JPS6026491B2 - Production method of solid phenol-melamine cocondensation resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a self-curing solid phenol-melamine cocondensation resin.

Both melamine resin and phenolic resin are resins that have been known for a long time and have been used in practice, but while melamine resin has excellent tracking resistance, arc resistance, flame resistance, etc., it is too hard to cure. Therefore, there are problems with poor impact resistance, crack resistance, machinability, moldability, etc.Also, phenolic resins have excellent heat resistance, machinability, etc., but have poor tracking resistance and arc resistance. sex,
The problem was that it had poor weather resistance. Therefore, various phenol-melamine cocondensation resins have been developed in order to take advantage of the advantages of both of these resins and improve their disadvantages. The following method can be cited as a typical method for producing the phenol/melamine cocondensation resin that has been developed in the past.

'1} A method of co-condensing a mixture of melamine, phenol and formaldehyde in the presence of a basic catalyst.

■ A method in which phenol and formaldehyde are condensed in the presence of a basic catalyst to obtain a self-curing phenol resin initial condensate, and then melamine is added to this to conduct a condensation reaction.

Since the resins obtained by these methods are all liquid resins, they are used as fillers (base materials) when used as molding materials.
A wet construction method will be used, which requires impregnation, drying, and pulverization.

Therefore, there is a drawback that the manufacturing method is complicated and productivity is low. On the other hand, a dry method is also known in which a solid phenol resin and a solid melamine resin are mixed and then a filler is added and mixed, but the resin mixture obtained by this method has poor moldability and There is a drawback that the crack resistance of the molded product is insufficient.

In addition, phenol and formaldehyde are first reacted in the presence of an acidic catalyst to create a nopolac-type initial condensate, and a basic catalyst is added to this to methylolize it to form a self-curing novolak resin, and then melamine is added to perform co-condensation. A method for producing a self-curing phenol-melamine cocondensation resin is also known, but it has the disadvantage of poor tracking resistance and arc resistance.

The object of the present invention is to provide a phenol-melamine co-condensed resin that does not have the drawbacks of the conventional phenol-melamine co-condensed resins and mixtures of phenol resins and melamine resins as described above. The present invention
Melamine and formaldehyde in the presence of a basic catalyst
: Liquid melamine resin initial condensate obtained by reacting at a molar ratio of 1.6 to 3.0, and enol and formaldehyde in the presence of an acidic catalyst at a ratio of 1:0.1 to 0.45.
The novolak type phenolic resin initial condensate Tsukuda obtained by reacting at a molar ratio of
This method consists of a method for producing a self-curing solid phenol/melamine cocondensation resin, which is characterized by subjecting it to a cocondensation reaction under conditions of 7 to 10, and then distilling water off under reduced pressure.

Next, the configuration of the present invention will be explained in detail.

The present invention first involves preparing an initial condensate of melamine and formaldehyde (1) and a novolak-type initial condensate of phenol and formaldehyde [B-] separately, subjecting both to a co-condensation reaction, and then subjecting them to a dehydration treatment. It is characterized by doing.

The present invention furthermore determined the relative ratio of the amounts of raw materials used in the preparation of each initial condensate, and specified the mixing ratio of each initial condensate used as a raw material for the co-condensation reaction and the reaction conditions for the co-condensation reaction. Points are also a feature. In the present invention, the initial condensate of melamine and formaldehyde is prepared by mixing melamine and formaldehyde in the presence of a basic catalyst at a molar ratio of 1:1.5 to 3.0 (melamine:formaldehyde), preferably 1:1.6. Molar ratio of ~2.2 (same)
Prepared by reacting at

The basic catalyst used in this reaction can be arbitrarily selected from the basic catalysts commonly used in the production of melamine resins; examples of such catalysts include sodium hydroxide, potassium hydroxide, and carbonate. Sodium can be mentioned. This reaction is carried out, for example, by adding a basic catalyst to a mixed solution of melamine and formaldehyde within a predetermined molar ratio range, adjusting the pH of the mixed solution to 8 to 10, and then flooding the solution to remove melamine. The melamine is dissolved in the mixture, and from the time of dissolution of the melamine, about 50%
The incipient condensation produced when less than 1.5 moles of formaldehyde per mole of melamine is used in the preparation of the incipient condensate stream by maintaining the solution at a temperature in the range of 70 qC to reflux for ~120 minutes. Since unreacted melamine remains in the product, the next cocondensation reaction tends to be non-uniform, which is undesirable.

On the other hand, 3.0% formaldehyde was added to 1 mole of melamine.
If the amount is more than 0 mole, the product will contain a large amount of methylol groups and dimethylene phenol groups, making gelation more likely to occur. In this case, the amount of gases such as condensed water and formaldehyde generated increases, which is undesirable because it causes deterioration of the working environment, deterioration of crack resistance, mechanical strength, electrical insulation, and poor appearance of the molded product. In the present invention, a liquid initial condensate of melamine and formaldehyde obtained under the above conditions is used as one of the raw materials.

