JP2023012662A - Addition-curable liquid silicone rubber composition for air bag and air bag - Google Patents

Abstract

To provide an addition-curable liquid silicone rubber composition for an air bag having excellent adhesion durability to a base fabric for an air bag and flame retardancy and an air bag.SOLUTION: There is provided an addition-curable liquid silicone rubber composition for an air bag which comprises (A) 100 pts.mass of an organopolysiloxane, (B) 5 to 100 pts.mass of a boron atom-containing three-dimensional network organopolysiloxane resin containing a monofunctional R13SiO1/2 unit, a tetrafunctional SiO4/2 unit and a trifunctional boron atom bonded to 3 oxygen atoms, (C) an organic hydrogen polysiloxane in an amount so that a hydrosilyl group contained in the composition is 1 to 10 mol per mol of the total of alkenyl groups bonded to a silicon atom contained in the composition, (D) 1 to 50 pts.mass of silica fine powder, (E) 1 to 500 ppm of a catalyst for hydrosilylation reaction and (F) 0.1 to 10 pts.mass of an organosilicon compound.SELECTED DRAWING: None

Description

The present invention relates to an addition-curable liquid silicone rubber composition for airbags and airbags.

Conventionally, silicone rubber compositions for airbags have been proposed for the purpose of forming a rubber film on the fiber surface. Airbags having a silicone rubber coating are excellent in internal pressure retention and low burning rate, and are therefore suitably used as airbags for automobiles and the like.

Examples of such addition-curable liquid silicone rubber compositions for airbags include those obtained by combining a cross-linking agent having hydrosilyl groups at both molecular chain terminals and a cross-linking agent having hydrosilyl groups in side chains (Patent Documents 1). This addition-curable liquid silicone rubber composition for air bags is characterized by excellent internal pressure retention. Also known is a method of producing an addition-curable liquid silicone rubber composition for airbags by pre-mixing a siloxane component with resinous polysiloxane, silica, a surface treatment agent, and water (Patent Document 2). . By coating the surface of the fiber with this composition, an airbag fabric excellent in low burning rate property can be obtained. Furthermore, an addition-curable liquid silicone rubber composition for airbags is disclosed which uses an organohydrogenpolysiloxane containing T units or Q units as a cross-linking agent (Patent Document 3). A coated base fabric coated with this composition is characterized by excellent strength. Further, an addition-curable liquid silicone rubber composition for air bags is disclosed, which contains, as a flame retardant, a silicone resin which consists of M, D, and Q units and contains a crosslinkable functional group only in the D unit (Patent Reference 4). An airbag coated with this composition is characterized by excellent low burning rate properties.

However, coating base fabrics for air bags using conventional addition-curable liquid silicone rubber compositions for air bags show a marked decrease in adhesiveness after endurance tests such as heat resistance and moist heat resistance. Therefore, it did not satisfy the adhesion durability required for air bag base fabrics. In recent years, there has been a tendency to reduce the coating amount of the silicone rubber composition coated on the air bag base fabric for the purpose of weight reduction and space saving. Therefore, there is a demand for a material that is excellent in adhesion durability and flame retardancy even at a low coating weight.

Japanese Patent Application Publication No. 2013-531695 JP 2013-209517 A Japanese Patent Application Publication No. 2019-513907 WO2018/168315

The present invention has been made in view of the above circumstances, and provides an addition-curable liquid silicone rubber composition for airbags and an airbag which are excellent in adhesion durability to airbag base fabrics and flame retardancy. With the goal.

In order to solve the above problems, the present invention provides an addition-curable liquid silicone rubber composition for air bags, comprising:
(A) an organopolysiloxane containing two or more silicon-bonded alkenyl groups per molecule and having a weight average degree of polymerization of 50 to 2,000: 100 parts by mass;
(B) Monofunctional R ¹ ₃ SiO _1/2 units (M units, where R ¹ is independently an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms , and a group selected from alkenyl groups having 2 to 10 carbon atoms), tetrafunctional SiO _4/2 units (Q units), and trifunctional boron atoms bonded to three oxygen atoms (BO _3/2 units ), wherein the ratio of said M units to said Q units is from 0.65 to 1.40, and the ratio of said trifunctional boron atoms to said silicon atoms of said Q units is from 0.05 to 0.4; A boron atom-containing three-dimensional network organopolysiloxane resin having an alkenyl group content of 0.01 to 0.30 mol/100 g: 5 to 100 parts by mass,
(C) Organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms (hydrosilyl groups) per molecule: Hydrosilyl groups contained in the composition are bonded to silicon atoms contained in the composition an amount of 1 to 10 mol per 1 mol of the total alkenyl group,
(D) Silica fine powder having a BET specific surface area of 50 m ² /g or more: 1 to 50 parts by mass,
(E) Catalyst for hydrosilylation reaction: 1 to 500 ppm in terms of mass of catalyst metal element per 100 parts by mass of component (A), and (F) Organosilicon compound containing adhesion imparting functional group: 0.1 to 10 parts by mass,
Provided is an addition-curable liquid silicone rubber composition for an air bag, comprising:

Such an addition-curable liquid silicone rubber composition is an addition-curable liquid silicone rubber composition that is excellent in adhesion durability to airbag fabrics and flame retardancy.

In the present invention, it is preferable that the component (G) further contains 0.1 to 5 parts by mass of one or more condensation catalysts selected from organic titanium compounds, organic zirconium compounds, and organic aluminum compounds.

Such an addition-curing liquid silicone rubber composition is superior in adhesiveness.

In the present invention, the adhesion-imparting functional group is preferably one or more groups selected from an epoxy group, a silicon-bonded alkoxy group, a hydrosilyl group, an isocyanate group, an acrylic group, and a methacrylic group.

With such an addition-curable liquid silicone rubber composition, the adhesion of the addition-curable liquid silicone rubber composition to the airbag base fabric can be further improved.

The present invention also provides an airbag comprising a base fabric for an airbag and a cured film of the addition-curable liquid silicone rubber composition for an airbag described above.

With such an airbag, the airbag is excellent in adhesion durability to the airbag base fabric and flame retardancy.

As described above, according to the present invention, it is possible to provide an addition-curable liquid silicone rubber composition for airbags and an airbag which are excellent in adhesion durability to airbag base fabrics and flame retardancy.

As described above, there has been a demand for the development of addition-curable liquid silicone rubber compositions and airbags that are excellent in adhesion durability to airbag fabrics and flame retardancy.

The present inventors have made intensive studies to achieve the above object, and as a result, found that an addition-curable liquid silicone rubber composition containing a boron atom-containing three-dimensional network organopolysiloxane resin of a specific composition is suitable for use in airbags. I found that Specifically, the inventors have found that an airbag base fabric coated with and cured with the addition-curable liquid silicone rubber composition is excellent in adhesion durability to the base fabric and flame retardancy, and have completed the present invention. .

