, a glass product,
It can also be applied to applications such as coating agents and adhesives for metal products and plastic products.

[0031]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following examples, all parts are parts by weight, and the viscosity is the value at 25 ° C.

[Synthesis Example 1] 100 parts of α, ω-dimethylvinyl-dimethylpolysiloxane having a viscosity of 30,000 centipoise, 7 parts of trimethoxysilane and 1 part of a 1% isopropanol solution of chloroplatinic acid as a catalyst were added. ,
Mixing was performed at 80 ° C. for 8 hours under N ₂ flow. Then 10 mm
The mixture was heated to 50 ° C. under reduced pressure of Hg, and excess trimethoxysilane was distilled off.

The polymer obtained has a viscosity of 30,500 centipoise and is 100: 100 with tetrabutyl titanate.
When mixed at a ratio of 1, the viscosity did not increase immediately and it was cured after 1 day. From this, it can be confirmed that trimethoxysilane was added to the vinyl group at the terminal of the polymer. This polymer is referred to as polymer A.

[Synthesis Example 2] 100 parts of α, ω-dihydroxy-dimethylpolysiloxane having a viscosity of 20,000 centipoise, 10 parts of tetramethoxysilane and 0.1 part of isopropylamine as a catalyst were added, and the mixture was added under a stream of N _2. At 100 ° C. for 6 hours. After that, it was heated to 50 ° C. under a reduced pressure of 10 mmHg to distill off excess tetramethoxysilane.

The polymer obtained has a viscosity of 21,000 centipoise and is 100: 100 with tetrabutyl titanate.
When mixed at a ratio of 1, the viscosity did not increase immediately and it was cured after 1 day. From this, it can be confirmed that the polymer terminal was substituted with a trimethoxysilyl group. This polymer is referred to as polymer B.

Example 1 100 parts of Polymer A and Denka Black HS-100 [average particle size 48 nm, DBP oil absorption 140 ml / 100 g (manufactured by Denki Kagaku Kogyo KK)] 20
Parts are mixed evenly and mixed with vinyltrimethoxysilane 6
Parts and diisopropoxy-bis (ethyl acetoacetate) titanium 2 parts were mixed under reduced pressure until uniform to prepare a composition. This was placed in a poly cartridge and sealed.

Example 2 100 parts of polymer A, trimethylsiloxy units ((CH ₃ ) ₃ SiO _1/2 units) and SiO _4/2 units were used, and (CH ₃ ) ₃ SiO _1/2 / SiO
_4/2 molar ratio is 0.74, silanol group content is 0.0
6 mol / 100 g, 10 parts of a resinous siloxane copolymer dissolved in toluene so that the solid content is 50% by weight, and 20 parts of Denka Black HS-100 (manufactured by Denki Kagaku Kogyo Co., Ltd.) were uniformly mixed, and mixed with this. A composition was prepared by mixing 6 parts of vinyltrimethoxysilane and 2 parts of diisopropoxy-bis (ethylacetoacetate) titanium under reduced pressure until uniform. This was placed in a poly cartridge and sealed.

Example 3 100 parts of Polymer B, trimethylsiloxy units ((CH ₃ ) ₃ SiO _1/2 units) and SiO _4/2 units were used, and (CH ₃ ) ₃ SiO _1/2 / SiO
_4/2 molar ratio is 0.74, silanol group content is 0.0
6 mol / 100 g, 10 parts of a resinous siloxane copolymer dissolved in toluene so that the solid content is 50% by weight, and 20 parts of Denka Black HS-100 (manufactured by Denki Kagaku Kogyo Co., Ltd.) were uniformly mixed, and mixed with this. A composition was prepared by mixing 6 parts of vinyltrimethoxysilane and 2 parts of diisopropoxy-bis (ethylacetoacetate) titanium under reduced pressure until uniform. This was placed in a poly cartridge and sealed.

A sheet having a thickness of 2 mm was prepared from the composition obtained above and cured in an atmosphere of 23 ° C. and 50% RH for 7 days. According to JIS-K6249, the physical properties of rubber (hardness, hardness,
Tensile strength and elongation at break) were measured. Furthermore, the rubber properties (hardness, tensile strength, elongation at break) after storage under the following conditions, and after oil resistance and after LLC resistance were measured. The results are shown in Table 1. Storage condition: It was stored in a dryer at 70 ° C. for 7 days. Oil resistance evaluation conditions: Toyota engine oil Neo SJ20 was used and evaluated at 120 ° C. for 240 hours. LLC-resistant evaluation condition: Toyota LLC 50% aqueous solution was used, and it evaluated on condition of 240 degreeC at 120 degreeC.

