Liquid fluorosilicone sponge composition and molded product thereof

Abstract

To provide a liquid fluorosilicone sponge composition that exhibits a small density difference before and after heat curing, retains mechanical strength, and can be suitably applied to injection molding, and also to provide a molded product derived from heat-curing of the composition.SOLUTION: A liquid fluorosilicone sponge composition comprises the following essential components (A) to (E), and has a density difference of 0.03 g / cm3 or less before and after heat curing: (A) an organopolysiloxane containing a fluoroalkyl group, and having a viscosity of 100 to 500,000 mPa s at 25°C; (B) an organohydrogenpolysiloxane being free from a fluoroalkyl group; (C) an addition reaction catalyst: a catalytic amount; (D) a reinforcing silica filler treated with dimethyldichlorosilane: 10 to 60 pts.mass; and (E) pre-expanded resin fine particles with an organic resin shell, having a specific gravity of 0.01 to 0.3 and an average particle diameter of 10 to 200 μm: 1.0 to 20 pts.mass.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a liquid fluorosilicone sponge composition and a molded silicone sponge article obtained by heat curing said composition. [Background technology]

[0002] Since liquid fluorosilicone rubber compositions have a higher density than dimethylsilicone rubber, there has been a demand for lighter weight. In addition, liquid fluorosilicone rubber compositions can be processed using highly productive methods (Patent Document 1). In order to reduce the weight of fluorosilicone rubber, hollow powders made of inorganic substances such as glass and ceramics are known to be blended into the rubber. However, in the case of continuous molding, these hollow powders can cause wear on molding equipment, making their use difficult. If an attempt is made to use a pre-expanded resin balloon as a countermeasure, there is a problem in that the resin balloon deforms under pressure during molding, resulting in a high density after curing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-19560 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in view of the above circumstances, and has as its object to provide a liquid fluorosilicone sponge composition which exhibits a small difference in density before and after heat curing and which retains its mechanical strength, and which is particularly suitable for injection molding, and a molded article obtained by heat curing this composition. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention provides a thermoplastic elastomer composition comprising the following components (A) to (E) as essential components, and having a density difference of 0.03 g / cm before and after heat curing: 3A liquid fluorosilicone sponge composition is provided which is: (A) The following formula (1) [ka] (In the formula, R 1 are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, x is an integer of 1 to 10, m is an integer of 0 to 100, and n is an integer of 1 to 800, with the proviso that 5≦m+n≦800, and the bonds of the siloxane units bracketed by m and n may be block or random. and having a viscosity at 25°C of 100 to 500,000 mPa s: 100 parts by mass, (B) The following formula (2) [ka] (In the formula, R 2 are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, not including a fluoroalkyl group, and r is an integer of 5 to 100. or an organohydrogenpolysiloxane represented by the formula: (H(R 2 ) 2 SiO 1 / 2 ) units and SiO 4 / 2 An organohydrogenpolysiloxane having a three-dimensional network structure containing a unit as an essential structural unit (wherein R 2 is the same as above.): the number of hydrogen atoms bonded to silicon atoms in component (B) is 0.5 to 10 per silicon-bonded vinyl group in component (A); (C) an addition reaction catalyst: a catalytic amount, (D) Reinforcing silica filler obtained by treating the following (D-1) with the following (D-2): 10 to 60 parts by mass (D-1) Specific surface area by BET method is 50m 2 / g or more of dimethyldichlorosilane-treated fumed silica (D-2) an organosilicon compound represented by the following general formula (3), and [ka] (In the above formula (3), R 3 are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms; R 4 are each independently the above R 3 or a 3,3,3-trifluoropropyl group, where R 4 at least one of is a 3,3,3-trifluoropropyl group, and p is an integer of 1≦p≦20. (E) Expanded resin fine particles having an organic resin shell and a specific gravity of 0.01 to 0.3 and an average particle diameter of 10 to 200 μm: 1.0 to 20 parts by mass.

[0006] The liquid fluorosilicone sponge composition of the present invention provides a fluorosilicone sponge that exhibits a small difference in density before and after heat curing and retains its mechanical strength.

[0007] The present invention further provides a silicone sponge molded product which is a cured product of the above liquid fluorosilicone composition.

