JP7443763B2 - Adhesive composition and laminate - Google Patents

Description

The present invention is a film having excellent adhesive properties that is suitably used when manufacturing laminates for packaging of foods, medicines, cosmetics, detergents, miscellaneous goods, etc. by laminating a plurality of various plastic films and metallized films. The present invention relates to a solvent-based adhesive composition. Furthermore, the present invention relates to a laminate used for packaging foods, medicines, cosmetics, detergents, miscellaneous goods, etc.

In recent years, composite materials have been used as packaging materials for foods, medicines, cosmetics, detergents, miscellaneous goods, etc. by laminating multiple layers of metal foil such as aluminum foil or metallized film with plastic films such as polyethylene, polypropylene, vinyl chloride, polyester, and nylon. something is being used. As adhesives for bonding these plastic films and metal foils or metallized films, there are known adhesives made of polyols and organic isocyanate compounds reacted with aromatic polycarboxylic anhydrides.

Conventionally, solvent-based laminating adhesives used for laminated composite films containing metal foils or metal-deposited films include two-component curing adhesives containing a polyol compound as a main ingredient and a polyisocyanate compound as a curing agent. is suitably used, and for the purpose of imparting adhesion to metal foil or metal-deposited film, acid groups are introduced to the molecular terminals by reacting polyol compounds with acid anhydrides, and phosphoric acid, phosphoric acid, etc. are used as additives. A method of using a silane coupling agent in combination is widely known.
In addition, in order to react a polyol compound and an acid anhydride, a high temperature reaction of 100°C or higher is required, and if a polyether polyol compound is used as a polyol compound, there is a risk of decomposition of the main chain and unreacted substances remaining. Therefore, a method is mainly selected in which an acid group is introduced at the end of a polyester polyol compound using an acid anhydride. As the acid anhydride, a substance having an aromatic ring in the compound, such as phthalic anhydride and trimellitic anhydride, is preferably selected.

However, when an acid group having an aromatic ring is introduced at the end of the polyol base resin, curing is accelerated due to the urethanization catalytic effect of the acid group, and the viscosity increases sharply after the base resin and curing agent are blended, resulting in poor workability. occurs. This problem is particularly noticeable in solvent-free adhesive compositions.

To address the above issues, Patent Document 1 improves workability by limiting the terminal hydroxyl groups of a polyol acid-modified with an acid anhydride to secondary and tertiary groups and suppressing reactivity due to the effect of steric hindrance. A two-component curable solvent-free adhesive composition is described.

Japanese Patent Application Publication No. 2005-089734

However, the laminate using the adhesive composition described in Patent Document 1 has a problem that lifting occurs when the heat-sealed portion is bent because of poor metal adhesion and heat resistance. In addition, the main polyol compound is specified as a polyester polyol compound, and a solution using a polyether polyol compound is not described.
Therefore, an object of the present invention is to provide an adhesive which is not limited to polyester polyol as a base material, has excellent workability because the increase in viscosity after blending the base material and a curing agent is suppressed, and has excellent resistance to bending and lifting of the heat-sealed part. An object of the present invention is to provide a drug composition. Another object of the present invention is to provide a laminate that uses the adhesive composition and has excellent resistance to bending and lifting of the heat-sealed portion.

As a result of intensive studies to solve the above problems, it was discovered that the above problems could be solved by the embodiments shown below, and the present invention was completed.

An embodiment of the present invention includes a polyol component, a polyisocyanate component, and an aliphatic hydroxy acid, and the content of the aliphatic hydroxy acid is 0.1% by mass with respect to the total mass of the polyol component and the polyisocyanate component. The present invention relates to an adhesive composition in which the content is 5.0% by mass or less.

In another embodiment of the present invention, the aliphatic hydroxy acid is at least one selected from the group consisting of glycolic acid, lactic acid, glyceric acid, hydroxybutyric acid, tartronic acid, malic acid, tartaric acid, and citric acid. The present invention relates to adhesive compositions.

Another embodiment of the present invention relates to the adhesive composition, wherein the aliphatic hydroxy acid has 10 or less carbon atoms.

Another embodiment of the present invention relates to the above adhesive composition, wherein the polyisocyanate component comprises an aromatic polyisocyanate or a derivative thereof.

Another embodiment of the present invention relates to a laminate in which an adhesive layer made of the adhesive composition described above is laminated between at least two sheet-like base materials.

ADVANTAGE OF THE INVENTION According to the present invention, an adhesive composition can be provided which has excellent workability since the increase in viscosity after blending the base resin and the curing agent is suppressed, and which has excellent resistance to bending and lifting of the heat-sealed portion. Further, according to the present invention, it is possible to provide a laminate that uses the adhesive composition and has excellent resistance to bending and lifting of the heat-sealed portion.