That is, the present invention provides an addition-curable liquid silicone rubber composition for air bags,
(A) an organopolysiloxane containing two or more silicon-bonded alkenyl groups per molecule and having a weight average degree of polymerization of 50 to 2,000: 100 parts by mass;
(B) Monofunctional R ¹ ₃ SiO _1/2 units (M units, where R ¹ is independently an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms , and a group selected from alkenyl groups having 2 to 10 carbon atoms), tetrafunctional SiO _4/2 units (Q units), and trifunctional boron atoms bonded to three oxygen atoms (BO _3/2 units ), wherein the ratio of said M units to said Q units is from 0.65 to 1.40, and the ratio of said trifunctional boron atoms to said silicon atoms of said Q units is from 0.05 to 0.4; A boron atom-containing three-dimensional network organopolysiloxane resin having an alkenyl group content of 0.01 to 0.30 mol/100 g: 5 to 100 parts by mass,
(C) Organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms (hydrosilyl groups) per molecule: Hydrosilyl groups contained in the composition are bonded to silicon atoms contained in the composition an amount of 1 to 10 mol per 1 mol of the total alkenyl group,
(D) Silica fine powder having a BET specific surface area of 50 m ² /g or more: 1 to 50 parts by mass,
(E) Catalyst for hydrosilylation reaction: 1 to 500 ppm in terms of mass of catalyst metal element per 100 parts by mass of component (A), and (F) Organosilicon compound containing adhesion imparting functional group: 0.1 to 10 parts by mass,
An addition-curable liquid silicone rubber composition for an air bag, comprising:

Although the present invention will be described in detail below, the present invention is not limited thereto. In the present specification, viscosity is a value measured at 25° C. using a rotational viscometer according to the method described in JIS K 7117-1:1999. The weight average degree of polymerization is a value obtained as a weight average degree of polymerization (weight average molecular weight) in terms of polystyrene by GPC (gel permeation chromatography) analysis using toluene as a developing solvent measured under the following conditions.
[Measurement condition]
Developing solvent: toluene Flow rate: 0.35 mL/min
Detector: Differential Refractive Index Detector (RI)
Column: TSK Guard column SuperH-L
TSKgel Super H4000 (6.0mm ID x 15cm x 1)
TSKgel Super H3000 (6.0mm I.D. x 15cm x 1)
TSKgel SuperH2000 (6.0mm I.D. x 15cm x 2)
(both manufactured by Tosoh Corporation)
Column temperature: 40°C
Sample injection volume: 10 μL (toluene solution with a concentration of 0.5% by weight)

<Addition-curable liquid silicone rubber composition for air bags>
The addition-curable liquid silicone rubber composition for airbags of the present invention is
(A) an organopolysiloxane containing two or more silicon-bonded alkenyl groups per molecule and having a weight average degree of polymerization of 50 to 2,000: 100 parts by mass;
(B) Monofunctional R ¹ ₃ SiO _1/2 units (M units, where R ¹ is independently an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms , and a group selected from alkenyl groups having 2 to 10 carbon atoms), tetrafunctional SiO _4/2 units (Q units), and trifunctional boron atoms bonded to three oxygen atoms (BO _3/2 units ), wherein the ratio of said M units to said Q units is from 0.65 to 1.40, and the ratio of said trifunctional boron atoms to said silicon atoms of said Q units is from 0.05 to 0.4; A boron atom-containing three-dimensional network organopolysiloxane resin having an alkenyl group content of 0.01 to 0.30 mol/100 g: 5 to 100 parts by mass,
(C) Organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms (hydrosilyl groups) per molecule: Hydrosilyl groups contained in the composition are bonded to silicon atoms contained in the composition an amount of 1 to 10 mol per 1 mol of the total alkenyl group,
(D) Silica fine powder having a BET specific surface area of 50 m ² /g or more: 1 to 50 parts by mass,
(E) Catalyst for hydrosilylation reaction: 1 to 500 ppm in terms of mass of catalyst metal element per 100 parts by mass of component (A), and (F) Organosilicon compound containing adhesion imparting functional group: 0.1 to 10 parts by mass,
and is liquid at room temperature (25° C.). Each component will be described in detail below.

[(A) component]
The organopolysiloxane of component (A) is an organopolysiloxane containing two or more silicon-bonded alkenyl groups per molecule and having a weight-average degree of polymerization of 50 to 2,000. It is the base polymer (main agent) of the product.

Component (A) may have, for example, a linear, cyclic, or branched molecular structure. Group-blocked linear diorganopolysiloxanes are preferred. Further, when the molecular structure of the organopolysiloxane of component (A) is linear or branched, the position of the silicon atom to which the alkenyl group is bonded in the molecule of the organopolysiloxane is the terminal of the molecular chain (i.e., triorganosiloxy group) and in the middle of the molecular chain (that is, bifunctional diorganosiloxane units or trifunctional monoorganosilsesquioxane units located at the non-terminus of the molecular chain), or both. A particularly preferred component (A) is a linear diorganopolysiloxane containing at least alkenyl groups bonded to silicon atoms at both ends of the molecular chain.

The silicon-bonded alkenyl group in component (A) generally has 2 to 8 carbon atoms, preferably 2 to 4 carbon atoms. Specific examples thereof include vinyl group, allyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, cyclohexenyl group, heptenyl group and the like, and vinyl group is particularly preferable.

The content of alkenyl groups bonded to silicon atoms in component (A) is 0.001 based on the total monovalent organic groups bonded to silicon atoms (that is, unsubstituted or substituted monovalent hydrocarbon groups). It is preferably about 10 mol %, more preferably about 0.01 to 5 mol %.

The silicon-bonded monovalent organic groups other than the alkenyl groups of component (A) include, for example, the same or different unsubstituted or substituted groups having usually 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms. are monovalent hydrocarbon groups. Specific examples of monovalent organic groups include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, cyclohexyl group and heptyl group; phenyl group, tolyl group, xylyl group and naphthyl group. aralkyl groups such as benzyl group and phenethyl group; halogen-substituted alkyl groups such as chloromethyl group, 3-chloropropyl group and 3,3,3-trifluoropropyl group; is preferably

The weight average degree of polymerization of component (A) is 50 to 2,000, preferably 100 to 1,500, more preferably 120 to 1,000. If the weight-average degree of polymerization is lower than 50, the resulting silicone rubber may have poor mechanical properties. , the coating workability may deteriorate.
The viscosity of component (A) at 25° C. is preferably 50 to 200,000 mPa·s, more preferably 100 to 150,000 mPa·s, still more preferably 400 to 100,000 mPa·s.