[0008] Silicone sponge molded articles, which are cured products obtained by heating and addition curing the composition of the present invention, have sufficient mechanical strength and can be produced easily and inexpensively. Effect of the Invention

[0009] The liquid fluorosilicone sponge composition of the present invention provides a fluorosilicone sponge that has a low density after heat curing and retains its mechanical strength. Such liquid addition-curable fluorosilicone sponge compositions are suitable as materials for casting, compression molding, and injection molding, and can therefore contribute to improving the productivity of molded products. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] As mentioned above, there has been a need for the development of a liquid fluorosilicone sponge composition which exhibits a small difference in density before and after heat curing and which retains its mechanical strength, and which is particularly suitable for injection molding, as well as molded articles obtained by heat curing such a composition.

[0011] The present inventors have conducted intensive research to solve the above problems, and have found that by blending an organosilicon compound having a trifluoropropyl group, a reinforcing silica filler that has been surface-treated with dimethyldichlorosilane, and pre-expanded resin particles having an organic resin shell into a liquid fluorosilicone sponge composition, and adding a specific crosslinking agent, it is possible to obtain a fluorosilicone sponge that has a small density difference before and after heat curing and maintains mechanical strength.Furthermore, the present inventors have found that the above liquid fluorosilicone sponge composition is suitable as a material for casting, compression molding, and injection molding, and have thus completed the present invention.

[0012] That is, the present invention comprises the following components (A) to (E) as essential components, and the density difference before and after heat curing is 0.03 g / cm 3 A liquid fluorosilicone sponge composition which is: (A) The following formula (1) [ka] (In the formula, R 1 are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, x is an integer of 1 to 10, m is an integer of 0 to 100, and n is an integer of 1 to 800, with the proviso that 5≦m+n≦800, and the bonds of the siloxane units bracketed by m and n may be block or random. and having a viscosity at 25°C of 100 to 500,000 mPa s: 100 parts by mass, (B) The following formula (2) [ka] (In the formula, R 2are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, not including a fluoroalkyl group, and r is an integer of 5 to 100. or an organohydrogenpolysiloxane represented by the formula: (H(R 2 ) 2 SiO 1 / 2 ) units and SiO 4 / 2 An organohydrogenpolysiloxane having a three-dimensional network structure containing a unit as an essential structural unit (wherein R 2 is the same as above.): the number of hydrogen atoms bonded to silicon atoms in component (B) is 0.5 to 10 per silicon-bonded vinyl group in component (A); (C) an addition reaction catalyst: a catalytic amount, (D) Reinforcing silica filler obtained by treating the following (D-1) with the following (D-2): 10 to 60 parts by mass (D-1) Specific surface area by BET method is 50m 2 / g or more of dimethyldichlorosilane-treated fumed silica (D-2) an organosilicon compound represented by the following general formula (3): [ka] (In the above formula (3), R 3 are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms; R 4 are each independently the above R 3 or a 3,3,3-trifluoropropyl group, where R 4 at least one of is a 3,3,3-trifluoropropyl group, and p is an integer of 1≦p≦20. (E) Expanded resin fine particles having an organic resin shell and a specific gravity of 0.01 to 0.3 and an average particle diameter of 10 to 200 μm: 1.0 to 20 parts by mass.

[0013] The present invention will be described in more detail below, but the present invention is not limited thereto.

[0014] (A) Vinyl-containing organopolysiloxane Component (A) is an organopolysiloxane represented by the following formula (1) and having a viscosity at 25°C of 100 to 500,000 mPa·s. [ka] (In the formula, R 1 are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, x is an integer of 1 to 10, m is an integer of 0 to 100, and n is an integer of 1 to 800, with the proviso that 5≦m+n≦800, and the bonds of the siloxane units bracketed by m and n may be block or random.

[0015] In the above formula (1), R 1 are each independently selected from alkyl groups having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a hexyl group, and a cyclohexyl group, aryl groups having 6 to 12 carbon atoms, such as a phenyl group, a tolyl group, and an aralkyl group having 7 to 12 carbon atoms, such as a benzyl group. Among these, alkyl groups having 1 to 8 carbon atoms are preferred, and a methyl group is particularly preferred.

[0016] m is an integer of 0 to 100, preferably an integer of 0 to 50, more preferably an integer of 0 to 30, further preferably an integer of 0 to 20, and most preferably an integer of 0 to 10. If m exceeds 100, the durability to hydrocarbon solvents decreases, which is not preferable.

