Adhesive composition and laminate

Abstract

The adhesive composition contains a modified polyolefin resin. The polyolefin resin is modified with an unsaturated carboxylic acid and a radical-reactive aromatic compound. The polyolefin resin has a heat of fusion of 10 J / g or less as measured according to JIS K7122. The modification amount of the unsaturated carboxylic acid with respect to the modified polyolefin resin is greater than 0.5 mass% and less than 5 mass%. The modification amount of the radical-reactive aromatic compound with respect to the modified polyolefin resin is 0.1 mass% or more and less than 3 mass%.

Description

Technical Field

[0001] This invention relates to adhesive compositions and laminates. Background Technology

[0002] Polyolefin resins have been used in various fields such as packaging materials in the past.

[0003] On the other hand, polyolefin resins have low polarity, and therefore have low adhesion to materials with higher polarity than polyolefin resins (high polarity materials).

[0004] Therefore, from the viewpoint of improving the adhesion of polyolefin resins, it is known to place a primer layer between the polyolefin resin and the highly polar material.

[0005] As a material for forming such a primer layer, for example, modified polyolefin resins obtained by modifying polyolefin resins using anhydrides of α,β-carboxylic acids and compounds having benzene rings have been proposed (see, for example, Patent Document 1).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2018 / 037849 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] On the other hand, adhesion is further required for the primer layer.

[0011] The present invention provides an adhesive composition and laminate with excellent adhesion and coatability to a substrate formed of a polyolefin resin and a surface layer formed of a material with a higher polarity than the polyolefin resin.

[0012] Methods for solving problems

[0013] The present invention [1] is an adhesive composition comprising a modified polyolefin resin, wherein the modified polyolefin resin is formed by modifying the polyolefin resin with unsaturated carboxylic acid and free radical reactive aromatic compounds, wherein the heat of fusion of the aforementioned polyolefin resin as determined according to JIS K7122 is less than 10 J / g, the amount of modification of the aforementioned unsaturated carboxylic acid relative to the aforementioned modified polyolefin resin is greater than 0.5% by mass and less than 5% by mass, and the amount of modification of the aforementioned free radical reactive aromatic compounds relative to the aforementioned modified polyolefin resin is more than 0.1% by mass and less than 3% by mass.

[0014] The present invention [2] includes the adhesive composition described in [1] above, wherein the amount of the aforementioned free radical reactive aromatic compound modified relative to the aforementioned modified polyolefin resin is 0.5% by mass or more.

[0015] The present invention [3] is the adhesive composition described in [1] or [2] above, wherein the amount of modification of the aforementioned unsaturated carboxylic acid relative to the aforementioned modified polyolefin resin is 1.1% by mass or more.

[0016] The present invention [4] includes a laminate having, on one side facing the thickness direction, the following components in sequence: a substrate formed of a polyolefin resin; a primer layer formed of an adhesive composition as described in any one of [1] to [3] above; and a surface layer formed of a material with a higher polarity than the aforementioned polyolefin resin.

[0017] Invention Effects

[0018] The modified polyolefin resin in the adhesive composition of the present invention is obtained by modifying the polyolefin resin with unsaturated carboxylic acids and free radical reactive aromatic compounds based on a specified modification amount. As a result, the primer layer obtained using this adhesive composition exhibits excellent adhesion to a substrate formed of polyolefin resin and excellent adhesion to a surface layer formed of a material with a higher polarity than the polyolefin resin.

[0019] Furthermore, the polyolefin resin has a heat of melting within a specified range. Therefore, the primer layer obtained using this adhesive composition exhibits excellent adhesion to the substrate formed from the polyolefin resin.

[0020] The laminate of the present invention includes a primer layer formed by the adhesive composition of the present invention. Therefore, the adhesion between the substrate formed of polyolefin resin and the surface layer formed of a material with a higher polarity than polyolefin resin is excellent. Attached Figure Description

[0021] [ Figure 1 ] Figure 1 This is a schematic diagram illustrating one embodiment of the laminate of the present invention.

[0022] [ Figure 2 ] Figure 2 This is a schematic diagram illustrating one embodiment of the method for manufacturing the laminate of the present invention. Figure 2 A shows the first step in preparing the polyolefin substrate. Figure 2 B shows the second step of applying a primer layer to one surface of a polyolefin substrate in the thickness direction. Figure 2 C shows the third step of configuring a surface layer on one side of the primer layer in the thickness direction. Detailed Implementation

[0023] The adhesive composition comprises a modified polyolefin resin.

[0024] Modified polyolefin resins are obtained by modifying polyolefin resins using unsaturated carboxylic acids and free radical reactive aromatic compounds.

[0025] <Polyolefin resin>

[0026] Polyolefin resins are olefin polymers that contain structural units derived from olefins.

