JP4318535B2 - Cover film base material for electronic component carrier tape - Google Patents

Description

  The present invention relates to a base material for a cover film used as a cover material for a carrier tape for storing electronic components and the like.

  Along with the downsizing of electronic devices, the electronic parts used are also downsizing. In such an electronic device assembly process, small electronic components are automatically mounted on a printed circuit board, and the small electronic components are taped and packaged so that they can be sequentially supplied.

  As such taping packaging, an electronic component carrier tape is often used. For example, as disclosed in Patent Document 1, the electronic component carrier tape includes a carrier tape main body in which recesses for storing electronic components are formed at regular intervals, and both end portions along the length direction on the upper surface of the carrier tape main body. Is composed of a heat-sealed cover film.

  As this cover film, a base material layer made of a biaxially stretched film such as a biaxially stretched polyester film, an intermediate layer made of polyolefin resin provided on the base material layer, and a heat seal layer provided on the intermediate layer In general, a heat seal layer having antistatic performance is used for the purpose of protecting small electronic components from static electricity. As the intermediate layer, a resin having a heat seal ability and a bilayer configuration of a biaxially stretched polyester film and a heat seal layer is also known.

  At the time of mounting, the cover film is peeled off at high speed and the small electronic component is taken out. However, in order to peel the cover film uniformly without the carrier tape vibrating, it is preferable that there is a thick layer of polyolefin resin.

As the heat seal layer of this cover film, ethylene copolymer resins such as ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-acrylic resin copolymer, ethylene-acrylic resin copolymer, polyvinyl chloride Resins, ionomer resins, polyester resins, polyurethane resins and the like are used. When the heat sealability at a low temperature and high speed is required, there is a problem that blocking occurs when the cover film wound up in a roll shape is stored.
JP 2001-106256 A

  This invention is made | formed in view of the said situation, The solution subject is eliminating a blocking and providing the base material of the cover film which has the outstanding characteristic.

  As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be easily solved by a film having a specific configuration, and have completed the present invention.

That is, the gist of the present invention is a base material used as a cover film for an electronic component carrier tape, which is obtained by applying a coating liquid containing an antistatic agent to a longitudinally uniaxially stretched film . A base material for a cover film, wherein an antistatic layer having an adhesive strength of 2.4 N / cm or less is provided on one surface of a biaxially stretched polyester film. Exist.

Hereinafter, the present invention will be described in detail.
The polyester used in the biaxially stretched polyester film of the present invention is terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, 4,4′-diphenyldicarboxylic acid, 1,4-cyclohexyldicarboxylic acid And melt polycondensation of dicarboxylic acid or its ester with ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol Polyester produced. Polyesters composed of these acid components and glycol components can be produced by arbitrarily using a commonly used method. For example, a transesterification reaction between a lower alkyl ester of an aromatic dicarboxylic acid and a glycol, or a direct esterification of an aromatic dicarboxylic acid and a glycol, to form a substantially bisglycol of an aromatic dicarboxylic acid A method is employed in which an ester or a low polymer thereof is formed and then polycondensed by heating under reduced pressure. Depending on the purpose, an aliphatic dicarboxylic acid may be copolymerized.

  Typical examples of the polyester of the present invention include polyethylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, and the like. It may be a polymerized polyester and may contain other components and additives as necessary.

  These polyesters include inorganic particles such as calcium carbonate, kaolin, silica, aluminum oxide, titanium oxide, alumina, and barium sulfate, organic particles such as acrylic resin and guanamine resin, and catalysts for the purpose of improving film runnability. Precipitated particles in which the residual is made into particles can be contained. The particle size and amount of these particles can be appropriately determined according to the purpose. In addition, various stabilizers, lubricants, antistatic agents, and the like can be added as appropriate.

  The film forming method of the present invention may be a generally known film forming method and is not particularly limited. For example, an unstretched film obtained by melt extrusion from an extruder is first stretched 2 to 6 times at 60 to 120 ° C. by a roll stretching method to obtain a uniaxially stretched polyester film, and then in the tenter The stretching direction may be a sequential biaxial stretching film-forming method in which stretching is performed 2 to 6 times at 80 to 130 ° C. in a direction perpendicular to the stretching direction, and further heat treatment is performed at 150 to 250 ° C. for 1 to 600 seconds. Moreover, the simultaneous biaxial stretching film-forming method of extending | stretching an unstretched film to the length and width simultaneously, and heat-processing with a tenter after that may be sufficient. The film forming method of the present invention may be a multilayer film using a plurality of extruders.

