JP2001011145A - Phenolic resin for molding, its production and phenolic resin molded article obtained from the same resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a phenolic resin for molding, excellent in preservation stability, being a liquid state at 50 deg.C and excellent in molding property, especially in cast molding property, to provide a method for producing the phenolic resin for molding easily, and to obtain a phenolic resin molded article obtained from the above phenolic resin and excellent in transparency and uniformity. SOLUTION: This phenolic resin for molding has <=5 wt.% water content and 70-95 wt.% non-vaporizable content, and is a self curing phenolic resin being liquid state at 50 deg.C. The phenolic resin for molding is produced by reacting a novolak resin, phenols and aldehydes in the presence of a base catalyst and then distilling off the water content used in the reaction and produced during the reaction to <=5 wt.% water content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phenolic resin for molding, a method for producing the same, and a phenolic resin molded article obtained therefrom.

[0002]

2. Description of the Related Art Phenolic resins are widely used as well-balanced plastics in molding materials, binders, adhesives, etc., and are particularly widely used as molding materials. This phenol resin is generally divided into a resole resin and a novolak resin.

Conventionally known resol resins are prepared by charging a phenol (P) and an aldehyde (F) in the presence of a basic catalyst such as sodium hydroxide, ammonia or an organic amine, and charging them in a molar ratio (hereinafter referred to as F / P). Abbreviated as 1)
It is manufactured by reacting at about 2 or less. The resole resin thus obtained has, as a main component, a trimer of phenol having a relatively large amount of methylol group,
It is a resin with extremely high reactivity. Therefore, usually
It is stored in a cool and dark place as an aqueous solution or a methanol solution having a solid content of 60% by weight or less.
It is about four months. When molding and curing such a resol resin, water or alcohol is removed, and if necessary, the resin is cured by heating in the presence of an acid catalyst. This curing reaction rate is extremely high, and there is a problem that control of molding conditions is extremely difficult because gelation occurs within several tens of seconds at 150 ° C., for example.

On the other hand, novolak resins usually have a molar ratio of phenols (P) to formaldehydes (F) of F / F.
It is produced by reacting phenol with formalin in the presence of an acid catalyst such as oxalic acid under conditions of phenol excess such that P = 0.7-0.9. The novolak resin obtained by such a method is mainly composed of a trimer to pentamer in which phenol is mainly bonded by a methylene group, hardly contains a free methylol group,
Therefore, it does not have a self-crosslinking property by itself and shows thermoplasticity. Therefore, when a novolak resin is used as a molding material, a curing agent such as hexamethylenetetramine is usually added to the novolak resin in an amount of about 8 to 15% by weight.
A method of mixing and heating and curing at the time of molding is adopted.

[0005] A novolak resin to which hexamethylenetetramine is added generally has a large number of methylene groups as described above, and thus often has better thermosetting properties and physical properties than resol resins. However, when a novolak resin to which hexamethylenetetramine is added is used as a molding material, it is used only by mixing the solid novolak resin and the solid hexamethylenetetramine. Decomposition gas is generated, and there is a problem that voids are generated in the molded article due to the decomposed gas, and free hexamethylenetetramine which is non-uniformly dispersed remains in the molded article, thereby deteriorating the physical properties of the molded article. Was.

[0006] JP-B-63-46004 discloses a thermosetting resin or the like which can contain 20% by weight or more of water in a resin composition before curing. However, when the liquid thermosetting resin disclosed therein is used as a molding material, polymerization, a large amount of water contained in the resin cannot be completely deviated during thermosetting, and voids and cracks are easily generated, In addition, there is a problem that it is difficult to obtain a molded article having high transparency. Further, this thermosetting resin solution has a problem that polymerization tends to proceed during storage and storage stability is poor.

[0007]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide a phenolic resin for molding which has excellent storage stability, is liquid at 50 ° C., and has excellent moldability, especially moldability. An object of the present invention is to provide a method for easily producing a phenolic resin for molding, and to provide a phenolic resin molded article obtained from the phenolic resin for molding and having excellent transparency and homogeneity.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve such a problem, and as a result, have found that it is possible to solve the above problem by adopting a configuration as described below. Reached the present invention.

