JPH10273638A - Adhesive resin composition for polyolefin sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive resin composition excellent in adhesion of polyolefin-based resin sheet. SOLUTION: This adhesive resin composition is obtained by adding 0.5-20 wt.% organic diisocyanate compound to an acid-modified chlorinated polyolefin resin having 15-25 wt.% chlorine content, 1-10 wt.% grafted amount of α,β-unsaturated carboxylic acid or an anhydride thereof, and 40,000-100,000 weight average molecular weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive used in the production of a printed and embossed decorative sheet, and more particularly to an excellent adhesive when a printed polyolefin resin sheet is thermocompressed. The present invention relates to a resin composition for adhesives having strength.

[0002]

2. Description of the Related Art A decorative sheet conventionally used as a decorative sheet by bonding it to the surface of a wooden board, an inorganic board, a metal plate, or the like with an adhesive has excellent flexibility, embossability, stain resistance, and the like. Vinyl chloride resin sheets are often used.

[0003] However, since vinyl chloride resin causes corrosion of an incinerator and acid rain due to hydrogen chloride gas at the time of incineration, a decorative sheet using no vinyl chloride resin sheet has recently been required.

As a resin to replace the vinyl chloride resin, thermoplastic polyolefin resins such as polypropylene and polyethylene have been studied (JP-A-8-230113, JP-A-8-90740, JP-A-8-1881).
Gazette, JP-A-6-155692, JP-A-6-1556-1
98831). Adhesives used for them include urethane-based, polyester-based, water-based acrylic emulsion-based adhesives for polyolefins, but the use of these adhesives does not provide sufficient adhesive strength. It is a fact.

The present inventors have previously proposed an adhesive for polyolefin sheets (JP-A-6-306227). The chlorinated polyolefin used in the present invention has a softening temperature and an average molecular weight. Since it was not optimized, there was a drawback that sufficient adhesive strength could not be obtained when used as an adhesive for an olefin sheet.

The inventors of the present invention disclosed in Japanese Patent Application No. 9-64227 a softening point, an average molecular weight, and the like of a chlorinated polyolefin resin for a thermoplastic polyolefin resin such as polypropylene and polyethylene, which are difficult to adhere. By optimizing the chlorine content, a resin composition for an adhesive having excellent adhesion to the polyolefin resin was proposed. However, even in this resin composition, the adhesive strength was sometimes insufficient depending on the type of the polyolefin resin.

Examples of resin compositions for coatings include a mixture of a chlorinated polyolefin and a hydroxyl group-containing vinyl copolymer and a polyisocyanate compound, or a mixture of a chlorinated polyolefin obtained by copolymerizing a hydroxyl group-containing vinyl monomer and the like with a polyisocyanate compound. (JP-A-59-96136, JP-A-5-59327, JP-A-5-59327).
-194910).

In these compositions, a polyisocyanate compound is used to crosslink a hydroxyl group-containing vinyl monomer or a chlorinated polyolefin obtained by copolymerizing a hydroxyl group-containing vinyl monomer. However, since these compositions have a short pot life due to a mixture of a hydroxyl group and an isocyanate group, there remain problems such as long-term stability and limited use.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an adhesive resin composition having excellent adhesion to thermoplastic polyolefin resins such as polypropylene and polyethylene which are difficult to adhere.

[0010]

The present inventors have found that the chlorine content is 15 to 25% by weight, the amount of α, β-unsaturated carboxylic acid or its anhydride grafted is 1 to 10% by weight, and An adhesive resin composition comprising a resin obtained by reacting an organic diisocyanate compound with a chlorinated polyolefin resin having an average molecular weight of 40,000 to 100,000 in an amount of 0.5 to 20% by weight exhibits good adhesive strength in a polyolefin sheet. We have found and solved the above problem.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The acid-modified chlorinated polyolefin in the present invention is a component that adheres to a polyolefin resin.

As the raw material of the acid-modified chlorinated polyolefin, crystalline polypropylene, amorphous polypropylene, propylene-α-olefin copolymer, or the like can be used alone or as a mixture of two or more.

