Adhesive kit, method for manufacturing substrate with adhesive layer, and method for manufacturing article

Abstract

To provide an adhesive kit for forming an adhesive layer that exhibits strong adhesion to a polyolefin-containing substrate at a low heat treatment temperature (e.g., 130°C or below). [Solution] An adhesive kit comprising a first agent containing a low molecular weight polyolefin with a weight-average molecular weight of 100,000 or less, and a second agent containing a polyurethane having a hydrocarbon group (i) with 40 or more carbon atoms in its main chain.

Description

Technical Field

[0001] The present invention relates to an adhesive kit, a method for producing a substrate with an adhesive layer, and a method for producing an article.

Background Art

[0002] Resin substrates containing polyolefins such as polypropylene are widely used industrially. Resin substrates have the advantages of being lightweight and inexpensive compared to metal materials, and being easy to mold and process.

[0003] Generally, it is known that resin substrates are more difficult to wet on the surface compared to metal substrates. The difficulty of wetting the surface (hereinafter referred to as poor wettability) is, for example, a factor that causes defects such as peeling when applying an adhesive. In addition, substrates showing poor wettability are generally known to show poor adhesion, which is also a factor for poor adhesion of adhesives.

[0004] Therefore, conventionally, studies have been conducted to improve the adhesion to adhesives by changing the composition of the substrate, surface modification, etc.

[0005] For example, Patent Document 1 describes a method for obtaining a modified polyolefin resin composition with improved properties such as adhesiveness by melt-kneading a radical polymerization initiator, an unsaturated carboxylic acid monomer, and an aromatic vinyl monomer with a polyolefin resin. However, this method requires replacing the conventional resin substrate from its material, and there are problems in terms of practicality and cost.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] To ensure strong adhesion of the adhesive, high-temperature heat treatment (e.g., above 140°C) has been considered. However, such heat treatment requires a substrate with high heat resistance, which presents practical and cost challenges.

[0008] The present invention aims to provide an adhesive kit for forming an adhesive layer that exhibits strong adhesion to a polyolefin-containing substrate at a low heat treatment temperature (e.g., 130°C or below). Furthermore, the present invention aims to provide an adhesive-layer-coated substrate in which an adhesive layer is disposed on a polyolefin-containing substrate, and in which strong adhesion between the substrate and the adhesive layer can be achieved at a low heat treatment temperature (e.g., 130°C or below). Moreover, the present invention aims to provide an article in which an adherend is strongly bonded to a polyolefin-containing substrate via an adhesive layer. [Means for solving the problem]

[0009] One aspect of the present invention relates to an adhesive kit comprising a first agent containing a low molecular weight polyolefin with a weight-average molecular weight of 100,000 or less, and a second agent containing a polyurethane having a hydrocarbon group (i) with 40 or more carbon atoms in its main chain.

[0010] In one embodiment, the polyurethane may have a polyol unit (A) and a polyisocyanate unit (B). In this case, the polyol unit (A) may include a first polyol unit (A-1) having the hydrocarbon group (i).

[0011] In one embodiment, the content of the first polyol unit (A-1) may be 75% by mass or more, based on the total amount of the polyol unit (A) and the polyisocyanate unit (B).

[0012] In one embodiment, the hydrocarbon group (i) may be an alkanediyl group having 40 or more carbon atoms.

[0013] An adhesive kit according to one embodiment may be an adhesive kit for forming an adhesive layer on a substrate containing polyolefin.

[0014] Another aspect of the present invention relates to a method for producing a substrate with an adhesive layer, comprising: a first step of applying a first agent containing a low molecular weight polyolefin having a weight-average molecular weight of 100,000 or less onto a substrate containing a polyolefin to form a first layer containing the low molecular weight polyolefin; and a second step of applying a second agent containing a polyurethane having a hydrocarbon group (i) with 40 or more carbon atoms onto the first layer to form a second layer containing the polyurethane.

[0015] Another aspect of the present invention relates to a method for manufacturing an article, comprising: a first step of applying a first agent containing a low molecular weight polyolefin having a weight-average molecular weight of 100,000 or less onto a polyolefin-containing substrate to form a first layer containing the low molecular weight polyolefin; a second step of applying a second agent containing a polyurethane having a hydrocarbon group (i) with 40 or more carbon atoms onto the first layer to form a second layer containing the polyurethane; a third step of placing a adherend on the second layer to obtain a laminate comprising the substrate, the first layer, the second layer, and the adherend; and a fourth step of heating the laminate to obtain an article in which the substrate and the adherend are joined. [Effects of the Invention]

[0016] The present invention provides an adhesive kit for forming an adhesive layer that exhibits strong adhesion to a polyolefin-containing substrate at a low heat treatment temperature (e.g., 130°C or lower). Furthermore, the present invention provides an adhesive-layer-coated substrate in which an adhesive layer is disposed on a polyolefin-containing substrate, and in which strong adhesion between the substrate and the adhesive layer can be achieved at a low heat treatment temperature (e.g., 130°C or lower). Moreover, the present invention provides an article in which an adherend is strongly bonded to a polyolefin-containing substrate via the adhesive layer. [Modes for carrying out the invention]

[0017] Preferred embodiments of the present invention will be described in detail below.