  The polyester film of the present invention preferably has a thickness of 9 to 75 μm.

  In the present invention, an antistatic layer is provided. If a low molecular weight anionic antistatic agent that is widely used is used as an antistatic agent, the antistatic agent is transferred to the opposite surface in a state where the polyester film is wound in a roll shape. In addition, the adhesion with the polyolefin resin may be hindered, or when the cover film is rolled up after processing, the antistatic agent may be transferred to the heat seal layer, resulting in fluctuations in heat seal force. In order to prevent such transfer of the antistatic agent, a high molecular weight anionic compound is preferable. In the case of a cationic antistatic agent, it is desirable to use a high molecular weight cationic compound.

The surface resistivity of the antistatic layer is preferably 1 × 10 ¹³ Ω / □ or less, and preferably 1 × 10 ¹² Ω / □ or less. When the surface specific resistance exceeds 1 × 10 ¹³ Ω / □, the antistatic performance is inferior, and problems in the process may not be improved.

  As described above, the antistatic layer of the present invention is characterized by little or no transfer of the antistatic agent, but at the same time, it should not block with the heat seal layer. As a measure for preventing blocking, the peel strength of the adhesive tape from the cello tape (registered trademark) is 2.4 N / cm or less, preferably 2.0 N / cm or less, and more preferably 1.7 N / cm or less. When this value exceeds 2.4 N / cm, the effect of improving the blocking property is not obtained.

  Examples of the antistatic agent satisfying such characteristics include a compound having a quaternary ammonium base. This refers to a compound having a component containing a quaternary ammonium base in the main chain or side chain in the molecule. Examples of such constituents include, for example, a pyrrolidinium ring, an alkylamine quaternized product, a copolymer of these with acrylic acid or methacrylic acid, an N-alkylaminoacrylamide quaternized product, a vinylbenzyltrimethylammonium salt, 2-hydroxy 3-methacryloxypropyltrimethylammonium salt etc. can be mentioned. Further, these may be combined or copolymerized with other resins. In addition, examples of anions that serve as counter ions for these quaternary ammonium salts include ions such as halogen, alkyl sulfate, alkyl sulfonate, and nitric acid.

  In the present invention, the compound having a quaternary ammonium base is preferably a polymer compound. When the molecular weight is too low, there is a concern that the antistatic agent is transferred from the antistatic layer to the heat seal layer and the desired heat seal effect is not achieved. In order not to cause such a problem, it is desirable that the number average molecular weight of the compound having a quaternary ammonium base is usually 1000 or more, further 2000 or more, and particularly 5000 or more. On the other hand, when such a compound has a molecular weight that is too high, it may cause problems such as the viscosity of the coating solution becoming too high. In order not to cause such a problem, the number average molecular weight is preferably 500,000 or less.

  In order to make the peel strength of the adhesive tape with the adhesive not more than 2.4 N / cm, not only the selection of the antistatic agent is important, but in order to make the peel strength smaller, polyolefin resin and / or fluorine resin. It is effective to mix

  As the polyolefin-based resin and the fluorine-based resin, those having little transfer, preferably those having no transfer, are blended similarly to the antistatic agent. As polyolefin etc., the compound which has the compound as described in following (1)-(5) as a basic skeleton can be mentioned, for example. Polyolefin or the like is used after being dissolved or dispersed in water.

(1) Waxes, resins, and rubber-like materials composed of homo- or copolymers of α-olefin unsaturated hydrocarbons such as ethylene, propylene, 1-butene, and 4-methyl-1-pentene. Examples of the corresponding compound include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, and propylene-1-butene copolymer. A polymer etc. are mentioned.

(2) A rubbery copolymer of two or more of the above α-olefins and a conjugated or non-conjugated diene. Applicable compounds include, for example, ethylene-propylene-budadiene copolymer, ethylene-propylene-dicyclopentadiene copolymer, ethylene-propylene-ethylidene norbornene copolymer, ethylene-propylene-1,5-hexadiene copolymer. And isobutene-isobrene copolymer.

(3) A copolymer of the above α-olefin and a conjugated or non-conjugated diene. Examples of the corresponding compound include an ethylene-butadiene copolymer and an ethylene-ethylidene norbornene copolymer.

(4) A copolymer of the above α-olefin (especially ethylene) and vinyl acetate and a complete or partially saponified product thereof.

(5) A graft polymer obtained by grafting the above conjugated or nonconjugated diene, vinyl acetate or the like onto the above-mentioned α-olefin homopolymer or copolymer, and a complete or partially saponified product thereof.

