Adhesive composition and molded article

Abstract

To provide an adhesive composition which is excellent in adhesion between metal and a polyamide resin, and a molded article bonded with the adhesive composition.SOLUTION: An adhesive composition contains an acrylic polymer (A) which contains (anhydrous) maleic acid (a1), glycidyl (meth)acrylate (a2) and other monomer (a3) as essential raw materials and has a weight average molecular weight of 5,000-150,000, wherein a mass ratio of the (anhydrous) maleic acid (a1) in a monomer component that is a raw material of the acrylic polymer (A) is 20-40 mass%, a mass ratio of the glycidyl (meth)acrylate (a2) is 25-50 mass%, and a mass ratio of the other monomer (a3) is 10-55 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition and a molded article. [Background technology]

[0002] Many metal parts, including steel plates, are used in automobiles, home appliances, office equipment, and the like. These metal parts are often formed by pressing metal plates to a desired shape and then joining them to other metal or plastic parts by welding, screwing, or other methods. In this process, the surface of the metal plate is given adhesive properties with respect to plastic, and the metal plate is then pressed. The metal plate is then placed in a plastic molding die, and molten plastic is poured into the metal plate and cooled and solidified, thereby bonding the metal and plastic parts together to form a metal-plate composite resin molded product. These methods, known as in-mold molding and insert molding, have attracted attention because they can improve the efficiency of component manufacturing processes and reduce the weight of components.

[0003] A method for imparting adhesiveness to plastics to the surface of a metal sheet uses a resin material that has a high affinity for metal sheets and plastics. For example, when joining a resin molded product such as an olefin to a metal sheet by injection molding, a technology has been disclosed that uses a surface-treated metal in which a chemical conversion coating and then an adhesive layer are sequentially laminated to the metal sheet, thereby enabling high adhesive strength and easy joining (see Patent Document 1). Also, an injection molding adhesive has been proposed that is made by dispersing a specific acid-modified polypropylene resin in an aqueous medium, even without a chemical conversion layer on the metal sheet (see Patent Document 2).

[0004] However, all of these methods are for adhesion between metal and olefin resin, and none of them exhibit good adhesion to polyamide resin (nylon) used in automobile parts that require sliding properties. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-110318 [Patent Document 2] Japanese Patent Application Publication No. 2017-31302 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide an adhesive composition that has excellent adhesion between metal and polyamide resin, and a molded article bonded with said adhesive composition. [Means for solving the problem]

[0007] As a result of investigations conducted by the present inventors to solve the above-mentioned problems, they found that an adhesive composition containing an acrylic polymer having a specific composition and a weight-average molecular weight of 5,000 to 150,000 can solve the above-mentioned problems.

[0008] Specifically, the present invention relates to an adhesive composition containing an acrylic polymer (A) having a weight average molecular weight of 5,000 to 150,000, and consisting essentially of maleic anhydride (a1), glycidyl (meth)acrylate (a2), and other monomers (a3), wherein the mass ratio of the maleic anhydride (a1) in the monomer components that are the raw materials for the acrylic polymer (A) is 20 to 40 mass%, the mass ratio of the glycidyl (meth)acrylate (a2) is 25 to 50 mass%, and the mass ratio of the other monomers (a3) ​​is 10 to 55 mass%. [Effects of the Invention]

[0009] The adhesive composition of the present invention has excellent adhesive properties and can be used as a variety of adhesives, and is particularly useful as an adhesive between different types of materials. DETAILED DESCRIPTION OF THE INVENTION

[0010] The aqueous resin composition of the present invention is an adhesive composition containing an acrylic polymer (A) having a weight average molecular weight of 5,000 to 150,000, and consisting essentially of maleic acid (anhydride) (a1), glycidyl (meth)acrylate (a2), and other monomers (a3), in which the mass ratio of the maleic acid (anhydride) (a1) in the monomer components that are the raw materials for the acrylic polymer (A) is 20 to 40 mass%, the mass ratio of the glycidyl (meth)acrylate (a2) is 25 to 50 mass%, and the mass ratio of the other monomers (a3) ​​is 10 to 55 mass%.

[0011] In the present invention, the term "(maleic anhydride)" refers to either or both of "maleic acid" and "maleic anhydride," and the term "(meth)acrylate" refers to either or both of "acrylate" and "methacrylate."

