JP7413648B2 - Urethane resin composition, adhesive composition, and method for producing articles - Google Patents

Description

The present invention relates to a urethane resin composition, an adhesive composition using the urethane resin composition, and a method for manufacturing articles.

Conventionally, resin base materials such as polypropylene have been widely used industrially. For example, resin base materials are often used in automobiles, electrical appliances such as washing machines and refrigerators, and electronic devices such as smartphones and personal computers. This is because resin base materials have the advantage of being lighter and cheaper than metal materials, and are easier to mold and process. There are also specific uses for resin base materials such as films; for example, films made of polyethylene terephthalate are widely used as base materials for release films used in the manufacturing process of food packaging materials and electronic materials.

It is generally known that the surface of a resin base material is less wettable than that of a metal base material. The difficulty of wetting the surface of a resin base material (hereinafter referred to as "difficulty of wettability") can cause defects such as repellency when applying adhesives or paints, making it impossible to obtain a uniformly coated surface. , undesirable. In addition, it is known that substrates that exhibit poor wettability generally exhibit poor adhesion, which can cause serious defects such as poor adhesion in the case of adhesives and peeling of the paint film in the case of paints. This is undesirable.

Methods for improving wettability include changing the composition of the resin base material and surface modification.

As a method of changing the composition of a polypropylene base material, for example, a method of reacting polypropylene with an unsaturated carboxylic acid and an aromatic vinyl monomer has been reported (Patent Document 1), but sufficient improvement in wettability has not been achieved. First, there were problems such as insufficient reaction yield.

As a surface modification method, for example, corona treatment is conventionally known and has already been put into practical use (Non-Patent Document 1). However, it is not necessarily versatile enough because it requires large equipment and a large investment in equipment, and it is difficult to set optimal conditions. Therefore, there were problems such as concerns about a decrease in mechanical strength.

As described above, although there is a strong desire for a method that can sufficiently adhere to a substrate that exhibits poor wettability, the methods are limited.

Japanese Patent Application Publication No. 2009-13230

Japan Rubber Association Journal 1997 70 333

An object of the present invention is to provide a urethane resin composition that can provide good adhesion to plastic substrates such as polypropylene.

As a result of intensive research to solve the above problems, the present inventors have discovered that a urethane resin composition, which is a reaction product with a specific polyol compound and a polyisocyanate compound, is effective against plastic substrates such as polypropylene. It was discovered that the adhesive exhibited good adhesion, and the present invention was completed.

That is, the present invention includes the embodiments shown below.

The urethane resin composition of the present invention is characterized by being a reaction product of a compound (A) represented by the following general formula (1) and a polyisocyanate compound (B).

[In general formula (1), R is a hydrocarbon group having 40 to 500 carbon atoms (here, the hydrocarbon group may have a straight chain, branched chain, or cyclic structure, and may be a saturated hydrocarbon or an unsaturated hydrocarbon group) hydrogen). ].
In the urethane resin composition of the present invention, the compound (A) represented by general formula (1) (hereinafter also referred to as compound (A) or simply (A)) has hydroxyl groups on different carbon atoms in the molecule. , a polyol polyolefin having 50 to 400 carbon atoms is preferable.

The number average molecular weight of the urethane resin composition of the present invention is preferably 3,000 to 250,000.

In the urethane resin composition of the present invention, the content of compound (A) is preferably 30% to 99.9% by mass.

The adhesive composition of the present invention is characterized by containing the urethane resin composition of the present invention.

The adhesive layer of the present invention is characterized in that it is obtained from the adhesive composition of the present invention.

An article having an adhesive layer of the present invention is characterized by having the adhesive layer of the present invention on a base material.

The article having an adhesive layer of the present invention is preferably obtained by heating the adhesive layer and the base material.

In the article having an adhesive layer of the present invention, the base material is preferably plastic. Preferably, the substrate is a polyolefin.

