JPS60262855A - Production of electromagnetic wave shielding resin - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic resin having improved moldability and excellent electromagnetic wave shielding properties, by interposing a metallic fiber between thermoplastic resin sheets, molding them by heating, cutting the molding into pellets and blending the pellets with a thermoplastic resin. CONSTITUTION:A metallic fiber having a fiber diameter of pref. 4-20mu is interposed between thermoplastic resin sheets and the laminate is molded by heating. The resulting molding is cut into pellets, which are blended with a thermoplastic resin, pref. polypropylene to obtain an electromagnetic wave shielding resin. The metallic fiber is used in a quantity of pref. 80-120pts.wt. per 100pts.wt. thermoplastic resin. Pref. the pellet should have nearly the same size as that of the thermoplastic resin pellet from the viewpoint of excellent moldability, and is to be cut into such a length that the metallic fiber has a length of 1-10mm..

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a resin with excellent electromagnetic shielding properties, and in particular improves moldability when filling and molding conductive metal fibers into a thermoplastic resin, thereby improving electromagnetic shielding properties. Concerning methods for producing excellent resins.

Generally speaking, the manufacturing method of so-called electromagnetic shielding resin molded products (housings) is to fill a thermoplastic resin with a conductive filler and then mold it, or to make a thermoplastic resin molded product. A method of forming conductive 1- on the surface of the substrate is used. Among them, the former method of filling a thermoplastic resin with a conductive filler eliminates the problem of peeling of the conductive layer, which is a concern with molded products obtained by the latter method of forming a conductive layer on the surface of the resin molded product. It also has the advantage of not requiring secondary processing after molding. Conventionally,
Carbon particles and carbon fibers have generally been used as the conductive fillers described above, but recently metal fibers have also come to be used as materials with excellent conductivity. However, in the former method, when using small metal fibers with a fiber diameter of 3071 m or less, the metal fibers become bulky in the thermoplastic resin when wrinkles necessary to exhibit the desired electromagnetic shielding properties are added. Therefore, when the metal fibers are then subjected to molding using general methods such as injection molding or extrusion molding, the metal fibers are dispersed in the resin in the form of powder or unevenly distributed in the form of flocs, resulting in decreased fluidity and dispersibility. [C] The moldability becomes extremely poor, or in some cases, it becomes impossible to mold. In addition, the obtained molded product has problems such as poor electromagnetic shielding properties such as increased volume resistivity, and lack of synergistic effects with other additives, such as flame retardants.

The present inventors have found that when using metal fibers in combination with a conductive filler, they improve the dispersibility and moldability of the metal fibers in hot plastic ladle tallow, while impairing the effects of other additives. Therefore, we conducted extensive research on a method for producing thermoplastic resin with excellent electromagnetic shielding properties. As a result, by producing pellets containing metal fibers in advance and filling the pellets with hot iJ rice grain resin, the above-mentioned tll'
It was discovered that I20 could be solved, and the present invention was completed.

That is, the present invention involves sandwiching metal fibers between thermoplastic resin sheets.
n Heat molding [Cutting the obtained molded product into pellet shapes (),
This is a method for producing a sli shielding resin, which is characterized in that the pellets are filled with a transparent resin.

The material, shape, etc. of the metal fibers used herein are not particularly limited, and various types may be used. For example, material and number 1 are iron, austenitic stainless steel, copper,
There is aluminum. In addition, the shape may be appropriately selected depending on the type of resin, molding conditions, etc., but in the present invention, short wires 1a (sliver, chop) cut from continuous fibers (tow) to about 50 to 10 mm, or slivers shaped like cotton (web)
You can use any of the following. These metal fibers preferably have a fiber diameter of about 11 to 206 m.

