JPS5815520A - Production of modified formaldehyde resin - Google Patents

Abstract

PURPOSE:To produce a formaldehyde resin being speck-free and excellent in adhesiveness, washability and stability, by subjecting urea, melamine or a phenol and formalin to a condensation reaction in the presence of a formalin solution of a PVA resin. CONSTITUTION:A formalin solution of PVA is obtained by adding at least 5wt% PVA to formalin at room temperature and dissolving the PVC by gradually heating to 80-90 deg.C under agitation. Then a reaction tank is charged with a reactant selected from the group consisting of urea, melamine and a phenol, formalin and the above formalin solution of PVA and, after adjusting the pH, the reaction mixture is subjected to a condensation reaction. The formalin solution of PVA can be prepared in a highly concentrated form and stored in the form of a concentrated solution without any changes in fluidity with the lapse of time. Accordingly, it is possible to adopt an automatic metering system for starting materials.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a formalin-based resin modified with a boribilic alcohol-based resin (hereinafter polyvinyl alcohol is abbreviated as PVA). More specifically, in a method for producing formalin resins such as urea resin, melamine resin, phenol resin, urea melamine resin, and urea phenol resin, PVA resin is dissolved in formalin at any stage of the condensation reaction between formalin and other components. 1- A formalin that is characterized by the use of a concentrated formalin solution and has no undissolved PVA resin, and has excellent adhesiveness, cleanability, and stability, as it is called in the industry. The present invention relates to a method for producing a resin based resin.

Conventionally, in order to improve the adhesion, cleansability, and stability of formalin-based resins, PVA powder has often been added during the production of formalin-based resins. In this case, P
The mechanism of action of VA is not clear, but it is a method in which PVA powder is dispersed in a reaction system of urea, melamine, phenols, and formalin, and the PVA powder is dissolved and involved in the reaction using the reaction temperature. , a heterogeneous reaction system is generally adopted.

The problem with this method is that depending on the method and timing of adding PVA powder, the P'VA powder may not be completely dissolved and fine particles, i.e., pus, may be mixed in and reduce the product value. Although PVA with good solubility is required, it is not yet available on the market.

If particles are present in the resin, it will inhibit adhesion.Currently, when storing products, it is necessary to use a strainer when the resin has completed its reaction and is still warm and has a low viscosity.

These particles are removed as much as possible through the process. In order to minimize the occurrence of these lumps, PVA powder is actually added at the early stage of the reaction when the temperature of the reaction system is low and the viscosity is low, but these lumps still occur. Also, PVA powder is used in the form of fine particles so that it can be dissolved as quickly as possible, but it is true that the fine particles alone dissolve quickly, but when added in a certain amount, they tend to become lumpy. Currently, such fine powder PVA is added in small amounts over time to avoid creating lumps, but there are still lumps and the problem has not been solved, and the preparation time is lengthened, which is an issue in terms of streamlining the work. This is one of the problems.

The present inventors have developed a method for producing formalin-based resin modified with PVA, in addition to preventing the above-mentioned particles from being mixed in.
As a result of intensive studies aimed at the effective use of VA, we found that P was added to the reaction system.
Using a solution of PVA dissolved in formalin instead of adding VA powder3- does not achieve the above objectives, but surprisingly provides better adhesion, cleaning properties, and better cleaning properties than when adding PVA powder.
The present invention was achieved by discovering that it is possible to produce a resin with good stability. That is, the present invention uses urea, melamine,
In a method for producing a formalin-based resin, which involves a condensation reaction between at least one reaction component selected from the group consisting of phenols and formalin, a solution of a polyvinyl alcohol-based resin dissolved in formalin is added to the condensation reaction. This is a method for producing modified formalin resin that is used in steps. The formalin solution of PVA resin used in the present invention has a strong odor during its preparation.
In addition, PVA is also effective in terms of long-term storage stability as a solution.
It is superior to aqueous solutions, can be highly concentrated, and has good fluidity with no change over time, so it can be stored as a highly concentrated solution and there are no problems with preparation. It has advantages. For this reason, the use of a formalin solution of PVA allows a predetermined amount to be easily added to the reaction system from a storage tank through piping, compared to the conventional method of adding powder gradually over a long period of time. It also eliminates the deterioration of the working environment due to dust and provides industrial advantages, such as the ability to use an automatic measuring and feeding system for raw materials.

