JPS63196678A - Adhesive composition for laminating films - Google Patents

Abstract

PURPOSE:To form an adhesive compsn. which has a low viscosity even when it has a high solid content, is quickly curable and has a stable pot life, by blending a specified urethane prepolymer with specified polyether polyol and/or polyester polyol. CONSTITUTION:This compsn. is formed from the following components A and B in a mixing ratio of one equivalent of the free isocyanate group of the component A to 1.0-5.0 equivalents of the hydroxyl group of the component B. [A]: a urethane prepolymer component having a free NCO group content of 2-15%, composed of a trihydric alcohol (1), one or more polyols (2) selected from the group consisting of polyether polyols, polyester polyols and polyether polyester polyols and a polyisocyanate (3). [B]: a polyether polyol component having a number-average MW of 400-4,000 and at least three hydroxyl groups per molecule and/or a polyester polyol component having a number-average MW of 300-2,000 and at least two hydroxyl groups per molecule.

Description

[Detailed description of the invention] [Industrial application field] The present invention has a high solid content and low viscosity during processing, has a stable pot life, has fast curing properties, good adhesive properties, etc. The present invention relates to an adhesive composition for dry laminated films having excellent properties.

[Conventional technology]

Dry lamination is a technology that has a major feature: it allows arbitrary films to be laminated together using adhesives, making it possible to obtain high-performance packaging materials tailored to the purpose.

In this dry laminator, a polycrethane adhesive is used in place of an organic solvent in most cases because of its ease of use, excellent adhesive performance, and excellent durability.

When laminating, the adhesive must be diluted with an organic solvent to reduce the solid content to 2Q~3.
It is prepared to about 50% and then coated into a film. That is, organic solvent equivalent to 65 to 80 parts of the adhesive composition is discharged into the atmosphere.

[Problem that the invention seeks to solve]

Therefore, dry lamination using organic solvent type adhesives faces the following problems, and there is a pressing need for countermeasures.

(1) Emission regulations for organic bath agents (pollution prevention) (2) Resource and energy conservation (3) Improvement of factory working environment (occupational safety and health) (4)
Residual solvent in laminated film (food safety and hygiene)
As a solution to these problems, attempts have been made to reduce the amount of organic solvent, for example, by making it aqueous, making it solvent-free, and increasing solidity.

Among them, adhesives with high solid content that can be processed are conventionally
The purpose is to reduce the organic solvent content by increasing the solid content ratio during application of a solvent-based adhesive, which is about 35%, and to solve the above-mentioned problems.

The higher the solid content ratio of the adhesive during lamination, the more the amount of organic solvent discharged will be reduced. The effects obtained by this are as follows.

(1) Solvent costs are reduced and lightened.

(2) By reducing the drying load, productivity can be improved and energy costs can be reduced.

(3) There is little residual solvent.

However, technical problems arising from increasing the solid content ratio of the adhesive during lamination processing include: (1) The powder drive becomes shorter, which tends to increase the solution viscosity, making it difficult to apply the adhesive uniformly. It is difficult to control the coating amount.

(2) By lowering the viscosity of the adhesive (lowering the molecular weight) in order to achieve a coatable viscosity, the curing speed of the adhesive tends to be slow.

etc.

As a result of intensive research into high solid content type skin contact agents, the present inventors have discovered an adhesive composition for 2-layer films that solves these problems, and have completed the present invention.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present inventors have developed the present invention (410 trihydric alcohol and one or two selected from the group consisting of polyether polyol, polyester polyol, and polyether polyester polyol). Consisting of the above polyol and ■ polyisocyanate, 2
a urethane sol polymer component containing ~15% free NCO groups; and (B) 400-4. For laminates consisting of polyether polyol components having a number average molecular weight of OOO and 3 or more hydroxyl groups in the molecule and/or polyether polyol components having a number average molecular weight of 300 to 2.000 and 2 or more hydroxyl groups in the molecule. In the adhesive composition,
The free incyanate group (-NCO
) is the water r! in the component (B). IR group (-OH
The present invention provides an adhesive composition for laminating films, which is characterized in that the adhesive composition is 1.0 to 5.0 times that of our company.

Examples of the trivalent alcohol used in the present invention as component (4) include trimethylolpropane, glycerin, trimethylolethane, and 1,2.6-hexandriol.

