JPH0525302A - Release film having antistatic properties - Google Patents

Abstract

PURPOSE:To obtain the subject film excellent in long-term adhesion of a coating film, antistatic properties and release properties by forming a water-soluble organosilane primer coating layer, a complex-forming silane antistatic layer and a curable silicone release layer on the surface of a polyester film. CONSTITUTION:After forming a primer coating layer on one or both sides of a polyester film by application of an aqueous solution containing a water-soluble organosilane compound (e.g. gamma-aminopropyltrimethoxysilane) and a nonionic surfactant, an isopropyl alcohol solution containing a tetra-alkoxysilane constituting a charge-transfer complex together with a metal compound (e.g. magnesium acetate) and/or its partly hydrolyzed material is applied thereto to form an antistatic layer. A toluene solution of a curable silicone such as isocyanatosilicone composed of a mixture of silanetriisocyanate with polydimethylsiloxane is then further applied thereon and dried at 120 deg.C to form a release layer. Thereby, the objective release film having antistatic properties can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film having antistatic properties, and more specifically, it secures long-term coating adhesion, has stable antistatic properties, and has excellent release properties. Releasing film

[0002]

2. Description of the Related Art In recent years, with the wide application of adhesives and adhesives, the use of paper and film coated with silicone for protecting the adhesive surface has been remarkably increasing.
It has become an indispensable protective layer for masking tapes and dicing tapes in electrical equipment. Among plastics, rubbers, etc., especially for molding vinyl chloride, epoxy, polyurethane, polyester resin, etc., silicone coated paper or film is used to maintain moldability until curing reaction and cooling and curing. ing.

The silicones used in these silicone-coated papers and films are generally required to prevent surface tack and to minimize backside migration of the silicone. Therefore, as a silicone, polydimethylsiloxane having an -OH group at the terminal and
Polydimethylsiloxane (Hydroxypolydimethylsiloxane) having an H group, which is formed by a condensation reaction using an organic tin catalyst to form a three-dimensional crosslinked structure, and a polydimethylsiloxane and a hydroxypolydimethylsiloxane in which a vinyl group is introduced at a terminal. The type in which is subjected to an addition reaction using an organic catalyst is mainly used.

However, the silicone thin film thus formed has a drawback that it is easily charged due to no leakage of charges due to the silicone main chain bond and the three-dimensional structure. Therefore, the film coated with this silicone thin film is naturally highly charged and causes various problems. For example, when a release film is used as a molded substrate of various resins, the amount of peeling charge is large and dust and the like adhere.
Particularly, when it is repeatedly used, the adhered foreign matter causes a defect on the surface of the molded resin, and the silicone film also falls off, so that it cannot be said that the adhesion between the base material and the coating film is sufficient for long-term use.

[0005]

The present inventors have improved these points, ensured long-term coating adhesion, have stable antistatic properties, and have excellent releasability. The present invention has been achieved as a result of earnest research to develop

[0006]

That is, the present invention relates to a polyester film having a subbing layer comprising a water-soluble organosilane compound on at least one side thereof, and a tetraalkoxysilane having a metal compound and a charge transfer complex formed thereon. And / or an antistatic layer using a partial hydrolyzate thereof, and a release layer using a curable silicone formed on the antistatic layer, and a release film having antistatic properties.

The polyester in the present invention is a linear saturated polyester produced from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative, and specifically, polyethylene terephthalate, polypropylene terephthalate, Examples include polybutylene terephthalate and polyethylene-2,6-naphthalate. Further, it may be a copolymer in which a part of these is substituted with another component, or a mixture with a polyalkylene glycol or another resin.

The polyester film of the present invention is
It can be manufactured by a conventionally known method. For example, the above polyester is dried and then melted, extruded from a die (for example, T-die, I-die, etc.) onto a cooling drum and rapidly cooled to obtain an unstretched film. It can be manufactured by stretching 4 times, stretching 2 to 4 times in the transverse direction, and further heat setting at 180 to 200 ° C. The film thickness is not particularly limited, but 5 to 50 μ
m is preferred.

As the polyester film, a film containing no lubricant is preferable from the viewpoints of transparency and surface flatness, but from the viewpoints of the slip property and processability of the film, lubricants such as calcium carbonate, kaolin, silica, titanium oxide and the like are used. A film containing inorganic fine particles such as the above and / or fine particles precipitated from a catalyst residue may be used, and a film containing other additives such as an antistatic agent such as sodium dodecyl sulfonate and a color tone adjusting agent. It may be.

The water-soluble organosilane compound used for forming the undercoat layer in the present invention has a structure having a hydrolyzable group usually bonded to a silicon atom and various organic functional groups.

Examples of such water-soluble organic silane compounds include γ-aminopropyltrimethoxysilane, γ
-Aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane,
γ-glycidoxypropyltriethoxysilane, γ-glycidoxymethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane,
N-β- (aminopropyl) -γ-aminopropylmethyldimethoxysilane, N-β- (aminoethyl) -γ-
Aminopropyltriethoxysilane and the like can be mentioned. These are some examples of the water-soluble organic silane compounds that can be used in the present invention, and the present invention is not limited to these. The water-soluble organic silane compound may be used alone or in combination of two or more.