The α-olefin component used in the propylene-α-olefin copolymer is, for example, ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene,
At least one α-olefin having 2 or 4 to 6 carbon atoms selected from -methyl-1-pentene and 1-hexene is preferable, and the ratio of the propylene component to the α-olefin component in the copolymer is particularly limited. However, it is desirable that the propylene component be at least 50 mol%.

The adhesive resin composition of the present invention can be obtained by reacting an organic diisocyanate compound with a resin obtained by introducing an α, β-unsaturated carboxylic acid or its anhydride and chlorine into the above-mentioned polyolefin resin. It can be manufactured by the following two methods. That is,
A method in which an α, β-unsaturated carboxylic acid or an anhydride thereof is graft-polymerized to a polyolefin resin in advance, followed by a chlorination reaction and further reaction with an organic diisocyanate compound; This is a method in which a carboxylic acid or an anhydride thereof is graft-polymerized and further reacted with an organic diisocyanate compound.

As an example of a specific production method, in the first method, first, an α, β-unsaturated carboxylic acid or an anhydride thereof is graft-copolymerized with a polyolefin resin in the presence of a radical generator. Known methods such as a method in which a resin is heated and melted to a melting point or more to cause a reaction (melting method), a method in which the above resin is dissolved in an organic solvent, and then heated and stirred in the presence of a radical generator to react (solution method) It can be done by a method.

In the case of the melting method, a Banbury mixer,
Since the reaction is carried out in a short time at a temperature of not less than the melting point and not more than 300 ° C. by using a kneader, an extruder or the like, there is an advantage that the operation is simple.

On the other hand, in the solution method, it is desirable to use an aromatic solvent such as toluene or xylene as an organic solvent. No problem. The radical generator used in the reaction can be appropriately selected from known ones, and an organic peroxide compound is particularly desirable.

Examples of the above-mentioned organic peroxide compounds include di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide, benzoyl peroxide, dilauryl peroxide, cumene hydroperoxide and t-butyl peroxide. -Butyl hydroperoxide,
1,1-bis (t-butylperoxy) -3,5,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) -cyclohexane, cyclohexanone peroxide, t-butylperoxybenzoate, t- Butyl peroxyisobutyrate, t-butyl peroxy-3,
5,5-trimethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisopropyl carbonate, cumylperoxyoctoate, and the like.

However, in the case of the solution method, when the chlorination reaction is carried out after graft copolymerizing an α, β-unsaturated carboxylic acid or its anhydride, the above solvent must be replaced with a chlorinated solvent such as chloroform. Therefore, the melting method is more preferable in the first method.

In the subsequent chlorination reaction, a polyolefin resin obtained by graft copolymerizing an α, β-unsaturated carboxylic acid or its anhydride is dissolved in a chlorine-based solvent such as chloroform, and then irradiated with ultraviolet rays or This is performed by blowing gaseous chlorine in the presence of the organic peroxide.

The subsequent reaction with an organic diisocyanate compound is carried out by substituting the above chlorinated polyolefin with an organic solvent such as toluene, appropriately diluting and heating, and then gradually adding the organic diisocyanate compound and stirring for several hours. . The reaction can be carried out at a temperature of not lower than 50 ° C. and not higher than the boiling point of the solvent.

In the second method, in which a chlorination reaction is carried out, an α, β-unsaturated carboxylic acid or an anhydride thereof is graft-polymerized, and further an organic diisocyanate compound is reacted. Dissolved in a chlorinated solvent of the formula (1), and a chlorinated reaction is performed in the same manner as in the first method to produce a chlorinated polyolefin resin.
The β-unsaturated carboxylic acid or its anhydride is graft-copolymerized in the presence of the above-mentioned organic peroxide, and an organic diisocyanate compound is gradually added to carry out the reaction for several hours. The reaction can be carried out at a temperature of not lower than 50 ° C. and not higher than the boiling point of the solvent.

