JP2010174076A - Urethane resin composition for forming coating film and wood plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a urethane resin composition for forming coating films, having an excellent touch and having good design and good staining resistance, and to provide a wood plate using the same. <P>SOLUTION: This urethane resin composition for forming coating films on wood plates comprises an acrylic resin having dimethylsilicone groups represented by formula (1) [wherein, (n) is an integer of 1 to 20] and hydroxyl groups on side chains, an isocyanate resin, and spherical silica. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a urethane resin composition for forming a coating film and a wooden board using the same.

  Conventionally, in order to protect the surface of wooden boards that are susceptible to dirt and scratches, such as flooring and stair treads, and to improve stain resistance, generally with a paint film made of urethane resin composition or photo-curable resin composition Coating is done.

  On the other hand, wooden boards are used in areas where hands touch, such as counters, handrails, doors, storage doors, and areas where feet, such as flooring and stair treads, come into contact with human skin. Many. Therefore, in recent years, there is a demand for a wooden board having a high quality in consideration of a feeling of material, texture, and touch (smooth feeling, slipperiness, soft feeling) in addition to contamination resistance.

  Conventionally, as a method of obtaining a coating film with excellent tactile sensation, blended with natural polyurethane powder such as elastic polyurethane resin fine powder, leather powder with water absorption, collagen powder, chitin powder, chitosan powder, keratin powder, silk powder, etc. It has been proposed to use a resin composition (see Patent Document 1). In addition, a resin composition using a soft and elastic rubber as a binder resin, and a soft urethane resin composition in which acrylic resin beads are blended into a main coating material have been proposed (see Patent Documents 2 and 3).

Japanese Patent Laid-Open No. 8-199483 JP 2003-221947 A Japanese Patent Laid-Open No. 9-253577

  However, although the above-described conventional method can provide a coating film with excellent tactile sensation, the stain resistance is not necessarily sufficient, and it is not suitable for a wood board that requires both design and stain resistance. . That is, it has been difficult to obtain a wood board having excellent tactile sensation and having a design property and a level of stain resistance required for the wood board.

  The present invention has been made in view of the circumstances as described above, and provides a urethane resin composition for forming a coating film having excellent tactile sensation, design properties and stain resistance, and a wood board using the same. The challenge is to do.

  The present invention is characterized by the following in order to solve the above problems.

  1stly, the urethane resin composition for coating-film formation of this invention is a urethane resin composition for coating-film formation for forming a coating film in a wooden board, Comprising: following formula (1):

(Wherein n represents an integer of 1 to 20) and is characterized by containing an acrylic resin, an isocyanate resin, and spherical silica each having a dimethyl silicone group and a hydroxyl group in the side chain.

  2ndly, the content rate of the dimethyl silicone group in an acrylic resin is 0.1-30 mass% in the said 1st urethane-resin composition for coating-film formation, It is characterized by the above-mentioned.

  Thirdly, in the first or second coating film-forming urethane resin composition, the acrylic resin contains at least one fluorine-containing group selected from the following formulas (2) to (5) in the acrylic resin. It is characterized by containing 60 mass%.

  Fourth, in any one of the first to third coating film-forming urethane resin compositions, the average particle size of the spherical silica is 3 to 30 μm.

  Fifth, in the urethane resin composition for forming a coating film according to any one of the first to fourth aspects, the content of the spherical silica is 5 to 40% by mass in solid content ratio with respect to the acrylic resin. .

  Sixth, in the urethane resin composition for forming a coating film according to any one of the first to fifth aspects, the content ratio of the isocyanate resin to the acrylic resin is such that the equivalent ratio of the isocyanate group of the isocyanate resin to the hydroxyl group of the acrylic resin is 0.00. It is the range which becomes 7-1.5.

  7thly, the wood board of this invention has the coating film formed with the urethane resin composition for coating-film formation in any one of the said 1st thru | or 6th.

  According to the first aspect of the invention, by using the acrylic resin having a dimethyl silicone group and a hydroxyl group represented by the formula (1) in the side chain, it is possible to impart stain resistance and a light feeling to the wooden board. it can. By using spherical silica, slipperiness can be controlled, a soft feeling can be imparted, and design properties can be further improved. Thus, it is possible to obtain a wood board that has excellent tactile sensation (smooth feeling, slipperiness, soft feeling), and also has designability and stain resistance.

  According to the said 2nd invention, in addition to the effect of the said 1st invention, the tactile sensation can be improved especially by making the content rate of the dimethyl silicone group in an acrylic resin into said specific range.

