JP2023027794A - Joint material of polypropylene resin and silicone rubber, and method for producing the same - Google Patents

Abstract

To provide a method for producing a joint material in which a polypropylene resin and silicone rubber are strongly joined to each other.SOLUTION: There is provided a joint material in which a polypropylene resin and silicone rubber are joined to each other by a primer composition. A method for producing a joint material of a polypropylene resin and silicone rubber includes: a first step of subjecting the surface of a polypropylene resin base material to dry treatment; a second step of coating a primer composition containing (A) a silane compound in which a 3-aminopropyl group is bonded to a silicon atom, and (B) a silane compound having one or more epoxy group-containing organic groups in one molecule onto the base material surface subjected to dry treatment in the first step, drying the base material surface, and forming a primer layer, after the first step; and a third step of applying a silicone rubber composition to the surface of the primer layer, heating and curing the silicone rubber composition, and forming a silicone rubber layer, after the second step.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a bonded product of polypropylene resin and silicone rubber and a method for producing the same.

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 parts in combination with organic resins and metals. . Polypropylene resin, which is a type of polyolefin resin, is second only to polyethylene resin in production volume among synthetic resins, and has low specific gravity and excellent mechanical strength, workability, and scratch resistance. However, polypropylene resin is known as a difficult-to-adhere material, and no technique has yet been found to develop strong adhesion between polypropylene resin and silicone rubber so as to ensure cohesive failure.

As an example of examining the adhesion of polypropylene resin and silicone rubber, Japanese Patent Application Laid-Open No. 60-247556 (Patent Document 1) describes the addition of an epoxy compound, an acid anhydride, an acrylic-modified silane, and unsaturated carbonization to an addition-curable silicone composition. Addition of hydrogen-containing oxirane has been proposed, but although cohesive failure is obtained with polyethylene resin, sufficient adhesive strength with respect to polypropylene resin is not obtained.
In JP-A-60-084335 (Patent Document 2), a silane coupling agent layer containing aminosilane and vinylsilane is provided on a vulcanized silicone rubber, and a silicone/polyolefin copolymer and a thermoplastic resin are added thereto. It says that they are heated and vulcanized at the same time, but it is difficult to mold the silicone rubber on the polypropylene resin by this method.
Japanese Patent Application Laid-Open No. 2004-210894 (Patent Document 3) states that a chlorinated polyolefin resin and a silicone sealant are adhered via an aminosilane compound and/or a ketimine compound. The polypropylene resin coated with only aminosilane without treatment did not exhibit sufficient adhesive strength to the addition-curing silicone resin.
In addition, in Japanese Patent Application Laid-Open No. 2009-1555358 (Patent Document 4), a moisture-curable silicone rubber composition is passed through a silicon oxide film formed by burning an organosilicon compound, which is also partly practiced in the present invention. It is adhered to various resin substrates including polypropylene resin. However, according to the study by the present inventors, no strong adhesion to addition-curable silicone rubber was obtained in any of the primer treatments in combination with the silane coupling agents contained in the compositions of the Examples.
Furthermore, in Japanese Patent Laid-Open No. 2013-244652 (Patent Document 5), a polypropylene resin substrate that has been subjected to silicon oxide film treatment (itro treatment) is provided with a primer layer containing methylhydrogenpolysiloxane as a main component, and addition curing is performed. Although heat molding of silicone rubber has been proposed, the present inventors have found that the adhesive strength is not strong enough to cause cohesive failure of the addition cure silicone rubber.

JP-A-60-247556 JP-A-60-084335 JP 2004-210894 A JP 2009-155358 A JP 2013-244652 A

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a bonded article in which a polypropylene resin and a silicone rubber are firmly bonded together, and a method for producing the same.

As a result of intensive research to achieve the above object, the present inventors have found that a polypropylene resin substrate that has been subjected to plasma treatment or silicon oxide film treatment, a silane compound in which a γ-aminopropyl group is bonded to a silicon atom, and an epoxy group A primer composition containing as an essential component a silane compound containing the The inventors have found that good adhesion can be obtained, and completed the present invention.

Accordingly, the present invention provides the following jointed product of polypropylene resin and silicone rubber and a method for producing the same.

