JP2017031302A - Adhesive for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an additive for injection molding with water as a medium, useful for unifying a metal sheet and a metal in an injection molding and a metal sheet composite resin molded article having an adhesive coated film consisting of the adhesive, the metal sheet and the resin unified and excellent in heat resistance and wet heat resistance.SOLUTION: There is provided an adhesive for injection molding by dispersing an acid modified polypropylene resin in an aqueous medium, where the acid modified polypropylene resin contains unsaturated carboxylic acid of 1.5 to 10.0 mass%, a polypropylene component has an isotactic structure and a value of MFR (melt flow rate) at 180°C and 2160 g load is 400 g/10 min. or less.SELECTED DRAWING: None

Description

  The present invention relates to an injection molding adhesive, an adhesive coating, a metal plate having an adhesive coating, and a metal plate composite resin molded article made of the metal plate and a resin.

  Many metal parts such as steel plates are used in automobiles, home appliances, OA equipment, and the like. In many cases, such metal parts are used after being pressed to give a predetermined shape to a metal plate and then joined to other metal parts or plastic parts by welding or screwing.

  At that time, by giving adhesion to the plastic on the surface of the metal plate, pressing the metal plate, setting the metal plate in the plastic mold, pouring molten plastic and solidifying by cooling The metal part and the plastic part are bonded to form a metal plate composite resin molded product. Such a method called in-mold molding or insert molding is attracting attention because it leads to the efficiency of the member manufacturing process and the weight reduction of the member. As a method of imparting adhesiveness to the surface of the metal plate, a resin material having high affinity with the metal plate or plastic is used. For example, Patent Documents 1 and 2 propose such a technique. .

  Patent Document 1 discloses a technique in which a polar group-containing thermoplastic resin layer is formed on the surface of a metal plate for joining with a molded body made of glass fiber reinforced resin. Specifically, a maleic anhydride-modified polypropylene resin is laminated on the surface of a metal plate with a press or the like, and then inserted into a mold, and a polypropylene resin containing glass fibers is injection-molded and integrated. It is.

  On the other hand, in Patent Document 2, when a resin molded product and a metal plate are joined by injection molding, a surface-treated metal obtained by sequentially laminating a chemical conversion treatment film and then an adhesive layer on the metal plate is used, so that high adhesive strength and easy are achieved. The technique which can be joined to is disclosed.

JP 2001-341670 A JP2015-110318A

  However, Patent Document 1 discloses that the polar group-containing thermoplastic resin layer has a low maleic anhydride modification rate and the adhesive interaction between the polar group-containing thermoplastic resin layer and the metal plate is insufficient. In the method of laminating with a press or the like, the adhesion to the metal plate is insufficient, that is, the adhesive strength as a whole metal plate composite resin molded product is insufficient. In addition, Patent Document 2 discloses a technique using an aqueous adhesive, but the metal plate composite resin molded product using the adhesive has insufficient adhesive strength when used under high temperature or high humidity heat. there were. Moreover, since it is necessary to form two layers of a chemical conversion treatment film and an adhesive layer, there is a problem that the manufacturing process becomes complicated.

  The present invention solves the above-mentioned problems, and provides a useful adhesive when integrating a metal plate and a resin in injection molding, and a metal having an adhesive film made of the adhesive. The present invention provides a metal plate composite resin molded product excellent in heat resistance and moisture and heat resistance in which a plate and a resin are integrated.

As a result of intensive studies to solve the above problems, the present inventors have found that an aqueous dispersion containing an acid-modified polypropylene resin having a specific structure is suitable as an adhesive for injection molding,
The present invention has been reached.

That is, the gist of the present invention is as follows.
(1) An adhesive for injection molding in which an acid-modified polypropylene resin is dispersed in an aqueous medium, the acid-modified polypropylene resin containing 1.5 to 10.0% by mass of an unsaturated carboxylic acid, and a polypropylene component Has an isotactic structure, and an MFR (melt flow rate) value at 180 ° C. under a load of 2160 g is 400 g / 10 min or less.
(2) The adhesive for injection molding according to (1), which does not substantially contain a non-volatile aqueous agent.
(3) The adhesive for injection molding according to (1) or (2), wherein the weight average molecular weight in the aqueous dispersion is 0.15 μm or less.
(4) The adhesive for injection molding according to any one of (1) to (3), which contains a urethane resin and / or a crosslinking agent component.
(5) An adhesive film obtained by removing the aqueous medium of the injection molding adhesive according to any one of (1) to (4).
(6) A metal plate having the adhesive coating according to (5).
(7) A metal plate composite resin molded product in which the metal plate and the resin according to (6) are laminated via an adhesive film.
(8) The metal plate composite resin molded article according to (7), wherein the resin is a polypropylene resin.
(9) After charging the metal plate described in (6) in the mold, the molten resin is injected into the mold to laminate the resin on the metal plate via the adhesive film of the metal plate. A method for producing a metal plate composite resin molded product.

  The adhesive for injection molding of the present invention is excellent in adhesion between the metal plate and the resin, and the metal plate and resin metal plate composite resin molded product obtained through the adhesive coating of the adhesive has heat resistance and Excellent moisture and heat resistance. Further, since the injection molding adhesive of the present invention is a water-based adhesive, it is excellent from the viewpoint of environment and safety.

  The metal plate composite resin molded article using the injection molding adhesive of the present invention is excellent in heat resistance and moist heat resistance, and thus is useful for various applications such as automobile parts, home appliances, building materials, and OA equipment.

Hereinafter, the present invention will be described in detail.
The adhesive for injection molding of the present invention (hereinafter sometimes simply referred to as “adhesive”) is in the form of a so-called aqueous dispersion in which an acid-modified polypropylene resin is dispersed in an aqueous medium.

  In the present invention, the acid-modified polypropylene resin requires that the polypropylene component has an isotactic structure. If the polypropylene has a structure other than isotactic structure, such as syndiotactic structure or atactic structure, the adhesion when the metal plate and resin are combined by injection molding may be inferior, or the environment may be high temperature or high humidity There is a tendency for the adhesion to decrease below.

Polypropylene resins are generally homopolypropylenes composed only of propylene components, random polypropylene and block polypropylenes containing 1 to 10% by mass of ethylene components, and polypropylene terpolymers containing ethylene components and 1-butene components. Can be classified into polymers.
The polypropylene component of the acid-modified polypropylene resin in the present invention needs to be a homopolypropylene in which the olefin component consists only of the propylene component. When the polypropylene component of the acid-modified polypropylene resin is a polypropylene other than homopolypropylene, such as random polypropylene, block polypropylene, and terpolymer, it has poor adhesion when the metal plate and the resin are combined by injection molding. Or, there is a tendency for the adhesiveness to decrease under high temperature or high humidity heat environment.