[0012] Examples of the other monomers include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; (meth)acrylamide, glycidyl (meth)acrylate, 2-methylaminoethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and tetrahydrofurfuryl. Examples of suitable monomers include (meth)acrylate, γ-methacryloxypropyltrimethoxysilane, vinyltriethoxysilane, and other functional group-containing monomers; cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, diethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerin di(meth)acrylate, α-methylstyrene, paramethylstyrene, chloromethylstyrene, (meth)acrylic acid, fumaric acid, citraconic acid (anhydride), mesaconic acid, itaconic acid (anhydride), and aconitic acid (anhydride). Among these, alkyl (meth)acrylates having an alkyl group containing 1 to 18 carbon atoms are preferred because they provide improved adhesiveness. These other monomers (a3) ​​can be used alone or in combination of two or more.

[0013] The amount of the maleic acid (anhydride) (a1) used is 20 to 40 mass % in terms of mass ratio in the monomer components that are the raw materials of the acrylic polymer (A), and is preferably 30 to 40 mass % because it provides better adhesiveness.

[0014] The amount of the glycidyl (meth)acrylate (a2) used is in the range of 25 to 50 mass % in terms of mass ratio in the monomer components that are the raw materials of the acrylic polymer (A), and is preferably 25 to 40 mass % because it provides better adhesiveness.

[0015] The amount of the other monomer (a3) ​​used is 10 to 55 mass % in terms of mass ratio in the monomer components that are the raw materials of the acrylic polymer (A), and is preferably 25 to 50 mass % because this provides better adhesiveness.

[0016] The weight-average molecular weight of the acrylic polymer (A) is 5,000 to 150,000, and more preferably 10,000 to 50,000, as this provides better adhesiveness. The weight-average molecular weight is a value calculated in terms of polystyrene based on gel permeation chromatography (hereinafter abbreviated as "GPC") measurements.

[0017] The acid value of the acrylic polymer (A) is preferably 220 to 460 mgKOH / g, more preferably 340 to 460 mgKOH / g, because this provides better adhesiveness. In the present invention, the acid value of the acrylic polymer (A) is an acid value calculated from the composition of the monomers that are raw materials.

[0018] The acrylic polymer (A) can be produced, for example, by radical polymerization of the maleic acid (anhydride) (a1), the glycidyl (meth)acrylate (a2), and the other monomer (a3) ​​in an organic solvent in the presence of a polymerization initiator at a temperature of 60 to 140°C.

[0019] Examples of the organic solvent that can be used include aromatic solvents such as toluene and xylene, alicyclic solvents such as cyclohexanone, ester solvents such as butyl acetate and ethyl acetate, cellosolve solvents such as isobutanol, normal butanol, isopropyl alcohol, sorbitol and propylene glycol monomethyl ether acetate, and ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone. These solvents can be used alone or in combination of two or more.

[0020] Examples of the polymerization initiator include azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), and azobiscyanovaleric acid; organic peroxides such as tert-butyl peroxypivalate, tert-butyl peroxybenzoate, tert-butylperoxy-2-ethylhexanoate, di-tert-butyl peroxide, di-tert-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide, and tert-butyl hydroperoxide; and inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate. These polymerization initiators can be used alone or in combination. The polymerization initiator is preferably used in an amount of 0.1 to 10% by mass relative to the total amount of the monomers used as raw materials for the acrylic polymer (A).

[0021] The adhesive composition of the present invention contains the acrylic polymer (A), and from the viewpoint of imparting good coating workability and the like, it preferably contains the above-mentioned organic solvent as a solvent.

[0022] The acrylic polymer (A) contained in the adhesive composition of the present invention is preferably 10 to 90% by mass, more preferably 20 to 60% by mass, from the viewpoint of imparting good coating workability and the like.

[0023] The organic solvent contained in the adhesive composition of the present invention is preferably 10 to 90% by mass, more preferably 40 to 80% by mass, from the viewpoint of imparting good coating workability and the like.

[0024] Examples of the organic solvent contained in the adhesive composition of the present invention include the organic solvents described above as being usable in the production of the acrylic polymer (A).

