JPS60210684A - Adhesive composition - Google Patents

Abstract

PURPOSE:To provide an adhesive compsn. which makes it possible to bond woods with a wide range of moisture contents, has good workability and is economical, prepd. by adding specified amts. of an aqueous latex, an isocyanate, compd. and a specified protein to a formaldehyde type condensate resin. CONSTITUTION:The adhesive compsn. is prepd. by adding 2-40pts.wt. aqueous latex (e.g. butadiene/styrene copolymer latex), 1-30pts.wt. isocyanate compd. (e.g. 4,4'-diphenylmethane diisocyanate) and 2-50pts.wt. wheat protein and/or corn protein which contains at least 30wt% protein, to 100 pts.wt. formaldehyde type condensate resin (e.g. melamine/phenol/formaldehyde condensate resin). It bonds woods having a wide range of moisture contents, with sufficiently high adhesive strength and is economical as it can be used in any existing plywood mfg. equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive that is suitable for bonding wood, is capable of bonding wood with a wide range of moisture content, has good workability in use, and is highly economical.

Currently, formaldehyde-based synthetic resins are used in the production of plywood, but in order to develop sufficient adhesive performance, the veneer used must be thoroughly dried, and the moisture content of the veneer is usually kept at 10% by weight. It is necessary to control the following. However, the moisture content of raw wood varies widely, and the ease with which it dries varies depending on the type of wood, so the moisture content of the veneer after drying will vary over a wide range, which in turn will affect the adhesive strength of the manufactured plywood. There was a problem in that the amount of plywood fluctuated greatly, making it impossible to obtain plywood of stable quality. Additionally, if excessive drying is performed, depending on the type of raw wood used, the veneer may warp or twist, making it unsuitable for normal plywood production equipment.
There was also the problem that cracks occurred in the veneer, making it unusable.

In order to solve this problem, for example, when using a high moisture content veneer, a method of reducing the amount of filler such as wheat flour and water added to the adhesive, soybean flour, blood meal, corn protein, etc. Either the method of adding 100% or extending the heat-pressing time has been used, or adhesive strength sufficient for practical use has not yet been obtained.

Furthermore, Japanese Patent Publication No. 57-18148 discloses the use of an adhesive made by blending an incyanate group-containing compound dissolved in a hydrophobic organic solvent with a surfactant in an aqueous emulsion, and in some cases formaldehyde-based condensation. It is disclosed that a resin can also be used in combination.

However, although this method is effective for bonding wood with a high moisture content, it is not sufficient, and since the main component is an aqueous emulsion, it is difficult to apply adhesive when bonding wood with a low moisture content. If it takes a long time to post-press, or if the adhesive is applied to hot wood,
It has the disadvantage that the adhesive layer dries easily, resulting in the problem of so-called dry adhesion, in which sufficient adhesive strength is not developed. In addition, since water-based latex is the main component, there are problems with economic efficiency, and the stability of the blended adhesive is poor, resulting in poor workability in actual use, so this method is still not practical. I can't say that.

In addition, water-soluble proteins such as blood meal and defatted soybean flour are sometimes used as bulking agents, but when incyanate and free formalin are present, the mixed glue tends to thicken.
This caused problems in actual use.

The present inventor aimed to obtain an adhesive composition that can bond wood with a wide range of moisture content with sufficient adhesive strength, can be easily used with currently used plywood manufacturing equipment, and is economically efficient. As a result of intensive studies with the aim of
The present invention was completed based on the discovery that the above-mentioned problems, which could not be solved by conventional techniques, could be solved by adding wheat protein and/or corn protein containing more than % by weight.

That is, the present invention comprises: (1) formaldehyde condensation resin, (2) aqueous latex, (2) incyanate compound, and (3) protein.
Contains wheat protein and/or corn protein containing at least % by weight, and when the nonvolatile content of the formaldehyde condensation resin is 50% by weight, 02 to 40 parts by weight, 01 to 30 parts by weight relative to 0100 parts by weight. Part, 02-50
This is an adhesive composition characterized in that (1) 5 parts by weight or less of a nonionic surfactant is added as necessary.