That is, the gist of the present invention is that first, the water content is 5% by weight or less, and the nonvolatile content is 70 to 95% by weight.
A phenolic resin for molding characterized by being a self-curable phenolic resin which is liquid at 0 ° C.
A method for producing a phenolic resin for molding, comprising reacting a novolak resin, a phenol and an aldehyde in the presence of a basic catalyst, and then distilling water present in the reaction system to a water content of 5% by weight or less. In this production method, it is particularly preferable that the amount of the phenol is 40 to 250 parts by weight and the amount of the aldehyde is 1.5 to 2.5 times the phenol relative to 100 parts by weight of the novolak resin. Thirdly, there is a phenolic resin molded article obtained from the phenolic resin for molding.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The phenolic resin for molding of the present invention has a moisture content of 5% by weight or less,
It is a self-curable phenol resin having a nonvolatile content of 70 to 95% by weight and being liquid at 50 ° C. If the moisture content of the phenolic resin for molding exceeds 5% by weight, steam is often generated due to heating during molding, bubbles remain in the molded product, and it is difficult to obtain a highly transparent phenolic resin molded product. Further, the moisture content is more preferably 3% by weight or less. The moisture percentage is determined as follows. That is, a self-hardening phenol resin liquid at 50 ° C.:methanol=1:10
(Weight ratio) of a solution prepared by Mitsubishi Chemical Corporation CA-
The moisture content was measured at two points per sample using a type 07 trace moisture analyzer (coulometric titration automatic moisture analyzer), the average of those values was determined, and the obtained value was self-cured at 50 ° C. The water content of the phenolic resin was determined.

The phenolic resin for molding of the present invention has a nonvolatile content of 70 to 95%. When the nonvolatile content is less than 70%, it takes a long time to cure the resin. On the other hand, when the resin content exceeds 95%, gelation and precipitation of the resin occur during the production, and the production is difficult. Non-volatile components are determined as follows. That is, the phenolic resin for molding of the present invention is
The value measured according to IS K6909-1995 "Liquid phenolic resin test method" was taken as the non-volatile content of the liquid self-curable phenolic resin at 50C.

In the present invention, the term "self-curing" means that the resin has a property of being three-dimensionally crosslinked by an intramolecular and / or intermolecular condensation reaction upon heating to change into an insoluble or infusible resin. The term "liquid" means a viscous liquid at 50 ° C.

The phenolic resin for molding of the present invention is obtained, for example, by reacting a novolak resin, phenols and aldehydes in the presence of a basic catalyst, and then converting the water used in the reaction and the water generated during the reaction to a water content of 5%. It is manufactured by distilling it down to less than% by weight. Novolak resin is obtained by converting phenols or modified phenols (P) and aldehydes (F) into F
/ P ≦ 1 (molar ratio), reacted under an acidic catalyst such as oxalic acid, hydrochloric acid, sulfuric acid, etc., and then heated, dehydrated and dephenolized to obtain a solid thermoplastic resin,
It has a melting point of 70 to 100 ° C. (based on the free ball method) and a chemical structure represented by the following formula (1), and these novolak resins are easily available as general commercial products.

[0014]

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The phenols include phenol and phenol derivatives. Examples of the phenol derivative include m substituted with an alkyl group having 1 to 9 carbon atoms.
-Alkylphenol, o-alkylphenol, p-
Alkyl phenols, specifically, m-cresol, p-tert-butylphenol, o-propylphenol, resorcinol, bisphenol A and their benzene nuclei or part or all of the hydrogen atoms of the alkyl group are substituted with chlorine or bromine Halogenated phenol derivatives, and one or more of these are used. These phenols are easily available as general commercial products. The addition amount of the phenol is 40 to 250 parts by weight based on 100 parts by weight of the novolak resin,
In particular, it is preferably from 60 to 150. Outside of this range, non-volatile components exceeding 70 cannot be obtained,
During the reaction, resin precipitation such as gelation may occur, and a resin solution may not be obtained. The solid or powdered novolak resin is preferably used by dissolving it in phenols.

The aldehydes include, for example, formaldehyde or paraformaldehyde, furfural and the like. The amount of the aldehyde to be added is 1.5 to 2.5, preferably 1.8 in molar ratio to the phenol.
~ 2.2. Outside this range, the reaction becomes unstable,
A uniform resin solution may not be obtained. The aldehydes are preferably used as an aqueous solution.

