Liquid addition-curing fluorosilicone composition, fluorosilicone rubber, and molded article

Abstract

To provide a liquid addition-curing type fluorosilicone composition which has good curability, holds mechanical strength, and is suitable for injection molding.SOLUTION: An addition-curing type fluorosilicone composition contains (A) vinyl group-containing organopolysiloxane which is represented by the following general formula (1) and has viscosity at 25°C of 100-500,000 mPa s, (B) branched organohydrogen polysiloxane having three or more silicon atom-bonded hydrogen atoms in one molecule: the number of hydrogen atoms bonded to the silicon atom in the component (B) of 0.5 to 10 per one silicon atom-bonded vinyl group in the composition, (C) an addition reaction catalyst: a catalyst amount, and (D) a reinforcing silica filler surface-treated with an organosilicon compound: 10-60 pts.mass with respect to 100 pts.mass of the component (A), and the composition being liquid at 23°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid addition-curing type fluorosilicone composition, a fluorosilicone rubber obtained by heat curing the composition, and a molded article thereof. [Background technology]

[0002] Conventionally, addition-curing fluorosilicone rubber compositions have been used in aircraft and automotive rubber parts, printer parts, etc., due to their excellent gasoline and oil resistance (Patent Document 1). In recent years, they have also been considered for use in mobile device components due to their sebum resistance, and for sealing parts in fuel cell vehicles due to their acid resistance. Addition-curing fluorosilicone rubber compositions used in these parts are required to have low compression set and maintain practical strength, i.e., mechanical strength. In particular, there has been a desire for the development of a liquid addition-curing fluorosilicone rubber composition with excellent productivity. While processing methods with excellent productivity include using molds, injection molding, compression molding, and injection molding, liquid addition-curing fluorosilicone rubber compositions have the problem that they can only be used if their viscosity is suitable for these processing methods. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2013-047290 [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention has been made in view of the above circumstances, and aims to provide a liquid addition-curing type fluorosilicone composition that has good curability, maintains mechanical strength, and is suitable for injection molding and the like. It also aims to provide a fluorosilicone rubber obtained by heat curing the above composition and a molded article thereof. [Means for solving the problem]

[0005] To solve the above problems, the present invention provides an addition-curing fluorosilicone composition comprising (A) the following general formula (1) [ka] (In the formula, R 1 Rf is a group independently selected from C1-C8 alkyl groups, C6-C12 aryl groups, and C7-C12 aralkyl groups; Rf is a group independently selected from C1-C10 perfluoroalkyl groups and C3-C30 perfluoropolyether groups; X is a divalent organic group; m is an integer from 0 to 100; and n is an integer from 1 to 800, where 5 ≤ m + n ≤ 800. A vinyl group-containing organopolysiloxane, as shown, has a viscosity of 100 to 500,000 mPa·s at 25°C. (B) The following formula (3) has three or more silicon-bonded hydrogen atoms in one molecule [ka] (In the above equation (3), R 4 Rf is a group independently selected from C1-C8 alkyl groups, C6-C12 aryl groups, or C7-C12 aralkyl groups; Rf is a group independently selected from C1-C10 perfluoroalkyl groups and C3-C30 perfluoropolyether groups; and X is a divalent organic group. x1 is a number between 2 ≤ x1 ≤ 4, x2 is an integer between 0 ≤ x2 ≤ 20, x3 is an integer between 0 ≤ x3 ≤ 20, satisfying 0 ≤ x2 + x3 ≤ 20, y1 is an integer between 0 ≤ y1 ≤ 30, z1 is an integer between 0 ≤ z1 ≤ 10, y2 is an integer between 0 ≤ y2 ≤ 30, z2 is an integer between 0 ≤ z2 ≤ 10, and z1 + z2 > 0. Branched organohydrogenpolysiloxane represented by: (B) an amount such that the number of hydrogen atoms bonded to the silicon atom in component (B) is 0.5 to 10 per silicon atom bonded vinyl group in the composition, (C) Addition reaction catalyst: amount of catalyst, and (D) Reinforcing silica filler surface-treated with an organosilicon compound represented by the following general formula (2) [Chemical formula] (In the above formula (2), R 3 are independently selected from a group consisting of 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, and R 2 are independently a group represented by the above R 3 or a 3,3,3-trifluoropropyl group, provided that at least one of R 2 is a 3,3,3-trifluoropropyl group, and p is an integer of 1 ≦ p ≦ 20.): 10 to 60 parts by mass with respect to 100 parts by mass of component (A) is contained, Provided is an addition-curable fluorosilicone composition characterized in that the addition-curable fluorosilicone composition is liquid at 23°C.

