JP2022113657A - Adhesive composition for wood, adhesive kit for wood, woody material and method for producing the same - Google Patents

Abstract

To provide an adhesive composition for wood that can express sufficient adhesive strength under cold pressing or hot pressing at low temperature in the production of woody materials such as plywood.SOLUTION: An adhesive composition for wood contains a secondary reaction resol type phenol resin in which a novolac phenolic resin has been made into a resol, an organic acid ester, and resorcinol.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to an adhesive composition for wood, an adhesive kit for wood, a woody material, and a method for producing the same.

2. Description of the Related Art Resol-type phenolic resins (alkali phenolic resins) obtained by reacting phenols and aldehydes in the presence of an alkali catalyst have been known as adhesives for bonding wooden veneers in the production of plywood.
In order to enhance the curability of the resol-type phenolic resin, a curing accelerator may be added to the resol-type phenolic resin. Sodium carbonate, propylene carbonate, ethylene carbonate, γ-butyl lactone, ethyl butyrate and the like are known as curing accelerators (Patent Documents 1 to 5).

JP-A-2000-117704 Japanese Patent Application Laid-Open No. 2002-018808 Japanese Patent Application Laid-Open No. 2002-137201 JP 2006-257271 A Japanese Unexamined Patent Application Publication No. 2012-201728

However, in Patent Documents 1 to 5, although the curability of the resol-type phenolic resin is improved to some extent by the addition of the curing accelerator, plywood production is carried out at a high hot pressing temperature exceeding 100°C. Considering the productivity of plywood, it is desirable that the plywood can be sufficiently hardened at a lower hot pressing temperature without prolonging the hot pressing time, or at a cold pressing to develop sufficient adhesive strength.

The present invention provides an adhesive composition for wood and an adhesive kit for wood that can exhibit sufficient adhesive strength even under cold pressure or hot pressure at a low temperature in the production of woody materials such as plywood, and sufficient adhesion even at low heat pressure temperatures. An object of the present invention is to provide a wooden material having strength and a method for manufacturing the same.

As a result of extensive studies, the present inventors have found that the above problems can be solved by combining a specific resol-type phenolic resin, an organic acid ester, and resorcinol, and have completed the present invention.

The present invention has the following aspects.
[1] An adhesive composition for wood containing a secondary reaction resol-type phenolic resin obtained by converting a novolac-type phenolic resin into a resol, an organic acid ester, and resorcinol.
[2] The adhesive composition for wood according to [1], wherein the organic acid ester is at least one selected from the group consisting of lactones, monocarboxylic acid esters, dicarboxylic acid monoesters and dicarboxylic acid diesters.
[3] The organic acid ester is a carbonate such as ethylene carbonate, propylene carbonate, or dimethyl carbonate; from the group consisting of ethyl acetate, methyl butyrate, ethyl butyrate, ethyl formate, methyl salicylate, ethyl acetoacetate, dimethyl succinate, diethyl succinate, dimethyl adipate, diethyl adipate, dimethyl glutarate, diethyl glutarate and diethyl malonate The adhesive composition for wood according to the above [1] or [2], which is at least one selected.
[4] The organic acid ester contains at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, γ-butyrolactone, α-acetolactone, β-propiolactone, triacetin and ethylene glycol diacetate. , the adhesive composition for wood according to any one of the above [1] to [3].
[5] Any one of [1] to [4], wherein the content of the organic acid ester is 1.0 to 20.0 parts by mass with respect to 100 parts by mass of the secondary reaction resol-type phenolic resin. Adhesive composition for wood.
[6] For wood according to any one of [1] to [5], wherein the content of the resorcinol is 1.0 to 10.0 parts by mass with respect to 100 parts by mass of the secondary reaction resol-type phenolic resin. adhesive composition.
[7] The adhesive composition for wood according to any one of [1] to [6], wherein the secondary reaction resol-type phenolic resin has a pH of 10.0 to 13.5.
[8] The adhesive composition for wood according to any one of [1] to [7], wherein the secondary reaction resol-type phenolic resin has a weight average molecular weight of 2,000 to 10,000.
[9] A first container containing a first agent containing a secondary reaction resol-type phenolic resin obtained by converting a novolac-type phenolic resin into a resol;
An adhesive kit for wood, comprising a second container containing a second agent containing an organic acid ester and resorcinol.
[10] A woody material in which two or more pieces of wood are bonded via a cured product of the adhesive composition for wood according to any one of [1] to [8].
[11] The wooden material according to [10], which is plywood.
[12] The wooden material of [10] above, which is a laminated lumber.
[13] A step of preparing an adhesive composition for wood by mixing a secondary reaction resol-type phenolic resin obtained by converting a novolac-type phenolic resin into a resol, an organic acid ester, and resorcinol;
a step of stacking a plurality of woods via the adhesive composition for wood to obtain a laminate;
a step of applying cold pressure or hot pressure to the laminate to cure the adhesive composition for wood.

According to the present invention, an adhesive composition for wood that can exhibit sufficient adhesive strength even with cold pressure or hot pressure at low temperature in the production of wood materials such as plywood, and sufficient adhesive strength even with cold pressure or hot pressure at low temperature. It is possible to provide a wooden material having

4 is a graph showing the results of Test Example 1 (horizontal axis: elapsed days, vertical axis: viscosity). Graph showing the results of Test Example 2 (horizontal axis: amount of ester added, vertical axis: gelling time). Graphs showing the results of Examples 1 to 5 and Comparative Examples 1 to 5 (horizontal axis: resin pH, vertical axis: adhesive strength). Graphs showing the results of Examples 7 to 11 and Comparative Examples 7 to 11 (horizontal axis: F/P molar ratio, vertical axis: adhesive strength). Graph showing the results of Examples 3, 14 to 17, and Comparative Example 14 (horizontal axis: content of resorcinol, vertical axis: adhesive strength, gelation time). Graph showing the results of Examples 3, 18 to 23, and Comparative Example 15 (horizontal axis: content of propylene carbonate, vertical axis: adhesive strength, gelation time). Graphs showing the results of Examples 24 to 32 and Comparative Example 15 (horizontal axis: content of triacetin, vertical axis: adhesive strength, gelling time). Graph showing the results of Test Example 3 (horizontal axis: cold pressing time, vertical axis: adhesive strength). 5 is a graph comparing the adhesive strengths of Example 3 and Comparative Examples 16, 18, and 19; 4 is a graph comparing the adhesive strengths of Examples 27, 17, 20, and 21;

In the present invention, pH is a value at 25°C unless otherwise specified.
Viscosity is a value measured with an E-type viscometer at 25°C.
The weight average molecular weight (hereinafter also referred to as "Mw") of the phenolic resin (secondary reaction resol type phenolic resin, novolac type phenolic resin) is measured by gel permeation chromatography (hereinafter also referred to as "GPC"). , are values converted to standard polystyrene.
A solid content is a non-volatile matter. The non-volatile content is the residue after heating 1.5 g of the sample at 135° C. for 1 hour.
A specific method for measuring the solid content concentration (non-volatile content concentration) of a sample is shown below.
Weigh the mass C ₁ (g) of an aluminum foil plate (inner diameter 50 mm, height 15 mm), accurately weigh the sample there so that it becomes 1.5 ± 0.1 g, and dry the specific mass of the sample. Let the previous sample mass be S (g). Place this aluminum foil dish in a thermostatic chamber pre-maintained at 135 ± 1 ° C, dry it for 60 ± 2 minutes, allow it to cool in a desiccator, and measure its mass C ₂ (g) . From the result, the sample mass D after drying (the mass of the sample remaining on the aluminum foil plate after drying) (g) is calculated by the following formula (1), and the solid content concentration is calculated by the following formula (2). do.
D=C ₂ -C ₁ (1)
Solid content concentration (mass%) = D / S × 100 (2)

[Adhesive composition for wood]
An adhesive composition for wood according to one aspect of the present invention (hereinafter also referred to as "this composition") contains a secondary reaction resol-type phenolic resin, an organic acid ester, and resorcinol.
The present composition may further contain components other than the secondary reaction resol-type phenolic resin, organic acid ester and resorcinol, if desired.

<Secondary reaction resol type phenolic resin>
The secondary reaction resol-type phenolic resin is a resin obtained by converting a novolac-type phenolic resin into a resol. Specifically, it is a reaction (secondary reaction, resol-type reaction) product of a novolac-type phenolic resin and an aldehyde in the presence of an alkali catalyst.
A novolac-type phenolic resin is a reaction product (primary reaction, novolac-type reaction) of phenols and aldehydes in the presence of an acid catalyst.

