JPH06145560A - Conductive composition for plastic coating - Google Patents

Abstract

PURPOSE:To obtain the title composition which can give a coating film which is excellent in contour following properties, conductivity and antiblocking properties during, the fabrication of a plastic sheet and does not change even under high-temperature high-humidity conditions. CONSTITUTION:The composition comprises a mixture comprising an aqueous dispersion (a) of a polyester resin, conductive carbon (b), an aqueous dispersion (c) of a polyolefin resin of a softening point of 100 deg.C or above and having a particle diameter of 2-10mum. The weight ratio of component (a) to component (b) is 95:5-50050, and that of the total weight of components (a) and (b) to the solid content of component (c) s 98:2-80:20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic coating conductive composition comprising an aqueous dispersion of a polyester resin.

[0002]

2. Description of the Related Art Generally, a plastic sheet (hereinafter referred to as a sheet) has excellent properties such as impact resistance, easy moldability, and light weight, and is used for various purposes. However, while these sheets have the above-mentioned characteristics, they are easily charged with static electricity, and dust and dirt adhere to them, so when used for packaging materials such as electronic components, the performance of the stored components deteriorates due to the generation of static electricity. However, there is a disadvantage that it is contaminated with dust and dirt during use, and its performance is impaired.

To prevent these disadvantages, in order to impart conductivity to the sheet, a solution or emulsion of a resin dissolved in a solvent is mixed or dispersed with a conductive substance such as an antistatic agent or conductive carbon metal powder. There is known a method of coating a sheet with.

[0004]

However, when the sheet is coated with a mixture or dispersion of the above-mentioned conductive substance in a solution of a resin dissolved in a solvent, there is a risk of air pollution and fire occurrence due to the solvent. However, there is a problem that it is not preferable in terms of worker health management and safety management.

Further, due to the residual solvent left in the coating film formed by coating on the sheet, the physical properties of the sheet itself are deteriorated,
There is also the problem of causing blocking and the like. Also,
Emulsion with water as a medium does not have sufficient elongation of the coating film, so the coating film cannot follow the elongation of the sheet during secondary sheet forming such as vacuum forming, pressure forming, press forming, etc. However, there is a problem that the conductivity is impaired, so plasticizers and soft polymers are used to improve the elongation of the coating film, but in this case the coating film becomes soft and blocks on the sheet after coating. There was a drawback that it caused.

In order to solve the above-mentioned drawbacks, the present inventors have
First, by using an aqueous solution or emulsion of a thermoplastic resin, a wax emulsion, a mixture containing a conductivity-imparting agent, when the solid content ratio of each component is within a specific range, vacuum forming, pressure forming, press forming, etc. It was proposed that a conductive composition for plastic coating, which has excellent followability of the coating film, conductivity and blocking resistance during secondary molding of the sheet (1), can be provided (Japanese Patent Application No. 10-2021).

However, as a result of further research, when a sheet coated with the composition is stored and transported, blocking may occur under certain environmental conditions, particularly when the temperature is kept at 50 ° C. or higher, and Temperature 40 ℃,
When the relative humidity (RH) is about 90% in a high temperature and high humidity state, the coating film swells and the wax content contained in the composition bleeds out to the surface of the coating film. However, there is a problem that the film strength is lowered and the film is easily scratched. Therefore, for example, when used as a carrier tape or the like, the seal strength between the tape and the cover tape is remarkably reduced, and when used as a packaging bag, peeling (bag breakage) is observed at the seal portion. Was occurring. in this way,
It was very difficult to satisfy all of the sheet secondary formability, blocking property and moisture resistance at the same time.

Therefore, in view of the above-mentioned conventional problems, the present invention, in particular, follows the covering film at the time of secondary forming of a sheet such as vacuum forming, pressure forming, press forming, conductivity, and blocking resistance at high temperature. It is an object of the present invention to provide a conductive composition for plastic coating, which has excellent properties and durability of the coating film at high temperature and high humidity.

[0009]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that an aqueous dispersion of a polyester resin, a conductivity-imparting agent, and a softening point of 100 ° C. or more are used to improve the particle size. The inventors have found that a mixture containing an aqueous dispersion of a polyolefin-based resin of 2 μm or more and 10 μm or less has an excellent effect when the solid content ratio of each component is within a specific range, and completed the invention.

