JP5035301B2 - Plywood adhesive, production method and use of resol type phenolic resin for plywood adhesive - Google Patents

Description

The present invention relates to a plywood adhesive, a method for producing a resol type phenolic resin for plywood adhesive, and applications.

  Conventionally, amino resin adhesives typified by melamine / formaldehyde resins and urea / formaldehyde resins, and phenol / formaldehyde resin adhesives have been used as adhesives for plywood. Conventional phenol-formaldehyde resin adhesives (hereinafter referred to as phenol resin adhesives) are superior in adhesion, durability, and stability compared to amino resin adhesives, but they have the heat to produce plywood. When pressing (pressing), a high temperature and a long time are required, which causes a decrease in workability, a reduction in thickness of the product after pressing, and surface deterioration.

  As a solution to the problem of such a phenol resin adhesive, Patent Document 1 discloses a resol type in which a phenol resin component having 4 or more nuclei is 40% by weight or more and a monomethylolphenol component is 5% by weight or more. A phenol resin adhesive composition obtained by blending an isocyanate compound with a phenol-formaldehyde resin has been proposed.

  Patent Document 2 discloses a first stage reaction in which a molar ratio (F / P) of formaldehyde (F) to phenol (P) is reacted at 2.2 to 3.0, and a molar ratio after completion of the first stage reaction. Adjusted to 1.4 to 1.8 and reacted with 100 parts by weight of the phenol resin adhesive consisting of the second stage reaction, 5 to 20 parts by weight of isocyanate compound and 3 to 15 parts by weight of tannin having a polyphenol content of 70% or more A phenol resin adhesive composition obtained by addition has been proposed.

  According to the phenol resin adhesive composition described in Patent Documents 1 and 2, plywood can be obtained by heating and pressurizing 5 sheets of 1.8 mm thick single plate (5 ply) at 120 ° C. and 20 seconds / mm. It is described.

JP 2001-254066 A JP 2001-279214 A U.S. Pat. No. 2,464,207

Bender, H.C. L. Farnham, A .; G. Guyer, J .; W. , Apel, F.M. N. Gibb. T.A. B. : Ind. Enng. Chem. 44, 1619 (1952)

  On the other hand, in recent years, the use of domestic cedar as a plywood material has been considered because of the rising price of larch imported as raw wood and the difficulty of obtaining it. Since cedar has a high water content, when a plywood is manufactured using a conventional resin, it is necessary to use a veneered plate (water content of about 6% or less). However, the moisture content of the veneer cannot be reduced to a predetermined amount due to insufficient drying, etc., and the heating temperature in the pressing process during plywood production causes the water in the veneer to become steam and cause peeling called puncture was there. Moreover, since the specific gravity of cedar is small, when the heating temperature in a press process is high, the thickness reduction was remarkable.

Using the phenol resin adhesive composition described in Patent Document 1 or 2 as described above, the thickness is 9 mm (five 1.8 mm thick single plates) and the thickness is 12 mm (vertical core 1.8 mm3, paste core 3 When a plywood is produced from a laminated veneer of about 2 mm (.5 mm), peeling is suppressed. However, when producing a thick plywood with a thickness of 15 mm or more, it is necessary to press for a long time in order to stabilize the plywood characteristics at a high temperature of about 130 ° C. to 135 ° C. in consideration of productivity. There was room for improvement in the reduction of the thickness of the product (plywood) after pressing and the occurrence of peeling. Furthermore, the phenolic resin adhesive composition described in Patent Document 1 or 2 reduces the amount of formaldehyde emitted when plywood is used, especially when using tree species with high formaldehyde emissions such as planted trees and domestic cedar. There was also room for improvement in storage stability.
In addition, cedar is difficult to dry, and in order to reduce the moisture content, drying time and the like become longer when a veneer is produced, so there is a point to be improved in terms of the production cost and production rate of plywood.

The present invention can be described below.
[1] An adhesive for plywood containing a resol type phenolic resin in which the content of mononuclear and binuclear is 6% or less in the area ratio on a gel permeation chromatogram (GPC) chart of tetrahydrofuran-soluble matter.

