JPS5834497B2 - Ethylene-vinyl ester - Google Patents

Description

Detailed Description of the Invention The present invention relates to ethylene-vinyl ester copolymer (hereinafter referred to as E
VE), and more specifically, it involves adding a coagulant to an emulsified aqueous dispersion containing EVE to produce EVE.
After coagulating, add an anti-blocking agent of 0.5 to 10 parts by weight (commonly) before or after dehydrating the coagulated product to a water content of 10 to 100 weight φ (based on the dry polymer, the same applies hereinafter). The present invention relates to an EVE powdering method, which comprises adding (hereinafter the same applies) to 100 parts by weight of a polymer, pulverizing and drying.

EVE is a synthetic resin that has been attracting attention in recent years because it is highly elastic, has excellent durability, and has good compatibility with other resins.

Conventionally, methods for producing EVE include bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization.
Obtaining a powder of VE is difficult because it fuses into lumps during drying, making it extremely difficult to handle, and even if these lumps are crushed, they become more flexible due to the frictional heat generated during the grinding process, making it even more difficult. .

Generally, the methods used to obtain powdered EVE include pelletizing it with an extruder or kneading it with rolls and rolling it into sheets, but the production costs are high and it is difficult to obtain particles with a small size. is not practical.

As a result of various studies on powdering EVE, the present inventors came up with a method that can easily powderize and obtain EVE powder with uniform particle size.

That is, the present invention has a melt viscosity of 5X103 poise or more, and the component composition is ethylene:vinyl ester-1:
When producing 10 to 200 meshes of dried and powdered copolymer from an emulsified aqueous dispersion containing an ethylene-vinyl ester copolymer having a ratio of 9 to 6:4, a coagulant is added to the aqueous dispersion. After coagulating the ethylene-vinyl ester copolymer, the coagulated product has a water content of 10 to 1
Before or after dehydration to 0.00% by weight (hereinafter simply referred to as ``parts''), 0.5 to 10 parts by weight (hereinafter simply referred to as ``parts'') of an anti-blocking agent is added to the coagulated material, and then pulverized. It is an object of the present invention to provide a method for pulverizing EVE, which comprises drying.

The purpose of the present invention is to make EVE produced in an aqueous medium into a powder that does not fuse even when stored for a long time.
The object is to provide EVE powder with uniform particle size.

The melt viscosity in the present invention is a load of 10 kg/i and a temperature of 160 kg/i.
℃, Tice 1mvt x 1mm, and in the present invention, it is usually measured using a Koka-type flow tester manufactured by Shimadzu Corporation.

The EVE of the present invention may be used as long as it has a melt viscosity of 5 x 10" poise or more, but it is preferably 5 x 10' to 5 x 106 poise due to the difficulty of manufacturing by emulsion polymerization and the deterioration of processability of the resulting resin. Usually used.

Incidentally, EVE having a melt viscosity of 5×10” poise or less is difficult to powder by the method of the present invention because it has a low molecular weight.

Further, the EVE in the present invention is obtained from ethylene and a vinyl ester, and examples of the vinyl ester in this case include vinyl acetate, vinyl propionate, vinyl pivalate, Veova 10, and the like.

Among these vinyl esters, vinyl acetate is most preferably used.

The EVE of the present invention may contain other vinyl monomers that can be polymerized with ethylene and vinyl esters, such as acrylic acid, mecracrylic acid, and esterified products thereof;
Examples include higher fatty acid vinyl ester, vinyl chloride, vinylidene chloride, styrene, acrylonitrile, acrylamide, and olefin compounds, and one or more of these monomers can be copolymerized or graft polymerized.

The EVE of the present invention usually has a polymerization ratio of ethylene and vinyl ester of 1:9 to 6:4.

Ethylene content (summed with vinyl ester) is 1ofb
The following EVEs are not preferred because they are difficult to powder and have poor flexibility.

In addition, the ethylene content (total with vinyl ester) is 60
% of EVE is substantially difficult to produce by emulsion polymerization method, and the EVE-containing aqueous dispersion used in the present invention is mainly synthesized by emulsion polymerization method. is meaningless.

However, it is of course possible to employ EVE with a vinyl ester content of 60% or more synthesized by a polymerization method other than the emulsion method, such as a solution polymerization method, if it can be emulsified by known means.

Coagulants used in the present invention include, for example, inorganic acids, organic acids, and inorganic salt electrolytes, and more specifically, hydrochloric acid, sulfuric acid, sodium chloride, ammonium chloride, potassium chloride,
These include aluminum chloride and aluminum sulfate.

The amount of coagulant is usually 0.5-5% (based on EVE solids).

