JPH0436358A - Resin composition - Google Patents

Abstract

PURPOSE:To provide an inexpensive resin composition for wood which can be expanded and cured at low temperatures, does not cause a ply wood to undergo volume shrinkage, warpage, etc., when applied thereto and excels in workability, productivity, etc., by mixing an aqueous emulsion resin with a blowing agent. CONSTITUTION:An aqueous emulsion resin is mixed with a blowing agent to produce a resin composition for wood. Examples of the aqueous resin emulsion to be used include acrylic resin, vinyl acetate resin and vinyl chloride resin emulsions. Examples of the blowing agent to be used include sodium carbonate and ammonium bicarbonate. By further adding a polyisocyanate compound (e.g. phenylene diisocyanate) to the above composition, the curing rate at low temperatures can be improved. By applying the obtained resin composition to a ply wood or the like, a smooth coated surface can be obtained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides a coating film containing bubbles that is free from volumetric shrinkage.
The present invention relates to a wood resin composition for obtaining a smooth surface.

[Prior art and problems to be solved by the invention] Conventional wood resin compositions are classified into solvent-based and water-based.The former has the characteristic of quick drying, but contains organic solvents or is difficult to use due to the use of organic solvents. environmental and health disadvantages,
There is also the issue of fire hazard during construction. Although the latter is not inconvenient for the health of workers or poses a risk of fire, it dries slowly after application and has problems with workability.

Furthermore, after both coatings are applied, dents usually occur due to volumetric shrinkage of the resin, which is called "eye loss," so as a solution to this problem, a resin composition based on a foaming agent such as urethane foam or phenol foam is overlaid. However, in recent years, there has been a growing need for resins with excellent surface smoothness without ``eye discoloration'' to cope with the use of raw wood, which is the raw material for plywood, particle board, etc., which has become lower grade in recent years. However, under the current circumstances, it is not possible to obtain a resin composition with good versatility that can be applied with a cell-containing resin at a low temperature using ordinary general-purpose painting equipment.

For example, recently, polyisocyanate has been added to water-based elastomer, and a resin composition is applied to the entire surface of the plywood using a two-component mixing machine.
One possible method is to heat the plywood for about 10 minutes before and after C to harden the foam, fill in defects such as dents and cracks on the plywood surface with the resin composition, and then sand the excess foam with paper to obtain smoothness. ing. However, with this method, 100℃
Wood-based materials such as plywood that are exposed to high temperatures before and after
The value of the product is often lost due to twisting and warping.

Therefore, curing accelerators are generally used to foam and harden polyisocyanate at low temperatures, but there is a problem in that sufficient curing and foaming cannot be promoted at temperatures below 60°C.

By adding polyisocyanate, a foaming effect can be observed even at room temperature, but it takes several hours and is not economical for industrial use, and the coating film itself is not sufficiently cured, causing problems in subsequent processes. It is not practical because it causes problems such as paper clogging during siding.

[Means to solve the problem]

In order to solve these problems, the present inventors have developed a material that foams and hardens at low temperatures, provides a smooth surface without "twisting,""warping," and "fading," and has good workability and productivity. We have discovered a low-cost wood resin composition and completed the present invention.

That is, it relates to a resin composition characterized by containing a blowing agent in an aqueous emulsion resin, or a blowing agent and a polyisocyanate compound in an aqueous emulsion resin.

[Specific means for carrying out the invention]

The present invention will be explained in detail below.

The aqueous emulsion of the aqueous emulsion resin used in the present invention is one or two of the following: acrylic resin emulsion, vinyl acetate resin emulsion, vinyl chloride resin emulsion, vinylidene chloride resin emulsion, and styrene-butadiene resin emulsion. A mixture of the above is mainly used.

That is, the water-based emulsion resin includes an emulsion type acrylic resin, a vinyl acetate resin, a vinylidene chloride resin, a vinyl chloride-acrylic copolymer resin, a vinylidene chloride-acrylic copolymer resin, an acrylic-vinyl acetate copolymer resin, and a chloride resin as a vehicle. One type or a mixture of two or more of vinyl-vinyl acetate copolymer resins, vinyl acetate copolymer resins, vinyl acetate rubeover styrene-acrylic copolymer resins, vinyl styrene acetate-butadiene copolymer resins, etc. are used.

