WO2020017269A1 - Polyolefin adhesive composition - Google Patents

Abstract

[Problem] To provide an adhesive composition which achieves good adhesion between a polyolefin resin base material and a material of a different kind even if no curing agent is used, and which enables bonding at low temperatures, while exhibiting excellent storage stability. [Solution] An adhesive composition which contains (A) an acid-modified polyolefin and (B) a stress relaxation agent which contains, as a monomer, styrene in an amount of 30% by mass or more, while having a type A durometer hardness of 69 or more.

Description

Polyolefin adhesive composition

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

Polyolefin-based resins such as polypropylene and polyethylene are inexpensive and have many excellent properties such as moldability, chemical resistance, water resistance, and electrical properties, and have been widely used in recent years as sheets, films, molded articles, and the like.
However, base materials made of these polyolefin resins (hereinafter, polyolefin base materials) are non-polar and crystalline, unlike polar base materials such as polyurethane resins, polyamide resins, acrylic resins, and polyester resins. It has the drawback that painting and bonding are difficult.
Recently, there has been an increasing demand for excellent adhesion between not only polyolefin-based substrates but also polar plastic substrates such as vinyl chloride and polyester, and different materials such as metals and polyolefin-based substrates.
The main components of the dissimilar material adhesive include ketones of ethylene-vinyl acetate copolymer, polyamide resins, polycarboxylic anhydrides, copolymers of ethylene and acrylic esters (Patent Document 1), There are known styrene-ethylene-propylene-styrene block copolymer rubbers or styrene-butadiene-styrene block copolymer rubbers to which a liquid plasticizer such as a tackifying resin component and a process oil is added (Patent Documents) However, in both cases, since the difference in polarity between the adhesive composition and the polyolefin-based substrate is large and the affinity is poor, peeling between the adhesive composition and the polyolefin-based substrate is likely to occur, and the adhesiveness is insufficient.
Therefore, a method of improving the adhesiveness by applying an organic solvent solution (varnish) such as a modified polyolefin resin having a high affinity to the polyolefin-based substrate to the polyolefin-based substrate as an adhesive (Patent Document 3) ) Etc. are used. However, only adhesiveness to a polar base material is low, and adhesiveness to a non-polar base material such as polypropylene is low.
Under such circumstances, various kinds of adhesives for different materials have been proposed (for example, see Patent Documents 4 to 6).

JP-A-11-92733 JP-A-8-60121 JP-A-2002-173514 Patent No. 6006387 JP 2004-292716 A Patent No.5320662

However, the proposed adhesive composition had insufficient adhesiveness when a curing agent was not used, and a curing agent was essential. Therefore, it is still insufficient in that aging is required and that the pot life is short. The present invention provides an adhesive composition which exhibits good adhesion between a polyolefin resin base material and other dissimilar materials without using a curing agent, and can be bonded at a low temperature.

た め In order to achieve the above object, the present inventors have conducted intensive studies and found that a combination of a specific stress relaxation agent and an acid-modified polyolefin is effective, and have come to propose the following invention. That is, the present invention has the following configurations.

An adhesive composition comprising an acid-modified polyolefin (A) and a stress relaxation agent (B) containing 30% by mass or more of styrene as a monomer and having a durometer A hardness of 69 or more.

It is preferable that the stress relaxing agent (B) is a styrene elastomer.

The acid value of the acid-modified polyolefin (A) is preferably 2 to 50 mgKOH / g.

It is preferable that the mass ratio of the stress relaxing agent (B) is 5 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the acid-modified polyolefin (A).

The adhesive composition according to any one of the above, further comprising a solvent (C).

The solvent (C) preferably contains an alicyclic hydrocarbon solvent (C1) and an ester solvent (C2).

The mass ratio of the alicyclic hydrocarbon solvent (C1) to the ester solvent (C2) is preferably (C1) / (C2) = 95/5 to 60/40.

接着 The adhesive composition according to any one of the above, which is used for bonding the polyolefin resin substrate 1 and the substrate 2 different from the substrate 1.

The adhesive composition according to any one of the above, wherein the substrate 2 is a polyester substrate.

A laminate of a polyolefin resin substrate 1 and a substrate 2 different from the substrate 1 adhered by the adhesive composition according to any one of the above.