[0017] n is an integer of 1 to 800, preferably an integer of 5 to 750, more preferably an integer of 10 to 650, still more preferably an integer of 50 to 650, and most preferably an integer of 100 to 650. If n exceeds 800, the viscosity of the material increases, making molding difficult, which is not preferable.

[0018] However, m+n is an integer satisfying 5≦m+n≦800, preferably 10≦m+n≦680, more preferably 60≦m+n≦680, and further preferably 120≦m+n≦680. If m+n is less than 5, the practical strength of the material is significantly reduced, and if it exceeds 800, the viscosity of the material becomes high, making molding difficult, which is undesirable.

[0019] x is an integer of 1 to 10, preferably 1 to 3, and most preferably x = 1. If x exceeds 10, the synthesis process becomes complicated, which is not preferable.

[0020] The viscosity of the organopolysiloxane (A) is characterized by being in the range of 100 to 500,000 mPa·s at 25°C, and is preferably in the range of 300 to 100,000 mPa·s. Within this range, the physical properties of the cured product are good, and the handling and workability of the composition are good. Furthermore, if the viscosity is less than 100 mPa·s, the strength of the resulting cured product is insufficient, and if it exceeds 500,000 mPa·s, the handling of the composition is reduced, which is not preferable. In the present invention, the viscosity is a value measured using a rotational viscometer according to the method described in JIS K 7117-1:1999.

[0021] The number of siloxane units having a fluoroalkyl group (i.e., the value of n) is preferably 10 mol % or more, more preferably 20 mol % or more, and particularly preferably 30 to 100 mol %, based on all siloxane units in the molecule (particularly the sum of difunctional siloxane units constituting the main chain (i.e., n+m). The upper limit is not particularly limited as long as it is 100 mol % or less, preferably 95 mol % or less, more preferably 90 mol % or less, and even more preferably 80 mol % or less. This range is preferable because it provides excellent durability to hydrocarbon solvents.

[0022] (B) Organohydrogenpolysiloxane Component (B) is a component that acts as a crosslinking agent (curing agent) when the present composition crosslinks. It is an organohydrogenpolysiloxane represented by the following formula (2) that is composed only of organosiloxy groups having hydrogen atoms in their side chains and terminal triorganosiloxy groups, or (H(R 2 ) 2 SiO 1 / 2 ) units and SiO 4 / 2 The organohydrogenpolysiloxane has a three-dimensional network structure and contains the unit as an essential structural unit (wherein R 2 is the following R 2 (This is the same as [ka] (In the formula, R 2 are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, not including a fluoroalkyl group, and r is an integer of 5 to 100. r is preferably an integer of 5 to 50, and more preferably an integer of 10 to 40. If r is less than 5, the practical strength of the material will be low, and if it exceeds 100, the physical properties of the molded product will change significantly over time, and either case is undesirable.

[0023] Examples of monovalent organic groups bonded to silicon atoms other than hydrogen atoms bonded to silicon atoms include unsubstituted or substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, that do not contain aliphatic unsaturated bonds, such as alkenyl groups. Examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl groups, aryl groups such as phenyl, tolyl, xylyl, and naphthyl groups, and benzyl groups. Methyl groups are preferred.

[0024] Component (B) is preferably liquid at room temperature (25° C.). The viscosity at 25° C. is preferably 0.1 to 1,000 mPa·s, more preferably 0.5 to 500 mPa·s, and even more preferably 1 to 200 mPa·s. If the viscosity is too low or too high, workability may decrease.

[0025] The three-dimensional network structure of organohydrogenpolysiloxane is (H(R 2 ) 2 SiO 1 / 2 ) unit (hereafter referred to as MH unit) and SiO 4 / 2 A unit (hereinafter referred to as a Q unit) is an essential structural unit (wherein, R 2 refers to an organohydrogenpolysiloxane with a three-dimensional network structure that is a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, does not contain a fluoroalkyl group, and contains two or more MH units (i.e., two or more Si-H groups (hydrogen atoms bonded to silicon atoms)) and one or more Q units in the molecule.

