JP2013203946A - Polyester resin and adhesive for dry laminate containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester resin to which low glass transition temperature can be readily imparted without deteriorating adhesion or heat-resistant adhesion.SOLUTION: A polyester resin is obtained by reacting a dibasic acid component and a diol containing 2-methyl-1,3-propanediol and comprises 10-40 mol% structural unit derived from 2-methyl-1,3-propanediol. The polyester resin is preferably synthesized using an aliphatic dibasic acid having a methylene chain with 6 or more carbons or a diol having a methylene chain with 6 or more carbons.

Description

  The present invention relates to a polyester resin. Specifically, it is easy to design a resin having a low glass transition temperature, and a polyester resin suitable for use as an adhesive, and an adhesive for dry lamination including the same and a food, medical product, cosmetic, and the like manufactured using the same. The present invention relates to a laminate laminate suitably used for soft packaging (hereinafter collectively referred to as foods).

Polyester resins are widely used in adhesives, paints, fibers, films, containers and the like. In particular, in the field of adhesives, it is preferably used for soft packaging applications such as food.
Each of the above uses has specific required quality and physical properties, and a resin design suitable for each is performed. The main physical property items include glass transition temperature, average molecular weight, viscoelastic properties, functional group concentration, etc., but glass transition temperature is one of the major influencing factors for adhesion performance.
And when used in containers, etc., since rigid properties are usually preferred, a high glass transition temperature is often required, while in adhesive applications, the type of adherend and curing agent is also used. However, a low glass transition temperature may be required.

  As a technique for setting the glass transition temperature of the polyester resin low, the cohesive force of the resin is reduced by copolymerizing monomers having side chains, and the glass transition temperature (hereinafter also referred to as “Tg”). There are known adhesives and the like that have a reduced height (for example, see Patent Document 1). However, the pressure-sensitive adhesive disclosed in Patent Document 1 is intended to impart biodegradability, and since the resin skeleton is an aliphatic polyester, it is easy to obtain tack and is relatively flexible. There were problems such as insufficient adhesion. Similar problems are likely to occur when used as an adhesive for dry lamination.

Japanese Patent Laid-Open No. 11-021340

  An object of this invention is to provide the polyester resin which can provide a low glass transition temperature easily, without reducing adhesive force or heat resistant adhesiveness.

  As a result of intensive studies to solve the above-described problems, the present inventors have used 2-methyl-1,3-propanediol as a diol monomer as a raw material for a polyester resin, thereby increasing the cohesive strength of the adhesive. It has been found that the above problems can be solved by combining an aliphatic dibasic acid or an aliphatic diol having a long methylene chain for the purpose of enhancement, and the present invention has been completed.

  That is, the present invention comprises reacting a dibasic acid component with a diol containing 2-methyl-1,3-propanediol, and converting structural units derived from 2-methyl-1,3-propanediol to 10 to 10. It is related with the polyester resin characterized by containing 40 mol%.

  The present invention also relates to the above-described polyester resin comprising an aliphatic dibasic acid having a methylene chain having 6 or more carbon atoms or a diol having a methylene chain having 6 or more carbon atoms.

  Moreover, this invention relates to said polyester resin characterized by containing 5-40 mol% of structural units derived from ethylene glycol.

  Moreover, this invention relates to the polyester resin in any one of Claims 1 thru | or 3 whose glass transition temperature is -25-0 degreeC.

  Moreover, this invention relates to the adhesive agent for dry laminates containing any one of the said polyester resins and an isocyanate compound.

  The present invention also relates to a laminate laminate in which a substrate is laminated via an adhesive layer formed from the above adhesive for dry lamination.

  The present invention also relates to the above laminate laminate, wherein the substrate is a plastic film, a metal foil, or a metal vapor deposition film.

Furthermore, the present invention relates to any one of the above laminate laminates, wherein the concentration of the solvent contained in the adhesive layer is 3 mg / m ² or less at the adhesive layer thickness of 3 g / m ² .

  According to the present invention, it was possible to provide a polyester resin capable of easily imparting a low glass transition temperature without lowering the adhesive strength or heat resistant adhesiveness.

  The polyester resin of the present invention is obtained by reacting a dibasic acid component with a diol, and is characterized by using 2-methyl-1,3-propanediol as an essential diol.

  When a monomer having a highly symmetric structure such as ethylene glycol or neopentyl glycol is used as the diol component used in the production of the polyester resin, the polymer chains are closely arranged and flexible. Form a low structure. On the other hand, 2-methyl-1,3-propanediol having an asymmetric structure has only one side chain of a methyl group, so that it has a polymer chain as compared with neopentyl glycol or the like having two methyl group side chains. Can hardly be arranged, and the glass transition temperature (Tg) of the resin can be lowered.

  However, if a highly symmetric monomer such as neopentyl glycol is simply replaced with 2-methyl-1,3-propanediol, the cohesive strength of the resin may be reduced and the adhesive strength may be reduced. By combining an aliphatic dibasic acid having a methylene chain having 6 or more carbon atoms, such as sebacic acid, or a diol having a methylene chain having 6 or more carbon atoms, such as 1,6-hexanediol, The Tg of the resin can be lowered while maintaining the cohesive force.

Examples of the dibasic acid component used in the present invention include known dicarboxylic acids and acid anhydrides thereof, and esterified products of dicarboxylic acids and acid anhydrides with monoalcohols such as methanol and ethanol.
For example, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, suberic acid, maleic acid, chloromaleic acid, fumaric acid, dodecanedioic acid, pimelic acid, citraconic acid, glutaric acid, itaconic acid, etc. Aliphatic dicarboxylic acids;

  Examples of dicarboxylic acids and acid anhydrides thereof include o-phthalic acid, isophthalic acid, terephthalic acid, 2,5-dimethylterephthalic acid, 4,4-biphenyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2, Aromatic dicarboxylic acids such as 6-naphthalenedicarboxylic acid, norbornene dicarboxylic acid, diphenylmethane-4,4′-dicarboxylic acid, phenylindane dicarboxylic acid;

For example, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid, hexahydrophthalic acid, tetrahydrophthalic acid;
Alicyclic dicarboxylic anhydrides such as hexahydrophthalic anhydride, 3-methyl-hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride, 1,2-cyclohexanedicarboxylic anhydride;

  For example, succinic anhydride, methyl succinic anhydride, 2,2-dimethyl succinic anhydride, butyl succinic anhydride, isobutyl succinic anhydride, hexyl succinic anhydride, octyl succinic anhydride, dodecenyl succinic anhydride, phenyl succinic anhydride Glutaric anhydride, 3-allyl glutaric anhydride, 2,4-dimethyl glutaric anhydride, 2,4-diethyl glutaric anhydride, butyl glutaric anhydride, hexyl glutaric anhydride, maleic anhydride, 2-methyl maleic anhydride 2,3-dimethylmaleic anhydride, butylmaleic anhydride, pentylmaleic anhydride, hexylmaleic anhydride, octylmaleic anhydride, decylmaleic anhydride, dodecylmaleic anhydride, 2,3-dichloromaleic anhydride, phenyl Maleic anhydride, 2,3-diphenyl maleic anhydride, none Itaconic acid, citraconic anhydride, phthalic anhydride, 4-methylphthalic anhydride, dimer acid, 1,2,3,6-tetrahydrophthalic anhydride, 3-methyl-1,2,3,6-tetrahydrophthalic anhydride 4-methyl-1,2,3,6-tetrahydrophthalic anhydride, 3-methyl-1,2,3,6-tetrahydrophthalic anhydride, 4-methyl-1,2,3,6-tetrahydrophthalic anhydride Acid, methylbutenyl-1,2,3,6-tetrahydrophthalic anhydride, chlorendic anhydride, head acid anhydride, biphenyldicarboxylic anhydride, hymic anhydride, endomethylene-1,2,3,6-tetrahydrophthalic anhydride Methyl-3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride, 1-cyclopentene-1,2-dicarboxylic anhydride, B hexene dicarboxylic acid anhydride, trimellitic anhydride, 1,8-naphthalene dicarboxylic acid anhydride, acid anhydrides such as octahydro-1,3-dioxo-4,5-isobenzofurandione carboxylic acid anhydrides.

  In the present invention, in order to adjust the molecular weight and the degree of branching of the polyester resin, in addition to the dibasic acid component, a monobasic acid and a polybasic acid of tribasic acid or more can be used as necessary.

Examples of the aromatic monobasic acid include benzoic acid, methyl benzoic acid, dimethyl benzoic acid, trimethyl benzoic acid, phenylacetic acid, tertiary butyl benzoic acid, and naphthoic acid.
Examples of the aliphatic monobasic acid include octylic acid, capric acid, lauric acid, myristic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid.

  Examples of the polybasic acid having a tribasic acid or higher include trimellitic acid, pyromellitic acid, and anhydrides thereof.

  Among the diols other than 2-methyl-1,3-propanediol in the present invention, the aliphatic diol is, for example, ethylene glycol, propylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1 , 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, octanediol, cyclohexanediol, cyclohexanedimethanol, tricyclodecane dimethanol, cyclopentadiene diene Methanol, dimer diol, polyoxyethylene glycol (addition mole number 10 or less), polyoxypropylene glycol (addition mole number 10 or less), neopentyl glycol, 3-methyl-1,5-pentanedioe 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-butyl-2- Methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 3- Butyl-3-ethyl-1,5-pentanediol, 1,3,5-trimethyl-1,3-pentanediol, 2-methyl-1,6-hexanediol, 2-methyl-1,8-octanediol, etc. These can be used alone or in combination of two or more.

  Examples of the aromatic diol include benzene-1,2-dimethanol (also known as phthalyl alcohol), benzene-1,3-dimethanol (also known as isophthalyl alcohol), benzene-1,4-dimethanol ( Alias: terephthalyl alcohol), 1,3-bis (2-hydroxyethoxy) benzene, 1,2-bis (2-hydroxyethoxy) benzene, 1,4-bis (2-hydroxyethoxy) benzene, (3,4 -Dihydroxyphenyl) methanol (alias: protocatechuyl alcohol), (4-hydroxy-3-methoxyphenyl) methanol (alias: vanillyl alcohol), 2- (4-hydroxy-3-methoxyphenyl) ethane-1-ol (Also known as: homovanillyl alcohol), 3- (4-hydroxy-3-methoxyphenyl) Lopa-2-en-1-ol (also known as coniferyl alcohol), 3- (4-hydroxy-3,5-dimethoxyphenyl) prop-2-en-1-ol (also known as sinapyl alcohol), 1 , 2-diphenylethane-1,2-diol (also known as hydrobenzoin), hydroquinone, resorcin, 4-chlororesorcin, 4-methylresorcin, 5-methylbenzene-1,3-diol (also known as orcinol), 2- Methylbenzene-1,4-diol (alias: tolhydroquinone), 2,3-dimethylbenzene-1,4-diol (alias: o-xylohydroquinone), 2,6-dimethylbenzene-1,4-diol (alias) : M-xylohydroquinone), 2,5-dimethylbenzene-1,4-diol (also known as p-xylohydroquinone), 2,3,5 -Trimethylbenzene-1,4-diol (alias: pseudo-couhydrohydroquinone), 2-isopropyl-5-methylbenzene-1,4-diol (alias: thymohydroquinone), 2,3,5,6-tetramethylbenzene -1,4-diol (also known as jurohydroquinone), 4,4′-methylenediphenol, 4,4 ′-(2-norbornylidene) diphenol, 4,4′-dihydroxymethylbiphenyl, 4,4′-biphenyl Diol, 2,3-dihydroxybuphenyl, tetranitrobiphenyldiol, 5,5'-dipropyl-biphenyl-2,2'-diol, 3,3'-diaminobiphenyl-4,4'-diol, 5,5 ' -Tetramethylbiphenyl-4,4'-diol, diphenylsilanediol, (E) -4,4 '-(hexa- -Ene-3,4-diyl) diphenol (also known as diethylstilbestrol), 2,2-bis (4-hydroxyphenyl) sulfone, o-, m-, and p-dihydroxybenzene, 4,4'- Isopropylidenephenol, 1,2-indanediol, 4,4′-dihydroxydiphenyl ether, 2,2-bis (4-hydroxyphenyl) propane, 1,3-naphthalenediol, 1,5-naphthalenediol, 1,7- Naphthalenediol, 1,7-dihydroxymethylnaphthalene, ammonium 1,4-dihydroxy-2-naphthalenesulfonate, 9,9′-bis (4-hydroxyphenyl) fluorene, 9,9′-bis (3-methyl-4) -Hydroxyphenyl) fluorene or bisphenol A or bisphenol F Bisphenols obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to phenols, and aromatic diols such as 1,4-dihydro-9,10-anthracenediol, etc., may be used alone or in combination A combination of the above can be used.