In the first method and the second method, crystalline polypropylene, amorphous polypropylene, propylene
α, β graft copolymerized to α-olefin copolymer
-Unsaturated carboxylic acids or anhydrides thereof are for imparting adhesion to the printing ink of the decorative sheet, for example, maleic acid, citraconic acid, itaconic acid, aconitic acid and their anhydrides, acrylic acid And methacrylic acid, fumaric acid, mesaconic acid, etc., and maleic anhydride is most suitable in consideration of the graftability to a polyolefin resin.

In the present invention, the amount of the α, β-unsaturated carboxylic acid or anhydride introduced by graft copolymerization is optimally from 1 to 10% by weight. When the amount is less than 1% by weight, sufficient adhesion to the printing ink (for example, urethane-based printing ink) of the base sheet cannot be obtained. When the amount is 10% by weight or more, the moisture resistance tends to decrease when used as an adhesive. It is in.

The chlorine content of the acid-modified chlorinated polyolefin resin is an important factor that determines the adhesion to the polyolefin resin. The lower the chlorine content, the better the adhesion to the polypropylene resin and the higher the chlorine content, the higher the chlorine content. Adhesion with polypropylene resin is reduced. On the other hand, if the chlorine content is low, the solubility in an organic solvent is reduced. If the chlorine content is too low, it does not dissolve in the solvent.

Normally, chlorinated polypropylene is used for bonding polypropylene, but most of them have been developed for paints and inks, and the chlorine content is generally 30% by weight in order to increase the solvent solubility. That's all.

In the present invention, the adhesion of a polyolefin resin sheet or film such as polypropylene by thermocompression bonding is taken into consideration, and the chlorine content is optimally 15 to 25% by weight. If the chlorine content is less than 15% by weight, there is a disadvantage that the solvent solubility is poor and the workability is reduced,
If it exceeds 25% by weight, there is a disadvantage that the adhesion to the film is reduced.

Further, the obtained acid-modified chlorinated polyolefin resin is subjected to gel permeation chromatography (G
The weight average molecular weight of the polystyrene resin measured by PC) is preferably 40,000 to 100,000. If it is less than 40,000, the cohesive strength of the resin is insufficient, and if it is more than 100,000, the viscosity is too high when applied to a polyolefin sheet, which is not preferable.

Further, when the obtained acid-modified chlorinated polyolefin resin having a softening point of 70 to 100 ° C. is subjected to thermocompression bonding,
It is preferable in that the wettability to the film is improved. The thermocompression bonding of the film is performed by lamination bonding using a hot-press roll or bonding using a hot press, and the temperature of the hot-press roll or the hot press is usually in the range of 80 to 150 ° C. Therefore, the acid-modified chlorinated polyolefin resin has a softening point of 15
If the temperature is 0 ° C. or lower, the film can be melted and the wettability to the film is considered to be improved.

However, since the time required for the film to come into contact with the hot-press roll or hot press in the process is several seconds, the hot-press process ends before the resin is completely melted with a resin having a softening point near 150 ° C. . Therefore, in order to melt the resin in a short time, the range of the softening point of the acid-modified chlorinated polyolefin resin is preferably from 70 to 100C.
If the softening point is lower than 70 ° C., the wettability to the film is good, but there is a drawback that the cohesiveness as an adhesive is reduced, and if it exceeds 100 ° C., the wettability to the film is deteriorated.

The adhesion to the polyolefin sheet was improved by optimizing the softening point, average molecular weight and chlorine content of the chlorinated polyolefin resin. To further improve the adhesion, a reaction product with an organic diisocyanate compound was used. Was devised.

It is known that a polar group such as a hydroxyl group is formed on the surface of an extruded polyolefin sheet or a corona-treated polyolefin sheet.

In the present invention, by reacting an acid-modified chlorinated polyolefin with an organic diisocyanate compound,
It is considered that the bonding strength can be increased by chemically bonding the hydroxyl group of the polyolefin sheet and the acid-modified chlorinated polyolefin via an isocyanate compound during thermocompression bonding.