The greatest feature of the present invention is that the metal fibers as described above are heated [h].
(After being sandwiched between plastic resin sheets and heat-formed, the molded product is cut into a certain size to obtain pellets, and then the pellets are filled in 1 (il J plastic resin). Improved moldability with thermoplastic resin in which metal fibers are well dispersed [] Prevents deterioration of physical properties of molded products
-C can provide extremely excellent electromagnetic shielding properties. Conventionally, there is a method of bundling a plurality of metal fibers using a sizing agent and filling them with thermoplastic material, but in the present invention, only 1 ton of metal wire is sandwiched between sheets, and the drying step in the method using a sizing agent is is not needed, and T is extremely simplified.

The thermoplastic resin used in the present invention includes polyolefins such as polyethylene, polypropylene, and polybutene; styrene-based resins such as polystyrene, AS resin (acrylonitrile-styrene copolymer), ABS resin (acrylonitrile-butadiene copolymer), etc. Polymer; nylon 61,
Examples include homopolymers such as polyamides such as nylon 6.6; halogen-containing polymers such as polyvinyl chloride and chlorinated polypropylene; and copolymers thereof, which may be used alone or in the form of a mixture. Particularly preferred is polypropylene.
It is often used.

The method of forming the above-mentioned thermoplastic resin into a sheet is not particularly limited, and for example, calendering, extrusion molding, T-die method, etc. are used. In this specification, the term "sheet" refers to a sheet-like object, and is a concept that includes not only a sheet in the strict sense of one corner but also a film.

The amount of metal fibers sandwiched between thermoplastic resin sheets is generally 50 to 150 parts by weight, preferably 80 to 120 parts by weight, per 100 parts of thermoplastic resin. , production efficiency decreases due to the large amount of resin required;
If the amount is too large, moldability will be low. Molding is generally 1
A method of press molding at a temperature of fiO to 350°C or a lamination method is used. The molded product thus obtained is cut into pellet shapes using a cutter or the like. At this time, the size of the pellet is preferably about the same size as the pellet of the thermoplastic resin to be filled, because it has excellent moldability, and it is preferable to cut the metal fiber so that it has a length of h months to 101 IIR+. Note that it is preferable to use the same type of thermoplastic resin for forming the sheet and for filling the pellet, in order to prevent deterioration in moldability and physical properties of the molded product.

Examples of methods for filling and molding pellets in thermoplastic resin include mixing the pellets and thermoplastic resin using a ζ-tumbler blender, ■-type blender, Henschel mixer, ribbon mixer, etc., and then extruding the mixture. It is not particularly limited.

In this case, the filling tag of the pellet is preferably 8 to 40 parts by weight per 100 parts by weight of the thermoplastic resin.

In addition to these ingredients, conventionally known flame retardants, stabilizers, colorants, antistatic agents, lubricants, nucleating agents, various fillers,
Glass, various strength/embrying agents, etc. may be added. In particular, inorganic ammonium salts, E# antimony, aromatic compounds in which bromine is directly bonded to the benzene nucleus (excluding compounds in which bromine is bonded to the side chain), or aliphatic bromine compounds having a triazine ring, as mentioned above. The molded product obtained by filling the pellet together with polypropylene resin has a flame retardant rating of 1! Extremely excellent as a magnetic shielding material.

Example 1゜Diameter + (17+ stainless steel laminating machine:
Using a single-layer tri-laminator), the weight ratio of
After creating a laminated sheet by heating and forming at 210℃, cut it vertically into 5III with a cutter.
+1 Cut into 41 dice shapes to make pellets. This pellet 20#l$1% and polypropylene pellet (
The mixture was mixed with MI=180% by using a blender with a tumbler, and pellets were prepared by using a -screw extruder.

From the obtained pellet, the length is 20 mm, the width is 20 mm, and the thickness is 2.
A test piece of mm was prepared and the volume resistivity value was measured: (2×10 ohms).

Comparative example! .

The same stainless steel tow as in Example 1 was cut into 411I11 pieces, 10 weight percent of the stainless steel tow and no weight percent of polypropylene pellets (MI=q) were mixed using a tumbler blender, and the pellets were made using a -shaft extruder. Created.

Hereinafter, the volume resistivity (-) was measured using the same method as in the example, and it was found to be 4.FiX10 ohms.

