JPH0136500B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition containing a high concentration of metal foil pieces and a method for producing the same.

BACKGROUND ART Recently, devices such as microwave ovens, TVs, and microcomputers that have built-in sources of electromagnetic waves have become widespread, and the chances of causing electromagnetic interference to communication devices, measuring instruments, etc. are increasing. Moreover, on the contrary, the chances that these devices will be affected by electromagnetic interference from the outside are increasing.

When assembling these devices, metal casings are often used to avoid interference from electromagnetic waves, but since they require many processes such as molding and painting, they are not easy to mold. thermoplastic resin,
In addition, it has been desired to develop a material that has a large amount of attenuation of electromagnetic waves passing through it.

However, if a large amount of metal foil (Al, Cu, etc.), which is effective in attenuating electromagnetic waves, is mixed and kneaded with thermoplastic resin, it will be difficult to get it into the screw in a single-screw extruder, and it can only be kneaded mechanically. In this case, it was difficult for the metal foil pieces to be sufficiently dispersed in the resin, and the strength of the resulting resin composition was also unsatisfactory.

The present inventors solved the problems of the prior art described above, and obtained a resin composition that contains metal foil pieces at a high concentration, has good dispersion of the metal foil pieces, and has sufficient strength. The present invention was achieved as a result of intensive research with the first objective being to develop a method for producing such a resin composition and the second objective being to develop a method for producing such a resin composition.

The first object of the present invention is that the surface of 100 parts by weight of a metal foil piece is made of a monomer selected from the group consisting of acrylic acid, methacrylic acid, alkyl acrylate, aminoalkyl acrylate, alkyl methacrylate, and aminoalkyl methacrylate; Alternatively, one whose surface is coated with 1 to 10 parts by weight of a first polymer obtained by polymerizing a mixture of two or more monomers, and an aromatic vinyl monomer based on 100 parts by weight of a metal foil piece. This can be achieved by a composition obtained by blending 5 to 33 parts by weight of a second polymer obtained by polymerizing a mixture consisting of a monomer copolymerizable with an aromatic vinyl monomer and an aromatic vinyl monomer.

A second object of the present invention is to provide a method for producing a composition containing 6 to 43 parts by weight of a thermoplastic resin based on 100 parts by weight of a piece of metal foil, including acrylic acid, methacrylic acid, alkyl acrylate, aminoalkyl acrylate, Suspension polymerization of 1 to 10 parts by weight of a monomer selected from the group consisting of alkyl methacrylates and aminoalkyl methacrylates or a mixture of two or more monomers in the presence of 100 parts by weight of metal foil, Subsequently, 5 to 33 parts by weight of a mixture consisting of an aromatic vinyl monomer and a monomer copolymerizable with the aromatic vinyl monomer is added and suspension polymerization is carried out.

The metal foil pieces used in the present invention include Al,
A material made of Cu or an alloy of these metals is preferable from the viewpoint of electrical conductivity, but a material made of other metals may also be used.

The size of the metal foil piece is 5 to 50 μm thick on one side.
A rectangular shape with a diameter of 0.5 to 5 mm is preferred, and a rectangular shape with a diameter of 1 to 2 mm is more preferred, but other shapes may be used as long as they are of the same size.

These metal foil pieces have a surface coated with a polymer of a monomer or a mixture of monomers selected from the group consisting of acrylic acid, methacrylic acid, alkyl acrylate, aminoalkyl acrylate, alkyl methacrylate, and aminoalkyl methacrylate. is coated. These polymers are suitable because they have high adhesion to metal foil pieces. In this case, it is appropriate to use 1 to 10 parts by weight of the above polymer per 100 parts by weight of the metal foil piece.

If it is less than 1 part by weight, there is no coating effect, and if it exceeds 10 parts by weight, the amount of polymer that does not adhere to the surface of the metal foil increases, which may adversely affect the physical properties of the composition, which is not preferable.

The polymer used to coat the metal foil piece may be one obtained by polymerizing the above-mentioned monomers alone, or may be one obtained by polymerizing a mixture of two or more arbitrary monomers. For example, methyl methacrylate is polymerized alone, acrylic acid is 10 to 30 wt.
A polymerized mixture of methyl methacrylate and acrylic acid containing 30 to 70 wt% of aminoalkyl methacrylate is used, and in particular, a polymerized mixture of methyl methacrylate and aminoalkyl methacrylate containing 30 to 70 wt% of aminoalkyl methacrylate is used to coat metal foil pieces. Excellent in terms of properties and compatibility with other resins. In this case, as the aminoalkyl group, dimethylaminoethyl group ((CH ₃ ) ₂ NCH ₂ CH ₂ -) is preferred, but diethylaminoethyl group, dimethylaminopropyl group, etc. can also be used.

