Polypropylene resin and silicone rubber bonded material and manufacturing method thereof

Abstract

To provide a joined article in which a polypropylene resin and an addition curable type silicone rubber are strongly joined to each other, and a production method of the same.SOLUTION: There is provided a joined article in which a polypropylene resin subjected to dry treatment and an addition curable type silicone rubber are joined to each other by a primer composition, wherein the primer composition contains (A) a silane compound in which a 3-aminopropyl group is bonded to a silicon atom, (B) a silane compound having one or more epoxy group-containing organic groups in one molecule, and (C) a platinum group metal catalyst, and a molar ratio of a nitrogen atom contained in the component (A) to a platinum atom contained in the component (C) is 50:1 to 1:1.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a bonded material of polypropylene resin and silicone rubber and a method for producing the same. [Background technology]

[0002] Silicone rubber is used in many fields due to its excellent heat resistance, cold resistance, weather resistance, electrical insulation, safety, etc., and is often used as a part combined with organic resins, metals, etc. In addition, polypropylene resin, a type of polyolefin resin, is the second most produced synthetic resin after polyethylene resin, has a low specific gravity, and has excellent mechanical strength, processability, and scratch resistance. However, polypropylene resin is known as a difficult-to-adhere material, and a method for developing strong adhesion between polypropylene resin and silicone rubber that will reliably cause cohesive failure has yet to be found.

[0003] As an example of the adhesion between polypropylene resin and silicone rubber, Japanese Patent Laid-Open No. 60-084335 (Patent Document 1) describes providing a silane coupling agent layer containing aminosilane and vinylsilane on vulcanized silicone rubber, and then simultaneously heating and vulcanizing a silicone / polyolefin copolymer and a thermoplastic resin on top of the layer; however, this method makes it difficult to mold silicone rubber onto polypropylene resin.

[0004] Furthermore, polypropylene resins generally contain additives such as antioxidants, UV absorbers, lubricants, plasticizers, surfactants, etc. Among these additives, organic compounds containing nitrogen, sulfur, phosphorus, etc., and ionic compounds of heavy metals can also cause curing inhibition in addition-cured silicone rubbers that use platinum group metal catalysts. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 60-084335 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to provide a bonded article in which polypropylene resin and addition-curing silicone rubber are firmly bonded together, and a method for producing a bonded article in which polypropylene resin and addition-curing silicone rubber can be firmly bonded together even during a hot molding process in a mold, such as compression molding, press molding, or injection molding. [Means for solving the problem]

[0007] As a result of intensive research conducted by the inventors in order to achieve the above-mentioned object, they discovered that by applying a primer composition containing as essential components a silane compound in which a γ-aminopropyl group is bonded to a silicon atom, a silane compound containing an epoxy group, and a platinum group metal compound to a polypropylene resin substrate that has been subjected to plasma treatment or silicon oxide film treatment, and then heat-curing a silicone rubber composition thereon, strong adhesion can be obtained between the polypropylene resin and the silicone rubber even within a mold, thereby completing the present invention.

[0008] Accordingly, the present invention provides the following bonded article of polypropylene resin and silicone rubber and a method for producing the same.

