JPS61209238A - Production of carbon black-containing thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To obtain inductrially advantageously the titled composition containing highly and uniformly dispersed carbon black, having highly electrical conductivity, by dissolving a polar thermoplastic resin in a specific amount of a solvent having specified solubility, and blending the solution with an aqueous solution suspending carbon black. CONSTITUTION:Firstly, a solution of a polar thermoplastic resin and an aqueous solu tion suspending carbon black (suspended aqueous solution for short) are prepared by using a solvent which has <=10wt% solubility water in the solvent at a temperature when the resin solution is blended and stirred with the suspended aqueous solution, and <=20wt% solubility of the solvent in water as the solvent for dissolving the polar thermoplastic resin in such a way that the amount of the solvent W1g, the amount of water W2g for the suspended aqueous solution, and the solubility of the solvent in water S% satisfy the equation 40/S>=W2/W1. Then, the solution of the polar plastic resin is blended and stirred with the suspended aqueous solution so that the resin is not coagulated and precipitated from the solvent layer, to give a double layer mixed solution of a resin solution having uniformly dispersed carbon black and water. Finally, the solution is dehydrated, the solvent is removed, and the solid component is dried, to give the aimed composition.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for producing a resin composition comprising carbon black and a polar thermoplastic resin. The present invention relates to a method for producing a thermoplastic resin composition having polarity.

(Prior Art) It is generally known that carbon black is added to various thermoplastic resins to color the resin or to impart conductivity to the resin. When manufacturing a conductive carbon black-containing thermoplastic resin composition by blending the conductive carbon black, it is usually manufactured by a method of mechanically kneading the carbon black and the resin using a kneading machine such as a Nigu, Banbury mixer, or mixing roll. However, in such mechanical cross-wiring methods, undispersed carbon black lumps tend to remain in the cross-wire material, making it difficult to obtain a resin composition in which carbon black is uniformly dispersed, or the shear stress during cross-crossing tends to cause the carbon black to become undispersed. There were drawbacks such as the stractures being destroyed and the electrical conductivity of carbon black being reduced.

Additionally, some types of carbon black have a stock char that is difficult to break even when kneaded with other materials. A decrease in conductivity due to char destruction is unavoidable.

For these reasons, as a method for preventing the destruction of stock char, it is recommended to use a solution in which a thermoplastic resin or a nydistomer is dissolved and carbon black, as disclosed in the Japanese Patent Publication No. 2003-2013, YT, I-R Publication, or the Japanese Patent Publication No. Sho Go-RTR Dak. A method has been proposed in which a carbon black-containing thermoplastic resin composition is obtained by mixing carbon black with an aqueous dispersion solution.

(Problems to be Solved by the Invention) However, when carbon black is blended into a highly polar thermoplastic resin such as polyvinyl chloride using this method, a resin composition in which carbon black is uniformly dispersed cannot be obtained. I can't get it.

This is because the solvents that dissolve polar thermoplastic resins are generally highly polar and highly soluble in water, such as tetrahydrofuran and methyl ethyl ketone. This is because when mixed with carbon black, water is mixed into the solvent, the solubility of the resin in the solvent layer decreases, and the resin coagulates and precipitates from the solvent layer without carbon black being uniformly dispersed.

(Means for Solving the Problems) Therefore, as a result of intensive studies to solve these problems, the present inventors have found that thermoplastic resins with high polarity can be used by using a specific amount of a solvent with a specific solubility. The inventors have discovered that a resin composition in which the resin does not coagulate and precipitate from the solvent layer and in which carbon black is uniformly dispersed can be obtained even if the resin composition is dispersed uniformly, and the present invention has been achieved.

That is, an object of the present invention is to provide a method for producing a highly conductive carbon black-containing thermoplastic resin composition in which carbon black is uniformly dispersed using a highly polar thermoplastic resin, and in particular, it is an object of the present invention to provide a method for producing a highly conductive carbon black-containing thermoplastic resin composition in which carbon black is uniformly dispersed. It is an object of the present invention to provide a method for producing a resin composition with a high carbon black content, so-called a thermoplastic resin master patch with a high carbon black content.

