JPS6045204B2 - Method for producing ethylene-ethyl acrylate-acrylic acid polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an ethylene-ethyl acrylate-acrylic acid polymer.

Ethylene-ethyl acrylate with improved color and solubility especially from ethylene-ethyl acrylate polymers
This invention relates to a novel manufacturing method for continuously manufacturing acrylic acid polymers. Conventionally, ammonia aqueous solutions of ethylene-acrylic acid polymers have been used as emulsion adhesives and water-based paints, but these applications require low viscosity at high resin concentrations.

Therefore, relatively low molecular weight ethylene-acrylic acid polymers are needed to meet such demands. However, when an ethylene-acrylic acid polymer is obtained by hydrolyzing a normal ethylene-ethyl acrylate polymer, the melt index is compared to that of an ethylene-ethyl acrylate polymer due to intermolecular hydrogen bonding of acrylic acid groups. The melt index of ethylene-acrylic acid is significantly reduced.

For example, in order for the ethylene-acrylic acid polymer to have a high concentration as an ammonia aqueous solution, the melt index must be approximately 30 Og/l0mln (190°C);
/10 min (190°C) or more of ethylene-ethyl acrylate polymer is required. However, although ethylene-ethyl acrylate polymers can generally be produced by high-pressure polymerization methods known in the art, it is extremely difficult to produce such low molecular weight ethylene-ethyl acrylate. In other words, the ethylene-ethyl acrylate polymer has a melt index of 300g/101T11n (190g/101T11n).
C) or higher, the viscosity immediately after production is extremely low, and it is extremely difficult to granulate, cool, or crush it using ordinary equipment. In addition, installing new equipment to produce such a special small amount of ethylene-ethyl acrylate polymer by high-pressure polymerization has the disadvantage that it is too costly. Furthermore, when producing ethylene-ethyl acrylate polymer using a high-pressure polymerization method, the reaction rate difference between ethylene and ethyl acrylate makes it difficult to produce an ethylene-rich copolymer and acrylic acid. The blending tendency of ethyl-rich copolymers is significantly increased, which has a negative impact on the physical properties of the final product. Without the need for such a low molecular weight ethylene-ethyl acrylate polymer, a high-concentration, low-viscosity resin can be obtained from a conventional comparatively high molecular weight ethylene-ethyl acrylate polymer as an ammonia aqueous solution using a conventional manufactured ethylene-acrylate polymer. Ethyl acid polymer (melt index 300g/10m1)
jn or less, ethyl acrylate content is 10 to 4% by weight) can be obtained by continuously reacting ethyl acrylate in the presence of water or steam by adjusting temperature, pressure and time.

On the other hand, as mentioned above, the ethylene-ethyl acrylate polymer which is the raw material for the present invention can be produced by conventional methods known in the art. That is, U.S. Patent No. 335
No. 03n contains ethylene and alkyl acrylate from 700 to
A preferred method of copolymerizing at a pressure of 2800k9/Clt and a temperature of at least 93°C is shown. The polymerization reaction takes place in the presence of a free radical polymerization initiator and a small amount of! It can be carried out in the absence of added solvents other than those used for the catalyst support or telogen agent. The molar ratio of ethylene to ethyl acrylate in the ethylene-ethyl acrylate polymers encompassed within the scope of the present invention can be applied over a wide range, but typically contains up to 0.5 moles of acrylic acid per 5 moles of ethylene. Contains Ezal. In the present invention, when an ethylene-ethyl acrylate polymer having a relatively high molecular weight is continuously heated, kneaded and extruded using an extruder, and reacted, the extruder must be able to completely control the area in which the ethylene-4 ethyl acrylate polymer is in a solid state. pressure 200
Tn! The molecular weight, ethyl acrylate content, and acrylic acid content were arbitrarily controlled by reducing the pressure to NHg or less, then heating and kneading, injecting water or steam beyond the melting region, heating, pressurizing, kneading, and reacting. A method for obtaining an ethylene-ethyl acrylate-acrylic acid polymer.

In particular, the reaction is based on the new fact that the degradation of the ethylene polymer chain of the ethylene-ethyl acrylate polymer and the conversion of the ester group of the ethyl acrylate into an acid can be controlled under particularly selected conditions. ing. That is,
To achieve the object of the present invention, it is necessary to react ethylene-ethyl acrylate, which has a relatively high molecular weight, to degrade the ethylenefurine polymer chain, and to control the molecular weight to a desired value. At the same time, it is necessary to arbitrarily control the conversion reaction of the ester group of ethyl acrylate to acid. However, ethylene
In alkyl acrylate polymers, it is known that the dissociation energy of the alkyl group in the ester group varies depending on the alkyl group. Therefore, in the present invention, since it is necessary to simultaneously control the scission of the ethylene polymer chain and the conversion of the ester group into an acid, ethylene-ethyl acrylate is particularly suitable for the reaction among the ethylene-alkyl acrylate polymers. Based on the discovery that ethylene-ethyl acrylate polymers are suitable, the ethylene-ethyl acrylate polymer is limited. The reaction in the present invention is carried out at 250% in order to effectively carry out the ethylene polymer chain scission reaction.
A temperature of ℃ or higher is required.