[0009] <1> A bonded article in which a dry-processed polypropylene resin and an addition-curing silicone rubber are bonded with a primer composition, the primer composition comprising: (A) a silane compound having a 3-aminopropyl group bonded to a silicon atom; (B) a silane compound having one or more epoxy group-containing organic groups in one molecule, and (C) Platinum group metal catalyst wherein the molar ratio of nitrogen atoms contained in component (A) to platinum atoms contained in component (C) is 50:1 to 1:1. <2> The component (A) is at least one selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, and 3-aminopropylmethyldiethoxysilane. <1> The joint material according to claim 1. <3> A first step of performing a dry treatment on a surface of a polypropylene resin substrate; a second step of applying a primer composition to the surface of the substrate dry-treated in the first step and drying the composition to form a primer layer; and a third step of applying a silicone rubber composition to the surface of the primer layer and heat curing the composition to form an addition-cured silicone rubber layer, The primer composition comprises: (A) a silane compound having a 3-aminopropyl group bonded to a silicon atom; (B) a silane compound having one or more epoxy group-containing organic groups in one molecule, and (C) Platinum group metal catalyst wherein the molar ratio of nitrogen atoms contained in component (A) to platinum atoms contained in component (C) is 50:1 to 1:1. <4> The dry treatment is a plasma treatment or a silicon oxide film treatment. <3> A method for producing the bonded article according to claim 1. <5> The amount of the primer layer formed by applying and drying the primer composition after drying is 0.05 to 5 g / m 2 characterized in that <3> or <4> A method for producing the bonded article according to claim 1. <6> The silicone rubber composition contains the following components (D) to (I): <3> ~ <5> 13. A method for producing the bonded article according to any one of claims 1 to 12. (D) Organopolysiloxane having a degree of polymerization of 100 to 10,000 and having two or more alkenyl groups bonded to silicon atoms in one molecule: 100 parts by mass (E) The specific surface area measured by the BET method is 50 to 500 m 2 / g: 10 to 100 parts by mass per 100 parts by mass of component (D). (F) Organohydrogenpolysiloxane having two or more hydrosilyl groups per molecule: an amount such that the amount of hydrosilyl groups in component (F) is 0.5 to 5 moles per mole of alkenyl groups in component (D). (G) Platinum group metal catalyst: 0.5 to 1,000 ppm by weight of platinum group metal relative to the weight of component (D) <7> In the third step of applying a silicone rubber composition to the surface of the primer layer and heat-curing the composition to form a silicone rubber layer, the silicone rubber composition is heat-molded by any method selected from compression molding, press molding, and injection molding. <3> ~ <6> 13. A method for producing the bonded article according to any one of claims 1 to 12. Effect of the Invention

[0010] By using the manufacturing method of the present invention, a bonded product in which dry-processed polypropylene resin and addition-curing silicone rubber are firmly bonded can be stably obtained even in a hot molding process in a mold such as compression molding, press molding, injection molding, etc. Polypropylene resin is used for various purposes such as home appliances, stationery, automobile parts, toys, sporting goods, tableware, etc., and if silicone rubber of different hardness and color can be firmly bonded to it, it is useful for adjusting the texture (anti-slip, etc.) and imparting design properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will now be described in more detail.

[0012] The present invention relates to a bonded article in which a dry-processed polypropylene resin and an addition-curing silicone rubber are bonded together with the following primer composition. (A) a silane compound having a 3-aminopropyl group bonded to a silicon atom; (B) a silane compound having one or more epoxy group-containing organic groups in one molecule, and (C) Platinum group metal catalyst wherein the molar ratio of nitrogen atoms contained in component (A) to platinum atoms contained in component (C) is 50:1 to 1:1. The method for producing a bonded article of the present invention further comprises the steps of: A first step of performing a dry treatment on a surface of a polypropylene resin substrate; a second step of applying a primer composition to the surface of the substrate dry-treated in the first step and drying the composition to form a primer layer; and a third step of applying a silicone rubber composition to the surface of the primer layer and curing the composition by heating to form an addition-cured silicone rubber layer. The primer composition comprises: (A) a silane compound having a 3-aminopropyl group bonded to a silicon atom; (B) a silane compound having one or more epoxy group-containing organic groups in one molecule, and (C) Platinum group metal catalyst wherein the molar ratio of nitrogen atoms contained in component (A) to platinum atoms contained in component (C) is 50:1 to 1:1.

[0013] Polypropylene Resin The polypropylene resin substrate used in the present invention is not particularly limited, and polypropylene resins with various melting points and molecular weights can be used. Generally, polypropylene resins are classified into three types according to the form of copolymerization: homopolymers, which are single polymers of propylene only; random copolymers containing ethylene at a ratio of 4.5% by weight or less; and block copolymers containing ethylene-propylene copolymers in which ethylene is copolymerized after polymerization of homopolymers, and any of these can be used.

[0014] Addition cure silicone rubber The addition-curing silicone rubber used in the present invention contains an alkenyl-containing organopolysiloxane, reinforcing silica, an organohydrogenpolysiloxane, and a platinum group metal catalyst. Either millable rubber that can be plasticized and mixed in a kneading roll or internal mixer, or liquid rubber that is in a liquid or paste state before curing can be used.

[0015] [Method of manufacturing the bonded article of the present invention] The first step is to dry treat the surface of the polypropylene resin substrate. Dry Processing In the present invention, a dry treatment of the polypropylene resin surface before forming a primer layer is an essential step. In general, examples of dry treatments include plasma treatment, corona treatment, flame treatment, silicon oxide film treatment (Itro treatment), UV treatment, and excimer treatment. When the dry treatment is performed, hydrophilicity is expressed, for example, by generating a hydrophilic group having an oxygen atom. This can improve the reactivity between the propylene resin and the primer composition. In the present invention, among these dry treatments, plasma treatment or silicon oxide film treatment is particularly preferred because strong adhesion can be stably obtained.

