JPS6035953B2 - Manufacturing method of adhesive for plywood - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a plywood adhesive.

As a matter of fact, urea-formalin resin and melamine-formalin resin are widely used as adhesives for plywood.
Generally, polypynyl alcohol and starch are added as temporary adhesion improvers, and carboxymethyl cellulose is usually added as a thickener. In this case, in order to further improve the temporary adhesion, it is necessary to increase the amount of polyvinyl alcohol and starch, but it lacks stability and cannot be stored for a long time. Therefore, at present, polyvinyl alcohol and carboxymethyl cellulose are used in combination, with the mixing ratio appropriately changed. In this case, it is not possible to achieve a large temporary adhesion, and the formulation is complicated, making it impossible to obtain a useful and inexpensive adhesive. In addition, starch is an inexpensive additive that has a certain degree of temporary adhesive strength and thickening effect.
Because starch has aging properties, it lacks storage stability and appears to have poor temporary adhesion.

Ether starch is a product that removes the drawbacks caused by starch, but although the storage stability is improved by removing starch aging, a large amount is required for temporary bushing, and it is necessary to use it in combination with polyvinyl alcohol. This could not provide cheap adhesive strength. In order to overcome the above-mentioned drawbacks, the present inventors conducted extensive research in search of a thickening stabilizer with high temporary adhesion, and discovered that cationic starch is suitable for such uses, and completed the present invention. It came to this.

In other words, when producing urea or melamine and formaldehyde resin according to the conventional method, if a stable cationic starch conductor is added, it will have good storage stability and good fluidity for workability, and will have good fluidity during cold pressure. It was possible to obtain an inexpensive adhesive for plywood that excels in temporary adhesion, does not produce gel when ripe, shows favorable affinity for wood, provides excellent water resistance upon thermosetting, and is inexpensive.

Furthermore, the resin liquid using this cationic starch had excellent effects. That is, since cationized starch has a flocculating effect, adding a small amount of water produces a water-insoluble flocculated precipitate. Therefore, when mechanically cleaning the coating roller, etc., adding a small amount of water to the remaining resin liquid creates a cloudy precipitate, which can be easily separated from the liquid, so the precipitate can be reused by adding it to new resin liquid. At the same time, the liquid can also be used again as a cleaning liquid. In this way, the amount of industrial wastewater is extremely reduced or almost eliminated, and since the precipitate can be recovered and reused, it is possible to reduce costs and is also advantageous in terms of pollution control.

Therefore, the object of the present invention is to provide urea and/or
The object of the present invention is to produce various advantages obtained by co-condensing melamine with formaldehyde or by adding a cationized starch derivative after condensation. What is co-condensed for the production of resin liquid may be urea and formaldehyde, melamine and formaldehyde, or urea, melamine and formaldehyde, and the co-condensation is carried out according to a known method in an appropriate molar ratio of 70 to 90.
Heating to o0, addition reaction and condensation reaction are carried out.

The cationized starch to be used for this purpose is untreated starch or starch-containing materials such as potato, corn, wheat, rice, tapioca, and sago, or oxidation, acid treatment, dextrinization, enzyme treatment, crosslinking, etherification, and esterification of these. A cationizing agent is added to any of the modified starches obtained by a known reaction to a degree of substitution of 0.005 to 0.
．． 1 (0.005 substituents per mole of glycol anhydride residue)
~0.1 mol) is suitable.

The degree of cationization of starch varies depending on the amount of starch used, but preferably the degree of substitution is 0.01 to 0.05, and when more stability of the starch itself is required, a nonionic substituter is used by using an ester or ether bond. More needs to be introduced. A commonly used cationizing agent is used to cationize starch.

When separated, the cationizing agent can be divided into primary amines, secondary amines, tertiary amines, and quaternary ammonium salts.

Among these, preferred are tertiary amines and quaternary ammonium salts. Examples of tertiary amines include 2-
Jetylaminoethyl chloride, 3-dibutylamino-1,2-epoxypropane, 8-chloroethylmorpholine, chloromethylpyrrolidine, etc. can be used. In addition, examples of quaternary ammonium salts include, for example, 3-
Chloro-2-hydroxypropylmethylammonium chloride, 2,3-epoxypropyltrimethylammonium chloride, 4-chlorobutenetriethylammonium chloride, 3-chloro-2-hydroxypropyltriethylammonium chloride, 3-chloropropyl (N-ethyl) piberi Zin chloropropyl (
N-ethyl)piverizine chloride, etc. can be used. However, cryl or chloride in the above compounds can be replaced with other halogens. In addition to cationic starch obtained by directly reacting with a cationizing agent, there are also cationically modified starches obtained by reacting epichlorohydrin with starch and then alkylamine, and starch produced by ether-bonding acrylamide with starch. Any substance containing a substituent that ultimately exhibits cationic properties may be used, such as cationic modification by Hofmann decomposition or Mannich reaction, or cationic modification by ether bonding (meth)acrylonitrile to starch and then hydrogenation.

It also includes starch modified by graft copolymerization with cationic monomers such as (meth)acrylic acid alkyl esters or quaternary ammonium salts thereof, vinylpyridine, and derivatives thereof. It is also possible to carry out cationic modification after graft copolymerizing acrylamide, (meth)acrylonitrile (meth)acrylic acid glycidyl ester, etc. The amount of cationized starch added is usually 0.2 to 3. Preferably within the range of weight %〈 is 0.5~
It is 2.0% by weight.

