JP5232724B2 - Surface finishing method - Google Patents

Description

  The present invention relates to a surface finishing method for a polyvinyl chloride surface such as a polyvinyl chloride coated steel sheet and a polyvinyl chloride sheet.

  Conventionally, polyvinyl chloride has been used for various members such as buildings because of its excellent physical properties such as acid resistance, alkali resistance, water resistance, and petroleum resistance. As an example, a polyvinyl chloride coated steel sheet is formed by forming a polyvinyl chloride film on various steel sheets such as a hot rolled steel sheet, a cold rolled steel sheet, a hot dip galvanized steel sheet, a stainless steel sheet, and an aluminum sheet. Widely used as roofing materials, outer wall materials, etc. (for example, Patent Document 1).

JP-A-8-25557

  However, such a surface made of polyvinyl chloride (hereinafter referred to as “polyvinyl chloride surface”) may be discolored by the influence of ultraviolet rays or the like, or may be contaminated by dust in the atmosphere when exposed to sunlight or wind and rain. Therefore, there is a limit in maintaining the initial appearance for a long time. Therefore, the surface finish by repainting is required for the deteriorated polyvinyl chloride surface. Even if the deterioration has not progressed, if there is a request to change the design properties such as the color and shape, it is necessary to repaint.

  However, in a material having a polyvinyl chloride surface as described above, a plasticizer is generally included in its constituent components in order to impart flexibility, workability, and the like. Such a plasticizer has a problem that it shifts to a film formed by repainting, softens the film, and thus promotes adhesion of dust substances in the atmosphere. In addition, when the polyvinyl chloride surface is repainted, there is a problem that it is difficult to ensure adhesion even if a normal coating material is used.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a finishing method suitable for repainting a polyvinyl chloride surface.

  As a result of intensive studies to achieve the above object, the present inventor has conceived that a film is formed from a coating material containing a specific polyol, an isocyanate, and a specific solvent as essential components, thereby completing the present invention. It was.

That is, the present invention has the following characteristics.
1. For polyvinyl chloride surface
The coating film is formed by a coating material containing a polyol, a polyisocyanate, and a solvent as essential components, the polyester-containing acrylic polyol in the polyol in an amount of 40% by weight or more, and a ketone compound in the solvent in an amount of 10 to 50% by weight. Surface finishing method.
2. For polyvinyl chloride surface
A film is formed with a coating material containing a polyol, a polyisocyanate, and a solvent as essential components, containing at least 40% by weight of a polyester-containing acrylic polyol in the polyol, and containing 10 to 50% by weight of a ketone compound in the solvent,
A surface finishing method comprising forming a film with a top coating material.

  The finishing method of the present invention is suitable for repainting a polyvinyl chloride surface. ADVANTAGE OF THE INVENTION According to this invention, while being excellent in the adhesiveness with respect to a polyvinyl chloride surface, the film which can suppress a plasticizer transfer can be formed.

  Hereinafter, the best mode for carrying out the present invention will be described.

  The present invention is applied to a polyvinyl chloride surface, and particularly effectively acts on a polyvinyl chloride surface containing a plasticizer. Examples of the material having such a polyvinyl chloride surface include a polyvinyl chloride coated steel sheet and a polyvinyl chloride sheet. Among these, the polyvinyl chloride coated steel sheet is a sheet in which a polyvinyl chloride film is formed on various steel sheets. Examples of the polyvinyl chloride coated steel plate include materials specified in JIS K6744.

  Examples of the steel plate used for the polyvinyl chloride coated steel plate include a hot rolled steel plate, a cold rolled steel plate, a hot dip galvanized steel plate, a stainless steel plate, and an aluminum plate. As the polyvinyl chloride resin used for the polyvinyl chloride coating, those produced by a method such as suspension polymerization or emulsion polymerization can be used. Examples of the plasticizer blended in the polyvinyl chloride film include, for example, dioctyl phthalate, trioctyl trimellitic ester, triisodecyl trimellitic ester, dioctyl adipate, dioctyl sebacate, diisodecyl sebacate Examples include esters, azelaic acid dioctyl ester, epoxidized soybean oil, and epoxidized linseed oil.