The formaldehyde condensation resins used in the present invention include urea formaldehyde condensation resins, melamine formaldehyde condensation resins, phenol formaldehyde condensation resins,
These include urea melamine formaldehyde condensation resin, melamine phenol formaldehyde condensation resin, urea melamine formaldehyde condensation resin, urea melamine phenol formaldehyde condensation resin, etc. In urea melamine phenol formaldehyde condensation resin, the molar ratio of formaldehyde to urea melamine phenol is is 1.
2-3.5, melamine content of 3% by weight or more, phenol content of 1% by weight or more, methanol content of 2-20% by weight, and the weight ratio of urea and melamine phenol is 10=1 to 1:20. is particularly desirable in terms of lateral stability of the formulation. The urea melamine phenol formaldehyde resin having the above composition may be synthesized singly, or may be prepared by mixing two or more resins in advance. Also, when blending 2
It may be adjusted by adding and mixing more than one type of resin.

The aqueous latex used in the present invention includes a latex obtained by copolymerizing a conjugated diene such as butadiene or isoprene with a monomer copolymerized therewith, such as a variety of vinyl heptamers such as styrene, methyl methacrylate, or acrylonitrile, a chloroprene latex, or a butyl rubber latex. , polyvinyl chloride emulsion, polybutadiene latex, ethylene vinyl acetate copolymer emulsion,
Polyvinyl acetate emulsion or these latex polymers contain carboxy groups, N-methylol groups, N
- A reactive monomer having at least one crosslinkable reactive group selected from the group consisting of an alkoxymethyl group, a glycidyl group, a β-methylglycidyl group, a hydroxyl group, an amine group, an amide group, and an acid anhydride group in its side chain. This includes so-called modified latex obtained by emulsion polymerization of at least one of the above.

The modified latex may be one obtained by copolymerizing a reactive heptamer during latex polymer emulsion polymerization, or
A latex polymer may be reacted with a reactive monomer.

Furthermore, two or more types of aqueous latex may be used in combination.

Furthermore, in the present invention, the blending ratio of (1) aqueous latex to (1) formalin-based condensation resin must be 02 to 40 parts by weight relative to 100 parts by weight, preferably in the range of 3 to 35 parts by weight. be.

If the blending ratio is less than 2 parts by weight, adhesion to high moisture content wood will be insufficient, punctures may occur during plywood production, and only extremely low adhesion can be expected. If the blending ratio exceeds 40 parts by weight, when using wood with low moisture content or high temperature wood, or when the blended glue is deposited for a long time after application and before cold pressing, This causes a so-called dry adhesion problem in which the adhesive layer dries and does not exhibit sufficient adhesive strength.

Furthermore, the isocyanate compound referred to in the present invention may be any compound containing two or more isocyanate groups in the molecule, such as tolylene diisocyanate (TDI),
4-4'-diphenylmethane diisocyanate (MDI
), hexamethylene diisocyanate ()IMDI)
, xylene diisocyanate (XDI), inphorone diisocyanate (IDI), polymethylene polyphenyl polyisocyanate (polymeric MDI), and the like.

Examples of compounds having an incyanate group include, for example, a mixture of polyincyanate and a polyol, a prepolymer, that is, an NGO-terminated prepolymer prepolymerized with a polyol and an excess of polyisocyanate, or
A polymer obtained by adding an excessive amount of polyisocyanate at the time of use to an OH-terminated prepolymer that has been polymerized in advance with an excess of polyol may also be used.

The amount of the incyanate compound in the present invention must be 1 to 30 parts by weight, preferably 2 to 20 parts by weight, based on 100 parts by weight of the formalin condensation resin.

If the amount of the incyanate compound is less than 1 part by weight, good adhesion to high moisture content wood cannot be expected, and if it exceeds 30 parts by weight, the adhesive after compounding will increase in viscosity over time and will be less economical. Therefore, it is not practical. As for the addition method,
Isosia.

The nate compound may be added alone or may be added after being diluted with an appropriate solvent. Alternatively, the incyanate compound may be emulsified and added.

