JPH04288379A - Method for filling void of plywood - Google Patents

Abstract

PURPOSE:To prevent water, etc., from being sucked by the vessels of wood in plywood and fill the voids of plywood by coating plywood with a coating material composed mainly of a specified unsaturated polyester resin, a polyisocyanate compound, and a plurality of other substances at a specified ratio. CONSTITUTION:Plywood is coated with a coating material composed mainly of an unsaturated polyester resin (A) having at least two unsaturated double bonds and at least one OH group in the molecule (e.g. Goselac 400, a product of Nihon Synthetic Chemical Co.), a polyisocyanate compound (B) (e.g. tolylene diisocyanate), an extender pigment (e.g. talc), an organic peroxide catalyst (e.g. methyl ethyl ketone peroxide), a reactive diluent (e.g. styrene), and a drying accelerator (e.g. cobalt naphthenate) wherein the equivalent ratio of the OH group of component A to the NCO group of component B is 0.3 to 3.0.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for sealing wood plywood, which consists of applying a specific paint, and more specifically, to give aesthetic appearance to wood plywood and further prevent water and other substances from being absorbed by wood conduits. This invention relates to a sealing method for improving the durability of wood plywood.

0002

BACKGROUND OF THE INVENTION In recent years, wood plywood has come into widespread use as building materials and other materials from the standpoint of protecting wood resources. However, although wood plywood serves the purpose of resource conservation, it has more concavities such as knotholes than natural wood boards, and is unsatisfactory in terms of aesthetics. In addition, there were also drawbacks such as poor durability and poor appearance due to the suction of moisture and other substances by the conduit of the wood itself.

[0003] In general, the following methods (a) and (b) have been known for smoothing the surface of wood plywood having recesses such as knotholes. (b) A method of cutting out the area around the wood plywood including the knotholes and other recesses, and then inserting a piece of another wood plywood of the same shape. (B) A method of applying unsaturated polyester resin paint or As a method of embedding the polyurethane resin paint and then curing it, and as a method of preventing suction by the wood conduit, the following method (c) has been used. (c) A method of mixing abrasive powder with water or oil and rubbing it into the wood plywood with a piece of cloth.

0004

[Problem to be solved by the invention] However, the above (
Method b) must be carried out manually and requires a lot of labor, so it is not a preferable method. On the other hand, in the method (b) of embedding the paint, if an unsaturated polyester resin paint is used, it has the advantage of being easy to apply a thick film and making it possible to smooth the surface with one application; Since the resulting resin is rigid, it has the disadvantage of causing cracks when nails are driven into the embedded area. In addition, in the case of polyurethane resin paint, unlike unsaturated polyester resin paint, it is difficult to apply a thick film, so at least
It is necessary to apply three or more times, which is time-consuming, and the curing speed of the paint itself is slow, so if you pile up the wood plywood immediately after applying it, the wood plywood will cause blocking, making it impossible to stack, and the paint will harden. There were disadvantages such as the need for a large drying area.

On the other hand, the method (c) for sealing wood conduits is as follows:
Originally, it had to be done manually,
Normally, this sealing method (c) is not carried out alone, and there is the inconvenience that methods (a), (b), etc. described above must be carried out in advance.

[0006]

[Means for Solving the Problems] The present inventors have solved the problems of these conventional sealing methods for wood plywood, and have been able to fill in and repair recesses such as knot holes in wood plywood by simply applying it once. , a method for sealing wood plywood that can simultaneously prevent suction from wood pipes, can be applied in a thick film, cures quickly, has excellent adhesion, flexibility, and smoothness, and does not lose its thickness during curing. As a result of extensive research with the aim of achieving this goal, it was discovered that this goal could be achieved by applying a sealing paint made by combining specific ingredients shown in (A) to (F) below. , we have completed the present invention.

That is, the present invention provides the following components (A) to
This is a method for sealing wood plywood, which consists of applying a paint containing (F) as the main component. (A) Unsaturated polyester resin containing two or more unsaturated double bonds and one or more hydroxyl groups in the molecule (B) Polyisocyanate compound (C) Extender pigment (D) Organic peroxide catalyst (E) Reaction (F) Drying accelerator However, in this case, the component (A) for the hydroxyl group in component (A)
The equivalent ratio of isocyanate groups in B) is from 0.3 to 3.0.

