JPH0564769A - Method for repairing and sealing surface of wood board - Google Patents

Abstract

PURPOSE:To repair and seal the surface of a wood board with putty composed of a mixture of a main agent consisting of a solid component and a formaldehyde resin and a curing agent, not generating foaming, grain depression and a crack and excellent in flocculation force, water resistance and durability and curing the putty layer. CONSTITUTION:The surface of a wood board such as plywood or laminated lumber having a recessed surface such as a conduit, a crack, a haircrack or a pinhole is coated with putty to be repaired and sealed. At this time, putty composed of a mixture of a main agent containing 78-85% of a solid component (e.g. clay) with formaldehyde resin content of 13-20% and a curing agent (e.g. ammonium chloride) is applied to the wood board to be cured. As a result, the fault possessed by the formaldehyde resin to the repairing and sealing use of the surface of the wood board can be improved and the putty not generating foaming, grain depression and a crack and excellent in flocculation force, water resistance and durability can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface repairing / sealing method for wooden boards.

[0002]

2. Description of the Related Art On the surface of plywood and laminated wood, there are conduits, barbs, pinholes, cracks caused by knot holes and processing, fine hair cracks, planer knife markers on the surface of wood. -There are various unevennesses such as black and white, press marks and the like. Therefore, for products classified by appearance,
Due to its defects, it is regarded as a low grade product, and when paper, veneer, plastic sheet, etc. are secondarily adhered to the surface of the product, the effects of these defects are There are many cases that appear on the surface of and cause problems. For example,
When sticking an extremely thin paper or veneer of several tens to several hundreds of microns on the surface of plywood, cracks, knot holes, and sometimes even pipes after bonding or painting adversely affect the surface and damage the aesthetics. It may be a cause.

Conventionally, as a means for covering these defects, a method of applying the putty using a putty made of an acrylic resin, an epoxy resin, a urethane resin or the like has been adopted. Since the drying is mainly based on the volatilization of water and organic solvents, so-called "eye loss" occurs, in which the filling part collapses after curing, or conversely, foaming and filling with a lot of bubbles in the sanding process in the post process. However, there are problems that the mechanical strength is lowered, that it takes a long time to dry, and that the workability is poor because it is insoluble in water.

On the other hand, formaldehyde resins are also sometimes used for this purpose. Formaldehyde resin is
It has good adhesion to wood, good workability such as viscosity stability and water solubility of the prepared paste solution, and its major advantages are mass production, low cost and economical. is there. However, in general, when a formaldehyde resin, such as a urea resin, is heat-cured, it foams due to water in the system, becomes a brittle sponge after curing, and also contracts due to water.
It was considered to be completely unsuitable for this application because of cracking due to its low durability originally.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides advantages of the formaldehyde-based resin having good adhesion to wood, good workability such as stability of viscosity of prepared paste solution and water solubility, and economical efficiency. The present invention aims to provide an improved technique for the use by utilizing the above.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to conduits, cracks,
When applying putty to the surface of wooden boards such as plywood having a concave surface such as hair cracks and pinholes and laminated wood, and repairing and sealing the surface, (1) the solid content is 78 to 85. %
Then, a putty consisting of a mixture of two kinds of a main agent containing 13 to 20% of formaldehyde resin and (2) a curing agent is applied therein, and the putty is cured. It is related to the surface repair / sealing method of a class.