The wheat protein referred to in the present invention has a gluten content of 30% by weight.
Above, preferably 40% by weight or more of wheat protein,
For example, wheat flour with a large amount of gluten may be used as it is, or one obtained by extracting the gluten content from ordinary wheat flour, drying it, and pulverizing it may be used. In addition, wheat flour, which is usually used as a filler for plywood, is also called powder and is made up mainly of the outer periphery of wheat particles, and contains a lot of impurities called so-called bran, and the gluten content is 5% by weight. It has a negligible amount of gluten and is distinguished from the wheat protein used in the present invention.

The corn protein used in the present invention is a protein contained in corn, and a typical example is gluten meal, which is obtained as a by-product when starch is extracted from corn.

In the production of corn protein, for example, corn is soaked in an aqueous sulfite solution, crushed in a crusher to separate and remove the germ, and then ground in a crusher to separate a milky substance. The starch is then separated from the emulsion, and the remaining liquid is concentrated, filtered and dried, and pulverized. This product usually consists of 60 to 80% by weight of corn protein, and the remainder consists of starch, ash, water, etc.

When using a large amount of wheat flour or corn flour with low protein content to obtain adhesive for high moisture content wood, the fluidity of the blended glue deteriorates and the viscosity increases over time, which is problematic for practical use. The protein content should be at least 30% to yield . Wheat protein and corn protein preferably have a particle size of 80 mesh or less in order to improve miscibility with the blended flour and uniform application of the blended paste.

Further, wheat protein and corn protein may be used alone or in combination of two or more.

The wheat protein and/or corn protein in the present invention should be added in an amount of 2 to 50 parts by weight per 00 parts by weight of the formaldehyde condensation resin, and preferably,
It is 5 to 30% by weight. If the amount added is less than 2 parts by weight, the adhesion to wood with a high moisture content will be poor, and if it exceeds 50 parts by weight, the fluidity of the blended glue will be impaired, and the adhesion with a commonly used roll spreader may be impaired. The problem arises that the performance is significantly inferior. Wheat protein and/or corn protein may be added alone at the time of blending, or they may be premixed and added to extenders or fillers added at the time of blending, such as wheat flour, barley flour, rice flour, cornstarch, clay, etc. It's okay.

The nonionic surfactant used in the present invention may be of any type, and its structural components are not particularly limited. Specific examples include polyoxymethylene alkyl ether, sorbitan fatty acid ester, polyoxyethylene acyl ester, and the like. Among them, the HLB value is 1
7 or higher is particularly preferable, and the stability of the blended paste over time,
It plays a role in improving the applicability and also contributes greatly to stabilizing the adhesive strength of the resulting plywood.

Nonionic surfactant is formaldehyde condensation resin 1
It should be blended in an amount of 5 parts by weight or less per 00 parts by weight, and may not be blended if there is no practical problem in the stability of the blended paste over time and the applicability.

It is preferable to add 0.1 to 3 parts by weight. If 5 parts by weight or more is added, the adhesive strength of the resulting plywood, especially the water resistance, will be reduced, which is not practical.

The nonionic surfactant can be added in advance to the formaldehyde condensation resin or aqueous latex.

According to this method, the complexity of adding a surfactant at the time of compounding can be eliminated, and the effect of improving the storage stability of the formaldehyde-based condensation resin can also be expected.

Moreover, two or more types of nonionic surfactants can also be used in combination. When two or more types are used in combination, it is sufficient that the HLB value of the mixture of all nonionic surfactants added is 17 or more. When added, they may be mixed in advance and added, or may be added individually.

In preparing the composition of the present invention, the formaldehyde-based condensation resin is combined with aqueous TEX, incyanate compounds, wheat protein and/or corn protein, nonionic surfactants, and bulking agents such as commonly used wheat flour, rice flour, and talc. Alternatively, a method of adding and mixing a filler, water and a hardening agent is adopted. The mixing order is not particularly limited, and the stirring time during mixing, the finished viscosity of the blended composition, etc. may be controlled under the same conditions as in a normal method. At this time, barley flour, cornstarch, wood flour, clay, etc., which have been conventionally used in plywood production, can also be used. Furthermore, polyvinyl alcohol added for the purpose of improving temporary adhesion, a water-retaining polymer compound added to prevent dry adhesion, and a deliquescent inorganic substance may be added.

