JPS6054988B2 - Alkali-curing modified urea resin liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel modified area resin liquid that hardens with alkalinity. The purpose is to provide an inexpensive resin liquid.

Conventionally, area resin has been the cheapest resin among plastics, and for that reason, it has been used in large quantities as an adhesive for plywood and particle board.

Area resins are generally subjected to an addition reaction under alkaline conditions and then to a condensation reaction under acidic conditions. Therefore, when curing the area resin, use an acidic curing agent and
Harden by acidifying H3-6. When wood is bonded using area resin, excellent adhesive strength can be obtained, but water resistance and durability are insufficient.

Therefore, when high water resistance and durability are required, melamine or the like is co-condensed.

Since carmelamine is more expensive than urea, the resin liquid co-condensed with melamine is also expensive. The reason why area resins have insufficient water resistance and durability is that the acid used when curing the resin remains in the adhesive layer and acts as a catalyst for the decomposition reaction of methylene bonds. If residual acid is removed, even those bonded with area resin adhesive will exhibit excellent water resistance and durability.

Therefore, if the area resin is cured under alkaline conditions, not only can an inexpensive wood adhesive with excellent water resistance and durability be obtained, but most of them are alkaline and have a comparable strength. It can also be effectively used as an adhesive or reinforcing agent for fragile inorganic moldings.
From this viewpoint, the present inventors have been conducting research on amino resins that harden under alkalinity.

First, by co-condensing 1.5 to 12 moles of formaldehyde and 0.3 to 3 moles of acetone with respect to 1 mole of an amino compound, a modified amino resin liquid that hardens under alkalinity was produced and a patent application was filed. (Special application Sho M-88
7♀ issue). The present invention further improves the adhesive performance of the alkali-curable modified amino resin liquid in the prior invention, and has succeeded in further improving the water-resistant adhesive performance of the resin liquid.

That is, the present invention provides a modified area resin liquid containing urea, formaldehyde, and acetone as main components and co-condensed in a ratio of 1.5 to 12 moles of formaldehyde and 0.3 to 3 moles of acetone per 1 mole of urea, and an aqueous This is an alkaline curing type modified area resin liquid consisting of rubber latex.

The modified area resin liquid of the present invention is prepared by mixing formaldehyde in a ratio of 1.5 to 12 moles with respect to 1 mole of urea, and adding acetone and urea to an initial mixture of area resin obtained by heating and condensing the mixture by a known method. It is produced by adding at a rate of 0.3 to 3 moles per mole and co-condensing under alkalinity at a temperature of 50 to 90C and a pH of 8.5 to 12.

At this time, it is more preferable that part of the formaldehyde to be added be divided and added at the time of adding acetone.

Alternatively, it can be produced by heating and condensing urea and formaldehyde and acetone and formaldehyde separately in advance, and then mixing these initial condensates at room temperature or under heating to form the resin composition of the present invention.

Furthermore, if necessary, the present invention may also include adding a small amount of one or more of thiourea, ethylene urea, melamine, acetoguanamine, benzoguanamine, phenol, resorcinol, etc. during the production of the modified area resin liquid. - Also, one or more of starch, dextrin, cationically modified starch, gum arabic, gum tragacanth, sodium alginate, carboxymethylcellulose, methylcellulose, hydroxycellulose, polyvinyl alcohol, sodium polyacrylate, polyacrylic acid amide, etc. Two or more types may be added in small amounts.

The first feature of the present invention is that the molar ratio of urea and acetone is limited to 0.3 to 3 moles of acetone per mole of urea.

If the amount of acetone is less than 0.3 mol per mol of urea, the properties of area resin will appear and it will not harden under alkaline conditions.

Furthermore, if the amount of acetone exceeds 3.0 moles, the viscosity of the resin will become too low and the permeability will increase, making it difficult to always obtain a stable adhesive effect and causing problems such as significantly higher manufacturing costs. . However, urea 1
If the amount of acetone is 0.3 mol or more, it will harden under alkaline conditions;
When the amount is within the range of 3 to 3.0 mol, a resin liquid with a viscosity suitable for adhesion and impregnation reinforcement can be obtained.

The second feature of the present invention is that the modified area resin liquid obtained by the above method is mixed with a water-based rubber latex.

The aqueous rubber latex used in the present invention is synthesized from natural rubber latex, styrene-butadiene rubber, acrylonitrile-butadiene rubber, butyl rubber, isoprene rubber, chloroprene rubber, methacrylic acid-butadiene rubber, etc. Rubber latex is preferred, and those modified with carboxyl groups, hydroxyl groups, amino groups, amide groups, etc. can also be used.

By mixing one or more of these aqueous rubber latexes with the modified area resin liquid, the alkali-curable modified area resin liquid of the present invention, which has even better adhesive performance, can be obtained.

The mixing ratio of water-based rubber latex and modified area resin liquid is
Although not necessarily limited, modified area resin liquid 1
It is preferable to mix 5 to 100 parts by weight of the aqueous rubber latex to 0 parts of rutting.

If the amount of water-based rubber latex mixed is less than 5 parts by weight, the effect of improving adhesive performance by adding the latex is small, and if the amount of ruts is more than 10 parts, the product cost increases and practicality decreases.

When using the resin liquid of the present invention, known fillers such as wheat flour, barley flour, defatted soybean flour, cornstarch, etc., clay, talc, bentonite, asbestos, wood flour, walnut flour, bark powder, etc. may be used. It is preferable to use a known filler such as potassium, etc. as a hardening agent.
One or more mixtures of oxides, hydroxides or basic salts of alkali metals such as sodium, lithium, etc., or divalent or trivalent metals such as calcium, barium, magnesium, strontium, zinc, aluminum, etc. It is preferable to use However, nitrogen compounds such as ammonium hydroxide and amine compounds
It is not very suitable as a curing agent because it causes the gelation rate of the resin to be extremely slow.