The acid-modified polypropylene resin in the present invention is obtained by acid-modifying homopolypropylene having the isotactic structure as described above with an unsaturated carboxylic acid component.
Unsaturated carboxylic acid components used for acid modification include acrylic acid, methacrylic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, fumaric acid, crotonic acid, etc., as well as unsaturated dicarboxylic acid half esters and half amides And other derivatives. Among these, acrylic acid, methacrylic acid and (anhydrous) maleic acid are preferable from the viewpoint of adhesiveness, and (anhydrous) maleic acid is particularly preferable. In addition, “(anhydrous) to acid” means “to acid or anhydrous to acid”. That is, (anhydrous) maleic acid means maleic acid or maleic anhydride.
The unsaturated carboxylic acid component only needs to be copolymerized in the acid-modified polypropylene resin, and the form thereof is not limited. Examples of the copolymerization state include random copolymerization, block copolymerization, and graft copolymerization (grafting). Modification) and the like, and from the viewpoint of ease of production and adhesiveness, graft copolymerization is preferred.

The graft copolymerization method for introducing the unsaturated carboxylic acid component into the polypropylene resin is not particularly limited. For example, in the presence of a radical generator, the polypropylene resin and the unsaturated carboxylic acid are heated and melted to a melting point or higher of the polypropylene resin. Examples thereof include a reaction method and a method in which a polypropylene resin and an unsaturated carboxylic acid are dissolved in an organic solvent and then reacted by heating and stirring in the presence of a radical generator. The former method is preferable because the operation is simple.
Examples of the radical generator used for graft copolymerization include di-tert-butyl peroxide, dicumyl peroxide, tert-butyl hydroperoxide, tert-butyl cumyl peroxide, benzoyl peroxide, dilauryl peroxide, Examples thereof include organic peroxides such as cumene hydroperoxide, tert-butyl peroxybenzoate, ethyl ethyl ketone peroxide, and di-tert-butyl diperphthalate, and azonitriles such as azobisisobutyronitrile. These may be appropriately selected and used depending on the reaction temperature.

  The content of the unsaturated carboxylic acid component as a copolymerization component in the acid-modified polypropylene resin requires 1.5 to 10.0% by mass, and preferably 2.0 to 5.0% by mass. When the content of the unsaturated carboxylic acid component is less than 1.5% by mass, it becomes difficult to process the aqueous dispersion described later. Even if the content of the unsaturated carboxylic acid component is within a preferable range, if the content is small, the particle size of the aqueous dispersion tends to be large, or sufficient adhesion tends to be difficult to obtain. On the other hand, when it exceeds 10.0% by mass, the adhesiveness with the resin tends to be lowered.

  In the present invention, the acid-modified polypropylene resin may contain a component other than the olefin component and the unsaturated carboxylic acid component, such as a component such as (meth) acrylic acid ester, as a copolymer component. Although content of such a copolymerization component will not be specifically limited if it is a range which does not impair the effect of this invention, It is preferable that it is 20 mass% or less of acid-modified polypropylene resin.

  The most preferred specific example of the acid-modified polypropylene resin in the present invention includes isotactic polypropylene- (anhydrous) maleic acid binary copolymer. Since the acid-modified polypropylene resin is an isotactic polypropylene- (anhydrous) maleic acid binary copolymer, it has excellent adhesion when a metal plate and a resin are combined by injection molding, and has heat and moisture resistance. Excellent thermal properties. In addition, the maleic anhydride (maleic anhydride) in the isotactic polypropylene- (maleic anhydride) binary copolymer may be either maleic anhydride or maleic acid, or both may be mixed. The mixed composition is an isotactic polypropylene-maleic anhydride-maleic acid copolymer. In the present invention, this copolymer is also an isotactic polypropylene- (maleic anhydride) binary copolymer. Included in coalescence.

  The melt flow rate at 180 ° C. and 2160 g load, which is a measure of the molecular weight of the acid-modified polypropylene resin, is preferably 400 g / 10 min or less, more preferably 0.1 to 400 g / 10 min, and 1 to 300 g. / 10 min is more preferable, and 10 to 250 g / 10 min is particularly preferable. When the melt flow rate exceeds 400 g / 10 min, the adhesiveness tends to decrease under high temperature or wet heat conditions. Moreover, when the melt flow rate is extremely small, it tends to be difficult to obtain a stable aqueous dispersion.

  From the viewpoint of heat resistance, the acid-modified polypropylene resin preferably has a melting point of 130 ° C or higher, more preferably 135 ° C or higher, and particularly preferably 140 ° C or higher.

  The aqueous medium in the adhesive of the present invention is water or a liquid containing water as a main component, and may contain a basic compound or an organic solvent described later.

  The aqueous medium preferably contains a basic compound. The carboxyl group of the acid-modified polypropylene resin is neutralized by a basic compound, and the electric repulsion between the generated carboxyl anions prevents aggregation between the fine particles and imparts dispersion stability. The basic compound is not particularly limited as long as it can neutralize the carboxyl group, but is preferably a volatile compound from the viewpoint of maintaining good performance of the metal plate composite resin molded article.

As the basic compound, ammonia and organic amines are preferable. Specific examples of the organic amine include triethylamine, N, N-dimethylethanolamine, isopropylamine, aminoethanol, dimethylaminoethanol, diethylaminoethanol, ethylamine, diethylamine, isobutylamine, dipropylamine, 3-ethoxypropylamine, 3- Diethylaminopropylamine, sec-butylamine, propylamine, n-butylamine, 2-methoxyethylamine, 3-methoxypropylamine, 2,2-dimethoxyethylamine, monoethanolamine, morpholine, N-methylmorpholine, N-ethylmorpholine, pyrrole , Pyridine and the like.
The content of the basic compound is preferably 0.5 to 10 times equivalent to the carboxyl group in the acid-modified polypropylene resin, more preferably 0.8 to 5 times equivalent, and 0.9 to A 3.0-fold equivalent is particularly preferred. When the content of the basic compound is less than 0.5 times equivalent, the addition effect of the basic compound is not recognized, whereas when the content exceeds 10 times equivalent, the drying time during the formation of the adhesive layer becomes longer. Or the stability of the aqueous dispersion may be reduced.

The aqueous medium may contain an organic solvent. By including the organic solvent, the wettability to the substrate can be improved. Furthermore, by adding an organic solvent during the aqueous dispersion of the acid-modified polypropylene resin described later, the aqueous dispersion can be promoted and the dispersed particle size can be reduced.
The content of the organic solvent in the adhesive of the present invention is preferably 50% by mass or less, more preferably 0.1 to 45% by mass, further preferably 2 to 40% by mass, It is especially preferable that it is 3-35 mass%. When the content of the organic solvent exceeds 50% by mass, the stability as an aqueous dispersion may be lowered.
The organic solvent preferably has a solubility in water at 20 ° C. of 10 g / L or more, more preferably 20 g / L or more, and 50 g / L from the viewpoint of aqueous dispersion promotion performance and dispersion stability. More preferably, it is the above.
Moreover, according to the drying temperature at the time of drying the adhesive of this invention and obtaining an adhesive film, it is preferable that the boiling point of an organic solvent is 200 degrees C or less. An organic solvent having a boiling point exceeding 200 ° C. tends to remain in the adhesive film, and the adhesiveness and the like may be lowered.

