JPS5912982A - Adhesive composition - Google Patents

Abstract

PURPOSE:The titled composition having improved storage stability, pot life of paste blended with an adhesive, initial bond strength after cold pressurizing, and bond strength resistant to warm water, obtained by blending an amino resin with specific amounts of polyacrylamide, polyvalent metallic compound, formaldehyde and urea. CONSTITUTION:(A) 100pts.wt. amino resin such as urea resin, urea-melamine co- condensation resin, etc. is blended with (B) 0.1-10pts.wt. nonionic polyacrylamide, (C) 0.1-5pts.wt. polyvalent metallic compound, preferably aluminum sulfate, etc., (D) formaldehyde (the preferable amount added is an amount equimolar with the component B when it is previously reacted with the component B and 1-10pts.wt. excess amount calculated as pure component D based on the component A when the component A is added in its use), and (E) urea (preferably amount is an amount to give a molar ratio of it to the component D added of 1.0-1.5), to give the desired composition. USE:Useful for preparing plywood, particle board, etc. with a low content of released formaldehyde.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive composition for use in the production of plywood, particle board, hardboard, etc., which releases a small amount of formaldehyde.

In recent years, there has been concern about the effects of formaldehyde emitted from plywood, particle boards, etc. on the human body, and the Japanese Agricultural Standards and Japanese Industrial Standards have been revised to regulate the amount of formaldehyde emitted from plywood and particle boards.

In the production of plywood and particle board, the most commonly used initial condensate is a urea compound, a phenol compound, and at least one of melamine, and formaldehyde. In order to control the amount of formaldehyde produced, it is necessary to keep the molar ratio of formaldehyde to urea compounds, phenolic compounds, or melamine to 15 or less, but this results in poor storage stability of the resulting amine resin, and The initial adhesive strength after cold pressing during plywood production is low, and the hot water resistant adhesive strength of the resulting plywood and particle board is also low.

In order to improve the above-mentioned drawbacks of the conventional method,
537 and Japanese Patent Publication No. 5'5-22519 disclose a method for improving storage stability and initial adhesive strength by adding vinyl polymer compounds such as polyvinyl alcohol, polyacrylamide, and polyacid-resistant vinyl. .

However, in the above-mentioned conventional technology, thermoplastic plastic
Although the initial adhesion of N is improved due to the addition of a Neil-based polymer compound, the hot water resistant adhesive strength is reduced.Additionally, the addition of a polymer compound increases the viscosity of the resulting adhesive and deteriorates its storage stability. In addition, the pot life of the adhesive-containing paste is short, and in order to avoid deteriorating the storage stability, only a small amount of the vinyl-based polymer compound can be added, and as a result, no improvement in the initial adhesive strength can be expected.

The object of the present invention is to improve the storage stability and to increase the initial adhesive strength and hot water resistant adhesive strength after cold pressing during the pot life of the adhesive-containing paste.

As a result of intensive research to achieve these goals, the present inventors have found that by adding a specific amount of polymethylol acrylamide and a polyvalent metal compound to the amine resin, the initial adhesive strength and hot water resistant adhesive strength can be improved. The present invention was based on the discovery that the storage stability of the adhesive composition is good, the pot life of the adhesive compounded paste is extended, and the puncture prevention effect is large when using high moisture content veneers and chips. completed.

That is, in the present invention, a), 0
1-10 parts by weight of polyacrylamide, b) 01-5
An adhesive composition characterized in that parts by weight of a polyvalent metal compound, C) formaldehyde, and d) urea are added.

Amine resins used in the present invention include urea resins, melamine resins, benzoguanamine resins, acetoguanamine resins, thiourea resins, mixtures thereof, or co-condensation resins, and these resins and phenolic resins may be used. Includes co-condensation resins with resorcinol resins, toluene resins and xylene resins. There is no problem in adding polyvinyl alcohol or cellulose-based thickener to the above-mentioned resin.

