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KR-102964445-B1 - ADDITION-CURABLE SILICONE COMPOSITION

KR102964445B1KR 102964445 B1KR102964445 B1KR 102964445B1KR-102964445-B1

Abstract

The present invention relates to an addition-curing silicone composition comprising: (A) an organopolysiloxane having at least two silicon atom-bonded alkenyl groups (Si-alkenyl) per molecule; (B) an organohydrogenpolysiloxane having at least three silicon atom-bonded hydrogen atoms (Si-H) per molecule, containing at least one SiO 4/2 repeating unit per molecule, and having a content of 30 to 40 mol% of the SiO 4/2 repeating unit; (C) silica; (D) an addition-curing catalyst; and (E) a reaction retardant.

Inventors

  • 오용환
  • 원석재
  • 최수연
  • 박지현

Assignees

  • 주식회사 케이씨씨실리콘

Dates

Publication Date
20260513
Application Date
20221221

Claims (8)

  1. (A) Organopolysiloxane having at least two silicon atom bonded alkenyl groups (Si-alkenyl) per molecule; (B) an organohydrogenpolysiloxane having at least 3 silicon atom-bonded hydrogen atoms (Si-H) per molecule, containing at least 1 SiO 4/2 repeating unit per molecule, and having a SiO 4/2 repeating unit content of 30 to 40 mol%; (C) Silica; (D) catalyst for addition curing; and (E) reaction retardant; including, The above organopolysiloxane (A) comprises a first organopolysiloxane (A-1) having a weight-average molecular weight of 10,000 to 50,000 g/mol and a second organopolysiloxane (A-2) having a weight-average molecular weight of more than 50,000 g/mol and less than or equal to 100,000 g/mol, and The above organohydrogenpolysiloxane (B) is an addition-curing silicone composition having a Si-H content of 1 to 20 mmol/g and a viscosity of 500 mPa·s or less at 25°C.
  2. In claim 1, The above organopolysiloxane (A) is an addition-curing silicone composition having an alkenyl group content of 0.0005 to 5 mmol/g, a degree of polymerization of 100 to 2,000, and a viscosity of 500 to 150,000 mPa·s at 25°C.
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  5. In claim 1, The above organopolysiloxane (A) is an addition-curing silicone composition represented by the following chemical formula 1: [Chemical Formula 1] (R 1 R 2 2 SiO 1/2 ) 2 (R 3 R 4 SiO) a (R 5 2 SiO) b In Chemical Formula 1, R1 and R3 are each independently substituted or unsubstituted C1-6 alkyl groups or C2-6 alkenyl groups, and R2 , R4 , and R5 are each independently substituted or unsubstituted C1-6 alkyl groups or C6-15 aryl groups, and a and b are each independently greater than or equal to 0 integers, and a + b is 100 to 2,000.
  6. In claim 1, The above organohydrogenpolysiloxane (B) is an addition-curing silicone composition represented by the following chemical formula 2: [Chemical Formula 2] (SiO 4/2 ) c (SiO 1/2 R 6 R 7 H) d In Chemical Formula 2, R6 and R7 are each independently substituted or unsubstituted C1-10 alkyl groups, and c and d are each independently integers greater than or equal to 1, and c+d is 5 to 200.
  7. In claim 1, An addition-curing silicone composition comprising 100 parts by weight of organopolysiloxane (A), 1 to 10 parts by weight of organohydrogenpolysiloxane (B), 31 to 45 parts by weight of silica (C), 0.0003 to 0.3 parts by weight of an addition-curing catalyst (D), and 0.05 to 3 parts by weight of a reaction retardant (E).
  8. In claim 1, Addition-curing silicone composition for fuel cell separator gaskets.