Specific examples of the organopolysiloxane of component (A) include dimethylsiloxane-methylvinylsiloxane copolymer with trimethylsiloxy groups at both ends of the molecular chain, methylvinylpolysiloxane with trimethylsiloxy groups at both ends of the molecular chain, and trimethyl at both ends of the molecular chain. Siloxy group-blocked dimethylsiloxane/methylvinylsiloxane/methylphenylsiloxane copolymer, both molecular chain ends dimethylvinylsiloxy group-blocked dimethylpolysiloxane, molecular chain both ends dimethylvinylsiloxy group-blocked methylvinylpolysiloxane, molecular chain both ends dimethylvinyl Siloxy group-blocked dimethylsiloxane/methylvinylsiloxane copolymer, both molecular chain ends dimethylvinylsiloxy group-blocked dimethylsiloxane/methylvinylsiloxane/methylphenylsiloxane copolymer, both molecular chain ends divinylmethylsiloxy group-blocked dimethylpolysiloxane, molecule Divinylmethylsiloxy group-blocked dimethylsiloxane/methylvinylsiloxane copolymer at both chain ends, trivinylsiloxy group-blocked dimethylpolysiloxane at both molecular chain ends, dimethylsiloxane/methylvinylsiloxane copolymer at both molecular chain ends trivinylsiloxy group-blocked, and mixtures of two or more of these organopolysiloxanes.

The (A) component organopolysiloxane may be used alone or in combination of two or more.

[(B) component]
The boron atom-containing three-dimensional network organopolysiloxane resin of the component (B) is a boron atom-containing organopolysiloxane resin with a three-dimensional network (resin-like) structure, and is composed of monofunctional R ¹ ₃ SiO _1/2 units (M unit, wherein R ¹ is a group independently selected from unsubstituted or substituted alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and alkenyl groups having 2 to 10 carbon atoms), 4 containing functional SiO _4/2 units (Q units) and trifunctional boron atoms (BO _3/2 units) bonded to three oxygen atoms, the ratio of said M units to said Q units (M units/ Q unit) is 0.65 to 1.40, and the ratio of the trifunctional boron atom to the silicon atom of the Q unit (boron atom of BO _3/2 unit/silicon atom of Q unit) is 0.05 to 1.40 0.4, and the amount of alkenyl groups is 0.01 to 0.30 mol/100 g. Optionally, difunctional R ¹ ₂ SiO _2/2 units (D units) and trifunctional R ¹ SiO _3/2 units (T units) may be included. This boron atom-containing three-dimensional network organopolysiloxane resin (wherein the organo groups here can also include alkenyl groups) can also act as a flame retardant improver and an adhesion durability improver. However, this boron atom-containing three-dimensional network organopolysiloxane resin does not contain hydrogen atoms (hydrosilyl groups) bonded to silicon atoms.

In the above formula, R ¹ is independently an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms, and It is a group selected from 2 to 10 alkenyl groups. At this time, it is preferably a group independently selected from an alkyl group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms. The same alkenyl groups and monovalent organic groups (unsubstituted or substituted monovalent hydrocarbon groups) exemplified in component (A) above can be mentioned, and specific examples include vinyl, allyl, and propenyl groups. , alkenyl groups such as butenyl group, pentenyl group, hexenyl group, cyclohexenyl group and heptenyl group; alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, cyclohexyl group and heptyl group; aryl groups such as groups, tolyl groups, xylyl groups and naphthyl groups; aralkyl groups such as benzyl groups and phenethyl groups; halogen-substituted alkyl groups such as chloromethyl groups, 3-chloropropyl groups and 3,3,3-trifluoropropyl groups groups, etc., and a methyl group and a vinyl group are particularly preferred.

The content of alkenyl groups bonded to silicon atoms in component (B) is 0.01 to 0.30 mol/100 g, preferably 0.03 to 0.20 mol/100 g, more preferably 0.05 to 0. .15 mol/100 g. If the alkenyl group amount is less than 0.01 mol/100 g, the mechanical strength required for the air bag coating material may not be obtained, and if it is greater than 0.30 mol/100 g, the hardness of the cured product is extremely high. may become high, and adhesiveness and mechanical strength may decrease.

The boron atom-containing three-dimensional network organopolysiloxane resin of component (B) has a ratio of M units to Q units of 0.65 to 1.40, preferably 0.70 to 1.30, more preferably 0.75 to 1.20. If the ratio of M units to Q units is lower than 0.65, the viscosity may increase and the coating workability may deteriorate when blended in the silicone rubber composition. The effect of improving flame retardancy may not be obtained.

In the boron atom-containing three-dimensional network organopolysiloxane resin of component (B), the ratio of trifunctional boron atoms bonded to three oxygen atoms to silicon atoms in Q units is 0.05 to 0.40. , preferably 0.08 to 0.30, more preferably 0.1 to 0.25. If the ratio of trifunctional boron atoms bonded with three oxygen atoms to the silicon atom of the Q unit is less than 0.05, a sufficient effect of improving adhesion durability cannot be obtained, and if it is greater than 0.40, it is blended in the silicone rubber composition. When this is done, the thixotropy may increase and the coating workability may deteriorate.

Here, in the boron atom-containing three-dimensional network organopolysiloxane resin of the component (B), as described above, M units, Q units and trifunctional boron atoms bonded to three oxygen atoms are essential constituents. However, in addition, D units and T units may be contained. In that case, the total content of M units, Q units, and trifunctional boron atoms bonded to three oxygen atoms is 50 to 100 mol in the boron atom-containing three-dimensional network organopolysiloxane resin of component (B). %, more preferably 80 to 100 mol %. When the total content of M units, Q units and trifunctional boron atoms bonded to three oxygen atoms in the boron atom-containing three-dimensional network organopolysiloxane resin of component (B) is within the above range, it is sufficiently It is suitable because it can obtain a good effect of improving flame retardancy and an effect of improving adhesion durability.

The boron atom-containing three-dimensional network organopolysiloxane resin of component (B) preferably has a weight average degree of polymerization of 2,000 to 50,000, more preferably 4,000 to 20,000. When the weight average degree of polymerization is in the range of 2,000 to 50,000, a sufficient flame retardancy improving effect is obtained, and the viscosity of the liquid silicone rubber coating agent composition has good coating workability.

Specific examples of the boron atom-containing three-dimensional network organopolysiloxane resin of component (B) include a siloxane unit represented by the formula: R' ₃ SiO _1/2 and a siloxane unit represented by the formula: R' ₂ R″SiO _1/2 . A siloxane unit and a siloxane unit represented by the formula: SiO _4/2 and a boric acid-organosiloxane copolymer consisting of a trifunctional boron atom unit bonded to three oxygen atoms represented by the formula: BO _3/2 , the formula : A siloxane unit represented by R′ ₃ SiO _1/2 and a formula: R′ ₂ R″SiO _1/2 A siloxane unit represented by a formula: SiO _4/2 and a siloxane unit represented by a formula: R′ ₂ SiO ₂ A boric acid-organosiloxane copolymer consisting of a siloxane unit represented by _/2 and a trifunctional boron atom unit bonded to three oxygen atoms represented by the formula: BO _3/2 , formula: R' ₃ SiO _{1/ 2} and the siloxane unit represented by the formula: R' ₂ R"SiO _1/2 and the siloxane unit represented by the formula: SiO _4/2 and the siloxane unit represented by the formula: R' ₁ R"SiO _2/2 A boric acid-organosiloxane copolymer consisting of a siloxane unit and a trifunctional boron atom unit bonded to three oxygen atoms represented by the formula: BO _3/2 , a siloxane represented by the formula: R' ₃ SiO _1/2 A siloxane unit represented by a unit and a formula: R′ ₂ R″SiO _1/2 A siloxane unit represented by a formula: SiO _4/2 A siloxane unit represented by a formula: R′ ₁ SiO _3/2 A siloxane unit represented by a formula: BO ₃ Examples include boric acid-organosiloxane copolymers composed of trifunctional boron atom units bonded to three oxygen atoms represented by _/2 , and mixtures of two or more of these organopolysiloxanes.