[0018] (Adhesive kit) The adhesive kit of this embodiment comprises a first agent containing a low molecular weight polyolefin with a weight-average molecular weight of 100,000 or less, and a second agent containing a polyurethane having a hydrocarbon group (i) with 40 or more carbon atoms in its main chain.

[0019] According to the adhesive kit of this embodiment, an adhesive layer can be easily formed on a substrate by sequentially forming a coating film of the first agent and a coating film of the second agent on the substrate. The adhesive layer formed from the adhesive kit of this embodiment can exhibit strong adhesion to polyolefin at a low heat treatment temperature (e.g., 130°C or below) because the first agent contains a low molecular weight polyolefin and the second agent contains a specific polyurethane. For this reason, the adhesive kit of this embodiment can be suitably used as an adhesive kit for forming an adhesive layer on a substrate containing polyolefin.

[0020] The first agent contains a low molecular weight polyolefin. The weight-average molecular weight of the low molecular weight polyolefin is 100,000 or less, and from the viewpoint of easily obtaining strong adhesion at lower heat treatment temperatures, it may be 90,000 or less, 80,000 or less, 70,000 or less, 60,000 or less, 50,000 or less, 45,000 or less, 40,000 or less, 35,000 or less, 30,000 or less, 25,000 or less, 20,000 or less, 15,000 or less, 10,000 or less, or 9,000 or less.

[0021] Furthermore, the weight-average molecular weight of the low molecular weight polyolefin may be, for example, 1000 or more, and from the viewpoint of having a suitable melting point for the low molecular weight polyolefin, it may be 2000 or more, 3000 or more, 4000 or more, 5000 or more, 6000 or more, or 7000 or more.

[0022] The weight-average molecular weight of low molecular weight polyolefins is the value measured by gel permeation chromatography (GPC) under the following conditions. <Measurement of Weight-Average Molecular Weight of Low-Molecular-Weight Polyolefin> As the apparatus, a high-speed GPC apparatus (HLC-8321GPC / HT manufactured by Tosoh Corporation) was used. As the column, one TSKgel guardcolumn HR (30)HT (7.5 mm I.D. × 7.5 cm) and three TSKgel GMH HR -H(20)HT (7.8 mm I.D. × 30 cm) were connected in series in the described order (all columns were manufactured by Tosoh Corporation). As the mobile phase, 1,2,4-trichlorobenzene with 0.05% by mass of dibutylhydroxytoluene added was used, and the mobile phase velocity was set to 1.0 mL / min. The column temperature was 140 °C, the detector was an RI detector (polarity (-)), and the molecular weight was determined as the polystyrene-equivalent molecular weight. The sample solution was prepared using 1,2,4-trichlorobenzene to a concentration of 1 mg / mL and used. The injection volume of the sample was 300 μL.

[0023] The low-molecular-weight polyolefin may be, for example, polyethylene, polypropylene, ethylene-propylene rubber, ethylene-propylene-diene rubber, or the like.

[0024] The low-molecular-weight polyolefin is preferably the same type of polyolefin as the polyolefin contained in the substrate on which the adhesive layer is formed. That is, when the polyolefin in the substrate is polyethylene, the low-molecular-weight polyolefin is preferably polyethylene, and when the polyolefin in the substrate is polypropylene, the low-molecular-weight polyolefin is preferably polyethylene.

[0025] The first agent may further contain a solvent. The solvent can be any solvent capable of dissolving low molecular weight polyolefins. Examples of solvents include aromatic hydrocarbon solvents such as toluene, ethylbenzene, trimethylbenzene, o-xylene, p-xylene, chlorobenzene, 1,2,4-trichlorobenzene, Solvesso 100, Solvesso 150, and Solvesso 200, and aliphatic hydrocarbon solvents such as pentane, hexane, and cyclohexane. Of these, toluene, o-xylene, and p-xylene are preferred.

[0026] The solvent content in the first agent is not particularly limited and may be adjusted as appropriate, for example, so that the solid content concentration falls within the preferred range described later. The solvent content in the first agent may be, for example, 1 part by mass or more, preferably 10 parts by mass or more, and more preferably 1000 parts by mass or more, per 100 parts by mass of low molecular weight polyolefin. Alternatively, the solvent content in the first agent may be, for example, 1,000,000 parts by mass or less, preferably 100,000 parts by mass or less, and more preferably 10,000 parts by mass or less, per 100 parts by mass of low molecular weight polyolefin.

[0027] The solid content concentration of the first agent is not particularly limited and may be adjusted as appropriate depending on the application method of the first agent. The solid content concentration of the first agent may be, for example, 0.0010% by mass or more, preferably 0.010% by mass or more, more preferably 0.10% by mass or more, and may be 1% by mass or more. Alternatively, the solid content concentration of the first agent may be, for example, 99% by mass or less, and may be 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, or 2% by mass or less.

[0028] The first agent may further contain other components besides low molecular weight polyolefin and solvent. Examples of other components include catalysts, defoamers, leveling agents, organic thickeners, antioxidants, light stabilizers, adhesion enhancers, mold release agents, reinforcing agents, softeners, colorants, flame retardants, antistatic agents, wetting and dispersing agents, and the like.