[0027] Examples of olefins include, for example, α-olefins. Examples of α-olefins include, for example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

[0028] As olefins, α-olefins with 2 to 6 carbon atoms are preferred, and ethylene, propylene, and 1-butene are more preferred.

[0029] Olefins can be used alone or in combination of two or more. Preferred examples include the combination of ethylene and propylene, and the combination of ethylene, propylene, and 1-butene. That is, the polyolefin resin is preferably a propylene / ethylene copolymer or a propylene / 1-butene / ethylene copolymer.

[0030] When the polyolefin resin is a propylene / ethylene copolymer, the proportion of structural units from propylene is, for example, 60 mol% or more, preferably 70 mol% or more, and, for example, 90 mol% or less, preferably 80 mol% or less, relative to the total 100 mol% of structural units from propylene and ethylene. The proportion of structural units from ethylene is, for example, 10 mol% or more, preferably 20 mol% or more, and, for example, 40 mol% or less, preferably 30 mol% or less.

[0031] Furthermore, when the polyolefin resin is a propylene / 1-butene / ethylene copolymer, relative to the total 100 mol% of structural units from propylene, 1-butene, and ethylene, the content of structural units from propylene is, for example, 50 mol% or more, preferably 60 mol% or more, and also, for example, 80 mol% or less, preferably 70 mol% or less. The content of structural units from 1-butene is, for example, 5 mol% or more, preferably 10 mol% or more, and also, for example, 30 mol% or less, preferably 20 mol% or less. The content of structural units from ethylene is, for example, 10 mol% or more, preferably 20 mol% or more, and also, for example, 40 mol% or less, preferably 30 mol% or less.

[0032] The heat of melt of the polyolefin resin, as determined according to JIS K7122, is 10 J / g or less, preferably 5 J / g or less, more preferably 3 J / g or less, and usually 0 J / g or more.

[0033] Furthermore, if the heat of melting is below the aforementioned upper limit, the primer layer 3 (described later) obtained using this adhesive composition exhibits excellent adhesion to the polyolefin substrate 2 (described later).

[0034] It should be noted that the method for determining the heat of fusion is described in detail in the examples described later.

[0035] In addition, the melting point of the polyolefin resin is, for example, 50°C or higher, preferably 60°C or higher, more preferably 70°C or higher, and, for example, 115°C or lower, preferably 113°C or lower, more preferably 110°C or lower.

[0036] Alternatively, it can be an amorphous material that does not contain polyolefin resin.

[0037] It should be noted that the method for determining the melting point is described in detail in the examples described later.

[0038] In addition, the weight-average molecular weight of the polyolefin resin, as determined by gel permeation chromatography (GPC) and converted to polystyrene, is, for example, 40,000 or more, preferably 50,000 or more, more preferably 55,000 or more, and for example, 500,000 or less, preferably 400,000 or less, more preferably 380,000 or less.

[0039] It should be noted that the method for determining the weight-average molecular weight is described in detail in the examples described later.

[0040] Polyolefin resins are obtained by polymerizing olefins using known methods. Additionally, metallocene catalysts can be incorporated into the polymerization process as needed.

[0041] <Unsaturated carboxylic acids>

[0042] Examples of unsaturated carboxylic acids include, for example, those with 3 to 8 carbon atoms. Examples of unsaturated carboxylic acids with 3 to 8 carbon atoms include monocarboxylic acids and dicarboxylic acids. Examples of monocarboxylic acids include (meth)acrylic acid (acrylic acid and / or methacrylic acid), crotonic acid, and isocrotonic acid. Examples of dicarboxylic acids include maleic acid, fumaric acid, itaconic acid, citraconic acid, mesoconic acid, pentenic acid, allyl succinic acid, nadic acid, methyl nadic acid, tetrahydrofumaric acid, and methylhexahydrophthalic acid.

[0043] In addition, among unsaturated carboxylic acids, the anhydrides of the aforementioned unsaturated carboxylic acids can be cited.

[0044] As an unsaturated carboxylic acid, anhydrides of unsaturated carboxylic acids are preferred, anhydrides of dicarboxylic acids are more preferred, and maleic anhydride is even more preferred.

[0045] Unsaturated carboxylic acids can be used alone or in combination with two or more.

[0046] In addition, the amount of unsaturated carboxylic acid modification relative to the modified polyolefin resin is greater than 0.5% by mass, preferably more than 1.1% by mass, and less than 5% by mass, preferably less than 3% by mass, and more preferably less than 2% by mass.

[0047] If the modified amount is above the lower limit, the primer layer 3 (described later) obtained using the adhesive composition exhibits excellent adhesion to the surface layer 4 (described later) and to the polyolefin substrate 2 (described later), especially excellent adhesion to the surface layer 4 (described later). Furthermore, if the modified amount is 1.1% by mass or more, the adhesion is further improved.