The novolac-type phenolic resin includes a phenol condensate in which two or more phenolic aromatic rings are bonded via a methylene group. In the secondary reaction, aldehydes are added to the aromatic ring of the phenol condensate to form methylol groups, and some of the methylol groups thus formed react with other phenol condensates to increase the molecular weight. Therefore, the secondary reaction resol-type phenolic resin contains a phenol condensate having a methylol group and a higher molecular weight than the phenolic condensate contained in the novolac-type phenolic resin.
Secondary reaction resol-type phenolic resins undergo novolac-type phenolic resins, so compared to resol-type phenolic resins obtained by reacting phenols and aldehydes only in the presence of an alkali catalyst, they have a low content of three nuclei or less. The content of molecular weight components is small, and the average molecular weight of the entire resin tends to be high.

Phenols are compounds having an aromatic ring and a hydroxyl group bonded to the aromatic ring. etc.), polyaromatic ring phenols (each naphthol of α, β, etc.), polyhydric phenols (bisphenol A, bisphenol F, bisphenol S, pyrogallol, resorcinol, catechol, hydroquinone, etc.). These phenols may be used individually by 1 type, and may use 2 or more types together.
Phenols other than resorcinol are preferred from the viewpoint of storage stability of the secondary reaction resol type phenol resin. Practical substances other than resorcinol as phenols are phenol, o-, m-, and p-cresols, and isomers of xylenol.

Aldehydes are at least one compound selected from the group consisting of compounds having a formyl group and multimers thereof, and examples thereof include formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, salicylaldehyde, glyoxal and the like. These aldehydes may be used individually by 1 type, and may use 2 or more types together. Among these, practical substances are formaldehyde and paraformaldehyde.

The acid catalyst used for the primary reaction is not particularly limited as long as the primary reaction proceeds. Examples include organic acids such as sulfonic acid, and organic acid salts such as zinc acetate and zinc borate. These acid catalysts may be used individually by 1 type, and may use 2 or more types together.

The amount of acid catalyst used is preferably 0.05 to 2.0 parts by mass, more preferably 0.1 to 1.0 parts by mass, per 100 parts by mass of phenols. If the amount of acid catalyst used is at least the above lower limit, a sufficient reaction rate can be obtained, and if it is at most the above upper limit, the reaction can be easily controlled.
In addition, in this specification, preferable upper limit and lower limit can be combined suitably. For example, the acid catalyst may be used in an amount of 0.05 to 1.0 parts by mass or 0.1 to 1.0 parts by mass with respect to 100 parts by mass of the phenols.

The molar ratio of aldehydes/phenols (hereinafter also referred to as “F/P molar ratio”) in the novolak-type phenolic resin is preferably 0.6 to 0.9, more preferably 0.7 to 0.8. If the F/P molar ratio in the novolak-type phenolic resin is at least the above lower limit, the amount of aldehydes during the resol formation reaction (during the secondary reaction) can be reduced, and heat generation during the reaction can be suppressed. If it is equal to or less than the upper limit, gelation during the novolak reaction (during the primary reaction) can be suppressed.

The Mw of the novolak-type phenol resin is preferably 1,000 to 8,000, more preferably 1,500 to 6,000. If the Mw of the novolac-type phenolic resin is within the above range, the Mw of the secondary reaction resol-type phenolic resin tends to be within the preferred range described below.

The alkali catalyst used for the secondary reaction is not particularly limited as long as it can promote the secondary reaction, and various alkaline substances can be used. Specific examples include hydroxides of alkali metals such as sodium and potassium (sodium hydroxide, potassium hydroxide, etc.), oxides and hydroxides of alkaline earth metals such as calcium, magnesium, and barium, sodium carbonate, and ammonia. Inorganic alkaline substances such as; tertiary amines such as triethylamine and trimethylamine; DBU (1,8-diazabicyclo[5.4.0]undec-7-ene); ] organic alkaline substances such as cyclic amines such as nona-5-ene); These alkali catalysts may be used individually by 1 type, and may use 2 or more types together.

The preferred amount of the alkali catalyst to be used is defined by the alkali catalyst/phenol molar ratio (hereinafter also referred to as "alkali/P molar ratio").
The alkali/P molar ratio is preferably 0.25 to 0.45, more preferably 0.30 to 0.40. If the alkali/P molar ratio is at least the above lower limit, a secondary reaction resol-type phenolic resin can be obtained quickly, and if it is at most the above upper limit, the secondary reaction can be easily controlled.

The F/P molar ratio in the secondary reaction resol type phenolic resin is preferably 2.0 to 2.6, more preferably 2.1 to 2.5.
Here, the F/P molar ratio in the secondary reaction resol type phenolic resin is the molar ratio of the total amount of aldehydes used in the primary reaction and secondary reaction to the phenols used in the primary reaction. Hereinafter, this molar ratio is also referred to as "final F/P molar ratio".
If the final F/P molar ratio is at least the above lower limit, a sufficient amount of methylol groups are present in the secondary reaction resol-type phenolic resin, and low-molecular-weight components of three nuclei or less are sufficiently reduced. Therefore, the bonding strength between wood is better. If the final F/P molar ratio is equal to or less than the above upper limit, the amount of formaldehyde emitted is reduced.

The weight average molecular weight (Mw) of the secondary reaction resol type phenol resin is preferably 2,000 to 10,000, more preferably 3,000 to 10,000, further preferably 3,000 to 9,000. 000 to 9,000 are particularly preferred, and 5,000 to 8,000 are most preferred. If the weight-average molecular weight of the secondary reaction resol-type phenolic resin is at least the above lower limit, the adhesive strength between wood tends to be more excellent. Workability tends to improve.
The weight-average molecular weight of the secondary reaction resol-type phenolic resin is preferably about 2 to 5 times the weight-average molecular weight before resolization, that is, the weight-average molecular weight of the starting novolac-type phenolic resin.

The ratio of the trinuclear or less low-molecular-weight component to the total of the polynuclear and mononuclear bodies contained in the secondary reaction resol-type phenolic resin is preferably 5 area% or less, more preferably 3 area% or less. preferable. The lower limit is not particularly limited, and may be 0 area %. If the proportion of the low-molecular-weight component is equal to or less than the upper limit, the adhesion strength between woods will be more excellent.
The ratio (area %) of trinuclear or lower low-molecular-weight components is the total ratio of trinuclear, binuclear and mononuclear components, and is calculated from gel permeation chromatography (GPC).
A polynuclear compound means a component having two or more phenol skeletons, for example, a phenol condensate, an unreacted phenol having two or more phenol skeletons, and a methylol compound obtained by adding a methylol group to this phenol. mentioned. At least part of the polynuclear is a phenol condensate. A trinuclear body means a component having three phenol skeletons among polynuclear bodies. A binuclear compound means a component having two phenol skeletons among polynuclear compounds. A mononuclear compound means a component having one phenol skeleton, and includes, for example, unreacted phenols having one phenol skeleton, and methylol compounds obtained by adding methylol groups to these phenols.
The ratio of low molecular weight components having three nuclei or less can be adjusted by the charged molar ratio of phenols and aldehydes.

A secondary reaction resol type phenolic resin typically contains a phenol condensate, an alkaline substance and water.
Examples of alkaline substances include the aforementioned alkaline catalysts.
At least part of the alkaline material is usually an alkaline catalyst used for secondary reactions. A portion of the alkaline substance may have been added after the secondary reaction (eg, during preparation of the composition).

The molar ratio of alkaline substance/phenol in the secondary reaction resol type phenol resin is preferably 0.4 to 1.0, more preferably 0.5 to 0.9, and even more preferably 0.6 to 0.8.
Here, the molar ratio of the alkaline substance/phenols in the secondary reaction resol type phenolic resin is the total amount of phenols used in the primary reaction, the alkali catalyst used in the secondary reaction and the amount added after the secondary reaction. It is the molar ratio of the total amount of alkaline substances. Hereinafter, this molar ratio is also referred to as "final alkaline substance/phenol molar ratio". When no alkaline substance is added after the secondary reaction, the total amount of the alkali catalyst used in the secondary reaction and the alkaline substance added after the secondary reaction is the amount of the alkali catalyst used in the secondary reaction.
If the final molar ratio of alkaline substance / phenol is at least the above lower limit, the amount of free formaldehyde can be reduced without significantly increasing the molecular weight (without increasing the viscosity), and if it is below the above upper limit , a sufficient reaction rate can be obtained and is easy to control.

The pH of the secondary reaction resol type phenolic resin is preferably 10.0 to 13.5, more preferably 11.0 to 13.5, even more preferably 11.5 to 12.5. If the pH is at least the above lower limit, the solubility of the secondary reaction resol type phenolic resin is more excellent, and if it is at most the above upper limit, a constant curing rate can be maintained.

The viscosity of the secondary reaction resol type phenol resin is preferably 50 to 3,000 mPa s, more preferably 50 to 2,000 mPa s, still more preferably 50 to 1,000 mPa s, and 100 to 1,000 mPa s. is particularly preferred, and 100 to 400 mPa·s is most preferred. If the viscosity of the secondary reaction resol-type phenolic resin is at least the above lower limit, the viscosity of the present composition can be easily adjusted.
The viscosity of the secondary reaction resol type phenolic resin can be adjusted by adjusting the reaction time and the like in the secondary reaction.

