JPH05263059A - Polyurethane adhesive - Google Patents

Abstract

PURPOSE:To provide a polyurethane adhesive which is excellent in adhesion to various plastics such as polyester, nylon, polyethylene, and polypropylene and in resistance to oil and heat. CONSTITUTION:A polyurethane adhesive contains a binder comprising a polyurethane obtd. by reacting a diisocyanate compd. with a high-molecular polyol component. The polyol component contains a reactional product of 1mol of a diepoxy compd. with 2mol of a rosin compd. in such an amt. that the amt. of the rosin compd. accounts for 3-60wt.% of the resulting polyurethane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel polyurethane adhesive, and more specifically, it has excellent adhesion to various plastic moldings, metals, wood, rubber, etc. and has high resistance. The present invention relates to a polyurethane adhesive.

[0002]

2. Description of the Related Art In recent years, as a packaging material for foods, etc., plastic films such as cellophane, polyethylene, polypropylene, nylon, polyester, vinyl chloride, ethylene-vinyl alcohol copolymer, etc. and metal foils such as aluminum foil are laminated in several layers. The multilayer composite film has been developed and is widely used. When manufacturing the multilayer composite film,
Polyurethane adhesives are often used, but it has been pointed out that they are not always sufficient in terms of adhesive strength.

In the above-mentioned polyurethane adhesives, the polyurethane resin used therefor generally has insufficient adhesion to general-purpose films such as polyethylene film and polypropylene film. Therefore, in order to improve the adhesion, rosin ester resin, ketone resin and styrene are used. Tackifiers such as oligomers are commonly used. However,
When these tackifiers are used in combination, their molecular weight is usually low, and there is a disadvantage that the physical properties as an adhesive, such as oil resistance and heat resistance, are reduced.

Attempts have been made to improve the disadvantages of the tackifiers by reacting isocyanate-terminated urethane prepolymers having carboxyl groups introduced into the side chains by ester bonds with rosin esters obtained from rosins and polyhydric alcohols. (Japanese Patent Laid-Open No. 2-155978),
The rosin ester could not be completely incorporated into the polyurethane molecule, and the low molecular weight substance remained considerably, so the physical properties as an adhesive were still insufficient.

[0005]

The present invention is to solve the above problems, that is, when used as an adhesive, it has excellent adhesiveness to various plastic molded products such as polyester, nylon, polyethylene, and polypropylene.
It is an object of the present invention to provide a novel polyurethane having heat resistance, oil resistance and the like.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the present inventor has conducted earnest studies to actively introduce rosins into polyurethane molecules rather than simply mixing them. As a result, when a specific polyurethane in which a rosin skeleton is regularly introduced into the molecule, which is constituted by using a specific polymer polyol, is used as a binder, a tackifier is surprisingly used together. It has been found that the above problems can be solved without problems. The present invention has been completed based on these findings.

The present invention relates to a polyurethane adhesive containing polyurethane as a binder, which is obtained by reacting a polymer polyol and a diisocyanate compound, wherein the binder comprises 1 molecule of a diepoxy compound and 2 molecules of rosin as the polymer polyol component. A polyurethane system having a rosin skeleton, which contains 3 to 60% by weight of the reaction product in terms of the content of the reaction product in terms of the content of rosin per solid content of the produced polyurethane. Regarding adhesives.

The polymeric polyol characterizing the present invention is
It is a reaction product composed of one molecule of the following diepoxy compound and two molecules of rosins.

As the diepoxy compound, various known diepoxy compounds can be used without particular limitation. Specifically, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene Glycol diglycidyl ether, neopentyl glycol diglycidyl ether,
Acyclic aliphatic diglycidyl ethers such as 1,6-hexanediol diglycidyl ether; 2,2-bis (4-hydroxyphenyl) propane diglycidyl ether, bis (4-hydroxyphenyl) methane diglycidyl ether, 1, 1-bis (4-hydroxyphenyl) ethane diglycidyl ether, 2,2-bis (4-
Hydroxycyclohexyl) propane diglycidyl ether, 3,3 ', 5,5'-tetramethyl-4,4'-
Dihydroxybiphenyl diglycidyl ether, 2,
Aromatic or cycloaliphatic diglycidyl ethers such as 2′-bis (4- (β-hydroxypropoxy) phenyl) propane diglycidyl ether; 3,4-epoxycyclohexylmethyl, 3,4-epoxycyclohexanecarboxylate, vinyl Examples thereof include cycloaliphatic cyclic oxiranes such as cyclohexene dioxide.

