JPH0373680B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a conductive film suitable for packaging, and is particularly flexible and has excellent surface smoothness, so it does not damage the contents of the package and protects the contents. The present invention relates to a method for producing a conductive film that has sufficient conductivity to protect against electrostatic damage, transparency to the extent that the contents can be seen through, and which can be heat-sealed. Electronic components such as semiconductor ICs and LSIs, printed circuit boards,
Magnetic tape and other products need to protect products from problems caused by static electricity, such as attracting dust and static electricity during the packaging and shipping process.In particular, C-MOS type ICs, which are commonly used these days, are susceptible to dielectric breakdown due to static electricity. Prevention of static electricity has become essential. In order to protect products from these electrostatic disturbances, packaging them with a conductive film with low surface resistivity may be considered. Conventionally, conductive paper made by mixing inorganic fibers such as carbon fibers, stainless steel fibers, and aluminum-coated glass fibers with wood pulp has been proposed as a conductive filler for this purpose. Because of its high surface strength, it easily damages the packaged contents. 2. Since there is no bending recovery property, the conductive performance decreases due to bending during use or processing. 3. Because it has a high specific gravity (stainless fiber 7.9, aluminum coated glass fiber 2.54) and water repellency, uniform dispersion in wood pulp stock is not easy, and the in-plane specific resistance of the conductive paper tends to be uneven. However, there is a need for conductive paper that does not damage the packaged contents. The present applicant previously filed an application for a conductive paper with transparency and heat-sealability using carbon fiber as a conductive filler (Japanese Patent Laid-Open No. 134421/1983), which allows the contents to be seen through without tearing the package. Moreover, by providing heat-sealability, an invention has been disclosed that can contribute to automation of packaging work. Subsequently, as a result of further research into the drawbacks of the above-mentioned inorganic fibers, it was found that all of these drawbacks were solved by using a specific organic fiber that had been treated with conductivity instead of the carbon fiber of the invention, and also improved transparency and heat resistance. The inventors have discovered that a conductive film with sealing properties can be obtained, and have arrived at the present invention. That is, the present invention has thermoplastic synthetic pulp of 99.5~
70% by volume, which is a conductively processed organic fiber based on an organic fiber having a melting point, softening point, or thermal decomposition temperature higher than the melting point of the thermoplastic synthetic pulp,
0.5 to 30 with a length of 1 to 40 mm and a diameter of 5 to 30 μm
% by volume and then heated by calendering at a temperature above the melting point of the thermoplastic synthetic pulp and at which the conductive treated organic fibers can be dispersed in their original form and have contact points. Opacity 30, characterized by pressure treatment
The present invention relates to a method for manufacturing a conductive film having a specific resistance in the in-plane direction of 1×10 ⁸ Ω·cm or less. The electrically conductive processed organic fibers (hereinafter referred to as "organic conductive fibers") used in the present invention refer to various synthetic fibers, semi-synthetic fibers, or natural fibers that are preferably electrically processed without impairing the properties of these fibers. For example, organic fibers are chemically bonded with metal ions or metal compounds, or organic fibers are physically bonded with a conductive agent such as metal or carbon. Preferred typical examples of materials to which metal ions or metal compounds are bonded are conductive fibers in which copper ions are diffused into acrylic fibers during the dyeing process (trade name: Thunderon SS-N, manufactured by Nippon Kage Senso Co., Ltd.), or various organic fibers. Conductive fibers containing adsorbed cuprous iodide in the fibers
39299) etc. Examples of materials to which a conductive agent is physically bonded include organic fibers with a conductive agent kneaded into the base (Japanese Patent Laid-Open No. 56-134298), carbon composite fibers, and organic fibers plated with metal (Japanese Patent Publication No. 134298/1983) 49−
No. 3921), etc., but chemical bonding is more preferable because it does not impair the properties of the base organic fiber and there is no risk of separation of the conductive agent during the papermaking process. The method of electrically conductive processing is not limited to the above example, and may be carried out so that the specific resistance of the fibers is about 1×10 ⁴ Ω·cm or less, preferably about 1×10 ⁰ Ω·cm or less. The conductive processed organic fiber has a specific gravity of 0.9 to 2.5.
