JPH03243613A - Phenol-melamine cocondensation resin and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject resin having excellent heat-curability, durability, heat-resistance, etc., and suitable as a molding material, adhesive, etc., by reacting a phenol (or its precondensate) with melamine (or its precondensate) in acidic state and neutralizing or alkalizing the reaction product. CONSTITUTION:The objective resin composed of a condensate of a phenol, melamine and an aldehyde and having a cocondensation ratio of the phenol and melamine corresponding to 20-90% of the total methylene bond can be produced by reacting (A) one or more kinds of phenols (e.g. resorcinol) or precondensates of phenols and aldehydes (e.g. formaldehyde) with (B) one or more kinds of substances selected from melamine and precondensates of melamine and aldehydes (either the component A or the component B is precondensate) preferably at a molar ratio (A/B) of 0.1-10 under acidic condition (preferably pH2.0-5.0) and neutralizing or alkalizing the reaction product.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a novel thermosetting phenol-melamine cocondensation resin and a method for producing the same. More specifically, it is a co-condensed resin with an extremely high co-condensation rate, and has excellent durability, heat resistance, hydrolysis resistance, fast curing properties, and flame retardancy, making it industrially useful as molding materials, laminates, adhesives, etc. It is something.

(Prior art and problems to be solved by the invention) Conventionally,
BACKGROUND ART Phenol resin, which is a thermosetting resin formed by condensing phenol and formaldehyde, and melamine resin, which is formed by condensing melamine and formaldehyde, are widely used industrially as molding materials, laminates, and the like. Generally, phenolic resins have excellent durability, heat resistance, and hydrolysis resistance, but have the disadvantage of slow curing. Amino resins such as melamine resins have good curability, but are insufficient in durability, heat resistance, and hydrolysis resistance.

Therefore, a co-condensation resin that combines the advantages of both has been desired. However, a mere mixture of the two does not improve performance much, and the storage stability of the resin is also poor. Therefore, phenol-melamine co-condensation resins have been studied, but since the condensation reaction between melamines takes precedence over the co-condensation reaction between phenols and melamine, it has been extremely difficult to produce resins with a high co-condensation rate. Bonds between melamines are generally inferior in heat resistance and hydrolysis resistance compared to bonds between phenols and amino compounds or bonds between phenols, so co-condensation resins with a large amount of bonds between melamines have a high durability. is close to that of the amine resin, and a sufficiently improved cocondensation resin cannot be obtained.

By the way, with the rapid development of analytical technology in recent years, it has become possible to quantitatively determine the proportion of self-condensation and co-condensation in resins, but this shows that with conventional manufacturing techniques, the proportion of co-condensation is It was as low as 0-2%.

(Means for Solving the Problems) As a result of intensive studies on the relationship between the condensation reaction conditions of phenol and melamine and the co-condensation rate, the present inventors discovered that the initial condensate of phenols and aldehydes and melamine etc. were mixed under acidic conditions. It was discovered that the co-condensation rate could be easily improved by reacting with melamine, and a co-condensate of phenols and melamine with excellent curability and durability could be obtained, and based on this knowledge, the present invention was completed.

That is, the present invention provides (1) a phenol-melamine cocondensation product, which is a condensation product of phenols, melamine, and aldehydes, and is characterized in that the phenol-melamine cocondensation ratio of the total methylene bonds is 20 to 90%. Resin, (2
) (i) An initial condensate obtained by reacting phenols with one or more members from the group consisting of A, which is an initial condensate obtained by reacting phenols and aldehydes in an alkaline environment, and (ii) an initial condensate obtained by reacting melamine with melamine and aldehydes. 1 from the group consisting of B
The species or two or more species, either (i) or (ii) -
The present invention provides a novel method for producing a phenol-melamine cocondensation resin, characterized in that the initial condensate A or B is selected to contain the initial condensate A or B, reacted under acidic conditions, and then neutralized or made alkaline.

In the phenol-melamine cocondensation resin of the present invention, it is necessary that the phenol-melamine cocondensation ratio to the total methylene bonds be 20 to 90%. Cocondensation rate is 2
If it is less than 0%, the improvement in performance (durability, heat resistance, hydrolysis resistance, etc.) is insufficient, and if it is more than 90%, the reaction process becomes complicated and is economically disadvantageous.

The ratio of co-condensation can be easily determined by C-NMR analysis. Phenols and melamine have -CH, --CH, -
It is bonded via 0-CH,-, etc., but the methylene group (
-GHz-) signal is located at 30~t o
o ppm.