  In the present invention, a film is formed on the polyvinyl chloride surface with a specific coating material. The coating material includes a polyester-containing acrylic polyol as a polyol, a polyisocyanate as a component that causes a curing reaction with the polyol, and a ketone compound as a solvent. In the present invention, by using such a covering material, adhesion to the polyvinyl chloride surface and prevention of plasticizer migration can be exhibited. When only a normal acrylic polyol is used as the polyol component, it is difficult to obtain sufficient performance in adhesion to the polyvinyl chloride surface, and it is disadvantageous in terms of preventing plasticizer migration.

  Among the components constituting the coating material, the polyester-containing acrylic polyol is composed of a main chain made of acrylic polyol and a side chain made of polyester. Such a polyester-containing acrylic polyol can be obtained, for example, by reacting a polyester resin (a) having a polymerizable unsaturated group, a hydroxyl group-containing monomer (b), and another polymerizable monomer (c).

  Among the above components, the polyester resin (a) having a polymerizable unsaturated group (hereinafter referred to as “component (a)”) is obtained by polycondensing a polybasic acid and a polyhydric alcohol to obtain a polyester resin. The acid and / or polyhydric alcohol can be obtained by using a part having a polymerizable unsaturated group. Moreover, (a) component makes the polyester resin react the monomer which can react with the hydroxyl group or carboxyl group in a polyester resin, specifically, maleic acid, (meth) acrylic acid, glycidyl (meth) acrylate, etc. Can also be obtained. The component (a) is usually used at a ratio of about 2 to 20% by weight in the polyester-containing acrylic polyol.

  The hydroxyl group-containing monomer (b) (hereinafter referred to as “component (b)”) is a compound having a hydroxyl group and a polymerizable unsaturated group, and provides a reaction point with polyisocyanate. As such component (b), for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, ethylene glycol mono (meth) acrylate, and the like can be used. The component (b) may be introduced within a range where the hydroxyl value of the polyester-containing acrylic polyol is 5 to 200 KOHmg / g (preferably 10 to 150 KOHmg / g, more preferably 20 to 100 KOHmg / g).

  Other polymerizable monomers (c) (hereinafter referred to as “component (c)”) include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and the like (meta ) Acrylic acid alkyl ester; Aromatic monomers such as styrene, 2-methylstyrene and vinyltoluene; Epoxy group-containing monomers such as glycidyl (meth) acrylate and diglycidyl fumarate; Amide groups such as maleic acid amide and (meth) acrylamide Containing monomer: Carboxyl group-containing monomers such as (meth) acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid and the like can be used. The component (c) preferably contains at least a (meth) acrylic acid alkyl ester.

  Further, the component (c) preferably contains at least a carboxyl group-containing monomer. This carboxyl group-containing monomer is a compound having a carboxyl group and a polymerizable unsaturated group. By including a carboxyl group-containing monomer in the component (c), the curing reaction of the coating material is promoted, which is advantageous for manifesting effects such as adhesion and plasticizer migration prevention. It is desirable that the carboxyl group-containing monomer is introduced within a range in which the acid value of the polyester-containing acrylic polyol is 0.1 to 30 KOHmg / g (preferably 1 to 25 KOHmg / g, more preferably 2 to 20 KOHmg / g).

  The polyester-containing acrylic polyol in the present invention can be obtained by radical polymerization of the monomer component. The weight average molecular weight of the polyester-containing acrylic polyol is usually about 5,000 to 200,000 (preferably 10,000 to 100,000). Moreover, glass transition temperature is about 0-100 degreeC (preferably 30-70 degreeC) normally.