In particular, a range of 0.9 to 1.35 is desirable. This is because the main raw material in which the organic conductive fibers are blended is thermoplastic synthetic pulp (for example, polyethylene synthetic pulp with a specific gravity of 0.94 to 0.96), so it is easy to uniformly disperse materials with similar specific gravity, and the in-plane specific resistance, This is because it is easy to obtain a conductive film with uniform transparency. Therefore, for example, polyvinyl alcohol type (specific gravity 1.26 to 1.30), polyamide type (specific gravity 1.14), acrylic type (specific gravity 1.14 to 1.30) can be used as the base organic fiber.
1.18) A conductive agent chemically bonded to polyvinyl alcohol and polyvinyl chloride copolymer fiber (specific gravity 1.32) is suitable. However, aluminum (specific gravity 2.7), copper (specific gravity 7.9), nickel (specific gravity 8.9),
Even if it is plated with other metals, it may be used as long as the thickness of the coating layer is reduced, since a product with a small specific gravity can be obtained. When synthetic fibers are used as the organic fibers serving as the base, their melting point, preferably their softening point, must be higher than the melting point of the thermoplastic resin raw material, such as thermoplastic synthetic pulp, serving as the matrix. This is because when the thermoplastic resin that becomes the matrix is heated and melted to make it transparent, such as in the method of heating and pressing the base paper made using a calendar in the manufacturing process of conductive film, organic conductive fibers are This is because if the organic conductive fibers melt earlier or at the same time and lose their shape, the electrical properties imparted to the organic conductive fibers will change, making it impossible to obtain a conductive film having the desired in-plane specific resistance. Therefore, the transparentization treatment of the matrix portion by heating and pressing is carried out at a temperature that is above the melting point of the matrix raw material and below the melting point, preferably below the softening point, of the organic conductive fiber. For example, when polyethylene synthetic pulp (melting point 110-138°C) is used as a matrix raw material, organic conductive fibers of the same type are inconvenient, and acrylic fibers (softening point 190-240°C) are used in combination. Polyester fiber (softening point 235-240
°C), polyvinyl alcohol fiber (softening point 220~
230℃), polyamide fiber (softening point 180-235℃)
etc. can also be used. When using semi-synthetic fibers or organic conductive fibers based on natural fibers, there are no problems such as softening or melting, but since the thermal decomposition temperature of cellulose is 240 to 400°C, the melting point is 240°C as a matrix raw material. It is preferable to use the following materials and perform heat and pressure treatment at 240°C or less. The diameter of the organic conductive fiber is 5 to 30 μm, and the length is 1
A diameter of 5 to 20 μm and a length of 1 to 25 mm are particularly preferred, although a diameter of 5 to 20 μm is preferred. This is a requirement for ease of paper making, uniform in-plane resistivity, and transparency. That is, regarding the diameter, the diameter of the synthetic pulp, wood pulp, etc. that occupies the matrix of the conductive film is 5 to 20 μm, and the conductive film according to the present invention usually has a basis weight of 20 g/m ² (thickness of about 22 μm). This is because uniform dispersion is possible because it is used in the range of ~100 g/m ² , and the surface of the conductive film is finished smoothly, which is preferable from the viewpoint of protecting the contents of the package. In addition, fibers with a length of 1 mm or less tend to fall off during paper manufacturing, making the conductive film's in-plane resistivity uneven. This is because it cannot be obtained and transparency cannot be obtained. On the other hand, if it is 40 mm or more, flocs tend to form, the formation becomes less uniform, and resistivity and transparency in the surface direction become non-uniform, which is not preferable. The thermoplastic resin that becomes the matrix in the conductive film produced by the present invention includes polyolefin, polyacrylonitrile, polyester, polyamide, polyvinyl alcohol, etc., and it becomes transparent when melted by heating and returns to a solid polymer by cooling. It also maintains its transparency, and a material with an appropriate melting point is selected in relation to the organic conductive fiber used. Among these, particularly preferred are polyolefins that have a low melting point and are relatively inexpensive. Polyolefins include polyethylene, polypropylene, copolymers of ethylene and propylene,
copolymer of ethylene or propylene and α-olefin, ethylene or propylene and vinyl acetate,
It includes a copolymer with acrylic acid or the like, a mixture thereof, or a polymer obtained by further chemically treating these. These polymers can also be used in combination with polyvinyl alcohol binders used in the paper industry. As mentioned above, there is an upper limit to the heat treatment temperature to avoid softening, melting, or thermal decomposition of organic conductive fibers, and when considering the heat sealability of the conductive film, the melting point should be 200°C or lower, especially 170°C. It is preferable that the temperature is below ℃. The conductive film according to the present invention is mainly manufactured by applying paper manufacturing technology, and the matrix made of thermoplastic synthetic resin is formed using thermoplastic synthetic pulp as a raw material. The term "pulp" is generally used to refer to a collection of cellulose fibers extracted by mechanically or chemically processing plant materials, but here it refers to a fibrous material or an aggregate thereof, and in the present invention, it refers to a fibrous material or an aggregate thereof. Plastic synthetic pulp is pulp made of thermoplastic synthetic resin.