[0026] Here, the MH and Q units are essential structural units, but there is no (CH 3 ) 3 SiO 1 / 2 Unit (hereafter M unit), (CH 3 )SiO 3 / 2 Unit (hereafter T unit), HSiO 3 / 2 The effects of the present invention can be sufficiently obtained even when an organohydrogenpolysiloxane having a three-dimensional network structure containing any number of units (hereinafter referred to as TH units) is used.

[0027] The molar ratio of MH units to Q units in the molecule ([MH] / [Q]) is preferably about 0.3 to 1.5, and particularly preferably about 0.5 to 1.2, and the total of MH units and Q units relative to all siloxane units in the molecule is preferably 50 mol % or more (i.e., 50 to 100 mol %), and particularly preferably 75 mol % or more (75 to 100 mol %). Therefore, the total of the optional structural units M units, T units and TH units is desirably 50 mol % or less (0 to 50 mol %), and particularly preferably 25 mol % or less (0 to 25 mol %).

[0028] The viscosity of the organohydrogenpolysiloxane having a three-dimensional network structure is not particularly limited, but the viscosity at 25° C. is preferably 5 to 500 mPa·s, and more preferably 10 to 300 mPa·s.

[0029] The organohydrogenpolysiloxane having a three-dimensional network structure containing MH units and Q units as essential structural units of the component (B) may use either a single type alone or a combination of two or more types.

[0030] The amount of component (B) is such that the ratio of the number of silicon-bonded hydrogen atoms in component (B) to one silicon-bonded vinyl group in component (A) is within the range of 0.5 to 10, preferably 1 to 5. If the amount of component (B) is less than the lower limit of 0.5, the resulting composition will not cure sufficiently. If the amount of component (B) exceeds the upper limit of 10, the resulting silicone sponge will have poor heat resistance. When a vinyl-containing organosiloxane other than component (A) is included, as described below, it is sufficient that the ratio of the number of silicon-bonded hydrogen atoms in component (B) to the number of vinyl groups bonded to silicon atoms in the composition satisfies the above range.

[0031] (C) Addition reaction catalyst The addition reaction catalyst of component (C) may be any catalyst that promotes the addition reaction between the vinyl group in component (A) and the hydrogen atom bonded to the silicon atom in component (B). Usually, platinum group metal catalysts are preferably used. For example, platinum, palladium, rhodium, etc., platinum group metals or compounds thereof such as chloroplatinic acid, alcohol-modified chloroplatinic acid, coordination compounds of chloroplatinic acid with olefins, vinylsiloxanes or acetylene compounds, tetrakis(triphenylphosphine)palladium, chlorotris(triphenylphosphine)rhodium, etc. are listed, and platinum compounds are particularly preferred. Component (C) may be used alone or in combination of two or more.

[0032] The amount of component (C) to be blended may be an effective amount as a catalyst, but is usually 0.5 to 1,000 ppm, preferably 1 to 500 ppm, and more preferably 10 to 100 ppm, calculated as a catalytic metal element (platinum group metal element) by mass relative to the amount of component (A). If this range is satisfied, the reaction rate of the addition reaction becomes appropriate, and the heat resistance of the cured product becomes good.

[0033] (D) Reinforcing Silica Filler Component (D) is component (D-1) with a specific surface area of ​​50 m2 by the BET method. 2 / g or more, and then surface-treated with a linear organosilicon compound having silanol groups at both molecular chain terminals, which is component (D-2), as represented by the following formula (3): [ka] In the above formula (3), R 3 are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms. For example, 1 Examples of R are those described above, and a methyl group is preferred. 4 is the above R 3 or a 3,3,3-trifluoropropyl group, where R 4At least one of these is a 3,3,3-trifluoropropyl group. p is an integer of 1≦p≦20, and preferably an integer of 3 to 9. If p exceeds 20, the mechanical strength of the material may decrease, which is not preferable.

[0034] In the present invention, component (D) is essential for imparting mechanical strength to the resulting silicone rubber. If the organosilicon compound represented by formula (3) does not have a 3,3,3-trifluoropropyl group, the resin balloon of the resulting cured product will be prone to deformation due to pressure.

[0035] The component (D-1) may be either untreated dry silica treated with dimethyldichlorosilane by a known method, or commercially available dimethyldichlorosilane-treated silica.

