JPS58222173A - Adhesive composition - Google Patents

Abstract

PURPOSE:To provide an adhesive composition which emits only a small amount of free HCHO and has high temporary adhesive strength and bonding power and excellent water resistance, prepared by adding HCHO, urea and a specified inorganic metal salt to an amino resin. CONSTITUTION:1-10pts.wt. HCHO, uea in such an amount that the molar ratio of HCHO to urea may be 1.0-1.5, and 1-20pts.wt. inorganic metal salt excluding alkali metal halide (e.g. Na2SO4) are added to 100pts.wt. (on a solid basis) amino resin (e.g. melamine resin). EFFECT:The adhesive composition shows a high initial bonding strength and minimizes cold pressing time in the manufacture of plywood which may employ veneers with a high water content of 20-25%, thus producing plywood, particle board, etc. which emit only a small amount of HCHO without lowering the water resistance of the products.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to adhesive compositions for use in the manufacture of plywood, particleboard, fiberboard, etc., which have low formaldehyde emission needles.

In recent years, there has been concern about the effects of formaldehyde emitted from plywood, particleboard, and fiberboard on the human body, and the amount of formaldehyde emitted from plywood and particleboard is regulated by the Japanese Agricultural Standards and the Japanese Industrial Standards, respectively.

For the production of plywood and particleboard, at least one of urea compounds, phenolic compounds and melamine is used.
Seeds and formaldehyde are the main raw materials, and in order to control the amount of formaldehyde, it is necessary to lower the molar ratio of formaldehyde to urea compounds, phenolic compounds, and melamine. There is a problem that the force is reduced and the adhesive strength and water resistance of the resulting plywood and particle board are reduced.

In order to improve the initial adhesion strength after cold pressing during plywood production (hereinafter referred to as temporary adhesion), it is known to add vinyl polymer compounds such as polyvinyl alcohol and polyacrylamide, but the resulting adhesive becomes thicker,
There are drawbacks such as further deterioration of water resistance.

In order to maintain water resistance, it is possible to increase the amount of melamine, phenol, etc. in the amine resin, but this has the disadvantage of making the width of both adhesive paths significantly higher.

The present invention provides an adhesive composition suitable for the production of plywood and particleboard that releases less formaldehyde and does not pose problems in temporary adhesion, adhesion strength and water resistance, without significantly increasing the cost of adhesives. The purpose is to provide.

The present inventor has arrived at the present invention as a result of research on Kannon in order to accomplish these problems.

That is, the present invention is an adhesive composition characterized by a skewer in which (a) formaldehyde, (b) urea, and (C) inorganic metal salts other than alkali metal chlorides are added to an amine resin.

Amino resins in the present invention include urea resins, melamine resins, benzoguanamine resins, acetoguanamine resins, thiourea resins, or mixtures thereof, or cocondensation resins with them, phenolic resins, resorcinol ItJ]L
1) Contains a mixture or co-condensation resin with a luene resin, a cylene resin, etc. Polyvinyl alcohol or a cellulose thickener may be added to the above resin.

The formaldehyde used in the present invention may be liquid formalin or solid paraformaldehyde, and the amount added is preferably 1 to 10 parts by weight as a pure formaldehyde content per 100 parts by weight of the amino resin solid content. If the amount added is less than 1 part by weight, no effect can be expected;
If it exceeds 0 parts by weight, the amount of formaldehyde released will be greatly affected and is not practical.

Inorganic metal salts other than alkali metal halides in the present invention include sulfates, nitrates, phosphates, carbonates, oxides, and halogens of metals other than alkali metals such as calcium, copper, magnesium, lead, and aluminum. oxides, sulfates of alkali metals such as sodium and potassium,
Examples include nitrates, phosphates, carbonates, and oxides, preferably sulfuric acid, IJ Uno 1, aluminum sulfate, and calcium chloride.

The amount of these inorganic metal salts added is based on the solid content of amine resin 1
It is preferably 1 to 20 parts by weight per 00 parts by weight. If the amount added is less than 1 part by weight, no effect can be expected, and if it exceeds 20 parts by weight, the adhesive strength and water resistance will decrease.