It includes all fibrous substances that can be made into paper, such as thermoplastic synthetic fibers and thermoplastic synthetic fibrous binders. Moreover, in the conductive film according to the present invention,
Cellulose fibers may be dispersed in the thermoplastic resin matrix of the conductive film by replacing a part of the thermoplastic synthetic pulp as a raw material with chemical pulp in order to improve paper formability. The chemical pulp in the present invention includes not only sulfite pulp, kraft pulp, soda pulp, etc., but also semi-chemical pulp. Moreover, either bleached pulp or unbleached pulp may be used. The preferred chemical pulp for use in the present invention is bleached sulfite pulp or bleached kraft pulp from the viewpoint of transparency. Although it is not necessarily desirable to use chemical pulp in combination with the resulting conductive film in terms of its properties such as transparency and heat sealability, it is used in order to improve the formability when manufacturing the conductive film and from the viewpoint of price. It is something. However, the amount should be limited to replacing 50% by volume or less of the thermoplastic synthetic pulp. The conductive film according to the present invention is manufactured by the following method. First, thermoplastic synthetic pulp and short fibrous organic conductive fibers are mixed. When mixing, the thermoplastic synthetic pulp is placed in hot water or the like in advance and stirred to disintegrate it, and the organic conductive fibers are also dispersed in water or the like and then mixed. The blending ratio of the thermoplastic synthetic pulp and the conductive fibers has an important meaning on the properties of the resulting conductive film, such as its in-plane resistivity and transparency. If the amount of organic conductive fibers is too small, the contact between the fibers will be insufficient, making it impossible to obtain a conductive film with low specific resistance in the planar direction, and if the amount of organic conductive fibers is too large, the opacity will become high. The optimal blending ratio of organic conductive fibers may vary depending on the type of organic conductive fibers used and the thickness of the fibers, but in order to obtain a conductive film with an in-plane specific resistance of 1×10 ⁸ Ω・cm or less, At least 0.5% by volume or more,
Preferably, it is blended in an amount of 2% by volume or more. Furthermore, in order to ensure the opacity of the conductive film to be 30% or less, the amount of organic conductive fibers is adjusted to 30% by volume or less, preferably 10% by volume or less, depending on the thickness. If the diameter of the organic conductive fiber is 5 to 10 μm, it is 7% by volume or less, if it is 10 to 15 μm, it is 12% by volume or less, and 15 to 15% by volume.
When the thickness is 20 μm, it is preferably 20% by volume or less, and when the thickness is 20 μm or more, it is preferably 30% by volume or less. When blending chemical pulp as a raw material, the beaten pulp is mixed with the above raw material. In papermaking, a papermaking machine that is used in normal papermaking technology and is composed of a screen section, a pressing section, a drying section, etc. can be used. The dried base paper is heated and pressurized to make it transparent. Heat and pressure can be carried out by calender treatment or hot press treatment, which makes the paper glossy and smooth the surface in the normal papermaking process.The pressure conditions include a linear pressure of 10 to 200 kg/cm by normal calender treatment, or hot press. In this case, the pressure is appropriately selected from 10 to 200 kg/cm ² . Further, under similar conditions, treatment using a plastic calendar can also be carried out. Regarding the temperature conditions, unlike ordinary calender treatment, it is essential to heat the process to a temperature higher than the melting point of the plastic synthetic pulp. However, the heating temperature is set to a temperature below the melting point, preferably below the softening point, of the organic conductive fiber used. For example, if thermoplastic synthetic pulp with a melting point of 123°C (polyethylene resin product name SWP UL410 manufactured by Mitsui Petrochemicals Co., Ltd.) is used as the matrix raw material, and acrylic fiber with a softening point of 190°C is used as the base of the organic conductive fiber. for,