[0048] Furthermore, if the amount of modification is below the upper limit, the primer layer 3 (described later) obtained using the adhesive composition exhibits excellent adhesion to the surface layer 4 (described later) and to the polyolefin substrate 2 (described later), especially excellent adhesion to the polyolefin substrate 2 (described later).

[0049] It should be noted that the aforementioned amount of modification can be determined, for example, by the proportions of each component during the preparation of the modified polyolefin resin. Additionally, it can be determined through the modification of the polyolefin resin... 1 It can be confirmed using known methods such as H-NMR measurement.

[0050] <Free radical reactive aromatic compounds>

[0051] Radical-reactive aromatic compounds are compounds that possess both a site capable of radical addition and an aromatic ring.

[0052] Examples of free radical reactive aromatic compounds include, for example, aromatic compounds containing free radical polymerizable double bonds and free radical reactive aromatic hydrocarbons.

[0053] Aromatic compounds containing free radical polymerizable double bonds are compounds that possess both free radical polymerizable double bonds and aromatic rings.

[0054] Examples of aromatic compounds containing free radical polymerizable double bonds include, for example, aromatic vinyl compounds and (meth)acrylates containing aromatic rings. Examples of aromatic vinyl compounds include, for example, styrene, α-methylstyrene (2-phenylpropene), 2-phenylbutene, 3-phenylpropene, divinylbenzene, 1-vinylnaphthalene, p-methylstyrene, m-methylstyrene, o-methylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, 3-methyl-5-ethylstyrene, p-tert-butylstyrene, p-sec-butylstyrene, p-chlorostyrene, p-vinylbenzoic acid, p-vinylbenzoic acid esters, and vinyl benzoate. Examples of (meth)acrylates containing aromatic rings include, for example, phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and triphenyl (meth)acrylate.

[0055] Examples of free radical reactive aromatic hydrocarbons include toluene, xylene, and ethylbenzene.

[0056] As free radical reactive aromatic compounds, aromatic compounds containing free radical polymerizable double bonds are preferred, aromatic vinyl compounds are more preferred, and styrene is even more preferred.

[0057] Furthermore, the amount of free radical reactive aromatic compound modified relative to the modified polyolefin resin is 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and for example less than 3% by mass, preferably 2% by mass or less, more preferably 1.5% by mass or less, and even more preferably 1.1% by mass or less.

[0058] If the modification amount is above the lower limit, the primer layer 3 (described later) obtained using the adhesive composition exhibits excellent adhesion to the polyolefin substrate 2 (described later). Furthermore, especially if the modification amount is 0.5% by mass or more, the adhesion is further improved.

[0059] Furthermore, if the amount of modification is below the upper limit, the increase in viscosity of the adhesive composition can be suppressed, and the coatability (specifically, the spray coating property) is excellent.

[0060] It should be noted that the aforementioned amount of modification can be determined, for example, by the proportions of each component during the preparation of the modified polyolefin resin. Additionally, it can be determined through the modification of the polyolefin resin... 1 It can be confirmed using known methods such as H-NMR measurement.

[0061] <Preparation of Modified Polyolefin Resins>

[0062] Modified polyolefin resins are obtained by modifying polyolefin resins using unsaturated carboxylic acids and free radical reactive aromatic compounds.

[0063] Specifically, it is obtained by polymerizing unsaturated carboxylic acids and free radical reactive aromatic compounds in the presence of a polyolefin resin. Thus, the polyolefin resin is grafted and modified using unsaturated carboxylic acids and free radical reactive aromatic compounds.

[0064] The reaction temperature is, for example, 50°C or higher, preferably 80°C or higher, and also, for example, 250°C or lower. The reaction time is, for example, 1 minute or more, and also, 10 hours or less.

[0065] In addition, free radical polymerization initiators may be added in appropriate proportions as needed in the above reactions.

[0066] Examples of free radical polymerization initiators include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(benzoyl peroxide)-3-hexyne, 1,4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butyl peracetate, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl benzoate, tert-butyl perphenylacetate, tert-butyl perisobutyrate, tert-butyl peroxy-octanoate, tert-butyl perpentylate, cumyl perpentylate, and tert-butyl perethylacetate, as well as azo compounds such as azobisisobutyronitrile and dimethylazoisobutyronitrile.

[0067] As a free radical polymerization initiator, preferred dialkyl peroxides include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxide)-3-hexyne, 2,5-dimethyl-2,5-di(tert-butylperoxide)hexane, and 1,4-bis(tert-butylperoxyisopropyl)benzene.

[0068] Furthermore, the above reaction is carried out in the presence of a solvent or under solvent-free conditions.