Further, the anti-tack agent used in the present invention may be either inorganic or organic, but one that is in the form of a fine powder and is insoluble in water is used.

Examples of such anti-blocking agents include inorganic substances such as calcium carbonate, silica, fluoride, talc, magnesium oxide, and zinc oxide, fatty acid metal salts such as barium stearate, calcium stearate, and zinc stearate, stearic acid, stearic acid amide, Examples include organic substances such as polyethylene powder and wax.

The amount of this anti-blocking agent added is 0.5 to 10 parts per 100 parts of dry EVE.

If the amount of the anti-blocking agent added is less than 0.5 parts, the anti-stick effect will be impaired, and if it is more than 10 parts, the flexibility, which is a characteristic of EVE, especially the ethylene-vinyl acetate copolymer, will decrease, which is not preferable. .

The feature of the method of the present invention is that EVE is coagulated from an emulsified aqueous dispersion containing EVE using a coagulant, and the above-mentioned anti-blocking agent is added to the coagulated product, and when the coagulated product is crushed and dried, the water content of the coagulated product is 10 to 100%. Before or after dehydration (based on dry EVE), 0.5 to 10 parts (based on 100 parts dry EVE) of an antiblocking agent are added.

The antiblocking agent must be added after the EVE is coagulated, and it is not preferable to add the antiblocking agent before coagulation because a large amount of the antiblocking agent is required to obtain the antiblocking effect.

Moreover, the EVE coagulated material of the present invention has a water content of 10 to 1 before pulverization.
If the water content exceeds 100φ, coalescence will occur during drying after pulverization, and if the water content is 10 to 60φ (relative to dry EVE).
If the diameter is less than φ, frictional heat generated during pulverization may cause fusion, making it difficult to powderize.

In addition, if the water content is 10 to 100%, it is effective because the water absorbs the heat generated during pulverization, and the evaporation of appropriate water makes the pulverization easier without causing fusion or coalescence. be.

The coagulated material of the present invention is dehydrated as described above before being pulverized, and a centrifugal dehydration method is usually employed for dehydration.

Generally, when an emulsified aqueous dispersion aggregate of EVE is centrifugally dehydrated,
Agglomerated particles coalesce due to centrifugal force, and it is difficult to prevent coalescence even if an anti-blocking agent is added.

However, when an anti-blocking agent is added as in the present invention, whether the anti-blocking agent is added before or after dehydration, the water content of the EVE coagulum after dehydration and the amount of anti-blocking agent added are Due to this relationship, even if the EVE coagulum is coalesced immediately after dehydration, if it is pulverized, it is possible to obtain the particle size targeted by the present invention, that is, 10 to 200 mesh.

The water content of the EVE coagulate immediately after coagulation is about 200% (based on dry EVE).

EVE with a water content of 10 to 100φ containing an anti-blocking agent
The coagulum is then ground by a grinder.

The pulverizer used at this time grinds EVE coagulates at 10 to 200
Any pulverizer that can be pulverized to the size of a mesh may be used, such as a power mill (manufactured by Sanei Seisakusho Co., Ltd.), a turbo mill (manufactured by Turbo Kogyo Co., Ltd.), a super micron mill (manufactured by Paper Iron Works Co., Ltd.), etc. machine is valid.

In particular, a pulverizer such as a turbo mill is capable of pulverizing particles to a particle size even smaller than the particle size when agglomerated before dehydration, which is surprising.

Furthermore, the material pulverized by the pulverizer does not fuse when properly dried, and has good storage stability without coalescence or fusion even after long-term storage.

In general, when a pulverizer is not used, that is, when a pulverization process is not performed, the particle size of the coagulated product becomes large in normal agglomeration operations, and while washing, filtration, and dehydration are easy to operate, it is difficult to add a large amount of anti-blocking agent. However, particles smaller than the particle size of the aggregated particles cannot be obtained simply by drying.

In addition, in order to obtain particles with a small particle size, they must be agglomerated into particles with a small particle size during aggregation, which is cumbersome to operate, reduces the efficiency of operations such as washing, filtration, and dehydration, and causes time loss. growing.

According to the method of the present invention, it is possible to easily achieve a uniform particle size distribution of 10 to 2
00 mesh powder can be obtained industrially.

Further, the drying in the present invention is carried out by a conventional method, such as flash drying, stirring drying, fluidized bed drying, hot air drying, etc.

At this time, if the drying temperature is too high, it will cause fusion of the EVE particles, so it is usually preferable to carry out the drying at a temperature of 40 to 80°C.

