JP3073916B2 - Coating composition for plasticized vinyl chloride resin and molded article of plasticized vinyl chloride resin coated with the composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition for a plasticized vinyl chloride resin and a plasticized vinyl chloride resin molded article whose surface is coated with the composition. More specifically, it prevents bleed-out (surface migration) of a plasticizer in a molded product, prevents contamination of the molded product surface, and has excellent weather resistance, flexibility, water resistance, solvent resistance, adhesiveness, and the like. The present invention relates to a composition for coating a plasticized vinyl chloride resin molded article and a plasticized vinyl chloride resin molded article coated with the composition.

[0002] Conventionally, vinyl chloride resins are inexpensive, have excellent chemical stability, and can be used over a wide range from hard to soft by changing the amount of plasticizer. It is widely used in many applications as interior materials, agricultural products such as seats, tents, and canvas sheets, desk mats, and molded products such as hoses and tubes. However, plasticized vinyl chloride resin contains a large amount of plasticizer, and the plasticizer bleeds out on its surface over time,
There are drawbacks such as adhesion of dirt and blocking.

Various methods for preventing bleed-out of a plasticizer in a plasticized vinyl chloride resin have been conventionally studied. For example, in Japanese Patent Publication No. 47-28740, a resin coating layer is provided on the surface of a plasticized vinyl chloride resin molded product,
A method has been proposed for suppressing the transfer of the plasticizer to the surface. As such a coating layer-forming resin, homopolymers and copolymers of acrylic acid esters and methacrylic acid esters are known, but these polymer films do not sufficiently prevent the migration of the plasticizer. However, the above-mentioned properties such as stain resistance, blocking resistance and bending resistance cannot be satisfied.

[0004] Also, Japanese Patent Application Laid-Open No. 2-29838 discloses that
As a coating material formed on the surface of the plasticized vinyl chloride resin sheet, it is mainly composed of a fluorinated copolymer or an acrylic copolymer having a cross-linking site, and has excellent adhesion with the plasticized vinyl chloride resin. A sheet is disclosed. However, this sheet does not sufficiently prevent bleed out of the plasticizer.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a coating composition for preventing bleed-out of a plasticizer in a plasticized vinyl chloride resin molded product and preventing contamination of the surface of the resin molded product. An object of the present invention is to provide a plasticized vinyl chloride resin molded article coated with the composition.

[0006]

The above object is achieved by the present invention described below. That is, the present invention provides a coating composition for a plasticized vinyl chloride resin, which comprises a polyvinyl alcohol-based copolymer obtained by grafting an aliphatic polyester to polyvinyl alcohol as a film-forming component, and a surface of the coating composition for the plasticized vinyl chloride-based resin. It is a coated plasticized vinyl chloride resin molded product.

The present inventors have focused on polyvinyl alcohol which is excellent in solvent resistance, coating strength and abrasion resistance, and gas barrier properties for preventing the plasticizer from blooming out. Polyvinyl alcohol is a preferred material in terms of preventing bleed-out of plasticizers, but has poor flexibility, causing cracking and whitening when flexing, and its water solubility makes it resistant to blocking under high humidity. And poor in stain resistance and the like, and were not satisfactory.

[0008] By the way, in order to plasticize a vinyl chloride resin, an ester plasticizer or a polyester resin has been conventionally used, and these ester bonds are formed by the plasticization of the vinyl chloride resin and the vinyl chloride resin. It is clear that this contributes to the compatibility with Therefore, the present inventors have conducted intensive studies to solve the problems based on the plasticizer, and as a result, those obtained by grafting polyester to polyvinyl alcohol prevent bleed out of the plasticizer in the plasticized vinyl chloride resin. In addition, they have found that they have excellent flexibility, water resistance, solvent resistance, and weather resistance, and also have excellent adhesion to a plasticized vinyl chloride resin, and have completed the present invention.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to embodiments of the present invention. The polyvinyl alcohol copolymer obtained by grafting an aliphatic polyester to polyvinyl alcohol, which is used as a film forming component in the present invention, can be obtained by subjecting lactone to ring-opening polymerization in the presence of polyvinyl alcohol. As polyvinyl alcohol, the degree of saponification of vinyl acetate unit is 60 mol%
The above are preferred. The preferred degree of polymerization of polyvinyl alcohol is from 20 to 20,000, more preferably from 200 to 3,000.

