JPS5829825B2 - Taisui Seisei Setuchi Yakuzai - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive having excellent water resistance and stability, and is particularly suitable as an adhesive for wood.

Currently, urea resins, urea-melamine cocondensation resins, phenolic resins, and the like are mainly used as adhesives for plywood or secondary processing of plywood, for example.

These are widely used because they are inexpensive and have good water resistance, but recently the formaldehyde (hereinafter referred to as formalin) that remains in them has become a problem, making the environment for plywood work worse. Formalin is emitted from furniture and houses made with this material, and it has become a major problem in the world.

Recently, various attempts have been made to reduce formalin release using urea resins, etc., and considerable results have been reported.
In essence, it is impossible to eliminate formalin, and there is a possibility that incomplete curing of the adhesive may occur due to variations in the moisture content of the veneer veneer or variations in the heat and pressure conditions during the manufacturing process. May cause formalin release.

Therefore, at present, formalin-based resins such as urea resin cannot be said to be safe at all.

Furthermore, there are adhesives for plywood that do not contain formalin at all, such as protein-based and vinyl acetate resin-based adhesives, but these are not generally used because of their poor water resistance.

Furthermore, non-formalin-based polyvinyl alcohol (hereinafter referred to as PVA) is used as an adhesive for plywood.

An example of using toy isocyanate adhesive is also reported in U.S. Patent No. 2.
This can be seen in the specification of No. 277083.

However, in this US patent, PVA and isocyanate are used in a non-aqueous system. For example, in Example 2 of the US patent, a PVA aqueous solution is applied to plywood, the water is evaporated, and then hexamethylene diisocyanate is applied on top of the PVA solution. Even if plywood is produced by applying a toluene solution and laminating them together, or by such a method, it is not possible to obtain plywood with excellent adhesive strength, especially water-resistant adhesive strength.

Furthermore, various aqueous emulsions are used in various adhesives, but they are not always sufficient in terms of water resistance.

The present invention eliminates these drawbacks and is an aqueous emulsion (excluding vinyl acetate polymer emulsion and isoprene polymer emulsion) (hereinafter simply referred to as "
(1) PVA and (
2) A compound having an isocyanate group with a boiling point of 200°C
This adhesive is made by blending the above hydrophobic solvent.

The adhesive of the present invention has excellent water resistance and various adhesive strengths.

Furthermore, the incyanate group-containing compound used in the present invention exhibits unique behavior in an "aqueous emulsion" containing PVA, and acts to impart water resistance to the composition.

The compound having an isocyanate group may be any compound containing two or more incyanate groups in the molecule, such as tolylene diisocyanate (TDI, e.g. Desmodur T from Hayer), hydrogenated TDI,
Trimethylpropane (TMP)-TDI adduct (Desmodur L), triphenylmethane triisocyanate (TTI Desmodur R)
, methylene bis-dephenyl isocyanate (MD■
Desmodur 44), hydrogenated MDI, hexamethylene diisocyanate (Desmodur N)
, xylene diisocyanate, 4,4' dicyclohexylmethane diisocyanate, and the like are representative isocyanate compounds or isocyanate polymers that can be used.

The blending ratio of the isocyanate compound or its polymer is “
1 to 300% by weight based on the "aqueous emulsion" (solid content), and 10-300% by weight when used as a plywood adhesive.
150% by weight is preferred.

In the present invention, compounds having isocyanate groups are hydrophobic with a boiling point of 200°C or higher (i.e., with a boiling point of 200°C or higher).
As described above, the solvent (hereinafter, this solvent will be simply referred to as "solvent") has almost mutual solubility with water and further has mutual solubility with incyanate compounds or polymers thereof.

) and mix.

This is particularly preferred for wood adhesives such as plywood adhesives.

If such a "solvent" is used, it will be odorless and will not cause environmental pollution problems during the bonding under heating that is normally performed, and the "solvent" will remain in the adhesive layer and act effectively as a plasticizer. In addition, incyanate compounds or polymers can be uniformly dispersed in the "aqueous emulsion", and furthermore, contact between isocyanate groups and water is reduced by emulsifying action, and incyanate groups are protected from water. You can also do that.