The adhesive composition of the present invention contains a modified polyolefin and a stress relieving agent, a non-polar substrate such as a polyolefin and a polar substrate such as polyester even when a curing agent is not used, and other heterogeneous substrates such as metal. Excellent adhesion. Further, since coating can be performed by dry lamination, equipment costs can be reduced and the film thickness can be reduced. Furthermore, excellent adhesiveness is exhibited even at a low temperature such as 110 ° C. or less where the heat shrinkage of the polyolefin substrate is small.

The adhesive composition of the present invention can be used not only with polyolefin base materials, but also with base materials such as polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene copolymer (ABS), polyvinyl chloride (PVC), acrylic resin, and steel plate. Since it shows good adhesion, it is useful as an adhesive for multi-base materials.

た め Further, since the adhesive composition of the present invention does not use a curing agent, it can be easily peeled off from the substrate by performing heat treatment even after bonding.

Hereinafter, embodiments of the present invention will be described in detail.

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

Homopolypropylene is particularly preferably used as the polypropylene, but a propylene / α-olefin copolymer can also be used. The propylene / α-olefin copolymer is obtained by copolymerizing α-olefin with propylene as a main component. As the α-olefin, for example, one or several kinds of ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate and the like can be used. Among these α-olefins, ethylene and 1-butene are preferred, and 1-butene is most preferred.

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

The preferred range of the molar ratio of propylene to 1-butene is propylene / 1-butene = 100 to 60/0 to 40, more preferably 98 to 65/2 to 35, even more preferably 90 to 70/10 to 30. It is. When the propylene molar ratio is 60% or more, excellent adhesion to a polyolefin substrate can be exhibited. When the molar ratio of 1-butene is 2% or more, solubility in an organic solvent is increased, and coating properties as an adhesive are improved.

と し て As the olefin component, the total amount of the propylene and 1-butene components is preferably at least 62 mol%. It is more preferably at least 80 mol%, further preferably at least 90 mol%, particularly preferably at least 95 mol%, and even if it is at least 100 mol%. When the total amount of the propylene and 1-butene components is at least 62 mol%, the adhesiveness and chemical resistance are particularly good. What

Examples of at least one of the α, β-unsaturated carboxylic acids and acid anhydrides thereof include maleic acid, itaconic acid, citraconic acid and acid anhydrides thereof. Of these, acid anhydrides are preferred, and maleic anhydride is more preferred. 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. These acid-modified polyolefins can be used alone or in combination of two or more. Of these, 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. The range is more preferably 3 to 40 mg KOH / g, still more preferably 5 to 30 mg KOH / g, and particularly preferably 5 to 16 mg KOH / g. When the acid value is 2 mgKOH / g or more, the adhesive strength is favorably exhibited. On the other hand, when the acid value is 50 mgKOH / g or less, the compatibility with the stress relaxing agent (B) tends to be good.

The melting point (Tm) of the acid-modified polyolefin (A) is preferably from 50 ° C to 100 ° C. It is more preferably at least 55 ° C, and even more preferably at least 60 ° C. Further, the temperature is more preferably 90 ° C. or less, further preferably less than 90 ° C., more preferably 87 ° C. or less, and most preferably 85 ° C. or less. When the temperature is 50 ° C. or higher, the cohesive force derived from the crystals becomes strong, and the adhesiveness is good. On the other hand, when the temperature is 100 ° C. or lower, the solution stability and fluidity are good, and the operability at the time of bonding is excellent. .

The crystallinity of the acid-modified polyolefin (A) is preferably in the range of 10 to 50%. More preferably, it is in the range of 15 to 45%, most preferably in the range of 20 to 40%. When the value is more than the above value, the cohesive force derived from the crystal becomes strong, and the adhesiveness to the substrate is excellent. On the other hand, when the value is less than the above-mentioned value, gelation hardly occurs and the solution stability is good.

The heat of fusion of the modified polyolefin (A) is preferably in the range of 25 to 40 J / g. It is more preferably in the range of 28 to 38 J / g, and most preferably in the range of 30 to 36 J / g. When the value is more than the above value, the cohesive force derived from the crystal becomes strong and the adhesiveness is excellent. On the other hand, when the value is less than the above value, gelation is hard to occur, and the solution stability is good.