The coating material of the present invention is prepared such that the weight ratio of the polyester-containing acrylic polyol is 40% by weight or more, preferably 50% by weight or more, and more preferably 55% by weight or more based on the solid content. Within such a range, the effects of the present invention can be obtained. The polyol may contain a polyol other than the polyester-containing acrylic polyol as necessary, but an embodiment in which the polyol is composed only of the polyester-containing acrylic polyol is also suitable. Examples of polyols other than polyester-containing acrylic polyols include acrylic polyols, polyester polyols, and polyether polyols. In this, an acrylic polyol is suitable.
The hydroxyl value of the acrylic polyol is desirably 5 to 200 KOH mg / g (preferably 10 to 150 KOH mg / g, more preferably 20 to 100 KOH mg / g). The acid value of the acrylic polyol is desirably 0.1 to 30 KOH mg / g (preferably 1 to 25 KOH mg / g, more preferably 2 to 20 KOH mg / g). The weight average molecular weight is usually about 5,000 to 200,000 (preferably 10,000 to 100,000), and the glass transition temperature is usually about 0 to 100 ° C. (preferably 30 to 70 ° C.).
In addition, said hydroxyl value and acid value are both values with respect to resin solid content.

  The polyisocyanate in the coating material of the present invention is a component that causes a curing reaction with the polyol. In the present invention, by such a curing reaction, sufficient effects are exhibited from the initial stage of film formation in terms of adhesion, plasticizer migration prevention properties and the like. Moisture curable urethane resins that cause a curing reaction due to moisture in the air require a considerable amount of time to cure, so that the effect at the initial stage of film formation tends to be insufficient.

Examples of the polyisocyanate include toluene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (pure-MDI), polymeric MDI, xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), and hydrogenation. XDI, hydrogenated MDI, or the like, or those derivatized by allohanation, biuretization, dimerization (uretidione), trimerization (isocyanurate), adduct formation, carbodiimide reaction, or the like can be used.
The mixing ratio of these polyisocyanates and polyols may be within a range such that the NCO / OH ratio is usually 0.7 to 2.0, preferably 0.8 to 1.5.

The coating material of the present invention contains a ketone compound as a solvent. Such a ketone compound greatly contributes to the expression of adhesion to the polyvinyl chloride surface. Furthermore, since such a ketone compound expresses the drying acceleration effect of the coating film, it acts effectively also in terms of improving the plasticizer migration prevention property.
Examples of the ketone compound include acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, methyl-n-hexyl ketone, methyl amyl ketone, and cyclohexanone, and one or more of these can be used. In the present invention, among these, it is desirable to include one or more selected from acetone, methyl ethyl ketone, and methyl isobutyl ketone.

  In this invention, it prepares so that the weight ratio of the ketone compound in the whole solvent may be 10 to 50% by weight, preferably 20 to 45% by weight, more preferably 30 to 40% by weight. If it is in such a range, the effect of this invention can fully be acquired. When a ketone compound is smaller than the said ratio, it becomes difficult to acquire sufficient effect in adhesiveness, a plasticizer transfer prevention property, etc. On the other hand, when the ketone compound is larger than the above ratio, drying at the time of film formation becomes too fast, which may adversely affect workability, adhesion and the like.

  Examples of the solvent other than the ketone compound include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, isoamyl acetate, n-amyl acetate, methyl cellosolve acetate, cellosolve acetate, butyl cellosolve, Examples thereof include ester compounds such as methoxypropyl acetate, methoxybutyl acetate, carbitol acetate, and butyl carbitol acetate, aromatic hydrocarbon compounds such as toluene and xylene, and aliphatic hydrocarbon compounds such as mineral spirits. In this invention, what is necessary is just to use it combining a ketone compound and another solvent within the range from which the weight ratio of a ketone compound becomes the said ratio. Among these, the ratio of the aliphatic hydrocarbon compound is desirably 50% by weight or less (preferably 30% by weight or less) in the solvent, and an embodiment that does not include the aliphatic hydrocarbon compound as the solvent is also suitable. In the present invention, a solvent containing a ketone compound, an ester compound and an aromatic hydrocarbon compound is particularly suitable. In addition, the solvent used as media, such as a polyol and isocyanate, is also included by the solvent in this invention.

  In addition to the above-described components, the coating material of the present invention can be blended with various components within a range that does not significantly impair the effects of the present invention. Examples of such components include coloring pigments, extender pigments, thickeners, plasticizers, antiseptics, antifungal agents, algaeproofing agents, antifoaming agents, leveling agents, pigment dispersants, antiskinning agents, and dryers. , Matting agents, ultraviolet absorbers, light stabilizers, antioxidants, low-contaminating agents, catalysts and the like.