[0036] The specific surface area of ​​the above component (D-1) by the BET method is 50 m 2 / g or more, and preferably 100 to 400m 2 / g, more preferably 150 to 350 m 2 / g. The specific surface area is 50m 2 If it is less than 400m / g, not only will sufficient strength not be obtained, but the appearance of the rubber molded product may also be poor. 2 / g or less, the compounding will not be difficult. The specific surface area of ​​the silica after the surface treatment, as measured by the BET method, may also be within the above range.

[0037] The amount of the organosilicon compound of formula (3) used to surface treat component (D-1) with component (D-2) is preferably 3 to 75 parts by mass, and more preferably 5 to 50 parts by mass, per 100 parts by mass of silica prior to surface treatment with the organosilicon compound of formula (3).

[0038] In addition to the above-mentioned (D-2) component, organosilanes or organosilazanes may be used as surface treatment agents. Examples of organosilanes include chlorosilanes such as trimethylchlorosilane, dimethyldichlorosilane, dimethylvinylchlorosilane, and trivinylchlorosilane, alkoxysilanes such as methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, trimethylmethoxysilane, triethylmethoxysilane, and vinyltris(methoxyethoxy)silane, and silazanes such as hexamethyldisilazane, hexamethylcyclotrisilazane, and 1,3-divinyl-1,1,3,3-tetramethyldisilazane, and among these, hexamethyldisilazane and 1,3-divinyl-1,1,3,3-tetramethyldisilazane are preferred. The amount of these organosilanes or organosilazanes used for surface treatment is preferably 0.25 to 37.5 parts by mass, and more preferably 0.25 to 25 parts by mass, per 100 parts by mass of surface-untreated silica.

[0039] The blend amount of component (D) is 10 to 60 parts by mass, and preferably 15 to 55 parts by mass, per 100 parts by mass of component (A). If the blend amount is less than the above lower limit of 10, the obtained silicone sponge will not have sufficient strength, and if it exceeds the above upper limit of 60, it will be difficult to blend it into the composition.

[0040] (E) Expanded resin microparticles having an organic resin shell The expanded resin particles having an organic resin shell are a component that imparts a gaseous portion to the cured rubber, thereby reducing the density like sponge rubber.

[0041] The organic resin shell of the expanded resin particles is not particularly limited, but may be vinylidene chloride, acrylic acid, or the like. Acrylonitrile, methacrylonitrile, acrylic acid esters and methacrylic acid esters It is preferable to adopt a polymer of a monomer selected from the group or a copolymer of two or more of the above monomers. The expanded resin microparticles used in the present invention are those which are obtained by heating and expanding unexpanded resin microparticles in a powder state in advance, in which a volatile substance or a low boiling point substance is encapsulated in the organic resin shell. When the expanded resin microparticles are blended, those which have an inorganic filler such as calcium carbonate or talc attached to the surface can also be blended in order to improve the strength of the expanded resin microparticles.

[0042] The above-mentioned expanded resin particles are in a state where the density of the silicone rubber sponge composition is sufficiently reduced. In order to provide the function, the true specific gravity is 0.01 to 0.3, preferably 0.01 to 0.25. If the true specific gravity is less than 0.01, not only is it difficult to mix and handle, but the pressure resistance of the expanded resin particles is insufficient, and they may break during mixing or molding, making it impossible to reduce the weight. Also, if the true specific gravity is more than 0.3, the density may not be reduced sufficiently.

[0043] The average particle diameter of the expanded resin particles is 10 to 200 μm, more preferably 50 to 150 μm. If the average particle diameter is larger than 200 μm, the expanded resin particles may be destroyed by the pressure during molding, resulting in high density or low durability. If the average particle diameter is less than 10 μm, the expanded resin particles may aggregate with each other, increasing the viscosity of the material and making molding difficult, which is not preferable. In the present invention, the average particle diameter refers to a value measured as a median diameter using a particle size distribution measuring device using a laser light diffraction method.

[0044] The amount of the expanded resin fine particles is 1.0 to 20 parts by mass, and preferably 1.5 to 18 parts by mass, per 100 parts by mass of the organopolysiloxane composition (A).