<Adhesive composition>
The adhesive composition of the present invention includes a polyol component, a polyisocyanate component, and an aliphatic hydroxy acid, and the content of the aliphatic hydroxy acid is 0.1 with respect to the total mass of the polyol component and the polyisocyanate component. It is characterized by being at least 5.0% by mass and not more than 5.0% by mass. Hydroxy acid is a general term for carboxylic acids having a hydroxyl group, and the aliphatic hydroxy acid in the present invention is an aliphatic carboxylic acid substituted with at least one hydroxyl group.
The solvent-free adhesive composition of the present invention contains the aliphatic hydroxy acid in a predetermined amount, so that when the polyol component and the polyisocyanate component three-dimensionally crosslink to form a coating film, some The isocyanate reacts with the hydroxy group of the aliphatic hydroxy acid to form a crosslinked coating film grafted with a carboxylic acid that has high affinity with the surface of the metal substrate. As a result, the adhesive composition of the present invention has improved adhesion to the metal substrate surface due to the carboxylic acid of the aliphatic hydroxy acid, and since one of the hydroxy groups is incorporated into the crosslinked coating film, the laminate It exhibits excellent metal conformability against the strain between the base materials that occurs when the material is bent, and can suppress the occurrence of floating. Therefore, a laminate using the adhesive composition of the present invention can be used as a packaging material for various uses such as foods, medicines, cosmetics, detergents, and miscellaneous goods.
The present invention will be explained in detail below.

<Aliphatic hydroxy acid>
Examples of aliphatic hydroxy acids include glycolic acid, lactic acid, glyceric acid, hydroxybutyric acid, tartronic acid, malic acid, tartaric acid, citric acid, and isocitric acid. Among these, the hydroxy group in the aliphatic hydroxy acid is preferably primary or secondary, since the hydroxy group is easily incorporated into the crosslinked coating film. Further, from the viewpoint of suppressing pot life deterioration, the number of carboxylic acid groups in the aliphatic hydroxy acid is preferably 3 or less.
Since the aliphatic hydroxy acid can exhibit its effect even in a small amount added, the number of carbon atoms in the carboxylic acid of the aliphatic hydroxy acid is preferably 18 or less, more preferably 10 or less, particularly preferably 7 or less. It is.
The content of the aliphatic hydroxy acid is 0.1% by mass or more and 5.0% by mass or less based on the total mass of the polyol component and polyisocyanate component described below. If it is less than 0.1% by mass, metal adhesion will be insufficient and lifting during bending cannot be suppressed, and if it exceeds 5.0% by mass, the number of reaction points with isocyanate will increase, causing crosslinking of the coating film itself. This results in a decrease in adhesive strength.
The content of aliphatic hydroxy acid is more preferably 0.3 to 3.0% by mass, particularly preferably 0.5 to 2.0% by mass.

<Polyol component>
The polyol component used in the present invention is not particularly limited and includes, for example, polyester polyol, polyether polyol, polyurethane polyol, polyester amide polyol, acrylic polyol, polycarbonate polyol, polycaprolactone polyol, polyvalerolactone polyol, polyolefin polyol, polyhydroxyalkane. , castor oil or mixtures thereof, as well as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-5-pentanediol, 1,6-hexane Glycols such as diol, neopentyl glycol, methylpentane glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, triethylene glycol; Polyalkylene glycol with an average molecular weight of 200 to 3,000; Trifunctional or tetrafunctional aliphatic alcohol such as glycerin, trimethylolpropane, or pentaerythritol; The above glycol or polyol is added to the above trifunctional or tetrafunctional aliphatic alcohol. Polyols can be used. These may be used alone or in combination of two or more.

The polyol component preferably contains polyester polyol or polyether polyol.
Examples of polyester polyols include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, phthalic anhydride, adipic acid, azelaic acid, sebacic acid, succinic acid, glutaric acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, and anhydride. A dibasic acid such as itaconic acid, a dialkyl ester thereof, or a mixture thereof (hereinafter also referred to as a carboxyl group component),
Ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, butylene glycol, neopentyl glycol, dineopentyl glycol, trimethylolpropane, glycerin, 1,6-hexanediol, 1,4-butanediol, 1, 4-Cyclohexane dimethanol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, 1,9-nonanediol, polyoxyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, poly Diols such as ether polyols, polycarbonate polyols, polyolefin polyols, acrylic polyols, and polyurethane polyols, or mixtures thereof (hereinafter also referred to as hydroxyl group components),
or polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone).
Two or more types of the above carboxyl group component and hydroxyl group component may be used in combination.

Examples of polyether polyols include polyether diols, polyether triols, and the like. Polyether diol obtained by polymerizing as an initiator; polyether triol obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran using a low amount triol such as trimethylolpropane and glycerin as an initiator; can be mentioned.

The polyester polyol or polyether polyol may be a polyester polyurethane polyol or a polyether polyurethane polyol that has been further reacted with a diisocyanate, or may be one that has been further reacted with an acid anhydride.
Examples of the diisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, and hydrogenated diphenylmethane diisocyanate. Can be mentioned.
Examples of the acid anhydride include pyromellitic anhydride, mellitic anhydride, trimellitic anhydride, and trimellitic acid ester anhydride. Examples of the trimellitic acid ester anhydride include ethylene glycol bisanhydrotrimellitate and propylene glycol bisanhydrotrimellitate.

The number average molecular weight of the polyol component is preferably 1,000 to 100,000, more preferably 1,000 to 10,000, particularly preferably 1,000 to 6,000. When the number average molecular weight is 1,000 or more, the cohesive force is sufficient, and when it is 100,000 or less, polybasic acid or its anhydride can be easily reacted at the terminal during synthesis, resulting in thickening. and gelation can be suppressed.
In the present invention, the number average molecular weight (Mn) can be determined as a polystyrene equivalent value measured using, for example, Showa Denko GPC (gel permeation chromatography) "Shodex GPC System-21" and tetrahydrofuran as a solvent. .