[0008]

[Structure of the Invention] The unsaturated polyester resin as component (A) used in the present invention is a resin containing two or more unsaturated double bonds and one or more hydroxyl group in the molecule. The unsaturated polyester resin can be obtained by condensation polymerization of an unsaturated dibasic acid and a polyhydric alcohol.

[0009] In this case, as the unsaturated dibasic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, or their acid anhydrides are used alone or in combination of two or more. be able to. In addition, polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol, hexylene glycol, hydrogenated bisphenol A, 2, Dihydric alcohols such as 2-bis(4-hydroxyethoxyphenyl)propane, glycerin, trimethylolethane, trimethylolpropane, etc. can be used alone or in combination of two or more.

[0010] As a method for preparing the unsaturated polyester resin of component (A), the above-mentioned unsaturated dibasic acid or acid anhydride thereof and a polyhydric alcohol are mixed in a mixture of 20/80 to 70/
It can be obtained by carrying out an esterification reaction in a conventional manner at a weight ratio of 30.

Similarly, the polyisocyanate compound as component (B) used in the present invention includes, for example, tolylene diisocyanate, m-xylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and decamers of these or less. In addition to polymers, examples include reaction products of these polyisocyanate compounds with water, polyhydric alcohols such as ethylene glycol, propylene glycol, and trimethylolpropane, and these can be used alone or in combination of two or more. can be used. and,
Each of these compounds has two or three isocyanate groups per molecule.

The amount of such polyisocyanate compound to be used is based on 1 equivalent of hydroxyl group contained in component (A).
Isocyanate group in polyisocyanate compound 0.3
The ratio should be 3.0 to 3.0 equivalents, particularly preferably 0.5 to 2.0 equivalents. If the equivalent ratio of isocyanate groups is less than 0.3, there is a risk that the cure of the coating film will be slow and blocking will occur, or that the cured coating film will be brittle and may crack when nailed.
If it exceeds 3.0, the pot life of the paint itself will be shortened and gelation will likely occur.

Extender pigments as component (C) used in the present invention include, for example, kaolin, barium sulfate, calcium carbonate, talc, silica, alumina, hydrated alumina, hydrated magnesium, mica, barium carbonate, zirconia,
Examples include silicon nitride, boron nitride, aluminum nitride, and clay, and these can be used alone or in combination of two or more.

[0014] The blending ratio of the extender pigment in the paint is from 15 to
70% by weight, preferably 25-60% by weight. If the blending ratio is less than 15% by weight, thinning occurs during curing of the coating film and the smoothness of the coating film is impaired, and if it exceeds 70% by weight, the properties of the coating are poor and the coating workability and film-forming properties are impaired.

The organic peroxide catalyst used as component (D) in the present invention includes, for example, ketone peroxide, peroxyketal, hydroperoxide, peroxydicarbonate, benzoyl peroxide, methyl ethyl ketone peroxide, peroxy ester, etc. alone. Alternatively, two or more types can be used in combination.

The proportion of the organic peroxide catalyst in the paint is 0.1 to 3.0% by weight, preferably 0.3 to 1.0% by weight. If the blending ratio is less than 0.1% by weight, the curing of the coating film in winter will be insufficient, and even if it exceeds 3.0% by weight, no further effect can be expected, and painting workability and film-forming properties will be affected. This is not desirable because it causes

The reactive diluent (Component (E)) used in the present invention is a component that adjusts the viscosity of the paint during coating and also polymerizes itself to become a coating film element. They can be used alone or in combination. The viscosity during painting is 30 to 1000 poise (20
℃) is preferably 50 to 800 poise (at 20℃), and therefore the proportion of its use in the paint should be 3 to 800 poise (at 20℃).
It may be used within a range of 40% by weight.

Examples of the drying accelerator used as component (F) in the present invention include cobalt naphthenate, manganese naphthenate, lead naphthenate, dimethylaniline, and diethylaniline, which may be used alone or in combination of two kinds. A mixture of the above can be used.

