Flame-resistant airbag, method of manufacturing flame-resistant airbag, and addition-curable liquid silicone rubber composition for flame-resistant airbags
Provided is a flame-resistant airbag having a low rate of combustion. The flame-resistant airbag is obtained by forming, on a cloth substrate, a cured film of a composition containing: (A) 100 parts by mass of a liquid organopolysiloxane containing an alkenyl group bonded to a silicon atom; (B) 5 to 100 parts by mass of a three-dimensional network-structured organopolysiloxane resin in which 0.05 to 0.15 mol/100 g alkenyl groups are bonded only to D units, the ratio of M units to T and/or Q units is 0.65 to 1.40, and hydroxyl group content is 0.040 mol/100 g or less; (C) 0.1 to 50 parts by mass micropulverized silica having a specific surface area of at least 50 m 2 /g; (D) an organohydrogen polysiloxane comprising a hydrogen atom bonded to a silicon atom, in an amount such that the number of hydrogen atoms bonded to silicon atoms in component (D) is 1 to 10 per total 1 alkenyl group bonded to a silicon atom in components (A) and (B); (E) an effective amount of a platinum group metal catalyst; and (F) 0.1 to 10 parts by mass of an organic silicon compound. The composition is applied in an amount of 5 to 150 g/m 2 .
1. A flame-resistant airbag obtained by forming, on at least one side of an airbag base fabric, a cured film of an addition-curable liquid silicone rubber composition having a coating weight of 5 to 150 g/m 2 , which composition comprises:
(A) 100 parts by weight of an organopolysiloxane which includes at least two silicon-bonded alkenyl groups of 2 to 8 carbon atoms per molecule and is liquid at 25° C.;
(B) from 5 to 100 parts by weight of a three-dimensional network-type organopolysiloxane resin in which from 0.05 to 0.15 mol/100 g of alkenyl groups are bonded solely to difunctional R 1 R 2 SiO 2/2 units (D units; in the formula, R 1 is an alkenyl group of 2 to 8 carbon atoms and R 2 is a group selected from alkyl groups of 1 to 8 carbon atoms, alkenyl groups of 2 to 8 carbon atoms and aryl groups of 6 to 12 carbon atoms), in which the ratio (M units/T and/or Q units) of monofunctional R 3 3 SiO 1/2 units (M units; in the formula, each R 3 is independently a group selected from alkyl groups of 1 to 8 carbon atoms and aryl groups of 6 to 12 carbon atoms) to branched siloxane units which are trifunctional R 3 SiO 3/2 units (T units; in the formula, R 3 is the same as above) and/or tetrafunctional SiO 4/2 units (Q units) is from 0.65 to 1.40, and in which the amount of hydroxyl groups is 0.040 mol/100 g or less;
(C) from 0.1 to 50 parts by weight of a silica fine powder having a specific surface area according to the BET method of at least 50 m 2 /g;
(D) an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule, in an amount such that the number of silicon-bonded hydrogen atoms included on a molecule of component (D) per silicon-bonded alkenyl group in components (A) and (B) combined is from 1 to 10;
(E) an effective amount of a platinum family metal catalyst as a hydrosilylation reaction catalyst; and
(F) from 0.1 to 10 parts by weight an organosilicon compound having on the molecule, as adhesion-promoting functional groups, an epoxy group and a silicon-bonded alkoxy group.
2. The flame-resistant airbag of claim 1 , wherein the addition-curable liquid silicone rubber composition further comprises, as component (G): from 0.1 to 5 parts by weight, per 100 parts by weight of component (A), of at least one type of co-condensation catalyst selected from organotitanium compounds and organozirconium compounds.
3. The flame-resistant airbag of claim 1 , wherein component (C) is a surface-hydrophobized silica fine powder.
4. The flame-resistant airbag of claim 1 which has a combustion rate in the combustion test for airbags of Federal Motor Vehicle Safety Standard (FMVSS) No. 302 that is 40 mm/min or less.