The solid content concentration of the secondary reaction resol type phenol resin is preferably 20 to 60% by mass, more preferably 30 to 55% by mass. If the solid content concentration of the secondary reaction resol type phenolic resin is within the above range, the viscosity of the secondary reaction resol type phenolic resin can easily be set within the preferable range described above. The solid content concentration of the secondary reaction resol-type phenolic resin may further be 35 to 55% by mass, or 30 to 50% by mass.

The secondary reaction resol type phenolic resin can be produced, for example, by the method described in JP-A-2018-53131.

<Organic acid ester>
The organic acid ester functions as a curing accelerator. It is believed that when cold pressure or hot pressure is applied, the organic acid ester is hydrolyzed to form an organic acid, and the pH of the composition is lowered, thereby accelerating the curing reaction.

Examples of organic acid esters include carbonates such as ethylene carbonate, propylene carbonate and dimethyl carbonate; lactones such as γ-butyrolactone, α-acetolactone and β-propiolactone; triacetin, ethylene glycol diacetate, triethylene glycol diacetate; Monocarboxylic acid esters such as acetate, ethyl acetate, methyl butyrate, ethyl butyrate, ethyl formate, methyl salicylate, ethyl acetoacetate; dimethyl succinate, diethyl succinate, dimethyl adipate, diethyl adipate, dimethyl glutarate, diethyl glutarate , diethyl malonate, and other dicarboxylic acid monoesters or dicarboxylic acid diesters. These organic acid esters may be used alone or in combination of two or more.

Among the above organic acid esters, at least one selected from the group consisting of carbonate esters, lactones and carboxylic acid esters of polyols is preferable because of its excellent low-temperature curability and relatively high boiling point. At least one selected from the group consisting of ethylene, propylene carbonate, dimethyl carbonate, γ-butyrolactone, α-acetolactone, β-propiolactone, triacetin and ethylene glycol diacetate is more preferred. Among these, at least one selected from the group consisting of propylene carbonate, γ-butyrolactone, triacetin and ethylene glycol diacetate is preferable in that a curing acceleration effect can be obtained with a smaller amount. If necessary, organic acid esters other than these may be used in combination.

<Other ingredients>
Other ingredients are not particularly limited, and include, for example, various additives and sugars.
As the additive, a component known as a component of an adhesive composition for wood can be appropriately used. Examples of additives include curing accelerators other than organic acid esters, thickeners, bulking agents, viscosity modifiers, and the like.
Other hardening accelerators include, for example, alkali metal carbonates such as sodium carbonate, sodium hydrogencarbonate, potassium carbonate and potassium hydrogencarbonate.
Examples of thickeners include polysaccharides such as wheat flour.
Bulking agents include, for example, alkaline earth metal carbonates such as calcium carbonate.
Examples of viscosity modifiers include high boiling water-soluble organic solvents such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexylene glycol, and phenoxyethanol. is mentioned.

When the present composition contains sugars, particularly reducing sugars, the amount of formaldehyde emitted during curing of the present composition or from the cured product can be reduced, and the color tone of the cured product can be lightened.
The reducing sugar is not particularly limited, and may be, for example, monosaccharide, oligosaccharide, dextrin, and the like. Here, "oligosaccharide" means a combination of 2 or more and 10 or less monosaccharides, and "dextrin" includes the general concept of maltodextrin, and refers to a sugar composition with a DE of 20 or less.
Monosaccharides include, for example, glucose, fructose, mannose, galactose, ribose, xylose and the like.
Oligosaccharides include, for example, disaccharides such as maltose, lactose and isomaltose; trisaccharides such as maltotriose; etc.
Any one of these reducing sugars may be used alone, or two or more thereof may be used in combination.

<Composition of the present composition>
In the present composition, the content of the organic acid ester is preferably 1.0 to 20.0 parts by mass, more preferably 1.0 to 10.0 parts by mass, relative to 100 parts by mass of the secondary reaction resol-type phenolic resin. . If the content of the organic acid ester is at least the above lower limit, when applying cold pressure or hot pressure at a preferred temperature (25 to 80 ° C.) described later when producing a wood material using the present composition, the present Curability of the composition and adhesive strength between wood tend to be better. If the content of the organic acid ester is equal to or less than the above upper limit, the adhesion strength between woods is superior when cold pressure or hot pressure is applied at the above preferable temperature, and the thickening of the composition is suppressed, making it usable. It tends to take longer.

There is a tendency that the lower the temperature at which the cold pressure or hot pressure is applied, the higher the preferred content of the organic acid ester.
When the temperature when applying cold pressure or hot pressure is within 70 ° C. ± 10 ° C., the content of the organic acid ester is 0.1 to 10.0 mass parts with respect to 100 parts by mass of the secondary reaction resol type phenolic resin. is more preferably 0.1 to 8.0 parts by mass, particularly preferably 0.1 to 4.0 parts by mass, and most preferably 0.5 to 3.0 parts by mass.
When the temperature when applying cold pressure or hot pressure is within 50 ° C. ± 10 ° C., the content of the organic acid ester is 0.1 to 15.0 mass parts per 100 parts by mass of the secondary reaction resol type phenolic resin. is more preferably 0.1 to 12.0 parts by mass, particularly preferably 1.0 to 5.0 parts by mass, and most preferably 2.0 to 4.0 parts by mass.
When the temperature when applying cold pressure or hot pressure is within 30 ° C. ± 10 ° C., the content of the organic acid ester is 2.0 to 20.0 mass parts per 100 parts by mass of the secondary reaction resol type phenolic resin. 2.0 to 17.0 parts by weight is more preferred, 2.0 to 6.0 parts by weight is particularly preferred, and 3.0 to 5.0 parts by weight is most preferred.

The preferred content of the organic acid ester may vary depending on the type of the organic acid ester as well as the temperature at which cold pressure or hot pressure is applied.
For example, the preferred content of propylene carbonate and γ-butyrolactone tends to be less than the content of triacetin and ethylene glycol diacetate.
Taking the case where the temperature when applying cold pressure or hot pressure is within 50 ° C. ± 10 ° C. as an example, when the organic acid ester is propylene carbonate or γ-butyrolactone, the content of the organic acid ester is secondary More preferably 1.5 to 4.5 parts by mass, more preferably 2.0 to 4.0 parts by mass, per 100 parts by mass of the reactive resol type phenolic resin. When the organic acid ester is triacetin or ethylene glycol diacetate, the content of the organic acid ester is more preferably 2.0 to 20.0 parts by mass with respect to 100 parts by mass of the secondary reaction resol type phenolic resin. 0 to 17.0 parts by weight is more preferred, 2.0 to 10.0 parts by weight is particularly preferred, and 3.0 to 8.0 parts by weight is most preferred. When the organic acid ester is a mixture of dimethyl glutarate, dimethyl succinate and dimethyl adipate, the content of the organic acid ester is 4.0 to 20.0 with respect to 100 parts by mass of the secondary reaction resol type phenolic resin. Parts by weight are more preferred, and 6.0 to 20.0 parts by weight is even more preferred. When the content of the organic acid ester is at least the above lower limit, the curability of the present composition and the adhesive strength between wood tend to be more excellent when the temperature at which cold pressure or hot pressure is applied is within the above range. There is If the content of the organic acid ester is equal to or less than the above upper limit, the adhesion strength between woods is superior when the temperature at which cold pressure or hot pressure is applied is within the above range, and the viscosity of the present composition is increased. is suppressed and the pot life tends to be longer.

The content of resorcinol is preferably 0.5 to 10.0 parts by mass, more preferably 0.5 to 8.0 parts by mass, more preferably 0.5 to 7.0 parts by mass with respect to 100 parts by mass of the secondary reaction resol type phenolic resin. 0 parts by weight is more preferred, 0.5 to 5.5 parts by weight is even more preferred, 1.0 to 5.0 parts by weight is particularly preferred, and 1.5 to 4.5 parts by weight is most preferred. When the content of resorcinol is within the above range, the curability of the present composition and the adhesive strength between wood tend to be more excellent.

The total ratio of the solid content of the secondary reaction resol-type phenolic resin, the organic acid ester and the resorcinol to the solid content of 100% by mass of the present composition is preferably 60.0% by mass or more, and more preferably 70.0% by mass or more. Preferably, it may be 100% by mass.

The pH of the present composition is preferably 10.5-13.5, more preferably 11.0-13.0. When the pH is at least the above lower limit, the penetration into wood is good and the adhesion strength is superior.

The viscosity of the present composition is preferably 100 to 3,000 mPa·s, more preferably 500 to 2,000 mPa·s. When the viscosity of the present composition is at least the above lower limit value, sufficient adhesive strength can be maintained when wood is temporarily bonded, and when it is at most the above upper limit value, the coatability of the present composition is more excellent.

