JP2013018915A - Coating material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating material composition capable of forming a coating film having excellent heat resistance.SOLUTION: The coating material composition contains a synthetic resin binder and 2-20 mass% polyvinyl alcohol and/or the derivative in the total amount of the synthetic resin binder. It is particularly preferable to contain a synthetic resin emulsion as the synthetic resin binder and to contain 70 mass% or more of nonvolatile portion of the synthetic emulsion in the total amount of the synthetic resin binder.

Description

  The present invention relates to a coating agent composition containing polyvinyl alcohol and / or a derivative thereof as a synthetic resin binder.

  Conventionally, polyvinyl alcohol is sometimes used as a protective colloid of a synthetic resin emulsion used as a binder of a coating agent composition (for example, Patent Document 1). In addition to the polymer emulsions described above, phenol resins, amino resins, polyvinyl alcohol, polyvinyl alcohol derivatives, etc. for the purpose of improving the curability and adhesion of water-based paints and water-based coating agent compositions using a synthetic resin emulsion as a binder 1 type or 2 types or more may be added (for example, patent document 2 etc.).

  Thus, in the coating agent composition containing polyvinyl alcohol, since polyvinyl alcohol is used as a protective colloid or for the purpose of improving curability and adhesion, the content of polyvinyl alcohol is not so high.

JP 2010-280852 A JP 2008-101077 A

  The present inventor examined the technique for improving the heat resistance of a coating agent composition containing a synthetic resin binder, and contained a suitable amount of polyvinyl alcohol or a derivative thereof in the synthetic resin binder. The present inventors have found that a coating film formed from the composition is excellent in heat resistance, and have reached the present invention.

  An object of this invention is to provide the coating agent composition which can form the coating film excellent in heat resistance.

  The invention according to claim 1 is a coating agent composition comprising a synthetic resin binder and containing 2 to 20% by mass of polyvinyl alcohol and / or a derivative thereof in the total amount of the synthetic resin binder. is there.

  The invention according to claim 2 is the coating agent composition according to claim 1, wherein the synthetic resin binder is contained as the synthetic resin binder, and the non-volatile content of the synthetic resin emulsion is 70 in the total amount of the synthetic resin binder. It is characterized by containing at least mass%.

  Invention of Claim 3 is a coating agent composition of Claim 1 or 2, The saponification degree of the said polyvinyl alcohol or its derivative (s) is 70.0 mol% or more, It is characterized by the above-mentioned.

Invention of Claim 4 is a coating agent composition in any one of Claims 1-3, The polymerization degree of the said polyvinyl alcohol or its derivative (s) is 300-3500, It is characterized by the above-mentioned.

  If the coating agent composition of this invention is used, the coating film excellent in heat resistance can be obtained.

  Moreover, the coating film which was more excellent in heat resistance is obtained by making the content rate of the water-soluble polymer in the whole quantity of a synthetic resin binder into 2-30 mass%.

  Moreover, if the saponification degree of polyvinyl alcohol or a derivative thereof is 70.0 mol% or more, a coating film having a particularly excellent heat resistance can be obtained, and if the polymerization degree is 300 to 3500, the heat resistance is particularly excellent. A coating film is obtained.

The coating agent composition of the present invention contains a synthetic resin binder, and 2 to 20% by mass of polyvinyl alcohol and / or its derivative is contained in the total amount of the synthetic resin binder.

The synthetic resin binder is a synthetic resin component that can form a film by drying or reaction curing, and is a component that remains in the film formed by the coating agent composition and serves as a binder for the film. Solid components that cannot form a film, such as a synthetic resin filler, are not included in the synthetic resin binder.
Specific examples of the synthetic resin binder include synthetic resin emulsions and water-soluble polymers.

The synthetic resin emulsion can be appropriately selected from those used in ordinary coating agent compositions and water-based paints. For example, vinyl resins such as vinyl acetate, ethylene vinyl acetate, vinyl propionate and vinyl versatate; methyl (meth) acrylate resin, ethyl (meth) acrylate resin, methyl (meth) acrylate resin, (meth) acrylic Acrylic resin such as ethyl acid resin, (meth) acrylic acid butyl resin, (meth) acrylic acid 2-ethylhexyl resin, acrylonitrile resin, methacrylonitrile resin; polyester resin; fluororesin; epoxy resin; polyurethane resin; A vinyl acetate resin; a resin in which a synthetic resin such as a silicone resin is dispersed in water, or a resin in which two or more synthetic resins are copolymerized in water can be used. Two or more synthetic resin emulsions may be mixed and used.

The synthetic resin is preferably an acrylic resin. By using the acrylic resin in combination with polyvinyl alcohol or a derivative thereof, an acrylic resin coating film with better heat resistance can be obtained.

The synthetic resin is excellent in affinity with polyvinyl alcohol or a derivative thereof by using an emulsion. In addition, a coating film having more excellent heat resistance can be obtained.

