JPS5817211B2 - Method for producing liquid phenolic resin composition for organic self-hardening molds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an organic self-hardening phenolic resin composition for molds.

This type of resin composition is prepared by mixing phenol, formaldehyde, and a catalyst, heating the mixture, causing condensation polymerization, and then heating the mixture under reduced pressure to remove water, unreacted phenol, unreacted formaldehyde, and other volatile components. obtained by removing.

By the way, regarding the content of free phenol, the one made by eight companies in West Germany is 11. '4wt.%, and that of company D in the US is 11.7wt.

%, which is quite high.

If there is too much of this, a terrible odor will be emitted during paper mixing, mold making, and pouring, and workers may develop rashes on some parts of their bodies, significantly deteriorating the working environment.

In addition, free formaldehyde was 0.69 wt.% from eight companies in West Germany, and Q.78 wt. from eight companies in the United States.
This is on the order of t,%, which is also an extremely high rate for experts.

Its presence in large quantities also gives off a strong pungent odor,
Deteriorate the working environment.

The viscosity is on the order of 90-135 Cp/30°C.

The lower this value is, the better the molding process will be, so conventionally, if you lower this value by mixing in a fairly large amount of methanol or a similar organic solvent, the flash point will drop and, for example, The temperature is approximately 35 to 58°C, making it highly flammable and requiring special storage equipment.

Furthermore, when the amount of free phenol increases, the internal hardening ability deteriorates, which is extremely disadvantageous, especially in molds for large castings.

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide a mold with good internal hardening ability and to significantly improve the working environment even with large molds.
Moreover, it provides a method for producing the above-mentioned type of liquid phenolic resin composition (hereinafter referred to as phenol resin), which eliminates the risk of ignition and substantially eliminates the need for addition of an organic solvent when storing the liquid composition. The gist of the present invention to achieve the object is as set forth in the claims set forth in the preamble.

In the method of the present invention, the phenol formaldehyde resin concentration (hereinafter referred to as resin concentration) is 50 to 80 wt%.
A resin composition was obtained, the free phenol content of which was 5w.
t, % or less, free formaldehyde content is Q, 5wt, %
Hereinafter, it can preferably be 0.2wt,% or less.

Moreover, when used, the organic solvent can be substantially freed.

The most important thing is to have scales that are not flammable.

This is even more surprising.

The water content is adjusted so that the resin concentration is 5 to 45 wt.%.

For this purpose, an appropriate amount of water may be added after the dehydration step.

In the present invention, water is artificially added immediately before the dehydration step, contrary to conventional wisdom.

The amount of water to be added is such that the resin concentration is 5 to 45 wt.%.If the resin concentration is over 45 wt.%, the free phenol content and free formaldehyde content will not be sufficiently reduced.
If it is less than wt.%, the amount of heat required for dehydration becomes large and is uneconomical.

The reason for adding water is to carry out the dehydration process in a long tube under flushing with a large amount of generated water vapor, and to prevent excessive condensation products from forming and depositing on the inner wall surface of the tube.

Thereby, the heating temperature can be increased compared to the conventional method.

The composition of the present invention will be described in detail below, with particular reference to several production examples. In the examples, the resin concentration refers to the resin concentration in an aluminum foil container and the temperature at 180°C.
After heating for 1 hour on a hot plate at ±1°C, it was left to cool to room temperature, and the residual content is shown in wt and %, and free phenol is HC
C. Free formaldehyde is determined by the hydrochloric acid hydroxyamine method;
Moisture was measured using the Karl Fischer method, viscosity was measured using a B-type viscometer, and flash point was measured using a tag method.

Example 1 550 kg of phenol, 568 k of 38% formalin
g, NaOH as catalyst 1.65 kg, water 6.6 k
g 23.85 kg of Ca(OH) as a catalyst, 15.0 kg of water.
A batch operation was carried out using a mixture of 4 kg.

In the reaction pot, the rice temperature is raised to 70℃ within 1 hour from 30℃.
The temperature was maintained for 6.5 hours and then cooled again to 30° C. within 1 hour.

After cooling, 22.7 kg of pappaparatoluenesulfonic acid and 34.1 ky of water were added as a neutralizing agent to the above amount of raw materials.

The resin concentration of the polycondensate was 49 wt.%, and the pH was 4 to 5.

145 kg of water was added to this to make a stock solution with a resin concentration of 43.7 wt%.

The total amount charged was 1202.3 to 9.

Next, the dehydration process is carried out in continuous operation, and the flow rate], OO
kg/h, and the temperature inside the tube was 120-130°C.

The pressure of the heated steam was 2.5 to 3.4 kg/cri.

Processing time was 13.5 hours.

The resin concentration of 4,700 kg of the distillate thus obtained was 80 wt.%.

Moreover, the viscosity was 550-100 OCT) and 730°C.

Evaporator pressure was 100-120 imHg.

By adjusting this by adding some water, a product composition having the following properties was obtained.