[0029] The content of other components in the first agent may be, for example, 25 parts by mass or less, preferably 12 parts by mass or less, more preferably 6 parts by mass or less, 2 parts by mass or less, or even 0 parts by mass, per 100 parts by mass of low molecular weight polyolefin.

[0030] The second agent contains a polyurethane having a hydrocarbon group (i) with 40 or more carbon atoms in its main chain.

[0031] The polyurethane in the second component may have polyol units (A) and polyisocyanate units (B). Here, among the constituent units formed by the polymerization of polyol (a) and polyisocyanate (b), the constituent units derived from polyol (a) are polyol units (A), and the constituent units derived from polyisocyanate (b) are polyisocyanate units (B). In other words, the polyurethane may be a monomer polymer containing polyol (a) and polyisocyanate (b).

[0032] The average number of hydroxyl groups (average number of functional groups) of polyol(a) may be 1.3 or more, preferably 1.7 or more, more preferably 1.9 or more, and may be 4 or less, preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The average number of hydroxyl groups (average number of functional groups) of polyol(a) may be less than 2, which may be due to, for example, the presence of a monool impurity in the diol. Polyol(a) is particularly preferably a diol, and polyol unit(A) is particularly preferably a diol unit.

[0033] The average number of isocyanate groups (-NCO) in polyisocyanate (b) (average number of functional groups) may be, for example, 1.3 or more, preferably 1.7 or more, more preferably 1.9 or more, and may be, for example, 4 or less, preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The average number of isocyanate groups (average number of functional groups) in polyisocyanate (b) may be less than 2, which may be due to, for example, the presence of a monofunctional isocyanate impurity in the diisocyanate. Polyisocyanate (b) is particularly preferably diisocyanate, and polyisocyanate unit (B) is particularly preferably diisocyanate unit.

[0034] Polyurethane preferably has a first polyol unit (A-1) having a hydrocarbon group (i) as the polyol unit (A). That is, it is preferable that the polyol unit (A) has a first polyol unit (A-1) having a hydrocarbon group (i).

[0035] The first polyol unit (A-1) can be described as a constituent unit derived from the first polyol (a-1) having a hydrocarbon group (i).

[0036] The hydrocarbon group (i) may be a saturated hydrocarbon group or an unsaturated hydrocarbon group, preferably a saturated hydrocarbon group, and more preferably an alkanediyl group.

[0037] The number of carbon atoms in hydrocarbon group (i) is 40 or more, preferably 50 or more, more preferably 75 or more, and even more preferably 100 or more. Alternatively, the number of carbon atoms in hydrocarbon group (i) may be, for example, 500 or less, preferably 400 or less, more preferably 300 or less, and even more preferably 250 or less.

[0038] The hydrocarbon group (i) may be, for example, a saturated hydrocarbon skeleton such as a polyethylene skeleton, a polypropylene skeleton, a hydrogenated polybutadiene skeleton, a polybutene skeleton, a hydrogenated polyisoprene skeleton, or a hydrogenated polyfarnesene skeleton, or an unsaturated hydrocarbon skeleton such as a polybutadiene skeleton, a polyisoprene skeleton, or a polystyrene skeleton.

[0039] The first polyol unit (A-1) may have a saturated hydrocarbon skeleton or an unsaturated hydrocarbon skeleton, and it is preferable that it has a saturated hydrocarbon skeleton. The first polyol unit (A-1) may also be a polyol unit having oxygen atoms at both ends of a saturated hydrocarbon skeleton or an unsaturated hydrocarbon skeleton, and it is preferable that it is a polyol unit having oxygen atoms at both ends of a saturated hydrocarbon skeleton.

[0040] The first polyol (a-1) may be, for example, a polyol having a saturated hydrocarbon skeleton or an unsaturated hydrocarbon skeleton, and preferably a polyol having a saturated hydrocarbon skeleton. The first polyol (a-1) may also be a polyol having hydroxyl groups at both ends of a saturated hydrocarbon skeleton or an unsaturated hydrocarbon skeleton, and preferably a polyol having hydroxyl groups at both ends of a saturated hydrocarbon skeleton.

[0041] The average number of hydroxyl groups (average number of functional groups) of the first polyol (a-1) may be 1.3 or more, preferably 1.7 or more, more preferably 1.9 or more, and may be 4 or less, preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The average number of hydroxyl groups (average number of functional groups) of the first polyol (a-1) may be less than 2, which may be due to, for example, the presence of a monool impurity in the diol. The first polyol (a-1) is particularly preferably a diol, and the first polyol unit (A-1) is particularly preferably a diol unit.

[0042] The content of the first polyol unit (A-1) may be, for example, 60% by mass or more, preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total amount of polyol unit (A) and polyisocyanate unit (B). This tends to further improve the adhesive strength of the adhesive layer. The content of polyol unit (A) may be, for example, 99% by mass or less, based on the total amount of polyol unit (A) and polyisocyanate unit (B), and may be 98% by mass or less, 97% by mass or less, 96% by mass or less, 95% by mass or less, or 94% by mass or less.