5. A method of manufacturing flame-resistant airbags, comprising the steps of:
preparing an addition-curable liquid silicone rubber composition comprising
(A) 100 parts by weight of an organopolysiloxane which contains at least two silicon-bonded alkenyl groups of 2 to 8 carbon atoms per molecule and is liquid at 25° C.,
(B) from 5 to 100 parts by weight of a three-dimensional network-type organopolysiloxane resin in which from 0.05 to 0.15 mol/100 g of alkenyl groups are bonded solely to difunctional R 1 R 2 SiO 2/2 units (D units; in the formula, R 1 is an alkenyl group of 2 to 8 carbon atoms and R 2 is a group selected from alkyl groups of 1 to 8 carbon atoms, alkenyl groups of 2 to 8 carbon atoms and aryl groups of 6 to 12 carbon atoms), in which the ratio (M units/T and/or Q units) of monofunctional R 3 3 SiO 1/2 units (M units; in the formula, each R 3 is independently a group selected from alkyl groups of 1 to 8 carbon atoms and aryl groups of 6 to 12 carbon atoms) to branched siloxane units which are trifunctional R 3 SiO 3/2 units (T units; in the formula, R 3 is the same as above) and/or tetrafunctional SiO 4/2 units (Q units) is from 0.65 to 1.40, and in which the amount of hydroxyl groups is 0.040 mol/100 g or less,
(C) from 0.1 to 50 parts by weight of a silica fine powder having a specific surface area according to the BET method of at least 50 m 2 /g,
(D) an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule, in an amount such that the number of silicon-bonded hydrogen atoms included on a molecule of component (D) per silicon-bonded alkenyl group in components (A) and (B) combined is from 1 to 10,
(E) an effective amount of a platinum family metal catalyst as a hydrosilylation reaction catalyst, and
(F) from 0.1 to 10 parts by weight of an organosilicon compound having on the molecule, as adhesion-promoting functional groups, an epoxy group and a silicon-bonded alkoxy group;
coating the composition onto at least one side of an airbag base fabric to a coating weight of from 5 to 150 g/m 2 ; and
heat-curing the base fabric coated with the composition.
6. The flame-resistant airbag manufacturing method of claim 5 , wherein the addition-curable liquid silicone rubber composition further comprises, as component (G): from 0.1 to 5 parts by weight, per 100 parts by weight of component (A), of at least one type of co-condensation catalyst selected from organotitanium compounds and organozirconium compounds.
7. The flame-resistant airbag manufacturing method of claim 5 which includes the step of using, as component (C) in the addition-curable liquid silicone rubber composition preparation step, a surface-hydrophobized silica fine powder that is already surface-treated or a surface-hydrophobized silica fine powder that is surface-treated in the preparation step.
8. The flame-resistant airbag manufacturing method of claim 5 , wherein the addition-curable liquid silicone rubber composition has a viscosity at 25° C., as measured by the method described in JIS K 7117-1:1999, of from 1,000 to 1,000,000 mPa·s.
9. An addition-curable liquid silicone rubber composition for flame-resistant airbags, comprising:
(A) 100 parts by weight of an organopolysiloxane which includes at least two silicon-bonded alkenyl groups of 2 to 8 carbon atoms per molecule and is liquid at 25° C.;
(B) from 5 to 100 parts by weight of a three-dimensional network-type organopolysiloxane resin in which from 0.05 to 0.15 mol/100 g of alkenyl groups are bonded solely to difunctional R 1 R 2 SiO 2/2 units (D units; in the formula, R 1 is an alkenyl group of 2 to 8 carbon atoms and R 2 is a group selected from alkyl groups of 1 to 8 carbon atoms, alkenyl groups of 2 to 8 carbon atoms and aryl groups of 6 to 12 carbon atoms), in which the ratio (M units/T and/or Q units) of monofunctional R 3 3 SiO 1/2 units (M units; in the formula, each R 3 is independently a group selected from alkyl groups of 1 to 8 carbon atoms and aryl groups of 6 to 12 carbon atoms) to branched siloxane units which are trifunctional R 3 SiO 3/2 units (T units; in the formula, R 3 is the same as above) and/or tetrafunctional SiO 4/2 units (Q units) is from 0.65 to 1.40, and in which the amount of hydroxyl groups is 0.040 mol/100 g or less;
(C) from 0.1 to 50 parts by weight of a silica fine powder having a specific surface area according to the BET method of at least 50 m 2 /g;
(D) an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule, in an amount such that the number of silicon-bonded hydrogen atoms included on a molecule of component (D) per silicon-bonded alkenyl group in components (A) and (B) combined is from 1 to 10;
(E) an effective amount of a platinum family metal catalyst as a hydrosilylation reaction catalyst; and
(F) from 0.1 to 10 parts by weight of an organosilicon compound having on the molecule, as adhesion-promoting functional groups, an epoxy group and a silicon-bonded alkoxy group.
10. The addition-curable liquid silicone rubber composition for flame-resistant airbags of claim 9 , further comprising, as component (G): from 0.1 to 5 parts by weight, per 100 parts by weight of component (A), of at least one type of co-condensation catalyst selected from organotitanium compounds and organozirconium compounds.
11. The addition-curable liquid silicone rubber composition for flame-resistant airbags of claim 9 , wherein the addition-curable liquid silicone rubber composition has a viscosity at 25° C., as measured by the method described in JIS K 7117-1:1999, of from 1,000 to 1,000,000 mPa·s.