In the present invention, a trivalent or higher polyol is used in addition to the diol in order to adjust the molecular weight and branching degree of the polyester resin, or to increase the cohesive force of the adhesive for dry lamination by utilizing a reaction with a curing agent. Can do.
Examples of the trivalent or higher polyol include glycerin, trimethylolethane, trimethylolpropane, 1,1,1-trimethylolbutane, 1,1,1-trimethylolpentane, 1,1,1-trimethylolhexane, 1,1,1-trimethylol heptane, 1,1,1-trimethylol octane, 1,1,1-trimethylol nonane, 1,1,1-trimethylol decane, 1,1,1-trimethylol undecane, 1,1,1-trimethylol dodecane, 1,1,1-trimethylol tridecane, 1,1,1-trimethylol tetradecane, 1,1,1-trimethylol pentadecane, 1,1,1-trimethylol hexadecane 1,1,1-trimethylolheptadecane, 1,1,1-trimethyloloctadecane, 1,1,1- Trimethylol linear alkanes such as limethylol nanodecane, 1,1,1-trimethylol-sec-butane, 1,1,1-trimethylol-tert-pentane, 1,1,1-trimethylol-tert -Nonane, 1,1,1-trimethylol-tert-tridecane, 1,1,1-trimethylol-tert-heptadecane, 1,1,1-trimethylol-2-methyl-hexane, 1,1,1- Trimethylol-3-methyl-hexane, 1,1,1-trimethylol-2-ethyl-hexane, 1,1,1-trimethylol-3-ethyl-hexane, 1,1,1-trimethylolisoheptadecane Trimethylol branched alkanes such as trimethylol butene, trimethylol heptene, trimethylol pentene, trimethylol Sen, trimethylol heptene, trimethylol octene, trimethylol decene, trimethylol dodecene, trimethylol tridecene, trimethylol pentadecene, trimethylol hexadecene, trimetrole heptadecene, trimethylol octadecene, 3-methylpentane-1 , 3,5-triol, trihydric alcohols such as 1,2,6-hexanetriol;

  For example, pentaerythritol, dipentaerythritol, tripentaerythritol, diglycerin, triglycerin, polyglycerin, ditrimethylolethane, ditrimethylolpropane, tris (2-hydroxyethyl) isocyanurate, inositol, tetrakishydroxymethylphosphonium chloride, Examples thereof include polyhydric alcohols such as sorbitan, sorbitol, mannitol, saccharose, and cellulose, and these can be used alone or in combination of two or more.

In order to adjust the molecular weight of the polyester resin, a monool can be used in addition to the diol and the trivalent or higher polyol.
Monools include, for example, methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecyl alcohol, dodecyl alcohol (lauryl alcohol), tridecyl alcohol, tetradecyl alcohol (myristyl alcohol). , Pentadecyl alcohol, hexadecyl alcohol (cetyl alcohol), heptadecyl alcohol, octadecyl alcohol (stearyl alcohol, octadecanol), nonadecyl alcohol, and isomers thereof (2-methyl-1-propanol (iso-butanol) In addition, other alkanols (C20-50 alcohol), for example, alkenyl alcohols such as oleyl alcohol, Eg to alk dienol such octadienol, for example, aliphatic monool such as polyethylene butylene mono-ol. Moreover, alicyclic monools, such as cyclohexanol and methylcyclohexanol, for example, araliphatic monools, such as benzyl alcohol, etc. are mentioned. These are desirably compounds having a boiling point higher than the reaction temperature of esterification so that they can be condensed in the esterification step.

The polyester resin of the present invention can be obtained, for example, by the following method.
(1) One-step reaction: a dibasic acid component, a diol, and a monobasic acid, a tribasic acid or higher polybasic acid, a trivalent or higher polyol, and a monool, which are used as necessary, at 160 to 280 ° C., preferably 160 to Esterification is performed directly at 240 ° C., and after cooling, the organic solvent is added to prepare the target non-volatile content.
(2) Two-stage reaction: a dibasic acid component, a diol, and a monobasic acid, a tribasic acid or higher polybasic acid, a trivalent or higher polyol, and a monool, which are used as necessary, at 160 to 280 ° C., preferably 160 A dehydration reaction or a transesterification reaction is performed at ˜240 ° C., and then heated to 160 to 280 ° C., preferably 160 to 240 ° C. under a reduced pressure of 5 Torr or less to remove excess hydroxyl group-containing components. It is prepared by adding an organic solvent so as to have a non-volatile content.
Incidentally, when the polymerization temperature is less than the above lower limit, the reaction does not proceed sufficiently. On the other hand, if the polymerization temperature exceeds the upper limit, side reactions such as decomposition may occur or coloring may be easily caused. The reaction time can usually be about 1 to 60 hours.

