JP2006257271A - Adhesive for plywood and method for producing plywood - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an adhesive for plywood, which has excellent coating property and causes no blowout phenomenon and to provide a method for producing plywood using the same. <P>SOLUTION: The adhesive for plywood comprises a resol type phenol resin (A) and a polymer (B) obtained by polymerizing a polymerizable monomer containing an acrylic acid ester, preferably a 1-10C straight-chain hydrocarbon group-containing (meth) acrylic acid ester. The method for producing plywood comprises coating veneers with the adhesive for plywood and bonding the veneers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an adhesive for plywood that has good coatability and does not generate a puncture phenomenon, and a method for manufacturing a plywood using the same.

  As the adhesive for plywood used for manufacturing the plywood, for example, an adhesive obtained by mixing a thermosetting resin, a curing accelerator, a filler, and a viscosity modifier is used. As the thermosetting resin used here, for example, urea resin, urea melamine resin, resol type phenol resin and the like have been conventionally used. This resol type phenolic resin is generally slower to cure than urea resin and urea melamine resin and requires high temperature and long time heat pressure. However, in view of health consciousness, there is an increasing demand for reduction of formaldehyde emission. In recent years, the amount of adhesive for plywood using a resol-type phenolic resin, which can achieve low formaldehyde comparatively easily, is increasing.

  For example, after applying the above-mentioned adhesive for plywood to a single plate, the plywood is stacked on each other and pressed at room temperature (cold pressure), and then the pressure is usually applied under heating at about 120 to 150 ° C. It can be manufactured by applying (hot pressing). By the way, in such a process, the water vapor pressure is larger than the cohesive force of the adhesive due to the adhesive and the water vapor from the veneer during the hot pressure, and as a result, the phenomenon that the adhesive layer expands due to the vapor pressure during the decompression. (Puncture phenomenon) may occur.

  As an adhesive for plywood that prevents this puncture phenomenon and cures in a short time, for example, an adhesive for plywood containing sodium bicarbonate and propylene carbonate as a curing accelerator in a resol type phenol resin is disclosed. (For example, refer to Patent Document 1). However, since the adhesive for plywood is required to be cured quickly, the viscosity of the adhesive is remarkably increased. Specifically, the viscosity after 60 minutes has been increased to more than twice the viscosity at the time of preparation. End up. Therefore, there is a problem that it is difficult to apply the adhesive uniformly and the workability at the time of manufacturing the plywood is not good.

JP 2000-117704 A

  An object of the present invention is to provide an adhesive for plywood that does not generate a puncture phenomenon at the time of manufacturing plywood and has a small increase in viscosity of the prepared adhesive, and a method for manufacturing a plywood using the adhesive for plywood. is there.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor obtained an adhesive obtained by mixing a polymer obtained by polymerizing a polymerizable monomer containing an acrylate ester with a resol type phenol resin. No occurrence of puncture, low viscosity increase after preparation, good coatability and excellent workability in plywood production, and bonding the veneer by applying the adhesive to the veneer It has been found that the plywood manufacturing method can easily manufacture plywood having excellent strength, and the present invention has been completed.

  That is, the present invention comprises a plywood adhesive comprising a resol type phenolic resin (A) and a polymer (B) obtained by polymerizing a polymerizable monomer containing an acrylate ester. Is to provide.

  Moreover, this invention provides the manufacturing method of the plywood characterized by apply | coating the said adhesive agent for plywood to a single plate, and adhere | attaching a single plate.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive for plywood which does not generate | occur | produce a puncture phenomenon at the time of plywood manufacture, and also has a little raise of the viscosity of the prepared adhesive can be provided. Moreover, the manufacturing method of the plywood which can manufacture the plywood which is excellent in intensity | strength easily by using this adhesive agent for plywood can be provided.

  The resol-type phenol resin (A) used in the present invention is obtained, for example, by reacting phenols and aldehydes under an alkaline reaction catalyst.

  The phenols are not particularly limited, and examples thereof include alkylphenols such as phenol and cresol; aromatic diols such as resorcinol and catechol; bisphenols such as bisphenol A and the like.

  Examples of the aldehydes include formaldehyde, paraformaldehyde, and acetaldehyde.

