WO2013012037A1 - High-solid adhesive composition - Google Patents

Abstract

The present invention addresses the problem of providing: an organic solvent-borne two-pack curable adhesive composition for laminates, which has both pot life stability and fast curing properties even with high solid content by being provided with curing catalyst ability through catalyst-free synthesis that does not use a metal catalyst, an amine catalyst or the like as a curing accelerator for a polyester polyol and an isocyanate; and a laminating method using the adhesive composition. A high-solid adhesive composition which is a two-pack curable adhesive composition for laminates, said adhesive composition containing a polyester polyol component as the base material, while containing a polyisocyanate component as a curing agent. The high-solid adhesive composition is characterized in that the polyester polyol serving as the base material, which is synthesized without using a catalyst, is provided with curing catalyst ability at a resin acid value of 5-20 mgKOH/g.

Description

High solid adhesive composition

The present invention relates to a high solid type adhesive composition, and more specifically, a high solid type adhesive composition used for an adhesive for food packaging, an industrial adhesive, etc., for bonding a plastic film, a metal foil, paper or the like. About.

Adhesive for laminating widely for laminating various kinds of film, metal foil, paper and other laminating materials in order to provide design, functionality, storage, convenience, transportability, etc. for food packaging, industrial products, etc. Agents are widespread.

In recent years, the environment surrounding the flexible packaging industry converter, trends as part of the emission control and life cycle assessment of VOC due to the revision of the Air Pollution Control Law, such as efforts to reduce CO ₂ emissions due to the "visible", such as carbon footprint Is seen. For this reason, there is a demand for a laminate adhesive that can further reduce costs by saving resources and energy.

溶 剤 Solventless adhesives and high solids are attracting attention as a resource-saving, energy-saving, and cost-saving measure for laminate adhesives. A solvent-type two-component curable adhesive composition having a polyol component as a main component and a polyisocyanate component as a curing agent is known (for example, see Patent Document 1). In general, solventless adhesives are not widely used because they have a weaker initial cohesive force than solvent-based adhesives and easily cause poor appearance, and require a special machine. Further, high solid adhesives are known for the purpose of improving initial cohesion and physical properties after curing, and can be applied up to a solid content of 40% (for example, see Patent Document 2). It is an object of the present application to achieve high solid differentiation.

When the coating is applied at a higher solid content, it is necessary to lower the viscosity of the adhesive, and therefore the molecular weight of the resin must be further reduced. In this case, the curing speed (rise of adhesive strength) is slowed down. For this reason, metal catalysts and amine catalysts are conventionally used as the curing accelerator for polyols and isocyanates. However, the pot life (potential time after compounding the curing agent) is shortened and the faster curing is achieved as the blended liquid becomes higher in solid content. It is difficult to balance sex. For this reason, the present condition is that the adhesive whose compounding solid content is 50% or more, the pot life is stable, and the curing speed is high has not yet been obtained.

In recent years, there are concerns about the safety of metal catalysts and amine catalysts, but no alternative curing accelerator has been found. Therefore, in the present invention, a conventional polyester polyol with a resin acid value of usually 2.0 mgKOH / g or less is synthesized, and a curing catalyst ability is exhibited by setting it to 5.0 mgKOH / g or more without using a metal catalyst or an amine catalyst. It was found that both pot life stability and fast curability were achieved even at high solids. In addition, safety is high because no metal catalyst or amine catalyst is used.

That is, an object of the present invention is to make a curing catalyst functional with a polyester acid resin acid value of 5 to 20 mg KOH / g without using a metal catalyst or an amine catalyst as a curing accelerator for polyester polyol and isocyanate. The present invention provides an organic solvent-type two-component curable adhesive composition for laminating that has both pot life stability and fast curability even at a high solid content, and a laminating method using the same.

JP2003-129024 JP-A-2005-298588

An object of the present invention is a two-high solid type two-component curable laminating adhesive comprising polyester polyol and polyisocyanate as essential components, and pot life stability and rapid curing without using a metal catalyst or an amine catalyst. It is an object of the present invention to provide a high solid adhesive composition capable of achieving compatibility of properties.

