TWI873276B - Polyolefin adhesive composition - Google Patents

Abstract

The subject of the present invention is to provide an adhesive composition that exhibits good adhesion between a polyolefin resin substrate and other heterogeneous materials and can be bonded at low temperature. An adhesive composition contains an acid-modified polyolefin (A), a diene polymer (B) and a tackifier (C).

Description

Polyolefin adhesive composition

The present invention relates to an adhesive composition and a laminate.

Polyolefin resins such as polypropylene and polyethylene are inexpensive and have many excellent properties such as moldability, chemical resistance, water resistance, and electrical properties. Therefore, they have been widely used in the form of sheets, films, and molded products in recent years. However, unlike polar substrates such as polyurethane resins, polyamide resins, acrylic resins, and polyester resins, substrates composed of these polyolefin resins (hereinafter referred to as polyolefin substrates) are non-polar and crystalline, so they have the disadvantage of being difficult to paint and bond. Recently, there is a growing demand for excellent adhesion between polyolefin substrates, not only between polyolefin substrates, but also between polar plastic substrates such as vinyl chloride (PVC) and polyester, and different materials such as metals. As the main component of the adhesive between the polyolefin resin substrate and the heterogeneous materials, some proposals have been made: using a thermoplastic copolymer linear polymer as the base resin, composed of a modified polyolefin resin and a binder (Patent Document 1); composed of a modified polyolefin, an aliphatic polyester resin, an olefin resin and a binder (Patent Document 2); composed of a modified polyolefin, a thermoplastic resin and a binder (Patent Document 3), etc. [Prior Art Documents] [Patent Documents]

[Patent Document 1] Japanese Patent Application No. 2004-292716 [Patent Document 2] Japanese Patent Application No. 2014-234400 [Patent Document 3] Japanese Patent Application No. 2016-89060

[The problem that the invention wants to solve]

However, although the adhesive compositions proposed above have good adhesion between polyolefin resin substrates and metal (aluminum) and between polyolefin resin substrates and polyester (PET) substrates, the adhesion between substrates other than aluminum or PET and polyolefin resin substrates is still unclear. In addition, all of them are hot-melt adhesives and need to be bonded at high temperatures such as 180°C. The present invention provides an adhesive composition that exhibits good adhesion between polyolefin resin substrates and polar plastic substrates and metal substrates other than polyolefin resin substrates, and can be bonded at low temperatures. [Means for Solving the Problem]

In order to achieve the above-mentioned problem, the inventors of the present case have conducted intensive research and found that a specific combination of modified polyolefin, diene polymer and binder is effective, and proposed the following invention. That is, the present invention consists of the following components. (1) An adhesive composition comprising an acid-modified polyolefin (A), a diene polymer (B) and a binder (C), wherein the mass ratio of the diene polymer (B) is 1 mass part or more and 100 mass parts or less, and the mass ratio of the binder (C) is 1 mass part or more and 100 mass parts or less, relative to 100 mass parts of the acid-modified polyolefin (A). (2) An adhesive composition as described in (1), wherein the acid value of the acid-modified polyolefin (A) is 2 to 50 mgKOH/g. (3) The adhesive composition as described in (1) or (2), further comprising a solvent (D). (4) The adhesive composition as described in any one of (1) to (3), wherein the solvent (D) comprises an alicyclic hydrocarbon solvent (D1) and an ester solvent or a ketone solvent (D2). (5) The adhesive composition as described in any one of (1) to (4), wherein the mass ratio of the alicyclic hydrocarbon solvent (D1) to the ester solvent or the ketone solvent (D2) is (D1)/(D2)=95/5 to 50/50. (6) The adhesive composition as described in any one of (1) to (5), comprising a hardener (E). (7) An adhesive composition as described in any one of (1) to (6) is used for bonding a polyolefin resin substrate 1 and a substrate 2 different from the substrate 1. (8) A laminated body, which is a laminated body of a polyolefin resin substrate 1 and a substrate 2 different from the substrate 1 bonded by using an adhesive composition as described in any one of (1) to (6). [Effect of the invention]

The adhesive composition of the present invention contains an acid-modified polyolefin, a diene polymer and an adhesive, and has excellent adhesion to non-polar substrates such as polyolefin, polar substrates such as acrylonitrile-butadiene-styrene copolymer (ABS) and polycarbonate (PC), and other heterogeneous substrates such as metals, and has good elongation. In addition, it can be coated by dry coating, so the equipment cost can be reduced and the film thickness can be made thinner. In addition, even when the heat shrinkage effect of the polyolefin substrate is small, such as a low temperature below 90°C, excellent adhesion can be exhibited.

