JP7458845B2 - Solvent-based adhesive compositions and laminates - Google Patents

Description

The present invention relates to a solvent-based adhesive composition and a laminate.

From the perspective of reducing plastic waste, there is a growing need for paper packaging materials as packaging materials. In such packaging materials, it is usual to provide an adhesive layer that allows materials to be bonded together, particularly a heat-seal adhesive layer that can be bonded by heat.

Water-based adhesive compositions, such as aqueous dispersions containing ethylene/unsaturated carboxylic acid copolymers, that can be used as such adhesive layers have been proposed (see, for example, Patent Document 1).

International Publication No. 2016/076130

The aqueous dispersion described in Patent Document 1 is an excellent aqueous dispersion in that it can provide a heat seal adhesive layer with excellent adhesive strength, and the laminate containing the adhesive layer has excellent blocking resistance. In addition, aqueous adhesive compositions containing the above-mentioned ethylene/unsaturated carboxylic acid copolymer or modified polyolefin resin generally have excellent coating appearance and applicability to substrates such as paper.

However, in the case of an aqueous adhesive composition made of the above-mentioned aqueous dispersion, it is necessary to provide dedicated equipment for using the aqueous adhesive composition. Therefore, if such equipment is not available, it is difficult to use the aqueous adhesive composition. In such cases, it is possible to use a solvent-based adhesive composition instead of the aqueous adhesive composition.

However, the reality is that, particularly for paper base materials, a solvent-based adhesive composition that has excellent physical properties that can be achieved with a water-based adhesive composition has not yet been obtained.
The present invention relates to a solvent-based adhesive composition, which provides an adhesive layer with excellent heat-sealing properties, has an excellent appearance after coating, and has excellent coating properties on substrates such as paper, and the solvent-based adhesive composition. An object of the present invention is to provide a laminate including an adhesive layer obtained from a composition and a base material, a packaging material containing the laminate, and the like.

After extensive research, the inventors discovered that the above problems could be solved by using a coating agent having the following composition, and thus completed the present invention. An example of the composition of the present invention is as follows.

[1] A dispersion (A) in which a polyolefin-based resin (a1) is dispersed in an organic solvent (a2);
A solvent-based adhesive composition comprising: a solution (B) in which a thermoplastic elastomer (b1) is dissolved in an organic solvent (b2).

[2] The solvent-based adhesive composition according to item [1], wherein the polyolefin resin (a1) has a melting point of 95 to 180°C as measured according to JIS K 7122.
[3] The solvent-based adhesive composition according to item [1] or [2], wherein the heat of fusion of the thermoplastic elastomer (b1) measured according to JIS K 7122 is 0 J/g or more and 40 J/g or less.

[4] Part or all of the at least one polymer selected from the group consisting of the polyolefin resin (a1) and the thermoplastic elastomer (b1) is a polymer graft-modified with a polar group-containing monomer. The solvent-based adhesive composition according to any one of [1] to [3].

[5] The solvent-based adhesive composition according to item [4], wherein the polar group-containing monomer is maleic anhydride.
[6] The solvent-based adhesive composition according to any one of items [1] to [5], wherein the mass ratio (a1)/(b1) of the polyolefin resin (a1) to the thermoplastic elastomer (b1) is 20/80 to 95/5.

[7] A laminate comprising a substrate and an adhesive layer laminated on at least one surface of the substrate, the substrate being paper, and the adhesive layer being a layer obtained from the solvent-based adhesive composition described in any one of items [1] to [6].

[8] The laminate according to item [7], wherein the adhesive layer is a heat seal adhesive layer.
[9] A packaging material comprising a laminate comprising item [8].

According to the present invention, there is provided a solvent-based adhesive composition, which provides an adhesive layer with excellent heat-sealing properties, has an excellent appearance after coating, and has excellent coatability on substrates such as paper, and the solvent-based adhesive composition. A laminate comprising an adhesive layer and a base material obtained from the adhesive composition, a packaging material containing the laminate, etc. are obtained.

The present invention will be explained in detail below.
[Solvent-based adhesive composition]
The solvent-based adhesive composition of the present invention includes:
A dispersion (A) in which a polyolefin resin (a1) is dispersed in an organic solvent (a2),
A solution (B) in which a thermoplastic elastomer (b1) is dissolved in an organic solvent (b2) is included.

<Polyolefin resin (a1)>
The polyolefin resin (a1) is a polyolefin resin dispersed in an organic solvent (a2).

The polyolefin resin (a1) is not particularly limited as long as it can be dispersed in the organic solvent (a2). Examples of the polyolefin resin (a1) include ethylene homopolymers, ethylene copolymers, propylene homopolymers, and propylene copolymers.

Among these, at least one propylene selected from the group consisting of ethylene/α-olefin copolymer (a1-1), propylene homopolymer, propylene/ethylene copolymer, and propylene/α-olefin copolymer; At least one selected from the group consisting of polymers (a1-2) is preferred.

The copolymer (a1-1) contains a structural unit derived from ethylene and a structural unit derived from α-olefin. The α-olefin is preferably an α-olefin having 3 or more carbon atoms, more preferably an α-olefin having 3 to 50 carbon atoms.

Examples of the α-olefin having 3 to 50 carbon atoms include propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1 -Pentene, 3,4-dimethyl-1-pentene, 4-methyl-1-hexene, 3-ethyl-1-pentene, 3-ethyl-4-methyl-1-pentene, 3,4-dimethyl-1-hexene , 4-methyl-1-heptene, 3,4-dimethyl-1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, vinylcyclohexane, etc. can be mentioned.

The ethylene-derived structural unit contained in the copolymer (a1-1) is preferably 50 mol% or more and 97 mol% or less, more preferably 60 mol% or more and 95 mol% or less. Further, the α-olefin-derived structural unit contained in the copolymer (a1-1) is preferably 3 mol% or more and 50 mol% or less, more preferably 5 mol% or more and 40 mol% or less. preferable.

The copolymer (a1-1) contains unsaturated monomers other than ethylene and α-olefin (hereinafter referred to as "other unsaturated monomers (1)") to the extent that the effects of the present invention are not impaired. It can also contain structural units derived from. Other unsaturated monomers (1) include, for example, conjugated polyenes such as butadiene and isoprene; 1,4-hexadiene, 1,7-octadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-vinyl Examples include non-conjugated polyenes such as -2-norbornene, 5-methylene-2-norbornene, and 2,5-norbonadiene.

Among the copolymers (a1-1), ethylene/propylene copolymers, ethylene/butene copolymers, and ethylene/1-octene copolymers are preferred.
The propylene/α-olefin copolymer that can be used as the propylene polymer (a1-2) contains structural units derived from propylene and structural units derived from α-olefin. The α-olefin is preferably ethylene or an α-olefin having 4 or more carbon atoms, and more preferably ethylene. The α-olefin having 4 to 50 carbon atoms may be the same as the α-olefin exemplified as the α-olefin having 3 to 50 carbon atoms, which is a constituent unit of the ethylene/α-olefin copolymer (a1-1), other than propylene. α-olefins may be mentioned.

The propylene-derived structural unit contained in the propylene polymer (a1-2) is preferably more than 80 mol% and 100 mol% or less, more preferably 90 mol% or more and 100 mol% or less, and 95 More preferably, it is mol% or more and 100 mol% or less. Further, the structural unit derived from ethylene or an α-olefin having 4 or more carbon atoms that may be contained in the propylene polymer (a1-2) is preferably 0 mol% or more and less than 20 mol%, and 0 mol% or more It is more preferably 10 mol% or less, and even more preferably 0 mol% or more and 5 mol% or less.

The propylene polymer (a1-2) may also contain structural units derived from unsaturated monomers other than propylene, ethylene, and α-olefins having 4 or more carbon atoms (hereinafter referred to as "other unsaturated monomers (2)"), to the extent that the effects of the present invention are not impaired.

Other unsaturated monomers (2) include conjugated dienes similar to other unsaturated monomers (1) that can be the constituent units of the ethylene/α-olefin copolymer (a1-1), Examples include polyenes.

Among the propylene polymers (a1-2), propylene homopolymers and propylene/ethylene copolymers are preferred.
The polyolefin resin (a1) is produced by polymerizing monomers corresponding to the constituent units of the resulting polymer in the presence of a known solid Ti catalyst or metallocene catalyst that is commonly used in the production of polyolefin resins. can get. Examples of metallocene catalysts include metallocene compounds such as rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, organoaluminumoxy compounds such as methylaluminoxane, and triisobutylaluminum. and an organoaluminum compound. A more specific method for producing the polyolefin resin (a1) includes the method described in International Publication No. 2004/87775 pamphlet.

The polyolefin resin (a1) may be a modified polyolefin resin that has been graft-modified with a polar group-containing monomer in part or in whole. By including the modified polyolefin resin in the solvent-based adhesive composition, the adhesive layer obtained from the solvent-based adhesive composition can have a further improved adhesion to a substrate (e.g., paper, etc.).

Examples of the polar group include a group having active hydrogen, and specific examples thereof include a hydroxyl group, an amino group, a carboxyl group, an acid anhydride group, an ester group, and a thiol group.
The polar group-containing monomer may have one type of polar group, or may have two or more types of polar groups. Further, the number of polar groups may be one or two or more.

The polar group-containing monomer may enhance the affinity between the adhesive layer obtained from the solvent-based adhesive composition of the present invention and an adherend such as a base material (for example, paper), thereby enhancing the bond between the adhesive layer and the adherend. A monomer having an acid anhydride group or a carboxyl group is preferable because it can further improve the adhesive strength with the adherent.

The polar group-containing monomer includes hydroxyl group-containing ethylenically unsaturated compounds, amino group-containing ethylenically unsaturated compounds, epoxy group-containing ethylenically unsaturated compounds, unsaturated carboxylic acids and their anhydrides, vinyl ester compounds, vinyl chloride, thiol group-containing ethylenically unsaturated compounds, and derivatives thereof.

Examples of hydroxyl group-containing ethylenically unsaturated compounds include hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxy-3-phenoxy-propyl (meth)acrylate. , 3-chloro-2-hydroxypropyl (meth)acrylate, glycerin mono(meth)acrylate, pentaerythritol mono(meth)acrylate, trimethylolpropane mono(meth)acrylate, tetramethylolethane mono(meth)acrylate, butanediol mono Hydroxyl group-containing (meth)acrylic acid esters such as (meth)acrylate, polyethylene glycol mono(meth)acrylate, 2-(6-hydrohexanoyloxy)ethyl acrylate; 10-undecen-1-ol, 1-octen-3- ol, 2-methanol norbornene, hydroxystyrene, N-methylol acrylamide, 2-(meth)acroyloxyethyl acid phosphate, glycerin monoallyl ether, allyl alcohol, allyloxyethanol, 2-butene-1,4-diol, Examples include glycerin monoalcohol. In addition, (meth)acrylate means acrylate and methacrylate, (meth)acrylic ester means acrylic ester and methacrylic ester, and (meth)acryloyl means acryloyl and methacrylate. It means methacryloyl.