Heat treatment at a temperature of 123℃ or higher and 190℃ or lower. This heating is necessary both to make the thermoplastic resin matrix formed from the thermoplastic synthetic pulp transparent and to reduce the in-plane specific resistance value of the conductive film. The conductive film according to the present invention preferably has a thickness of 100 μm or less from the viewpoint of transparency, flexibility, etc. The conductive film manufactured as described above is
Short organic conductive fibers are dispersed in a film-like transparent thermoplastic resin matrix, and the conductive fibers have contact points with each other to maintain electrical contact. , it has a portion where there is no organic conductive fiber, that is, a portion where there is only a transparent resin matrix. For this reason, electrical conduction occurs through many contact points of the organic conductive fibers, so it has a small in-plane specific resistance of 1×10 ⁸ Ω・cm or less, and light is not transmitted through the transparent resin matrix portion. Therefore, a transparent conductive film with an opacity of 30% or less can be obtained. According to the present invention, a conductive film that has conductivity and transparency, which did not exist in the past, can be obtained because a small amount of organic conductive fibers is dispersed in a thermoplastic resin matrix without being cut. It's for a reason. This is because the conductive film according to the present invention is made by applying paper manufacturing technology and uses organic conductive fibers with high flexibility as the conductive filler. When conventional plastic molding techniques such as injection molding and extrusion molding are used, the resin matrix and conductive filler tend to get wet due to kneading, and the contact resistance at the contact points between the fillers tends to be high. Manufacturing by applying this method is desirable in order to obtain a film with excellent conductivity. In the present invention, the conductive film is manufactured by applying papermaking technology, so the organic conductive fibers are made into paper without being damaged for the most part, and even when they are fixed by pressure and heating, they remain in a state due to the melting of the thermoplastic synthetic pulp. The change acts as a buffer to protect the organic conductive fibers from breaking due to the pressure of the calender, and each contact point between the organic conductive fibers is made of molten thermoplastic composite fibers with a large ratio of length to diameter. It is gripped by the pulp and fixed by cooling after treatment to form a film. Therefore, in the conductive film of the present invention, the large number of contacts reduces the total resistance value, like a parallel resistance. This is considered to be the reason why a low in-plane specific resistance can be obtained despite the small amount of organic conductive fibers added. In carrying out the present invention, a natural or synthetic polymer substance with a refractive index lower than or equivalent to that of cellulose and whose melting point is similar to that of thermoplastic synthetic pulp is used as a clarifying agent for the papermaking raw material. There is no problem with mixing it into the paper stock. Further, various binders, surfactants, paper strength enhancers, antifoaming agents, etc. may be added to the papermaking raw materials. Further, in order to promote transparency, it is possible to use known techniques such as dumping moisture into the base paper and treating it with a super calendar, or treating it by increasing the linear pressure. Depending on the type of thermoplastic synthetic pulp, a hot air heating machine, an infrared heating machine, etc. can also be used in combination. In addition, the papermaking process is preferably carried out at a drying temperature below the softening point of the thermoplastic synthetic pulp. As mentioned above, the method for manufacturing the conductive film according to the present invention has been described using a paper manufacturing method, but a dry nonwoven fabric manufacturing method can also be adopted based on the same technical concept. The conductive film obtained by the present invention is practically as transparent as or more transparent than glassine paper, and has antistatic properties and heat sealing properties, making it a novel and useful product that meets the needs of the industry. It is something. In the conductive film produced according to the present invention, a desired specific resistance can be obtained by changing the blending ratio of the conductive fibers, and the in-plane specific resistance is mainly 10 ⁸
~ ¹⁰⁰ Ω・cm can be used as a bag to prevent dust from adhering to electronic parts, ^etc. , and to prevent electrostatic damage.