The formalin solution of PVA used in the present invention may generally be prepared in the same manner as in the case of preparing an aqueous solution of PVA. That is, formalin (usually 3
PVA powder (commercially available as an aqueous solution) is charged in this order, and the temperature is gradually raised to 80 to 90°C.If the temperature is raised and stirred for 30 minutes from the 9th point, it will be completely dissolved. It may then be cooled to room temperature and stored. The above dissolution must be carried out in a closed system to prevent formalin from escaping, but preparing an aqueous solution is also generally carried out in a closed system to prevent moisture from escaping during dissolution, so it is not particularly difficult. . P
If the concentration of VA is 5% by weight or more, it can serve the purpose of adding it instead of adding PVA powder. When adding a formalin solution of PVA that has been dissolved in advance during the production of formalin resin, it is obviously desirable to dissolve and store it at the highest concentration possible in order to streamline the work, but the upper limit concentration that can be stored and used is It varies depending on the type of PVA, but if it is PVA with a polymerization degree of about 1700, which is commonly used, it is 15wt*
It is possible up to 40 wt if the degree of polymerization is around 500
% is possible.

The PVA formalin solution thus prepared and stored is used in the production of formalin resin as follows. That is, formalin is charged into a reaction tank.

The amount of formalin used at this time is the total planned amount to be used, reduced by the amount of formalin in the PVA formalin solution that will be added later. Next, urea, melamine, or phenol is charged, and then a formalin solution of PVA is added...adjustments are made before the reaction begins. The above is an example and PVA
The formalin solution may be added at an early stage, or may be added before adding urea, melamine, phenol, etc. Further, it can be added during the reaction and while the temperature is rising, or even during the reaction at a constant temperature. In this way P
The formalin-based resin produced by adding a formalin solution of VA has better adhesion, durability, washability, and stability than the case of adding powdered PVA, and there is no visible lump in the resin and it has good strainer passability. It was found that it improved.

As the PVA used in the present invention, any PVA generally used in this field can be used, regardless of whether it is modified or not. That is, ordinary commercially available PVA, anion-modified PVA, cation-modified PVA or hydrophobic group-modified PVA
Modified PVA such as "& PV during production of taformin-based resin
Addition 1 of formalin solution A is the same as or a smaller amount than when adding PVA in the form of powder, and can be changed as appropriate depending on the purpose of use.

The present invention will be specifically explained below using reference examples, working examples, and comparative examples. In these descriptions, parts and parts are based on weight unless otherwise specified.

Reference Example Preparation of formalin solution of PVA 7-85 parts by weight of formalin with a formaldehyde content of 37q6 and an average degree of polymerization of 1700. 15 parts by weight of completely saponified PVA fine powder type PVA (Kuraray Boval PVA-1178) was charged into a dissolving tank, heated to 90°C in a closed system, and stirred for 20 minutes.

Since PVA was completely dissolved to form a homogeneous solution, the solution was allowed to cool to room temperature while stirring.

This formalin solution was left in a low-temperature constant temperature bath at 5° C. to observe changes in fluidity over time. Viscosity after standing for a specified time (ηt)
The ratio of the initial viscosity and the initial viscosity (η0) is shown in FIG. For comparison, data for an aqueous solution under the same conditions are also shown. η. In case of formalin solution, s s o o o cps at 5℃
On the other hand, the viscosity of an aqueous solution is about half that, but the change in fluidity over time of a formalin solution is much better, and there is no change at all even after 10 days of standing. The aqueous solution Vi had become a gel after one day.

Moreover, the solubility of polyhinyl alcohol powder in formalin is shown in FIG. Comparing the solubility in water, it can be seen that it dissolves more quickly and completely in formalin.

Similarly, partially saponified 8-PVA with an average degree of polymerization of 1700 (manufactured by Kuraray Co., Ltd., Kuraray Bobal 217),
Modified P containing a carboxyl group and having an average degree of polymerization of 1800
VA (Kuraray Boval KL-118 and KL-318 manufactured by Kuraray Co., Ltd.) was also dissolved in formalin and the fluidity of the solution was observed to see the change over time, but no change was found.