Examples of the organic diisocyanate compound to be reacted with the acid-modified chlorinated polyolefin include isophorone diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate and its hydrogenated product, 4,4'-diphenylmethane diisocyanate and its hydrogenated product, xylylene diisocyanate and A hydrogenated product thereof, and an adduct, a burette, an isocyanurate, and the like of these organic diisocyanates can be used, and the proportion thereof is optimally 0.5 to 20% by weight based on the chlorinated polyolefin resin. Outside this range, sufficient adhesion to the polyolefin resin cannot be obtained.

The adhesive resin composition of the present invention is preferably a solution in consideration of workability. Solution concentration is 10
A concentration of 30% is preferred. As the solvent, aromatic solvents such as toluene and xylene, and alicyclic solvents such as cyclohexane, methylcyclohexane and ethylcyclohexane can be mainly used, but esters such as ethyl acetate, butyl acetate, methyl ethyl ketone and methyl isobutyl ketone, and ketones can be used. Solvents can also be used. Further, an alcohol solvent such as isopropyl alcohol can also be used.

The adhesive resin composition according to the present invention may be used as it is, or may be used by adding an antioxidant, an ultraviolet absorber, a light stabilizer, an antiblocking agent and other additives.

The adhesive resin composition of the present invention is a polyolefin-based transparent resin sheet which is bonded to a printed polyolefin-based resin sheet to protect the printed surface of the substrate sheet or to enhance the design by embossing. Used as an adhesive with.

Examples of the polyolefin base sheet and the polyolefin transparent resin sheet include a random polymer such as a polypropylene homopolymer and a propylene-α-olefin copolymer, a block polymer or a polypropylene homopolymer. A resin in which low-density polyethylene and ethylene-propylene copolymer rubber are mixed can be used.

In order to increase the adhesion of the printing ink to the substrate sheet and the adhesiveness of the transparent sheet, the adhesive surface may be subjected to a corona treatment.

The effect of the adhesive resin composition of the present invention does not change even if it is applied to either the printed surface of the printed base sheet or the adhesive surface of the transparent resin sheet.

The method of laminating a transparent film on a substrate sheet is performed by a dry lamination method in which a polyolefin film such as polypropylene formed in advance into a film is laminated, and an extrusion lamination method in which a thermoplastic resin is melt-extruded. It can be carried out by a commonly used method such as a method.

The method of thermocompression bonding of a film can be carried out by a commonly used method such as lamination bonding using a hot-press roll or bonding using a hot press.

[0043]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

Example 1 In a four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 500 g of isotactic polypropylene was heated and dissolved at 200 ° C. After performing nitrogen replacement in the flask for 10 minutes,
While stirring, 25 g of maleic anhydride was added over about 5 minutes, and 2 g of di-t-butyl peroxide as a radical generator was added dropwise over about 30 minutes. After the reaction was further continued for 30 minutes, unreacted maleic anhydride was removed while reducing the pressure in the flask with an aspirator. The maleic anhydride graft amount of this product was 4.4% by weight.
Next, this product was put into a glass-lined reaction vessel, 5 L of chloroform was added, and the mixture was placed under a pressure of ² kg / cm ² .
While irradiating ultraviolet rays, gaseous chlorine was blown from the bottom of the reactor until the chlorine content became 22.2% by weight. After completion of the reaction, chloroform as a solvent was distilled off with an evaporator, and a 20% solution of a chlorinated polyolefin modified with maleic anhydride by substitution with toluene / cyclohexane = 70/30 (weight ratio) was obtained. The weight average molecular weight of this resin was 56,000. The softening point was 86 ° C.

450 g of this resin solution (20% solution) was added to 8
Heat to 5 ° C and add 10 g of isophorone diisocyanate to 3
It was added over 0 minutes, and the reaction was further performed for 3 hours while maintaining the reaction temperature at 85 ° C. After the reaction, the resin concentration was adjusted to 20% with toluene.

Example 2 20 g of maleic anhydride was graft-copolymerized to 500 g of isotactic polypropylene in the same manner as in Example 1. The grafted amount of maleic anhydride in this product was 3.5% by weight. Further, a 20% solution of a chlorinated polyolefin chlorinated to a chlorine content of 20.6% by weight and modified with maleic anhydride by the same operation as in Example 1 (solvent composition: toluene / cyclohexane =
50/50 (weight ratio)). The weight average molecular weight of this resin was 94,000. The softening point was 90 ° C.