<1>
Bonded product in which polypropylene resin and silicone rubber are bonded using the following primer composition.
(A) a silane compound having a 3-aminopropyl group bonded to a silicon atom, and
(B) A primer composition containing a silane compound having one or more epoxy group-containing organic groups in one molecule.

<2>
A first step of performing a dry treatment on the surface of the polypropylene resin base material;
After the first step,
(A) a silane compound having a 3-aminopropyl group bonded to a silicon atom, and
(B) A primer composition containing a silane compound having one or more epoxy group-containing organic groups in one molecule is applied to the substrate surface dry-treated in the first step and dried to form a primer layer. a second step of
After the second step,
The method for producing a jointed product of polypropylene resin and silicone rubber according to <1>, further comprising the third step of applying a silicone rubber composition to the surface of the primer layer and heating and curing to form a silicone rubber layer.

<3>
The method for producing a joined product of polypropylene resin and silicone rubber according to <2>, wherein the dry treatment is plasma treatment or silicon oxide film treatment.

<4>
The component (A) is one or more selected from 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane and 3-aminopropylmethyldiethoxysilane. <1> or <2>.

<5>
The polypropylene resin according to any one of <1> to <4>, wherein the primer layer formed by applying and drying the primer composition has a weight of 0.05 to 5 g / m ² A method for producing a bonded article of silicone rubber.

<6>
The method for producing a bonded product of polypropylene resin and silicone rubber according to any one of <2> to <5>, wherein the silicone rubber composition contains the following components (C) to (F).
(C) 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 (D) Specific surface area measured by BET method is 50 Reinforcing silica of up to 500 m ² /g: 10 to 100 parts by mass (E) Organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule: Per mol of alkenyl groups in component (C) ( (F) platinum group metal catalyst: 0.5 to 1,000 ppm in terms of mass of platinum group metal relative to component (C)

By using the manufacturing method of the present invention, a bonded product in which polypropylene resin and silicone rubber are firmly bonded can be obtained. Polypropylene resin is used in various applications such as home appliances, stationery, automobile parts, toys, and sporting goods. It is also useful for adding designability.

The present invention will be described in more detail below.

The present invention is a jointed article in which a polypropylene resin and a silicone rubber are joined together using the following primer composition.
(A) a silane compound having a 3-aminopropyl group bonded to a silicon atom, and
(B) A primer composition containing a silane compound having one or more epoxy group-containing organic groups in one molecule.

Moreover, the manufacturing method of the bonded article of the present invention comprises:
A first step of performing a dry treatment on the surface of the polypropylene resin base material;
After the first step,
(A) a silane compound having a 3-aminopropyl group bonded to a silicon atom, and
(B) A primer composition containing a silane compound having one or more epoxy group-containing organic groups in one molecule is applied to the substrate surface dry-treated in the first step and dried to form a primer layer. a second step of
After the second step,
and a third step of applying a silicone rubber composition to the surface of the primer layer and curing by heating to form a silicone rubber layer.

Polypropylene resin The polypropylene resin substrate used in the present invention is not particularly limited, and polypropylene resins having various melting points and molecular weights can be used. In general, polypropylene resin is a homopolymer that is a single polymer of propylene only, a random copolymer that contains ethylene at a rate of 4.5% by weight or less, and a homopolymer that is copolymerized with ethylene after polymerization. Although it is classified into three types of block copolymers including ethylene-propylene copolymers, any of them can be used.

Silicone Rubber The silicone rubber used in the present invention is not particularly limited, but addition-curable silicone rubbers containing alkenyl group-containing organopolysiloxane, reinforcing silica, organohydrogenpolysiloxane, and platinum group metal catalysts are used. preferable. Both millable rubber that can be plasticized and mixed with a kneading roll machine or closed mixer and liquid rubber that is in a liquid or pasty state before curing can be used.

1st Step Dry Treatment for Dry Treatment of Polypropylene Resin Substrate Surface In the present invention, the dry treatment of the polypropylene resin surface before forming the primer layer is an essential step. Dry treatments generally include plasma treatment, corona treatment, flame treatment, silicon oxide film treatment (itro treatment), UV treatment and excimer treatment. When the dry treatment is carried out, for example, a hydrophilic group having an oxygen atom is generated, thereby exhibiting hydrophilicity. 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 preferable because strong adhesion can be stably obtained.