That is, the present invention is: Aqueous dispersion of polyester resin, conductive carbon, softening point 100 ℃ or more, and particle size 2μm or more 10μm
A mixture containing the following aqueous dispersion of polyolefin resin, wherein the weight ratio of the solid content of the aqueous dispersion to the conductive carbon is 95: 5 to 50:50.
And the total weight ratio of the solid content and the conductive carbon to the solid content of the aqueous dispersion is 9
A conductive composition for plastic coating, which is 8: 2 to 80:20. Or, 2. Aqueous dispersion of polyester resin, conductive metal compound, softening point of 100 ℃ or more, and particle size of 2μm or more and 10μm
A mixture containing the following aqueous dispersion of a polyolefin resin, wherein the weight ratio of the solid content of the aqueous dispersion to the conductive metal compound is 75:25 to 40:
A conductive composition for plastic coating, which has a weight ratio of 60 and a total weight ratio of the solid content of the conductive metal compound to the solid content of the aqueous dispersion of 98: 2 to 80:20. Is the gist.

The present invention will be described in detail below. The polyester resin constituting the plastic coating conductive composition of the present invention is one having an ester bond between a carboxyl group and a hydroxyl group obtained by polycondensation of a polybasic acid and a polyhydric alcohol in the main chain. Yes, it may be saturated or unsaturated. Further, it may be a copolymer with styrene, acryl, urethane or the like, and an aqueous dispersion of these polyester resins can be used alone or in combination. Such an aqueous dispersion of polyester resin may be produced by a conventionally known method.

Examples of the conductive carbon which constitutes the conductive composition for plastic coating of the present invention include Ketjen black, acetylene black, graphite and carbon whiskers.

The polyolefin resin constituting the conductive composition for plastic coating of the present invention includes hard polyethylene and polypropylene (does not include wax or silicone oil), and their aqueous dispersions are conventionally known. It may be manufactured by the method. This polyolefin resin has a softening point of 100 ° C or higher and a particle size of 2μ.
It is in the range of m to 10 μm. This softening point is 100
When the temperature is lower than 0 ° C, a sufficient blocking preventing effect cannot be obtained, which is not preferable. If the particle size is less than 2 μm, the effect of preventing blocking is poor, and if it exceeds 10 μm, the particles fall off from the coating film, which is not preferable. Examples of commercially available products that meet such a range include Chemipearl W300 and W308 manufactured by Mitsui Petrochemical Co., Ltd.

Each of the above-mentioned components contained in the conductive composition for plastic coating of the present invention, that is, an aqueous dispersion of a polyester resin, conductive carbon, and a polyolefin having a softening point of 100 ° C. or higher and a particle size of 2 μm or more and 10 μm or less. The technical feature is that the weight ratio of each solid content of the aqueous dispersion of the resin is within a specific range. The range is such that the weight ratio of the solid content of the aqueous dispersion of the polyester resin to the conductive carbon is 95: 5 to 50:50, and the total weight of the solid content of the aqueous dispersion of the polyester resin and the conductive carbon. And a softening point of 100 ° C. or higher, a particle size of 2 μm or more and 10 μm
The weight ratio of solids in the following aqueous dispersion of polyolefin resin is 98: 2 to 80:20.

It is important that the conductive composition for coating a plastic of the present invention satisfies both of the above two conditions. If the ratio of conductive carbon is less than 5% under the above first condition, the conductive composition becomes conductive. Is not obtained, and if it exceeds 50%, the coating film becomes brittle and unsuitable. Further, under the second condition, if the solid content ratio of the aqueous dispersion of the particulate polyolefin resin is less than 2%, the blocking property at high temperature becomes poor, and if it exceeds 20%, the adhesion to the sheet becomes poor. It is not preferable.

In the present invention, a conductive metal compound may be contained in place of the conductive carbon constituting the conductive composition for plastic coating. Examples of the conductive metal compound include white sinter, titanium oxide particles coated with tin oxide, zinc oxide particles doped with aluminum, and potassium titanate whiskers. In the conductive composition for plastic coating of the present invention containing this conductive metal compound, each component, that is, an aqueous dispersion of a polyester resin, a conductive metal compound, a softening point of 100 ° C. or more and a particle diameter of 2 μm or more and 10 μm or less The weight ratio of the solid content of the aqueous dispersion of the polyolefin resin is characterized in that it is within a specific range, as in the case where the conductive carbon is contained. The range is such that the weight ratio of the solid content of the aqueous dispersion of polyester resin to the conductive metal compound is 75:25 to 40:60, and the solid content of the aqueous dispersion of polyester resin and the conductive metal compound are The weight ratio of the total weight to the solid content of the aqueous dispersion of the polyolefin resin is 98: 2 to 80:20.

It is important that the above composition of the present invention satisfies both of these two conditions. If the ratio of the conductive metal compound is less than 25% under the above first condition, the composition has good conductivity. Is not obtained, and if it exceeds 60%, the coating film becomes brittle and is not suitable. Further, under the second condition, if the solid content ratio of the aqueous dispersion of the granular polyolefin resin is less than 2%, the blocking property will be poor, and if it exceeds 20%, the adhesion to the sheet will be poor, which is not preferable. .