Example 2゜Team 1. A pellet was prepared in exactly the same manner as in Example 1 except that (1 mm polyethylene sheet and polyethylene sheet) (MI=4.) was used, and the volume resistivity of the pellet was measured.2. lX1-Kame0 ohm.

Comparison VA2゜Example 2 instead of polypropylene pellet of Comparative Example 1
Comparative Example 1 except that the same polyethylene pellet was used.
A pellet was prepared using the same method as above.The volume resistivity of the pellet was measured: 3°6×0.

Example 3 Stainless steelware with a diameter of 8/I was molded using a compression molding machine (5-ton automatic press molding 11) to form 300 x 30 (1
mI11. Thickness] -: (Put it between the polypropylene sheets of till so that the weight ratio is 1:1,
After creating a laminated sheet by heating and forming at C, the sheet is twisted and rolled lengthwise. It was cut into dice-shaped pieces with a width of 4 mm and a novelette.

This pellet 15% heavy weight and polypropylene (M1=9)
Pellets) 85 weight 11% are mixed using a ■ type blender,
- The pellets were made using a screw extruder.

M: Hold the cut bellet vertically 20IIll11. Width 20m
A test piece with a thickness of 2 mm was prepared, and the volume resistance value was measured ()-1, and it was found to be 4.3 x 10 ohms.

Comparative Example 3 The same stainless steel web as in Example 3 was cut into 4 pieces, and 7.5% by weight of the stainless steel ware and polypropylene (MI=
9) Pellets were mixed using a type blender, and pellets were made using a -screw extruder.

The volume resistivity value was measured in the same manner as in Example 3 and found to be 2.6×10 ohms.

Example 4 A) (S sheet and ARS for general molding) with a thickness of 1.3 mm
The volume resistivity value was measured in the same manner as in Example 3 except for using pellets], RX] (1 ohm Comparative example 4゜A Comparative example except for using BS pellets of Example 4:)
The volume resistivity value was measured using the same method as 8.6X.
]O ohm.

Implementation f9Ilf5° Brass fiber sliver with a diameter of 4μ was used using a laminating machine;
By sandwiching between 9x50μ polypropylene films at a weight ratio of 2:3 and heat forming,
Create a laminated film and use a cutter to cut it vertically 4III111
It was cut into dice-like pieces with a width of 3 ms+ to form pellets.

10% by weight of this pellet and 90% by weight of M+9 polypropylene powder were mixed using a type tumbler.

201mm vertically by 1 pellet. Horizontal 201I11,
A test piece of Atsushi 2 III 11 was made and the volume resistivity was measured 1. The value was 11.9XIO oh 11.

Comparative Example 5 The same brass fiber sliver as in Example 5 was cut by a 1 m line, and the sliver was directly mixed with the same polypropylene powder as in Example 5 in the same proportion and method as in Example 5 to prepare pellets.

The volume resistivity value of the obtained pellet was measured in the same manner as in Example 5. Its value was 2.3 x 10 oats.

Example 6 Example 5 except that a vinyl chloride film of ゜j9SFiO)t and a vinyl chloride powder with a degree of polymerization of 800 were used.
The same method [) was carried out to measure the volume resistivity value.

The diameter of the child was 2.9X1 (1 ohm).

Comparative Example 6゜The same brass fiber sliver as in Example 6 was cut into 3iII11 pieces, and the sliver was directly mixed with vinyl chloride powder in the same proportion as on the day of Example to make pellets.1. Ta.

The volume resistivity (-) was measured from the obtained beret in the same manner as in Example PA6.

Its value was 71 (XIO ohms).

Example 7 Directly using an 871 stainless steel web compression molding machine!
Sandwich between PP sheets of lL, O, Bms+ so that the ratio of l to l by weight pressure [C Create a laminated sheet by heating and forming, lengthwise with force and tumble;] lll1l, width 3ml
Cut into 11 squares and make pellets. 1fiii weight% of this pellet, 44% by weight of polypropylene powder.
, 23% by weight of ammonium bromide, 12% by weight of decabromodiphenyl ether, and 6% by weight of antimony pentoxide were mixed using a tumbler blender, and pellets were prepared using a conventional single screw extruder.