10 ^-2 Ω・cm is suitable for applications requiring electromagnetic shielding effect. Furthermore, the organic conductive fibers used in the present invention have superior flexibility and flexibility compared to other conductive fibers such as carbon fibers and metal fibers, so the resulting conductive film also has excellent flexibility and flexibility. In addition to being highly flexible, the fibers and matrix resin are compatible with each other, so that the fibers are fully embedded in the resin matrix even on the surface of the conductive film, resulting in a conductive film with an extremely smooth surface. Therefore, when used as a packaging film, it does not damage the packaged contents at all, and it also has better formability than other conductive fibers, so it can be used to form desired shapes and structures. It also has the effect of making the product easier to manufacture. Further, the conductive film produced according to the present invention can be used by laminating it with other transparent materials or bonding it with opaque materials, or can be used as an embossed product with some opaque parts remaining. Experimental Example 1 The following experiment was conducted to find out that when the conductive film according to the present invention is used for packaging, the organic conductive fibers do not damage the contents. Thunderon SS-N (trademark, acrylic type, softening point 190-240℃, specific gravity 1.18,
Average fiber length 3mm, single yarn diameter 17.5μm, specific resistance 5.85×
10 ^-2 Ω・cm (manufactured by Nippon Silk Hair Dying) and Kureha Carbon Fiber Tip C203 (trademark, graphite, average fiber length 3 mm, single yarn diameter 12.5 μm, manufactured by Kureha Chemical Co., Ltd.) as a comparison material. This was used as a test sample. Hold both ends of this adhesive paper between lab testers (manufactured by Toyo Seiki) and separately prepared methacrylic resin plate Acrylite (trademark, manufactured by Mitsubishi Rayon).
500 with a load of 0.5 lb/sq.
I rubbed it back and forth. Next, the scratches on the methacrylic resin board and the degree of adhesion of powder from the methacrylic resin board to the sample were visually judged, and the gloss of the methacrylic resin board was measured using a gloss meter S (manufactured by Toyo Seiki).
It was measured with The results are shown in Table 1.

[Table] As is clear from Table 1, Thunderon SS-N
The surface hardness of carbon fiber is much lower than that of carbon fiber, so it can be seen that it is one of the conductive fibers suitable for the purpose of the present invention. Next, SWP UL410 as thermoplastic synthetic pulp
(trademark, polyethylene resin manufactured by Mitsui Petrochemicals, specific gravity 0.94, melting point 123℃, average fiber length 0.9mm, whiteness 94)
% or more) (hereinafter abbreviated as SWP410),
The above-mentioned Thunderon SS-N (hereinafter referred to as Thunderon) was used as the conductive fiber and the above-mentioned carbon fiber was used as a comparison sample. Each conductive fiber was mixed with SWP410 in an amount of 30% by weight to make paper, and then heated at 130°C and 60 kg/cm. Pressure treated to produce two types of conductive films (approx.
100g/m ² ). A comparison was also made with a commercially available polyethylene film for packaging. This was subjected to a friction test in the same manner as above, and the results are shown in Table 2.

[Table] As a result, it was found that the product of the present invention, like ordinary packaging films, has almost no risk of damaging the contents even when subjected to severe friction. When observing the surface of the conductive film with an electron microscope magnified 100 to 500 times, it was found that Thunderon SS-N was completely buried in the resin matrix, but the carbon fibers were not covered by the resin matrix and protruded. Also, the fusion with the matrix was poor, and many continuous and discontinuous holes were observed around the fibers. From these results, it was considered that the reason why carbon fiber blended products easily damage the contents is because they have poor affinity with the resin matrix, have high surface hardness, and lack flexibility. Experimental example 2 SWP410 was used as thermoplastic pulp, and NBKP (softwood bleached kraft pulp) was used as chemical pulp.
And as the organic conductive fiber, Thunderon fiber diameter 17.5 μm and fiber length 3 mm were used. The experimental sample contained 5% by weight of Thunderon.
(3.8 volume%) and changed the mixing ratio of SWP410 and NBKP to produce ³ sheets with a target basis weight of 50g/m2.
I created a seed. The freeness of NBKP was set to 300 ml CSF using a Canadian standard hydrometer, and SWP410 and Thunderon were each dispersed in water and then uniformly mixed with NBKP. Next, the linear pressure of the super calender for testing was 60Kg/
The properties of each sheet were measured by heating at a roll surface temperature of 130°C at a constant speed of 4.5 m/min. The measurement results are shown in Table 3. Here, the volume % is calculated using the specific gravity of the raw materials used (Thunderon 1.2, SWP410 0.9, chemical pulp 0.9). Furthermore, the true specific gravity of chemical pulp is
Although the specific gravity is 1.4 to 1.6, an apparent specific gravity of 0.9 was used in the present invention.

[Table] The opacity is measured using a photovolt photoelectric reflectometer.
Measured with Model 670. Further, the in-plane specific resistance is generally expressed by the following formula. ρ=RTW/L ρ: Planar specific resistance Ω・cm L: Distance between voltage electrodes (cm) R: Actual resistance value (Ω) T: Thickness of test piece (cm) W: Width of test piece (cm) ) Measurement of in-plane specific resistance is based on the Japan Rubber Association method.