  Examples of the alkaline catalyst include sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide and the like.

  The use ratio of the phenols and aldehydes is preferably 1 or more in the molar ratio of [(aldehydes) / (phenols)] because the curing rate of the resulting resol-type phenol resin is fast, and the aldehyde from the produced plywood 3.5 or less is preferable because the production environment is improved. Among these, the molar ratio of [(aldehydes) / (phenols)] is particularly preferably 1.5 to 2.5.

  The amount of the alkaline reaction catalyst used is preferably from 0.1 to 3.0 mol, more preferably from 0.2 to 1.0 mol, based on 1 mol part of the total phenols.

  In addition, in order to improve the curability of the adhesive for plywood of the present invention, a resole co-condensed with aldehydes using a resorcinol, aminophenol or other modifier as part of the phenol as a resole type phenol resin (A) A type phenolic resin can be used in combination. The modifying agent is preferably used in an amount of 0.1 to 20% by weight based on the weight of the resin because a good effect of improving curability is obtained and the cost is not easily increased.

  The polymer (B) used in the present invention is obtained by polymerizing a polymerizable monomer containing an acrylate ester. The polymer (B) can be obtained, for example, by subjecting a polymerizable monomer containing an acrylate ester to emulsion polymerization in the presence of an emulsifier and an initiator.

  Examples of the acrylic ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl ( (Meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, dodecyl (meth) acrylate, stearyl ( (Meth) acrylate and other straight chain hydrocarbon group-containing (meth) acrylic acid esters; cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate and other alicyclic hydrocarbon groups Yes of (meth) acrylic acid ester; phenyl (meth) acrylate, benzyl (meth) acrylate aromatic ring-containing (meth) acrylic acid ester. As the acrylic acid ester, a linear hydrocarbon group-containing (meth) acrylic acid ester is preferable, and a linear hydrocarbon group-containing (meth) acrylic acid ester having 1 to 10 carbon atoms is more preferable. Acrylic acid esters may be used alone or in combination of two or more.

  Examples of the monomer that may be contained in the polymerizable monomer together with the acrylate ester include, for example, a conjugated diene compound, an aromatic vinyl compound, a vinyl cyanide compound, an α-β unsaturated carboxylic acid compound, and a multifunctional compound. And monomers.

  Examples of the conjugated diene compound include butadiene and isoprene. Examples of the aromatic vinyl compound include styrene, α-methylstyrene, p-methylstyrene, and the like. Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile.

  Examples of the α-β unsaturated carboxylic acid compound include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and the like. Examples of the polyfunctional monomer include divinylbenzene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol (meth) acrylate, polyethylene glycol di (meth) acrylate, and polypropylene glycol di (meth). ) Acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate and the like.

  In addition to the above monomers, vinyl acetate, hydroxyalkyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, glycidyl (meth) acrylate, acrylamide, methacrylamide, N-methylolacrylamide, N-methoxymethyl acrylamide, N-methoxybutyl acrylamide and the like can also be used.

  As the polymer (B) used in the present invention, a polymerizable single amount containing an allylic acid ester so as to be 0.1 to 40 parts by weight with respect to 100 parts by weight of the solid content of the resol type phenol resin (A). The polymer obtained by using the body is preferable because the adhesive for a plywood having a high curing rate and a long usable time (usable time) is obtained, and the resin content of the resol type phenol resin (A) is 100% by weight. More preferred is a polymer obtained by using a polymerizable monomer containing an allylic acid ester so as to be 0.1 to 30 parts by weight with respect to parts, and allylic acid so as to be 0.2 to 20 parts by weight. More preferred is a polymer obtained using a polymerizable monomer containing an ester.

  As the emulsifier used for the preparation of the polymer (B) used in the present invention, for example, a reactive emulsifier having a carbon-carbon double bond can be preferably used. As such a reactive emulsifier, for example, those having an alkylphenyl group as a hydrophobic group and a polyoxyethylene group as a nonionic hydrophilic group are preferable. Among them, alkyl propenyl phenol ethylene oxide 20 mol adduct, 30 mol adduct, 50 mol adduct (Aqualon RN-20, RN-30, RN-50, Daiichi Kogyo Seiyaku), alkyl propenyl phenol polyethylene oxide 10 mol adduct Sulfate ammonium salt, 20 mol adduct sulfate ammonium salt (Aqualon HS-10, HS-20, Daiichi Kogyo Seiyaku), 1-alkylphenoxy-3- (2-propenyl) oxy-propane-2 -All ethylene oxide adducts or sulfates thereof (rear soap NE-10, NE-20, NE-30, NE-40, SE-10N; manufactured by Asahi Denka Kogyo).