The basic catalyst used in the present invention includes:
Basic catalysts used in the production of ordinary resol resins are used, and examples thereof include caustic soda, potassium hydroxide, aqueous ammonia, hexamethylenetetramine, and alkylamines such as dimethylamine, diethylenetriamine, and polyethyleneimine. The amount of the basic catalyst to be added is preferably 0.01 to 0.2, more preferably 0.01 to 0.05, in terms of a molar ratio with respect to the phenol.
The basic catalyst is preferably used as an aqueous solution.

The reaction of the novolak resin, phenols and aldehydes is carried out, for example, with stirring, and the reaction temperature is 7
It is preferably performed at 0 to 90 ° C, more preferably at 75 to 80 ° C. The reaction time at this temperature is preferably 1.5 to 3 hours, particularly preferably 2 hours. After the reaction, the water used during the reaction and the water generated during the reaction are distilled off to a water content of 5% by weight or less. The method can be carried out by a usual method, and it is preferable to heat and concentrate under reduced pressure, and it is preferable that the degree of reduced pressure is 30 to 100 mmHg and the temperature is 60 to 70 ° C. The phenolic resin for molding obtained in this way has less free phenols and free aldehydes than ordinary liquid resol resins, and thus has excellent storage stability at room temperature.

Further, the phenolic resin for molding of the present invention comprises:
It can be molded by a usual method, and as a molding method,
Cast molding, transfer molding, and the like are suitably used, and cast molding is particularly preferred. For example, in order to obtain a phenolic resin molded article by casting, a phenolic resin for molding is poured into a predetermined mold, and 70 to 180 At 2 ° C for 2-5 hours,
A phenolic resin molded article is obtained.

The transparency of the phenolic resin molded article can be determined by the following method according to the haze (haze value) measuring method JIS-K7105 (1981). The phenol resin for molding is poured into a glass mold of 100 mm × 100 mm × 10 mmt, and the temperature is raised from 90 ° C. to 145 ° C. at a rate of 1 ° C./minute from 90 ° C. for 1 hour by a circulating hot air drier. Further, the composition is thermoset at 145 ° C. for 1 hour to form a phenolic resin molded product having a thickness of 3 mm. With respect to the obtained sample, the diffuse transmittance and the total light transmittance are measured at three points per sample using a Z- # 90 type color difference meter manufactured by Nippon Denshoku Industries Co., Ltd., and the average value is obtained. Haze (cloudiness value) is calculated from the following equation from the measured values of the obtained diffuse transmittance and total light transmittance. Haze (cloudiness value) = diffuse transmittance (%) / total light transmittance (%) × 100 When the haze value is 20% or less, it is determined to be transparent.
Regarding the transparency of the phenolic resin molded product, it is difficult to reduce the haze value to less than 3% even if the phenolic resin molded product is of high purity because a molecular light absorbing material such as a quinoid side reaction product is present.
When the haze value exceeds 3%, the value exceeding 3% is due to light absorption and scattering by minute contaminant impurities other than the phenol resin, fine pores, and the like. %, It appears as a large defect in the properties of the phenolic resin molded article. The haze value is particularly preferably 10% or less.

As described above, from the phenolic resin for molding of the present invention, a phenolic resin molded body having high purity and containing no pores and having high transparency can be obtained. It is excellent in properties such as chemical resistance and breaking strength, and is desired in many industrial fields including electronics, chemistry, and optics.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to embodiments. Example 1 A 2 L glass flask was charged with 200 parts by weight of novolak resin (# 600, manufactured by Mitsui Toatsu Co., Ltd., melting point: 75 to 85 ° C., 1.5% by weight of free phenol) and 300 parts by weight of phenol, and stirred. The contents were dissolved at 50-70 ° C. Then, 517.5 parts by weight of a 37% formalin aqueous solution was added, and 1.5 parts by weight of caustic soda was further added to water 1 part.
Add a solution dissolved in 5 parts by weight and stir at 70-75 ° C
For 2 hours to carry out the reaction. Next, the content was lowered to a temperature of 30 ° C. or less, and the content 6 was placed in a 1-L eggplant type flask.
100 parts by weight, using an aspirator connected to a water supply, under a reduced pressure of about 30 to 100 mmHg, at a temperature of 60 to 6
198 parts by weight of water was distilled off at 5 ° C. to obtain a liquid phenol resin for molding.