The solid content concentration of the present composition is preferably 30.0 to 60.0% by mass, more preferably 35.0 to 55.0% by mass, even more preferably 40.0 to 50.0% by mass. If the solid content concentration of the present composition is within the above range, the viscosity of the present composition can easily be within the preferred range described above.

<Method for preparing the present composition>
The composition can be prepared by mixing the components described above. For example, the present composition can be obtained by mixing a secondary reaction resol-type phenolic resin, an organic acid ester, resorcinol, and, if necessary, additional water, an alkaline substance, and other components.
When the secondary reaction resol type phenolic resin is mixed with at least one of the organic acid ester and resorcinol, thickening due to gelation of the secondary reaction resol type phenolic resin tends to proceed, so the secondary reaction resol type Phenolic resin, organic acid ester and resorcinol are preferably mixed immediately before production of the woody material. The time from mixing the secondary reaction resol-type phenolic resin with at least one of the organic acid ester and resorcinol to applying the present composition to wood is preferably 1 hour or less.
The organic acid ester and resorcinol may be individually mixed with the secondary-reaction resol-type phenolic resin, or may be pre-mixed before mixing with the secondary-reaction resol-type phenolic resin. It is preferable that the organic acid ester and the resorcinol are mixed in advance from the viewpoint that the manufacturing process of the woody material is simpler.
As a method for preparing the present composition, a method of mixing the first agent and the second agent of the adhesive kit for wood described below is suitable.

The composition is for wood and is used to bond wood together. More on wood later. A wood material is obtained by bonding two or more pieces of wood together with the present composition. The composition can also be said to be for the production of wood-based materials.

Since the present composition contains a secondary reaction resol-type phenolic resin, an organic acid ester, and resorcinol, even if the hot pressing temperature is low in the production of wood materials such as plywood, or even if only cold pressing, it is relatively stable. Sufficient adhesive strength can be developed by spending time.
For example, conventionally, the heat and pressure temperature is about 120 to 140° C. when plywood is produced using a resol type phenolic resin. On the other hand, when producing wood materials such as plywood using the present composition, even if the hot pressing temperature is less than 120 ° C. (for example, about 20 to 100 ° C. or about 30 to 100 ° C.), The adhesive strength is fully cured with a heat and pressure time of .
Therefore, according to the present composition, the energy cost in the production of woody materials can be reduced.
The reason for the above effect is that the secondary reaction resol type phenolic resin contains less low-molecular-weight components of three nuclei or less than the resol type phenolic resin obtained by reacting phenols and aldehydes only with an alkali catalyst. Curing is relatively fast due to its large molecular weight, and the presence of resorcinol together with the secondary reaction resol-type phenolic resin and organic acid ester further improves reactivity, especially at low temperatures. is incorporated into the skeleton of the cured product, and resorcinol reacts quickly, but since it is basically a monomer, it has good permeability to wood, and it is thought that it provides a firm anchoring effect when bonding to wood.

〔kit〕
An adhesive kit for wood according to one aspect of the present invention (hereinafter also referred to as "this kit") comprises a first container containing a first agent and a second container containing a second agent. Prepare.

The first agent contains a secondary reaction resol type phenolic resin. The first agent preferably does not contain an organic acid ester and resorcinol. The first agent may further contain other components.
The secondary reaction resol-type phenolic resin, the organic acid ester, and other components are as described above, and preferred embodiments are also the same.
The pH of the first agent is preferably 11.0 to 13.5, more preferably 11.5 to 12.5.
The viscosity of the first agent is preferably 50 to 3,000 mPa·s, more preferably 50 to 2,000 mPa·s, even more preferably 50 to 1,000 mPa·s, and particularly preferably 100 to 400 mPa·s.
The solid content concentration of the first agent is preferably 30.0 to 60.0% by mass, more preferably 40.0 to 55.0% by mass, and particularly preferably 40.0 to 50.0% by mass.

The second agent contains an organic acid ester and resorcinol. The second agent preferably does not contain a secondary reaction resol type phenolic resin. The second agent may further contain other components.

The preferred content (parts by mass) of the organic acid ester in the second agent with respect to 100 parts by mass of the secondary reaction resol-type phenolic resin in the first agent is the organic acid per 100 parts by mass of the secondary reaction resol-type phenolic resin in the present composition. It is the same as the preferred content of the ester.

The preferred content (parts by mass) of resorcinol in the second agent with respect to 100 parts by mass of the secondary reaction resol-type phenolic resin in the first agent is Same as quantity.

It is the same as the preferred ratio (% by mass) of the total of the solid content of the secondary reaction resol-type phenolic resin, the organic acid ester, and the resorcinol with respect to the total 100% by mass of the solid content of the first agent and the solid content of the second agent. .

In this kit, the first agent and the second agent are mixed to form the present composition, which is used for bonding wood together.

[wood material]
A wood material according to one aspect of the present invention is obtained by bonding two or more pieces of wood together via a cured product of the present composition.

Wood includes solid wood, woody materials, and the like, and is typically solid wood.
Examples of solid wood include birch, paulownia, cedar, cypress, pine, hiba, cypress, and pine. The form of solid wood may be lumber, sawn board, or the like.
Examples of wood materials include plywood, laminated lumber, cross laminated lumber, laminated veneer lumber, blockboard, veneer, and wooden board. Wood boards include IB (insulation board), MDF (medium density fiberboard), HB (hard board), particle board, OSB (oriented strand board), and the like.

Examples of the woody material of this embodiment include the same woody materials as the woody materials. Plywood or laminated wood is preferable as the wooden material of this aspect.
In the case of plywood, a plurality of wooden veneers are bonded via the cured product of the present composition. The wood veneer is not particularly limited, and a known wood veneer for plywood can be used. For example, cedar, Japanese larch, etc. are suitably used as the material for the wooden veneer. The number of wooden veneers forming the plywood is not particularly limited, and can be, for example, 2 to 20.
In the case of laminated wood, a plurality of laminas are adhered via the cured product of the present composition. Lamina is generally cut from sawn board. The number of laminas constituting the laminated material is not particularly limited, and can be, for example, 2 to 30 sheets.

[Method for producing wooden material]
A method for producing a wooden material according to one aspect of this aspect includes:
A step of mixing a secondary reaction resol-type phenolic resin obtained by resolizing a novolak-type phenolic resin, an organic acid ester, and resorcinol to prepare an adhesive composition for wood;
a step of stacking a plurality of woods via the adhesive composition for wood to obtain a laminate;
and a step of applying cold pressure or hot pressure to the laminate to cure the adhesive composition for wood.
In the step of curing the adhesive composition for wood, hot pressing may be applied after cold pressing.
The manufacturing method of this embodiment will be described below, taking as an example the case of manufacturing plywood or laminated lumber as the wooden material. However, the manufacturing method of this embodiment is not limited to the following examples.

<Manufacturing method of plywood>
The plywood manufacturing method of this example includes a step of mixing a secondary reaction resol-type phenolic resin obtained by resolizing a novolac-type phenolic resin, an organic acid ester, and resorcinol to prepare the present composition (composition preparation step )When,
A step of stacking a plurality of veneers with the present composition interposed to obtain a laminate (lamination step);
a step of applying cold pressure only, hot pressure only, or cold pressure and hot pressure to the resulting laminate to cure the composition (bonding step);
have
After the curing step, the plywood produced may be stacked and cured for a period of time, if desired.

The composition preparation step is the same as the preparation method of the present composition described above.

In the lamination step, the present composition is applied to at least one surface of overlapping veneers in the plywood, and the plurality of veneers are stacked. The method of applying the composition and the method of stacking the veneers may each be similar to those used in the manufacture of known plywood.
The coating amount of the present composition is, for example, 100 to 350 g/m ² as mass per unit area of the laminated surface of the veneer.
In the composition preparation step, the time from mixing the secondary reaction resol type phenolic resin with at least one of the organic acid ester and resorcinol to applying the present composition to the veneer is, as described above, 1 hour or less. Preferably.

In the bonding step, cold pressure conditions and hot pressure conditions are sufficient as long as the present composition can be cured.
The cold pressing conditions include, for example, temperature: room temperature (25° C.), cold pressing time: 10 to 60 minutes, and pressure: 0.1 to 2.0 MPa.
As for the heat-pressing conditions, the temperature is preferably 100° C. or lower, more preferably 80° C. or lower, in consideration of energy costs, and preferably 20° C. or higher, more preferably 25° C. or higher, and 40° C. or higher in consideration of productivity. is more preferred. The hot pressing time is, for example, 10 to 100 seconds per 1 mm of thickness after hot pressing in the direction of hot pressing. The pressure is, for example, 0.1-2.0 MPa.
When hot pressure is applied after cold pressure is applied in the bonding process, the time between applying the composition to the veneer in the lamination process and applying cold pressure in the bonding process, the so-called open deposition time ( The open assembly time) is preferably within 40 minutes. The time between the application of cold pressure and the application of hot pressure, the so-called closed deposition time (closed assembly time), is preferably within 3 hours.
After applying cold pressure or hot pressure, processing such as applying a load may be performed as necessary.

