JPS6158483B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a resol type phenolic resin. It has been known to produce resol-type phenolic resins (hereinafter abbreviated as resol resins) by reacting phenols and formaldehyde with a tertiary amine having a pK _a of 10 or more as a catalyst. Although this method has a high reaction rate of phenols and formaldehyde and a fast reaction rate, the following problems arose when producing a laminate using the obtained resol resin. In other words, if the molecular weight of the resol resin obtained in this way is low, "fading" will occur due to resin outflow during lamination molding of the laminate, and if the molecular weight is high, the gel time of the varnish will be too short and the resol resin impregnated paper will The drying properties of the (resin paper) became extremely poor, and "fading" occurred due to insufficient fluidity of the resin. On the other hand, a method of producing resol resins by reacting phenols and formaldehyde under an ammonia catalyst is also widely used. According to this method, since the molecular weight of the obtained resol resin is large, when manufacturing a laminate using this,
Good moldability. Incidentally, the relationship between the molecular weight and melt viscosity of resol resin is shown in the drawing. In the figure, curve A is for a resol resin with a large molecular weight produced under a triethylamine catalyst.
Curve B is the melt viscosity curve at 135°C of a resol resin with a small molecular weight produced using the same catalyst as in curve A. Curve C is the melt viscosity curve at 135°C of a resol resin produced under an ammonia catalyst. ℃
This is the melt viscosity curve of As is clear from the figure, it can be seen that the larger the molecular weight of the resol resin, the more gradual the change in melt viscosity, and the better the moldability during the production of a laminate. Therefore, when a laminate is manufactured using a resol resin synthesized under an ammonia catalyst, moldability is good. However, in this method, the resol resin production reaction required a long time and the reaction rate of phenols and formaldehydes was low, resulting in poor production efficiency. Another problem with this reaction was that it had a strong odor. Therefore, an object of the present invention is to provide a method for producing a resol type phenolic resin that is free from such problems. The feature of this invention is that in a method for producing a resol type phenolic resin by reacting phenols and formaldehyde in the presence of an alkaline catalyst, a tertiary amine having a _pKa of 10 or more and ammonia are used together as the alkaline catalyst, both,
(Tertiary amine with pK _a of 10 or more)/(ammonia)
The purpose is to mix and use them so that the molar ratio of the two is 0.8 to 2.0. That is, by doing so, a resol resin having a large molecular weight and a long gel time can be efficiently produced with reduced odor. Next, this invention will be explained in detail. The phenols and formaldehyde used in this invention are those commonly used. And their usage ratio is (formaldehyde)/
It is preferable to select a molar ratio of (phenols) from 1.0 to 1.5. As alkaline catalysts, triethylamine,
A tertiary amine with a _pKa of 10 or more, such as trimethylamine, and ammonia are used in combination. The ratio of the two used is preferably such that the molar ratio of (tertiary amine)/(ammonia) is 0.8 to 2.0, more preferably 1.2 to 1.5.
If the molar ratio between the two is less than 0.8, the reaction rate of the raw materials will be low and the reaction will be slow, and if it exceeds 2.0, the moldability will deteriorate during the production of a laminate. Furthermore, when a tertiary amine with a pK _a of less than 10 is used, the reaction rate becomes extremely slow, which is unsatisfactory for actual resin production. There is no particular restriction on the amount of these composite catalysts used. The amount of catalyst to be used may be selected depending on the reaction time. However, usually the composite catalyst is 0.05% per mole of phenol.
~0.02Nmol is used. When producing resol resin using such a composite catalyst system, it is preferable to carry out the reaction depending on the type and amount of the catalyst, and to terminate the reaction so that the molecular weight is in the range of 280 to 380. . The gel time of the resol resin thus obtained was more than 17 minutes, and the formaldehyde reaction rate was 95 minutes.