The acid value of the polyol component is preferably 0 to 40 mgKOH/g, more preferably 0 to 10 mgKOH/g, even more preferably 0 to 5 mgKOH/g, particularly preferably 0 to 1.0 mgKOH/g. The hydroxyl value of the polyol component is preferably 1 to 200 mgKOH/g, more preferably 10 to 150 mgKOH/g.

<Polyisocyanate component>
The adhesive composition of the present invention includes a polyisocyanate component. Examples of the polyisocyanate component include aromatic polyisocyanates and aliphatic polyisocyanates, and aromatic polyisocyanates or derivatives thereof are preferably used. These polyisocyanate components can be used alone or in combination of two or more.

Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate, or 2,6-tolylene diisocyanate. mixtures thereof, 4,4'-toluene diisocyanate, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, or mixtures thereof; ω,ω'-diisocyanate-1,4-diethylbenzene, 1,3-bis(1-isocyanate-1-methylethyl)benzene or 1,4-bis(1-isocyanate-1-methylethyl)benzene or mixtures thereof Aromatic diisocyanates such as triphenylmethane-4,4',4'-triisocyanate, 1,3,5-triisocyanate benzene, 2,4,6-triisocyanate toluene; 4, Aromatic polyisocyanates such as 4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate;

Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2 , 4,4'-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate, 1,3-xylylene diisocyanate or 1,4-xylylene diisocyanate. .

The polyisocyanate component may be a derivative derived from the aromatic or aliphatic polyisocyanates mentioned above. Examples of such derivatives include reaction products of aromatic or aliphatic polyisocyanates and known polyols.
Examples of known polyols include ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and 3,3'-dimethylol. Low molecular weight polyols with a molecular weight of less than 200 such as propane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol; polypropylene glycol, polyester polyol, polyether ester polyol, polyester amide Polyols such as polyols, polycaprolactone polyols, polyvalerolactone polyols, acrylic polyols, polycarbonate polyols, polyhydroxyalkanes, castor oil, and polyurethane polyols; may be used alone or in combination of two or more types. good.
The molar ratio of isocyanate groups to hydroxyl groups (number of NCO moles/number of OH moles) during the reaction of an aromatic or aliphatic polyisocyanate with a known polyol is preferably 2 or more.

The polyisocyanate component is preferably a reaction product of polyisocyanate and polypropylene glycol, more preferably a reaction product of aromatic polyisocyanate and polypropylene glycol. It is preferable that the polyisocyanate component contains an aromatic skeleton, as this improves heat resistance and suppresses the occurrence of floating due to bending of the heat-sealed portion. The number average molecular weight of polypropylene glycol is preferably 200 to 5,000.

When the adhesive composition is a solvent type, the isocyanate group content in the polyisocyanate component is preferably 2 to 5% by mass, more preferably 4 to 10% by mass. When the adhesive composition is a solvent-free type, the amount is preferably 10 to 30% by weight, more preferably 15 to 25% by weight. By being within the above range, when a film base material with high gas barrier properties is used, a laminate with a better appearance can be formed. The content of isocyanate groups (% by mass) can be determined by titration with hydrochloric acid.

<Manufacture of adhesive composition>
The adhesive composition of the present invention essentially includes a polyol component, a polyisocyanate component, and an aliphatic hydroxy acid, and can be produced by weighing the above components and stirring well using a spatula or the like. The molar ratio of isocyanate groups to hydroxyl groups (number of NCO moles/number of OH moles) in all components of the adhesive composition is preferably 1.0 to 3.0, more preferably 1.1 to 2.5. It is. Further, from the viewpoint of adhesive performance, the content of the polyisocyanate component is preferably 40 to 300 parts by mass, more preferably 70 to 200 parts by mass, based on 100 parts by mass of the total polyol components.

When the adhesive composition is a solvent type, its preferred viscosity is 30 seconds or less, more preferably 20 seconds or less in a #3 Zahn cup at room temperature (25° C.). A time of 20 seconds or less is preferable because the leveling properties will be good and the coating appearance will be excellent.

When the adhesive composition is a solvent-free type, its preferable viscosity is preferably 100 to 10,000 mPa·s, more preferably at room temperature (25°C) to 120°C, preferably room temperature to 80°C. It is 1,000 to 5,000 mPa·s. When it is 100 mPa·s or more, the initial cohesive force of the adhesive is excellent. When it is 10,000 mPa·s or less, the coating appearance is excellent.

(Silane coupling agent)
The adhesive composition of the present invention can contain a silane coupling agent from the viewpoint of improving adhesive strength to metal materials such as metal foil. Examples of the silane coupling agent include vinyltriethoxysilane, vinyltriethoxysilane, and other vinyl group-containing trialkoxysilanes; 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, Trialkoxysilane having an amino group such as methoxysilane; glycidyl such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, etc. trialkoxysilane having a group. These can be used alone or in any combination of two or more.
The content of the silane coupling agent is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 3 parts by weight, based on 100 parts by weight of all polyol components. By setting it as the said range, the adhesive strength to metal foil can be improved.

(phosphoric acid or phosphoric acid derivative)
The adhesive composition of the present invention may contain phosphoric acid or a phosphoric acid derivative, and two or more types may be used in combination, from the viewpoint of improving adhesive strength to metal-based materials such as metal foil.
The phosphoric acid may be any one having at least one free oxygen acid, such as phosphoric acids such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, and hypophosphoric acid; metaphosphoric acid, Examples include condensed phosphoric acids such as pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. Examples of phosphoric acid derivatives include those obtained by partially esterifying the above-mentioned phosphoric acid with an alcohol while leaving at least one free oxygen acid. Examples of the alcohols include aliphatic alcohols such as methanol, ethanol, ethylene glycol, and glycerin; aromatic alcohols such as phenol, xylenol, hydroquinone, catechol, and phloroglycinol.
The content of phosphoric acid or its derivatives is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, particularly preferably 0.05 to 5% by mass, based on the total solid content of the adhesive composition. It is 1% by mass.