[0016] The plasma treatment used in the present invention is a method of treating the surface of a substrate under reduced pressure using argon or oxygen plasma, and it is possible to adjust the plasma output, gas flow rate, degree of vacuum, treatment time, etc. The treatment conditions can be adjusted based on the wettability and spreading property of the primer composition, and the contact angle of liquid such as water.

[0017] The silicon oxide film treatment used in the present invention is also called ITORO treatment, and is a method of introducing a silane compound or the like into a fuel gas for forming a flame and using the flame to treat the surface of a substrate. After the treatment, a large number of fine particles mainly composed of silicon dioxide are formed on the surface of the substrate, improving the reactivity with the primer composition. The degree of treatment of the surface treatment can be adjusted by the size and shape of the flame, the distance between the burner and the substrate, the moving speed of the burner, the treatment time, etc. The treatment conditions can be adjusted based on the wettability and spreading of the primer composition, and the contact angle of liquids such as water. In addition, the effective procedure of this silicon oxide film treatment is described in detail in JP-A-2003-238710.

[0018] The second step is to form a primer layer on the surface of the substrate that has been dry-treated in the first step. The primer composition used in the present invention for forming a primer layer on the substrate surface dry-treated in the first step is (A) a silane compound having a 3-aminopropyl group bonded to a silicon atom; (B) a silane compound having one or more epoxy group-containing organic groups in one molecule, and (C) Platinum group metal catalyst The composition contains the above, and the molar ratio of nitrogen atoms contained in component (A) to platinum atoms contained in component (C) is 50:1 to 1:1. Each component is described in detail below.

[0019] (A) Silane compound with a 3-aminopropyl group bonded to a silicon atom The silane compound in which a 3-aminopropyl group is bonded to a silicon atom of component (A) is a compound having one or more 3-aminopropyl groups bonded to a silicon atom in each molecule, preferably one or two, and more preferably one. Furthermore, groups bonded to silicon atoms other than the 3-aminopropyl group include groups selected from alkyl groups having 1 to 10 carbon atoms and alkoxy groups having 1 to 6 carbon atoms, and those having one or more alkoxy groups per molecule are preferred. Specific examples of the silane compound of component (A) include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, di(3-aminopropyl)dimethoxysilane, and di(3-aminopropyl)diethoxysilane. The component (A) can be used alone or in appropriate combination of two or more. Known aminosilanes include silane compounds in which an N-2-(aminoethyl)-3-aminopropyl group, an N-(1,3-dimethyl-butylidene)propylamino group, or an N-phenyl-3-aminopropyl group is bonded to a silicon atom, but none of these compounds provide strong adhesion.

[0020] (B) Silane compound having an epoxy group-containing organic group As the silane compound having an epoxy group-containing organic group of component (B), a known compound can be used. The silane compound has one or more epoxy group-containing organic groups bonded to silicon atoms in one molecule, preferably one or two, more preferably one. Furthermore, groups bonded to silicon atoms other than the epoxy group-containing organic group include groups selected from alkyl groups having 1 to 10 carbon atoms and alkoxy groups having 1 to 6 carbon atoms, and those having one or more alkoxy groups per molecule are preferred. Specific examples of the silane compound of component (B) that are easily available and have high reactivity include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The component (B) can be used alone or in appropriate combination of two or more.

[0021] (C) Platinum group metal catalyst Suitable examples of the platinum group metal catalyst for component (C) include Karstedt catalysts, such as the platinum(0)-1,3-divinyltetramethyldisiloxane complex, which is widely used as a catalyst for addition-curing silicone rubber, and chloroplatinic acids such as hexachloroplatinic acid (IV) acid and tetrachloroplatinic acid (II) acid. Other examples that can be used include platinum black, reaction products of chloroplatinic acid with monohydric alcohols, complexes of chloroplatinic acid with olefins, platinum bisacetoacetate, palladium-based catalysts, and rhodium-based catalysts.

[0022] The mixing ratio of components (A) and (B) in the primer composition is preferably such that the molar ratio of amino groups to epoxy groups is 2:8 to 8:2, more preferably 3:7 to 7:3, and even more preferably 4:6 to 6:4.