The adhesive composition of the present invention exhibits good adhesion not only to polyolefin substrates, but also to substrates such as ABS resin, polycarbonate, polyethylene terephthalate (PET), polyvinyl chloride (PVC), acrylic resin, and aluminum, and is therefore useful as an adhesive for multiple substrates.

The following is a detailed description of the embodiments of the present invention.

<Acid-modified polyolefin (A)> The acid-modified polyolefin (A) used in the present invention is not particularly limited, and is preferably obtained by grafting at least one of α,β-unsaturated carboxylic acid and its anhydride onto polypropylene.

As for polypropylene, homopolypropylene is particularly preferable, and propylene-α-olefin copolymer can also be used. Propylene-α-olefin copolymer is a copolymer made of propylene as the main component and α-olefin copolymerized therewith. As α-olefin, for example, one or more of ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate, etc. can be used. Among these α-olefins, ethylene and 1-butene are preferred, and 1-butene is particularly preferred.

The acid-modified polyolefin (A) preferably contains 60 mol% or more of propylene as an olefin component. More preferably, it is 70 mol% or more, and even more preferably, it is 80 mol% or more. Even more preferably, it is 90 mol% or more. The higher the propylene content, the better the adhesion to the polypropylene substrate.

The molar ratio of propylene to 1-butene in the acid-modified polyolefin (A) is preferably propylene/1-butene = 99-60/1-40, more preferably 98-65/2-35, and particularly preferably 90-70/10-30. When the molar ratio of propylene is 60% or more, excellent adhesion to the polyolefin substrate can be exhibited.

For at least one of α,β-unsaturated carboxylic acids and their anhydrides, for example, maleic acid, itaconic acid, liraconic acid and their anhydrides can be cited. Among them, anhydrides are preferred, and maleic anhydride is more preferred. As the acid-modified polyolefin (A), specifically, maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, maleic anhydride-modified propylene-1-butene copolymer, maleic anhydride-modified propylene-ethylene-1-butene copolymer, etc. can be cited. These acid-modified polyolefins can be used alone or in combination of two or more. Among them, maleic anhydride-modified polypropylene is preferred.

The acid value of the acid-modified polyolefin (A) is preferably in the range of 2 to 50 mgKOH/g. It is more preferably in the range of 3 to 40 mgKOH/g, particularly preferably in the range of 5 to 30 mgKOH/g, and particularly preferably in the range of 10 to 20 mgKOH/g. When the acid value is 2 mgKOH/g or more, the molecular weight is high and the elongation of the adhesive layer is well exerted. On the other hand, when the acid value is 50 mgKOH/g or less, the molecular weight becomes low and the solution stability at low temperature tends to be good.

The crystallization degree of the acid-modified polyolefin (A) is preferably in the range of 12 to 70%. It is more preferably in the range of 15 to 60%, and most preferably in the range of 18 to 50%. When it is above the above value, the cohesive force derived from the crystallization becomes strong, and the adhesion to the substrate is excellent. On the other hand, when it is below the above value, the cohesive force derived from the crystallization is moderate, and the adhesion is good.

The heat of fusion of the modified polyolefin (A) is preferably in the range of 25 to 80 J/g. It is more preferably in the range of 28 to 75 J/g, and most preferably in the range of 30 to 70 J/g. When it is above the above value, the cohesive force derived from crystallization becomes strong and the adhesiveness is excellent. On the other hand, when it is below the above value, the cohesive force derived from crystallization is moderate and the adhesiveness is good.

The acid-modified polyolefin (A) may also be chlorinated.

The melting point (Tm) of the acid-modified polyolefin (A) is preferably 50°C or higher and 130°C or lower. It is more preferably 55°C or higher, and particularly preferably 60°C or higher. It is more preferably 125°C or lower, particularly preferably less than 120°C, still more preferably 115°C or lower, and most preferably 110°C or lower. When it is 50°C or higher, the cohesive force derived from crystallization becomes stronger, and the adhesiveness is good. On the other hand, when it is 130°C or lower, the solution stability and fluidity are good, and the workability during bonding is excellent. In addition, the temperature during bonding may also be low.

The heat of fusion of the acid-modified polyolefin (A) is preferably in the range of 20 to 70 J/g. It is more preferably in the range of 25 to 65 J/g, and most preferably in the range of 30 to 60 J/g. When it is 20 J/g or more, the cohesive force derived from crystallization becomes strong, and the adhesiveness is excellent. On the other hand, when it is 70 J/g or less, it has flexibility and can follow the substrate, so the adhesiveness is excellent.