Resin concentration・・・・・・・・・・・・・・・・・・・・・
・・・・・・7.2wt,% viscosity・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・75
cp / 30°C free phenol...
......5 wt, % free formaldehyde...0.2 wt, % moisture...
・・・・・・・・・・・・・・・・・・・・・・・・
...17.7wt,% flash point...
・・・・・・As a comparative example, the above stock solution was dehydrated by a batch method without igniting, and the degree of vacuum was 60.
The dehydration temperature could only be raised to 80°C at mrrtHg.

The reason for this is that the viscosity increases due to polymerization.

In addition, the properties of the product in that case were as follows.

Resin concentration・・・・・・・・・・・・・・・・・・・・・
・・・・・・72wt,% viscosity・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・155
cp/30°C free phenol...
......13wt, % free formaldehyde...
・・・・・・1% moisture・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・9wt,%
flash point······················
...It does not catch fire, that is, even if water is added in the same way, the free phenol content and free formaldehyde content are much higher, and in that respect it is no different from conventional products.

It is clear that the thinning was not simply due to the effect of diluting it with water.

In addition, free phenol was added to 5 wt% by the same method as in the comparative example.
In order to achieve the following, dehydration was carried out by raising the temperature to 95°C at a reduced pressure of 20 mmHg.

At this time, the resin concentration was 87wt% and the viscosity was 75000c.
p/30°C.

By adding methanol to this, a product composition with the following properties was obtained.

Resin concentration 70wt, % viscosity
120, cp/30°C Free Phenol 5.0wt, % Free Formaldehyde
Q, 2wt, % moisture 4.2w
t, % Flash point 37℃ So, 5wt of free phenol by patch method.

% or less, it is necessary to use a large amount of methanol in order to lower the resin viscosity, which lowers the flash point.

In producing a resin composition by the method of the present invention, in the dehydration step, for example, in a pilot plant, the pipe has an inner diameter D = 12 mm, a length L - 22 m, and L/D
was 1833.

In the plant under actual operation, the inner diameter]) = 35.7 mm, the length L'' = 39.6 m, and L/D = 1109.

If L/D is set to at least 1000, preferably about 2500 with a maximum value of 1500, a kind of flushing phenomenon will be introduced in the dehydration process, and even if the temperature is raised to a certain extent, excessive condensation polymerization will be prevented. I believe there is.

Example 2 Phenol 5501<g, 38% formalin 568 kg
, 1.65 kg of NaOH, 6.6 kg of water, Ca(OH
) and 15.4 kg of water to carry out the condensation polymerization reaction.

The temperature conditions for heating and cooling were the same as in Production Example 1.

After the reaction, add 22.7 kg of paratoluenesulfonic acid to 3 ml of water.
4.1 kg of the solution was added under stirring to neutralize it.

The pH was adjusted to 4-5. The resin concentration in this case is approximately 49
wt,%.

Add 325ky of water to the above stock solution to make the resin concentration 3.
8.6wt,% bound.

The resin content was 1527ky.

Next, in order to perform a dehydration operation, a stock solution having a temperature of 30° C. was used, and the stock solution flow rate was adjusted to 100 kg/h.

The temperature inside the tube is 110-120℃, the steam pressure is 2-3
kg,/cr7tz evaporator pressure is 100-120mmH
It was g.

The operation was carried out continuously. The resin discharge temperature in the case of
The temperature was 5 to 40°C, and the amount of resin (yield) was 680 kg.

In this case, the composition is: Resin concentration・・・・・・・・・・・・・・・・・・・・・
... 81wt, % free phenol...
...... 6.7wt, % free formaldehyde... Q, 2wt, % residual moisture...
・・・・・・・・・・・・・・・・・・ 7. Owt,%
Total of the above・・・・・・・・・・・・・・・・・・・・・
・ 94.9wt, % viscosity・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・ 650cp/3
It was 0°C.

In order to commercialize this into a desired product, 422 kg of water was added to make the resin concentration 50 wt%.

The composition of this product is resin concentration...
・・・・・・・・・・・・ 50wt, % free phenol 4.1wt, % free formaldehyde 0.12wt, % moisture・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・ 42.6wt, total of % or more・・・・・・
・・・・・・・・・・・・・・・ 96.82wt,%
Viscosity 2・・・・・・・・・・・・・・・・・・・・・
It was 35 cp/30°C.

Example 3 The raw material ratios were selected as in Example 2, and the condensation reaction conditions and stock solution were adjusted in the same manner as in the previous example.
9 was added to make the resin concentration 21wt%, and the resin amount was 2.
The ratio was set to 806ky.

Next, the above stock solution was dehydrated in the same manner as in the previous example.

The conditions are stock solution temperature...3
0°C stock solution flow rate・・・・・・・・・・・・100
kg/h Tube temperature・・・・・・・・・・・・・・・
120-130℃ (steam pressure is 2.5-3.5 kg
/crrt) Evaporator pressure・・・・・・・・・・・・1
When continuous operation was performed at a pressure of 00 to 1.20 mmHg, discharged material was obtained at a rate of resin discharge temperature of 30 to 35°C and resin amount (yield) of 651 kg.