This temperature is also necessary for the conversion reaction of acrylic acid ethyl ester to acid. This reaction temperature is, of course, above the temperature range required for the conversion reaction of the produced acrylic acid to an acid anhydride or the over-decomposition reaction such as decarboxylation reaction in the absence of water or steam. Therefore, when these reactions involving ethylene-ethyl acrylate polymers are carried out under an inert atmosphere on an economical industrial scale according to general procedures, the ethylene-ethyl acrylate-acrylic acid polymers produced are When coalescing, there is a degree of discoloration that cannot be avoided, resulting in a decrease in product value. Although these coloring processes have not been elucidated, the conjugated double bond formed in a part of the main chain due to the cleavage of the ethylene polymer chain in the above reaction and the oxidation reaction product or peroxidation of the carboxylic acid produced by conversion from the ester. It is possible that decomposition reaction products or other abnormal reaction products are involved. Furthermore, when the ethylene-ethyl acrylate-acrylic acid polymer obtained by the above-mentioned general method is made into an ammonia aqueous solution, an insoluble portion is generated to the extent that the commercial value is reduced. Removal of this insoluble portion by filtration increases costs and is not desirable in industrialization. This insoluble part is completely removed. It is thought that many intermolecular crosslinks are involved as a result of the reaction proceeding in the presence of residual oxygen that could not be completely eliminated.
The present invention aims to continuously obtain a resin which becomes low in viscosity at high concentration as an ammonia aqueous solution from ordinary ethylene-ethyl acrylate having a relatively high molecular weight while avoiding such defects.

As a result of intensive research to achieve this objective, we have discovered new and effective facts. That is, a relatively high molecular weight ethylene-ethyl acrylate polymer (
A melt index of 300g/10rT11n or less and an ethyl acrylate content of 10 to 10% by weight is supplied to the extruder, and the area in which the ethylene-ethyl acrylate polymer maintains a solid state in the extruder is After the ethylene-ethyl acrylate is heated and sufficiently melted, water or steam is injected and at the same time, heating, pressurization, and kneading are appropriately controlled to cause a continuous reaction. It is possible to obtain an ethylene-ethyl acrylate-acrylic acid polymer in which the ethyl acrylate content and the acrylic acid content are arbitrarily controlled. It was found that the reaction product polymer was significantly improved in terms of color and formation of insoluble portions in aqueous ammonia solution compared to the reaction product polymer reacted in an inert atmosphere.

Moreover, when the ethylene-ethyl acrylate-acrylic acid polymer is made into an ammonia aqueous solution, there is no change in the properties of high resin concentration and low viscosity, and the properties that the film formed from the ammonia aqueous solution is flexible and tough without cracking. I stopped talking.
One method of carrying out the present invention is to supply the raw material ethylene-ethyl acrylate polymer to a conventional resin extruder that can reduce the pressure in the supply section, heat and knead it, and then heat or knead it with water or steam in the extruder or after passing through the extruder. is injected and then kneaded under heat and pressure in a reaction tube equipped with fixed stirring blades to react.

As the pressure reducing device, for example, a commercially available vacuum hopper for extrusion decomposition can be used. Combining these extruders with vacuum hoppers is nothing new.
Generally, a vacuum hopper is used for the purpose of removing volatile components (such as moisture) from the extruded material, but in the present invention, experiments have shown that the increase or decrease in volatile components has no bearing on the magnitude of the effect of the present invention. As a result, it has become clear that this has nothing to do with the use of a conventional vacuum hopper extruder. Next, the extruder is capable of injecting water or steam after heating and melting and kneading the raw material ethylene-ethyl acrylate polymer. Furthermore, it is equipped with a reaction tube equipped with fixed stirring blades that can maintain sufficient temperature, pressure, and time for reaction during heating and kneading. The steps of water or steam injection and heating and kneading reaction can be carried out in the extruder or in a separate extruder replacing the reaction tube. The configuration of these devices other than the reduction of the absolute pressure of the raw material solid maintenance region to below 20 H and the injection of water or steam after melting the raw material do not limit the present invention. Furthermore, although the effect can be seen even when the pressure reduction in the solid state maintenance region of the raw material is below atmospheric pressure, it is practically effective to reduce the pressure below the absolute pressure of 200Tf0nHg. Further, both of these reduced pressures and the presence of water or (and) steam during the reaction are indispensable. Even if either one of them is missing, the object of the present invention cannot be achieved. On the other hand, Japanese Patent Publication No. 46-21643 discloses a method in which ethylene-acrylic acid isopropyl ester or ethylene-methacrylic acid isopropyl ester is reacted at a temperature higher than the ester decomposition temperature in the presence of water vapor, but this method is different from the present invention. This method uses raw materials with different ester decomposition temperatures, and is a reaction that does not involve decomposition of ethylene polymer chains, and as described above, the product is significantly different from the present invention, which requires decomposition of ethylene polymer chains. This invention is different from the present invention, which is concerned with the improvement of coloration or insoluble components in an ammonia aqueous solution, and furthermore, it does not disclose any elements constituting the present invention.

