JP2000144055A - Water-base coating material for wood - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a coated surface excellent in resistance to stains without detriment to excellent moisture absorbing and desorbing properties and woody texture originally possessed by wood by employing a fluorine-containing silicone resin emulsion specified in its solid concentration, surface tension and pH and without employing organic materials which release formaldehyde or a volatile organic compound. SOLUTION: As a water-base coating material for wood is employed a fluorine-containing silicone resin emulsion having a solid concentration of 4-10 wt.%, a surface tension of 27-34 mN/m and a pH of 4.5-8.5. From the viewpoint of the wetting property to the surface of wood, penetrability, recoatability and the like, the surface tension is preferably low and can be regulated by the addition of a surfactant. As the surfactant capable of attaining uniform coating without bubbles and lowering the surface tension, an acetylene diol type surfactant is preferable. Preferably, the fluorine-containing silicone resin emulsion contains around 20 wt.% of fluorine so as to ensure excellent resistance to stains of the coated surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based paint for wood, and more particularly to a water-based paint suitable for surface coating of wood for interior of buildings.

[0002]

2. Description of the Related Art Conventionally, as a wood coating material, a coating material comprising a solution obtained by dissolving a resin having an adhesive property to a wood surface, such as xyldecor, osmokara, or auro, in an organic solvent, or acrylic emulsion or Aqueous paints such as aqueous urethanes are commonly used.

[0003] Among these wood coatings, the former organic solvent-based coatings are originally intended to impart decay resistance to wood and each have excellent performance, but have the following problems. In recent years, from the viewpoint of energy saving, from the viewpoint of energy saving, the airtightness and insulation of the living space have been remarkably advanced, and as a result of the increase in double-working households, single or small-sized households, it has become difficult for indoor air to be sufficiently ventilated,
In addition, due to factors that increase indoor humidity due to indoor cultivation of houseplants and the like, there is a tendency for an indoor environment in which mold and mites are likely to occur. -The problem of causing sexual illness has become remarkable.

[0004] In recent years, interior materials processed variously using synthetic materials have become popular in houses.
The so-called sick house syndrome caused by formaldehyde and volatile organic compounds (hereinafter abbreviated as VOCs) emitted from the interior materials has been taken up by the media as a social problem. Relying solely on improving the air-conditioning system as a measure to eliminate it and make it more comfortable has not always yielded sufficient results to solve the problem.

[0005] In a hot and humid climatic zone such as Japan, wood which is rich in both moisture absorption and moisture release (hereinafter collectively referred to as moisture absorption and release) under these climatic conditions,
It has been widely used as an interior material since ancient times, and the use of such wood still plays an important role in indoor humidity control even today. However, in order to prevent stains on the surface of wood used as an interior material, it is common to apply some paint to the surface. However, the conventional paints used for the above-mentioned purpose not only impair the excellent moisture absorption / release properties of wood, but also have the drawback that it is difficult to remove oily stains on the application surface. More recently, the presence of VOCs, which have become a pollutant in living spaces and have received attention for their adverse effects on the human body, has been regarded as a problem, and paints based on organic solvents, which are the basis for the emission of VOCs, have been shunned. is there.

On the other hand, since the latter acrylic emulsion paint and water-based urethane paint are water-based paints, the problem of contamination of the indoor atmosphere by VOC as described above can be avoided. Since the characteristic wood texture is lost, and the resin coating film formed thereby has a moisture barrier property, there is a drawback that the moisture absorption and desorption properties of wood are not sufficiently exhibited.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned disadvantages in paints for coating wood, especially wood used as interior materials for houses,
An object of the present invention is to provide a water-based paint for wood that can form an application surface with excellent stain resistance without using an organic material that emits OC, without deteriorating the excellent moisture absorption and desorption properties of wood and the texture of wood. And

[0008]

The present inventors have conducted various studies in order to solve the above-mentioned problems. As a result, (1) a fluorine-containing silicone resin emulsion was selected as the silicone resin emulsion. When it is used as a paint for wood, not only does the wood texture of the wood not be impaired, but a paint film having higher moisture permeability and air permeability than the paint film formed by the conventional acrylic emulsion paint is produced. Because of its high water and oil repellency, water- and oil-based stains on its painted surface can be easily removed by wiping, and if the coating amount is properly selected, it does not hinder the moisture absorption / release properties of wood at all. In order to form the above-mentioned advantageous coating film by the above-mentioned fluorinated silicone resin emulsion coating material, it is necessary to use Solids fee of 4 to 10% by weight,
It has been found that it must have the properties of a surface tension of 27-34 mN / m and a pH of 4.5-8.5.

