JPH04372617A - Production of phenolic resin - Google Patents

Abstract

PURPOSE:To obtain a liquid resol phenolic resin which is useful for SMC, BMC or the like, lowly viscous and lowly volatile, has a long thickening time in the production of SMC or BMC and is excellent infiltrability into e.g. glass fibers, molding strengths and moldability. CONSTITUTION:A liquid resol phenolic resin is prepared and then dewatered to a free water content of 4.0wt.% or below, desirably at the final temperature of 80 deg.C or below.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for producing phenolic resins. More specifically, the present invention has low free moisture, low volatility, and low viscosity, which is useful for SMC, BMC, etc., and has a long thickening time during the production of SMC and BMC.
The present invention relates to a method for producing a liquid resol type phenolic resin that has good impregnability with glass fibers.

0002

[Prior Art] Phenol resin has been widely used in various fields such as electrical and electronic equipment, mechanical parts, and daily necessities.
It has also been used for C and BMC. This SMC
, Liquid resol type phenolic resin for BMC is usually
(a) Either stop the dehydration operation after synthesis and leave some water, or
Alternatively, (a) after dehydration, it is diluted with an organic solvent to lower the viscosity.

0003

[Problems to be Solved by the Invention] However, conventional liquid resol type phenol resins used for phenol SMC and BMC inevitably swell due to the generation of gas during molding due to moisture or organic solvents. If there is a large amount of free water, the viscosity of the prepared resin compound will increase quickly, and the workability when trying to use the resin will be poor, and the impregnation of the inorganic filler into glass fibers etc. will be insufficient. Ta.

[0004] Therefore, in the case of conventional phenolic resins, these factors have caused problems in that molded products swell and strength decreases. Therefore, this invention was made in view of the above-mentioned circumstances, and it solves the drawbacks of conventional liquid resol type phenolic resin, and has a low free moisture content.
A new inorganic solvent-based liquid resol type phenolic resin that has low volatility and low viscosity, has a long thickening time during SMC and BMC production, is easy to work with, and has good impregnability with glass fibers, etc. The purpose is to provide a manufacturing method.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a phenol resin which is characterized by dehydrating free water in a liquid resol type liquid phenol resin after synthesis to 4% by weight or less. A method for producing a resin is provided. That is, the present invention is characterized by controlling the free moisture in the resin by dehydration without using an organic solvent, thereby suppressing gas blistering during molding and rapid thickening of the compound. The amount is adjusted to 4% or less by dehydration.

[0006] The composition of the phenol resin in this case is not particularly limited as long as it is a liquid resol type, and as in the past, it can be synthesized using a formaldehyde source and a phenol source as raw materials, preferably using a catalyst. Any suitable material can be used. As a formaldehyde source during this synthesis, formaldehyde, paraformaldehyde, a formaldehyde aqueous solution, etc. can be used, and as a phenol source, phenol, cresol, resorcinol, etc. can be used. Usually, this synthesis reaction is carried out at a formaldehyde/phenol raw material molar ratio of 0.5 to 3.
．． 0, preferably in the range of 0.8 to 2.5,
This can be carried out using a metal organic acid salt or the like as a catalyst.

[0007] As the catalyst, appropriate catalysts such as zinc acetate, zinc propionate, ammonia, and ammonium compounds are used. This catalyst is preferably used in a proportion of about 0.1 to 1.5% based on the raw material phenol. After completion of this synthesis reaction, the free water content is dehydrated to 4% or less as described above, but this dehydration is preferably carried out under reduced pressure, and generally at a vacuum degree of about 10 to 100 torr at the final dehydration temperature. It is preferable to carry out the reaction at a temperature of 80°C or lower. If the temperature exceeds 80°C, the phenol resin becomes highly viscous, which is not preferable.

[0008] After dehydration, it is also effective to allow the product to stand for 20 to 60 minutes.
Preferably, the reaction is carried out at a temperature of about .degree. Of course, these operating conditions can be changed as appropriate depending on the raw material, catalyst, etc. used. This phenolic resin is SM
When used as a molding material for C, BMC, etc., metal oxides or phenol sulfonic acid, etc., as in the past, can be added and blended as hardening aids, along with appropriate inorganic fillers such as glass fiber. can.

When using phenolsulfonic acid,
Usually, it is used at a rate of about 0.01 to 0.5 PHR. By the production method of the present invention as described above, a resin with low free water content, low volatility, low viscosity, and slow thickening can be obtained compared to conventional phenolic resins. Examples are shown below.
The manufacturing method of the present invention will be explained in more detail.

0010

[Example] Example 1 Under the conditions of a formaldehyde/phenol raw material molar ratio of 1.8 and an amount of zinc acetate of 0.9% (based on phenol), a reaction was carried out in the same manner as in a conventionally known method, and after the reaction was completed, dehydration was carried out. Dehydration was carried out at a final temperature of 70° C. and a vacuum degree of 50 Torr. By this reaction operation, free moisture was 3.0%, Mn was 30%
A liquid resol type phenolic resin having a temperature of 0.0, Mw of 400, and a viscosity of 2000 cps/25°C was obtained.

[0011] Glass fibers and the like were blended with this resin. At this time, the viscosity of the compound, its thickening property, and moldability were evaluated. As is clear from Table 1, which shows the results in comparison with the comparative examples described below, the resin of the present invention has low viscosity and low volatility, and takes a long time to thicken during the production of SMC and the like. Therefore, it had good impregnating properties with glass fibers, and also had excellent strength and moldability.

Example 2 In the same manner as in Example 1, a liquid resol type phenol resin having a free water content of 3.0% and a viscosity of 8000 cps/25°C was produced using an ammonia catalyst. As shown in Table 1, similar to Example 1, the resin properties were good. Comparative Example 1 In the same manner as in Example 1, dehydration was carried out at a temperature of 100° C. and a degree of vacuum of 50 Torr, and the free water content was 1.5%. A resin with a viscosity of 20,000 cps/25°C was obtained.

As shown in Table 1, the properties of the obtained resin were such that the viscosity of the compound was extremely high at 100,000.
It wasn't practical. Comparative Example 2 In Example 2, dehydration was carried out at 60° C. in a vacuum of 150 Torr, free moisture was 10.0%, and the viscosity was 5000.
A resin of cps/25°C was obtained.

[0014] As shown in Table 1, the compound thickened quickly and gas blistering occurred during molding.

[0015]

[Table 1]

[0016]

[Effects of the Invention] As explained in detail above, the present invention provides a material with low viscosity and low volatility that is useful for molding, various impregnations, and especially SMC and BMC by reducing the free water content to 4.0% or less. , SMC, BMC have a long thickening time during production, good impregnation with glass fibers, etc., and the strength of molded products.
A liquid resol type phenolic resin with good moldability is obtained.

Claims (2)

[Claims] 1. A method for producing a phenol resin, which comprises dehydrating free water in a liquid resol type phenol resin after synthesis to 4% by weight or less. 2. The method for producing a phenolic resin according to claim 1, wherein the final temperature during dehydration is 80° C. or lower.