Compliant with SRIS2301. From Table 3, it was found that the greater the amount of SWP410, the lower both the in-plane specific resistance and opacity, and the more excellent the sheet was obtained in conductivity and transparency. Also, the surface temperature of the roll obtained when a sheet with a mixing ratio of SWP410/NBKP/Thunderon of 66.5/28.5/5% by weight (Thunderon 3.8% by volume) and a basis weight of 50 g/ ^m2 was calendered. The relationship between sheet opacity is shown in FIG. From this, if the linear pressure of the calendar roll is constant at 60Kg/cm,
Up to the softening point (100-105℃) of SWP410,
There is no significant change in opacity, but above the softening point, the opacity decreases rapidly, and above the melting point (123°C), the sheet becomes a sheet with low opacity. Experimental example 3 Using SWP410 as the thermoplastic pulp and Thunderon (fiber diameter 17.5 μm, fiber length 3 mm) as the organic conductive fiber, the target rice was achieved by varying the blending amount of Thunderon without adding any chemical pulp. Basis weight 50
Various sheets of g/m ² were prepared. The heating and pressurizing conditions were the same as in Experimental Example 2. Regarding the obtained conductive film, the relationship between the opacity and the blending amount (volume %) of Thunderon is shown in FIG. 2, and the relationship between the specific resistance in the in-plane direction is shown in FIG. From FIG. 2, the tendency for the opacity to increase as the amount of organic conductive fibers increases is relatively gradual, and conductive films with opacity well below 30% were obtained for each sample. It can be seen that the desired amount of Thunderon used is 20% by volume or less, and in particular, if it is 10% by volume or less, an opacity of several percent and excellent transparency can be obtained. From Figure 3, a conductive film with Thunderon of 1% by volume or more and a specific resistance in the planar direction of 1×10 ⁶ Ω・cm or less was obtained, and the specific resistance in the planar direction suddenly decreases from around 2% by volume. When the amount of compounding is increased, it becomes 1×
A conductive film with a resistance of ¹⁰ Ω・cm or less can be obtained. Experimental Example 4 Various conductive films were created by using chemical pulp in combination so that the mixing ratio of SWP410/NBKP was 80/20 parts by weight, and by varying the blending amount of Thunderon. Thunderon has fiber lengths of 5 mm and 3, respectively.
mm, 0.7mm (fiber diameter is 17.5μ)
An experiment was conducted regarding m). The target weight for each sample was 50 g/m ² , and the heating and pressing conditions were the same as in Experimental Example 2. FIG. 4 shows the relationship between the in-plane specific resistance and the amount of Thunderon (volume %) for the obtained conductive film. In Fig. 4, ● marks are for Thunderon fibers with a length of 5 mm, ○ marks are for 3 mm fibers, and △ marks are for 0.7 mm fibers. For comparison, the fiber length is 3 mm and the diameter is 12.5 μm.
The measurement results for a conductive film made under the same conditions using carbon fibers are also shown in FIG. 4 as x marks. From Figure 4, in order to make the in-plane resistivity less than 1×10 ⁸ Ω・cm, the amount of Thunderon added should be increased by increasing the fiber length by 5.
It can be seen that the amount should be 0.7% by volume or more for mm and 3mm products, and 5.5% by volume or more for 0.7mm products. Furthermore, the longer the fiber length of Thunderon is, the smaller the amount required to obtain specific resistance in the same plane direction is required. Also, when compared with those containing carbon fiber,
When the blending amount is 3% by volume or less, the degree of increase in the in-plane resistivity as the blending amount decreases is different for fiber lengths of 3 mm and 5 mm.
Sanderon is more gentle, and in the case of Thunderon, a conductive film of 1×10 ⁶ Ω·cm or less can be obtained even at 1% by volume. Example 1 SWP UL410 (manufactured by Mitsui Petrochemical Co., Ltd., polyethylene resin, melting point 123°C) as thermoplastic synthetic pulp
(hereinafter abbreviated as SWP410) was poured into hot water at 50°C to give a concentration of 3%, and disintegrated with a stirrer. In addition, as a chemical pulp, NBKP was beaten with a test beater until the degree of beating was 30 ml CSF. Thunderon SS-N as an organic conductive fiber (Nihon Kasuke Dyeing Co., Ltd.)