Examples of the rosins include gum rosin, tall oil rosin, wood rosin and hydrogenated rosin. Further, it is more preferable to use a purified rosin obtained by distilling these rosins to remove unsaponifiable matters and impurities.

The reaction between the diepoxy compound and the rosins is not particularly limited and can be easily carried out by employing known reaction conditions. For example, the ring-opening addition reaction may be continued at 120 to 200 ° C. in the presence of a catalyst with 1 mol of a diepoxy compound and 2 mols of rosins until the acid value becomes 5 or less, preferably 3 or less. Examples of the catalyst include amine catalysts such as trimethylamine, triethylamine, tributylamine, benzyldimethylamine, pyridine, and 2-methylimidazole, quaternary ammonium salts such as benzyltrimethylammonium chloride, Lewis acids, borate esters, and organometallic compounds. , Organic metal salts and the like can be used. The reaction product obtained by the method has two rosin skeletons and two rosin skeletons.
It is a diol compound having a narrow molecular weight distribution having individual hydroxyl groups in the molecule (hereinafter referred to as rosin-modified polymer polyol). Further, a polymer obtained by ring-opening polymerization of ethylene oxide, propylene oxide, or ε-caprolactone using the present compound as an initiator (hereinafter, referred to as rosin-modified polymer polyol) is also the same as the rosin-modified polymer polyol. Can be used.

Next, other constituent components in the present invention will be described. In the present invention, various known polymer polyols can be used in combination with the rosin-modified polymer polyol or. The combination ratio may be appropriately determined so as to be in the range of 3 to 60% by weight in terms of the content of the rosin per solid content of the rosin-modified polymer polyol or polyurethane produced. When the content of rosin contained in the polyurethane molecule is less than 3% by weight, the adhesiveness to the plastic molded product and the pigment dispersibility are insufficient,
When it exceeds 60% by weight, the polyurethane skeleton becomes too hard and the flexibility becomes poor, which is not preferable.

Examples of various known polymer diols that can be used in combination in the above are, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, octanediol, 1,4-butynediol, dipropylene glycol, etc. Various saturated glycols,
alkyl glycidyl ethers such as n-butyl glycidyl ether and 2-ethylhexyl glycidyl ether,
Monocarboxylic acid glycidyl esters such as versatic acid glycidyl ester, adipic acid, maleic acid,
Dibasic acids such as fumaric acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, azelaic acid, sebacic acid and suberic acid, or acid anhydrides corresponding to these Polyester diols obtained by condensation reaction with dimer acid and the like, polyether diols such as polymers or copolymers of ethylene oxide, propylene oxide and tetrahydrofuran, polyesters obtained by ring-opening polymerization of cyclic ester compounds , Other, polycarbonate polyols,
Examples thereof include polybutadiene glycols and glycols obtained by adding ethylene oxide or propylene oxide to bisphenol A.

The number average molecular weight of the rosin-modified polymer polyol and the polymer diol that can be used in combination therewith are usually preferably 700 to 10,000.

Examples of the polyisocyanate compound used in the production of the polyurethane include various known aromatic, aliphatic or alicyclic diisocyanates. For example, 1,5-naphthylene diisocyanate, 4,4′-
Diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4,4′-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate,
1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-
1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate, m-
Typical examples thereof include tetramethylxylylene diisocyanate and dimerisocyanate obtained by converting a carboxyl group of dimer acid into an isocyanate group.
Furthermore, in the adhesive of the present invention, as a curing agent component,
In addition to the above diisocyanates, trifunctional or higher functional isocyanates, for example, adducts of the above isocyanates with polyols such as glycerin and trimethylolpropane may be used alone or in combination.