[0045] Other Ingredients The liquid fluorosilicone composition of the present invention may contain other components other than the components (A) to (D) as necessary. Examples of other components include conductive agents such as carbon black, conductive zinc oxide, and metal powder, hydrosilylation reaction inhibitors such as nitrogen-containing compounds, acetylene compounds, phosphorus compounds, nitrile compounds, carboxylates, tin compounds, mercury compounds, and sulfur compounds, heat resistance imparting agents such as iron oxide and cerium oxide, compression set improvers such as triazole compounds and benzotriazole derivatives, internal release agents such as dimethyl silicone oil, adhesion imparting agents, and thixotropy imparting agents. However, the liquid fluorosilicone composition of the present invention does not contain an isocyanuric acid derivative having three trialkoxy groups in one molecule.

[0046] The liquid fluorosilicone sponge composition of the present invention can be prepared by uniformly mixing the above-mentioned components (A) through (E), and, if necessary, each of the optional components, using a conventional mixer / stirrer, kneader or other such device.

[0047] The liquid fluorosilicone composition of the present invention can also be of the two-liquid type. In this case, the components (B) as a crosslinking agent and (C) as an addition reaction catalyst can be appropriately divided so that they are not mixed in the same composition (Liquid A or Liquid B). For example, a two-liquid type composition can be made consisting of Liquid A containing Components (A), (C), and (D), and Liquid B containing Components (A), (B), and (D), and it is preferable to prepare it so that they can be mixed in equal masses or volumes.

[0048] The liquid fluorosilicone sponge composition of the present invention can be used in a variety of molding methods, including cast molding, compression molding, injection molding, etc. Below, the methods of molding silicone sponges by cast molding, compression molding, or injection molding are explained in detail.

[0049] In the case of injection molding, the liquid fluorosilicone composition of the present invention is divided into a two-component type of liquid A and liquid B. The materials divided into two components are mixed in equal amounts of each liquid A and liquid B, injected into a metal mold, heated in a thermostatic bath to cure, and a silicone sponge is formed. In the case of compression molding, a metal mold is installed in a compressor such as a press machine, the above liquid A and liquid B are mixed in equal amounts in the same manner as in injection molding, injected into the mold, heated to cure, and a silicone sponge is formed. In the case of injection molding, each of liquid A and liquid B is supplied from a material supply pump to a metering device. Liquid A and liquid B merge from the metering device at an equal ratio through a material supply line. The material is mixed in the screw part and cylinder part of the molding machine body. Then, it is injected into the mold, heated in the mold to cure, and a silicone sponge is formed.

[0050] As the curing and molding (primary cure) conditions of the liquid fluorosilicone composition of the present invention, they may be the same as those of known addition reaction-curing type silicone compositions. The curing temperature is 80 to 220 °C, particularly 120 to 200 °C, and the curing time is 3 seconds to 10 minutes, particularly 5 seconds to 5 minutes. It can be cured and molded by heating. The molded cured product may be post-cured (secondary cure) at, for example, 180 to 220 °C for about 30 minutes to 6 hours as necessary.

[0051] The silicone sponge molded product obtained by heat-curing the liquid fluorosilicone sponge composition of the present invention is excellent in gasoline resistance and oil resistance. Therefore, it can be suitably used for aircraft and in-vehicle rubber parts, printer parts, etc. In recent years, it can also be suitably used for mobile parts from the point of sebum resistance and fuel cell vehicle seal parts from the point of acid resistance.

Examples

[0052] Hereinafter, the present invention will be specifically described using examples and comparative examples, but the present invention is not limited thereto.

[0053] The components used in the examples and comparative examples are shown below.

[0054] (Component (A-1)) The following formula (4) [ka] The viscosity of the trifluoropropylmethylpolysiloxane shown in the formula (1) is 76.6 Pa s at 25°C and is end-capped with dimethylvinylsiloxy groups (vinyl group amount: 4.6×10 -5 mol / g Component (A-2) Dimethylpolysiloxane with a degree of polymerization of 300 and a viscosity of 3 Pa s at 25°C, both ends of which are capped with dimethylvinylsiloxy groups [vinyl group amount 6.7 x 10 -5 mol / g

