JPH0689319B2 - Polyurethane resin adhesive - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel polyurethane resin adhesive having excellent adhesive strength, and more specifically, it is excellent in hydrolysis resistance and has a plastic film or a plastic molded product. The present invention relates to a polyurethane resin-based adhesive having excellent adhesion to metals, rubbers and the like.

[Conventional technology]

In general, polyester-based polyurethane resin adhesives are superior in adhesive strength to polyether-based polyurethane adhesives. On the other hand, however, it is the current situation that it is limited in applications requiring hydrolysis resistance. Furthermore, in recent years, for example, as a food packaging material, it has been used as an adhesive or information electronic material for a multi-layer composite film obtained by laminating several layers of plastic film such as cellophane, polyethylene, polypropylene, nylon, polyester, vinyl chloride, etc., and metal foil such as aluminum foil. Polyurethane resin-based adhesives are widely used as adhesives for the above-mentioned films and as undercoating coating agents used to enhance the adhesive strength of these films, but it has been pointed out that the adhesive strength is not always sufficient.

[Object of the Invention]

In view of the present situation, the present inventors have conducted various studies on polycaprolactone polyol-based polyurethane resins, which are excellent in hydrolysis resistance and mechanical strength among polyester-based polyurethane resins, and as a result, ε using bishydroxyethyl terephthalate as an initiator. Polyurethane resin obtained by reacting a polyhydroxy compound having two or more active hydrogens in the molecule containing a polycaprolactone polyol having a number average molecular weight of 500 to 5,000, which is obtained by polymerizing caprolactone By using as an adhesive, it was found that hydrolysis resistance, solution stability and adhesion to various adherends are superior to those using conventional polyester-based polyurethane resins, and the object of the present invention Was achieved.

[Structure of Invention]

The polyurethane resin used in the present invention has a weight average molecular weight of 5,000 to 200,000, preferably 10,000 to 150,000.
When the weight average molecular weight is 5,000 or less, the mechanical strength of the polyurethane resin is low and the adhesive strength is poor. Weight average molecular weight of 200,00
When it is 0 or more, the flowability of the polyurethane resin and the solubility in a solvent deteriorate.

The method for producing the polyurethane resin used in the present invention is appropriately selected from known production methods in consideration of the degree of polymerization of the desired polyurethane resin, the type of raw materials used, and the like.

For example, if necessary, a solvent which is usually inert to an isocyanate group is used, and if necessary, a conventional urethane-forming catalyst is used to produce a polyhydroxy compound having active hydrogen in a temperature range of 10 to 150 ° C, preferably 20 to 130 ° C. The compound is reacted with a stoichiometrically excess polyisocyanate compound to produce a prepolymer having an isocyanate group at the terminal, and then a chain extender such as diol, diamine or triol is reacted to contain a hydroxyl group at the terminal. Or a method in which a polyhydroxy compound, a chain extender and a polyisocyanate compound are simultaneously reacted in a stoichiometrically excess amount of hydroxyl groups to obtain a polyurethane resin having terminal hydroxyl groups. Further, a method of reacting a polyisocyanate compound and a polyhydroxy compound without using a chain extender to obtain a polyurethane resin having a terminal hydroxyl group, and further reacting a polyhydroxy compound and a polyisocyanate compound to obtain a terminal hydroxyl group, and further adding a poly A method of reacting an isocyanate compound to obtain a polyurethane resin having a terminal hydroxyl group can also be adopted.

It is also possible to employ a method in which bulk polymerization is carried out without using a solvent, and cooling and pulverization are carried out to obtain a powdery resin.

In the present invention, polycaprolactone polyol having an average molecular weight of 500 to 5,000 obtained by ring-opening polymerization of ε-caprolactone with bishydroxyethyl terephthalate as an initiator glycol is used as a polyhydroxy compound having two or more active hydrogens in the molecule. Compounds are used.