The plasma treatment used in the present invention is a method of performing substrate surface treatment under reduced pressure using argon or oxygen plasma, and the plasma output, gas flow rate, degree of vacuum, treatment time, etc. can be adjusted. The treatment conditions can be adjusted based on the wettability and spreadability of the primer composition and the contact angle of a liquid such as water.

The silicon oxide film treatment used in the present invention is also called Itro 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 substrate surface. After the treatment, a large number of fine particles containing silicon dioxide as a main component are formed on the substrate surface, and the reactivity with the primer composition is improved. The degree of surface treatment can be adjusted by adjusting the size and shape of the flame, the distance between the burner and the substrate, the moving speed of the burner, the treatment time, and the like. The treatment conditions can be adjusted based on the wettability and spreadability of the primer composition and the contact angle of a liquid such as water. Further, the effective procedure of this silicon oxide film treatment is described in detail in Japanese Patent Application Laid-Open No. 2003-238710.

Second step of forming a primer layer on the substrate surface 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, and
(B) A primer composition containing a silane compound having one or more epoxy group-containing organic groups in one molecule.
Each component will be described in detail below.

(A) A silane compound in which a 3-aminopropyl group is bonded to a silicon atom The silane compound in which a 3-aminopropyl group is bonded to a silicon atom of component (A) is the key material of the present invention. Good adhesion is obtained. The silane compound has one or more, preferably one or two, more preferably one 3-aminopropyl group bonded to a silicon atom per molecule.
In addition, the silicon-bonded group other than the 3-aminopropyl group includes a group selected from an alkyl group having 1 to 10 carbon atoms and an alkoxy group having 1 to 6 carbon atoms. Those having an alkoxy group are preferable.
Specific examples of (A) component silane compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, di( 3-aminopropyl)dimethoxysilane and di(3-aminopropyl)diethoxysilane can be mentioned. (A) component can be used individually by 1 type or in combination of 2 or more types as appropriate.
Known aminosilanes include an N-2-(aminoethyl)-3-aminopropyl group, an N-(1,3-dimethyl-butylidene)propylamino group, or an N-phenyl-3-aminopropyl group on the silicon atom. There are bound silane compounds, but none of them give strong adhesion.

(B) Silane Compound Having an Epoxy Group-Containing Organic Group As the component (B), a silane compound having an epoxy group-containing organic group, known compounds can be used. The silane compound has one or more, preferably one or two, more preferably one epoxy group-containing organic group bonded to a silicon atom per molecule.
In addition, the silicon-bonded group other than the epoxy group-containing organic group includes a group selected from an alkyl group having 1 to 10 carbon atoms and an alkoxy group having 1 to 6 carbon atoms. Those having an alkoxy group are preferable.
Specific examples of the silane compound (B) include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-glycidoxypropyltriethoxysilane, due to their availability and high reactivity. Propylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane may be mentioned. (B) component can be used individually by 1 type or in combination of 2 or more types as appropriate.

Regarding the mixing ratio of the components (A) and (B) in the primer composition, the molar ratio of the amino group to the epoxy group is preferably 2:8 to 8:2, more preferably 3:7 to 7:3, and 4: 6 to 6:4 is more preferred.

(A) component and (B) component can also be diluted with a solvent and used. The solvent is not limited as long as it dissolves the components (A), (B) and other optional components, and known solvents can be used. The solvent may be used singly or in combination of two or more depending on the evaporation rate during coating 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; mixed aromatic/aliphatic hydrocarbons such as ligroin and rubber gasoline; Chlorinated hydrocarbons such as perchlorethylene 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 solvents. Among them, aliphatic alcohols are preferable, and aliphatic alcohols having 1 to 6 carbon atoms, which are easy to dry, are particularly preferable. 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 ring of the epoxy group to generate a hydroxyl group. This is because the reaction with atoms is suppressed and the storage stability of the primer solution can be enhanced.

The amount of the solvent to be blended is preferably 0.1 to 20% by mass, preferably 0.5% to 10% by mass, of the components (A), (B) and other optional components in the primer composition. is more preferable.