[0023] Furthermore, the molar ratio (nitrogen:platinum) of the nitrogen atoms contained in component (A) to the platinum atoms contained in component (C) in the primer composition is preferably 50:1 to 1:1, more preferably 35:1 to 1:1, and even more preferably 20:1 to 1:1. If the molar ratio (nitrogen:platinum) exceeds 50, sufficient adhesion cannot be obtained, and if it is below 1, the adhesive performance is maintained but the cost burden increases.

[0024] The (A), (B) and (C) components can be used by diluting with a solvent. The solvent is not limited as long as it dissolves the (A), (B) and (C) components and other optional components, and known solvents can be used. The solvent may be used alone or in combination of two or more depending on the evaporation rate during application and drying of the primer composition. Specific examples of the solvent include aromatic hydrocarbons such as xylene, toluene and benzene; aliphatic hydrocarbons such as heptane and hexane, aromatic / aliphatic mixed hydrocarbons such as ligroin and rubber volatile oil; chlorinated hydrocarbons such as trichloroethylene, perchloroethylene and methylene chloride; esters such as ethyl acetate; ketones such as methyl isobutyl ketone, methyl ethyl ketone and cyclohexanone; aliphatic alcohols such as ethanol, isopropanol and butanol; ethers such as diethyl ether; and silicone-based solvents. Among them, aliphatic alcohols are preferred, and aliphatic alcohols having 1 to 6 carbon atoms, which are easy to dry, are particularly preferred. The reason for this is that in the primer composition, the amino group and the epoxy group in the silane compound react to open the epoxy group and generate a hydroxyl group, but in the aliphatic alcohol, the reaction between this hydroxyl group and the silicon atom in the silane compound is suppressed, thereby improving the storage stability of the primer solution.

[0025] The amount of the solvent is preferably such that the total amount of components (A), (B), (C) and other optional components in the primer composition is 0.1 to 20 mass %, and more preferably 0.5 to 10 mass %.

[0026] The method of applying the primer composition includes brush application and spraying. The amount of application is adjusted by the application method, the number of applications, the concentration of the primer composition, etc., and can be estimated from the change in weight after drying. The amount of the primer composition after drying is 0.05 to 5 g / m 2 The amount is preferably 0.1 to 3 g / m 2 The amount of coating is preferably 0.05 g / m 2 If it is less than 5g / m, sufficient adhesive strength may not be obtained. 2If it exceeds this value, the primer layer may be easily damaged by external stress.

[0027] The primer composition may be dried and cured by leaving it at room temperature or by placing it in an incubator or thermo-hygrostat. In consideration of the heat resistance of polypropylene resin, the incubator is preferably set at a temperature of 160° C. or less, more preferably 130° C. or less.

[0028] Although the number of steps is increased, the (A) and (B) components may be coated and dried, and then the (C) component may be coated and dried thereon. In this case, the molar ratio of amino groups to epoxy groups between the (A) and (B) components is preferably 2:8 to 8:2, more preferably 3:7 to 7:3, and even more preferably 4:6 to 6:4. The molar ratio (nitrogen:platinum) of nitrogen atoms contained in the (A) component to platinum atoms contained in the (C) component is preferably 50:1 to 1:1, more preferably 35:1 to 1:1, and even more preferably 20:1 to 1:1.

[0029] The third step is to form an addition-curing silicone rubber layer on the surface of the primer layer. The silicone rubber composition used in the present invention for forming a silicone rubber layer on the surface of the primer layer is not particularly limited, but a preferred example is one containing the following components (D) to (G). (D) Organopolysiloxane having a degree of polymerization of 100 to 10,000 and having two or more alkenyl groups bonded to silicon atoms in one molecule: 100 parts by mass (E) The specific surface area measured by the BET method is 50 to 500 m 2 / g: 10 to 100 parts by mass per 100 parts by mass of component (D). (F) Organohydrogenpolysiloxane having two or more hydrosilyl groups per molecule: an amount such that the amount of hydrosilyl groups in component (F) is 0.5 to 5 moles per mole of alkenyl groups in component (D). (G) Platinum group metal catalyst: 0.5 to 1,000 ppm by weight of platinum metal relative to the weight of component (D). Each component will be described in detail below.

