JPS5947691B2 - Method for producing unsaturated polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an unsaturated polyester from an alkylene oxide and an acid component in which 15 to 70 mol % of saturated or unsaturated dicarboxylic acids or their anhydrides are isophthalic acid.

Conventionally, unsaturated polyesters containing isophthalic acid as part of the acid component (hereinafter referred to as isophthalic acid) are compared to unsaturated polyesters using orthophthalic acid instead of isophthalic acid (hereinafter referred to as ortho-type). It has excellent properties as a resin, such as water resistance, chemical resistance, and mechanical strength, but its disadvantage is that the esterification reaction time generally takes more than twice that of ortho-based resins, and productivity is low. has been done. Furthermore, when looking at iso-unsaturated polyesters, there are two methods of reaction for producing them, called a one-step method and a two-step method. That is, the one-stage method is a method in which all acid components including isophthalic acid are reacted with glycol at the same time, and the two-stage method is a method in which isophthalic acid and glycol are reacted, and at an acid value of 30 or less, an unsaturated acid is further reacted. This is the way to do it. Although the one-stage method has a shorter reaction time than the two-stage method, it has the disadvantage that the performance of the resulting resin is inferior. For example, as pointed out in ``Reinforced Plastics, vol. 193P, 308'', unsaturated polyesters obtained by a one-step process are
Generally, the acid value is high, and the resin has a high bending strength, heat distortion temperature,
It has poor properties such as water resistance and alkali resistance. Therefore, commercially available iso-unsaturated polyesters are generally produced by a two-step process. The method for producing unsaturated polyesters, in which alkylene oxa/nido reacts with dicarboxylic acid or its anhydride as the acid component, is well known from many patents, but in this case, one of the acid components is There are no reports on the method of adding isophthalic acid to

The reason for this is that isophthalic acid has an extremely high melting point of 353° C., making it difficult to react with alkylene oxide. As a result of extensive research, the present inventors have discovered a method for producing an excellent iso-unsaturated polyester by reacting an acid component containing 15 to 70 mol% of isophthalic acid with an alkylene oxide.

Generally, the reaction between glycol and isophthalic acid, e.g.
In the reaction between propylene glycol and isophthalic acid, the 35'F6 of isophthalic acid dissolves in propylene glycol at 180°C and the reaction proceeds, but in the reaction between alkylene oxide and an acid component containing isophthalic acid, as described above, The reaction does not proceed because isophthalic acid has a high melting point and does not melt.

Even if maleic anhydride is used as the melting acid, 21
The solubility of isophthalic acid at 0°C is only 3%, making the reaction extremely difficult. The present invention is the result of an analysis of the esterification reaction mechanism between an alkylene oxide and an acid component containing 15 to 70 mol% of isophthalic acid, and the content of the analysis will be specifically explained below.

When a mixture consisting of 4 moles of maleic anhydride, 6 moles of isophthalic acid, and 1 mole of ethylene glycol as an initiator is heated to a reaction temperature of 210° C., the solubility of isophthalic acid in maleic anhydride becomes a suspension state of 3%.

When propylene oxide is blown into this suspension system, the esterification reaction is initiated. When undissolved isophthalic acid was quantified hourly, it was 95% in 1 hour, 80% in 2 hours, 70% in 3 hours, and 55% in 4 hours, and the reaction time was 5 hours when 10 moles of propylene oxide was blown into it. At this time, the amount of undissolved isophthalic acid was 30%, and the acid value in the system was 120. After the propylene oxide injection was completed, the reaction was continued for another 1 hour, and 600T was produced in 3 hours.
The pressure was reduced to fr1rLHy to obtain an ester with an acid value of 30.
The above reaction can be estimated from a model as follows.

That is, the reaction system consists of 6 moles of isophthalic acid, 4 moles of maleic anhydride, 1 mole of ethylene glycol, and 9 moles of propylene oxide, and at the beginning of the reaction, the addition reaction of propylene oxide to maleic anhydride proceeds, resulting in the following: It becomes like this. In parallel with this esterification, propylene oxy-
戊-h{Junior Fl. Five monoesters of T1P, E1P, E1P, I-P, E1P, I and one isophthalic acid are present. However, 〇 indicates isophthalic acid. In the actual reaction process, since only a small amount of condensed water distills out at the end of propylene oxide blowing, it is unlikely that isophthalic acid participates in the esterification reaction of dimers or more. .

As the esterification reaction further progresses, the following results occur.

This condensation step is a reaction between hydroxyl groups and carboxylic acids, producing water of condensation.

Since the rate determining factor of this reaction is the production of condensed water, it is effective to remove the condensed water by reducing the pressure. -Generally, in the esterification reaction using glycol, glycol is distilled out when condensation water is removed by reduced pressure, and its separation is difficult, so vacuum dehydration is performed at a reaction rate of about 90%, In the production of unsaturated polyester using the method, there is no such problem, and since only condensed water is distilled out under reduced pressure, the dehydration operation under reduced pressure is extremely easy.

The reaction of the present invention is carried out at a reaction temperature of 180°C or higher, preferably 2°C.
00°C or higher, reacts under normal pressure or slightly increased pressure,
It is desirable to remove the condensed water by reducing the pressure within 1 hour after the completion of alkylene oxide addition.

The alkylene oxide is preferably blown into the reaction system under normal pressure or increased pressure, and the amount is controlled to such an extent that it does not distill out of the system.

The alkylene oxide distilled out of the system can be returned into the system if necessary. The inventors,
By effectively utilizing the characteristics of alkylene oxide as described above, we have established a method for producing isophthalic acid-based unsaturated polyester, which had been considered difficult.

