JPS60192762A - Electrically conductive molding material and production thereof - Google Patents

Abstract

PURPOSE:To produce an electrically conductive molding material which gives moldings having excellent electromagnetic wave-shielding properties, by mixing a natural pellet of a synthetic resin with a specified master pellet contg. a bundle of an electrically conductive long fiber filler. CONSTITUTION:A synthetic resin layer 3 is formed on the outer surface of a material 4 obtd. by bundling together 100-50,000 electrically conductive long fiber fillers 1 (e.g. metallic fibers or carbon fibers) having a surface coated with an organophosphorus compd. 2 of the formula [wherein X<1>, X<2> are each halogen, (cyclo)alkyl, aralkyl, aryl; m, n are each 0-3] such as 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide. The resulting material is cut in lengths to form a master pellet. 1pt.wt. said master pellet and 1-20pts.wt. natural pellet of a synthetic resin (which is the same as or well miscible with the resin of the master pellet) are blended together.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a highly reliable synthetic resin molded product in which a conductive filler can be uniformly dispersed without reducing the strength of the molded product, and which has an excellent electromagnetic shielding effect. The present invention relates to an SN molding material and a method for producing the same.

[Technical background of the invention and its problems] In recent years, the housings of electronic devices have been designed to protect electronic circuits from external interference radio waves and to prevent unnecessary radio waves generated from oscillation circuits from leaking to the outside. It is required that the body be made of electromagnetic shielding material. Examples of such electromagnetic shielding materials include metals and conductive synthetic resins, but while the former metals have excellent electromagnetic shielding effects, they have drawbacks such as being heavy, expensive, and having poor workability. However, the use of the latter conductive synthetic resin is becoming mainstream. Methods of imparting conductivity to synthetic resin include forming a conductive layer on the surface by applying conductive paint, spraying or plating metal after molding the synthetic resin, and adding carbon to the inside of the synthetic resin. There is an internal addition method in which a conductive filler such as metal powder or metal fiber is added and molded.

The method of forming a conductive layer on the surface of a synthetic resin molded product requires many steps and is not suitable for mass production, and also has the disadvantage that the conductive layer peels off after long-term use, so expectations are high for the internal addition method. It is being

However, the internal addition method also has the following problems.

However, in order to obtain the desired electromagnetic shielding effect, it is necessary to incorporate a large amount of conductive fillers such as carbon, metal powder, or metal fibers, which may result in poor dispersion and damage to the molded product. This had the disadvantage of reduced mechanical strength. Furthermore, when a synthetic resin is filled with metal or the like, there is a problem of accelerating deterioration of the synthetic resin. Some have a silane coupling layer provided on the conductive filler so as not to reduce the strength, but they have the drawback that the conductivity is significantly inhibited. Furthermore, metal fibers and highly flexible fiber fillers tend to form clumps when mixed alone, requiring pretreatment steps such as loosening. Furthermore, due to the differences in specific gravity and shape, it requires a high level of skill and skill to knead uniformly. Furthermore, when workers handle the filler material, the fibers tend to get stuck or touch the skin, causing physical pain such as pain and itching, and other environmental health problems are likely to occur. Therefore, it was desired that the molding material "A'IN" be able to be operated in a closed system in the shortest possible process, and that the shape of the filler remains constant (does not change).In other words, it is desired to have a large electromagnetic shielding effect. There has been a demand for the development of a conductive molding material that can be mixed uniformly with synthetic resins, is environmentally hygienic, and does not cause a decrease in the strength or conductivity of the synthetic resin.

[Object of the invention 1 The present invention has been made in view of the above-mentioned circumstances,
In addition to quantifying and stably supplying the form and quantity of conductive charging IU, it can be uniformly dispersed in synthetic resin, is environmentally hygienic, has a large electromagnetic shielding effect, has great mechanical strength, and is electrically The purpose of this invention is to provide a highly reliable conductive molding material with excellent properties and a method for producing the same.

[Invention 6! If main point 1: As a result of intensive research to achieve the above object, the present invention uses a conductive filler formed by integrally forming a synthetic resin layer on the surface of a metal fiber or the like having an organic phosphorus compound layer. It has been found that the above object can be achieved by this.

That is, the conductive molding material of the present invention is produced by integrally forming a synthetic resin layer on the surface of a bundle of long fibrous conductive fillers having an organic phosphorus compound layer on the surface, and cutting it into pellets at °C.
The main ingredients are master pellets and natural pellets made of pellet-shaped synthetic resin.