Examples of the method of applying the primer composition include brush coating and a spray device. The coating amount is adjusted by the coating method, the number of times of coating, the concentration of the primer composition, etc., and the amount can be estimated from the change in weight after drying. The coating amount of the primer composition is preferably 0.05 to 5 g/m ² , more preferably 0.1 to 2 g/m ² . If the coating amount is less than 0.05 g/m ² , sufficient adhesive strength may not be obtained, and if it exceeds 5 g/m ² , external stress may easily destroy the primer layer.

Third step of forming a 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 for example, the following (C) An addition curing type silicone rubber composition containing component (F) is preferred.
(C) 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 (D) Specific surface area measured by BET method is 50 Reinforcing silica of up to 500 m ² /g: 10 to 100 parts by mass (E) Organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule: Per mol of alkenyl groups in component (C) ( (F) platinum group metal catalyst: 0.5 to 1,000 ppm in terms of mass of platinum metal relative to component (C)
Each component will be described in detail below.

（式（Ｉ）中、Ｒは同一又は異種の炭素数１～１２の１価炭化水素基を示し、ａは１．９５～２．０５の数である。） (C) Alkenyl group-containing organopolysiloxane Component (C), which is preferably used in the above silicone rubber composition, has a degree of polymerization (or the number of silicon atoms in the molecule) of 100 to 10,000, and is an organopolysiloxane having two or more alkenyl groups bonded to silicon atoms. This component (C) is used as the main ingredient (base polymer) of this composition. Also, the alkenyl group-containing organopolysiloxane of component (C) is preferably a gum-like component (that is, highly viscous and non-liquid without self-fluidity) at room temperature (25°C). A silicone rubber composition containing this alkenyl group-containing organopolysiloxane as a main component is usually of a millable type (that is, raw rubber-like) and can be uniformly kneaded under shear stress by a kneader such as a roll mill. i) the composition. Component (C), the alkenyl group-containing organopolysiloxane, is typically represented by, for example, the following average compositional formula (I).

(In formula (I), R represents the same or different monovalent hydrocarbon group having 1 to 12 carbon atoms, and a is a number of 1.95 to 2.05.)

In the 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, methyl group, ethyl group, propyl group, butyl Alkyl groups such as group, hexyl group and octyl group; Cycloalkyl groups such as cyclopentyl group and cyclohexyl group; Fluoroalkyl groups such as 3,3,3-trifluoropropyl group; Alkenyl groups such as vinyl group, allyl group and propenyl group Aryl groups such as cycloalkenyl group, phenyl group and tolyl group; Aralkyl groups such as benzyl group and 2-phenylethyl group; methyl group, vinyl group, phenyl group and trifluoropropyl group are preferred, particularly A methyl group and a vinyl group are preferred. Methyl groups preferably account for 80 mol % or more, particularly 90 mol % or more, of R, and more preferably all R groups other than alkenyl groups are methyl groups.

Specific examples of the alkenyl group-containing organopolysiloxane of component (C) include those in which the main chain of the organopolysiloxane consists of dimethylsiloxane units, or in which a part of the main chain of the dimethylpolysiloxane contains a phenyl group, Those into which a diphenylsiloxane unit having a vinyl group, a 3,3,3-trifluoropropyl group, or the like, a methylvinylsiloxane unit, a methyl-3,3,3-trifluoropropylsiloxane unit, or the like is preferably introduced.

The organopolysiloxane of component (C) must have 2 or more (usually 2 to 50, particularly 2 to 20) alkenyl groups, preferably vinyl groups, in one molecule. Alkenyl groups preferably account for 0.01 to 10%, particularly 0.02 to 5%, of all R groups in composition formula (I).
The alkenyl group may be bonded to a silicon atom at the terminal of the molecular chain, bonded to a silicon atom in the middle (non-terminal) of the molecular chain, or both. It preferably contains alkenyl groups bonded to silicon atoms at both ends. Specifically, those whose molecular chain ends are blocked with a dimethylvinylsilyl group, a methyldivinylsilyl group, a trivinylsilyl group, or the like are preferred.