[0069] As a solvent, a known solvent can be selected.

[0070] Thus, a modified polyolefin resin is obtained. Furthermore, when the above reaction is carried out in the presence of a solvent, the resulting modified polyolefin resin is prepared in the form of a varnish.

[0071] In addition, the melting point of the modified polyolefin resin is, for example, 50°C or higher, preferably 60°C or higher, more preferably 70°C or higher, and, for example, 115°C or lower, preferably 113°C or lower, more preferably 110°C or lower.

[0072] Alternatively, it can be an amorphous material without modified polyolefin resin.

[0073] It should be noted that the method for determining the melting point is described in detail in the examples described later.

[0074] In addition, the weight-average molecular weight of the modified polyolefin resin, as determined by gel permeation chromatography (GPC) based on polystyrene, is, for example, 40,000 or more, preferably 50,000 or more, more preferably 55,000 or more, and for example, 500,000 or less, preferably 400,000 or less, more preferably 380,000 or less.

[0075] It should be noted that the method for determining the weight-average molecular weight is described in detail in the examples described later.

[0076] Furthermore, the adhesive composition comprises the aforementioned modified polyolefin resin and a solvent as needed.

[0077] When the adhesive composition contains a solvent, the concentration of the solid component of the modified polyolefin resin is, for example, 1.0% by mass or more, preferably 3.0% by mass or more, and also, for example, 30% by mass or less, preferably 20% by mass or less.

[0078] As will be described in detail later, the primer layer 3 (described later) obtained using the adhesive composition exhibits excellent adhesion to the polyolefin substrate 2 (described later) and to the surface layer 4 (described later). Therefore, the adhesive composition can be suitably used to form a primer layer disposed between the polyolefin substrate 2 (described later) and the surface layer 4 (described later).

[0079] The laminate 1 having a primer layer 3 (described below) obtained using an adhesive composition will be described in detail below.

[0080] <Layered Body>

[0081] Reference Figure 1 An embodiment of the laminate of the present invention will be described.

[0082] Figure 1 In the diagram, the vertical direction on the paper is the vertical direction (thickness direction), the upper side of the paper is the upper side (one side of the thickness direction), and the lower side of the paper is the lower side (the other side of the thickness direction). Additionally, the horizontal direction and depth direction of the paper are plane directions orthogonal to the vertical direction. Specifically, refer to the directional arrows in each diagram.

[0083] like Figure 1 As shown, the laminate 1 has a film shape (including a sheet shape) with a specified thickness. The laminate 1 extends along a plane direction orthogonal to the thickness direction. The laminate 1 has a flat upper surface and a flat lower surface.

[0084] The laminate 1 comprises a polyolefin substrate 2, a primer layer 3, and a surface layer 4 sequentially on the side facing the thickness direction. Specifically, the laminate 1 comprises a polyolefin substrate 2, a primer layer 3 directly disposed on the upper surface (one side in the thickness direction) of the polyolefin substrate 2, and a surface layer 4 directly disposed on the upper surface (one side in the thickness direction) of the primer layer 3.

[0085] <Polyolefin substrate>

[0086] The polyolefin substrate 2 has a film shape. The polyolefin substrate 2 is disposed on the entire lower surface of the primer layer 3 in such a way that it is in contact with the lower surface of the primer layer 3.

[0087] The polyolefin substrate 2 is formed of polyolefin resin.

[0088] Examples of polyolefin resins exemplified in the above-described adhesive compositions include those described above.

[0089] <Primer layer>

[0090] The primer layer 3 has a film shape. The primer layer 3 is disposed on the entire lower surface of the surface layer 4 in such a way that it contacts the lower surface of the surface layer 4.

[0091] The primer layer 3 is formed from an adhesive composition.

[0092] As will be described in detail later, the primer layer 3 is obtained by coating an adhesive composition onto one side of the polyolefin substrate 2 in the thickness direction.

[0093] The thickness of the primer layer 3 is, for example, 1 μm or more, or, for example, 5 μm or less.

[0094] <Surface Layer>

[0095] Surface layer 4 has a film shape. Surface layer 4 is disposed on the entire upper surface of primer layer 3 in a manner that contacts the upper surface of primer layer 3. Surface layer 4 is the uppermost layer of laminate 1.

[0096] Surface layer 4 is formed of a material with a higher polarity than polyolefin resin (high polarity material).

[0097] Examples of highly polar materials include resins having ether bonds, ester bonds, amide bonds, imide bonds, and urethane bonds. Specifically, examples include acrylic resins, polyamide resins, polyimide resins, polyurethane resins, and vinyl chloride-vinyl acetate copolymers, with acrylic resins and vinyl chloride-vinyl acetate copolymers being preferred.