In addition to the above-mentioned essential components, the conductive composition for plastics coating of the present invention may contain a surfactant and a plasticizer, if necessary, within a range that does not affect secondary moldability, blocking property and conductivity. , Fusing agents, leveling agents, wetting agents, antifoaming agents, preservatives, ultraviolet absorbers, dyes, pigments, antioxidants, inorganic powders, and other additives can be added. These additives may be any conventionally known additives.

The method for producing the conductive composition for coating plastics of the present invention includes an aqueous dispersion of polyester resin as the first component, conductive carbon or conductive metal compound as the second component, and third component. An aqueous dispersion of a polyolefin-based resin that is is separately prepared according to a conventional method,
It can be produced by mixing the above-mentioned solid content weight ratios and, if necessary, appropriately adding the additives as the optional components.

The composition of the present invention obtained by the above method is applied to a sheet, and the coating method includes dipping method, spray method, flow coating method, gravure method, roll coating method and the like. Then, a smooth surface solidified coating film can be obtained.

Examples of the material of the sheet to be coated include plastics such as polycarbonate, polyacrylonitrile, polydiethylene glycol bisallyl carbonate, ABS resin, polyvinyl chloride, polyester and amorphous polyethylene terephthalate, and particularly electronic parts. It is a sheet used for carrier trays and carrier tapes, and is useful for plastics with poor conductivity. An inorganic filler or the like may be mixed in these exemplified plastics, or alloys of the exemplified plastics may be used.

The above-mentioned coated sheet is dried and solidified at a temperature not higher than the heat distortion temperature of each plastic. Specifically, it varies depending on the type of sheet, but usually 40 to
It is carried out at a temperature of 140 ° C., preferably 60 to 120 ° C., and the solidified coating film is solidified to a thickness of usually 0.5 to 20 μm, preferably 1 to 10 μm.

The conductive composition for plastic coating of the present invention can be used not only as a sheet but also as a coating agent for plastic molded articles. In particular, it is more effective to use as a coating agent that imparts followability of the coating film, conductivity, blocking resistance, and moisture resistance during secondary molding of the sheet. The composition of the present invention can also be used in the field of coating production and the field of plastics processing, but especially packaging for electronic component trays, carrier tapes, reels for carrier tapes, etc. in which troubles due to static electricity should be prevented. It is useful for products such as materials.

[0024]

The aqueous dispersion of polyester resin constituting the conductive composition for plastic coating of the present invention functions as a conductivity-imparting agent (conductive carbon or conductive metal compound) and a binder for granular polyolefin resin, It also functions as a binder for the sheet, the conductivity-imparting agent, and the granular polyolefin resin. Further, the conductive carbon or the conductive metal compound can impart good conductivity and antistatic property by being dispersed almost uniformly in the coating film. Further, the aqueous dispersion of the polyolefin-based resin, when mixed with the aqueous dispersion of the polyester-based resin, imparts lubricity to the surface of the coating film, and provides anti-blocking property and scratch resistance to the sheet or the coating film to be in contact with. Can be improved. In particular, it is possible to eliminate damage to the surface of the interior electronic component due to vibration that occurs when an inorganic substance such as amorphous silica is used.

[0025]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples of the present invention. However, the present invention is not limited to these Examples and Comparative Examples.

(Regarding Each Component) Aqueous dispersion of polyester resin Rack skin US180 manufactured by Seiko Kasei Co., Ltd. was used. (NV. (Nonvolatile content) is 20%.)

Conductive carbon Lion Paste W-376R manufactured by Lion Co., Ltd. was used. (NV. Is 12.5%.)

Conductive Metal Compound Lion Paste WS-520A manufactured by Lion Corporation was used. (NV. Is 41.5%.)

At a softening point of 100 ° C. or more, a particle size of 2 μm or more 1
Aqueous dispersion of polyolefin resin having a size of 0 μm or less was used Chemipearl W-308 manufactured by Mitsui Petrochemical Co., Ltd.
(NV. Is 40%.)

Examples 1 to 6 and Comparative Examples 1 to 8 Using the above components, plastic coating compositions having the mixing ratios shown in Table 1 were produced.

[0031]

[Table 1] Next, these compositions were applied to a layer having a thickness of 0.5 mm and a width of 300 m.
It was coated on a sheet made of amorphous polyethylene terephthalate having a length of m and a length of 400 mm by using a 5 mil bar coater. Immediately, it was placed in a hot air drier and dried and solidified at 60 ° C. for 5 minutes to obtain a sheet having a coating film with a film thickness of 2 μm. The physical properties of the obtained sheet were evaluated by the following methods.