[0006] The addition-curable fluorosilicone composition of the present invention has good curability, retains mechanical strength, and is suitable for injection molding and the like.

[0007] Further, the present invention provides a fluorosilicone rubber characterized in that it is a cured product of the above addition-curable fluorosilicone composition.

[0008] The fluorosilicone rubber of the present invention retains good mechanical strength.

[0009] Further, the present invention provides a fluorosilicone rubber molded product characterized in that it is a molded product of the above fluorosilicone rubber.

[0010] The fluorosilicone rubber molded product of the present invention is excellent in gasoline resistance and oil resistance, and thus can be suitably used for aircraft and in-vehicle rubber parts, printer parts, etc. It can also be suitably used for mobile parts from the point of sebum resistance and for fuel cell vehicle seal parts from the point of acid resistance. [Advantages of the Invention]

[0011] The addition-curing fluorosilicone composition of the present invention is liquid and cures rapidly even at relatively low temperatures, resulting in good curability and providing a fluorosilicone rubber that maintains mechanical strength. Furthermore, since this liquid addition-curing fluorosilicone composition is suitable as a material for injection molding, compression molding, and injection molding, it can contribute to improving the productivity of molded products. [Modes for carrying out the invention]

[0012] The present inventors, through diligent research to achieve the above objectives, have discovered that by using a hydrogen polysiloxane of a specific structure in an addition-curing type fluorosilicone composition that is liquid at 23°C, a fluorosilicone rubber with good curability and maintained mechanical strength can be obtained. Furthermore, they have found that this liquid addition-curing type fluorosilicone composition is suitable as a material for injection molding, compression molding, and injection molding, leading to the present invention. Specifically, the present invention provides the following fluorosilicone composition, fluorosilicone rubber, and molded articles thereof.

[0013] That is, the present invention relates to an addition-curing type fluorosilicone composition, (A) General formula (1) below [ka] (In the formula, R 1 Rf is a group independently selected from C1-C8 alkyl groups, C6-C12 aryl groups, and C7-C12 aralkyl groups; Rf is a group independently selected from C1-C10 perfluoroalkyl groups and C3-C30 perfluoropolyether groups; X is a divalent organic group; m is an integer from 0 to 100; and n is an integer from 1 to 800, where 5 ≤ m + n ≤ 800. A vinyl group-containing organopolysiloxane, as shown, has a viscosity of 100 to 500,000 mPa·s at 25°C. (B) The following formula (3) has three or more silicon-bonded hydrogen atoms in one molecule [ka] (In the above formula (3), R 4 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, or an aralkyl group having 7 to 12 carbon atoms; Rf are each independently a group selected from a perfluoroalkyl group having 1 to 10 carbon atoms and a perfluoropolyether group having 3 to 30 carbon atoms; X is a divalent organic group. x1 is a number of 2 ≤ x1 ≤ 4, x2 is an integer of 0 ≤ x2 ≤ 20, x3 is an integer of 0 ≤ x3 ≤ 20, and 0 ≤ x2 + x3 ≤ 20 is satisfied. y1 is an integer of 0 ≤ y1 ≤ 30, z1 is an integer of 0 ≤ z1 ≤ 10, y2 is an integer of 0 ≤ y2 ≤ 30, and z2 is an integer of 0 ≤ z2 ≤ 10, and z1 + z2 > 0.) The branched organohydrogenpolysiloxane represented by:(B) the amount such that the number of hydrogen atoms bonded to the silicon atoms in the component is 0.5 to 10 per vinyl group bonded to a silicon atom in the composition, (C) Addition reaction catalyst: a catalytic amount, and (D) Reinforcing silica filler surface-treated with an organosilicon compound represented by the following general formula (2)

Chemical formula

[0014] The fluorosilicone composition of the present invention contains, as a main component, a linear polysiloxane whose main chain consists of repeating diorganosiloxane units having a fluoroalkyl group. On the other hand, a typical dimethylsilicone composition uses a linear dimethylpolysiloxane whose main chain consists of repeating dimethylsiloxane units as its main component. In this respect, the fluorosilicone composition of the present invention is essentially different from a dimethylsilicone composition.

[0015] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0016] The addition-curing fluorosilicone composition of the present invention is characterized by containing (A) a vinyl group-containing organopolysiloxane having a specific viscosity at 25°C of 100 to 500,000 mPa·s, (B) a specific branched organohydrogenpolysiloxane having three or more silicon atom-bonded hydrogen atoms in one molecule, (C) an addition reaction catalyst, and (D) a reinforcing silica filler surface-treated with a specific organosilicon compound, and being liquid at 23°C. The composition may further contain components other than those listed above (A) to (D). These components will be described below.