[0043] The polyol unit (A) may further have other polyol units besides the first polyol unit (A-1). Examples of other polyol units include polyols having hydrocarbon groups with fewer than 40 carbon atoms, polyether polyols such as polyethylene glycols, polypropylene glycols, and polybutylene glycols, and monoglycerides such as caprylic acid monoglyceride, capric acid monoglyceride, lauric acid monoglyceride, stearate monoglyceride, and behenic acid monoglyceride.

[0044] The proportion of the first polyol unit (A-1) to the total polyol unit (A) (i.e., the content of the first polyol unit (A-1) on a total basis of polyol unit (A)) may be, for example, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 98% by mass or more, and may also be 100% by mass. This tends to further improve the adhesive strength of the adhesive layer.

[0045] The polyol unit (A) content may be, for example, 60% by mass or more based on the total amount of polyurethane, preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and even more preferably 85% by mass or more. This tends to further improve the adhesive strength of the adhesive layer. The polyol unit (A) content may also be, for example, 99% by mass or less based on the total amount of polyurethane, and may be 98% by mass or less, 97% by mass or less, 96% by mass or less, 95% by mass or less, or 94% by mass or less.

[0046] The polyurethane preferably has a first polyisocyanate unit (B-1) having an aromatic ring as the polyisocyanate unit (B). That is, the polyisocyanate unit (B) preferably contains a first polyisocyanate unit (B-1) having an aromatic ring.

[0047] The first polyisocyanate unit (B-1) can be described as a constituent unit derived from the first polyisocyanate (b-1) which has an aromatic ring.

[0048] The average number of isocyanate groups (-NCO) in the first polyisocyanate (b-1) (average number of functional groups) may be, for example, 1.3 or more, preferably 1.7 or more, more preferably 1.9 or more, and may be, for example, 4 or less, preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The average number of isocyanate groups (average number of functional groups) in the first polyisocyanate (b-1) may be less than 2, which may be due to, for example, the presence of a monofunctional isocyanate impurity in the diisocyanate. The first polyisocyanate (b-1) is particularly preferably a diisocyanate, and the first polyisocyanate unit (B-1) is particularly preferably a diisocyanate unit.

[0049] The aromatic ring of the first polyisocyanate unit (B-1) may be, for example, a benzene ring, a naphthalene ring, an anthracene ring, etc., and is preferably a benzene ring.

[0050] Specific examples of the first polyisocyanate unit (B-1) include, for example, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, and 1,4-tetramethylxylylene diisocyanate.

[0051] The polyisocyanate unit (B) may further include a second polyisocyanate unit (B-2) that does not have an aromatic ring, in addition to the first polyisocyanate unit (B-1).

[0052] The second polyisocyanate unit (B-2) can be described as a constituent unit derived from the second polyisocyanate (b-2) which does not have an aromatic ring.

[0053] The average number of isocyanate groups (-NCO) in the second polyisocyanate (b-2) (average number of functional groups) may be, for example, 1.3 or more, preferably 1.7 or more, more preferably 1.9 or more, and may be, for example, 4 or less, preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The average number of isocyanate groups (average number of functional groups) in the second polyisocyanate (b-2) may be less than 2, which may be due to, for example, the presence of a monofunctional isocyanate impurity in the diisocyanate. The second polyisocyanate (b-2) is particularly preferably a diisocyanate, and the second polyisocyanate unit (B-2) is particularly preferably a diisocyanate unit.

[0054] Specific examples of the second polyisoanate unit (B-2) include, for example, aliphatic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane-4,4'-diisocyanate, hydrogenated diphenylmethane-2,4'-diisocyanate, hydrogenated xylylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate.

[0055] The proportion of the first polyisocyanate unit (B-1) to the total polyisocyanate unit (B) (i.e., the content of the first polyisocyanate unit (B-1) on a total basis of the polyisocyanate unit (B)) may be, for example, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more, or 100% by mass.

[0056] The proportion of the second polyisocyanate unit (B-2) to the polyisocyanate unit (B) (i.e., the content of the second polyisocyanate unit (B-2) on a total basis of the polyisocyanate unit (B)) may be, for example, 30% by mass or less, 20% by mass or less, 10% by mass or less, or 5% by mass or less, or even 0% by mass.

[0057] The polyisocyanate unit (B) content may be, for example, 1% by mass or more based on the total amount of polyurethane, and may also be 2% by mass or more, 3% by mass or more, 4% by mass or more, 5% by mass or more, or 6% by mass or more. Furthermore, the polyisocyanate unit (B) content may be, for example, 40% by mass or less, preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0058] Polyurethane may further have other constituent units besides polyol units (A) and polyisocyanate units (B). Examples of other constituent units include polyamine units and polyamino alcohol units.

[0059] The total content of polyol units (A) and polyisocyanate units (B) in the polyurethane may be, for example, 90% by mass or more, preferably 95% by mass or more, more preferably 97% by mass or more, and may also be 100% by mass, based on the total amount of polyurethane.

[0060] The weight-average molecular weight (Mw) of polyurethane is not particularly limited, but may be, for example, 10,000 or more, preferably 12,500 or more, and more preferably 15,000 or more. Alternatively, the weight-average molecular weight (Mw) of polyurethane may be, for example, 200,000 or less, preferably 175,000 or less, and more preferably 160,000 or less.