  Among these, as coloring pigments, for example, titanium oxide, zinc oxide, carbon black, iron black, copper / chrome black, cobalt black, copper / manganese / iron black, molybdate orange, ferric oxide (Bengara), yellow oxidation Inorganic color pigments such as iron, titanium yellow, ultramarine blue, bitumen, cobalt / aluminum blue, chrome green, cobalt green, azo, naphthol, pyrazolone, anthraquinone, perylene, quinacridone, disazo, isoindolinone And organic coloring pigments such as benzimidazolone, phthalocyanine, and quinophthalone. Examples of extender pigments include heavy calcium carbonate, clay, kaolin, talc, precipitated barium sulfate, barium carbonate, white carbon, and diatomaceous earth.

  In the coating material of the present invention, by including powder components such as a color pigment and an extender pigment, the cohesive force at the time of film formation is increased, and a more excellent effect in adhesion and the like can be obtained. In order to acquire such an effect, the aspect which contains 10-200 weight part (preferably 20-150 weight part) of a powder component with respect to 100 weight part of total solid content of a polyol and polyisocyanate is desirable. In such an embodiment, when the powder component is 100 parts by weight or less, the finish of the top coating material can be improved. Further, by using a powder component having an average particle size of 1 μm or more (preferably 5 to 50 μm), it is possible to further improve the adhesion, the plasticizer migration prevention property and the like.

The coating material of the present invention may be coated by mixing a main agent containing a polyester-containing acrylic polyol and a curing agent containing a polyisocyanate immediately before coating. The solvent can be included in either the main agent, the curing agent, or both. Moreover, in this invention, a solvent can also be mixed at the time of a coating as a diluent separately from a main ingredient and a hardening | curing agent. What is necessary is just to prepare about the solvent of this invention coating | covering material so that the ratio of the ketone compound in the solvent at the time of coating may finally become in the said range.
In the coating material of the present invention, the solvent is contained in an amount of 100 to 500 parts by weight (preferably 110 to 400 parts by weight, more preferably 120 to 300 parts by weight) with respect to 100 parts by weight of the total solid content of polyol and polyisocyanate. It is desirable. If the content of the solvent is within such a range, it is preferable in terms of preventing plasticizer migration, finishing of the top coating material, and the like.

The coating material of the present invention can be applied using various methods such as brush coating, roller coating, and spray coating. The coating amount at the time of coating is usually about 30 to 500 g / m ² , preferably about 50 to 300 g / m ² . The number of coatings of the covering material may be appropriately set depending on the surface state of the polyvinyl chloride surface, etc., but is usually 1 to 2 times.

In the present invention, the top coating material can be applied after the coating film is dried. If such a top coating material has a cosmetic property, a desired hue, gloss, surface pattern and the like can be imparted.
Specifically, examples of the top coating material include alkyd resin-based paints, acrylic resin-based paints, urethane resin-based paints, acrylic silicon resin-based paints, and fluororesin-based paints. Examples of the form of the resin include an aqueous resin, a non-aqueous resin, and a solventless resin. Of these, non-aqueous resins are preferred. As the non-aqueous resin, a solvent-soluble resin and / or a non-aqueous dispersion resin can be used. Such an overcoating material usually contains such a resin and a coloring pigment as essential components.

  In the present invention, by using a thermosetting resin as a binder in the overcoat material, weather resistance, water resistance, swelling prevention, peeling prevention and the like can be improved. Examples of thermosetting resins include carboxyl group and carbodiimide group, carboxyl group and epoxy group, carboxyl group and aziridine group, carboxyl group and oxazoline group, hydroxyl group and isocyanate group, carbonyl group and hydrazino group, epoxy group and hydrazino group, epoxy Those having a crosslinkability by a functional group such as a group, an amino group, or an alkoxysilyl group can be used. Among these, those having a crosslinkability by a hydroxyl group and an isocyanate group are particularly preferable in terms of durability, adhesion and the like. As such a top coating material, for example, a non-aqueous resin having a hydroxyl group and a polyisocyanate as a resin component can be used.