The purpose is to mix and stir the solvent in which the thermoplastic resin is dissolved and the carbon black suspended aqueous solution, to transfer the carbon black from the water layer to the solvent layer, and then to separate the resin containing carbon black from the liquid phase. In the method for producing a thermoplastic resin composition containing carbon black, a polar thermoplastic resin is used as the thermoplastic resin, the polar thermoplastic resin is dissolved, and the solubility of water in the solvent at the temperature during the mixing and stirring is 10% by weight. - A resin solution is prepared by mixing the polar thermoplastic resin with a solvent whose solubility in water is less than 10% by weight,
The amount of solvent used at that time W, (fi and the amount of water used to make the carbon black suspension aqueous solution 94M, (fi
9 and the solubility S (wt%) of the solvent in water, the amount of solvent and the amount of water are determined so as to satisfy the relational expression: II O/8≧W, /W, and the resin solution and carbon black suspension aqueous solution are prepared. are prepared separately, and then the resulting resin solution and carbon black suspended aqueous solution are mixed and stirred to prevent the resin from coagulating and precipitating to form a homogeneous solvent layer and water layer in which carbon black is evenly dispersed. This is achieved by obtaining a mixed solution, dehydrating and removing solvent from the core solution to obtain a resin composition containing carbon black, and then drying the resin composition.

The present invention will be explained in detail below.

Invention Fci? The polar thermoplastic resin referred to herein refers to a thermoplastic resin whose solubility coefficient δ(eat/cC)% is at least larger than Q, and may be any thermoplastic resin that satisfies this condition. Specifically, polyvinyl chloride-based thermoplastic resins in which vinyl chloride is a substantial component and seven or more other monomers are copolymerized, such as polyvinyl chloride and vinyl chloride-vinyl acetate copolymer, are preferably used. .

Examples of carbon black include channel black, acetylene black, furnace black, and by-products produced when partially oxidized CO gas, H, and gas are produced from heavy oil, ethylene bottom oil, etc. in the presence of oxygen and water vapor. Carbon black, and furthermore, carbon black which has a high specific surface area by subjecting these carbon blacks to an activation treatment using water vapor, CO, etc., can also be used. Especially those with a large specific surface area or a large DBP absorption amount.
It is preferable to use so-called conductive carbon black, specifically having a specific surface area of 17y or more or a DBP absorption of 1! Omt//θθ? It is preferable to use the above carbon black.

The amount of carbon black to be blended is preferably 10 to 0 parts by weight per 100 parts by weight of the polar thermoplastic resin, and if the amount is less than 10 parts by weight, the resulting resin composition will be sufficiently conductive. If the amount exceeds 5 parts by weight, the resulting resin composition will not have sufficient strength, which is not preferable.

The solvent is one that dissolves the polar thermoplastic resin, and the solubility of water in the solvent at the temperature at which the resin solution and the carbon black suspension aqueous solution described below are mixed and stirred is as low as IO weight. It is preferable to use methylene, methyl in butyl ketone, etc. whose solubility in water is 20. In this case, if a solvent is used in which the solubility of water in the solvent exceeds IO weight, a large amount of water will be mixed with the solvent, reducing the ability of the solvent to dissolve the resin, and the solubility of the solvent in water will exceed 20% by weight. When a solvent is used, a large amount of solvent dissolves in water, reducing the volume of the solvent layer.
Even if K is used, a part of the resin will precipitate from the solvent layer, which is not preferable.

Next, a resin solution in which a polar thermoplastic resin is dissolved is prepared using such a solvent, and the amount of solvent used is closely related to the amount of water used when preparing an aqueous suspension of carbon black.

That is, the amount of solvent used w, (51) and the amount of water wt (s
Solvent amount and water tt-determined so that ao7S≧W, /W, between Q and the solubility of the solution in water S (heavy corrosion) at the temperature during mixing and stirring of the resin solution and the carbon black suspension aqueous solution. It is important to do so.

If the above relational expression is not satisfied, a large amount of solvent will dissolve into the water layer, which will reduce the volume of the solvent layer and cause the dissolved resin to coagulate and precipitate, which is not preferable.

A resin solution and an aqueous suspension of carbon black are prepared separately using the amount of solvent and water that are appropriately selected within the range that satisfies this relational expression.

These solutions can be prepared by known methods, but especially when preparing an aqueous suspension of carbon black, it is necessary to uniformly disperse the carbon black while applying a high shearing force using a dispersing machine such as a colloid mill type.