(Other additives)
The adhesive composition of the present invention may contain various additives as long as the effects of the present invention are not impaired. Examples of additives include inorganic fillers such as silica, alumina, mica, talc, aluminum flakes, and glass flakes, layered inorganic compounds, and stabilizers (antioxidants, heat stabilizers, ultraviolet absorbers, hydrolysis inhibitors, etc.) ), rust inhibitors, thickeners, plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, fillers, crystal nucleating agents, and catalysts for adjusting the curing reaction.

[Laminated body]
The laminate of the present invention is one in which an adhesive layer made of the above-mentioned adhesive composition is laminated between at least two sheet-like substrates, and specifically, the adhesive layer is laminated between at least two sheet-like base materials. An adhesive layer is formed by coating on a sheet-like base material, a second sheet-like base material is superimposed on the adhesive layer, and the adhesive layer located between both sheet-like base materials is cured. be.
The sheet-like base material is not particularly limited, and examples thereof include conventionally known plastic films, paper, metal foils, etc., and the two sheet-like base materials may be of the same type or different types.
As the plastic film, a thermoplastic resin or thermosetting resin film can be used, and preferably a thermoplastic resin film. Examples of the thermoplastic resin include polyolefin, polyester, polyamide, polystyrene, vinyl chloride resin, vinyl acetate resin, ABS resin, acrylic resin, acetal resin, polycarbonate resin, and cellulose plastic. The sheet-like base material may be provided with a barrier film such as a vapor deposited layer, and examples of the vapor deposited layer include vapor deposited layers of aluminum, silica, alumina, and the like.

The first sheet-like substrate is preferably a plastic film. Plastic films include those commonly used for packaging materials, such as polyester resin films such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polylactic acid (PLA); polyethylene (PE), polypropylene; Polyolefin resin film such as (PP); Polystyrene resin film; Polyamide resin film such as nylon 6, poly-p-xylylene adipamide (MXD6 nylon); Polycarbonate resin film; Polyacrylonitrile resin film; Polyimide resin film ; composites thereof (for example, nylon 6/MXD6/nylon 6, nylon 6/ethylene-vinyl alcohol copolymer/nylon 6) and mixtures thereof can be mentioned. Among these, those having mechanical strength and dimensional stability are preferred.
The plastic film preferably has a thickness of 5 μm or more and 50 μm or less, more preferably 10 μm or more and 30 μm or less.

When the second sheet-like base material becomes the outermost layer of the laminate, the second sheet-like base material is preferably a sealant base material.
Examples of the sealant base material include polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), acid-modified polyethylene, polypropylene (PP), acid-modified polypropylene, and copolymer. Examples include polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-(meth)acrylic acid copolymer, and ionomer.
The thickness of the sealant base material is not particularly limited, and in consideration of processability into packaging materials, heat sealability, etc., it is preferably 10 to 150 μm, more preferably 20 to 70 μm. Further, by providing the sealant base material with unevenness having a height difference of about several μm, it is possible to impart slipperiness and tearability to the packaging material.
When the second sheet-like base material becomes an intermediate layer of the laminate, the above-mentioned plastic film, paper, metal foil, etc. can be suitably used as the second sheet-like base material.

The sheet-like base material may have a printed layer on the base material.
The printing layer contains letters, numbers, pictures, figures, symbols, patterns, etc. for decoration, display of contents, display of expiration date, display of manufacturer, seller, etc., and for giving a sense of beauty. It is a layer that forms any desired printed pattern, and also includes a solid printing layer. The printing layer can be formed using conventionally known pigments and dyes, and the method for forming the printing layer is not particularly limited.
Generally, the printing layer is formed using printing ink containing a coloring agent such as a pigment or dye. The coating method for printing ink is not particularly limited, and can be applied by methods such as gravure coating, flexo coating, roll coating, bar coating, die coating, curtain coating, spin coating, and inkjet coating. . A printed layer can be formed by leaving this as it is, or by blowing air, heating, drying under reduced pressure, irradiating ultraviolet rays, etc. as necessary.
The printed layer preferably has a thickness of 0.1 μm or more and 10 μm or less, more preferably 1 μm or more and 5 μm or less, and still more preferably 1 μm or more and 3 μm or less.

Conventionally known methods can be used to manufacture the laminate. For example, an adhesive is applied to one side of one sheet-like base material using a laminator to form an uncured adhesive layer, and then the adhesive is applied. Examples include a method of bonding one side to the other sheet-like base material and then curing the adhesive layer at room temperature or under heating. The coating amount of the adhesive composition after drying is preferably about 1 to 4 g/m ² , and the thickness of the laminate is preferably 10 μm or more.

