JP3325905B2 - Adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive for a composite laminate film, and more particularly, to an adhesive for producing a composite film by laminating various plastic films, metallized films and papers. The present invention relates to a polyurethane adhesive composition that imparts transparency and durability.

[0002]

2. Description of the Related Art Composite films obtained by laminating plastic films such as polyethylene, polypropylene, polyethylene terephthalate and nylon, or laminating these plastic films with metal-deposited films, papers, woven fabrics, etc. are used in foods, pharmaceuticals, cosmetics and households. It is widely used as a soft packaging material for articles and the like. Conventionally, a one-component moisture-curable or two-component curable polyurethane adhesive has been used for bonding the above composite film.

[0003]

The one-component moisture-curable polyurethane adhesive containing polyisocyanate or polyurethane polyisocyanate as a main component does not require the mixing of two components required for a two-component curing type. Although it is excellent in workability, moisture is indispensable for curing the adhesive, and the supply of moisture to the adhesive layer is greatly affected by the surrounding environment. was there. On the other hand, a two-component curable polyurethane adhesive containing a polyol or a polyurethane polyol as a main component and a polyisocyanate or a polyurethane polyisocyanate as a curing agent is generally superior in adhesive strength to a one-component moisture-curable adhesive, and can be used for bonding a composite film. The hardening of the layer is hardly affected by the surrounding environment, and a stable bonding process is possible, which is more advantageous than a one-component curable adhesive. Therefore, two-component curing type is used for most of polyurethane adhesives. However, among the above two-component curable polyurethane adhesives, those using a polyisocyanate or a low molecular weight isocyanate adduct as a curing agent have a high isocyanate content, so that the mixing ratio with the main agent is from 1:10 to 1: 1. : 20, the dispersion of the compounding ratio was large, and the dispersion of the adhesion performance was caused. In addition, the viscosity is generally several thousand [cp
s / 25 ° C] to tens to hundreds [cps / 25 ° C]
And the difference in viscosity is extremely low, so that there is a defect that the mixing and mixing properties during the mixing operation are inferior. Furthermore, for the purpose of overcoming the above-mentioned drawbacks, the molecular weight is increased to lower the isocyanate content, and the mixing ratio with the base agent is made closer to 1: 1 while the viscosity is also increased to improve the mixing and mixing characteristics. A polyurethane polyisocyanate obtained by reacting a polyisocyanate with a polyol having three or more functional groups so that a group remains, or a curing agent mainly comprising a polyurethane polyisocyanate obtained by chain-extending the polyurethane polyisocyanate with some diol is widely used. However, these polyurethane polyisocyanate-based curing agents gradually increase in viscosity during the storage period until they are mixed with the main component, and the viscosity when actually using an adhesive is too high. Workability became extremely poor, and the stability of the solution was impaired, resulting in turbidity There was a defect that is. The present inventors have conducted intensive studies in order to solve the above-mentioned deficiencies of the prior art, and as a result, as a main component of the curing agent, a hydroxyl group having two functional groups and a diisocyanate having two isocyanate groups are obtained. By using a polyurethane isocyanate obtained by subjecting a polyurethane diisocyanate having substantially two functional groups of isocyanate groups to chain extension with a polyol having three or more hydroxyl functional groups, viscosity stability and solution stability during the storage period can be obtained. The inventors have found that they have extremely excellent performance, and have reached the present invention.

[0004]

That is, the present invention provides (1) a two-component curable polyurethane adhesive composition comprising a main component mainly composed of polyurethane polyol and a curing agent mainly composed of polyurethane polyisocyanate;
The mixing ratio of polyurethane polyol (base) to polyurethane polyisocyanate (curing agent) is 1: 3 to 3: 1.
Wherein the polyurethane polyisocyanate is a polyurethane diisocyanate having a functional group of 2 or more obtained from a diol having a hydroxyl group of 2 and a diisocyanate having a functional group of 2 isocyanate groups. An adhesive composition characterized by using a polyurethane polyisocyanate obtained by chain elongation with a polyol of (2), the adhesive composition according to item 1, which contains an organic solvent,
And (3) the viscosity [cps / 25] of the polyurethane polyol (base) to the polyurethane polyisocyanate (curing agent).
C.] is from 1: 3 to 3: 1. Hereinafter, the present invention will be described in more detail.

In the two-part curable polyurethane adhesive composition of the present invention, the polyurethane diisocyanate having substantially two functional groups of isocyanate groups, which is particularly used as a curing agent component, has two functional groups of hydroxyl groups. It is obtained by reacting a diol and a diisocyanate having a functional group number of isocyanate group of 2 by an ordinary method so that an isocyanate group remains at a molecular terminal.
At this time, it is desirable to avoid side reactions that cause branching of the molecular chain as much as possible. That is, it is important to obtain as linear a molecular structure as possible with a diol having a hydroxyl group of 2 and a diisocyanate having an isocyanate group with a functional group of 2. When side reactions that cause branching of the molecular chain are severe, even if a diol having a hydroxyl group of 2 and a diisocyanate having an isocyanate group of 2 are used, the number of functional groups of the isocyanate group is substantially reduced. Is not obtained, and a polyurethane polyisocyanate having substantially more than 2 functional groups of isocyanate groups can be obtained. One of the most important effects of the present invention is that during the storage period of the curing agent, Is not preferred, because the stability of the excellent viscosity in is impaired.