The present inventor has obtained the following knowledge as a result of intensive studies to solve the above problems.
(1) A polyester polyol synthesized without using a catalyst is used for a high solid type two-component curable laminate adhesive containing polyester polyol and polyisocyanate as essential components.
(2) When the acid value of the polyester polyol is in the range of 5 mgKOH / g or more, such a catalyst is used without using the catalyst usually used for the reaction between the hydroxyl group of the polyester polyol and the isocyanate group of the polyisocyanate. Has the same catalytic ability as
(3) If the acid value of the polyester polyol is in the range of 20 mgKOH / g or less, the pot life can be controlled.
(4) As a result, the pot life can be controlled, and fast curability can be secured. The present invention is based on such knowledge.

That is, the present invention is an organic solvent-type two-component curable laminating adhesive composition having a polyester polyol component as a main component and a polyisocyanate component as a curing agent, and is a non-catalyzed synthesized polyester polyol resin. Provided is a high solid adhesive composition having an acid value of 5 to 20 mgKOH / g.

According to the present invention, the adhesive composition can be applied at a nonvolatile content of 50% by weight or more, and by limiting the resin acid value of the polyester resin of the adhesive to 5 to 20 mg KOH / g, Provided are a high solid adhesive composition having both stability and fast curing problems, and a laminating method using the same.

The present invention will be described in detail below.
The high solid adhesive composition of the present invention is an organic solvent-type two-component curable adhesive composition having a polyol component as a main component and a polyisocyanate component as a curing agent, and is synthesized without a catalyst. The two-component organic solvent-soluble type, characterized by having both a pot life stability and a fast curing property even at high solids by making the resin acid value of polyester polyol of 5 to 20 mg KOH / g a curing catalyst. It is an adhesive composition for a curable laminate.

The composition of the present invention is used in the technical field of dry lamination in which an adhesive is applied to one material surface, the solvent is evaporated to dryness, and the other material is laminated while being heated and pressed.

Since the composition of the present invention can freely bond arbitrary films together and can obtain a composite film having performance according to the purpose, it is widely used in the production of food packaging materials that require high performance. Used.

The composition of the present invention comprises (1) initial adhesiveness for preventing floating immediately after lamination, (2) high normal adhesiveness to various plastic films, metal-deposited films, metal foils, etc., (3) boil, High performance is required for boiling, retort resistance, etc. that do not cause delamination during high-temperature sterilization treatment such as retort, etc. In order to have these functions, as an adhesive for dry lamination, a two-component curing type consisting of a main agent and a curing agent A polyurethane adhesive is used.

As the polyester polyol which is the main component of the composition of the present invention, a polyester or polyester urethane composition component is used.

In order to avoid the use of a metal catalyst, it is preferable that the polyester or polyester urethane is synthesized without a catalyst. The resin acid value of polyester or polyester urethane is preferably 5 to 20 mgKOH / g, more preferably 7 to 17 mgKOH / g. Even if an acid raw material such as a polybasic acid of polyester or polyester urethane raw material is put in the system, it contributes as a curing accelerator for isocyanate group (NCO), but it contributes to final film properties (adhesion, heat resistance, hot water resistance, etc.). In order to have an adverse effect, it is desirable to incorporate the acid into the polyester resin system.

On the other hand, the curing agent of the composition of the present invention may be a general one, an adduct obtained by adding 3 mol of organic diisocyanate to 1 mol of trimethylolpropane, and 1 mol of water to 3 mol of organic diisocyanate. A polyfunctional organic polyisocyanate having a bonding form such as a islet obtained by reacting 3 mol of organic diisocyanate or isocyanurate obtained by polymerization of 3 mol of organic diisocyanate is used. Also, polyisocyanate and polyester polyol, polyether polyol or necessary A polyurethane polyisocyanate compound obtained by reacting these with a low molecular polyol is used.

Furthermore, it is preferable that the non-volatile content of the above-mentioned main agent and curing agent is 50% by weight or more and the Zahn cup viscosity is # 3 in the range of 13 to 30 seconds, preferably in the range of 13 to 20 seconds. Is more preferable.