Examples of the amino group-containing ethylenically unsaturated compound include vinyl monomers having at least one type of amino group or substituted amino group as represented by the following formula.
-NR ₁ R ₂
In the above formula, R ₁ is a hydrogen atom, a methyl group or an ethyl group, and R ₂ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, or an alkyl group having 8 to 12 carbon atoms, Preferably it is a 6-9 cycloalkyl group. In addition, examples of R ₂ include groups in which a portion of the alkyl group and cycloalkyl group is substituted with a substituent.

Examples of such amino group-containing ethylenically unsaturated compounds include aminomethyl (meth)acrylate, propylaminoethyl (meth)acrylate, dimethylaminoethyl methacrylate, aminopropyl (meth)acrylate, and phenyl methacrylate. Alkyl ester compounds of acrylic acid or methacrylic acid such as aminomethyl and cyclohexylaminoethyl methacrylate; Vinylamine compounds such as N-vinyldiethylamine and N-acetylvinylamine; acrylamide, methacrylamide, N-methylacrylamide, N-methyl Acrylamide-based compounds or methacrylamide-based compounds such as methacrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide; p-amino Examples include imide compounds such as hexylsuccinimide and 2-aminoethylsuccinimide.

As the epoxy group-containing ethylenically unsaturated compound, a monomer having at least one polymerizable unsaturated bond group and epoxy group in one molecule is used.
Such epoxy group-containing ethylenically unsaturated compounds include, for example, glycidyl esters of unsaturated carboxylic acids such as glycidyl acrylate and glycidyl methacrylate; unsaturated dicarboxylic acids (such as maleic acid, fumaric acid, crotonic acid, and tetrahydrophthalic acid); , itaconic acid, citraconic acid, endo-cis-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic acid (Nadic acid (registered trademark)), endo-cis-bicyclo[2,2, 1] Monoglycidyl ester of hept-5-ene-2-methyl-2,3-dicarboxylic acid (methylnadic acid (registered trademark)) (in the case of monoglycidyl ester, the alkyl group has 1 to 12 carbon atoms), p - Alkyl glycidyl ester of styrene carboxylic acid, allyl glycidyl ether, 2-methylallyl glycidyl ether, styrene-p-glycidyl ether, 3,4-epoxy-1-butene, 3,4-epoxy-3-methyl-1-butene , 3,4-epoxy-1-pentene, 3,4-epoxy-3-methyl-1-pentene, 5,6-epoxy-1-hexene, and vinylcyclohexene monoxide.

Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, norbornene dicarboxylic acid, and bicyclo[2,2,1]heptate. -2-ene-5,6-dicarboxylic acid is mentioned.

Examples of the unsaturated carboxylic anhydride include maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, and bicyclo[2,2,1]hept-2-ene-5,6-dicarboxylic anhydride. can be mentioned.

Examples of vinyl ester compounds include vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl persate, vinyl laurate, vinyl stearate, vinyl benzoate, and vinyl salicylate. , vinyl cyclohexanecarboxylate.

Examples of the thiol group-containing ethylenically unsaturated compound include thiophenol derivatives such as allylmercaptan, 2-vinylbenzylmercaptan, 3-vinylbenzylmercaptan, 4-vinylbenzylmercaptan, and vinylthiophenol.

Examples of the derivatives of the compounds include unsaturated carboxylic acid derivatives other than unsaturated carboxylic acid anhydrides. Examples of unsaturated carboxylic acid derivatives include maleyl chloride, malenylimide, dimethyl maleate, monomethyl maleate, diethyl maleate, diethyl fumarate, dimethyl itaconate, diethyl citraconate, dimethyl tetrahydrophthalate, bicyclo[2,2, 1] dimethyl hept-2-ene-5,6-dicarboxylate.

The polar group-containing monomer may enhance the affinity between the adhesive layer obtained from the solvent-based adhesive composition of the present invention and an adherend such as a base material (for example, paper), thereby enhancing the bond between the adhesive layer and the adherend. Unsaturated carboxylic acids and unsaturated carboxylic acid anhydrides are preferred, unsaturated carboxylic acid anhydrides are more preferred, and maleic anhydride is even more preferred, from the standpoint of further improving the adhesive strength with the adherent.

These polar group-containing monomers can be used alone or in combination.
When the polyolefin resin (a1) is graft-modified with a polar group-containing monomer, the polyolefin resin (a1) replaces the constituent units derived from the polar group-containing monomer with the modified polyolefin resin (a1). ), preferably in an amount of 0.1 to 15% by mass, more preferably 0.2 to 10% by mass, and still more preferably 0.5 to 5% by mass.

The content (modification amount) of these polar group-containing monomers is determined by, for example, the preparation when reacting the raw material unmodified polyolefin resin with the polar group-containing monomer in the presence of a radical initiator, etc. It can be adjusted by ratio.

Further, the amount of modification can be determined by known means such as ¹ H-NMR measurement. As specific NMR measurement conditions, the following conditions can be exemplified.
In the case of ¹ H-NMR measurement, an ECX400 nuclear magnetic resonance apparatus manufactured by JEOL Ltd. was used, the solvent was deuterated orthodichlorobenzene, the sample concentration was 20 mg/0.6 mL, the measurement temperature was 120 °C, and the observation nucleus was The conditions are: ¹ H (400 MHz), the sequence is a single pulse, the pulse width is 5.12 μsec (45° pulse), the repetition time is 7.0 seconds, and the number of integrations is 500 or more. The standard chemical shift is set to 0 ppm for hydrogen in tetramethylsilane, but similar results can also be obtained by setting the peak derived from residual hydrogen in deuterated orthodichlorobenzene to 7.10 ppm as the standard value for chemical shift. be able to. A peak such as ¹ H derived from a functional group-containing compound can be assigned by a conventional method.

In addition, when a monomer having an acidic functional group such as the unsaturated carboxylic acid and its anhydride is used as the polar group-containing monomer, the amount of the functional group introduced into the modified olefin polymer is as follows: For example, it is also possible to use the acid value as the amount. Here, examples of methods for measuring acid value include the following.

(Measurement of acid value)
Basic operation conforms to JIS K2501-2003.
Accurately measure out about 10 g of modified polyolefin resin (a1) and put it into a 200 mL tall beaker. 150 mL of a mixed solvent of xylene and dimethylformamide mixed at a ratio of 1:1 (volume ratio) is added thereto as a titration solvent. Several drops of 1 w/v % phenolphthalein ethanol solution (manufactured by Wako Pure Chemical Industries, Ltd.) are added as an indicator, and the liquid temperature is heated to 80° C. to dissolve the sample. After the liquid temperature becomes constant at 80° C., titration is performed using a 0.1 mol/L potassium hydroxide 2-propanol solution (manufactured by Wako Pure Chemical Industries, Ltd.), and the acid value is determined from the titration amount.

The formula is Acid value (mgKOH/g) = (EP1-BL1) x FA1 x C1/SIZE
It is.

In the above formula, EP1 is the titration amount (mL), BL1 is the blank value (mL), FA1 is the factor of the titrant (1.00), C1 is the concentration conversion value (5.611 mg/mL: equivalent to potassium hydroxide in 1 mL of 0.1 mol/L KOH), and SIZE is the amount of sample taken (g).

This measurement is repeated three times and the average value is taken as the acid value.
The acid value of the modified olefin polymer is preferably 0.1 to 100 mgKOH/g, more preferably 0.5 to 60 mgKOH/g, and still more preferably 0.5 to 30 mgKOH/g. Here, when the polyolefin resin (a1) is a mixture of a graft-modified polyolefin resin and an unmodified polyolefin resin, it is preferable that the mixture as a whole has the above acid value.

In addition, when maleic anhydride is used as the polar group-containing monomer, the amount of grafting is determined based on the absorption of the carbonyl group of maleic anhydride detected at around 1790 cm ^-1 using an infrared spectrophotometer. You can also do that.

There are various methods for graft copolymerizing a polar group-containing monomer to an unmodified raw material polyolefin resin. Such a method includes, for example, a method in which an unmodified raw material polyolefin resin is dissolved in an organic solvent, a polar group-containing monomer and a radical polymerization initiator are added, and the mixture is heated and stirred to cause a graft copolymerization reaction; A method in which a raw material polyolefin resin is heated and melted, a polar group-containing monomer and a radical polymerization initiator are added to the resulting melt, and the mixture is stirred to cause a graft copolymerization reaction; unmodified raw material polyolefin resin, polar A method in which a group-containing monomer and a radical polymerization initiator are mixed in advance, and the resulting mixture is fed to an extruder and subjected to a graft copolymerization reaction while being heated and kneaded; Examples include a method of impregnating a solution prepared by dissolving a radical polymerization initiator and a radical polymerization initiator in an organic solvent, then heating to the highest temperature at which the unmodified raw material polyolefin resin does not dissolve, and causing a graft copolymerization reaction.

The reaction temperature is preferably 50° C. or higher, particularly preferably in the range of 80 to 200° C., and the reaction time is about 1 minute to 10 hours.
The reaction system may be either a batch system or a continuous system, but the batch system is preferred in order to carry out the graft copolymerization uniformly.

The radical polymerization initiator used is not limited as long as it promotes the reaction between the unmodified olefin polymer and the polar group-containing monomer, but organic peroxides and organic peresters are particularly preferred.

Examples of the radical polymerization initiator include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxybenzoate) hexyne-3,1,4 -Bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butyl peracetate, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, 2,5-dimethyl-2,5 -di(tert-butylperoxy)hexane, tert-butyl benzoate, tert-butyl perphenylacetate, tert-butyl perisobutyrate, tert-butyl per-sec-octoate, tert-butyl perpivalate, cumyl perpivalate and organic peroxides such as tert-butylperdiethyl acetate; and azo compounds such as azobis-isobutylnitrile and dimethylazoisobutylnitrile.

Among these, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3,2,5-dimethyl-2,5-di(tert- Dialkyl peroxides such as butylperoxy)hexane and 1,4-bis(tert-butylperoxyisopropyl)benzene are preferred.

The radical polymerization initiator is preferably used in an amount of about 0.001 to 10 parts by weight based on 100 parts by weight of the unmodified raw material polyolefin resin.
The melting point (Tm) of the polyolefin resin (a1) is preferably 95 to 180°C, more preferably 100 to 170°C, and still more preferably 100 to 160°C. When the melting point is within the above range, the obtained dispersion (A) has excellent stability and an adhesive layer having high adhesive strength can be obtained.