  Examples of the initiator used for preparing the polymer (B) used in the present invention include benzoyl peroxide, lauryl peroxide, cumene peroxide, diisopropyl peroxycarbonate, di-t-butyl peroxide, and t-butyl peroxide. Peroxides such as benzoate; azo compounds such as azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile; and inorganic compounds such as ammonium persulfate and potassium persulfate.

  The polymer (B) of the present invention is preferably obtained by polymerizing a polymerizable monomer containing a linear hydrocarbon group-containing (meth) acrylic acid ester. What is obtained by polymerizing a polymerizable monomer containing 10 (meth) acrylic acid esters containing a linear hydrocarbon group is more preferred.

  The adhesive for plywood of the present invention can be obtained, for example, by stirring and mixing the resol type phenol resin (A) and the polymer (B). Moreover, the adhesive for plywood of this invention can add a hardening accelerator, a viscosity modifier, a filler, etc. further as needed.

  As the mixing ratio of the resol type phenolic resin (A) and the polymer (B), the adhesive of the present invention is rapidly cured, and a plywood having excellent heat resistance and water resistance can be obtained. The polymer (B) solid content is preferably 5 to 50 parts by weight, more preferably 10 to 30 parts by weight, based on 100 parts by weight of the phenol resin (A) solids.

  Examples of the curing accelerator include sodium carbonate and sodium hydrogen carbonate. Examples of the viscosity modifier include water.

  Examples of the filler include wheat flour and calcium carbonate.

  The method for producing a plywood of the present invention is characterized in that the plywood adhesive of the present invention is applied to bond a single plate. The plywood as used in the present invention refers to a product obtained by applying an adhesive on a single plate, laminating, and curing by hot pressing, and includes, for example, general plywood or other LVL (Laminated Veneer Number).

  Examples of the production method of the present invention include: 1. Adhesive is applied to a single plate, and a predetermined number of sheets are stacked. Then, the manufacturing method including the process of hardening the plywood temporarily bonded by cold pressure at 120-150 degreeC by hot pressure is mentioned. Further, after curing, the plywood is completed through processes such as ear trimming, surface finishing, sorting, and inspection.

  Hereinafter, the present invention will be described with reference to examples and comparative examples. The parts and% described below are based on weight unless otherwise specified.

Production Example 1 (Synthesis of resol type phenol resin)
1000g of phenol, 1596g of 40% formaldehyde aqueous solution and 900g of ion-exchanged water are put in a flask equipped with a refluxing device, and stirring is started. The temperature is raised to 80 ° C while gradually adding 400g of 50% aqueous solution of sodium hydroxide, The reaction was allowed to proceed for 5 hours to obtain a water-soluble resol type phenol resin. The obtained resol-type phenol resin had a nonvolatile content concentration of 40%, a viscosity of 120 mPa · s, and a pH of 11. This is abbreviated as resin (A1).

Production Example 2 [Synthesis of Polymer (B)]
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 290 g of deionized water and Aqualon KH-10 [Reactive emulsifier manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: active ingredient 100%] 1 g was added, and the temperature was raised to 80 ° C. while blowing nitrogen. Under stirring, 0.02 g of ammonium persulfate was added, followed by a monomer mixture consisting of 228 g of n-butyl acrylate, 152 g of methyl methacrylate, 8 g of glycidyl methacrylate and 12 g of methacrylic acid, 3 g of Aqualon KH-10 and 80 g of deionized water. And 10 g of a monomer pre-emulsion emulsified by adding and a polymerization reaction was carried out for 60 minutes while maintaining the temperature in the reaction vessel at 85 ° C. Subsequently, while maintaining the temperature in the reaction vessel at 80 ° C., 73 g of the monomer pre-emulsion and 40 g of 1.0% aqueous solution of ammonium persulfate were kept at 85 ° C. using a separate dropping funnel. The polymerization was carried out dropwise over 240 minutes. After completion of the dropping, the mixture is stirred for 120 minutes at the same temperature, and the contents are cooled. Then, the pH is adjusted to 7.5 with aqueous ammonia (10% active ingredient), filtered through a 200-mesh wire mesh, and an acrylic polymer. An aqueous dispersion was obtained. The aqueous acrylic polymer dispersion obtained here had a solid content concentration of 48.8% and a viscosity of 200 mPa · s. This is abbreviated as polymer (B1).