[0017] (A) Vinyl group-containing organopolysiloxane Component (A) is an organopolysiloxane represented by the following general formula (1), having a viscosity of 100 to 500,000 mPa·s at 25°C. [ka] (In the formula, R 1 Rf is a group independently selected from C1-C8 alkyl groups, C6-C12 aryl groups, and C7-C12 aralkyl groups; Rf is a group independently selected from C1-C10 perfluoroalkyl groups and C3-C30 perfluoropolyether groups; X is a divalent organic group; m is an integer from 0 to 100; and n is an integer from 1 to 800, where 5 ≤ m + n ≤ 800.

[0018] Preferably, it is a perfluoroalkyl group-containing organopolysiloxane represented by the following formula (1'). [ka] (In the formula, R 1 The groups are independently selected from alkyl groups with 1 to 8 carbon atoms, aryl groups with 6 to 12 carbon atoms, and aralkyl groups with 7 to 12 carbon atoms, where k is an integer from 1 to 10, m is an integer from 0 to 100, and n is an integer from 1 to 800, where 5 ≤ m + n ≤ 800.

[0019] In the above equation (1), R 1 These groups may be independently selected from C1-C8 alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, hexyl, and cyclohexyl groups, C6-C12 aryl groups such as phenyl and tolyl groups, and C7-C12 aralkyl groups such as benzyl groups. Among these, C1-C8 alkyl groups are preferred, and methyl groups are particularly preferred.

[0020] In formula (1) above, Rf is independently selected from perfluoroalkyl groups having 1 to 10 carbon atoms and perfluoropolyether groups having 3 to 30 carbon atoms. The perfluoroalkyl groups are as follows: C k F 2k+1 - (k is an integer between 1 and 10) Examples include the following formula for the perfluoropolyether group. [ka] (s and t are integers from 1 to 9) Examples are given.

[0021] Furthermore, in formula (1) above, X is a divalent organic group. X functions as a spacer connecting the main chain of the linear vinyl group-containing organopolysiloxane of component (A) and the Rf groups of the side chains, and can adjust the interactions between Rf groups or between Rf groups and other molecules to make the properties of the cured product, such as its hydrocarbon solvent resistance, desirable. The divalent organic group is not particularly limited, but can be an alkylene group having 2 to 4 carbon atoms, and some of the hydrogen atoms of the alkylene group may be substituted with fluorine atoms, etc., and it may have oxygen atoms, ester bonds, or amide bonds in the middle or at the end. Examples of this divalent organic group include those shown in the following formula. [ka] (* indicates a bond with an Rf group, and ** indicates a bond with a silicon atom.)

[0022] As for the Rf-X group, C k F 2k+1 A -CH2CH2 group (where k is an integer from 1 to 10) is preferred, and a 3,3,3-trifluoropropyl group (where k is 1) is more preferred.

[0023] m is an integer between 0 and 100, preferably between 0 and 50, more preferably between 0 and 30, even more preferably between 0 and 20, and most preferably between 0 and 10. n is an integer between 1 and 800, preferably between 5 and 750, more preferably between 10 and 650, even more preferably between 50 and 650, and most preferably between 100 and 650. However, (m+n) is an integer between 5≦m+n≦800, preferably between 10≦m+n≦680, more preferably between 60≦m+n≦680, and even more preferably between 120≦m+n≦680.

[0024] 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 most preferably 30 to 100 mol% of the total siloxane units in the molecule (in particular, the sum of the bifunctional siloxane units constituting the main chain (i.e., n + m)). The upper limit is not particularly limited and should be 100 mol% or less, and may be 95 mol% or less, 90 mol% or less, or 80 mol% or less. This range is preferable because it allows for excellent hydrocarbon solvent resistance.

[0025] (A) The viscosity of the organopolysiloxane is characterized by being in the range of 100 to 500,000 mPa·s at 25°C, and 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 of the composition is also good. Furthermore, if the viscosity is less than 100 mPa·s, the strength of the resulting cured product will be insufficient, and if it exceeds 500,000 mPa·s, the handling of the composition will deteriorate, which is undesirable. In this invention, viscosity is the value measured by a rotational viscometer using the method described in JIS K 7117-1:1999. (A) The degree of polymerization of the organopolysiloxane is the value at which the viscosity at 25°C falls within the above range.