The present invention has been made on the basis of these findings, and has a solid content of 4 to 10% by weight and a solid content of 27 to 34 m.
The present invention relates to an aqueous paint for wood, which is a fluorine-containing silicone resin emulsion having a surface tension of N / m and a pH of 4.5 to 8.5.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The characteristics required for the surface of a building material differ depending on how the building material is used. However, it is basically necessary for interior materials of living space to be generally excellent in water repellency and oil repellency. is there. In this living space, contamination of interior materials by food etc. is likely to occur frequently on a daily basis, for example,
It is unavoidable that the adhesion of water-based stains derived from miso soup, soy sauce, vinegar, coffee, and the like, and the adhesion of oily stains derived from edible oil, mayonnaise, etc. occur frequently on a daily basis. It may not only impair the aesthetic appearance of the interior material surface but also become a nutrient source of mold and may be a factor that promotes the development of mold particularly in an atmosphere having a relative humidity of 75% or more.

Therefore, in order to secure a comfortable living space, it is an important requirement of the application surface that the dirt formed on the application surface of the interior material be easily removed by wiping. The properties of the coated surface, which are related to the difficulty of removing dirt by wiping, include water repellency and oil repellency of the surface, and evaluation of these properties is an important guide for judging the suitability of the coated surface. Become.

The water repellency is measured by dropping a predetermined size of water droplet on a coating surface using a dropper, visually measuring the contact angle of the dropped water droplet, and comparing the sizes with each other. Oil repellency is also evaluated using oil droplets such as salad oil or sesame oil instead of water droplets. The fluorine-containing silicone resin emulsion paint according to the present invention preferably contains about 20% by weight of fluorine, but any commercially available fluorine-containing silicone resin may be used.
A resin emulsion can also be used. The solid content of the fluorinated silicone resin emulsion paint according to the present invention means the content of the fluorinated silicone resin dispersed in water, and if the content is less than 4% by weight, sufficient resistance to fluorinated silicone resin is obtained. A coating film having stain resistance and abrasion resistance cannot be obtained. On the other hand, if it exceeds 10% by weight, not only does the moisture absorption / release property of the coating film decrease, but also the penetration of the coating material into wood is hindered. In this invention, the desired adhesion of the paint to the wood surface cannot be obtained.
The solid content of the resin emulsion paint was determined to be 4 to 10% by weight.

The moisture absorption / release properties of the coating film are determined, for example, as follows. 10cm x 10cm x 1cm thick
A paint is applied to a 10 cm × 10 cm surface of a plate having the following dimensions, and the remaining five surfaces excluding the applied surface are coated with aluminum.
After curing the plate material covered with the pump for 48 hours in a thermo-hygrostat kept at a temperature of 20 ° C. and a relative humidity of 50%,
The weight of the plate was measured, then the atmosphere in the constant temperature and humidity chamber was changed to a temperature of 30 ° C. and a relative humidity of 80%, the plate was left under the atmosphere for 24 hours, and the weight was measured. When the amount of increase in weight per unit area of the coated surface is determined from the weight of both, the amount of increase is a measure of the hygroscopicity of the coating film. Contrary to such moisture absorption, the atmosphere in the thermo-hygrostat is heated from a temperature of 30 ° C. and a relative humidity of 80% to a temperature of 20 ° C.
When the weight loss of the coated plate material in the moisture release process of returning the relative humidity to 50%, that is, the amount of moisture release, is obtained, the amount of moisture release is generally about 70 to 80% of the above-mentioned moisture absorption, and the two are approximately proportional. It is in. Therefore, in the present invention, the moisture absorption / release properties of the coating film are evaluated based on the above moisture absorption.

