JPS5812883B2 - Method for producing halogenated polyolefin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for halogenating polyolefins in an aqueous suspension system.

The method of halogenating polyolefin in an aqueous suspension has the advantages of high safety and low production costs, but on the other hand, it tends to cause partial halogenation and particles tend to aggregate with each other during the reaction. This causes a decrease in the rate and non-uniform halogenation, and may sometimes prevent the reaction from continuing.

Although many proposals have been made to avoid these drawbacks, no definitive method has yet been found.

For example, in order to achieve uniform halogenation, if the reaction is carried out near the melting point of the polyolefin, aggregation between particles will occur even more intensely.

In order to prevent the above-mentioned agglomeration, various methods have been proposed, such as a method of continuously adding a surfactant and a method of making an additive having an agglomeration-preventing effect exist in water, but since these additives change in quality during the reaction, This method was not desirable as it increased the cost or caused the product to deteriorate mechanical properties or cause coloration.

Furthermore, according to the conventional method, the concentration of polyolefin in water is at most 10 from the viewpoint of suspension stability and prevention of particle agglomeration.
%, and it was almost impossible to exceed 120%.

Therefore, the capacity of the reactor for the halogenation treatment had to be increased.

An object of the present invention is to provide a halogenation method that enables uniform halogenation without adding surfactants or other additives to water, and that has almost no fear of particle aggregation.

Another object of the present invention is to provide a method for halogenating even highly concentrated polyolefin suspensions.

Another object of the present invention is to produce a halogenated polyolefin with good physical properties.

Other objects of the invention will become clear from the following description.

According to the present invention, substantially spherical particles of a polyolefin having a particle size of 0.1 to 10μ containing 1 to 30% by weight of a salt of a carboxyl group-containing polyolefin having an acid value of 10 to 150 are prepared in an aqueous medium. A method for producing a halogenated polyolefin characterized by halogenation is provided.

The raw material for halogenation of the present invention is a stable aqueous dispersion of a polyolefin containing a salt of a carboxyl group-containing polyolefin wax.

Here, polyolefins include ethylene, propylene, 1-
It is a homopolymer or a copolymer of 1-olefinic unsaturated hydrocarbons such as butene and 4-methyl-1-bentene.

For example, polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene/propylene copolymer, ethylene/1-butene copolymer, propylene/1-butene copolymer, ethylene/vinyl acetate copolymer polymers, ethylene/acrylic acid ester copolymers, etc.

These may be crystalline or amorphous.

In addition, polyolefins containing carboxyl groups have C
A waxy polyolefin containing an OOH group and/or an acid anhydride group, which has a structure obtained by randomly copolymerizing a 1-olefin and an unsaturated carboxylic acid or its anhydride, or a polyolefin containing an unsaturated carboxylic acid or anhydride in a polyolefin wax. It has a structure in which the anhydride is grafted.

Examples of unsaturated carboxylic acids or anhydrides thereof include acrylic acid, methacrylic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, 5-norbornene-2,3-dicarboxylic acid, and anhydrides thereof.

For the stability of the aqueous dispersion, it is preferable to use a carboxyl group-containing polyolefin wax that has a lower molecular weight than the polyolefin used, for example, at 135°C.
The intrinsic viscosity [η] measured in decalin is at least 0.
It is preferable that they are separated by 2 or more.

As a carboxyl group-containing polyolefin wax,
η] is preferably from 0.05 to 1.0, and its acid value must be from 10 to 150, preferably from 30 to 100.

Here, the acid value is the number of potassium hydroxide required for neutralization per sample 11.

If a material with a low acid value is used, a stable dispersion will not be obtained.

Furthermore, if a material with too high [η] is used, it will be difficult to obtain a stable aqueous dispersion.

On the other hand, [η] of the polyolefin varies depending on the desired physical properties of the halogenated polyolefin, but is generally preferably in the range of 0.6 to 5.0.

As the salt of the carboxyl group-containing polyolefin wax, monovalent and polyvalent salts such as lithium salt, sodium salt, potassium salt, ammonium salt, calcium salt, and magnesium salt are used.

It is not necessary that all of the carboxyl groups of these be converted into salts, and some of them may remain in the form of free acids, acid anhydrides, or esters.

(2) In the case of a valent metal salt, it is preferable that the polyolefin contains 0.02 to 40 meq/g of metal, and in the case of a polyvalent metal salt, it is preferably contained in an amount of 0.01 to 1.0 meq/g.

The polyolefin of the present invention contains 1 to 30% by weight, preferably 5 to 25% by weight of the salt of the polyolefin wax.
It is necessary that the content be % by weight.

In other words, it is necessary to add the wax salt in the amount described above in order to keep the suspension stable during the halokenization reaction and to allow the reaction to proceed smoothly, but if it is added in too large a quantity, the physical properties of the product may be affected. It is not preferable to use it excessively as it may damage it.

In the present invention, in addition to blending a predetermined amount of the specific wax salt into the polyolefin, it is important to select the particle size and shape of the polyolefin.

That is, the particle size must be 0.1 to 20μ, preferably 1 to 10μ, and the particle shape must be substantially spherical.

Since the polyolefin has such properties as described above, uniform halogenation is possible, and aggregation of particles during the reaction can be prevented.