[0006] The diol having a hydroxyl functional group of 2 used for obtaining the polyurethane diisocyanate having a functional group of the isocyanate group of 2 is a conventionally known bifunctional polyol used in ordinary polyurethane production. is there. These bifunctional polyols are used alone or as a mixture of two or more. Preferred examples of such conventionally known bifunctional polyols include, for example,
Polyethylene adipate having a molecular weight of 300 to 10,000, polyethylene propylene adipate, polyethylene butylene adipate, polydiethylene adipate, polybutylene adipate, polyethylene succinate, polybutylene succinate, polyethylene sebacate, polybutylene sebacate, polytetramethylene ether glycol, poly ε-caprolactoneol, polyhexamethylene adipate, polycarbonateol, polyethylene glycol, polypropylene glycol, etc., and their bifunctional polyols,
There is a bifunctional polyurethane polyol obtained by reacting a diisocyanate having a functional group number of 2 with an isocyanate group in accordance with a conventional method using a functional chain extender in combination.
Here, the bifunctional chain extender that may be used to obtain the bifunctional polyurethane polyol includes ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, and water. Etc. However, it is possible to use too much bifunctional chain extender, because it makes it difficult to obtain excellent solution stability during the storage period of the curing agent, which is one of the most important effects of the present invention. It is preferable to keep it as small as possible.

In the present invention, a diisocyanate having two functional groups of an isocyanate group used for obtaining a polyurethane diisocyanate having substantially two functional groups of an isocyanate group refers to at least two diisocyanates in an aliphatic or aromatic compound. Is a bifunctional organic polyisocyanate which has been widely used as a raw material for synthesizing polyurethane resins. Any of these known bifunctional organic polyisocyanates are useful in the present invention. Particularly preferred bifunctional organic polyisocyanates include, for example, tolylene diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-
Phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate-diphenyl ether, methylene diisocyanate,
4,4′-methylenebis (phenyl diisocyanate),
Julylylene diisocyanate, 1,5-naphthalene diisocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate, 4,4-diisocyanate dibenzyl, 1,4-tetramethylene diisocyanate, 1,6-tetramethylene diisocyanate, 1,1
Examples thereof include 0-decamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, xylene diisocyanate, 4,4-methylene bis (cyclohexyl diisocyanate), 1,5-tetrahydronaphthalenediisocyanate, and isophorone diisocyanate.

Next, a polyol having a hydroxyl functional group of 3 or more, which is used in the present invention, for extending a polyurethane diisocyanate having substantially 2 functional groups of isocyanate groups is a conventionally known polyol used in ordinary polyurethane production. Is a polyfunctional polyol having three or more functional groups. These polyfunctional polyols are used alone or as a mixture of two or more. Preferred examples of such conventionally known polyfunctional polyols having three or more functionalities include, for example, polytetramethylene ether glycol having a molecular weight of 300 to 3000, poly ε-caprolactoneol, polycarbonateol, polyethylene glycol, polypropylene glycol and the like. And trimethylolethane, trimethylolpropane, glycerin, triethanolamine,
Quadrol, sorbitol and the like.

The curing agent containing the above-mentioned polyurethane polyisocyanate as a main component has a ratio of the viscosity of the main agent to the curing agent [cps / 25 ° C.] of 1 in order to improve the mixing property.
3 to 3 to 1 (0.333 ≦ base agent viscosity / hardener viscosity ≦
3.00) (particularly preferably 1 to 1), and the set mixing ratio of the main agent to the curing agent (the mixing ratio of the main agent to the curing agent is 1: 1 for better mixing weighability). The number of functional groups of hydroxyl groups is such that the equivalent ratio of isocyanate groups to active hydrogen groups is in the range of 3 to 3: 1, particularly preferably 1: 1), and preferably in the range of 1.2 to 5. The type, molecular weight, compounding ratio, compounding amount of the diol 2 and the kind, compounding ratio, compounding amount of the diisocyanate having the number of isocyanate groups of 2, and the number of functional groups of the isocyanate group obtained substantially from these are 2 It can be obtained by adjusting the type, molecular weight, compounding ratio, compounding amount, and non-volatile content of the polyol having a hydroxyl group functional group number of 3 or more for chain elongation of the polyurethane diisocyanate. The adhesive composition of the present invention is used by mixing the above-mentioned curing agent mainly composed of polyurethane polyisocyanate and the main agent mainly composed of polyurethane polyol at a set blending ratio.