Further, the amount of adhesive composition applied and bonding conditions such as cold pressure and hot pressure can all be the same as usual conditions. The fluidity of the compounded glue obtained by the present invention is equivalent to that of commonly used adhesives made by adding fillers, water, hardening agents, etc. to formaldehyde-based condensation resins, so it can be easily applied to commonly used mixers, spreaders, etc. It can be applied using equipment such as a press.

The adhesive composition of the present invention has particularly excellent performance in adhering high moisture content wood, and it is possible to produce high quality plywood even when using high moisture content veneer.

In addition, even if a veneer with a low moisture content is used or a veneer with a relatively high temperature is used, the problem of so-called dry adhesion is unlikely to occur. That is, it has the advantage of being applicable to wood with a wide range of moisture content, and this is of great significance when used in actual plywood production. Furthermore, the adhesive composition of the present invention has excellent workability, such as small changes in the viscosity of the compounded glue over time and extremely good applicability of the compounded glue to veneers, making it suitable for current plywood manufacturing lines. It also has the feature of being applicable.

Furthermore, since a formaldehyde-based condensation resin can be used as the main component in the formulation, it is effective in reducing the cost of the compounded glue, and is economical enough to enable practical use in plywood production. Further, the formaldehyde-based condensation resin can be selected depending on the required water resistance, and by selecting an appropriate condensation resin, it is also possible to optimize the cost of the blended glue.

Next, the present invention will be explained with reference to Examples, in which parts and percentages are by weight.

Reference Examples 1 to 3 (Production of aqueous latinx) The composition shown in Table 1 was charged into a tank equipped with a stirrer to prepare a monomer emulsion.

Next, 32 parts of water, 0.1 part of tetrasodium salt of ethylenediaminetetraacetic 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% of the seven-mer emulsion was placed in the autoclave. The mixture was then 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 seven-mer emulsion was continuously added to the autoclave over a period of 4 hours. During this time, the autoclave was kept at 80°C. After continuing the reaction 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 8.0. Below, the latex synthesized according to Reference Example 1 is referred to as Latex A, the latex synthesized according to Reference Example 2 is referred to as Latex B, and the latte synthesized according to Reference Example 3 Table-1 Raw materials Reference example 1 Reference example 2 Reference example 3 Water 50.0 (
parts) 50.0 (parts) 50.0 (parts) Sodium lauryl sulfate 0.3 (parts) 0.2 (parts) 0.2 (parts) Sodium bicarbonate 0.5 (parts) 0.5 (parts) 0. 4 (part)
Methacrylic acid 2.5 (parts) 3.0 (parts) 2.5 (parts) Carbon tetrachloride 2.5 (parts) 3.0 (parts) 2.8 (
parts) Butadiene 39.0 (parts) 40.0 (parts) 3
8.5 (parts) Styrene eo, o (parts) - Monomethyl methacrylate - 58.0 (parts) - Acrylonitrile - 5i 3.5 (parts) Reference example 4 (Production of formaldehyde condensation resin) Phenol 84 parts, 37% 200 parts of formalin (methanol content 8%) was adjusted in pH and pH with a 20% caustic soda aqueous solution, reacted for 2 hours at 85° C. with stirring, and cooled to obtain an intermediate raw material.

On the other hand, 240 parts of urea and 700 parts of 37% formalin (methanol content 8%) were mixed with a 20% caustic soda aqueous solution to pH 7.
After heating with stirring and reacting at 85°C for 30 minutes, the pH was adjusted to 5.0 with a 40% acetic acid aqueous solution, reacting at 856°C for 30 minutes, and further with a 20% caustic soda aqueous solution. Adjust the pH to 8.0 and add melamine 12
After adding 8 parts and reacting at 75°C for 30 minutes, 20 parts
% caustic soda aqueous solution to adjust the pH to 8.0, and cooled. The above-mentioned intermediate raw materials were added to the mixture and stirred and mixed at room temperature for 30 minutes to synthesize a urea-melamine-phenol-formaldehyde-based condensation resin. Hereinafter, this will be referred to as UMPF.