[0014] In many of the conventional wood coatings, the coating film blocks or does not substantially transmit the scent of wood, but the coating of the present invention not only transmits water but also has a good scent of wood. This produces a paint film. To determine whether or not the coating has the scent permeability of wood, or the degree of the scent permeability, apply paint to a wood chip such as cypress or hiba, which is rich in wood, and then dry the coating to determine how much from the application surface. Is determined by a sensory test to determine whether the scent of the tree is felt. The property that the fragrance of wood, which has a favorable effect on the mind and body, is easily released from the interior material through the painted surface into the living space is highly appreciated by those who use this space. It can be said that the characteristics of the fluorine silicone resin emulsion paint are unique to conventional paints for interior wood.

It is technically difficult to reduce the surface tension of the paints according to the invention to less than 27 mN / m while it is 34 mN / m.
If it is larger than this, the penetration of the coating material into the wood structure becomes worse, and unsatisfactory recoatability occurs, that is, it becomes difficult to obtain uniform recoatability with good adhesion. The surface tension of the fluorine silicone resin emulsion paint was determined to be 27 to 34 mN / m.

From the above, the paint of the present invention must have as low a surface tension as possible, that is, within the above-mentioned range, from the viewpoints of wettability to the wood surface, permeability and recoatability. This surface tension can be adjusted by the addition of a surfactant, but a general surfactant lowers and adjusts the surface tension of the paint and at the same time increases its foaming property, so that it can be adjusted during the coating operation. However, the acetylene diol-based surfactant is different from other ordinary surfactants in that it tends to form bubbles on the coating surface, making it difficult to achieve uniform application without bubbles. As a result, it was confirmed that the surface tension of the paint could be reduced without causing bubbles, thereby increasing the wettability and permeability of the paint on the wood surface, and also significantly improving the recoatability.

Although the fluorinated silicone resin emulsion paint according to the present invention has no particular adverse effect on the wood surface itself when its pH is less than 4.5, the paint is in contact with metal. In the present invention, the pH of the fluorine-containing silicone resin emulsion paint is adjusted to 4.5 to 4.5, since rust may be induced, and if the alkalinity exceeds 8.5, the wood may be yellowed.
8.5.

[0018]

EXAMPLES The present invention will be described with reference to examples, but the present invention is of course not limited to these examples. Example 1 A cedar board having dimensions of 10 cm × 10 cm × 1 cm thick was prepared, and a fluorine-containing silicone resin emulsion stock solution having a fluorine content of 18% by weight (fluorine-containing silicone resin manufactured by Konsho Co., Ltd.) Paint 1 comprising a resin emulsion “Isinol KW11”, solid content 30% by weight)
The three paints of the present invention paint 1 (solid content 6% by weight) and comparative paint 2 (solid content 3% by weight) obtained by diluting the emulsion stock solution 5 times and 10 times with water, respectively, were prepared as described above. After brushing each of the 10 cm × 10 cm surfaces of the plate material and curing for 2 days, the remaining five surfaces excluding the coated surface were covered with aluminum tape, and the comparative test piece 1 and the test of the present invention, respectively. A body 1 and a comparative specimen 2 were prepared, and a comparative specimen 3 treated with an aluminum tape as described above was prepared without applying a paint to the surface corresponding to the above-mentioned coated surface. The surface tension of Inventive Paint 1 was 34 mN / m, and the pH was 5.3, as shown in Example 5 below.

Paint 1 of the Present Invention Each test specimen thus obtained was cured for 48 hours in a thermo-hygrostat maintained at a temperature of 20 ° C. and a relative humidity of 50%, and the weight thereof was measured. Then, the atmosphere in the thermo-hygrostat was heated to 30 ° C.
And the relative humidity was changed to 80%, each specimen was left under the atmosphere for 24 hours, and then its weight was measured. The measured weight per unit area of the coated surface (exposed surface) of both of them was measured. , Ie, the amount of increase in the weight of the specimen, was determined as the moisture absorption (g / m ² ) of the specimen. The results are shown in Table 1.

[0020] From the results in Table 1, it is found that the comparative test piece 1 to which the comparative paint 1 having a solid content of 30% by weight was applied, the comparative test piece 3 to which no coating was applied.
Specimen 1 and Comparative Specimen 2 of the present invention coated with inventive paint 1 having a solid content of 5% by weight and comparative paint 2 having a solid content of 3% by weight, respectively, although the moisture absorption is reduced by 40% as compared to It can be seen that the moisture absorption does not decrease.

