KR19990062775A - Method for producing antistatic resin composition and antistatic resin composition produced thereby - Google Patents

Abstract

The present invention prepares an antistatic agent mixture by mixing and stirring an anionic antistatic agent and a nonionic antistatic agent such as polyalkylene glycol in a paste or solidified form, such as an alkali metal alkylsulfonate, and in a extruder through a liquid pump. The present invention relates to a method for producing an antistatic resin composition composed of uniformly blending with a molten resin in an extruder and to continuously extruding the same, and an antistatic resin composition obtained thereby and its use as a master batch.

Description

Method for producing antistatic resin composition and antistatic resin composition prepared thereby

The present invention relates to a method for producing an antistatic resin composition and to an antistatic resin composition prepared accordingly. More specifically, the present invention relates to an antistatic agent mixture composed of an anionic antistatic agent and a nonionic antistatic agent such as polyalkylene glycol in paste or solidified form such as an alkali metal alkylsulfonate PMMA (polymethyl methacrylate). It relates to a method for producing an antistatic resin composition composed of blending and extruding a resin such as, and a method for producing an antistatic resin composition produced thereby.

In general, plastics are used as materials for products in various fields because of their lightness, colorful color and soft texture as well as excellent insulation. However, the good insulation of plastics sometimes leads to the problem of generating static electricity, which causes problems when used as the material of some products.

Although the cause of the generation of static electricity in plastics is not yet clear, it is generally frequently caused by surface contact such as friction, and it is known that the occurrence frequency of electrostatic charge is very high especially when the surface accumulates on the surface between insulators.

The generation of static electricity in plastic products not only shortens the lifespan of electronic and electrical products, but also becomes a dangerous factor for the safety of workers and workplaces, and development of plastic materials which prevents or suppresses the generation of static electricity has been desired.

Until now, as a method for reducing the generation of static electricity in plastics, the surface coating method of coating the surface of the plastic product with an antistatic agent by dipping or spraying, the melt blending method of blending the plastic material with the antistatic agent, and the hydrophilic monomer resin The copolymerization method etc. which introduce | transduce into a copolymerization or graft polymerization etc. are proposed.

The surface coating method has the advantage of being easy to impart antistatic property and simple process, but it is difficult to apply because a large immersion bath is required when manufacturing a large article by immersion method, and the coating may be damaged. In addition, there is a disadvantage in that an additional process of coating is required, and the copolymerization method can impart semi-permanent antistatic property and can produce a product having antistatic property by only molding the obtained antistatic polymer, but depending on the application It is difficult to apply variously, and the heat resistance is relatively weak, so that injection molding may be commercialized, but extrusion grade may not be commercialized.

The melt blending method has excellent flexibility according to the application, but suitable manufacturing conditions (processing temperature, composition ratio, shape and compatibility of resin and antistatic agent) according to the type and shape (shape and absorbency) of resin and antistatic agent are used. The disadvantage is that you have to find it.

Nevertheless, the melt blending method is mainly used at present, and the method for producing the antistatic resin composition of the present invention is also based on such a melt blending method.

In the melt blending method, the resin is melt blended with the antistatic agent and extruded at 210 ° C to 250 ° C or injected at 190 ° C to 210 ° C. Therefore, the antistatic agent used in the melt blending method should have excellent thermal stability, especially in the method by extrusion.

The antistatic agent for reducing or eliminating static electricity in plastics may be classified into an external coating type used by coating on the surface and an internal mixing type used by incorporating it into the polymer by a melt blending method as described above. , Cationic antistatic agents such as compounds containing quaternary ammonium salts, anionic antistatic agents such as phosphate salts or sulfonate salts, and nonionic antistatic agents such as polyalkylene glycols.

In general, the cationic antistatic agent has the best antistatic ability but the lowest thermal stability, and therefore cannot be used in the melt blending method. The nonionic antistatic agent has the best thermal stability, but the antistatic property is the lowest heat. Therefore, the nonionic antistatic agent should be mixed and used in excess of the polymer resin, for example, 10 parts by weight or more based on 100 parts by weight of the resin. There arises a disadvantage that the physical properties of the resulting antistatic polymer is greatly inhibited.