In the present invention, Tm is determined by differential scanning calorimetry (DSC measurement) in accordance with JIS K7122, and specifically, after raising the temperature from 30°C to 200°C at 10°C/min and holding it at that temperature for 3 minutes. Then, in the process of lowering the temperature to 0 °C at a rate of 10 °C/min, holding it at that temperature for 3 minutes, and then raising the temperature again to 200 °C at a rate of 10 °C/min, from the thermogram at the second temperature increase, Determined according to JIS K7122.

The polyolefin resin (a1) preferably has a weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) and converted to standard polystyrene, for example, from 10,000 to 1,000,000. The molecular weight distribution (dispersity) is, for example, 1 or more and 3 or less. Note that the molecular weight distribution is the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn). In the present invention, Mw and Mw/Mn can be specifically measured by the method described in the Examples below.
The polyolefin resin (a1) may be used alone or in combination of two or more.

<Organic solvent (a2)>
The dispersion liquid (A) contains an organic solvent (a2) in which the polyolefin resin (a1) is dispersed. When the polyolefin resin (a1) is an unmodified polyolefin resin, the dispersion liquid (A) can be prepared by dispersing the unmodified polyolefin resin in an organic solvent (a2).

Further, when at least a part of the polyolefin resin (a1) contains a graft-modified polymer, the dispersion liquid (A) can be prepared as follows.
As mentioned above, the grafting reaction can be carried out in an organic solvent or without a solvent. When the grafting reaction is carried out in an organic solvent, the polyolefin resin (a1 ) is dispersed in an organic solvent (a2) to prepare a dispersion (A). When the graft reaction is carried out without using an organic solvent, the organic solvent (a2) is added again to prepare the dispersion (A). In addition, when the polyolefin resin (a1) is a mixture of a graft-modified polyolefin resin and an unmodified polyolefin resin, a mixture of these resins prepared in advance and an organic solvent (a2) may be mixed. Alternatively, the dispersion (A) may be prepared by mixing the graft-modified polyolefin resin and the unmodified polyolefin resin in the organic solvent (a2). Good too.

The organic solvent (a2) used to prepare the dispersion liquid (A) is not particularly limited as long as the polyolefin resin (a1) can be maintained in a dispersed state in the organic solvent.
Examples of the organic solvent (a2) include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane, heptane, octane, and decane; cyclohexane, cyclohexene, methylcyclohexane, ethylcyclohexane, and decahydronaphthalene. Alicyclic hydrocarbons such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, phenol, etc.; Ketone solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, isophorone, acetophenone, etc. Cellsolves such as methyl cellosolve and ethyl cellosolve; Esters such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate and butyl formate; Halogenated hydrocarbons such as trichlorethylene, dichloroethylene and chlorobenzene; Normal Examples include paraffinic solvents and isoparaffinic solvents.

Among these, aromatic hydrocarbons, normal paraffin solvents, isoparaffin solvents, alicyclic hydrocarbons, alicyclic hydrocarbon/ester mixed solvents, and alicyclic hydrocarbon/ketone solvent mixed solvents are preferred, since a dispersion liquid (A) having excellent dispersibility of the polyolefin resin (a1) can be obtained, and toluene, methylcyclohexane/ethyl acetate mixed solvent, and methylcyclohexane/methyl ethyl ketone mixed solvent are more preferred.
The organic solvent (a2) may be used alone or in combination of two or more kinds.

The dispersion liquid (A) may optionally contain transition metal compounds such as titanium oxide (rutile type) and zinc oxide, pigments such as carbon black, hydrocarbon synthetic oil, and acetic acid to the extent that the effects of the present invention are not impaired. Additives such as modifiers, thickeners, tackifiers, antifoaming agents, surface conditioners, antisettling agents, antioxidants, weathering agents, heat stabilizers, light stabilizers, pigment dispersants, and antistatic agents are used. May be included.

As mentioned above, the polyolefin resin (a1) is dispersed in the organic solvent (a2). There are no particular restrictions on the dispersion state, but the average particle size of the polyolefin resin (a1) in the dispersion (A) is preferably 1 to 20 μm, more preferably 1 to 18 μm, and even more preferably 1 to 15 μm. Note that the average particle size of the polyolefin resin (a1) can be determined using a Coulter counter.

In consideration of more stable dispersibility of the polyolefin resin (a1), the non-volatile content (components other than the organic solvent (a2)) in the dispersion liquid (A) is preferably 5 to 40 mass%, more preferably 10 to 30 mass%, and even more preferably 15 to 25 mass%.
The content of the polyolefin resin (a1) in the dispersion liquid (A) may be 100% by mass relative to 100% by mass of the nonvolatile content (components other than the solvent) in the dispersion liquid (A).

<Thermoplastic elastomer (b1)>
The thermoplastic elastomer (b1) is dissolved in an organic solvent (b2).

The above thermoplastic elastomer (b1) is not particularly limited as long as it can be dissolved in the organic solvent (b2). Examples of the thermoplastic elastomer (b1) include an olefin-based elastomer (b1-1) and a styrene-based elastomer (b1-2). In addition, a mixture of an olefin-based elastomer (b1-1) and a styrene-based elastomer (b1-2) in any ratio can also be used as the thermoplastic elastomer (b1).

In one preferred embodiment, the thermoplastic elastomer (b1) is a modified thermoplastic elastomer in which part or all of the thermoplastic elastomer is graft-modified with a polar group-containing monomer.
Furthermore, although the measurement conditions will be described in detail below, it is one preferred embodiment that the heat of fusion of the thermoplastic elastomer (b1) is 0 J/g or more and 40 J/g or less.

The number of thermoplastic elastomers (b1) contained in the solution (B) may be one or two or more.
The content of the thermoplastic elastomer (b1) in the solution (B) may be 100% by mass based on 100% by mass of nonvolatile components (components other than the solvent) in the solution (B). In this case, it is preferable to use an olefin elastomer (b1-1) and a styrene elastomer (b1-2) as the thermoplastic elastomer. It is also preferable to use a modified olefin elastomer graft-modified with a polar group-containing monomer and a modified styrenic elastomer graft-modified with a polar group-containing monomer.

When using a mixture of a modified styrenic elastomer graft-modified with a polar group-containing monomer and a modified olefin elastomer graft-modified with a polar group-containing monomer, the weight of the modified olefin elastomer/modified styrenic elastomer The ratio is 60/40 or more, more preferably 55/45 or more, and there is no particular upper limit.
When the content of the thermoplastic elastomer (b1) is within the above range, an adhesive layer having excellent adhesive strength can be easily obtained from the solvent-based adhesive composition of the present invention.

<Olefin elastomer (b1-1)>
Examples of the olefin elastomer (b1-1) include a polymer (b1-1a) derived from an α-olefin having 2 to 20 carbon atoms, and a polymer derived from an unmodified α-olefin having 2 to 20 carbon atoms. It is preferable that the polymer is a modified polymer (b1-1b) graft-modified with a polar group-containing monomer.

[Polymer derived from α-olefin having 2 to 20 carbon atoms (b1-1a)]
The polymer (b1-1a) is not particularly limited as long as it contains a structural unit derived from an α-olefin having 2 to 20 carbon atoms, and may be a polymer consisting of an α-olefin having 4 to 20 carbon atoms. It may be a copolymer obtained using an α-olefin having 4 to 20 carbon atoms and an α-olefin having 2 to 3 carbon atoms, and if necessary, an unsaturated monomer other than the α-olefin (hereinafter referred to as It may also be a polymer containing a structural unit derived from "another unsaturated monomer (3)").

When the polymer (b1-1a) has a structural unit derived from an α-olefin having 4 to 20 carbon atoms, this is preferable in terms of the long-term stability of the solution (B) containing the polymer and the organic solvent (b2) and the excellent adhesive strength of the adhesive layer obtained from the solvent-based adhesive composition of the present invention.

The α-olefin used as a raw material for the polymer (b1-1a) may be used alone or in combination of two or more types. That is, the polymer (b1-1a) may be a homopolymer of an α-olefin having 2 to 20 carbon atoms, or a copolymer obtained using the α-olefin. It may also be a copolymer (b1-1a1) obtained using at least one type of α-olefin having 4 to 20 carbon atoms and one or more α-olefin having 2 to 3 carbon atoms.

Examples of the copolymer (b1-1a1) include random copolymers and block copolymers, with random copolymers being preferred.
Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, and 1-tetradecene. , 1-hexadecene, 1-octadecene, 1-eicosene, and other linear or branched α-olefins.

The α-olefin having 4 to 20 carbon atoms is preferably a linear chain having 4 to 10 carbon atoms, since a polymer having excellent solubility in the organic solvent (b2) and strength can be easily obtained. It is a linear olefin having 4 to 6 carbon atoms, more preferably a linear olefin having 4 to 6 carbon atoms, and it is more preferable that it contains 1-butene, from the viewpoint of obtaining a polymer particularly excellent in the above-mentioned effects. Butene is particularly preferred.

Examples of the α-olefin having 2 to 3 carbon atoms include ethylene and propylene, and propylene is included because a polymer having excellent solubility in the organic solvent (b2) and strength can be easily obtained. is preferred, and propylene is particularly preferred.

The other unsaturated monomer (3) may be the same conjugated dienes as the other unsaturated monomer (1) that can be a constituent unit of the ethylene/α-olefin copolymer (a1-1), or non-conjugated dienes. Examples include conjugated polyenes.

As the polymer (b1-1a), the copolymer (b1-1a1) is preferred from the viewpoint of being able to easily obtain a polymer having excellent solubility in a solvent and strength, and a copolymer of propylene and an α-olefin having 4 to 20 carbon atoms is more preferred, and in particular, a copolymer in which all of the structural units except for the structural units derived from propylene are structural units derived from the α-olefin having 4 to 20 carbon atoms is more preferred, and it is even more preferred that the α-olefin having 4 to 20 carbon atoms contains 1-butene, and a copolymer of 1-butene and propylene is particularly preferred.

In the polymer (b1-1a), the content of the structural units derived from an α-olefin having 4 to 20 carbon atoms is, for example, 5 mol% or more, preferably 10 mol% or more, more preferably 20 mol% or more, relative to 100 mol% of the structural units derived from an α-olefin having 2 to 20 carbon atoms, and preferably relative to 100 mol% of all structural units constituting the polymer (b1-1a), and is, for example, 100 mol% or less, preferably 60 mol% or less, more preferably 50 mol% or less, even more preferably 40 mol% or less, and particularly preferably 35 mol% or less.