When an alkali metal halide such as sodium chloride is used as the inorganic metal salt, the effects mentioned in the present invention cannot be expected in terms of temporary adhesion, water resistance, etc.

In the present invention, it is preferable that the molar ratio of urea to formaldehyde to be added is formaldehyde/urea = 10 to 15. If the molar ratio is less than 10, there is a concern that the elbow contact force will decrease in aqueous properties, and if it exceeds 15, formaldehyde released from plywood and particle board will increase.

In the present invention, the above-mentioned pornographic aldehyde, urea and alkali metal halide can be removed.
Even if the king of the three is mixed in advance, cooled, and the remaining ingredients are added separately, or if the three are mixed in advance and then added, the effect remains the same.

Furthermore, when urea and formaldehyde are allowed to coexist in advance, the effect does not change even if each exists as a 7-mer and 1- as a urea-formaldehyde non-resinous condensate.

Among the constituent elements of the present invention, (a) formaldehyde, (
1)) If any component of the inorganic metal salts other than urea and (C) alkali metal halides is missing, the effect referred to in the present invention cannot be expected. For example, if (a) formaldehyde is missing, adhesive strength and water resistance will be affected. (1) Lack of urea results in increased formaldehyde release. Furthermore, if (c) inorganic metal salts other than alkali metal halides are missing, the adhesive strength and water resistance become unstable. In contrast, the coexistence of the three constituent elements of the present invention with the amine resin makes it possible to achieve temporary adhesion without significantly increasing the adhesive price.
It becomes possible to produce plywood and particle board that emit less formaldehyde without causing problems in adhesive strength and water resistance.

In the practice of the present invention, barley flour, rice flour, wood flour, talc, clay, etc. may be used as extenders in addition to the conventionally used stamp flour, and compounds such as polyvinyl alcohol for the purpose of improving temporary adhesion may be used. There is no problem in using together blood meal, soybean flour, corn flour, which are used as a countermeasure for high moisture content veneers, and wax emulsion, which is used to improve water repellency.

According to the method of the present invention, in order to reduce formaldehyde released from plywood and particleboard, even if an amino resin with a low molar ratio of formaldehyde and amine compounds such as urea and melamine is used, it is possible to High adhesive strength, short cold pressing time, and 20
It is possible to use veneers with high moisture content, such as ~25%, and it is possible to produce products with low formaldehyde emissions without reducing the water resistance of plywood particleboard.

Further, according to the method of the present invention, in addition to the above-mentioned purposes, plywood particle board when using high moisture content veneer chips,
The fiberboard is protected from punctures.

As described above, the present invention has high practical value in the production of plywood and particle board with low formaldehyde emission.

Next, the present invention will be specifically explained using Examples and Comparative Examples. All terms in the text below refer to parts by weight, except for those relating to wood breakage rate and water absorption thickness expansion rate. Moreover, parts indicate parts by weight.

Example 1 4 parts of sodium sulfate, 37 parts per 100 parts of urea resin (manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name U-701, resin content 52%)
Add 7 parts formalin, 2 parts urea, and add 20 parts flour.
1 part, 16 parts of water, and 1 part of ammonium chloride were added and stirred to obtain an adhesive compounded paste for plywood, and plywood was manufactured using the compounded paste under the following bonding conditions. The performance of plywood is shown in Table 1.

Veneer 1-i'7 composition: 0.6 + 1.3 + 0.6
-+, /- thickness lauan 3-ply veneer composition Moisture content: 7 to 10 for both original plate and middle plate Coating amount: 25 g 7900 m Deposition time = 20 flags η Cold pressure conditions: ,, 1';, 2 Illusion/7, ISO? +1 heat and pressure conditions: 10 kq/cl, 120° 0.50 J SiO Example 2 100 parts of urea resin U-701 (mentioned above) was coated with 4 parts of sodium sulfate, 7 parts of formalin 67, and urea. 2nd part,
10 parts of water was heated and mixed and heated to a temperature of 0.degree. C., and further 20 parts of wheat flour, 6 parts of water, and 1 part of ammonium chloride were added and mixed with stirring to obtain an adhesive compound paste for plywood.