[0026] (B) Organohydrogenpolysiloxane Component (B) is a branched organohydrogenpolysiloxane represented by the following formula (3), having three or more silicon-bonded hydrogen atoms in one molecule. This organohydrogenpolysiloxane undergoes a hydrosilylation addition reaction with component (A) and acts as a curing agent (crosslinking agent). The molecular structure of component (B) is a terminally hydrogen-modified branched siloxane, and by including this organohydrogensiloxane, the fluorosilicone composition can be rapidly cured, and the cured fluorosilicone rubber can be made to have high strength.

[0027] [ka] (In the above equation (3), R 4Rf is a group independently selected from C1-C8 alkyl groups, C6-C12 aryl groups, or C7-C12 aralkyl groups; Rf is a group independently selected from C1-C10 perfluoroalkyl groups and C3-C30 perfluoropolyether groups; and X is a divalent organic group. x1 is a number between 2 ≤ x1 ≤ 4, x2 is an integer between 0 ≤ x2 ≤ 20, x3 is an integer between 0 ≤ x3 ≤ 20, satisfying 0 ≤ x2 + x3 ≤ 20, y1 is an integer between 0 ≤ y1 ≤ 30, z1 is an integer between 0 ≤ z1 ≤ 10, y2 is an integer between 0 ≤ y2 ≤ 30, z2 is an integer between 0 ≤ z2 ≤ 10, and z1 + z2 > 0.

[0028] A monovalent organic group R bonded to a silicon atom other than the hydrogen atom bonded to the silicon atom. 4 The group is selected from alkyl groups having 1 to 8 carbon atoms, aryl groups having 6 to 12 carbon atoms, or aralkyl groups having 7 to 12 carbon atoms. Examples include monovalent hydrocarbon groups having 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms, that are unsubstituted or substituted and 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 aralkyl groups such as benzyl, phenylethyl, and phenylpropyl groups, with methyl being preferred. The number of silicon atoms in one molecule of component (B) ((x1+x2+x3+y1+y2+z1+z2) or degree of polymerization) is preferably 4 to 60, more preferably 4 to 50, and even more preferably 4 to 40.

[0029] The monovalent organic group Rf bonded to a silicon atom other than the hydrogen atom bonded to the silicon atom is selected from perfluoroalkyl groups having 1 to 10 carbon atoms and perfluoropolyether groups having 3 to 30 carbon atoms, and the groups shown for Rf in formula (1) above are examples. Preferably it is a perfluoroalkyl group, and more preferably a trifluoromethyl group.

[0030] X is a divalent organic group, and the group shown for X in formula (1) above is an example. Furthermore, as an Rf-X group, C k F 2k+1 A -CH2CH2 group (where k is an integer from 1 to 10) is preferred, and a 3,3,3-trifluoropropyl group (where k is 1) is more preferred.

[0031] x1 is a number between 2 and 4, x2 is an integer between 0 and 20, and x3 is an integer between 0 and 30, satisfying 0 between 0 and x2 + x3. y1 is an integer between 0 and 30, z1 is an integer between 0 and 30, y2 is an integer between 0 and 30, z2 is an integer between 0 and 30, and z1 + z2 > 0. However, x2, x3, y1, y2, z1, and z2 cannot all be zero at the same time. Since z1 + z2 > 0, the branched organohydrogen polysiloxane represented by equation (3) above contains one or more z1 or z2 units, which are T units.

[0032] (B) Specific examples of component (B) include the branched organohydrogenpolysiloxanes listed below, but are not limited to these. [ka]

[0033] Component (B) is preferably liquid at room temperature (25°C). The viscosity of component (B) 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. Workability is good when the viscosity is within this range.

[0034] The amount of component (B) is 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 the composition. In other words, the ratio of silicon-bonded hydrogen atoms (hydrosilyl groups) in component (B) to one silicon-bonded vinyl group (SiVi group) in the composition is 0.5 to 10, preferably 1 to 5. If the amount of component (B) is less than the lower limit, the resulting composition will not cure sufficiently. If the amount of component (B) exceeds the upper limit, the heat resistance of the resulting silicone rubber will be extremely poor. If the composition contains vinyl-containing silicon compounds such as vinyl-containing organosiloxanes other than component (A) described later, it is sufficient that the ratio of silicon-bonded hydrogen atoms of component (B) to the number of vinyl groups bonded to silicon atoms in the composition satisfies the above range. Note that component (B) may be used alone or in combination of two or more types. Furthermore, the branched organohydrogenpolysiloxane represented by formula (3) above may contain hydroxyl groups and / or alkoxy groups in its molecule. Specifically, it may contain hydroxyl groups and / or C1 to C6 alkoxy groups in an amount of 20 mol% or less of the total substituents of the organopolysiloxane. Specific examples of C1 to C6 alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, t-butoxy, pentyloxy, neopentyloxy, and hexyloxy groups, with methoxy, ethoxy, and isopropoxy groups being particularly noteworthy.