The water content and the nonvolatile content of the obtained resin liquid were measured. Table 1 shows the results. Further, the viscosity at 50 ° C. and the gel time at 145 ° C. were measured by the following method, and the obtained measurement results are shown in Table 1.
The viscosity at 50 ° C. and the gelation time at 145 ° C. were measured by the following methods according to JIS M8812-1977 “Testing method for liquid phenolic resin”. That is, the viscosity measurement uses a B-type rotational viscometer,
The test was performed at a resin temperature of 50 ° C. The gelation time was 1 hour while stirring at 150 rpm with 30 g of the resin.
The time until gelation was visually confirmed at 45 ° C. was measured.

Next, 30 g of the obtained resin liquid was weighed at 100 mm ×
Injected into a 100 mm x 10 mm flat mold, heated with a circulating hot air dryer at 90 ° C for 1 hour, from 90 ° C to 145 ° C at a rate of 1 ° C / min, and kept at 145 ° C for 1 hour. Then, thermosetting was performed to obtain a phenol resin molded body having a thickness of 3 mm. The haze value of the obtained phenolic resin molded body was measured according to the above-mentioned means, and the number of pores was determined by Nikon UF.
Using an X-DX microscope, the number of pores having a pore diameter of 10 μm or more per 1 cm ² at a magnification of 100 was counted. Table 1 shows the results. The smaller the number of pores, the more uniform the structure. Table 1 shows that the phenolic resin molded product obtained in this example is extremely excellent in both transparency and homogeneity.

Example 2 The same procedure as in Example 1 was carried out except that the water content of the resin solution was changed to 5% by weight, and the nonvolatile content, viscosity (50 ° C.), and gel time (1
45 ° C.), the haze value and the number of pores are shown in Table 1. Table 1 shows that the phenolic resin molded product obtained in this example is excellent in both transparency and homogeneity.

Example 3 A phenolic resin for molding was obtained in the same manner as in Example 1 except that the amount of the phenolic resin per 100 parts by weight of the novolak resin was changed to 42 parts by weight. Table 1 shows the results obtained by measuring the minutes, the viscosity (50 ° C.), the gel time, the haze value, and the number of pores. Table 1 shows that the phenolic resin molded product obtained in this example is excellent in both transparency and homogeneity.

Comparative Example 1 The procedure of Example 1 was repeated except that the water content was changed to 10%.
A phenol resin for molding was obtained, and the results of measuring the nonvolatile content, viscosity (50 ° C.), gel time, haze value, and number of pores in the same manner as in Example 1 are shown in Table 1. Table 1 shows that both the transparency and the homogeneity are inferior to the phenolic resin molded product obtained in the present example.

Comparative Example 2 A phenolic resin for molding was obtained in the same manner as in Example 1 except that the amount of the phenolic resin per 100 parts by weight of the novolak resin was changed to 300 parts by weight. Table 1 shows the results obtained by measuring the minutes, the viscosity (50 ° C.), the gel time, the haze value, and the number of pores.

From Table 1, it can be seen that both the transparency and the homogeneity are inferior to the molded article of the phenolic resin for molding obtained in this example.

[0030]

[Table 1]

[0031]

Since the present invention is constituted as described above, the phenolic resin for molding of the present invention has low reactivity at room temperature and excellent storage stability, and is liquid at 50 ° C., and has excellent moldability. Excellent moldability. According to the method for producing a phenolic resin for molding of the present invention, such a phenolic resin for molding can be easily obtained. Furthermore, from the phenolic resin for molding of the present invention, a highly transparent phenolic resin molded article containing no pores is obtained, which has a homogeneous structure structure, and thus has gas impermeability, chemical resistance, and breaking strength. It is excellent in such properties as, and can be suitably used in many industrial fields including electronics, chemistry, and optics.

Claims (4)

[Claims] 1. A water content of 5% by weight or less, and a nonvolatile content of 70 to 9
A phenol resin for molding, which is 5% by weight and is a self-curable phenol resin which is liquid at 50 ° C. 2. The method according to claim 1, wherein after reacting the novolak resin, phenols and aldehydes in the presence of a basic catalyst, water present in the reaction system is distilled off to a water content of 5% by weight or less. 2. A method for producing the phenolic resin for molding according to 1. 3. The method according to claim 2, wherein the amount of the phenol is 40 to 250 parts by weight based on 100 parts by weight of the novolak resin, and the amount of the aldehyde is 1.5 to 2.5 times the amount of the phenol. Production method of phenolic resin for molding. 4. A phenolic resin molded product obtained from the phenolic resin for molding according to claim 1.