The (4) component polyether polyol used in the present invention is, for example, a linear or branched polyalkylene polyol such as an ethylene oxide or propylene oxide adduct of polyethylene glycol, polypropylene glycol, glycerin, or trimethylolpropane. etc.

(1) A linear or branched polyester having an OH group in its molecular chain obtained by reacting a polybasic acid with a low-molecular-weight polyol can be used as the polyester polyol, which is the active ingredient used in the present invention. Examples of the polybasic acids include anovic acid, azelaic acid, dodecanniic acid, dimer acid, isophthalic acid, hexahydrophthalic anhydride, terephthalic acid, and dimethyl terephthalate. itaconic acid, 7
Examples include malic acid, maleic anhydride, hexahydrophthalic anhydride, or their esters; trimellitic anhydride, trimellitic tribasic acid, and the like. The low-molecular polyols include, for example, nools such as ethylene glycol, butylene glycol, diethylene glycol, and hydrogenated bisphenol A; triols such as glycerin, trimethylol zolopuff; and tetrafunctional or higher functional polyols such as pentaerythritol and nrubitol. Polyols and the like can be mentioned.

In addition, (II) 2-
Trifunctional polyester polyols may also be used.

The polyether polyester polyol of component (4) used in the present invention includes (1) the above-mentioned polybasic acid and the above-mentioned 2
A linear or branched polyester having an OH group in the molecular chain obtained by esterifying a riether polyol or a mixture of this and the low-molecular-weight polyol,
In addition, polyethers obtained by t-addition reaction of alkylene oxide (e.g. ethylene oxide, propylene oxide, etc.) to a polyester having a carboxyl group and/or hydroxyl group at the terminal, and (n) ε-caglolactone opening. A copolymer of a ring polymer and polyzolopylene glycol and/or polytetramethylene glycol can be used.

Examples of the polyisocyanate used in the present invention as component (A) include hexamethylene diisocyanate), o
-1m-6 or p-7 enylene diisocyanate, 2
．． 4- or 2,6-lylene diisocyanate, 2,4-4-lylene diisocyanate with hydrogenated aromatic ring, di7-dylmethane-4,4'-diisocyanate, 3,3'-methyl -4,4'-biphenylene diisocyanate, nocyclohexylmethane-
Examples include 4,4'-diisocyanate, inphorone diisocyanate, ω,ω'-noisocyanate, 1,4-dimethylbenzene, ω,ω'-soisocyanate)-1,3-tumethylbenzene, etc. can be used alone or in combination.

Furthermore, examples of the low-molecular polyol used as necessary in the production of the polyurethane material include the low-molecular polyols mentioned above as raw materials for the polyester polyol. In addition, amino alcohols such as ethanolamine and chloroamine, amino compounds such as ethylenediamine and n-butylamine, water, etc. may be used in the production of polyurethane (4).

The urethane-forming reaction when producing polyurethane (A) may be carried out at a reaction temperature of usually 50 to 100°C in the presence or absence of an organic solvent inert to incyanate groups.Also, when performing the urethane-forming reaction If desired, as a catalyst, for example, butyltin nolaurate, stannath-2-ethylhexoate iron-acetylacetonate, triethylenediamine, N-methylmorpholine, etc., are added in an amount of 5 to 0.2% by weight of O,OO based on the resin solid content. Add so that
The brepolymer (A) having terminal isocyanate groups produced in this way suitably has 2 to 15% free incyanate groups, more preferably 3 to 10%.
Those having free isocyanate groups are suitable.

If the content of free incyanate groups is less than 2%, the viscosity of the polymer becomes high, making it difficult to process with a high solids content. Moreover, when it exceeds 15%, the adhesive cured coating film becomes hard and the adhesion property decreases.

Examples of the polyether polyol as component (B) used in the present invention include glycerin and trimethylolpro
Examples include polyether polyols having three or more hydroxyl groups in the molecule, which are obtained by reacting a polyol having three or more hydroxyl groups in the molecule with ethylene oxide, propylene oxide, or the like. Regarding the number average molecular weight, 400 to 4,000 is preferable, and the number average molecular weight is 4
If it is less than 00, the amount (wt%) of component (4) will be reduced, which will increase the viscosity of the adhesive composition, which is not preferable. In addition, the reaction is fast, the point and trine are short, and processing with a high solids content is difficult. When the number average molecular weight exceeds 4,000, the crosslinking density after curing becomes small, and adhesion tends to occur, resulting in poor adhesive strength, Goyle resistance,
It is not desirable because the heat resistance becomes too fast.