The article having an adhesive layer of the present invention may include another base material apart from the adhesive layer and the base material.

The article having an adhesive layer of the present invention may include, in addition to the adhesive layer and the base material, a base material coated with a resin.

The method for producing an article having an adhesive layer according to the present invention is preferably a heat treatment method.

The method for producing an article having an adhesive layer of the present invention is preferably a method of heat treatment at 70° C. or higher.

According to the present invention, a urethane resin composition can be obtained that exhibits good adhesion to resin substrates that exhibit difficult wettability, such as polypropylene.

The urethane resin composition of the present invention is characterized by being a reaction product of a compound (A) represented by the following general formula (1) and a polyisocyanate compound (B).

[In general formula (1), R is a hydrocarbon group having 40 to 500 carbon atoms (here, the hydrocarbon group may have a straight chain, branched chain, or cyclic structure, and may be a saturated hydrocarbon or an unsaturated hydrocarbon group) hydrogen). ].

The compound (A) of the present invention is not particularly limited, but includes, for example, polyol polyolefins having an unsaturated skeleton such as polybutadiene, polyisoprene, polystyrene, polyethylene, polypropylene, hydrogenated polybutadiene, polybutene, hydrogenated Examples include polyol polyolefins having a saturated skeleton such as polyisoprene. Among these, from the viewpoint of adhesion, the number of carbon atoms is preferably 50 to 400, more preferably 75 to 375, and most preferably 100 to 230. From the viewpoint of resin polymerizability, it is preferable to have a hydroxyl group at the end of the molecule. Further, polybutadiene, polyisoprene, hydrogenated polybutadiene, and polyol polyolefins having a hydrogenated polyisoprene skeleton are preferred, and hydrogenated polybutadiene and polyol polyolefins having a hydrogenated polyisoprene skeleton are more preferred.

The polyisocyanate compound (B) of the present invention (hereinafter also simply referred to as (B)) is not particularly limited, but examples include diphenylmethane-4,4'-diisocyanate and diphenylmethane-2,4'-diisocyanate. , 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, 1,4-tetramethylxylylene diisocyanate, etc. Isocyanates with an aromatic skeleton, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane-4,4'-diisocyanate, hydrogenated diphenylmethane-2,4'-diisocyanate, hydrogenated xylylene diisocyanate, 2,2,4-trimethyl Examples include isocyanates having an aliphatic skeleton such as hexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate. These may be monomers or multimers, and may be allophanate-modified or biuret-modified. Among these, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 2,4-toluene diisocyanate, and 2,6-toluene diisocyanate are preferred from the viewpoint of surface hardness and mechanical strength, and from the viewpoint of light resistance. Among them, hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane-4,4'-diisocyanate, and hydrogenated diphenylmethane-2,4'-diisocyanate are preferred. These may be used alone or in combination of two or more.

In the present invention, in addition to (A) and (B), another component (C) may be optionally used in the reaction within a range that does not impair the object of the present invention. Other components are not particularly limited, and include, for example, polyether polyols such as polyethylene glycols, polypropylene glycols, and polybutylene glycols, caprylic acid monoglyceride, capric acid monoglyceride, lauric acid monoglyceride, stearic acid monoglyceride, and behenic acid monoglyceride. Examples include monoglycerides such as , polyols such as . These may be used alone or in combination of two or more.

The content of (A) in the reaction products of (A) and (B) is preferably 30% to 99.9% by mass, more preferably 60% to 99%, and most preferably 80% to 98%. preferable. In addition, also when reacting other component (C), it is preferable that (A) has the said content. If the mass ratio is less than 30% or more than 99.9%, there is a concern that the adhesion may be insufficient.

The number average molecular weight of the urethane resin composition which is the reaction product of (A) and (B) is preferably 3,000 to 250,000, more preferably 3,000 to 100,000, and 3,000 to 25,000. Most preferred. In addition, also when reacting other component (C), it is preferable that it has the said molecular weight.