[2] In the resol type phenol resin, the ratio (O / P bond ratio) between the number of methylene groups of ortho bond (O) and the number of methylene groups of para bond (P) indicating the bonding position of methylene group to the OH group of phenol is 0. The adhesive for plywood according to [1], comprising a resol of a high-ortho novolak type phenolic resin that is .3 to 1.0 .

[3] The resol type phenol resin contains 70% or more of a high ortho novolac type phenol resin resole having 5 or more nuclei in an area ratio on a gel permeation chromatogram (GPC) chart of a tetrahydrofuran soluble component [1] ] Or the adhesive for plywood according to [2].

[4] The resol-type phenol resin is measured using a Fourier transform infrared spectrophotometer (FT-IR), and C derived from a methylol group with respect to a peak intensity derived from a C═C bond in an aromatic ring. = The adhesive for plywood according to any one of [1] to [3], wherein the peak intensity derived from the O bond is 0.5 or more and 1 or less.

[5] In the presence of a catalyst comprising an alkaline earth metal salt, aldehydes are reacted in an amount of 0.9 to 1.2 in molar ratio to phenols to prepare orthomethylolphenol, The orthomethylol phenol is condensed under acidic conditions to prepare a high ortho novolac type phenol resin as an initial condensate, and then the high ortho novolac type phenol resin is reacted with an aldehyde in the presence of an alkaline catalyst. An adhesive for plywood containing a resol type phenolic resin obtained by resolification.

[6] The adhesive for plywood according to [5], wherein the alkaline earth metal salt is magnesium oxide, magnesium acetate, calcium oxide, or zinc acetate.

[7] A step of preparing orthomethylolphenol by reacting aldehydes in an amount of 0.9 or more and 1.2 or less in a molar ratio with respect to phenols in the presence of a catalyst comprising an alkaline earth metal salt;
A step of condensing the orthomethylolphenol under acidic conditions to prepare a high ortho novolac type phenol resin as an initial condensate;
A step of reacting the high ortho novolak type phenol resin with an aldehyde in the presence of an alkaline catalyst to form a resole;
Method for producing a resol type phenolic resin plywood adhesives comprising.

[8] The alkaline earth metal salts, magnesium oxide, magnesium acetate or zinc acetate [7] The method for producing a resol type phenol resin for plywood adhesive according to.

[ 9 ] A plywood in which at least two wooden veneers are bonded via the plywood adhesive according to any one of [1] to [6] .

[10] the wood veneer, heating conditions for bonding through the plywood adhesive, 20 seconds / mm or more, 30 seconds / mm or less, 110 ° C. or higher, the at 125 ° C. or less [9] Plywood as described.

[ 11 ] The plywood according to [ 9 ] or [ 10 ], wherein the water content of the wooden veneer is 10% by weight or more and 20% by weight or less.

Since the adhesive for plywood containing the resol type phenolic resin of the present invention is excellent in low-temperature adhesiveness, a thick plywood having a thickness of 15 mm or more can be produced by a pressing process at a low temperature of about 120 ° C. Thereby, since the step reduction of a single board becomes small compared with the case where a plywood is produced by long-time press at high temperature, the thickness of the single board to be used can be set thinner. Therefore, the acquisition rate of the single board obtained from the raw wood can be improved. Furthermore, thickness reduction in the pressing process can be suppressed, and the yield of products can be improved.

Moreover, since a plywood can be produced even if the veneer is not in an absolutely dry state, the moisture content of the veneer can be set to about 10 wt% to 20 wt%. Therefore, the drying time of the veneer can be shortened, and further, when the veneer containing 10% by weight to 20% by weight of the veneer is completely dried, it contracts by about 10 mm per 300 mm. The acquisition rate is improved by about 3%. Therefore, the manufacturing cost and manufacturing efficiency of the plywood can be improved and the productivity of the plywood can be improved. Further , the adhesive for plywood of the present invention has a reduced formaldehyde emission amount and is excellent in storage stability.

2 is a chart showing the results of GPC measurement of a resol type phenolic resin obtained in Example 1 and a phenolic resin obtained in Comparative Example 1. 6 is a chart showing the results of GPC measurement of a resol type phenolic resin obtained in Example 2 and a phenolic resin obtained in Comparative Example 1. 2 is a chart showing the results of FT-IR measurement of a resol type phenolic resin obtained in Example 1 and a phenolic resin obtained in Comparative Example 1.

Hereinafter, the present invention will be specifically described.
<Resol type phenolic resin>
The resol type phenol resin of the present invention comprises a polymer component, a mononuclear body and a binuclear body, and has an area ratio of 1 on a gel permeation chromatogram (GPC) chart of a tetrahydrofuran (THF) soluble component. Nucleus and dinuclear are included in an amount of 6% or less.

  In the present invention, the resol type phenol resin comprises a polymer component having a molecular weight exceeding 1000, an oligomer component having a molecular weight of 1000 or less from a tetranuclear body, a mononuclear body to a trinuclear body derived from phenols that are monomers, and the like. Including. The mononuclear body includes phenols as monomers, methylol group-containing phenols having at least one methylol group, and the like. Examples of the binuclear compound include a compound in which two mononuclear bodies are bonded. Examples of the trinuclear body include a compound in which three mononuclear bodies are bonded.

  The resol type phenolic resin of the present invention contains mononuclear and binuclear compounds in an amount of 6% or less, preferably 3% or less, more preferably 2% or less. In addition, the lower limit can be set to 0.1% from the viewpoint of suppressing rapid curing (drying property) at the time of cold heat and imparting adhesiveness.

The polymer component contained in the resol type phenolic resin of the present invention is preferably composed of a resol of a high ortho novolac type phenolic resin. The resol of the high ortho novolac type phenol resin has a number average molecular weight of 1700 or more and 2000 or less.
In addition, the ratio of the number of methylene groups between the ortho bond and the para bond (O / P bond ratio) indicating the bonding position of the methylene group to the OH group of phenol is in the range of 0.3 to 1.0. The ratio of the number of methylene groups was measured using a Fourier transform infrared spectrophotometer (FT-IR), and the peak intensity (1) derived from the C—H bond substituted at the para-position and the C—H substituted at the ortho-position. Based on the peak intensity (2) derived from the bond, it is calculated by the formula: (2) / ((1) × 1.3).
The resol type phenol resin of the present invention contains 70% or more, preferably 80% or more, of a high ortho novolak type phenol resin having 5 or more nuclei. The content of the high molecular weight component of five or more nuclei can be calculated from the area of a gel permeation chromatogram (GPC) chart soluble in THF.

  Since such a resol type phenol resin is superior in low-temperature adhesiveness, a thick plywood having a thickness of 15 mm or more can be produced by a pressing process at a low temperature of about 120 ° C.

  Furthermore, since adhesiveness can be imparted by heating at a low temperature, a reduction in thickness in the pressing process can be suppressed, and the yield of products can be improved. Further, since the plywood can be produced even if the veneer is not in an absolutely dry state, the drying time of the veneer can be shortened, and further shrinkage in the length direction and the width direction can be suppressed. Thereby, while improving the manufacturing cost and manufacturing efficiency of a plywood, productivity of a plywood can be improved.

  The resol type phenol resin of the present invention is derived from a methylol group with respect to a peak intensity a derived from a C═C bond in an aromatic ring, measured using a Fourier transform infrared spectrophotometer (FT-IR). The ratio b / a of the peak intensity b derived from the C═O bond is 0.5 or more and 1 or less, preferably 0.6 or more and 1 or less.

  Thus, since there are few methylol groups compared with the conventional phenol resin, while being excellent in storage stability, emission of formalin by methylol decomposition is suppressed.

<Resol type phenol resin production method>
The manufacturing method of the resol type phenol resin of this invention includes the following processes.
(A) A step of obtaining orthomethylolphenol by reacting aldehydes in an amount of 0.7 or more and 1.5 or less in molar ratio to phenols in the presence of a catalyst comprising an alkaline earth metal salt (b) A step of condensing orthomethylolphenol under acidic conditions to obtain a high ortho novolak type phenol resin as an initial condensate (c) in the presence of an alkaline catalyst, the high ortho novolac type phenol resin as an initial condensate with aldehydes; Process of reacting to resole Hereinafter, it demonstrates in order of a process.