The weight average molecular weight (Mw) of the acid-modified polyolefin (A) is preferably in the range of 10,000 to 200,000. It is more preferably in the range of 20,000 to 180,000, particularly preferably in the range of 30,000 to 160,000, particularly preferably in the range of 35,000 to 140,000, and most preferably in the range of 40,000 to 120,000. When it is 10,000 or more, the cohesion becomes stronger and the adhesion is good. On the other hand, when it is 200,000 or less, the fluidity is high, the workability during bonding is good, and the solution stability at low temperature is good.

The method for producing the acid-modified polyolefin (A) is not particularly limited, and examples thereof include free radical grafting reaction (i.e., a reaction in which free radical species are generated for a polymer serving as a main chain, and unsaturated carboxylic acid and anhydride are grafted onto the free radical species as a polymerization starting point).

The free radical generator is not particularly limited, and an organic peroxide is preferably used. The organic peroxide is not particularly limited, and examples thereof include: di-tert-butyl peroxyphthalate, tert-butyl hydroperoxide, diisopropylbenzene peroxide, benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxytrimethylacetate, methyl ethyl ketone peroxide, di-tert-butyl peroxide, lauryl peroxide and other peroxides; azonitriles such as azobisisobutylonitrile and azobisisopropionitrile, and the like.

These acid-modified polyolefins (A) may be used alone or in combination of two or more.

<Diene polymer (B)> The adhesive composition of the present invention contains a diene polymer (B). By containing a diene polymer, the internal stress after the adhesive is formed into a film can be reduced and the adhesion to the substrate can be improved.

Diene polymers refer to polymers containing diene monomers as constituent units. Diene polymers are not particularly limited, and examples thereof include ethylene-propylene-diene rubber, polybutadiene, isoprene rubber, etc. Moreover, these may also be modified. These may be used alone or in combination of two or more.

The number average molecular weight (Mn) of the diene polymer (B) is preferably 1,000 or more and 100,000 or less. It is more preferably 2,000 or more and 80,000 or less, particularly preferably 3,000 or more and 60,000 or less, particularly preferably 4,000 or more and 50,000 or less, still more preferably 4,500 or more and 40,000 or less, and most preferably 4,800 or more and 20,000 or less. When it is 1,000 or more, the compatibility with the acid-modified polyolefin (A) is moderate, the stress relaxation effect is exhibited, and the adhesiveness tends to be good. When it is 100,000 or less, the compatibility with the acid-modified polyolefin (A) is significantly improved.

The content of the diene polymer (B) is 1 part by mass or more and 100 parts by mass or less relative to 100 parts by mass of the acid-modified polyolefin (A). It is more preferably 2 parts by mass or more and 95 parts by mass or less, particularly preferably 5 parts by mass or more and 90 parts by mass or less, particularly preferably 8 parts by mass or more and 85 parts by mass or less, still more preferably 10 parts by mass or more and 80 parts by mass or less, and most preferably 12 parts by mass or more and 75 parts by mass or less. When it is 1 part by mass or more, a stress relief effect is exhibited and the adhesion tends to be good. When it is 100 parts by mass or less, the cohesion of the coating is moderate and the adhesion is improved.

The shape of the diene polymer (B) is not particularly limited, and it is preferably a semi-solid or liquid at room temperature. It has good compatibility with the acid-modified polyolefin (A) and good solution stability at low temperatures. ＜Binder (C)＞ The adhesive composition of the present invention contains a binder (C). By containing a binder, the adhesive can maintain surface adhesion after the adhesive is formed into a film, and the adhesion to the substrate is better.

The content of the adhesive (C) used in the present invention is 1 part by mass or more and 100 parts by mass or less relative to 100 parts by mass of the acid-modified polyolefin (A). It is more preferably 2 parts by mass or more and 95 parts by mass or less, particularly preferably 5 parts by mass or more and 90 parts by mass or less, particularly preferably 8 parts by mass or more and 85 parts by mass or less, still more preferably 10 parts by mass or more and 80 parts by mass or less, and most preferably 15 parts by mass or more and 75 parts by mass or less. Moreover, if it is 1 part by mass or more, the viscosity of the solution is moderate and the stability of the solution becomes good. On the other hand, if it is 100 parts by mass or less, the adhesion of the surface is moderate and the adhesion is well exerted.