Bishydroxyethyl terephthalate is 20% by weight of an oligomer having a degree of polymerization of 2 to 4 shown below in addition to a pure monomer.
You can also use the ones included below.

n = 1 monomer n = 2-4 oligomer having a polymerization degree of 2-4 Polycaprolactone polyol is prepared by ring-opening polymerization using bishydroxyethyl terephthalate as an initiator glycol in the presence of ε-caprolactone as a catalyst according to a method known per se. Obtained by

In the present invention, it is necessary to contain the above-mentioned polycaprolactone polyol as a polyhydroxy compound having two or more active hydrogens in the molecule, but other polyhydroxy compounds can be used in combination. Such other polyhydroxy compounds usually have a molecular weight of 50 to 10
Known polyhydroxy compounds generally used for producing polyurethane resins, such as low molecular weight glycols, polyethers, polyesters, polythioethers, polybutadiene glycols, silicon-containing polyols, phosphorus-containing polyols. Etc. can be used.

As the low molecular weight glycols, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, 2- Ethyl-1,3-hexanediol, N-alkyldiethanolamine, bisphenol A and the like are used. Further, a diol having a carboxyl group such as dimethylolpropionic acid or a low molecular weight polyol such as trimethylolpropane can be partially mixed and used.

Examples of polyethers include polymerization products or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran and the like. Further, polyethers obtained by condensation of the low molecular glycols, mixed ethers, and products obtained by addition-polymerizing ethylene oxide and propylene oxide to these polyethers and the low molecular glycol can also be used.

As polythioethers, it is particularly preferable to use thioglycol alone or a condensation product of thioglycol with other glycols.

Examples of the polyesters include polyesters obtained by dehydration condensation reaction of low molecular weight glycols and dibasic acid, and lactone polyols obtained by ring-opening polymerization of lactone such as ε-caprolactone in the presence of the low molecular weight glycols. Can be mentioned.

It is also possible to use a mixture of some trifunctional or higher functional polyols as the polyhydroxy compound.

In the present invention, the content of the polycaprolactone polyol is preferably at least 10 wt% with respect to the total amount of the polyhydroxy compound having two or more active hydrogens in the molecule. Is less than 10 wt%, the adhesiveness and hydrolysis resistance, which are the features of the present invention, cannot be sufficiently expressed, which is not preferable.

Examples of the polyisocyanate compound used for producing a polyurethane resin by reacting with a polyhydroxy compound in the present invention include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, Naphthalene-1,5-diisocyanate,
Organic diisocyanate compounds such as trisine diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, lysine ethyl ester diisocyanate, 4,4 ′ methylenebis (cyclohexyl isocyanate), ω, ω′-diisocyanate dimethylcyclohexane and these organic diisocyanate compounds An addition product with a polyhydric alcohol can be used.

Chain extenders used in the production of polyurethane resins include glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and pentanediol, trimethylolpropane and glycerin. Molecular polyol,
Ethylenediamine, propylenediamine, hydrazine,
Diamines such as piperazine and isophoronediamine can be used.

It is also possible to use the above polyhydroxy compounds as chain extenders.

As the solvent when producing the polyurethane resin in the present invention, usually methyl ethyl ketone which is inactive to an isocyanate group, methyl isobutyl ketone, ketones such as cyclohexanone, ethyl acetate, esters such as butyl acetate,
Aromatic hydrocarbon solvents such as toluene and benzene, tetrahydrofuran and the like are used.

As a catalyst for producing a polyurethane resin, a tin-based, iron-based, or tertiary amine-based catalyst which is a usual urethanization reaction catalyst is used. Examples of the tin-based catalyst include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctoate and stannas octoate. Examples of iron-based catalysts include iron acetylacetonate and ferric chloride. Examples of tertiary nitrogen-based catalysts include triethylamine and triethylenediamine.

In the adhesive of the present invention, the polyurethane resin obtained in the present invention may be used alone or as a cross-linking agent, a low molecular weight polyisocyanate compound may be mixed and used. At this time, pigments and colorants such as carbon black, titanium oxide and silica powder, an ultraviolet absorber and an antioxidant may be added depending on the purpose.

In addition, polyurethane resins, acrylic resins, epoxy resins, which are commonly used to enhance the effect as an adhesive,
It is also possible to use a mixture of a rubber resin, a vinyl chloride resin, a cellulose resin, a polyolefin resin, a polyester resin and the like.

As the low molecular weight polyisocyanate compound, an adduct of an isocyanate compound containing two or more isocyanate groups (adduct with a divalent or trivalent polyhydric alcohol, an adduct such as a dimer or a trimer, and water) Adduct body, etc.) can be used.