[0025] The adhesive composition of the present invention may further contain, as necessary, additives such as curing catalysts, lubricants, fillers, thixotropy agents, tackifiers, waxes, heat stabilizers, light resistance stabilizers, fluorescent brighteners, and foaming agents, pH adjusters, leveling agents, antigelling agents, dispersion stabilizers, antioxidants, radical scavengers, heat resistance imparting agents, inorganic fillers, organic fillers, plasticizers, reinforcing agents, catalysts, antibacterial agents, mildew inhibitors, rust inhibitors, thermoplastic resins, thermosetting resins, pigments, dyes, conductivity imparting agents, antistatic agents, moisture permeability improvers, water repellents, oil repellents, hollow foams, compounds containing crystal water, flame retardants, water absorbing agents, moisture absorbing agents, deodorizers, foam stabilizers, antifoaming agents, antifungal agents, preservatives, antialgae agents, pigment dispersants, antiblocking agents, and hydrolysis inhibitors.

[0026] The adhesive composition of the present invention has excellent adhesive properties and can be used as a variety of adhesives, and is particularly useful as an adhesive between different types of materials. [Example]

[0027] The present invention will be described in more detail below with reference to Examples and Comparative Examples. The weight average molecular weight of the acrylic polymer was measured under the following GPC measurement conditions.

[0028] [GPC measurement conditions] Measurement equipment: High-speed GPC equipment (Tosoh Corporation "HLC-8220GPC") Column: The following columns manufactured by Tosoh Corporation were connected in series and used. "TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mmI.D. x 30cm) x 1 Detector: RI (differential refractometer) Column temperature: 40℃ Eluent: tetrahydrofuran (THF) Flow rate: 1.0mL / min Injection volume: 100 μL (sample concentration 4 mg / mL in tetrahydrofuran solution) Standard sample: A calibration curve was prepared using the following monodisperse polystyrene.

[0029] (monodisperse polystyrene) Tosoh Corporation's "TSKgel Standard Polystyrene A-500" Tosoh Corporation's "TSKgel Standard Polystyrene A-1000" Tosoh Corporation's "TSKgel Standard Polystyrene A-2500" Tosoh Corporation's "TSKgel Standard Polystyrene A-5000" "TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation Tosoh Corporation's "TSKgel Standard Polystyrene F-2" Tosoh Corporation's "TSKgel Standard Polystyrene F-4" Tosoh Corporation's "TSKgel Standard Polystyrene F-10" Tosoh Corporation's "TSKgel Standard Polystyrene F-20" Tosoh Corporation's "TSKgel Standard Polystyrene F-40" Tosoh Corporation's "TSKgel Standard Polystyrene F-80" Tosoh Corporation's "TSKgel Standard Polystyrene F-128" Tosoh Corporation's "TSKgel Standard Polystyrene F-288" Tosoh Corporation's "TSKgel Standard Polystyrene F-550"

[0030] (Example 1: Production and evaluation of adhesive composition (1)) A 1.0 L reactor equipped with a stirrer, thermometer, condenser, and nitrogen blower was charged with 80 parts by weight of methyl ethyl ketone and heated to 55°C. A mixture of 35 parts by weight of maleic anhydride, 30 parts by weight of glycidyl methacrylate, 35 parts by weight of n-butyl acrylate, 0.8 parts by weight of peroxide (Nippon Shokubai "Perbutyl PV"), and 40 parts by weight of methyl ethyl ketone was added dropwise over a period of 3 hours to allow the reaction to proceed. After the reaction was complete, the mixture was held at the same temperature for 2 hours and then cooled to yield adhesive composition (1). This adhesive composition (1) had a nonvolatile content of 43.1%, a viscosity of 320 mPa·s, and an acid value of 400 mgKOH / g of the acrylic polymer.

[0031] (Example 2: Production and evaluation of adhesive composition (2)) A 1.0 L reactor equipped with a stirrer, thermometer, condenser, and nitrogen blower was charged with 80 parts by weight of methyl ethyl ketone and heated to 55°C. A mixture of 25 parts by weight of maleic anhydride, 45 parts by weight of glycidyl methacrylate, 30 parts by weight of n-butyl acrylate, 0.8 parts by weight of peroxide (Nippon Shokubai "Perbutyl PV"), and 40 parts by weight of methyl ethyl ketone was added dropwise over a period of 3 hours to allow the reaction to proceed. After the reaction was complete, the mixture was held at the same temperature for 2 hours and then cooled to yield adhesive composition (2). This adhesive composition (2) had a nonvolatile content of 43.3%, a viscosity of 180 mPa·s, and an acid value of 286 mgKOH / g of the acrylic polymer.