A test piece with a length of 20 m, a width of 20111 m, and a vagina size of 2III11 was made from the obtained pellets, and the volume resistivity was measured. Its value was 2.1 (XI (1 ohm).

In addition, the results of a combustion test conducted in accordance with the vertical method of the IJ 1.94 standard showed that the average self-extinguishing time was 1. After 3 seconds, there was no ignition of the cotton due to "flame drip", and the flame retardance was determined to be ①-〇.

Comparative Example 7゜Same stainless steel web as Example 7: Cut to 3 mm [
The web was directly mixed in the same proportion and method as in Example 7 without being pelletized to produce pellets.

The volume resistivity of C1 and the flammability of 7J were measured using the same method as in Example 7 from the pellets obtained.

3 Volume resistivity value is 3. ((XIO ohms, the average self-extinguishing time is 7.; (seconds, the ignition rate of cotton is 3/10, and the V
It was determined that the flame retardance was -2.

Example date.

Using a laminating machine, a stainless steel sliver with a diameter of 4 B was sandwiched between polypropylene films with a thickness of 60 μm at a weight ratio of 2:3, and then heated and formed to create a laminated film, and cut vertically with a cutter; ) 爾-5 width 2m
It was cut into 1-inch dice and made into berets.

This pellet is 10! i, i! 1'% and 57% by weight of MI9 polypropylene powder, 29% by weight of ammonium sulfate, 10111% of decabromodiphenyl ether, and 4% of antimony trioxide were mixed using a type blender. did.

Test pieces were prepared from the obtained pellets in the same manner as shown in Example 7, and the volume resistivity and flame retardance were measured.

The volume resistivity value is 8.3XIO, the average self-extinguishing time is 1.1 seconds, and there is no ignition of cotton due to "sparkle".■
It was determined that the flame retardance was -0.

Comparative Example 8 The same stainless steel sliver as in Example 8 was cut into 2Illl pieces, and the slivers were directly mixed in the same ratio and method as in Example 8 without pelletizing to create a Havelet.

The volume resistivity and flame retardance of the obtained pellets were measured in the same manner as in Example 8.

The volume resistivity value is 5.7X]03 ohms, the average self-extinguishing time is 5.9 seconds, the ignition rate of cotton is 371O, and the V-
It was determined that the flame retardancy was 2.

Note■ Comparative examples all had poor pellet formability in an extruder.

(For example, there was a lot of surging and strand breakage occurred frequently.) (2) The dispersibility of the metal fibers in the final pellets obtained in the comparative example was found to be significantly worse than in the example.

Patent expert Tokuyama Soda Co., Ltd.

Claims (1)

[Claims] 1) An electromagnetic device characterized in that metal fibers are sandwiched between thermoplastic resin sheets, the molded product obtained by heat molding is cut into pellets, and the pellets are filled in a thermoplastic resin. Manufacturing method of shielding resin 2) Fiber diameter of metal fiber is 4 to 207 Lm
3) A method for manufacturing an electromagnetic shielding resin according to claim 1, wherein the thermoplastic resin constituting the sheet and the thermoplastic resin filling the pellets are of the same type.
5) Method for manufacturing electromagnetic shielding resin according to claim 1 or 3, wherein the thermoplastic resin is polypropylene; 5) Technique for metal fibers in pellets. 6) A method for manufacturing an electromagnetic shielding resin according to claim 1, in which the length is 1 to 10+ m. 6) The metal fibers sandwiched between the thermoplastic resin sheets are 7) An aromatic bromine compound in which bromine is directly bonded to an inorganic ammonium salt, antimony trioxide, and a benzene nucleus (however, the amount of (excluding compounds in which bromine is bonded to) or an aliphatic bromine compound having a triazine ring.