Further, in the synthesis of polyurethane, a low molecular weight compound having two or more active hydrogen atoms is usually used as a chain extender. In the present invention, these active hydrogen atom compounds are also used. You can As typical examples of these active hydrogen atom-containing compounds, for example, ethylenediamine, propylenediamine, hexamethylenediamine, triethylenetetramine, diethylenetriamine, isophoronediamine, dicyclohexylmethane-
4,4'-diamine and the like can be mentioned. In addition, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc. in the molecule Representative examples thereof include diamines having a hydroxyl group and low molecular weight glycols described in the above-mentioned polyester diol and dimer diamines obtained by converting a carboxyl group of dimer acid into an amino group.

If necessary, a chain length terminator may be used. Examples of such chain length terminators include di-
Examples thereof include dialkylamines such as n-butylamine and alcohols such as ethanol isopropyl alcohol.

With respect to the method for producing the polyurethane used in the present invention, a known urethanization reaction technique is used. For example, the rosin-modified polymer polyol, and
If necessary, a high molecular weight polyol and a low molecular weight compound having an active hydrogen atom are mixed and heated to about 40 to 100 ° C. Then, the number of active hydrogen atoms and NCO of these compounds
Add a polyisocyanate compound in a ratio such that the ratio of groups is (equivalent number of NCO group) / (equivalent number of active hydrogen of compound having active hydrogen atom) = 2.0 to 0.8
The reaction is carried out at ℃ to obtain a polyurethane having an isocyanate group or a hydroxyl group at the terminal.

These reactions can be carried out in various organic solvents or without solvent. For example, in the case of a polyurethane-based adhesive that requires a high molecular weight to some extent, it is preferable to use a solvent having a low boiling point and low toxicity, such as ethyl acetate, methyl ethyl ketone, and acetone.
Examples thereof include toluene, methyl cellosolve acetate, ethyl cellosolve acetate, cyclohexane, methyl isobutyl ketone, dioxane, cyclohexanone, tetrahydrofuran and dimethylformamide. The amount of the solvent used is 1.0 to 1 with respect to the obtained polyurethane solid content.
5 times by weight is preferable.

When the adhesive of the present invention is used, its composition can be appropriately determined depending on the type of adherend and its application. For example, in an adhesive or the like used for a film for food packaging, since the use of a solvent is not preferable, a method in which a liquid prepolymer before chain extension and the curing agent are mixed and applied, and then a curing reaction and an adhesion are simultaneously adopted is adopted. it can. Here, when the terminal group of the liquid prepolymer is a hydroxyl group, a method of adding triisocyanate (1: 3 adduct of trimethylolpropane and tolylene diisocyanate) or the like and curing it is adopted. When the liquid prepolymer has a terminal isocyanate group, a method of adding an amine, triol or the like and curing it is used.

The adhesive of the present invention can also be used as a structural adhesive. For example, for use in wood, etc., it is preferable to use a prepolymer close to a moisture-curing type, and it is generally a one-pack type, but if necessary, a two-pack type by combining with an amine or a polyol may be used. ..

[0022]

EFFECT OF THE INVENTION The polyurethane-based adhesive of the present invention is made of polyester, nylon, polyethylene, polypropylene, etc. by using polyurethane as a binder, which contains the rosin-modified polymer polyol as an essential component as a polymer polyol component. It exhibits excellent adhesion, oil resistance and heat resistance to various plastic molded products.

Although the reason why the polyurethane adhesive of the present invention exhibits the above effect is not clear, the polyurethane comprising the above-mentioned specific polymer polyol has a rosin skeleton having a high tackifying effect and a strong hydrophobicity in its side chain. It is presumed that it is because they have almost uniform.

[0024]

EXAMPLES The present invention will be specifically described below with reference to production examples, examples and comparative examples, but the present invention is not limited to these examples. Hereinafter, parts and% are based on weight unless otherwise specified.

Production Example 1 In a round-bottomed flask equipped with a stirrer, a thermometer, a cooling tube and a nitrogen gas introduction tube, Chinese gum rosin (WG grade, acid value 16)
6.1) 200 parts were charged, heated under a nitrogen stream to be completely melted, and then 108.9 parts of 2,2-bis (4-hydroxyphenyl) propane diglycidyl ether were added with stirring to 140 ° C. Then, by adding 0.058 part of 2-methylimidazole and reacting at 150 ° C. for 5 hours, a hydroxyl value is 113.0 and an acid value is 1.4 KOHm.
g / g, number average molecular weight 993 diol compound (A) 3
08.6 parts were obtained.

