JP3526467B2 - Method for producing oxidized ethylene polymer - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an oxidized ethylene-based polymer. More specifically, it relates to a method for producing a high-melting point oxidation type ethylene polymer useful as a floor polish and a fiber treating agent.

[0002]

2. Description of the Related Art Conventionally, as a method for producing an oxidation type ethylene polymer, a low molecular weight polyethylene obtained by decomposing a high molecular weight polyethylene or a low polymer of ethylene is oxidized in a molten state by oxygen or oxygen containing ozone. Method (for example, Japanese Patent Publication No. 47-43310,
JP-B-48-37991, JP-A-50-11998
89, etc.) or a method in which high-density polyethylene powder is mixed with a small amount of organic peroxide and oxidized in the presence of oxygen at a temperature below the melting point of polyethylene (West German Patent Publication 14).
95938, JP-A-57-170905), and a method of contacting oxygen in the presence of boric acid at a temperature below the melting point in an aqueous medium of polyolefin (Japanese Patent Publication No. 50-35).
117) or a method of contacting with oxygen in the presence of phosphoric acid (Japanese Patent Publication No. 51-29558), and recently, an aqueous dispersion of an ethylene-based polymer has a melting point or less and oxygen in the presence of a water-soluble copper compound. Method of contact with (Japanese Patent Laid-Open No. 4-136004)
No. publication) is proposed.

[0003]

However, in the method of using a low molecular weight olefin having a thermally reduced molecular weight, the molecular weight and the melting point are lowered so that good physical properties cannot be obtained, and a method of directly oxidizing the material at a temperature lower than the melting point is used. However, there was a problem that a decrease in melting point could be prevented but a sufficient catalytic effect was not observed, a polyolefin having a high acid value could not be obtained, and poor emulsification might occur.

[0004]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have found that the oxidation rate is equivalent to that of the conventional method, the above-mentioned pretreatment is unnecessary, and the melting point is The present invention has been accomplished by finding a method of acid value of an ethylene-based polymer in which the emulsification property and the transparency are good because the acid value of the obtained oxide is sufficiently high.

That is, in the present invention, an aqueous dispersion of a polymer is used as a catalyst using cobalt (II) acetylacetate or / and cobalt (III) acetylacetate at a temperature below the melting point of an ethylene polymer and containing oxygen or oxygen. It is a method for producing an oxidized ethylene-based polymer, which comprises contacting with a gas to oxidize it.

In the present invention, examples of the ethylene polymer include low density polyethylene, high density polyethylene, and a copolymer of ethylene and one or more kinds of other α-olefins. Examples of this other α-olefin include propylene, 1-butene, and 4-methyl-1-.
Mention may be made of pentene, 1-octene, 1-decene and 1-dodecene. Among these ethylene polymers, high density polyethylene is preferable. In the present invention,
The melt index (hereinafter abbreviated as MI) of the ethylene polymer is usually 0.03 to 50, preferably 0.1 to 25. MI is JISK6760 (temperature 190
It can be measured according to ° C and a load of 2.16 Kgf).

In the present invention, the shape of the ethylene polymer is not particularly limited, and examples thereof include powder, pellet, film, fiber, filament and the like. Of these shapes, powder is preferable. These ethylene-based polymers can be obtained by a known polymerization method such as a high pressure polymerization method or a low pressure polymerization method using a Ziegler catalyst.

In the present invention, in order to obtain a stable aqueous dispersion of the ethylene polymer, it is desirable to add a surfactant to the liquid. Examples of this surfactant include anionic surfactants (sodium lauryl sulfate, sodium dodecylbenzene sulfonate, etc.), nonionic surfactants (polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, polyhydric alcohol fatty acid ester, etc.) Is mentioned. The amount of the surfactant added is 100 parts by weight of the ethylene polymer,
It is usually 0.01 to 5 parts by weight.

The amount of cobalt (II) acetylacetate or / and cobalt (III) acetylacetate used as a catalyst in the present invention is 0.001-1 based on 100 parts by weight of the polyethylene polymer in terms of pure cobalt. 0.0 parts by weight, preferably 0.0
1 to 0.5 parts by weight. If it is less than 0.001 part by weight, it takes a long time to oxidize and the reaction is performed for a long time, so that the hue is lowered. On the other hand, when it is 1.0 or more, the hue of the obtained oxidized polyethylene polymer is lowered and it is also disadvantageous in terms of cost.