The manufacturing method of the present invention also includes a step of forming an organic phosphorus compound layer in which the bundled long fiber conductive core filler is immersed in an organic phosphorus compound solution, and a long fiber conductive A master pellet process in which a synthetic resin layer is coated and integrated on the surface of the plastic filler and cut into pellets.
and a mixing step of mixing the master pellets and natural pellets 1 to 1 made of pellet-shaped synthetic resin.

The organic compound used for forming the organic phosphorus compound layer of the present invention (in the formula, x' and x2 represent a halogen atom, an alkyl group, a cycloargyl group, an aralgyl group, or an aryl group, and m and n are integers of 0 to 3) is an organic phosphorus compound represented by J. This compound is, for example, 9,10-dihydro-9-oxa-10-small sphaphenanthrene-
10-oxide, 9.10-dihydro-9-phospha-
10-Aki→nophenanthrene-9-oxide, 9.1
0-dihydro-3-α,α'-dimethylbenzyl-
9-Bosphor 10-A xaphenanthrene-9-oxide, 9,10-dihydro-1,3-dichloro-〇-
Examples include small sulfur 10-'Aki→nophenanthrene-9 oxide, and these are used singly or as a mixture of two or more.

A metal layer such as long fiber shoe-shaped conductive material used in the present invention (materials include metal fibers such as copper, aluminum, iron, nickel, zinc, or alloys thereof), or copper, etc. Examples include inorganic fibers such as glass, carbon, and boron. The thinner these long fibers are, the better, and usually a bundle of ioo to 50,000 mv* fibers is used.

Examples of the synthetic resin used to coat the surface of the long-fiber conductive filler of the present invention include poly)stylene resin, ABS resin, polycarbonate resin, and modified PP○.
Examples include resin. The synthetic resin used here may be the same or the same as the synthetic resin used for natural pellets, and the third synthetic resin formed at the interface by mixing with the synthetic resin of natural pellets may have a reinforcing effect, i.e. Any blend polymer may be used. For example, if the natural pellets are made of styrene-based synthetic resin, the master pellets may contain modified PPO resin, polybutadiene resin, polyhydrene resin, etc.
・Good results can be obtained by using resin, etc. By doing so, the third synthetic resin formed at the interface has a reinforcing effect, and the characteristics of the molded product obtained by molding these molding materials can be improved.

Master pellets are produced by forming an organic phosphorus compound layer on the surface of a long fibrous conductive filler, then covering and integrating a synthetic resin layer on the bundled surface of the filler, and cutting the filler into pellets. The shape of the master bellet 1- may be circular or flat in cross section, and is not particularly limited to any particular shape.

Flat shapes can be easily obtained by pressing the pellets into a flat shape with a roll or the like before cutting into pellets, and then cutting the pellets. The natural pellets 1- may be made of a desired synthetic resin in the form of pellets, and may be the same or the same as the synthetic resin of the master pellet, or may be a different resin. Furthermore, the above-mentioned blend polymer may be formed. As for the mixing ratio of master pellets and natural pellets, it is usually desirable to mix 1 to 1 to 20 parts by weight of natural pellets to 1 part by weight of master pellets.

The conductive molding material of the present invention will be described below with reference to the drawings. Figure 1 is a cross-sectional view of the conductive filler used in the present invention (an organic phosphorus compound layer 2 is formed on the surface of the long fibrous conductive filler 1. Usually, the filler 1 is bundled and a liquid of the organic phosphorus compound is An organic phosphorus compound layer is formed on the surface of the filler material 1 by dipping and passing through it.

FIG. 2 is a sectional view of a master pellet, in which a large number of 11+ fibers with an organic phosphorus compound layer 2 formed on the surface of a filler 1 are bundled -C1, and a synthetic resin layer 3 is formed on the bundled surface. FIG. 3 shows a sketch of master pellets 1 to 1, in which there is a bundled filler material 4 in the center, the surface of which is coated with a synthetic resin layer 3, forming a master pellet 5. The master pellets produced usually have a circular cross section, but are not necessarily circular and may be flat, and are not particularly limited in shape.

To explain the manufacturing method of the master pellet 1- with reference to FIG. 4, long fibrous conductive fillers 10 are bundled and immersed in an organic phosphorus compound liquid 11 to form an organic phosphorus compound layer on the surface of the fillers 10. is formed, then die 1 of extruder 12
3 to form a coating 14 with a synthetic resin, and further cut 15 to form a master pellet 16. Continuously performing this manufacturing process results in a closed system and is economically advantageous. However, in some cases, it may not be a continuous manufacturing process.