Production Example 2 A round bottom flask similar to that of Production Example 1 was charged with 308.6 parts of diol compound (A), 313 parts of ε-caprolactone and 0.06 part of dibutyltin laurate, and the mixture was heated to 170 ° C. under a nitrogen stream. By reacting for 5 hours, the diol compound (A) is used as an initiator and further ε-caprolactone is subjected to ring-opening polymerization, and the hydroxyl value is 56.8 KOHmg /
g, acid value 0.9 KOHmg / g, number average molecular weight 1975
To obtain the diol compound (B).

Example 1 500 parts of the diol compound (A) obtained in Preparation Example 1, 500 parts of a polybutylene adipate diol having a molecular weight of 2000, and 267.6 parts of isophorone diisocyanate were placed in the same round bottom flask as in Preparation Example 1. Preparation, 1 under nitrogen flow
By reacting at 00 ° C. for 6 hours, a prepolymer having a free isocyanate content of 2.70% was obtained. The rosin content in the resin solid content is 25.5%.

Example 2 A round-bottomed flask similar to that used in Production Example 1 was charged with 1000 parts of the diol compound (B) obtained in Production Example 2 and 202.3 parts of isophorone diisocyanate, and the mixture was heated to 100 in a nitrogen stream.
A prepolymer having a free isocyanate content of 2.56% was obtained by reacting at 6 ° C. for 6 hours. The rosin content in the resin solid content is 26.7%.

Example 3 In the same round bottom flask as in Production Example 1, 500 parts of the diol compound (B) obtained in Production Example 2 and poly (3-methyl-1,5-pentaneadipate) diol 500 having a molecular weight of 2000 were used. Part, 202.3 parts of isophorone diisocyanate,
Was charged and reacted at 100 ° C. for 6 hours under a nitrogen stream to obtain a prepolymer having a free isocyanate content of 2.65%. The rosin content in the resin solid content is 1
It is 3.4%.

Comparative Example 1 A round-bottomed flask similar to that used in Production Example 1 was charged with 1000 parts of polybutylene adipate diol having a molecular weight of 2000 and 200 parts of isophorone diisocyanate, and charged under a nitrogen stream at 10
By reacting at 0 ° C. for 6 hours, a prepolymer having a free isocyanate content of 2.60% was obtained.

Comparative Example 2 Diisocyanate prepolymer 1000 obtained in Comparative Example 1
Further rosin ester (brand name: Super Ester S
(-115, pentaerythritol ester of disproportionated rosin) (430.6 parts) was added, and the mixture was stirred and mixed at 100 ° C. for 1 hour to obtain a prepolymer having a free isocyanate content of 1.75%. The rosin content in the resin solid content is 26.7.
%.

Using the prepolymers of Examples 1 to 3 and Comparative Examples 1 and ² , corona discharge treated polypropylene (0.3 mm) was laminated so that the coating amount was 20 g / m ² .
Adhesive peeling after 30 minutes at room temperature and after 10 days at room temperature (humidity 60
%) Peel strength and heat-resistant creep (environmental temperature 70 ° C, 1
Kg load) was evaluated under the following conditions. The evaluation results are shown in Table 1. (Evaluation of adhesiveness) Tensile speed: 100 mm / min Measurement: T-type peel strength Heat resistant creep 1 mm Days until peeling

[0033]

[Table 1]

Claims (2)

[Claims] 1. A polyurethane adhesive containing polyurethane as a binder, which is obtained by reacting a polymer polyol and a diisocyanate compound, wherein the binder is the diepoxy compound 1 as the polymer polyol component.
A polyurethane having a rosin skeleton containing a reaction product of a molecule and two molecules of a rosin, and the content of the reaction product is 3 to 60% by weight in terms of the content of the rosin per solid content of the produced polyurethane. A polyurethane adhesive characterized in that 2. The polyurethane adhesive according to claim 1, wherein the number average molecular weight of the reaction product of one molecule of diepoxy compound and two molecules of rosins is 700 to 10,000.