Next, salad oil colored with soy sauce, coffee and red ink was dropped on the coated surfaces (exposed surface in the case of the comparative test sample 3) of these four test samples using a dropper. And stain these coated or exposed surfaces,
After leaving it for one day, wipe off these stains with a wet cloth, and then check for the presence and degree of remaining stains.
The results are shown in Table 2.

[0022] From the results in Table 2, comparative paint 2 having a solids content of 3% by weight
In Comparative Example 2, the paint of the present invention 1 having a solid content of 6% by weight was applied, though stains of soy sauce, coffee, and salad oil slightly penetrated into the coating film and some stains remained. It can be seen that the water-based and oil-based stains can be removed by wiping the comparative test specimen 1 coated with the test specimen 1 of the present invention and the comparative paint 1 having a solid content of 30% by weight.

Example 2 A cedar plate having a size of 10 cm × 10 cm × 1 cm thick was prepared, and the above-mentioned paint 1 of the present invention, xyladecor, auro, which are commercially available organic solvent-based paints, were prepared.
Osmokara and non-lot cleaner are brush-coated on the 10 cm × 10 cm surface of the plate material, respectively.
After curing for 2 days, the remaining five surfaces except for the coated surface were coated with aluminum tape to prepare test specimen 2 of the present invention and comparative test specimens 4, 5, 6, and 7, respectively. A comparative test piece 8 treated with aluminum tape as described above was prepared without applying the coating material to the surface corresponding to the surface.
Each specimen obtained in this manner was cured for 48 hours in a thermo-hygrostat kept at a temperature of 20 ° C. and a relative humidity of 50%, then weighed, and then weighed. After changing the atmosphere in the atmosphere to a temperature of 30 ° C. and a relative humidity of 80%, each specimen was left under the atmosphere for 24 hours, its weight was measured, and the measured coated surface (exposed surface) ), Ie, the increase in the weight of the test specimens, was determined as the moisture absorption (g / m ² ) of each test specimen, and the results are shown in Table 3.

[0024] From the results shown in Table 3, the moisture absorption of the test specimen 2 of the present invention coated with the paint 1 of the present invention was determined by comparing the moisture absorption of the test specimen 8 with no paint applied.
However, it can be seen that the comparative samples 4 to 7 to which the conventional paint was applied reduced the moisture absorption by 17% or more by the application of those paints.

Example 3 Paint 1 of the present invention, 5-fold diluted paint (comparative paint 3) of a fluorine-free silicone resin emulsion (Rhodorsil 878 manufactured by Rh ヌ ne-Planne), xyldecor, auro,
Osmokara and non-lot clean 10cm x 1
After brush-coating each of the 10 cm × 10 cm surfaces of the cypress board material of 0 cm × 1 cm thickness and curing for 2 days, the remaining five surfaces excluding the coated surface were covered with aluminum tape,
Specimen 3 of the present invention and comparative specimens 9, 10, 11, 12 and 13 were prepared.

Next, in order to examine the water repellency and oil repellency of the coated surfaces of these six types of test pieces, water drops and oil drops of salad oil were dropped on the coated surfaces using a dropper, and the water droplets were applied to these coated surfaces. As a result of visually observing and comparing the contact angles of the oil droplets, the order of the contact angles was as follows. Rank of water repellency Invention specimen 3 ≧ Comparative specimen 9 ≧ Comparative specimen 12> Comparative specimen 13 ≧ Comparative specimen 10 = Comparative specimen 11 Order of oil repellency Invention specimen 3> Comparative specimen 9 ≧ Comparative Specimen 11> Comparative Specimen 12> Comparative Specimen 13 = Comparative Specimen 10 From the comparison of the magnitudes of the contact angles, the water repellency and oil repellency of the surface of the specimen 3 of the present invention coated with the paint 1 of the present invention. It can be seen that is superior to any of the water repellency and oil repellency of the surfaces of the comparative specimens 10 to 13 to which the conventionally used water-based paint for wood was applied. In addition, although a 5-fold dilution of a silicone resin emulsion containing no fluorine contained a coating surface exhibiting good water repellency, its oil repellency was not always good.

