JPS6058245B2 - Manufacturing method of resol type liquid phenolic resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a resol type liquid phenolic resin used as an organic or inorganic binder.

Conventionally, resol-type liquid phenolic resins are prepared by preparing phenols and formaldehyde, and are heated to a temperature of 1 to 6 at 60 to 90°C.
After reaction time, neutralize with organic or inorganic acid, water under reduced pressure,
It is generally produced in a batch manner to remove unreacted free phenol and formaldehyde to achieve desired physical properties.

However, in this method, the content of unreacted free phenol is as high as 10 to 15% by weight based on the solid content, and this free phenol is a major drawback in terms of the working environment and physical properties. For example, if a resol resin containing such free phenol is used in a white sand mold, workers may get a rash or burns due to the free phenol, and depending on the mold used, there may be gas defects or problems during pouring. There are drawbacks such as a deterioration of the working environment due to the generation of abnormal odors.
As a method for reducing the content of free phenol, 1) the reaction molar ratio of formaldehyde to phenol is increased;

There are methods such as 2) increasing the amount of catalyst added during the reaction of phenol and formaldehyde, and 3) increasing the degree of vacuum and dehydration temperature, but both of these methods lead to the following: 1) The degree of condensation increases and water miscibility decreases. There are drawbacks such as an increase in the viscosity of a predetermined solid content, and it cannot be an efficient method for reducing the free phenol content.

The present inventors have conducted intensive research aimed at reducing the content of free phenol and making the molecular weight distribution uniform, and as a result they have arrived at the present invention.

That is, in the present invention, 1 mole of phenol is reacted with 1 to 3 moles of aldehyde in the presence of a catalyst to obtain a resol type initial condensate. In order to neutralize the liquid with an organic or inorganic acid, or neutralize it when an amine catalyst is used, the resin is equipped with a rotating blade consisting of a vertical blade with a twist, and a liquid head pipe is connected to the resin extraction section. The present invention provides a method for producing a resol-type liquid phenolic resin, which is treated with a thin-film evaporator equipped with a rotor-type pump with a screw, and then diluted with water and/or an organic solvent.

According to the invention, 1 mole of phenols and 1 mole of aldehydes
~3 mol, preferably 1.2 to 2 mol, in the presence of a catalyst such as an alkali metal or alkaline earth metal hydroxide or oxide, or one or more amines at a reaction temperature of 60 to 100 mol. ℃ for a reaction time of 1 to 8 hours, and then the obtained resol-type initial condensate is treated with an organic or inorganic acid at a temperature of usually 40℃ or less when a catalyst other than an amine type is used. The initial condensate is treated, for example, by one of the following methods, without going through the steps of neutralization and removal of neutralized salts by filtration or centrifugation, if an amine catalyst is used. Then, the resulting resin is diluted to a desired solid content with water and/or an organic solvent to obtain a resol-type liquid phenolic resin with a narrow molecular weight distribution, low free phenol content, low system viscosity, and many residual methylol groups. can get. After neutralization with 1 acid, the initial condensate is directly dehydrated using a thin film evaporator to obtain dehydrated phenol.

2. The initial condensate as above is preliminarily reduced in moisture to 2 to 10% by weight under reduced pressure.
Then, dehydrate and remove phenol using a thin film evaporator.

3 Add a solvent to the initial condensate as above, and perform dehydration, phenol removal, and solvent removal using a thin film evaporator.

4. The initial condensate as above is dehydrated under reduced pressure to a water content of 2 to 1% by weight, diluted with an organic solvent, and dehydrated, phenol removed, and solvent removed using a thin film evaporator.

The methods 1) to 4) above have the following characteristics, and are appropriately selected depending on the purpose.

Method 1 has a large amount of water in the system, so the load on the thin film evaporator is large, that is, the residence time is long, and the processing temperature is 140°C.
Since a certain degree is required, foaming may become large and the molecular weight distribution of the obtained resin may become wide.

In method 2, the viscosity of the obtained initial condensate becomes high, and it is necessary to keep it warm during transfer to a feed tank and storage, and there is a problem in terms of stability.

Method 3 is better in terms of stability and removal of phenol than methods 1) and 2) above, but the load on the thin film evaporator is increased and the throughput is inferior.

Method 4 is the most effective method for reducing the stability of the initial condensate and the free phenol content depending on the solvent used.

Examples of the phenols used in the present invention include phenol, cresol, bisphenols such as bisphenol A and bisphenol, and para- or ortho-substituted alkylphenols such as paratertiary butylphenol and orthomethylphenol.
It is served as a mixture of more than one species.

Further, examples of aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, etc., and formaldehyde or paraformaldehyde is generally used.

In the present invention, the molar ratio of aldehydes/phenols varies depending on the phenols used and the intended use of the phenol resin, but the molar ratio is 1 to 3.5,
Preferably, 1.2 to 2.5 is the best, and the molar ratio of aldehydes/phenols is 0 compared to the case where the resin is produced and processed using a batch type reactor without using a thin film evaporator. It can be increased in the range of .2 to 0.5.