[0098] The thickness of surface layer 4 is, for example, 6 μm or more, or, for example, 20 μm or less.

[0099] <Manufacturing Method of Laminated Materials>

[0100] The manufacturing method of the laminate 1 includes the following steps: a first step of preparing a polyolefin substrate 2; a second step of depositing a primer layer 3 on one side of the polyolefin substrate 2 in the thickness direction; and a third step of depositing a surface layer 4 on one side of the primer layer 3 in the thickness direction.

[0101] In the first process, such as Figure 2 As shown in Figure A, prepare polyolefin substrate 2.

[0102] In the second process, such as Figure 2 As shown in Figure B, a primer layer 3 is disposed on one surface of the polyolefin substrate 2 in the thickness direction.

[0103] To deposit a primer layer 3 on one side of the polyolefin substrate 2 in the thickness direction, the aforementioned adhesive composition (varnish of modified polyolefin resin) is applied to one side of the polyolefin substrate 2 in the thickness direction and dried as needed. Thus, a primer layer 3 is deposited (formed) on one side of the polyolefin substrate 2 in the thickness direction.

[0104] There are no particular limitations on the coating method, but from a productivity point of view, spray coating is preferred.

[0105] As for drying conditions, any conditions that allow volatile components such as organic solvents contained in the adhesive composition to evaporate are acceptable and are not particularly limited. The drying temperature is, for example, 200°C or below, preferably 150°C or below, and for example, 10°C or above. In addition, the drying time is, for example, 3 seconds or more, preferably 1 minute or more, and for example, 1 hour or less.

[0106] In the third process, such as Figure 2 As shown in C, a surface layer 4 is disposed on one surface in the thickness direction of the primer layer 3.

[0107] The material of the surface layer 4 is applied to one side of the primer layer 3 in the thickness direction and dried as needed. Thus, the surface layer 4 is disposed (formed) on one side of the primer layer 3 in the thickness direction.

[0108] As for drying conditions, any conditions that allow volatile components such as organic solvents contained in the surface layer 4 material to evaporate are acceptable and are not particularly limited. The drying temperature is, for example, below 200°C, preferably below 150°C, and for example, above 10°C. In addition, the drying time is, for example, 3 seconds or more, preferably 1 minute or more, and for example, 1 hour or less.

[0109] The above method yields laminate 1.

[0110] <Effects>

[0111] The modified polyolefin resin in the adhesive composition is obtained by modifying the polyolefin resin using unsaturated carboxylic acids and free radical reactive aromatic compounds based on a specified modification amount. As a result, the primer layer 3 obtained using this adhesive composition exhibits excellent adhesion to the polyolefin substrate 2 and to the surface layer 4.

[0112] In detail, if the amount of unsaturated carboxylic acid modification is increased, the polarity of the primer layer 3 becomes higher, and the adhesion to the relatively high polarity surface layer 4 is improved. However, on the other hand, the adhesion to the relatively low polarity polyolefin substrate 2 tends to decrease.

[0113] In addition, increasing the amount of free radical reactive aromatic compounds improves the adhesion to the polyolefin substrate 2, but on the other hand, it tends to reduce the coatability.

[0114] In the adhesive composition, both the amount of unsaturated carboxylic acid modification and the amount of free radical reactive aromatic compound modification are adjusted to within a specified range. As a result, the coatability of the adhesive composition is improved, and the primer layer 3 obtained using this adhesive composition exhibits excellent adhesion to the polyolefin substrate 2 and to the surface layer 4. Consequently, the relatively low polarity polyolefin substrate 2 and the relatively high polarity surface layer 4 can be bonded through this primer layer 3.

[0115] Furthermore, the polyolefin resin has a heat of melting within a specified range. As a result, the primer layer 3 obtained using this adhesive composition exhibits excellent adhesion to the polyolefin substrate 2.

[0116] On the other hand, the modified polyolefin resin in Patent Document 1 is obtained by modifying the polyolefin resin using an anhydride of α,β-carboxylic acid (specifically maleic anhydride) and a compound having a benzyl ring (specifically benzylamine). Specifically, the polyolefin resin is first graft-modified using maleic anhydride. Then, the carboxyl group of the modified, ring-opened maleic anhydride reacts with the amino group of benzylamine. In this way, the benzylamine inhibits adhesion to the polyolefin substrate 2.

[0117] In contrast, in the modified polyolefin resin of the present invention, unsaturated carboxylic acids and free radical reactive aromatic compounds are grafted onto the polyolefin resin through free radical reactions.