Next, the obtained resin solution and carbon black suspension aqueous solution may be mixed and stirred by a conventional method, but specifically, a batch or continuous mixing method using a mixing tank equipped with a stirrer, or a sufficient mixing method may be used. This can also be carried out by a pipe mixing method in which the resin solution and carbon black suspended aqueous solution are continuously supplied into a pipe having a structure that allows mixing.

Note that the mutual solubility of the resin solvent and water usually decreases as the temperature increases, and the solubility of the resin in the solvent increases, so it is preferable to mix and stir the resin solution and carbon black suspension at as high a temperature as possible. .

By this mixing and stirring operation, the carbon black uniformly dispersed in the water layer is transferred to the solvent layer, and the carbon black is uniformly dispersed to obtain a mixed solution consisting of two layers of the resin solution and water. At that time, it is important to perform a mixing and stirring operation so that the resin does not solidify and precipitate from the solvent layer, and as long as the above W*/W1 value is not exceeded during mixing, there are no particular limitations on the addition order or mixing method, but it is preferable. It is preferable to gradually add an aqueous suspension of carbon black to the resin solution.

In order to obtain a resin composition containing Cicabon Plaque from the obtained mixed solution, methods such as distillation removal of the solvent and water by steam distillation, or addition of a solvent that warms up with the solvent but does not dissolve the resin are used. coagulate and precipitate the resin composition,
Separate from the liquid phase. The obtained resin composition is then dried to obtain a carbon black-containing thermoplastic resin composition.

In addition, in the present invention, soluble additives such as plasticizers or stabilizers are dissolved in the resin solution, or various additives in the form of fine particles insoluble in water and solvent are dispersed in the aqueous suspension of carbon black. It can be blended into the resulting resin composition.

(Effects) The resin composition of the present invention obtained in this way can be kneaded with another synthetic resin (base resin) and used as a masterbatch to make the base resin contain CB, or! ! You can also mold it.

Generally, mixing of masterbatch and base resin is done by blending the two in an appropriate ratio, heating to 777~-ZOC to melt the resin, and using an open roll mill, extruder, pan/IJ-mixer, etc. At that time, if the resin composition of the present invention is used as a masterbatch, not only will there be no scattering of CB and a desired amount of CB can be blended into the base resin in a short crosstalk time, but also Compared to conventional resin compositions, it is easier to blend and incorporate into the base resin, and furthermore, it is possible to improve the dispersibility of CB.

Therefore, in the blending of CB and thermoplastic resin, the present invention provides
It is possible to provide a composition in which CB is highly uniformly dispersed in a wide range of content, which is extremely industrially advantageous.

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

Example-l Polyvinyl chloride Vinyryoku KR-boo (trademark of Mitsubishi Monnant Chemical Vinyl Co., Ltd., δ value 9.ri (eax/cc) 3A)
was dissolved in cyclohexanone at room temperature to a concentration i.

A weighty resin solution was made. On the other hand, Ketschen Black GC (trademark of Akzochemy Co., Ltd., specific surface area l 00WX/l
, DIP absorption amount J! Oad/f) was added to warm water at room temperature and dispersed using a homomixer at 1a000 rpm for 20 minutes to prepare a carbon black suspension aqueous solution having a weight concentration of 2%.

Put 1000 parts by weight of the resin solution into a mixing tank, and add the carbon black suspension aqueous solution 1-S while stirring at room temperature.
Parts by weight of O were gradually added, and after the entire amount was added, the mixture was vigorously stirred for a further minute, and then allowed to stand still. The standing liquid was separated into two layers, and virtually all of the carbon black had migrated to the solvent layer.
A mixed solution consisting of two layers of water and a cyclohexanone solution of polyvinyl chloride in which carbon black was uniformly dispersed without any coagulum was obtained. This cyclohexanone layer was dropped into 10C hot water under reduced pressure and stirred to distill out cyclohexanone together with water vapor. When the cyclohexanone was removed, a black polyvinyl chloride resin composition containing solid carbon black was obtained. This solid material was separated from the aqueous layer, pulverized, and dried under reduced pressure to obtain a carbon black-containing thermoplastic resin composition.

Example - Acetylene black electrified acetylene (Denki Kagaku Kogyo Co., Ltd. trademark, specific surface area 6/??//) D as cocarbon black
A polyvinyl chloride resin composition containing carbon black was obtained in the same manner as in Example 1 except that BP absorption amount d/100f) was used.