A resin paste solution prepared by mixing these extenders, fillers, curing agents, etc. is used for bonding in the same manner as a conventional area resin adhesive paste solution.

The alkaline curing modified area resin liquid of the present invention is not only suitable for adhering wood materials such as plywood, particle board, hardboard, wood panels, and laminated wood, but also for bonding wood wool cement boards, valve cement boards, gypsum boards, etc. It can also be used for adhesion or impregnation reinforcement of asbestos slate boards, calcium silicate boards, rock wool boards, magnesium carbonate boards, foamed concrete, glass fibers, glass fiber mats, etc.

The adhesive bonded using the resin liquid of the present invention exhibits excellent water-resistant adhesive performance that can strongly withstand immersion in boiling water.

Next, examples of the present invention will be given to demonstrate the effects of the present invention.

Example 1) 202f of formalin with a concentration of 37% and 60f of urea were added in a volume of 5
The mixture was weighed into a 00ml Mitsuro flask, and dibasic sodium phosphate was added thereto to adjust the pH to 9.6, and the temperature was raised to 90C with stirring.

After 3 powder reactions were carried out in step 9, a 20% formic acid aqueous solution was added to adjust the pH of the reaction solution to 5.0, and the condensation reaction was continued.

When the reaction solution was cooled to 1C) and no longer cloudy, tribasic sodium phosphate was added to adjust the pH of the reaction solution to 9.0, and at the same time, the temperature of the reaction solution was cooled to 5 (range).

Next, 32 f of acetone was added to cause a two-powder reaction, and then the temperature was raised to 80'C to cause a three-powder reaction. After that, 20
After reaction with % formic acid aqueous solution, the pH was adjusted to 7.5 and cooled. Acetone modified area resin liquid 100B1 obtained in this way
2 parts of coconut flour, 2 parts of wheat flour, and 10 parts of slaked lime were added to S and kneaded, and 0, 1, 4, and 7 parts of styrene-butadiene rubber (SBR) latex (manufactured by Japan Synthetic Rubber, #U668) were added. It was made into a glue solution.

This size liquid was applied to the front and back surfaces of lauan veneers with a thickness of 2.0 mm and a moisture content of 7 to 8% at a rate of 150 f/I, respectively, and the fiber directions of the lauan veneers of the same thickness were perpendicular to each other. They were overlapped in the same way to form 3 fries, and were temporarily pressed at a pressure of 10k9/C7lf.

Then, 2. at a temperature of 120°C and a pressure of 10k9/Crl. The powder was heated and pressed to make plywood. The adhesive tensile strength of the obtained plywood was measured according to the JAS standard plywood test method, and the results are shown in the following table.

As a control example, the adhesion strength of plywood similarly manufactured using an acetone-modified area resin liquid not mixed with water-based rubber latex and a normal area resin liquid was also shown at the same time. Example 2 Acetone 116y1 Baraform (formaldehyde content 81%) 148fI 137% Formalin 162f was placed in a 4-volume flask with a capacity of 1e, and while stirring, 2% aqueous sodium hydroxide solution was added dropwise little by little to bring the pH of the reaction solution to 8.4.
It was adjusted within the range of ~9.6 (T-B test paper).

Stirring was continued while keeping the temperature around 70C, and a 2% aqueous solution of caustic soda was added to continue the reaction for 3 hours while keeping the pH within the range of &4 to 9.6.

Thereafter, the acetone resin initial condensate obtained by cooling and a commercially available area resin liquid (manufactured by Honen Oil Co., Ltd., UL-002) were uniformly mixed at a ratio of 1:1 (weight ratio) at room temperature.

100ml of acetone modified area resin solution obtained in this way
In contrast, acrylonitrile butadiene rubber (NBR
) Latex (manufactured by Nippon Zeon ■, Nipole #1562)
, 5 parts each of chloroprene rubber (CR) latex (manufactured by Showa Neoprene ■) were mixed separately, and then 5 parts of wheat flour,
Two portions of slaked lime were added to each to form a glue solution.

This size liquid was applied to the front and back surfaces of a lauan veneer with a thickness of 2.0wt and a moisture content of 7 to 8% at a rate of 150y/Trt, respectively, and the lauan veneer of the same thickness was placed so that the fiber directions were perpendicular to each other. They were overlapped and temporarily pressed for 15 minutes at a pressure of 10k9/Cli.

Then, 2. at a temperature of 120 C and a pressure of 10 kg/Cii. The powder was heated and pressed to make plywood.

The adhesive tensile strength of the obtained plywood was measured according to the JAS standard synthesis test method, and the results are shown in the following table.

Claims (1)

[Claims] 1 Formaldehyde 1.5-12 per mole of urea
When cocondensing at a ratio of 0.3 to 3 moles of acetone, (a) acetone is added to the urea resin initial condensate obtained by mixing formaldehyde with urea and heating and condensing the mixture, and if necessary, formaldehyde is added. Add aqueous solution,
Either co-condensation is carried out under an alkaline condition at a temperature of 50 to 90°C and a pH of 8.5 to 12, or (b) urea and formaldehyde and acetone and formaldehyde are preheated and condensed separately, and these initial condensates are heated at room temperature. Or an alkali-curable modified urea resin liquid consisting of a modified urea resin liquid mixed under heating and water-based rubber latex.