% or more. In this case, if the gel time is 16 minutes or less, drying workability tends to be poor when used for resin paper. Furthermore, if the formaldehyde reaction rate is less than 95%, the odor tends to increase and workability tends to decrease. Using the resol resin efficiently produced in this manner, resin-impregnated paper was made by impregnating and drying a base material such as paper using a conventional method, and a plurality of sheets of paper were laminated and molded to make a laminate. In this case, the drying workability of the resin-impregnated paper was also good, and a laminate in good condition was obtained without "fading" or the like during lamination molding of the laminate. The present invention can also be applied to the production of aniline-modified resol resins for producing laminates with high impact resistance. Also in this case, the same effects as in the above case can be expected. When producing such an aniline-modified resol resin, for example, 0.015 to 0.045 mol of aniline may be added to 1 mol of phenol in addition to the above-mentioned catalyst. Next, examples will be described. Example 1 94 g (1 mol) of phenol, 65 g (1.2 mol) of 55% formalin, 0.005 mol (0.51 g) of triethylamine, and 0.0038 mol (0.26 g) of 2.5% NH ₃ were added to a 300 ml flask, and a stirring bar and thermometer were added. was attached and stirred, and after 30 minutes, it was brought to a boil, kept in that state for 85 minutes, and then cooled to obtain a resol resin. The molecular weight of this product is 296 (measured by high performance liquid chromatography), and the gel time at 135°C is:
22 minutes 18 seconds, formaldehyde reaction rate 96.0%
It was hot. When a resin paper was prepared by impregnating and drying this material into a paper base material, the drying workability was good. As a result of stacking a plurality of sheets and molding them, a good laminate was obtained. That is, the results show that the resol resin obtained in this example has good moldability and good drying workability. Example 2 The proportions and amounts of triethylamine and 25% NH ₃ catalyst used were changed as shown in the table below, and
A resol resin was prepared in the same manner as in Example 1, except that the reaction time was changed as shown in the table below, and a laminate was made using it. This laminate was also in good condition. Comparative Examples 1 and 2 The proportions and amounts of triethylamine and 25% NH ₃ catalyst used were changed as shown in the table below, and
A resol resin was prepared in the same manner as in Example 1, except that the reaction time was changed as shown in the table below, and laminates were made using the resin. In each case, problems occurred as shown in the table below. Examples 3 and 4 In Examples 1 and 2, aniline was replaced with phenol 1
A resol resin was obtained in the same manner as in Examples 1 and 2, except that the amounts shown in the table below were added based on the mole. The laminate produced using this resol resin was of good quality and had good impact resistance. Comparative Examples 3 and 4 The proportions and amounts of triethylamine and 25% NH ₃ catalyst used were changed as shown in the table below, and
Examples 3 and 4 except that the reaction time was changed as shown in the table below.
Resole resin was made in the same manner as above, and laminates were made using it. In each case, problems occurred as shown in the table below. Reference Examples 1 and 2 A resol resin was produced in the same manner as in Example 1, except that only triethylamine was used as a catalyst in the amount shown in the table below, and the reaction time was changed as shown in the table, and a laminate was made using it. Ivy. In this case, problems as shown in the following table arose. Reference Example 3 A resol resin was produced in the same manner as in Example 1, except that only 25% ammonia was used as a catalyst in the amount shown in the table below, and the reaction time was changed as shown in the table, and a laminate was made using it. Ivy. In this case, problems as shown in the following table arose. 【table】

[Brief explanation of the drawing]

The drawing is an explanatory diagram illustrating the relationship between the molecular weight and melt viscosity of a resol resin.

Claims (1)

[Claims] 1. In a method for producing a resol type phenolic resin by reacting phenols and formaldehyde in the presence of an alkaline catalyst, a tertiary amine with a pK _a of 10 or more and ammonia are used together as the alkaline catalyst, and both are combined into (pK Tertiary amine with _a of 10 or more)/(ammonia) molar ratio from 0.8 to
1. A method for producing a resol type phenolic resin, which is characterized in that it is used by mixing it so that the amount of the resin becomes 2.0.