  The water-soluble polymer refers to a water-soluble polymer, generally having a molecular weight of 10,000 or more and having a water-soluble group such as a hydroxyl group, a carboxyl group, a carboxylic acid ester group, or a sulfonic acid group. A molecular compound. Examples thereof include polyvinyl alcohol, starches, water-soluble acrylic resins, water-soluble apolyester resins, water-soluble apolyamide resins, water-soluble apolyurethane resins, and cellulose derivatives (such as methylcellulose, hydroxycellulose, and hydroxypropylcellulose).

The polyvinyl alcohol is represented by the following chemical formula.

In addition, OAc in Chemical formula 1 represents an acetic acid group. M is an integer of 1 or more, and n is an integer of 0 or more.
The derivatives of the polyvinyl alcohol are ethylene-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, modified polyvinyl alcohol such as cation-modified polyvinyl alcohol, hydroxyl groups such as carbonyl group, carboxyl group, alkyl group, and acetate groups. Polyvinyl alcohol having a functional group.

In addition, the value of “m + n” in Chemical Formula 1 is referred to as the polymerization degree, and the value of “(m / (m + n)) × 100” is referred to as the saponification degree.

The degree of polymerization of the polyvinyl alcohol or derivative thereof is preferably 300 to 3500, more preferably 400 to 2500, and most preferably 450 to 1200. When it exists in this range, the coating film by a coating agent composition is excellent in heat resistance. When the degree of polymerization of the polyvinyl alcohol or its derivative is too small, the heat resistance is not sufficient. Conversely, if the degree of polymerization is too large, the affinity with the synthetic resin emulsion is not sufficient.
The saponification degree of the polyvinyl alcohol or a derivative thereof is preferably 70.0 mol% or more, more preferably 75.0 to 99.0, and most preferably 80.0 to 90.0. When it exists in this range, the coating film by a coating agent composition is excellent in heat resistance. When the saponification degree of the polyvinyl alcohol or its derivative is too small, the heat resistance of the coating film is not sufficient. Moreover, the water resistance of the coating film also decreases. On the other hand, when the degree of saponification is too large, the miscibility with the synthetic resin emulsion is not sufficient, so that the storage stability (JIS A6909) of the coating agent composition is lowered.

The content of polyvinyl alcohol or a derivative thereof in the total amount of the synthetic resin binder is preferably 2 to 20% by mass, more preferably 5 to 18% by mass, and particularly preferably 8 to 15% by mass. When it exists in this range, the coating film by a coating agent composition is excellent in heat resistance. When there is too little content rate of the said polyvinyl alcohol or its derivative (s), the heat resistance of the coating film by a coating agent composition is not enough. On the other hand, if the content is too high, the water resistance of the coating film is lowered, so that the heat resistance under humid conditions is not sufficient.

  Further, the synthetic resin binder preferably comprises a non-volatile content of the synthetic resin emulsion, and the non-volatile content of the synthetic resin emulsion in the total amount of the synthetic resin binder is preferably It is 70 mass% or more, More preferably, it is 80 mass% or more. In addition, since the said coating agent composition necessarily contains polyvinyl alcohol or its derivative in the whole quantity of a synthetic resin binder, the content rate of the non volatile matter of a synthetic resin emulsion is substantially from the whole quantity of a synthetic resin binder. The amount obtained by subtracting the content of polyvinyl alcohol or its derivative is the upper limit. When the non-volatile content of the synthetic resin emulsion is within this range, a coating agent composition having particularly excellent heat resistance can be obtained.

  The coating agent composition may contain pigments, fillers, additives and the like other than the synthetic resin binder as long as the effects of the present invention are not impaired. These may be appropriately selected from those usually used in paints using a synthetic resin binder as a binder.

  For example, the pigments include cadmium red, red rose, toluidine red, yellow lead, iron yellow, titanium yellow, fast yellow, anthraquinone yellow, benzidine yellow, chromium oxide, phthalocyanine green, bitumen, ultramarine blue, phthaloncyanine blue, carbon black, Inorganic pigments and organic pigments such as iron black and graphite can be used.

  As the filler, for example, calcium carbonate, talc, kaolin clay, calcium oxide, glass beads, resin beads, silica sand, cold water sand, metal powder, and the like can be used.

Examples of additives include viscosity modifiers such as thickeners, surfactants such as wetting agents and dispersants, antifoaming agents, film forming aids, antifreezing agents, crosslinking agents, antioxidants, and ultraviolet rays. Absorbers, light stabilizers, leveling agents, silane coupling agents, preservatives, algaeproofing agents and the like can be used.

Among these fillers and additives, it is preferable to use metal powder such as aluminum powder in the coating composition of the present invention. The OH group of polyvinyl alcohol or a derivative thereof crosslinks with a metal, and a coating agent composition having excellent heat resistance is obtained.
The metal is particularly preferably one whose outermost shell is not closed and has one or more empty orbits. Since the outermost shell of the metal is not closed and there are one or more vacant orbitals, the OH group of the polyvinyl alcohol or its derivative and the metal are easily cross-linked by a coordinate bond.

The method of coating with the coating agent composition is not particularly limited, and for example, it can be applied by a general paint application method. For example, it can be painted using a painting tool or a coating machine such as a brush, a roller, an air spray, an airless spray, a flow coater, a roll coater, or a curtain coater. Moreover, you may paint by dipping etc., without using a painting tool or a coating machine.