(Process (a))
In step (a), phenols (P) and aldehydes (F) are reacted at the following reaction molar ratio (F / P) in the presence of a catalyst comprising an alkaline earth metal salt to give orthomethylol. Obtain phenol.
The reaction molar ratio (F / P) is 0.7 or more and 1.5 or less, preferably 0.9 or more and 1.2 or less.

  In the conventional phenol resin adhesive composition, from the viewpoint of accelerating the reaction to obtain a novolac type phenol resin, the reaction is performed at a reaction molar ratio (F / P) of about 2 to 3, and resolation is performed under alkaline conditions. It was. However, as a result of diligent investigations by the present inventor, an orthomethylolphenol was obtained by reacting with phenols and aldehydes within the above reaction molar ratio (F / P), and an initial condensate of orthomethylolphenol was obtained. When resolation was performed later, it was found that the content of mononuclear and binuclear bodies can be reduced with good controllability. And it discovered that the adhesive agent which consists of a resol type phenol resin obtained by this method was excellent in low-temperature adhesiveness, and was able to acquire said effect, and completed this invention.

  Examples of the alkaline earth metal salt include magnesium oxide, magnesium acetate, calcium oxide, and zinc acetate. These can be used alone or in combination of two or more. By using these alkaline earth metal salts as catalysts, a high-ortho structure having a methylol group at the ortho position of the phenols can be introduced. It is preferable to use magnesium oxide as the alkaline earth metal salt because the reaction in the neutral region is excellent in controllability with respect to the contents of the monomer component and the dimer component.

  Examples of aldehydes include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural, glyoxal, n-butyraldehyde, caproaldehyde, allylaldehyde, benzaldehyde, crotonaldehyde, acrolein, Examples include tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, and salicylaldehyde. These can be used alone or in combination of two or more.

Phenols include phenol,
cresols such as o-cresol, m-cresol, p-cresol,
Xylenol such as 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol,
o-ethylphenol, m-ethylphenol, ethylphenol such as p-ethylphenol, isopropylphenol, butylphenol, butylphenol such as p-tert-butylphenol, p-tert-amylphenol, p-octylphenol, p-nonylphenol, p- Alkylphenols such as cumylphenol,
Halogenated phenols such as fluorophenol, chlorophenol, bromophenol, iodophenol,
monovalent phenol substitutes such as p-phenylphenol, aminophenol, nitrophenol, dinitrophenol and trinitrophenol, and monovalent phenols such as 1-naphthol and 2-naphthol,
Examples thereof include polyphenols such as resorcin, alkylresorcin, pyrogallol, catechol, alkylcatechol, hydroquinone, alkylhydroquinone, phloroglucin, bisphenol A, bisphenol F, bisphenol S, and dihydroxynaphthalene. These can be used alone or in combination of two or more.

Specifically, first, water, alkaline earth metal salt, phenols and aldehydes are added, and the reaction is carried out with stirring in a temperature range of 88 ° C. or higher and lower than reflux conditions for 10 minutes or more and 60 minutes or less. In addition, pH of the solution at the time of reaction is 6-8.
The catalyst comprising an alkaline earth metal salt is used in a molar ratio to phenol (alkaline earth metal salt / phenol molar ratio) of 0.001 or more and 0.0025 or less from the viewpoint of solubility.

(Process (b))
Next, the solution obtained in the step (a) is acidified, and orthomethylolphenol is condensed to obtain a high ortho novolac type phenol resin as an initial condensate.
To make the solution acidic, acetic acid, formic acid, salicylic acid and the like are used. These acids are acids having a relatively high pH, and oxalic acid or the like having a low pH is preferable because the condensation reaction proceeds rapidly but the controllability of the reaction is excellent. The pH is set to 4 or more and 6 or less, and the mixture is stirred for 10 to 120 minutes in a temperature range of 88 ° C. or more and reflux condition or less. Thereby, orthomethylol phenol can be condensed to obtain a high ortho novolac type phenol resin as an initial condensate.