[0035] (C) Addition reaction catalyst The addition reaction catalyst for component (C) may be any catalyst that promotes the addition reaction between the vinyl group in the composition and the hydrogen atom bonded to the silicon atom in component (B). Platinum group metal catalysts are usually preferred. Examples include platinum, palladium, rhodium, chloroplatinic acid, alcohol-modified chloroplatinic acid, coordination compounds of chloroplatinic acid with olefins, vinylsiloxanes, or acetylene compounds, tetrakis(triphenylphosphine)palladium, chlorotris(triphenylphosphine)rhodium, and other platinum group metals or compounds thereof, but platinum-based compounds are particularly preferred. Component (C) may be used alone or in combination of two or more.

[0036] The amount of component (C) can be the effective amount (catalytic amount) as a catalyst, but relative to the amount of component (A), it is usually in the range of 0.5 to 1,000 ppm, preferably 1 to 500 ppm, and more preferably in the range of 10 to 100 ppm, on a mass basis when converted to catalytic metal elements (platinum group metal elements). When this range is satisfied, the reaction rate of the addition reaction becomes appropriate and the heat resistance of the cured product becomes good.

[0037] (D) Reinforcing silica filler Component (D) is a reinforced silica surface-treated with a linear organosilicon compound having silanol groups at both ends of the molecular chain, represented by the following formula (2). [ka] In equation (2) above, R 3 These are groups independently selected from alkyl groups having 1 to 8 carbon atoms, aryl groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms, for example, the above R 1 Examples are given for this purpose. Preferably, it is a methyl group. R 2 The above R 3 The group represented by , or the 3,3,3-trifluoropropyl group, however R 2 At least one of the groups is a 3,3,3-trifluoropropyl group. p is an integer between 1 and 20, preferably between 3 and 9.

[0038] In the present invention, the reinforcing silica filler is essential for imparting mechanical strength to the resulting silicone rubber. If the organosilicon compound represented by formula (2) does not have a 3,3,3-trifluoropropyl group, the resulting cured product will have inferior tensile strength, elongation at break, and compression set.

[0039] By including a reinforcing silica filler surface-treated with a linear organosilicon compound in which both ends of the molecular chain are sealed with silanol groups, the viscosity of this composition and the compression set of the rubber after heat curing can be reduced. As the reinforcing silica filler mentioned above, those conventionally used in silicone rubber compositions can be used, and precipitated silica (wet silica), fumed silica (dry silica), calcined silica, etc., are preferred. Fumed silica is particularly preferred.

[0040] Component (D) is silica that has been surface-treated in advance with the organosilicon compound of formula (2) above. Alternatively, the silica and polysiloxane (i.e., component (A)) may be kneaded together, the organosilicon compound of formula (2) above may be added, and the mixture may be heated and mixed in the presence of a small amount of water to perform surface treatment. Furthermore, the silica used in this invention refers to silica that has not been surface-treated with the organosilicon compound of formula (2) above, and may be dry silica that has been surface-treated with dimethyldichlorosilane or the like (for example, Aerosil R-974). It is preferable to further treat the surface of the dry silica that has been surface-treated with dimethyldichlorosilane or the like with the organosilicon compound of formula (2) above.

[0041] When surface-treating silica with the organosilicon compound of formula (2) above, it is preferable to use 1 to 30 parts by mass, particularly 2 to 20 parts by mass, of the organosilicon compound of formula (2) above for surface treatment with 40 parts by mass of silica before surface treatment with the organosilicon compound of formula (2).

[0042] In addition, organosilanes and organosilazanes other than the organosilicon compound of formula (2) above may be used in combination 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. 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 0.1 to 15 parts by mass, and more preferably 0.1 to 10 parts by mass, per 40 parts by mass of untreated silica.

[0043] The specific surface area of ​​silica before surface treatment with the organosilicon compound of formula (2) above, calculated by the BET method, is 50 m². 2 / g or more, preferably 100-400m 2 / g, more comfortably 150-350m 2 It is / g. The specific surface area is 50m². 2 A value of 400m or more provides sufficient strength and improves the appearance of the molded rubber product. 2 If the amount is less than / g, the formulation is easy. The specific surface area of ​​silica after surface treatment, calculated by the BET method, should also be within the above range.

[0044] The amount of component (D) is 10 to 60 parts by mass, preferably 15 to 55 parts by mass, per 100 parts by mass of component (A). If the amount is less than the lower limit, the resulting silicone rubber will not have sufficient rubber strength, and if it exceeds the upper limit, it will be difficult to incorporate into the composition.