Average fiber length 5mm, fiber diameter 17.5μm, specific resistance 5.9×
10 ^-2 Ω・cm) is dispersed in water at room temperature to a concentration of 1%, and trimin is added to this as an antifoaming agent.
Adjustments were made by adding a small amount of DF130 (manufactured by Miyoshi Yushi Co., Ltd.). The mixing ratio of these is 80/20/5 parts by weight (77/
19.2/3.8% by volume), placed in a mixing tank and stirred for 10 minutes, then added PEO − as a dispersant.
A base paper was produced by adding 0.06% PF (manufactured by Seitetsu Kagaku Co., Ltd.) to the raw material and aiming for a basis weight of 50 g/m ² . The base paper was dried at 80-100°C. Linear pressure 60Kg/
cm, and processed in a super calender at a temperature of 130°C to produce a conductive film. Table 4 shows the physical properties of the base paper and conductive film.

[Table] The heat seal strength shown in the table was based on Tatsupi Standard T517-69 and was conducted under the following conditions. Sealing conditions: crimping pressure 2Kg/cm ² , crimping time 1 second,
Temperature: 150℃, seal width: 10mm Strength test: T-type peeling speed: 50mm/all-purpose tensile tester Tensilon (manufactured by Toyo Baldwin Co., Ltd.)
The base paper had a high opacity and had the appearance of a high-grade paper. The conductive film has a very smooth surface.
The organic conductive fibers were uniformly dispersed in the film without any discomfort from the matrix, giving it the feel of a homogeneous plastic film, and when it was made into a bag, the contents could be seen through. The high air permeability is due to the melting effect of the synthetic resin pulp, and therefore the water permeability is low, so even if the bags were heat-sealed, filled with water 1, and left for a long time, there was no tactile sensation of water oozing out. Moreover, the heat sealing strength was also sufficient. Example 2 Mixing ratio of SWP410/NBKP/Thunderon
A conductive film was produced in the same manner as in Example 1, except that the ratio was 80/20/1 part by weight (79.3/19.9/0.8% by volume). The conductive film obtained had a surface direction specific resistance of 5×10 ⁶ Ω·cm and an opacity of 10.3%.
This conductive film could be used satisfactorily as a dust prevention bag. Example 3 The average fiber length of Thunderon was 3 mm,
Mixing ratio of SWP410/NBKP/Thunderon
A conductive film was produced in the same manner as in Example 1, except that the proportions were 50/50/3 parts by weight (48.9/48.9/2.2% by volume). The physical properties of the conductive film were as shown in Table 5.

[Table] Compared to Examples 1 and 2, the amount of chemical pulp was larger and the transparency was slightly lower. Compared to Example 1, the air permeability decreased, the moisture permeability increased, and the heat seal strength decreased;
Tensile strength has improved. The conductive film of this example could be used as a sufficiently conductive container. Example 4 Using ES instead of SWP as thermoplastic synthetic pulp
-Chop (composite fiber of polyethylene and polypropylene manufactured by Chitsuso Co., Ltd., melting point 165-170℃, fiber length 5
mm, fineness 3 denier) and a polyvinyl alcohol fibrous binder at a ratio of 90:10, no chemical pulp was used, and 5 parts of Thunderon (fiber length 3 mm) was added to this. Therefore, in this composition, the mixing ratio of thermoplastic synthetic pulp and organic conductive fiber is
It is 100/5 parts by weight (96.1/3.9% by volume). This was made into paper in the same manner as in Example 1, aiming at a basis weight of 50 g/m ² to produce a base paper. Next, we used a super calendar and an infrared heating machine to heat the product at 180℃ and 60Kg/cm.
Processed with. The characteristics of the obtained conductive film are as follows.
It was as shown in the table.

[Table] Compared with Example 1, the conductive film of this example was more flexible and noble, had excellent suitability for processing into bags, and had sufficient transparency. Example 5 Same method as Example 1 except that no chemical pulp was used, the mixing ratio of SWP410/Thunderon was 100/5 parts by weight (96.2/3.8% by volume), and the average fiber length of Thunderon was 3 mm. 30, 40, 50 basis weight
Paper was made with a target of g/m ² and subjected to supercalender treatment to produce three types of conductive films.
Table 7 shows the properties of the conductive film obtained.

