JPS5950272B2 - water resistant adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel adhesive composition that cures under alkaline conditions, and its purpose is to provide an inexpensive adhesive composition with excellent water resistance suitable for bonding wood, inorganic molded products, etc. Our goal is to provide adhesives.

Conventionally, area resin has been the cheapest resin among plastics, and for this reason, it has been used in large quantities in adhesives for plywood and particle board.

Area resins are generally subjected to an addition reaction under alkaline conditions,
A condensation reaction is then carried out under acidic conditions. Therefore, when curing the area resin, use an acidic curing agent and adjust the pH to 3.
-6 acidic and harden. When wood is bonded using area resin, excellent bonding strength can be obtained, but water-resistant bonding performance and durable bonding performance cannot be said to be sufficient.

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

However, since melamine 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. Once the remaining 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-resistant adhesive performance and durable adhesive performance be obtained, but most of them are alkaline and have low strength. It can also be effectively used as an adhesive for relatively brittle inorganic molded products.

From this point of view, the present inventors have been conducting research on amino resins that harden under alkalinity. and, first, to)
A ketone-modified area resin liquid whose main components are urea, formaldehyde, and ketones and hardens under alkaline conditions, a powder whose main component is protein that is insoluble in water at room temperature, and f→alkali metal or alkaline earth metal oxides. , developed a water-resistant adhesive mainly consisting of hydroxide or basic salt, and filed a patent application.

The present invention further improves the adhesive performance of the water-resistant adhesive in this prior invention.

That is, the present invention consists of fl) a modified area resin liquid containing urea, formaldehyde, and ketone compounds as main components and hardening under alkaline conditions, middle) aqueous latex, and ←→ powder containing a protein insoluble in room temperature water as a main component. This is a water-resistant adhesive made by adding an alkali metal or alkaline earth metal oxide or basic salt, or a mixture of two or more of them.

The ketone-modified area resin liquid used in the present invention contains, for example, 1.5 to 12 formaldehyde per mole of urea.
A ketone compound selected from acetone, methyl ethyl ketone, acetophenone, cyclohexanone, diacetone acrylamide, diacetone alcohol, etc. is added to the initial condensate of the area resin obtained by mixing in a molar ratio and heating and condensing by a known method. A species or two or more species with urea
It is added at a rate of 0.3 to 3 moles per mole, and the temperature is 50 to
It is manufactured by a method of co-condensation at 90° C. under alkaline conditions of pH 8.5 to 12.

In addition, urea and formaldehyde, as well as a ketone compound and formaldehyde are heated and condensed separately in advance,
A ketone-modified area resin solution is also used, which is prepared by mixing these initial condensates at room temperature or under heating and curing the mixture under alkaline conditions.

Furthermore, if necessary, one or more compounds that react with formaldehyde such as thiourea, ethyleneurea, melamine, acetoguanamine, phenol, resorcinol, etc. may be added in small amounts during the production of the modified area resin liquid. The effects of the present invention can also be obtained with water-soluble polymers having a thickening effect such as starch, dextrin, gum arabic, sodium alginate, sodium polyacrylate, polyacrylic acid amide, carboxymethyl cellulose, polyvinyl alcohol, methyl cellulose, etc. One or more of the substances may be added in small amounts. The first feature of the present invention is to add to this ketone-modified area resin liquid a powder whose main component is a protein that is insoluble in water at room temperature.

A powder substance whose main component is protein that is insoluble in room temperature water is a protein-based powder substance that becomes soluble in a short period of time when added to room temperature water and does not exhibit significant thickening. hand,
For example, high-temperature defatted soybean flour, high-temperature defatted rapeseed meal powder, corn gluten powder, which is not normally used as a filler,
Examples include water-insoluble proteins such as dried blood powder, milk casein, algae protein, bacterial cell protein, etc., or powdered materials containing such proteins as a main component.

Ordinary adhesives use powdered substances as bulking agents, such as low-temperature defatted soy flour, blood albumin, and other proteins that are easily soluble in room-temperature water.