The polyester polyol as the component (B) used in the present invention may be any polyester polyol having two or more hydroxyl groups in the molecule, but in particular it consists of a polyester polyol having three hydroxyl groups in the molecule as a main component. For the most preferred number average molecular weight, 300 to 2,00
Examples of the polyester polyol of component (B), which is preferably 0, include polyester 49ol of component (A).

(B) Component epoxy resin 0-201 silane strength.

, 41j can also be added in an amount of 0 to 10%.

Regarding the mixing ratio of component (A) and component (B), the equivalent of incyanate group in component (4) is 1.0 to 5.0 times the equivalent of hydroxyl group in component (B), more preferably 1 .5-3
．． 5 times is preferable.

The solvent added to the adhesive composition of the present invention may be any organic solvent that does not show reactivity with incyanate groups or hydroxyl groups, such as aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate. Main examples include ketones such as acetone and methyl ethyl lactone. Note that the solvent may be added in advance to the ((conversion)) component or the (four components), or may be added when mixing the (4) component and the (B) component.

Using the adhesive composition for laminated films of the present invention,
For lamination processing, commonly used methods, for example,
A method is employed in which the adhesive is applied to the film surface using a dry laminator, the solvent is volatilized, the adhesive surfaces are brought together, and the composition is cured at room temperature or under heating.

As will be clear from the examples described later, the adhesive composition for laminating films of the present invention can be used as a laminating adhesive for polypropylene, polyethylene, nylon, polyethylene terephthalate, U-deposited film, paper aluminum foil, etc.
It has good adhesion, can be processed with a high degree of adhesiveness during processing, has a long pan life, and has a long pot life.
After lamination, curing is quick.

The present invention will be specifically described below with reference to Examples.

In the examples, all references to "arrogant" mean "% by weight".

〔Example〕

1. (A) Synthesis of urethane fur polymer containing terminal incyanate groups (1) Tolylene diisocyanate (TDI) (2,4/
2.6-isomer weight ratio = 80/20) 522j'-Ethyl acetate 780F was heated to 60°C, glycerin 92p was gradually added, and the mixture was reacted for 4 hours. After that, TDI226
Polypropylene glycol 1.500 F having a number average molecular weight of p, 1,000 was added and reacted at 70C for 10 hours. This polyurethane prepolymer solution (hereinafter referred to as prepolymer A-1) had a solid content of 751NC.
The O group content was 3.5% (4.7% based on solid content), and the viscosity was 2,000 cps/25°C.

(2) TDI 244 p1 acetic acid xfh 167 p,
Polypropylene glycol 100j' having a number average molecular weight of 1,000 was heated to 60° C., 54 ml of trimethylol glomerone was gradually added, and the mixture was allowed to react for 6 hours.

Thereafter, 113 p of TDI and 47 p of polypropylene glycol having a number average molecular weight of 1,000 and 47 p of ethylene glycol were added and reacted at 75° C. for 8 hours. This polyurethane prepolymer solution (hereinafter referred to as A-
Say 11. ) had a solid content of 80%, an NCO group content of 8% (10% based on the solid content), and a viscosity of 2,300 ep/25°C.

(3) TDI 522 p1 ethyl acetate 627 p 60
The mixture was heated to 'C' and 134 jl of trimethylolpropane was gradually added and reacted for 4 hours. Then TDI 22
62.2-functional polycaglolactone polyol (manufactured by Daicel Chemical Industries [Plaxel 208 J]) 1,000 j
' was added and reacted at 70°C for 5 hours. This polyurethane prepolymer solution (hereinafter referred to as Prepolymer A-111) had a solid content of 75%, an NCO content of 4.9 inches (6.5% based on solid content), and a viscosity of 3.000 cps.
/25°C.

2. (B) Component polyether triol "Efsenol 3030J,""Efsenol903J": A trade name manufactured by Asahi Olin Co., Ltd., which is a polyether triol obtained by adding propylene oxide to trihydric alcohol.

a, (B) component polyester polyol polyurethane predelimer A-1, A-11 and A-111;
Polyether polyol and polyester polyol B
-1, B-2, B-3 and B-4t- were mixed to prepare laminate film adhesive compositions Oboro 1 to A6 shown in Table 1.