Examples of the organic solvent include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, tert-amyl alcohol, Alcohols such as 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol and cyclohexanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone and cyclohexanone, ethers such as tetrahydrofuran and dioxane , Ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, 3-methoxybutyl acetate, methyl propionate, Esters such as ethyl onate, diethyl carbonate, dimethyl carbonate, glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol ethyl ether acetate, -Methoxy-2-propanol, 1-ethoxy-2-propanol, 3-methoxy-3-methyl-1-butanol, methoxybutanol, acetonitrile, dimethylformamide, dimethylacetamide, diacetone alcohol, ethyl acetoacetate, 1,2- Examples include dimethyl glycerin, 1,3-dimethyl glycerin, and trimethyl glycerin.
Among them, ethanol, n-propanol, isopropanol, n-butanol, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether are aqueous solutions of acid-modified polyolefin resins. It is effective and effective in promoting dispersion.
In the present invention, a mixture of these organic solvents may be used.

  In the present invention, the weight average particle diameter of the acid-modified polypropylene resin particles is preferably 0.15 μm or less, and more preferably 0.1 μm or less, from the viewpoint of suppressing variation in adhesiveness. By reducing the particle diameter, the film forming property of the adhesive layer can be improved, and variations in the adhesive property of the metal plate composite resin molded product can be reduced.

  The content of the acid-modified polypropylene resin in the adhesive of the present invention can be appropriately selected according to the bonding conditions, the adhesive layer thickness, performance, etc., and is not particularly limited, but keeps the viscosity of the aqueous dispersion moderate, and It is preferably 1 to 60% by mass, more preferably 3 to 55% by mass, further preferably 5 to 50% by mass, and more preferably 10 to 45% by mass in terms of expressing good coating properties. It is particularly preferred that

  The viscosity of the adhesive of the present invention is not particularly limited, but the viscosity measured at 20 ° C. with a B-type viscometer is preferably 1 to 100,000 mPa · s. Moreover, although pH is not specifically limited, It is preferable that it is pH 6-13.

  The adhesive of the present invention preferably contains substantially no nonvolatile aqueous dispersion aid. Although the present invention does not exclude the use of a nonvolatile aqueous dispersion aid, the acid-modified polypropylene resin is stable in an aqueous medium with a weight average particle size of 0.15 μm or less without using an aqueous dispersion aid. Can be dispersed. Since the adhesive of the present invention does not substantially contain a non-volatile aqueous dispersion aid, it is excellent in adhesiveness and water resistance, and these performances hardly change even in the long term.

  Here, the “aqueous dispersion aid” is a drug or compound added for the purpose of promoting aqueous dispersion or stabilizing the aqueous dispersion in the production of the aqueous dispersion. Means that it does not have a boiling point at normal pressure or has a high boiling point (for example, 300 ° C. or higher) at normal pressure.

  “Substantially free of non-volatile aqueous dispersion aid” means that such an aid is not used at the time of production (at the time of aqueous dispersion of the acid-modified polypropylene resin), and the resulting aqueous dispersion results in this aid. This means that no agent is contained. Therefore, the content of such an aqueous dispersion aid is particularly preferably zero, but within a range not impairing the effects of the present invention, it is 5% by mass or less, preferably 2% by mass or less, based on the acid-modified polypropylene resin. More preferably, it may be contained in an amount of less than about 0.5% by mass.

  Examples of the non-volatile aqueous dispersion aid used in the present invention include an emulsifier described later, a compound having a protective colloid effect, a modified wax, a high acid value acid-modified compound, a water-soluble polymer, and the like.

  Examples of the emulsifier include a cationic emulsifier, an anionic emulsifier, a nonionic emulsifier, and an amphoteric emulsifier. In addition to those generally used for emulsion polymerization, surfactants are also included. For example, anionic emulsifiers include higher alcohol sulfates, higher alkyl sulfonates, higher carboxylates, alkyl benzene sulfonates, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, vinyl sulfosuccinates. Nonionic emulsifiers include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyethylene glycol fatty acid ester, ethylene oxide propylene oxide block copolymer, polyoxyethylene fatty acid amide, ethylene oxide-propylene oxide. Compounds having a polyoxyethylene structure such as copolymers and sorbitan derivatives such as polyoxyethylene sorbitan fatty acid esters And examples of the amphoteric emulsifiers, lauryl betaine, lauryl dimethyl amine oxide, and the like.

  Compounds having protective colloid action, modified waxes, acid-modified compounds with high acid value, water-soluble polymers include polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, modified starch, polyvinylpyrrolidone Polyacrylic acid and salts thereof, carboxyl group-containing polyethylene wax, carboxyl group-containing polypropylene wax, carboxyl group-containing polyethylene-propylene wax, and other acid-modified polyolefin waxes having a number average molecular weight of usually 5000 or less and salts thereof, acrylic acid-anhydride Maleic acid copolymer and salt thereof, styrene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid copolymer, isobutylene-maleic anhydride A carboxyl group-containing polymer having an unsaturated carboxylic acid content of 10% by mass or more, such as an acid alternating copolymer, a (meth) acrylic acid- (meth) acrylic acid ester copolymer, and a salt thereof, polyitaconic acid and a salt thereof, amino Examples thereof include water-soluble acrylic copolymers having a group, gelatin, gum arabic, and casein, and compounds generally used as fine particle dispersion stabilizers.

Next, the manufacturing method of the aqueous dispersion which is the adhesive agent of this invention is demonstrated.
As a method for producing an aqueous dispersion of an acid-modified polypropylene resin, for example, an acid-modified polypropylene resin and an aqueous medium (containing an organic solvent or a basic compound as necessary) are heated in a sealable container. A method of stirring is known. However, in the acid-modified polypropylene resin in the present invention, the polypropylene component is a homopolypropylene having an isotactic structure, so that the crystallinity is high and the melting point is high, and chemicals such as acids, alkalis, organic solvents, and water are used. Therefore, it is difficult to disperse in water. In particular, it was more difficult to make the weight average particle diameter of the aqueous dispersion obtained within a preferable range. Therefore, in this invention, it is preferable to employ | adopt the manufacturing method mentioned later among such methods. Below, the preferable manufacturing method in this invention is demonstrated concretely.

  As an apparatus used for aqueous dispersion, a container used as a solid / liquid stirring apparatus or an emulsifier can be used, and an apparatus capable of pressurization of 0.1 MPa or more is preferably used. The stirring method and the rotation speed of stirring are not particularly limited, but may be stirring at a low speed such that the acid-modified polypropylene resin is in a floating state in an aqueous medium. Therefore, high-speed stirring (for example, 1000 rpm or more) and use of a homogenizer are not essential, and an aqueous dispersion can be produced with a simple apparatus.

Raw materials such as an acid-modified polypropylene resin, a basic compound, an organic solvent, and water are added to the above apparatus, and the mixture is preferably stirred and mixed at a temperature of 40 ° C. or lower. Next, stirring is continued until coarse particles disappear, preferably while maintaining the temperature in the tank at 80 to 240 ° C., preferably 100 to 220 ° C., more preferably 110 to 200 ° C., particularly preferably 100 to 190 ° C. (For example, 5 to 300 minutes).
In the above process, when the temperature in the tank is less than 80 ° C., the aqueous dispersion of the acid-modified polypropylene resin is difficult to proceed. On the other hand, when the temperature in the tank exceeds 240 ° C., the acid-modified isotactic polypropylene resin May reduce the molecular weight.