The characteristics of the discharged resin composition obtained in this way are resin concentration...
...82wt, % free phenol...
...3.6wt, % free formaldehyde...
...0.19wt, % residual moisture...
・・・・・・・・・・・・7.5wt, % viscosity・
・・・・・・・・・・・・・・・・・・・・・・・・
...It was 860cp/30°C.

In order to commercialize this into the required product, 16 kg of water was added to the composition thus made to achieve a resin concentration of 8.
It was set to 0%.

The composition of this product is resin concentration... 80
wt, % free phenol...Concave...3.
5wt, % free formaldehyde...Q, 18
wt, % moisture・・・・・・・・・・・・・・・
9.7wt, % viscosity...
...700Cp/30'C.

In the resin composition produced by the method of the present invention, if the free formaldehyde content is 0.15% or more, the working environment will be seriously deteriorated due to formaldehyde gas during kneading or molding.

In other words, the irritating odor is very noticeable and is very bad for worker hygiene.

Furthermore, as described above, an appropriate amount of water is required to adjust the amounts of the resin component and free monomer within the required range.

In particular, if the composition has a water content of 45% or more, a separation phenomenon tends to occur between the resin component and the water component.

Furthermore, if the water content is less than 20%, the viscosity increases and it becomes difficult to use.

In the present invention, the content limit value of phenolic resin is 5
The reason why I chose the value % from 0 to 80wt is that if 50w
If the molding temperature is less than t,%, the residual moisture in the mold will increase and drying will be necessary, and the residual moisture will slow down the internal hardening speed.

On the other hand, if it exceeds 80 wt.%, the wettability to the aggregate becomes poor and the mold performance is poor.

The fluidity of the coating sand deteriorates, causing clogging and defects.

However, if the free phenol content exceeds 5 wt.%, it must be handled in accordance with the Ordinance on Prevention of Hazards from Specified Chemical Substances, the Poisonous and Deleterious Substances Control Law, etc., and is subject to very severe restrictions in terms of potash and occupational safety and health.

Furthermore, phenol gas is generated during kneading, molding, and pouring, and there is a risk that it will have an adverse effect on the human body, such as rashes.

Next, we conducted an experiment to determine the degree of conductivity caused by steam when using crystal.

Quartz contains no organic solvents except phenolic resin, water and some unreacted phenol and unreacted formaldehyde.

Therefore, with regard to toxicity due to vapor, it is only necessary to consider the unreacted components remaining in the resin.

The crystal has less than 1/2 the unreacted content compared to conventional phenolic resin type products.

The allowable concentration and vapor pressure of each component for crystal are shown below.

Phenol resin is originally in the form of a solid substance and is not volatile at room temperature.

Free phenol also has low toxicity due to its low vapor pressure.

Among these, formaldehyde is relatively problematic.

This is despite the fact that the content is low due to the high vapor pressure.
Shows a value close to the permissible concentration.

For this reason, the amount of formaldehyde in the resin is regulated to within 0.5%.

The gases generated during kneading and molding of crystal are shown below.

Condition: 1 bi-speed mixer 1・・・・・・・・・・・・・・・・・・・・・・
・0.8% mouth hardening agent・・・・・・・・・・・・・・・・・・5
Although a very small amount of formalin was sometimes detected during 0% kneading and molding, it was generally below the allowable concentration and caused no problem.

The concentrations of other gases were too low to be measured with a detector tube.

In the present invention, if the free phenol content is 5%, the internal curing ability is good even in a large mold.

A comparison of the internal curing ability of the resin produced in Production Example 1 and Comparative Example is shown below.

Condition Bi-speed mixer resin 0.8wt, % (relative to sand) Hardener
50wt, % (relative to phenolic resin) Hirakaki strength measures the depth of teeth sunk in by rotational force, and the smaller the value, the higher the mold strength.

This result shows that resins with less free phenol have higher internal strength, and therefore moldability is better when there is less resin with less free phenol.

To use the present invention for coating sand and forming molds, conventional methods may be used.

It has been found that the strength of the mold thus obtained is normal or better.

Claims (1)

[Claims] 1 A process comprising a first step of mixing and heating phenol, formaldehyde, and a catalyst to perform condensation polymerization, and a second step of heating the product of the step under reduced pressure to dehydrate it. Between the end of the first step and the beginning of the second step, an artificial water addition step is inserted at an amount of added water such that the resin concentration is 5 to 45 wt% or less, and the second step is performed under reduced pressure and Under heating, flushing with a large amount of generated water vapor prevents the formation and adhesion of excessive condensation polymerization products on the inner surface of the tube wall, and performs continuous dehydration treatment with a small ratio L/D of tube length (L) to tube inner diameter (D). Tomo 1000
1. A method for producing a liquid phenolic resin composition for organic self-hardening molds, which is carried out in a pipe.