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, further preferably in the range of 30,000 to 160,000, particularly preferably in the range of 40,000 to 140,000, and most preferably in the range of 50 to 140,000. 000-100,000. If it is at least the above value, the cohesive strength will be high and the adhesiveness will be good. On the other hand, when the value is equal to or less than the above value, the operability at the time of bonding with good fluidity becomes good.

The method for producing the acid-modified polyolefin (A) is not particularly limited, and may be, for example, a radical grafting reaction (that is, a method in which a radical species is generated with respect to a polymer serving as a main chain, the unsaturated carboxylic acid and A reaction for graft-polymerizing an acid anhydride).

The radical generator is not particularly limited, but it is preferable to use an organic peroxide. Organic peroxides include di-tert-butylperoxyphthalate, tert-butyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexano. Ethate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, di-tert-butyl peroxide, lauroyl peroxide and the like can be mentioned. Examples of other radical generators include azonitriles such as azobisisobutyronitrile and azobisisopropionitrile.

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

<Stress relaxation agent (B)>
The adhesive composition of the present invention contains a stress relaxing agent (B). By including the stress relaxing agent, the internal stress after forming the adhesive film can be reduced, and the adhesion to the base material can be improved.

応 力 The stress relaxation agent (B) used in the present invention contains a styrene component as a monomer in an amount of 30% by mass or more. It is more preferably at least 33% by mass, even more preferably at least 35% by mass, particularly preferably at least 40% by mass, more preferably at least 45% by mass, most preferably at least 48% by mass. Further, it is preferably at most 80% by mass, more preferably at most 70% by mass. It is more preferably at most 65% by mass, particularly preferably at most 60% by mass, more preferably at most 55% by mass, most preferably at most 53% by mass. When the content is 30% by mass or more, compatibility with the acid-modified polyolefin (A) is moderate, a stress relaxation effect is exhibited, and adhesiveness tends to be improved. If it is at most 80% by mass, the compatibility with the acid-modified polyolefin (A) will be significantly improved. As the stress relaxing agent (B), a styrene-based thermoplastic elastomer is preferable.

The styrene-based thermoplastic elastomer is not particularly limited, but styrene-ethylene-butylene-styrene resin and styrene-ethylene-propylene resin are preferable. Other examples include styrene elastomer, styrene butadiene resin, styrene ethylene propylene styrene resin, styrene isoprene butadiene styrene resin, styrene isoprene styrene resin, and the like. The styrene-based thermoplastic elastomer may be an acid-modified product.

応 力 In addition to the styrene-based elastomer, an olefin-based elastomer, an alkene-based elastomer, a vinyl chloride-based elastomer, a urethane-based elastomer, an amide-based elastomer, and the like can be used as the stress relaxation agent (B) of the present invention. Among them, styrene elastomers are particularly preferred.

The durometer A hardness of the stress relaxing agent (B) used in the present invention is 69 or more. It is preferably at least 70, more preferably at least 75, even more preferably at least 80, further preferably at least 85, more preferably at least 90, most preferably at least 95. When it is 69 or more, the stress relaxation effect does not become too large, and the effect is favorably exhibited. Moreover, when it is 69 or more, not only the adhesiveness to polyolefin but also the adhesiveness to polyester, polyvinyl chloride, acrylic, ABS, and stainless steel are excellent. Although 100 may be used, it is preferably 99 or less.
Durometer A hardness can be measured according to JIS K6253-3: 2012.

The density of the stress relaxing agent (B) is preferably in the range of 0.88 to 0.99 g / cm ³ . More preferably, it is in the range of 0.90 to 0.97 g / cm ³ . When it is 0.88 g / cm ³ or more, the specific gravity difference from the acid-modified polyolefin (A) does not become too large, and the solution stability tends to be good. If it is 0.99 g / cm ³ or less, the specific gravity difference from the acid-modified polyolefin (A) does not become too large, and the solution stability becomes good.

引 張 The stress relaxation agent (B) preferably has a tensile strength in the range of 1.0 to 17 MPa. More preferably, it is in the range of 1.2 to 15 MPa. When the content is within the above range, good adhesiveness is exhibited.