In the average composition formula (I) above, a is a number from 1.95 to 2.05, preferably from 1.98 to 2.02, more preferably from 1.99 to 2.01. The molecular structure of component (C), alkenyl group-containing organopolysiloxane, is basically such that the main chain consists of repeating diorganosiloxane units (R ₂ SiO _2/2 ), and both ends of the molecular chain are triorganosiloxy groups. _It generally has a linear structure blocked with (R ₃ SiO _1/2 ). It may have a branched structure (R is the same as above).

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

[GPC measurement conditions]
Developing solvent: toluene Flow rate: 0.6 mL/min
Detector: Differential Refractive Index Detector (RI)
Column: TSK Guard column SuperH-H
TSKgel Super H5000 (6.0 mm I.D. x 15 cm x 1)
TSKgel Super H4000 (6.0mm ID x 15cm x 1)
TSKgel Super H3000 (6.0mm I.D. x 15cm x 1)
(both manufactured by Tosoh Corporation)
Column temperature: 40°C
Sample injection volume: 50 μL (toluene solution with a concentration of 0.5% by mass)

The alkenyl group-containing organopolysiloxane of component (C) may be used singly or in combination of two or more having different molecular structures and degrees of polymerization.

Component (C), alkenyl group-containing organopolysiloxane, can be prepared by a known method, for example, by (co)hydrolyzing and condensing one or more organohalogenosilanes, or by reacting a cyclic polysiloxane with an alkaline or acidic catalyst. It can be obtained by ring-opening polymerization using

(D) Reinforcing Silica As the reinforcing silica, component (D), which is preferably used in the above silicone rubber composition, fine reinforcing silica powder commonly used in silicone rubber compositions can be used. (D) Component reinforcing silica includes, for example, fumed silica (fumed silica), dry silica such as pyrogenic silica, wet silica such as precipitated silica, and the like. is preferred.
The specific surface area measured by the BET method is preferably 50 to 500 m ² /g, more preferably 100 to 400 m ² /g, particularly preferably 100 to 300 m ² /g. If the specific surface area is less than 50 m ² /g, the mechanical strength may be insufficient. Moreover, if it is larger than 500 m ² /g, industrial production may become difficult.

The surface of this reinforcing silica may be subjected to hydrophobic treatment with a known treating agent such as chlorosilane or hexamethyldisilazane, if necessary.

The amount of reinforcing silica (D) added to the silicone rubber composition is preferably 10 to 100 parts by mass, more preferably 100 parts by mass of the alkenyl group-containing organopolysiloxane (C). is 20 to 70 parts by weight, particularly preferably 30 to 60 parts by weight. If it is less than 10 parts by mass, the addition amount is too small to obtain a sufficient reinforcing effect, and if it exceeds 100 parts by mass, workability may deteriorate and mechanical strength may decrease.

（式（ＩＩ）中、Ｒ²は互いに独立に同一又は異種の炭素数１～１０の非置換又は置換の１価炭化水素基である。ｂは０．７～２．１、ｃは０．００１～１で、かつｂ＋ｃは０．８～３を満足する数である。） (E) Organohydrogenpolysiloxane Component (E), which is preferably used in the above silicone rubber composition, has at least two, preferably three or more, silicon-bonded hydrogen atoms (hydrosilyl groups) per molecule. It is preferably an organohydrogenpolysiloxane having the following average composition formula (II) and is liquid at room temperature.

(In formula (II), R ² is independently the same or different, unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, b is 0.7 to 2.1, c is 0.7 to 2.1). 001 to 1, and b+c is a number that satisfies 0.8 to 3.)

In formula (II), each R ² independently represents the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, or the like. Alkyl groups may be mentioned.

Further, in formula (II), b is 0.7 to 2.1, preferably 0.8 to 2, c is 0.001 to 1, preferably 0.01 to 1, and b + c is 0.8 to 3, preferably a number satisfying 0.9 to 2.7.

The component (E) organohydrogenpolysiloxane has at least 2 (2 to 300) hydrosilyl groups, preferably 3 or more (eg 3 to 200), more preferably 4 or more (eg 4 to 100), which may be at the end of the molecular chain, in the middle (non-terminal) of the molecular chain, or at both. In addition, the organohydrogenpolysiloxane should generally have 2 to 300, preferably 3 to 200, and more preferably 4 to 100 silicon atoms (or the degree of polymerization) in one molecule. Also, the viscosity at 25° C. is preferably 0.5 to 1,000 mPa·s, more preferably 1 to 500 mPa·s, particularly preferably 5 to 300 mPa·s. This viscosity refers to a value measured at 25° C. using a rotational viscometer according to JIS K 7117-1:1999.