[0118] That is, the modified polyolefin resin of the present invention is a resin obtained by grafting one molecule of polyolefin resin with both unsaturated carboxylic acid and free radical reactive aromatic compound, which is different from a mixture of resin obtained by grafting one molecule of polyolefin resin with unsaturated carboxylic acid and resin obtained by grafting one molecule of polyolefin resin with free radical reactive aromatic compound. Therefore, the free radical reactive aromatic compound is efficiently introduced into the polyolefin resin, improving its adhesion to the polyolefin substrate 2.

[0119] Furthermore, the laminate 1 includes a primer layer 3 formed from the aforementioned adhesive composition. Therefore, the adhesion between the polyolefin substrate 2 and the surface layer 4 is excellent.

[0120] The laminate 1 can be appropriately used in various fields such as packaging materials.

[0121] In the above description, surface layer 4 is a single layer. On the other hand, surface layer 4 can also be multiple layers (for example, two or more layers, preferably two or three layers).

[0122] In the above description, the polyolefin substrate 2 is in the shape of a film, but the shape of the polyolefin substrate 2 is not limited to this, for example, it can also be in the shape of a plate.

[0123] Example

[0124] The present invention will now be described based on embodiments and comparative examples, but the present invention is not limited to the embodiments described below. It should be noted that, unless otherwise specified, "parts" and "%" are based on mass. Furthermore, the specific values ​​of proportions (including ratios), physical property values, parameters, etc., used in the following description can be replaced with the corresponding upper limit values ​​(defined in the form of "less than" or "less than") or lower limit values ​​(defined in the form of "above" or "greater than") of the proportions (including ratios), physical property values, parameters, etc., described in the "Specific Embodiments" above.

[0125] 1. Preparation of adhesive compositions

[0126] Example 1

[0127] 100 parts by mass of propylene-ethylene copolymer (PER) with 79 mol% propylene unit and 21 mol% ethylene unit and 516 parts by mass of butyl acetate were added to a 1.0L autoclave equipped with a stirrer. The autoclave was heated to 145°C with stirring to completely dissolve the propylene-ethylene copolymer.

[0128] Then, while maintaining the solution at 145°C, 6 parts by mass of maleic anhydride, 1.5 parts by mass of styrene, and 3.6 parts by mass of di-tert-butyl peroxide were added dropwise over 6 hours with stirring. After the addition was complete, the mixture was stirred at 145°C for another 3 hours to carry out the reaction. Next, the resulting solution was cooled to 80°C and diluted with 774 parts by mass of methylcyclohexane. Then, the solution was cooled to room temperature and diluted with 1290 parts by mass of toluene to a solid content of 4%. This yielded an adhesive composition containing modified polyolefin resin.

[0129] Examples 2 to 4, and Comparative Examples 1 to 6

[0130] Following the same steps as in Example 1, an adhesive composition comprising a modified polyolefin resin was obtained.

[0131] However, the formulation was changed according to Table 1.

[0132] In addition, in Example 4, a propylene-butene-ethylene copolymer (PBER) with 66 mol% propylene units, 13 mol% butene units, and 21 mol% ethylene units was used.

[0133] In addition, in Comparative Example 5, a propylene-butene-ethylene copolymer (PBER) with 63 mol% propylene units, 23 mol% butene units, and 14 mol% ethylene units was used.

[0134] In addition, in Comparative Example 6, a propylene-ethylene copolymer (PER) with 85 mol% propylene units and 15 mol% ethylene units was used.

[0135] Comparative Example 7

[0136] 50 parts by mass of a propylene-ethylene copolymer consisting of 79 mol% propylene units and 21 mol% ethylene units, along with 261.6 parts by mass of butyl acetate, were added to a 1.0L autoclave equipped with a stirrer. The autoclave was heated to 145°C with stirring to completely dissolve the propylene-ethylene polymer.

[0137] Then, while maintaining the solution at 145°C, 6 parts by mass of maleic anhydride and 3.6 parts by mass of di-tert-butyl peroxide were added dropwise over 6 hours with stirring. After the addition was complete, the mixture was stirred further at 145°C for 3 hours to carry out the reaction. Next, the resulting solution was cooled to 80°C and diluted with 392.4 parts by mass of methylcyclohexane. It was then cooled to room temperature to obtain solution X. Next, the 6 parts by mass of maleic anhydride were replaced with 3 parts by mass of styrene, and the same procedure as for solution X was performed to obtain solution Y.

[0138] Solution X and solution Y were mixed at room temperature and then diluted with 1308 parts by mass of toluene to make the solid component 4% to obtain an adhesive composition.

[0139] Comparative Example 8

[0140] 100 parts by mass of a propylene-ethylene copolymer consisting of 79 mol% propylene units and 21 mol% ethylene units, along with 537.6 parts by mass of butyl acetate, were added to a 1.0L autoclave equipped with a stirrer. The autoclave was heated to 145°C with stirring to completely dissolve the propylene-ethylene polymer.