In the coating of the top coat material, for example, various methods such as brush coating, roller coating, and spray coating can be employed. Coating with the amount of overcoating material depends on the type of paint, usually 50 to 500 g / ^{m 2} approximately, and preferably from 100 to 400 g / ^{m 2} approximately.
In addition, although what is necessary is just to use 1 type of material for coating of a top coat material, it is also possible to laminate | stack 2 or more types.

  Examples are given below to clarify the features of the present invention.

44 parts by weight of polyol, 28 parts by weight of solvent, 12 parts by weight of coloring pigment, 14 parts by weight of extender pigment, 1.5 parts by weight of dispersant and 0.5 part by weight of antifoaming agent are uniformly mixed and stirred by a conventional method. Thus, the main agent was produced.
On the other hand, a curing agent was produced by uniformly mixing and stirring 33 parts by weight of polyisocyanate and 67 parts by weight of a solvent by a conventional method.
As the coating material, a mixture obtained by mixing the main agent and the curing agent so that the NCO / OH ratio was 1.1 / 1.0 was used.
The ratio of the solvent in the coating material is 224 parts by weight with respect to 100 parts by weight of the total solid content of polyol and polyisocyanate. The ratio of the powder component (color pigment and extender pigment) is 103 parts by weight with respect to 100 parts by weight of the total solid content of polyol and polyisocyanate.
In addition, the following were used as a raw material in a coating | covering material.

Polyol 1 (polyester-containing acrylic polyol, polyester ratio 10% by weight, hydroxyl value 40 KOH mg / g, acid value 6 KOH mg / g, weight average molecular weight 33000, glass transition temperature 52 ° C., solid content 50% by weight, medium: aromatic hydrocarbon Compounds, ester compounds)
Polyol 2 (acrylic polyol, hydroxyl value 40 KOH mg / g, acid value 6 KOH mg / g, weight average molecular weight 30000, glass transition temperature 52 ° C., solid content 50% by weight, medium: aromatic hydrocarbon compound, ester compound)
・ Coloring pigment (titanium oxide, average particle size 0.3μm)
・ External pigment (talc, average particle size 8μm)
・ Polyisocyanate (hexamethylene diisocyanate trimer, NCO ratio 23% by weight)

Example 1
In Example 1, as the polyol in the main agent, polyol 1 and polyol 2 were mixed at a solid content weight ratio of 60:40, the ratio of the ketone compound (methyl isobutyl ketone) in the entire solvent was 28% by weight, and the ester compound was 36% by weight. %, Using the coating material prepared to 36% by weight of aromatic hydrocarbon compound, the following tests were conducted. The test results are shown in Table 1.

(1) Adhesion test 1
The coating material was brush-coated at a coating amount of 100 g / m ² on a 150 mm × 70 mm polyvinyl chloride-coated steel plate (containing a plasticizer) and cured for 72 hours. The coating, curing, and the like were all performed under standard conditions (temperature 23 ° C., relative humidity 50%).
In the adhesion test 1, the specimen obtained by the above method was immersed in warm water at 50 ° C. for 72 hours, and then evaluated by a cross-cut method (4 × 4 mm · 25 squares). In this test, the larger the value, the better the adhesion.

(2) Adhesion test 2
The coating material was brush-coated at a coating amount of 100 g / m ² on a 150 mm × 70 mm polyvinyl chloride coated steel plate (containing a plasticizer), and cured for 24 hours. Next, the top coating material (polyurethane resin paint corresponding to JIS K5656) was spray-coated at a coating amount of 0.3 kg / m ² and cured for 72 hours. All painting, curing, etc. were performed under standard conditions.
In the adhesion test 2, the specimen obtained by the above method was immersed in warm water at 50 ° C. for 72 hours, and then evaluated by a cross-cut method (4 × 4 mm · 25 squares). In this test, the larger the value, the better the adhesion.