[0045] Other ingredients The liquid addition-curable fluorosilicone composition of the present invention may optionally contain other components besides the components (A) to (D) described above. Examples of other components include conductive agents such as carbon black, conductive zinc oxide, and metal powders; hydrosilylation reaction control agents such as nitrogen-containing compounds, acetylene compounds such as ethynylcyclohexanol, 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 such as benzotriazolesilane; internal mold release agents such as dimethyl silicone oil; adhesion imparting agents; and thixotropic agents. However, the liquid addition-curable fluorosilicone composition of the present invention does not contain isocyanuric acid derivatives having three trialkoxy groups in one molecule.

[0046] The liquid addition-curing fluorosilicone composition of the present invention can be prepared by uniformly mixing the above components (A) to (D), and any optional components, using a conventional mixing and stirring device such as a kneader or planetary mixer, or a compounding device.

[0047] The composition of the present invention is characterized by being liquid at 23°C. Here, "liquid at 23°C" means that it has a constant volume at 23°C, but its shape changes according to the shape of the container (it has fluidity). From the viewpoint of workability, etc., at 23°C, with a shear rate of 10s -1 The viscosity at this shear rate is preferably 1,500 Pa·s or less, more preferably 100 to 1,200 Pa·s, and even more preferably 200 to 1,100 Pa·s. If this viscosity exceeds 1,500 Pa·s, material supply takes time during injection, compression, and injection molding, which can significantly reduce productivity. In this invention, the viscosity at the above shear rate was measured using a precision rotational viscometer (manufactured by Thermo Fisher Scientific).

[0048] The liquid addition-curing fluorosilicone composition of the present invention can also be a two-component type. In this case, the components can be appropriately divided so that component (B) as a crosslinking agent and component (C) as an addition reaction catalyst are not mixed in the same composition (liquid A or liquid B). For example, a two-component 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 it can be mixed in equal mass or volume.

[0049] The liquid addition-curing fluorosilicone composition of the present invention can be applied to various molding methods such as injection molding, compression molding, and injection molding. The molding methods for fluorosilicone rubber by injection molding, compression molding, or injection molding will be described in detail below.

[0050] In injection molding, the liquid addition-curing fluorosilicone composition is divided into two components, A and B. Equal amounts of each component are mixed, injected into a metal mold, heated in a constant-temperature bath to cure, and silicone rubber is formed. In compression molding, a metal mold is placed in a compressor such as a press, and equal amounts of A and B are mixed as in injection molding, injected into the mold, heated to cure, and silicone rubber is formed. In injection molding, each component A and B is supplied from a material supply pump to a metering device. From the metering device, A and B are combined in equal proportions through the material supply line. The materials are mixed in the screw and cylinder sections of the molding machine body. Then, they are injected into the mold, heated and cured inside the mold, and silicone rubber is formed.

[0051] The liquid addition-curing fluorosilicone composition of the present invention is particularly suitable for liquid silicone rubber injection molding systems (LIMS). An LIMS is a molding system that combines liquid silicone rubber with excellent properties and a molding machine that injects it precisely and stably. It can automate the entire process from mixing to molding, simplifying and shortening the process while facilitating the molding of high-quality products. In this molding method, the composition of the present invention has the following advantages: (i) It has a fast curing speed, which shortens the molding time and thus shortens the process; (ii) Because the material is liquid, it can be molded at low injection pressure and can handle the molding of precision parts, thus improving productivity; (iii) It supports burr-free and runner-less molding, and also has excellent release properties after curing, so the molding process can be automated; and (iv) There are no by-products from the curing reaction, and since burr-free and runner-less molding eliminates the need for waste material disposal, it enables environmentally friendly manufacturing.

[0052] The present invention provides a fluorosilicone rubber which is a cured product of the above-described addition-curing type fluorosilicone composition. Such a fluorosilicone rubber can maintain good mechanical strength. The curing of the composition may be carried out according to known techniques, and the curing method and conditions are not particularly limited.

[0053] The curing and molding (primary curing) conditions for liquid addition-curing type fluorosilicone compositions may be the same as those for known addition-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. The molded cured product may be post-cured (secondary cured) as needed, for example, at 180 to 220°C for 30 minutes to 6 hours.