However, when these commonly used protein-based powders that are soluble in room temperature water are added to the ketone-modified area resin solution, oxides, hydroxides, or basic salts of alkali metals or alkaline earth metals are added. When added, the viscosity increases instantaneously and the mixture turns into a gel. However,
As in the present invention, when a powder material mainly composed of proteins insoluble in room temperature water, which is not normally used as a filler, is added, oxides, hydroxides, or basic salts of alkali metals or alkaline earth metals are added. Even when the adhesive is added, no rapid increase in viscosity is observed, and the adhesive is gradually increased in viscosity to obtain a highly viscous adhesive.

In addition, many powdered materials whose main component is protein that is insoluble in water at room temperature are relatively inexpensive, so not only do they have the economical effect of reducing the cost of adhesives, but also the ketone-modified area resin liquid can be applied to adherends. Since it prevents excessive penetration into the inside, it has a remarkable effect on improving temporary adhesion and normal and water-resistant adhesion performance.

A second feature of the present invention is that an aqueous latex is added to the ketone-modified area resin liquid together with a powder whose main component is a protein that is insoluble in water at room temperature.

Aqueous latex means a general aqueous dispersion of natural or synthetic polymers, specifically natural rubber latex, styrene, styrene derivatives, butadiene, acrylonitrile, chloroprene, isoprene, isobutene, acrylic acid, etc. , methacrylic acid ester, vinyl acetate, ethylene, vinyl chloride, vinylidene chloride, etc., or a dispersion of a copolymer made of one or more copolymerizable unsaturated monomers.

Furthermore, latexes obtained by adding carboxyl groups or carboxylic acid salts to these aqueous latexes, hydroxyl groups, amino groups, amide groups, . Latexes to which functional groups such as sulfonic acid groups and epoxy groups have been added can also be used as the aqueous latexes of the present invention.

These water-based latics preferably have the property of forming a more flexible film when a film is formed.
For example, styrene-butadiene copolymer latex is particularly preferred. The water-based latex used in the present invention has the effect of significantly improving the adhesive performance of water-resistant adhesives.

That is, the addition of water-based latex further improves the adhesive strength at room temperature and water resistance. The oxides, hydroxides or basic salts of alkali metals or alkaline earth metals used in the present invention refer to alkali metals such as lithium, potassium, sodium, etc. or alkaline earth metals such as magnesium, calcium, strontium, barium, etc. oxides, hydroxides, carbonates, bicarbonates, silicates, borates, aluminates, zincates, etc. of similar metals, and one or two of these metal compounds exhibiting alkalinity By adding the above to the ketone-modified area resin liquid, the resin liquid can be easily cured.

Among these alkaline metal compounds, oxides of alkaline earth metals such as magnesium and calcium,
Hydroxide has the effect of increasing the water resistance of the adhesive by bonding with the added protein, and is therefore preferable in order to more significantly exhibit the effects of the present invention.

In addition, these alkaline metal compounds include oxides, hydroxides, hydrochlorides, sulfates, nitrates, and phosphates of polyvalent metals such as copper, aluminum, zinc, iron, chromium, molybdenum, etc. Even if salts such as silicates are used or added, the effects of the present invention will not change. The adhesive of the present invention includes (a) a ketone-modified area resin liquid, (b) an aqueous latex, (f) a powder whose main component is protein that is insoluble in water at room temperature, and (d) an alkali metal or alkaline earth metal. It has four essential components: one or a mixture of two or more selected from oxides, hydroxides, and basic salts, and the blending ratio is 100% of the ketone-modified area resin liquid.
Based on parts by weight, 5 to 200 parts by weight of aqueous latex, 5 to 200 parts by weight of a powder whose main component is protein insoluble in water at room temperature, oxides of alkali metals or alkaline earth metals,
The amount of hydroxide or basic salt is preferably 0.5 to 50 parts by weight.

At this time, if the amount of powdery material whose main component is protein that is insoluble in water at room temperature exceeds 200 parts by weight, the water-resistant adhesive performance will decrease, and the alkali metal or alkaline earth used as a curing accelerator will deteriorate. If the amount of the metal oxide, hydroxide or basic salt exceeds 50 parts by weight, the usable life of the adhesive will be significantly shortened, causing a practical problem.