When the content ratio of the structural unit derived from an α-olefin having 4 to 20 carbon atoms satisfies the above upper limit, a polymer with better strength can be obtained, and when the content ratio of the constituent units derived from the above lower limit is satisfied, the organic solvent is more A polymer having excellent solubility in (b2) can be obtained.

In the polymer (b1-1a), the content of structural units derived from an α-olefin having 2 to 3 carbon atoms (preferably propylene) is preferably 40 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, particularly preferably 65 mol% or more, relative to 100 mol% of structural units derived from an α-olefin having 2 to 20 carbon atoms, and preferably 100 mol% of all structural units constituting the polymer (b1-1a), and is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 80 mol% or less.

When the content ratio of the structural unit derived from an α-olefin having 2 to 3 carbon atoms satisfies the above-mentioned upper limit, the melting point (Tm) and heat of fusion (ΔH) of the obtained polymer can be lowered, and the above-mentioned When the lower limit is met, a polymer with even higher strength can be obtained.

The heat of fusion (ΔH) of the polymer (b1-1a) is preferably 0 J/g or more, more preferably 3 J/g or more, particularly preferably 5 J/g or more, and preferably 40 J/g or less. , more preferably 35 J/g or less. Further, it is also a preferable form that ΔH is 0 J/g, that is, ΔH is not observed.

The polymer (b1-1a) having the above-mentioned ΔH can be obtained, for example, by appropriately adjusting the content ratio of the structural unit derived from an α-olefin having 2 to 3 carbon atoms in the polymer (b1-1a). I can do it.

When ΔH satisfies the above upper limit, the adhesive layer made of the solvent-based adhesive composition of the present invention has excellent adhesive strength after thermocompression bonding.
In the present invention, ΔH is determined by differential scanning calorimetry (DSC measurement) according to JIS K 7122, and specifically, it is calculated from the peak area of a thermogram obtained during a temperature increase process of 10° C./min. More specifically, in order to cancel the thermal history before measurement, the temperature was raised to 200 °C at a rate of 10 °C/min before measurement, held at that temperature for 3 minutes, and then lowered to 0 °C at a rate of 10 °C/min. After holding at that temperature for 3 minutes, ΔH is measured.

The melting point (Tm) of the polymer (b1-1a) is preferably less than 120°C, more preferably less than 100°C. Moreover, it is also a preferable form that Tm is not observed at 0° C. or higher. The polymer (b1-1a) having the above-mentioned Tm can be obtained, for example, by appropriately adjusting the content ratio of the structural unit derived from an α-olefin having 2 to 3 carbon atoms in the polymer (b1-1a). I can do it.

When Tm satisfies the above condition, an adhesive layer having excellent adhesive strength can be obtained even when the adhesive layer is formed from the solvent-based adhesive composition of the present invention under low-temperature curing conditions.
The weight average molecular weight (Mw) of the polymer (b1-1a), measured by gel permeation chromatography (GPC) and calculated using standard polystyrene, is preferably 1 x 10 ⁴ or more and preferably 1 x 10 ⁷ or less, and the molecular weight distribution (Mw/Mn) is preferably 1 or more and preferably 3 or less.

When Mw or Mw/Mn satisfies the lower limit, an adhesive layer with sufficiently high adhesive strength can be obtained, and the adhesive strength between the adhesive layer and an adherend such as paper can be good. When the upper limit is satisfied, a polymer with good solubility in organic solvent (b2) can be obtained, and a solvent-based adhesive composition that is less likely to solidify or precipitate can be obtained.

The polymer (b1-1a) can be obtained by polymerizing an α-olefin having 2 to 20 carbon atoms in the presence of a known solid Ti catalyst or metallocene catalyst that is commonly used in the production of α-olefin polymers. It can be obtained by Examples of metallocene catalysts include metallocene compounds such as rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, organoaluminumoxy compounds such as methylaluminoxane, and triisobutylaluminum. and an organoaluminum compound. More specifically, the polymer (a) can be obtained, for example, by the method described in International Publication No. 2004/87775.

[Modified polymer (b1-1b)]
As the thermoplastic elastomer (b1), a modified polymer (b1-1b) in which part or all of the unmodified polymer (b1-1a) is graft-modified with a polar group-containing monomer may also be used. This is a preferred form. The modified polymer (b1-1b) is not particularly limited as long as it is a polymer derived from an unmodified α-olefin having 2 to 20 carbon atoms and graft-modified with a polar group-containing monomer. The polymer is preferably a polymer obtained by reacting a monomer having one or more polar group-containing monomers with one or more unmodified polymers.

Regarding specific examples of polar groups and their forms in the modified polymer (b1-1b), as well as specific examples and preferred forms of polar group-containing monomers, see This is the same as the explanation regarding the polar group and the polar group-containing monomer in the case of a graft-modified modified polyolefin resin.

The ΔH of the modified polymer (b1-1b) is preferably 0 J/g or more, more preferably 3 J/g or more, particularly preferably 5 J/g or more, and is preferably 40 J/g or less, more preferably 35 J/g or less, particularly preferably 30 J/g or less. In addition, it is also a preferred embodiment that ΔH is 0 J/g, i.e., ΔH is not observed.

When the ΔH of the modified polymer (b1-1b) satisfies the upper limit specified above, the adhesive layer formed from the solvent-based adhesive composition of the present invention has excellent adhesive strength after thermocompression bonding.
The modified polymer (b1-1b) having the above ΔH can be obtained, for example, by appropriately adjusting the content of structural units derived from an α-olefin having 2 to 3 carbon atoms in the modified polymer (b1-1b).

The Tm of the modified polymer (b1-1b) is preferably less than 120°C, more preferably less than 100°C, even more preferably 90°C or less, particularly preferably 87°C or less, and preferably 40°C or more, more preferably Preferably it is 50°C or higher. Further, it is also a preferable form that Tm is not observed at 0° C. or higher.

When the Tm of the modified polymer (b1-1b) satisfies the upper limit specified above or the condition that the melting point is not observed at 0°C or higher, the adhesive layer made of the solvent-based adhesive composition of the present invention has excellent adhesive strength after thermocompression bonding at low temperatures.

The modified polymer (b1-1b) having the above-mentioned Tm can be obtained by, for example, appropriately adjusting the content ratio of the structural unit derived from an α-olefin having 2 to 3 carbon atoms in the modified polymer (b1-1b). Obtainable.

The half crystallization time of the modified polymer (b1-1b) at 50° C. is preferably 100 seconds or more, more preferably 150 seconds or more, and still more preferably 200 seconds or more. Furthermore, the half-crystallization time also includes cases where crystallization does not substantially occur or the value of the half-crystallization time is too large to be determined, that is, the half-crystallization time is infinite. It will be done.

When the half-crystallization time of the modified polymer (b1-1b) satisfies the above lower limit, the component containing the modified polymer (b1-1b) of the solvent-based adhesive composition of the present invention forms on the surface of the adherend. By penetrating into the irregularities and having an anchor effect, the adhesive strength of the resulting adhesive layer can be further improved.

The half crystallization time can be determined by isothermal crystallization measurement using a differential scanning calorimeter.
The Mw of the modified polymer (b1-1b) measured by GPC and converted to standard polystyrene is preferably 1 x 10 ⁴ or more, more preferably 2 x 10 ⁴ or more, particularly preferably 3 x 10 ⁴ or more. Moreover, it is preferably 1×10 ⁷ or less, more preferably 1×10 ⁶ or less, particularly preferably 5×10 ⁵ or less.

When the Mw of the modified polymer (b1-1b) satisfies the above-mentioned lower limit, the solvent-based adhesive composition of the present invention provides an adhesive layer with sufficiently high adhesive strength and excellent adhesive strength with the adherend. can be easily obtained, and when the above upper limit is satisfied, a modified polymer (b1-1b) can be obtained that has good solubility in the organic solvent (b2) and is less likely to solidify and precipitate. In particular, when the Mw of the modified polymer (b1-1b) is 5×10 ⁵ or less, it is possible to obtain an adhesive layer with superior adhesive strength to the adherend.

Mw/Mn of the modified polymer (b1-1b) is preferably 1 or more, more preferably 1.5 or more, and preferably 3 or less, more preferably 2.5 or less.
When Mw/Mn satisfies the above lower limit, it is possible to obtain a modified polymer (b1-1b) that has good solubility in the organic solvent (b2) and is less likely to solidify and precipitate; When the conditions are satisfied, an adhesive layer having sufficiently high adhesive strength and excellent adhesive strength with an adherend can be easily obtained from the solvent-based adhesive composition of the present invention.

The kinematic viscosity of the modified polymer (b1-1b) at 40°C is preferably over 500,000 cSt. Here, cases where the kinematic viscosity exceeds 500,000 cSt include cases where the fluidity is so low that the kinematic viscosity cannot be measured.

In the present invention, kinematic viscosity at 40°C is measured based on ASTM D 445.
The content ratio (modified amount) of the structural units derived from the polar group-containing monomer in the modified polymer (b1-1b) is preferably based on 100% by mass of the total structural units of the modified polymer (b1-1b). is 0.1% by mass or more, more preferably 0.5% by mass or more, and preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, particularly preferably 4% by mass. % or less, more preferably 2% by mass or less.

When the amount of modification is within the above range, the affinity of the adhesive layer obtained from the solvent-based adhesive composition of the present invention to the adherend is increased, and the adhesive strength between the adhesive layer and the adherend is further improved. can be done.

As a method for producing a modified polymer (b1-1b) by graft copolymerizing a polar group-containing monomer to a polymer derived from an unmodified α-olefin having 2 to 20 carbon atoms, polyolefin resin ( In a1), a method similar to the method of graft copolymerizing a polar group-containing monomer to an unmodified raw material polyolefin resin can be mentioned. Further, the modified polymer (b1-1b) may be synthesized according to a conventional method, for example, as disclosed in International Publication No. 2017/126520.

<Styrenic elastomer (b1-2)>
There are no particular limitations on the type and manufacturing method of the styrenic elastomer (b1-2), and examples thereof include copolymers containing structural units derived from monovinyl aromatic hydrocarbons such as styrene.

Examples of the styrene-based elastomer (b1-2) include copolymers containing monovinyl-substituted aromatic hydrocarbons (styrene-based aromatic hydrocarbons) as copolymerization components. Specific examples include styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-butylene-butadiene-styrene block copolymer (SBBS), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-ethylene copolymer, styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), poly(α-methylstyrene)-polybutadiene-poly(α-methylstyrene) (α-MeSBα-MeS), poly(α-methylstyrene)-polyisoprene-poly(α-methylstyrene) (α-MeSIα-MeS). Furthermore, copolymers in which the conjugated diene portion constituting these copolymers, specifically the structural units derived from butadiene or isoprene, are hydrogenated are also included. Of these, SEBS and SEPS are preferred.