[0010]

The present invention will be described below in detail with reference to examples. Example 1 In a flask equipped with a nitrogen inlet tube, a thermometer, a stirrer and a distillation tube, 700 parts by weight of polypropylene glycol (molecular weight: about 700, bifunctional) as a polyol component, and 4,4′-methylenebis (phenyl diisocyanate) as an isocyanate component ) 500 parts by weight were charged and reacted at a temperature of 70 ° C for 5 hours to obtain a polyurethane diisocyanate having substantially two isocyanate groups. Thereafter, as a chain extender, 60 parts by weight of polypropylene glycol (molecular weight: 300, trifunctional) was added.
, And finally, 315 parts by weight of ethyl acetate was added as a solvent component to obtain a polyurethane polyisocyanate ethyl acetate solution. This is designated as curing agent A.
To 100 parts by weight of the curing agent A, 100 parts by weight of a separately prepared polyurethane polyol (trade name: Seika Bond A150, a product of Dainichi Seika Kogyo Co., Ltd., viscosity 2700 cps / 25 ° C., hydroxyl value 16) was blended to obtain an adhesive composition. Was. Tables 2 and 3 show the storage stability, viscosity, degree of turbidity of the solution, change over time of each of the obtained curing agents A, and the adhesive strength when the adhesive composition was used as the adhesive composition.

Examples 2-3 and Comparative Examples 1-6 Curing of Examples 2-3 and Comparative Examples 1-6 with the polyol component, isocyanate component and chain extender component shown in Table 1 in the same manner as in Example 1. Agents B to I were obtained. Polyurethane polyol (trade name; Seika Bond A150, manufactured by Dainichi Seika Kogyo Co., Ltd., viscosity 2700 cps / 25 ° C., hydroxyl value 16) 100 parts by weight of each obtained curing agent 1
00 parts by weight were obtained to obtain an adhesive composition. Tables 2 and 3 show the storage stability, viscosity, degree of turbidity of the solution, time-dependent changes of each of the obtained curing agents B to I, and the adhesive strength in the case of using the adhesive composition.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

Storage condition of the curing agent: left in a sealed metal can at room temperature Solution condition: good ○ ← △ → × bad (turbidity, poor fluidity, etc.)

[0016]

[Table 4]

Adhesion conditions Adherend Biaxially oriented polypropylene film manufactured by Nimura Chemical Industry Co., Ltd.
FOR # 20 unstretched polypropylene film manufactured by Futmura Chemical Co., Ltd.
FEK-2 # 40 Adhesive Adhesive compositions of Examples and Comparative Examples 1: 1 mixture of main agent and curing agent Coating Biaxially oriented polypropylene film side Drying 95 ° C 3 seconds Hot air Compression 3 kg / cm ² 1 second 25 ° C Aging 40 ° C 48 hours ・ Measurement condition of adhesive strength According to JIS K-6854, pulling speed 300mm /
min, 15mm width

[0018]

The adhesive composition of the present invention has a very small increase in viscosity during storage of the curing agent used therein,
Further, even when stored for a long time, turbidity hardly occurs, and the stability of the solution is excellent. Therefore, the workability of the adhesive is extremely good, and it is useful as an adhesive for a composite laminate.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-10520 (JP, A) JP-A-1-167389 (JP, A) JP-A-2-261882 (JP, A) JP-A-1- 266161 (JP, A) JP-A-61-64777 (JP, A) JP-A-49-339 (JP, A) JP-A-3-281589 (JP, A) JP-A-3-234783 (JP, A) JP-A-3-182584 (JP, A) JP-A-64-54088 (JP, A) JP-A-63-256676 (JP, A) JP-A-2-16181 (JP, A) JP-A-1-213382 (JP, A) JP-A-55-161847 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09J 175/00-201/10 C08G 18/00-18/87

Claims (3)

(57) [Claims] 1. A two-part curable polyurethane adhesive composition comprising a main component comprising a polyurethane polyol as a main component and a curing agent comprising a polyurethane polyisocyanate as a main component .
The mixing ratio of polyisocyanate (curing agent) is from 1: 3 to
A polyurethane diisocyanate having a functional group number of hydroxyl groups of 2 : 1 as the polyurethane polyisocyanate , wherein the polyurethane diisocyanate having a functional group number of 2 is obtained from a diol having a hydroxyl group number of 2 and a diisocyanate having a functional group number of 2; An adhesive composition characterized by using a polyurethane polyisocyanate obtained by elongating a chain with three or more polyols. 2. The adhesive composition according to claim 1, further comprising an organic solvent. 3. The viscosity of a polyurethane polyol (base) to a polyurethane polyisocyanate (curing agent) [cps /
25 ° C.] is from 1: 3 to 3: 1.