The lactone is not particularly limited as long as it is a lactone which forms an aliphatic polyester by ring-opening polymerization. Particularly preferred are ε-caprolactones and δ-lactones.
-Valerolactones. Examples of ε-caprolactones include, for example, ε-caprolactone, monomethyl-ε-
Monoalkyl-ε-caprolactone such as caprolactone, monoethyl-ε-caprolactone, monodecyl-ε-caprolactone, monopropyl-ε-caprolactone, and monodecyl-ε-caprolactone; two alkyl groups each being substituted with a carbon atom other than the ε-position Dialkyl-ε-caprolactone; trialkyl-ε in which three alkyl groups are respectively substituted on carbon atoms other than the ε-position
-Caprolactone; alkoxy-ε-caprolactone such as ethoxy-ε-caprolactone; cyclohexyl-ε
Cycloalkyl-lactone such as caprolactone; aralkyl-ε-caprolactone such as benzyl-ε-caprolactone; and aryl-ε-caprolactone such as phenyl-ε-caprolactone.

As δ-valerolactones, for example,
5-valerolactone, 3-methyl-5-valerolactone, 3,3-dimethyl-5-valerolactone, 2-methyl-5-valerolactone, 3-ethyl-5-valerolactone, and the like. One or two of these lactones
Used in more than species.

The graft reaction of an aliphatic polyester onto polyvinyl alcohol can also be obtained by ring-opening polymerization of the above lactone in an emulsified dispersion of polyvinyl alcohol or in a solution of a suitable solvent. Since thermal decomposition is involved, a method of reacting a mixture of powdery polyvinyl alcohol and liquid lactone in a nitrogen stream using a known ring-opening polymerization catalyst such as tetrabutyl titanate is preferred. The reaction can be carried out under stirring in a usual reaction vessel or under melting in a mixer such as a single-screw and twin-screw extruder, a Banbury mixer, a kneader, a Brabender and the like. The reaction is carried out at 80-220 ° C for several hours. In a normal reaction in a reaction vessel, white powder polyvinyl alcohol and liquid lactone are in a heterogeneous mixed state in the initial stage of the reaction, but as the reaction proceeds, the two become a uniform mixed state, and a uniform reaction product is formed. can get. In this method, despite the reaction at a high temperature, no thermal decomposition of polyvinyl alcohol is observed.

By varying the amount and molecular weight of the aliphatic polyester to be grafted onto the polyvinyl alcohol, various graft copolymers having both the characteristics of the polyvinyl alcohol and the aliphatic polyester can be obtained. The ratio of the preferred both polymers in the polyvinyl alcohol-based copolymer in which the aliphatic polyester is grafted on the polyvinyl alcohol is such that the polyvinyl alcohol is 50 to 50%.
90% by weight, 50 to 10% by weight of aliphatic polyester. In this copolymer, the solvent resistance, high strength, abrasion resistance and gas barrier properties (performance of preventing bleed-out of a plasticizer) possessed by polyvinyl alcohol and the flexibility, flex resistance and water resistance possessed by aliphatic polyester And performance such as adhesion.

However, the proportion of polyvinyl alcohol exceeds 90% by weight and the proportion of aliphatic polyester is 1%.
In a polyvinyl alcohol-based copolymer of less than 0% by weight,
Although the bleed-out preventing performance of the plasticizer is excellent, the adhesiveness to the plasticized vinyl chloride resin molded product, flexibility, bending resistance and water resistance become insufficient. In the case of a polyvinyl alcohol-based copolymer in which the proportion of polyvinyl alcohol is less than 50% by weight and the proportion of aliphatic polyester exceeds 50% by weight, adhesion to plasticized vinyl chloride-based resin molded products, flexibility, and bending resistance Although excellent in water resistance and water resistance, the bleed-out prevention performance, solvent resistance and film strength of the plasticizer are insufficient. A more preferable ratio is that the polyvinyl alcohol is 60%.
80% by weight, 40-20% by weight of aliphatic polyester
It is.

The coating composition for a plasticized vinyl chloride resin of the present invention contains the above-mentioned polyvinyl alcohol-based copolymer as a film-forming component, and the copolymer is used as it is (without crosslinking). ) But also flexibility, water resistance,
Solvent resistance, it is possible to form a coating excellent in plasticizer bleed-out prevention performance and strength properties, etc., by cross-linking with various cross-linking agents utilizing the hydroxyl groups remaining in the copolymer at the time of coating formation. Thus, it is possible to form a film having the above-mentioned characteristics further improved. As the crosslinking agent, any one that reacts with a hydroxyl group can be used, but a phenol resin, a melamine resin, an epoxy resin, a polyisocyanate, or the like is preferable.

The coating composition for the plasticized vinyl chloride resin of the present invention may contain various additives as required in addition to the polyvinyl alcohol copolymer which is an essential component. Examples of additives include coloring pigments, extenders, ultraviolet absorbers, ultraviolet stabilizers, colloidal silica, dispersants, fungicides, matting agents, and the like.The form of the coating composition of the present invention is particularly limited. But not, for example,
It may be a solution or a solid.