These stress relaxation agents may be used alone or in combination of two or more.

は The content of the stress relaxing agent (B) in the adhesive composition of the present invention is preferably 5 parts by mass or more when the acid-modified polyolefin (A) is 100 parts by mass. It is more preferably at least 10 parts by mass, further preferably at least 15 parts by mass, particularly preferably at least 18 parts by mass, more preferably at least 20 parts by mass, most preferably at least 25 parts by mass. When the amount is 5 parts by mass or more, the adhesion to the polyolefin base material is favorably exhibited. . When the amount of the acid-modified polyolefin (A) is 100 parts by mass, the amount of the stress relaxation agent (B) is preferably 70 parts by mass or less. It is more preferably at most 67 parts by mass, further preferably at most 55 parts by mass, further preferably at most 50 parts by mass, more preferably at most 45 parts by mass, most preferably at most 35 parts by mass. When the amount is less than 70 parts by mass, the adhesion to the polyolefin substrate is particularly good.

<Solvent (C)>
The adhesive composition of the present invention can contain a solvent (C). The solvent (C) is not particularly limited as long as it can dissolve or disperse the acid-modified polyolefin (A) and the stress relieving agent (B), and alicyclic hydrocarbon solvents and ester solvents can be preferably used.
For example, cycloaliphatic hydrocarbon solvents include cyclohexane, methylcyclohexane, ethylcyclohexane and the like. Examples of the ester solvent include ethyl acetate, propyl acetate, butyl acetate and the like. Of these, methylcyclohexane and propyl acetate are preferred. These may be used alone or in combination of two or more.

溶 剤 As the solvent (C) used in the present invention, a mixed solvent containing an alicyclic hydrocarbon solvent (C1) and an ester solvent (C2) can be used. By using a mixed solvent of an alicyclic hydrocarbon solvent and an ester solvent, the solubility of the adhesive composition can be improved.

When the mixed solvent is used, the mass ratio of the alicyclic hydrocarbon solvent (C1) to the ester solvent (C2) is preferably (C1) / (C2) = 95/5 to 60/40. It is more preferably in the range of 90/10 to 65/35, and particularly preferably in the range of 80/20 to 70/30. When the mass ratio of the alicyclic hydrocarbon (C1) is within the above range, the solubility of the resin is good, and the solution viscosity is moderate, so that coating unevenness is small and good adhesion is exhibited.

The solvent (C) can be contained in the range of 10 to 2,000 parts by mass based on 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, further preferably 100 parts by mass or more and 900 parts by mass or less, more preferably 110 parts by mass or more and 800 parts by mass or less. It is. Within the above range, it is advantageous from the viewpoint of production cost and transportation cost.

The adhesive composition according to the present invention includes various tackifiers, plasticizers, and curing accelerators in addition to the acid-modified polyolefin (A) and the stress relieving agent (B) as long as the performance of the present invention is not impaired. And additives such as a flame retardant, a pigment and an anti-blocking agent.

<Adhesive composition>
The adhesive composition of the present invention contains an acid-modified polyolefin (A) and a stress relieving agent (B), and optionally contains a solvent (C). It is preferable that styrene is included in an amount of 1.5 parts by mass or more based on 100 parts by mass of the solid content of the adhesive composition. It is more preferably at least 3.3 parts by mass, even more preferably at least 4.3 parts by mass, particularly preferably at least 5.3 parts by mass, more preferably at least 6.3 parts by mass, most preferably at least 7 parts by mass. That is all. The upper limit is preferably 56 parts by mass or less, more preferably 47 parts by mass or less, still more preferably 36 parts by mass or less, particularly preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and most preferably 19 parts by mass or less. Not more than parts by mass. Within the above range, the compatibility with the acid-modified polyolefin and the adhesive strength tend to be good.

接着 The adhesive composition of the present invention preferably contains a total of 5% by mass or more of the acid-modified polyolefin (A) and the stress relaxation agent (B) in the adhesive composition. It is more preferably at least 7% by mass, further preferably at least 10% by mass, particularly preferably at least 15% by mass. Further, it is preferably at most 40% by mass, more preferably at most 35% by mass. It is more preferably at most 30% by mass, particularly preferably at most 25% by mass. Within the above range, storage stability and adhesiveness are good. In addition, when the content is 5% by mass or more, the coatability is improved.