Further, as the alkyl group, a linear, branched, or cyclic alkyl group having about 1 to 10 carbon atoms is used, but a methyl group or an ethyl group is preferable from the viewpoint of physical properties of the resulting polymer, such as tensile strength. . The blending ratio of each monomer mixture is not limited to the above range, but if it is within the above range, good results can be obtained in terms of coverage, dispersibility, physical properties, etc. of the surface of the metal foil piece. .

To coat a metal foil piece with the above polymer, the metal foil piece may be immersed in a solution in which the polymer is dissolved in a suitable organic solvent; Coating can be more easily achieved by suspension polymerization in the presence of.

Subsequently, 5 to 33 parts by weight of a polymer obtained by polymerizing a mixture consisting of an aromatic vinyl monomer and a monomer copolymerizable with the monomer to 100 parts by weight of the initially used metal foil piece. parts and the polymer used to coat the surface of the metal foil piece so that the total amount is 6 to 43 parts by weight based on 100 parts by weight of the metal foil piece initially used.

If the amount of the aromatic vinyl monomer and the monomer copolymerizable with it is less than 5 parts by weight, the bulk density of the resulting composition will be low, making it difficult to blend with ABS resin etc. Become. Also, if it exceeds 33 parts by weight, when blending with ABS resin or other thermoplastic resins,
This is not preferred because it becomes difficult to increase the concentration of the metal foil pieces.

Examples of the aromatic vinyl monomer used in the present invention include styrene, α-methylstyrene, vinyltoluene, and nuclear halogenated styrene. Further, as the "copolymerizable monomer", acrylonitrile, methacrylonitrile, and alkyl esters of acrylic acid and methacrylic acid are suitable. The appropriate concentration of these "copolymerizable monomers" in the monomer mixture is 20 to 50 wt%. If it is outside the above range, the compatibility with other resins will deteriorate, which is not preferable.

In order to produce the composition according to the present invention, it is preferable to carry out suspension polymerization of each of the above monomers in the presence of a piece of metal foil.

That is, 100 parts by weight of metal foil pieces, as well as acrylic acid, methacrylic acid, alkyl acrylate,
1 to 10 parts by weight of a monomer or monomer mixture selected from the group consisting of aminoalkyl acrylate, alkyl acrylate, and aminoalkyl methacrylate are suspended in water and subjected to suspension polymerization by a conventional method. . In this case, the use of a water-soluble initiator (persulfate, etc.) provides better coverage of the foil surface. After the polymerization is completed, 5 to 33 parts by weight of a mixture of an aromatic vinyl monomer and a monomer copolymerizable therewith are added to further carry out suspension polymerization.

The resulting composition was in the form of a pellet made of several dozen metal foils laminated, had a high bulk density, and had good compatibility with ABS resin and the like.

The composition according to the present invention can be used as it is, but it can also be used in combination with ABS resin, AS resin, etc. In this case, compounding can be carried out using a single screw extruder. The resulting composition has good physical properties and exhibits good electrical conductivity.

Furthermore, the metal foil pieces are hardly peeled off by external force.

The present invention will be explained in more detail based on Examples, Comparative Examples, and Application Examples.

Example 1 2.0 kg of deionized water and aluminum (Al) were placed in a glass four-necked flask with an internal volume of 3 and equipped with a stirrer.
Foil piece (1.4mm x 1mm x 0.025mm, K made by Transmet)
-102) Add 320g and stir well. To this, 8 g of methyl methacrylate and 8 g of dimethylaminoethyl methacrylate were added, and after purging the inside of the flask with nitrogen gas, the temperature was raised to 70°C. After the polymerization system reached 70°C, 0.8 g of potassium persulfate was added and reacted for 1.5 hours. Subsequently, the temperature was raised to 90°C and the mixture was reacted for 1 hour. The temperature of the polymerization system was set at 80°C, 50 g of styrene, 34 g of acrylonitrile, 1 g of terpinolene as a chain transfer agent, 2 g of benzoyl peroxide and 0.5 g of azobisisobutyronitrile were added as an initiator, and polymerization was carried out for 2 hours. Summer. After the reaction was completed, the temperature was raised to 90°C, and unreacted monomers were removed for 1 hour under nitrogen gas flow.

Thereafter, the polymer containing the Al foil pieces was separated using a 200-mesh wire mesh.

The bulk density of the obtained polymer was 0.46 g/cm ³ (the bulk density of the Al foil pieces used was 0.19 g/cm ³ ), the content of the Al foil pieces was 83.3 wt%, and the yield was 95%. It was hot.