Further, by using an incyanate compound or a polymer thereof dissolved in the above-mentioned "solvent", an adhesive composition which is stable and has excellent water resistance can be obtained.

The "solvent" that dissolves the isocyanate compound or isocyanate polymer is normally liquid and
It means a solvent compound whose solubility in water at ~30°C and solubility in water in a solvent are both 5 wt% or less.

Typical "solvents" include aliphatic and aromatic hydrocarbons, liquid mixtures containing these as main components, halogenated hydrocarbons (such as chlorinated liquid paraffin, etc.) (e.g., tetralin, decalin, liquid paraffin, etc.), In addition to ketones (e.g. acetophenone, etc.), ethers (e.g. eva ethyl pen gel ether, etc.), esters (e.g. citric acid esters, ricinol esters, etc.), various citric acid esters (e.g. diptyl phthalate, dioctyl phthalate, phthalate). butylbenzyl acid, etc.), various oleate esters, various adipate esters, various azelaic esters, various sebacic esters, various stearic esters, various benzoic esters, various abietic esters, various oxalic esters, various phosphoric esters etc.), and other oils containing higher fatty acids as a main component, such as castor oil, can also be used.

Among these, dibutyl phthalate, dioctyl phthalate, methyl oleate, etc. are preferred.

When dissolving an isocyanate compound or its polymer in a "solvent", if the "solvent" contains active hydrogen such as a carboxyl group, hydroxyl group, or amine group in its molecule, it will react with the incyanate compound via the active hydrogen. It is not appropriate to dilute it too thinly, as this will reduce its effectiveness.

However, if such a "solvent" does not have active hydrogen, there is no particular dilution limit, so it can be diluted to a limit value that allows the isocyanate compound or its polymer-solvent system to be uniformly dispersed in water.

However, from the viewpoint of water resistance and dispersion effect, isocyanate compounds or their polymers are
Adding 1000% by weight, preferably 50 to 400% by weight,
It is best to dissolve it.

When adding an isocyanate-based compound or its polymer to an "aqueous emulsion" after dissolving it in a "solvent", it is best to disperse it uniformly with somewhat strong stirring.

In the present invention, PVA is conventional partially or fully saponified PVA, or PVA derivatives.

The degree of polymerization and degree of saponification are not particularly limited, but in particular, the degree of polymerization is 300 to 2500, and the degree of saponification is 80.
~100 mol% is preferable.

The appropriate concentration of PVA in the aqueous emulsion is 5 to 20% by weight.

In the present invention, "aqueous emulsion" refers to styrene-
Butadiene copolymer (SBR) latex Acrylonitrile-butadiene copolymer (NBR) latex, Methyl methacrylate-butadiene copolymer (MBR) latex, Chloroprene (CR) latex, Polybutadiene (BR) latex, Butyl rubber (IIR) latex rubber latex, polyacrylic acid ester latex, polyvinylidene chloride latex, polyvinyl chloride emulsion, polybutadiene latex, or carboxyl-modified latexes.

In addition, from "aqueous emulsion", vinyl acetate type (co)
Polymer emulsions and isoprene-based polymer emulsions are excluded.

The blending ratio of the "aqueous emulsion" and PVA is arbitrary, but preferably PVA (solid content) is 10 to 400% by weight, more preferably 50 to 200%, based on the solid content of the "aqueous emulsion". .

Further, when the composition of the present invention is used as an adhesive, an extender can be further added.

This extender not only acts as an extender, but also reacts with the other components of the adhesive, particularly the incyanate, to impart additional water resistance and initial adhesion to the adhesive.

As bulking agents, common bulking agents such as wheat flour, starches, defatted soybean flour, blood meal, etc. can be used (for example, bulking agents used in urea resins, etc.), but among these, wheat flour and starches are made water resistant by isocyanates. It is more preferable because it does not gelatinize in cold water but becomes gelatinized and viscous by heating during adhesion.