The softening point of the adhesive (C) used in the present invention is preferably above 60°C. It is more preferably above 65°C, and particularly preferably above 70°C. It is also preferably below 150°C, particularly preferably below 138°C, particularly preferably below 135°C, still more preferably below 130°C, and most preferably below 128°C. If the softening point is above 60°C, the adhesive is not easy to seep to the surface at room temperature, and the surface becomes smooth with good adhesion. If the softening point is below 140°C, it produces adhesiveness at room temperature and has good adhesion. These can be used alone or in combination of two or more.

The binder (C) of the present invention can maintain good adhesion and improve compatibility and storage stability by making the binders with different softening points into an appropriate blending ratio. For example, in the present invention, a binder (C1) with a softening point of 110°C to 150°C and a binder (C2) with a softening point of 75°C to less than 110°C can be combined. The binder (C1) is particularly preferably 115°C to 140°C, and the best is 120°C to 130°C. In addition, the binder (C2) is particularly preferably 75°C to 100°C, and the best is 80°C to 95°C. By combining the above two types, bleeding can be prevented and the adhesion can be improved. The mass ratio of (C1) to (C2) is preferably (C1)/(C2) = 90-50/10-50, more preferably 85-60/15-40, and even more preferably 78-65/22-35. When the mass ratio is within the above range, the compatibility and storage stability are good, thereby achieving good adhesion.

The binder (C) used in the present invention includes various materials, for example, petroleum resins (aliphatic, alicyclic, aromatic, etc.), terpene resins (polymers of α-pinene, β-pinene, limonene, etc.), aromatic hydrocarbon-modified terpene resins, rosin resins (gum rosin, tall-oil rosin, wood rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin, maleated rosin, rosin ester, etc.), terpene phenol resins, etc., and rosin resins are particularly preferred. These can be used alone or in combination of two or more.

The binder (C) used in the present invention may also have a hydroxyl group. For example, Pinecrystal KE-359 having a hydroxyl value of 38 to 47 mgKOH/g may be used.

<Solvent (D)> The adhesive composition of the present invention may contain a solvent (D). The solvent (D) is not particularly limited as long as it can dissolve or disperse the acid-modified polyolefin (A), the diene polymer (B) and the binder (C), and is preferably an alicyclic hydrocarbon solvent (D1), an ester solvent or a ketone solvent (D2). For example, the alicyclic hydrocarbon solvent (D1) may include cyclohexane, methylcyclohexane, ethylcyclohexane, etc. The ester solvent or ketone solvent (D2) may include ethyl acetate, propyl acetate, butyl acetate, methyl ethyl ketone, etc. Among them, cyclohexane and butyl acetate are preferred. These may be used alone or in any combination of two or more.

The solvent (D) used in the present invention may be a mixed solvent containing an alicyclic hydrocarbon solvent (D1) and an ester solvent or a ketone solvent (D2). By preparing a mixed solvent of an alicyclic hydrocarbon solvent and an ester solvent or a ketone solvent, the solubility of the adhesive composition can be improved.

When the aforementioned mixed solvent is used, the mass ratio of the alicyclic hydrocarbon solvent (D1) to the ester solvent or ketone solvent (D2) is preferably (D1)/(D2) = 99/1 to 50/50. It is more preferably in the range of 95/5 to 60/40, and particularly preferably in the range of 90/10 to 70/30. If the alicyclic hydrocarbon (D1) is more than the aforementioned range, the viscosity may be high, resulting in uneven coating and reduced adhesion. If the alicyclic hydrocarbon (D1) is contained within the aforementioned range, the solubility of the resin is good.

The content of the solvent (D) may be in the range of 10 to 2000 parts by mass relative to 100 parts by mass of the acid-modified polyolefin (A). It is preferably 25 parts by mass or more and 1500 parts by mass or less, more preferably 50 parts by mass or more and 1000 parts by mass or less, particularly preferably 100 parts by mass or more and 900 parts by mass or less, and even more preferably 100 parts by mass or more and 800 parts by mass or less. If it is within the above range, it is advantageous in terms of manufacturing cost and transportation cost.

<Curing agent (E)> The curing agent (E) used in the present invention is not particularly limited, and epoxy compounds, isocyanate compounds, compounds containing oxazoline groups and carbodiimide groups, silane coupling agents, etc. can be appropriately used. From the perspective of good adhesion to the resin substrate, isocyanate compounds are preferred.

The isocyanate compound used in the present invention is not particularly limited, and diisocyanates, triisocyanates, and compounds derived therefrom can be preferably used. For example, diisocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, bis(4-isocyanatocyclohexyl)methane, or hydrogenated diphenylmethane diisocyanate can be listed. In addition, compounds derived from the aforementioned diisocyanates, i.e., isocyanurate forms, adduct forms, diurea forms, uretdione forms, allophanate forms, prepolymers having isocyanate residues (oligomers obtained from diisocyanates and polyols), tris(epoxypropyl) isocyanurate, or complexes thereof, etc., can be listed. These can be used alone or in any combination of two or more.