The present invention will be explained below with reference to Examples. Example 1 A high-pressure polyethylene extruder of 9 caliber 4mm and L/=22 was equipped with a commercially available vacuum hopper, and water could be injected from a high-pressure pump into the cylinder part corresponding to the metering area of the screw. A reaction tube was connected to the tip of the reactor, which was composed of a plurality of reaction tubes with fixed stirring blades and a filled reaction tube alternately, and a reaction equipment equipped with a throttle valve was used at the outlet.

The extruder feed section was maintained at an absolute pressure of 60T0f1Hg, and ethylene-ethyl acrylate polymer (ethyl acrylate content: 3
%, melt index 100) at a rate of 4 kg/Hr, heated the extruded material to 260°C in the quantitative range, injected 60'C water at a rate of 4g/Min, and kneaded and extruded. The reaction was carried out in a reaction tube at a maximum temperature of 360'C (
The residence time in the entire reaction tube at this time was 1 hour and 20 minutes).As a result, an ethylene-ethyl acrylate-acrylic acid polymer having the following properties was obtained. melt index
580 ethyl acrylate content
5J weight% acrylic acid content 19.4
Weight% Color: Immediately after melting at 90°C, equivalent to Gardner 2 25
% ammonia solution was clear.

Comparative Example 1 The reaction was carried out under the same conditions as in Example 1, except that the pressure in the feed section of the extruder was reduced, water was not injected, and the residence time in the reaction tube was shortened, and the following characteristics were obtained. An ethylene-ethyl acrylate-acrylic acid polymer was obtained.

Melt index 650 Ethyl acrylate content 4. Weight% acrylic acid content
19.1% by weight, color: immediately after melting at 90'C,
The 25% ammonia aqueous solution equivalent to Gardner 7 contained an insoluble portion and was cloudy.

Comparative Example 2 A reaction was carried out under the same conditions as in Comparative Example 1 except that water was injected, and the following results were obtained.

Color: Immediately after melting at 90'C, an ammonia aqueous solution equivalent to Gardner 4-5: White turbidity was observed.

Comparative Example 3 A reaction was carried out under the same conditions as Comparative Example 1 except that the pressure of the extruder was reduced, and the following results were obtained.

Color: Immediately after melting at 90°C, ammonia aqueous solution equivalent to Gardner 4: White turbidity was observed.

Comparative Example 4 A hot air-dried ethylene-ethyl acrylate polymer was reacted under the same conditions as in Comparative Example 2 to obtain the following ethylene-ethyl acrylate-acrylic acid polymer.

Color: Immediately after melting at 90°C, ammonia aqueous solution equivalent to Gardner 4-5: White turbidity was observed.

Comparative Example 5 Same conditions as Example 1, except that the absolute pressure of the supply section was 300T0f1
When the reaction was carried out as Hg, the following results were obtained.

Color: Immediately after melting at 90°C, ammonia aqueous solution equivalent to Gardner 4-5: White turbidity was observed. Comparative Example 6 The reaction was carried out under the same conditions as in Example 1, except that the atmosphere in the supply section was continuously replaced with nitrogen, and the following results were obtained.

Color: Immediately after melting at 90°C, ammonia aqueous solution equivalent to Gardner 4: White turbidity was observed.

Claims (1)

[Claims] 1. A method for producing an optionally low molecular weight ethylene-ethyl acrylate-acrylic acid polymer by continuously heating and kneading an ethylene-ethyl acrylate copolymer in the presence of water or steam using an extruder, Immediately after feeding the ethylene-ethyl acrylate copolymer in the extruder, the pressure is reduced to an absolute pressure of 200 mmHg or less, and water or steam is injected into the melting region, and at the same time the temperature is at least the ester decomposition temperature and the temperature at which the main chain of the copolymer starts to break. A method for continuously producing an improved low molecular weight ethylene-ethyl acrylate-acrylic acid polymer, characterized in that the reaction is carried out by heating, pressurizing, and kneading.