Further, fillers can also be added to the composition of the present invention.

This filler also not only acts to prevent excessive penetration of the adhesive into the wood, but it also reacts with the other adhesive ingredients, especially incyanate, to give the adhesive additional water resistance and initial adhesion properties. It will also have an effect.

Inorganic fillers such as clay, kaolin, and talc are used as fillers, but organic fillers such as wood flour and walnut shell powder can also be used.

The blending ratio of these extenders and/or fillers varies depending on the composition, especially the purpose of use of the adhesive, but is 10 to 100% by weight of the "aqueous emulsion", especially 15 to 50% by weight for plywood adhesives. A range of is appropriate.

Further, these extenders and fillers may be used alone or in combination, but it is also preferable to use the extenders and fillers at the same time.

Furthermore, reaction promoters such as boric acid, aluminum sulfate, light bread, chromium borate, and water glass can also be added to the adhesive of the present invention.

When the composition of the present invention is used as an adhesive, it is possible to achieve sufficient adhesion by just adhesion at room temperature (cold pressing), but in order to further improve adhesive strength and water resistance, adhesion by hot pressing is preferable.

The composition of the present invention is suitable as an adhesive, particularly for plywood or its secondary processing, but is also suitable for use in woodworking, particle board, corrugated board, etc., metal foil bonding, paper use, and commercial use. , adhesives for textile processing, or ceramics, inorganic boards (cement-based inorganic boards (asbestos slate boards,
Pulp - cement boards, concrete boards, etc.), mineral and inorganic boards (asbestos, rock wool, etc.), plastic sheets (e.g. PVC tiles, asphalt tiles)
It can also be applied to bonding glass plates, etc.

In addition, it can be applied as a coating composition for clay coatings and paints.

Next, the present invention will be further explained by examples, but the present invention is not limited thereto.

Example l 10% aqueous solution 1 of PVA117 (Kuraray holvinyl alcohol, degree of polymerization 1750, degree of saponification 98.5 mol%)
2002 of Polylac ML505 (butadiene/methyl methacrylate copolymer latex manufactured by Mitsui Toatsu Co., Ltd., concentration 47%) was added to the mixture under stirring.

This liquid is called liquid A. On the other hand, prepare Millione) MR (MDI-based incyanate-based polymer manufactured by Nippon Polyurethane), and for each 15P of Millione) MR, add the following solvent, which is incompatible with water but compatible with Millionate MR, namely diheptyl phthalate. (boiling point approximately 386℃, boiling point of 5mmHg, calculated from 212℃), dibutylphta v-) (boiling point 3
39℃), dioctyl phthalate**-to (boiling point 390℃)
, methyl oleate (boiling point approximately 260℃, boiling point 110℃ Hg, calculated from 190℃), acetyltriethyl citrate (boiling point 294℃), dibutyl maleate (boiling point 280℃)
A mixture of 2Of each of 7 types of Toyoparax 145 (chlorinated paraffin manufactured by Toyo Soda) (boiling point 200°C or higher) with 5i sufficiently mixed therein was used as liquid B.

Next, liquid B was dispersed in liquid A using a motor at a ratio of 2C1 of liquid B to 120 g of liquid A, and 401 calcium carbonate was further mixed and dispersed to form an adhesive liquid.

Immediately after preparation, these adhesive solutions were applied to lauan material (0.7 mm + 1
．． 4mm+0.7mm) under the following conditions.

Application amount 22? / scale 2, deposition time 20 minutes, cold pressure condition 0.1
kg/crA-20 minutes, standing time 30 minutes, heat pressure condition 1
Table 1 shows the hot and cold water adhesive strength and adhesive viscosity based on the JAS standard of the plywood bonded under the above conditions at 20° C.-10 kg/crA-1 minute.