The isocyanate compound used in the present invention is preferably an isocyanurate of the above-mentioned diisocyanate compound because of its excellent adhesion to the resin substrate.

The epoxy curing agent used in the present invention is not particularly limited. Epoxy resins and compounds derived therefrom can be preferably used, and bifunctional epoxides are more preferred. Specific examples include: glycidylamine type epoxy resins, bisphenol A, phenol novolac type epoxy resins, cresol novolac type epoxy resins and other glycidyl ether type epoxy resins, glycidyl hexahydrophthalate, glycidyl dimer acid glycidyl ester type, or alicyclic or aliphatic epoxides such as 3,4-epoxyhexylmethylcarboxylate, epoxidized polybutadiene, epoxidized soybean oil, etc., and one type can be used alone or two or more types can be used in combination.

The blending amount of the hardener (E) used in the present invention is preferably 10 parts by mass or less relative to 100 parts by mass of the total solid content of the adhesive such as the acid-modified polyolefin (A), the diene polymer (B) and the adhesive (C). In particular, it is preferably in the range of 8 parts by mass or less, more preferably 6 parts by mass or less, particularly preferably 4 parts by mass or less, and particularly preferably 3 parts by mass or less. If the hardener is added, a sufficient cross-linked structure can be obtained, and the heat resistance becomes better. If it is 10 parts by mass or less, the pot life is extended and the coating stability is better. In addition, the curing shrinkage becomes smaller, and the adhesion to the substrate is better.

The adhesive composition of the present invention may be mixed with and used with various additives such as plasticizers, hardening accelerators, flame retardants, pigments, and anti-adhesion agents in addition to the acid-modified polyolefin (A), the diene polymer (B), and the adhesive (C) within the range that does not impair the performance of the present invention.

<Adhesive composition> When the adhesive composition of the present invention contains a solvent (D), the total amount of the acid-modified polyolefin (A), the diene polymer (B) and the binder (C) in the adhesive composition/the amount of the solvent (D) is preferably 5/95 to 100/0. It is more preferably 7/93 to 40/60, particularly preferably 10/90 to 35/65, and particularly preferably 12/88 to 30/70. If it is within the above range, there is a tendency for good storage stability and good coating properties.

<Laminate> The laminate of the present invention is formed by laminating a polyolefin resin substrate 1 and a polyolefin substrate 1 or a heterogeneous substrate 2 using the adhesive composition of the present invention. The heterogeneous substrate 2 is a substrate different from the polyolefin substrate 1. For example, if the polyolefin substrate 1 is polypropylene, the heterogeneous substrate 2 is an ABS resin, polycarbonate, etc. other than polypropylene.

The laminated body of the present invention is useful in, for example, automobile parts such as bumpers, instrument panels, trims, and decorative panels, transportation parts such as Shinkansen interior materials, home appliance parts such as televisions, washing machine tanks, refrigerator parts, air conditioning parts, and vacuum cleaner parts, mobile devices such as mobile phone terminals and notebooks, communication equipment, touch panels of various devices, and daily necessities.

The lamination method can utilize the lamination manufacturing technology known in the past. For example, the adhesive composition is applied to the surface of the substrate using an appropriate coating means such as a coating machine and a coating rod, and then dried without special limitation. After drying, while the layer of the adhesive composition (adhesive layer) formed on the surface of the substrate is in a molten state, another substrate is laminated and bonded (laminated bonding, heat-sealed bonding) on the coated surface to obtain a laminate. Either lamination bonding or heat-sealed bonding method can ensure sufficient adhesion. The thickness of the adhesive layer formed by the adhesive composition is not particularly limited, but is preferably 0.5 to 60 μm, more preferably 1 to 50 μm, and even more preferably 2 to 40 μm.

<Polyolefin resin substrate (film)> As for the polyolefin resin substrate, it is sufficient to appropriately select from the conventionally known polyolefin resins. For example, polyethylene, polypropylene, ethylene-propylene copolymer, etc. can be used without particular limitation. Among them, it is preferable to use a non-stretched film of polypropylene (hereinafter also referred to as CPP). Its thickness is not particularly limited, and it is preferably 20 to 100 μm, preferably 25 to 95 μm, and even more preferably 30 to 90 μm. In addition, the polyolefin resin substrate can be mixed with pigments and various additives as needed, and can also be subjected to surface treatment.