接着 The adhesive composition of the present invention may not substantially contain a curing agent or a tackifier. The term "substantially not contained" means, for example, 1 part by mass or less, more preferably 0.5 part by mass or less, still more preferably 0.3 part by mass or less, more preferably 1 part by mass or less based on 100 parts by mass of the acid-modified polyolefin. 0.1 parts by mass or less, and even 0 parts by mass is acceptable. By substantially not containing a curing agent, even a once-formed laminate of the base material / adhesive / base material can be easily peeled off by a treatment such as heating.

The curing agent is not particularly limited, and indicates a generally known curing agent. For example, there are an epoxy curing agent, an isocyanate curing agent, a compound containing an oxazoline group or a carbodiimide group, and a silane coupling agent.

<Laminate>
The laminate of the present invention is obtained by laminating a polyolefin resin substrate and a heterogeneous substrate with the adhesive composition according to the present invention. For example, the adhesive composition of the present invention can favorably bond polypropylene and polyethylene terephthalate and can be preferably laminated. The adhesive composition of the present invention has good adhesiveness between a polyolefin resin substrate and various other heterogeneous substrates. The different kind of base material is a base material different from the polyolefin base material 1. For example, if the polyolefin substrate 1 is polypropylene, the different types of substrates include polyesters other than polypropylene, aluminum foil, and polyvinyl chloride substrates.

As a method of laminating, a conventionally known laminate manufacturing technique can be used. For example, although not particularly limited, the adhesive composition is applied to the surface of the substrate using an appropriate application means such as an applicator or a bar coater, and dried. After drying, while the adhesive composition layer (adhesive layer) formed on the substrate surface is in a molten state, the other substrate is laminated and adhered (laminated adhesive, heat seal adhesive) to the application surface. To obtain a laminate. Sufficient adhesiveness can be ensured by any of the laminate production methods of lamination bonding and heat sealing bonding.
The thickness of the adhesive layer formed by the adhesive composition is not particularly limited, but is preferably 0.5 to 15 μm, more preferably 1 to 12 μm when the heterogeneous substrate is a film, More preferably, the thickness is 2 to 10 μm. When the heterogeneous base material is a molded product, the thickness is preferably 5 to 40 μm, more preferably 10 to 30 μm.

<Polyolefin resin substrate (film)>
The polyolefin resin substrate may be appropriately selected from conventionally known polyolefin resins. For example, although not particularly limited, polyethylene, polypropylene, ethylene-propylene copolymer and the like can be used. Among them, use of a non-stretched polypropylene film (hereinafter, also referred to as CPP) is preferable. The thickness is not particularly limited, but is preferably 20 to 100 μm, more preferably 25 to 95 μm, and further preferably 30 to 90 μm. The polyolefin resin base material may be mixed with a pigment or various additives as necessary, or may be subjected to a surface treatment.

<Polyester resin substrate (film)>
The polyester resin substrate is not particularly limited. Although it varies depending on the purpose of use, it is generally used in the form of a sheet having a thickness of 0.01 to 10 mm, preferably 0.02 to 5 mm.
The surface of the polyester resin substrate may be subjected to a surface treatment in advance, or may be left untreated. In any case, the same effect can be exhibited.

<Other heterogeneous substrates>
As other different base materials, ABS resin, polyvinyl chloride, acrylic resin, SUS304, or the like can be used. Although not particularly limited, a commercially available test plate can be used. The thickness is also not particularly limited, but is preferably from 100 μm to 3 mm, and more preferably from 1 to 2.5 mm. The surface of these different kinds of base materials may be subjected to a surface treatment in advance, or may be left untreated. In any case, the same effect can be exhibited.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the embodiments.

