JPH05170858A - Resin composition for repair - Google Patents

Abstract

PURPOSE:To prepare the title compsn. suitable esp. for repairing a conifer, free from blistering, and excellent in adhesive properties by adding a plasticizer and a specific filler to a resin compsn. which is usually used for repairing a wood material and comprises an active hydrogen compd., a polyisocyanate compd., and a filler. CONSTITUTION:A plasticizer (e.g. dibutyl phthalate) and at least one water- trapping filler selected from the group consisting of MgO, CaO, and BaO are added to a resin compsn. which is usually used for repairing a wood material and comprises an active hydrogen compd. (e.g. a polyether polyol prepd. by the addition reaction of ethylene oxide with bisphenol A), a polyisocyanate compd. (e.g. a polymeric MDI), and a filler (e.g. CaCO3 and silica).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for repairing wood plywood and the like, and more particularly to a urethane resin composition suitable for repairing softwood.

[0002]

2. Description of the Related Art Conventionally, a resin composition containing a filler has been used to repair wood materials such as wood, plywood or veneer for plywood. As the resin, an elastomeric thermoplastic resin, a thermoplastic resin blended with an amino resin or the like,
Urethane resin is used. Although urethane resin is expensive, it is used for relatively expensive wood because it has excellent adhesion to wood. In recent years, the demand for coniferous trees is increasing due to the shortage of South Sea trees, but coniferous trees have a lot of fungus holes, and in the processing of veneer for plywood, it is difficult to perform smooth cutting because the material is hard, so it is difficult to repair. Often needed. For this purpose, urethane resin having a large adhesive force is preferably used.

A resin composition for repairing wood materials is required not to expand or contract when dried or cured,
Further, it is important that the wood material does not warp after curing and that the resin composition does not crack. The urethane resin composition has a drawback that it foams and expands due to the composition or wood or moisture in the air, so-called "blister" occurs, which further causes a decrease in adhesive strength, and further the softness is not sufficient. Warpage often occurs.

[0004]

SUMMARY OF THE INVENTION The present invention has been completed as a result of various studies to solve the above-mentioned drawbacks of urethane resin-based repairing materials for wood materials, and is particularly suitable for repairing softwood. A resin composition is provided.

[0005]

The present invention provides a resin composition for repairing wood materials, which comprises (a) an active hydrogen-containing compound, (b) a polyisocyanate compound, and (c) a filler as essential components,
Further, the resin composition for repairing wood materials is characterized in that (d) a plasticizer and (e) at least one of magnesium oxide, calcium oxide and barium oxide are blended as a filler for trapping water.

Used in the resin composition of the present invention (a)
As the active hydrogen-containing compound, a compound having two or more hydroxyl groups, amino groups, active methylene groups and the like can be used, but various polyester polyols, polyether polyols, acrylic polyols, urethane polyols, epoxy polyols, terminal hydroxyl polybutadienes. , Polycarbonate polyol, ethylene glycol, butylene glycol, diethylene glycol, neopentyl glycol, trimethylolethane, trimethylolpropane, glycerin, hexanetriol, castor oil, etc. are generally used alone or in combination.

The polyisocyanate compound (b) in the present invention has two or more isocyanate groups in the molecule. For example, hexamethylene diisocyanate, 2,4-diisocyanate-1-methylcyclohexane, 2,6-diisocyanate-1-methylcyclohexane, diisocyanate cyclobutane, tetramethylene diisocyanate, o-, m- and p-xylylene diisocyanate, dicyclohexylmethane diisocyanate. , Dimethyldicyclohexylmethane diisocyanate, and aliphatic or cycloaliphatic diisocyanates such as lysine diisocyanate, alstel, etc., tolylene-2,4-diisocyanate, diphenylmethane-
4,4'-diisocyanate, 3-methyldiphenylmethane-4,4'-diisocyanate, m- and p-phenylene diisocyanate, chlorophenylene-2,4-
Diisocyanate, naphthalene-1,8-diisocyanate-3,3'-dimethyldiphenyl, 1,3,5-triisopropylbenzene-2,4-diisocyanate,
And aromatic polyisocyanates such as diphenyl ether diisocyanate and mixtures thereof. It may also be a polyurethane polyisocyanate obtained by reacting an excess of these polyisocyanates with a polyhydroxy compound such as ethylene glycol, butylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, glycerin, and hexanetriol. .. Further, a polyisocyanate containing an isocyanurate ring, a polyisocyanate containing an allophanate group, a polyisocyanate containing a buret group and the like can also be used. Further, in some cases, a polyisocyanate derived from dimer acid can also be used.

In the present invention, the molar ratio of isocyanate group to active hydrogen, for example, the --NCO /-OH equivalent ratio, is 0.5 to 0.5.
It is mixed in the range of 5. The -NCO / -OH equivalent ratio is 0.0.
When it is less than 5, curing is insufficient and a good cured product cannot be obtained. When it is 5 or more, the cured product becomes too hard due to the reaction of excess isocyanate groups, and the adhesive strength is lowered. Occurs. This equivalent ratio is preferably in the range of 1 to 3, in which the curing is sufficient and a good cured product is obtained.

As the filler (c) in the present invention, inorganic fillers such as calcium carbonate, talc, clay, bentonite, gypsum, alumina, diatomaceous earth, barium sulfate,
Silica, calcium hydroxide, perlite, vermiculite, mica powder, glass powder and the like can be used, and also organic fillers and mixed fillers such as fine wood powder, rice husk powder and synthetic resin powder can be used.