Comparative Example 1 1000 parts by weight of the resin solution used in Example 1 and 5000 parts by weight of an aqueous suspension of carbon black having a carbon black weight concentration of 00S% were mixed and stirred at room temperature to obtain a mixed solution.

When this mixed solution was left to stand after mixing, it separated into two layers, and the carbon black had migrated to the cyclohexanone layer, but a part of the coagulated polyvinyl chloride resin was precipitated in the cyclohexanone layer. Including this coagulated material, the solvent layer was prepared in Example-1.
In the same manner as above, it was dropped into heated water under reduced pressure to remove the solvent, solidify, separate in an oven, and dry to obtain a carbon black-containing thermoplastic resin.

Comparative Example - Using N,N-dimethylformamide as a co-solvent and using the same resin as in Example 7, a resin solution with a ratio of resin concentration/θ weight was prepared. When this resin solution and the carbon black suspension aqueous solution of Example 7 were mixed and stirred, a white coagulated resin was produced, and the solution did not separate into two layers. The entire amount of the solution containing this coagulated material was poured into hot water under reduced pressure in the same manner as in Example 7 to remove the solvent and obtain a resin composition.However, the solvent was not incorporated into the resin composition in the removed solution. There was a large amount of floating carbon black.

Comparative Example-3 Using a high-volume Z CC kneader, the polyvinyl chloride resin 60? The carbon black used in Example-7 was charged into the above kneader and masticated between θ?
After adding and kneading for several minutes, a polyvinyl chloride resin composition containing carbon black was obtained.

Comparative Example - A carbon black-blended polyvinyl chloride resin composition prepared with carbon black-blended polyvinyl chloride in the same manner as in Comparative Example-3 except that the carbon black used in Example-C was used as carbon black was prepared using the following method. The volume resistivity value (Ω・ctn) was measured and the results are shown in Table 1.
It was shown to. Table 1 also shows the mutual solubility of the solvents and water used in the Examples and Comparative Examples.

Volume resistivity measurement method: A polyvinyl chloride resin composition containing carbon black is pulverized, and a mixing roll having two rolls with a diameter of q inches is used to pulverize the polyvinyl chloride resin composition at a temperature of /! 3 to 4 pieces of the pulverized composition with an OC roll gap of 2 m! A sheet-like resin composition was obtained by passing through a rotating roll.

The obtained sheet-like resin composition was heated to a temperature of 1°C and a pressure of 00°C.
Pressure was applied at kp/a/l for 1 minute and 15 minutes to prepare a resin composition test piece (too x too x ~ 3IlII) ft with a thickness of 2 to 3 ft. The volume resistivity was calculated by placing the test piece in a specific resistivity measuring device, measuring the resistance value of the test piece in an atmosphere with 60 degrees of humidity and SC1, and calculating from this according to the following formula.

S: Electrode area of specific resistivity measuring device (CrlDt: Thickness of test piece crn)

Claims (2)

[Claims] (1) Carbon black in which a solvent in which a thermoplastic resin is dissolved and an aqueous suspension of carbon black are mixed and stirred to transfer the carbon black from the water layer to the solvent layer, and then the resin containing carbon black is separated from the liquid phase. In the method for producing a blended thermoplastic resin composition, a polar thermoplastic resin is used as the thermoplastic resin, the polar thermoplastic resin is dissolved, and the solubility of water in the solvent at the temperature during the mixing and stirring is 10% by weight or less. A resin solution is prepared by mixing the polar thermoplastic resin with a solvent whose solubility in water is 20% by weight or less, and the amount of solvent W_1 (g) used at that time and the carbon black suspension aqueous solution. 40/S≧W_
A resin solution and a carbon black suspension aqueous solution are prepared separately by determining the amount of solvent and water so as to satisfy the relational expression 2/W_1, and then the resin solution and the carbon black suspension aqueous solution obtained are mixed. After mixing and stirring to prevent coagulation and precipitation from the solvent layer to obtain a mixed solution consisting of two layers of a homogeneous resin solution and water in which carbon black is evenly dispersed, the solution is dehydrated and solvent removed to obtain carbon black. A method for producing a thermoplastic resin composition containing carbon black, which comprises obtaining a resin composition containing carbon black, and then drying the resin composition. (2) The method according to claim 1, characterized in that the aqueous suspension of carbon black is prepared such that the carbon black is present in an amount of 10 to 80 parts by weight based on 100 parts by weight of the polar thermoplastic resin.