(Process (c))
In the step (c), in the presence of an alkaline catalyst, the high-ortho novolak type phenol resin, which is the initial condensate obtained in the step (b), is reacted with aldehydes to be resolated.
As the catalyst, a strong base catalyst such as sodium hydroxide or potassium hydroxide is usually used.

  When sodium hydroxide is used as the catalyst, the amount of the catalyst is good for water solubility, so the molar ratio of sodium hydroxide to phenol (hereinafter referred to as sodium hydroxide / phenol molar ratio) is 0.1 or more. Desirably, the upper limit is preferably 0.8 or less. When this molar ratio is less than 0.1, the phenol resin is slowly cured, and when it exceeds 0.8, the water resistance of the adhesive layer is lowered. From this viewpoint, the catalyst amount can be determined within the above range. 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 75 ° C. or higher until a predetermined viscosity is reached.

  As an end point of the step (c), the viscosity at 25 ° C. measured with a B-type viscometer is preferably 200 mPa or more and 450 mPa or less when the resin solid content is 40%. When the viscosity of a solution having a resin solid content of 40% is less than 200 mPa, condensation of free phenol is insufficient, and when it exceeds 450 mPa, the content of low molecular weight methylolphenol is less than 0.1% by weight. Fast curability is not imparted. By continuing the reaction up to the above viscosity, in the gel permeation chromatogram (GPC) chart of the THF-soluble matter, a resol type phenol resin having a mononuclear and binuclear content of 6% or less is obtained. Can do.

<Plywood adhesive>
The adhesive for plywood of this invention contains said resol type phenol resin.
A paste solution (adhesive for plywood) by blending water, wheat flour, calcium carbonate and other fillers, curing aids such as sodium carbonate and sodium hydrogen carbonate, and tannins with a polyphenol content of 70% or more into the resol type phenol resin. Is prepared.

<Plywood>
The plywood of the present invention is obtained by applying the above-mentioned plywood adhesive between at least two wooden veneers and then heating and pressing the veneer located in the outermost layer in the surface direction.

  Since the adhesive for plywood of the present invention includes a resol type phenol resin and has excellent low-temperature adhesiveness, a thick plywood having a thickness of 15 mm or more can be produced by a pressing process at a low temperature of about 120 ° C. Specifically, a thick plywood having a thickness of about 15 mm to 28 mm is manufactured at a heating plate setting temperature of 110 ° C. or more and 125 ° C. or less under conditions of a heating time of 20 seconds / mm or more and 30 seconds / mm or less. Can do.

  Furthermore, since the adhesive for plywood containing the resol type phenolic resin of the present invention can provide adhesion in the above temperature range, thickness reduction in the press process at high temperature is suppressed, and the yield of the product is increased. improves.

  Moreover, the adhesive for plywood containing the resol type phenolic resin of the present invention can be used for the production of plywood even when the moisture content of the wooden veneer is 10 wt% or more and 20 wt% or less. In this way, since the plywood can be created even if the veneer is not in an absolutely dry state, the drying time of the veneer can be shortened, and further, shrinkage in the width direction due to drying can be suppressed. The acquisition rate can be improved by about 3%. Thereby, while improving the manufacturing cost and manufacturing efficiency of a plywood, productivity of a plywood can be improved.

Next, this invention is demonstrated based on an Example.
[Example 1]
94 parts by weight of phenol and 76.7 parts by weight of 43% formalin (F / P molar ratio: 1.09) were added to 100 parts by weight of water, and 0.08 part by weight of magnesium oxide was further added, followed by 90 ° C. The reaction was carried out in the pH range of 6.5 to 7.5 for 50 minutes. And the acetic acid was added and it was made to react for 90 minutes in the range of pH 4.5-6 of a solution, and the low condensate of novolak phenol was manufactured. And after cooling a solution to 50 degreeC, 43% formalin 87.3 weight part and 30% caustic soda 30 weight part are added, and it heats up to 90 degreeC, and the viscosity of the reaction liquid in 25 degreeC by a B type viscometer is The reaction was continued until 350 mPa · s. Then, 62.5 parts by weight of 30% caustic soda was added while cooling the reaction solution, and further reacted at a reaction temperature of 70 to 80 ° C. at 25 ° C. until the viscosity of the reaction solution reached 370 mPa · s. A resin was obtained. Further, 10 parts by weight of water and 5 parts by weight of urea were added.