Examples of such a low molecular weight polyisocyanate compound include, for example, trade names DESMODULE L, DESMODULE N, manufactured by Bayer AG, Nippon Polyurethane Industry Co., Ltd.
There are trade names such as Coronate L, Coronate HL, Mitec GP105A manufactured by Mitsubishi Kasei Kogyo Co., Ltd., and Mitec NY218A (registered trademark of Mitsubishi Kasei Kogyo Co., Ltd.).

These low molecular weight polyisocyanate compounds are used in a proportion of 3 to 50 (weight)% of the total amount of the binder.

The adhesive of the present invention can be applied to various kinds of adhesive such as adhesion of a multilayer film for food packaging, adhesion of a film for information electronic materials, adhesion between cloths and polyethylene terephthalate, polyethylene film and the like, which are difficult to adhere to undercoating of the film. It can be used for various purposes.

The adhesive of the present invention can be used in various methods depending on the purpose. For example, a doctor blade on both sides or one side of the material to be bonded with an adhesive whose viscosity is adjusted by a solvent, etc.
It is applied by an applicator, a roll coater or the like so as to have a predetermined film thickness. After the application, the solvent is dried until the solvent is almost evaporated. After drying, the surfaces to be bonded are heated to 20 to 160 ° C. for several minutes, and a pressure of several kg / cm ² is applied to bond them.

〔Example〕

Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

<Polyurethane resin synthesis example 1> 100 g of 4,4'-diphenylmethane diisocyanate and 495 g of cyclohexanone were charged into a four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, and a condenser with a drying tube.
The internal temperature was adjusted to 80 ° C and the mixture was stirred. 120 g of polycaprolactone polyol having a number average molecular weight of 800 obtained by ring-opening polymerization of ε-caprolactone with bishydroxyethyl terephthalate as an initiator and a general-purpose bifunctional polycaprolactone polyol having a number average molecular weight of 550 (Placcel 205: Daicel Chemical Industries, Ltd. (Plaxel is a trademark) 110 g was dropped. After the dropping was completed, the reaction was carried out by heating at 80 ° C. for 2 hours to prepare a prepolymer having an isocyanate group at the end. Subsequently, this reaction product was added dropwise to a mixed solution of 5.4 g of 1,4-butanediol and 8.1 g of methyl isobutyl ketone. 6 at 90 ° C after completion of dropping
A heating reaction was carried out for an hour to obtain a polyurethane resin-1.

The completion of the reaction was confirmed by the disappearance of the absorption of the isocyanate group at 2250 cm ^{-1 in} the infrared absorption spectrum.

(Polycaprolactone polyol 51% by weight based on the total amount of polyhydroxy compound) <Polyurethane resin synthesis example 2> 87 g of 2,4-tolylene diisocyanate and 506 g of methyl isobutyl ketone were charged in the same apparatus as in synthesis example 1, and the internal temperature was adjusted. The mixture was brought to 80 ° C. and stirred. A mixed solution of 240 g of caprolactone polyol having a number average molecular weight of 800 and 13.5 g of 1,4-butanediol obtained by ring-opening polymerization of ε-caprolactone using bishydroxyethyl terephthalate as an initiator was added dropwise thereto. After the completion of the dropping, a heating reaction was carried out at 80 ° C. for 2 hours to prepare a prepolymer having an isocyanate group at the end. This reaction product was subsequently treated with 32.5 g of polyoxytetramethylene glycol having a number average molecular weight of 650 and trimethylolpropane 2.2.
g and 52.1 g of methyl isobutyl ketone were added dropwise. After completion of the dropping, a heating reaction was carried out at 90 ° C. for 4 hours to obtain a polyurethane resin-2.

(83% by weight of polycaprolactone polyol relative to the total amount of polyhydroxy compound) <Polyurethane resin synthesis example 3> Obtained by ring-opening polymerization of ε-caprolactone with bishydroxyethyl terephthalate as an initiator in the same apparatus as in synthesis example 1. Charge 60 g of polycaprolactone polyol having a number average molecular weight of 1200, 27 g of 1,4-butanediol, 26.1 g of neopentyl glycol and 207 g of cyclohexanone, and the internal temperature is 80 ° C.
And stirred. To this, 25 g of diphenylmethane diisocyanate was added dropwise, and after completion of the addition, heating reaction was carried out at 90 ° C. for 8 hours to obtain polyurethane resin-3.