[0054] The cured product (silicone rubber) obtained from the liquid addition-curing type fluorosilicone composition of this invention has a compression set of 10% or less after compression at 180°C for 22 hours, as measured according to JIS K 6249:2003, and a tensile strength of 5.0 MPa or more. Alternatively, the compression set after compression at 180°C for 22 hours at a compressibility of 25% according to JIS K 6249:2003 should be 15% or less, preferably 10% or less. When the compression set is 10% or less, the cured product can be used as a sealant, O-ring, or gasket, or other component (molded body). From the viewpoint of the practical strength of a rubber molded product, the tensile strength should be 4.5 MPa or more, preferably 5.0 MPa or more.

[0055] Furthermore, the present invention provides a fluorosilicone rubber molded article characterized by being a molded article of the above-mentioned fluorosilicone rubber.

[0056] The fluorosilicone rubber molded articles obtained by heat curing the liquid addition-curing type fluorosilicone composition of the present invention have excellent gasoline resistance and oil resistance, and can therefore be suitably used in aircraft and automotive rubber parts, printer parts, and more recently, in mobile device parts due to their sebum resistance and in sealing parts for fuel cell vehicles due to their acid resistance. [Examples]

[0057] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The viscosity of component (A) was measured at 25°C using a BH-type rotational viscometer (rotor No. 7, rotation speed 10 rpm).

[0058] The curability of the composition was measured using a curability tester [rotorless type disk rheometer, moving die type rheometer, or MDR] at 130°C for 3 minutes, with the 10% and 90% curing times (i.e., the time from the start of measurement to when 10% and 90% of the maximum torque value at 130°C for 3 minutes) defined as T10 and T90 (seconds).

[0059] The hardness, tensile strength, elongation at break, and tear strength (angle) of the cured material were measured using the following method. The composition was press-cured at 150°C for 10 minutes and then subjected to secondary vulcanization (post-curing) in a constant temperature bath at 200°C for 4 hours. The hardness (Type A durometer hardness), tensile strength, elongation at break, and tear strength (angle) of the resulting cured product were measured according to the description in JIS K 6249:2003.

[0060] The compression set of the cured material was measured using the following method. The composition was cured at 150°C for 15 minutes (press curing), and then subjected to secondary vulcanization (post-curing) in a constant temperature bath at 200°C for 4 hours. The resulting cured product was subjected to compression set after compression at 180°C for 22 hours at a compressibility of 25%, according to the description in JIS K 6249:2003.

[0061] The components used in the following examples and comparative examples are as follows: (A) Component: See formula (4) below [ka] Trifluoropropylmethylpolysiloxane [vinyl group content: 4.6 × 10], with both ends sealed with dimethylvinylsiloxy groups, and a viscosity of 76.6 Pa·s at 25°C. -5 mol / g]

[0062] (D) Component: Specific surface area of ​​200 m² as determined by the BET method. 2 Humed silica (manufactured by Nippon Aerosil Co., Ltd., Aerosil R-974) is / g, The organosilicon compound represented by the following formula (5) [ka]

[0063] (B) Crosslinking agent: (B-1) Methylhydrogenpolysiloxane represented by the following formula (6-1) [SiH group content: 0.0086 mol / g] [ka] (B-2) Methylhydrogenpolysiloxane represented by the following formula (6-2) [SiH group content: 0.0020 mol / g] [ka] (B-3) Methylhydrogenpolysiloxane represented by the following formula (6-3) [SiH group content: 0.0016 mol / g] [ka] (B-4) Methylhydrogenpolysiloxane represented by the following formula (6-4) [Viscosity: 0.06 Pa·s, SiH group content: 0.0049 mol / g] [ka]

[0064] (C) Platinum catalyst (Pt concentration: 0.5% by mass)

[0065] (Other ingredients) Reaction control agent: Ethinylcyclohexanol Compression set improver: Benzotriazolesilane represented by the following formula (7) [ka] Heat resistance modifier: Cerium oxide

[0066] [Preparation Example 1] (A) Trifluoropropylmethylpolysiloxane represented by formula (4) above [vinyl group content 4.6 × 10 -555 parts by mass of [mol / g], 40 parts by mass of the above-mentioned fumed silica as a reinforcing silica filler, 6 parts by mass of the organosilicon compound represented by formula (5), 0.5 parts by mass of water, and 0.4 parts by mass of 1,3-divinyl-1,1,3,3-tetramethyldisilazane were mixed at 25°C for 30 minutes, then the temperature was raised to 160°C and stirring was continued for 3 hours. Further, 60 parts by mass of trifluoropropylmethylpolysiloxane represented by formula (4) were added and mixed for 30 minutes to obtain silicone rubber base A1. In the obtained silicone rubber base, the amount of component (D) per 100 parts by mass of component (A) was 35 parts by mass.

[0067] [Examples 1-4, Comparative Examples 1,2] Silicone rubber compositions were prepared using the formulations shown in Table 1 below. The viscosity of the obtained compositions was measured under the above conditions, and cured products were prepared to measure the general physical properties described above. These results are shown in Table 1. In the table, the "Curability T10 / T90" column shows the 10% and 90% curing times (seconds) obtained by the above measurement method, respectively, and the "Curability T90-T10" column shows the difference between them. A smaller difference indicates faster curing. Also, "SiH / SiVi" is the number ratio of SiH groups in component (B) to SiVi groups in the composition.

[0068] [Table 1]

[0069] As shown in Table 1 above, the cured products obtained from the liquid addition-curing type fluorosilicone composition of the present invention exhibit good curability (fast curing), excellent tensile strength, and elongation at break. On the other hand, the fluorosilicone compositions of Comparative Examples 1 and 2, which used linear silicone (B-4) with side chains modified by hydrogen using the organosilicon compound of the present invention, exhibited poor curability (somewhat slow curing) and also poor mechanical strength.

[0070] The liquid addition-curing fluorosilicone composition of the present invention is suitable as a material for injection molding, compression molding, and injection molding, and can contribute to improving the productivity of molded products. Furthermore, the liquid addition-curing fluorosilicone composition of the present invention has a low compression set value after heat curing, and can be suitably used as a rubber molded product such as a sealant, O-ring, or gasket.

[0071] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. An addition-curing fluorosilicone composition, (A) General formula (1) 【Chemistry 1】 (In the formula, R １ (Each group is independently selected from alkyl groups having 1 to 8 carbon atoms, aryl groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms; Rf is independently selected from perfluoroalkyl groups having 1 to 10 carbon atoms and perfluoropolyether groups having 3 to 30 carbon atoms; X is a divalent organic group; m is an integer from 0 to 100; and n is an integer from 1 to 800, where 5 ≤ m + n ≤ 800.) A vinyl group-containing organopolysiloxane having a viscosity of 100 to 500,000 mPa·s at 25°C, as shown by [formula]. (B) The following formula (3) has three or more silicon-bonded hydrogen atoms in one molecule 【Chemistry 2】 (In the above formula (3), R ４ Rf is a group independently selected from an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms. Rf is a group independently selected from a perfluoroalkyl group having 1 to 10 carbon atoms and a perfluoropolyether group having 3 to 30 carbon atoms. X is a divalent organic group. x1 is a number 2 ≤ x1 ≤ 4, x2 is an integer 0 ≤ x2 ≤ 20, x3 is an integer 0 ≤ x3 ≤ 20 satisfying 0 ≤ x2 + x3 ≤ 20, y1 is an integer 0 ≤ y1 ≤ 30, z1 is an integer 0 ≤ z1 ≤ 10, y2 is an integer 0 ≤ y2 ≤ 30, z2 is an integer 0 ≤ z2 ≤ 10, and z1 + z2 > 0. Branched organohydrogenpolysiloxane represented by: (B) an amount such that the number of hydrogen atoms bonded to the silicon atom in component (B) is 0.5 to 10 per silicon atom bonded vinyl group in the composition, (C) Addition reaction catalyst: amount of catalyst, and (D) A reinforcing silica filler in which 40 parts by mass of silica before surface treatment is surface-treated with 1 to 6 parts by mass of the organosilicon compound of the following formula (2), and is surface-treated with 0.1 to 15 parts by mass of one or more surface treatment agents selected from trimethylchlorosilane, dimethyldichlorosilane, dimethylvinylchlorosilane, trivinylchlorosilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, trimethylmethoxysilane, triethylmethoxysilane, vinyltris(methoxyethoxy)silane, hexamethyldisilazane, hexamethylcyclotrisilazane, and 1,3-divinyl-1,1,3,3-tetramethyldisilazane. 【Transformation 3】 (In the above formula (2), R ３ These are groups independently selected from alkyl groups having 1 to 8 carbon atoms, aryl groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms, R ２ These are independent of each other, the above R ３ The group represented by , or the 3,3,3-trifluoropropyl group, however R ２ At least one of the groups is a 3,3,3-trifluoropropyl group, and p is an integer of 1 ≤ p ≤ 20. (A) 10 to 60 parts by mass per 100 parts by mass of component It contains, The addition-curing fluorosilicone composition is characterized in that it is liquid at 23°C.

2. A fluorosilicone rubber characterized by being a cured product of the addition-curing type fluorosilicone composition described in claim 1.

3. A fluorosilicone rubber molded article characterized by being a molded article of fluorosilicone rubber as described in claim 2.

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