[Example 2]
The process for producing novolac phenol and the process until the viscosity of the reaction solution reached 350 mPa · s were carried out in the same manner as in Example 1. Then, after cooling the solution to 50 ° C., 87.3 parts by weight of 43% formalin and 30 parts by weight of 30% caustic soda are added, the temperature is raised to 90 ° C., and the reaction is continued until the viscosity measured by a B-type viscometer reaches 250 mPa · s. It was. Then, while cooling the reaction solution, 62.5 parts by weight of 30% sodium hydroxide is added, and further reacted at a reaction temperature of 70 to 80 ° C. at 25 ° C. until the viscosity of the reaction solution reaches 250 mPa · s. A phenolic resin was obtained. Further, 10 parts by weight of water and 5 parts by weight of urea were added.

[Comparative Example 1]
94.1 parts by weight of phenol, 210.8 parts by weight of 37% formalin (F / P molar ratio: 2.6) and 47 parts by weight of 30% aqueous sodium hydroxide solution (molar ratio of sodium hydroxide / phenol: 0.35) ) It was made to react until 70% of the phenol resin component more than the tetranuclear by the gel permeation chromatography was prepared under reflux conditions. After cooling to 70 ° C., 94.1 parts by weight of phenol, 81.1 parts by weight of 37% formalin (F / P molar ratio: 1.8, primary P / secondary P molar ratio: 1.0) and 30% water 47 parts by weight of an aqueous sodium oxide solution (sodium hydroxide / phenol ratio: 0.35) was charged and reacted at 85 ° C. until the free phenol in the resin reached 3%. After cooling, by adding water, the viscosity of the phenol resin at 25 ° C. with a B-type viscometer is adjusted to about 2.0 poise, and 61 or more phenol resin components having a tetranuclear body determined by gel permeation chromatography are obtained. %, A resol type phenolic resin containing 6% monomethylolphenol component was obtained.

  The gel permeation chromatogram (GPC) chart of the tetrahydrofuran (THF) soluble part of the resol type phenol resin obtained in Example 1 and Comparative Example 1 is shown in FIG. 1, Example 2 and Comparative Example 1 A GPC chart of the THF soluble part of the phenol resin is also shown in FIG. In the area ratio on the GPC chart, the resol type phenol resin obtained in Example 1 has a content of low molecular weight components of mononuclear (phenol, monomethylolphenol, dimethylolphenol) and binuclear of 2.0. %Met. The resol of the high-ortho novolak type phenol resin having 5 or more nuclei was 75% from the peak of the retention time of 18 to 27.

  In the resol-type phenol resin obtained in Example 2, the content of mononuclear (phenol, monomethylolphenol, dimethylolphenol) and low molecular weight components of the binuclear was 5.5% or less. The resol type phenol resin obtained in Comparative Example 1 was 6.5%. The reorsol of the high ortho novolac type phenol resin having 5 or more nuclei was 70% from the peak of the retention time of 18 to 27. The GPC measurement conditions are shown below.

Apparatus: HLC-8120 (manufactured by Tosoh Corporation)
Detector: RI
Column: 1 series of TSK-GEL G1000H (manufactured by Tosoh Corporation) and 2 series of TSK-GEL G2000H (made by Tosoh Corporation) Temperature: 40 ° C
Solvent: THF
Flow rate: 1.0 ml / min Sample: 50 μl of sample having a concentration of 1% by weight is injected