Through the steps so far, the acid-modified polypropylene resin is approximately dispersed in the aqueous medium. However, in the present invention, in order to make the dispersion of the acid-modified polypropylene resin better, and to make the number average particle diameter of the acid-modified polypropylene resin within a preferable range specified in the present invention, then further into the system, It is preferable to add at least one selected from a basic compound, an organic solvent, and water, and again heat (re-heat up) and stir in a sealed container at a temperature of 100 to 240 ° C. In this way, by adding what constitutes the aqueous medium, and heating and stirring again, the number-average particle size and particle size distribution of the acid-modified polypropylene resin in the aqueous dispersion are adjusted to a preferable range. be able to.
In the reheating step, when the temperature in the tank is less than 100 ° C., aqueous dispersion of the acid-modified polypropylene resin is difficult to proceed. On the other hand, when the temperature in the tank exceeds 240 ° C., the acid-modified polypropylene resin May reduce the molecular weight.
The method of adding the basic compound, the organic solvent, and water is not particularly limited. However, the method of adding the product under pressure using a gear pump or the like, the method of adding the product after the system temperature is lowered to normal pressure, etc. There is.
What is necessary is just to determine suitably the ratio of the basic compound to mix | blend, the organic solvent, and water according to the solid content density | concentration, particle diameter, dispersion degree, etc. which are desired. The total amount of the basic compound, organic solvent, and water is preferably adjusted so that the solid content concentration after blending is 1 to 50% by mass, more preferably 2 to 45% by mass. An amount of 40% by weight is particularly preferred.

When the above organic solvent is used during the production of the aqueous dispersion, after the aqueous dispersion, part or all of the organic solvent is distilled out of the system by a solvent removal process generally called “stripping”. The content of may be reduced. It is preferable from the viewpoint of the stability of the aqueous dispersion that the content of the organic solvent in the aqueous dispersion is 50% by mass or less by stripping.
In the stripping step, substantially all of the organic solvent used for the aqueous dispersion can be distilled off. However, in order to distill off substantially all of the organic solvent, it is necessary to increase the degree of decompression of the apparatus or lengthen the operation time, and considering the productivity, the lower limit of the organic solvent content is 0.01 mass. % Is preferred.
Examples of the stripping method include a method in which the aqueous dispersion is heated with stirring at normal pressure or reduced pressure to distill off the organic solvent. In addition, since the solid content concentration is increased by distilling off the aqueous medium, for example, when the viscosity increases and the workability decreases, water is added to the aqueous dispersion in advance. Also good.

  The solid content concentration of the aqueous dispersion can be adjusted by distilling off the organic solvent by such stripping or diluting with an aqueous medium.

  By the above method, the acid-modified polypropylene resin can be dispersed in an aqueous medium with little or no undispersed resin remaining. However, a filtration step may be provided when removing the aqueous dispersion from the apparatus in order to remove foreign substances in the container and a small amount of undispersed resin. Although the filtration method is not limited, For example, the method of carrying out pressure filtration (for example, air pressure 0.5MPa) with a 300 mesh stainless steel filter (wire diameter 0.035mm, plain weave) is mentioned. By providing such a filtration step, it is possible to remove foreign matter and undispersed resin even if they exist, so the obtained aqueous dispersion can be used without any problem as an anchor coating agent for polypropylene resin extrusion lamination. Can do.

  In order to further improve the performance, the adhesive for injection molding of the present invention may further contain a polyurethane resin and / or a crosslinking agent.

  As the polyurethane resin, a polymer containing a urethane bond in the main chain can be used. For example, a polymer obtained by a reaction between a polyol compound and a polyisocyanate compound can be used.

  In the present invention, the polyol component constituting the polyurethane resin is not particularly limited. For example, water, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,2- Propanediol, 1,3-propanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, methyl-1,5-pentanediol, 1,8-octanediol, 2-ethyl-1 , 3-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol and other low molecular weight glycols, trimethylolpropane, glycerin, pentaerythritol and other low molecular weight polyols, ethylene oxide and propylene oxide units Polyol compounds, polyether diols, high molecular weight diols such as polyester diols, bisphenols such as bisphenol A, bisphenol F, dimer diol, and the like to the carboxyl group of the dimer acid was converted to hydroxyl groups.

  As the polyisocyanate component, one or a mixture of two or more known diisocyanates belonging to aromatic, aliphatic or alicyclic groups can be used. Specific examples of diisocyanates include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, dimethyl diisocyanate, lysine diisocyanate. , Hydrogenated 4,4′-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, dimerized isocyanate obtained by converting a carboxyl group of dimer acid into an isocyanate group, and adducts, biurets, and isocyanurates. As the diisocyanates, trifunctional or higher functional polyisocyanates such as triphenylmethane triisocyanate and polymethylene polyphenyl isocyanate may be used.

  In the present invention, commercially available water-based polyurethane resins include Takelac series (product numbers: W-615, W-6010, W-511, etc.) manufactured by Mitsui Chemicals, and Adekabon titer series (product number: HUX, manufactured by Adeka). -232, HUX-320, HUX-380, HUX-401, etc.), Superflex series (part numbers: 500, 550, 610, 650, etc.) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Hydran manufactured by Dainippon Ink & Chemicals, Inc. Series (product number: HW-311, HW-350, HW-150, etc.) can be mentioned.

As the crosslinking agent used in the present invention, a crosslinking agent having a self-crosslinking property, a compound having a plurality of functional groups that react with an unsaturated carboxylic acid component in the molecule, a metal having a polyvalent coordination site, or the like may be used. it can.
Specific examples include oxazoline group-containing compounds, carbodiimide group-containing compounds, isocyanate group-containing compounds, melamine compounds, urea compounds, epoxy compounds, zirconium salt compounds, silane coupling agents, etc. A mixture may be used. Among these, from the viewpoint of easy handling and adhesion, it is preferable to add a compound containing an oxazoline group and / or a compound containing an epoxy group and / or a silane coupling agent.

  As the oxazoline group-containing compound, compounds having two or more oxazoline groups in the molecule can be preferably used. For example, 2,2'-bis (2-oxazoline), 2,2'-ethylene-bis (4,4'-dimethyl-2-oxazoline), 2,2'-p-phenylene-bis (2-oxazoline) , A compound having an oxazoline group such as bis (2-oxazolinylcyclohexane) sulfide, an oxazoline group-containing polymer, and the like. These 1 type (s) or 2 or more types can be used. Among these, an oxazoline group-containing polymer is preferable because it is easy to handle.

  The oxazoline group-containing polymer is generally obtained by polymerizing an addition polymerizable oxazoline such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline. The oxazoline group-containing polymer may be copolymerized with other monomers as necessary. The polymerization method of the oxazoline group-containing polymer is not particularly limited, and a known polymerization method can be employed. Examples of commercially available oxazoline group-containing polymers include Nippon Shokubai Epocross series. Specific product names include, for example, water-soluble type “WS-500”, “WS-700”; emulsion type “K-1010E”, “K-1020E”, “K-1030E”, “K-” 2010E "," K-2020E "," K-2030E "and the like.