[0055] (B) Crosslinker: Component (B-1): Methylhydrogenpolysiloxane represented by the following formula (5): [Hydrosilyl group content: 0.0145 mol / g] [ka] Component (B-2): Organohydrogenpolysiloxane with a three-dimensional network structure containing MH units and Q units, with a viscosity of 40 mPa·s at 25°C [hydrosilyl group content: 0.0102 mol / g] Component (B-3): Methylhydrogenpolysiloxane represented by the following formula (6) [hydrosilyl group content: 0.0049 mol / g] [ka] Component (B-4) Methylhydrogenpolysiloxane having hydrosilyl groups at both ends and on the side chains, with a degree of polymerization of 17 [hydrosilyl group content: 0.006 mol / g]

[0056] (C) Platinum catalyst (Pt concentration 0.5% by mass)

[0057] (D) Component (D-1) Specific surface area by BET method is 200m 2 / g and surface-treated with dimethyldichlorosilane (Aerosil R-974, manufactured by Nippon Aerosil Co., Ltd.) (D-2) An organosilicon compound represented by the following formula (7): [ka]

[0058] Component (E) Expanded resin particles: Product name F80DE (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., average particle size 100 μm, true specific gravity 0.0225

[0059] (Other Ingredients) Reaction control agent: ethynylcyclohexanol Reaction inhibitor: Benzotriazole 10% by mass in ethanol

[0060] The silicone rubber base used in the examples and comparative examples was prepared as follows.

[0061] [Preparation Example 1] The trifluoropropylmethylpolysiloxane (A-1) represented by the above formula (4) [vinyl group content: 4.6×10 -5 mol / g] 31.4 parts by mass, 22.9 parts by mass of the fumed silica of the component (D-1) as a reinforcing silica filler of the component (D), 3.4 parts by mass of the organosilicon compound of the component (D-2) represented by the above formula (8), 0.3 parts by mass of water, and 0.2 parts by mass of 1,3-divinyl-1,1,3,3-tetramethyldisilazane were mixed at 25°C for 30 minutes, and then heated to 160°C and stirred for 3 hours. Furthermore, 34.3 parts by mass of the trifluoropropylmethylpolysiloxane of the component (A-1) represented by the above formula (4) was added, and after mixing for 30 minutes, a silicone rubber base 1 was obtained. In addition, the amount of the component (D) per 100 parts by mass of the component (A-1) in the obtained silicone rubber base was 35 parts by mass.

[0062] [Preparation Example 2] Component (A-2) is a dimethylpolysiloxane having a degree of polymerization of 300 and both ends capped with dimethylvinylsiloxy groups [vinyl group content: 6.7×10 -5mol / g] 31.4 parts by mass, the above fumed silica of the component (D-1) as a reinforcing silica filler of the component (D), 22.9 parts by mass of the organosilicon compound represented by the above formula (8) of the component (D-2), 0.3 parts by mass of water, and 0.2 parts by mass of 1,3-divinyl-1,1,3,3-tetramethyldisilazane were mixed at 25°C for 30 minutes, and then the temperature was raised to 160°C and stirring was continued for 3 hours. Furthermore, 34.3 parts by mass of dimethylpolysiloxane of the component (A-2) with a polymerization degree of 300 and both ends blocked with dimethylvinylsiloxy groups was added, and after mixing for 30 minutes, a silicone rubber base 2 was obtained. In addition, the amount of the component (D) per 100 parts by mass of the component (A-2) in the obtained silicone rubber base was 35 parts by mass.

[0063] [Preparation Example 3] The component (A-1) is a trifluoropropylmethylpolysiloxane represented by the above formula (4) [vinyl group content: 4.6×10 -5 31.4 parts by mass of the above-mentioned fumed silica as component (D-1) as a reinforcing silica filler for component (D), 22.9 parts by mass of the above-mentioned organosilicon compound represented by the above formula (8) as component (D-2), 0 part by mass of water, and 0.2 parts by mass of 1,3-divinyl-1,1,3,3-tetramethyldisilazane were mixed at 25° C. for 30 minutes, but the mixture did not come together and could not be proceeded to the next step.

[0064] [Examples 1 and 2, Comparative Examples 1 to 3] Silicone sponge compositions A to E of Examples 1 and 2 and Comparative Examples 1 to 3 were prepared in the amounts shown in Table 1 below. The resulting compositions were press cured at 120°C for 10 minutes to obtain cured products. The general physical properties of density, hardness, tensile strength, and elongation at break of the resulting cured products after heat curing were measured. Specifically, hardness (type A durometer hardness), tensile strength, and elongation at break were measured according to the description of JIS K 6249:2003, and density was measured by the method described below. The results are shown in Table 1.