[0141] Next, while maintaining the solution at 145°C, 6 parts by mass of maleic anhydride and 3.6 parts by mass of di-tert-butyl peroxide were added dropwise over 6 hours with stirring. After the addition was complete, the mixture was stirred further at 145°C for 3 hours to carry out the subsequent reaction. The resulting solution was cooled to 135°C, and 6 parts by mass of benzylamine were added, followed by further stirring for 2 hours. The solution was then cooled to 80°C and diluted with 806.4 parts by mass of methylcyclohexane. After cooling to room temperature, it was diluted with 1344 parts by mass of toluene to a solid content of 4% to obtain the adhesive composition.

[0142] 2. Determination of heat of fusion

[0143] For the polyolefin resins used in each embodiment and comparative example, the heat of fusion was determined using a differential scanning calorimeter (TA Instruments; DSC-Q1000).

[0144] During the process of heating from 30°C to 180°C at a rate of 10°C / min, cooling down to 0°C at a rate of 10°C / min, and then heating up again to 150°C at a rate of 10°C / min, the melting point and heat of fusion were determined according to JIS K 7122 based on the temperature spectrum during the second heating. The results are shown in Table 1.

[0145] 3. Determination of the amount of modification

[0146] Regarding the modification amounts of unsaturated carboxylic acids relative to polyolefin resins and the modification amounts of free radical reactive aromatic compounds relative to polyolefin resins, the following conditions were adopted. 1 The measurements were performed using H-NMR. The results are shown in Table 1.

[0147] [Measurement Conditions]

[0148] Equipment: JEOL Ltd. ECX400 nuclear magnetic resonance spectrometer

[0149] Solvent: deuterated o-dichlorobenzene

[0150] Sample concentration: 20 mg / 0.6 mL

[0151] Measurement temperature: 120℃

[0152] Observation kernel: 1H (400MHz)

[0153] Sequence: Single Pulse

[0154] Pulse width: 5.12 μs (45° pulse)

[0155] Repeat time: 7.0 seconds

[0156] Total number of times: 500 or more

[0157] It should be noted that the baseline chemical shift is set to 0 ppm for the hydrogen in tetramethylsilane (it should also be noted that the same result can be obtained by setting the baseline chemical shift to 7.10 ppm for the residual hydrogen peak from deuterated o-dichlorobenzene). Peaks such as 1H from compounds containing functional groups are assigned using conventional methods.

[0158] 4. Determination of melting point

[0159] The melting points of the polyolefin resins used in each embodiment and the modified polyolefin resins used in each embodiment were determined. Specifically, a differential scanning calorimeter (TA Instruments; DSC-Q1000) was used to determine the melting points according to JIS K7122, based on the temperature spectrum at the second heating step, during the process of heating from 25°C to 200°C at 10°C / min, holding at 200°C for 3 minutes, cooling to 0°C at 10°C / min, and then heating back to 200°C at 10°C / min. The results are shown in Table 1.

[0160] 5. Weight-average molecular weight

[0161] For the polyolefin resins used in each embodiment, and the modified polyolefin resins used in each embodiment, the weight-average molecular weight was determined. Specifically, the weight-average molecular weight was determined based on the GPC method under the following conditions. The results are shown in Table 1.

[0162] Detector: Shimadzu Corporation; C-R4A

[0163] Columns: TSKG 6000H-TSKG 4000H-TSKG 3000H-TSKG 2000H (Made by Tosoh Corporation)

[0164] Mobile phase: Tetrahydrofuran

[0165] Column temperature: 40℃

[0166] Flow rate: 0.8 ml / min

[0167] Mw was calculated using a standard curve made from monodisperse standard polystyrene.

[0168] 6. Fabrication of laminated bodies

[0169] [Manufacturing of laminate A]

[0170] <Step 1>

[0171] Prepare polypropylene sheets.

[0172] <Step 2>

[0173] The adhesive compositions of each embodiment and comparative example were spray-coated onto one side of a polypropylene sheet in the thickness direction and dried at 60°C for 2 minutes. This yielded a primer layer with a thickness of 2 μm to 3 μm.

[0174] <Step 3>

[0175] An acrylic coating is spray-coated onto one side of the primer layer in the thickness direction and dried at 60°C for 3 minutes. The acrylic coating is then cured by UV irradiation. This forms a surface layer with a thickness of 10 μm to 15 μm. Laminate A is manufactured using this method.

[0176] [Manufacturing of Layer B]

[0177] Laminate B is manufactured using the same steps as laminate A.

[0178] However, the third process is modified as described below.