The epoxy group-containing compound is not particularly limited as long as it has at least two epoxy groups in the molecule. For example, bisphenol A diglycidyl ether, bisphenol A β-dimethyl glycidyl ether, bisphenol F diglycidyl ether, tetrahydroxyphenylmethane tetraglycidyl ether, resorcinol diglycidyl ether, brominated bisphenol A diglycidyl ether, chlorinated bisphenol A diglycidyl ether, Glycidyl ether types such as hydrogenated bisphenol A diglycidyl ether, diglycidyl ether of bisphenol A alkylene oxide adduct, novolac glycidyl ether, polyalkylene glycol diglycidyl ether, glycerin triglycidyl ether, pentaerythritol diglycidyl ether, epoxy urethane resin; p-Oxybenzoic acid glycidyl ether Glycidyl ether / ester type such as terephthalic acid; glycidyl ester type such as phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, acrylic acid diglycidyl ester, dimer acid diglycidyl ester; glycidyl aniline , Glycidylamine types such as tetraglycidyldiaminodiphenylmethane, triglycidylisocyanurate, triglycidylaminophenol; linear aliphatic epoxy resins such as epoxidized polybutadiene and epoxidized soybean oil; 3,4-epoxy-6methylcyclohexylmethyl-3 , 4-Epoxy-6methylcyclohexanecarboxylate, 3,4-epoxycyclohexylmethyl (3,4-epoxycyclohexane) carboxylate, bis (3 , 4-epoxy-6methylcyclohexylmethyl) adipate, vinylcyclohexene diepoxide, dicyclopentadiene oxide, bis (2,3-epoxycyclopentyl) ether, limonene dioxide, and the like. These 1 type (s) or 2 or more types can be used.
Examples of commercially available epoxy compounds include water-based compounds suitable for the present invention, such as Denasel series (EM-150, EM-101, etc.) manufactured by Nagase Chemtech, Adeka Resin series manufactured by Asahi Denka Kogyo Co., Ltd. Adeka Resins EM-0517, EM-0526, EM-11-50B, and EM-051R manufactured by Asahi Denka Co., Ltd., which are polyfunctional epoxy resin emulsions, are preferable from the viewpoint of improving UV ink adhesion and scratch resistance.

  As the silane coupling agent, known ones can be used. Specifically, for example, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ- Amino group-containing silane coupling agents such as aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane; γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxy Glycidoxy group (or epoxy group) -containing silane coupling agent such as silane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxymethyldimethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane; vinyl Trimethoxysilane, vinyl triethoxy Vinyl group-containing silane coupling agents such as silane and vinyltris (β-methoxyethoxy) silane; methacryloxy group-containing silane coupling agents such as γ-methacryloxypropyltrimethoxysilane; γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyl Examples include mercapto group-containing silane coupling agents such as methyldimethoxysilane; halogen group-containing silane coupling agents such as γ-chloropropylmethoxysilane and γ-chloropropyltrimethoxysilane. These silane coupling agents may be used alone or in combination of two or more. Among these, an amino group-containing silane coupling agent and a glycidoxy group (or epoxy group) -containing silane coupling agent are preferable in that the joint strength of the overall metal plate composite resin molded article finally obtained is good.

  The adhesive layer in the present invention may contain either a polyurethane resin or a crosslinking agent, or both.

  In the adhesive layer, when a polyurethane resin is used without using a crosslinking agent, the content thereof is preferably 1 to 300 parts by mass, more preferably 1 to 150 parts by mass, and more preferably 100 parts by mass of the polyolefin resin. Preferably it is 2-130 mass parts, Most preferably, it is 3-100 mass parts. When the content of the polyurethane resin is less than 1 part by mass, the adhesion between the base material layer and the adhesive layer becomes insufficient, making it difficult to obtain sufficient adhesion and heat resistance as a laminate. On the other hand, when it exceeds 300 parts by mass, the adhesion between the polypropylene layer and the adhesive layer becomes insufficient, and it is difficult to obtain sufficient adhesion and heat resistance as a laminate.

  In a contact bonding layer, when using a crosslinking agent without using polyurethane resin, it is preferable that the content is 0.1-50 mass parts with respect to 100 mass parts of polyolefin resin, More preferably, it is 0.5-40. Part by mass, more preferably 1 to 30 parts by mass. If the content of the cross-linking agent is less than 0.1 parts by mass, since the cross-linking is insufficient, the adhesion between the base material layer and the adhesive layer is inferior, making it difficult to obtain sufficient adhesion and heat resistance as a laminate. . On the other hand, when it exceeds 50 parts by mass, the adhesion between the polypropylene layer and the adhesive layer becomes insufficient, and it is difficult to obtain sufficient adhesion and heat resistance as a laminate.

  When both the polyurethane resin and the crosslinking agent are included in the adhesive layer, the crosslinking agent is used in a range of 50 parts by mass or less and 300 parts by mass or less of the polyurethane resin with respect to 100 parts by mass of the polyolefin resin. It is preferable to contain 1 part by mass or more. When any component is less than 0.1 part by mass, the adhesion between the base material layer and the adhesive layer becomes insufficient, and it is difficult to obtain sufficient adhesion and heat resistance as a laminate. On the other hand, if any one of the components exceeds the above range, the adhesion between the sealant layer and the adhesive layer becomes insufficient, and it is difficult to obtain sufficient adhesion and heat resistance as a laminate.

  Further, the adhesive of the present invention may contain a small amount of a polymer other than the above in order to further improve the performance depending on the purpose.

  Examples of other resins added to the adhesive of the present invention include polyethylene resin, polyester resin, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, and ethylene- (meth) acrylic acid. Copolymer, ethylene- (meth) acrylic ester-maleic anhydride copolymer, styrene-maleic acid resin, styrene-butadiene resin, butadiene resin, acrylonitrile-butadiene resin, poly (meth) acrylonitrile resin, (meth) acrylamide Examples thereof include resins, chlorinated polyethylene resins, chlorinated polypropylene resins, modified nylon resins, rosin-based and terpene-based tackifier resins, phenol resins, silicone resins, epoxy resins, and the like. You may mix and use several things as needed.

  The polyethylene resin preferably added to the adhesive of the present invention is more preferably an acid-modified polyethylene resin, and particularly preferably an acid-modified polyethylene resin having an unsaturated carboxylic acid content of 1 to 5% by mass. . Specific examples of the acid-modified polyethylene resin include an ethylene- (meth) acrylic acid ester-maleic anhydride copolymer having an unsaturated carboxylic acid content of 1 to 5% by mass.

  The polyester resin preferably added to the adhesive of the present invention is a polymer mainly composed of a polybasic acid component and a polyhydric alcohol component. The polyester resin may be copolymerized with monocarboxylic acid, monoalcohol, or hydroxycarboxylic acid.