In contrast, anionic antistatic agents have an excellent balance of excellent antistatic properties and excellent thermal stability.

However, cationic and nonionic antistatic agents can be obtained in the liquid or powder state, while anionic antistatic agents are generally obtained in paste or solidified form, thereby making it difficult to quantitatively supply the antistatic agent in the blending process or Due to the high viscosity, it is difficult to supply to a conventional liquid pump or powder feeder and to blend the resin uniformly with the antistatic agent in the extruder.

In the case of a porous powdery resin such as PVC (polyvinyl chloride), powdery, liquid, paste, and granular antistatic agents can be mixed and extruded relatively easily regardless of the melt viscosity and thermal stability of the resin.

Similarly, nonporous granular or pelletized polymers such as PE (polyethylene) and PP (polypropylene) also have excellent thermal stability and low melt viscosity of the resin, which makes powder, liquid, paste and granular antistatic agents relatively easy. Can be mixed and extruded.

However, non-porous resins, such as PMMA (polymethyl methacrylate), have low thermal stability and high melt viscosity, so that when the antistatic agent is in liquid, powder, or granular form, it can be easily mixed and extruded with the antistatic agent. It cannot be easily mixed and extruded with the antistatic agent in paste or solidified state.

As described above, since the anionic antistatic agent which is relatively excellent in terms of antistatic property and manufacturing is mainly obtained in paste form or solidified state, it is difficult to supply quantitatively and in the case of paste form, it is difficult to adhere to the base wall of the mixer and blend easily. The disadvantage is that In addition, there is a risk of thermal decomposition when liquefied by using heat, and even when blended with granules or pellets such as PMMA or non-porous resin, it is difficult to supply quantitatively with a liquid pump, etc. This presents the disadvantage of making it difficult to evaluate the blended and added amount with the molten resin.

When the anionic antistatic agent in paste or solidified form is heated and used in liquid form, there is a risk of pyrolysis and color change as well as the viscosity does not drop to the extent that a liquid pump is used. Thus, the problem as described above still remains.

In particular, sodium alkylsulfonate used as an anionic antistatic agent has a black color when heated for liquefaction and does not significantly lower its viscosity, so it is almost impossible to use a sulfonate type antistatic agent such as sodium alkylsulfonate alone. impossible.

For this reason, anionic antistatic agents prepared in a liquid or powder state other than a paste or solidified state by adding a suitable process after the preparation or preparation of the anionic antistatic agent are commercially available, but are thus anionic prepared in a liquid or powder state. When antistatic agents are used, it is difficult to achieve satisfactory antistatic properties in the final product, and the types thereof are limited, so that it is difficult to obtain various products according to the use.

The prior art also aims only at compositions which exhibit antistatic properties and mainly use a method of dry blending resins and antistatic agents in a mixer, such as a Henschel mixer, but in such a method the added amount of antistatic agent is deposited on the wall of the mixer to give the correct amount. The antistatic agent was difficult to be introduced and was not absorbed by the nonporous resin, so it was often impossible to apply it to actual production, and it was also difficult to introduce a large amount of the antistatic agent to make a master batch.

The present inventors have studied to develop a novel method for melt blending anionic antistatic agents obtained in pastes or solidified forms which are excellent in antistatic properties but difficult to melt blend to nonporous and relatively high melt viscosity polymers such as PMMA. As a result, it has been found that the liquid mixture obtained by mixing with anionic antistatic agent obtained in a paste or solidified state and a generally nonionic antistatic agent can be fed to the extruder by a conventional liquid pump, and thus prepared The present invention was completed to find that the fed mixture can be uniformly blended and extruded with a nonporous polymer resin such as PMMA. In addition, according to this method, since the antistatic agent mixture is used in a liquid state and mixed with the resin, a large amount of the antistatic agent can be mixed, and the resin composition thus prepared can be used in a master batch.

Accordingly, the first object of the present invention relates to a method of preparing an antistatic resin composition, wherein the anionic antistatic agent and nonionic antistatic agent such as polyalkylene glycol in paste or solidified form, such as alkali metal alkyl sulfonate To obtain a liquid antistatic mixture, which is supplied in a suitable amount into the extruder through a liquid pump to uniformly mix with the molten resin and to extrude the resulting resin mixture.

According to the present invention, the above-mentioned anionic antistatic agents are generally obtained in paste or solidified state, and are used as they are without further processing to make them into liquid or powder state. Anionic antistatic agents are phosphates or sulfonates, preferably alkali metal alkylsulfonates, particularly preferably sodium dodecylsulfonate.

The nonionic antistatic agent is polyalkylene glycol, for example polyethylene glycol or polypropylene glycol, preferably polyethylene glycol. Its molecular weight is preferably 100 to 500.

The mixing ratio of the anionic antistatic agent and the nonionic antistatic agent may be in any ratio as long as it can be mixed or pumped with a liquid or liquid pump without being separated from each other, but generally 1: 1 to 1 A weight ratio of 9: is preferred. It is preferable that the liquid mixture obtained by mixing the anionic antistatic agent and the nonionic antistatic agent has a viscosity of about 500 cps.

The resin that can be used in the method of the present invention is not particularly limited. It is necessary or preferable to use the method of this invention are nonporous pellet-shaped resins which are hard to impart antistatic property by another method, and especially PMMA is mentioned.

A second object of the present invention is an antistatic resin composition prepared according to the method of the present invention.

The antistatic resin composition thus prepared may contain 0.5 to 10% by weight of the antistatic agent based on the total weight of the composition.

In this case, the antistatic resin composition according to the present invention having a relatively high content of an antistatic agent, for example, 10 to 20% by weight, may be further mixed with a resin composition containing no antistatic agent so as to have a low content of an antistatic agent. The antistatic resin composition which is 1-3 weight% can be manufactured. The resin composition used in this way is called a master batch, and becomes the basis for producing a large quantity of the resin composition to which antistatic property was provided.

Accordingly, a third object of the present invention relates to a method of using the master batch made according to the method of the present invention.

One of the characteristics of the present invention is liquid charging by mixing anionic antistatic agent (e.g. alkali metal alkylsulfonate) in paste or solidified form and nonionic antistatic agent (e.g. polyethylene glycol or polypropylene glycol) in liquid form. By preparing and using the inhibitor mixture, the disadvantages generated when used alone are improved to show an increased antistatic effect.

There is no restriction on the mixing method of the anionic antistatic agent and the nonionic antistatic agent, but generally, the mixture is stirred and stirred at a temperature between 30 ° C and 100 ° C. When the temperature at the time of mixing is 30 degrees C or less, there exists a tendency for the separation degree to not mix with each other, and when it is 100 degrees C or more, there exists a possibility of discoloration, forming a bubble.

As nonionic antistatic agents, mention may be made of polyethylene glycol. Polyethylene glycol has better thermal stability than other cationic or anionic antistatic agents but has a lower antistatic effect. Therefore, the antistatic effect is exhibited by adding 10 parts by weight or more, which is 5 times or more compared to the general amount of antistatic agent (0.2 to 2 parts by weight). However, when a large amount of polyethylene glycol is incorporated into the resin as described above, not only the surface of the resulting resin is slippery but also the heat resistance is lowered.

On the other hand, the alkali metal alkylsulfonate, an anionic antistatic agent, has excellent antistatic properties but is not only supplied to a high viscosity paste but may also be discolored in black. Therefore, there is a high risk of discoloration when using only alkali metal alkylsulfonate alone in transparent PMMA.

According to the method of the present invention, such a polyethylene glycol and an alkali metal alkylsulfonate are mixed to obtain a liquid mixture, which is quantitatively supplied into an extruder barrel by using a liquid pump to form a nonporous pellet or granule such as PMMA. By mixing with the phase resin and extruding, a uniform antistatic resin composition can be produced continuously without any such risk.