An example of the structure of the laminate of the present invention is listed below, but the structure is not limited thereto.
Biaxially oriented polypropylene (OPP) / printing layer / adhesive layer / unoriented polypropylene (CPP),
OPP/printing layer/adhesive layer/aluminum (AL) vapor-deposited CPP,
OPP/printing layer/adhesive layer/PE,
Printing layer/OPP/adhesive layer/CPP,
NY/printing layer/adhesive layer/PE,
Printing layer/NY/Adhesive layer/CPP
NY/printing layer/adhesive layer/CPP,
PET/printing layer/adhesive layer/CPP,
Printing layer/PET/adhesive layer/CPP
PET/printing layer/adhesive layer/NY/adhesive layer/CPP,
Transparent vapor deposited PET/printing layer/adhesive layer/NY/adhesive layer/CPP,
PET/printing layer/adhesive layer/AL vapor-deposited PET/adhesive layer/PE,
PET/printing layer/adhesive layer/AL/adhesive layer/CPP,
PET/printing layer/adhesive layer/AL/adhesive layer/PE,
PET/printing layer/adhesive layer/NY/adhesive layer/AL/adhesive layer/CPP,
PET/printing layer/adhesive layer/AL/adhesive layer/NY/adhesive layer/CPP

Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples. "Parts" and "%" in Examples and Comparative Examples mean "parts by mass" and "% by mass" unless otherwise specified.

[Method for measuring number average molecular weight (Mn)]
The number average molecular weight (Mn) was measured using GPC (gel permeation chromatography) "Shodex GPCSystem-21" manufactured by Showa Denko. GPC is a liquid chromatography method that separates and quantifies substances dissolved in a solvent based on the difference in molecular size. Tetrohydrofuran was used as the solvent, and the molecular weight was determined in terms of polystyrene.

[Method for measuring acid value (AV)]
Approximately 1 g of the sample was accurately weighed into a stoppered Erlenmeyer flask, and 100 mL of a toluene/ethanol (volume ratio: toluene/ethanol = 2/1) mixed solution was added to dissolve it. To this, phenolphthalein test solution was added as an indicator and the test was continued for 30 seconds. Thereafter, the solution was titrated with 0.1N alcoholic potassium hydroxide solution until the solution took on a pale pink color. The acid value was determined by the following (Formula 1). (Unit: mgKOH/g).
(Formula 1) Acid value (mgKOH/g) = [{(ba) x F x 28.25}/S]
S: Amount of sample collected (g)
a: Consumption amount (mL) of 0.1N alcoholic potassium hydroxide solution
b: Consumption amount (mL) of 0.1N alcoholic potassium hydroxide solution in blank experiment
F: Titer of 0.1N alcoholic potassium hydroxide solution

[Method for measuring hydroxyl value (OHV)]
Approximately 1 g of the sample was accurately weighed into a stoppered Erlenmeyer flask, and 100 mL of a toluene/ethanol (volume ratio: toluene/ethanol = 2/1) mixed solution was added to dissolve it. Furthermore, exactly 5 mL of an acetylating agent (a solution of 25 g of acetic anhydride dissolved in pyridine to make a volume of 100 mL) was added, and the mixture was stirred for about 1 hour. To this, phenolphthalein test solution is added as an indicator and maintained for 30 seconds. Thereafter, the solution was titrated with 0.1N alcoholic potassium hydroxide solution until the solution took on a pale pink color. The hydroxyl value was determined by the following (Formula 2). The hydroxyl value was the value of the resin in a dry state (unit: mgKOH/g).
(Formula 2) Hydroxyl value (mgKOH/g) = [{(ba) x F x 28.25}/S]/(Non-volatile content concentration/100) + D
S: Amount of sample collected (g)
a: Consumption amount (mL) of 0.1N alcoholic potassium hydroxide solution
b: Consumption amount (mL) of 0.1N alcoholic potassium hydroxide solution in blank experiment
F: Potency of 0.1N alcoholic potassium hydroxide solution D: Acid value (mgKOH/g)

[Method for measuring NCO content (mass%)]
Approximately 1 g of the sample was weighed into a 200 mL Erlenmeyer flask, and 10 mL of a toluene solution of 0.5N di-n-butylamine and 10 mL of toluene were added to dissolve the sample. Next, a phenolphthalein test solution was added as an indicator, held for 30 seconds, and then titrated with a 0.25N hydrochloric acid solution until the solution turned pale pink. The NCO content (mass%) was determined by the following (Equation 3).
(Formula 3): NCO (mass%) = {(ba) x 4.202 x F x 0.25}/S
However, S: Sample amount (g)
a: Consumption amount of 0.25N hydrochloric acid solution (ml)
b: Consumption amount (ml) of 0.25N hydrochloric acid solution in blank experiment
F: Titer of 0.25N hydrochloric acid solution

<Production of polyether polyol>
(Manufacturing example 1)
363.9 parts of polypropylene glycol (hereinafter referred to as PPG-400) with a number average molecular weight of approximately 400, 78.1 parts of polypropylene glycol (hereinafter referred to as PPG-2000) with a number average molecular weight of approximately 2,000, and polypropylene glycol added to glycerin. 78.1 parts of a triol with a number average molecular weight of about 400 (hereinafter referred to as PPG-400-3 functional), 179.9 parts of tolylene diisocyanate (hereinafter referred to as TDI), and 300 parts of ethyl acetate were charged into a reaction vessel, and nitrogen gas was added. A urethane reaction was carried out by heating at 80°C to 90°C for 5 hours while stirring under a stream of air, and the disappearance of isocyanate groups was confirmed by IR to obtain a solution of polyether polyurethane polyol with a number average molecular weight of 5,000. Ta.
Next, 20 parts of malic acid as an aliphatic hydroxy acid was added to the obtained polyether polyurethane polyol solution, and the mixture was stirred at 70 to 80°C until dissolved to form a polyether polyol with a solid concentration of 70% and an aliphatic hydroxy acid. A mixture (A-1) with acid was obtained.