Examples 1 to 15 and Comparative Examples 1 to 9 UMPF synthesized in Reference Example 4 as a formaldehyde-based condensation resin, Nealoid U-310 (manufactured by Mitsui Toatsu Chemical Co., Ltd., urea-formalin-based condensation resin), and Nealoid U-350 (manufactured by Mitsui Toatsu Chemical Co., Ltd., melamine urea formalin condensation resin), reference example 1 as aqueous latex
Latex A, B, and C synthesized in steps 3 to 3, Millione-114R (manufactured by Nippon Polyurethane Co., Ltd., MDI series) as the incyanate compound, and wheat flour with a gluten content of 51% (manufactured by Nippon Seifun Co., Ltd., red) as the wheat protein. Gluten meal (manufactured by Oji Cornstarch Co., Ltd., crude protein content 67%) is ground to 80 mesh or less as corn starch, Emulgen 850 (manufactured by Kao Atlas Co., Ltd., polyoxy) is used as a nonionic surfactant. Ethylene nonylphenol ether type, HLB 18.
2), a filler, water, and ammonium chloride as a hardening agent were mixed in the proportions shown in Table 2 to prepare an adhesive.

1.0 +2.0 +1.0 m using these adhesives
4m+a plywood of +a veneer composition (lauan veneer, moisture content less than 4% and 23-27%) was coated with a coating amount of 33g/
Manufactured at 900cm2, cold pressure 10kg/am2.20 minutes; hot pressure 9kg/Cl112, 115°C 160 seconds.

As a filler, a mixture of wheat flour (manufactured by Nippon Seifun ■, fan, gluten content: 5%) and talc at a ratio of 1:1 was used. Table of data on compounded glue viscosity increase over time, applicability, and adhesive strength.
Shown in 2.

From Table 2, it can be seen that the adhesive composition of the present invention exhibits excellent performance in terms of thickening rate of blended paste, applicability, and adhesive strength on wood having a wide range of moisture contents.

Example 1B An adhesive was prepared using Emulgen 803 (same as above system, 1 (LB 7.8)) in place of Emulgen 950 with the same formulation as in Example 1, and a similar test was conducted. The results are shown in Table ( Note 1
) The value obtained by dividing the viscosity immediately after blending by the viscosity after 53 hours at 35°C. The viscosity immediately after blending was adjusted to 15 to 25 poise.

(Note 2) After the blended paste was left at 35°C for 3 hours, the applicability to the veneer was evaluated by the application state and workability when applying it to the veneer using a roll spreader.

(Note 3) When plywood is manufactured with a veneer moisture content of less than 4%, if the veneer is cold pressed immediately after applying the compounded glue and then hot pressed (
4%-1 in the table), and when cold pressing and hot pressing were performed after applying the blended glue to a veneer at 40°C and then cold pressing for 30 minutes (shown as 4%-1 in the table). The evaluation was carried out using two methods (indicated as -2).

The adhesive strength is JAS type 2 adhesive strength. In addition, the wood breakage rate is the percentage of the area where the wood was broken relative to the bonded area.

Patent applicant: Mitsui Toatsu Kagaku Co., Ltd. Agent, Patent attorney: Masa Inoue, Draft amendment for legal proceedings June 8, 1980, Commissioner of the Patent Office, Kazuo Wakasugi 1, Indication of case: 1989 Patent Application No. 85850, 2, Title of the invention Adhesive composition 3, Relationship with the case of the person making the amendment Patent applicant address 3-2-5-4 Kasumigaseki, Chiyoda-ku, Tokyo, Agent 103-5, Date of amendment order Voluntary 6, Increased due to amendment Number of inventions: None 8. Contents of amendment (1) The scope of claims is amended as shown in Attachment I.

(2) Page 6 of the specification is amended as shown in Attachment 2.

(3) On page 18, lines 12 and 14, "formalin-based" is corrected to "formaldehyde-based".

(4) Add the following sentence to the end of page 20.

[Examples 17 to 18 As the formaldehyde condensation resin of Example 1, U-
[1 (manufactured by Mitsui Toatsu Chemical Co., Ltd., melamine phenol formaldehyde-based condensation resin) was used to conduct the same test as in Example 1. The results are shown in Table 3. (5) Add Attachment 3 at the end of page 21 of the same.