[0065] The density before heat curing was measured by the following method, and the results are shown in Table 1. ·Measuring device: automatic density meter · Stabilize the water temperature of the automatic density meter at 23±0.5℃. · Attach a clamp to the automatic density meter to adjust the weight to zero. · A clip is used to attach the copper plate, which is then hung from the clamp of an automatic density meter, and its weight in air (W1) is measured. After immersing the copper plate in water, measure its weight underwater (W2). Remove the copper plate from the water, thoroughly wipe off any adhering moisture, and apply 0.6 to 0.8 g of the sample with a spatula below the center of the copper plate surface. Immediately hang it from the clamp and measure the weight (W3) of the copper plate and sample. After immersing the copper plate + sample in water, measure the weight in water (W4). Remove the copper plate and sample from the water and thoroughly wipe off any remaining sample. Calculate the density at 23℃ using the following formula: Density (g / cm 3 )=(W3-W1) / {(W3-W1) / (W4-W2)} The density after heat curing was measured based on the description of JIS K 6249:2003. The results are shown in Table 1.

[0066] [Table 1]

[0067] As can be seen from each of the Examples and Comparative Examples in Table 1, the liquid fluorosilicone sponge compositions of Examples 1 and 2 (the present invention) contained a fluoroalkyl group-containing component (A) (component (A-1)), and a fluoroalkyl group-free component (B), and as a result, the difference in density before and after heat curing was 0.03 g / cm 3 It was found that:

[0068] On the other hand, in Comparative Example 1, in which the component (B) having a fluoroalkyl group was used, and in Comparative Example 3, in which the component (A) having no fluoroalkyl group was used, the difference in density before and after heat curing was 0.03 g / cm 3 It was found to exceed this.

[0069] Furthermore, in Comparative Example 2 which did not contain the component (B), the composition remained uncured and no cured product was formed.

[0070] Thus, it has been found that the present invention provides a liquid fluorosilicone sponge composition which has a small difference in density before and after heat curing and which retains its mechanical strength, making it particularly suitable for injection molding, and the cured product obtained by heat curing this composition.

[0071] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention.

Claims

1. The following components (A) to (E) are essential components, and the density difference before and after heat curing is 0.03 g / cm ３ A liquid fluorosilicone sponge composition which is: (A) Formula (1) below 【Chemistry 1】 (In the formula, R １ are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, x is an integer from 1 to 10, m is an integer from 0 to 100, and n is an integer from 1 to 800, with the proviso that 5≦m+n≦800, and the bonds of the siloxane units bracketed by m and n may be in a block or random fashion. and having a viscosity at 25°C of 100 to 500,000 mPa·s: 100 parts by mass, (B) The following formula (2) 【Chemistry 2】 (In the formula, R ２ are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, not including a fluoroalkyl group, and r is an integer of 5 to 100. or an organohydrogenpolysiloxane represented by the formula: (H(R ２ ) ２ SiO １／２ ) units and SiO ４／２ Organohydrogenpolysiloxane having a three-dimensional network structure containing a unit as an essential structural unit (wherein R ２ is the same as above.): an amount such that the number of hydrogen atoms bonded to silicon atoms in component (B) is 0.5 to 10 per silicon-bonded vinyl group in component (A); (C) an addition reaction catalyst: a catalytic amount, (D) Reinforcing silica filler obtained by treating the following (D-1) with the following (D-2): 10 to 60 parts by mass (D-1) BET specific surface area of ​​50 m ２ / g or more of dimethyldichlorosilane-treated dry silica (D-2) an organosilicon compound represented by the following general formula (3): 【Chemistry 3】 (In the above formula (3), R ３ are each independently a group selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms; R ４ are each independently the above R ３ or a 3,3,3-trifluoropropyl group, where R ４ at least one of is a 3,3,3-trifluoropropyl group, and p is an integer of 1≦p≦20. (E) Expanded resin fine particles having an organic resin shell and a specific gravity of 0.01 to 0.3 and an average particle diameter of 10 to 200 μm: 1.0 to 20 parts by mass.

2. A silicone sponge molded product which is a cured product of the liquid fluorosilicone composition according to claim 1.

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