  According to the third invention, by containing a specific amount of the fluorine-containing group in the acrylic resin, in addition to the effects of the first and second inventions, the stain resistance and the water / oil repellency are improved. be able to.

  According to the fourth invention, by using the spherical silica having an average particle diameter within the specific range, in addition to the effects of the first to third inventions, the design property, the urethane resin for coating film formation. The handleability of the composition can be improved.

  According to the fifth aspect of the invention, the spherical silica is contained in the specific amount in a solid content ratio with respect to the acrylic resin, so that in addition to the effects of the first to fourth aspects, tactile sensation, designability, and stain resistance are obtained. In particular, it can be improved.

  According to the sixth aspect of the invention, by setting the content ratio of the isocyanate resin to the acrylic resin within the specific range, in addition to the effects of the first to fifth aspects, the adhesiveness to the substrate at room temperature. A coating film excellent in stain resistance can be obtained without lowering.

  According to the seventh aspect of the invention, since the urethane resin composition for coating film formation of the first to sixth aspects of the invention is used, it has an excellent tactile sensation (smooth feeling, slipperiness, soft feeling) Excellent design properties and stain resistance can be exhibited.

  Hereinafter, the present invention will be described in detail.

  The acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain used in the present invention can impart stain resistance and a light feeling (not sticky) to the wooden board, and can also impart water and oil repellency.

  The acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain may be any of a block copolymer, a graft copolymer, and a block / graft copolymer.

  The molecular weight (Mw) of the acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain is preferably 50,000 to 500,000. If the molecular weight is too small, the stain resistance of the coating film by the urethane resin composition for forming a coating film may decrease. When the molecular weight is too large, the viscosity of the urethane resin composition for coating film formation becomes too high, and the handling property may be lowered.

  An acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain is copolymerized by mixing a monomer capable of introducing a dimethyl silicone group represented by the following formula (1) into the side chain at a predetermined ratio. Can be obtained.

(In the formula, n represents an integer of 1 to 20.)
The longer the main chain, the more the dimethyl silicone group can form a coating film with a better soft feeling. However, if the main chain is too long, the coating film may become excessively soft. On the other hand, when the main chain of the dimethyl silicone group is shortened, the hardness of the coating film tends to increase.

  The content rate of the dimethyl silicone group in an acrylic resin is 0.1-30 mass%. If the content of the dimethyl silicone group is too high, it is possible to form a coating film with a smooth and soft feeling, but the coating film tends to be soft and slippery, making it difficult to control the slipperiness. Become. If the content of the dimethyl silicone group is too low, the hardness of the coating film increases, but the smoothness and softness may be lowered.

  In a preferred embodiment of the present invention, an acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain can introduce at least one fluorine-containing group selected from the following formulas (2) to (5) into the main chain. It is synthesized by mixing a monomer with a raw material monomer at a predetermined ratio and copolymerizing it.

  Content of said fluorine-containing group in an acrylic resin becomes like this. Preferably it is 2-60 mass%, More preferably, it is 5-50 mass%. Here, the content of the fluorine-containing group can be measured by a combustion method. If the content is too small, stain resistance and water / oil repellency may not be obtained. When there is too much the said content, compatibility with a solvent or other resin will fall too much, and stain resistance may fall.

  In addition to the structural units represented by the above formulas (1) to (5), the acrylic resin having a dimethylsilicone group and a hydroxyl group in the side chain has other structural units introduced from monomers copolymerizable as raw materials. You may have in the range which does not impair the objective of this invention. Specific examples of the monomer capable of introducing such a structural unit include alkyl vinyl ether, alkyl allyl ether, allyl acid ester, methacrylic acid ester, ethylene, propylene, vinyl acetate and the like.

  The hydroxyl value of the acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain is preferably 40 to 200, more preferably 60 to 150. When the hydroxyl value is too low, the crosslinking density of the coating film is lowered, and the coating film strength may be insufficient. If the hydroxyl value is too high, a hard coating film can be obtained, but the compatibility with the solvent decreases, and the stability of the urethane resin composition for coating film formation may decrease.

  The isocyanate resin used in the present invention acts as a crosslinking agent for an acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain. The isocyanate resin can be cured by polymerization at low temperature with an acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain, and the coating film can be excellent in chemical resistance and water resistance.

  Specific examples of isocyanate resins include prepolymerized monomers such as hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane-4,4-diisocyanate, bis (4-isocyanatocyclohexyl) methane, isophorone diisocyanate, lysine triisocyanate. It can be used in the form of isocyanurate, adduct, biuret or the like.