As blowing agents used for these, carbonate compounds such as sodium carbonate, sodium hydrogen carbonate, calcium carbonate, magnesium carbonate, ammonium carbonate, and ammonium bicarbonate, and ammonium salts such as ammonium chloride, ammonium sulfate, and ammonium nitrate are used.

The amount of the blowing agent added is 1 to 30% by weight based on the vehicle of the water-based emulsion paint (hereinafter, % by weight unless otherwise specified).
is simply written as %) is preferably added, the amount added is 1
If it is less than 30%, sufficient results cannot be obtained as a foaming agent, and if it exceeds 30%, uniform foaming cannot be obtained, which is not preferable.

Examples of foaming aids used include organic tin compounds. For example, tin (n) acetate, tin (If
) octoate, tin(If) ethylhexoate, carboxylic acid salts such as tin(It) lauate, dialkyltin salts such as dibutyltin acetate, dibutyltin laurate, dibutyltin maleate and dioctyltin diacetate.

The amount added is preferably 0.1 to 1.0% based on the vehicle of the water-based emulsion paint.

Tertiary aliphatic amines are also commonly used, such as triethylenediamine, N-ethylmorpholine, N,N,N-tetramethyl-1,3-butanediamine, bis-2-(N,N- Compounds such as dimethylamino)ethyl ether, diethylenetriamine, oxybis(N,N-jetanolamine) are used.

The amount of the compound added is usually 0.1 to 0.6%, preferably 0.2 to 0.4%, based on the vehicle of the water-based emulsion paint.

The foaming agent and foaming aid may be one or more selected from the above, and may be used alone or as a mixture.

Foaming agents are often used to ensure uniform and smooth foaming. Silicone-based foam stabilizers are mainly used, and are added in an amount of 0.05 to 3.0% to the water-based emulsion resin vehicle to adjust the foam size, foaming amount, and condition. It is desirable that the foam stabilizer has the same function as the antifoaming agent, and antifoaming agents are usually added to water-based emulsion paints. It is necessary to determine the amount.

Note that if the foam condition of the coating film is sufficiently stabilized by the antifoaming agent in the aqueous emulsion paint, the foaming agent may not be added.

Pigments for water-based emulsion resin include titanium dioxide,
Calcium carbonate, mica, talc, phlegm, bentonite, tomato powder, kaolin, etc. are blended, but are not limited thereto.

In addition, as other additives used in the aqueous emulsion resin, a thickener, a dispersant, a film forming aid, etc. may be added as necessary.

Usually, the resin composition is prepared before coating and immediately applied by conventional application means. Normally, the prepared resin composition can be applied immediately, but the water-based emulsion resin, foaming agent, foaming aid, foaming agent, antifoaming agent, dispersing agent, and pigment are mixed during coating to form a resin composition, which can be applied to rolls or It is applied using a conventional coating method such as a knife coater.

The foaming agent blended into the water-based emulsion resin decomposes when slightly heated to generate small bubbles, and the foaming aid promotes and hardens the foaming to form a strong coating film containing bubbles.

When a foam stabilizer or an antifoaming agent is blended into the resin composition, the generated bubbles are more uniformly expanded and controlled.

The temperature at which foaming bubbles uniformly foam and harden is 40-80℃.
The temperature is preferably 40-60°C, more preferably 40-60°C.

Bubbles are formed throughout the foamed coating film, but the formation, amount, and growth rate of the bubbles vary depending on the type and amount of the emulsion resin and blowing agent, foam stabilizer, etc., so the formulation should be determined accordingly. It will be done.

Furthermore, in the present invention it is possible to achieve the initial goal by adding polyisocyanates.

That is, by adding a foaming agent, a foaming aid, a foam stabilizer, an antifoaming agent, a dispersing agent, and a pigment to an aqueous emulsion resin, and then adding and mixing a polyisocyanate compound, the foaming agent can cure the resin at low temperatures. This will increase your speed and allow you to achieve your initial goals.

The usage form of polyisocyanate is 2.4 isomer and 2,6 isomer, and 2.4 isomer is about 65 to 8
0% and one of the normal mixtures,
However, other polyisocyanates having an average of two isocyanate groups per aromatic ring are also suitable.