One preferred form of the styrene elastomer (b1-2) is to use a modified styrene elastomer graft-modified with a polar group-containing monomer. This modification can be performed by a conventionally known method. Specific examples of the polar groups in the modified styrenic elastomer and their forms are the same as those described above regarding the polar groups and polar group-containing monomers of the modified polymer (b1-1b).

Examples of the polar group-containing monomer for graft-modifying the styrene elastomer include the polar group-containing monomers described in connection with the modified polymer (b1-1b). Among these, unsaturated carboxylic acids or unsaturated carboxylic acid anhydrides are preferred, unsaturated carboxylic anhydrides are more preferred, and maleic anhydride is even more preferred.

In the modified styrenic elastomer, the content ratio (modification amount) of the structural units derived from the polar group-containing monomer is preferably 0.1% by mass or more, based on 100% by mass of the total structural units of the modified styrene-based elastomer. More preferably 0.5% by mass or more, preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, particularly preferably 4% by mass or less, and even more preferably 3% by mass. % or less.

Commercially available products can also be used as the modified styrene elastomer. Specific examples of the commercially available products include Dynaron 8630P (manufactured by JSR (example)) and Tuftec M1913 (manufactured by Asahi Kasei Corporation).

The ΔH of the styrene elastomer (b1-2) is preferably 0 J/g or more and 40 J/g or less, but in one preferred embodiment, the ΔH is 0 J/g (that is, ΔH is not observed).

When the ΔH of the styrene elastomer (b1-2) satisfies the above conditions, an adhesive layer with excellent adhesive strength can be obtained even if the adhesive layer is formed from the solvent-based adhesive composition of the present invention under low temperature curing conditions. This makes it possible to easily obtain an adhesive layer with excellent adhesive strength.

It is preferable that the Tm of the styrene elastomer (b1-2) is not observed at 0° C. or higher.
When the Tm of the styrene elastomer (b1-2) satisfies the above conditions, even if an adhesive layer is formed from the solvent-based adhesive composition of the present invention under low-temperature curing conditions, a decrease in adhesive strength can be prevented. It is possible to obtain an adhesive layer with excellent adhesive strength and durability.

The Mw of the styrene-based elastomer (b1-2), measured by GPC and converted into standard polystyrene, is preferably 1 x 10 ⁴ or more, more preferably 2 x 10 ⁴ or more, particularly preferably 3 x 10 ⁴ or more, and is preferably 1 x 10 ⁷ or less, more preferably 1 x 10 ⁶ or less, particularly preferably 5 x 10 ⁵ or less.

When the Mw of the styrene elastomer (b1-2) satisfies the lower limit, the solvent-based adhesive composition of the present invention provides an adhesive layer with sufficiently high adhesive strength and excellent adhesive strength with the adherend. can be easily obtained, and when the above upper limit is satisfied, a styrenic elastomer (b1-2) that has good solubility in the organic solvent (b2) and is difficult to solidify and precipitate can be obtained. In particular, when the Mw of the styrene elastomer (b1-2) is 5×10 ⁵ or less, it is possible to obtain an adhesive layer with superior adhesive strength to the adherend.

Mw/Mn of the styrenic elastomer (b1-2) is preferably 1 or more, more preferably 1.5 or more, and preferably 3 or less, more preferably 2.5 or less.
When Mw/Mn satisfies the above lower limit, it is possible to obtain a styrenic elastomer (b1-2) that has good solubility in the organic solvent (b2) and is less likely to solidify and precipitate; When the conditions are satisfied, an adhesive layer having sufficiently high adhesive strength and excellent adhesive strength with an adherend can be easily obtained from the solvent-based adhesive composition of the present invention.

<Organic solvent (b2)>
The solution (B) contains an organic solvent (b2) that dissolves the thermoplastic elastomer (b1). The organic solvent (b2) is not particularly limited as long as it can dissolve the thermoplastic elastomer (b1).

Suitable organic solvents (b2) include, for example, toluene, xylene, methylcyclohexane/methyl isobutyl ketone mixed solvent, methylcyclohexane/methyl ethyl ketone mixed solvent, methylcyclohexane/ethyl acetate mixed solvent, methylcyclohexane/n-propyl acetate mixed solvent, Examples include cyclohexane/methyl ethyl ketone mixed solvent, cyclohexane/ethyl acetate mixed solvent, and cellosolve/cyclohexanone mixed solvent. Among these, methylcyclohexane/methyl ethyl ketone mixed solvent, methylcyclohexane/ethyl acetate mixed solvent, toluene, and xylene are preferred.

<Hydrocarbon-based synthetic oil>
In addition to the thermoplastic elastomer (b1), the solution (B) further contains a hydrocarbon-based adhesive layer, since an adhesive layer with high adhesive strength can be easily obtained from the solvent-based adhesive composition of the present invention. May contain synthetic oil. Note that the hydrocarbon-based synthetic oil is a component other than the thermoplastic elastomer.

One type of hydrocarbon synthetic oil may be used alone, or two or more types may be used.
Examples of the hydrocarbon synthetic oil include polymers of olefins having 2 to 20 carbon atoms. Among these, oligomers obtained by homopolymerizing olefins having 2 to 20 carbon atoms and oligomers obtained by copolymerizing two or more of these olefins are preferred.

Examples of the olefin having 2 to 20 carbon atoms include ethylene, propylene, 1-butene, 1-octene, 1-decene, and 1-dodecene.
The hydrocarbon synthetic oil is preferably an ethylene-based copolymer containing structural units derived from ethylene and structural units derived from an α-olefin having 3 to 20 carbon atoms. The content of the structural units derived from ethylene in the ethylene-based copolymer is preferably 30 mol% or more, more preferably 40 mol% or more, and preferably 70 mol% or less, more preferably 60 mol% or less, relative to 100 mol% in total of the structural units derived from ethylene and the structural units derived from an α-olefin having 3 to 20 carbon atoms.

The hydrocarbon synthetic oil has a kinematic viscosity at 40°C, preferably 30 cSt or more, more preferably 300 cSt or more, more preferably 5,000 cSt or more, preferably 500,000 cSt or less, more preferably 400,000 cSt or less, More preferably, it is 300,000 cSt or less.

Further, the hydrocarbon synthetic oil has a kinematic viscosity at 200°C of preferably 10 cSt or more, more preferably 20 cSt or more, more preferably 30 cSt or more, and preferably 100,000 cSt or less, more preferably 80,000 cSt or less, More preferably, it is 60,000 cSt or less.

When the hydrocarbon synthetic oil has a kinematic viscosity at 40° C. or 200° C. within the above range, an adhesive layer with high adhesive strength can be easily obtained from the solvent-based adhesive composition of the present invention.
When the solution (B) contains a hydrocarbon synthetic oil, the content of the hydrocarbon synthetic oil is preferably 1 part by mass or more, preferably 80 parts by mass, based on 100 parts by mass of the thermoplastic elastomer (b1). Parts by mass or less. When the amount of hydrocarbon-based synthetic oil is within the above range, an adhesive layer having excellent strength and adhesive strength can be easily obtained from the solvent-based adhesive composition of the present invention.

Solution (B) may contain additives such as polar resins, curing agents, curing catalysts, leveling agents, defoamers, antioxidants, heat stabilizers, light stabilizers such as ultraviolet absorbers, plasticizers, surfactants, pigments such as titanium oxide (rutile type), zinc oxide, and carbon black, thixotropic agents, thickeners, tackifiers such as rosin resins and terpene resins, surface conditioners, antisettling agents, weather resistance agents, pigment dispersants, antistatic agents, fillers, organic or inorganic fine particles, antifungal agents, and silane coupling agents, as necessary, within the scope of the invention.

The solution (B) can be prepared by mixing the thermoplastic elastomer (b1) with hydrocarbon-based synthetic oil and other additives, which are included as necessary, to form a solution.
The content of nonvolatile components (components other than the organic solvent (b2)) in the solution (B) is, for example, 5% by mass or more, preferably 10% by mass or more, and, for example, 50% by mass or less, preferably 40% by mass. % or less.

The solvent-based adhesive composition of the present invention is obtained by mixing the dispersion (A) and solution (B). In addition, when preparing a solvent-based adhesive composition, the substances exemplified as additives that can be included in the dispersion (A) or solution (B), and the carbonized Hydrogen-based synthetic oil may also be added.

In a preferred embodiment, at least one polymer selected from the group consisting of polyolefin resin (a1) and thermoplastic elastomer (b1) contained in the solvent-based adhesive composition of the present invention is a polymer graft-modified with a polar group-containing monomer. In this embodiment, one may be a polymer graft-modified with a polar group-containing monomer and the other may be an unmodified polymer (a combination of polyolefin resin (a1) graft-modified with a polar group-containing monomer and unmodified thermoplastic elastomer (b1), or a combination of unmodified polyolefin resin (a1) and thermoplastic elastomer (b1) graft-modified with a polar group-containing monomer). In addition, each of the polyolefin resin (a1) and the thermoplastic elastomer (b1) may be a mixture of a polymer graft-modified with a polar group-containing monomer and an unmodified polymer. Furthermore, both the polyolefin resin (a1) and the thermoplastic elastomer (b1) may be a polymer graft-modified with a polar group-containing monomer.

In the solvent-based adhesive composition obtained in the present invention, the mass ratio (a1)/(b1) of the polyolefin resin (a1) and the thermoplastic elastomer (b1) is preferably 20/80 to 95/5, More preferably 30/70 to 90/10, still more preferably 40/60 to 85/15. When the mass ratio of the polyolefin resin (a1) and the thermoplastic elastomer (b1) is within the above range, a uniform coating film without poor appearance can be obtained when coated on a paper base material.

The nonvolatile content (components other than organic solvent (a2) and (a2), also referred to as solid content) in the solvent-based adhesive composition obtained in the present invention is preferably 15 to 20% by mass, and 15.5 to 19% by mass. It is more preferably 5% by mass, and even more preferably 15.8 to 19% by mass. When the nonvolatile content is within the above range, the solvent-based adhesive composition has good handling properties and is easy to coat.

The type B viscosity (measured temperature: 25° C.) of the solvent-based adhesive composition obtained in the present invention is preferably 65 to 400 mPa·s, more preferably 66 to 350 mPa·s, and even more preferably 70 to 310 mPa·s. When the B-type viscosity is within the above range, the solvent-based adhesive composition has good handling properties and is easy to coat. The B-type viscosity of the present invention is a value measured with a B-type viscometer.

[Laminated body]
A laminate in an embodiment of the present invention (hereinafter also referred to as "a laminate of the present invention") includes a base material and an adhesive layer laminated on at least one surface of the base material, and the adhesive layer is laminated on at least one surface of the base material. The layer is characterized in that it is a layer obtained from the solvent-based adhesive composition of the present invention. The above-mentioned laminate is not particularly limited as long as it has a base material and an adhesive layer obtained from the solvent-based adhesive composition of the present invention, and may have layers other than these.

In the laminate of the present invention, the adhesive layer may be present on one side or both sides of the base material. Further, the adhesive layer may be present on the entire surface of the base material, or may be present on a part of the base material.

The method for producing the laminate of the present invention is not particularly limited, but is preferably a method including a coating film formation step in which an adhesive layer (coating film) is formed on a substrate from the solvent-based adhesive composition obtained by the present invention.

In the method for producing a laminate of the present invention, it is preferable to carry out all the steps at a temperature of 220°C or lower, preferably 200°C or lower, since the laminate can be obtained without impairing the properties of the base material etc. .

The coating film forming step is a method of forming a coating film by applying the solvent-based adhesive composition obtained in the present invention onto a substrate, and removing volatile components of the coating film if necessary. and, immersing a base material in the solvent-based adhesive composition, taking out the base material, and removing volatile matter from the coating film made of the solvent-based adhesive composition adhered to the base material, if necessary, to remove the coating film. A method of forming is preferred.

The coating method is not particularly limited, and examples thereof include die coating, flow coating, spray coating, bar coating, gravure coating, gravure reverse coating, kiss reverse coating, microgravure coating, and roll coating. method, blade coating method, rod coating method, roll doctor coating method, air knife coating method, comma roll coating method, reverse roll coating method, transfer roll coating method, kiss roll coating method, curtain coating method, printing method, etc.

Methods for removing volatile components from the coating film provided on the substrate include, for example, leaving the substrate with the coating film at room temperature (approximately 20° C.) under normal pressure, and leaving the substrate with the coating film under reduced pressure. Examples include a method in which volatile matter contained in the coating film is removed by placing the material on the substrate, and a method in which the base material having the coating film is heated. This heating may be performed in one stage or in two or more stages.

The heating conditions are not particularly limited as long as the volatile components such as organic solvents contained in the solvent-based adhesive composition are volatilized, but the heating temperature is, for example, 220° C. or lower, preferably 200° C. or lower, For example, the temperature is 40° C. or higher, and the heating time is, for example, 3 seconds or more, preferably 1 minute or more, and, for example, 1 hour or less.

The thickness of the adhesive layer may be appropriately set depending on the desired use, and is, for example, 0.2 μm or more, preferably 1 μm or more, and, for example, 100 μm or less, preferably 20 μm or less.

Examples of the base material include a plastic base material, a plastic base metal foil having a metal-deposited film, paper, and nonwoven fabric. Among these, paper is preferred.
There are no particular limitations on the paper that is suitable as a base material for the laminate of the present invention, and any known paper containing pulp as a main component can be used. Examples of pulp that is the main component of paper include chemical pulps such as LBKP (hardwood bleached kraft pulp) and NBKP (softwood bleached kraft pulp); GP (groundwood pulp), PGW (pressurized groundwood pulp), and RMP (refiner mechanical pulp). Mechanical pulp such as pulp), TMP (thermomechanical pulp), CTMP (chemothermomechanical pulp), CMP (chemimechanical pulp), CGP (chemiground pulp); wood pulp such as DIP (deinked pulp); kenaf, bagasse , non-wood pulp such as bamboo, cotton, etc.

These may be used alone or in combination of two or more. For example, a pulp containing 90 to 100% by mass of LBKP (broad-leaved bleached kraft pulp) can be used as the pulp.

Further, the pulp may contain synthetic fibers within a range that does not impair the effects of the present invention.
From the viewpoint of environmental conservation, among the pulps, ECF (Elemental Chlorine Free) pulp, TCF (Total Chlorine Free) pulp, waste paper pulp, and pulp obtained from planted trees are preferable.

The freeness of the pulp is, for example, 200 to 700 ml CSF, preferably 450 to 620 ml CSF, according to the Canadian standard freeness (JIS P 8121:1995 "Pulp freeness test method").

Paper containing filler can also be used as the base paper. Examples of fillers include light calcium carbonate, heavy calcium carbonate, talc, clay, kaolin, calcined clay, titanium dioxide, and aluminum hydroxide. The filler content in the paper is, for example, 1 to 30 parts by weight based on 100 parts by weight of the dry pulp. When light calcium carbonate is included as a filler, the light calcium carbonate may be contained, for example, from 1 to 10 parts by mass per 100 parts by mass of the dry pulp.

In addition to pulp, the paper may contain various known papermaking additives. Examples of papermaking additives include internal paper strength enhancers such as sizing agents and wet strength enhancers; bulk enhancers, retention improvers, drainage improvers, coloring dyes, coloring pigments, fluorescent brighteners, fluorescent decolorizers, and pitch control agents.

Further, the paper serving as the base material may be paper coated with a water-soluble polymer such as starch, polyvinyl alcohol, or polyacrylamide.
There are no particular restrictions on the papermaking method for the paper that serves as the base material, and examples include a Fourdrinier paper machine, a Fourdrinier multilayer paper machine, a cylinder paper machine, a cylinder multilayer paper machine, a Fourdrinier combination multilayer paper machine, and a twin wire paper machine. Paper can be manufactured using various paper machines such as paper machines. Further, the paper used in the laminate of the present invention may be single-layer paper, multi-layer paper, or a laminated product of multiple layers.

In the laminate of the present invention, paper serving as a suitable base material may be provided with one or more coating layers other than the adhesive layer obtained from the solvent-based adhesive composition of the present invention. Examples of such a coating layer include a pigment coating layer obtained from a coating liquid containing a pigment and an adhesive.

As the pigment contained in the pigment coating layer, known pigments used in the coating layer of general coated printing paper can be used, such as calcium carbonate (heavy calcium carbonate, light calcium carbonate, etc.). , kaolin (including clay), calcined clay, talc, magnesium carbonate, barium sulfate, calcium sulfate, titanium dioxide, zinc oxide, zinc sulfate, zinc carbonate, calcium silicate, aluminum silicate, magnesium silicate, diatomaceous earth, aluminum hydroxide, water Inorganic pigments such as magnesium oxide; organic pigments (so-called plastic pigments) such as acrylic resins, styrene resins, vinyl chloride resins, nylon, and resins obtained by copolymerizing the monomers that constitute these resins; It will be done.

As the pigment used in the pigment coating layer, for example, a combination of 20 to 40 parts by mass of kaolin and 60 to 80 parts by mass of heavy calcium carbonate can be used.
Furthermore, as the adhesive used for the pigment coating layer, known adhesives used for the coating layer of general coated printing paper can be used, such as butadiene copolymer latex, crosslinking agent-modified starch, etc. Starches such as , oxidized starch, enzyme-modified starch, esterified starch, etherified starch, cationic starch, and amphoteric starch; water-soluble polymers such as gelatin, casein, soy protein, and polyvinyl alcohol; vinyl acetate, ethylene vinyl acetate, Examples include synthetic resins such as polyurethane resins, acrylic resins, polyester resins, and polyamide resins.

The blending ratio of the pigment and adhesive in the pigment coating layer is not particularly limited, but is preferably 5 to 50 parts by weight of the adhesive per 100 parts by weight of the pigment. For example, an adhesive combination of 1 to 5 parts by weight of phosphated starch and 5 to 15 parts by weight of styrene-butadiene latex can be used for 100 parts by weight of pigment.

The pigment coating layer may contain various auxiliary agents as long as they do not impair the effects of the present invention, such as viscosity modifiers, softeners, brightening agents, water resistance agents, dispersants, flow modifiers, etc. , an ultraviolet absorber, a stabilizer, an antistatic agent, a crosslinking agent, a sizing agent, an optical brightener, a coloring agent, a pH adjuster, an antifoaming agent, a plasticizer, and a preservative.

Further, the coating amount of the coating liquid for producing such a pigment coating layer is, for example, 2 to 40 g/m ² in terms of solid content per one side of the base paper.
In one embodiment of the paper-based laminate (for example, packaging paper) of the present invention, the adhesive layer obtained from the solvent-based adhesive composition of the present invention is applied to the pigment coating provided on the paper. In another embodiment, the pigment coating layer may be provided on only one side of the paper, and the adhesive may be provided on the other side where the pigment coating layer is not provided. Layers may be provided.

The adhesive layer obtained from the solvent-based adhesive composition of the present invention can be suitably used as a heat-sealable adhesive layer that can be welded by heat.
For example, when the laminate of the present invention is a laminate having a heat-sealable adhesive layer obtained from the solvent-based adhesive composition of the present invention, there are no particular restrictions on the method of thermocompression bonding this laminate to an adherend. For example, thermocompression bonding can be performed by a conventionally known method. For example, thermocompression bonding (heat sealing) can be carried out by superimposing an adherend on the adhesive layer (heat-sealing adhesive layer) included in the laminate of the present invention and then applying heat and pressure.

Further, the laminates of the present invention may be bonded together by thermocompression. In such a case, the adhesive layers (heat-seal adhesive layers) included in the laminate of the present invention may be stacked on top of each other and then heated and pressurized.

The heating temperature during thermocompression bonding is, for example, 80°C or higher, preferably 100°C or higher, and, for example, 250°C or lower, preferably 200°C or lower. Further, the pressure during thermocompression bonding is, for example, 50 kPa or more, preferably 100 kPa or more, and, for example, 500 kPa or less, preferably 300 kPa or less.

Thereby, when the laminate of the present invention has a heat-seal adhesive layer, the laminate is thermocompression bonded (heat-sealed).
In addition, in this way, a laminate in which an adherend layer is laminated on one surface of the adhesive layer included in the laminate of the present invention (in other words, an adherend layer laminated on one surface of the adhesive layer) A laminate including a body layer) is included in the laminate of the present invention regardless of its thermocompression bonding state (that is, before or after heat sealing).

The laminate of the present invention has an adhesive layer obtained from the solvent-based adhesive composition of the present invention that has excellent heat sealability and also has an excellent appearance after coating. Therefore, it is suitably used as a packaging material in various industrial fields.

Items to be packaged with the packaging material containing the laminate of the present invention are not particularly limited, and include, for example, foods such as confectionery, tea leaves, and spices; aromatic substances such as tobacco and aromatic wood; pharmaceuticals, paper, etc. Various industrial products can be mentioned.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.
1. Physical properties of polymers
The physical properties of the polyolefin resins and thermoplastic elastomers synthesized in Production Examples 1-1 to 1-6, and the hydrocarbon synthetic oil (C-1) synthesized in Production Example 2-1 were measured as follows.

<Content ratio of structural units derived from propylene, ethylene and 1-butene>
The content ratios of structural units derived from propylene, ethylene, and 1-butene in the polymers obtained in the following production examples were determined using ¹³ C-NMR. The results are shown in Table 1.

<Measurement of melting point and heat of fusion>
The melting point and heat of fusion were determined using a differential scanning calorimeter (manufactured by TA Instruments; DSC-Q1000). After raising the temperature from 30 °C to 200 °C at 10 °C/min, holding it at 200 °C for 3 minutes, lowering the temperature at 10 °C/min to 0 °C, and raising the temperature again to 200 °C at 10 °C/min, 2. The melting point and heat of fusion were determined according to JIS K 7122 from the thermogram obtained during the second temperature rise. The results are shown in Table 1.

<Measurement of the amount of modification of the polar group-containing monomer (content of structural units derived from the polar group-containing monomer)>
Determined from ¹ H-NMR measurement. The specific method is as described above. The results are shown in Table 1.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) was measured using gel permeation chromatography (manufactured by Shimadzu Corporation; LC-10 series) under the following conditions.

・Detector: Shimadzu Corporation; C-R4A
・Column: TSKG 6000H-TSKG 4000H-TSKG 3000H-TSKG 2000H (manufactured by Tosoh Corporation)
・Mobile phase: Tetrahydrofuran ・Temperature: 40℃
・Flow rate: 0.8ml/min
Mw was calculated using a calibration curve created from monodisperse standard polystyrene. The results are shown in Table 1.

<Measurement of kinetic viscosity>
The kinematic viscosities at 40° C. and 200° C. were determined according to ASTM D 445. The results are shown in Table 1.

2. Synthesis of polymer [Production Example 1-1] Synthesis of polyolefin resin (a1-1) In an autoclave with an internal volume of 1.5 L equipped with a stirrer, 78 mol% of ethylene units and 22 mol% of 1-octene units were added. 100 parts by mass of ethylene/1-octene copolymer and 435 parts by mass of toluene were added, and the temperature was raised to 140°C while stirring to completely dissolve the ethylene/1-octene copolymer in toluene. A toluene solution of an octene copolymer was obtained. While this solution was kept at 140° C., 16 parts by mass of maleic anhydride and 1.5 parts by mass of dicumyl peroxide were simultaneously added dropwise over 4 hours while stirring. After the dropwise addition was completed, the mixture was further stirred at 140° C. for 1 hour to carry out a post-reaction, and a solution containing polyolefin resin (a1-1) was obtained. Next, this solution containing polyolefin resin (a1-1) was cooled to room temperature, and acetone was added to the solution to precipitate polyolefin resin (a1-1). The precipitated polyolefin resin (a1-1) was repeatedly washed with acetone and then dried to recover the polyolefin resin (a1-1). The melting point of the polyolefin resin (a1-1) is 105°C, and the amount of modification of maleic anhydride (content of structural units derived from maleic anhydride) in the polyolefin resin (a1-1) is 0.9% by mass. , Mw was 100,000.

[Production Example 1-2] Synthesis of thermoplastic elastomer (b1-1) 3 kg of Kraton G1652M (SEBS) was added to 10 L of toluene, and the temperature was raised to 145°C under a nitrogen atmosphere to dissolve the copolymer in toluene. Ta. Furthermore, 382 g of maleic anhydride and 175 g of di-tert-butyl peroxide were fed into the system over 4 hours while stirring, followed by stirring at 145° C. for 2 hours. After cooling, a large amount of acetone was added to precipitate the modified copolymer, which was filtered, washed with acetone, and then vacuum dried.

The melting point and heat of fusion of the obtained maleic anhydride-modified SEBS (thermoplastic elastomer (b1-1)) were not observed, and the Mw was 100,000. The amount of modification of maleic anhydride (content of structural units derived from maleic anhydride) in the thermoplastic elastomer (b1-1) was 2% by mass.

[Production Example 1-3] Synthesis of thermoplastic elastomer (b1-2) Into a 2-liter autoclave that was sufficiently purged with nitrogen, 900 ml of hexane and 90 g of 1-butene were charged, 1 mmol of triisobutylaluminum was added, and the mixture was heated to 70°C. After raising the temperature, propylene was supplied to make the total pressure 7 kg/cm ² G, and 0.30 mmol of methylaluminoxane and rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride were added. 0.001 mmol in terms of Zr atoms was added, and polymerization was carried out for 30 minutes while keeping the total pressure at 7 kg/cm ² G by continuously supplying propylene. After polymerization, the polymer was degassed and recovered in a large amount of methanol, and dried under reduced pressure at 110° C. for 12 hours. The resulting propylene/1-butene copolymer (thermoplastic elastomer (b1-2)) had a melting point of 78.3°C, a heat of fusion of 29.2 J/g, an Mw of 330,000, and a propylene unit content of 67. 2 mol%, and the 1-butene unit content was 32.8 mol%.

[Production Example 1-4] Synthesis of thermoplastic elastomer (b1-3) 3 kg of the above propylene/1-butene copolymer (thermoplastic elastomer (b1-2)) was added to 10 L of toluene, and the mixture was heated at 145°C under a nitrogen atmosphere. The copolymer was dissolved in toluene. Furthermore, 382 g of maleic anhydride and 175 g of di-tert-butyl peroxide were supplied to the system over 4 hours while stirring, and stirring was continued at 145° C. for 2 hours. After cooling, a large amount of acetone was added to precipitate the modified copolymer, which was filtered, washed with acetone, and then vacuum dried.

The resulting maleic anhydride-modified propylene/1-butene copolymer (thermoplastic elastomer (b1-3)) had a melting point of 75.8°C, a heat of fusion of 28.6 J/g, and an Mw of 110,000. The amount of acid modification (content of structural units derived from maleic anhydride) was 1% by mass.

[Production Example 1-5] Synthesis of polyolefin resin (a1-2) In an autoclave with an internal volume of 1.5 L equipped with a stirrer, propylene/propylene containing 99.25 mol% of propylene units and 0.75 mol% of ethylene units was added. 100 parts by mass of ethylene copolymer and 435 parts by mass of toluene were added, and the temperature was raised to 140°C while stirring to completely dissolve the propylene/ethylene copolymer in toluene. While this solution was maintained at 140° C., 16 parts by mass of maleic anhydride and 1.5 parts by mass of dicumyl peroxide were simultaneously added dropwise over 4 hours while stirring. After the dropwise addition was completed, the mixture was further stirred at 140° C. for 1 hour to carry out a post-reaction, and a solution containing polyolefin resin (a1-2) was obtained. Next, this solution containing polyolefin resin (a1-2) was cooled to room temperature, and acetone was added to the solution to precipitate polyolefin resin (a1-2). The precipitated polyolefin resin (a1-2) was repeatedly washed with acetone and then dried to recover the polyolefin resin (a1-2). The melting point of the polyolefin resin (a1-2) is 157°C, and the amount of modification of maleic anhydride (content of structural units derived from maleic anhydride) in the polyolefin resin (a1-2) is 1.1% by mass. , Mw was 90,000.

[Production Example 1-6] Synthesis of polyolefin resin (a1-3) 100 parts by mass of a propylene/ethylene copolymer containing 99.25 mol% of propylene units and 0.75 mol% of ethylene units was added to 96.5 mol of propylene units. Same as Production Example 1-5, except that 100 parts by mass of propylene/ethylene copolymer with % and 3.5 mol% ethylene units was used, and 16 parts by mass of maleic anhydride was changed to 30 parts by mass. A polyolefin resin (a1-3) was obtained. The melting point of the polyolefin resin (a1-3) is 141°C, and the amount of modification of maleic anhydride (content of structural units derived from maleic anhydride) in the polyolefin resin (a1-3) is 2.1% by mass. , Mw was 95,000.

[Production Example 2-1] Synthesis of hydrocarbon synthetic oil (C-1) 1 liter of dehydrated hexane was added to a continuous polymerization reactor equipped with a stirring blade that had been sufficiently purged with nitrogen, and ethylaluminum sesquis whose concentration was adjusted to 96 mmol/L was added. After continuously supplying a hexane solution of chloride (Al(C ₂ H ₅ ) _1.5 ·Cl _1.5 ) at a rate of 500 ml/h for 1 hour, VO(OC ₂ H ₅ )C adjusted to 16 mmol/l as a catalyst was added. ₁₂ of hexane solution was continuously supplied at 500 ml/h, and hexane was continuously supplied at 500 ml/h. On the other hand, the polymerization liquid was continuously drawn out from the upper part of the polymerization vessel so that the polymerization liquid in the polymerization vessel was always 1 liter. Next, 47 l/h of ethylene gas, 47 l/h of propylene gas, and 20 l/h of hydrogen gas were supplied using bubbling pipes. The copolymerization reaction was carried out at 35° C. by circulating a refrigerant through a jacket attached to the outside of the polymerization vessel. The obtained polymerization solution was deashed with hydrochloric acid, poured into a large amount of methanol to precipitate it, and then dried under reduced pressure at 130° C. for 24 hours.

The resulting ethylene/propylene copolymer (hydrocarbon synthetic oil (C-1)) had an ethylene unit content of 55.9 mol%, a propylene unit content of 44.1 mol%, an Mw of 14,000, and a temperature of 40°C. The kinematic viscosity was 37,500 cSt, and the kinematic viscosity at 200°C was 132 cSt.

3. Preparation of coating material [Example 1]
In an autoclave equipped with a stirrer, 15 g of the polyolefin resin (a1-1) obtained in Production Example 1-1 and 85 g of a mixed solvent of ethyl acetate/methylcyclohexane = 5.5/4.5 (mass ratio) were placed, and the polyolefin resin (a1-1) was completely dissolved by heating to 130 ° C. Then, the mixture was gradually cooled with stirring to obtain a coating material K (dispersion (A-1)) in which a polyolefin resin having an average particle size of 12 μm was dispersed in a solvent with a non-volatile content (solid content) of 15% by mass and a uniform milky white color. The average particle size was measured with a Coulter counter.

Next, 20 g of the thermoplastic elastomer (b1-1) obtained in Production Example 1-2 was heated and dissolved in 80 g of a mixed solvent of methylcyclohexane/methyl ethyl ketone = 6/4 (mass ratio), so that the thermoplastic elastomer was dissolved in the solvent. Coating material J (solution (B-1)) was prepared.

Finally, 30 g of coating material K (dispersion (A-1)) and 70 g of coating material J (solution (B-1)) were mixed to prepare coating material A (solvent-based adhesive composition (1)). . The nonvolatile content (solid content) of the obtained coating material A (solvent-based adhesive composition (1)) was 18.5% by mass, and the type B viscosity (measured temperature: 25°C) was 270 mPa·s.

[Example 2]
50 g of coating material K (dispersion liquid (A-1)) obtained in Example 1 and 50 g of coating material J (solution (B-1)) were mixed, and coating material B (solvent-based adhesive composition (2)) was prepared. adjusted. The nonvolatile content (solid content) of the obtained coating material B (solvent-based adhesive composition (2)) was 17.5% by mass, and the type B viscosity (measured temperature: 25°C) was 170 mPa·s.

[Example 3]
70 g of coating material K (dispersion liquid (A-1)) obtained in Example 1 and 30 g of coating material J (solution (B-1)) were mixed, and coating material C (solvent-based adhesive composition (3)) was prepared. adjusted. The nonvolatile content (solid content) of the obtained coating material C (solvent-based adhesive composition (3)) was 16.5% by mass, and the B type viscosity (measured temperature: 25°C) was 100 mPa·s.

[Example 4]
16 g of the thermoplastic elastomer (b1-3) obtained in Production Example 1-4 and 4 g of the hydrocarbon synthetic oil (C-1) obtained in Production Example 2-1 were mixed in methylcyclohexane/ethyl acetate = 8/2 (mass ratio ) was heated and dissolved in 80 g of a mixed solvent to prepare coating material I (solution (B-2)).

Next, 70 g of coating material K (dispersion liquid (A-1)) obtained in Example 1 and 30 g of coating material I (solution (B-2)) were mixed, and coating material D (solvent-based adhesive composition (4)) was adjusted. The nonvolatile content (solid content) of the obtained coating material D (solvent-based adhesive composition (4)) was 16.5% by mass, and the B type viscosity (measured temperature: 25°C) was 70 mPa·s.

[Example 5]
Coating material .

Next, 70 g of coating material K (dispersion liquid (A-1)) obtained in Example 1 and 30 g of coating material X (solution (B-3)) were mixed, and coating material E (solvent-based adhesive composition) was mixed. (5)) was adjusted. The nonvolatile content (solid content) of the obtained coating material E (solvent-based adhesive composition (5)) was 16.5% by mass, and the B type viscosity (measured temperature: 25°C) was 300 mPa·s.

[Example 6]
In an autoclave equipped with a stirrer, put 5.5 g of the polyolefin resin (a1-2) obtained in Production Example 1-5, 12.5 g of the polyolefin resin (a1-3) obtained in Production Example 1-6, and 82 g of toluene. The thermoplastic resin was completely dissolved by heating to 130°C. Thereafter, the coating material Y (dispersion liquid (A-2)), in which a polyolefin resin with an average particle size of 10 μm and a uniform milky white color with a nonvolatile content (solid content) of 18% by mass is dispersed in a solvent, is gradually cooled while stirring. ) was obtained.

Next, 70 g of coating material Y (dispersion (A-2)) and 30 g of coating material J (solution (B-1)) obtained in Example 1 were mixed, and coating material F (solvent-based adhesive composition) was mixed. (6)) was prepared. The nonvolatile content (solid content) of the obtained coating material F (solvent-based adhesive composition (6)) was 18.6% by mass, and the B type viscosity (measured temperature: 25°C) was 120 mPa·s.

[Example 7]
85 g of coating material K (dispersion liquid (A-1)) obtained in Example 1 and 15 g of coating material J (solution (B-1)) were mixed, and coating material G (solvent-based adhesive composition (7)) was prepared. was prepared. The nonvolatile content (solid content) of the obtained coating material G (solvent-based adhesive composition (7)) was 15.8% by mass, and the B-type viscosity (measured temperature: 25°C) was 75 mPa·s.

[Comparative example 1]
28 g of the thermoplastic elastomer (b1-3) obtained in Production Example 1-4 and 7 g of the hydrocarbon synthetic oil (C-1) obtained in Production Example 2-1 were mixed in methylcyclohexane/ethyl acetate = 8/2 (mass ratio ) was heated and dissolved in 65 g of a mixed solvent to prepare coating material H (adhesive composition (1')). The nonvolatile content (solid content) of the obtained coating material H (adhesive composition (1')) was 35.0% by mass, and the B type viscosity (measured temperature: 25°C) was 1000 mPa·s.

[Comparative example 2]
Coating material I (solution (B-2)) obtained in Example 4 was used as it was as an adhesive composition (2'). The nonvolatile content (solid content) of coating material I (adhesive composition (2')) was 20.0% by mass, and the B type viscosity (measurement temperature: 25°C) was 120 mPa·s.

[Comparative Example 3]
The coating material J (solution (B-1)) obtained in Example 1 was used as it was as adhesive composition (3'). The non-volatile content (solid content) of coating material J (adhesive composition (3')) was 20.0 mass%, and the B-type viscosity (measurement temperature: 25 ° C.) was 420 mPa s.

[Comparative example 4]
Coating material K (dispersion A-1) obtained in Example 1 was used as it was as an adhesive composition (4'). The nonvolatile content (solid content) of coating material K (adhesive composition (4')) was 15.0% by mass, and the B type viscosity (measurement temperature: 25°C) was 65 mPa·s.

[B type viscosity]
The B-type viscosity (Brookfield viscosity) of the coating material (adhesive composition) used in the examples was determined by Toki Sangyo Co., Ltd. after the coating material was placed in a water bath controlled at 25°C for 3 hours. The measurement temperature was 25° C. using a B-type viscometer (model BL) manufactured by Manufacturer Co., Ltd. The value 1 minute after the start of viscosity measurement was defined as the Brookfield viscosity of the sample.

[Average particle size]
The average particle size of the coating material (adhesive composition) used in the examples was determined by filtering the coating material through a 100μ filter paper, and then dissolving the filtration residue in a mixed solution of 0.9 g of sodium chloride, 100 ml of distilled water, and 140 ml of isopropanol. After ultrasonic dispersion for a minute, measurement was performed using Multisizer 4 manufactured by Beckman Coulter. The median diameter of the obtained volume statistics was defined as the average particle diameter.

[Measurement of Paper/Paper Adhesion Strength]
The coating materials (adhesive compositions) of Examples 1 to 7 and Comparative Examples 1 to 4 were applied to the paper substrate, and the coating was heated at 100°C for 1 minute to remove volatiles from the coating, to prepare paper having a heat-seal adhesive layer (thickness of the adhesive layer after heating: about 3 μm). The heat-seal adhesive layers were overlapped, and thermocompression bonding (heat sealing) was performed at 0.15 MPa for 1 second under three conditions of lamination temperatures of 120°C, 140°C, and 160°C. Then, a test piece was prepared by cutting into a width of 15 mm, and a 90° peel test was performed on this test piece using a universal tensile measuring device at a crosshead speed of 50 mm/min to measure the adhesive strength of paper/paper. The measurement was performed three times, and the average value was calculated, which was taken as the adhesive strength.

[Adhesiveness]
The paper/paper adhesive strength was measured under three bonding temperatures of 120° C., 140° C., and 160° C., and was judged based on the following criteria.
◎: All surface layer destruction 〇: Average adhesive strength is 2N/15mm or more △: Average adhesive strength is less than 2N/15mm, greater than 0N/15mm ×: Average adhesive strength is 0N/15mm, or coating material is uniform cannot be coated

[Coating appearance]
The coating materials (adhesive compositions) of Examples 1 to 7 and Comparative Examples 1 to 4 were applied to paper, and heated at 100°C for 1 minute to remove volatile components from the coating film to form a heat-seal adhesive layer. (The thickness of the adhesive layer after heating is approximately 3 μm). The boundary between the coated surface and the non-coated surface and the back surface were visually evaluated and judged according to the following criteria.
◎: The boundary between the coated and non-coated surfaces is almost invisible, and there is no seepage into the back side. 〇: The boundary between the coated and non-coated surfaces is visible, but there is almost no seepage into the back side. △: There is no seepage into the back side. The boundaries of the coated surface are clearly visible, and there is seepage to the back side. ×: The coating material cannot be applied evenly.

[Paper coating properties]
The viscosity of the coating materials (adhesive compositions) of Examples 1 to 7 and Comparative Examples 1 to 4 and the speed at which the coating materials spread when applied to paper were evaluated and judged according to the following criteria.
◎: Low viscosity, coating material wets and spreads evenly quickly when applied to paper. 〇: Medium viscosity, coating material wets and spreads evenly somewhat quickly when applied to paper. △: High viscosity, coating material wets and spreads evenly slowly when applied to paper. ×: Coating material cannot be applied evenly.

In the column of organic solvents in Table 2, the numbers in parentheses in the case of mixed solvents indicate the mass ratio of each solvent.

Each symbol in Table 3 is an abbreviation as follows.
EOR: Ethylene/1-octene copolymer SEBS: Styrene-ethylene-butylene-styrene block copolymer PER: Propylene/ethylene copolymer PBR: Propylene/1-butene copolymer EPR: Ethylene/propylene copolymer

Claims (8)

A solvent obtained by mixing a dispersion (A) in which a polyolefin resin (a1) is dispersed in an organic solvent (a2) and a solution (B) in which a thermoplastic elastomer (b1) is dissolved in an organic solvent (b2). adhesive composition,
Part or all of the at least one polymer selected from the group consisting of the polyolefin resin (a1) and the thermoplastic elastomer (b1) is selected from the group consisting of unsaturated carboxylic acids and unsaturated carboxylic acid anhydrides. is a polymer graft-modified with at least one polar group-containing monomer ,
Solvent-based adhesive composition. The solvent-based adhesive composition according to claim 1, wherein the polyolefin resin (a1) has a melting point of 95 to 180°C as measured according to JIS K 7122. The solvent-based adhesive composition according to claim 1 or 2, wherein the heat of fusion of the thermoplastic elastomer (b1) measured according to JIS K 7122 is 0 J/g or more and 40 J/g or less. The solvent-based adhesive composition according to any one of claims 1 to 3, wherein the polar group-containing monomer is maleic anhydride. The solvent system according to any one of claims 1 to 4 , wherein the mass ratio (a1)/(b1) of the polyolefin resin (a1) and the thermoplastic elastomer (b1) is 20/80 to 95/5. Adhesive composition. A laminate comprising a substrate and an adhesive layer laminated on at least one surface of the substrate, the substrate being paper, and the adhesive layer being a layer obtained from the solvent-based adhesive composition according to any one of claims 1 to 5 . The laminate according to claim 6 , wherein the adhesive layer is a heat seal adhesive layer. A packaging material comprising the laminate according to claim 7 .