The urethane resin composition of the present invention may optionally contain other components other than (A) and (B) as long as the object of the present invention is not impaired. Other components are not particularly limited, and include, for example, a solvent, a catalyst, an antifoaming agent, a leveling agent, an organic thickener, an antioxidant, a light stabilizer, an adhesion improver, a mold release agent, a reinforcing material, and a softening agent. agents, colorants, flame retardants, antistatic agents, wetting and dispersing agents, etc.

The solvent is not particularly limited, and includes, for example, aromatic hydrocarbon solvents such as toluene, ethylbenzene, trimethylbenzene, and xylene, aliphatic hydrocarbon solvents such as pentane, hexane, and cyclohexane, acetone, methyl ethyl ketone, and methyl isobutyl. Ketones, ketone solvents such as cyclohexanone, alcohol solvents such as methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl diglycol, ethyl diglycol, butyl diglycol Glycol, glycol ether solvents such as propylene glycol monomethyl ether, ester solvents such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide , amide solvents such as N-methylpyrrolidone, ether solvents such as diethyl ether and tetrahydrofuran, and water. These may be used alone or in combination of two or more.

When the urethane resin composition of the present invention contains a solvent, the content may be selected depending on the coating method and the desired thickness of the urethane resin coating film, and is not particularly limited. The amount is preferably 1.0 to 10,000 parts by weight, more preferably 40 to 3,200 parts by weight, and most preferably 150 to 2,000 parts by weight. If the content is less than 1.0 parts by mass, the viscosity of the urethane resin composition may increase and coating may become difficult, and if it exceeds 10,000 parts by mass, the thickness of the urethane resin coating may become thin. , there is a risk that a sufficient film thickness may not be obtained.

The catalyst is not particularly limited, and examples thereof include organometallic compounds such as dibutyltin diacetate, dibutyltin dilaurate, and dioctyltin dilaurate, organic amines such as triethylenediamine and triethylamine, and salts thereof. These may be used alone or in combination of two or more.

When the urethane resin composition of the present invention contains a catalyst, the content may be selected depending on the reactivity of the polyisocyanate compound used, and is not particularly limited, but is 0.00010 to 1 part by mass of the urethane resin composition. It is preferably 25 parts by weight, more preferably 0.0010 to 6.0 parts by weight, and most preferably 0.010 to 1.0 parts by weight. If the content is less than 0.00010 parts by mass, a sufficient catalytic effect may not be obtained, and if it exceeds 25 parts by mass, the economical efficiency may become poor.

Leveling agents are not particularly limited, and examples include polyoxyethylene alkyl ethers, polyoxyethylene aryl ethers, silicone surfactants, nonionic surfactants, fluorine surfactants, acrylic surfactants, etc. can be mentioned. These may be used alone or in combination of two or more.

When the urethane resin composition of the present invention contains a leveling agent, its content is not particularly limited, but it is preferably 0.0010 to 25 parts by mass, and 0.0010 to 25 parts by mass, based on 100 parts by mass of the urethane resin composition. More preferably, the amount is from 0.010 to 12 parts by weight, and most preferably from 0.050 to 6 parts by weight. If the content is less than 0.0010 parts by mass, the leveling properties may be insufficient, and if it exceeds 25 parts by mass, the adhesion of the urethane resin coating may be insufficient.

The coating film obtained from the urethane resin composition of the present invention exhibits good adhesion to various substrates including difficult-to-wet substrates.