When used, the adhesive of the present invention may be used as a filler based on starch such as wheat flour, barley flour, rice flour, corn starch, tapioca starch, etc., gypsum, diatomaceous earth, clay, zeolite, etc.
The effects of the present invention are not affected by the addition of inorganic fillers such as talc, asbestos, etc., or organic fillers such as walnut shell powder, perilla powder, and wood flour.

The water-resistant adhesive of the present invention can be applied to plywood, veneer cross-layered wood, laminated wood,
Not only is it suitable for adhering wood materials such as particle board, hardboard, and wood panels, but also inorganic molded materials such as asbestos slate board, calcium silicate board, gypsum board, wood wool cement board, foam concrete board, etc. It can also be used for adhesives, and exhibits excellent water-resistant adhesive performance that can withstand strong immersion in boiling water.

Next, examples of the present invention will be given.

Example 1 Acetone 1169, paraform (formaldehyde content 81%) 1489, and 37% formalin 162 g were placed in a four-piece flask with a capacity of 11, and while stirring, a 2% aqueous sodium hydroxide solution was added dropwise little by little to adjust the pH of the reaction solution to 8.4-8.4.
It was adjusted to within the range of 9.6 (TB test paper).

Stirring was continued while maintaining the temperature at around 70°C, and a 2% aqueous sodium hydroxide solution was added to continue the reaction for 3 hours while maintaining the pH within the range of 8.4 to 9.6.

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

To 100 parts (parts by weight, the same applies hereinafter) of the acetone-modified area resin solution obtained in this way, 10 parts of high-temperature defatted soybean flour that is insoluble in room temperature water, 10 parts of magnesium hydroxide powder, and 5 parts of water.
to prepare a size solution, and further add S to this size solution.
0 BR latex (manufactured by Japan Synthetic Rubber, #U668)
．． 10% (weight?, same below), 50%, 100% amount,
Each was added and mixed. Add these pastes to a thickness of 2.01
11 15 each on the front and back sides of lauan veneer with a moisture content of 7 to 8%
Apply at a rate of 0V, stack lauan veneers of the same thickness so that the fiber directions are perpendicular to each other, and apply at a rate of 10kg/Cd.
Temperature 120℃, pressure 1
Plywood was manufactured by heating and pressurizing at 0 kg/Cd for 2.5 minutes.

The tensile adhesive strength of the obtained plywood was measured according to the JAS standard plywood test method.

The results are shown in the table below.

From the above results, it can be seen that the water-resistant adhesive to which the SBR latex of the present invention is added has better normal and water-resistant adhesive performance than the control adhesive to which no SBR latex is added.

Example 2 To 100 parts of the acetone modified area resin solution obtained by the same method as Example 1, 10 parts of corn gluten powder insoluble in room temperature water, 10 parts of slaked lime, and 5 parts of water were added to prepare a sizing solution. Furthermore, polyvinyl acetate resin emulsion (Showa Kobunshi Co., Ltd., Polysol #1000), N
BR Latex (Nippon Zeon), Nipole #1551
) and acrylic ester copolymer latex (manufactured by Nippon Zeon KK, Nipole, LX-814) were added and mixed in an amount of 30% each.

These size solutions were applied at a rate of 150 g/771" to the front and back surfaces of lauan veneers with a thickness of 2.0 mm and a moisture content of 7 to 8%, respectively, and the lauan veneers of the same thickness were made with the fiber directions perpendicular to each other. After overlapping and temporarily compressing at a pressure of 10 n- for 15 minutes, they were heated and pressed at a temperature of 120° C. and a pressure of 10 kg/Clil for 2.5 minutes to produce plywood.

The tensile adhesive strength of the obtained plywood was measured according to the JAS standard plywood test method.

As a control, the tensile adhesive strength of plywood manufactured in the same manner using an adhesive paste without the addition of water-based latex was also measured.

The results are shown in the table below.

From the above results, it can be seen that the water-resistant adhesive to which the water-based latex of the present invention is added has superior normal and water-resistant adhesive performance compared to the control adhesive to which no water-based latex is added.

Claims (1)

[Claims] 1 (a) Ketone-modified area resin liquid, (b) aqueous latex, (c) powder material whose main component is protein that is insoluble in water at room temperature, and (d) oxide of alkali metal or alkaline earth metal, water A water-resistant adhesive consisting mainly of oxides or basic salts.