  In the present invention, the obtained polyester resin preferably contains 10 to 40 mol% of a structural unit derived from 2-methyl-1,3-propanediol. When the polyester resin contains 10 to 40 mol% of the 2-methyl-1,3-propanediol structural unit, the resin can be provided with a good balance of flexibility and cohesive strength. When the amount is less than 10 mol%, the decrease in Tg is not noticeable. When it is more than 40 mol%, the cohesive force is lowered and the adhesive force is lowered.

  In obtaining the polyester resin of the present invention, at least one of an aliphatic dibasic acid having a methylene chain having 6 to 20 carbon atoms or a diol having a methylene chain having 6 to 20 carbon atoms is used. It is preferable to use it. By using these, it becomes easy to impart a low Tg without reducing the cohesive strength of the resin.

Moreover, in this invention, it is preferable to contain 5-40 mol% of structural units derived from ethylene glycol in a polyester resin.
When the proportion of the ethylene glycol structural unit that is easily removed as an excess hydroxyl group-containing component in the two-stage reaction during the resin synthesis is less than 5 mol%, the polymerization reaction is difficult to proceed and it is difficult to obtain a resin having a sufficiently large molecular weight. When it exceeds 40 mol%, the resin becomes too hard and it is difficult to develop an adhesive force.

The glass transition temperature of the polyester resin is preferably −25 to 0 ° C.
When the glass transition temperature is less than −25 ° C., the cohesive strength of the resin becomes too low, and the adhesive strength decreases depending on the type of substrate and curing agent and the measurement conditions. When it exceeds 0 ° C., the tackiness of the resin becomes too low, and the adhesive strength is lowered depending on the type of the base material and the curing agent. Also, the residual solvent tends to increase. The glass transition temperature of the polyester resin was measured with a differential scanning calorimeter (DSC6200 manufactured by SII). The heating rate in the measurement was 10 ° C./min.

  The weight average molecular weight (Mw) of the polyester resin is preferably in the range of 2,000 to 500,000 from the viewpoint of adhesiveness, and more preferably in the range of 4,000 to 200,000. When such a polyester resin is used, an adhesive having excellent adhesion and wettability can be obtained. When Mw is less than 2,000, it becomes difficult to develop the cohesive force as an adhesive layer. On the other hand, when Mw exceeds 500,000, the fluidity of the pressure-sensitive adhesive decreases even if diluted with a solvent. Since coating property falls, it is not preferable. Mw was measured by gel permeation chromatography (GPC) analysis (THF solvent, 40 ° C., polystyrene standard).

In the present invention, structure identification such as quantification of the structural units in the resulting resin with chloroform -D Nippon Denshi nuclear magnetic resonance spectrometer with solvent ^{(NMR) ECX-400, 13} C-NMR analysis And determined from the integration ratio.

In addition, the polyester resin of the present invention contains trimellitic anhydride or trimellitic ester anhydride after or during the polymerization reaction in order to increase acid resistance or oil resistance, or to maintain the adhesive strength over a long period of time. The resin can also be modified by reaction.

  By adding an isocyanate compound and other components as required to the polyester resin of the present invention, an adhesive can be obtained and can be suitably used for dry lamination.

The adhesive of the present invention further includes additives such as, for example, silane coupling agents, antioxidants, ultraviolet absorbers, hydrolysis inhibitors, antifungal agents, thickeners, plasticizers, pigments and fillers. It can be contained if necessary. Moreover, in order to adjust hardening reaction, a well-known catalyst, an additive, etc. can be contained.
The adhesive of the present invention may further contain phosphorus oxyacid or a derivative thereof in order to increase acid resistance.

  The adhesive may also contain a polyol that is unmodified or modified with a polybasic acid or acid anhydride thereof.