The material of the base material is not particularly limited, and includes, for example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polycarbonate, acrylonitrile-butadiene-styrene copolymer synthetic resin (ABS resin), nylon 6, nylon 66, aramid, acrylic, polyethylene. Resins such as terephthalate and polybutylene terephthalate, composite materials made of the above-mentioned resin base materials and glass fibers, thermosetting resins such as epoxy resins, or composite materials of thermoplastic resins such as polyphenylene sulfide and carbon fibers (CFRP, CFRTP), aluminum, aluminum alloy, magnesium, stainless steel, tin plate, electrogalvanized steel sheet, chrome-plated steel sheet, etc., glass, and the like. These base materials may be used alone, or two or more of them may be used in combination or as a composite material. Among these, resin base materials are preferred because they have high versatility, such as ease of molding after painting, and polyethylene, polypropylene, and polystyrene are more preferred because they are lightweight and inexpensive.

The urethane resin composition of the present invention explained above can be suitably used in an adhesive composition.

The method of forming an adhesive layer using the adhesive composition of the present invention is not particularly limited, and includes, for example, a method of applying the adhesive composition of the present invention to at least one surface of a base material and then drying the adhesive composition. can be mentioned.

The method for applying the adhesive composition of the present invention is not particularly limited, and examples thereof include an applicator method, a bar coating method, a spin coating method, a spray coating method, a dip coating method, a nozzle coating method, a gravure coating method, and a reverse roll coating method. Coating method, die coating method, air doctor coating method, blade coating method, rod coating method, curtain coating method, knife coating method, transfer roll coating method, squeeze coating method, impregnation coating method, kiss coating method, calendar coating method, extrusion coating method etc.

The drying temperature during drying is not particularly limited, but is preferably 70 to 300°C, more preferably 100 to 250°C, and most preferably 150 to 230°C. If the drying temperature is less than 70°C, residual solvent may become a problem, and if it exceeds 300°C, the adhesive layer may thermally decompose. Further, the drying time is not particularly limited, but is preferably from 5 seconds to 10 days, and more preferably from 20 seconds to 6,000 seconds. If the drying time is less than 5 seconds, drying may be insufficient, and if it exceeds 10 days, the time required for the process becomes longer, which is not preferable from the viewpoint of productivity.

When bonding the base material having the urethane resin adhesive layer of the present invention to another base material, the other base material may be bonded unpainted, or the other base material may be bonded to the other base material. A resin having affinity may be applied and used for adhesion. When applying a resin that has affinity with other base materials, the resin composition is not particularly limited as it is selected depending on the base material, and examples thereof include urethane resins, epoxy resins, acrylic resins, and the like. Among these, urethane resins are preferred in consideration of their affinity with the urethane resin adhesive layer of the present invention. Moreover, the urethane resin applied to other base materials may be the same as or different from the urethane resin of the present invention. The conditions for applying and drying the resin on other base materials are the same as the conditions for drying the urethane resin of the present invention.

The temperature at which the base material having the urethane resin adhesive layer of the present invention is bonded to another base material is not particularly limited, but is preferably 70 to 300°C, more preferably 100 to 250°C. Preferably, the temperature is 150 to 230°C, most preferably. If the treatment temperature is less than 70°C, there is a risk of poor adhesion due to residual solvent, and if it exceeds 300°C, the urethane resin coating may thermally decompose. Furthermore, the treatment time is not particularly limited, but is preferably from 1 second to 10 days, more preferably from 20 seconds to 6,000 seconds. If the treatment time is less than 1 second, poor adhesion may occur, and if it exceeds 10 days, the time required for the process becomes longer, which is not preferable from the viewpoint of productivity.

The thickness of the adhesive layer is not particularly limited, but is preferably from 0.05 to 300 μm, more preferably from 0.1 to 200 μm. If the thickness is less than 0.05 μm or more than 300 μm, the adhesion of the adhesive layer may be insufficient.

Examples of the present invention will be described below, but the present invention is not limited to these Examples. Note that unless otherwise specified, percentages are expressed on a mass basis.

(Example 1)
A urethane resin composition was manufactured, a test piece was prepared, and the physical properties of the coating film were evaluated in the following manner. The results are shown in Table 1.