Example 2 A composition containing Al foil pieces was produced in the same manner as in Example 1, except that 16 g of methyl methacrylate was used instead of the mixture of methyl methacrylate and dimethylaminoethyl methacrylate.

The bulk density was 0.35 g/cm ³ , the Al content was 84 wt%, and the yield was 96.8%.

Example 3 Instead of a mixture of methyl methacrylate and dimethylaminoethyl methacrylate, acrylic acid
Same as Example 1 except that a mixture consisting of 3.2 g and 12.8 g of methyl methacrylate was used.
A composition containing Al foil pieces was produced.

The bulk density was 0.38 g/cm ³ , the Al content was 90.7 wt%, and the yield was 88%.

Comparative example Deionized water in a four-necked flask with an internal volume of 3
2.0Kg, Al foil piece (same as that used in Example 1)
320g was added and stirred well to disperse. to this,
62.5 g of styrene, 37.5 g of acrylonitrile, 1 g of terpinolene, 2 g of benzoyl peroxide, and 0.5 g of azobisisobutyronitrile were added, and polymerization was carried out at 80° C. for 2 hours. Subsequently, the temperature was raised to 90°C, and unreacted monomers were removed for 1 hour under nitrogen gas flow.

The bulk density of the polymer is 0.28 g/cm ³ and the yield is 83
% but a large number of polymer particles that did not contain aluminum foil pieces were present. In addition, aluminum foil pieces to which no polymer was attached and which were not laminated were also observed.

Example 4 Using the same equipment as in Example 1, 2.0 kg of deionized water,
900 g of copper foil cut pieces (1.5 mm x 1.3 mm x 0.035 mm) were added and stirred to disperse. To this, 10 g each of methyl methacrylate and dimethylaminoethyl methacrylate were added, and the temperature was raised to 70°C. After raising the temperature,
2 g of potassium persulfate was added and the above monomer mixture was polymerized for 1.5 hours, and further polymerized for 1 hour at 90°C. After lowering the temperature of the polymerization system to 80℃, 64g of styrene, 36g of acrylonitrile, 1g of terpinolene,
3 g of benzoyl peroxide and 2 g of azobisisobutyronitrile were added and polymerized for 2 hours.

The composition containing the copper foil pieces was separated with a 200 mesh wire mesh.

The bulk density of the obtained composition was 1.44 g/cm ³ , the bulk density of only the copper foil pieces used was 0.95 g/cm ³ ), the content of the copper foil pieces was 91.5 wt%, and the yield was 97%. Ta.

Application Example 1 The composition obtained in Example 1 was dry blended with ABS resin (Mitsubishi Monsanto Chemicals, Ltd. TFX-455AB) so that the content of Al foil pieces was 40 wt%, and then injection molded. The physical properties of the obtained composition were as follows.

Tensile strength at break 365Kg/cm ²
(Measured according to JIS, K-6871) Elongation at break 1.7%
( 〃 ) Izod impact strength 6.1Kg-cm/cm
(〃) Volume resistivity ^* 3.0Ω-cm * Measured using a test piece of 1.27 cm x 1.27 cm x 10 cm.

Application example 2 The composition obtained in Example 4 and ABS resin (Mitsubishi Monsanto Chemical Co., Ltd. TFX-455AB) were mixed with copper content.
The mixture was mixed to a concentration of 70 wt% and pelletized using a single screw extruder. The volume resistivity of the obtained test piece molded using pellets was measured in the same manner as in Application Example 1 and was 10 ^-2 Ω-cm or less.

Claims (1)

[Scope of Claims] 1. The surface of 100 parts by weight of the metal foil piece is a monomer selected from the group consisting of acrylic acid, methacrylic acid, alkyl acrylate, aminoalkyl acrylate, alkyl methacrylate, and aminoalkyl methacrylate, or A surface coated with 1 to 10 parts by weight of a first polymer obtained by polymerizing a mixture of two or more monomers;
5 to 33 parts by weight of a second polymer obtained by polymerizing a mixture consisting of an aromatic vinyl monomer and a monomer copolymerizable with the aromatic vinyl monomer to 100 parts by weight of the metal foil piece. A composition made by blending. 2 1 to 10 parts by weight of a monomer selected from the group consisting of acrylic acid, methacrylic acid, alkyl acrylate, aminoalkyl acrylate, alkyl methacrylate, and aminoalkyl methacrylate, or a mixture of two or more monomers was suspended and polymerized in the coexistence of 100 parts by weight of metal foil,
Subsequently, mixtures 5 to 33 consisting of an aromatic vinyl monomer and a monomer copolymerizable with the aromatic vinyl monomer
A method characterized by adding parts by weight and carrying out suspension polymerization.