  Furthermore, the residual solvent after a drying process can be reduced by adding a very small amount of a high boiling point solvent to the adhesive of the present invention. Examples of the high boiling point solvent to be added include a solvent containing a hydroxyl group, such as DPM (dipropylene glycol methyl ether), TPM (tripropylene glycol methyl ether), PNP (propylene glycol n-propyl ether), DPNP (dipropylene). Propylene glycol n-propyl ether), PNB (propylene glycol n-butyl ether), DPNB (dipropylene glycol n-butyl ether), TPNB (tripropylene glycol n-butyl ether), EDG (diethylene glycol monoethyl ether) ), BDG (diethylene glycol monobutyl ether) and the like. In addition, examples of the high boiling point solvent include polyhydric alcohols (including triols and polyols) such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol.

  The adhesive of the present invention is suitably used in the form of an organic solvent solution. The nonvolatile content concentration of the adhesive according to the present invention in the organic solvent solution is preferably 40% or less, and more preferably about 20% or more and less than 40%. When the non-volatile content concentration is in such a range, it can be easily applied to a sheet-like substrate described later using a general coating apparatus such as a gravure coating machine.

The isocyanate compound contained in the adhesive of the present invention is generally called a curing agent or a crosslinking agent.
In the adhesive of the present invention, the proportion of the isocyanate compound combined with the polyester resin is preferably 0.001 to 20 parts by mass, and 0.01 to 10 parts by mass with respect to 100 parts by mass of the polyester resin. Is more preferable.

  If the proportion of the isocyanate compound is too small, the number of cross-linking points formed in the adhesive will be reduced, heat resistance during retort will be insufficient, peeling will occur after retorting, and the appearance will become whitish (whitening) Tend to. Furthermore, adhesive performance may deteriorate during long-term storage after retorting. On the other hand, if the isocyanate group is excessive, the excess isocyanate group remains unreacted, causing problems in hygiene, taking a long time to disappear, or the crosslinked structure becomes too dense, and the adhesive layer Becomes harder. Therefore, there is a possibility that the adhesion performance with a flexible film (for example, polypropylene) in a laminated structure or a film (for example, nylon) that easily stretches due to the influence of moisture may be deteriorated. Note that the retort is a method of sterilizing foods with bags at high temperature and pressure.

  As the isocyanate compound contained in the adhesive of the present invention, a compound having two or more isocyanate groups is preferably used. An aliphatic diisocyanate, an alicyclic diisocyanate, an aromatic diisocyanate, an araliphatic diisocyanate, a trifunctional or more polyfunctional polyisocyanate. Isocyanate monomer, dimer, trimer, biuret, allophanate derived from the polyisocyanate monomer, poly having 2,4,6-oxadiazinetrione ring obtained from carbon dioxide and the above polyisocyanate monomer Isocyanate or the like can be used. Examples of the aliphatic diisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2, Examples include 4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate, and the like.

Examples of the alicyclic diisocyanate include 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), and methyl. Examples include 2,4-cyclohexane diisocyanate, methyl 2,6-cyclohexane diisocyanate, 1,4-bis (isocyanate methyl) cyclohexane, 1,3-bis (isocyanate methyl) cyclohexane and the like.
Examples of the aromatic diisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4- or 2,6- Examples include tolylene diisocyanate or a mixture thereof, 4,4′-toluidine diisocyanate, dianisidine diisocyanate, 4,4′-diphenyl ether diisocyanate, and the like.

Examples of the araliphatic diisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω′-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-bis (1 -Isocyanate-1-methylethyl) benzene or a mixture thereof.
Examples of the tri- or higher functional polyisocyanate monomer include triphenylmethane-4,4 ′, 4 ″ -triisocyanate, 1,3,5-triisocyanatebenzene, and 2,4,6-triisocyanate toluene. Examples thereof include organic triisocyanates and organic tetraisocyanates such as 4,4′-diphenyldimethylmethane-2,2′-5,5′-tetraisocyanate.

  As the isocyanate compound, the polyisocyanate exemplified above, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3, 3'-dimethylolpropane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol and other adducts with low molecular weight polyols of less than 200, or molecular weights of 200 to 20,000 polyester polyols, polyether ester polyols, polyester amide polyols, polycaprolactone polyols, polyvalerolactone polyols It Le, acrylic polyols, polycarbonate polyols, polyhydroxy alkanes, castor oil, also be used an adduct such as polyurethane polyols.