Example 4 Paint 1 of the present invention and Comparative Paint 3 on a thin piece of wood having a thickness of 1 mm.
Was brushed. After the coated surfaces were cured at room temperature for 2 days, a piece of wood was attached to a friction tester, and the coated surfaces were mechanically rubbed with a slightly wet cloth, and the contact angles of water droplets and oil droplets before and after the rubbing were measured. Example 3
The water repellency and the oil repellency of the coated surface were examined in the same manner as described above.

As a result, the coated surface formed by the paint 1 of the present invention maintained almost the same contact angle after friction as before, but the contact angle on the coated surface formed by the comparative paint 3 was: After rubbing, it tended to decrease. This indicates that the paint 1 of the present invention is superior to the comparative paint 3 in permeability and adhesion to the wood surface structure. Incidentally, as shown in the following Example 5, the surface tension of the paint 1 of the present invention was 34 mN /
m, whereas the surface tension of Comparative Paint 3 was 50 mN.
/ M.

Example 5 The surface tension of the paint 1 of the present invention was measured with a Dunui's surface tensiometer to be 34 mN / m. This paint 1 of the present invention
After adding 0.5% by weight of an acetylene diol-based surfactant "Surfinol 104E" manufactured by Air Products Co., Ltd., and sufficiently stirring the mixture, the surface tension was measured.
mN / m.

The paint of the present invention 1 and the comparative paint 3 were each brush-coated on the cypress board material used in Example 4, and the coated surfaces were aged at room temperature for 1 day. The same paint was applied repeatedly, and the coating characteristics in the case of this overcoat, that is, the recoatability were examined. When the surfactant was not added, repelling was partially observed, but when the surfactant was added, no repelling was observed.

Example 6 Aomori Hiba wood pieces having dimensions of 4 cm × 7 cm × 1 cm thick were prepared, and the entire surface thereof was brushed with the paint 1, Xyladedecor, Auro, Osmokara and non-lot cleaner, respectively. After being applied and cured for one day, the intensity of the fragrance of Aomori Hiba scented through each coated surface was examined by a sensory test.

In the wood piece to which the paint 1 of the present invention was applied, a fragrance of hiba having almost the same intensity as that of the wood piece to which no paint was applied was felt. The wood chips coated with Xyladecor and Non-Lot Clean showed a slightly weaker Hiba scent compared to those coated with the paint 1 of the present invention, but the Hiba scent on the other coated surfaces. Showed little. The wood piece to which the auro was applied felt not the smell of hiba but rather the smell peculiar to this paint.

Thus, it was found that the paint 1 of the present invention, unlike other comparative paints, did not seal the scent of Aomori Hiba, that is, produced a coated surface with good scent permeability.

[0034]

As is apparent from the above description, according to the present invention, wood has excellent moisture absorption / desorption properties inherent to wood, high moisture permeability and scent permeability which do not impair the texture of wood, and water and oil properties. Provided is a water-based paint for wood that can form a coating film that can easily remove dirt by wiping, and when such a paint is used for surface coating of wood for building interior, when the humidity of living space is controlled by wood. At the same time, it is possible to obtain a benefit that a comfortable living environment can be ensured even when the favorable fragrance peculiar to wood is not prevented from being released into the space and the painted surface is hardly stained.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Takagi 1-614 Honcho, Tokamachi, Niigata Prefecture Konsho Co., Ltd. (72) Inventor Yoshimoge Takezawa 1-614, Honmachi, Tokamachi City, Niigata Prefecture Konsho F Term (reference) 4D075 CA33 CA45 DB21 DC02 EA06 EB16 EB42 EC35 4J038 DL031 DL071 GA12 KA09 MA08 MA10 PB05 PC06

Claims (2)

[Claims] 1. A solid content of 4 to 10% by weight, 27 to 34 m
A water-based paint for wood, which is a fluorine-containing silicone resin emulsion having a surface tension of N / m and a pH of 4.5 to 8.5. 2. The water-based paint for wood according to claim 1, wherein the surface tension is adjusted with an acetylene diol-based surfactant.