<Production example of acid-modified polyolefin (A)>
Production Example 1
To a 1 L autoclave were added 100 parts by mass of polypropylene (Tm: 80 ° C., crystallinity = 23%), 150 parts by mass of toluene, 8.5 parts by mass of maleic anhydride, and 4 parts by mass of di-tert-butyl peroxide. After the temperature was raised to ° C., the mixture was further stirred for 1 hour (here, it was referred to as “reacted” for 1 hour). Thereafter, the obtained reaction solution was cooled to 125 ° C., and then poured into a container containing 219 parts by mass of methyl ethyl ketone preliminarily heated to 40 ° C. while stirring, cooled to 40 ° C., further stirred for 30 minutes, and further stirred at 25 ° C. The resin was precipitated by cooling to a temperature below (here, an operation of pouring the reaction solution into a solvent such as methyl ethyl ketone while stirring and cooling to precipitate the resin is referred to as "reprecipitation"). Thereafter, the slurry liquid containing the resin was centrifuged to separate acid-modified polypropylene grafted with maleic anhydride from (poly) maleic anhydride and a low molecular weight product.
Further, the acid-modified polypropylene taken out by centrifugation was charged with stirring into a new container of 2,000 parts by mass of methyl ethyl ketone kept at 25 ° C. in advance, and stirring was continued for 1 hour. Thereafter, the slurry liquid was centrifuged to further separate acid-modified polypropylene from (poly) maleic anhydride and low molecular weight substances. This operation was repeated twice to purify (here, the acid-modified polypropylene taken out by centrifugation was added to methyl ethyl ketone while stirring, and the operation of strengthening the purification by centrifugation again was referred to as “reslurry”. Do).
After purification, the residue was dried under reduced pressure at 50 ° C. for 5 hours to obtain a maleic anhydride-modified polypropylene (A-1, acid value 11 mg KOH / g-resin, weight average molecular weight 60,000, Tm 80 ° C., crystallization). (Degree = 25%).

Production Example 2
A maleic anhydride-modified polypropylene (A-2, acid value 6), which is an acid-modified polyolefin, was prepared in the same manner as in Production Example 1 except that the amount of maleic anhydride used in Production Example 1 was changed to 3.5 parts by mass. 0.5 mg KOH / g-resin, weight average molecular weight 77,000, Tm 80 ° C., crystallinity = 30%).

Production Example 3
Except that the polypropylene (Tm: 80 ° C.) used in Production Example 1 was changed to a propylene-butene copolymer (Tm: 83 ° C., 80% by mass of propylene, 20% by mass of butene), the same procedure as in Production Example 1 was carried out. Thus, a maleic anhydride-modified propylene-butene copolymer (A-3, acid value 11 mg KOH / g-resin, weight average molecular weight 90,000, Tm 80 ° C., crystallinity = 36%) as an acid-modified polyolefin was obtained.

Example 1
In a 500 ml four-necked flask equipped with a water-cooled reflux condenser and a stirrer, 75 parts by mass of the maleic anhydride-modified polypropylene (A-1) obtained in Production Example 1 and 25 parts of the stress relaxation agent (B-1) were added. A mass part, 280 parts by mass of methylcyclohexane and 120 parts by mass of methyl ethyl ketone were charged, the temperature was raised to 70 ° C. with stirring, the stirring was continued for 1 hour, and the mixture was cooled to obtain an adhesive composition. Using this adhesive composition 1, a laminate was prepared by the following method.

Production of laminate of polyolefin resin substrate and polyester resin substrate (lamination bonding)
A PET film (E5101, manufactured by Toyobo Co., thickness 50 μm) is used as the polyester resin base material, and a non-stretched polypropylene film (Pyrene (registered trademark) film CT manufactured by Toyobo Co., thickness 40 μm) is used as the polyolefin resin base material ( Hereinafter, also referred to as CPP).
The obtained adhesive composition was applied to a polyester resin base material using an applicator so that the thickness of the adhesive layer after drying was about 8 μm. The coated surface was dried in a 100 ° C. atmosphere for 1 minute using a hot air drier to obtain a polyester resin substrate on which an adhesive layer having a thickness of about 8 μm was laminated. A polyolefin resin base material is superimposed on the surface of the adhesive layer, and is stuck at a lamination temperature of 80 ° C. at 0.3 MPa and 1 m / min using a small table-top test laminator (SA-1010-S) manufactured by Tester Sangyo Co., Ltd. The laminate was cured at room temperature for one day to obtain a laminate.
The adhesiveness of the obtained laminate was evaluated. The results are shown in Tables 1 and 2.