The polyester resin used in the present invention is obtained by reacting a polybasic acid and a polyhydric alcohol, and various compounds can be used as the polybasic acid.

For example, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis (phenoxy) ethane-p, p′-dicarboxylic acid and These dicarboxylic acid anhydrides or ester-forming derivatives; p-hydroxybenzoic acid, p- (2-hydroxyethoxy) benzoic acid, ester-forming derivatives of these dihydroxycarboxylic acids, and polybasic acids such as dimer acid alone Or a mixture of two or more.

Any known polyhydric alcohol can be used as long as it is known. Specific examples include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, Neopentyl glycol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, 1, 4-cyclohexanedimethanol, triethylene glycol, polycaprolactone diol, dimer diol, bisphenol A, hydrogenated bisphenol A and other glycols, propiolac Polyesters obtained by ring-opening polymerization reaction of cyclic ester compounds such as ethylene, butyrolactone, ε-caprolactone, δ-valerolactone, β-methyl-δ-valerolactone, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, Ethylene oxide using one or more compounds having two active hydrogen atoms such as methylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and the like as an initiator Polyhydric alcohol components such as polyethers obtained by addition polymerization of one or more monomers such as propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran and cyclohexylene by a conventional method are used. Can be used alone or as a mixture of two or more.

Moreover, an adhesion promoter can also be used in the adhesive composition of the present invention. Examples of the adhesion promoter include silane coupling agents, titanate coupling agents, aluminum coupling agents, epoxy resins, and the like.
Examples of the silane coupling agent include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, and N-β (aminoethyl) -γ. Amino silanes such as aminopropyltrimethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane; β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycine Epoxy silanes such as Sidoxypropyltriethoxysilane; Vinylsilanes such as Vinyltris (β-methoxyethoxy) silane, Vinyltriethoxysilane, Vinyltrimethoxysilane, γ-Methacryloxypropyltrimethoxysilane; Hexamethyldisilazane, γ-Mel Hept trimethoxysilane and the like.

Examples of titanate coupling agents include tetraisopropoxy titanium, tetra-n-butoxy titanium, butyl titanate dimer, tetrastearyl titanate, titanium acetylacetonate, titanium lactate, tetraoctylene glycol titanate, and tetrastearoxy titanium. I can list them.

As epoxy resins, commercially available bisphenol type epoxy resins, novolac type epoxy resins, cyclic oxirane type resins, glycidyl ether type resins, glycidyl ester type resins, polyglycol ether type epoxy resins, glycol ether type epoxy resins, Various epoxy resins such as an epoxidized fatty acid ester type resin, a polyvalent carboxylic acid ester type epoxy resin, a glycidylamine type resin, and a resorcinol type epoxy resin can be mentioned.

Furthermore, in the adhesive composition of the present invention, a known acid anhydride can be used in combination as a method for improving the acid resistance of the adhesive layer. Examples of the acid anhydride include phthalic acid anhydride, succinic acid anhydride, het acid anhydride, hymic acid anhydride, maleic acid anhydride, tetrahydrophthalic acid anhydride, hexahydraphthalic acid anhydride, tetraprom phthalic acid Anhydride, tetrachlorophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenotetracarboxylic anhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 5- (2 , 5-oxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride and the like.

Diluting solvents that can be used include, for example, esters such as ethyl acetate, butyl acetate and cellosolve acetate, ketones such as acetone, methyl ethyl ketone, isobutyl ketone and cyclohexanone, ethers such as tetrahydrofuran and dioxane, and aromatic hydrocarbons such as toluene and xylene. , Halogenated hydrocarbons such as methylene chloride and ethylene chloride, dimethyl sulfoxide, dimethyl sulfoamide and the like. Of these, it is usually preferable to use ethyl acetate.

The adhesive of the present invention may be applied by any coating method as long as it is known, but is generally applied by a gravure roll coating method. The application amount of this adhesive is 1.5 to 5 g / m ² , preferably 2 to 4 g / m ² in terms of nonvolatile content.

Hereinafter, the contents and effects of the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. In the examples, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively.