The amount of the organohydrogenpolysiloxane compounded is preferably 0.1 to 30 parts by mass, more preferably 0.3 to 10 parts by mass, per 100 parts by mass of the organopolysiloxane of component (C).
In this organohydrogenpolysiloxane, the molar ratio of hydrosilyl groups to the total alkenyl groups of component (C) is preferably in the range of 0.5 to 5, more preferably in the range of 0.8 to 3. , 1 to 2.5. When organohydrogenpolysiloxane is used, if the amount of organohydrogenpolysiloxane blended is too small, crosslinking may be insufficient and rubber physical properties such as strength and elongation may be poor. (The crosslink density is too high), and the physical properties of the rubber may similarly deteriorate.

(F) Platinum group metal catalyst The component (F) preferably used in the above silicone rubber composition includes platinum black, platinum chloride, chloroplatinic acid, a reaction product of chloroplatinic acid and a monohydric alcohol, chloride Complexes of platinic acid and olefins, platinum bisacetoacetate, palladium-based catalysts, rhodium-based catalysts, and the like can be mentioned.

The amount of component (F) can be a catalytic amount, and is usually preferably 0.5 to 1,000 ppm, more preferably 1 to 500 ppm, in terms of platinum metal mass with respect to component (C). .

Curing conditions for the 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 molding the silicone rubber composition onto the primer layer (that is, after primary curing), it is preferable to carry out post-curing (secondary curing) for the purpose of improving adhesion and compression set of the cured product. The post-curing conditions are preferably 100 to 180° C. and 30 minutes to 100 hours, more preferably 120 to 160° C. and 1 to 8 hours, in consideration of the heat resistant temperature and melting point of the polypropylene resin.

As a method for molding the silicone rubber composition, injection molding, compression molding, extrusion molding, transfer molding, or any other method may be employed.

EXAMPLES Hereinafter, the present invention will be specifically described by showing examples and comparative examples, but the present invention is not limited to the following examples.

[Base silicone rubber compound]
Consisting of 99.9 mol% of dimethylsiloxane units, 0.075 mol% of methylvinylsiloxane units, and 0.025 mol% of dimethylvinylsiloxane units, the weight average degree of polymerization is about 6,000, and the amount of vinyl groups is 1.4×10 ^-5 mol. 25 parts by mass of fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 m ² /g by the BET method, and 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 base compound.

[Silicone rubber composition (addition cross-linking)]
100 parts by mass of a base silicone rubber compound, 0.05 parts by mass of a platinum catalyst (Pt concentration of 1% by mass), 0.025 parts of ethynylcyclohexanol, both ends blocked with trimethylsiloxy groups and an average of 20 hydrosilyl groups in side chains 0.8 parts by mass of methylhydrogendimethylpolysiloxane (average degree of polymerization: 40, hydrosilyl group content: 0.014 mol/g) was blended with a two-roll mill.

[Silicone rubber composition (peroxide cross-linking)]
0.6 parts by mass of bis(4-methylbenzoyl) peroxide was blended with 100 parts by mass of the base silicone rubber compound using a two-roll mill.

[Silane compound]
As silane compounds having an amino group, 3-aminopropyltriethoxysilane (KBE-903, manufactured by Shin-Etsu Chemical Co., Ltd.), N-2-(aminoethyl)-3-aminopropylsilane (KBM-603, Shin-Etsu Chemical Co., Ltd.) Co., Ltd.), 3-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) as silane compounds having an epoxy group. KBM-303, manufactured by Shin-Etsu Chemical Co., Ltd.) and vinyltriethoxysilane (KBE-1003, manufactured by Shin-Etsu Chemical Co., Ltd.) were prepared as a silane compound having a vinyl group.

[Primer composition]
A primer composition was prepared by adding one or two types of predetermined silane compounds to isopropyl alcohol so that the concentration of each compound was 5% by mass. When two kinds of silane compounds were used, the amino groups, epoxy groups, and vinyl groups were adjusted to be equimolar amounts. After the preparation of the primer composition, the mixture was stirred for 1 hour with a shaker, and the primer composition was applied and dried on the following day. When the primer composition was applied by brushing, the mass after drying was approximately 0.5 g/m ² . Drying was carried out by leaving at room temperature for 2 hours or more.