  Examples of the organic solvent contained in the adhesive of the present invention are inert to isocyanate compounds, such as esters such as ethyl acetate, ketones such as methyl ethyl ketone, and aromatic hydrocarbons such as toluene and xylene. Any material may be used as necessary. However, as described above, as the high boiling point solvent added for the purpose of reducing the residual solvent amount after drying, a solvent having a reactive group such as a hydroxyl group can be used as long as the amount used is small.

A laminate laminate obtained by using the dry laminate adhesive of the present invention will be described. The laminate laminate of the present invention is obtained by laminating a plurality of sheet-like substrates via an adhesive layer formed by an adhesive for dry lamination.
The sheet-like substrate is a plastic film, paper, metal foil, metal-deposited film or the like that is usually used for a laminate for packaging, and the laminated sheet-like substrate may be the same or different.

  As the plastic film, a thermoplastic resin film or a thermosetting resin film can be used, but a thermoplastic resin film is preferable. 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 fiber-based plastic.

In order to make a laminate using the adhesive solution of the present invention, the adhesive solution is applied to one side of one sheet-like substrate by a commonly used method, for example, a gravure coater, and the solvent is evaporated. After forming the adhesive layer, it may be bonded to the other sheet-like substrate and cured at room temperature or under heating. The amount of the adhesive after drying is applied to the sheet-shaped base material surface is preferably about 1 to 10 g / m ^2, more preferably 2-5 g / m ^2. Moreover, as an aging period for polyester and a hardening | curing agent to react after coating, about 1 to 5 days is preferable at 40 degreeC.

The residual solvent concentration contained in the formed adhesive layer is preferably 3.0 mg / m ² or less at a thickness of 3 g / m ² of the adhesive layer. When the residual solvent concentration is higher than 3.0 mg / m ² , toxicity is not considered as a problem, but it may be a problem in terms of sensuality. In particular, toluene and the like emit a petroleum odor that is unrelated to the aroma of foods, and are therefore problematic.
The residual solvent concentration in the adhesive layer can be quantified by gas chromatography using a headspace method.

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

<Synthesis Example 1>
In a four-necked flask, ethylene glycol 15 mol%, 1,6-hexanediol 5 mol%, 2-methyl-1,3-pentanediol 30 mol%, isophthalic acid 20 mol%, terephthalic acid 10 mol%, adipic acid 20 mol% was charged and the ester reaction was carried out at 160 to 240 ° C. for 10 hours while stirring under a nitrogen stream. After distilling a predetermined amount of water, the pressure was gradually reduced, and 230 to 250 ° C. under a reduced pressure of 5 Torr or less. For 5 hours to obtain a polyester resin (1) having a number average molecular weight of 5,000 and an acid value of 0.5 mgKOH / g.

According to the mixing | blending of Table 1, it reacted similarly to manufacture of the said polyester resin (1), and obtained polyester resin (2)-(4).
In addition, the result (unit: mol%) which quantified the structural unit of each obtained resin by NMR is combined with Table 1, and is shown.

<Preparation of adhesive samples (1) to (5)>
The polyester resin obtained in each synthesis example was diluted with ethyl acetate so that the non-volatile content concentration became 60%, and a polyester resin solution was prepared.

According to the composition of Table 2 (the numerical values in the table are parts by mass), 0.3 parts by mass of the silane coupling agent and polyisocyanate with respect to 100 parts by mass of the polyester resin solution obtained in Synthesis Examples (1) to (4) About 20 parts by mass of an ethyl acetate dilute solution (non-volatile content: 70% by mass) of a trimethylolpropane adduct of toluene diisocyanate (TDI-TMP adduct), and BDG (diethylene glycol monobutyl ether) for sample (5), The adhesives of 1) to (5) were prepared.
The adhesive sample (4) does not contain a polyester resin using 2-methyl-1,3-propanediol, and is a comparative example of the present invention.

<Creation of three-layer composite laminate>
Using ethyl acetate, each adhesive sample prepared above was diluted to a non-volatile content of 30%, and a polyethylene terephthalate (PET) film (thickness 12 μm) / adhesive layer (3 g / m ² ) / aluminum (AL) foil A three-layer composite laminate of (thickness 9 μm) / adhesive layer (3 g / m ² ) / unstretched polypropylene (CPP) film (thickness 70 μm) was prepared by the method described below. In addition, polyethylene terephthalate and unstretched polypropylene used the corona discharge treatment surface as the bonding surface.