<Method for producing laminated lumber>
The method for producing the laminated wood of this example includes a step of mixing a secondary reaction resol-type phenolic resin obtained by resolizing a novolac-type phenolic resin, an organic acid ester, and resorcinol to prepare the present composition (composition preparation process) and
A step of stacking a plurality of laminas via the present composition to obtain a laminate (lamination step);
A step (adhesion step) of curing the composition by pressing the obtained laminate at room temperature for a certain period of time is included.
If necessary, the produced laminated lumber may be stacked and cured at a constant temperature for a certain period of time.

The composition preparation step is the same as the preparation method of the present composition described above.

In the lamination step, for example, the present composition is applied to at least one lamination surface of adjacent or overlapping laminas among the plurality of laminas, and the plurality of timbers are overlapped. The method of applying the composition and the method of stacking wood may each be similar to those used in the manufacture of known laminated lumber.
The coating amount of the present composition is, for example, 100 to 350 g/m ² as mass per unit area of the laminated surface of the lamina.
In the composition preparation step, the time from mixing the secondary reaction resol-type phenolic resin with at least one of the organic acid ester and resorcinol to applying the composition to the lamina is, as described above, 1 hour or less. is preferred.

The pressing conditions in the bonding process include, for example, temperature: room temperature (25° C.), time: 30 to 240 minutes, and pressure: 0.1 to 2.0 MPa.
After application of the present composition, the time until pressing, the so-called open deposition time (open assembly time), is preferably within 30 minutes.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples. In the following examples, "parts" and "%" indicate "parts by mass" and "% by mass", respectively, unless otherwise specified.

<Abbreviation>
The esters used below are shown below.
PC: propylene carbonate.
GBL: gamma-butyrolactone.
TACN: Triacetin.
EGDA: ethylene glycol diacetate.
TEGDA: triethylene glycol diacetate.
DBE: A mixture of dimethyl glutarate/dimethyl succinate/dimethyl adipate = 60/20/20 (mass ratio) (manufactured by Changle Yili Chemicals, China).
In the following, resorcinol may be abbreviated as Re.

<Measurement method>
(Weight average molecular weight by GPC measurement)
3 g of a sample (phenol resin) was diluted with 50 g of pure water, and adjusted to pH 4.0 with a 3% sulfuric acid aqueous solution while checking the pH. This is No. After filtering with the filter paper No. 2, the filtrate was further washed with 100 g of pure water, and air-dried to obtain a sample for GPC measurement.
The obtained sample for GPC measurement was subjected to GPC measurement under the following measurement conditions, and the polystyrene-equivalent weight average molecular weight was confirmed from the results.
Column: TSKgel G3000HXL 7.8 x 300 mm x 1 (manufactured by Tosoh Corporation),
TSKgel G2000HXL 7.8×300 mm×2 (manufactured by Tosoh Corporation).
Column temperature: 40°C.
Detector: RI (Differential Refractive Index Detector).
Solvent: THF (tetrahydrofuran).
Flow rate: 0.8 mL/min.

(viscosity)
Viscosity was measured with an E-type viscometer at 25°C.

(Solid content concentration)
Weigh the mass C ₁ (g) of an aluminum foil plate (inner diameter 50 mm, height 15 mm), accurately weigh the sample there so that it becomes 1.5 ± 0.1 g, and dry the specific mass of the sample. The mass of the previous sample was S (g). Place this aluminum foil dish in a constant temperature chamber pre-maintained at 135 ± 1 ° C, dry it for 60 ± 2 minutes, allow it to cool in a desiccator, and weigh its mass C ₂ (g). rice field. From the result, the sample mass D after drying (the mass of the sample remaining on the aluminum foil plate after drying) (g) is calculated by the following formula (1), and the solid content concentration is calculated by the following formula (2). did.
D=C ₂ -C ₁ (1)
Solid content concentration (mass%) = D / S × 100 (2)

(Gelling time (GT))
Weigh 6 g of sample in a test tube (dimensions: inner diameter 15 mm x 150 mm), add a stirring rod, immerse in an oil bath maintained at a predetermined measurement temperature (120 ° C. or 80 ° C.), press the stopwatch, Stirred continuously with a stir bar. The time (seconds) from when the sample was immersed in the oil bath until it could no longer be stirred due to gelation was read, and this value was defined as the gelation time (hereinafter also referred to as "GT").

(Plywood adhesion strength)
Ten test pieces of 150 mm×150 mm were cut out from the plywood, and each test piece was immersed in hot water at 60° C. for 3 hours. After that, the adhesive strength (class 2) of the test piece taken out from the hot water was measured based on the test method described in the JAS standard wood edition, and the average value was obtained. The adhesive strength (type 2) is preferably 0.7 MPa or higher, more preferably 1.0 MPa or higher.
In Test Examples 3 and 5, which will be described later, 10 cut test pieces were further immersed in cold water for 2 hours, steamed at 130°C for 2 hours, immersed in cold water for 1 hour, and again at 130°C. After steaming for 2 hours at , the adhesive strength (special class) was measured based on the test method described in the JAS standard wood edition, and the average value was obtained. The adhesive strength (special class) is preferably 0.7 MPa or higher, more preferably 0.9 MPa or higher, and even more preferably 1.0 MPa or higher.
In the following description, the adhesion strength in examples other than Test Examples 3 and 5 means adhesion strength (class 2).

It should be noted that the gelation time and adhesive strength are slightly changed depending on the temperature and humidity at the time of measurement. Therefore, in the following, the gelling time or adhesive strength of Examples and Comparative Examples shown in the same table were measured at almost the same timing for accurate comparison.

<Production of secondary reaction resol type phenolic resin>
(Production Example 1: Production of base resin)
517.0 parts of phenol, 264.0 parts of 50% formalin (F/P molar ratio: 0.80), 1.7 parts of 30% sulfuric acid, and 93 parts of water were placed in a 2 L flask equipped with a reflux tube, a stirrer and a thermometer. 0 part was charged and reacted for 3 hours under reflux conditions. Then, 256.9 parts of 30% aqueous sodium hydroxide solution (sodium hydroxide/phenol molar ratio: 0.35), 495.0 parts of 50% formalin (final F/P molar ratio: 2.30), 173 parts of water. 8 parts were added, reacted at 70° C. until the viscosity reached 4,500 to 5,500 mPa·s, and cooled to 40° C. or less to obtain a base resin (secondary reaction resol type phenolic resin).
Hereinafter, the sodium hydroxide/phenol molar ratio is also referred to as "NaOH/P molar ratio".

(Production Example 2: Production of resin A)
20.0 parts of 30% sodium hydroxide (final NaOH/P molar ratio: 0.50) was added to 327.0 parts of the base resin obtained in Production Example 1, and the solid content concentration was 42.0 to 43. Resin A (secondary reaction resol type phenolic resin) was obtained by adding water so as to make the concentration 0.0%.

(Production Example 3: Production of Resin B)
33.3 parts of 30% sodium hydroxide (final NaOH/P molar ratio: 0.60) was added to 327.0 parts of the base resin obtained in Production Example 1, and the solid content concentration was 42.0 to 43. Resin B (secondary reaction resol type phenolic resin) was obtained by adding water to 0%.

(Production Example 4: Production of Resin C)
To 327.0 parts of the base resin obtained in Production Example 1, 46.7 parts of 30% sodium hydroxide (final NaOH/P molar ratio: 0.70) was added, and the solid content concentration was 42.0 to 43. Resin C (secondary reaction resol type phenolic resin) was obtained by adding water so as to make the content 0.0%.

(Production Example 5: Production of Resin D)
To 327.0 parts of the base resin obtained in Production Example 1, 60.0 parts of 30% sodium hydroxide (final NaOH/P molar ratio: 0.80) was added, and the solid content concentration was 42.0 to 43. Resin D (secondary reaction resol-type phenolic resin) was obtained by adding water so that the concentration became 0%.

(Production Example 6: Production of Resin E)
To 327.0 parts of the base resin obtained in Production Example 1, 73.3 parts of 30% sodium hydroxide (final NaOH/P molar ratio: 0.90) was added, and the solid content concentration was 42.0 to 43. Resin E (secondary reaction resol-type phenolic resin) was obtained by adding water so as to make it 0%.