[Adhesive base material]
A polypropylene resin substrate having a width of 25 mm, a length of 100 mm, and a thickness of 2 mm was obtained from Testpiece Co., Ltd.

[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 conditions of a high frequency output of 100 W, an oxygen flow rate of 100 mL/min, and a degree of vacuum of 60 Pa.

[Silicon oxide film treatment]
The surface of the polypropylene resin substrate was washed with ethanol, dried, and then subjected to surface treatment using a silicon oxide coating apparatus (Flamebond FB-5, manufactured by SOFT99 Corporation). The size of the flame was adjusted to about 4 cm, the distance between the crater and the substrate was 3 cm, and the moving speed of the burner was 40 cm/sec. The loss of luster on the surface of the base material confirmed that it had been treated.

[Adhesiveness]
Adhesion was evaluated with reference to the shear adhesion test in JIS K 6850:1999. The silicone rubber composition was extruded with a two-roll mill to a thickness of 2 mm and cut into a size of 25 mm×12.5 mm. It was sandwiched between two polypropylene resin substrates that had been plasma treated or silicon oxide film treated, and heated in an oven set at 150° C. for 2 hours. After taking it out of the oven and leaving it at room temperature for 12 hours or longer, it was pulled in the opposite direction at 50 mm/min with a tensile tester (TENSOMETER 2020, manufactured by Alpha Technologies Japan LLC) and the maximum test force was recorded. The polypropylene resin base material was chucked through waterproof abrasive paper (#180, JIS standard) to prevent the chucked portion from slipping.

Table 1 shows the test results. When a plasma-treated or silicon oxide film-treated polypropylene resin substrate is treated with a primer containing both a silane compound having a 3-aminopropyl group and a silane compound having an epoxy group, strong adhesive strength is obtained. The resulting cured product (silicone rubber) of the silicone rubber composition failed cohesively, or the chucked portion did not suffer sliding failure (non-destruction). A similar test was conducted with a silane compound having an N-2-(aminoethyl)-3-aminopropyl group, but all of them resulted in easy interfacial peeling.

Claims (6)

Bonded product in which polypropylene resin and silicone rubber are bonded using the following primer composition.
(A) a silane compound having a 3-aminopropyl group bonded to a silicon atom, and
(B) A primer composition containing a silane compound having one or more epoxy group-containing organic groups in one molecule. A first step of performing a dry treatment on the surface of the polypropylene resin base material;
After the first step,
(A) a silane compound having a 3-aminopropyl group bonded to a silicon atom, and
(B) A primer composition containing a silane compound having one or more epoxy group-containing organic groups in one molecule is applied to the substrate surface dry-treated in the first step and dried to form a primer layer. a second step of
After the second step,
2. The method for producing a bonded product of polypropylene resin and silicone rubber according to claim 1, further comprising a third step of applying a silicone rubber composition to the surface of the primer layer and heating and curing to form a silicone rubber layer. 3. The method for producing a joined product of polypropylene resin and silicone rubber according to claim 2, wherein the dry treatment is plasma treatment or silicon oxide film treatment. The component (A) is one or more selected from 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane and 3-aminopropylmethyldiethoxysilane. 3. The method for producing a bonded product of polypropylene resin and silicone rubber according to claim 1 or 2. The polypropylene resin and silicone rubber according to any one of claims 1 to 4, wherein the primer layer formed by applying and drying the primer composition has a weight of 0.05 to 5 g/m ² . manufacturing method of the joint. The method for producing a bonded product of polypropylene resin and silicone rubber according to any one of claims 2 to 5, wherein the silicone rubber composition contains the following components (C) to (F).
(C) 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 (D) Specific surface area measured by BET method is 50 Reinforcing silica of up to 500 m ² /g: 10 to 100 parts by mass (E) Organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule: Per mol of alkenyl groups in component (C) ( (F) platinum group metal catalyst: 0.5 to 1,000 ppm in terms of mass of platinum group metal relative to component (C)