JPS60135471A - Adhesive composition - Google Patents

Abstract

PURPOSE:To provide an adhesive compsn. which can bond wood having a high water content with good workability, by blending an aq. latex, a specified condensation resin, an isocyanate and a specified surfactant in a specified ratio. CONSTITUTION:An aq. latex (A) such as a butyl rubber latex or an ethylene/ vinyl acetate copolymer latex is mixed with a melamine/phenol/formaldehyde condensation resin (B) in a weight ratio of 3:7-7:3. Further, 1-20wt% (based on the combined quantity of components A and B) isocyanate (C) such as tolylene diisocyanate and 0.1-10wt% (based on the combined quantity of components A, B and C) nonionic surfactant (D) having an HLB value of 17 or above such as Emulgen 950 (a product of Kao Atlas K.K.) are blended with the above mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive composition that is suitable for bonding wood with a high moisture content and has good workability.

Currently, formalin-based condensation resin is used in the production of plywood, but in order to obtain sufficient adhesive performance, the veneer must be sufficiently dried, and the moisture content of the veneer is usually controlled to below 10 wt. It is necessary to do so. However, the moisture content of logs varies widely, and the ease with which they dry varies depending on the type of wood, which can lead to many problems with drying, which may impair productivity or cause over-drying in some cases. This also caused the problem that the veneer would crack and become unusable. To solve this problem, for example, when using veneers with a high moisture content, we need to reduce the amount of fillers such as flour and water added to the adhesive, and at the same time, we have developed methods such as soybean flour, blood meal, corn starch, etc. A method using a method of using a heat-pressing method, a method of extending the heat-pressing time, etc. have been adopted, but no satisfactory method has been found yet.

Furthermore, Japanese Patent Publication No. 57-19148 provides an adhesive comprising an aqueous emulsion containing a compound having an isonic atom group dissolved in a hydrophobic organic solvent and a surfactant. It is disclosed that it can also be used in combination. However, regarding the formaldehyde-based condensation resin that is said to be able to be used for this removal, there is no mention of the specific type or amount of the formaldehyde-based condensation resin, nor is there any description of its effects. Furthermore, anionic surfactants are particularly preferred as surfactants. However, although this method is effective for bonding wood with high moisture content, it is not sufficient, and there are also major problems in terms of workability and economy, and it is still not a practical method. No, no.

As a result of various studies aimed at achieving this objective, the present inventors found that a specific nonionic surfactant coexists in a specified usage ratio of aqueous latex, melamine phenol formaldehyde condensation resin, and isocyanate compound. The inventors have discovered that the above-mentioned problems can be solved by doing so, and have arrived at the present invention.

That is, the present invention contains (1) aqueous latex, (2) melamine phenol formaldehyde yarn wire 1i fat, and (2) an isocyanate compound, and the weight ratio of said (1) and said (2) is 3 near to 7:
3, and the dragon of said ■ is 1 to 20% by weight of the total amount of said ■ and said O, and the HLB value is 17 or more. It relates to an adhesive composition in which 0.1 to 10 weight ratio of

The aqueous latex in the present invention includes butadiene,
Latices made by copolymerizing conjugated dienes such as isoprene with monomers copolymerized with them, such as styrene, methyl methacrylate, various vinyl heptanomers such as acrylonitrile, chloroprene latex, butyl rubber latex, polyvinyl chloride emulsion, polybutadiene latex, ethylene vinyl acetate. Copolymer emulsion resin, polyvinyl acetate emulsion, or these latexes and emulsions contain carboxyl groups, N-methylol groups, N-alkoxymethyl groups, glycidyl groups, β
-Methylgrindyl group, hydroxyl group, amine group, amide group,
It includes a so-called modified latex obtained by emulsion copolymerization of at least one reactive monomer having at least one crosslinkable reactive group selected from the group consisting of acid anhydride groups in its side chain.

The melamine phenol formaldehyde condensation resin in the present invention is not particularly limited, but the molar specific strength of formaldehyde and melamine phenol is 1.5 to 3.5.
- For the melamine phenol formaldehyde condensation resin liquid, the melamine content is 10 parts by weight or more, the phenol content is 3 parts by weight or more, and the methanol content is 5 parts by weight.
Preferably, the content is 20% by weight or t%. The resin content is not particularly limited either, but usually 40 to 60% by weight is used. In addition, there are no particular restrictions on the manufacturing method, and there are no particular limitations, such as co-condensing phenol with melamine resin, co-condensing melamine with phenol resin, or co-condensing melamine, phenol, and formaldehyde at the same time. It may also be a mixture or co-condensation of a phenol resin and a melamine resin.

Furthermore, these resins may be co-condensed with urea or resorcinol.

The weight ratio of (1) aqueous latex and O melamine phenol formaldehyde condensed resin in the adhesive in the present invention is 3 to 7:3, and the ratio of (2) to the total amount of (2) and (2) is 30 to 70% by weight. range, preferably 35-65
It is in the range of weight i%.