  The content ratio of the isocyanate resin to the acrylic resin is such that the equivalent ratio of the isocyanate group of the isocyanate resin to the hydroxyl group of the acrylic resin is 0.7 to 1.5. When the equivalent ratio is too small, the reactivity becomes poor and the stain resistance may be lowered. If the equivalent ratio is too large, the water / oil repellency and stain resistance may decrease.

  There is no restriction | limiting in particular as spherical silica used for this invention, For example, a well-known thing can be used, However, Among these, spherical silica which has a high sphericity and a sharp particle size distribution is preferable. High sphericity makes it easy to control slipperiness (non-slip property). In addition, by having a sharp particle size distribution, it is possible to improve the soft feeling, and further, by reducing the amount of particles that do not contribute to matting of the coating film, the transparency can be improved and the design can be improved. .

  The average particle size (volume average particle size) of the spherical silica is preferably 3 to 50 μm, more preferably 5 to 30 μm. If the average particle size is too small, the amount of particles that do not contribute to matting of the coating film increases and the matting effect per unit blending amount decreases, so in order to obtain a matting effect, a large amount must be blended. In some cases, the designability may deteriorate. Moreover, since it becomes easy to aggregate in the urethane resin composition for film formation, dispersion | distribution becomes difficult and the viscosity of the urethane resin composition for film formation may rise. On the other hand, if the average particle size is too large, the appearance of the coating film may become rough. Moreover, since it becomes easy to settle in the urethane resin composition for coating-film formation, handling property may fall.

  The content of spherical silica in the urethane resin composition for forming a coating film is preferably 5 to 40% by mass, more preferably 10 to 40% by mass in terms of the solid content ratio relative to the acrylic resin. If the content is too small, the tactile sensation, the designability, and the stain resistance may decrease. When there is too much the said content, the stain resistance of the coating film by the urethane resin composition for coating-film formation will fall.

  The urethane resin composition for forming a coating film according to the present invention impairs the effects of the present invention in addition to the acrylic resin, isocyanate resin, and spherical silica each having a dimethyl silicone group and a hydroxyl group in the side chain, which are the essential components. Within such a range, fine powder wax, resin beads, polyol resin, and other additives can be blended.

  Specific examples of the resin beads include urethane resin-based, acrylic resin-based, polystyrene resin-based, and silicon resin-based resin beads. Among these, inexpensive and highly resistant to acrylic resin and urethane resin-based resin beads having excellent tactile sensation are preferable.

  The polyol resin can be blended for the purpose of improving the coating film strength such as sliding resistance and scratch resistance of the urethane resin composition for forming a coating film. Specific examples of the polyol resin include a polyester polyol resin and an acrylic polyol resin. Specific examples of the polyester polyol resin include Juliano 2003 (Arakawa Chemical Industries, Ltd.), Juliano 2377 (Arakawa Chemical Industries, Ltd.), Polyure 2593 (Arakawa Chemical Industries, Ltd.), and KL-540B (Arakawa). Chemical Industry Co., Ltd.). Specific examples of the acrylic polyol resin include HITAROID 2525 (manufactured by Hitachi Chemical Co., Ltd.), HITAROID 2520 (manufactured by Hitachi Chemical Co., Ltd.), and the like. The hydroxyl value of the polyol resin is preferably 50 to 200 KOHmg / g from the viewpoint of improving the coating strength.

  Examples of other additives that can be blended in the urethane resin composition for forming a coating film of the present invention include an antifoaming agent, a leveling agent, a dispersant, an anti-settling agent, an ultraviolet absorber, and a heat stabilizer. An appropriate amount of an organic solvent can be blended, but it is desirable to use a so-called TX-free solvent in consideration of workability, safety, environmental pollution, and the like.

  A wood board can be obtained by applying the urethane resin composition for forming a coating film of the present invention to a wooden substrate and then curing the coating film. Specific examples of the wooden board include a flooring material, a stair tread board, a counter, a handrail, a door, a storage door, a fence, a structure, and a joinery frame.

  Veneer sticking may be sufficient as the wooden base material which coats the urethane resin composition for coating film formation, printing sheet sticking may be sufficient, and a solid material may be sufficient as it. In addition, the wood base material can be subjected to conventionally known sealing treatment, coloring treatment, etc. on the surface in advance as long as it does not impair the material feeling and the texture (appearance and feel). In addition, an undercoat paint or an intermediate coat paint can be applied.

  The undercoat paint and the intermediate coat paint can be applied by means generally applied when applying the paint, for example, air spray, airless spray, electrostatic coating, roll coater, and flow coater.