Among them, the signal based on cocondensation is 40.5°44.2
, around 49.2 ppm. That is 30-100p
40.5° for integrated intensity of pm 44.2, 49.2
The ratio of the total signal intensities around ppm is the cocondensation rate (%
).

In the phenol-melamine cocondensation resin of the present invention, the molar ratio of phenols to melamine (that is, the molar ratio of benzene rings to triazine rings) is preferably 10.1 to 1:10. If the amount of phenol is too low from this range, a material with poor durability will not be obtained, and if the amount of melamine is too small, a material with poor fast curing properties will be obtained.

Further, in this phenol-melamine cocondensation resin, the total molar ratio of phenol and melamine to aldehydes is preferably 2:1 to 4:1. If there is too much aldehyde, too much formalin will be released from the product, which will have an adverse effect on health, and if it is too little, the curing properties will be poor.

The phenol-melamine cocondensation resin, which is the thermosetting resin of the present invention, is prepared by the initial condensation with (i) one or more selected from the group consisting of phenols and initial condensate A, and (11) melamine. It can be efficiently obtained by a method of reacting one or more selected from the group consisting of substance B in a small amount (both containing initial condensate A or B) under acidic conditions, and then neutralizing or making it alkaline.

The phenols used in the present invention are not particularly limited, but include, for example, phenol, resorcinol, cresol, xylenol, catechol, p-tert.
These include butynol, p-phenylphenol, p-octylphenol, meditol, methylphenol, and the like.

The aldehydes used in the present invention are preferably formaldehyde, acetaldehyde, n-butyraldehyde, paraformaldehyde, trioxane, and the like.

Here, the initial condensate A is obtained by reacting aldehydes and phenols preferably at a molar ratio of 1.5 to 3.5.

If the molar ratio is less than 1.5, the physical strength of the co-condensed resin may be insufficient, and if it exceeds 3.5, there will be a large amount of unreacted aldehydes, which is undesirable. The pH of the reaction to obtain A is 8.0-13
．． 0 is desirable. As the basic catalyst, alkali metal compounds such as alkali metal hydroxides and oxides, alkaline earth metal compounds such as alkaline earth metal hydroxides and oxides, and amine compounds are used. For example, NaOH.

KOH, Ca (OH)a, Cab, Mg (OH)2
Examples include ammonia. The weight average molecular weight of the initial condensate A is preferably 2,000 or less. 2000
If it exceeds this amount, insoluble substances are likely to be produced during the reaction with melamine or melamine-based condensates, which is not preferable.

The initial condensate B preferably contains aldehydes and melamine compounds in a molar ratio of 0.5 to 2.5. It is obtained by reacting at pH 5.0 to 12.0. The weight average molecular weight of the initial condensate B is
It is desirable that it is 500 or less.

In the present invention, preferably the phenol component (i) contains the phenol initial condensate A, and the melamine component (ii) contains melamine and the initial condensate B. In this case, the ratio of the phenols in the phenol component (i) to the initial condensate A is from 1:100 to 1:1 in terms of solid weight ratio.
5 is preferable, and the ratio of melamine to initial condensate B in the melamine component (ii) is preferably l=1 to 50:1 in terms of solid content weight ratio.

The reaction molar ratio of the phenol component i) and the melamine component (ii) is the ratio of phenol to melamine, and is 0.1 to 10. The reaction must be carried out under acidic conditions, p)(L
O~5.5 is desirable, more desirably 2.0~5.
It is 0. When the pH is lower than 1.0, the cocondensation reaction is too rapid and it is difficult to control the reaction, and when it exceeds 5.5, the cocondensation reaction does not proceed sufficiently. As the acidic catalyst, mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, organic acids such as acetic acid, formic acid, phthalic acid, maleic acid, and oxalic acid, and salts thereof that can make the reaction solution acidic can be used.

The reaction between the phenol component (i) and the melamine component (ii) is preferably carried out in an aqueous solvent; % may be included.

In the reaction of phenol component (i) and melamine component (ii), it is desirable that the free aldehydes in both components be 5% by weight or less based on the entire reaction system, and if it is 5% by weight or more, the resulting cocondensation The heat resistance of the resin deteriorates. The cocondensation rate can be increased by reducing the amount of free aldehydes. In order to reduce the aldehydes, the initial condensate A and the initial condensate B may be introduced into an aldehyde-soluble solvent such as ethanol, acetone, or isopropyl alcohol, and the precipitate may be recovered.

Also. In the present invention, aldehydes may be added at any stage of the reaction.

By the method of the present invention, a reddish-brown transparent resin liquid with a viscosity of 0.1 to 5 voids and a nonvolatile content of 50 to 65% can be obtained. If necessary, distillation can be performed to increase the solid content.

The actual use of the phenol-melamine cocondensation resin of the present invention can be carried out in substantially the same manner as conventional alkaline resol resins, but since the phenol-melamine cocondensation resin has improved curing properties, the heat-pressing time can be reduced.
It doesn't matter if it's short.

Furthermore, the phenol-melamine cocondensation resin of the present invention may be used in combination with conventional urea-formaldehyde resins and melamine-formaldehyde resins, depending on required water resistance and the like. Further, if necessary, conventional additives such as fillers, extenders, preservatives, colorants, etc. can be added.

(Effects of the Invention) The phenol-melamine co-condensation resin of the present invention is a phenol-melamine co-condensation resin that is inexpensive, quick to cure, has excellent durability, hydrolysis resistance, and flame retardancy that could not be achieved with conventional technology. , each melamine resin has its own advantages. According to the method of the present invention, it is possible to efficiently produce a phenol-melamine cocondensation resin with such excellent performance and a significantly high cocondensation rate.

(Example) In order to demonstrate the present invention more specifically, an example will be shown below.
The present invention is not limited in any way by these Examples.

Example 1 In a reaction flask equipped with a reflux condenser, thermometer, stirrer, and dropping funnel, 200 g of phenol and 37% formalin 51
7 g of Ca(OH)a and 11.8 g of Ca(OH)a were charged and dissolved while cooling, and then reacted at 50° C. for 8 hours. 35
After cooling to ℃, 30 g of 50% sulfuric acid was added dropwise from the dropping funnel. At this time, the pH was 3.5. Next, 127 g of melamine was added to this reaction solution and reacted at 85° C. for 60 minutes. The mixture was cooled to 35° C., 10 g of NaOH was added, and the mixture was further cooled. The obtained resin liquid was reddish-brown and transparent, and had a viscosity of 50 cp.
The non-volatile content was 50%. The co-condensation rate was 35%.

Example 2 In a reaction flask equipped with a reflux condenser, thermometer, stirrer, and addition funnel, 200 g of phenol, 37% formalin 51
7g of NaOH and 42.4g of NaOH were charged and dissolved while cooling, and then reacted at 50°C for 8 hours. After cooling to 35° C., 125 g of 50% sulfuric acid was added dropwise from the dropping funnel.

At this time, the pH was 3.5. Next, 127 g of melamine was added to this reaction solution and reacted at 85° C. for 60 minutes. 3 more
100 g of 7% formalin was added and reacted for 60 minutes. Next, the mixture was cooled to 35° C., 20 g of NaOH was added, and the mixture was further cooled. The resulting resin liquid was reddish-brown and transparent, had a viscosity of 50 cp, and had a nonvolatile content of 50%. The co-condensation rate was 45%.

Reference Example: In a reaction flask equipped with a reflux condenser, thermometer, stirrer, and dropping funnel, 248 g of melamine and 162 g of 37% formalin were added.
After charging 42.4 g of NaOH and dissolving it while cooling, the mixture was reacted at 570°C for 1 hour and then cooled to 35°C. This is designated as initial condensate B-1.

Example 3 In a reaction flask equipped with a reflux condenser, thermometer, stirrer, and addition funnel, 200 g of phenol, 37% formalin 51
7 g and 42.2 g of NaOH were charged and dissolved while cooling, and then reacted at 50° C. for 8 hours. After cooling to 35° C., 125 g of 50% sulfuric acid was added dropwise from the dropping funnel. At this time, the pH was 3.5. Next, 127 g of initial condensate B-1 was added to this reaction solution, and the mixture was reacted at 85° C. for 60 minutes.

The mixture was cooled to 35° C., 20 g of NaOH was added, and the mixture was further cooled. The resulting resin liquid was reddish-brown and transparent, had a viscosity of 50 cp, and had a nonvolatile content of 50%. The co-condensation rate was 30%.

Example 4 200 g of phenol and 37% formalin 5 in a square flask
After preparing and dissolving 17 g and 842.4 g of NaO, 20
The reaction was carried out at ℃ for 120 hours.