Plywood was manufactured under the same bonding conditions as in Example 1.

Its performance is shown in Table 1. Example 3 Instead of urea resin, urea melamine cocondensation resin (manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name, U-350) was used instead of sodium iliiiate. Plywood was manufactured using aluminum sulfate under the same conditions as in Example 1, and its performance is shown in Table 1.

Examples 4 to 9 Amine resin, formaldehyde, inorganic metal salt, and urea were stirred and mixed in the ratios shown in Table 1 to obtain adhesive compositions for plywood.

Plywood was manufactured under the same bonding conditions as in Example 1, and its performance is shown in Table 1.

Comparative Examples 1 to 8 Formaldehyde, inorganic metal salt, and urea were stirred and mixed with the amine resin in the proportions shown in Table 1, or without addition.
An adhesive compounded paste for plywood was obtained.

Plywood was manufactured under the same bonding conditions as in Example 1, and its performance is shown in Table 1.

Example 10 Using urea resin (manufactured by Yoi Toatsu Kagaku Co., Ltd., trade name U755, resin content 65%), sodium sulfate formalin, urea, water, and ammonium chloride, the following compounded glue for particle board was obtained. .

Sodium sulfate 55 37% formalin 88 Urea 55 Water
52 25 Ammonium Chloride 05 1" Particle board was manufactured using the compounded glue described in "2" under the following bonding conditions. Table 2 shows the +'1 ability of particle board.

Model configuration: 6 layers using lauan chip (II')
207 Plate J: 13mm Chip moisture content 2 3% resin spraying rate for both surface layer and length layer
: (Surface layer) 12th layer, (top layer) 7th layer pine moisture content =
(Surface layer) 20%, (hair waste) 10 pieces Heat and pressure conditions: 15
0°0.4 mLr+Lr side 11 Increase the resin blowing rate of Example 10 by 2 factors (surface layer) 10
Particleboard was produced with five receiving and (stopping) layers and other viewing conditions unchanged. The formulation and performance of the particle board at that time are shown in Table 2.

Example 12 Example 10 was performed using urea melamine resin (manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name U 775, resin content 65 yen) in place of urea 41,1 fat, and aluminum sulfate in place of sodium sulfate. Partifrucon 1 was produced under the same conditions. Particle board 9 performance is shown in Cloth-2.

Example 7 (i+j Example 13 Particle board was manufactured under the same conditions as Example 11 using urea melamine resin U755 (described above) instead of urea resin and aluminum sulfate instead of sodium sulfate. Performance of particle board are shown in Table-2.

Comparative Examples 9 to 12 Formaldehyde, inorganic metal salt, and urea were stirred and mixed with amine resin in the ratios shown in Table 2, or a compounded paste for particle board was obtained without adding them. Using this, a particle board was manufactured under the same conditions as in Example 10. The performance of particle board is shown in Table 2.

2 (Notes) Table 1 (1) This refers to the adhesion state of the constituent veneers after cold pressing during the plywood manufacturing process.

(2) Japanese Agricultural Standards for Ordinary Plywood (hereinafter abbreviated as JAS)
I followed. Figures in ) indicate the wood breakage rate. The same applies to water-resistant adhesive strength.

(3) Example 345 was subjected to one JAS fish boiling test, and the other samples were subjected to hot and cold water immersion tests.

(4) The desiccator method specified by JAS was used.

Table 2 (1) Performance test is based on Japanese Agricultural Standards JIS-A 5908
Follow the method.

However, the water absorption thickness expansion coefficient of 70°02Jr was measured using a wet bending specimen.

Patent applicant Mitsui Toatsu Chemical Co., Ltd. 6

Claims (1)

[Claims] (1) Amine resin, (a) formaldehyde, (b)
An adhesive composition characterized by adding urea and (C) inorganic metal salts other than alkali metal halides. The adhesive composition described in .