According to one variant of the method of the invention, the antistatic resin composition can of course also be used for injection molding, and thus the extruder can also be replaced by an injection machine.

The antistatic resin composition thus prepared is not only excellent in antistatic effect, but also hardly deteriorates in physical properties such as impact strength, flexural strength, flexural modulus, and tensile strength, thereby preparing various articles requiring antistatic properties. It is useful as a material.

In the following, the present invention is explained in more detail using non-limiting examples.

Example 1-3 and Comparative Example 1-3

Preparation of Resin Compositions and Sheets

Sodium dodecylsulfonate and polyethylene glycol (molecular weight 400) were mixed and stirred in a water bath of 50 ° C. to 200 ° C. in the weight ratio shown in Table 1 below to prepare a liquid antistatic mixture, and the viscosity of the mixed solution reached approximately 500 cps. In order to maintain flowability, the solution was metered into the extruder while maintaining at 80-90 ° C., and mixed with 100 parts by weight of PMMA. The blended mixture was extruded continuously in the form of sheets, pellets, granules and the like through an extruder.

exam

Sheet-shaped extrudate produced by Brabender Single Extruder T-Die is cut into 5 cm wide and 5 cm long, 23 ° C., 50% RH according to ASTM D 618-61. Condition at least 1 day under conditions. Using the sheet thus prepared as a test piece, the surface resistance was measured by a surface resistance measuring instrument (Ultra Resistance Meter, Adventest, Japan) in accordance with ASTM D 257. The results are shown in Table 1 below.

Example 1 Example 2 Comparative Example 1 Example 3 Comparative Example 2 Comparative Example 3 PMMA (HY-020) 100 100 100 100 100 100 Sodium alkylsulphonate One 5/3 0 1.5 3 0 Polyethylene glycol 2 10/3 0 1.5 0 10 Surface resistance (Ωsq) 7 × 10 ¹⁰ 3 × 10 ¹⁰ 1 × 10 ¹⁶ 3.2 × 10 ¹⁰ Cannot be manufactured 5 × 10 ¹³

Example 4

A master batch was prepared in the same manner as in Example 1, except that the antistatic agent content was 15 parts by weight based on the total resin composition.

8.2 parts by weight and 28.7 parts by weight of this master batch were blended with 100 parts by weight of raw material PMMA to prepare an antistatic resin composition having an antistatic agent content of 1 part by weight and 3 parts by weight, respectively.

These surface resistances (? / Square) were 2.0 × 10 ¹¹ and 1.1 × 10 ¹⁰ , respectively.

The method of the present invention provides a resin composition having excellent balance of antistatic property and thermal stability by using a mixture of anionic antistatic agent and nonionic antistatic agent in the production of antistatic resin composition, and the manufacturing process is simple.

Claims (8)

An anionic antistatic agent such as an alkali metal alkylsulfonate or a nonionic antistatic agent such as polyalkylene glycol and a solidified form are mixed and stirred to obtain a liquid antistatic mixture, which is appropriately supplied to the extruder through a liquid pump. A method for producing an antistatic resin composition comprising uniformly blending with molten resin in an extruder and extruding it continuously. The method according to claim 1, wherein the resin is PMMA (polymethyl methacrylate). A process according to claim 1 wherein the polyalkylene glycol is polyethylene glycol. The production method according to claim 1, 2 or 3, wherein the resin is in a pellet form. 4. Process according to claim 1, 2 or 3, characterized in that the alkali metal alkylsulfonate and polyalkylene glycol are 1: 1 to 1: 8-9. An antistatic resin composition prepared by the method according to any one of claims 1 to 5. A method characterized by using the antistatic resin composition according to claim 5 as a master batch. An antistatic agent composition comprising an alkali metal alkylsulfonate and polyethylene glycol in a ratio of 1: 1 to 1: 8-9.