This is effective in reducing the amount of free phenol and
It can increase the methylol group content in the resulting resin, shorten the curing time of the resin, and increase the yield of the resin based on the charged phenol by 5 to 1% depending on the set molar ratio. can. The catalyst for the reaction between phenols and aldehydes may be any catalyst that can produce a resol type phenolic resin, such as alkali metal oxides and hydroxides, alkaline earth metal oxides and hydroxides, and these. Examples include reactants with acids, amines, etc., and one or more of these may be used.

The amount used is in the range of 0.5 to 10% by weight based on phenol, and can be appropriately selected within that range depending on the catalyst used. The reaction conditions for phenols and aldehydes when synthesizing the initial condensate vary depending on the purpose and application, but generally the reaction conditions are 60 to 100°C for 1 to 8 hours, and batch polymerization and continuous polymerization are possible. Polymerization method is adopted.

In this case, the continuous polymerization method is effective in mass production plants for a single product, but in the case of small quantities of a wide variety of products, it takes a long time to stably supply the raw material, and the number of times the inside of the kettle is washed is reduced. It is difficult to say that this is an efficient method because of the increase. In addition, when the purpose is to reduce the free phenol content and make the molecular weight distribution of the resulting resin uniform, secondary addition of catalysts, aldehydes, etc. is effective, and in this case, batch polymerization is optimal. . In the present invention, the initial condensate obtained under the above reaction conditions is usually cooled to 40°C or less when a catalyst other than an amine type catalyst is used, and the product is neutralized with an organic or inorganic acid to a pH of 7 to 8. Salts are separated by filtration or centrifugation to obtain acid-treated resin.

Note that if the salt produced is water-soluble, it remains in the resin and deteriorates the physical properties of the resin, so it is desirable to select the catalyst and neutralizing acid so as to produce a water-insoluble salt. The initial condensate in the present invention is usually an aqueous solution containing 30 to 50% by weight of water, and is treated by the following method.

1. Feed the incipient condensate to a feed tank and then from the tank to a thin film evaporator for continuous processing.

In addition, since the water content of the initial condensate is high, the processing conditions in the thin film evaporator are a jacket temperature of 140 to 160 °C and a degree of vacuum of 20.
~50T0rr1 residence time of about 30@ is suitable.
2 The obtained initial condensate was heated to 50-80°C in a reaction vessel and dehydrated under reduced pressure until the water content became 2-1% by volume, and then kept at 30-40'C. It is fed to a feed tank and processed in a thin film evaporator. The processing conditions for this evaporator are: jacket temperature 120-140, C1 vacuum degree 20-140,
50T0rr is suitable. 3 The initial condensate has a boiling point of 60-12
Dilute with an organic solvent at 0°C and process in a thin film evaporator.

At this time, foaming is observed because the organic solvent and water are mixed, but the addition of the solvent reduces the viscosity of the system and is effective in removing monomers. The processing conditions of the thin film evaporator are a jacket temperature of 120 to 140°C and a degree of vacuum of 20 to 50T0rr.
is suitable. 4 In 2) above, the water content is 2 to 1% by weight.
The dehydrated initial condensate is diluted with an organic solvent having a boiling point of 60 to 120°C and treated with a thin film evaporator.

The processing conditions of the thin film evaporator are a jacket temperature of 100 to 1
A temperature of 20° C. and a degree of reduced pressure of 20 to 8 CfVf)Rr is suitable. Examples of organic solvents with a boiling point of 60 to 120°C used in 3) and 4) above include hydrocarbons such as benzene, toluene, and xylene, alcohols such as methyl alcohol, ethanol, and isopropyl alcohol, and acetone and methyl ethyl ketone. One or more types of ketones may be mentioned. Incidentally, mixed solvents such as isopropyl alcohol/acetone, isopropyl alcohol/toluene, methanol/toluene, etc. are more preferred, and are more effective depending on their ratio. The thin-film evaporator used in the present invention is equipped with a rotary blade consisting of a vertical blade with a twist, and is equipped with a liquid head pipe and a rotor-type pump with a screw in the resin extraction section, which prevents abnormal accumulation of resin. There are few drawbacks such as scaling, and resins of any viscosity can be processed under reduced pressure, e.g.
It is possible to extract continuously without any problem at 0T0rr or less.

As such an evaporator, for example, the one shown in Fig. 1 is used. This evaporator has a motor 1 installed at the head, removes unreacted phenol, water, etc. from a vapor outlet 2, introduces the initial condensate from a raw solution inlet 3, and uses movable blades 4 rotated by the motor 1. The system is designed to treat the initial condensate, and then discharge the treated liquid resol resin from a discharge port 8 through a liquid head pipe 5, a screw 6, and a rotor section 7. The liquid resol resin treated in the thin film evaporator is led to, for example, a tank or a mixer, and diluted with water and/or an organic solvent.

The organic solvent used at this time may be the one used in the treatment with the thin film evaporator, but methanol and acetone are generally used from a practical standpoint.In addition, water and/or dilution of the organic solvent The amount is appropriately selected depending on the application. Next, an example of the manufacturing method of the present invention will be explained with reference to FIG.