In the present invention, when using the adhesive, polyacrylamide and formaldehyde water may be mixed or reacted with the amine resin, and then added to the amino resin to be used as the adhesive composition of the present invention.

Examples of the polyacrylamide used in the present invention include nonionic polyacrylamide, cationic Mannich polyacrylamide, and vinyllactam polyacrylamide.
Examples include acrylamide copolymers, anionic acrylic acid no-goo acrylamide copolymers, and the like.

The amount of polyacrylamide added in the adhesive composition of the present invention is 01 to 1 with respect to 100 parts by weight of the amine resin.
It is necessary to add 0 parts by weight, preferably in the range of 01 to 5 parts by weight. If the amount added is less than 0.1 parts by weight, no effect on initial adhesive strength will be obtained, and if it is more than 10 parts by weight, the storage stability of the resulting adhesive composition will be reduced.

The amount of formaldehyde added may be equivalent to the amount of polyacrylamide in order to react with the polyacrylamide as described above, but when adding it to the amine resin at the time of use or when simply mixing acrylamide and formaldehyde. 21. i.e. formal versus amine resin.

It is safe to add usually 1 to 10 parts by weight of pure tehyde. Due to the addition of formaldehyde mentioned above, it is necessary to add urea to reduce the formaldehyde needles emitted from plywood and particle hoards, etc. The amount of urea added is desirably adjusted to a molar ratio of 1.0 to 15 with respect to the amount of formaldehyde mentioned above.

The polyvalent metal compounds in the present invention are oxides and salts of polyvalent metals of divalent or higher valence among metals from Groups 2 to 8 of the periodic table and transition metals, and examples of the former include calcium, magnesium, etc. , zinc, barium, cadmium,
Examples include lead, copper, aluminum, iron, zirconium, and chromium, as well as bentonite, clay, and talc, which are constituent components of these oxides.

Examples of polyvalent metal salts include carbonates, sulfates, nitrates, acetates, chlorides, and silicates of the above-mentioned polyvalent metals.

Among these, it is desirable to use acidic salts such as zirconium carbonate, aluminum sulfate, chromium nitrate, zirconium acetate, aluminum chloride, ferrous chloride, and ferric chloride. These metal salts and oxides may be used alone or in combination of two or more.

The amount of these polyvalent metal compounds added results in poor amine resin properties and poor puncture prevention effect when using high moisture content veneer.
Furthermore, if the amount is more than 5 parts by weight, the initial adhesive strength and water-resistant adhesive strength will decrease.

In carrying out the present invention, in addition to wheat flour as a bulking agent conventionally used, barley flour, rice flour, wood flour, talc, clay, etc. may be used, and polyvinyl alcohol for the purpose of improving temporary adhesion may be used. It is permissible to use the compound in combination with blood meal, soybean meal, corn meal, etc., which have been conventionally used as a countermeasure for high moisture content veneers.

According to the method of the present invention, the storage stability of the adhesive is good despite the addition of a polymer compound, and the pot life of the adhesive composition is sufficiently long, so that there are no practical problems.

In addition, due to the adhesive strength of polyacrylamide, the initial adhesive strength during plywood production is high, and the cold pressing time is short, and it is also possible to use high moisture content veneer such as 20 to 25% by weight. It is.

According to the method of the present invention, although a thermoplastic resin such as polyacrylamide is used, it is crosslinked with an amine resin using formaldehyde and a polyvalent metal compound as an intermediary, resulting in a decrease in hot water resistant adhesive strength. It is now possible to produce plywood, particle board, and hardboard that have stable adhesive strength and emit less formaldehyde.
Plywood when using veneers and chips that still have high moisture content,
Particle board and hardboard can be prevented from punctures.

It has high practical value.

Next, the present invention will be specifically explained using Examples and Comparative Examples. In the following text, except for those related to the percentage of wood breakage, "chi" indicates weight %, and "part" indicates parts by weight.