Table 1 The [NcoloHJ column in Table 1 is a column showing the value obtained by dividing the number of equivalents of free isocyanate groups (-NCO) in the pre-l rift by the number of equivalents of hydroxyl groups (-OH) in the 4-liol. .

The above adhesive composition for laminate film was diluted with total ethyl acetate, and the viscosity and pot life when the solid content was 50% were shown in Table 2.
It was shown to.

Table 2 511J constant conditions: Adhesive solution f 200 ce was poured into a mayonnaise bottle at 2 s° C. and 225 ee, and measurements were taken.

As is clear from Table 2, the adhesive composition for laminate films of the present invention has a low viscosity of 16 to 28 seconds at a solid content of 50%, and a small increase in viscosity even when kept at 40°C.
Pot life is stable.

In addition, in the case of normal dry lamination processing, the solid content of the adhesive is 20 to 35%, and a viscosity in the range of 10 to 30 seconds (Zanka, DE 43) may impede workability and the appearance of the laminated film. This is a condition where no

Next, each of the adhesive compositions for laminated films of the present invention was diluted with ethyl acetate to have a solid content of 50%. Each film was laminated using an ordinary dry laminator, and the curing speed and adhesive strength were measured.

The following commercially available adhesive composition for laminate film was used as a comparative example to clarify the technical effects of the present invention.

Commercial products used: 2 parts of [EP8781J (polyether polyurethane polyol adhesive manufactured by Dainippon Ink & Chemicals ■) and 1 part of KA80J (polyether polyurethane polyisocyanate adhesive manufactured by Dainippon Ink & Chemicals ■) The adhesive composition was diluted with ethyl acetate and used after adjusting the solid content to 25%.

0 curing speed stretched nylon film (thickness 15μ) (hereinafter referred to as N71) and linear low density polyethylene film (thickness 60μ)
μ) (hereinafter referred to as L-LDPE) were laminated together to form a laminate film with a coating amount of each adhesive composition of 2.2/-, and then placed in a constant temperature bath at 20°C. ,2
Bags were made after 4 hours, 48 hours, and 72 hours.

The contents were filled with water and a mixture of water:salad oil=1021. This bag was subjected to an illumination test at 98° C. for 1 hour, and the curing speed of each adhesive composition was determined by examining the peeling state between N)Fl and L-LDPE. The results are shown in Table 3.

As is clear from Table 3, the adhesive composition for laminate films of the present invention has Goyle resistance t- after aging at 20° C. for 24 to 48 hours, and has a fast curing speed.

0 Adhesive Strength A test piece measuring 300 g x 15 m was taken from a laminate film having the film structure shown in Table 4, which was prepared in the same manner as above. Using these +7) E scissors pieces, the adhesive strength was measured by T-peeling at a peel strength of 300 m/min using an Instron type tensile tester. The measured value indicates the adhesive strength (j+/15m) between each component film as the average value of 5 test pieces.

7/'/' Table 4 opp: Stretched polypropylene film (Jl[su60
μ] CPP S unstretched polypropylene film (thickness 6
0μ) PET: Polyethylene tele7 tallate film (Jlt12μ) XxPE: Low-density polyethylene film (thickness 50μ) It has viscosity and stable pot life, and also has excellent effects on curing speed and adhesive strength.

Therefore, when the adhesive composition for laminated films of the present invention is used, solvent costs and drying energy costs can be reduced, productivity can be improved, and the amount of solvent remaining in the laminated film can be reduced.

Claims (1)

[Scope of Claims] (A) (1) trihydric alcohol; (2) one or more polyols selected from the group consisting of polyether polyol, polyester polyol, and polyether polyester polyol; ) a urethane prepolymer component consisting of a polyisocyanate and containing 2-15% free NCO groups; (B) a number average molecular weight of 400-4,000 and 3% in the molecule;
Polyether polyol and/or polyether polyol having hydroxyl groups or more
Or, in a laminating adhesive composition comprising a polyester polyol component having a number average molecular weight of 300 to 2,000 and two or more hydroxyl groups in the molecule, the free isocyanate group (-NCO) in the component (A) is equivalent,
1.0 to 1.0 of the equivalent of the hydroxyl group (-OH) in the component (B)
An adhesive composition for a laminate film, characterized in that the adhesive composition is 5.0 times larger.