In the paint of the present invention, in addition to the above-mentioned essential paint components (A) to (F), insect repellents, coloring pigments, other resins, additives, solvents, etc. may be added as necessary. can. It is known that boric acid is effective as an insect repellent, especially for termite control when wood plywood is used for houses, etc., but in the present invention, boric acid is also used by mixing it with paint. It is possible to do so. In this case, the amount of boric acid blended into the paint is 1 to 50% by weight.
It can be blended within the following range. As the coloring pigment, pigments normally used in paints can be used. As other resins, for example, acrylic resins, polyester resins, phenol resins, cellulose, water-soluble resins, and other color vehicles commonly used in paints may be mixed. In this case, the blending amount should be within 70 parts by weight per 100 parts by weight of the total amount of components (A) and (B).

[0020] Examples of additives include photopolymerization initiators,
Antioxidants and the like can be added. By blending the photopolymerization initiator into a coating material, it becomes possible to cure the coating film by irradiating it with ultraviolet rays, electron beams, etc. at the time of curing the coating film. Such photopolymerization initiators include benzophenone, benzyl, benzyl methyl ketal, 4,4
'-Bisdiethylaminobenzophenone, 2,2-diethoxyacetophenone, thioxanthone, alkylanthraquinone, 2,2-dimethoxy-2-phenylacetophenone, α-acyloxime ester, 1-phenyl-
1,2-propanedione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-benzoyl)oxime, chlorinated acetodenone derivative, 2-hydroxy-2-methylpropylene Piophenone, 4'-isopropyl-2-hydroxy-2-methylpropiophenone, etc. can be used alone or in combination of two or more. Further, when curing the coating film surface due to air oxidation, an antioxidant can be added to the coating material for the purpose of preventing the curing failure. As the antioxidant for this purpose, allyl glycidyl ether, glycerin diether, etc. can be used.

As the solvent, solutions commonly used in paints can be used. The proportion of the solvent used should be 10% by weight or less in the paint, and in consideration of thinning during curing, it is preferable to use a small amount of solvent.

The paint of the present invention contains the above-mentioned components (A) and (C).
), (E), and (F), a curing agent consisting of component (B), and a polymerization catalyst consisting of component (D). After mixing in a predetermined ratio, it is applied for painting. An example of the preparation method is shown below, but the method is not limited thereto. First, the components (A), (C), (E
), (F) and other additives if necessary are mixed and dispersed using a sand mill or the like to prepare a main ingredient. Next, the polyisocyanate compound of component (B) as a curing agent is added to the main ingredient as it is or dissolved in an ester solvent, and further component (D) is added as a polymerization catalyst.
) is added as is, and mixed thoroughly to form a paint.

The usual method for applying this paint to wood plywood is to place the wood plywood horizontally, pour the paint prepared above over the entire surface, and then rub the entire surface with a knife coater to make it smooth. Stacking is possible if left at room temperature for 5 minutes after application. In addition, when applying to the end surface of wood plywood, airless painting, hand-blown painting, brush painting, etc. can be used as necessary.

[0024]

[Action] The coating film curing effect of the paint of the present invention is based on the components (
A), (B) urethane reaction and components (A), (
The polymerization reactions of unsaturated bonds in B) and (E) proceed in parallel, resulting in curing at room temperature. In addition, if a shorter curing time is required, irradiation with ultraviolet rays (usually by adding a photopolymerization initiator to the component (A)) or curing for less than 10 minutes at 100°C or less may be necessary. It is also possible to perform forced drying.

[0025]

Effects of the Invention: The paint of the present invention does not contain a solvent or contains only a small amount of solvent, and it also contains an extender pigment, so it does not cause thinning during curing, especially in the concave areas of wood plywood. Even after curing, the same smoothness as when applied can be maintained. In addition, the cured coating film contains component (A) and (
Because it takes into account curing by urethane reaction with B),
It has a moderate amount of flexibility and will not crack when nailed. Furthermore, by incorporating boric acid, it can also be used for wood plywood for termite prevention purposes. As described above, the wood plywood sealed by the method of the present invention using the wood plywood sealing paint of the present invention can simultaneously and easily prevent suction of wood conduits and fill in surface recesses. It has a smooth finished surface and does not crack when nailed, making it very useful for the development of the wood plywood industry. Furthermore, the wood plywood sealing paint of the present invention is
It also has excellent performance as a paint for formwork (concrete panels) when curing concrete, and can be used without problems.