Example 1 100 parts of urea resin (Mitsui Toatsu (Warisaki, Nyroid U-701, trade name)) was preliminarily mixed with 1 part of polyacrylamide (Mitsui Suipunamitsu ■, Acofflock N-10 part 8 trade name) and 67%. An adhesive composition was obtained by adding 3 parts of formaldehyde solution, 2 parts of urea, and 6 parts of aluminum sulfate.Furthermore, 15 parts of wheat flour, 20 parts of water, and 1 part of ammonium chloride were added and mixed by stirring. An adhesive compounded paste was obtained, and plywood was manufactured using the compounded glue under the following bonding conditions.

Table 1 shows the performance of the adhesive composition, blended paste, and plywood.

- Adhesion conditions - Veneer composition: 3-layer composition of lauan veneer with each thickness of 0.6 + 13 + O6” 7m Veneer moisture content: 7-10% for both original and intermediate boards Coverage: 25 fi' / 900 cni Deposition time: 20 minutes Cold pressure condition '12 Kg/Cwt, 60 minutes hot pressure condition
10 kg/cnl, 120°C, 50 seconds/sheet Initial adhesion strength was measured 20 minutes after cold decompression.

Example 2 100 parts of urea resin (manufactured by Mitsui Toatsu ■, Niroid U-701, trade name) was preliminarily added with polyacrylamide (manufactured by Mitsui Toatsu ■, Aco-Floref N-1008,
Product name) 2 parts, 5 parts of 67% formaldehyde aqueous solution,
A heated mixture of 6 parts of urea, 2 parts of aluminum chloride, and 10 parts of water was added, and further 20 parts of wheat flour, 11 parts of water, and 1 part of ammonium chloride were added and mixed with stirring to obtain a paste containing an adhesive for plywood.

Plywood was manufactured under the same bonding conditions as in Example 1, except that the moisture content of the veneer was set to 16 to 20%, and its performance is shown in Table 1.

Example 5 In place of the urea resin, a urea-melain cocondensation resin (Mitsui Toatsu (Warisaki, Niroid U-350, trade name)) was used.
．． Plywood was manufactured under the same conditions as in Example 2 using ferric chloride instead of aluminum chloride, and its performance is shown in Table 1.

Examples 4 to 7 Amino resin, polyacrylamide, polyvalent metal compound,
A formaldehyde aqueous solution of Section 37 and urea were stirred and mixed in the proportions shown in Table 1 to obtain a paste containing an adhesive 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 5 Amine resin, polyacrylamide, polyvalent metal compound,
A 67% formaldehyde aqueous solution and urea were stirred and mixed in the proportions shown in Table 2 to obtain a paste containing an adhesive for plywood. Furthermore, plywood was manufactured under the same bonding conditions as in Example 1, and its performance is shown in Table 2.

Reference Examples 1 to 4 Amine resin, polyacrylamide, polyvalent metal compound,
A 67% formaldehyde aqueous solution and urea were stirred and mixed in the proportions shown in Table 6 to obtain a paste containing an adhesive for plywood. Furthermore,
Plywood was manufactured under the same bonding conditions as in Example 1, and its performance is shown in Table 6.

[Note]

≠1) UP: urea resin, UMF: urea/melamine resin, MPF: melamine, phenolic resin H2) PAM
: Polyacrylamide -
0-2535 ￥4) Except for Examples 6 and 4, the test was conducted according to the Japanese Agricultural Standards hot and cold water immersion test.

Examples 6 and 4 were based on the repeated boiling test according to the Japanese Agricultural Standards.

XS) Mitsui Cyanamitsu Aco-Flock A
-110

Claims (1)

[Scope of Claims] Shun To 100 parts by weight of amino resin, a) 01 to 10 parts by weight of polyacrylamide, b) 01 to 5 parts by weight of a polyvalent metal compound, c) formaldehyde, and d) urea are added. An adhesive composition characterized by: 2) Claim 1 in which the polyvalent metal compound is an acid salt
The adhesive composition described in .