As mentioned above, all of the experiments A1 to 7 using the composition of the present invention had good initial adhesion (temporary adhesion), not only satisfying the JAS standard of 7 kg/crtf, which is easily the passing line, but also having stable adhesive fluid viscosity. The adhesive properties were also relatively good, and the stability was good due to the adhesive solution having the same composition without adding any solvent.

Example 2 A 10% aqueous solution of PVA 117(7) was heated to 500'? The following emulsions 51 were mixed with 75 g of this PVA117 aqueous solution using a motorized stirrer to obtain liquid A.

The following six types of emulsions were used.

(1) Polylac AL-2 (Mitsui Toatsu butadiene/acrylonitrile copolymer latex with a concentration of 40%) (2
) Primal B-15 (acrylic ester latex manufactured by Nippon Acrylic Chemical Co., Ltd., concentration 48%) (3) Butyl latex 80-21 (Enjay chem-co
Isobutyne/isoprene latex, concentration 55%)
, (4) polychloroprene latex (concentration 50%),
(5) Polybutadiene latex (concentration 50%), <6
) COHOLEX 1'021 (concentration: 50% butadiene/methyl methacrylate copolymer latex manufactured by Nippon Gas Chemical) On the other hand, dibutyl phthalate (boiling point 339°C) was added to 3 parts of PAPi 901 (MDI isocyanate compound manufactured by Kasei Upjohn). 7 parts of B solution mixed well at a ratio of 1 part
01 was prepared.

Next, after dispersing liquid B in liquid A** at a ratio of liquid B LOP to 8C1 of each human fluid, further kaolinite clay 1
M', wood flour 4r, wheat flour 41, and cornstarch 21 were dispersed to prepare a total of 6 types of adhesive liquids.

Using the obtained adhesive liquid, plywood was produced under the same conditions as in Example 1, and the hot and cold water adhesive strength was measured based on the JAS standard.

The results are shown in Table 2. Table 2 shows that all of Experiments A1 to 6 of the present invention achieved the pass line of <7 kg/crA or more based on the JAS standard.

In either case, the initial adhesive strength was good.

Example 3 10% aqueous solution 1 of PVArC8TJ (polyvinyl alcohol manufactured by Kuraray, degree of polymerization 1750, degree of saponification 96 mol%)
Crossren NS-16 (butadiene/acrylonitrile copolymer latex manufactured by Narita Pharmaceutical Co., Ltd. at a concentration of 40 parts)
%) A liquid A 5001 mixed at a ratio of 20 parts was prepared.

On the other hand (1) PAPi 135 (M made by Kasei Upjohn)
DI incyanate)/dibutyl phthalate (boiling point 3
39℃) with a mixing ratio of 3/1 (2) bamboo shoots) 500 (
Xylene diisocyanate (manufactured by Takeda Pharmaceutical) 7 Dibutyl phthalate (boiling point 339°C) Mixing ratio of 3/1 (3)
Two CIs each of three types of B liquids with a mixing ratio of 3/1 were prepared.

Next, 20 g of liquid B was added to 120 g of liquid A, stirred and dispersed, and 1 gram of aluminum hydroxide powder was added as a filler.
0 parts, 5 parts of wood flour, and 5 parts of wheat flour were added, stirred, and dispersed to obtain an adhesive liquid.

Immediately after preparing the four types of adhesive solutions described above, three sheets of lauan material having an equal thickness of 1.4 mm were bonded together under the following conditions.

Coating amount 30r/shaku2, cold pressing condition 10kg/crA6
After 0 minutes and 2 days later, the hot and cold water adhesion strength was measured based on JAS standards, and the results are shown in Table 3.

As is clear from Table 3, all of them are based on the JAS standard.
The initial adhesive strength was also good, showing an adhesive strength of 7 kg/crrf or more.

Claims (1)

[Claims] 1 Aqueous emulsion (excluding vinyl acetate polymer emulsion and isoprene polymer emulsion)
) and (1) polyvinyl alcohol and (2) a compound having an isocyanate group dissolved in a hydrophobic solvent having a boiling point of 200° C. or higher.