Next, specific embodiments of the present invention will be described with reference to Examples.

Reference example 1 After dissolving 2.5 parts of caustic soda (vehicle, same below) and 5 parts of sodium sulfate in 150 parts of water, 1 part of untreated potato starch
0 anchor was uniformly suspended, 7.5 parts of ethylaminoethyl chlorite was added while stirring, and the reaction was carried out at 4,000 ℃ for 6 hours.

After finishing, neutralize and wash with water. Dried to obtain powdered jetylaminoethyl potato starch. Degree of substitution 0.07 Example 1 Urea 120 (2 mol) and 37% formaldehyde 3
08 days (3.8 mol) was mixed with 2 days of jetylaminoethyl potato starch obtained in the reference example.
The pH was adjusted to 8.5 and reacted at 9000 for 6 minutes, the temperature was lowered to 70°C, the pH was adjusted to 5.5 and the reaction was carried out for 60 minutes.

After completion, it was neutralized and cooled to 3000 ml. The viscosity of this resin liquid was 8 ps. Example 2 In the same manner as in Example 1, three portions of diethylaminoethyl potato starch were added and the same reaction was carried out.

The viscosity of the resin liquid was 20 ps. Example 3 In Example 1, Jethylaminoethyl potato starch 2
After removing the starch, the mixture is reacted, and after neutralization, 5 tons of Jethylaminoethyl potato starch as a reference example is added, heated for 30 minutes, and cooled to 30 qo.

The viscosity of the resin liquid was 25 ps. Comparative Example 1 The same reaction as in Example 1 was carried out by adding 4 portions of untreated potato starch instead of 2 portions of jetylaminoethyl potato starch.

The viscosity at 30:00 was 21 ps.

Comparative Example 2 The same reaction as in Example 1 was carried out by adding polyvinyl alcohol (manufactured by Nippon Gosei, completely saponified, degree of polymerization 1700) in place of the jethylaminoethyl potato starch.

The viscosity of 30oo was 5 ps. Comparative Example 3 The same reaction as in Example 1 was carried out by adding carboxymethyl cellulose (manufactured by Daicel) in place of the ethylaminoethyl potato starch.

The following tests were conducted on the resin liquids obtained in the above Examples and Comparative Examples.

1 Storage test Examples 1 to 3 and Comparative Examples 1 to 3 at storage temperature 30qo
The viscosity change over time of the resin liquid in Step 3 was measured using a BM type rotational viscometer (3 points).
The results measured in step m) are shown in Figure 1.

2. Thickening Test In Example 1 and Comparative Examples 1, 2, and 3, the viscosity of the resin liquid was measured at 30 oo by a BM rotational viscometer (3 pm) when the amount of additives added was varied.

The results are shown in FIG. Examples 1 to 3 100 parts of the resin liquid obtained in Comparative Examples 1 to 3, 20 parts of wheat flour, 13 parts of water, and 1 part of ammonium chloride were mixed to prepare a glue for plywood, and the following tests were conducted.

■ For temporary adhesion test 3, apply the above glue evenly on one side of 300 x 2 red lauan material (8-10% combined water) and apply 300 x 3 on both sides.
00x1 skin red lauan materials were pressed together at 10k9 perpendicular to the wood grain for 5 minutes, and then subjected to a tensile tester to measure the adhesive strength.

[B'Normal adhesion test and wood breakage rateNormal adhesion strength was determined using the plywood standard test method for ordinary plywood specified by JAS.The 0.7 x 1.5 x 0.7 fence was made of three layers of lauan material. The above adhesive was applied at a rate of 260 mm, cold pressed for 30 mm, 15 minutes, and hot pressed at 8 mm, 120°C, and 6 tochi sands, and its adhesive strength was measured.

The percentage of wood breakage is shown in parentheses in Table 1, which represents the percentage of parts of the adhesion layer where the painted surface cannot be peeled off and the wood is destroyed. [C' Adhesive strength test after water immersion and wood breakage rate Normal adhesive strength test
Test adhesion after soaking in cold water.

The method of expressing the wood breakage rate is the same as that for the normal adhesion test. Dissolved white precipitate test sample by dilution with water Take 10' of resin solution into a 1000' measuring cylinder, add a small amount of water, read the secretion number at the point where a cloudy coagulated precipitate starts to form, and The value obtained by dividing the number of secretions by 10M is the double amount of water.

Distilled water at a temperature of 2500 is used. The results of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1. [E} Drainage B
OD test The value of the liquid from which the white precipitate obtained in the above test (D) was removed was measured by the conventional 80D measuring method.

The results are shown in Table 1. The test results of A-B above are shown in Table 1.

Table 1

[Brief explanation of drawings]

Examples 1 to 3 and Comparative Examples 1 to 3 at storage temperature 3000
Fig. 1 shows the storage test for the resin liquid of No. 3. In Example 1 and Comparative Examples 1, 2, and 3, the viscosity of the resin liquid was measured at 3000 when the amount of additives added was varied and is shown in FIG. Figure-1 Figure-2

Claims (1)

[Claims] 1. A method for producing a plywood adhesive, which comprises adding cationized starch during or after co-condensing urea and/or melamine with formaldehyde.