1. Adhesion of coating film Place the sheet on a cross-cut tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) and insert a single-edged razor to make a cross hatch.
A cellophane adhesive tape was attached on the crosshatch, and the tape was strongly pulled in a direction perpendicular to the sheet to examine the peeling state of the coating film.

2. Conductivity in sheet form The surface resistance of the coated surface of the sheet was measured using a surface resistance meter with a comparator (MCP-TESTER manufactured by Mitsubishi Petrochemical Co., Ltd.).

3. The conductive sheet after vacuum forming was vacuum formed under the condition that the drawing ratio was 25%, and the surface resistance of the coated surface at this time was measured by the same device as in the above 2.

4. Blocking property The coated surfaces of the sheets are placed on top of each other, a load of 1 kg / cm ² is applied in an atmosphere of 50 ° C, left for 24 hours, then left at room temperature for 2 hours, and then the two sheets are peeled off to make contact surfaces. Of the blocking state of.

5. Nail Scratch Property The method of scratching when the coated surface of the sheet was strongly rubbed with a nail was examined.

6. High temperature and high humidity resistance Cover tape for carrier tape SP-
82 (manufactured by Shin-Etsu Polymer Co., Ltd.) is placed at a temperature of 140 ° C.
Sealed under a load of 4 kg / cm ² and a time of 1 second, and allowed to stand for 24 hours in a room temperature of 40 ° C. and a relative humidity of 90%, then immediately peeled 180 degrees, and the peeling force was checked to find that it was normal. Compared.

The results of the above physical property tests are shown in Table 2, and ◯, Δ, and × in the table mean the following, respectively.

1. Adhesion of coating film ◯: 100% no peeling, ×: 1% or more peeling,

2. Conductivity in sheet state ◯: 1 × 10 ⁸ Ω or less, ×: 1 × 10 ¹⁰ Ω or more,

3. Conductivity after vacuum molding ◯: 1 × 10 ⁸ Ω or less, Δ: One in which 1 × 10 ¹⁰ Ω or more partially occurs due to molding, ×: 1 × 10 ¹⁰ Ω or more

4. Blocking property ◯: No blocking, Δ: little blocking, ×: blocking,

5. Scratchability of nails ◯: No scratch, Δ: Slight scratch, ×: Scratch,

6. Resistance to high temperature and high humidity ◯: Change rate of less than 10%, Δ: Change rate of 10% to less than 50%, ×: Change rate of 50% or more,

[0045]

[Table 2]

(Test Results) In Examples 1, 2, 5 and Comparative Examples 1, 2, 3, 4, 7, the ratio of the weight of the aqueous dispersion of the polyester resin to the conductive carbon or the conductive metal compound is specified. The experimental results demonstrating the effect of the above are shown, and Examples 3, 4, 6 and Comparative Examples 5, 6, 8 show the solid content of the aqueous dispersion of the polyester resin and the conductive carbon or the conductive metal compound. It is an experimental result to clarify the effect of defining the ratio of the total weight to the solid content of the aqueous dispersion of the polyolefin resin having a softening point of 100 ° C. or more and a particle diameter of 2 μm or more and 10 μm or less.

[0047]

EFFECTS OF THE INVENTION According to the conductive composition for plastic coating of the present invention, by applying it to a sheet and drying it, the conductivity, adhesion, moldability, conductivity after molding, blocking resistance and scratch resistance are obtained. , Excellent in all properties of high temperature and high humidity resistance, furthermore, it does not pollute the atmosphere with solvent and has no drawbacks, so instead of the conventional conductive surface coating agent, a very good conductive composition for plastic coating is prepared. Can be provided.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location C09D 167/02 PKW 8933-4J PLA 8933-4J

Claims (2)

[Claims] 1. An aqueous dispersion of a polyester resin, conductive carbon, a softening point of 100 ° C. or higher, and a particle size of 2 μm or more and 10 μm.
A mixture containing an aqueous dispersion of a polyolefin resin of m or less, wherein the weight ratio of the solid content of the aqueous dispersion to the conductive carbon is 95: 5 to 50: 5.
0, and the weight ratio of the total weight of the solid content and the conductive carbon to the solid content of the aqueous dispersion is 98: 2 to 80:20. Composition. 2. An aqueous dispersion of a polyester resin, a conductive metal compound, a softening point of 100 ° C. or higher, and a particle size of 2 μm or more and 10 μm.
A mixture containing an aqueous dispersion of a polyolefin resin of m or less, wherein the solid content of the aqueous dispersion and the conductive metal compound are in a weight ratio of 75:25 to 4
The plastic coating is 0:60, and the weight ratio of the solid content, the conductive metal compound, and the solid content of the aqueous dispersion is 98: 2 to 80:20. Conductive composition for use.