If the proportion of aqueous latex exceeds 70% by weight,
Not only is the stability of the compounding part poor and there are problems with workability, but also a rapid decline in performance is observed over time.On the other hand, if the weight is less than 30 φ, the tolerance of the compounding part to wood with a high moisture content is not sufficient. I can't say, but I can only guarantee that the adhesive strength will be so low that punctures will occur during plywood manufacturing, or that it will not be practical.

The isocyanate compound in the present invention may be any compound containing two or more isocyanate groups in the molecule, for example, tolylene diincia L-t' (T
I) I), 4-4-diphenylmethane diisoni;
-) (MDI), hexamethylene diisocyanide, -卜(MDI),
HMDI), xylylene diisocyanate) (XDI)
, Inphorondiinosia monomer (IDi), Polymethylenepolyphenylpolyinoa monomer (Polymeric MD
I) etc.

Compounds having isocyanate groups include their polymers, such as mixtures of polyisocyanate and polyol, prepolymers, i.e., NCO-terminated prepolymers prepolymerized with polyol and excess polyisocyanate, or prepolymerization with excess polyol. 0H
It is also possible to use a polymer obtained by adding an excessive amount of polyisocyanate to the terminal prepolymer at the time of use.

The amount of the O isocyanate compound in the present invention must be 1 to 20% by weight of the total amount of the aqueous latex and @melamine phenol formaldehyde condensation resin;
Moreover, it is preferable that it is the range of 3-15 weight%. Therefore, if the amount of O isocyanate compound is less than 1% by weight, it is not possible to specify the tolerance for high moisture content wood as referred to in the present invention, whereas if it exceeds 20% by weight, the adhesive will increase over time after compounding. It is highly sticky and is not practical.

The HLB value used in the present invention is 17 or more @
The structure of the nonionic surfactant is not particularly limited, and examples include polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether,
Examples include polyoxyethylene acyl ester, and more specifically Kako Atlas (product name: Emulgen 14 made of silk).
7 (H1JB value 17.1), Emulgen 950 (HL
B value 18.2), Emulgeno 985 (HLB value 18.9)
), Emanone 3199 (HLB value 19.1), etc.

In the present invention, the coexisting amount of the nonionic surfactant with an HLB value of 17 or more is in the range of 0.1 to 10% by weight of the total solid content of the aqueous latex, the melamine phenol formaldehyde condensation resin, and the isocyanate compound. It is.

However, if this amount of coexistence is less than 0.1 weight factor, the effect of improving the performance and workability of the resulting plywood cannot be expected.
On the other hand, if it exceeds 10% by weight, problems will arise in the adhesion performance of plywood.

In the present invention, using a nonionic surfactant with an LB value of 17 or more significantly contributes to improving the performance and workability of plywood. Although it can be recognized that they contribute to the performance and workability of plywood, they are not as good as those with an HLB value of 17 or higher.There are anionic and cationic ionic types, but these If the nonionic surfactant with an HLB value of 17 or more used in the invention is replaced, or if a nonionic, anionic, and/or cationic surfactant is used in combination, the balance of the blended glue will be disrupted, resulting in extremely poor fluidity, which may cause problems in the adhesion operation. Not only will this have a serious effect, but it will also cause a decline in physical properties.In order to avoid such negative effects, anionic surfactants and cationic surfactants cannot be blended together.

On the other hand, nonionic surfactants with a l-1L B value of 17 or more play a role in significantly improving the applicability of the blended paste, and therefore greatly contribute to stabilizing the physical properties.

The present invention applies HL to aqueous latex, melamine phenol formaldehyde condensation resin, and incyanate compound.
By coexisting a nonionic surfactant with a B value of 17 or more in the ratio shown above, it is possible to obtain highly excellent adhesive performance and stable workability for the first time, and the above four components Even if one of them is missing, or even if the mixing ratio is deviated from the limited range, the effects of the present invention cannot be expected.

The nonionic surfactant having an HLB value of 17 or more used in the present invention may be added at the time of blending, or may be made to coexist in the aqueous latex and/or melamine phenol formaldehyde condensation resin in advance.

In the present invention, as an incyanate compound, a compound having an isocyanate group is dissolved in a hydrophobic solvent, that is, a solvent that has almost no mutual solubility with water and has mutual solubility with the isocyanate compound or its polymer. Although blending is also included, the blended paste of the present invention is sufficiently stable even when no hydrophobic solvent is used, and it is actually better not to use a solvent in terms of adhesive performance.

In carrying out the present invention, barley flour, rice flour, wood flour, talc, clay, etc. may be used in addition to wheat flour as a bulking agent conventionally used in plywood manufacturing, and polyvinyl alcohol for the purpose of improving temporary adhesion may be used. There is no problem in using compounds such as, blood powder, soybean powder, corn powder, etc., which are conventionally used as measures for adhesion.

When using the adhesive composition of the present invention, the viscosity is close to that of formaldehyde-based resins, so there is no need to modify gear pumps, etc. for transferring within piping (the equipment currently used for formaldehyde-based resins can be used as is). is possible.