[0032] (Comparative Example 1: Production and Evaluation of Adhesive Composition (R1)) A 1.0 L reactor equipped with a stirrer, thermometer, condenser, and nitrogen blower was charged with 80 parts by weight of methyl ethyl ketone and heated to 55°C. A mixture of 25.0 parts by weight of maleic anhydride, 20.0 parts by weight of styrene, 55.0 parts by weight of n-butyl acrylate, 1.6 parts by weight of peroxide (Nippon Shokubai "Perbutyl PV"), and 40 parts by weight of methyl ethyl ketone was added dropwise over a period of 3 hours to allow the reaction to proceed. After the reaction was complete, the mixture was held at the same temperature for 2 hours and then cooled to yield adhesive composition (R1). This adhesive composition (R1) had a nonvolatile content of 43.1%, a viscosity of 240 mPa·s, and an acid value of 286 mgKOH / g of the acrylic polymer.

[0033] (Comparative Example 2: Production and Evaluation of Adhesive Composition (R2)) 100 parts by mass of isotactic homopolypropylene resin (MFR (melt flow rate) = 2 g / 10 min, 180°C, 2160 g load) was reacted with 5.5 parts by mass of maleic anhydride and 1.0 part by mass of di-t-butyl peroxide using a twin-screw extruder set at 170°C to obtain an acid-modified polypropylene resin. This resin was washed several times with acetone and then dried in a vacuum dryer to obtain an acid-modified polypropylene resin. 90 parts by mass of this acid-modified polypropylene resin was further dissolved in 210 parts by mass of cyclohexanone to obtain adhesive composition (R2). This adhesive composition (R2) had a nonvolatile content of 29.8% and a viscosity of 1950 mPa·s.

[0034] [Preparation of test panels] The adhesive composition obtained above was dropped onto an aluminum plate (10 mm x 70 mm) in an amount of 0.005 to 0.015 cc using a dropper, and spread laterally to leave an overlapping area of ​​50 mm 2 After bonding the polyamide 11 molded plates together so that the bonded portions were fixed with clips, the mixture was left at 23°C for 24 hours.

[0035] [Adhesion evaluation] The shear strength of the test plate obtained above was measured using an Autograph manufactured by Shimadzu Corporation at a tension speed of 10 mm / min.

[0036] The monomer compositions and evaluation results of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 1.

[0037] [Table 1]

[0038] It was confirmed that the adhesive compositions of Examples 1 and 2 of the present invention had high shear strength and excellent adhesiveness.

[0039] On the other hand, Comparative Example 1 is an example in which glycidyl (meth)acrylate (a2) was not used as a raw material for the acrylic polymer, and it was confirmed that the shear strength was small and the adhesiveness was poor.

[0040] Comparative Example 2 is an example in which an acid-modified polypropylene resin was used instead of the acrylic polymer (A), but it was confirmed that the shear strength was small and the adhesiveness was poor.

Claims

1. An adhesive composition comprising an acrylic polymer (A) having a weight average molecular weight of 30,000 to 50,000, and consisting essentially of maleic anhydride (a1), glycidyl (meth)acrylate (a2), and another monomer (a3), wherein the other monomer (a3) ​​is one or more monomers selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, cyclohexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; and wherein the mass ratio of the maleic anhydride (a1) in the monomer components serving as raw materials for the acrylic polymer (A) is 20 to 40 mass%, the mass ratio of the glycidyl (meth)acrylate (a2) is 25 to 50 mass%, and the mass ratio of the other monomer (a3) ​​is 25 to 50 mass%.

2. 2. The adhesive composition according to claim 1, wherein the acrylic polymer (A) has an acid value of 220 to 460 mgKOH / g.

3. A molded article bonded with the adhesive composition according to claim 1 or 2.

4. A molded article in which a metal plate and a polyamide molded plate are bonded together with the adhesive composition of claim 1 or 2.

Images