When the coating composition is a solution, the coating composition is used as a solution of a solvent that dissolves the polyvinyl alcohol copolymer. Examples of the solvent include glycols such as ethylene glycol, glycerin, and diethylene glycol; and mixtures of water with lower alcohols such as dimethyl sulfoxide (DMSO), N, N-dimethylformamide (DMF) and isopropanol, and the like. Practically, a mixture of lower alcohol and water is preferable. The concentration of the solution is not particularly limited, and is, for example, about 10 to 50% by weight.

As a method for forming a film on the surface of a plasticized vinyl chloride resin molded article using the coating composition of the present invention, when the coating composition is a solution, a gravure coater,
Examples thereof include a method of applying with a knife coater, a reverse coater, a bar coater, dipping, brush coating, air spray, airless spray, or the like.

When the coating composition is a solid, there is a method in which the coating composition of the present invention is directly melt-molded into a film or sheet, and this is laminated on a plasticized vinyl chloride resin molded article. Lamination may be performed by direct thermal lamination or via various adhesives. Examples of the plasticized vinyl chloride resin molded article coated with the coating composition of the present invention include, for example, wallpaper,
Floor materials, ceiling materials, leather, films, hoses, tubes and the like can be mentioned.

[0020]

Next, the present invention will be described specifically with reference to examples and comparative examples. The parts and percentages in the text are based on weight unless otherwise specified. Production Examples 1-3 Powder of polyvinyl alcohol (degree of polymerization 550) having a saponification degree of 98.5 mol% and ε-caprolactone were charged into a reaction vessel equipped with a stirrer together with a tetrabutyl titanate catalyst in a quantitative ratio shown in Table 1 below. And 1 ° C./2 to 3 min. The temperature was raised at the following rate. 1
When the temperature reached 50 to 160 ° C., the conventional heterogeneous system gradually became homogeneous, and at 180 to 200 ° C., it became completely homogeneous. The reaction was performed at 200 to 220 ° C. for 6 hours to obtain a polyvinyl alcohol-based copolymer to which an aliphatic polyester was grafted.

Each of the obtained copolymers was evaluated by the following test methods. Table 1 shows the results. (1) Number average molecular weight Measured by GPC as a 5% solution of DMF. The number average molecular weight is a number average molecular weight in terms of standard polystyrene. (2) Hardness A sheet obtained by press-molding each copolymer at 160 ° C. was used and measured with an A-type hardness meter according to JIS K-6301. (3) Strength properties A dumbbell test piece No. 3 was prepared from the above press-formed sheet, and measured according to JIS K-7311. (4) Vicat softening point Measured according to JIS K-7206.

[0022]

[Table 1]

Example 1 Each of the copolymers obtained in Production Examples 1 to 3 was dissolved in a mixed solvent of isopropyl alcohol / water (3/7) to give a solid content of 20%.
% Of the coating composition of the present invention. The above solution was applied to both sides of a soft vinyl chloride resin sheet (thickness: 3 mm) with a bar coater so that the dry thickness was 10 to 20 μm.
It was dried at 0 ° C. for 30 seconds and tested by the following test method. Table 2 shows the results.

(1) Bleed-out amount of plasticizer The above-mentioned soft vinyl chloride resin sheet coated on both sides is 50 mm ×
It is cut to 50 mm, sandwiched between polyethylene sheets weighed in advance, and further sandwiched between glass plates. A load of 5 Kg is applied and left in a constant temperature bath at 70 ° C. for 24 hours. Thereafter, the polyethylene sheet is taken out of the thermostat, the weight of the polyethylene sheet is weighed, the increase in weight is determined, and the increase is defined as the amount of the bleeding plasticizer.

(2) Stain resistance The above double-sided soft vinyl chloride resin sheet is 50 mm ×
The sheet is cut to 50 mm, brought into close contact with a previously exposed copy sheet, and sandwiched between glass plates. Apply a load of 3 kg and
Leave for 24 hours and 72 hours in a thermostat at 0 ° C. After the standing, the sheet is peeled from the copy paper, and the degree of contamination of the sheet is visually observed. ○ indicates no contamination, △ indicates partial contamination, and × indicates total contamination.

(3) Adhesion The coating film is cut into 100 squares of 1 mm square with a knife and subjected to a peeling test with a cellophane tape. (4) Flexibility The above-mentioned soft vinyl chloride resin sheet coated on both sides is cured at room temperature for 20 minutes.
Bend and observe the state of the coating film visually.は indicates no change, △ indicates whitening, and × indicates cracking.