R' in the above formula is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, and does not contain an alkenyl group. Examples of R′ include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, cyclohexyl group and heptyl group; aryl groups such as phenyl group, tolyl group, xylyl group and naphthyl group. aralkyl groups such as benzyl group and phenethyl group; halogenated alkyl groups such as chloromethyl group, 3-chloropropyl group and 3,3,3-trifluoropropyl group; Among them, a methyl group is preferred. In addition, R″ in the above formula is an alkenyl group having 2 to 10 carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2 to 4 carbon atoms. Examples of R″ include vinyl group, allyl group, butenyl group, A pentenyl group, a hexenyl group, a heptenyl group and the like can be mentioned. Among them, a vinyl group is preferred.

The amount of component (B) is 5 to 100 parts by mass, preferably 5 to 80 parts by mass, and 5 to 50 parts by mass, per 100 parts by mass of organopolysiloxane as component (A). is particularly preferred. If the blending amount is outside the range of 5 to 100 parts by mass, sufficient effects of improving flame retardancy and adhesion durability cannot be obtained, and the cost effectiveness is poor.

The boron atom-containing three-dimensional network organopolysiloxane resin of component (B) can be used alone or in combination of two or more.

[(C) Component]
Component (C), an organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms (hydrosilyl groups) per molecule, is mainly composed of alkenyl groups and hydrosilyl groups in components (A) and (B). It undergoes a chemical addition reaction and acts as a cross-linking agent (curing agent).
The molecular structure of component (C) includes, for example, linear, cyclic, branched, and three-dimensional network (resinous) structures. 25 or more hydrogen atoms (hydrosilyl groups) bonded to silicon atoms. ℃ is used. Such hydrosilyl groups may be located either at the end of the molecular chain, in the middle of the molecular chain, or both.

As this organohydrogenpolysiloxane, one represented by the following average compositional formula (1) can be used.

In formula (1), R ² is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms. For example, alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group and decyl group, Aryl groups such as phenyl group, tolyl group, xylyl group and naphthyl group; aralkyl groups such as benzyl group, phenylethyl group and phenylpropyl group; substituted with a halogen atom, such as chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group and the like. R ² is preferably an alkyl group or an aryl group, more preferably a methyl group. R ² excludes aliphatic unsaturated hydrocarbon groups such as alkenyl groups. Further, a is 0.7 to 2.1, b is 0.001 to 1.0, and a+b is a positive number satisfying 0.8 to 3.0, preferably a is 1.0 to 2.0, b is 0.01 to 1.0, and a+b is a positive number that satisfies 1.5 to 2.5.

Such organohydrogenpolysiloxanes of component (C) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, and tris(hydrogendimethylsiloxy). Methylsilane, Tris(hydrogendimethylsiloxy)phenylsilane, Methylhydrogencyclopolysiloxane, Methylhydrogensiloxane/Dimethylsiloxane cyclic copolymer, Methylhydrogenpolysiloxane blocked with trimethylsiloxy groups at both ends of the molecular chain, Trimethyl at both ends of the molecular chain Siloxy group-blocked dimethylsiloxane/methylhydrogensiloxane copolymer, both molecular chain ends trimethylsiloxy group-blocked dimethylsiloxane/methylhydrogensiloxane/methylphenylsiloxane copolymer, both molecular chain ends trimethylsiloxy group-blocked dimethylsiloxane/methylhydro gensiloxane-diphenylsiloxane copolymer, methylhydrogensiloxy group-blocked methylhydrogenpolysiloxane at both molecular chain ends, dimethylpolysiloxane blocked at both molecular chain ends with dimethylhydrogensiloxy group, dimethylhydrogensiloxy group-blocked at both molecular chain ends siloxane-methylhydrogensiloxane copolymer, dimethylsiloxane-methylphenylsiloxane copolymer with dimethylhydrogensiloxy group-blocked at both molecular chain ends, dimethylsiloxane-diphenylsiloxane copolymer with dimethylhydrogensiloxy group-blocked at both molecular chain ends, molecule A methylphenylpolysiloxane having both chain ends blocked with dimethylhydrogensiloxy groups, a diphenylpolysiloxane having both molecular chain ends blocked with dimethylhydrogensiloxy groups, and in each of these exemplified compounds, some or all of the methyl groups are ethyl groups, propyl groups, etc. substituted with another alkyl group, a siloxane unit represented by the formula: R ² ₃ SiO _1/2 and a siloxane unit represented by the formula: R ² ₂ HSiO _1/2 and a siloxane unit represented by the formula: SiO _4/2 Organosiloxane copolymer composed of siloxane units, formula: R ² ₂ HSiO _1/2 Organosiloxane copolymer composed of siloxane units represented by formula: SiO _4/2 and formula: R ² HSiO _{2 /2} and a siloxane unit represented by the formula: R ² SiO _3/2 or a siloxane unit represented by the formula: HSiO _3/2 and mixtures of two or more of these organopolysiloxanes.

The amount of component (C) is such that component (C) is added to a total of 1 mol (or units) of silicon-bonded alkenyl groups contained in the composition containing components (A) and (B). The amount of hydrosilyl groups contained in the composition is 1 to 10 mol (or pieces), preferably 1.2 to 9 mol (or pieces), more preferably 1.5 to 8 mol (or pieces) is.
Less than 1 mol of hydrosilyl groups contained in the composition containing component (C) per total 1 mol of silicon-bonded alkenyl groups contained in the composition containing components (A) and (B) If this is the case, the composition will not cure sufficiently, and if it exceeds 10 mol, the heat resistance of the resulting cured silicone rubber may be extremely poor.

The (C) component organohydrogenpolysiloxane may be used alone or in combination of two or more.

[(D) component]
(D) The fine silica powder having a BET specific surface area of 50 m ² /g or more acts as a reinforcing filler. That is, it imparts strength to the silicone rubber cured product obtained from the composition according to the present invention, and by using silica fine powder as a reinforcing filler, a coating film that satisfies the strength required for the present invention is formed. It becomes possible to Such fine silica powder has a BET specific surface area of 50 ^{m 2} /g or more, preferably 50 to 400 m ² /g, more preferably 100 to 300 m ² /g. If it is less than g, it is not possible to impart mechanical strength characteristics that are satisfactory as a coating agent for airbags.

Such fine silica powder may be a known one that has been conventionally used as a reinforcing filler for silicone rubber, provided that the specific surface area is within the above range. silica), precipitated silica (wet silica), and the like.