In the present invention, by the above means, the proportion of the resin in the main component of the putty is reduced to such an extent that curability and water resistance are not impaired, while the main component comprises the resin and the filler. By devising the solid content in the system and increasing the solid content by the filler, it has become possible to improve the above-mentioned drawbacks of the formaldehyde resin. That is, upon completion of the present invention, the inventors of the present invention have made earnest studies and found that when the solid content in the system is less than 78%, shrinkage and accompanying cracking are observed after curing. Therefore, in order to eliminate these, it is necessary to make the solid content higher than that, but too high a solid content causes inconvenience, and further, the content rate of the formaldehyde resin in it (hereinafter referred to as resin rate). Sometimes
It was also found to have a great influence. That is, the formaldehyde resin produces water by a condensation reaction in the process of curing. This water causes foaming at the time of thermosetting as well as water existing in the system from the time of preparation, and conversely volatilizes in the curing process to cause shrinkage (so-called eye loss) or cracking of the cured product. However, it was also found that if the resin ratio is greatly reduced in order to suppress this phenomenon, the cohesive force as a binder is lacking, and sufficient strength and water resistance of the putty cannot be obtained. Therefore, as a result of further diligent studies, the present inventors have determined that the solid content is 78 to 85%, and the resin ratio therein is 13%.
By setting the content to ˜20%, the foaming as described above,
It has become possible to develop putty that has no cohesiveness, water resistance, and durability with no visible skin loss or cracking.

The constitution of the present invention will be supplemented below. The main agent used in the present invention comprises a formaldehyde resin and a filler. The formaldehyde resin referred to in the present invention may be one generally used in the wood industry, and one or more chemical species of urea (A), melamine (B) and phenol (C). And a formaldehyde co-condensate, which has a molar ratio that influences the properties, that is, one or more chemical species selected from urea (A), melamine (B), and phenol (C) selected. The mole ratio of formaldehyde (F) to the mole number (F / A, B,
C) is preferably 1.3 to 2.5. The resin is thiourea, benzoguanamine, tannin, rhizonine, crezo-
It is also possible to denature it with resulcin, resorcin, etc.

Examples of the above-mentioned filler include inorganic fillers such as clay, calcium carbonate, calcium sulfate, titanium oxide, bentonite and dolomite, or wood flour, wheat flour, rice flour, soybean flour, coconut shell flour, coke A vegetable filler such as starch can be used. It is also possible to mix an appropriate amount of a flexibility-imparting agent such as polyvinyl acetate resin emulsion, ethylene-vinyl acetate resin emulsion, styrene rubber latex, nitrile rubber latex or the like with the base material in order to impart flexibility to the filler. is there.

In the present invention, the solid content of the main component is 78 to
It is necessary that the content of the formaldehyde-based resin is 85 wt% and that the content of the formaldehyde resin is in the range of 13 to 20 wt%. If the solid content of the system is less than 78 wt%, shrinkage and accompanying cracking will occur after curing, while the solid content of the system will be 85 wt%.
When it exceeds%, the cohesive force as a binder is insufficient, and it is difficult to obtain sufficient strength and water resistance of the putty. These solid contents need to be balanced with the content rate (resin rate) of the formaldehyde resin in the solid content,
When the proportion of the formaldehyde resin in the base resin is less than 13 wt%, the cohesive force as a binder is lacking, and it is difficult to obtain sufficient strength and water resistance of the putty. On the other hand, when it exceeds 20 wt%, foaming during thermosetting occurs. Or conversely, moisture is likely to evaporate during the curing process to cause shrinkage (so-called eye loss) or cracking of the cured product.

The putty is used as a mixture of two kinds of (1) a main agent containing a formaldehyde resin and (2) a curing agent. Examples of the curing agent include ammonium salts such as ammonium chloride, ammonium sulfate, and ammonium acetate, which are generally known as curing accelerators for formaldehyde resins, acidic salts such as aluminum chloride and aluminum sulfate, inorganic salts such as hydrochloric acid and sulfuric acid, and acetic acid. , Organic acids such as oxalic acid and paratoluene sulfonic acid may be used alone or in combination of two or more as a single substance or as a diluting solution or an aqueous solution. When the above-mentioned flexibility-imparting agent is mixed, or when the above-mentioned curing agent is used as a powder, there is no problem, but when it is used as a liquid, the viscosity is lowered when mixed with the main agent, and the wood is filled. Since it sometimes flows and may appear as a thin layer after curing, in order to solve this, polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, cone star are added to the curing liquid. Soybean flour, soybean flour, etc.
It is good to make a strike.