[0030] (D) Alkenyl-containing organopolysiloxane The (D) component preferably used in the above addition curing silicone rubber composition is an organopolysiloxane having a degree of polymerization (or the number of silicon atoms in the molecule) of 100 to 10,000 and having two or more alkenyl groups bonded to silicon atoms in one molecule. This (D) component is used as the main component (base polymer) of this composition. The (D) component alkenyl group-containing organopolysiloxane is preferably a raw rubber-like component (i.e., a non-liquid component with high viscosity and no self-flowability) at room temperature (25°C). The addition curing silicone rubber composition containing this alkenyl group-containing organopolysiloxane as the main component is usually a millable type composition (i.e., a raw rubber-like composition that can be uniformly kneaded under shear stress by a kneader such as a roll mill). The (D) component alkenyl group-containing organopolysiloxane is, for example, typically represented by the following average composition formula (I). [ka] (In formula (I), R represents the same or different monovalent hydrocarbon groups having 1 to 12 carbon atoms, and a is a number from 1.95 to 2.05.)

[0031] In the above average composition formula (I), R represents the same or different monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, specifically, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, etc.; cycloalkyl groups such as cyclopentyl group, cyclohexyl group, etc.; fluoroalkyl groups such as 3,3,3-trifluoropropyl group, etc.; alkenyl groups such as vinyl group, allyl group, propenyl group, etc.; aryl groups such as cycloalkenyl group, phenyl group, tolyl group, etc.; aralkyl groups such as benzyl group, 2-phenylethyl group, etc., and methyl group, vinyl group, phenyl group, trifluoropropyl group, etc. are preferred, and methyl group, vinyl group are particularly preferred. Methyl group is preferably 80% or more, particularly 90% or more of R, and more preferably all R groups except alkenyl group are methyl group.

[0032] Specifically, the alkenyl-containing organopolysiloxane of component (D) is preferably an organopolysiloxane whose main chain is composed of dimethylsiloxane units, or a dimethylpolysiloxane whose main chain has, in part, a diphenylsiloxane unit having a phenyl group, a vinyl group, or a 3,3,3-trifluoropropyl group, such as a methylvinylsiloxane unit, or a methyl-3,3,3-trifluoropropylsiloxane unit, etc. introduced therein.

[0033] The organopolysiloxane of component (D) must have two or more (usually 2 to 50, particularly 2 to 20) alkenyl groups, preferably vinyl groups, per molecule. For example, it is preferred that 0.01 to 10%, particularly 0.02 to 5%, of all R groups in the average composition formula (I) above be alkenyl groups. The alkenyl group may be bonded to a silicon atom at the molecular chain terminal, or may be bonded to a silicon atom in the middle of the molecular chain (non-terminal), or may be both, but it is preferable that the alkenyl group contains at least an alkenyl group bonded to a silicon atom at both molecular chain terminals.Specifically, it is preferable that the molecular chain terminals are blocked with a dimethylvinylsilyl group, a methyldivinylsilyl group, a trivinylsilyl group, or the like.

[0034] In the above average composition formula (I), a is a number from 1.95 to 2.05, preferably from 1.98 to 2.02, and more preferably from 1.99 to 2.01. The molecular structure of the alkenyl-containing organopolysiloxane of component (D) is basically such that the main chain is made up of diorganosiloxane units (R 2 SiO 2 / 2 ) repeating units, and both ends of the molecular chain are triorganosiloxy groups (R 3 SiO 1 / 2 Generally, the main chain has a linear structure blocked with branch units (RSiO 3 / 2 ) may be contained in a branched structure (R is the same as above).

[0035] The degree of polymerization of the organopolysiloxane of component (D) is from 100 to 10,000, preferably from 1,000 to 10,000, more preferably from 2,000 to 10,000, still more preferably from 3,000 to 8,000, and particularly preferably from 5,000 to 8,000. If the degree of polymerization is less than 100, sufficient rubber strength may not be obtained. In this specification, the degree of polymerization is a value calculated as the weight-average degree of polymerization from the weight-average molecular weight converted into polystyrene in gel permeation chromatography (GPC) analysis measured under the following conditions.

[0036] [GPC measurement conditions] Developing solvent: toluene Flow rate: 0.6mL / min Detector: Refractive index detector (RI) Column: TSK Guardcolumn SuperH-H TSKgel SuperH5000(6.0mmI.D.×15cm×1) TSKgel SuperH4000(6.0mmI.D.×15cm×1) TSKgel SuperH3000(6.0mmI.D.×15cm×1) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 50 μL (toluene solution with a concentration of 0.5% by mass)

[0037] The alkenyl-containing organopolysiloxane of component (D) may use either a single type, or a combination of two or more types having different molecular structures or degrees of polymerization.

[0038] The alkenyl group-containing organopolysiloxane of component (D) can be obtained by known methods, such as (co)hydrolyzing and condensing one or more organohalogenosilanes, or by ring-opening polymerization of a cyclic polysiloxane using an alkaline or acidic catalyst.