[0061] In this specification, the weight-average molecular weight (Mw) of polyurethane is the value measured by gel permeation chromatography (GPC) under the following conditions. <Measurement of weight-average molecular weight of polyurethane> A high-speed GPC instrument (Tosoh HLC-8320GPC) was used as the apparatus, and one TSKgel guardcolumn α (6.0 mm I.D. × 4 cm) and two +α-M (67.8 mm I.D. × 30 cm) columns were connected in series in the order listed (all columns were manufactured by Tosoh). Cyclohexanone was used as the mobile phase, and the mobile phase rate was set to 1.0 mL / min. The column temperature was 40°C, and the detector was an RI detector (polarity(+)). The molecular weight was determined as polystyrene-equivalent molecular weight. The sample solution was prepared using cyclohexanone to a concentration of 1 mg / mL. The sample injection volume was 100 μL.

[0062] The second agent may further contain a solvent. The solvent can be any solvent capable of dissolving polyurethane. Examples of solvents include aromatic hydrocarbon solvents such as toluene, ethylbenzene, trimethylbenzene, and xylene; aliphatic hydrocarbon solvents such as pentane, hexane, and cyclohexane; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol solvents such as methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol; glycol ether solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl diglycol, ethyl diglycol, butyl diglycol, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate; amide solvents such as N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; ether solvents such as diethyl ether and tetrahydrofuran; and water. Of these, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone are preferred.

[0063] The solvent content in the second agent is not particularly limited and may be adjusted as appropriate, for example, so that the solid content concentration falls within the preferred range described later. The solvent content in the second agent may be, for example, 1.0 part by mass or more, preferably 40 parts by mass or more, and more preferably 150 parts by mass or more, per 100 parts by mass of polyurethane. Alternatively, the solvent content in the second agent may be, for example, 10,000 parts by mass or less, preferably 3,200 parts by mass or less, and more preferably 2,000 parts by mass or less, per 100 parts by mass of polyurethane.

[0064] The solid content concentration of the second agent is not particularly limited and may be adjusted as appropriate depending on the application method of the second agent. The solid content concentration of the second agent may be, for example, 1% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, and may also be 8% by mass or more. Alternatively, the solid content concentration of the second agent may be, for example, 99% by mass or less, and may also be 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, or 20% by mass or less.

[0065] The second agent may further contain other components besides polyurethane and solvent. Examples of other components include catalysts, defoamers, leveling agents, organic thickeners, antioxidants, light stabilizers, adhesion enhancers, release agents, reinforcing agents, softeners, colorants, flame retardants, antistatic agents, wetting and dispersing agents, and the like.

[0066] The content of other components in the second agent may be, for example, 25 parts by mass or less, preferably 12 parts by mass or less, more preferably 6 parts by mass or less, 2 parts by mass or less, or even 0 parts by mass, per 100 parts by mass of polyurethane.

[0067] The adhesive kit of this embodiment may include a first container containing a first agent and a second container containing a second agent.

[0068] The adhesive kit of this embodiment can be used to form an adhesive layer on a substrate (particularly a substrate containing polyolefin).

[0069] The adhesive layer formed by the adhesive kit of this embodiment may comprise a first layer containing a low molecular weight polyolefin and a second layer containing polyurethane. The first layer is formed from the first component, and the second layer is formed from the second component. Such an adhesive layer can exhibit strong adhesion to polyolefin even at relatively low heat treatment temperatures.

[0070] The first layer is formed directly on a substrate (particularly a substrate containing polyolefin). The first layer can be formed, for example, by coating and drying the first agent. More specifically, the first layer may be formed by, for example, the steps of coating the first agent to form a coating film and removing at least a portion of the solvent from the coating film to form the first layer.

[0071] The method of applying the first agent is not particularly limited and may include, for example, the applicator method, bar coating method, spin coating method, spray coating method, dip coating method, nozzle coating method, gravure coating method, reverse roll coating method, die coating method, air doctor coating method, blade coating method, rod coating method, curtain coating method, knife coating method, transfer roll coating method, squeeze coating method, impregnation coating method, kiss coating method, calender coating method, and extrusion coating method.

[0072] The drying method (solvent removal method) is not particularly limited and may include methods such as heating, reduced pressure, or air drying.

[0073] The thickness of the first layer may be, for example, 100 μm or less, preferably 10 μm or less, more preferably 5 μm or less, even more preferably 2 μm or less, and may even be 1 μm or less. This tends to make the adhesive layer less brittle. The thickness of the first layer may also be, for example, 0.010 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, even more preferably 0.15 μm or more, and may even be 0.18 μm or more. This tends to make the effect of using the first layer more pronounced.

[0074] The second layer is formed directly on the first layer. The second layer can be formed, for example, by applying and drying a second agent. More specifically, the second layer may be formed by the steps of applying a second agent to form a coating film and removing at least a portion of the solvent from the coating film to form the second layer.

[0075] The method of applying the second agent is not particularly limited and may include methods such as the applicator method, bar coating method, spin coating method, spray coating method, dip coating method, nozzle coating method, gravure coating method, reverse roll coating method, die coating method, air doctor coating method, blade coating method, rod coating method, curtain coating method, knife coating method, transfer roll coating method, squeeze coating method, impregnation coating method, kiss coating method, calender coating method, and extrusion coating method.

[0076] The drying method (solvent removal method) is not particularly limited and may include methods such as heating, reduced pressure, or air drying.

[0077] The thickness of the second layer may be, for example, 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, and may also be 30 μm or less. This allows the second layer to be formed at a lower cost. The thickness of the second layer may also be, for example, 0.05 μm or more, preferably 0.1 μm or more, more preferably 1 μm or more, even more preferably 5 μm or more, and may also be 8 μm or more. This tends to further improve the adhesive strength.

[0078] The adhesive layer formed by the adhesive kit of this embodiment is firmly bonded to the substrate by heat treatment. The heat treatment temperature may be, for example, 40°C or higher, preferably 60°C or higher, and more preferably 80°C or higher.

[0079] Furthermore, the heat treatment temperature may be, for example, 200°C or lower, and may also be 190°C or lower, 180°C or lower, 170°C or lower, 160°C or lower, 150°C or lower, or 140°C or lower. The adhesive kit of this embodiment can exhibit strong adhesion to polyolefins even at relatively low heat treatment temperatures. From this viewpoint, the heat treatment temperature may be, for example, 130°C or lower, 120°C or lower, 110°C or lower, 100°C or lower, or 90°C or lower.

[0080] The adhesive layer may be heat-treated, for example, with the adherend placed on the second layer. This allows for strong adhesion between the substrate and the adherend.

[0081] If the adherend contains a polyolefin, a third layer containing a low molecular weight polyolefin may be further provided on the second layer, and the adherend may be placed on the third layer. The third layer can be formed, for example, by coating and drying the first agent. The third layer may be the same as the first layer.

[0082] (Substrate with adhesive layer) The adhesive-layered substrate of this embodiment comprises a substrate containing polyolefin and an adhesive layer disposed on the substrate. The adhesive layer includes a first layer in contact with the substrate and a second layer disposed on the first layer. The adhesive layer may further have a third layer on the second layer. The substrate, first layer, second layer, and third layer may be the same as the substrate, first layer, second layer, and third layer described above.

[0083] A substrate with an adhesive layer can be manufactured, for example, by a manufacturing method that includes a first step of applying a first agent onto the substrate to form a first layer, and a second step of applying a second agent onto the first layer to form a second layer.

[0084] The above manufacturing method may further include a third step of applying the first agent onto the second layer to form a third layer.

[0085] The first step may be, for example, a step of directly applying the first agent onto a substrate to form a coating film, and then removing at least a portion of the solvent from the coating film to form the first layer.

[0086] The second step may be, for example, a step of directly applying the second agent onto the first layer to form a coating film, and then removing at least a portion of the solvent from the coating film to form the second layer.

[0087] The third step may be, for example, a step of directly applying the first agent onto the second layer to form a coating film, and then removing at least a portion of the solvent from the coating film to form the third layer.

[0088] (Goods) The article of this embodiment comprises a base material, an object to be adhered to, and a bonding layer that joins the base material and the object to be adhered.

[0089] The bonding layer is formed by heat treatment of the adhesive layer and adheres firmly to the substrate and the object to be adhered.

[0090] The article can be manufactured by a manufacturing method that includes, for example, a first step of applying a first agent to a substrate to form a first layer, a second step of applying a second agent to the first layer to form a second layer, a third step of placing an adherend on the second layer to obtain a laminate comprising a substrate, a first layer, a second layer, and an adherend, and a fourth step of heating the laminate to obtain an article in which the substrate and adherend are joined. The substrate, the first layer, and the second layer may be the same as the substrate, the first layer, and the second layer described above.

[0091] The first step may be, for example, a step of directly applying the first agent onto a substrate to form a coating film, and then removing at least a portion of the solvent from the coating film to form the first layer.

[0092] The second step may be, for example, a step of directly applying the second agent onto the first layer to form a coating film, and then removing at least a portion of the solvent from the coating film to form the second layer.

[0093] The above manufacturing method may further include a step of applying the first agent onto the second layer to form a third layer. This step may involve directly applying the first agent to form a coating film, and then removing at least a portion of the solvent from the coating film to form the third layer. Including this step allows for strong adhesion between the substrate and the adherend, even when the adherend contains polyolefin.

[0094] The third step is to place the adherend on the second layer, which may be a step of directly placing the adherend on the second layer, or a step of directly placing the adherend on the third layer formed on the second layer. That is, the laminate obtained in the third step may be a laminate in which the base material, the first layer, the second layer and the adherend are laminated in this order, or a laminate in which the base material, the first layer, the second layer, the third layer and the adherend are laminated in this order.

[0095] The fourth step is to bond the substrate and the adherend by heat treatment of the laminate. In the fourth step, it is sufficient that the adhesive layer in the laminate is heated. The method of heat treatment in the fourth step is not particularly limited and may be, for example, heating with hot air, hot pressing, or laser heating.

[0096] The heat treatment temperature in the fourth step is, for example, 40°C or higher, preferably 60°C or higher, and more preferably 80°C or higher.

[0097] Furthermore, the heat treatment temperature may be, for example, 200°C or lower, and may also be 190°C or lower, 180°C or lower, 170°C or lower, 160°C or lower, 150°C or lower, or 140°C or lower. The adhesive layer of this embodiment can exhibit strong adhesion to polyolefins even at relatively low heat treatment temperatures. From this viewpoint, the heat treatment temperature may be, for example, 130°C or lower, 120°C or lower, 110°C or lower, 100°C or lower, or 90°C or lower.

[0098] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. [Examples]

[0099] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0100] (Example 1) <Manufacturing of Polyurethane (1)> In a 2 L four-neck separable flask equipped with a stirrer, thermometer, heating device, and reflux tubing, 150 g of hydroxyl-terminated hydrogenated polyisoprene, 16 g of diphenylmethane-4,4'-diisocyanate (hereinafter referred to as MDI), 0.10 g of dioctyltin dilaurate, and 1499 g of cyclohexanone were charged at room temperature, and the flask was then purged with nitrogen gas by blowing in nitrogen. These were reacted under uniform stirring conditions at 80°C for 6 hours to obtain a coating solution (1) containing polyurethane (1). The weight-average molecular weight of the obtained polyurethane (1) was measured by the following method.

[0101] <Measurement of weight-average molecular weight> A high-speed GPC instrument (Tosoh HLC-8320GPC) was used as the apparatus, and one TSKgel guardcolumn α (6.0 mm I.D. × 4 cm) and two +α-M (7.8 mm I.D. × 30 cm) columns were connected in series in the order listed (all columns were manufactured by Tosoh). Cyclohexanone was used as the mobile phase, and the mobile phase rate was set to 1.0 mL / min. The column temperature was 40°C, and the detector was an RI detector (polarity(+)). The molecular weight was determined as polystyrene-equivalent molecular weight. The sample solution was prepared using cyclohexanone to a concentration of 1 mg / mL. The sample injection volume was 100 μL.

[0102] <Manufacturing of goods> As the first agent, a low molecular weight polypropylene solution (1) was prepared. The low molecular weight polypropylene solution (1) was obtained by charging 0.030 g of low molecular weight polyolefin (Viscol 660-P, manufactured by Sanyo Chemical Industries, Ltd., weight-average molecular weight 8000) and 30 g of p-xylene into a 50 mL screw-capacity tube, then purging the inside of the screw-cap tube with nitrogen gas, and allowing it to stand for 30 minutes under 80°C conditions to dissolve the low molecular weight polyolefin. In addition, as the second agent, a coating solution (1) containing polyurethane (1) was prepared. The polypropylene substrate and the adherend were bonded using the first and second agents in the following manner. First, the first agent was applied to the polypropylene substrate (Kobe Poly Sheet PP, manufactured by Hitachi Chemical Co., Ltd.) using an applicator, left to stand for 5 minutes at room temperature, and then dried in a hot air dryer at 80°C for 5 minutes to form the first layer with a dry film thickness of 0.20 μm. Next, the second agent was applied onto the first layer using a bar coater, left to stand for 5 minutes at room temperature, and then dried in a hot air dryer at 80°C for 5 minutes to obtain a laminate having a first and second layer with a dry film thickness of 10 μm. A polyethylene terephthalate film (Toyobo Ester Film E5100, manufactured by Toyobo Co., Ltd.) was laminated onto the second layer of this laminate, and then a test specimen was obtained by heat treatment at a specified temperature for 10 minutes. Here, the heat treatment was performed at 80°C or 185°C, and test specimens were prepared for each case.

[0103] <Measuring adhesive strength> The adhesive strength of two types of articles, one with a heat treatment temperature of 185°C and the other with a heat treatment temperature of 80°C, was measured using the following method. The results are shown in Table 1. Adhesion strength was evaluated by performing a 180-degree peel test in accordance with JIS K6854-2. The test was performed using an Autocom type testing machine (UTPS-Acs(S) manufactured by TSE Corporation).

[0104] (Example 2) Except for changing the low molecular weight polyolefin in the first agent to polypropylene with a weight-average molecular weight of 15,000 (Viscol 550-P, manufactured by Sanyo Chemical Industries, Ltd.), the article was manufactured and its adhesive strength was measured in the same manner as in Example 1. The results are shown in Table 1.

[0105] (Example 3) Except for changing the low molecular weight polyolefin in the first agent to polypropylene with a weight-average molecular weight of 30,000 (Viscol 440-P, manufactured by Sanyo Chemical Industries, Ltd.), the article was manufactured and its adhesive strength was measured in the same manner as in Example 1. The results are shown in Table 1.

[0106] (Example 4) Except for changing the low molecular weight polyolefin in the first agent to polypropylene with a weight-average molecular weight of 40,000 (Viscol 330-P, manufactured by Sanyo Chemical Industries, Ltd.), the article was manufactured and its adhesive strength was measured in the same manner as in Example 1. The results are shown in Table 1.

[0107] (Comparative Example 1) <Manufacturing of goods> The article was manufactured using the following method without using the first agent. Polyurethane (1) was applied to a polypropylene substrate using a bar coater, left to stand for 5 minutes at room temperature, and then dried in a hot air dryer at 80°C for 5 minutes to obtain a laminate having a polyurethane adhesive layer with a dry film thickness of 10 μm. A polyethylene terephthalate film (Toyobo Ester Film E5100 manufactured by Toyobo) was laminated onto the polyurethane layer, and then a test specimen was obtained by heat treatment at a specified temperature for 10 minutes. Here, the heat treatment was performed at 80°C or 185°C, and test specimens were prepared for each case. The adhesive strength of the obtained test specimens was measured in the same manner as in Example 1. The results are shown in Table 1.