The isophthalic acid used in the present invention accounts for 15% of the total acid components.
It is effective within the range of 70 mol%.

That is, when the amount is less than 15 mol%, the resulting unsaturated polyester is inferior in chemical resistance and mechanical properties,
In addition, when the content is 70 mol% or more, the resulting unsaturated polyester has good curability and heat resistance (heat distortion temperature is 60% or less).
V.C. All of them are unsuitable for molding, paints, or coatings. The organic polybasic acids other than isophthalic acid used in the present invention are preferably dicarboxylic acids or their anhydrides, such as maleic anhydride, itaconic anhydride, citraconic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, and endomethylenetetrahydrophthalic anhydride. Anhydrides such as phthalic acid, tetrachlorophthalic anhydride, hexachloroendomethylenetetrahydrophthalic anhydride, and in some cases one or more of the above dicarboxylic acids, adipic acid, fumaric acid, head acids, etc. It is used together.

Examples of alkylene oxide include ethylene oxide,
Propylene oxide, butylene oxide, styrene oxide, methyl glycidyl ether, propyl glycidyl ether, phenyl glycidyl ether, etc. are used.

In carrying out the present invention, it is preferable to use a reaction initiator.

Although isophthalic acid itself acts as a reaction initiator, it is more preferable to use one that is highly reactive with acid anhydrides, such as ethylene glycol and propylene glycol.
The present invention will be explained below with reference to Examples.

Example 1 A 20 t reactor was equipped with a blowing device, a fractionating condenser, and a condensing condenser, and propylene glycol 532
7 (7 mol), maleic anhydride 4116f (42 monoli), isophthalic acid 46487 (28 mol),
00 CVC heating.

Next, propylene oxide is blown into the system, and the amount is controlled so that it does not evaporate out of the system. It took about 4 hours to blow in 4040 tons (70 moles) of propylene oxide. The acid value at this time was 120, and the solubility of isophthalic acid was 70% of the amount used. React for another 1 fC for 1 hour and the acid value will be 600? The pressure was reduced to Ht, and the reaction was completed 30 hours later. Total reaction time was 9 hours. The reaction product was transparent and had an acid value of 30. Example 2 Into the same reaction apparatus as in Example 1, 266 tons of propylene glycol (35 tons) and 4807 tons of maleic anhydride (4 tons) were added.
9 mol), isophthalic acid 23247 (14 mol), endomethylene anhydride tetrahydrophthalic acid 1149 t (
After heating at 200'CVC, propylene oxide 42347 (73 moles) was blown into the reactor over a period of 3 hours.

The acid value at this time was 68, and the reaction was further carried out for 90 minutes under reduced pressure of 6007 mH7 to obtain a transparent reaction product with an acid value of 18. Total reaction time was 5 hours and 30 minutes. Comparative Example 1 In the formulation of Example 1, propylene glycol 5320t (70 mol) was used instead of propylene oxide.

Using the same reactor as in Example 1, the reaction was carried out as follows. By a two-stage reaction method, propylene glycol and isophthalic acid were charged, and the temperature was raised to 190°C in 30 minutes.

After 10 hours of reaction, when the acid value reached 32, the temperature was lowered to 1.
00C1fC. The temperature was lowered, maleic anhydride was charged, and the temperature was raised to 215°C over 2 hours.

At an acid value of 70, the reaction at 215°C was performed for a total of 2 hours and 30 minutes, including 1 hour of reaction under reduced pressure of 660 WfLH7, and the acid value was 3.
A clear reaction product of 0 was obtained. Total reaction time was 16 hours. Comparative Example 2 In the formulation of Example 2, propylene glycol 5548t (73 mol) was used instead of propylene oxide.

A two-stage reaction was carried out in the same manner as in Comparative Example 1. 190 in 30 minutes after adding propylene glycol and isophthalic acid
The temperature was raised to ℃. After reacting for 8 hours, the acid value reached 30, the temperature was lowered to 100°C, maleic anhydride and endomethylenetetrahydrophthalic anhydride were added, and the temperature was raised to 215°C over 2 hours.

The reaction was carried out at 215°C for a total of 2 hours and 30 minutes, including 1 hour of reaction under reduced pressure at 660 TmHt at an acid value of 70.
A clear reaction product was obtained. Total reaction time was 14 hours. The unsaturated polyesters of Example 1 and Comparative Example 1 were dissolved in styrene containing 0.016 parts of hydroquinone based on the resin amount to obtain respective unsaturated polyester resins.

The amount of styrene is 37% by weight of the resin. Further, the unsaturated polyesters of Example 2 and Comparative Example 2 were dissolved in styrene containing 0.025 parts of hydroquinone based on the amount of resin to obtain respective unsaturated polyester resins.

The amount of styrene is 3.7% by weight of the resin. The properties of the obtained unsaturated polyester resin are shown in Table 1, and the properties of the cast cured product are shown in Table 2.

Claims (1)

[Claims] 1. When producing an unsaturated polyester from an alkylene oxide and an organic polybasic acid containing an unsaturated acid or its anhydride as at least one of the acid components,
70 mol% is isophthalic acid, and the alkylene oxide is blown in at a reaction temperature of 180° C. or higher, under normal pressure or slightly increased pressure, and controlled to the extent that the alkylene oxide does not distill out of the reaction system. A method for producing an unsaturated polyester, which comprises reducing the pressure within one hour after completion of the reaction to remove condensation water.