475 g of this resin solution (20% solution) was added to 8
Heat to 5 ° C and add 5 g of isophorone diisocyanate to 30
The reaction was continued for 3 hours while maintaining the reaction temperature at 85 ° C. After the reaction, the resin concentration was adjusted to 20% with toluene.

Example 3 Ethylene content 6.1 mol%
33 g of maleic anhydride was graft-copolymerized to 500 g of the ethylene-propylene copolymer as in Example 1. The grafted amount of maleic anhydride of this product was 5.5% by weight. Further, a 20% solution of a chlorinated polyolefin modified with maleic anhydride and chlorinated to a chlorine content of 18.2% by weight in the same manner as in Example 1 (solvent composition: toluene / cyclohexane = 75/25 (weight ratio)) I got The weight average molecular weight of this resin is 60,000
Met. The softening point was 72 ° C.

450 g of this resin solution (20% solution) was added to 8
Heat to 5 ° C and add 10 g of hexamethylene diisocyanate
Was added over 30 minutes, and the reaction was further carried out for 3 hours while maintaining the reaction temperature at 85 ° C. After the reaction, the resin concentration was adjusted to 20% with toluene.

Example 4 Ethylene content 3.2 mol%
500 g of ethylene-propylene copolymer is charged into a glass-lined reaction vessel, 5 L of chloroform is added, and the mixture is irradiated with ultraviolet light under a pressure of ² kg / cm ² until the chlorine content becomes 18.6% by weight. Gaseous chlorine was blown from the bottom of the reactor. After completion of the reaction, chloroform as a solvent was distilled off with an evaporator, and replaced with toluene.
% Solution was obtained. Next, this product was charged into a four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, heated to 85 ° C., and purged with nitrogen in the flask for 10 minutes. 5 g of benzoyl peroxide was added as a radical generator, and 30 g of maleic anhydride was added to about 5
Then, the reaction was continued for 3 hours while stirring. This product had a grafted amount of maleic anhydride of 5.2.
% By weight. After completion of the reaction, the reaction mixture was diluted with toluene and cyclohexane to give a solvent composition of toluene / cyclohexane = 50.
A 20% solution of a chlorinated polyolefin modified with maleic anhydride at a weight ratio of / 50 was obtained. The weight average molecular weight of this resin was 64000. The softening point was 84 ° C.

425 g of this resin solution (20% solution) was added to 8
Heat to 5 ° C and add 15 g of isophorone diisocyanate to 3
It was added over 0 minutes, and the reaction was further performed for 3 hours while maintaining the reaction temperature at 85 ° C. After the reaction, the resin concentration was adjusted to 20% with toluene.

Example 5 500 g of isotactic polypropylene was chlorinated to a chlorine content of 24.6% by weight in the same manner as in Example 4. Then, 30 g of maleic anhydride was graft-copolymerized in the same manner as in Example 4, and a 20% solution of a chlorinated polyolefin modified with maleic anhydride (solvent composition: toluene / cyclohexane = 50/50).
(Weight ratio)). This product had a grafted amount of maleic anhydride of 5.0% by weight and a weight average molecular weight of 80%.
000. The softening point was 71 ° C.

450 g of this resin solution (20% solution) was added to 8
Heat to 5 ° C and add 10 g of isophorone diisocyanate to 3
It was added over 0 minutes, and the reaction was further performed for 3 hours while maintaining the reaction temperature at 85 ° C. After the reaction, the resin concentration was adjusted to 20% with toluene.

