JP2012201728A - Adhesive composition for lumber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition for lumbers having excellent board properties (low-emitting formaldehyde levels, etc.) while keeping excellent productivity and moldability (curability).SOLUTION: The adhesive composition for lumbers comprising: a resol-type phenol-formaldehyde resin (a); an organic ester compound (b); and wax (c), is provided; being characterized in that: the organic ester compound (b) and the wax (c) are at 0.1-20 pts.wt. and 1-20 pts.wt., respectively, based on 100 pts.wt. of the resol-type phenol-formaldehyde resin (a).

Description

The present invention relates to an adhesive composition for wood, and more particularly to an adhesive composition for particle board.

The use of particleboard is increasing as part of resource recycling in recent years and as part of lowering the cost of residential building materials. Currently, melamine resins or urea resins are mainly used as adhesives for particle boards. However, it is difficult for particle board using melamine resin and urea resin to clear the building standard F ☆☆☆☆. In addition, since these resins have low water resistance, it is difficult to apply them to watering places such as kitchens and under floors. In order to compensate for these drawbacks, 1,4-diphenylmethane diisocyanate (hereinafter referred to as MDI) is used to produce particleboard, but MDI is a mutagen and is not preferred for health reasons. Sometimes, the price of the release agent, which is indispensable from the countermeasure against adhesion, is expensive, and there is a problem of cost. An example of an adhesive that compensates for these drawbacks is phenol resin. Particle boards using phenolic resin have less formaldehyde emission compared to melamine resin and urea resin, have improved water resistance, and have no problem of mutagenesis due to the use of MDI. On the other hand, a slow curing rate is mentioned as a drawback. Since the curing speed is slow, the hot press time becomes long, which causes significant problems in terms of productivity and cost.

Conventional phenol-formaldehyde resin adhesives (hereinafter referred to as phenol adhesives) require higher temperatures and longer time for hot pressing (pressing) when producing particle boards than amino resin adhesives. Because of this, it is a cause of productivity decline. In addition, since caustic soda solution is usually used as a catalyst in the production of phenolic resin, the non-volatile content of the resin is lower than that of amino resin, so that the moisture content of the mat is high, and when the pressure is released after hot pressing. , Puncture is likely to occur. Further, in order to keep the moisture content of the mat low, it is necessary to use an excessively dried chip having a low moisture content.

As a method of rapidly curing at low temperature using a phenol adhesive, the molar ratio of formaldehyde (F) and phenol (P) (hereinafter referred to as F / P molar ratio) is set to 2.5 to 2.8. Although it is known that an effect can be obtained to some extent, there is a problem that the curability is greatly lowered as compared with an actual amino resin adhesive.

In addition, a technique for adding resorcinol, lignin, tannin, etc. to a phenol adhesive has been proposed (see, for example, Patent Document 1). However, these techniques have little effect unless added in a large amount, and if added in a large amount, the increase in viscosity of the prepared solution before chip spraying becomes extremely fast, and there is a problem in productivity.

JP 2000-63787 A

This invention provides the adhesive composition for wood from which a particle board is obtained with the outstanding moldability (curability), adhesiveness, and the amount of formaldehyde emitted low.

Such an object is achieved by the following present inventions (1) to (4).
(1) An adhesive composition for wood comprising a resol type phenol / formaldehyde resin (a), an organic ester compound (b), and a wax (c), the resol type phenol / formaldehyde resin (a) being 100 weights The adhesive composition for wood, wherein the organic ester compound (b) is 0.1 to 20 parts by weight and the wax (c) is 0.1 to 20 parts by weight with respect to parts.
(2) The resol type phenol / formaldehyde resin (a) is obtained by reacting within a molar ratio (F / P) of 1.5 to 2.7 of formaldehyde (F) and phenol (P). The wood adhesive composition according to (1), wherein the pH is in the range of 9 to 13 and the weight average molecular weight is 1000 or more.
(3) The adhesive composition for wood according to (1) or (2), wherein the organic ester compound (b) is any one of carbonates such as propylene carbonate and ethylene carbonate, or a mixture thereof.
(4) The adhesive composition for wood according to (1) or (2), wherein the organic ester compound (b) is any one of phenyl acetate, glycerol triacetate, methyl formate, methyl salicylate, and ethyl butyrate or a mixture thereof. .