As the silica fine powder, for example, silica fine powder whose surface has been hydrophobized with a surface treatment agent such as a (usually hydrolyzable) organosilicon compound such as chlorosilane, alkoxysilane, or organosilazane can be used. . In that case, these silica fine powders may be used in advance in a powder state and directly subjected to a surface hydrophobization treatment with a surface treatment agent. Moreover, a surface treatment agent may be added at the time of kneading with silicone oil (for example, the alkenyl group-containing organopolysiloxane of component (A)) to make the surface hydrophobic.

As a method for treating component (D), surface treatment can be performed by a known technique. For example, the untreated silica fine powder and the surface treatment agent are placed in a mechanical kneading device or fluidized bed sealed at normal pressure, and if necessary, in the presence of an inert gas, at room temperature (25 ° C.) or heat treatment (heating ). Optionally, water or catalysts (such as hydrolysis accelerators) may be used to facilitate the surface treatment. Surface-treated silica fine powder can be produced by drying after kneading. The amount of the surface treatment agent to be blended may be at least the amount calculated from the coverage area of the surface treatment agent.

Specific examples of the surface treatment agent include silazanes such as hexamethyldisilazane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, vinyl trimethoxysilane, Silane coupling agents such as ethoxysilane, vinyltrimethoxysilane, trimethylmethoxysilane, triethylmethoxysilane, vinyltris(methoxyethoxy)silane, trimethylchlorosilane, dimethyldichlorosilane, divinyldimethoxysilane and chloropropyltrimethoxysilane, polymethylsiloxane, Examples include organohydrogenpolysiloxane, etc., which can be surface-treated and used as hydrophobic silica fine powder. A silane coupling agent or a silazane is particularly preferable as the surface treatment agent.

In the case where the silica fine powder of component (D) is in powder form and has been directly surface-hydrophobicized with a surface-treating agent containing an alkenyl group, components (A), (B) and 1 to 10 mol of hydrosilyl groups contained in the composition containing component (C) per 1 mol of silicon-bonded alkenyl groups in total contained in the composition containing the surface treatment agent of component (D) (or pieces), preferably 1.2 to 9 mol (or pieces), more preferably 1.5 to 8 mol (or pieces).
This is because if the amount of hydrosilyl groups is less than 1 mol with respect to 1 mol of alkenyl groups bonded to silicon atoms in the composition, the composition may not sufficiently cure and exhibit sufficient adhesive strength. On the other hand, if the number of hydrosilyl groups exceeds 10 mol, the heat resistance of the resulting silicone rubber cured product may be extremely deteriorated.

Component (D) is added in an amount of 1 to 50 parts by mass, preferably 3 to 40 parts by mass, more preferably 5 to 30 parts by mass, per 100 parts by mass of organopolysiloxane as component (A). . If the amount is less than 1 part by mass, the strength required for the present invention cannot be obtained, and if the amount exceeds 50 parts by mass, the resulting silicone rubber composition will have a high viscosity and poor fluidity. Coating work may deteriorate.

The silica fine powder of the component (D) may be used singly or in combination of two or more.

[(E) Component]
The hydrosilylation reaction catalyst of component (E) mainly promotes the addition reaction between the silicon-bonded alkenyl groups in components (A) and (B) and the hydrosilyl groups in component (C). be. This hydrosilylation reaction catalyst is not particularly limited, and examples thereof include platinum group metals such as platinum, palladium, and rhodium; chloroplatinic acid; alcohol-modified chloroplatinic acid; coordination compounds; platinum group metal compounds such as tetrakis(triphenylphosphine)palladium and chlorotris(triphenylphosphine)rhodium; and the like, preferably platinum group metal compounds.

The amount of component (E) to be blended is 1 to 500 ppm, preferably 5 to 100 ppm, in terms of the mass of the catalytic metal element per 100 parts by mass of component (A). If the amount is less than 1 ppm, the addition reaction will be significantly slowed down, and the composition will not cure.

The (E) component addition reaction catalyst may be used alone or in combination of two or more.

[(F) component]
Component (F) is an organosilicon compound containing an adhesion-imparting functional group, and the adhesion-imparting functional group includes an epoxy group, an alkoxy group bonded to a silicon atom (alkoxysilyl group), a hydrosilyl group, an isocyanate group, Examples include one or more groups selected from acrylic groups and methacrylic groups, which are added to develop and improve the adhesion of the addition-curable liquid silicone rubber composition for airbags to the base fabric for airbags. .
As the organosilicon compound, any organosilicon compound can be used as long as it has such an adhesion-imparting functional group. From the viewpoint of adhesion development, at least one epoxy group and at least one silicon-bonded alkoxy group (e.g., trialkoxysilyl group, organodialkoxysilyl group, etc.) ), for example, an organosilane, or a cyclic or linear organosiloxane having 1 to 100 silicon atoms, preferably about 1 to 50 silicon atoms, and at least one epoxy group and More preferred are those having at least two silicon-bonded alkoxy groups.

Epoxy groups include, for example, glycidoxyalkyl groups such as glycidoxypropyl groups; epoxy-containing cyclohexylalkyl groups such as 2,3-epoxycyclohexylethyl groups and 3,4-epoxycyclohexylethyl groups; is preferably bound to
A silicon-bonded alkoxy group is, for example, a trialkoxysilyl group such as a trimethoxysilyl group and a triethoxysilyl group; a methyldimethoxysilyl group, an ethyldimethoxysilyl group, a methyldiethoxysilyl group, It is preferable to form an alkyldialkoxysilyl group such as an ethyldiethoxysilyl group.

In addition, component (F) contains functional groups other than epoxy groups and silicon-bonded alkoxy groups in one molecule, such as alkenyl groups such as vinyl groups, acrylic groups, (meth)acryloxy groups, isocyanate groups, and at least one functional group selected from the group consisting of hydrosilyl groups.

Examples of the organosilicon compound (F) include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, (3,4-epoxycyclohexylethyl)trimethoxysilane, (3, 4-epoxycyclohexylethyl)triethoxysilane, (3,4-epoxycyclohexylethyl)methyldimethoxysilane, (3,4-epoxycyclohexylethyl)methyldiethoxysilane, (2,3-epoxycyclohexylethyl)triethoxysilane, (2,3-epoxycyclohexylethyl)methyldimethoxysilane, (2,3-epoxycyclohexylethyl)methyldiethoxysilane, and other epoxy group-containing silane coupling agents (i.e., epoxy functional group-containing organoalkoxysilanes) or vinyl Vinyl group-containing silane coupling agents such as methoxysilane, or acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane, or isocyanate group-containing silane coupling agents such as 3-isocyanatopropylethoxysilane, or tri In addition to silane coupling agents such as methoxysilyl-modified allyl isocyanurate, organosilicon compounds such as cyclic organopolysiloxanes or linear organopolysiloxanes represented by the following chemical formulas, mixtures of two or more of these, or Partial hydrolysis condensates of one or more of these may be mentioned.
Main examples are given below.

（式中、ｈは１～１０の整数、ｋは０～４０の整数、好ましくは０～２０の整数、ｐは１～４０の整数、好ましくは１～２０の整数、ｑは１～１０の整数である。Ｒ^４の少なくとも１つは－ＣＨ_２ＣＨ_２ＣＨ_２Ｓｉ（ＯＣＨ_３）_３である。）

(Wherein, h is an integer of 1 to 10, k is an integer of 0 to 40, preferably an integer of 0 to 20, p is an integer of 1 to 40, preferably an integer of 1 to 20, q is an integer of 1 to 10 is an integer, and at least one of R ⁴ is -CH ₂ CH ₂ CH ₂ Si(OCH ₃ ) _3. )

Component (F) is added in an amount of 0.1 to 10 parts by mass, preferably 0.25 to 5 parts by mass, per 100 parts by mass of organopolysiloxane (A). If the amount is less than 0.1 part by mass, the resulting composition may not exhibit sufficient adhesive strength. If the blending amount exceeds 10 parts by mass, the thixotropy of the composition may be increased, the fluidity may be lowered, and the coating workability may be deteriorated.

When the component (F) contains an alkenyl group and/or a hydrosilyl group, the component (F) contains silicon atoms ( or nitrogen atom), the total number of hydrosilyl groups contained in the composition containing component (C) and component (F) per 1 mol (or pieces) of alkenyl groups bonded to 1 to 10 mol (or pieces). The amount is preferably 1.2 to 9 mol (or pieces), more preferably 1.5 to 8 mol (or pieces).
This is because if the amount of hydrosilyl groups is less than 1 mol with respect to 1 mol of alkenyl groups bonded to silicon atoms in the composition, the composition may not sufficiently cure and exhibit sufficient adhesive strength. On the other hand, if the number of hydrosilyl groups exceeds 10 mol, the heat resistance of the resulting silicone rubber cured product may be extremely poor.

(F) component may be used individually by 1 type, or may use 2 or more types together.

[Other ingredients]
In addition to the above components (A) to (F), the composition according to the present invention may contain other optional components depending on the purpose of the present invention. Specific examples thereof include the following. Each of these other components may be used alone or in combination of two or more.

[(G) component]
The condensation catalyst of component (G) is at least one selected from organic titanium compounds, organic zirconium compounds, and organic aluminum compounds. It acts as

Specific examples of component (G) include organic titanate esters such as titanium tetraisopropoxide, titanium tetra-normal butoxide, titanium tetra-2-ethylhexoxide, titanium diisopropoxybis(acetylacetonate), titanium-based condensation catalysts (titanium compounds) such as titanium diisopropoxybis(ethylacetoacetate) and organic titanium chelate compounds such as titanium tetraacetylacetonate; organic zirconium esters such as zirconium tetra-normal propoxide and zirconium tetra-normal butoxide; Zirconium-based condensation catalysts (zirconium compounds) such as organic zirconium chelate compounds such as zirconium tributoxy monoacetylacetonate, zirconium monobutoxy acetylacetonate bis(ethylacetoacetate), and zirconium tetraacetylacetonate; organic compounds such as aluminum secondary butoxide; aluminum-based condensation catalysts (aluminum compounds) such as aluminum acid esters, aluminum trisacetylacetonate, aluminum bisethylacetoacetate monoacetylacetonate, and organic aluminum chelate compounds such as aluminum trisethylacetoacetate.

The organic titanium compound, organic zirconium compound, and organic aluminum compound of component (G) are optional components that are blended as needed, and the blending amount thereof is preferably 0 per 100 parts by mass of component (A). .1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass. When the blending amount is within the range of 0.1 to 5 parts by mass, the obtained cured product has excellent adhesion to the base fabric for airbags.

(G) component may be used individually by 1 type, or may use 2 or more types together.

Reaction Control Agent The reaction control agent is not particularly limited as long as it is a compound having a curing inhibitory effect on the hydrosilylation reaction catalyst of the component (E), and known ones can be used. Specific examples thereof include phosphorus-containing compounds such as triphenylphosphine; nitrogen-containing compounds such as tributylamine, tetramethylethylenediamine and benzotriazole; sulfur-containing compounds; acetylenic compounds such as acetylene alcohols; compounds; hydroperoxy compounds; maleic acid derivatives and the like.

Since the degree of curing inhibitory effect of the reaction control agent varies depending on the chemical structure of the reaction control agent, the amount of the reaction control agent to be added is preferably adjusted to the optimum amount for each reaction control agent used. By adding an optimum amount of the reaction control agent, the composition has excellent long-term storage stability and curability at room temperature.

-Non-reinforcing fillers Examples of fillers other than the silica fine powder of the component (D) include crystalline silica (for example, quartz powder having a BET specific surface area of less than 50 m ² /g), organic resin hollow fillers, poly Methylsilsesquioxane fine particles (so-called silicone resin powder), fumed titanium dioxide, magnesium oxide, zinc oxide, iron oxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, zinc carbonate, carbon black, diatomaceous earth, talc, kaolinite Fillers such as glass fibers; fillers obtained by surface-hydrophobicizing these fillers with organosilicon compounds such as organoalkoxysilane compounds, organochlorosilane compounds, organosilazane compounds, and low-molecular-weight siloxane compounds; silicone rubber powders; silicone resins Powder etc. are mentioned.

・Other components In addition, for example, an organopolysiloxane containing one silicon-bonded hydrogen atom per molecule and no other functional groups, one silicon atom per molecule Organopolysiloxanes containing bonded alkenyl groups and no other functional groups, non-functional organopolysiloxanes containing neither silicon-bonded hydrogen atoms nor silicon-bonded alkenyl groups or other functional groups Siloxane (so-called dimethyl silicone oil), organic solvents, creep hardening inhibitors, plasticizers, thixotropic agents, pigments, dyes, antifungal agents and the like can be blended.

<Preparation of addition-curable liquid silicone rubber composition>
An addition-curable liquid silicone rubber composition can be prepared by uniformly mixing components (A) to (F), component (G), and other optional components. .
The addition-curable liquid silicone rubber composition thus obtained is a composition that is liquid at 25°C, and has a viscosity of 1 to 1,000 Pa s at 25°C measured by the method described in JIS K 7117-1:1999. is preferably 5 to 500 Pa·s, and still more preferably 10 to 300 Pa·s. At 25° C., if the viscosity is within the above range, it is less likely to cause uneven coating or insufficient adhesion to the base fabric after curing when applied to the base fabric for airbags, so it can be preferably used. can.

<Air bag base fabric>
In general, known airbag base fabrics (base materials made of fiber fabrics) on which a silicone rubber layer is formed are used, and specific examples thereof include 6,6-nylon, 6-nylon, and aramid fibers. woven fabrics of various synthetic fibers such as various polyamide fibers such as polyethylene terephthalate (PET) and various polyester fibers such as polybutylene terephthalate (PBT).

<Airbag>
The airbag of the present invention comprises a base fabric for an airbag and a cured film of the addition-curable liquid silicone rubber composition for an airbag described above.