Comparative Example 1 In a four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 500 g of isotactic polypropylene was heated and dissolved at 200 ° C. After performing nitrogen replacement in the flask for 10 minutes,
While stirring, 30 g of maleic anhydride was added over about 5 minutes, and 2 g of di-t-butyl peroxide as a radical generator was added dropwise over about 30 minutes. After the reaction was further continued for 30 minutes, unreacted maleic anhydride was removed while reducing the pressure in the flask with an aspirator. The grafted amount of maleic anhydride of this product was 5.2% by weight.
Next, this product was put into a glass-lined reaction vessel, 5 L of chloroform was added, and the mixture was placed under a pressure of ² kg / cm ² .
While irradiating ultraviolet rays, gaseous chlorine was blown from the bottom of the reactor until the chlorine content reached 18.6% by weight. After completion of the reaction, chloroform as a solvent was distilled off using an evaporator, and a 20% solution of a chlorinated polyolefin modified with maleic anhydride by substituting with toluene / cyclohexane = 50/50 (weight ratio) was obtained. The weight average molecular weight of this resin was 66,000. The softening point was 81 ° C.

Comparative Example 2 Ethylene content of 3.2 mol%
30 g of maleic anhydride was graft-copolymerized to 500 g of the ethylene-propylene copolymer as in Example 1. The grafted amount of maleic anhydride of this product was 5.2% by weight. Further, a 20% solution of chlorinated polyolefin chlorinated to a chlorine content of 18.2% by weight and modified with maleic anhydride by the same operation as in Example 1 (solvent composition: toluene / cyclohexane = 50/50 (weight ratio)) I got The weight average molecular weight of this resin is 56,000
Met. The softening point was 78 ° C.

350 g of this resin solution (20% solution) was
Heat to 5 ° C and add 30 g of isophorone diisocyanate to 3
It was added over 0 minutes, and the reaction was further performed for 3 hours while maintaining the reaction temperature at 85 ° C. After the reaction, the resin concentration was adjusted to 20% with toluene.

The resin solutions obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were coated on a polypropylene base sheet printed in a woodgrain with a two-part urethane ink to a thickness of 5 to 6 μm. Let dry. A transparent sheet made of corona-treated polypropylene is superimposed on the base sheet thus obtained, and a heat seal tester (Yasuda Seiki Seisakusho) is used at 130 ° C., 2 kg / cm ² for 10 seconds. Thermocompression bonding.

The adhesive strength between the substrate sheet coated with the adhesive and the transparent sheet was measured by a T-peel test using a universal tensile tester (Toyo Sokki Co., Ltd.). The peeling speed was set at 50 mm / min. Table 1 shows the test results.

[0059]

[Table 1]

[0060]

From the above test results, it can be seen that those obtained by reacting an organic diisocyanate compound with a chlorinated polyolefin obtained by graft copolymerizing an α, β-unsaturated carboxylic acid or its anhydride have a high peel strength. Further, it can be seen that even if the reaction amount of the organic diisocyanate compound is too large, the peel strength is lowered and an optimum amount is present.

Claims (4)

[Claims] (1) a chlorine content of 15 to 25% by weight;
The amount of the unsaturated carboxylic acid or its anhydride grafted is 1
-10% by weight and a weight average molecular weight of 40,000-1
An adhesive resin composition for a polyolefin sheet obtained by reacting 0.5 to 20% by weight of an organic diisocyanate compound with an acid-modified chlorinated polyolefin resin of 00000. 2. The adhesive resin composition for a polyolefin sheet according to claim 1, wherein the acid-modified chlorinated polyolefin resin has a softening point of 70 to 100 ° C. 3. The method according to claim 1, wherein the acid-modified chlorinated polyolefin resin is polypropylene, or propylene and C2 or C4.
The adhesive resin composition for a polyolefin-based sheet according to claim 1 or 2, wherein a resin obtained by copolymerizing α-olefins of (a) to (c) is used as a raw material. 4. The method according to claim 1, wherein the chlorine content is 15 to 25% by weight, α, β
The amount of the unsaturated carboxylic acid or its anhydride grafted is 1
-10% by weight and a weight average molecular weight of 40,000-1
A method for producing an adhesive resin composition for a polyolefin-based sheet, comprising reacting an organic diisocyanate compound with an acid-modified chlorinated polyolefin resin of 00000 in an amount of 0.5 to 20% by weight.