The wood adhesive composition of the present invention has excellent board properties (low emission formaldehyde amount, etc.) while maintaining productivity, curability and moldability equivalent to melamine resin and urea resin during particle board production. is there.

Hereinafter, embodiments of the adhesive composition for wood according to the present invention will be described.
The wood adhesive composition according to the present invention is a wood adhesive composition comprising a resol type phenol-formaldehyde resin (a), an organic ester compound (b), and a wax (c), The organic ester compound (b) is 0.1 to 20 parts by weight and the wax (c) is 1 to 20 parts by weight with respect to 100 parts by weight of the resol type phenol / formaldehyde resin (a). .

The resol-type phenol / formaldehyde resin (a) used in the wood adhesive composition of the present invention is usually composed of phenols (P) and aldehydes (F) in an F / P molar ratio of 1.5 to 2.7. Preferably, a value obtained by reacting to a predetermined viscosity in the presence of a basic catalyst as 2.0 to 2.6 can be preferably applied.
Here, when the F / P molar ratio is less than the above lower limit value, the curing of the resol type phenol-formaldehyde resin (a) may be slow. This will cause problems in terms of environmental safety.

Examples of the phenols used to obtain the resol-type phenol / formaldehyde resin (a) used in the wood adhesive composition of the present invention include phenol, cresol, xylenol, resorcinol and the like. You may do it. As formaldehyde, any of formalin (formaldehyde aqueous solution) and paraformaldehyde (solid) may be used, or they may be used alone or in combination.

As the catalyst, a strong base catalyst such as sodium hydroxide is usually used, but it is not particularly limited. The amount of catalyst during the reaction is preferably such that the molar ratio of sodium hydroxide / phenol is 0.1 or more and 1.1 or less. If the value is below the lower limit, the water solubility is low and there is a risk of problems in use during production. On the other hand, when the above upper limit is exceeded, the water resistance in the particle board characteristics is lowered, so that there is a high possibility that the quality will be abnormal. Reaction conditions for reacting phenols with aldehydes are not particularly limited, but it is preferable to carry out a condensation reaction under normal reflux or at a temperature of 70 ° C. or higher until a predetermined viscosity is reached.

Regarding the pH of the resol-type phenol / formaldehyde resin (a), it is difficult to maintain water solubility when 9 to 13 that maintain water solubility necessary for productivity is preferably less than 9. On the other hand, if the pH exceeds 13, there is a high possibility of causing a decrease in water resistance as described above.
Further, in the case of a resin having a weight average molecular weight of less than 1000, the effect of the present invention cannot be sufficiently obtained because the curing speed of the resin itself is significantly slower than that of melamine resin or the like.

The organic ester compound (b) blended in the wood adhesive composition of the present invention is a compound having an ester bond in the molecule and is not particularly limited. For example, carbonate compounds such as propylene carbonate and ethylene carbonate are desirable, but other organic ester compounds such as phenyl acetate, glycerol triacetate, methyl formate, methyl salicylate, and ethyl butyrate are not particularly limited.

The compounding quantity of an organic ester compound (b) is 0.1-20 weight part with respect to 100 weight part of resol type | mold phenol formaldehyde resin (a), More preferably, it is 0.1-15 weight part. If it is less than 0.1, the effect on the curability is small and the effect of improving the particle board characteristics is small. On the other hand, when the amount is 20 parts by weight or more, the curing speed is increased, so that the increase in viscosity during particle production is large, and the productivity is greatly reduced.

Although it does not specifically limit as wax (c) mix | blended with the adhesive agent for woods of this invention, For example, organic paraffin etc. are mainly used. Thereby, the water resistance of the particle board can be improved.
The blending amount of the wax is 0.1 to 20 parts by weight with respect to 100 parts by weight of the resol type phenol / formaldehyde resin (a), but is not particularly limited. When the amount is larger than the upper limit value, the curability is hindered and the particle board characteristics are deteriorated. On the other hand, when the amount is less than the lower limit value, the effect cannot be sufficiently obtained.

Although the raw material of the wood chip used for the particle board in the case of using the present wood adhesive is usually used by pulverizing waste materials or the like, it is not particularly limited. Of the particle board divided into three layers, the surface layer uses a relatively small chip and the inner layer uses a relatively large chip. Also, after spraying the adhesive composition, which is an adhesive, with the resin solid content, the surface layer is 10 to 20% and the inner layer is 5 to 15% while flowing the chips using a stirring device, etc., the predetermined press conditions Particleboard is obtained by molding with

In the present specification, the production examples, examples, and modes are for supporting the understanding of the contents of the invention according to the present application, and the present invention is not limited in any way by the description. “Parts” indicates “parts by weight” and “%” indicates “% by weight”.