  These additives may be used alone or in combination of two or more. Moreover, it is preferable to use a water-soluble or water-dispersible additive from the viewpoint of easy addition and mixing.

  An adhesive film can be formed by applying the adhesive of the present invention to a metal plate and drying and removing the aqueous medium in the adhesive.

As the metal plate, a cold-rolled steel plate, a hot-dip galvanized steel plate (GI), an alloyed hot-dip Zn-Fe-plated steel plate (GA), an alloyed hot-dip Zn-5% Al-plated steel plate (GF), an electro-pure galvanized steel plate (EG), an electric Zn—Ni plated steel plate, an aluminum plate, an aluminum alloy plate, a titanium plate, a galvalume steel plate and the like. The thickness of the metal substrate can be appropriately selected according to the application and is not particularly limited, but is preferably about 0.3 to 5.0 mm for reducing the weight of the final product.
The surface of the metal plate may be subjected to treatment for improving adhesion or other purposes, such as chemical treatment such as cleaning treatment, polishing treatment, laser treatment, chromate treatment, electrochemical treatment, plasma treatment, etc. Gas treatment, primer treatment, etc. can be performed.

  The method of applying the adhesive of the present invention can be appropriately selected depending on the shape of the metal plate, and is not particularly limited, but is a known method such as spray coating, dip coating, brush coating, wire bar coating, curtain flow coating, gravure. Roll coating, reverse roll coating, air knife coating, etc. can be employed.

The coating amount of the adhesive of the present invention is appropriately selected depending on the application, and is preferably 1 to 100 μm, more preferably 3 to 70 μm, and more preferably 5 to 50 μm as a dry film thickness (adhesive coating). Is more preferable.
In addition, in order to obtain a uniform adhesive film, it is preferable to use a paint whose concentration and viscosity are adjusted according to the device and use conditions, in addition to appropriately selecting the device used for coating and the use conditions thereof. .

As a heating device used when drying after applying the adhesive of the present invention, a normal hot air circulation type oven, an infrared heater or the like can be used.
The heating temperature and the heating time are appropriately selected depending on the characteristics of the base material that is an object to be coated and the addition amount of the various materials described above that can be arbitrarily blended in the adhesive. As heating temperature, it is preferable that it is 50-250 degreeC, It is more preferable that it is 80-200 degreeC, It is further more preferable that it is 100-180 degreeC.
On the other hand, the heating time is preferably 5 seconds to 180 minutes, more preferably 30 seconds to 120 minutes, and further preferably 1 minute to 60 minutes. In addition, when a crosslinking agent is included as an additive, the heating temperature and time are appropriately selected depending on the type of the crosslinking agent in order to sufficiently advance the reaction between the carboxyl group of the acid-modified polypropylene resin or other polymer and the crosslinking agent. It is desirable.

  The metal plate composite resin molded article of the present invention is obtained by laminating a metal plate having the above-mentioned adhesive film and a resin through this adhesive film. Specifically, at least the metal plate / adhesive film / resin is They are stacked in this order.

The metal plate composite resin molded article of the present invention is preferably produced by an injection molding method such as in-mold molding or insert molding.
As a manufacturing method of the metal plate composite resin molded product of the present invention, for example, a metal plate on which an adhesive coating of the present invention has been applied and dried to form an adhesive coating is processed in advance into a desired shape. Thereafter, the metal plate is inserted into the mold of the injection molding machine, the mold is clamped, the molten resin is injected into the mold, and the resin is cooled and solidified to obtain the metal plate composite resin molded product of the present invention. be able to. The metal plate having an adhesive coating made of the injection molding adhesive of the present invention does not exclude the composite with the resin by the press molding method, but in terms of mass production of the metal plate composite resin molded product, It is preferable to employ a highly efficient injection molding (in-mold molding or insert molding) method.

  The injection molding conditions may be appropriately changed according to the type of resin constituting the molded product. For example, when the resin for the molded product is polypropylene, the cylinder temperature is 230 to 250 ° C. and the mold temperature is 45 to 55 ° C. The injection holding time can be 5 to 8 seconds and the cooling time can be about 20 to 30 seconds. When the resin for the molded product is nylon 6, the cylinder temperature is 240 to 250 ° C. and the mold temperature is 70 to 80. C., the injection holding time can be 5 to 8 seconds, and the cooling time can be about 20 to 30 seconds. When injection molding is performed under these conditions, a metal plate composite resin molded article in which the metal plate on which the adhesive film obtained from the adhesive of the present invention is formed and the resin are firmly bonded is obtained.

  Any known resin can be used as the resin for the molded article, and is not particularly limited. Among them, the adhesive of the present invention is particularly excellent in adhesiveness with a polypropylene resin. In order to increase the strength as a molded product, reinforcing fibers such as glass fibers and carbon fibers may be added to the resin for molded products in an amount of about 5 to 60% by mass. Moreover, you may add well-known additives, such as various pigments and dyes, a flame retardant, an antibacterial agent, antioxidant, a plasticizer, and a lubricant.

The adhesive strength of the metal / resin joint of the metal plate composite resin molded article is preferably 6 MPa or more, and particularly preferably 10 MPa or more. If the adhesiveness is 6 MPa or more, sufficient performance can be exhibited in various applications where the use of the adhesive of the present invention is assumed.
The adhesive strength can be evaluated by a known method, and as an example, it can be evaluated by measuring tensile shear stress with a tensile tester.

  Hereinafter, the present invention will be described specifically by way of examples. However, the present invention is not limited by these.

1. Characteristics of acid-modified polypropylene resin (1) Composition of acid-modified polypropylene resin, stereoregularity manufactured by Varian, GEMINI 2000/300 nuclear magnetic resonance apparatus (magnetic field intensity 7.05 T), composition ¹ HNMR, stereoregularity ¹³ C NMR measurement was performed and determined. The former was measured at 120 ° C. using tetrachloroethane (d ₂ ) and the latter using orthodichlorobenzene as a measurement solvent.
(2) Melt flow rate (MFR) of acid-modified polypropylene resin
According to the method described in JIS K7210: 1999, the measurement was performed at 180 ° C. under a load of 2160 g.
(3) Melting | fusing point of acid-modified polypropylene resin It measured by DSC method using DSC7 by Perkin Elmer.

2. Characteristics of Acid-modified Polypropylene Resin Aqueous Dispersion (1) Number average particle size of dispersed particles in aqueous dispersion Microtrac particle size distribution analyzer (manufactured by Nikkiso Co., Ltd., UPA150, MODEL No. 9340, dynamic light scattering method) Asked. The refractive index of the resin used for particle diameter calculation was 1.50.