FIG. 3 shows an FT-IR chart of the resol type phenolic resin (before urea addition) obtained in Example 1 and Comparative Example 1. FT-IR measurement was performed using (Product No. AVATAR: 320, manufactured by Nicolet). The resol type phenol resin obtained in Example 1 had a peak intensity derived from a C═O bond derived from a methylol group, relative to a peak intensity derived from a C═C bond in an aromatic ring, of 0.764. . Moreover, the resol type phenol resin obtained in Comparative Example 1 has a peak intensity of 1.14, and the methylol bond amount of the resole type phenol resin of Example 1 is the methylol bond amount of the resole type phenol resin of Comparative Example 1. It was confirmed that it was reduced to about 70%.
Moreover, the resol type phenol resin obtained in Example 1 has the peak intensity (1) derived from the C—H bond substituted at the para position and the peak intensity (2) derived from the C—H bond substituted at the ortho position. The ortho / para ratio represented by the formula: (2) / ((1) × 1.3) was 0.58. The ortho / para ratio of the resol type phenol resin obtained in Comparative Example 1 was 0.57, and the ortho / para ratio was the same.

  A resol-type phenol resin composition was prepared by mixing 100 parts by weight of the resol-type phenol resin obtained in Example 1, 11 parts by weight of water, 12 parts by weight of wheat flour, and 17 parts by weight of calcium carbonate. The sex was confirmed. The storage stability test was stored in a thermostat at 30 ° C., taken out after a predetermined number of days, and the viscosity was measured with a B-type viscometer. The results are shown in Table 1. Moreover, 100 parts by weight of the resol-type phenol resin obtained in Comparative Example 1, 11 parts by weight of water, 14 parts by weight of flour, and 17 parts by weight of calcium carbonate were mixed to prepare a resol-type phenol resin composition. Storage stability was measured in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
Using the resol type phenolic resin obtained in Example 1, a paste (adhesive for plywood) having a viscosity (B type viscometer, 25 ° C.) adjusted to 15 poises with the composition shown in Table 2 was obtained.

[Comparative Example 2]
Using the resol-type phenol resin obtained in Comparative Example 1, a paste liquid (plywood adhesive) having a viscosity (B-type viscometer, 25 ° C.) adjusted to 15 poise with the composition shown in Table 2 was obtained.

  The glue solution obtained in Example 3 and Comparative Example 2 was used, and the veneer used was a 2.3 mm, 3.1 mm thick North Sea larch material, and the 3.1 mm thick larch material was used as a glue plate. The original plate was in an absolutely dry state (water content 4% or less), the paste plate was also in an absolutely dry state, and a plywood was produced at 5 ply. The molding conditions were as follows.

・ Amount of paste applied: 32 g / scale angle,
-Cold pressure conditions: Volume time 15 minutes, cold pressure time 30 minutes, pressing pressure 1 mPa
・ Hot pressure conditions: Hot plate set temperature 125 ° C, hot pressing time 3 minutes 30 seconds (16 seconds / mm), hot pressing time 3 minutes 55 seconds (17.9 seconds / mm)
The temporary adhesion, formaldehyde emission, and normal adhesion of the obtained plywood were measured, and a repeated steaming test was performed. The results are shown in Table 2.

  The measuring method of the adhesive strength was measured according to the test method described in JIS (JIS K6802 wood tensile shear adhesive strength), and the measuring method of the formaldehyde emission amount was measured according to the test method described in JAS (formaldehyde emission amount test). The repeated steaming test was conducted in accordance with the test method described in the JAS wood edition. For normal adhesion, apply 18g of paste solution prepared in the composition of Table 2 to the front side of 300mm square glue plate 3.5mm (Hokuyo Larch). And cold pressed for 5 minutes. Thereafter, the 1.8 mm original plate was digitized by measuring the peel strength (N / mm) with a spring balance.

  Moreover, the paste liquid obtained by Example 3 and the comparative example 2 was used, a single board used the cedar material of 2.3 mm and 3.1 mm thickness, and used the cedar material of 3.1 mm thickness as the paste board. . The paste plates were made to have a moisture content of 15% and 20%, and the single plates other than the paste plates were kept in an absolutely dry state (moisture content of 6% or less). In order to minimize the evaporation of moisture from the mouth after cold pressing, the tip was sealed with heat-resistant tape and hot pressed to produce a plywood at 5 ply. The molding conditions were the same as above except that the hot pressing temperature was 115 ° C., 120 ° C., 125 ° C., and the hot pressing time was 25 seconds / mm. Formability, adhesiveness and formaldehyde emission (F emission) were evaluated by the following methods. The results are shown in Table 3.