In the present invention, a co-catalyst may be used in combination for promoting the oxidation of the above cobalt (II) acetyl acetate and / or cobalt (III) acetyl acetate. As the cocatalyst, there are water-soluble iron salts, water-soluble copper salts, and the like. Especially, iron sulfate, iron oxalate, iron citrate and the like are preferable, and iron citrate is particularly effective. The amount of the co-catalyst used is appropriately 1/100 to 1/10 of cobalt (II) acetylacetate or / and cobalt (III) acetylacetate used as a catalyst, as a metal pure content.

Furthermore, inorganic peroxides such as potassium persulfate;
Organic peroxides such as benzoyl peroxide, di-tert-butyl peroxide, and dicumyl peroxide, as well as 2,2-azobis (isobutyronitrile) and 2,2-azobis (2,4-dimethylvaleronitrile) You may use together such a radical generation initiator.

In the present invention, the reaction temperature for oxidation is
Usually, the temperature is lower than the melting point of the ethylene polymer, preferably 2 to 10 ° C. lower than the melting point of the ethylene polymer. At a temperature higher than the melting point, ethylene becomes in a molten state and cannot be sufficiently stirred due to adhesiveness, and oxidation cannot be performed uniformly, or a rapid decrease in molecular weight occurs due to local heating.For example, floor polish, fiber It becomes impossible to obtain a high-softening point ethylene polymer oxide useful as a processing agent. In the present invention, examples of the oxygen-containing gas include air and oxygen-containing gas having an increased oxygen concentration in the air.

In the present invention, the oxidation reaction is usually carried out in a pressurized reactor capable of supplying oxygen or the oxygen gas. The pressure during the reaction is usually 1 to 100 Kg / cm
^2. Gauge pressure, preferably 5 to 50 Kg / cm ²
Is. In order to maintain a constant pressure during the reaction, continuously,
It is carried out by supplying oxygen or the oxygen-containing gas. The time required for the oxidation reaction is usually 2 to 60 hours.

The acid value of the oxide of the ethylene polymer obtained by the method of the present invention is usually 5 to 50, preferably 10 to 30. If the acid value is less than 5, a highly transparent emulsion cannot be obtained. On the other hand, when it is 50 or more, it takes a long time to oxidize and the molecular weight decreases.

[0015]

The present invention is described in detail below with reference to examples, but the present invention is not limited to these examples.
Parts in the examples are parts by weight.

Example 1 1500 g of powdered high-density polyethylene (density: 0.
96, MI: 0.5), ion-exchanged water 1500 g, polyoxyethylene nonylphenyl ether (ethylene oxide 10 mol addition) 1.5 g, cobalt (II) acetylacetate dihydrate, 7.5 g (as Co pure content) 0.001 part by weight of polyethylene), 0.5 g of iron citrate (Fe
(1/20 to Co 1/20) was charged, the temperature was raised to 115 ° C. with sufficient stirring, and air was supplied so that the pressure of the autoclave was 10 kg / cm ² while maintaining this temperature, and the reaction was carried out for 40 hours. After completion of the reaction, the reaction product was taken out from the autoclave, filtered, washed with water repeatedly, and then vacuum dried. The powdered polyethylene thus obtained has an acid value of 19.3 and a melt viscosity of 1 at 160 ° C.
The melting point according to 0800 cPs and DCS was 132 ° C.

[0016]

Example 2 As in Example 1, powdered polyethylene 10
00 g (density: 0.96, MI: 8.0), ion-exchanged water 1500 g, polyoxyethylene nonyl phenyl ether (ethylene oxide 10 mol addition) 0.5 g, cobalt (III) acetyl acetate 4.2 g (Co pure content) 0.0007 parts by weight with respect to polyethylene) as
The reaction was carried out at an oxygen pressure of 25 Kg / cm ² for 6 hours. The obtained oxidized polyethylene has an acid value of 31.2, a melt viscosity at 160 ° C of 4300 cPs, and a melting point by DSC of 133 ° C.
Met.

[0017]

Comparative Example 1 The oxidation reaction was carried out for 40 hours in the same manner as in Example 1 except that cobalt (II) acetyl acetate was not used. The obtained polyethylene oxide has an acid value of 4.3 and DS
The melting point according to C was 134 ° C.

Claims (2)

(57) [Claims] 1. An ethylene polymer is dispersed in water and brought into contact with oxygen or an oxygen-containing gas in the presence of cobalt (II) acetyl acetate or / and cobalt (III) acetyl acetate to obtain a melting point of the ethylene polymer. A method for producing an oxidized ethylene-based polymer, which comprises oxidizing at the following temperature. 2. The method for producing an oxidized ethylene-based polymer according to claim 1, which comprises adding a water-soluble organic iron compound to cobalt (II) acetyl acetate and / or cobalt (III) acetyl acetate.