The EVE powder obtained according to the present invention has a very fast drying speed, is easy to perform operations such as measuring and packaging, and can significantly streamline the manufacturing process.

The EVE powder according to the invention can be effectively used for the purpose of improving other resin properties, such as impact resistance.

Other resins include polyvinyl chloride, vinyl chloride copolymers, polystyrene, polyacetals, polycarbonates, and the like.

Furthermore, the powder is homogeneous and has excellent processability and workability.

In addition, the powdered EVE of the present invention can be used not only for blending with other resins, but also for fields that could not be processed because conventionally suitable powders could not be obtained, such as fluidized dipping, backing, hot melt processing, and powdered elastomers. This is of great industrial significance.

The present invention will be explained below using examples, but is not limited to the examples only.

Examples 1 to 3, Comparative Examples 1 to 3 The following raw materials were charged into an electromagnetic rotary autoclave having an internal volume of 201 cm.

Ion exchange water 6001 vinyl acetate
4000 colloidal palladium (0,
1φ aqueous solution) 20 ferric ammonium sulfate
0.02 Emal O (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 120 sodium lauryl sulfate) Hydroxyethyl cellulose 20 After blowing ethylene into the reaction vessel twice to remove air, the ethylene pressure was set to 75 kg/- and the mixture was heated to 40°C.

Next, a reaction was carried out while dropping a catalyst solution in which peracid power IJ 20.9 was dissolved in water 500.9 for 6 hours.

The resulting emulsified aqueous dispersion contained 39 φ of a copolymer having a melt viscosity of 5.5×10 5 poise, an ethylene content of 44 poise, and a vinyl acetate content of 56 poise.

2 kg of the aqueous dispersion was diluted with water to a concentration of 15 ml and heated at 50°C.
When 200 g of a 10% aluminum sulfate solution was added, an aggregate was obtained in which more than 25 of the total particles could pass through a 30-mesh wire gauze.

Next, suspensions of various anti-blocking agents shown in Table 1 dispersed in appropriate amounts of methanol were added, stirred for about 10 minutes, and then dehydrated using a centrifugal dehydrator to a water content as shown in Table 1.

The dehydrated product was pulverized using a Turbo Mill T-400 type pulverizer (manufactured by Turbo Kogyo Co., Ltd.) and dried using a 50°C hot air dryer. A storage stability test was conducted in which the degree of fusion was observed when the sample was left in a dryer at 40° C. for 24 hours under a load of 500 g.

The results are shown in Table 1.

Examples 4 to 6, Comparative Example 4 Polymerization was carried out in the same manner as in Example 1, except that 40.9 g of carbon tetrachloride was added during initial charging to the kettle.

The obtained emulsified aqueous dispersion had a melt viscosity of 7×103 poise, an ethylene content of 41%, and a vinyl acetate content of 59%.
It contained 39 parts of vinyl acetate copolymer.

2 kg of the aqueous dispersion was diluted with water to a concentration of 15%, and heated at 40°C.
When 200 g of a 10% calcium chloride solution was added, an aggregate was obtained in which about 10% of the total particles could pass through a 10-mesh wire mesh.

This was treated in the same manner as in Example 1, except that the type and amount of antiblocking agent was as shown in Table 2.

The results are shown in Table 2. Example 7 2 kg of the emulsified aqueous dispersion obtained in Example 1 was agglomerated and centrifugally dehydrated in the same manner as in Example 1, followed by barium stearate 24 kg.
A suspension prepared by dispersing 50 g in 60 g of methanol was added thereto, and further centrifugal dehydration was performed. The dehydrated product was fused into a plate shape and had a water content of 39 φ.

When this material is pulverized with a turbo mill under-400 type pulverizer, the water content becomes 30%, and when dried with hot air at 50°C, it becomes 30-50 mesh 93% and 50 mesh or more 7
A powder of uniform diameter consisting of φ was obtained.

This product did not fuse at all in the storage stability test.

Claims (1)

[Claims] From an emulsified aqueous dispersion comprising an ethylene-vinyl ester copolymer having a melt viscosity of 15 x 103 pounds or more and a component composition of ethylene:vinyl ester-1 = 9-6:4 in weight ratio. When producing 200 meshes of the dried and powdered copolymer, a coagulant is added to the aqueous dispersion to coagulate the ethylene-vinyl ester copolymer, and the coagulated product is mixed with a water content of 10 to 10. 100 weight buns (
Before or after dehydration (based on the dry copolymer), 0.5 to 10 parts by weight of an antiblocking agent (based on 100 parts by weight of the copolymer) is added to the coagulum, and then pulverized. A method for powderizing an ethylene-vinyl ester copolymer, which method comprises drying.