<Polyolefin resin substrate (molded body)> As for the polyolefin resin substrate, it is sufficient to appropriately select from the conventionally known polyolefin resins. For example, polyethylene, polypropylene, ethylene-propylene copolymer, etc. can be used without particular limitation. Among them, polypropylene resin substrate is preferably used. Its thickness is not particularly limited, and is preferably 0.1 to 100 mm, preferably 0.5 to 90 mm, and particularly preferably 1 to 80 mm. In addition, the polyolefin resin substrate can be mixed with pigments and various additives as needed, and can also be subjected to surface treatment.

<Other heterogeneous substrates (molded bodies)> For heterogeneous substrates, ABS resin, polycarbonate, polyvinyl chloride, acrylic resin, urethane resin, Al foil, etc. can be used. The thickness is not particularly limited, and is preferably 0.1 to 100 mm, preferably 0.5 to 90 mm, and even more preferably 1 to 80 mm. The surface can be treated or untreated. In either case, the same effect can be achieved. [Example]

The present invention is described in more detail below with reference to the following embodiments. However, the present invention is not limited to the embodiments.

<Production Example of Acid-modified Polyolefin (A)> Production Example 1 In a 1L autoclave, add 100 parts by mass of polypropylene (Tm: 80°C, weight average molecular weight 135,000), 150 parts by mass of toluene, 8.5 parts by mass of maleic anhydride, and 4 parts by mass of di-tert-butyl peroxide, raise the temperature to 140°C, and stir for 1 hour. After the reaction is completed, the reaction solution is added to a large amount of methyl ethyl ketone to precipitate the resin. The resin is further washed with methyl ethyl ketone several times to remove the unreacted maleic anhydride. The obtained resin was dried under reduced pressure to obtain maleic anhydride-modified polypropylene (A-1, acid value 12 mgKOH/g-resin, weight average molecular weight 60,000, Tm 80°C, melting heat 31 J/g) which is an acid-modified polyolefin.

Production Example 2 Except that the polypropylene used in Production Example 1 was changed to a different polypropylene (Tm: 80°C, weight average molecular weight 45,000), the same procedures as in Production Example 1 were followed to obtain maleic anhydride-modified polypropylene (A-2, acid value 12 mgKOH/g-resin, weight average molecular weight 45,000, Tm 80°C, heat of fusion 34 J/g) which is an acid-modified polyolefin.

Production Example 3 The same process as in Production Example 1 was performed except that the polypropylene used in Production Example 1 was changed to a propylene-butene copolymer (Tm: 83°C, propylene 80 mol%, butene 20 mol%), thereby obtaining a maleic anhydride-modified propylene-butene copolymer (A-3, acid value 12 mgKOH/g-resin, weight average molecular weight 90,000, Tm 80°C, heat of fusion 48 J/g) which is an acid-modified polyolefin.

Production Example 4 The same process as in Production Example 1 was performed except that the polypropylene used in Production Example 1 was changed to a propylene-butene copolymer (Tm: 98°C, propylene 85 mol%, butene 15 mol%) and the amount of maleic anhydride was changed to 20 parts by mass, thereby obtaining a maleic anhydride-modified propylene-butene copolymer (A-4, acid value 25 mgKOH/g-resin, weight average molecular weight 60,000, Tm 95°C, heat of fusion 61 J/g) which is an acid-modified polyolefin.

Example 1 In a 500 ml four-necked flask equipped with a water-cooled reflux condenser and a stirrer, 100 parts by mass of maleic anhydride-modified polypropylene (A-1) obtained in Preparation Example 1, 20 parts by mass of diene elastomer (B-1), 35 parts by mass of adhesive (C-1), 15 parts by mass of (C-2), 432 parts by mass of cyclohexane (D1) and 48 parts by mass of butyl acetate (D2) were added, and the mixture was heated to 70°C while stirring. After stirring for 1 hour, the mixture was cooled to obtain an adhesive composition 1. The adhesive composition 1 was used to prepare a laminate according to the following method.