  Specific examples of the undercoat paint and the intermediate coat paint include water-based paints, acrylic lacquers, polyurethane paints, polyester paints, ultraviolet curable epoxy acrylates, urethane acrylates, polyester acrylates, and the like.

The coating amount of the undercoat paint and intermediate coat paint is appropriately adjusted according to the type of wood base material and its processing method, but it is converted to solid content from the viewpoint of not damaging the texture and texture (appearance and feel). And preferably 20 to 80 g / m ² in total, and more preferably 30 to 60 g / m ² . If the coating amount is too small, the durability of the produced wooden board may be lowered. On the other hand, when there is too much the said coating amount, a conduit | pipe may be buried and a feeling of material and a feeling of texture may be impaired.

  The urethane resin composition for forming a coating film of the present invention is a woody substrate by means generally applied when applying a paint, such as air spray, airless spray, electrostatic coating, roll coater, and flow coater. Can be applied to. Among these, air spray is preferably used from the viewpoint of the followability to the shape of the wooden substrate and the coating processing speed.

  In addition, preheating the surface of the woody substrate immediately before coating to 20 to 50 ° C. is effective in forming a good coating film.

The coating amount of the urethane resin composition for forming a coating film on a wooden substrate is preferably 1 to 50 g / m ² , more preferably 3 to 20 g / m ² in terms of solid content. If the coating amount is too small, the stain resistance of the wooden board may be lowered. On the other hand, if the coating amount is too large, the design properties such as the material feeling and texture of the wooden substrate may be impaired.

  After coating the urethane resin composition for forming a coating film on a wooden substrate, it is applied by, for example, room temperature drying, forced drying, baking drying, active energy ray irradiation, etc., depending on the type of the urethane resin composition for coating film formation. The film can be cured.

EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these Examples at all.
1. Preparation of Urethane Resin Composition for Forming Film Each component used in Examples, Comparative Examples, and Reference Examples is as follows.
Acrylic resin KD-270R having a dimethyl silicone group and a hydroxyl group represented by the above formula (1) in the side chain, manufactured by Kanto Denka Kogyo Co., Ltd., hydroxyl value 107.5, solid content 30%
ZX-022H, manufactured by Fuji Chemical Industry Co., Ltd., hydroxyl value 120.0, solid content 45%
MODIPER FS-700, NOF Corporation, hydroxyl value 60.0, solid content 100%
・ Isocyanate resin Takenate D-170HN, manufactured by Takeda Pharmaceutical Co., Ltd., NCO% 22.7%, solid content 100%
-Spherical silica Pyrosphere C-1510, manufactured by Fuji Silysia Chemical Ltd., average particle size 10 μm
・ Uniform silica P-510, manufactured by Mizusawa Chemical Co., Ltd., average particle size 10 μm
Acrylic polyol resin ACRYDIC 52-666BA, manufactured by DIC Corporation, hydroxyl value 147, solid content 50%
The above components were blended in the blending amounts (parts by mass) shown in Table 1, and mixed uniformly to prepare a urethane resin composition for forming a coating film.
2. Manufacture of wood board Using a veneer veneer with a 0.3 mm thick veneer attached to the surface of a 12 mm thick lauan plywood as a wood base material, the colored veneer is coated on the veneer surface with a roll coater. and Engineering, after 1 minute drying at 80 ° C., were in total 70 g / m ² coated with the primer coating and intermediate coating in terms of solid content was dried for 1 minute at 80 ° C..

Next, the urethane resin composition for forming a coating film obtained as described above was applied as a top coat by applying 10 g / m ^{2 in} terms of solid content with an air spray, and kept at room temperature for 1 week to be cured, and the woody material. A wood board having a coating film formed of a urethane resin composition for forming a coating film on a substrate was obtained.