(Manufacturing example 2)
363.7 parts of PPG-400, 198.8 parts of PPG-2000, 344.8 parts of PPG-400-3 functional, and 92.7 parts of TDI were charged into a reaction vessel, and while stirring under a nitrogen gas flow. A urethane reaction was carried out by heating at 80° C. to 90° C. for 5 hours, and the disappearance of isocyanate groups was confirmed by IR to obtain a polyether polyurethane polyol with a number average molecular weight of 1,500.
Next, 15 parts of D/L-lactic acid as an aliphatic hydroxy acid was added to the obtained polyether polyurethane polyol, and the mixture was stirred at 70° C. or lower until the solution became uniform, resulting in a polyether polyol with a solid concentration of 100%. and an aliphatic hydroxy acid (A-2) was obtained.

(Manufacturing example 3)
343.2 parts of PPG-400, 191.9 parts of PPG-2000, 336.3 parts of PPG-400-3 functional, and 128.2 parts of 4,4'-diphenylmethane diisocyanate (hereinafter referred to as 4,4'-MDI). 6 parts were charged into a reaction vessel and heated at 80°C to 90°C for 3 hours while stirring under a nitrogen gas stream to perform a urethanization reaction.The disappearance of isocyanate groups was confirmed by IR, and the number average molecular weight was 1. 500 polyether polyurethane polyol was obtained.
Next, 3.1 parts of D/L-lactic acid as an aliphatic hydroxy acid was added to the obtained polyether polyurethane polyol, and the mixture was stirred at 70°C or lower until the solution became homogeneous. A mixture (A-3) of ether polyol and aliphatic hydroxy acid was obtained.

(Manufacturing examples 4 to 6)
A mixture of polyether polyol and aliphatic hydroxy acid (A-4 ~A-6) was obtained.

(Manufacturing example 7)
A mixture (A-7) of polyether polyol and aliphatic hydroxy acid with a solid content concentration of 100% was obtained in the same manner as Production Example 4 except that D/L-lactic acid was changed to 12-hydroxystearic acid. .

(Production example 8)
The polyether polyurethane polyol with a solid content concentration of 100% obtained in Production Example 3 was designated as polyether polyol (A-8).

Abbreviations in Table 1 are shown below.
PPG-400: Polypropylene glycol with a number average molecular weight of about 400 PPG-2000: Polypropylene glycol with a number average molecular weight of about 2,000 PPG-400-3 Functional: Triol 4,4 with a number average molecular weight of about 400, which is obtained by adding polypropylene glycol to glycerin '-MDI: 4,4'-diphenylmethane diisocyanate TDI: Tolylene diisocyanate

<Manufacture of polyester polyol>
(Manufacturing example 9)
In a reaction vessel equipped with a stirrer, a temperature system, a reflux condenser, a dropping tank, and a nitrogen gas introduction tube, 55.6 parts of ethylene glycol (hereinafter referred to as EG) and 1,6-hexanediol (hereinafter referred to as 1,6 -HDI), 143.8 parts of 2-methyl-1,3-propanediol (hereinafter referred to as MPO), 159.5 parts of isophthalic acid (hereinafter referred to as IPA), and terephthalic acid (hereinafter referred to as TPA). and 140.4 parts of adipic acid (hereinafter referred to as ADA) were charged, and the temperature was raised to 260°C while stirring under a nitrogen stream. After continuing the reaction until the acid value became 5 mgKOH/g or less, the pressure inside the reaction vessel was gradually reduced and the reaction was carried out at 1.3 kPa or less to produce an acid value of 0.5 mgKOH/g, a hydroxyl value of 18 mgKOH/g, and a number average molecular weight. Approximately 6,000 polyester polyols were obtained.
Next, after cooling the obtained polyester polyol to 80°C, 360 parts of ethyl acetate and 10 parts of malic acid were added and stirred at 70 to 80°C until dissolved, resulting in a polyester polyol with a solid content concentration of 64%. A mixture (B-1) with an aliphatic hydroxy acid was obtained.

(Manufacturing example 10)
A reaction vessel equipped with a stirrer, a temperature system, a reflux condenser, a dropping tank, and a nitrogen gas introduction tube was charged with 465.6 parts of diethylene glycol (DEG) and 534.4 parts of ADA, and stirred under a nitrogen stream. The temperature was raised to 230°C. After continuing the reaction until the acid value became 10 mgKOH/g or less, the pressure inside the reaction vessel was gradually reduced and the reaction was carried out at 1.3 kPa or less to produce an acid value of 0.5 mgKOH/g, a hydroxyl value of 56 mgKOH/g, and a number average molecular weight. Approximately 2,000 polyester polyols were obtained.
Next, after cooling the obtained polyester polyol to 70°C, 10 parts of D/L-lactic acid was added, and the solution was stirred at 70°C or lower until the solution became homogeneous. A mixture (B-2) with a group hydroxy acid was obtained.

(Production example 11)
The polyester polyol with a solid content concentration of 100% obtained in Production Example 9 was designated as polyester polyol (B-3).