Production Example of Resol Type Phenol / Formaldehyde Resin (a) 259 parts of phenol, 446 parts of 37% formalin (F / P molar ratio: 2.0), 220 parts of 30% aqueous sodium hydroxide (sodium hydroxide / phenol molar ratio) = 0.6), and 75 parts of water were charged and reacted at 80 ° C. with a B-type viscometer until the viscosity at 25 ° C. reached about 200 mPa · s to obtain a resol type phenol / formaldehyde resin having a pH of 11.5. It was.

Examples 1-3
In 100 parts of the resol-type phenol / formaldehyde resin (a) obtained in the above production example, propylene carbonate and wax (c) as the organic ester compound (b) were blended in the respective parts shown in Table 1 to obtain a preparation solution.
As the wax, Cellozol Q-755 (solid content: 45%) manufactured by Chukyo Yushi Co., Ltd. was used.

Comparative Example 1
In 100 parts of the resol-type phenol / formaldehyde resin (a) obtained in the above production example, the wax (c) was blended in the number of parts shown in Table 1 to obtain a mixed solution.

Evaluation was carried out using the preparations obtained in the above examples and comparative examples.
Formulation stability:
The stability of the mixed solution was determined to be acceptable when the viscosity after standing for 1 hour at 30 ° C. was less than 3 times the initial viscosity and the change with time was suppressed. Further, the moisture content of the chip was adjusted to 5 to 15%, and the solid resin content of the surface layer was adjusted to 15%, and the solid resin content of the inner layer was adjusted to 7.5%.
Formability:
The pressing conditions were a press temperature of 180 ° C., a thickness of Examples 1 to 3 and Comparative Examples 1 to 3 with a pressing time of 12 seconds / mm, and Example 4 with a pressing time of 20 seconds / mm. The target thickness was set to 15 mm.

Formability (= curability) was determined by visual inspection of punctures on the board after hot pressing, and those without punctures were accepted and those with punctures were rejected.
Board characteristics:
The measuring method of bending strength at the time of wetness and formaldehyde emission was measured according to JIS A 5908 (P type, B test).

From the results of Examples 1 and 2 shown in Table 1, the wood adhesive composition of the present invention has excellent moldability (curability), adhesiveness, pot life of the preparation liquid during production, and low formaldehyde emission. It is clear that this is an adhesive composition for wood such as particle board.
Therefore, by using the wood adhesive composition of the present invention for production, the press time can be shortened and productivity can be improved.
In the case of Comparative Examples 1 and 2, since the curability was slow, it was punctured during molding, and a molded product was not obtained. On the other hand, in Comparative Example 3, since the curing rate was too high, the viscosity of the preparation liquid was remarkably increased, and it was impossible to spray the resin on the chip, and production was impossible.
In Comparative Example 4, the molding was possible, but the productivity was significantly lowered because the pressing time was significantly increased.

In the present invention, when the conventional phenol resin was used for the productivity, the curing rate was slow and could not be used, but the present invention significantly improved the curability as compared with the conventional phenol resin, and in a short time. It is useful as a wood adhesive that can be molded and can be used to obtain a particle board that can clear F ☆☆☆☆.

Claims (4)

An adhesive composition for wood comprising a resol type phenol / formaldehyde resin (a), an organic ester compound (b), and a wax (c), the resol type phenol / formaldehyde resin (a) per 100 parts by weight The organic ester compound (b) is 0.1 to 20 parts by weight, and the wax (c) is 0.1 to 20 parts by weight. The resol type phenol / formaldehyde resin (a) is obtained by reacting within a molar ratio (F / P) of 1.5 to 2.7 of formaldehyde (F) and phenol (P), and pH Is in the range of 9 to 13, and the weight average molecular weight is 1000 or more, the adhesive composition for wood according to claim 1. The wood adhesive composition according to claim 1 or 2, wherein the organic ester compound (b) is any one of carbonates such as propylene carbonate and ethylene carbonate, or a mixture thereof. The adhesive composition for wood according to claim 1 or 2, wherein the organic ester compound (b) is any one of phenyl acetate, glycerol triacetate, methyl formate, methyl salicylate, and ethyl butyrate, or a mixture thereof.