The following evaluation was performed on the wood board obtained as described above.
[Designability (appearance)]
The gloss value was measured with GM-60 (manufactured by Konica Minolta). Measurement conditions were an incident angle of 60 degrees and a reflection angle of 60 degrees.
[Contamination resistance]
(Curry dyeing resistance test)
A curry powder (made by Sakai Subby Foods Co., Ltd.) dissolved in hot water (concentration: 10%) was dropped onto the wooden board coating, and the watch was put on a watch glass and kept for 24 hours to prevent the water from evaporating. After 24 hours, it was washed with water, and the Lab value of the surface before and after the test was measured using a color difference meter (CM2600: manufactured by Konica Minolta Sensing Co., Ltd.) to calculate the color difference ΔE. And it evaluated by the following reference | standard.
○: ΔE ≦ 3.0
Δ: 3.0 <ΔE ≦ 5.0
×: 5.0 <ΔE
(Alkaline resistance test)
A 5% aqueous sodium hydroxide solution was dropped onto the wooden board coating, and the watch was put on a watch glass to keep the water from evaporating, and held for 24 hours. After 24 hours, it was washed with water and evaluated according to the following criteria from the appearance.
○: No appearance abnormality △: Some whitening of the coating film ×: Whitening of the coating film
(Acid resistance test)
A 1% aqueous solution of hydrochloric acid was dropped onto the wooden board coating, and a watch glass was placed over the glass so that the water did not evaporate. After 24 hours, it was washed with water and evaluated according to the following criteria from the appearance.
○: No appearance abnormality △: Some whitening of the coating film ×: Whitening of the coating film
[Feel]
(Slippery)
In accordance with the “Slip test method for flooring (diagonal tension type)” defined in the JIS A5705 appendix, the “slip resistance coefficient (CSR)” when walking with bare feet was used for evaluation according to the following criteria.
○: Slip resistance coefficient is in the range of 0.45 to 0.9 ×: Slip resistance coefficient is less than 0.45 or more than 0.9
(Feeling light)
The tactile sensation when walking with the bare feet on the film-formed surface of the wooden board was evaluated according to the following criteria.
○: I felt a good feeling when I walked.
Δ: A slight sticky feeling was felt during walking. ×: A sticky feeling was felt during walking.
(Soft feeling)
The tactile sensation when walking with the bare feet on the film-formed surface of the wooden board was evaluated according to the following criteria.
○: A good soft feeling was felt during walking.
Δ: A feeling of roughness and hardness was felt during walking. ×: A feeling of roughness and hardness was felt during walking.

  The evaluation results are shown in Table 1.

  From Table 1, Example 1 in which a coating film was formed on a wooden substrate using a urethane resin composition for coating film formation containing an acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain, an isocyanate resin, and spherical silica. In -5, in addition to having excellent tactile sensation (smooth feeling, slipperiness, soft feeling), it also had design properties and stain resistance.

  On the other hand, in Comparative Example 1 in which irregular-shaped silica was blended without blending spherical silica, slipperiness and softness were reduced among the tactile sensations.

  In Comparative Example 2 in which an acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain was not blended, the soft feeling and soft feeling of the tactile sensation were lowered.

  In Comparative Example 3 in which the spherical silica was not blended, the slipperiness and softness of the tactile sensation were lowered, and the design property was also greatly lowered.

  Further, as shown in Reference Examples 1 and 2, when the amount of spherical silica is excessive or too small in the solid content ratio relative to the acrylic resin having a dimethylsilicone group and a hydroxyl group in the side chain, contamination resistance, There was a tendency for the tactile sensation and the design to decrease. From such a point, the preferable content of the spherical silica is 5 to 40% by mass in a solid content ratio with respect to the acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain.

  In addition, as shown in Reference Example 3, when the equivalent ratio of the isocyanate group of the isocyanate resin to the hydroxyl group of the acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain is excessive or excessive, the stain resistance is reduced. There was a trend. From such a point, the preferable content ratio of the isocyanate resin with respect to the acrylic resin is a range in which the equivalent ratio of the isocyanate group of the isocyanate resin to the hydroxyl group of the acrylic resin is 0.7 to 1.5.

Claims (7)

A urethane resin composition for coating film formation for forming a coating film on a wooden board, the following formula (1):

(Wherein n represents an integer of 1 to 20) A coating film comprising an acrylic resin having a dimethyl silicone group and a hydroxyl group in the side chain, an isocyanate resin, and spherical silica Urethane resin composition.   The urethane resin composition for forming a coating film according to claim 1, wherein the content of dimethylsilicone groups in the acrylic resin is 0.1 to 30% by mass. The acrylic resin contains 2 to 60% by mass of at least one fluorine-containing group selected from the following formulas (2) to (5) in the acrylic resin. Urethane resin composition.

  4. The urethane resin composition for forming a coating film according to claim 1, wherein the spherical silica has an average particle size of 3 to 30 μm.   The urethane resin composition for forming a coating film according to any one of claims 1 to 4, wherein the content of the spherical silica is 5 to 40% by mass in terms of a solid content ratio relative to the acrylic resin.   The content ratio of the isocyanate resin to the acrylic resin is in a range where the equivalent ratio of the isocyanate group of the isocyanate resin to the hydroxyl group of the acrylic resin is in a range of 0.7 to 1.5. The urethane resin composition for coating film formation as described in 2.   A wood board comprising a coating film formed of the urethane resin composition for forming a coating film according to any one of claims 1 to 6.