-Formability: Observed by visual observation and judged according to the following criteria.
○: Good, x: Peeling / adhesion by puncture Judgment was made according to the following criteria according to repeated steaming of special plywood of JAS standard.
○: Satisfying special adhesion level △: Peeling does not occur but does not satisfy special adhesion level ×: Exfoliation sample observed ・ Formaldehyde emission amount Measured by JAS standard formaldehyde emission amount test method, Judgment was made based on the following criteria.
A: 0.15 mg / L or less B: Over 0.15 mg / L, 0.3 mg / L or less Δ: Over 0.3 mg / L, 0.4 mg / L or less X: Over 0.4 mg / L

  In addition, also in the paste liquid (plywood adhesive) containing the resol type phenol resin of Example 2, it was confirmed that the result equivalent to the paste liquid of Example 3 was obtained.

Claims (11)

An adhesive for plywood containing a resol type phenolic resin having a mononuclear and binuclear content of 6% or less in an area ratio on a gel permeation chromatogram (GPC) chart of tetrahydrofuran solubles. The resol-type phenol resin has a ratio (O / P bond ratio) of an ortho bond methylene group (O) indicating a bond position of a methylene group to an OH group of phenol and a methylene group (P) of a para bond is 0.3 to 0.3. The adhesive for plywood according to claim 1, comprising a resol of a high ortho novolak type phenolic resin which is 1.0 . The resol type phenolic resin contains 70% or more of a high ortho novolac type phenolic resin resol having 5 or more nuclei in an area ratio on a gel permeation chromatogram (GPC) chart of a tetrahydrofuran soluble content. The adhesive for plywood described in 1. The resol type phenol resin is measured using a Fourier transform infrared spectrophotometer (FT-IR), and a C═O bond derived from a methylol group with respect to a peak intensity derived from a C═C bond in an aromatic ring. The adhesive for plywood according to any one of claims 1 to 3, wherein the peak intensity derived from is 0.5 or more and 1 or less. In the presence of a catalyst comprising an alkaline earth metal salt, aldehydes are reacted in an amount of 0.9 to 1.2 in molar ratio to phenols to prepare orthomethylolphenol, In step 1, the ortho-methylol phenol is condensed to prepare a high-ortho novolak-type phenol resin as an initial condensate, and then the high-ortho novolac-type phenol resin is reacted with an aldehyde in the presence of an alkaline catalyst to be resolated. The adhesive for plywood containing the resol type phenol resin obtained. The adhesive for plywood according to claim 5, wherein the alkaline earth metal salt is magnesium oxide, magnesium acetate, calcium oxide, or zinc acetate. A step of preparing orthomethylolphenol by reacting aldehydes in an amount of 0.9 to 1.2 in molar ratio to phenols in the presence of a catalyst comprising an alkaline earth metal salt;
A step of condensing the orthomethylolphenol under acidic conditions to prepare a high ortho novolac type phenol resin as an initial condensate;
A step of reacting the high ortho novolak type phenol resin with an aldehyde in the presence of an alkaline catalyst to form a resole;
Method for producing a resol type phenolic resin plywood adhesives comprising. The alkaline earth metal salts, magnesium oxide, method for producing plywood adhesives resol type phenolic resin according to claim 7 which is magnesium acetate or zinc acetate. A plywood in which at least two wooden veneers are bonded via the plywood adhesive according to any one of claims 1 to 6 . The wood veneer, heating conditions for bonding through the plywood adhesive, 20 seconds / mm or more, 30 seconds / mm or less, 110 ° C. or higher, Plywood according to claim 9 is 125 ° C. or less . The plywood according to claim 9 or 10 , wherein the moisture content of the wooden veneer is 10 wt% or more and 20 wt% or less.

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