<Method for manufacturing airbag>
After the addition-curable liquid silicone rubber composition for airbags is applied to at least one surface, especially one surface, of the base fabric for airbags (substrate made of fiber fabric), it is cured by heating in a drying oven or the like. Thereby, a silicone rubber layer (cured film) can be formed. An air bag can be manufactured using the silicone rubber-coated base fabric for an air bag thus obtained.

Here, as a method for coating the addition-curable liquid silicone rubber composition for airbags on the base fabric for airbags, conventional methods can be employed, but coating with a knife coater is preferred. The thickness (or surface coating amount) of the coating layer can be generally 10 to 100 g/m ² , preferably 12 to 90 g/m ² , more preferably 15 to 80 g/m ² .

The addition-curable liquid silicone rubber composition for airbags can be cured by a known curing method under known curing conditions. Specifically, for example, the composition can be cured by heating at 100 to 200° C. for 1 to 30 minutes.

When processing the air bag base fabric having a silicone rubber layer on at least one surface (air bag silicone rubber coated base fabric) manufactured in this way into an air bag, at least the inner surface side of the air bag is made of silicone rubber. There is a method in which the outer peripheries of two coated plain woven fabrics are adhered to each other with an adhesive, and the adhesive layers are stitched together. In addition, as described above, the addition-curable liquid silicone rubber composition is coated in a predetermined coating amount on both sides of the airbag base fabric that has been prepared by hollow weaving in advance, and cured under predetermined curing conditions. method can be adopted. As the adhesive used here, a known one can be used, but a silicone-based adhesive called a seam sealant is preferable in terms of adhesive strength and adhesive durability.

Preparation Examples, Examples, and Comparative Examples are shown below to specifically describe the present invention, but the present invention is not limited to the following Examples.

[Preparation Example 1]
60 parts by mass of dimethylpolysiloxane (A1) having a viscosity of 30,000 mPa s at 25°C and an average degree of polymerization of 750, 8 parts by mass of hexamethyldisilazane, and water 2 parts by mass and 40 parts by mass of fine silica powder (D) (Aerosil 300, manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 300 m ² /g by the BET method were put into a kneader and mixed at room temperature for 1 hour. After that, 8 parts by mass of hexamethyldisilazane was added, and the mixture was further mixed for 1 hour. The temperature was then raised to 150° C. followed by mixing for 2 hours. After that, the temperature was lowered to room temperature, and both ends of the molecular chain were blocked with vinyldimethylsiloxy groups. containing 5 mol% vinylmethylsiloxane units and 95 mol% dimethylsiloxane units among the diorganosiloxane units, both ends of the molecular chain are blocked with trimethylsiloxy groups, the viscosity at 25°C is 700 mPa s, and the average polymerization 5 parts by mass of dimethyl-vinylmethylpolysiloxane (A2) having a viscosity of 200 was added and mixed until uniform to obtain a base compound (1).

[Example 1]
To 70 parts by mass of the base compound (1) obtained in Preparation Example 1 was added vinyldimethylsiloxy-blocked dimethylpolysiloxane having a viscosity at 25°C of 1,000 mPa·s and an average degree of polymerization of 200. (A3) 58.6 parts by mass, 27.5 parts by mass of dimethylpolysiloxane (A4) having both molecular chain ends blocked with vinyldimethylsiloxy groups and having an average degree of polymerization of 450, (CH ₃ ) ₃ SiO _1/2 units; (CH ₃ ) ₂ (CH ₂ ═CH) consists of SiO _1/2 units, SiO _4/2 units and BO _3/2 units, the ratio of the sum of M units to Q units is 0.85, and boron atoms and 27.5 parts by mass of a boron atom-containing three-dimensional network organopolysiloxane resin (B1) having a silicon atom ratio of Q units of 0.11 and an alkenyl group content of 0.010 mol/100 g; A dimethylsiloxane/methylhydrogensiloxane copolymer (C) having a viscosity of 8 mPa s and having silicon-bonded hydrogen atoms in the side chains of the molecular chain and trimethylsiloxy group-blocked dimethylsiloxane/methylhydrogensiloxane copolymer (C) containing silicon-bonded hydrogen atoms Amount = 0.0092 mol/g) 19 parts by mass, 0.50 parts by mass of γ-glycidoxypropyltrimethoxysilane (F), 0.07 parts by mass of 1-ethynylcyclohexanol, chloroplatinic acid/1,3-divinyl 0.32 parts by mass of a dimethylpolysiloxane solution (E) containing 1% by mass of a tetramethyldisiloxane complex as a platinum atom content, and 0.60 parts by mass of tetraoctyl titanate (G) were mixed for 1 hour to obtain composition A. (Overall composition, hydrosilyl group/vinyl group=4.8 mol/mol, viscosity 35 Pa·s) was prepared.

<Flame retardant test method>
After coating composition A on a 66 nylon base fabric (210 denier) for air bags with a knife coater so that the surface coating amount is 25 to 30 g / m ² , heat and cure for 1 minute in a dryer at 200 ° C. , an airbag base fabric coated with a silicone rubber cured product (cured film) was produced. The flame retardancy of the resin-coated air bag base fabric was evaluated by the method described in FMVSS-302 (Federal Motor Vehicle Safety Standard-302). The resin-coated surface of the base fabric (width 10 cm × length 35 cm), which is a test piece, is turned up, and when burned by the method described in FMVSS-302, the burning distance and burning time until the flame disappears N = 10 measured in The burning speed is calculated from this burning distance and burning time. At this time, those that do not ignite the test piece or self-extinguish before the A mark, those that self-extinguish within a burning distance of 51 mm (and within 60 seconds), and those with a burning rate of 102 mm / min or less are passed, and N = A sample that passed all 10 tests was evaluated as a pass, and a sample that failed even one test was evaluated as a fail.

<Adhesion test>
After coating composition A on a 66 nylon base fabric (210 denier) for air bags with a knife coater so that the surface coating amount is 25 to 30 g / m ² , heat and cure for 1 minute in a dryer at 200 ° C. , an air bag base fabric coated with a silicone rubber cured product was produced. The above silicone rubber-coated nylon base fabric was evaluated for adhesion using a Scott rubbing tester (device name: Scott rubbing resistance wear tester, manufactured by Toyo Seiki Seisakusho Co., Ltd.) according to the method described in JIS K 6404-6: 1999. bottom. After performing a rubbing test 500 times with a pressing force of 19.6N, visually confirm the breakdown of the coating part, and evaluate it as a pass if the silicone rubber layer has not peeled off from the coating surface, and if it has peeled off. was rated as unsatisfactory.