The initial condensate of phenol and formaldehyde ■ is a mixture of 1:1 of phenol and formaldehyde in the presence of an acidic catalyst.
It is prepared by reacting at a molar ratio of phenol:formaldehyde of 0.1 to 0.45, preferably 1:0.2 to 0.40, forming a novolac type. There is.

The acidic catalyst used in this reaction can be arbitrarily selected from acidic catalysts commonly used in the production of novolac type phenolic resins, and examples of such catalysts include hydrochloric acid and oxalic acid. This reaction is carried out by heating a mixed solution of fer/form, formaldehyde, and an acidic catalyst in a predetermined molar ratio to a temperature in the range of 8°C to reflux temperature for 10 to 120 minutes, preferably 30 to 90°C.
A product with a formaldehyde conversion of 99% or more is obtained. The thus obtained initial condensate of phenol and formaldehyde 'B is in liquid form and has an average molecular weight of about 140 to 250. When preparing Initial Condensate B}, if the amount of formaldehyde is more than 0.45 mol per 1 mol of phenol, the viscosity of the reaction solution increases as the reaction progresses, and water tends to separate, resulting in a heterogeneous system. It is undesirable because it makes your sex worse.

On the other hand, formaldehyde is 0 per mole of phenol.
．． If the amount is less than 1 mole, a large amount of unreacted phenol will remain, which will adversely affect the curability, crack resistance, and electrical insulation properties of the resin obtained after the next cocondensation reaction, which is not preferable. Liquid melamine resin initial condensate■ and/borac type liquid phenol resin initial condensate [B}10
They are mixed at a ratio of 0:6 to 56 (weight ratio of A:B) and subjected to a cocondensation reaction.

In the cocondensation reaction, the pH of the solution is adjusted to 7 to 10 by adding a basic compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, etc. to this mixed solution, and then the pH of the solution is adjusted to 7 to 10, for example, at a temperature ranging from 60°C to reflux temperature. This is done by maintaining this solution at a temperature within 9 minutes, preferably within 6 hours. Water is then removed from the cocondensation reaction solution thus obtained at 60 to 115° C. under reduced pressure to obtain a solid product, that is, a self-curing solid phenol-melamine cocondensation resin. Note that it is also possible to carry out the above-mentioned cocondensation reaction and dehydration treatment in one operation, that is, to carry out the cocondensation reaction under reduced pressure. When carrying out the co-condensation reaction of the present invention, if the phenol resin initial condensate [B} is less than 6 parts by weight relative to 10 parts by weight of the melamine resin initial condensate, the resulting resin will be similar to conventional melamine resins. This results in a resin with poor impact resistance and crack resistance.

On the other hand, when the phenolic resin initial condensate [B} is increased to more than 5 parts by weight per 10 parts by weight of the melamine resin initial condensate, a large amount of unreacted phenol remains in the resin after the co-condensation reaction. Therefore, such resins are not preferred in practice because they have poor tracking resistance, arc resistance, and curing properties. The phenolic resin initial condensate 'B)' obtained as described above exhibits acidity with a pH of 0.8 to 1.2, and when the co-condensation reaction with the melamine resin initial condensate 'B) is carried out in the same state. The pH of the cocondensation reaction system is 5 to 6.8.
The mixture becomes acidic, and the condensation reaction between the methylolmelamines in the melamine resin occurs preferentially rather than the desired cocondensation reaction, and the reaction solution also tends to gel. Therefore, it is necessary to manage the feed to be maintained at 7 to 10 during the co-condensation reaction and/or vacuum dehydration operation. If the cocondensation reaction is carried out at a pH lower than 7 or higher than PHIO, gelation will occur during the reaction, making it impossible to obtain the desired resin. In addition, in order to control the pH of the reaction solution for the cocondensation reaction to 7 to 10,
For example, the pH of the phenol resin initial condensate [B) is adjusted to be within the above range immediately after the production of the condensate, or
Alternatively, after mixing with melamine resin initial condensate, the pH
It is possible to adopt a method such as adjusting the When the method of the present invention is used to obtain a phenol-melamine cocondensation resin, it is characterized by high workability because the reactions at each stage can be easily controlled and gelation and heterogeneous reactions are less likely to occur. .

On the other hand, since the phenol-melamine cocondensation resin obtained by the present invention is self-curing and can be taken out as a solid,
After directly kneading with a filler, molding agent, etc., a molded article with excellent tracking resistance, arc resistance, crack resistance, heat resistance, and moldability can be manufactured using a highly productive dry method.

Next, the present invention will be explained in more detail with reference to Examples.

Note that "parts" in the examples mean "parts by weight." [Example 1] '11 Preparation of novolak-type phenolic resin initial condensate Add 1 oxalic acid to a mixture of 32.9 moles (3.5 moles) of phenol and 87.5 moles (1.05 moles) of 36% formalin.
．． The reaction mixture was reacted for 60 minutes under reflux, cooled at 30:00, and a 10% aqueous sodium hydroxide solution was added to adjust the pH of the reaction mixture to 8.8 to prepare a novolac type phenol resin initial condensate. Obtained 425.1 evening.