(Examples 2 to 12, Comparative Examples 1 to 5)
The adhesive compositions 2 to 17 were produced in the same manner as in Example 1 except that the acid-modified polyolefin and the stress relaxing agent were changed as shown in Tables 1 and 2. Using the obtained adhesive compositions 2 to 17, a laminate was produced in the same manner as in Example 1, and the adhesion was evaluated. The evaluation results are shown in Tables 1 and 2.

The stress relaxation agents (B) used in Tables 1 and 2 are as follows.
B-1: Dynaron (registered trademark) 9901P manufactured by JSR (styrene content 53% by mass, durometer A hardness 98)
B-2: Septon (registered trademark) 1020 manufactured by Kuraray Co., Ltd. (styrene content: 36% by mass, durometer A hardness: 70)
B-3: manufactured by Asahi Kasei Corporation Tuftec (registered trademark) P1500 (styrene content 30% by mass, durometer A hardness 69)
B-4: TUFTEC (registered trademark) P1083 manufactured by Asahi Kasei Corporation (styrene content: 20% by mass, durometer A hardness: 56)
B-5: Dynaron (registered trademark) 8903P (styrene content 35% by mass, durometer A hardness 49) manufactured by JSR Corporation

Example 13
An adhesive composition 1 was obtained in the same manner as in Example 1. Using this adhesive composition 1, a laminate was prepared by the following method.

Fabrication of laminated body of polyolefin resin base material and other different base materials (heat seal bonding)
The same unstretched polypropylene film as described above was used as the polyolefin resin substrate. The obtained adhesive composition was applied to a polyolefin resin base material using an applicator so that the thickness of the dried adhesive layer was about 20 μm. The coated surface was dried in a 100 ° C. atmosphere for 1 minute using a hot air drier to obtain a polyolefin resin substrate on which an adhesive layer having a thickness of about 20 μm was laminated. A polypropylene test plate (manufactured by Nippon Test Panel, thickness 2 mm), an ABS test plate (manufactured by Nippon Test Panel, thickness 2 mm), and a polycarbonate test plate (manufactured by Japan Test Panel, thickness 2 mm) on the surface of the adhesive layer. , Polyvinyl chloride test plate (manufactured by Nippon Test Panel, thickness 2 mm), acrylic test plate (manufactured by Japan Test Panel, thickness 2 mm), SUS304 test plate (manufactured by Japan Test Panel, thickness 2 mm), PET test The plates (manufactured by Nippon Test Panel Co., Ltd., thickness 2 mm) are stacked, and using a heat seal tester (TP-701-B) manufactured by Tester Sangyo Co., Ltd. at a heat seal temperature of 90 ° C. (the test plate side is 55 ° C.) A laminate was obtained by bonding at 0.3 MPa and 15 s and curing at room temperature for one day.
The adhesiveness of the obtained laminate was evaluated. Table 3 shows the results.

The stress relaxation agent (B) used in Table 3 is the same as that used in Tables 1 and 2.

Each of the acid-modified polyolefins, stress relaxation agents, adhesive compositions and laminates obtained as described above was analyzed and measured based on the following methods.
<Measurement of styrene content>
The stress relaxing agent was dissolved in deuterated chloroform, and the H-NMR spectrum of the sample solution was measured at an observation width of 15 ppm. A calibration curve was previously obtained from the peak areas and concentrations of styrene in the H-NMR spectrum of the polystyrene / deuterated chloroform solution having three concentrations, and the calibration curves were used to determine the styrene peak area of the sample solution. The content was calculated.

<Measurement of acid value>
The acid value (mgKOH / g-resin) in the present invention is the amount of KOH required to neutralize 1 g of the acid-modified polyolefin (A), and according to the test method of JIS K0070 (1992). It was measured. Specifically, after dissolving 1 g of the acid-modified polyolefin in 100 g of xylene adjusted to a temperature of 100 ° C., a 0.1 mol / L potassium hydroxide ethanol solution [trade name “0” using phenolphthalein as an indicator at the same temperature. .1 mol / L ethanolic potassium hydroxide solution ", manufactured by Wako Pure Chemical Industries, Ltd.]. At this time, the acid value (mgKOH / g) was calculated by converting the amount of potassium hydroxide required for the titration into mg.