(3) Plasticizer migration prevention test On a 150 mm x 70 mm polyvinyl chloride coated steel sheet (containing a plasticizer), the coating material was brushed at a coating amount of 100 g / m ² and cured for 24 hours. Next, the top coating material (polyurethane resin paint corresponding to JIS K5656) was spray-coated at a coating amount of 0.3 kg / m ² and cured for 72 hours. All painting, curing, etc. were performed under standard conditions.
The test plate obtained by the above method was left in an incubator at 80 ° C. for 6 hours, then removed from the incubator, placed horizontally and sprayed with black silica sand, and then the test plate was set up vertically to allow the silica sand to fall naturally. . At this time, the plasticizer transfer prevention property was evaluated by visually confirming the degree of the adhered black silica sand. The evaluation was performed in three stages (◯>Δ> ×) where “◯” indicates that black silica sand hardly adhered, and “x” indicates that black silica sand significantly adhered.

(Example 2 to Comparative Example 5)
As shown in Tables 1 and 2, tests were performed in the same manner as in Example 1 except that the polyol and solvent in the coating material were prepared. Test results are shown in Tables 1-2.

(Example 7)
The main agent is obtained by uniformly mixing and stirring 60 parts by weight of a polyol, 38 parts by weight of a solvent, 1.5 parts by weight of a color pigment, 0.3 parts by weight of a dispersant, and 0.2 parts by weight of an antifoaming agent by a conventional method. Manufactured. Here, as the polyol, polyol 1 and polyol 2 were used at a solid content weight ratio of 60:40.
On the other hand, a curing agent was produced by uniformly mixing and stirring 33 parts by weight of polyisocyanate and 67 parts by weight of a solvent by a conventional method.
As the coating material, a mixture obtained by mixing the main agent and the curing agent so that the NCO / OH ratio was 1.1 / 1.0 was used.
The ratio of the solvent in this coating material is 223 parts by weight with respect to 100 parts by weight of the total solid content of polyol and polyisocyanate. The ratio of the powder component (color pigment) is 4 parts by weight with respect to 100 parts by weight of the total solid content of polyol and polyisocyanate.
In Example 7, a coating material prepared by adjusting the ratio of the ketone compound (methyl isobutyl ketone) in the entire solvent to 36% by weight, the ester compound 30% by weight, and the aromatic hydrocarbon compound 34% by weight was used. A similar test was conducted. The results are shown in Table 3.

(Example 8)
A main agent was produced by uniformly mixing and stirring 56 parts by weight of a polyol, 30 parts by weight of a solvent, 12 parts by weight of a coloring pigment, 1.5 parts by weight of a dispersant, and 0.5 parts by weight of an antifoaming agent by a conventional method. . Here, as the polyol, polyol 1 and polyol 2 were used at a solid content weight ratio of 60:40.
On the other hand, a curing agent was produced by uniformly mixing and stirring 33 parts by weight of polyisocyanate and 67 parts by weight of a solvent by a conventional method.
As the coating material, a mixture obtained by mixing the main agent and the curing agent so that the NCO / OH ratio was 1.1 / 1.0 was used.
The ratio of the solvent in this coating material is 206 parts by weight with respect to 100 parts by weight of the total solid content of polyol and polyisocyanate. The ratio of the powder component (color pigment) is 37 parts by weight with respect to 100 parts by weight of the total solid content of polyol and polyisocyanate.
In Example 8, the ratio of the ketone compound (methyl isobutyl ketone) in the entire solvent was 36% by weight, the ester compound was 30% by weight, and the coating material prepared was 34% by weight of the aromatic hydrocarbon compound. A similar test was conducted. The results are shown in Table 3. In Example 8, the finish of the top coat material was better than that of Examples 1-6.

Claims (2)

For polyvinyl chloride surface
The coating film is formed by a coating material containing a polyol, a polyisocyanate, and a solvent as essential components, the polyester-containing acrylic polyol in the polyol in an amount of 40% by weight or more, and a ketone compound in the solvent in an amount of 10 to 50% by weight. Surface finishing method. For polyvinyl chloride surface
A film is formed with a coating material containing a polyol, a polyisocyanate, and a solvent as essential components, containing at least 40% by weight of a polyester-containing acrylic polyol in the polyol, and containing 10 to 50% by weight of a ketone compound in the solvent,
A surface finishing method comprising forming a film with a top coating material.