(Production Example 7: Production of resin F)
258.5 parts of phenol, 132.0 parts of 50% formalin (F/P molar ratio: 0.80), 0.9 parts of 30% sulfuric acid, and 46 parts of water were put into a 1 L flask equipped with a reflux tube, a stirrer and a thermometer. 5 parts were charged and reacted for 3 hours under reflux conditions. Then 128.5 parts of 30% aqueous sodium hydroxide solution (NaOH/P molar ratio: 0.35), 214.5 parts of 50% formalin (final F/P molar ratio: 2.10), 75.4 parts of water. parts are added and reacted at 70° C. until the viscosity reaches 4,500-5,500 mPa s, and 128.5 parts of 30% sodium hydroxide (final NaOH/P molar ratio: 0.70). Then, water was added so that the solid content concentration was 42.0 to 43.0% to obtain Resin F (secondary reaction resol type phenolic resin).

(Production Example 8: Production of resin G)
258.5 parts of phenol, 132.0 parts of 50% formalin (F/P molar ratio: 0.80), 0.9 parts of 30% sulfuric acid, and 46 parts of water were put into a 1 L flask equipped with a reflux tube, a stirrer and a thermometer. 5 parts were charged and reacted for 3 hours under reflux conditions. Then 128.5 parts of 30% aqueous sodium hydroxide solution (NaOH/P molar ratio: 0.35), 231.0 parts of 50% formalin (final F/P molar ratio: 2.20), 81.2 parts of water. parts are added and reacted at 70° C. until the viscosity reaches 4,500-5,500 mPa s, and 128.5 parts of 30% sodium hydroxide (final NaOH/P molar ratio: 0.70). Then, water was added so that the solid content concentration was 42.0 to 43.0% to obtain Resin G (secondary reaction resol type phenolic resin).

(Production Example 9: Production of Resin H)
258.5 parts of phenol, 132.0 parts of 50% formalin (F/P molar ratio: 0.80), 0.9 parts of 30% sulfuric acid, and 46 parts of water were put into a 1 L flask equipped with a reflux tube, a stirrer and a thermometer. 5 parts were charged and reacted for 3 hours under reflux conditions. Then 128.5 parts of 30% aqueous sodium hydroxide solution (NaOH/P molar ratio: 0.35), 264.0 parts of 50% formalin (final F/P molar ratio: 2.40), 92.8 parts of water. parts are added and reacted at 70° C. until the viscosity reaches 4,500-5,500 mPa s, and 128.5 parts of 30% sodium hydroxide (final NaOH/P molar ratio: 0.70). Then, water was added so that the solid content concentration was 42.0 to 43.0% to obtain Resin H (secondary reaction resol type phenolic resin).

(Production Example 10: Production of resin I)
258.5 parts of phenol, 132.0 parts of 50% formalin (F/P molar ratio: 0.80), 0.9 parts of 30% sulfuric acid, and 46 parts of water were put into a 1 L flask equipped with a reflux tube, a stirrer and a thermometer. 5 parts were charged and reacted for 3 hours under reflux conditions. Then 128.5 parts of 30% aqueous sodium hydroxide solution (NaOH/P molar ratio: 0.35), 280.5 parts of 50% formalin (final F/P molar ratio: 2.50), 98.6 parts of water. parts are added and reacted at 70° C. until the viscosity reaches 4,500-5,500 mPa s, and 128.5 parts of 30% sodium hydroxide (final NaOH/P molar ratio: 0.70). Then, water was added so that the solid content concentration was 42.0 to 43.0% to obtain Resin I (secondary reaction resol type phenolic resin).

(Production Example 11: Production of Resin J)
258.5 parts of phenol, 132.0 parts of 50% formalin (F/P molar ratio: 0.80), 0.9 parts of 30% sulfuric acid, and 46 parts of water were put into a 1 L flask equipped with a reflux tube, a stirrer and a thermometer. 5 parts were charged and reacted for 3 hours under reflux conditions. Then, 180.0 parts of 30% aqueous potassium hydroxide solution (KOH/P molar ratio: 0.35), 247.5 parts of 50% formalin (final F/P molar ratio: 2.30), 87.0 parts of water. parts and reacted at 70 ° C. until the viscosity reached 4,500 to 5,500 mPa s, and 180.0 parts of 30% potassium hydroxide (final KOH / P molar ratio: 0.70). Then, water was added so that the solid content concentration was 42.0 to 43.0% to obtain Resin J (secondary reaction resol type phenolic resin).

<Production of resol type phenolic resin>
(Production Example 12: Production of Resin K)
94.0 parts of phenol, 139.2 parts of 50% formalin (F/P molar ratio: 2.32), 59.9 parts of 48% aqueous sodium hydroxide solution, 73.8 parts of water was charged, reacted at 90° C. until the viscosity reached 140 mPa·s, and cooled to 40° C. or lower. Thereafter, water was added so that the solid content concentration was 44.0% to obtain resin K (resol-type phenolic resin).

<Production of secondary reaction resol type phenolic resin>
(Production Example 13: Production of Resin L)
258.5 parts of phenol, 132.0 parts of 50% formalin (F/P molar ratio: 0.80), 0.9 parts of 30% sulfuric acid, and 18 parts of water were placed in a 1 L flask equipped with a reflux tube, a stirrer and a thermometer. 0 part was charged and reacted for 3 hours under reflux conditions. Then 96.4 parts of 48% aqueous sodium hydroxide solution (NaOH/P molar ratio: 0.35), 231.0 parts of 50% formalin (final F/P molar ratio: 2.20), 31.5 parts of water. and reacted at 65° C. until the viscosity reached 7,500-8,500 mPa s, and 96.4 parts of 48% sodium hydroxide (final NaOH/P molar ratio: 0.70). Resin L (secondary reaction resol type phenolic resin) was obtained by addition.

(Production Example 14: Production of Resin M)
258.5 parts of phenol, 132.0 parts of 50% formalin (F/P molar ratio: 0.80), 0.9 parts of 30% sulfuric acid, and 18 parts of water were placed in a 1 L flask equipped with a reflux tube, a stirrer and a thermometer. 0 part was charged and reacted for 3 hours under reflux conditions. Then 96.4 parts of 48% aqueous sodium hydroxide solution (NaOH/P molar ratio: 0.35), 247.5 parts of 50% formalin (final F/P molar ratio: 2.30), 33.8 parts of water. and reacted at 65° C. until the viscosity reached 7,500-8,500 mPa s, and 96.4 parts of 48% sodium hydroxide (final NaOH/P molar ratio: 0.70). A resin M (secondary reaction resol type phenolic resin) was obtained by addition.

(Production Example 15: Production of Resin N)
258.5 parts of phenol, 132.0 parts of 50% formalin (F/P molar ratio: 0.80), 0.9 parts of 30% sulfuric acid, and 18 parts of water were placed in a 1 L flask equipped with a reflux tube, a stirrer and a thermometer. 0 part was charged and reacted for 3 hours under reflux conditions. Then 96.4 parts of 48% aqueous sodium hydroxide solution (NaOH/P molar ratio: 0.35), 264.0 parts of 50% formalin (final F/P molar ratio: 2.40), 36.0 parts of water. and react at 65° C. until the viscosity reaches 7,500-8,500 mPa·s, and add 96.4 parts of 48% sodium hydroxide (final NaOH/P molar ratio: 0.70). As a result, Resin N (secondary reaction resol type phenolic resin) was obtained.

(Production Example 16: Production of Resin O)
258.5 parts of phenol, 132.0 parts of 50% formalin (F/P molar ratio: 0.80), 0.9 parts of 30% sulfuric acid, and 18 parts of water were placed in a 1 L flask equipped with a reflux tube, a stirrer and a thermometer. 0 part was charged and reacted for 3 hours under reflux conditions. Then 96.4 parts of 48% aqueous sodium hydroxide solution (NaOH/P molar ratio: 0.35), 280.5 parts of 50% formalin (final F/P molar ratio: 2.50), 38.3 parts of water. and reacted at 65° C. until the viscosity reached 7,500-8,500 mPa s, and 96.4 parts of 48% sodium hydroxide (final NaOH/P molar ratio: 0.70). Resin O (secondary reaction resol type phenolic resin) was obtained by addition.

Tables 1-2 show the final F/P molar ratio, final NaOH/P molar ratio or KOH/P molar ratio, pH, weight average molecular weight, viscosity, gel time at 120° C. for Resins A-O. , indicates the solid content concentration.

<Test Example 1>
In this test, the effect of adding resorcinol on changes in resin viscosity over time was verified.
100 parts of Resin C were mixed with 3 parts of resorcinol and the resulting mixture was allowed to stand at 25°C. Separately, the resin C was allowed to stand still at 25°C.
The viscosity of each of the mixture and resin C was measured every day from the start of standing. The results are shown in FIG. FIG. 1 is a graph in which the horizontal axis represents the number of days elapsed from the start of standing and the vertical axis represents the viscosity.
As shown in FIG. 1, when resorcinol (Re) was added, the rate of increase in resin viscosity increased, indicating that resorcinol accelerated gelation of the resin.