First, a reaction is carried out in a reaction vessel 20 using phenol, aldehyde, a catalyst, etc., and then neutralized with an acid to obtain an initial condensate, which is then dehydrated if necessary.

This reaction vessel includes a heating and cooling jacket, a condenser,
Equipped with vacuum dehydration equipment, agitator, etc. The obtained initial condensate is stored in a stock tank 21 equipped with a stirrer and temperature adjustment equipment.

Thereafter, the initial condensate was pumped by the pump 22 at a reduced pressure of 10T.
It is possible to increase the jacket temperature to 70 to 18
The resin is supplied to a thin film evaporator 23 equipped with a rotor pump with a screw that can be controlled down to 0°C for treatment, and the resulting resin is introduced into a product tank 24 equipped with an agitator and a cooling jacket. Two tanks are required for continuous operation. Incidentally, the produced resin is diluted in this tank. The present invention will be further explained below with reference to Examples and Comparative Examples. Note that the percentages in the examples are based on weight. Example 1 In a reaction kettle, 1000 g of phenol, 1000 g of 141.5% formalin, and 25 g of 48% caustic soda (0
．． 3 mol) was added thereto, and the mixture was reacted at 70°C for 3 hours.

Next, it was cooled to 40°C or less and a sulfuric acid aqueous solution (sulfuric acid/water = 1
/2 weight ratio) and filtered to obtain an initial condensate of liquid resol resin. The properties of this condensate were as follows: viscosity (at 25° C.): 50 CPS; resin content: 45%; free phenol content (per resin content): 12.5%.

Next, the above condensate was introduced into a thin film evaporator as shown in Figure 1 and treated under the treatment conditions shown in Table 1, and the resulting resin was diluted with water to obtain a liquid resol with a resin content of approximately 60%. Resin was obtained.

Its properties are shown in Table 1. Example 2 The initial condensate obtained in Example 1 was treated in a reaction vessel at 60°C and a reduced pressure of 50T0rr to dehydrate the water content to 5%.

The properties of the obtained condensate are viscosity (25℃)
220011) PS resin content
78.3% free phenol content (per resin minute)
It was 11.5%.

Next, a liquid resol resin was obtained in the same manner as in Example 1 except that the processing conditions of the thin film evaporator were changed as shown in Table 1. Its properties are shown in Table-1. Example 3 To 1000 g of the initial condensate obtained in Example 1, 200 g of a mixed solvent of isopropyl alcohol/triol diol 70/30 (weight ratio) was added.

Its properties are viscosity (25℃) 5■P
Resin content below s 37.5%
The amount of free phenol (per resin) was 12.5%.

Next, a liquid resol resin was obtained in the same manner as in Example 1 except that the processing conditions of the thin film evaporator were changed as shown in Table 1.

Its properties are shown in Table-1.

Example 4 To 1000 g of the dehydrated initial condensate obtained in Example 2 was added 400 g of a mixed solvent of isopropyl alcohol/toluol 70/30 (weight ratio).

Its properties are viscosity (25°C) 1
25CpS resin content 56.
The amount of 5% free phenol (per resin) was 11.6%.

Next, a liquid resol resin was obtained in the same manner as in Example 2, except that the processing conditions of the thin film evaporator were changed as shown in Table 1.

Its properties are shown in Table-1.

Comparative Example 1 The same procedure as Example 1 was carried out, but the initial condensate was obtained without filtration,
Next, it was dehydrated in a reaction vessel at 50°C and a reduced pressure of 45T0rr to remove 600g of water, then cooled to 20°C, filtered, and diluted with water to a resin content of about 60% to obtain a liquid resol resin. Ta.

Its properties are shown in Table-1.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a thin film evaporator that can be used in the present invention. Moreover, FIG. 2 is a flow sheet showing an example of manufacturing according to the present invention. 1... Motor, 2... Vapor outlet, 3... Raw solution inlet, 4... Movable blade, 5
...Liquid head piping, 6...Screw, 7...Rotor section, 8...Discharge port,
9... Main shaft, 10... Distributor, 11... Jacket heat medium inlet, 12...
... Jacket heat medium outlet, 13 ... Heat retention heat medium inlet, 14 ... Heat retention heat medium outlet, 15 ...
・Screw part heat medium inlet, 16...Screw part heat medium outlet, 17...Rotor part heat medium inlet, 1
8... Rotor section heat medium outlet, 19...
Rotor part motor, 20...Reaction pot, 21.
... Stock tank, 22 ... Pump, 23
... Thin film evaporator, 24 ... Product tank,
25... Condenser.

Claims (1)

[Claims] 1 1 to 3.5 aldehydes per mole of phenols
mol in the presence of a catalyst to obtain a resol-type initial condensate, and if a catalyst other than an amine-based catalyst is used, the condensate is neutralized with an organic or inorganic acid and an amine-based catalyst is used. In such cases, without neutralization, the resin is treated in a thin-film evaporator equipped with a rotary blade consisting of vertical blades with a twist, and equipped with a liquid head pipe and a rotor pump with a screw in the resin extraction section. A method for producing a resol type liquid phenolic resin by diluting the resin with water and/or an organic solvent.