As the plasticizer (d) used in the present invention, phthalic acid esters such as dibutyl phthalate, dioctyl phthalate and diallyl phthalate, and phosphoric acid esters such as triphenyl phosphate and diphenyl cresyl phosphate can be used. .. Of these, dibutyl phthalate is most preferable because it does not increase the viscosity of the composition, has low volatility, and is inexpensive.

The addition amount of at least one of (e) calcium oxide, magnesium oxide and barium oxide in the composition of the present invention is arbitrarily selected according to the water content of the composition and the type and water content of the wood material. But you can
In order to effectively prevent foaming during curing, 1 in the composition
It is necessary to contain at least wt%, preferably 2
It is more than weight%. Further, calcium oxide, magnesium oxide, and barium oxide may be used alone or as a mixture at an arbitrary ratio. The filler may be added to either or both of the active hydrogen-containing compound and the polyisocyanate compound, but is preferably added to the active hydrogen-containing compound for ease of handling and foaming prevention effect. As other additives in the composition of the present invention, a curing accelerator, a silane coupling agent, a colorant, a thixotropic agent, a diluent and the like are used as necessary.

[0012]

The resin composition of the present invention is a two-component curing type urethane system, and usually contains (a) an active hydrogen-containing compound, (c) a filler,
(D) A first liquid agent (hereinafter referred to as a main agent) comprising a plasticizer and other additives and (b) a second liquid agent (hereinafter referred to as a curing agent) which is a polyisocyanate compound are mixed in various mixers. It is used by being mixed by using, and applied to a wood material by using a roll coater or a knife coater, and then reactively cured at room temperature or under heating. It was often the case that the conventional composition causes "blister" and becomes a defect of wood products, and the problem is that the polyisocyanate compound used reacts with the water contained in the air or wood or the water contained in the active hydrogen-containing compound. The result is that carbon dioxide gas is generated at the time of curing, and large and small bubbles are formed in the adhesive layer to cause peeling or a decrease in adhesive strength. The composition of the present invention serves as a filler for capturing water. Calcium oxide, magnesium oxide,
By adding at least one of barium oxide,
Effectively removes water contained in the composition, water absorbed from the atmosphere in the mixing and coating process and water contained in wood in the form of hydroxide, and is generated by the reaction between isocyanate and water. It solves the problems of "blisters" caused by carbon dioxide gas and defective defects due to poor adhesion.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples. The "parts" and "%" described in the examples and comparative examples mean "parts by weight" and "% by weight". Example 1 Polyether polyol obtained by adding ethylene oxide to bisphenol A (average molecular weight 68
0, hydroxyl value 165 mg KOH / g) 120 parts, plasticizer 100 parts dibutylphthalate, filler 10 parts calcium oxide, calcium carbonate 370 parts, ultrafine silica powder 20 parts, curing accelerator (dibutyltin laurate) 2 Was added as a main ingredient. Polymeric MDI as curing agent
(Isocyanate group content 31%) 40 parts was added to give a repairing resin composition. At this time, the -NCO / -OH molar ratio is 1.3. This resin composition has a large number of bush holes,
Apply with a knife coater on a plate of Yonematsu with convex wood grain on the surface, let stand at room temperature for 24 hours to cure,
A pine board with a smooth surface was obtained. [Examples 2 and 3] The same procedure as in Example 1 was repeated except that calcium oxide was replaced with magnesium oxide and barium oxide, respectively. [Example 4] 150 parts of a polyether polyol (average molecular weight 1000, hydroxyl value 114 mg KOH / g) obtained by adding ethylene glycol to polypropylene glycol, 100 parts of dibutyl phthalate as a plasticizer, and 20 parts of calcium oxide as a filler. , 400 parts of calcium carbonate, 20 parts of ultrafine silica powder, and 2 parts of a curing accelerator (dibutyltin laurate) were added to prepare a main agent. 40 parts of polymeric MDI (isocyanate group content 31%) was added as a curing agent to give a repairing resin composition. At this time -NCO / -OH
The molar ratio is 1.3. Thereafter, the pine boards were repaired in the same manner as in Example 1. [Examples 5 and 6] The same procedure as in Example 4 was carried out except that magnesium oxide and barium oxide were used instead of calcium oxide. [Comparative Example 1] The same procedure as in Example 1 was carried out except that the filler was calcium carbonate. [Comparative Examples 2 and 3] The same procedure as in Example 1 was repeated except that the filler was calcium carbonate and the plasticizers were diethyl phthalate and dioctyl phthalate, respectively. Comparative Example 3 had a high viscosity and was slightly difficult to apply. The surface state of the obtained pine boards was visually observed. Further, the adhesiveness of the cured resin product at the bush hole portion was examined. The results are shown in Table 1.
Shown in.

[0014]

[Table 1]

[0015]

As is apparent from the above examples, the resin composition for repairing wood materials according to the present invention does not cause "blister" which is a drawback of the prior art, and has good adhesiveness. It is suitable for repairing conifers.

Claims (1)

[Claims] 1. A resin composition for repairing wood materials, which contains an active hydrogen-containing compound, a polyisocyanate compound and a filler as essential components, and further comprises a plasticizer and magnesium oxide or calcium oxide as a filler for trapping water. A resin composition for repairing wood materials, comprising at least one kind of barium oxide.