<Test Example 2>
In this test, the effect of the addition of ester on the gelation time was verified.
To 100 parts of Resin C, 7 parts of 50% resorcinol (Re) aqueous solution was added, and a predetermined amount (parts) of ester was mixed, and the resulting mixture was measured for gelation time at 80°C. PC, GBL, TACN, EGDA, TEGDA or DBE was used as the organic acid ester. The results are shown in FIG. FIG. 2 is a graph in which the amount of ester added is plotted on the horizontal axis and the gelling time is plotted on the vertical axis. The content of the ester is the ratio (parts) to 100 parts by mass of the solid content of the resin.
As shown in FIG. 2, there was a tendency for gelation time to shorten as the amount of ester added increased. In addition, among the added esters, PC, GBL, TACN, and EGDA are smaller in amount than TEGDA and DBE, and the gelation time is shorter, and it was found that the effect of accelerating the curing of the secondary reaction resolized phenolic resin is excellent. .

<Examples 1 to 6, Comparative Examples 1 to 6>
(Preparation of adhesive composition for wood)
According to the formulation shown in Table 3, a 50% resorcinol (Re) aqueous solution and an ester (PC or GBL) were mixed with resins (resins A to E), and wood adhesives of Examples 1 to 6 and Comparative Examples 1 to 6 were prepared. A composition was obtained.

(Production of plywood)
Using the wood adhesive composition of any of Examples 1 to 6 and Comparative Examples 1 to 6 as an adhesive, a larch veneer of 150 mm long × 150 mm wide × 3.1 mm thick (without drying , moisture content 5-15%) was used.
Apply the following amount of adhesive to the first veneer, overlap the second veneer so that it crosses, apply the same amount of adhesive to the second veneer, and cross A third veneer was laminated in the same manner as above, and the resulting laminate was hot-pressed to obtain a plywood having a thickness of about 9 mm with 3 ply.
The time from mixing each material in the preparation of the adhesive composition for wood to coating the adhesive composition for wood in the production of plywood was 3 minutes. In addition, the time from the application of the adhesive composition for wood to the application of heat pressure was set to 7 minutes. Molding conditions are shown below.
- Amount of adhesive applied: 20 g/raku (=220 g/m ² ).
Hot-pressing conditions: 50° C., hot-pressing time: 10 minutes (67 seconds per 1 mm thickness of plywood after hot-pressing), pressure: 10 kgf/cm ² (=1 MPa).

Table 3 shows the gelation time at 80° C. and the adhesive strength to plywood of each example of the adhesive composition for wood.
FIG. 3 shows a graph in which the horizontal axis represents the pH of the resins used in Examples 1 to 5 and Comparative Examples 1 to 5, and the vertical axis represents the adhesive strength of the plywood.

Comparing Example 1 and Comparative Example 1, Example 1 containing resorcinol (Re) was superior in adhesive strength to the plywood. A similar tendency was observed in the comparison of Examples 2 to 6 and Comparative Examples 2 to 6, respectively.
Further, when comparing Examples 1 to 5, there was a tendency that the resin pH reached a maximum around 12.0 to 12.5.

<Examples 7 to 11, Comparative Examples 7 to 11>
(Preparation of adhesive composition for wood)
A 50% resorcinol (Re) aqueous solution and an ester (TACN) were mixed with resins (resins C to J) according to the formulations shown in Table 4, and wood adhesive compositions of Examples 7 to 11 and Comparative Examples 7 to 11 were prepared. got

(Production of plywood)
Plywood was obtained in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 6, except that the wood adhesive composition of any one of Examples 7 to 11 and Comparative Examples 7 to 11 was used as the adhesive.

Table 4 shows the gelling time at 80° C. and the adhesive strength to plywood of each example of the adhesive composition for wood.
FIG. 4 shows a graph in which the horizontal axis represents the F/P molar ratio and the vertical axis represents the adhesive strength of the plywood in Examples 7 to 11 and Comparative Examples 7 to 11, respectively.

Comparing Example 7 with Comparative Example 7, Example 7 containing resorcinol (Re) was superior in adhesive strength to the plywood. A similar tendency was observed in the comparison of Examples 8 to 11 and Comparative Examples 8 to 11, respectively.
Further, when comparing Examples 7 to 11, there was a tendency that the F/P molar ratio was maximized around 2.25 to 2.35.

<Examples 3, 14 to 17, Comparative Example 14>
(Preparation of adhesive composition for wood)
Resin C was mixed with a 50% resorcinol (Re) aqueous solution and PC according to the formulation shown in Table 5 to obtain adhesive compositions for wood of Examples 3, 14 to 17, and Comparative Example 14.

(Production of plywood)
Plywood was obtained in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 6, except that any of the wood adhesive compositions of Examples 3, 14 to 17, and Comparative Example 14 was used as the adhesive.

Table 5 shows the gelation time at 80° C. and the adhesive strength to plywood of each example of the adhesive composition for wood.
FIG. 5 shows a graph in which the resorcinol content in each of Examples 3, 14 to 17, and Comparative Example 14 is plotted on the horizontal axis, the adhesive strength of the plywood on the left vertical axis, and the gelation time on the right vertical axis. . The content of resorcinol is the ratio (parts) to 100 parts by mass of Resin C.

The adhesive compositions for wood of Examples 3 and 14 to 17 exhibited adhesive strength at 50° C. hot pressure.
On the other hand, the wood adhesive composition of Comparative Example 14, which does not contain resorcinol, did not develop adhesive strength under hot pressure at 50° C., and the veneers separated when the test piece was immersed in hot water.

<Examples 3, 18 to 23, Comparative Example 15>
(Preparation of adhesive composition for wood)
Resin C was mixed with a 50% resorcinol (Re) aqueous solution and PC according to the formulation shown in Table 6 to obtain adhesive compositions for wood of Examples 3, 18 to 23, and Comparative Example 15.

(Production of plywood)
Plywood was obtained in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 6, except that one of the wood adhesive compositions of Examples 3, 18 to 23, and Comparative Example 15 was used as the adhesive.

Table 6 shows the gelation time at 80° C. and the adhesive strength to plywood of each example of the adhesive composition for wood.
FIG. 6 shows a graph in which the horizontal axis represents the PC content, the left vertical axis represents the adhesive strength, and the right vertical axis represents the gelation time in each of Examples 3, 18 to 23, and Comparative Example 15. The content of PC is the ratio (parts) to 100 parts by mass of Resin C.

The adhesive compositions for wood of Examples 3 and 18 to 23 exhibited adhesive strength at 50° C. hot pressure.
On the other hand, the adhesive composition for wood of Comparative Example 15, which does not contain PC, did not develop adhesive strength under hot pressure at 50° C., and the veneers separated when the test piece was immersed in warm water.

<Examples 24 to 32, Comparative Example 15>
(Preparation of adhesive composition for wood)
Resin C was mixed with a 50% resorcinol (Re) aqueous solution and TACN according to the formulation shown in Table 7 to obtain adhesive compositions for wood of Examples 24 to 32 and Comparative Example 15.

(Production of plywood)
Plywood was obtained in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 6, except that one of the wood adhesive compositions of Examples 24 to 32 and Comparative Example 15 was used as the adhesive.

Table 7 shows the gelation time at 80° C. and the adhesive strength to plywood of each example of the adhesive composition for wood.
FIG. 7 shows a graph in which the horizontal axis represents the TACN content in each of Examples 24 to 32 and Comparative Example 15, the left vertical axis represents the adhesive strength of the plywood, and the right vertical axis represents the gelling time. The content of TACN is the ratio (parts) to 100 parts by mass of Resin C.

The adhesive compositions for wood of Examples 24 to 32 exhibited adhesive strength at 50° C. hot pressure.
On the other hand, the adhesive composition for wood of Comparative Example 15, which does not contain TACN, did not develop adhesive strength under hot pressure at 50° C., and the veneers separated when the test piece was immersed in hot water.

<Test Example 3>
In this test, the effect of cold pressing time on bond strength in the production of plywood was examined.
Examples 1 to 5 and Comparative Example except that the adhesive composition for wood of Example 27 was used as an adhesive, and only cold pressure was applied for a predetermined time without applying hot pressure. Plywood was obtained in the same manner as in 1 to 5. Adhesion strength (class 2 and class 2) of the obtained plywood was measured.
・Cold pressing conditions: 25°C, 15 minutes to 4 hours, pressure: 10 kgf/cm ² (=1 MPa)
FIG. 8 shows a graph in which the horizontal axis represents the cold pressing time and the vertical axis represents the adhesive strength of the plywood.
As shown in FIG. 8, there was a tendency that the longer the cold pressing time, the higher the adhesive strength (special class).

<Comparative Examples 16 to 21>
(Preparation of adhesive composition for wood)
A 50% resorcinol (Re) aqueous solution and TACN were mixed with a resin (Resin C or K) according to the formulation shown in Table 8 to obtain wood adhesive compositions of Comparative Examples 16-21.