<Adhesion durability test method>
After coating the composition A on a 66 nylon base fabric (210 denier) for air bags so that the surface coating amount is 25 to 30 g / m ² , heat curing is performed for 1 minute in a dryer at 200 ° C. to obtain a silicone rubber. An air bag base fabric coated with the cured product was produced. The above silicone rubber-coated nylon base fabric was subjected to a heat resistance test for 400 hours in a drier at 120°C and a heat and humidity test for 400 hours in a thermo-hygrostat at a temperature of 70°C and a humidity of 95%. Next, the silicone rubber-coated nylon base fabric after the above durability test is subjected to a Scott rubbing tester (device name: Scott rubbing resistance wear tester, manufactured by Toyo Seiki Seisakusho Co., Ltd.) by the method described in JIS K 6404-6: 1999. was used to evaluate adhesion. After performing a rubbing test 500 times with a pressing force of 19.6N, visually confirm the breakdown of the coating part, and evaluate it as a pass if the silicone rubber layer has not peeled off from the coating surface, and if it has peeled off. was rated as unsatisfactory.

[Example 2]
In Example 1, the boron atom-containing three-dimensional network organopolysiloxane resin (B1) was composed of (CH ₃ ) ₃ SiO _1/2 units and (CH ₃ ) ₂ (CH ₂ ═CH) SiO _1/2 units and SiO _4/2 units. units and BO _3/2 units, the ratio of the sum of M units to Q units is 0.85, the ratio of boron atoms to silicon atoms in Q units is 0.05, and the amount of alkenyl groups is 0.010 mol Composition B (hydrosilyl group/vinyl group = 4.8 mol/mol, viscosity 30 Pa) was prepared with the same formulation except that the same parts by weight were replaced with the boron atom-containing three-dimensional network organopolysiloxane resin (B2) of 100 g. ·s) was prepared and evaluated in the same manner as in Example 1. Table 1 shows the results.

[Example 3]
In Example 1, the boron atom-containing three-dimensional network organopolysiloxane resin (B1) was composed of (CH ₃ ) ₃ SiO _1/2 units and (CH ₃ ) ₂ (CH ₂ ═CH) SiO _1/2 units and SiO _4/2 units. units and BO _3/2 units, the ratio of the sum of M units to Q units is 0.85, the ratio of boron atoms to silicon atoms in Q units is 0.35, and the amount of alkenyl groups is 0.010 mol Composition C (hydrosilyl group/vinyl group = 4.8 mol/mol, A viscosity of 45 Pa·s) was prepared and evaluated in the same manner as in Example 1. Table 1 shows the results.

[Comparative Example 1]
In Example 1, the boron atom-containing three-dimensional network organopolysiloxane resin (B1) was composed of (CH ₃ ) ₃ SiO _1/2 units and (CH ₃ ) ₂ (CH ₂ ═CH) SiO _1/2 units and SiO _4/2 units. units and BO _3/2 units, the ratio of the total of M units to Q units is 0.85, the ratio of boron atoms to silicon atoms in Q units is 0.01, and the amount of alkenyl groups is 0.010 mol Composition D (hydrosilyl group/vinyl group = 4.8 mol/mol, viscosity 25 Pa· s) was prepared and evaluated in the same manner as in Example 1. Table 1 shows the results.

[Comparative Example 2]
In Example 1, the boron atom-containing three-dimensional network organopolysiloxane resin (B1) was composed of (CH ₃ ) ₃ SiO _1/2 units and (CH ₃ ) ₂ (CH ₂ ═CH) SiO _1/2 units and SiO _4/2 units. units and BO _3/2 units, the ratio of the sum of M units to Q units is 0.50, the ratio of boron atoms to silicon atoms in Q units is 0.11, and the amount of alkenyl groups is 0.010 mol Composition E (hydrosilyl group/vinyl group = 4.8 mol/mol, viscosity 1,200 Pa· s) was prepared and evaluated in the same manner as in Example 1. Table 1 shows the results.

[Comparative Example 3]
In Example 1, the boron atom-containing three-dimensional network organopolysiloxane resin (B1) was composed of (CH ₃ ) ₃ SiO _1/2 units and (CH ₃ ) ₂ (CH ₂ ═CH) SiO _1/2 units and SiO _4/2 units. wherein the ratio of the sum of M units to Q units is 1.60, the ratio of boron atoms to silicon atoms in Q units is 0.11, and the amount of alkenyl groups is 0.010 mol/100 g Composition F (hydrosilyl group/vinyl group = 4.8 mol/mol, viscosity 15 Pa s) was prepared and implemented with the same formulation except that the same parts by weight were substituted for the atom-containing three-dimensional network organopolysiloxane resin. Table 1 shows the results of the same evaluation as in Example 1.

As can be seen from Table 1, Examples 1 to 3, which used the addition-curable liquid silicone rubber composition for airbags of the present invention, were excellent in adhesion durability to airbag fabrics and flame retardancy. rice field.

On the other hand, Comparative Examples 1 to 3, in which the addition-curable liquid silicone rubber composition for airbags of the present invention was not used, failed to achieve both durability of adhesion to the base fabric for airbags and flame retardancy.

It should be noted that the present invention is not limited to the above embodiments. The above-described embodiment is an example, and any device having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect is the present invention. included in the technical scope of

Claims (4)

An addition-curable liquid silicone rubber composition for an air bag,
(A) an organopolysiloxane containing two or more silicon-bonded alkenyl groups per molecule and having a weight average degree of polymerization of 50 to 2,000: 100 parts by mass;
(B) Monofunctional R ¹ ₃ SiO _1/2 units (M units, where R ¹ is independently an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms , and a group selected from alkenyl groups having 2 to 10 carbon atoms), tetrafunctional SiO _4/2 units (Q units), and trifunctional boron atoms bonded to three oxygen atoms (BO _3/2 units ), wherein the ratio of said M units to said Q units is from 0.65 to 1.40, and the ratio of said trifunctional boron atoms to said silicon atoms of said Q units is from 0.05 to 0.4; A boron atom-containing three-dimensional network organopolysiloxane resin having an alkenyl group content of 0.01 to 0.30 mol/100 g: 5 to 100 parts by mass,
(C) Organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms (hydrosilyl groups) per molecule: Hydrosilyl groups contained in the composition are bonded to silicon atoms contained in the composition an amount of 1 to 10 mol per 1 mol of the total alkenyl group,
(D) Silica fine powder having a BET specific surface area of 50 m ² /g or more: 1 to 50 parts by mass,
(E) Catalyst for hydrosilylation reaction: 1 to 500 ppm in terms of mass of catalyst metal element per 100 parts by mass of component (A), and (F) Organosilicon compound containing adhesion imparting functional group: 0.1 to 10 parts by mass,
An addition-curable liquid silicone rubber composition for an air bag, comprising: 2. The composition according to claim 1, further comprising, as component (G), one or more condensation catalysts selected from organic titanium compounds, organic zirconium compounds, and organic aluminum compounds: 0.1 to 5 parts by mass. addition-curable liquid silicone rubber composition for airbags. 1 or claim 2, wherein the adhesion imparting functional group is one or more groups selected from an epoxy group, a silicon-bonded alkoxy group, a hydrosilyl group, an isocyanate group, an acrylic group, and a methacrylic group. Item 2. The addition-curable liquid silicone rubber composition for airbags according to item 2. An air bag comprising a base fabric for an air bag and a cured film of the addition-curable liquid silicone rubber composition for an air bag according to any one of claims 1 to 3 on the base fabric.