  In order to dissolve or disperse the above-mentioned polyolefin or the like in water and stabilize the composition so that aggregation does not occur, a conventionally known surfactant can be used in combination, or a hydrophilic polymer such as a water-soluble polyester can be used. A method of coexisting at the time of dispersion is also effective. Also, by introducing a vinyl compound having a hydrophilic group such as a carboxylic acid group, a sulfonic acid group, an amino group, a polyether, an alkylolamide group or a salt thereof into a skeleton such as a polyolefin by copolymerization or grafting. Water-solubilization or water-dispersion can also be facilitated.

  Particularly preferred polyolefins, etc. are the so-pressed or self-emulsifying type polyolefins dispersed or dissolved in water without introducing a surfactant or other hydrophilic polymer by introducing the above-mentioned vinyl compound having a hydrophilic group. Etc.

  Fluorine-containing polymer components include fluoroolefin copolymer resins using vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, etc. as monomers, and hydroxy group-containing fluororesin copolymers. Examples thereof include a fluorine-based copolymer resin obtained by graft polymerization of a polymer and a (meth) acrylic acid ester compound or another monomer, and a vinyl polymer having a perfluoroalkyl group. Of these, fluoroolefin copolymer resins are preferred. Specifically, about 20 to about 60 mol% of fluorinated vinyl monomers such as chlorotrifluoroethylene, hexafluoropropylene, tetrafluoroethylene or vinylidene fluoride, vinyl acetate, vinyl propionate, vinyl cyclohexanecarboxylate, etc. Specific examples thereof include copolymer resins composed of 30 to 70 mol% of various carboxylic acid vinyl esters and 5 to 35 mol% of maleic acid monoester and fumaric acid monoester.

  The polymer containing fluorine in the molecule is preferably used as an aqueous dispersion as a coating liquid. For example, the aqueous dispersion may be obtained by neutralizing a part of the carboxyl group with a basic compound, and then using an aqueous medium. There are a method of dispersing in, a method of emulsion polymerization in an aqueous medium using an anionic, cationic, amphoteric and nonionic surfactant as an emulsifier.

  In the present invention, in addition to the antistatic agent, a polyolefin-based resin and / or a fluorine-based resin may be blended as the antistatic layer, but the antistatic layer may further contain water-soluble or water other than the above as necessary. One or two or more dispersible binder resins may be used in combination to improve coatability. Examples of the binder resin include polyester, polyurethane, acrylic resin, vinyl resin, epoxy resin, amide resin, and polyvinyl alcohol. In these, each skeleton structure may have a composite structure substantially by copolymerization or the like. Examples of the binder resin having a composite structure include acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft polyester, and vinyl resin graft polyurethane.

  Further, in the present invention, the antistatic layer may contain a crosslinking reactive compound. The crosslinkable compound can prevent transferability by a crosslink reaction with the functional group of the component compound constituting the antistatic layer. Addition of a crosslinking agent improves the adhesion (blocking), water resistance, solvent resistance and mechanical strength of the coating layer. Examples of the crosslinking agent used in the present invention include a melamine crosslinking agent and an epoxy crosslinking agent. Examples of the melamine-based crosslinking agent include methoxymethylated melamine and butoxymethylated melamine which are alkylol or alkoxyalkylolated melamine compounds, and those obtained by co-condensing urea or the like with a part of melamine can also be used. The epoxy-based crosslinking agent may be a compound having an epoxy group having a water solubility or a water solubilization rate of 50% or more.

  The antistatic layer of the present invention may contain at least one additive such as an antifoaming agent, a coating property improver, a thickener, an organic lubricant, organic particles, and inorganic particles, if necessary. Good.

  The antistatic layer has a dry thickness of usually 0.003 to 1.5 μm, preferably 0.005 to 0.5 μm. If the thickness of the antistatic layer is less than 0.003 μm, sufficient performance may not be obtained, and if it exceeds 1.5 μm, blocking between films tends to occur.

  As described above, as described above, the biaxially stretched polyester film is provided with an intermediate layer made of a polyolefin resin as described above. For this lamination, an economically advantageous extrusion laminating method is adopted. ing. However, the adhesion between the two is poor, and there is a general method in which an anchor coat agent is coated during extrusion lamination and then extrusion lamination. As this anchor agent, there are isocyanate agents such as isocyanate-based, polyethyleneimine-based, organic titanate-based, polybutadiene-based, etc., which are applied using an organic solvent in the laminating process and dried in a drying furnace. For this reason, the operating cost of a drying furnace, the ventilation equipment for improving work environment, etc. are required, and there exists a problem which becomes expensive.

  As a method for solving this problem, there is a method in which a primer treatment is performed during the formation of a biaxially stretched polyester film, but the antistatic layer of the present invention can exhibit an effect of suppressing blocking with the primer layer provided during the film formation. .

As a coating agent for the primer coat layer, an organic silane compound is preferable. For example, monoalkoxysilane, dialkoxysilane, trialkoxysilane, tetraalkoxysilane, and the like can be used, and even a mixture or condensation reaction product thereof can be used. Good. Typical examples of the coating agent include silane coupling agents represented by the following general formula (1) or (2).
XR ² Si (OR ¹ ) ₃ (1)
(XR ² ) (YR ³ ) Si (OR ¹ ) ₂ (2)
(In the above formula, R ¹ is an alkyl group such as a methyl group or an ethyl group or a substituted alkyl group such as a methoxyalkyl group, R ² and R ³ are each independently an alkylene group such as a propylene group, And Y are each independently an organic functional group)

  In the above general formula, the organic functional group of X or Y is preferably an amino group, epoxy group, vinyl group, hydroxyl group, carboxyl group, epoxycyclohexyl group, mercapto group or glycidyl group. Also. The organic functional group may be a substituted amino group such as N-β (aminoethyl) amino group or a substituted one such as polyethyleneimine.

  Specific examples of the silane coupling agent having an organic functional group include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, Preferred examples include N-β (aminoethyl) γ-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-mercaptopropyltrimethoxysilane and the like. These may be used alone or in combination of two or more. If necessary, a mixture or a condensate containing an alkoxysilane having no functional group may be used.

  The primer coat layer in the present invention can be used after being diluted with an alcohol solvent, but is preferably water-based, and in this case, various surfactants can be blended for the purpose of improving coatability. . Further, if necessary, one or more water-soluble or water-dispersible binder resins may be used in combination to improve coatability. Examples of the binder resin include polyester, polyurethane, acrylic resin, vinyl resin, epoxy resin, amide resin, and polyvinyl alcohol. In these, each skeleton structure may have a composite structure substantially by copolymerization or the like. Examples of the binder resin having a composite structure include acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft polyester, and vinyl resin graft polyurethane. In addition, inorganic particles or organic particles may be added to the coating agent of the present invention for the purpose of ensuring the slipperiness of the coated surface.

  As a method of coating the polyester film with an antistatic agent, for example, a coating technique as shown in “Coating system” published by Yuji Harasaki, Tsuji Shoten, published in 1979 can be used. Specifically, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, cast coater, spray coater, curtain coater, calendar coater And techniques such as an extrusion coater and a bar coater.

  According to the present invention, in a carrier tape that stores electronic components and the like, blocking that occurs when a cover film used as a cover material is stored can be suppressed.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, the evaluation method and the processing method of a sample in an Example and a comparative example are as follows. Further, “parts” in Examples and Comparative Examples represents “parts by weight”.

(1) Method for Measuring Intrinsic Viscosity [η] (dl / g) of Polymer 1 g of polymer is dissolved in 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio), and 30 ° C. using an Ubbelohde viscometer. Measured in

(2) Measuring method of peel strength with cello tape adhesive Adhesive tape (Nichiban cello tape (registered trademark)) is affixed to the antistatic coating surface of the base film, and measured at 23 ° C. and 50% RH for 30 minutes. After humidity control, the peeling load when peeling the adhesive tape at an angle of 180 degrees at a speed of 300 mm / min was measured with an Intesco tensile tester.

(3) Measuring method of surface specific resistance value After using a high resistance measuring instrument (HP4339B) and measuring electrode (HP16008B) manufactured by Hewlett-Packard Japan, the sample was sufficiently conditioned in a measurement atmosphere of 23 ° C. and 50% RH, The surface specific resistance value of the coating layer after 1 minute at an applied voltage of 100 V was measured.