(Production of plywood)
Plywood was obtained in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 6, except that one of the wood adhesive compositions of Comparative Examples 16 to 21 was used as the adhesive.
Further, the same operations as in Examples 3 and 27 were performed again to obtain plywood.

Table 8 shows the gelling time at 80° C. and the adhesive strength to plywood of each example of the adhesive composition for wood.
FIG. 9 collectively shows the adhesive strength of the plywood of Example 3 and Comparative Examples 16, 18 and 19. As shown in FIG.
FIG. 10 collectively shows the adhesive strength of the plywood of Example 27 and Comparative Examples 17, 20, and 21. As shown in FIG.

Comparing Example 3 and Comparative Example 16, when Resin C was used as the resin, the example in which PC and resorcinol were combined was higher than Comparative Example 16 in which the amount of PC was increased without adding resorcinol. Excellent adhesion strength. Although the same tendency as described above was observed in comparison between Comparative Examples 18 and 19 using resin K, the effect of improving the adhesive strength was inferior to that in the case of using resin C.
In Example 27 and Comparative Examples 17, 20 and 21 in which TACN was used instead of PC, the same tendency as in Example 3 and Comparative Examples 16, 18 and 19 was observed. Furthermore, in Comparative Example 20 in which resin K, TACN and resorcinol were combined, the adhesive strength was inferior to that in Comparative Example 17 in which resin C and TACN were combined. From this, it was found that resorcinol cannot obtain a sufficient curing acceleration effect in combination with a general resol-type phenolic resin and TACN.

<Test Example 4>
In this test, a block shear test of laminated wood using birch was performed in accordance with the Japanese Agricultural Standards.

(Preparation of laminated wood block shearing test piece)
The adhesive compositions for wood of Example 27 and Comparative Example 17 were used as adhesives, and birch wood having a length of 150 mm, a width of 75 mm, and a thickness of 15 mm was used as the wood.
1.2 g of the above-mentioned adhesive composition was applied to each of two pieces of wood, and the adhesive surfaces were overlapped and cold-pressed for a predetermined time to obtain a test piece for a block shear test of laminated wood.
Based on the Japanese Agricultural Standards, block-shaped test pieces were cut out so that the adhesion area was 25 mm×25 mm=625 mm ² , and a total of 8 pieces were prepared.
The time from mixing each material in the preparation of the adhesive composition for wood to coating the adhesive composition for wood in the production of plywood was 3 minutes. In addition, the time from the application of the adhesive composition for wood to the application of heat pressure was set to 7 minutes. Molding conditions are shown below.
- Amount of adhesive applied: 20 g/raku (=220 g/m ² ).
- Cold pressure conditions: 25°C, time: 4 hours, pressure: 13 kgf/cm ² (=1.3 MPa).

Table 9 shows the gelling time at 80° C. of each example of the adhesive composition for wood and the results of the block shear test (strength and breaking rate of wood). A case where the shear strength was 9.6 MPa or more and the xylem fracture rate was 60% or more was judged to be acceptable, and the other cases were judged to be unacceptable.

Comparing Example 27 with Comparative Example 17, Example 27 containing resorcinol (Re) was superior in terms of shear strength and xylem fracture rate.

<Test Example 5>
In this test, a high-viscosity type resin was used to verify the effect on the bonding strength of room-temperature bonding in the production of plywood.

(Preparation of adhesive composition for wood)
According to the formulation shown in Table 10, resins (resins L to O) were added with a curing agent solution in which resorcinol (Re) was dissolved in ester (TACN), and water for viscosity adjustment was added and mixed to obtain wood of Examples 33 to 36. An adhesive composition was obtained. Separately, according to the formulation shown in Table 10, ester (TACN), water for adjusting the viscosity, and calcium carbonate were added to the resins (resins L to O) in order to match the paste ratio with those of the examples. 25 wood adhesive compositions were obtained. The "paste ratio" means the ratio of the total amount of glue (total of resin, ester, resorcinol, water, and calcium carbonate) to the amount of resin, and is calculated by the following formula.
Calculation formula: Glue ratio = total amount of glue (parts by mass) / amount of resin (parts by mass) x 100
In addition, the amount of TACN added in the comparative example was particularly adjusted so that the adhesive composition of each example and the comparative example had the same gelation time.

(Production of plywood)
Using the adhesive compositions for wood of Examples 33 to 36 and Comparative Examples 22 to 25 as adhesives, three larch veneers each having a length of 150 mm, a width of 150 mm, and a thickness of 2.0 mm were prepared. Boards 1-3) and two cedar veneers (150 mm long×150 mm wide×3.0 mm thick) (cedar veneers 1-2) (no drying, moisture content 5-15%) were used.
An adhesive was applied to the surface of the Japanese cedar veneer 1 in the following coating amount, and the larch veneers 1 were overlapped so as to cross each other. The back surface of the Japanese cedar veneer 1 was coated with the following amount of adhesive, and the larch veneers 2 were overlapped so as to cross each other. An adhesive was applied to the back surface of the Japanese cedar veneer 2 in the following coating amount, and placed on the larch veneer 3 so as to cross each other. An adhesive was applied to the surface of the cedar veneer 2 in the following amount, and the previously laminated larch veneer 1, cedar veneer 2, and larch veneer 2 were stacked so as to cross each other. The obtained laminate was pressed to obtain a plywood having a thickness of about 10 mm with 5 ply.
The time from mixing each material in the preparation of the adhesive composition for wood to applying the adhesive composition for wood in the production of plywood was 2 minutes, and the adhesive was applied in 3 minutes. The time from application of the adhesive composition for wood to application of hot pressure was 5 minutes. Molding conditions are shown below.
- Amount of adhesive applied: 20 g/raku (=220 g/m ² ).
- Pressing conditions: temperature: 25°C, time: 30 minutes, pressure: 10 kgf/cm ² (=1 MPa).
Table 10 shows the gelation time at 80° C. and the adhesive strength to plywood (special class) of the adhesive composition for wood of each example.

Plywood prepared at 25° C. for 30 minutes using the adhesives of Examples 33 to 36 exhibited excellent adhesive strength. On the other hand, the plywoods using the adhesives of Comparative Examples 22 to 25, which did not contain resorcinol, were inferior in adhesive strength, although the gelation times were at the same level as in Examples 33 to 36, respectively.

Claims (13)

An adhesive composition for wood comprising a secondary reaction resol type phenolic resin obtained by converting a novolac type phenolic resin into a resol, an organic acid ester, and resorcinol. The adhesive composition for wood according to claim 1, wherein the organic acid ester is at least one selected from the group consisting of lactones, monocarboxylic acid esters, dicarboxylic acid monoesters and dicarboxylic acid diesters. Carbonic acid esters such as ethylene carbonate, propylene carbonate, and dimethyl carbonate; At least selected from the group consisting of methyl butyrate, ethyl butyrate, ethyl formate, methyl salicylate, ethyl acetoacetate, dimethyl succinate, diethyl succinate, dimethyl adipate, diethyl adipate, dimethyl glutarate, diethyl glutarate and diethyl malonate The adhesive composition for wood according to claim 1 or 2, which is one type. wherein said organic acid ester comprises at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, γ-butyrolactone, α-acetolactone, β-propiolactone, triacetin and ethylene glycol diacetate; 4. The adhesive composition for wood according to any one of 1 to 3. For wood according to any one of claims 1 to 4, wherein the content of the organic acid ester is 1.0 to 20.0 parts by mass with respect to 100 parts by mass of the secondary reaction resol type phenolic resin. adhesive composition. The wood adhesive according to any one of claims 1 to 5, wherein the resorcinol content is 1.0 to 10.0 parts by mass with respect to 100 parts by mass of the secondary reaction resol-type phenolic resin. Composition. The adhesive composition for wood according to any one of claims 1 to 6, wherein the secondary reaction resol type phenolic resin has a pH of 10.0 to 13.5. The adhesive composition for wood according to any one of claims 1 to 7, wherein the secondary reaction resol type phenolic resin has a weight average molecular weight of 2,000 to 10,000. a first container containing a first agent containing a secondary reaction resol-type phenolic resin obtained by converting a novolac-type phenolic resin into a resol;
An adhesive kit for wood, comprising a second container containing a second agent containing an organic acid ester and resorcinol. A woody material in which a plurality of woods are bonded via a cured product of the adhesive composition for wood according to any one of claims 1 to 8. 11. Wood-based material according to claim 10, which is plywood. 11. The wooden material according to claim 10, which is laminated lumber. A step of mixing a secondary reaction resol-type phenolic resin obtained by resolizing a novolak-type phenolic resin, an organic acid ester, and resorcinol to prepare an adhesive composition for wood;
a step of stacking a plurality of woods via the adhesive composition for wood to obtain a laminate;
a step of applying cold pressure or hot pressure to the laminate to cure the adhesive composition for wood.

Images