Example 1 239 parts of formalin (11 degrees and 37 degrees) was charged into a reaction tank, and while stirring the formalin, a 10 degree formalin solution of fine powder of completely saponified PVA with an average degree of polymerization of 1700 (Tararebo Pearl 117S manufactured by Kuraray Co., Ltd.) was added. Add 20 parts of urea, then add 100 parts of urea, adjust the temperature to 7.5 with aqueous ammonia, immediately warm it to 90°C in 30 minutes, continue the reaction at 90°C for 90 minutes, and then It became 4,5,
Since a cloudy point was observed by the underwater white clouding method, the reaction was stopped by controlling the temperature with a caustic soda solution.

Thereafter, when the mixture was cooled to room temperature and filtered through a 200-mesh mesh, no particles were observed. Adhesion, washability, and stability were good as shown in Table 1.

Comparative Example 1 In Example 1, 257 parts of formalin was initially added,
Two parts of completely saponified PVA (Kuraray Boval 117S, manufactured by Kuraray Co., Ltd.) having an average degree of polymerization of 1700 was added, and then 100 parts of urea was added and reacted according to the same time schedule to obtain a urea resin.

When this product was filtered through a 200-mesh wire mesh, it was found to be bubbly. After washing the pad with warm water, drying and measuring the weight, it was found to be 1.22 in 1000 f of resin. As shown in Table 1, the adhesiveness, washability, and stability are inferior to those of Example 1.

Example 2 239 parts of formalin (concentration 37%) was placed in a reaction tank, 100 parts of urea was added under stirring, the temperature was adjusted to 8 with aqueous ammonia, and the temperature was immediately heated to 90° C. in 30 minutes. When the temperature reached 60'C (temperature was 6.5), a 10% formalin solution of completely saponified PVA (Kuraray Bovar 117S manufactured by Kuraray Co., Ltd.) with a degree of polymerization of 17oO was added to 20°C.
Part was added.

10- After that, the reaction was continued at 90℃ for 90 minutes, and the temperature was 4.5. Thereafter, no blisters were observed when measured in the same manner as in Example 1. Adhesion, cleanability, and stability were good as shown in Table 1.

Comparative Example 2 In Example 2, 257 parts of formalin was initially added,
Next, 100 parts of urea was added. The rice field was adjusted and the temperature was raised in the same way. When the temperature reached 60℃, 2 times of PVA-1178 was added.
Part was added. After that, a urea resin was obtained by reacting with the same time schedule, and the amount of the resin was determined using the same method.The resin was found to be 100% (1.6yR in 1).Adhesion, cleanability, and stability are shown in Table 1. As shown, it is inferior to Example 2.

Example 3 243 parts of formalin (concentration 37 parts) was charged into a reaction tank, and while stirring the formalin, completely saponified PVA with an average degree of polymerization of 500 (Kuraray Bovar 105 manufactured by Kuraray Co., Ltd.) was charged.
) was added for 20 seconds, then 100 parts of urea was added, the temperature was adjusted to 7.5 with aqueous ammonia, and the temperature was immediately heated to 90°C in 30 minutes.
After continuing the reaction for 110 minutes, the field was 4.5 years old, and the water was white.
Since a cloudy point was observed in the Shu method, the reaction was added by controlling the temperature to 8 with a caustic soda solution. after that,
After cooling to room temperature, the specks were quantified in the same manner as in Example 1, but no specks were observed. Adhesion, washability, and stability were good as shown in Table 1.

Example 4 530 parts of formalin (concentration 37q6) was charged into a reaction tank and, under stirring, partially saponified PVA containing carboxyl groups and having a degree of polymerization of 1 soo (Kuraray Boval KL-31 manufactured by Kuraray) was charged.
Add 90 parts of 10% formalin solution of 8) and add 1 urea.
00g, 210 parts of melamine and caustic soda aqueous solution)
After adjusting the temperature to H8.5, the temperature was immediately heated to 80°C in 20 minutes, and when the reaction was continued at 80°C for 120 minutes, a white stain point was observed by the white in water iφ method, so the water was heated with an aqueous solution of caustic soda. The reaction was stopped by controlling the temperature to 8.

Thereafter, the mixture was cooled at room temperature and the amount of particles was determined in the same manner as in Example 1, but no particles were noted. Adhesion, washability, and stability were good as shown in Table 1.