The resin solution was poured into 5 times the volume of isopropyl alcohol, and the precipitate was washed and filtered. This precipitate was dissolved in 500 g of water and placed in a reaction flask equipped with a reflux condenser, thermometer, stirrer, and dropping funnel, and 200 g of 40% acetic acid was added dropwise from the dropping funnel. At this time, the pH was 3.5. Then, 127 g of initial condensate B-1 was added and reacted at 85° C. for 90 minutes. The mixture was cooled to 35° C., 20 g of NaOH was added, and the mixture was further cooled. The resulting resin liquid was reddish-brown and transparent, with a viscosity of 50 cp,
The non-volatile content was 50%. The cocondensation rate was 65%.

Comparative Example 1 (Manufacture of phenolic resin) In a reaction flask equipped with a reflux condenser, a thermometer, a stirrer, and a dropping funnel, 200 g of phenol and 37% formalin: 15
17g of NaOH and 42.4g of NaOH were charged and dissolved while cooling, and then reacted at 80°C for 2 hours, and then cooled. The resulting resin liquid was reddish-brown and transparent, had a viscosity of 50 cp, and had a nonvolatile content of 50%.

Comparative Example 2 (Production of phenol melamine resin) In a reaction flask equipped with a reflux condenser, thermometer, stirrer, and dropping funnel, 200 g of phenol, 517 g of 37% formalin, and Na
After preparing 42.4g of OH and dissolving it while cooling,
The reaction was carried out at 0°C for 8 hours. Reaction solution (pH 10) at 45℃
After cooling to
The reaction mixture was allowed to react for several minutes and then cooled. The resulting resin liquid was reddish-brown and transparent.
The viscosity was 50 cp and the nonvolatile content was 50%. Cocondensation rate is 1%
was.

[Manufacture of Particle Board] The resin liquid synthesized as described above was applied to a chip according to a conventional method to manufacture a particle board, and a performance test was conducted. The results are shown in Table 1 below.

Plate thickness: 12mm Density + 0. 7g/cm2 chip moisture content: 2 surface layers 12%, core layer 3% Resin spraying rate: surface layer 12%, core layer 3% Heat pressure temperature: 150℃, 170℃ Heat pressure time: 3 minutes, 5 minutes Compression pressure: 28 kgf/cm” wood chips:
Table 1 (Note) Physical properties of lauan chips were conducted in accordance with JIS A-5908. Wet bending strength is B test.

As is clear from the results in Table 1, when the phenol-melamine cocondensation resin of the present invention is used as an adhesive for particle board, it exhibits excellent port properties even when hot-pressed at low temperatures and for a short time compared to conventional sealants. I can do it.

Claims (7)

[Claims] (1) A phenol-melamine co-condensation resin, which is a condensation product of phenols, melamine, and aldehydes, and is characterized in that the phenol-melamine co-condensation ratio of all methylene bonds is 20 to 90%. (2) The phenol is one or more selected from the group consisting of phenol, resorcinol, cresol, xylenol, catechol, p-tert-butylphenol, p-phenylphenol, p-octylphenol, meditol, and methylphenol. The phenol-melamine cocondensation resin according to claim (1). (3) The aldehyde is one or two selected from the group consisting of formaldehyde, acetaldehyde, n-butyraldehyde, paraformaldehyde, and trioxane.
The phenol-melamine co-condensation resin according to claim 1, wherein the phenol-melamine co-condensation resin is of at least one species. (4) Molar ratio of phenols and melamine is 10:1-1
The phenol-melamine cocondensation resin according to claim (1), characterized in that: :10. (5) Claim characterized in that the total molar ratio of aldehydes, phenol, and melamine is 2:1 to 4:1 (
1) The phenol-melamine cocondensation resin described above. (6) (i) An initial condensate obtained by reacting phenols, one or more of the group consisting of A, which is an initial condensate obtained by reacting phenols and aldehydes in alkaline conditions, and (ii) melamine, and an initial condensate obtained by reacting melamine with aldehydes. One or more selected from the group consisting of condensates B such that either (i) or (ii) contains the initial condensate A or B, reacted under acidic conditions, and then neutralized. Alternatively, a method for producing a novel phenol-melamine cocondensation resin characterized by making it alkaline. (7) The method for producing a phenol-melamine cocondensation resin according to claim (6), characterized in that aldehydes are added at any stage of the reaction.