The abbreviations in Table 2 are shown below.
IPA: Isophthalic acid TPA: Terephthalic acid ADA: Adipic acid EG: Ethylene glycol DEG: Diethylene glycol 1,6-HD: 1,6-hexanediol MPO: 2-methyl-1,3-propanediol

<Production of polyisocyanate component>
(Production example 12)
Charge 180.1 parts of PPG-400, 230.3 parts of PPG-2000, 18.3 parts of PPG-400-3 functional, 300 parts of 4,4'-MDI, and 200 parts of ethyl acetate into a reaction vessel. The mixture was heated at 80° C. to 90° C. for 3 hours with stirring under a nitrogen gas stream to carry out a urethane reaction, thereby obtaining a polyisocyanate solution. Next, 71.3 parts of an adduct of tolylene diisocyanate (hereinafter referred to as TDI trimer) was added and stirred at 70° C. or lower until the solution became uniform, so that the solid content concentration was 80% and the isocyanate group content was 4.5%. An 8% polyisocyanate component (C-1) was obtained.

(Manufacturing example 13)
A polyester polyol with a number average molecular weight of about 2,000 consisting of 53.6 parts of PPG-400, 329.7 parts of PPG-2000, 36.8 parts of PPG-400-3 functional, ADA and 1,2-propanediol. 106.2 parts of -1 and 398.7 parts of 4,4'-MDI were charged into a reaction vessel, and heated at 80°C to 90°C for 3 hours with stirring under a nitrogen gas stream to perform a urethanization reaction. A polyisocyanate resin was obtained.
Next, 75 parts of biuret hexamethylene diisocyanate (hereinafter referred to as HDI trimer) was added and stirred at 70°C or below until the solution became uniform, so that the solid concentration was 100% and the isocyanate group content was 10.7%. A polyisocyanate component (C-2) was obtained.

(Manufacturing example 14)
187.7 parts of PPG-400, 155.9 parts of polyester polyol-2 with a number average molecular weight of about 2,000 consisting of ADA and 1,4-butanediol, 2,4'-MDI and 4,4'-MDI 656.4 parts of the mixture (hereinafter referred to as liquid MDI) was charged into a reaction vessel, and heated at 80°C to 90°C for 3 hours while stirring under a nitrogen gas stream to perform a urethanization reaction, with a solid concentration of 100%, A polyisocyanate component (C-3) having an isocyanate group content of 17.3% was obtained.

(Production example 15)
202.1 parts of PPG-400 and 547.9 parts of liquid MDI were charged into a reaction vessel, heated at 80°C to 90°C for 3 hours with stirring under a nitrogen gas stream to perform a urethanization reaction, and then polymeric MDI Add 250 parts of a mixture of 4,4'-MDI and 4,4'-MDI (hereinafter referred to as crude MDI) and stir at 70°C or below until the solution becomes uniform, so that the solid concentration is 100% and the isocyanate group content is 21.5. % polyisocyanate component (C-4) was obtained.

The abbreviations in Table 3 are shown below.
PPG-400: Polypropylene glycol with a number average molecular weight of about 400 PPG-2000: Polypropylene glycol with a number average molecular weight of about 2,000 Polyester polyol-1: A polypropylene glycol with a number average molecular weight of about 2,000 consisting of adipic acid and 1,2-propanediol Polyester polyol Polyester polyol-2: Polyester polyol with a number average molecular weight of about 2,000 consisting of adipic acid and 1,4-butanediol 4,4'-MDI: 4,4'-diphenylmethane diisocyanate Liquid MDI: 2,4'- Mixture of 52% by mass of diphenylmethane diisocyanate (hereinafter referred to as 2,4'-MDI) and 48% by mass of 4,4'-MDI TDI trimer: adduct of tolylene diisocyanate HDI trimer: biuret crude of hexamethylene diisocyanate MDI: mixture of 60% by mass of polymeric MDI and 40% by mass of 4,4'-MDI CAT-10: Tomoflex CAT-10 (aromatic polyisocyanate, solid content concentration 75%, manufactured by Toyo Morton Co., Ltd.)

<Manufacture of adhesive composition>
[Examples 1 to 9, Comparative Examples 1 and 2] Adhesive compositions 1 to 11
A polyol component, a polyisocyanate component, and if necessary, ethyl acetate were mixed in the amounts shown in Table 4 to obtain adhesive compositions 1 to 11.

<Evaluation of adhesive composition>
The obtained adhesive composition was evaluated as follows. The results are shown in Table 5.

[Pot life of solvent-based adhesive composition]
For solvent-type adhesive compositions 1, 8, and 11, after adding 0.6% distilled water to the adhesive composition and stirring, the number of seconds was measured using a Zahn cup #3 at 25°C. Thereafter, after being stored at 25° C. for 1 day, the number of seconds was measured using Zahn cup #3 and the appearance of the solution was confirmed. The following criteria were used to evaluate the changes in viscosity before and after storage.
A: Within 20 seconds after storage, the solution appearance is colorless and transparent (good)
B: The solution appearance is colorless and transparent within more than 20 seconds and less than 25 seconds after storage (can be used)
C: The solution appearance is cloudy within 25 seconds after storage (unusable)
D: Other than A to C (defective)

[Pot life of solvent-free adhesive composition]
The viscosity of Adhesive Compositions 2 to 7, 9 and 10 was measured immediately after blending and after being stored at 40°C for 30 minutes using a cone plate viscometer CV-1S manufactured by Toa Kogyo Co., Ltd., respectively. The temperature during measurement was 40°C. The following criteria were used to evaluate the changes in viscosity before and after storage.
A: The viscosity after storage is less than twice the viscosity immediately after blending (good)
B: The viscosity after storage is 2 times or more and less than 3 times the viscosity immediately after blending (usable)
C: The viscosity after storage is 3 times or more and less than 4 times the viscosity immediately after blending (cannot be used)
D: The viscosity after storage is 4 times or more the viscosity immediately after blending (defective)

[Preparation of laminate]
Printing ink (manufactured by Toyo Ink Co., Ltd., Rio Alpha R631 White) was heated at 25° C. using a mixed solvent of ethyl acetate/IPA (mass ratio 70/30) so that the viscosity of Zahn cup #3 was 16 seconds. Diluted. The diluted printing ink was applied onto a 12 μm thick polyethylene terephthalate film (“Ester Film E5102” manufactured by Toyobo Co., Ltd., hereinafter referred to as PET) at a printing speed of 50 m/min using a gravure proofing machine equipped with a solid plate with a plate depth of 35 μm. After printing, it was dried at 50°C. The thickness of the printed layer was within the range of 0.5 to 1 μm.
Next, a solvent-based adhesive is coated on the printed layer of the obtained laminate using a dry laminator at a solid content coating amount of 2.0 to 3.5 g/m ² . It was dried. On the other hand, the solvent-free adhesive composition was coated using a solvent-free laminator with the solid content coating amount adjusted to 2.0 to 3.5 g/m ² .
Next, the aluminum vapor-deposited surface of a 12 μm thick aluminum vapor-deposited PET film ("Dialaster H27" manufactured by Reikosha, hereinafter referred to as VM-PET) and the adhesive-coated surface of the obtained laminate were bonded together.
Next, the adhesive composition was applied on the PET on the VM-PET side of the obtained laminate in the same manner as before, and the applied surface was covered with a linear low-density polyethylene film having a thickness of 100 μm and subjected to surface corona discharge treatment. (TUX-FCD manufactured by Mitsui Tohcello Co., Ltd., hereinafter referred to as LLDPE), and then kept warm at 40°C for 2 days to harden the adhesive. A laminate having a composition of agent layer/LLDPE was obtained.

[Resistance to lifting due to bending of heat seal (HS) part]
The obtained laminate was cut into a size of 6 cm wide and 10 cm long, and folded so that the LLDPE surfaces overlapped to obtain a size of 6 cm wide and 5 cm long. Next, a 3 cm area from the fold (width: 6 cm, length: 3 cm) was heat-sealed (180° C., 2.0 kg/m ² , 1.0 seconds), and then allowed to cool at room temperature for about 10 seconds. Next, the heat-sealed portion was folded in half, and the folded portion was strongly handled with the corner of a desk five times back and forth, and when the fold was slightly spread, it was visually checked to see if a white line had formed in the trough. Judgment was made based on the appearance based on the following criteria.
A: No white line or a white line less than 1/30 of the crease (good)
B: White lines occur on 1/30 or more and less than 1/3 of the crease (usable)
C: White line occurs on 1/3 or more of the crease (unusable)
D: A wide white line appears around the crease (defective)

[Adhesive strength]
The obtained laminate was cut to a length of 300 mm and a width of 15 mm to prepare a test piece. Using an Instron type tensile tester, the T-peel strength (N/15mm) between PET/VMPET at a width of 15mm was measured by pulling at a peeling speed of 300mm/min in an environment of 25°C. . This test was conducted five times, and the average value was calculated and evaluated based on the following criteria.
A: Adhesive force is 1.5N/15mm or more (good)
B: Adhesive force is 1.0N/15mm or more and less than 1.5N/15mm (usable)
C: Adhesive force is 0.5N/15mm or more and less than 1.0N/15mm (unusable)
D: Adhesive force is less than 0.5N/15mm (defective)

Abbreviations in Table 4 are shown below.
C-5: Tomoflex CAT-10 (aromatic polyisocyanate, solid content concentration 75%, manufactured by Toyo Morton Co., Ltd.)

According to the evaluation results, the adhesive composition of the present invention exhibited an effect of suppressing floating when the heat-sealed portion was bent while maintaining pot life and adhesive strength.
In particular, when a hydroxy acid was added to the polyether polyol base material, excellent bending resistance of the HS portion was exhibited. This is presumed to be due to the high compatibility of the hydroxy acid with the polyether resin.
As described above, the adhesive composition of the present invention exhibits resistance to lifting that tends to occur when the heat-sealed part is bent by containing a hydroxy acid having a fatty chain, and since it is a fatty chain carboxylic acid, The activation of isocyanate is suppressed compared to aromatic carboxylic acids, and the effect on pot life can be minimized.

Claims (4)

Contains a polyol component, a polyisocyanate component, and an aliphatic hydroxy acid,
The content of the aliphatic hydroxy acid is 0.1% by mass or more and 5.0% by mass or less based on the total mass of the polyol component and the polyisocyanate component,
The polyol component includes a polyether polyurethane polyol,
The adhesive composition, wherein the aliphatic hydroxy acid is at least one selected from the group consisting of glycolic acid, lactic acid, glyceric acid, hydroxybutyric acid, tartronic acid, malic acid, tartaric acid, and citric acid. The adhesive composition according to claim 1, wherein the aliphatic hydroxy acid has 10 or less carbon atoms. The adhesive composition according to claim 1 or 2, wherein the polyisocyanate component contains an aromatic polyisocyanate or a derivative thereof. A laminate in which an adhesive layer made of the adhesive composition according to any one of claims 1 to 3 is laminated between at least two sheet-like base materials.