Determination as to whether the particle shape is spherical or measurement of the particle diameter can be easily carried out by taking a micrograph.

When halogenation is carried out using such a raw material, a suspension of spherical halide particles is obtained as a product.

If the particles are not spherical but have a flat or angular shape, they tend to aggregate as the chlorination progresses.

Furthermore, it is impossible to use a highly concentrated aqueous dispersion.

On the other hand, if the particle size is too large, the surface area is too small, making uniform halogenation difficult.

Further, if the particle size is smaller than 0.1μ, there is a strong tendency to agglomerate, so it is not preferable to use ultrafine powder.

For details on the method for producing the above-mentioned aqueous suspension of polyolefin containing spherical particles, see Japanese Patent Application No. 50-88857 (Japanese Unexamined Patent Publication No. 52-13539) and Japanese Patent Application No. 10559-1983.
No. 9 (Japanese Unexamined Patent Publication No. 52-29844).

Although conventional methods are known in which an aqueous suspension of polyolefin fine powder of about 0.1 to 10 μm is halogenated (for example, Japanese Patent Publication No. 15660/1983)
, these seem to use mechanically pulverized fine powder.

However, mechanically pulverized polyolefins do not have a spherical shape, are bulky, and have a wide particle size distribution, so it is difficult to make a highly concentrated aqueous suspension, and as halogenation progresses, agglomeration of particles is avoided. I can't do it.

The polyolefin concentration of the aqueous suspension used for halogenation is arbitrary, but is usually 5 to 55% by weight, preferably 25 to 45% by weight.

In particular, the ability to operate at high concentrations in the present invention is a major advantage over conventional methods.

In the present invention, halogenation means not only chlorination but also bromination, chlorosulfonation, and the like.

The reaction temperature is usually room temperature to 200°C, and a multistage method may be adopted in which the reaction temperature is changed during the reaction.

The reaction time varies depending on the degree of halogenation, reaction temperature, etc., but is usually about 1 to 10 hours.

As for chlorinated polyolefins, by chlorination, etc., it is possible to produce products suitable for use as synthetic rubbers, paints, or as compounding materials for resins such as polyvinyl chloride.

Example 1 Ethylene/1-butene copolymer (density 0.920, [η
)10. 80 parts by weight of SO, melting point 121°C) and maleic anhydride kraft polyethylene wax (density 0.930,
20 parts by weight of [η] 0.10, melting point 84°C, acid value 50.5) were melt-mixed and poured into a KOH aqueous solution to give an average particle size of 4.
7μ (1-5μ 82% by weight, 6-10μ 18% by weight
A 50% aqueous dispersion of spherical particles of ) was obtained.

1/2 equivalent of the maleic anhydride unit was a potassium salt.

Put 600g of this aqueous dispersion into a 1L reaction container, and
The temperature was raised to 0.degree. C., and chlorine gas was blown in at a rate of 100 P/hr while stirring.

In a 1-hour reaction, a chlorinated product with a chlorine content of 20% by weight,
Further, in the reaction for 2 hours, a chlorinated product with a chlorine content of 37% by weight was obtained.

In each reaction, no aggregation of particles was observed,
The product particles were also spherical.

The latter chlorinated product had a tensile strength of 123 kg/cm2 and an elongation of 500%.

The tensile strength of the raw material composition is 107 kg/cm2,
The elongation was 24%.

Example 2 In Example 1, the ratio of ethylene/1-butene copolymer to wax was 9:1, and the average particle size was 5.1μ (1 to 5μ).
An aqueous dispersion of 62% (62%, 38% 6-10μ) was used.

Further, maleic anhydride kraft polyethylene (density 0.930, [η] 0.2, melting point 84° C., acid value 50) was used as the wax.

Other than that, halogenation was carried out in the same manner as in Example 1.

The chlorine content was 12% by weight after 1 hour reaction, 31% by weight after 2 hours reaction, and 42% by weight after 4 hours reaction.
% chloride by weight was obtained.

The one with a chlorine content of 42% by weight was soluble in triclene and dichloromethane at room temperature, and in toluene-xylene at 80°C.

During the reaction, no particle aggregation was observed in any case.
All products were spherical particles.

Example 3 In Example 1, the ethylene/1-butene copolymer had an ethylene content of 92.3 mol%, a density of 0.891, [η
〕■． Chlorination was carried out in the same manner as in Example 1, except that the spherical particles in the dispersion had an average particle size of 2.8 μm (all in the range of 1 to 5).

A chlorinated product with a chlorine content of 22% by weight was obtained after one hour of reaction, and a chlorinated product with a chlorine content of 45% by weight after 4 hours of reaction.

The solubility of the latter chloride in the solvent was similar to that of Example 2.

In all cases, there was no aggregation of particles, and all the products were spherical particles.

In addition, in the reaction at 70°C, the chlorine content decreased to 18 after 2 hours of reaction.
A chlorinated product having a chlorine content of 33% by weight was obtained after 4 hours of reaction.

Claims (1)

[Claims] 1. Beating substantially spherical particles of polyolefin with a particle size of 0.1 to 20μ containing 1 to 30% by weight of a carboxyl group-containing polyolefin wax salt having an acid value of 10 to 150 in an aqueous medium. A method for producing a halogenated polyolefin, characterized by: