JP4698573B2 - Antistatic self-adhesive polypropylene film - Google Patents

Description

  The present invention relates to an antistatic self-adhesive polypropylene film.

  Conventionally, in order to protect the surfaces of optical parts such as liquid crystal panels, plasma displays, polarizing plates and retardation plates, or printed circuit boards, ICs, transistors, capacitors, etc., antistatic surface protection films have been used. It is used. When the object to be protected by the surface protective film is an optical component or an electric / electronic component sensitive to electrostatic injury as described above, various kinds of static electricity are generated by peeling off the antistatic surface protective film from the object. There is a risk of damage to elements and circuits. Therefore, the surface protective film used for such applications is required to have a high antistatic performance.

  As the antistatic surface protective film, for example, a polyester film is used as a base layer, an antistatic layer is formed on one side of the base layer, and an adhesive layer is formed on the other side. In some cases, a protective layer is formed (for example, see Patent Documents 1 and 2). As an example of the production method of this antistatic surface protective film, first, a polyester film to be a base layer is prepared, and a coating liquid constituting the antistatic layer is applied on one side thereof with a gravure coater or the like, and heat treatment is performed after drying. . Next, a protective layer is formed on the surface of the antistatic layer, and the coating liquid constituting the protective layer is applied with a coater and dried in the same manner as described above. Thereafter, an adhesive layer is formed on the film surface opposite to the side on which the protective layer is provided, and the coating liquid constituting the adhesive layer is similarly applied by a coater and dried to produce an antistatic surface protective film. Is done.

  As described above, the production of the antistatic protective film involves repeating the steps of coating, drying, heat treatment, curing, and the like to form each layer by applying the coating liquid constituting the layer to be laminated on the base layer. Become very much. Further, in order to improve the adhesion and coating properties of each layer, preliminary treatment such as flame treatment, corona discharge treatment, or application of organic resin or inorganic resin paint is often performed. Therefore, there is a problem that the manufacturing process is extremely complicated and multi-step and the production cost becomes high. Moreover, as a conventional antistatic surface protective film, a polyester film and a polyethylene terephthalate film (hereinafter referred to as PET film) are mainly used. However, since such a film has low flexibility, it is difficult to stick to an object and workability is poor, and since the film itself does not have sufficient adhesive force, it is necessary to apply an adhesive. There is a problem that things are contaminated. Furthermore, there is a concern that the price of the raw resin itself is high.

On the other hand, an antistatic film made of polypropylene has also been proposed (see, for example, Patent Document 3). However, because polypropylene-based resin films are very easily charged, they usually protect the surface of an object, not in the field of optical parts and electrical / electronic parts that require advanced antistatic performance. In many cases, it is used for food packaging or the like for the purpose of preventing adhesion of dust and dirt. In addition, in order to improve the antistatic property, when a large amount of the antistatic agent is added, the cost becomes high, and the antistatic agent migrates to contaminate the object. .
JP 2000-26817 A JP 2003-154616 A JP 2003-334909 A

  The present invention has been made in view of the above points, and can be manufactured very easily by constituting an antistatic self-adhesive polypropylene film using a laminated polypropylene film formed by a coextrusion molding method. Provided is an antistatic self-adhesive polypropylene film that is very inexpensive, hardly blocking, has excellent antistatic performance, and has little contamination to the self-adhesive layer and the object to which the film is attached. It is.

  That is, the invention of claim 1 is the antistatic layer on the surface of the rough surface layer of the laminated polypropylene film in which the self-adhesive layer is integrally formed on one surface side of the base layer and the rough surface layer is integrally formed on the other surface side by coextrusion molding. It is related with the antistatic self-adhesive polypropylene film characterized by being formed.

  In the invention of claim 2, the antistatic layer comprises (a) the following formula (1):

(In the formula, R ¹ and R ² independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms, or R ¹ and R ² together may be optionally substituted 1 carbon atom. A conductive polymer comprising a polycationic polythiophene and a polyanion comprising a repeating unit represented by (-4) an alkylene group) (b) a polyester resin, a polyurethane resin, which is dispersed or dissolved in water, Resin binder composed of at least one selected from acrylic resins (c) Surfactant (d) Charge containing a dispersion medium composed of at least water selected from water and an organic solvent miscible with water The antistatic self-adhesive polypropylene film according to claim 1, wherein the antistatic coating composition is applied.

    The invention according to claim 3 relates to the antistatic self-adhesive polypropylene film according to claim 1 or 2, wherein the rough surface layer has a sea-island structure.

  According to a fourth aspect of the present invention, the rough surface layer has an arithmetic average roughness (SRa) measured by a three-dimensional surface roughness meter of 0.05 to 0.16 μm and a ten-point average roughness (SRz) of 0. The antistatic self-adhesive polypropylene film according to any one of claims 1 to 3, wherein the antistatic self-adhesive polypropylene film is 50 to 2.00 µm.

  The invention according to claim 5 relates to the antistatic self-adhesive polypropylene film according to any one of claims 1 to 4, wherein the rough surface layer contains a propylene / α-olefin block copolymer.

The invention according to claim 6 relates to the antistatic self-adhesive polypropylene film according to any one of claims 1 to 5, wherein a surface specific resistance value of the antistatic layer is 1 × 10 ¹⁰ Ω / □ or less.

  According to the antistatic self-adhesive polypropylene film according to the invention of claim 1, the laminated polypropylene film in which the self-adhesive layer is integrally formed on one surface side of the base layer and the rough surface layer is integrally formed on the other surface side by coextrusion molding. Since the antistatic layer is formed on the surface of the rough surface layer, the number of manufacturing steps is small, and it can be manufactured very easily, and the production cost can be reduced. In addition, since there is no need to add an adhesive or a pressure-sensitive adhesive in order to impart tackiness, there is very little risk of contaminating the object to which the antistatic self-adhesive polypropylene film is stuck.

According to a second aspect of the present invention, in the first aspect, the antistatic layer comprises: (a) the formula (1) (wherein R ¹ and R ² are independently of each other hydrogen or carbon atoms of 1 to 4; A polycationic polythiophene comprising a repeating unit represented by an alkyl group, or R ¹ and R ² together represent an optionally substituted alkylene group having 1 to 4 carbon atoms; Conductive polymer containing polyanion (b) Resin binder (c) Surfactant (d) composed of at least one selected from polyester resin, polyurethane resin, acrylic resin dispersed or dissolved in water ) Since the antistatic coating composition containing a dispersion medium composed of at least water selected from water and an organic solvent miscible with water is applied, the adhesion between the antistatic layer and the rough surface layer is high. , It is excellent in antistatic performance. Moreover, there is little possibility of contaminating the target object and the self-adhesive layer to which the antistatic self-adhesive polypropylene film is adhered.

  According to a third aspect of the invention, in the first or second aspect, since the rough surface layer has a sea-island structure, the surface of the rough surface layer is in a gentle state, and the adhesion to the antistatic layer is extremely high.

  According to the invention of claim 4, in any one of claims 1 to 3, the rough surface layer has an arithmetic average roughness (SRa) measured by a three-dimensional surface roughness meter of 0.05 to 0.16 μm. In addition, since the ten-point average roughness (SRz) is 0.50 to 2.00 μm, blocking is difficult to occur when the film is rolled.

  According to the invention of claim 5, in any one of claims 1 to 4, since the rough surface layer contains a propylene / α-olefin block copolymer, it is easy to control the surface state of the rough surface layer. , Blocking is difficult to occur when the film is rolled. Further, the transparency of the antistatic self-adhesive polypropylene film is improved.

According to the invention of claim 6, in any one of claims 1 to 5, since the surface specific resistance value of the antistatic layer is 1 × 10 ¹⁰ Ω / □ or less, the antistatic performance is very excellent. It can also be used in fields where high antistatic properties are required, such as the fields of optical parts and electrical / electronic parts.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a sectional view showing an embodiment of the antistatic self-adhesive polypropylene film of the present invention.

  As shown in the embodiment of FIG. 1, the antistatic self-adhesive polypropylene film 10 of the present invention is formed by integrally forming a self-adhesive layer 12 on one surface side of a base layer 11 and a rough surface layer 13 on the other surface side by coextrusion molding. An antistatic layer 18 is formed on the surface of the rough surface layer 13 of the formed laminated polypropylene film 15.

  The base layer 11 is made of a resin mainly composed of polypropylene, and a homo-polypropylene, a random copolymer, a block copolymer, or the like made of only a single polypropylene is appropriately selected and used alone or in combination of two or more. used. In the random copolymer and block copolymer, the copolymerization monomer is not particularly limited, but ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, etc., which are olefins other than propylene, etc. And an α-olefin having 4 to 10 carbon atoms. Among these, ethylene is preferable from the viewpoint of cost, and an ethylene / propylene block copolymer and an ethylene / propylene random copolymer are used. These polypropylene resins are less expensive than the polyethylene terephthalate resin or the like constituting the conventional antistatic protective film, and it is very advantageous in terms of cost to form the base layer mainly composed of the polypropylene resin.

  The self-adhesive layer 12 is made of a resin mainly composed of polypropylene as described above, a hydrogenated styrene elastomer, or the like. By forming the self-adhesive layer, there is no need to separately apply an adhesive or add a tackifier to the surface of the film, and the number of production steps is reduced. Further, when the film is peeled off from the object to which the film is attached as in the case of a conventional antistatic film, an adhesive or the like does not remain on the surface to contaminate the object. Such a self-adhesive layer is preferably composed of a propylene / α-olefin random copolymer and a hydrogenated styrene-based elastomer because the adhesive strength, processability, and variation in adhesive strength with time are small. . Examples of the propylene / α-olefin random copolymer include a propylene-ethylene-1-butene random copolymer and a propylene-ethylene random copolymer. Examples of the hydrogenated styrene elastomer include hydrogenated styrene-butadiene copolymer, styrene-ethylene / butylene-ethylene copolymer, and styrene-ethylene / butylene-styrene copolymer.

  The rough surface layer 13 is formed mainly of the polypropylene resin as described above, but preferably contains a propylene / α-olefin block copolymer. The propylene / α-olefin block copolymer has high transparency and excellent appearance. For example, when the object to which the antistatic self-adhesive polypropylene film is attached is a product in the inspection process, the product inspection is performed with the film attached, so that the object is used for such an application. Suitable for This propylene / α-olefin block copolymer is a block copolymer containing a random copolymer component of propylene and an α-olefin. As the α-olefin, specific examples of ethylene or an α-olefin having 4 to 18 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene and 4-methyl. Examples include -1-pentene and 3-methyl-1-pentene, and these can be used alone or in combination of two or more.

  The rough surface layer 13 preferably has a sea-island structure. This sea-island structure is a phase-separated structure composed of a resin component constituting the sea phase as a matrix and a resin component constituting the island phase. If the rough surface layer has a sea-island structure, the surface of the rough surface layer is smooth, and there are no sharp protrusions as when a so-called anti-blocking agent is added to physically form the rough surface layer. Therefore, the adhesiveness with the antistatic layer 18 is extremely excellent. Furthermore, when the antistatic layer is formed, when a coating liquid containing the antistatic coating composition or the like is applied, a stable coating film with little partial variation can be formed even if the coating amount is reduced. .

  Constituent components having such a sea-island structure include polypropylene for the sea component, and propylene / α-olefin copolymer, low-density polyethylene and the like for the island component. The island component is more preferably a propylene copolymer due to the fineness of the rough surface, and more preferably a propylene / ethylene copolymer from the viewpoint of cost. The ratio of the island component in the rough surface layer having the sea-island structure is 1 to 15% by weight in view of peelability, surface roughness, and ease of coating when forming the antistatic layer on the surface of the rough surface layer. The amount is preferably 2 to 12% by weight, more preferably 3 to 10% by weight.

  In order to obtain a sea-island structure, it is possible to control the melt flow rate of the propylene / α-olefin random copolymer in the propylene / α-olefin block copolymer and the melt flow rate with polypropylene. That is, the difference in melt flow rate between the resin constituting the sea component and the resin constituting the island component needs to be within a predetermined range, and is preferably about 20 to 300. When the difference in melt flow rate between the resin constituting the sea component and the resin constituting the island component is extremely smaller than 20, the degree of surface roughness of the rough surface layer may be low and the peelability may be inferior, When the difference in melt flow rate is larger than 300, the fish eyes formed on the surface of the rough surface layer tend to become ugly. The melt flow rate can be measured in accordance with JIS-K-7210 (1999).

  Further, the rough surface layer 13 has an arithmetic average roughness (SRa) measured by a three-dimensional surface roughness meter of 0.05 to 0.16 μm and a ten-point average roughness (SRz) of 0.50 to 2. It is desirable to be 0.000 μm. When the arithmetic average roughness (SRa) is smaller than 0.05 μm, or when the ten-point average roughness (SRz) is smaller than 0.5 μm, the film is likely to be blocked. On the other hand, when the arithmetic average roughness (SRa) is larger than 0.16 μm or the ten-point average roughness (SRz) is larger than 2.00 μm, the adhesion with the antistatic layer formed on the surface of the rough surface layer Tends to decrease and the antistatic performance tends to be low. The arithmetic average roughness (SRa) and the ten-point average roughness (SRz) are values measured according to JIS-B-0601 using “SE-3500K” manufactured by Kosaka Laboratory Ltd.

  The antistatic layer 18 may contain an antistatic agent such as polyethylene oxide and polypropylene oxide, a conductive polymer, and the like. Particularly preferred is the following (a) conductive polymer (b) resin binder (c): It is formed by applying an antistatic coating composition containing a surfactant (d) dispersion medium. That is, the antistatic coating composition has the following formula (1):

(In the formula, R ¹ and R ² independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms, or R ¹ and R ² together may be optionally substituted 1 carbon atom. A conductive polymer comprising a polycationic polythiophene and a polyanion comprising a repeating unit represented by (-4) an alkylene group) (b) a polyester resin, a polyurethane resin, which is dispersed or dissolved in water, Resin binder composed of at least one selected from acrylic resins (c) Surfactant (d) Charge containing a dispersion medium composed of at least water selected from water and an organic solvent miscible with water It is preferable that the prevention coating composition is applied. According to the antistatic coating composition, the adhesiveness to the rough surface layer is good, and the antistatic coating property is extremely excellent. In addition, there is little contamination to the object or self-adhesive layer to which the antistatic self-adhesive polypropylene film is attached.

In the formula (1) of the conductive polymer, the alkyl group having 1 to 4 carbon atoms of R ¹ and R ² is preferably a methyl group, an ethyl group, or an n-propyl group. Examples of the alkylene group having 1 to 4 carbon atoms formed by combining R ¹ and R ² include a 1,2-alkylene group and a 1,3-alkylene group, preferably a methylene group, 1,2 -Ethylene group and 1,3-propylene group, and 1,2-ethylene group is particularly preferable. Moreover, a C1-C4 alkyl group may be substituted and a C1-C12 alkyl group, a phenyl group, etc. are mentioned as a substituent. Examples of the substituted alkylene group having 1 to 4 carbon atoms include 1,2-cyclohexylene group and 2,3-butylene group. As typical examples of such an alkylene group, 1,2-alkylene groups substituted with an alkyl group having 1 to 12 carbon atoms formed by R ¹ and R ² together are ethene, propene, hexene, octene. , Derived from 1,2-dibromoalkanes obtained by bromination of α-olefins such as decene, dodecene and styrene.

  Examples of the polyanion include polymeric carboxylic acids such as polyacrylic acid, polymethacrylic acid, and polymaleic acid, and polymeric sulfonic acids such as polystyrene sulfonic acid and polyvinyl sulfonic acid. These carboxylic acids and sulfonic acids may be copolymers of vinyl carboxylic acids and vinyl sulfonic acids with other polymerizable monomers such as acrylates and styrene. As the polyanion, polystyrene sulfonic acid is particularly preferable. The average molecular weight of these polyanions is preferably in the range of 1,000 to 2,000,000, more preferably in the range of 2,000 to 500,000, and even more preferably in the range of 10,000 to 200,000. It is a range.

  The resin binder is composed of at least one selected from a polyester resin, a polyurethane resin, and an acrylic resin that is dispersed or dissolved in water, and the content thereof is 100 parts by weight of the solid content of the conductive polymer (a). On the other hand, the solid content is preferably in the range of 20 to 5000 parts by weight, particularly preferably in the range of 100 to 1000 parts by weight. When the amount is less than 20 parts by weight, adhesion to the rough surface layer cannot be obtained, and when the amount is more than 5000 parts by weight, the antistatic performance tends to be not obtained.

  Surfactants include nonionic surfactants (eg, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl ethers, sorbitan fatty acid esters, fatty acid alkylolamides, etc.) and fluorine surfactants (eg, fluoroalkyl carboxylic acids, Perfluoroalkylbenzenesulfonic acid, perfluoroalkyl quaternary ammonium, perfluoroalkyl polyoxyethylene ethanol, etc.). The content of the surfactant is preferably in the range of 3 to 50 parts by weight, more preferably in the range of 5 to 30 parts by weight, based on 100 parts by weight of the solid content of the conductive polymer (a). When the amount is less than 3 parts by weight, the wettability to the rough surface layer is not obtained. When the amount is more than 50 parts by weight, the surfactant bleeds out from the antistatic layer, so that the self-formation when the film is rolled. There is a high possibility of contaminating the product to which the adhesive layer or film is attached.

  The dispersion medium is configured to include at least water selected from water and an organic solvent miscible with water, and a mixed solvent of water and an organic solvent miscible with water can be used. The organic solvent miscible with water is not particularly limited, but alcohols such as methanol, ethanol, 2-propanol, 1-propanol, and n-butanol; ethylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol Glycol ethers such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether; propylene glycols such as ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate; Propylene glycol mono Propylene glycol ethers such as chill ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, propylene glycol diethyl ether, dipropylene glycol diethyl ether; propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate And propylene glycol ether acetates such as dipropylene glycol monoethyl ether acetate; N-methylformamide, N, N-dimethylformamide, N-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide, acetone, acetonitrile, and mixtures thereof . The content of the dispersion medium is preferably in the range of 6000 to 200,000 parts by weight, and more preferably in the range of 10,000 to 100,000 parts by weight with respect to 100 parts by weight of the solid content of the conductive polymer (a). When the amount is less than 6000 parts by weight, the dispersibility of the conductive polymer is lowered. When the amount is more than 200000 parts by weight, the concentration of the conductive polymer becomes too dilute, and the coating film hardly exhibits antistatic performance. Examples of the antistatic coating composition as described above include polythiophene antistatic coating agents “Denatron P-502RG” and “Denatron P-515FA” manufactured by Nagase ChemteX Corporation.

  The film thickness of each layer constituting the antistatic self-adhesive polypropylene film of the present invention is, for example, about 3 μm for the rough surface layer, about 24 μm for the base layer, and about 3 μm for the self-adhesive layer. It can be changed as appropriate. The film thickness of the antistatic layer can be about 50 nm, and the film thickness is appropriately adjusted depending on the solid content concentration of the antistatic coating composition and the thickness when the coating film is formed. In addition, the antistatic self-adhesive polypropylene film is used for ordinary polypropylene films, including antioxidants, lubricants, colorants, and UV absorbers, in order to improve the film forming property, workability, workability, etc. Various additives, fillers and the like that can be blended can be blended to such an extent that the object of the present invention is not impaired.

  Next, a method for producing the antistatic self-adhesive polypropylene film 10 will be described. First, the laminated polypropylene film 15 is composed of the base layer 11, the self-adhesive layer 12 and the rough surface layer 13, and is obtained by coextrusion molding. The co-extrusion molding uses a conventionally known method such as an inflation method or a T-die method. For example, the raw material resins constituting the base layer 11, the self-adhesive layer 12 and the rough surface layer 13 are first processed by different extruders. Melted and kneaded. The melted raw material resin is extruded from a T die, and the resin constituting each layer is laminated inside the T die or at the T die opening and formed into a film by a cooling roll to obtain a laminated polypropylene film. By forming the laminated polypropylene film by such coextrusion molding, each layer can be molded at a time, and the number of manufacturing steps is smaller and the production cost can be reduced compared with the case where each layer is molded separately. .

  In addition, the laminated polypropylene film is preferably stretched in a uniaxial direction or a biaxial direction from the viewpoint of workability and workability, and in particular, has a low directionality in the strength and elongation of the film and obtains a uniform film. Therefore, the film is preferably stretched by a biaxial stretching method. As the stretching method, a conventionally known method is used, and a tenter method, a tubular method, a roll stretching method and the like are used. Specifically, for example, as described above, a laminated polypropylene film formed into a film by a cooling roll passes through heating rollers having different rotational speeds, and is a longitudinal direction (also referred to as a machine direction, MD) that is a traveling direction of the film. ). Then, after the film is stretched in the width direction, that is, in the direction orthogonal to the film traveling direction (transverse direction, also referred to as TD) by clips connected at both ends of the tenter, heat treatment is performed, and the film is taken up by a take-up roller. To obtain a laminated polypropylene film. In addition, kneading | mixing of raw material resin in the said extruder, the temperature of a cooling roller, a heating roller, the distance of longitudinal stretch, and the quantity of lateral stretch are selected suitably.

  Subsequently, the antistatic coating composition is applied to the surface of the rough surface layer 13 of the laminated polypropylene film 15 to form the antistatic layer 18, whereby the antistatic self-adhesive polypropylene film 10 of the present invention is obtained. Conventionally known methods are used as the coating method, and examples include gravure coating, roll coating, bar coating, spray coating, and dipping. In addition, as drying and curing conditions, conditions suitable for each application method are selected. As an example, when using a roll coating method, the conditions are usually performed at 60 to 120 ° C. for 5 to 60 seconds. It is preferable that

The antistatic self-adhesive polypropylene film 10 preferably has a surface resistivity of the antistatic layer 18 of 1 × 10 ¹⁰ Ω / □ or less. Even when used for optical parts and electric / electronic parts as described above, which require high antistatic performance and are sensitive to electrostatic damage, sufficiently satisfactory antistatic performance can be obtained. On the other hand, when the surface specific resistance value is larger than 1 × 10 ¹⁰ Ω / □, it is suitable for use mainly in the packaging of textiles used for the purpose of preventing adhesion of dust, dirt, etc. and in the food field. It can be said.

  Furthermore, the antistatic self-adhesive polypropylene film 10 preferably has an adhesive strength to an acrylic plate in accordance with the method described in JIS-Z-0237 (2000) of 8 to 200 g / 25 mm. When the adhesive strength is greater than 200 g / 25 mm, the film is likely to be blocked. In particular, when the antistatic layer is formed, it is extremely difficult to feed out the laminated polypropylene film wound up in a roll shape, and the workability and workability may be reduced. When the adhesive strength is less than 8g / 25mm, that is, when the surface roughness of the rough surface layer is too rough, the surface resistivity increases, and the antistatic performance is not sufficient for the optical parts and electric / electronic parts fields. There is.

Next, examples of the antistatic self-adhesive polypropylene film of the present invention will be described.
[Example 1]
As shown in Table 1 below, the raw material resin for the laminated polypropylene film is a propylene / α-olefin block copolymer (A-1) and a propylene homopolymer (B) as a rough surface layer, and a propylene resin composition as a base layer. The product (C) and the propylene homocopolymer (B), and the hydrogenated styrene elastomer (D-1) and the propylene / α-olefin random copolymer (E) were used as the self-adhesive layer. Table 2 shows the blending ratio (% by weight) of each layer.

  The raw material resins constituting each layer are blended so as to have the above-mentioned blending ratio, and each raw material resin is extruded for a base layer (diameter 60 mm), and each extruder for a rough surface layer and a self-adhesive layer (both To 30 mm), extruded from a 250 ° C. T-die, and cooled with a 30 ° C. cooling roll to produce an original sheet. The original fabric sheet was stretched 5 times in the machine direction (MD) with a heating roll at 110 ° C. and stretched 8 times in the transverse direction (TD) with a tenter oven at 150 ° C. to obtain a laminated polypropylene film.

  Next, the antistatic layer is obtained by diluting a polythiophene antistatic coating agent (Nagase ChemteX Co., Ltd. polythiophene antistatic coating agent “Denatron P-502RG”), which is an antistatic coating composition, five times with water. , No. The surface of the rough surface layer was coated with a wire bar No. 4 (Wet 9.14 μm) and dried in a gear oven at 80 ° C. for 30 seconds to obtain an antistatic self-adhesive polypropylene film of Example 1.

[Examples 2 to 8]
First, the production of the laminated polypropylene film was carried out in the proportions (% by weight) of the raw material resins constituting the rough surface layer, the base layer and the self-adhesive layer. Examples 2 to 5 were as in Table 2 and Examples 6 to 8 were Adjustments were made so that the following Table 3 was obtained. Other than that was carried out similarly to Example 1, and obtained each laminated polypropylene film.

  Next, regarding the formation of the antistatic layer on the surface of the rough surface layer of the laminated polypropylene film, in Examples 2 to 8, only the polythiophene antistatic coating is used as the antistatic coating composition constituting the antistatic layer. An antistatic self-adhesive polypropylene film of Examples 2 to 8 was obtained in the same manner as in Example 1 except that the agent (polythiophene antistatic coating agent “Denatron P-515FA” manufactured by Nagase ChemteX Corporation) was used. . The resin binder in the polythiophene antistatic coating agent “Denatron” is the above-mentioned “P-502RG” is polyester-based, and “P-515FA” is polyurethane-based.

  Subsequently, for Examples 1 to 8 obtained by the above method, arithmetic average surface roughness (μm) and ten-point average roughness (μm), surface resistivity (Ω / □), adhesive strength (g / 25 mm), and the peelability, the structure of the rough surface layer, the adhesion, and the contamination of the object were evaluated. Moreover, comprehensive evaluation was performed based on these results. Details of the measurement method and evaluation will be described below.

[Arithmetic average surface roughness (SRa) and ten-point average roughness (SRz)]
The arithmetic average surface roughness (μm) and ten-point average roughness (μm) are based on JIS-B-0601 using a three-dimensional surface roughness meter (“SE-3500K” manufactured by Kosaka Laboratory Ltd.). The measurement was performed with a diamond needle of 0.7 mN and a cutoff of 0.25 mm.

[Peelability]
The antistatic self-adhesive polypropylene films of Examples 1 to 8 were first cut into 20 mm width and 50 mm width. A self-adhesive layer of an antistatic self-adhesive polypropylene film cut to a width of 20 mm for each example was bonded to the surface of the antistatic layer of the film cut to a width of 50 mm with a load of 2 kg. A load of 2 kg / 10 cm 2 was applied and held for 24 hours, and then held for 30 minutes in an atmosphere of 23 ° C. and 50% RH. This was peeled off, and the peeling state of the self-adhesive layer with respect to the antistatic layer was visually confirmed. Furthermore, in order to investigate the peelability with respect to the rough surface layer of the self-adhesive layer, the peelability was confirmed in the same manner as described above using each laminated polypropylene film produced in Examples 1-8. The results are shown in Tables 4 and 5 below. In the table, “◎” when the film can be peeled without resistance, and the peeled film can be used without any problem, “○” when the film has a feeling of resistance but can be peeled without any problem, and the peeled film can be used. When the feeling is strong but it can be peeled off or difficult to peel off, it is indicated by “Δ”.

[Surface specific resistance]
The surface specific resistance value (Ω / □) was measured according to JIS-K6911 using “High Lester UP (MCP-HT450)” manufactured by Mitsubishi Chemical Corporation.

[Adhesive strength]
The measurement of adhesive strength (g / 25 mm) is based on JIS-Z-0237 (2000) using a mirror-like acrylic plate (“Acrylite L001” 3 mm plate manufactured by Mitsubishi Rayon Co., Ltd.) instead of SUS304. It went as follows. The self-adhesive layer side of an antistatic self-adhesive polypropylene film having a width of 25 mm and a length of 200 mm was matched with an acrylic plate, and was adhered uniformly under a constant pressure using a rubber roller with a load of 2 kg. -Acrylic board was fixed by holding in an atmosphere of 50 RH% for 24 hours, and the strength when one end of the film was peeled 180 degrees at a constant speed of 300 mm / min was measured.

[Rough surface layer structure]
The structure of the rough surface layer was confirmed as follows. The film of each example was embedded in an epoxy resin, and a cross section perpendicular to the film surface direction was cut out as an ultrathin section using an ultramicrotome. The structure of the rough surface layer was dyed and observed with a scanning electron microscope (SEM). SEM used “JSM-5400LV” manufactured by JEOL Datum Co., Ltd. In Tables 4 and 5 below, the structure of the rough surface layer is a sea-island structure, “Yes”, and the structure that is not a sea-island structure is “No”.

[Adhesion]
The adhesion was evaluated by a cross-cut tape method according to JIS-K-5400. In Tables 4 and 5 below, “◎” indicates 10 points, “◯” indicates 8 points, and “Δ” indicates 6 points or less.

[Evaluation of target contamination]
Evaluation of object contamination was performed as follows. First, the surface of the self-adhesive layer side of the antistatic self-adhesive polypropylene film of Examples 1 to 8 was brought into close contact with the corona-treated surface side of a PET film (“FE2001” manufactured by Futamura Chemical Co., Ltd.), and 23 ° C. and 50%. It was kept for 2 weeks under a load of ² kg / cm ² in an atmosphere of RH. Next, the antistatic self-adhesive polypropylene film was peeled from the PET film, and the wetting index was measured according to JIS-K-6768 on the corona-treated surface of the PET film.

  Evaluation of contamination of the PET film as an object was performed as follows. Usually, the wetting index of the corona-treated surface of the PET film is 56 dyne or more, whereas the wetting index of the non-corona-treated surface of the film is 41 dyne. Therefore, if the wetting index of the corona-treated surface of the PET film after peeling off the antistatic self-adhesive polypropylene film of each example is 56 dyne or more, there is no contamination of the PET film as an object. As the wetting index approaches 41 dyne, it was determined that the effect of the corona treatment was reduced and the object was contaminated. In Tables 4 and 5 below, the PET film has a wetting index of 56 dyne or more, “ｄ”, 50 to 55 dyne, “◯”, and 42 to 49 dyne, “Δ”.

[Comprehensive evaluation]
Comprehensive evaluation considered the above-mentioned evaluation and measurement, and evaluated the suitability as a chargeable self-adhesive polypropylene film. In Tables 4 and 5 below, among the antistatic self-adhesive polypropylene films of Examples 1 to 8, “A” is extremely excellent, “B” is excellent, and “C” is otherwise. did. The measurement results and evaluation results of Examples 1 to 8 are shown in Tables 4 and 5 below.

As is clear from Tables 4 and 5, the antistatic self-adhesive polypropylene films of Examples 1 to 5 have a surface resistivity of 4 × 10 ⁷ (Ω / □) or less and excellent antistatic properties, There was almost no contamination with respect to a target object, and peelability, adhesiveness, etc. were also favorable. That is, as an antistatic self-adhesive polypropylene film, each performance was highly evaluated and balanced, and the overall evaluation was also good. Further, in Examples 1 and 5, the surface resistivity values are very small values of 8 × 10 ⁵ (Ω / □) and 1 × 10 ⁶ (Ω / □), respectively, and extremely high antistatic performance is exhibited. It was found to be an antistatic self-adhesive polypropylene film. In addition, extremely excellent results were obtained in the overall evaluation.

It is sectional drawing which shows one Example of the antistatic self-adhesive polypropylene film of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Antistatic self-adhesive polypropylene film 11 Base layer 12 Self-adhesive layer 13 Rough surface layer 15 Laminated polypropylene film 18 Antistatic layer

Claims (6)

  An antistatic layer is formed on the surface of the rough surface layer of the laminated polypropylene film in which a self-adhesive layer is integrally formed on one surface side of the base layer and a rough surface layer is integrally formed on the other surface side by coextrusion molding. Antistatic self-adhesive polypropylene film. The antistatic layer comprises: (a) the following formula (1)

(In the formula, R ¹ and R ² independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms, or R ¹ and R ² together may be optionally substituted 1 carbon atom. A conductive polymer comprising a polycationic polythiophene and a polyanion comprising a repeating unit represented by (-4) an alkylene group) (b) a polyester resin, a polyurethane resin, dispersed or dissolved in water, Resin binder composed of at least one selected from acrylic resins (c) Surfactant (d) Charging containing a dispersion medium composed of at least water selected from water and an organic solvent miscible with water The antistatic self-adhesive polypropylene film according to claim 1, wherein the antistatic coating composition is applied.   The antistatic self-adhesive polypropylene film according to claim 1 or 2, wherein the rough surface layer has a sea-island structure.   The rough surface layer has an arithmetic average roughness (SRa) measured by a three-dimensional surface roughness meter of 0.05 to 0.16 μm and a ten-point average roughness (SRz) of 0.50 to 2.00 μm. The antistatic self-adhesive polypropylene film according to any one of claims 1 to 3.   The antistatic self-adhesive polypropylene film according to any one of claims 1 to 4, wherein the rough surface layer contains a propylene / α-olefin block copolymer. The antistatic self-adhesive polypropylene film according to any one of claims 1 to 5, wherein a surface specific resistance value of the antistatic layer is 1 × 10 ¹⁰ Ω / □ or less.

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