(Polycaprolactone polyol 53% by weight relative to the total amount of polyhydroxy compound) <Polyurethane resin synthesis example 4> (Comparative example) In the same apparatus as in Synthesis example 1, 100 g of 4,4'-diphenylmethane diisocyanate and 440 g of methyl isobutyl ketone. Was charged, the internal temperature was adjusted to 80 ° C., and the mixture was stirred. This is a general-purpose bifunctional polycaprolactone polyol with a number average molecular weight of 550.
g was added dropwise. After completion of the dropping, the reaction was carried out by heating at 80 ° C. for 2 hours to prepare a prepolymer having an isocyanate group at the end. Subsequently, this reaction product was added dropwise to a mixed solution of 5.4 g of 1,4-butanediol and 8 g of methyl isobutyl ketone. After completion of the dropping, a heating reaction was carried out at 90 ° C. for 6 hours to obtain a polyurethane resin-4.

<Polyurethane resin synthesis example 5> (Comparative example) 69.6 g of 2,4-tolylene diisocyanate and 433 g of methyl isobutyl ketone were charged into the same apparatus as in Synthesis example 1 and the internal temperature was adjusted to 80 ° C and stirred. To this was added dropwise a mixed solution of 200 g of a polyester diol having a number average molecular weight of 1000 and consisting of 1,4-butanediol and adipic acid and 13.5 g of 1,4-butanediol. After completion of dropping, heat reaction at 80 ° C for 2 hours,
A prepolymer terminated with isocyanate groups was prepared.
Subsequently, 1,4-butanediol was added dropwise to this reaction product. After completion of the dropping, a heating reaction was carried out at 90 ° C. for 6 hours to obtain a polyurethane resin-5.

Examples 1-3, Comparative Examples 1-2 Polyurethane resin (40 wt%) 10 obtained in Synthesis Examples 1-5
For 0 parts, Mitec GP105A (low molecular weight polyisocyanate 75 wt% solution manufactured by Mitsubishi Kasei Co., Ltd., NCO content 1
3.2%) 5.3 parts were mixed and diluted with methyl ethyl ketone to a 20 wt% solution to prepare an adhesive solution. This adhesive solution is applied to 75μ polyester film with a resin coating amount of 30g / m ²
To remove the solvent for 5 minutes at 80 ℃
A polyester film was pressure-bonded at 3 kg / cm ² , and cured and adhered at 80 ° C. for 2 hours, and then cut into a width of 10 mm to prepare an adhesive strength measurement sample.

The adhesive strength was measured using Tensilon UTM-III. The results are shown in Table-1.

Examples 4 to 6 and Comparative Examples 3 to 4 The above-mentioned adhesive solution was applied onto a Teflon film, allowed to stand at room temperature for 30 minutes, and then dried at 80 ° C. for 4 hours to obtain a cured film having a thickness of 100 μm. Mechanical properties and 70 ℃,
Table 2 shows the mechanical properties after 2 weeks under the humid heat condition of 95% relative humidity.

[Effect of the invention] The polyurethane adhesive of the present invention is characterized by using a resin obtained by the reaction of a polyisocyanate compound and the above-mentioned specified polyhydroxy compound. Plastic film, plastic molded product It is recognized that the adhesive strength to the above and the resistance to moist heat of the adhesive layer are excellent.

Claims (2)

[Claims] 1. An adhesive comprising a polyurethane resin obtained by reacting a polyhydroxy compound having two or more active hydrogens in the molecule with a polyisocyanate compound,
A polyurethane resin system characterized by using a polyhydroxy compound containing a polycaprolactone polyol having a number average molecular weight of 500 to 5,000, which is obtained by polymerizing ε-caprolactone using bishydroxyethyl terephthalate as an initiator as the polyhydroxy compound. adhesive 2. A polycaprolactone polyol obtained by polymerizing ε-caprolactone using bishydroxyethyl terephthalate as an initiator is contained at least 10% by weight based on the total amount of the polyhydroxy compound having two or more active hydrogens in the molecule. The polyurethane resin-based adhesive according to claim 1, wherein