In the present invention, after applying the putty, the putty is cured. The curing is accelerated by heating, but it is recommended to use a hot air type dryer or a reverse infrared type dryer. An ambient temperature of 80 to 200 ° C is suitable.

[0013]

EXAMPLES Next, the present invention will be explained based on examples. Example 1. (1) Preparation of main agent Melamine-urea resin (trade name: Oshika Resin PWP-
520C / Oshika Shinko Co., Ltd., solid content 70%) 100 parts by weight, 42 parts by weight of water and 3 parts by weight of dispersant are added and stirred,
Kure-265 parts by weight were gradually dispersed. (2) Preparation of curing agent Ammonium chloride (20 parts by weight) was dissolved in water (80 parts by weight), and 10 parts by weight of cone starch was gradually added and dispersed. The mixture was heated to 70 to 80 ° C. and gelatinized to obtain a hardener paste. The weight ratio of the main component and the curing agent is 100:
Mix with 5 and apply evenly with a spatula on a 9 mm plywood having conduits, cracks, hair cracks, pinholes, etc., 80-1
It was completely cured in a 50 ° C. oven.

Comparative Example 1. (1) Preparation of main agent Urea resin adhesive (trade name: Oshika Resin # 104 / Oshika Shinko Co., Ltd., solid content 70%) 100 parts by weight of modified polyvinyl acetate resin adhesive (trade name: Multibond # 530)
/ Oshika Shinko Co., Ltd., solid content 55%) 20 parts by weight, dispersant 1
By weight, 80 parts by weight of Kle was dispersed with stirring. (2) Preparation of curing agent Prepared by dissolving 40 parts by weight of ammonium sulfate in 60 parts by weight of water. The weight ratio of the main agent and the curing agent is 100:
The mixture was mixed with 2.5 and applied and cured in the same manner as in Example 1.

Comparative Example 2. (1) Preparation of main agent 30 parts by weight of urea resin adhesive (trade name: Oshika Resin # 104 / same as above), 70 parts by weight of melamine resin adhesive (product name: Oshika Resin M34 / as above, solid content 60%), modified poly Vinyl acetate resin adhesive (Product name: Multibond #
530 / same as above) 20 parts by weight, water 50 parts by weight and dispersant 1 part by weight were added, and while stirring, 120 parts by weight of the clay was gradually dispersed. (2) Preparation of curing agent Prepared by dissolving 20 parts by weight of ammonium chloride in water 80. The above main agent and curing agent were mixed at a weight ratio of 100: 5, and applied and cured in the same manner as in Example 1.

Table 1 shows the results of performance evaluation in these examples and comparative examples.

[0017]

[Table 1]

[0018]

According to the present invention, the advantage of the formaldehyde resin having good adhesion to wood, workability, and economy can be utilized, and concave surfaces such as conduits, cracks, hair cracks and pinholes can be obtained. It is possible to repair the surface of wooden boards such as plywood and laminated wood, and to improve the drawbacks of formaldehyde resins for sealing applications, and no foaming, blinding or cracking is observed, and cohesive strength. ,
We succeeded in developing putty with excellent water resistance and durability.

Claims (2)

[Claims] Claims: 1. When applying putty to the surface of a wooden board such as a conduit, a crack, a hair crack, a plywood having a concave surface such as a pinhole, a laminated lumber, etc.
(1) Solid content is 78 to 85%, of which 13 to 20%
And a main agent containing the formaldehyde resin of (2)
A surface repair / sealing method for wooden boards, which comprises applying a putty composed of a mixture of two kinds of curing agents and curing the putty. 2. The surface repair of the wooden board according to claim 1, wherein the main component is a formaldehyde resin and a filler.
How to stop.