[0108] (Example 5) <Manufacturing of Polyurethane (2)> In a 2 L four-neck separable flask equipped with a stirrer, thermometer, heating device, and reflux tubing, 168 g of hydroxylated hydrogenated polybutadiene, 22 g of MDI, 0.15 g of dioctyltin dilaurate, and 1710 g of cyclohexanone were charged at room temperature, and the flask was then purged with nitrogen gas by blowing in nitrogen. These were reacted under uniform stirring conditions at 80°C for 6 hours to obtain a coating solution (2) containing polyurethane (2). The weight-average molecular weight of the obtained polyurethane (2) was measured in the same manner as in Example 1 using the following method.

[0109] <Manufacturing of goods> Except for changing the second agent to coating liquid (2), the article was manufactured and the adhesive strength was measured in the same manner as in Example 1. The results are shown in Table 2.

[0110] (Example 6) Except for changing the low molecular weight polyolefin in the first agent to polypropylene with a weight-average molecular weight of 40,000 and changing the second agent to coating liquid (2), the article was manufactured and its adhesive strength was measured in the same manner as in Example 1. The results are shown in Table 2.

[0111] (Example 7) <Manufacturing of goods> As the first agent, a low molecular weight polypropylene solution (2) was prepared. The low molecular weight polypropylene solution (2) was obtained by charging 0.030 g of low molecular weight polyolefin (Sanwax 171-P, manufactured by Sanyo Chemical Industries, Ltd., weight-average molecular weight 9500) and 30 g of p-xylene into a 50 mL screw-capacity tube, then purging the inside of the screw-cap tube with nitrogen gas, and allowing it to stand for 30 minutes under 80°C conditions to dissolve the low molecular weight polyolefin. In addition, as the second agent, a coating solution (1) containing polyurethane (1) was prepared. The polyethylene substrate and the adherend were bonded using the first and second agents in the following manner. First, the first agent obtained above was applied to a polyethylene substrate (Kobe Polyethylene Sheet EL-N-AN, manufactured by Hitachi Chemical Co., Ltd.) using an applicator, left to stand for 5 minutes at room temperature, and then dried in a hot air dryer at 80°C for 5 minutes to form the first layer with a dry film thickness of 0.20 μm. Next, the second agent was applied onto the first layer using a bar coater, left to stand for 5 minutes at room temperature, and then dried in a hot air dryer at 80°C for 5 minutes to obtain a laminate having a first layer and a second layer with a dry film thickness of 10 μm. A polyethylene terephthalate film (Toyobo Ester Film E5100, manufactured by Toyobo Co., Ltd.) was laminated onto the second layer of the laminate, and then a test specimen was obtained by heat treatment at a specified temperature for 10 minutes. Here, the heat treatment was performed at 120°C or 140°C, and test specimens were prepared for each case.

[0112] <Measuring adhesive strength> The adhesive strength was measured for two types of articles, one with a heat treatment temperature of 120°C and the other with a heat treatment temperature of 140°C, in the same manner as in Example 1. The results are shown in Table 3.

[0113] (Comparative Example 2) <Manufacturing of goods> The article was manufactured in the same manner as in Example 7, except that the first agent was not used. The adhesive strength of the obtained articles was measured in the same manner as in Example 7. The results are shown in Table 3.

[0114] [Table 1]

[0115] [Table 2]

[0116] [Table 3]

[0117] As shown in Tables 1-3, in Comparative Examples 1 and 2, where the adhesive layer was formed using only the second agent without the first agent, high adhesive strength was achieved at high heat treatment temperatures, but the adhesive strength decreased significantly at low heat treatment temperatures. On the other hand, in Examples 1-7, high adhesive strength comparable to the comparative examples was achieved at high heat treatment temperatures, and sufficient adhesive strength was also achieved at low heat treatment temperatures.

Claims

1. A first container containing a first agent containing a low molecular weight polyolefin with a weight-average molecular weight of 45,000 or less, A second container containing a second agent containing a polyurethane having a hydrocarbon group (i) with 40 or more carbon atoms in the main chain, Equipped with, An adhesive kit for forming an adhesive layer on a polyolefin-containing substrate, comprising a first layer containing the low molecular weight polyolefin formed directly on the substrate and a second layer containing the polyurethane formed directly on the first layer.

2. The polyurethane comprises a polyol unit (A) and a polyisocyanate unit (B). The adhesive kit according to claim 1, wherein the polyol unit (A) comprises a first polyol unit (A-1) having the hydrocarbon group (i).

3. The adhesive kit according to claim 2, wherein the content of the first polyol unit (A-1) is 75% by mass or more based on the total amount of the polyol unit (A) and the polyisocyanate unit (B).

4. The adhesive kit according to any one of claims 1 to 3, wherein the hydrocarbon group (i) is an alkanediyl group having 40 or more carbon atoms.

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