Example 5 217 parts of formalin (concentration 37%) was charged into a reaction tank,
Polymerization degree 1800 containing carboxyl groups sequentially under stirring
modified partially saponified PVA (Kuraray Bovar KL manufactured by Kuraray)
45 parts of 10 formalin solution of 318), 160 parts of melamine, and 30 parts of methanol were added, the pH was adjusted to 0 with an aqueous solution of caustic soda, and the temperature was immediately raised to 80°C. 8
When the temperature reached 0°C, the temperature was adjusted to 13 with a caustic soda aqueous solution, and the reaction was continued at 80°C. After 60 minutes, the cloudiness point was reached by the water whitening method, so the temperature was adjusted to 8 with a formic acid aqueous solution and the temperature was brought to room temperature. Cooled. Thereafter, when the particles were measured in the same manner as in Example 1, no particles were observed.

Adhesion, washability, and stability were good as shown in Table 1.

13-Example 6 195 parts of formalin (concentration 37%) was charged into a reaction tank,
While stirring, 200 parts of phenol and carboxyl group-containing modified partially saponified PVA (Kuraray H
Hohar KL-318) (2) After 72 parts of a 10% formalin solution was added, 251 parts of a 25% aqueous sodium hydroxide solution was added as a catalyst, and the temperature was immediately raised to 90°C. 90℃
After continuing the reaction for 90 minutes, the mixture was cooled to room temperature to obtain a resol type phenolic resin aqueous solution. Thereafter, when the amount of pup was quantified in the same manner as in Example 1, no pup was observed. Adhesion, washability, and stability were good as shown in Table 1.

14-1) Adhesion PVAf: Since the main purpose of addition is to improve initial adhesion, the adhesion was evaluated under the plywood manufacturing conditions of all lauan materials (lauan veneer with a content of 8.5%).

(b) Initial adhesion crab veneer (0.45m thick, 25cm thick,
After applying 1 (1/30 cFn square (one side)) of adhesive to a length of 60 mm, the tensile strength of the edge was determined by cold pressing (10 kr/clA) for 20 minutes.

(b) Hot water resistant adhesive strength and repeated boiling adhesive strength veneer:
Thickness: Front and back plates 0.45wm, middle plate 1.75ff Size: 25X80 gluing amount: 201t'/30cm square (both sides) Cold pressure: 10ky/ctA 20 minutes Hot pressure: 1oky/crA 11o℃-3 After heating and pressing, the adhesive was left at 20° C. for 1 day at 65° C., and then subjected to repeated soaking in hot and cold water and boiling in accordance with JAS (Japanese Agricultural Standards), and its adhesive strength was measured.

2) Cleanability Water was poured into a container to which the adhesive had adhered, and the adhesive was stirred, and the degree of emulsification and dispersion in water was visually confirmed to determine whether the cleanability was good or bad.

3) Stability The viscosity of formalin resin alone was expressed as the number of days the resin was allowed to stand for twice the time of production.

4) Piece content After production, after leaving at room temperature for 3 days, formalin resin 1000 F was filtered through a 200-mesh wire mesh, and after washing and steaming the raw material with warm water at 45°C, it was dried, and then left at 20°C - 60°C for 1 day. The weight was measured.

[Brief explanation of the drawing]

Figure 1 shows the change in fluidity over time of a formalin solution of PVA prepared in a reference example (in the case of a 15% PVA solution and a standing temperature of 5°C) compared with that of an aqueous solution. The axis shows the ratio of the viscosity (ηt) to the initial viscosity (η0) after being left for a predetermined time, and the horizontal axis shows the standing time (hours or days).
The solid line in (1) represents the change in formalin solution, and the solid line in (1) represents the change in formalin solution.
) dotted lines indicate changes in the aqueous solution 17-. Figure 2 shows the heating dissolution curve of PVA powder in formalin and water (heating rate 1°C/min, PVA2F/solvent 100$F), where the vertical axis is the dissolution force (%) and the horizontal axis is indicates time (minutes), the solid line in (1) indicates the change in formalin, and the dotted line in (2) indicates the change in water. Patent applicant Ri Rare Co., Ltd. Patent attorney Ken Honda 18-

Claims (1)

[Claims] In a method for producing a formalin-based resin, which comprises carrying out a condensation reaction between at least one reaction component selected from the group consisting of urea, melamine, and phenols, and formalin, a solution of a polyvinyl alcohol-based resin dissolved in formalin is subjected to the condensation reaction. A method for producing a modified formalin resin, characterized in that it is used at any stage of the reaction.