[Table] All of the obtained conductive films had excellent transparency and had the appearance of a lightly colored transparent plastic film, and the surface had a smooth plastic feel. Example 6 Mixing ratio of SWP410/NBKP/Thunderon
Paper was made in the same manner as in Example 1, except that 80/20/10 parts by weight (74.4/18.6/7.0% by volume) was used, aiming for a basis weight of 50 g/ ^m2 , and a conductive film was obtained by supercalendering. . This conductive film has a weight of
54.4g/m ² , opacity 17.9%, air permeability 5000 seconds/
The volume was 100 ml, and the in-plane specific resistance was 2.8×10 ⁰ Ω·cm. Example 7 Mixing ratio of SWP410/NBKP/Thunderon
Paper was made in the same manner as in Example 1, except that 75/25/25 parts by weight (63.2/21.0/15.8% by volume) was used, aiming for a basis weight of 40 g/m ² , and supercalendered to obtain a conductive film. . The characteristics of this conductive film are as follows:
It was as shown in the table.

[Table] Example 8 Acrylic fiber (diameter 14μ
Using fibers with an average fiber length of 5 mm (specific gravity 2.0) coated with aluminum to a thickness of approximately 3 μm on the surface of the fibers, the mixing ratio of SWP410/organic conductive fiber was 90/10 parts by weight (without using chemical pulp). 95.2/4.8 capacity%)
A conductive film was produced in the same manner as in Example 1, except for the following. The obtained conductive film had a basis weight of 51.2 g/m ² ,
The opacity was 7.5%, the in-plane specific resistance was 1.3×10 ⁰ Ω·cm, and it had the appearance of a smooth plastic film. Example 9 SWP410 was used as a thermoplastic synthetic pulp, human silk (diameter 26 μm) was used as an organic conductive fiber, and the surface was coated with copper to a thickness of 2 μm, and the average fiber length was 5 mm (specific gravity
3.4), without adding chemical pulp, and by changing the amount of copper-coated fibers to achieve a target basis weight of 50g/m ²
Various sheets were created. The heating and pressurizing conditions were the same as in Example 2. Table 9 shows the physical properties of the conductive film obtained.

[Table] According to Table 9, this conductive film exhibits stable in-plane resistivity when the content of copper-coated human silk is 1.4% by volume or more, and it exhibits the same transparency as a transparent film when the content is 6.2% by volume or less. have. It was also determined that the fibers were sufficiently embedded in the synthetic resin matrix and the film surface was smooth, so there was no risk of damaging the packaged contents.

[Brief explanation of drawings]

FIG. 1 is also a graph showing the relationship between the surface temperature of the roll and the opacity of the sheet obtained during calendering. FIG. 2 is a graph showing the relationship between the amount of organic conductive fibers (volume %) and the opacity of a conductive film made without using chemical pulp. FIG. 3 is a graph showing the relationship between the amount (volume %) of organic conductive fibers and the in-plane specific resistance of a conductive film made without using chemical pulp. FIG. 4 is a graph showing the relationship between the in-plane specific resistance of a conductive film made using chemical pulp in combination with the blending amount (volume %) of organic conductive fibers of various fiber lengths and carbon fibers.

Claims (1)

[Scope of Claims] 1 Conductively processed organic fibers containing 99.5 to 70% by volume of thermoplastic synthetic pulp and organic fibers having a melting point, softening point, or thermal decomposition temperature higher than the melting point of the thermoplastic synthetic pulp. The length is 1~40mm,
A base paper made by mixing 0.5 to 30% by volume of fibers with a diameter of 5 to 30 μm is heated to a temperature higher than the melting point of the thermoplastic synthetic pulp and the conductive treated organic fibers are dispersed in their original form to form contact points. 1. A method for producing a conductive film having an opacity of 30% or less and an in-plane specific resistance of 1×10 ⁸ Ω·cm or less, the method comprising heating and pressurizing the film by calendering at a temperature that allows the conductive film to have an opacity of 30% or less. 2. The method for producing a conductive film according to claim 1, wherein the organic fiber is a synthetic fiber and the heating temperature is a temperature below the melting point of the synthetic fiber. 3 The organic fiber is a semi-synthetic fiber or a natural fiber,
The method for producing a conductive film according to claim 1, wherein the heating temperature is 240°C. 4 Claim 1 in which less than 50% by volume of thermoplastic synthetic pulp is replaced with chemical pulp
A method for manufacturing a conductive film according to any one of items 1 to 3.