Comparative Example 1 Dry silica 20 surface-treated with dimethyldichlorosilane instead of Denka Black HS-100 (manufactured by Denki Kagaku Kogyo Co., Ltd.) in Example 1
A composition was prepared in the same manner as in Example 1 except that parts were used. The results of the same tests as in Example 1 using this composition are shown in Table 1.

Comparative Example 2 Dry silica 20 surface-treated with dimethyldichlorosilane instead of Denka Black HS-100 (manufactured by Denki Kagaku Kogyo) in Example 2
A composition was prepared in the same manner as in Example 2 except that parts were used. The results of the same test as in Example 2 using this composition are shown in Table 1.

COMPARATIVE EXAMPLE 3 In Example 2, instead of the polymer A, α, ω having a viscosity of 20,000 centipoise.
Composition in the same manner as in Example 2 except that 100 parts of dihydroxy-dimethylpolysiloxane and 20 parts of dry silica surface-treated with dimethyldichlorosilane were used instead of Denka Black HS-100 (manufactured by Denki Kagaku Kogyo Co., Ltd.). The thing was prepared. The results of the same test as in Example 2 using this composition are shown in Table 1.

[0043]

[Table 1]

[0044]

INDUSTRIAL APPLICABILITY The composition of the present invention has excellent storage stability under sealed conditions and is more harsh around the automobile engine than the conventional one-pack dealcohol type room temperature curable organopolysiloxane composition. A room-temperature-curable organopolysiloxane composition that gives an elastomer-like cured product with little change in physical properties even under conditions.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) (C08L 83/06 C08L 83:04 83:04) (72) Inventor Tsuneo Kimura Matsuida Town, Usui District, Gunma Prefecture Hitomi No. 1 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Technology Laboratory F-term (reference) 4H017 AA04 AA29 AB15 AC03 AD06 AE05 4J002 CP032 CP051 CP081 CP091 CP131 CP141 DA036 EE048 EH038 EX037 GH00 GJ01 GJ02 GN00

Claims (4)

[Claims] 1. (A) The following general formula (1): (In the formula, R ¹ is a monovalent hydrocarbon group, R ² is a monovalent hydrocarbon group or an alkoxy group-substituted monovalent hydrocarbon group, R ³ is an unsubstituted or substituted monovalent hydrocarbon group, Y is an oxygen atom or Divalent hydrocarbon group, b is an integer of 1 to 3, n is 25 at a viscosity of 20
It is an integer such that it is about 1,000,000 centipoise. ) 100 parts by weight of a linear organopolysiloxane having an organooxysilyl group at the end (B) 0.5 to 50 parts by weight of carbon black (C) the following general formula (2) R ¹ _a Si (OR ² ) _4-a (2) (in the formula, R ¹ is a monovalent hydrocarbon group, R ² is a monovalent hydrocarbon group or an alkoxy group-substituted monovalent hydrocarbon group, and a is 0 or 1). A room temperature curable organopolysiloxane composition comprising 0.5 to 15 parts by weight of an organooxysilane or a partially hydrolyzed condensate thereof as an essential component. 2. (D) R ⁴ ₃ SiO _1/2 unit (wherein R ⁴ represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms) and SiO _4/2. Becomes essential from the unit,
The molar ratio of R ⁴ ₃ SiO _1/2 units to SiO _4/2 units is a 0.6-1.2 organosiloxane 1-50 content of hydroxysilyl groups is less than 0.7 wt%
The room temperature-curable organopolysiloxane composition according to claim 1, which comprises parts by weight. 3. (E) titanium chelate catalyst 0.1
The room temperature curable organopolysiloxane composition according to claim 1 or 2, containing 10 to 10 parts by weight. 4. The average particle size of carbon black is 15 to 6.
5 nm, DBP oil absorption is 80-300 ml / 10
The room temperature curable organopolysiloxane composition according to claim 1, which has an amount of 0 g.