[Preparation Example 1] Preparation of polyol A-1 (resin acid value: 7.0 mg KOH / g, aromatic concentration: 3.0 mmol / g, polyester resin having molecular weight Mn = 1500)
In a polyester reaction vessel equipped with a stirrer, thermometer, nitrogen gas introduction tube, rectification tube, water separator, etc., 40.7 parts of phthalic anhydride, 21.9 parts of sebacic acid, 11.6 parts of ethylene glycol Part and 25.8 parts of neopentyl glycol were gradually heated so that the upper temperature of the rectifying tube did not exceed 100 ° C., and the internal temperature was maintained at 240 ° C. When the resin acid value reached 7.0 ± 1.0 mgKOH / g, the esterification reaction was terminated to obtain a polyester polyol. The obtained polyester polyol is diluted with ethyl acetate to a non-volatile content of 80%, and this is designated as polyol A-1.

[Preparation Example 2] Preparation of polyol A-2 (resin acid value: 12.0 mg KOH / g, aromatic concentration: 3.0 mmol / g, polyester resin having molecular weight Mn = 1500)
In a polyester reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectifying tube, moisture separator, etc., 40.9 parts of phthalic anhydride, 22.3 parts of sebacic acid, 11.7 parts of ethylene glycol Part and 25.1 parts of neopentyl glycol were gradually heated so that the upper temperature of the rectifying tube did not exceed 100 ° C., and the internal temperature was maintained at 240 ° C. When the resin acid value reached 12.0 ± 1.0 mg KOH / g, the esterification reaction was terminated to obtain a polyester polyol. The obtained polyester polyol is diluted with ethyl acetate to a non-volatile content of 80%, and this is designated as polyol A-2.

[Preparation Example 3] Preparation of polyol A-3 (resin acid value: 17.0 mg KOH / g, aromatic concentration: 3.0 mmol / g, polyester resin having a molecular weight Mn = 1500)
In a polyester reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, moisture separator, etc., 41.1 parts of phthalic anhydride, 22.7 parts of sebacic acid, 11.9 parts of ethylene glycol. Part and 24.3 parts of neopentyl glycol were gradually heated so that the upper temperature of the rectifying tube did not exceed 100 ° C., and the internal temperature was maintained at 240 ° C. When the resin acid value reached 17.0 ± 1.0 mg KOH / g, the esterification reaction was terminated to obtain a polyester polyol. The obtained polyester polyol is diluted with ethyl acetate to a non-volatile content of 80%, and this is designated as polyol A-3.

[Preparation Example 4] Preparation of polyol (resin acid value: 2.0 mg KOH / g, aromatic concentration: 3.0 mmol / g, polyester resin having a molecular weight Mn = 1500)
In a polyester reaction vessel equipped with a stirrer, thermometer, nitrogen gas introduction tube, rectification tube, water separator, etc., 40.7 parts of phthalic anhydride, 21.3 parts of sebacic acid, 11.5 parts of ethylene glycol Part and 26.5 parts of neopentyl glycol were gradually heated so that the upper temperature of the rectifying tube did not exceed 100 ° C., and the internal temperature was maintained at 240 ° C. When the resin acid value became 2.0 mgKOH / g or less, the esterification reaction was terminated to obtain a polyester polyol. The obtained polyester polyol is diluted with ethyl acetate to a non-volatile content of 80%, and this is designated as polyol B.

[Preparation Example 5] Preparation of polyol C (resin acid value: 2.0 mg KOH / g, aromatic concentration: 3.0 mmol / g, molecular weight Mn = 1500, adipic acid was added to a polyester resin to obtain a total acid value of 12. 0 mgKOH / g)
Adipic acid (1.35 parts) is dissolved in 100 parts of the polyester polyol obtained by the preparation of polyol B, and diluted with ethyl acetate to obtain a non-volatile content of 80%.