The coating agent compositions having the formulations shown in Table 1 and Table 2 were prepared, and the heat resistance of these coating agent compositions was confirmed by the following method.

The formulations shown in Tables 1 and 2 show the amount of each material added in parts by mass.
In addition, the following were used for polyvinyl alcohol (it describes with "PVA" in Table 1).
PVA 1: Degree of polymerization 600, degree of saponification 87 mol%
PVA 2: degree of polymerization 2000, degree of saponification 87 mol%
PVA 3: polymerization degree 600, saponification degree 95 mol%

  Further, as a polyvinyl alcohol derivative, silanol-modified polyvinyl alcohol having a polymerization degree of 600 and a saponification degree of 88 mol% was used.

  In addition, before mixing with the synthetic resin emulsion, the polyvinyl alcohol and the derivative of polyvinyl alcohol were previously dissolved in “water” being blended.

  An acrylic resin emulsion having a nonvolatile content of 45% by mass was used as the synthetic resin emulsion.

  Moreover, a film-forming aid, an antifoaming agent, and a thickener were used as additives. In addition, in the additive in a table | surface, hydroxyethyl cellulose (HEC) etc. are contained as a water-soluble polymer. In addition, calcium carbonate and aluminum powder were used as fillers.

  In Tables 1 and 2, the content of “synthetic resin binder” is indicated as “A”, the content of “polyvinyl alcohol and its derivatives” is indicated as “B”, and “B content in the total amount of A” “Rate (rounded to the nearest two decimal places)” is displayed as “(B / A) × 100”.

(Test specimen)
As the substrate, a copper plate having a size of 10 cm × 20 cm and a thickness of 0.5 mm was used. A test specimen was prepared by dipping the coating agent compositions shown as Examples and Comparative Examples in Tables 1 and 2 on the surface of the base material and allowing them to stand for 3 days. In addition, dipping coating was performed several times for each test body, and the film thickness of the coating layer by the coating agent composition was set to 100 ± 5 μm for each test body.

(Heat resistance test)
The constant temperature and humidity chamber was set to a temperature of 80 ° C. and a humidity of 95%, and the test body coated with the coating agent composition of each Example and Comparative Example was left in the constant temperature and humidity chamber for one week.
One week later, the specimen was taken out from the thermo-hygrostat and allowed to stand for 24 hours in a normal temperature environment, and then the state of the coating film was observed visually and with a microscope (100 times).

In the heat resistance test, Table 3 and Table 4 show the results of evaluating the state of the coating film of the test specimen according to the following criteria.
○: No abnormality in coating film.
(Triangle | delta): The coating film has discolored.
X: Swelling has occurred in the coating film.

(Heat resistance test)
As a result of the heat resistance test, a hot water resistance test was performed in order to select a coating agent composition having particularly excellent heat resistance among coating agent compositions that are known to have excellent heat resistance.
The test body which apply | coated the coating agent composition of each Example and the comparative example was immersed in the hot water of temperature 100 degreeC, and left still for 50 hours. After 50 hours, the test specimen was taken out from the hot water and allowed to stand for 24 hours in a room temperature environment, and then the state of the coating film was observed visually and with a microscope (100 times).

In the hot water resistance test, Table 3 and Table 4 show the results of evaluating the state of the coating film of the test specimen according to the following criteria.
○: No abnormality in coating film.
(Triangle | delta): The coating film has discolored.
X: The coating film and the base material (copper plate) are discolored.

From the results of the heat resistance test shown in Table 3 and Table 4, the following can be said.
When the ratio of polyvinyl alcohol or its derivative in the total amount of the synthetic resin binder is a certain amount or more, the heat resistance of the coating film is improved (Comparative Examples 1, 2, Examples 1 to 9). However, when the ratio of polyvinyl alcohol or its derivative exceeds a certain amount, discoloration tends to occur in the coating film (Comparative Example 3).

Moreover, the following can be said from the result of the hot water resistance test.
Those having a ratio of polyvinyl alcohol or a derivative thereof in the total amount of the synthetic resin binder of Examples 2 to 5 and Examples 7 to 9 are particularly excellent in heat resistance.
Those using aluminum powder as the filler have improved heat resistance compared to those using calcium carbonate as the filler (Examples 11 to 12 and Examples 13 to 14).

Claims (4)

A coating agent composition comprising a synthetic resin binder and containing 2 to 20% by mass of polyvinyl alcohol and / or a derivative thereof in the total amount of the synthetic resin binder.   The coating agent composition according to claim 1, wherein a synthetic resin emulsion is contained as the synthetic resin binder, and the nonvolatile content of the synthetic resin emulsion is contained in an amount of 70% by mass or more in the total amount of the synthetic resin binder.   The coating agent composition according to claim 1 or 2, wherein the saponification degree of the polyvinyl alcohol or a derivative thereof is 70.0 mol% or more. 4. The coating agent composition according to claim 1, wherein the degree of polymerization of the polyvinyl alcohol or a derivative thereof is 300 to 3500.