<Manufacture of urethane resin composition>
In a 2 L four-neck separable flask equipped with a stirrer, a thermometer, a heating device, and a reflux tube, 150.0 g of hydroxyl-terminated hydrogenated polyisoprene and diphenylmethane-4,4'-diisocyanate (hereinafter referred to as MDI) were placed. Product name: Millionate MT, isocyanate group content 31.3%, manufactured by Tosoh Corporation), 0.105 g of dioctyltin dilaurate, and 1505 g of cyclohexanone were charged at room temperature, and then nitrogen gas was blown into the solution. The inside of the flask was replaced with nitrogen. A urethane resin composition was obtained by reacting these for 2 hours while stirring uniformly at 80°C. The number average molecular weight and viscosity of the obtained urethane resin composition were measured by the following methods.

<Measurement of number average molecular weight>
It was determined by gel permeation chromatography (GPC). The conditions are as follows. The device is a high-speed GPC device (HLC-8220 manufactured by Tosoh Corporation), and the columns are G3000H-XL, G2500H-XL, G2000H-XL, and G1000H-XL (all manufactured by Tosoh Corporation), each connected in series in the order listed. was used, tetrahydrofuran was used as the mobile phase, and the mobile phase rate was 1.00 mL/min. The column temperature was 40° C., a differential refractometer was used as a detector, and the molecular weight was determined as a polystyrene equivalent molecular weight. A THF solution with a concentration of 0.5% was prepared and used as the sample solution.

<Measurement of viscosity>
Measurement was performed using a B-type viscometer (Vismetron VS-A1 manufactured by Shibaura System Co., Ltd.) in accordance with JIS7117-2.

<Creation of test piece>
First, the urethane resin composition obtained above was applied to a polypropylene base material (Kobe Poly Sheet PP manufactured by Hitachi Chemical Co., Ltd.) using a bar coater, left to stand for 5 minutes at room temperature, and then dried in a hot air dryer. A polypropylene test piece having an adhesive layer with a dry film thickness of 10 μm was obtained by drying at 80° C. for 5 minutes. Next, a polyurethane resin (Nipporan-5288, manufactured by Tosoh Corporation, trade name) different from the urethane resin composition of the present invention was coated on a polyethylene terephthalate film (Toyobo Ester Film E5100, manufactured by Toyobo) using a bar coater, and the film was coated under room temperature conditions. After being allowed to stand for 5 minutes under a hot air dryer, it was dried at 80° C. for 5 minutes to obtain a polyethylene terephthalate film test piece having a polyurethane resin layer with a dry film thickness of 10 μm. Then, each of the obtained test pieces was pasted together so that the adhesive layer and the polyurethane resin layer were in contact with each other, and then heat-treated at a specified temperature for 10 minutes to obtain a test piece. Here, the heat treatment was performed at 80°C or 185°C, and test pieces were created for each case.

<Evaluation of adhesive physical properties>
A 180 degree peel test was performed on the test piece obtained by pasting together in accordance with JIS K6854-2 to evaluate the adhesive strength. The test was carried out using an Autocom type tester (UTPS-Acs (S) manufactured by TSE).