[0026]

[Examples and Comparative Examples] The present invention will be explained in more detail below using Examples and Comparative Examples. Examples 1 to 10, Comparative Examples 1 to 3 <Preparation of coating sample> According to the formulation shown in Table 1, all components of the main ingredient were first mixed, and the particle size was 40 μm using a sand mill.
The main ingredients of each paint of Examples and Comparative Examples were prepared by dispersing the following amounts. Next, the polyisocyanate compound of component (B) shown in Table 1 was added as a curing agent to the main ingredient, and the polyisocyanate compound shown in Table 1 was further added as a polymerization catalyst.
The organic peroxide catalyst shown in Component (D) was added as is and thoroughly mixed to prepare a paint. A styrene monomer was further added to this paint to dilute it to a viscosity of 150 poise (20°C) to obtain a coated sample for use in the test.

[0027]

[Table 1] (Note) *1 Nippon Gosei Kagaku Kogyo Co., Ltd.: Unsaturated polyester resin solution *2 Sumitomo Bayer Urethane Co., Ltd.: Unsaturated polyester resin solution *3 Matsumura Sangyo Co., Ltd.: Talc (average particle size 1 ~15
μm) *4 Sankyo Seifun Co., Ltd.: Calcium carbonate (average particle size 1 to 10 μm) *5 Nippon Mining Co., Ltd.: Cobalt naphthenate (metal content 5% by weight) *6 Sumitomo Bayer Urethane Co., Ltd.: Tolylene diisocyanate Polymer solution *7 Nippon Polyurethane Industries Co., Ltd.: Polymethylene polyphenyl polyisocyanate *8 Nippon Oil & Fats Co., Ltd.: Methyl ethyl ketone peroxide

[0028] This coated sample was first tested for pot life of the paint according to the following test method. Also,
Separately, prepare a softwood plywood board with knot holes measuring 300 x 300 x 15 mm (depth of the recess 1.5 mm) as a plate to be coated. After applying the coating sample to the entire surface of the board, use a knife coater to coat the entire surface including the knot holes and the recess. I squeezed it and smoothed it out. This coated board was tested for blocking properties according to the test method below, and after the coated board was dried at room temperature for 24 hours after the coating sample was applied, the appearance of the coating was determined according to the test method below. A crack test was conducted after nailing. These results are shown in Table 2.

<Test method> (1) Pot life: The coated sample obtained as described above was allowed to stand in a room at 20°C, and those that did not gel even after 30 minutes were passed (○). , Those that turned into gel were judged as failed (x). (2) Blocking property: Coated plate 10 coated with coating sample
After drying the sheets at room temperature for 1 hour, stack them and place 2
A weight of 0 kg was placed on the sample and the sample was allowed to stand for 24 hours. Those that did not cause blocking were evaluated as passed (○), and those that caused blocking were evaluated as failed (×).

(3) Appearance of coating film: Visually observe the coated surface of the plate after drying at room temperature for 24 hours, and those with good smoothness without dents are judged as passing (○), and those with dents are judged as failing. It was marked as passed (×). (4) Cracks after nailing: After drying at room temperature for 24 hours, nails with a diameter of 2 mm are driven into the knot holes of the plate to be coated. Those with no cracks are marked as passing (○), and those with cracks are marked as failing (x). And so.

[0031]

[Table 2] In addition to these tests, the insect repellent efficacy of Examples 2, 4, 7, and 10 and Comparative Examples 2 and 3,
A test was conducted on the coated board after drying for a period of time. The test method was to leave each coated board in the vicinity of a termite nest for one year and observe termite damage, but no termite damage was observed on any of the coated boards.

As is clear from the results in Table 2 above, Comparative Examples 1 to 3 are unsatisfactory in at least one test item, but Examples 1 to 10 are unsatisfactory in any of the test items. It is clear that the method of the present invention is superior as it also shows very good results.

Claims (1)

[Claims] (1) A method for sealing wood plywood comprising applying a paint containing the following components (A) to (F) as main components. (A) Unsaturated polyester resin containing two or more unsaturated double bonds and one or more hydroxyl groups in the molecule (B) Polyisocyanate compound (C) Extender pigment (D) Organic peroxide catalyst (E) Reaction (F) drying accelerator However, the equivalent ratio of the isocyanate groups in component (B) to the hydroxyl groups in component (A) is from 0.3 to 3.0.