Production Example 3 (same as above)
An acrylic polymer aqueous dispersion having a solid content concentration of 48.8% and a viscosity of 200 mPa · s was obtained in the same manner as in Production Example 2, except that 2-ethylhexyl acrylate was used instead of n-butyl acrylate. This is abbreviated as polymer (B2).

Example 1
Resin (A1), polymer (B1), curing accelerator, filler and viscosity modifier were blended as shown in Table 1 to prepare an adhesive for plywood of the present invention (viscosity 20 dPa · s / 25 ° C.). Rotary veneer made from larch using this plywood adhesive, size 30.3cm x 30.3cm, 3.0mm thick glue core veneer, 2.1mm thick original plate and original middle plate veneer ( The water content is 6% for each, and the adhesive core veneer is coated on both sides with an adhesive for plywood in an amount of 19 g / scale ² per side, 2.1 / 3.0 / 2.1 / 3 A sample of a 0.0 / 2.1 mm 5-ply configuration was set, cold pressed at 1 MPa for 30 minutes, and then hot pressed at 120 ° C. × 0.9 MPa for 240 seconds to form a plywood. The presence or absence of a puncture phenomenon during plywood formation was confirmed visually. In addition, the tensile shear force, the average tree breakage rate, and the pass rate after the repeated steaming test were measured in accordance with the rules stipulated in the Japanese Agricultural Standard “Structural Plywood”. Furthermore, the viscosity of the plywood adhesive immediately after blending, 30 minutes after blending and 60 minutes after blending, and the workability of applying the adhesive for plywood 60 minutes after blending when each compound is blended to prepare a plywood adhesive It evaluated according to. These results are shown in Table 1 together with the composition of the adhesive for plywood.

  Evaluation method of coating workability: When the initial viscosity of the compounding paste exceeds 40 dPa · s, or even when the initial viscosity is 40 dPa · s or less, it is stored at 25 ° C. and becomes 60% or more of the initial viscosity after 60 minutes. The coating workability was judged to be poor.

Examples 2 and 3 and Comparative Examples 1 and 2
A plywood adhesive was prepared in the same manner as in Example 1 except that the composition shown in Table 1 was used. Various examinations were performed in the same manner as in Example 1, and the results are shown in Tables 1 and 2.

Claims (6)

An adhesive for plywood comprising a resol type phenol resin (A) and a polymer (B) obtained by polymerizing a polymerizable monomer containing an acrylate ester. The resol-type phenol resin (A) is obtained by using phenols and aldehydes in a molar ratio [(aldehydes) / (phenols)] of 1.5 to 2.5. Item 2. The adhesive for plywood according to Item 1. The polymer (B) is obtained by using a polymerizable monomer containing an allylic acid ester so as to be 0.1 to 30 parts by weight with respect to 100 parts by weight of the solid content of the resol type phenol resin (A). The adhesive for plywood according to claim 1, comprising a polymer to be produced. The polymer (B) is obtained by using a polymerizable monomer containing a (meth) acrylic acid ester containing a linear hydrocarbon group having 1 to 10 carbon atoms as an acrylic acid ester. The adhesive for plywood according to 1. The mixing ratio of the resol type phenol resin (A) and the polymer (B) is 10 to 30 parts by weight of the polymer (B) solid content with respect to 100 parts by weight of the solid content of the resol type phenol resin (A). The adhesive for plywood of any one of 1-4. The manufacturing method of the plywood characterized by apply | coating the adhesive agent containing the plywood adhesive of any one of Claims 1-5 to a single plate, and adhere | attaching a single plate.