■ Preparation of melamine resin initial condensate 36% formalin 300 g (3.6 mol) and water 20.2
A 10% aqueous sodium hydroxide solution was added to the mixture to adjust the pH of the mixture to 9.0, and melamine 252 (2.0 mol) was added thereto.

By flooding this mixture with an oil solution,
Gradually raise the temperature to C over 1 hour, then 90q
Melamine resin initial condensate 5 by keeping at o for 10 minutes
I got 73 nights. (3) Production of solid phenol-melamine co-condensate resin 81 parts of the phenol resin initial condensate obtained in {1) above was added to the total amount of the melamine resin initial condensate prepared from the above [small sieve], and 80 to 85 q0 de1
The cocondensation reaction was carried out for 8 minutes.

Next, dehydration was carried out by maintaining the temperature of the reaction mixture at 60 to 110 qo and simultaneously reducing the pressure of the reaction mixture system to 480 to 160 Hg. When the amount of dehydration reached 224, the dehydration operation was stopped and the solid resin produced was taken out. The solid resin obtained had a softening point of 85° C. and a gelation time of 120 seconds. This resin 7 Akito and pulp 1
A molding material containing 7 parts of asbestos and 3 parts of asbestos was blended into a bran mixture and pulverized to obtain a molding material.

[Example 2] A 10% aqueous sodium hydroxide solution was added to a mixture of 300 moles (3.6 moles) of 36% formalin and 20.2 moles of water to adjust the pH of the mixture to 9.0, and to this was added 252 moles of melamine. (2.0 mol) was added.

By heating this mixture in oil grade, it becomes 90q from room temperature.
The temperature was gradually increased over 1 hour until the temperature reached 90q.
Melamine resin initial condensate 5 by keeping at 0 for 10 minutes
I got 73 nights. To the total amount of the melamine resin initial condensate prepared by the above procedure, 106.8 kg of the phenolic resin initial condensate prepared in [1} of Example 1 was added, and 80 to 85
The cocondensation reaction was carried out for 15 minutes at midnight. Next, dehydration was carried out by maintaining the temperature of the reaction mixture at 60-105°C and simultaneously reducing the pressure of the reaction mixture system to 480-160° Hg. When the amount of dehydration reached 216, the dehydration operation was stopped and the solid resin produced was taken out. The obtained solid resin had a softening point of 870 and a gelation time of 24
It was sand. Seven parts of this resin, 17 parts of pulp, and three parts of asbestos were blended, kneaded, and ground to obtain a molding material.

[Comparative Example 1] A release agent was mixed with 4 parts of melamine resin (dimer type methylol melamine resin), 21 parts of novolac type phenol resin (number average molecular weight 580), 17 parts of pulp, and 30 parts of asbestos, and the mixture was kneaded and crushed. A molding material was obtained.

[Comparative Example 2] 4 cc of 3.65% hydrochloric acid was added to a mixed solution of phenol 188 (2.0 mol) and 36% formalin 166.7 (2.0 mol), and the mixture was reacted at 80 qo for 70 minutes to form a novolac type. Create an initial condensate, then add 36% formalin 333
．． 3 (4.0 mol), 50% triethanolamine 4
After adjusting the pH to 7.8 by adding 4 hours of water, the mixture was reacted at 80° C. for 60 minutes to obtain a resol.

Melamine 252 (2.0 mol) and 36% melamine were added to this resin solution.
Formalin 83.3 evening (1.

0 mol) and adjusted the pH to 7 with 50% triethanolamine.
．． The cocondensation reaction was carried out at 8000 for 60 minutes.

Next, dehydration was carried out under reduced pressure in the same manner as in Examples 1 and 2, and when the amount of dehydration reached 400, the dehydration operation was stopped and the resin was taken out. The obtained solid resin had a softening point of 80 oo and a gelation time of 6 hours. 7 parts of this resin, 17 parts of pulp, and 3 asbestos mold release agents were blended, kneaded, and pulverized to obtain a molding material.

In order to compare the performance of the molding materials of Examples 1 and 2 and Comparative Examples 1 and 2, each molding material was molded and various tests were conducted.

Test items and test results are shown in Table 1. Table 1 Note that the test pieces used in the tests were manufactured by compression molding for the tracking resistance and crack resistance tests, and by transfer molding for the other tests.

Crack resistance was measured using a test piece with a wall thickness of 4 and a 42-year-old willow with a height of 1.
One cycle was measured by heating for 5 minutes and then cooling in cold water for 5 minutes.

Claims (1)

[Claims] 1 Liquid melamine resin initial condensate (A) obtained by reacting melamine and formaldehyde at a molar ratio of 1:1.5 to 3.0 in the presence of a basic catalyst, and phenol in the presence of an acidic catalyst. and formaldehyde 1:0.1
A novolak type liquid phenolic resin initial condensate (B) obtained by reacting at a molar ratio of ~0.45,
It is characterized by mixing 6 to 56 parts by weight of (B) to 100 parts by weight of (A), subjecting this mixture to a co-condensation reaction under conditions of pH 7 to 10, and then distilling water off under reduced pressure. A method for producing a self-curing solid phenol-melamine cocondensation resin.