The adhesive composition of the present invention exhibits excellent performance in adhering high-moisture content veneers, enables production of high-quality plywood even when using high-moisture content veneers, and further improves the viscosity change over time of the compounding base. It is also excellent in terms of workability, such as a small amount of adhesive and extremely good adhesive application to veneers, and can be applied to current plywood production lines as is.

Therefore, the adhesive composition of the present invention has extremely high practical value.

Next, the present invention will be explained with reference to examples, and all parts and numbers in the examples are parts by weight and % by weight.

Reference Examples 1 to 3 Monomer emulsions were prepared by charging the compositions shown in Table 1 into a tank equipped with a stirrer.

32 parts of water, 0.1 part of tetrasodium salt of ethylenediamine-tetraacetic acid, 0.1 part of sodium lauryl sulfate, and 0.2 parts of potassium persulfate were placed in an autoclave equipped with a stirrer, and 10 parts of the monomer emulsion were placed in the autoclave. The mixture was transferred, heated to 80°C, and reacted for 1 hour. After 1 hour, 0.8 parts of potassium persulfate was charged together with 20 parts of water, and the remaining monomer emulsion was continuously fed into the autoclave over a period of 4 hours. During this time, the autoclave was kept at 80°C. After maintaining the temperature at 80'C for an additional hour, residual monomers were removed by steam distillation, and aqueous ammonia was added to adjust the pH of the latex to 9.0.

Table 1 Monomer emulsion composition The latex synthesized according to Reference Example 1 is called Latex A, the latex synthesized according to Reference Example 2 is called Latex B, and the latex synthesized according to Reference Example 3 is called Latex C.

Reference Example 4 126 parts of melamine, 300 parts of 37-thiformin (methanol content 8%) and 30 parts of methanol were adjusted to pH 12.0 with a 20-thickasei soda aqueous solution, and heated with stirring. After the melamine was dissolved, 32 parts of phenol was added, the reaction was carried out at 80°C for 3 hours, and the mixture was cooled to synthesize a melamine-phenol formaldehyde condensation resin. This is M
Reference Example 5 Melamine 126 parts, 37% formalin (methanol content 8%) 235 parts, methanol 20 parts, PVA 117 (
Clan@) product name) 2, was adjusted to p[-113,O with a 20% aqueous sodium chloride solution, and heated with stirring.
The reaction was carried out at 0° C. for 2 hours and cooled to synthesize a melamine formaldehyde condensation resin.

Next, 94 parts of phenol and 200 parts of 37% formalin (methanol content 8%) were added to a p+
(Adjust to 10.0, heat with stirring, react at 80°C for 2 hours, cool, then add the above melamine formaldehyde condensation resin, stir and mix at room temperature for 30 minutes to synthesize melamine phenol formaldehyde condensation resin. This will be referred to as 4PF-2.

Examples 1 to 5 and Comparative Examples 1 to 9 Latex A, B, C synthesized in Reference Examples 1 to 3 as aqueous latex, and MPF synthesized in Reference Example 4.5 as melamine phenol formaldehyde condensation resin
-1, MPF"-2, Millionate MR (manufactured by Nippon Polyurethane Co., Ltd., trade name) as an isocyanate compound,
Million MR.

and dibutyl phthalate at a weight ratio of 4:1 (hereinafter referred to as AH), as well as fillers, various surfactants (manufactured by Kako Atlas Co., Ltd.), and water in various proportions. Then, the adhesive was prepared as shown in Table 2. These adhesives were mixed in various proportions to prepare adhesives as shown in Table 1.

Using these adhesives, 1.0+2, 04-1,
Coating amount of 4 pieces of 0 mm single plate composition is 309 /
9oo=, cold pressure 10kg/ffl for 20 minutes, hot pressure 9k
l? /crl at 115°C for 60 seconds. The moisture content of all the veneers used was 23 to 27 inches. Table 2 shows data on the viscosity increase over time, applicability, and adhesive strength of the blended glue.

(Note) Filler +11 A mixture of wheat flour and clay in a ratio of 1=1 was used.

(Note 1) Immediately after blending, at 35℃, 11]r and 2h
r The value obtained by dividing the viscosity after elapsed time.

The initial sticky helmet was adjusted to 14 to 16 voices.

(Note 2) The applicability of 3-ply plywood to the glue core was evaluated. The aging was carried out at 35°C.

(Note 3) The blended glue was aged at 35°C.

(Note 4) Indicates that the test was separated during the immersion treatment.

(Note 5) The nonvolatile content of the latex and melamine phenol formaldehyde condensation resin used here was 50%.

(Note 6) In this calculation, dibutyl phthalate in ■ is
Not included in

patent applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] (1) Contains (1) aqueous latex, (1) a melamine phenol formaldehyde condensation resin, and (2) an isocyanate compound, the weight ratio of said (1) and said O is from 3 to 7:3, and the amount of said (1) is equal to that of said (1) and said O. 1 to 20% by weight of the total amount of O, and 0.1 to 10% by weight of the total solid content of
Adhesive composition made by coexisting with.