  First, the adhesive solution was applied to a polyethylene terephthalate (PET) film with a coating machine at room temperature to volatilize the solvent, and then the coated surface was bonded to the aluminum foil surface. Next, an adhesive solution was similarly applied to the aluminum (AL) foil surface of the laminate, and the solvent was evaporated. Then, the coated surface was bonded to an unstretched polypropylene (CPP) film, and a 96 hour atmosphere at 40 ° C. The adhesive layer was cured (aged) by keeping the temperature under the conditions.

(Lamination strength test 1)
A test piece having a size of 15 mm × 300 mm was prepared from the three-layer composite laminate prepared as described above, and using a tensile tester, the peel rate was 30 cm / min at a temperature of 20 ° C. and a relative humidity of 65%. T-type peeling was performed based on JIS K 6854, and the laminate strength (N / 15 mm) between the PET film / AL foil and between the AL foil / CPP film was measured. Furthermore, the appearance was also visually evaluated.

(Lamination strength test 2)
Using the above three-layer composite laminate, make a 14cm x 18cm bag with CPP inside, and fill it with 3% acetic acid / salad oil / ketchup = 1/1/1 (weight ratio) soup And retort treatment at 135 ° C. for 30 minutes.

  After the retort treatment, the bag was opened, and the laminate strength (N / 15 mm) was measured under the same conditions as in the laminate strength test 1. Furthermore, the appearance was also visually evaluated.

(Lamination strength test 3)
In the same manner as in the laminate strength test 2, the bag was retorted with the three-layer composite laminate, and then stored in an environment of 40 ° C. for 14 days.
After storage, the bag was opened, the laminate strength between the AL foil / CPP film was measured in the same manner as in the laminate strength test 2, and the appearance was visually evaluated.

  As a result of the laminate strength tests 1 to 3, the visual evaluation of the appearance and the residual solvent are shown in Table 3. In Table 3, ○ indicates that there is no floating in the laminate in visual evaluation, △ indicates that whitening and floating of the laminate are slightly observed, and X indicates that whitening and many floating of the laminate are observed. Show. In addition, the storage test after retorting is for examining the influence of the contents on the laminate strength between the AL foil / CPP film. The laminate strength between the PET film and the AL foil is not measured because the AL foil functions as a kind of protective layer and hardly changes due to storage after retorting.

<Residual solvent concentration of adhesive layer>
After the adhesive solution is applied to the nylon film with a coating machine at room temperature to evaporate the solvent and form an adhesive layer with a thickness of 3 g / m ² , the coated surface is coated with an LLDPE (linear low density polyethylene) film. The adhesive layer was cured (aged) by being bonded and kept at a temperature of 40 ° C. for 96 hours. Put a 0.2m ² sample in a 500ml Erlenmeyer flask, enclose with a silicone rubber stopper, incubate at 80 ° C for 30 minutes, and then inject 1ml of headspace into GC (gas chromatograph). Concentration was calculated.

Silane coupling agent: γ-glycidoxypropylmethoxysilane polyisocyanate solution: TDI TMP adduct diluted with ethyl acetate (non-volatile content 70%)

Claims (8)

  A dibasic acid component is reacted with a diol containing 2-methyl-1,3-propanediol and contains 10 to 40 mol% of a structural unit derived from 2-methyl-1,3-propanediol. Polyester resin characterized by   The polyester resin according to claim 1, wherein the polyester resin is an aliphatic dibasic acid having a methylene chain having 6 or more carbon atoms or a diol having a methylene chain having 6 or more carbon atoms.   The polyester resin according to claim 1 or 2, comprising 5 to 40 mol% of a structural unit derived from ethylene glycol.   The polyester resin according to any one of claims 1 to 3, having a glass transition temperature of -25 to 0 ° C.   An adhesive for dry lamination comprising the polyester resin according to claim 1 and an isocyanate compound.   A laminate laminate comprising a substrate and an adhesive layer formed from the adhesive for dry lamination according to claim 5.   The laminate laminate according to claim 6, wherein the substrate is a plastic film and a metal foil or a metal vapor-deposited film. The laminate laminate according to claim 6 or 7, wherein the concentration of the solvent contained in the adhesive layer is 3.0 mg / m ² or less at a thickness of 3 g / m ² of the adhesive layer.