3. Adhesiveness of metal plate composite resin molded product (1) Tensile test (20 ° C)
Using a tensile tester (precision universal material testing machine 2020, manufactured by Intesco), a test piece of a metal plate / resin molded product prepared in each example and comparative example was used, and the tensile speed was 100 mm in an atmosphere of 20 ° C. and 65% RH. The adhesion at the interface of the metal plate / resin molded product was measured by a tensile shear test under the conditions of / min. The measurement was performed with 15 samples, and the average value was defined as the adhesive strength. Moreover, the standard deviation of the adhesive strength at that time was calculated.
The adhesive strength and standard deviation were evaluated according to the following criteria.
[Adhesive strength]
◎: 10 MPa or more ○: 6 MPa or more, less than 10 MPa x: less than 6 MPa
[ standard deviation ]
○: Less than 1.5 MPa Δ: 1.5 MPa or more, less than 2 MPa x: 2 MPa or more

(2) Tensile test (80 ° C)
The tensile shear test was performed by changing the temperature during measurement from 20 ° C. to 80 ° C. in the same manner as in (1) above. Further, the adhesive strength was evaluated according to the same criteria.

(3) Tensile test (after wet heat test)
After the specimens of the metal plate / resin molded product prepared in each Example and Comparative Example were treated for 500 hours in a constant temperature and humidity apparatus at 85 ° C./85% RH, tensile shear was performed in the same manner as in (1) above. A test was conducted. Further, the adhesive strength was evaluated according to the same criteria.

(Production of acid-modified polypropylene resin)
Production Example 1 (Production of acid-modified polypropylene resin “P-1”)
To 100 parts by mass of isotactic homopolypropylene resin (MFR = 2 g / 10 min, 180 ° C., 2160 g load), 5.5 parts by mass of maleic anhydride and 1.0 part by mass of di-t-butyl peroxide, The reaction was carried out 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 with a vacuum dryer to obtain an acid-modified polypropylene resin “P-1”.

Production Example 2 (Production of acid-modified polypropylene resin “P-2”)
In Production Example 1, the addition amount of maleic anhydride was changed to 5.5 parts by mass to 6.0 parts by mass, and the addition amount of di-t-butyl peroxide was changed from 1.0 to 1.5 parts by mass. An acid-modified polypropylene resin “P-2” was obtained by carrying out the same operation except that.

Production Example 3 (Production of acid-modified polypropylene resin “P-3”)
In Production Example 1, the amount of maleic anhydride added was changed to 5.5 parts by mass to 3.8 parts by mass, and the amount of di-t-butyl peroxide added was changed from 1.0 parts by mass to 0.8 parts by mass. The acid-modified polypropylene resin “P-3” was obtained by carrying out the same operation except that.

Production Example 4 (Production of acid-modified polypropylene resin “P-4”)
In Production Example 1, the amount of maleic anhydride added was changed to 5.5 parts by mass to 2.8 parts by mass, and the amount of di-t-butyl peroxide added was changed from 1.0 parts by mass to 0.5 parts by mass. An acid-modified polypropylene resin “P-4” was obtained by carrying out the same operation except that.

Production Example 5 (Production of acid-modified polypropylene resin “P-5”)
In Production Example 1, the addition amount of maleic anhydride was changed to 5.5 parts by mass to 6.0 parts by mass, and the addition amount of di-t-butyl peroxide was changed from 1.0 to 1.8 parts by mass. An acid-modified polypropylene resin “P-5” was obtained by carrying out the same operation except that.

Production Example 6 (Production of acid-modified polypropylene resin “P-6”)
In Production Example 1, the same operation was performed except that a homopolypropylene resin having a syndiotactic structure (MFR = 5 g / 10 min, 180 ° C., 2160 g load) was used as the homopolypropylene resin, whereby the acid-modified polypropylene resin “P -6 "was obtained.

Production Example 7 (Production of acid-modified polypropylene resin “P-7”)
The same as in Production Example 1 except that random polypropylene (propylene / ethylene = 96/4 (mass ratio), MFR = 10 g / 10 min, 180 ° C., 2160 g load) was used instead of the homopolypropylene resin having an isotactic structure. The acid-modified polypropylene resin “P-7” was obtained by performing the above operations.

Production Example 8 (Production of acid-modified polypropylene resin “P-8”)
In Production Example 1, a random polypropylene (propylene / ethylene / butene = 89/5/6 (mass ratio), MFR = 10 g / 10 min, 180 ° C., 2160 g load) is used instead of the isotactic homopolypropylene resin. The acid-modified polypropylene resin “P-8” was obtained by carrying out the same operation except that.

  Table 1 shows the properties of the acid-modified polypropylene resins obtained in Production Examples 1-8.

(Preparation of acid-modified polypropylene resin aqueous dispersion)
Preparation Example 1 (Preparation of acid-modified polypropylene resin aqueous dispersion “E-1”)
75.0 g of acid-modified polypropylene resin “P-1”, 30.0 g of isopropanol, 170.0 g of tetrahydrofuran, 15.0 g of triethylamine using a stirrer equipped with a 1 L glass container that can be sealed with a heater. When 210.0 g of distilled water was charged into a glass container and stirred at a rotation speed of the stirring blade of 300 rpm, no resin precipitation was observed at the bottom of the container, confirming that it was in a floating state. Therefore, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the system temperature was maintained at 150 ° C. and the mixture was further stirred for 60 minutes, and then the heater was turned off and naturally cooled.
When the internal temperature was cooled to 80 ° C., the container was opened, and a raw material consisting of 60.0 g of tetrahydrofuran, 10.0 g of dimethylaminoethanol and 50.0 g of distilled water was additionally charged. Thereafter, the vessel was sealed, the heater was turned on, and the stirring blade was heated again (heated again) at a rotation speed of 300 rpm. After the system temperature was maintained at 140 ° C. and stirring was continued for 60 minutes, the output of the heater was adjusted so that the internal temperature was 80 ° C.
When the internal temperature decreased to 80 ° C., the system was gradually decompressed using a vacuum pump to remove isopropanol, tetrahydrofuran and water. After removing 400 g or more of tetrahydrofuran, isopropanol and water, the heater was turned off and when the system temperature reached 35 ° C., water was added and the concentration of “P-1” in the aqueous dispersion was 20% by mass. And pressure filtration with a 180 mesh stainless steel filter to obtain a uniform acid-modified polypropylene resin aqueous dispersion “E-1”. In addition, after pressure filtration, the undispersed resin was not confirmed on the filter.

Preparation Examples 2, 3, 6-9 (Preparation of acid-modified polypropylene resin aqueous dispersion “E-2, 3, 6-9”)
As an unsaturated carboxylic acid-modified polypropylene resin, instead of P-1, P-2 in Preparation Example 2 (E-2), P-3 in Preparation Example 3 (E-3), P in Preparation Example 6 (E-6) Preparation Example 1 except that P-5 was used in Preparation Example 7 (E-7), P-7 in Preparation Example 8 (E-8), and P-8 in Preparation Example 9 (E-9). In the same manner, acid-modified polypropylene resin aqueous dispersions “E-2, 3, 6-9” were obtained.

Adjustment example 5
Adjustment Example 5 (E-5) was carried out in the same manner as Adjustment Example 1 except that P-4 was used instead of P-1 as the unsaturated carboxylic acid-modified polypropylene resin, but the filter after pressure filtration Undispersed resin was observed on the top, and a stable dispersion could not be obtained.