[Preparation Example 6] Preparation of polyol D (resin acid value: 25.0 mg KOH / g, aromatic concentration: 3.0 mmol / g, polyester resin having molecular weight Mn = 1500)
In a polyester reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, moisture separator, etc., 41.0 parts of phthalic anhydride, 23.8 parts of sebacic acid, 12.2 parts of ethylene glycol Part and 23.0 parts of neopentyl glycol were gradually heated so that the upper temperature of the rectifying tube did not exceed 100 ° C., and the internal temperature was maintained at 240 ° C. When the resin acid value reached 25.0 ± 1.0 mg KOH / g, the esterification reaction was terminated to obtain a polyester polyol. The obtained polyester polyol is diluted with ethyl acetate to a non-volatile content of 80%.

(Examples 1 to 3)
Each polyol solution obtained in Preparation Examples 1 to 3 and Sumijour N-3210 (aliphatic polyisocyanate manufactured by Sumitomo Bayern) [E], which is a curing agent, are polyol solution: curing agent = 18: 5. The mixture was further mixed and diluted with ethyl acetate so that the nonvolatile content was 60% to obtain an adhesive composition. The adhesive composition was applied to an ONy (biaxially stretched nylon) film using a test laminator (manufactured by Musashino Machine Co., Ltd.) so that the coating amount was 2.5 g (non-volatile content) / m ^2, and the temperature The ONY adhesive surface coated with the adhesive composition and the LLDPE film were laminated by evaporating the diluting solvent with a drier set at 70 ° C., and a composite film composed of two layers of ONy / LLDPE was prepared. Next, the composite film was aged at 40 ° C. for 3 days to cure the adhesive composition to obtain a two-layer composite film. The following films were used.
ONy film: Unitika Co., Ltd. emblem 15 μm
LLDPE film: TUX-HC 60μm manufactured by Tosero Co., Ltd.

(Comparative Examples 1 to 3)
Instead of the polyol solutions obtained in Preparation Examples 1 to 3, the adhesive compositions obtained in the same manner as in Examples 1 to 3 were used except that the polyol solutions obtained in Preparation Examples 4 to 6 were used. A two-layer composite film was obtained in the same procedure as in Examples 1 to 3.
In Comparative Example 2, adipic acid was added to Preparation Liquid B (resin acid value 2 mgKOH / g) to adjust the total acid value to 12 mgKOH / g.

The following items were evaluated about the obtained adhesive compounding liquid and the two-layer composite film.
(1) Blending viscosity The adhesive composition blended above was measured for seconds in Zaan Cup # 3 at 25 ° C.
○: 13 seconds to less than 20 seconds ×: 20 seconds or more

(2) Pot life (viscosity after promotion)
The adhesive composition blended above was measured at 40 ° C. for 6 hours and the viscosity after 25 hours at Zaan Cup # 3 at 25 ° C.
○: 13 seconds to less than 30 seconds ×: 30 seconds or more

(3) Curing speed The composite film is heat-sealed under the conditions of 40 ° C. × 1 day and 180 ° × 0.1 MPa × 1 second with a width of 10 mm. The sample was cut to a width of 15 mm and the state at break was confirmed at a speed of 300 m / min.
(State at break)
Film break: ○
Triangular peeling or edge breakage: ×

(4) Using the composite film 1 after boil-resistant aging, a pouch having a size of 120 mm × 120 mm is prepared, and the contents are mixed with vinegar, salad oil, and meat sauce in a weight ratio of 1: 1: 1. 70 g was charged. About the produced pouch, the external appearance of the pouch after performing the boil sterilization process for 60 minutes at 98 degreeC was evaluated visually.
○: No change in appearance ×: Delamination

The evaluation results are shown in Tables 1 and 2.

The high solid type adhesive composition of the present invention is suitable for a wide range of fields, such as food packaging materials and electronic materials industrial products that apply composite films and composite materials formed by bonding plastic films, metal foils, paper, etc. Can be used.

Claims (2)

An organic solvent type two-component curable adhesive composition having a polyester polyol component as a main component and a polyisocyanate component as a curing agent, wherein the resin acid value of the polyester polyol as the main component synthesized without catalyst is 5 to A high solid adhesive composition characterized by being 20 mg KOH / g. A high solid adhesive composition having a nonvolatile content of 50% by weight or more and a Zahn cup viscosity of # 3 in the range of 13 to 30 seconds, wherein the main component and the curing agent according to claim 1 are blended.