(5) Water resistance The above-mentioned double-coated soft vinyl chloride resin sheet is immersed in water for one day. The state of the coating film immediately after removal and after drying at room temperature is visually observed. ：: Slightly cloudy immediately after removal, but no blistering, etc., was observed after drying and the same as before immersion. Δ: Cloudy or blistering was recognized immediately after removal,
×: No change after drying, and ×: a case where cloudiness and blistering are remarkable immediately after taking out, and the state does not return to the state before immersion after drying.

(6) Solvent resistance 500 g of the above-mentioned double-coated soft vinyl chloride resin sheet with a cloth containing toluene and white gasoline, respectively.
And rubbing it 20 times, and visually observe the state of the coating film. ○ indicates the case where there is no change, △ indicates the case where there is a trace of rubbing, and × indicates the case where the coating film has fallen off along with the trace of rubbing.

Examples 4 to 6 Here are the test results when a soft vinyl chloride resin sheet is covered with a crosslinked film of a polyvinyl alcohol copolymer. A coating was formed on a soft vinyl chloride resin sheet in the same manner as in Examples 1 to 3, except that a self-emulsifying type polyisocyanate (manufactured by Nippon Polyurethane Co., Ltd.) was added to the coating composition used in Examples 1 to 3. The test was performed in the same manner as in Examples 1 to 3. Table 2 shows the results.

Comparative Example 1 In the case where the coating of the coating composition was not formed on the soft vinyl chloride resin sheet. Table 2 shows the test results.

Comparative Example 2 A case where a polyvinyl alcohol film having a saponification degree of 98.5 mol% was formed on a soft vinyl chloride resin sheet. Table 2 shows the test results.

Comparative Example 3 A soft vinyl chloride resin sheet was coated with an acrylic resin (Acrylic polyol LR-620 manufactured by Mitsubishi Rayon Co.) and a curing (crosslinking) agent (Coronate HX manufactured by Nippon Polyurethane).
Was applied to form a coating film in the same manner as in Examples 1 to 3. Table 2 shows the test results.

Comparative Example 4 A soft vinyl chloride resin sheet was coated with a coating composition comprising a fluororesin for coating vinyl chloride resin (Fluorotop manufactured by Asahi Glass Co., Ltd.) and a curing agent (Coronate HX manufactured by Nippon Polyurethane Co., Ltd.). A coating was formed in the same manner as in Examples 1 to 3. Table 2 shows the test results.

[0034]

[Table 2]

Examples 7 to 9 Each of the copolymers obtained in Production Examples was vacuum dried at 60 ° C. for 24 hours. The dried copolymers and the acid value inhibitor were mixed under heating using a Brabender to prepare a coating composition of the present invention. Each coating composition was molded at 210 ° C. using a film molding machine to obtain a film having a thickness of 20 μm. A soft vinyl chloride sheet and these films were laminated by a thermal lamination method. Tests were performed on these laminates in the same manner as in Examples 1 to 3, and results similar to those in Examples 1 to 3 were obtained.

[0035]

According to the present invention described above, bleed out of a plasticizer contained in a plasticized vinyl chloride resin is prevented,
Provided are a coating composition which prevents surface contamination of the resin molded article, and the resin molded article coated with the coating composition.

Continuation of front page (72) Katsumi Kuriyama, Inventor 1-7-6 Bakurocho, Nihonbashi, Chuo-ku, Tokyo Inside Dainippon Seika Kogyo Co., Ltd. (56) References JP-A-62-15265 (JP, A) JP-A-7- 109339 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 7/04 C08G 63/00-63/91 C08L 67/00-67/04 C09D 167/00-167/04 C09J 167/00-167/04

Claims (7)

(57) [Claims] 1. A coating composition for a plasticized vinyl chloride resin, comprising a polyvinyl alcohol copolymer obtained by grafting an aliphatic polyester to polyvinyl alcohol as a film forming component. 2. The coating composition for a plasticized vinyl chloride resin according to claim 1, wherein the polyvinyl alcohol copolymer comprises 90 to 50% by weight of polyvinyl alcohol and 10 to 50% by weight of an aliphatic polyester. 3. The polyvinyl alcohol having a degree of saponification of 60
The coating composition for a plasticized vinyl chloride resin according to claim 1, which is at least mol%. 4. The coating composition for a plasticized vinyl chloride resin according to claim 1, wherein the aliphatic polyester is a ring-opened polymer of ε-caprolactone and / or δ-valerolactone. 5. The coating for a plasticized vinyl chloride resin according to claim 1, wherein the polyvinyl alcohol-based copolymer is obtained by ring-opening polymerization of lactone in a mixture of polyvinyl alcohol powder and lactone. Composition. 6. A molded article of a plasticized vinyl chloride resin, the surface of which is coated with the coating of the coating composition for a plasticized vinyl chloride resin according to claim 1. 7. The plasticized vinyl chloride resin molded article according to claim 6, wherein the coating is crosslinked.