[0039] (E) Reinforcing Silica The reinforcing silica of component (E) that is preferably used in the above-mentioned addition curing silicone rubber composition can be a reinforcing silica fine powder that is usually used in silicone rubber compositions. Examples of the reinforcing silica of component (E) include fumed silica, dry silica such as calcined silica, and wet silica such as precipitated silica, and among these, fumed silica is preferred from the viewpoint of heat resistance. The specific surface area measured by the BET method is 50 to 500 m 2 / g, preferably 100 to 400m 2 / g, more preferably 100 to 300m 2 / g. The specific surface area is 50m 2 If it is less than 500m / g, the mechanical strength may be insufficient. 2 / g or more may make industrial production difficult.

[0040] If necessary, the surface of this reinforcing silica may be subjected to a hydrophobic treatment with a known treating agent such as chlorosilane or hexamethyldisilazane.

[0041] The amount of reinforcing silica (E) added to the addition curable silicone rubber composition is 10 to 100 parts by mass, preferably 20 to 70 parts by mass, and more preferably 30 to 60 parts by mass, per 100 parts by mass of the alkenyl-containing organopolysiloxane (D). If the amount is less than 10 parts by mass, the amount is too small to obtain a sufficient reinforcing effect, whereas if the amount exceeds 100 parts by mass, the processability may deteriorate and the mechanical strength may decrease.

[0042] (F) Organohydrogenpolysiloxane Component (F) that is preferably used in the above addition-curable silicone rubber composition is an organohydrogenpolysiloxane having at least two, and preferably three or more, hydrogen atoms (hydrosilyl groups) bonded to silicon atoms in each molecule, and is preferably an organohydrogenpolysiloxane that is liquid at room temperature and is represented by the following average composition formula (II): [ka] (In formula (II), R 2 are each independently the same or different monovalent hydrocarbon groups having 1 to 10 carbon atoms; b is a number that satisfies 0.7 to 2.1, c is a number that satisfies 0.001 to 1, and b+c is a number that satisfies 0.8 to 3.

[0043] In formula (II), R 2 are each independently the same or different monovalent hydrocarbon group having 1 to 10 carbon atoms, and specific examples thereof include alkyl groups such as a methyl group, an ethyl group, and a propyl group.

[0044] In addition, in formula (II), b is a number that satisfies 0.7 to 2.1, preferably 0.8 to 2, c is a number that satisfies 0.001 to 1, preferably 0.01 to 1, and b+c is a number that satisfies 0.8 to 3, preferably 0.9 to 2.7.

[0045] The organohydrogenpolysiloxane of component (F) has at least two hydrosilyl groups (2 to 300), preferably three or more (e.g., 3 to 200), and more preferably four or more (e.g., 4 to 100) in one molecule, and these may be at the molecular chain terminals, in the middle of the molecular chain (non-terminal), or both. The organohydrogenpolysiloxane may have a silicon atom number (or degree of polymerization) of usually 2 to 300, preferably 3 to 200, and more preferably 4 to 100 in one molecule, and preferably has a viscosity at 25°C of 0.5 to 1,000 mPa·s, more preferably 1 to 500 mPa·s, and particularly preferably 5 to 300 mPa·s. The viscosity refers to a value measured at 25°C using a rotational viscometer described in JIS K 7117-1:1999.

[0046] The amount of the organohydrogenpolysiloxane blended is preferably 0.1 to 30 parts by mass, and more preferably 0.3 to 10 parts by mass, per 100 parts by mass of the organopolysiloxane of the component (D). This organohydrogenpolysiloxane can also be blended so that the molar ratio of hydrosilyl groups to the total alkenyl groups in component (D) is in the range of 0.5 to 5, preferably 0.8 to 3, and more preferably 1 to 2.5. When using an organohydrogenpolysiloxane, if the blending amount of the organohydrogenpolysiloxane is too small, crosslinking may be insufficient, resulting in poor rubber properties such as strength and elongation, while if the blending amount is too large, there may be too many crosslinking points (too high crosslinking density), which may also result in poor rubber properties.

[0047] (G)Platinum group metal catalyst Component (G), which is preferably used in the above addition-curable silicone rubber composition, is defined similarly to component (C).

[0048] The amount of component (G) added can be a catalytic amount, which is usually 0.5 to 1,000 ppm, calculated as platinum metal mass, relative to component (D), and preferably 1 to 500 ppm.