Description

Addition-curable silicone composition The present invention relates to an addition-curing silicone composition having excellent moldability and acid resistance, and in which inorganic metal ions that can cause a decrease in output during fuel cell operation are not eluted. A fuel cell is a device that converts the chemical energy contained in fuels such as hydrogen and methanol into electrical and thermal energy using electrochemical reactions. Such fuel cells typically include multiple unit cells, each consisting of a Membrane-Electrode Assembly (MEA) containing two electrodes and an electrolyte, and a separator. For example, a fuel cell typically includes a stack, which is a structure in which several to hundreds of unit cells are stacked. The separator blocks the space between each MEA to prevent gas mixing, acts as a passage to supply hydrogen gas or air to each MEA, and also serves as a conductor connecting the MEAs. In addition, to maintain airtightness regarding the reaction gases hydrogen/air (or oxygen) and cooling water in the fuel cell stack, a gasket is typically applied to each separator. Generally, fluorine elastomers, silicone elastomers, and hydrocarbon elastomers are widely used as gaskets for fuel cell stacks. These conventional gaskets improve the acid resistance of the composition by including a filler containing inorganic metal ions in the composition. Specifically, Korean Published Patent No. 2017-0003415 (Patent Document 1) discloses a seal material for a solid polymer fuel cell separator comprising a silicone rubber composition and a layered double hydroxide compounded therewith. Furthermore, magnesium and aluminum-containing hydrotalcite is disclosed as a specific example of the layered double hydroxide. However, as described in Patent Document 1, inorganic fillers containing cationic metal ions such as magnesium and aluminum had the disadvantage that metallic cations were leached out during the operation of the fuel cell, and said metallic cations were adsorbed onto the electrolyte membrane, which is a major component of electricity generation, thereby reducing the efficiency of the fuel cell. Therefore, there is a need for research and development on silicone compositions for fuel cell separator gaskets that do not leach inorganic metal ions, which can cause output degradation during fuel cell operation, and possess excellent moldability and acid resistance. The present invention will be described in detail below. The "weight-average molecular weight" used in this specification is measured by conventional methods known in the art, and can be obtained as a polystyrene equivalent value from the measurement of molecular weight distribution (degree of polymerization distribution) by, for example, the GPC (gel permeation chromatograph) method. Functional group content, such as 'Si-H content', 'SiO 4/2 repeating unit content', and 'alkenyl group content', can be measured by methods well known in the art and can be calculated through structural analysis, such as H-NMR, C-NMR, and Si-NMR. In addition, "viscosity" is measured by conventional methods known in the art, and can be measured, for example, by a cone-and-plate viscometer or a Brookfield viscometer. Addition-curing silicone composition The addition-curing silicone composition according to the present invention comprises (A) organopolysiloxane; (B) organohydrogenpolysiloxane; (C) silica; (D) an addition-curing catalyst; and (E) a reaction retardant. (A) Organopolysiloxane Organopolysiloxane (A) is the main resin and serves to impart elasticity to the manufactured coating film. The above organopolysiloxane has at least two silicon atom bonded alkenyl groups (Si-alkenyl) per molecule. For example, the organopolysiloxane above may be represented by the following chemical formula 1. [Chemical Formula 1] (R 1 R 2 2 SiO 1/2 ) 2 (R 3 R 4 SiO) a (R 5 2 SiO) b In Chemical Formula 1, R1 and R3 are each independently a substituted or unsubstituted C1-6 alkyl group or a C2-6 alkenyl group, and R2 , R4 , and R5 are each independently substituted or unsubstituted C1-6 alkyl groups or C6-15 aryl groups, and a and b are each independently greater than or equal to 0 integers, and a + b is 100 to 2,000. The above alkyl group may be, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, or a hexyl group, the above alkenyl group may be, for example, a vinyl group, an allyl group, a butenyl group, a pentenyl group, or a hexenyl group, and the above aryl group may be, for example, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, or a biphenyl group. Specifically, the organopolysiloxane may include vinyldimethyl-terminated dimethyl polymer ((ViMe 2 SiO 1/2 )(Me 2 SiO) n (ViMe 2 SiO 1/2 )), vinyldimethyl-terminated methylvinyldimethyl block polymer ((ViMe 2 SiO 1/2 )(Me 2 SiO) n (ViMeSiO) m (ViMe 2 SiO 1/2 )), trimethyl-terminated methylvinyldimethyl block polymer ((Me 3 SiO 1/2 )(Me 2 SiO) n (ViMeSiO)