Preparation of a laminate of a polyolefin resin substrate and a polyolefin resin substrate or other heterogeneous substrates (heat seal bonding) The polyolefin resin substrate used was an unoriented polypropylene film (Pylen (registered trademark) film CT manufactured by Toyobo Co., Ltd., thickness 80μm) (hereinafter also referred to as CPP). The obtained adhesive composition was applied to the polyolefin resin substrate using a coating machine in such a manner that the film thickness of the adhesive layer after drying was adjusted to about 20μm. The applied surface was dried in a hot air dryer at 100°C for 3 minutes to obtain a polyolefin resin substrate laminated with an adhesive layer having a film thickness of about 20μm. A polypropylene (PP) test plate (manufactured by Nippon Testpanel, thickness 2 mm), an ABS test plate (manufactured by Nippon Testpanel, thickness 2 mm), and a polycarbonate (PC) test plate (manufactured by Nippon Testpanel, thickness 2 mm) were stacked on the surface of the above-mentioned adhesive layer, and a heat seal tester (TP-701-B) manufactured by Tester Sangyo was used to bond them at a heat seal temperature of 90°C (55°C on the test plate side), 0.3MPa, and 15 seconds, and then aged at room temperature for 1 day to obtain a laminate. The obtained laminate was evaluated for adhesion. The results are shown in Table 1.

(Examples 2 to 11, Comparative Examples 1 to 4) The acid-modified polyolefin (A), diene polymer (B), binder (C) and curing agent (E) were changed as shown in Table 1, and adhesive compositions 2 to 15 were prepared in the same manner as in Example 1. Using the obtained adhesive compositions 2 to 15, laminates were prepared in the same manner as in Example 1, and the adhesion was evaluated. The evaluation results are shown in Table 1.

The diene polymers (B) used in Table 1 are as follows. B-1: Trilene (registered trademark) 65 manufactured by Lion Elasters (Mn: 17,000) B-2: Lithene ultra (registered trademark) N4-5000-15MA manufactured by Synthomer (Mn: 5750, acid value: 75 mgKOH/g-resin) B-3: Lithene ultra (registered trademark) N4-5000 (Mn: 5000) manufactured by Synthomer

The adhesives (C) used in Table 1 are as follows. C-1: Harima Chemicals HARITACK (registered trademark) FK125 (rosin ester adhesive, softening temperature 125°C) C-2: Harima Chemicals HARITACK (registered trademark) F85 (rosin ester adhesive, softening temperature 85°C) C-3: Arakawa Chemicals Pinecrystal (registered trademark) KE-311 (rosin adhesive, softening temperature 95°C) C-4: Arakawa Chemicals Pinecrystal (registered trademark) KE-359 (rosin adhesive, softening temperature 100°C, hydroxylation: 37-48 mgKOH/g-resin)

The hardener (E) used in Table 1 is as follows. E-1: CORONATE HX manufactured by Tosoh Corporation (registered trademark)

The acid-modified polyolefin, diene polymer, adhesive, adhesive composition and laminate obtained in the above manner were analyzed, measured and evaluated according to the following method. <Determination of acid value> The acid value (mgKOH/g-resin) in the present invention is the amount of KOH required to neutralize 1g of the acid-modified polyolefin (A), and is measured according to the test method of JIS K0070 (1992). Specifically, 1g of the acid-modified polyolefin is dissolved in 100g of xylene adjusted to 100°C, and then titrated at the same temperature using 0.1mol/L potassium hydroxide ethanol solution [trade name "0.1mol/L ethanolic potassium hydroxide solution", manufactured by Wako Junyaku Co., Ltd.] with phenolphthalein as an indicator. At this time, the amount of potassium hydroxide required for titration is converted into mg to calculate the acid value (mgKOH/g).

<Determination of number average molecular weight (Mn)> The number average molecular weight in the present invention is measured using a gel permeation chromatograph Alliance e2695 manufactured by Waters Corporation of Japan (hereinafter referred to as GPC, standard material: polystyrene resin, mobile phase: tetrahydrofuran, column: Shodex KF-806 + KF-803, column temperature: 40°C, flow rate: 1.0 ml/min, detector: photodiode array detector (wavelength 254 nm = ultraviolet light)).

<Determination of crystallization degree> The adhesive composition was applied to the surface of a Teflon (registered trademark) sheet using a coating machine, and then peeled off after drying to obtain a film-like adhesive composition. After that, XRD measurement was performed under the following conditions. Measurement equipment: Rigaku Denki X-ray diffraction device RINT2500 Target: Cu Tube voltage: 40kV Tube current: 200mA Collimator: 1mmφ Slit: 2° longitudinally, 1/2° transversely Light receiving part: Ni filter, scintillation counter Scanning range: 2θ/θ The crystallization degree was calculated from the obtained XRD diffraction peak.