The conductive molding material of the present invention has the thus obtained master pellets and natural pellets 1 to 1 as its main components, but other components may be added as necessary. The molding material of the present invention is used as a housing for electronic devices such as computers that require electromagnetic shielding.

[Examples of the Invention] Next, Examples of the present invention will be described, but the present invention is not limited to the Examples.

Example 300 long copper fibers with a diameter of 50 μm were bundled according to the composition not shown in Table 1, and after pickling and drying, 12,100 parts by weight of methi chloride was added to 5 parts by weight of HCA (organic phosphorus compound, trade name manufactured by Sanko Kagaku Co., Ltd.). An organic phosphorus compound layer was formed on the surface of the long steel U & fiber by immersing it in a mixed solution. The organic phosphorus compound layer thus obtained was integrated with a conductive filler by coating it with a thin layer of polystyrene resin (about 2 mm in diameter and cut into lengths of 5 mm to obtain master pellets).

A conductive molding material was produced by mechanically mixing 1 volume of this master pellet with 2 volumes of natural pellets of polystyrene resin. Injection molding was performed using the obtained molding material to obtain a molded article.

The mechanical and electrical properties and electromagnetic shielding effect of the molded product were measured and are shown in Table 1.

Comparative Example A conductive molding material was produced according to the composition shown in Table 1 in the same manner as in the Example. Using this molding material, the mechanical and electrical properties and electromagnetic shielding effect of a molded article (q) were measured in the same manner as in Examples, and the results are shown in Table 1.

As is clear from Table 1, the conductive molding material of the present invention has a large electromagnetic shielding effect and excellent mechanical and electrical properties.

[Effects of the Invention As explained above, according to the conductive molding material of the present invention,
By using a master pellet in which a synthetic resin layer is integrally formed on the surface of a bundle of long fibrous conductive fillers having an organic phosphorus compound layer, the conductive filler can be uniformly dispersed, which is good for environmental hygiene. It is possible to obtain a highly reliable molded product that has a large electromagnetic shielding effect, excellent mechanical and electrical properties, and does not reduce the strength of the synthetic resin.

Furthermore, according to the manufacturing method of the present invention, the conductive filler is not directly mixed with the synthetic resin, so the conductive filler is uniformly dispersed, and the process can be performed in a closed system, so there is no problem in terms of environmental hygiene. Furthermore, since the molding material is manufactured in a continuous process, the quality of the molding material remains constant.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the conductive filler used in the present invention, Figure 2 is a cross-sectional view of the conductive filler used in the present invention.
The figure is a cross-section E6i of the master pellet, FIG. 3 is a sketch of the master pellet, and FIG. 4 is a J diagram showing the method of manufacturing the master pellet according to the present invention. 1.10...Conductive filler, 2...Organic phosphorus compound layer, 3...Synthetic resin layer, 4...Bundled conductive filler, 5,16...Master pellet, 11.
・・Organic phosphorus compound liquid, 12・・Extruder, 13・
...Dice, 14...Coating formation, 15...Cutting Fig. 1 Fig. 3

Claims (1)

[Scope of Claims] 1. A master pellet obtained by forming a bundle of long fibrous conductive fillers having an organic phosphorus compound layer on the surface and integrally covering the surface with a synthetic resin layer and cutting the same into pellets; A conductive molding material whose main ingredient is natural pellets made of synthetic resin. 2 The organic phosphorus compound layer has the general formula (i), where x' and x2 represent a hegen atom, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group, and n+ and n are integers of 0 to 3. The conductive molding material according to claim 1, which is an organic phosphorus compound represented by: 3. The conductive molding material according to any one of claims 1 to 2, wherein the long fibrous conductive filler is a metal fiber or an inorganic fiber forming a metal layer. 4. The conductive molding material according to any one of claims 1 to 3, wherein the synthetic resin of the master pellets and the synthetic resin of the natural pellets form a blend polymer. 5. The conductive molding material according to any one of claims 1 to 3, wherein the synthetic resin of the master pellet and the synthetic resin of the natural pellet are the same synthetic resin. 6 An organic phosphorus compound layer forming step in which the bundled long fibrous conductive filler is immersed and passed through an organic phosphorus compound liquid, and a synthetic resin is applied to the surface of the long fibrous conductive filler following the organic phosphorus compound layer forming step. A master pellet step of forming a coating and integrating layers and cutting it into pellets, and natural pellets 1 to 1 consisting of the master pellet and a pellet-shaped synthetic resin.
A method for producing a conductive molding material, characterized by comprising a mixing step of mixing and mixing.