[0049] The above-mentioned addition-curable silicone rubber composition is applied to the surface of the primer layer and cured by heating to form an addition-curable silicone rubber layer (third step). The curing conditions for the addition curing silicone rubber composition are preferably 100 to 180°C for 10 seconds to 30 minutes, more preferably 120 to 160°C for 20 seconds to 20 minutes. After the addition curing silicone rubber composition is molded onto the primer layer (i.e., after the first curing), it is preferable to perform a post-cure (secondary curing) for the purpose of improving adhesion and compression set of the cured product. The post-cure conditions are preferably 100 to 180°C for 30 minutes to 100 hours, more preferably 120 to 160°C for 1 to 8 hours, taking into consideration the heat resistance temperature and melting point of the polypropylene resin.

[0050] The addition-curing silicone rubber composition may be molded by any method, including compression molding (press molding), pressure molding, injection molding, and extrusion molding. However, the present invention exhibits excellent adhesive performance particularly in molding within a mold, such as compression molding, pressure molding, and injection molding. EXAMPLES

[0051] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0052] [Solution P1 (silane)] 3-Aminopropyltriethoxysilane (KBE-903, Shin-Etsu Chemical Co., Ltd.) and 3-glycidoxypropyltrimethoxysilane (KBM-403, Shin-Etsu Chemical Co., Ltd.) were each added at 5 mass% in isopropyl alcohol (nitrogen atom content: 0.32 mass%). After the preparation, the mixture was stirred for 1 hour with a shaker, and the following day or later, mixed with Solution P2 or Solution P3.

[0053] [Solution P2 (Karstedt catalyst)] A platinum(0)-1,3-divinyltetramethyldisiloxane complex was prepared in normal heptane so that the platinum atom content was 0.1% by mass, and the mixture was stirred for 1 hour using a shaker.

[0054] [Solution P3 (chloroplatinic acid)] Hexachloroplatinic (IV) acid was prepared in isopropyl alcohol so that the platinum atom content was 0.1 mass %, and then the mixture was stirred for 1 hour using a shaker.

[0055] The primer was applied by mixing solution P1 and solution P2 or solution P3 in the combination shown in Table 1 so that the nitrogen atomic weight and platinum atomic weight were in the ratio shown in Table 1, stirring with a shaker for 1 hour to prepare a primer composition, and then applying it with a brush. The mixture was left to dry at room temperature for 30 minutes and then heated at 120°C for 30 minutes. The amount after drying was 1.5 g / m 2 It became.

[0056] [Base silicone rubber compound] It is composed of 99.9 mol% dimethylsiloxane units, 0.075 mol% methylvinylsiloxane units, and 0.025 mol% dimethylvinylsiloxane units, and has a weight average degree of polymerization of 8,000 and a vinyl group content of 1.3 × 10-5 100 parts by mass of an organopolysiloxane in which a in the formula (I) is 2.00, and a specific surface area measured by the BET method of 200 m 2 25 parts by mass of fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) having a molecular weight of 1 / g, 4 parts by mass of dimethyldimethoxysilane as a surface treatment agent, 0.15 parts by mass of methylvinyldimethoxysilane, and 1 part by mass of hydrochloric acid (pH = 3) were kneaded in a kneader and heat-treated at 180°C for 1 hour to obtain a silicone-based compound.

[0057] [Silicone rubber composition (addition crosslinking)] To 100 parts by mass of the base silicone rubber compound, 0.05 parts by mass of a platinum catalyst (Pt concentration: 1% by mass), 0.025 parts by mass of ethynylcyclohexanol, and 0.8 parts by mass of methylhydrogendimethylpolysiloxane (weight average degree of polymerization: 40, hydrosilyl group amount: 0.014 mol / g) which is terminally blocked with trimethylsiloxy groups and has an average of 20 hydrosilyl groups on the side chains, and in which b in the formula (II) is 1.5, c is 0.50, and b+c is 2.05, were blended using a two-roll mill.

[0058] [Adhesive base material] A polypropylene resin substrate with a width of 25 mm, length of 100 mm and thickness of 2 mm was used.

[0059] [Plasma treatment] The surface of the polypropylene resin substrate was washed with ethanol, dried, and then subjected to surface treatment using a plasma dry cleaner (ODC210, manufactured by Yamato Scientific Co., Ltd.) The surface treatment was performed for 1 minute under the conditions of a high-frequency output of 100 W, an oxygen flow rate of 100 mL / min, and a vacuum degree of 60 Pa.

[0060] [Silicon oxide coating] The surface of the polypropylene resin substrate was washed with ethanol, dried, and then surface treatment was performed using a silicon oxide film treatment device (Flamebond FB-5, manufactured by Soft99 Corporation). The flame size was adjusted to about 4 cm, the distance between the nozzle and the substrate was 3 cm, and the burner travel speed was set to 40 cm / sec, and the burner was moved back and forth over the substrate three times. The loss of gloss on the substrate surface confirmed that the treatment had been performed.

[0061] [Preparation of test specimens (press molding)] The edge of a plasma-treated or silicon oxide-coated polypropylene resin substrate was treated with a primer over an area of ​​25 mm x 12.5 mm. The primer-treated substrate was placed on the bottom of a 50 mm x 70 mm x 2 mm mold, 10 g of silicone rubber composition was placed on top, and press molding was performed at 120°C and 10 minutes under a pressure of 10 MPa. The test piece in which the polypropylene resin substrate and silicone rubber composition were integrated was removed from the mold and placed in an oven at 120°C and heated for an additional hour.

[0062] [Adhesion test] The adhesion test was carried out on the day after the silicone rubber was molded. The test pieces obtained by the above method were evaluated by a 180 degree peel test in which the rubber and the substrate were pulled, and were evaluated according to the following criteria. A: The adhesive surface does not peel off at all (or the rubber breaks in other areas) B: Rubber fracture and interfacial peeling occur together C: 100% interfacial peeling

[0063] The test results are shown in Table 1. It was shown that when a primer layer consisting of a primer composition in which a certain amount of a platinum group metal compound was added to a mixture of a silane compound in which a 3-aminopropyl group is bonded to a silicon atom and a silane compound having one or more epoxy group-containing organic groups in one molecule was provided on a polypropylene resin substrate that had been subjected to a dry surface treatment, strong adhesive strength was obtained even when molding was performed in a mold. [Table 1]

Claims

1. A bonded article in which polypropylene resin that has been dry-treated by plasma treatment or silicon oxide film treatment and addition-curing silicone rubber are bonded together with a primer composition, the primer composition being: (A) a silane compound having a 3-aminopropyl group bonded to a silicon atom; (B) a silane compound having one or more epoxy group-containing organic groups in one molecule, and (C) Platinum group metal catalyst wherein the molar ratio of nitrogen atoms contained in component (A) to platinum atoms contained in component (C) is 50:1 to 1:

1.

2. 2. The bonded article according to claim 1, wherein the component (A) is at least one member selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, and 3-aminopropylmethyldiethoxysilane.

3. A first step of performing a dry treatment on the surface of a polypropylene resin substrate by plasma treatment or silicon oxide film treatment; a second step of applying a primer composition to the surface of the substrate dry-treated in the first step and drying the composition to form a primer layer; and a third step of applying a silicone rubber composition to the surface of the primer layer and heat curing the composition to form an addition-cured silicone rubber layer, The primer composition comprises: (A) a silane compound having a 3-aminopropyl group bonded to a silicon atom; (B) a silane compound having one or more epoxy group-containing organic groups in one molecule, and (C) Platinum group metal catalyst wherein the molar ratio of nitrogen atoms contained in component (A) to platinum atoms contained in component (C) is 50:1 to 1:

1.

4. The amount of the primer layer formed by applying and drying the primer composition after drying is 0.05 to 5 g / m 2 4. The method for producing a bonded article according to claim 3,

5. The method for producing a bonded article according to claim 3, wherein the silicone rubber composition contains the following components (D) to (I): (D) Organopolysiloxane having a degree of polymerization of 100 to 10,000 and having two or more alkenyl groups bonded to silicon atoms in one molecule: 100 parts by mass (E) A specific surface area measured by the BET method is 50 to 500 m 2 / g: 10 to 100 parts by mass of reinforcing silica per 100 parts by mass of component (D). (F) an organohydrogenpolysiloxane having two or more hydrosilyl groups per molecule: an amount such that the amount of hydrosilyl groups in component (F) is 0.5 to 5 moles per mole of alkenyl groups in component (D) (G) Platinum group metal catalyst: 0.5 to 1,000 ppm by mass of platinum group metal relative to the component (D).

6. 4. The method for producing a bonded article according to claim 3, wherein in the third step of applying a silicone rubber composition to the surface of the primer layer and heat-curing it to form a silicone rubber layer, the silicone rubber composition is heat-molded by any method selected from compression molding, press molding, and injection molding.

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