[0179] On one side of the primer layer in the thickness direction, a coating formed of a vinyl chloride-vinyl acetate copolymer resin is spray-coated and dried at 60°C for 3 minutes. This forms a first surface layer with a thickness of 5 μm to 6 μm. Next, on one side of this surface layer in the thickness direction, an acrylic coating is spray-coated and dried at 60°C for 3 minutes. Then, the acrylic coating is cured by UV irradiation. This forms a second surface layer with a thickness of 10 μm to 15 μm. Laminate B is manufactured using the above method.

[0180] 7. Evaluation

[0181] [Seamlessness]

[0182] In laminates A and B of each embodiment and comparative example, the surface layer was cut into a checkerboard pattern (2mm interval, 100 squares), and a peel test based on celluloid adhesive tape was performed on the polypropylene sheet or surface layer. Adhesion was evaluated using the adhesion rate (the number of squares remaining on the substrate).

[0183] Specifically, the adhesion between polypropylene and the primer layer (PP adhesion), the adhesion between the surface layer formed of an acrylic coating and the primer layer (acrylic adhesion), and the adhesion between the surface layer formed of a vinyl chloride-vinyl acetate copolymer resin and the primer layer (vinyl chloride-vinyl acetate copolymer resin adhesion) were evaluated based on the following criteria. It should be noted that since the adhesive composition could not be applied by spray coating in Comparative Example 4, the adhesion evaluation was not performed.

[0184] <PP adhesion>

[0185] For the laminates A and laminates B of each Example and each Comparative Example, the adhesion rate between the polypropylene plate and the primer layer was evaluated by a checkerboard test, and the PP adhesion was judged according to the following criteria. The results are shown in Table 1.

[0186] ○: The average adhesion rate is 100.

[0187] △: The average adhesion rate is less than 100 and not less than 90.

[0188] ×: The average adhesion rate is less than 90.

[0189] <Acrylic adhesion>

[0190] For the laminates A of each Example and each Comparative Example, the adhesion rate between the primer layer and the surface layer (acrylic layer) was evaluated by a checkerboard test, and the acrylic adhesion was judged according to the following criteria. The results are shown in Table 1.

[0191] ○: The adhesion rate is 100.

[0192] △: The adhesion rate is less than 100 and not less than 90.

[0193] ×: The adhesion rate is less than 90.

[0194] <Vinyl chloride-vinyl acetate copolymer resin adhesion>

[0195] For the laminates B of each Example and each Comparative Example, the adhesion rate between the primer layer and the surface layer (vinyl chloride-vinyl acetate copolymer resin layer) was evaluated by a checkerboard test, and the vinyl chloride-vinyl acetate copolymer resin adhesion was judged according to the following criteria. The results are shown in Table 1.

[0196] ○: The adhesion rate is 100.

[0197] △: The adhesion rate is less than 100 and not less than 90.

[0198] ×: The adhesion rate is less than 90.

[0199] [Spray applicability]

[0200] For the adhesive compositions of each embodiment and each comparative example, the type B viscosity was measured, and the spray suitability was judged according to the following criteria.

[0201] 〇: Viscosity less than 40 mPa·s. Determined to be suitable for spray coating.

[0202] ×: Viscosity above 40 mPa·s. Determined not suitable for spray coating.

[0203] [Table 1]

[0204]

[0205] It should be noted that the above-described invention is provided as an illustrative embodiment of the present invention, but it is merely illustrative and not intended to be limiting. Modifications of the present invention that will be apparent to those skilled in the art are included in the appended claims.

[0206] Industrial availability

[0207] The adhesive compositions and laminates of the present invention can be suitably used, for example, as packaging materials.

[0208] Explanation of reference numerals in the attached figures

[0209] 1-layer stack

[0210] 2 Substrate

[0211] 3 Primer layer

[0212] 4 Surface Layer

Claims

1. An adhesive composition comprising a modified polyolefin resin and a solvent, The modified polyolefin resin is formed by modifying polyolefin resin with unsaturated carboxylic acids and free radical reactive aromatic compounds. The heat of melt of the polyolefin resin, as determined according to JIS K7122, is below 10 J / g. The amount of unsaturated carboxylic acid modification relative to the modified polyolefin resin is 1.1% by mass or more and less than 5% by mass. The amount of the free radical reactive aromatic compound modified relative to the modified polyolefin resin is 0.1% by mass or more and 1.5% by mass or less. In the adhesive composition, the concentration of the solid component of the modified polyolefin resin is 1.0% by mass or more and 30% by mass or less.

2. The adhesive composition of claim 1, wherein, The amount of the free radical reactive aromatic compound modified relative to the modified polyolefin resin is 0.5% by mass or more.

3. A laminated body, wherein the side facing the thickness direction comprises, in sequence: Substrate formed of polyolefin resin; A primer layer formed from the dried product of the adhesive composition of claim 1; and A surface layer formed of a material with a higher polarity than the polyolefin resin.

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