The aqueous coating liquid raw materials used in the following examples and comparative examples are as follows.
Antistatic agent (A1): polydiallyldimethylammonium chloride (average molecular weight: about 30000)
Aqueous resin (B1): partially saponified polyvinyl alcohol (degree of saponification: about 88 mol%)
Aqueous resin (B2): Oxidized polyethylene aqueous dispersion (John Wax manufactured by Johnson Polymer Co., Ltd.)
Water-based resin (B3): Fluorine-based resin water dispersion release agent (Mcclave made by GSI Creos)
Crosslinking agent (C): Methoxymethylol melamine (Dainippon Ink Co., Ltd., Becamine J101)

The raw material composition of the aqueous coating liquid used in Examples and Comparative Examples was as follows.
Coating solution (1): An aqueous solution having a concentration of 2.0% was prepared so that the antistatic agent (A1) was 65 parts, the aqueous resin (B1) was 5 parts, and the crosslinking agent (C) was 30 parts.
Coating solution (2): An aqueous solution having a concentration of 3.0% was prepared so that the antistatic agent (A1) was 40 parts, the aqueous resin (B2) was 30 parts, and the crosslinking agent (C) was 30 parts.
Coating solution (3): An aqueous solution having a concentration of 2.5% was prepared so that the antistatic agent (A1) was 50 parts, the aqueous resin (B3) was 20 parts, and the crosslinking agent (C) was 30 parts.
Coating solution (4): An aqueous solution having a concentration of 3.0% was prepared so that the antistatic agent (A1) was 40 parts, the aqueous resin (B1) was 40 parts, and the crosslinking agent (C) was 20 parts.

A polyester chip having an intrinsic viscosity of 0.66 containing 0.18 part of amorphous silica having an average particle size of 2.5 μm was obtained by a usual melt-in polymerization method. This chip is dried, moisture is reduced to 50 ppm or less, melted at 295 ° C., melt-extruded on a cooled drum to obtain an amorphous sheet, and then stretched 3.5 times vertically at 85 ° C. to 100 ° C. Thus, a longitudinally uniaxially stretched film was obtained. The coating liquid (1) is coated on a longitudinally uniaxially stretched film with a gravure coater by 5 μm, stretched 4.0 times horizontally in an atmosphere of 90 to 120 ° C., and then heat-treated at 235 ° C. to obtain a 25 μm thick biaxially stretched polyester. A film was obtained. This film had a surface resistance of 3 × 10 ⁹ Ω / □ and was a film that could prevent charging. Moreover, the peeling force with Cellotape (registered trademark) was 2.3 N / cm.

A polyester film was obtained in exactly the same manner except that the coating liquid in Example 1 was changed to the above-mentioned coating liquid (2). This film had a surface resistance of 4 × 10 ⁹ Ω / □ and could be prevented from being charged. Moreover, the peeling force with the cellophane tape was 1.7 N / cm.

A polyester film was obtained in the same manner except that the coating solution in Example 1 was changed to the coating solution (3) described above. This film had a surface resistance of 2 × 10 ⁹ Ω / □ and was a film that could be antistatic. Moreover, the peeling force with the cellophane was 2.3 N / cm.

In the same manner as in Example 2, the surface of the longitudinally uniaxially stretched film was coated with the coating liquid (2), and the other surface was coated with N-β (aminoethyl) γ-aminopropyltrimethoxysilane 8 as a primer layer. A 5% ethanol solution is coated with a gravure coater, stretched 4.0 times horizontally in an atmosphere of 90 to 120 ° C., and then heat treated at 235 ° C. to form a biaxially stretched polyester film having a film thickness of 25 μm in a roll shape. I rolled it up. This film had a surface resistance of 4 × 10 ⁹ Ω / □ and could be prevented from being charged. Moreover, the peeling force with the cellophane tape was 1.7 N / cm. Although this film had a primer layer, it was free from blocking or charging during unwinding and was a good substrate.

(Comparative Example 1)
In Example 1, the antistatic layer was not coated, and a 25 μm biaxially stretched polyester film was obtained. This was not preferred as a base material for the cover film because it had no antistatic ability.

(Comparative Example 2)
A polyester film was obtained in exactly the same manner except that the coating solution in Example 1 was the coating solution (4) described above. The surface resistance of this film was 1 × 10 ⁹ Ω / □, and it was an antistatic film. Moreover, the peeling force with the cellophane tape was 2.8 N / cm. Although this film has an antistatic ability, a blocking phenomenon was observed with the heat seal layer, which was not preferable.

(Comparative Example 3)
In Example 4, the coating liquid (2) was not applied, and a film having only a single-sided primer layer was obtained. This was a film having worse winding properties than Comparative Example 1.

The film of the present invention can be suitably used as a cover film used as a cover material in a carrier tape for storing electronic components and the like.

Claims (1)

A base material used as a cover film for an electronic component carrier tape, which is obtained by applying a coating liquid containing an antistatic agent to a longitudinally uniaxially stretched film, and has an adhesive force of 2.4 N / cm with the adhesive tape. A base material for a cover film, comprising the following antistatic layer provided on one surface of a biaxially stretched polyester film.