<Measurement of durometer A hardness>
Durometer A hardness was measured in accordance with JIS K6253-3: 2012. Specifically, place the test piece on a flat and solid surface, and hold the durometer so that the pressure plate of the durometer is parallel to the surface of the test piece and the indenter is perpendicular to the surface of the rubber. And bring the pressure plate into contact with the test piece. The tip of the indenter was measured at a distance of 12.0 mm or more from the end of the test piece.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight in the present invention is determined by gel permeation chromatograph Alliance e2695 manufactured by Nippon Waters (hereinafter, GPC, standard substance: 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).

<Measurement of melting point and heat of fusion>
In the present invention, the melting point and the heat of fusion are measured by using a differential scanning calorimeter (hereinafter, DSC, manufactured by TA Instruments Japan, Q-2000) at a rate of 10 ° C./min. Then, it was measured from the top temperature and the area of the melting peak at the time of reheating and melting again.

<Measurement of crystallinity>
The adhesive composition was applied to the surface of a Teflon (registered trademark) sheet using an applicator, dried, and then peeled to obtain a film-like adhesive composition. Thereafter, XRD measurement was performed under the following conditions. Measuring equipment: Rigaku X-ray diffractometer RINT2500
Target: Cu
Tube voltage: 40 kV
Tube current: 200 mA
Collimator: 1mmφ
Slit: vertical 2 °, horizontal 1/2 °
Light receiving section: Ni filter, scintillation counter scanning range: 2θ / θ
The crystallinity was calculated from the obtained XRD diffraction peak.

<Evaluation of adhesion>
The laminate was cut into 15 mm strips, and the adhesion was evaluated by a 180 ° peel test according to the following criteria.
The T-peel test was conducted in accordance with the test method of ASTM-D1876-61, and the peel strength at a tensile speed of 50 mm / min was measured at 25 ° C. using Tensilon RTM-100 manufactured by Orientec Corporation. The peel strength (N / 15 mm) between the polyester substrate and the polyolefin resin substrate was an average of three test values.

The adhesive composition of the present invention contains an acid-modified polyolefin and a thermoplastic resin, and even when a curing agent is not used, a non-polar substrate such as a polyolefin and a polar substrate, and the adhesiveness of other different substrates such as a metal. Excellent. Further, since coating can be performed by dry lamination, equipment costs can be reduced and the film thickness can be reduced. Furthermore, excellent adhesiveness is exhibited even at a low temperature such as 110 ° C. or less where the heat shrinkage of the polyolefin substrate is small. Therefore, the adhesive composition of the present invention can be widely used as an adhesive for bonding various types of substrates.
 

Claims (10)

An adhesive composition containing an acid-modified polyolefin (A) and a stress relaxation agent (B) containing 30% by mass or more of a styrene component and having a durometer A hardness of 69 or more. The adhesive composition according to claim 1, wherein the stress relaxing agent (B) is a styrene-based elastomer. 3. The adhesive composition according to claim 1, wherein the acid value of the acid-modified polyolefin (A) is 2 to 50 mgKOH / g. The adhesive composition according to any one of claims 1 to 3, wherein the mass ratio of the stress relaxing agent (B) is 5 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the acid-modified polyolefin (A). object. The adhesive composition according to any one of claims 1 to 4, further comprising a solvent (C). The adhesive composition according to claim 5, wherein the solvent (C) includes an alicyclic hydrocarbon solvent (C1) and an ester solvent (C2). The adhesive composition according to claim 6, wherein the mass ratio of the alicyclic hydrocarbon solvent (C1) to the ester solvent (C2) is (C1) / (C2) = 95/5 to 60/40. The adhesive composition according to any one of claims 1 to 7, which is used for bonding a polyolefin resin substrate 1 and a substrate 2 different from the substrate 1. 接着 The adhesive composition according to claim 8, wherein the substrate 2 is a polyester substrate. A laminate of a polyolefin resin substrate 1 and a substrate 2 different from the substrate 1 bonded by the adhesive composition according to any one of claims 1 to 7.