Examples of such compounds include phenylene diisocyanate, naphthalene diisocyanate, xylene diisocyanate, diphenyl-4,4"-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, bis(isocyanate)methylcyclohexane, trimethylhexamethylene diisocyanate, etc. Ru.

These additives are added in an amount of 5 to 50% and mixed with respect to the vehicle of the aqueous emulsion resin. Although common resins are used as vehicles for water-based emulsion resins, the composition Tg (glass transition point), molecular weight, and amount of the resin are determined depending on the use and required performance of the foamed coating film.

Further, the type and amount of polyisocyanate are determined depending on the use and required performance of the foamed coating film.

The resin composition thus obtained can be applied to wood materials such as plywood and particle board without causing "eye discoloration".
Twisted "It is a coated material that does not warp, can be finished smoothly, and has good sanding suitability, making it suitable as a wood material for secondary processing.

(Examples) Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples.

In addition, in Examples and Comparative Examples, parts represent weight standards.

Example 1 First, formulations A and B in Table 1 were used as water-based emulsion resins.
, I prepared a C5DO one.

Next, formulations (1), (2), (2), and (2) shown in Table 2 were prepared as blowing agents, blowing aids, and polyisocyanates.

As shown in Table 1, 16 types of resin compositions Al to DIV were obtained by mixing the combinations of aqueous emulsion resins and polyisocyanates in the total amounts shown in Table 3.

Table 3 The resin composition AI-DIV was prepared by using a 2.5 mm plywood board for testing (usually a back board called 6 board was also used for the front board, and there were no cracks or pinholes. After applying 50 to 100 g/bo on the entire surface of the 2.5-1 plywood using a knife coater,
It was heated at 50 to 60° C. for 10 minutes to foam and harden, and the defective concave portions were made smooth or slightly convex.

As a result, the 2,5+n+ plywood coated with the resin composition and dried did not exhibit any "twisting" or "warping", and even when sanding was performed, the sanding paper was not "clogged".

Furthermore, the sanded 2.51 plywood was left at room temperature for 10 days, but there was no "eye discoloration".

Comparative Examples 1 to 3 Formulations 1.2.3 in Table 4 were prepared by adding 5 to 15 parts of polyisocyanate to 100 parts of an aqueous emulsion resin composition, and mixing a foaming aid as needed.

When the foaming state of the resin compositions and Comparative Examples 1 to 3 was confirmed under the same conditions as in the examples, foaming to the extent of smoothing out defective recesses such as pinholes was not obtained.

Therefore, when we set the drying temperature to 90 to 100 degrees Celsius and heated the area sufficiently for 10 to 20 minutes, we were able to foam and harden the defective area, but it also prevented clogging of the sandpaper during sanding, which is required to create a smooth surface. The results of comparing the sanding suitability performance of Example 1 also showed that it was significantly inferior.

〔Effect of the invention〕

According to the present invention, it is possible to prevent volumetric shrinkage due to "scattering" after coating plywood, "twisting" and "warping" of plywood, and "clogging" during sanding, which could not be achieved with conventional technology. was found to be achieved.

That is, the conventional technology does not achieve the purpose of these phenomena;
In the present invention, a blowing agent is added to and mixed with the water-based emulsion,
It was possible to obtain a resin composition that has characteristics, that foams and hardens uniformly despite the low drying temperature, and that satisfies all of these phenomena.

In the future, the raw wood situation will continue to worsen, which will have a significant impact on the wood and plywood industries, and the present invention is of great significance.

Patent applicant Mitsui Toatsu Chemical Co., Ltd. Table 4

Claims (1)

[Scope of Claims] 1) A resin composition characterized by containing a foaming agent in an aqueous emulsion resin. 2) A resin composition comprising a water-based emulsion resin containing a foaming agent and a polyisocyanate compound. 3) The water-based emulsion of the water-based emulsion paint is any one or a mixture of two or more of acrylic resin emulsion, vinyl acetate-based resin emulsion, vinyl chloride-based resin emulsion, vinylidene chloride-based resin emulsion, and styrene-butadiene-based resin emulsion. A resin composition according to claim 1 or 2. 4) The resin composition according to claim 1 or 2, wherein the blowing agent is selected from the group consisting of carbonate compounds and ammonium compounds.