JP3114341B2 - Polyurethane adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel polyurethane-based adhesive, and more particularly, it has excellent adhesion to various plastic molded products, metal, wood, rubber, etc. and has high resistance. And a polyurethane adhesive having the same.

[0002]

2. Description of the Related Art In recent years, a plastic film such as cellophane, polyethylene, polypropylene, nylon, polyester, vinyl chloride, an ethylene-vinyl alcohol copolymer and a metal foil such as an aluminum foil have been laminated in several layers as a packaging material for foods and the like. Multilayer composite films have been developed and widely used. In producing the multilayer composite film,
It has been pointed out that polyurethane-based adhesives are often used, but are not always sufficient in terms of adhesive strength and the like.

[0003] In the above polyurethane-based adhesives, the polyurethane resin used therein generally has insufficient adhesion to general-purpose films such as polyethylene films and polypropylene films, and rosin ester resins, ketone resins, and styrene resins are used to improve the adhesion. Tackifiers such as oligomers are commonly used. However,
When these tackifiers are used in combination, the molecular weight is usually low, and thus there is a disadvantage that the physical properties of the adhesive, such as oil resistance and heat resistance, are reduced.

Attempts to improve the disadvantages of the above tackifiers by reacting an isocyanate-terminated urethane prepolymer having a carboxyl group introduced into a side chain by an ester bond with a rosin ester obtained from rosin and a polyhydric alcohol. (Japanese Unexamined Patent Publication (Kokai) No. 2-155978),
The rosin ester could not be completely incorporated into the polyurethane molecules, and the properties as an adhesive were still insufficient due to the considerable low molecular weight remaining.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, that is, excellent adhesiveness to various plastic molded articles such as polyester, nylon, polyethylene and polypropylene when used as an adhesive.
An object of the present invention is 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-mentioned problems, the present inventors have intensively studied not only means for simply mixing rosins but also for positively introducing them into polyurethane molecules. As a result, when a specific polyurethane composed of using a specific high molecular polyol and a rosin skeleton is regularly introduced into a molecule is used as a binder, it is surprising that a tackifier is used in combination. It has been found that all of the above problems can be solved. The present invention has been completed based on such findings.

According to the present invention, there is provided a polyurethane adhesive comprising a polyurethane obtained by reacting a high molecular polyol and a diisocyanate compound, wherein the binder comprises one molecule of a diepoxy compound and two molecules of a rosin as the high molecular polyol component. And a polyurethane having a rosin skeleton in which the content of the reactant is 3 to 60% by weight in terms of the content of rosins per solid content of the produced polyurethane. -Based adhesives: polymer polyols, diisocyanates
Polyurethane obtained by reacting anate compound
In a polyurethane-based adhesive as a binder,
A binder is used as the high molecular polyol component,
Initiator is a reaction product of one molecule of xy compound and two molecules of rosin
Of alkylene oxides or lactones
A cyclic polymer, and the content of the reactant is
3 to 6 in terms of rosin content per solid of ethane
Polyurethane having a rosin skeleton of 0% by weight
And a polyurethane adhesive .

The polymer polyol which characterizes the present invention is:
This is a reactant composed of one molecule of the following diepoxy compound and two molecules of rosin.

As the diepoxy compound, various known diepoxy compounds can be used without any 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-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 And cycloaliphatic cyclic oxiranes such as cyclohexene dioxide.

The rosins include gum rosin, tall oil rosin, wood rosin , disproportionated rosin, hydrogenated rosin and the like. Further, it is more preferable to use purified rosin obtained by distilling these rosins to remove unsaponifiables and contaminants.

The reaction between the above-mentioned diepoxy compound and rosins is not particularly limited and can be easily carried out by employing known reaction conditions. For example, 1 mole of the diepoxy compound and 2 moles of the rosin may be subjected to a ring-opening addition reaction at 120 to 200 ° C. in the presence of a catalyst 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. And organic metal salts. 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 two hydroxyl groups in a molecule (hereinafter referred to as a 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 a rosin-modified polymer polyol) is also similar to the rosin-modified polymer polyol described above. Can be used.

Next, other 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 above. The combination ratio may be appropriately determined such that the rosin-modified polymer polyol or the rosin content is in the range of 3 to 60% by weight in terms of the content of rosin based on the solid content of the produced polyurethane. When the content of the rosin contained in the polyurethane molecule is less than 3% by weight, the adhesion to the plastic molded product and the pigment dispersibility are not sufficient,
If the content exceeds 60% by weight, the polyurethane skeleton becomes too hard, resulting in poor flexibility, which is not preferable.

Examples of various known polymer diols that can be used in combination with the above include, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, , 4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, octanediol, 1,4-butynediol, dipropylene glycol and the like. Various known glycols that are saturated,
alkyl glycidyl ethers such as n-butyl glycidyl ether and 2-ethylhexyl glycidyl ether;
Glycidyl monocarboxylates such as glycidyl versatate and 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, suberic acid or acid anhydrides corresponding thereto Polyesterdiols obtained by condensation reaction with dimer acid, etc., polyetherdiols such as polymers or copolymers such as ethylene oxide, propylene oxide and tetrahydrofuran, and 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 rosin-modified high molecular polyol and the high molecular diol which can be used in combination with the rosin generally have a number average molecular weight of preferably 700 to 10,000.

Examples of the polyisocyanate compound used for 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-
Representative examples thereof include tetramethylxylylene diisocyanate and dimer isocyanate obtained by converting a carboxyl group of a dimer acid into an isocyanate group.
Furthermore, in the adhesive of the present invention, as a curing agent component,
In addition to the above-mentioned diisocyanates, trifunctional or higher-functional isocyanates, for example, adducts of the above-mentioned isocyanates with polyols such as glycerin and trimethylolpropane may be used alone or in combination.