<Determination of Melting Point and Heat of Fusion> The melting point and heat of fusion in the present invention are measured by using a differential scanning calorimeter (hereinafter referred to as DSC, manufactured by TA Instruments Japan, Q-2000), which is maintained at -50°C for 5 minutes, then heated at a rate of 10°C/min to melt, melted at 200°C and maintained at 200°C for 2 minutes, cooled to -50°C at a rate of 10°C/min and resinified, and then cooled and resinified and then heated again at a rate of 10°C/min to melt, and the top temperature and area of the melting peak when the temperature is increased again at a rate of 10°C/min to melt.

<Evaluation of Adhesion> The laminate was cut into 15mm strips and the adhesion was evaluated using the 180° peel test according to the following criteria. The 180° peel test was conducted in accordance with the test method of ASTM-D1876-61, using TENSILON RTM-100 manufactured by ORITENTIC COPORATION, to measure the peel strength at a tensile speed of 50mm/min at 25°C. The peel strength (N/15mm) between heterogeneous substrates/polyolefin resin substrates was the average of two test values.

<Stretchability of coating film> The stretchability of the coating film in the present invention is measured by preparing a cast film with a thickness of 50 μm and using TENSILON RTM-100 manufactured by ORITENTIC COPORATION at a tension rate of 50 mm/min at 25°C. The cast film is prepared as follows. The obtained adhesive composition is applied to a Teflon sheet using a coating machine in such a way that the film thickness of the adhesive layer after drying is adjusted to 50 μm. The coated surface is dried in a warm air dryer at 100°C for 10 minutes to obtain a Teflon sheet laminated with an adhesive layer with a thickness of 50 μm. The coating was peeled off from the Teflon sheet and cut into 60×15mm. The distance between the clips (the initial length of the coating) was set to 30mm, and the elongation was calculated according to the following formula. [(Length when the coating broke - Initial length of the coating)/Initial length of the coating]×100(%)

<Evaluation of heat resistance> The heat resistance of the present invention is evaluated by further storing each laminate obtained by the above method at 80°C for 10 days and then performing a peeling test in the same manner as the above-mentioned adhesion evaluation. The evaluation criteria are as follows. ◎: The peeling strength is 15N/15mm or more for various substrates ○: The peeling strength is 13N/15mm or more and less than 15N/15mm for various substrates △: The peeling strength is 11N/15mm or more and less than 13N/15mm for various substrates ×: The peeling strength is less than 11N/15mm for various substrates

[Table 1] [Industrial Applicability]

The adhesive composition of the present invention contains an acid-modified polyolefin, a diene polymer, and an adhesive, and has excellent adhesion not only to non-polar substrates such as polyolefins, but also to polar substrates, metals, and other heterogeneous substrates. In addition, it can be coated by dry coating, so the equipment cost can be reduced and the film thickness can be made thinner. In addition, even when the heat bonding is performed at a low temperature of 90°C or below where the thermal shrinkage effect of the polyolefin substrate is small, it can show excellent adhesion and good elongation. Therefore, the adhesive composition of the present invention can be widely used as an adhesive for various purposes, including decorative films and coating films, for bonding various types of substrates to each other.

Claims (7)

An adhesive composition comprises an acid-modified polyolefin (A), a diene polymer (B) and a binder (C). The mass ratio of the diene polymer (B) is 1 mass part or more and 100 mass parts or less relative to 100 mass parts of the acid-modified polyolefin (A), and the mass ratio of the binder (C) is 1 mass part or more and 100 mass parts or less. The acid value of the acid-modified polyolefin (A) is 2-50 mgKOH/g. The diene polymer (B) is selected from at least one of the group consisting of ethylene-propylene-diene rubber, polybutadiene, and isoprene rubber. An adhesive composition comprises an acid-modified polyolefin (A), a diene polymer (B), a tackifier (C) and a solvent (D), wherein the acid value of the acid-modified polyolefin (A) is 2-50 mgKOH/g, and the diene polymer (B) is selected from at least one of the group consisting of ethylene-propylene-diene rubber, polybutadiene and isoprene rubber. The adhesive composition of claim 1 or 2 contains a solvent (D), and the solvent (D) includes an alicyclic hydrocarbon solvent (D1) and an ester solvent or a ketone solvent (D2). As in the adhesive composition of claim 3, the mass ratio of the alicyclic hydrocarbon solvent (D1) to the ester solvent or ketone solvent (D2) is (D1)/(D2)=95/5~50/50. If the adhesive composition of claim 1 or 2 contains a hardener (E). The adhesive composition of claim 1 or 2 is used for bonding a polyolefin resin substrate 1 and a substrate 2 different from substrate 1. A laminated body is a laminated body of a polyolefin resin substrate 1 and a substrate 2 different from the substrate 1, which are bonded using an adhesive composition as described in any one of claims 1 to 5.