(Example 2)
In a 2 L four-neck separable flask equipped with a stirrer, thermometer, heating device, and reflux tube, 150.0 g of hydroxyl-terminated hydrogenated polyisoprene, 17.3 g of MDI, 0.105 g of dioctyltin dilaurate, After charging 1,507 g of cyclohexanone at room temperature, the inside of the flask was purged with nitrogen by blowing nitrogen gas. A urethane resin composition was obtained by reacting these for 2 hours while stirring uniformly at 80°C. The number average molecular weight and viscosity of the obtained urethane resin composition were measured in the same manner as in Example 1. Using the obtained urethane resin composition, test pieces were prepared and adhesive physical properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
In a 2 L four-neck separable flask equipped with a stirrer, thermometer, heating device, and reflux tube, 150.0 g of hydroxyl-terminated hydrogenated polyisoprene, 17.6 g of MDI, 0.105 g of dioctyltin dilaurate, After charging 1509 g of cyclohexanone at room temperature, the inside of the flask was replaced with nitrogen by blowing nitrogen gas. A urethane resin composition was obtained by reacting these for 2 hours while stirring uniformly at 80°C. The number average molecular weight and viscosity of the obtained urethane resin composition were measured in the same manner as in Example 1. Using the obtained urethane resin composition, test pieces were prepared and adhesive physical properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 4)
In a 2 L four-neck separable flask equipped with a stirrer, thermometer, heating device, and reflux tube, 150.0 g of hydroxyl-terminated hydrogenated polyisoprene, 11.2 g of caprylic acid monoglyceride, 29.8 g of MDI, and dilaurin were added. After charging 0.105 g of dioctyltin acid and 1720 g of cyclohexanone at room temperature, the inside of the flask was purged with nitrogen by blowing nitrogen gas. A urethane resin composition was obtained by reacting these for 2 hours while stirring uniformly at 80°C. The number average molecular weight and viscosity of the obtained urethane resin composition were measured in the same manner as in Example 1. Using the obtained urethane resin composition, test pieces were prepared and adhesive physical properties were evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative example 1)
In preparing the test pieces shown in Example 1, evaluation was performed in the same manner as in Example 1, except that the urethane resin composition of the present invention was not used. The results are shown in Table 1.

・Hydroxyl group-terminated polyisoprene: trade name EPOL, manufactured by Idemitsu Kosan, number average molecular weight 2,500, hydroxyl group content 0.9 mol/kg)
・Caprylic acid monoglyceride: Trade name Rikemar M-100, manufactured by Riken Vitamin Co., Ltd. ・Dioctyltin dilaurate: manufactured by Kishida Chemical Co., Ltd. ・Cyclohexanone: manufactured by Gordo Co., Ltd.

As is clear from Table 1, according to the urethane resin composition of the present invention, it is possible to obtain a urethane resin composition that can provide sufficient adhesion to plastic substrates, including polypropylene substrates that exhibit high wettability. Can be done.

Claims (11)

A urethane resin composition for adhering a polypropylene base material,
General formula (1) below:
[In general formula (1), R is a hydrocarbon group having 40 to 500 carbon atoms (here, the hydrocarbon group may have a straight chain, branched chain, or cyclic structure, and may be a saturated hydrocarbon or an unsaturated hydrocarbon group) hydrogen). ]
It is a reaction product of a compound (A) represented by and a polyisocyanate compound (B),
The compound (A) has a hydrogenated polyisoprene skeleton,
A urethane resin composition characterized in that the content of the compound (A) is 80% to 99.9% by mass. The urethane resin composition according to claim 1, having a number average molecular weight of 3,000 to 250,000. The urethane resin composition according to claim 1 or 2, having a number average molecular weight of 5,926 to 250,000. Claims 1 to 3 , wherein the polyisocyanate compound (B) is one or more selected from the group consisting of diphenylmethane-4,4'-diisocyanate and diphenylmethane-2,4'-diisocyanate. Any of the urethane resin compositions. The urethane resin according to any one of claims 1 to 4, wherein the compound (A) represented by the general formula (1) has hydroxyl groups on different carbon atoms in the molecule and is a polyol polyolefin having 50 to 400 carbon atoms. Composition. An adhesive composition comprising the urethane resin composition according to any one of claims 1 to 5 . An adhesive layer obtained from the adhesive composition according to claim 6 . An article having an adhesive layer according to claim 7 . Obtained by heating the adhesive layer and the base material,
9. The article of claim 8, wherein the substrate is polypropylene . The method for producing an article according to claim 8 or 9 , characterized in that the article is obtained by heat treatment. 11. The method for manufacturing an article according to claim 10, wherein the article is heat-treated at 70° C. or higher.