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

If necessary, a chain terminator may be used. Examples of such a chain terminator 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 urethane-forming reaction technique is used. For example, the rosin-modified polymer polyol and
If necessary, a high molecular polyol and a low molecular compound having an active hydrogen atom are mixed and heated to about 40 to 100 ° C. Then, the number of active hydrogen atoms of these compounds and NCO
A polyisocyanate compound is added in a ratio such that the ratio of groups is (NCO group equivalent number) / (Active hydrogen equivalent number of compound having active hydrogen atom) = 2.0 to 0.8, and 50 to 150.
C. to obtain a polyurethane having an isocyanate group or a hydroxyl group at a terminal.

These reactions can be carried out in various organic solvents or without solvent. For example, in the case of a polyurethane adhesive which requires a certain high molecular weight, it is preferable to use a low-toxic solvent having low toxicity, such as ethyl acetate, methyl ethyl ketone, acetone, or the like.
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 preferred.

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

The adhesive of the present invention can also be used as a structural adhesive. For example, in applications such as wood, it is better to use a prepolymer close to the moisture-curable type, and it is generally a one-part type, but a two-part type in combination with an amine or polyol may be used if necessary. .

[0022]

The polyurethane-based adhesive of the present invention can be made of polyester, nylon, polyethylene, polypropylene and the like by using as a polymer polyol component the above-mentioned rosin-modified polymer polyol as an essential component as a binder. Shows excellent adhesion, oil resistance and heat resistance to various plastic molded products.

The reason why the polyurethane adhesive of the present invention exerts the above-mentioned effects is not clear, but the polyurethane comprising the above-mentioned specific polymer polyol has a rosin skeleton having a high tackifying effect and strong hydrophobicity on its side chain. It is presumed that it has almost uniformly.

[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 by weight unless otherwise specified.

Production Example 1 Chinese gum rosin (WG grade, acid value 16) was placed in a round bottom flask equipped with a stirrer, thermometer, cooling tube and nitrogen gas inlet tube.
6.1) 200 parts were charged and heated and completely melted under a nitrogen stream, and then 108.9 parts of 2,2-bis (4-hydroxyphenyl) propane diglycidyl ether was charged with stirring, and 140 ° C. Then, 0.058 parts of 2-methylimidazole was added and reacted at 150 ° C. for 5 hours to obtain a hydroxyl value of 113.0 and an acid value of 1.4 KOHm.
g / g, diol compound (A) 3 having a number average molecular weight of 993
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 the diol compound (A), 313 parts of ε-caprolactone and 0.06 part of dibutyltin laurate, and heated at 170 ° C. under a nitrogen stream. After reacting for 5 hours, the diol compound (A) is used as an initiator, and ε-caprolactone is further subjected to ring-opening polymerization.
g, acid value 0.9 KOHmg / g, number average molecular weight 1975
The diol compound (B) was obtained.

Example 1 Into the same round bottom flask as in Production Example 1, 500 parts of the diol compound (A) obtained in Production Example 1, 500 parts of polybutylene adipate diol having a molecular weight of 2,000, and 267.6 parts of isophorone diisocyanate were placed. Charge, 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 content of rosins in the resin solid content is 25.5%.

Example 2 The same round-bottom flask as 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.
By reacting at 6 ° C. for 6 hours, a prepolymer having a free isocyanate content of 2.56% was obtained. The rosin content in the resin solids 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-pentane adipate) diol 500 having a molecular weight of 2000 were prepared. Parts, 202.3 parts of isophorone diisocyanate,
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
3.4%.

Comparative Example 1 The same round bottom flask as in Production Example 1 was charged with 1,000 parts of polybutylene adipate diol having a molecular weight of 2,000 and 200 parts of isophorone diisocyanate.
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
Rosin ester (trade name: Super Ester S)
(-115, pentaerythritol ester of disproportionated rosin) (430.6 parts) was added thereto, followed by stirring and mixing 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 bonded so that the coating amount was 20 g / m ² .
Adhesive peeling after 30 minutes at room temperature and after standing for 10 days at room temperature (humidity 60
%) Peel strength and heat creep (ambient 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 Days until 1 mm of heat-resistant creep peels off

[0033]

[Table 1]

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08G 18/58 C08G 18/58 18/64 18/64 59/14 59/14 (56) References JP-A-2-155788 ( JP, A) JP-A-57-133114 (JP, A) JP-A-56-70076 (JP, A) JP-A-61-78815 (JP, A) JP-A-61-281119 (JP, A) 63-20316 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09J 175/04-175/08 C08G 18/58 C08G 18/64 C08G 18/42-18/50 C08G 59/14

Claims (3)

(57) [Claims] 1. A polyurethane-based adhesive using a polyurethane obtained by reacting a high molecular polyol and a diisocyanate compound as a binder, wherein the binder comprises one molecule of a diepoxy compound and two molecules of a rosin as the high molecular polyol component. A polyurethane-based adhesive containing a reactant and having a rosin skeleton in which the content of the reactant is 3 to 60% by weight in terms of the content of rosins based on the solid content of the produced polyurethane. Agent. 2. High molecular polyol, diisocyanate
Polyurethane obtained by reacting the compound
In the polyurethane adhesive to be used, the binder
Is a diepoxy compound as the polymer polyol component
A reaction product of one molecule and two molecules of rosin is used as an initiator
Ring-opening polymers of alkylene oxides or lactones
Contains and the content of the reactant is polyurethane solid
3-60% by weight in terms of rosin content per minute
Characterized by a polyurethane with a certain rosin skeleton
Polyurethane adhesive. 3. The polyurethane adhesive according to claim 1, wherein the number average molecular weight of a reaction product of one molecule of the diepoxy compound and two molecules of the rosin is 700 to 10,000.