Agent Patent Attorney Masaru Inoue Paper Attachment 1 “Claims (1) ■ 100 parts by weight of formaldehyde-based condensation resin, ■ 2 to 40 parts by weight of an aqueous latex, ■ 1 to 30 parts by weight of an isocyanate compound, and ■ An adhesive composition comprising 2 to 50 parts by weight of wheat protein and/or corn protein containing 30% by weight or more of protein.

■The formaldehyde condensation resin is a urea melamine phenol formaldehyde condensation resin, and the molar ratio of formaldehyde to urea melamine phenol is 1.2 to 1.
3.5, melamine content is 3% by weight or more, phenol content is 1% by weight or more, and methanol content is 2-2
0% by weight, the weight ratio of urea and melamine phenol is 10
．． :1-1:20 or 1.5-3.5, melamine -
is 1O-0o゛ above, 2/-2 and 3o・,
■ For 100 parts by weight of formaldehyde condensation resin, ■ 2 to 40 parts by weight of aqueous latex, ■ 1 to 30 parts by weight of incyanate compound, ■ Wheat protein containing 30% by weight or more of protein and/or 2 to 50 parts by weight of corn protein, and 5 nonionic surfactants.
An adhesive composition characterized in that the adhesive composition is blended in a proportion of not more than parts by weight.

■The formaldehyde condensation resin is a urea melamine phenol formaldehyde condensation resin, and the molar ratio of formaldehyde to urea melamine phenol is 1.2 to 1.
3.5, melamine content is 3% by weight or more, phenol content is 1% by weight or more, and methanol content is 2-2
0% by weight, the weight ratio of urea and melamine phenol is 10
：In 1:20, Norformal-Hydrogen, Molsan nonionic surfactant with HLB value of 17 or more was used. These include condensation resins, melamine phenol formaldehyde condensation resins, urea melamine formaldehyde condensation resins, urea melamine phenol formaldehyde condensation resins, etc., but in the urea melamine phenol formaldehyde condensation resins, the molar ratio of formaldehyde to urea melamine phenol is 1.2 to 1.2. 3.5. Melamine content is 3% by weight or more, phenol content is 1% by weight or more, methanol content is 2-20% by weight, and the weight ratio of urea and melamine phenol is 10:1-1:20. , and a melamine phenol formaldehyde condensation resin in which the molar ratio of formaldehyde to melamine phenol is 1.5 to 3.5.The melamine content is 10% by weight.
As mentioned above, it is particularly desirable to have a phenol content of 3% by weight or more and a methanol content of 2 to 20% by weight in terms of the stability of the blended paste over time.

The urea melamine phenol formaldehyde resin or melamine phenol formaldehyde resin having the above composition may be used singly synthesized, or two or more types of resins may be mixed and adjusted in advance, or two or more types of resins may be mixed together in advance. The resin may be added and mixed for adjustment.

Claims (4)

[Claims] (1) Wheat protein and/or corn containing 2 to 40 parts by weight of an aqueous latex, 1 to 30 parts by weight of an isocyanate compound, and 30% by weight or more of @protein, based on 100 parts by weight of a formaldehyde condensation resin. An adhesive composition comprising 2 to 50 parts by weight of protein. (2) ■2 to 40 parts by weight of aqueous latex, ■1 to 30 parts by weight of isocyanate compound, and ■wheat protein and/or corn protein containing 30% by weight or more of protein based on 100 parts by weight of formaldehyde condensation resin. white 2
50 parts by weight or less, and (1) a nonionic surfactant in a proportion of 5 parts by weight or less. (3) The formaldehyde condensation resin is a urea melamine phenol formaldehyde condensation resin, and the molar ratio of formaldehyde to urea melamine phenol is 1.
2-3.5, melamine content is 3% by weight or more, phenol content is 1% by weight or more, and methanol content is 2% by weight.
~20% by weight, and the weight ratio of urea and melamine phenol is from 10:l to 1:20.
Compositions as described in Section. (4) The composition according to claim 2 or 3, wherein the nonionic surfactant has an ILB″ value of 17 or more.