Preparation Example 4 (Preparation of acid-modified polypropylene resin aqueous dispersion “E-4”)
An acid-modified polypropylene resin aqueous dispersion “E-4” was obtained in the same manner as in Preparation Example 3, except that dimethylaminoethanol was used instead of triethylamine.

Preparation Example 10 (Preparation of acid-modified polypropylene resin aqueous dispersion “E-10”)
25.0 g of acid-modified polypropylene resin “P-1” was added to 100 g of toluene and heated with stirring to be dissolved uniformly. On the other hand, in another container, 2.0 g of polyoxyalkyl surfactant was added to 100 g of water and dissolved. The toluene solution of the acid-modified polypropylene resin and the aqueous solution of the surfactant were stirred. Furthermore, after adding DMEA and adjusting pH, toluene was distilled off with the rotary evaporator and acid-modified polypropylene resin aqueous dispersion "E-10" was obtained.

  The properties of the acid-modified polypropylene resin aqueous dispersions obtained in Preparation Examples 1 to 10 are shown in Table 2.

Example 1
The thickness of the resin film after drying the acid-modified polypropylene resin aqueous dispersion “E-1” with a bar coater on the surface of a 1.0 mm thick aluminum alloy plate (chromate treated, acetone degreased) And heated at 120 ° C. for 10 minutes to obtain a metal plate having an adhesive film.
Next, injection molding was performed using an injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd .; NEX-110). The metal plate having the adhesive coating is cut into a size of 100 mm × 25 mm, put into a mold, and a polypropylene resin containing 30% by mass of glass fiber (manufactured by Prime Polymer; Prime Polypro E7000) is melted to be 100 mm × 23 mm × Injection molding was performed to obtain a thickness of 3 mm. The resin and the metal plate were bonded so as to overlap each other at 8 mm length × 23 mm width to obtain a test piece of metal plate / resin molded product. At this time, the injection conditions were a cylinder temperature of 240 ° C., a resin molding temperature of 240 ° C., a mold temperature of 50 ° C., an injection pressure of 50 MPa, an injection holding time of 6.5 seconds, and a cooling time of 25 seconds.

Examples 2-4, Comparative Examples 1-5
In Example 1, the acid-modified polypropylene resin aqueous dispersion was replaced with “E-1”, and “E-2” (Example 2), “E-3” (Example 3), “E-4” (implemented) Example 4), “E-6” (Comparative Example 1), “E-7” (Comparative Example 2), “E-8” (Comparative Example 3), “E-9” (Comparative Example 4), “E A test piece of metal plate / resin molded product was obtained in the same manner except for “−10” (Comparative Example 5).

Examples 5-9
In Example 1, 5 parts by mass (Example 5) of an oxazoline group-containing cross-linking agent in solid content with respect to 100 parts by mass of solid content of “E-1” in the acid-modified polypropylene resin aqueous dispersion, and epoxy group-containing cross-linking 5 parts by mass of solid agent (Example 6), 1 part by mass of silane coupling agent (Example 7), 20 parts by mass of polyurethane resin emulsion (Example 8), containing oxazoline group A test piece of a metal plate / resin molded product was obtained in the same manner except that 2 parts by mass of the cross-linking agent and 20 parts by mass (Example 9) of the polyurethane resin emulsion were added.
Here, Epocros WS-500 (manufactured by Nippon Shokubai Co., Ltd., solid concentration 39% by mass) as the oxazoline group-containing crosslinking agent, and Adeka Resin EM-0517 (manufactured by Adeka Corp., solid content concentration 51% by mass) as the epoxy group-containing crosslinking agent. ), KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd., active ingredient 100%) was used as the silane coupling agent, and Takelac W-6010 (manufactured by Mitsui Chemicals, solid content concentration 30% by mass) was used as the urethane resin emulsion.

Comparative Examples 6-10
In Comparative Examples 1 to 5, 2 parts by mass of the oxazoline group-containing crosslinking agent and 20 parts by mass of the polyurethane resin emulsion were added to 100 parts by mass of the solid content of the acid-modified polypropylene resin aqueous dispersion, respectively. A test piece of metal plate / resin molded product was obtained in the same manner as described above.

  Table 3 shows the test results using the metal plate / resin molded product test pieces obtained in Examples 1 to 9 and Comparative Examples 1 to 10.

  Examples 1-4 are adhesives for injection molding composed of an acid-modified polypropylene resin aqueous dispersion containing an acid-modified polypropylene resin and an aqueous medium whose homopolypropylene has a polypropylene component having an isotactic structure, and a metal plate / It had characteristics suitable for an adhesive for bonding resin molded products. Moreover, in Examples 5-9, adhesiveness, adhesiveness under high temperature, and heat-and-moisture resistance were improving by including a urethane resin and / or a crosslinking agent component in the acid-modified polypropylene resin aqueous dispersion. Although the acid-modified polypropylene resin aqueous dispersion of Example 4 had sufficient adhesiveness, the particle diameter was slightly large, and thus the adhesiveness slightly varied.

On the other hand, when the structure and composition of the polypropylene resin are out of the scope of the present invention (Comparative Examples 1 to 4 and 6 to 9), the adhesiveness and wet heat resistance at high temperatures (80 ° C.) were inferior. In particular, when the polypropylene resin is other than homopolypropylene (Comparative Examples 3, 4, 8, and 9), the adhesiveness at room temperature is inferior, and the structure of the polypropylene resin is not an isotactic structure (Comparative Examples 2 and 7). ), A large variation in adhesiveness was observed.
Furthermore, when the acid-modified polyolefin resin aqueous dispersion containing an emulsifier was used (Comparative Examples 5 and 12), the heat-and-moisture resistance was poor.
When an acid-modified polyolefin resin having a modification rate with an unsaturated carboxylic acid outside the range specified in the present invention was used (“E-5”), the dispersion did not substantially proceed and an aqueous dispersion could not be obtained. .

Claims (9)

  An adhesive for injection molding in which an acid-modified polypropylene resin is dispersed in an aqueous medium. The acid-modified polypropylene resin contains 1.5 to 10.0% by mass of an unsaturated carboxylic acid, and the polypropylene component is isotactic. An adhesive for injection molding having a tic structure and having an MFR (melt flow rate) value at 180 ° C. under a load of 2160 g of 400 g / 10 min or less.   The adhesive for injection molding according to claim 1, wherein the adhesive is substantially free of non-volatile water-based auxiliary.   The adhesive for injection molding according to claim 1 or 2, wherein the weight average molecular weight in the aqueous dispersion is 0.15 µm or less.   The adhesive for injection molding according to any one of claims 1 to 3, further comprising a urethane resin and / or a crosslinking agent component.   The adhesive film formed by removing the aqueous medium of the adhesive for injection molding in any one of Claims 1-4.   A metal plate having the adhesive coating according to claim 5.   A metal plate composite resin molded product in which the metal plate according to claim 6 and a resin are laminated via an adhesive film.   The metal plate composite resin molded article according to claim 7, wherein the resin is a polypropylene resin. After the metal plate according to claim 6 is inserted into the mold, the resin is laminated on the metal plate through an adhesive film of the metal plate by injecting molten resin into the mold. Manufacturing method of metal plate composite resin molded product.