The hydrolyzable group in the water-soluble organic silane compound is considered to form a hydroxyl group by hydrolysis and exert an action of strengthening the bond with the inorganic substance in the antistatic layer coated on the undercoat layer, In addition, a highly active organic functional group has a strong affinity with a polyester film, a binder resin for a coating layer, etc. For example, a primary or secondary amino group in a molecule has many functional groups such as a hydroxyl group, a carboxyl group and an epoxy group. It is believed that it reacts with the base to strengthen the bond between the film and the undercoat layer and between the undercoat layer and the antistatic layer.

The water-soluble organosilane compound is usually used as an aqueous solution at a concentration of 0.1 to 5.0%, and the coating amount on the surface of the polyester film is 0.02 to 0.2.
g / m ² (after drying) is preferred. The coating of the water-soluble organosilane compound may be performed during the film forming process, or may be performed at a place different from the film forming process. When it is carried out in the film forming step, it can be applied to an unstretched film, a uniaxially stretched film (especially a longitudinally stretched film), a biaxially stretched film, a film after biaxially stretched and heat set. Of these, it is preferable to apply the composition to a longitudinally stretched film before it is subjected to transverse stretching. As the coating method, various coating methods such as a spin coating method, a gravure coating method, a kiss coating method, a bar coating method and a reverse coating method can be used. The coating is on one or both sides of the polyester film.

In the present invention, the antistatic layer uses a coating solution of a tetraalkoxysilane and / or its partial hydrolyzate forming a charge transfer complex with a metal compound, which is coated on the undercoat layer and heated. It is formed by drying. During this heating and drying, the Milanol hydrolyzed by the moisture in the atmosphere causes a condensation reaction to form a three-dimensionally bonded silicon oxide film.

These reactions are known, and are schematically shown as follows.

[0016]

[Chemical 1]

The metal compound is preferably a divalent metal compound (for example, a halogen compound, an oxide, a hydroxide, a lower fatty acid salt, etc.) from the viewpoint of the reaction yield of the complex and by-products. The metals include Mg, Ca, Sr, Mn, C
o, Ni, Fe, Cu, Zn, Cd, Hg, Sn, P
Preferred examples include b and Al. Further, examples of the tetraalkoxysilane include tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane and the like. The complex formation reaction using an acetate salt is schematically shown below.

[0018]

[Chemical 2]

The tetraalkoxysilane and / or its partial hydrolyzate forming a charge transfer complex with a metal compound can be obtained from the market, and examples thereof include Colcoat EC920 and Colcoat EC851.

In the present invention, the release layer is formed by using a curable silicone coating liquid, applying this on the antistatic layer and curing it. Examples of the curable silicone include condensation reaction type, addition reaction type, radical reaction type, ultraviolet ray or electron beam curing type, silyl isocyanate addition alcohol reaction type and the like. Can also be used. The curing reaction of silicone is as follows.

[0021]

[Chemical 3]

[0022]

[Chemical 4]

[0023]

[Chemical 5]

Electron beams have higher energy than ultraviolet rays,
As in the case of UV curing, crosslinking reaction by radicals occurs even without using an initiator.

Examples of the condensation reaction system silicone include polydimethylsiloxane having a terminal --OH group and polydimethylsiloxane having a terminal --H group (hydroxypolydimethylsiloxane) as an organic tin catalyst (for example, an organic tin acylate catalyst). ) Is used to cause a condensation reaction to form a three-dimensional crosslinked structure. Examples of the addition reaction system silicone include those that form a three-dimensional crosslinked structure by subjecting a polydimethylsiloxane having a vinyl group introduced at the terminal to a hydroxypolydimethylsiloxane to carry out an addition reaction using a platinum catalyst. The UV-curable silicones include, for example, those that use the same radical reaction as ordinary silicone rubber cross-linking as the most basic type, those that cure by introducing an acrylic group, and those that decompose the onium salt with ultraviolet light to generate a strong acid. Examples thereof include those which are generated to open the epoxy group with this to crosslink, and those which are crosslinked by the addition reaction of thiol to vinylsiloxane. The alcohol-addition-type silicone utilizes the reaction of a silicon-functional silyl isocyanate with an alcohol. Silyl isocyanate reacts rapidly with alcohol, but no stable urethane compound is formed and the Si-N bond is cleaved,
Examples include those that form a three-dimensional crosslinked structure.

The curable silicone has a degree of polymerization of 5
About 0 to 50,000 are preferable, and specific examples thereof include DK-Q8-701 manufactured by Dow Corning.
-770, -778, -779; K manufactured by Shin-Etsu Chemical Co., Ltd.
S-774, -778, -841, -837, X-62
-2087, -2113, X-24-8301, X-2
2-343-160C; T manufactured by Toshiba Silicone Co., Ltd.
PR-6721, -6700, -6720, XS-56
-707, -619, YSR-3022, TUV600
0; SRX-211, -34 manufactured by Toray Silicone Co., Ltd.
5, SD-7220, -7223, -7229; SIC-003, SI-130, -2 manufactured by Matsumoto Pharmaceutical Co., Ltd.
20, -310, -400, etc. can be mentioned.

An antistatic layer is provided on the polyester film provided with an undercoat layer using a water-soluble organosilane compound.
Further, when a release layer is provided thereon, as a coating method, a conventionally known method such as a bar coating method, a doctor blade method, a reverse roll coating method or a gravure roll coating method can be used.

The coating film can be dried and cured (heat curing, ultraviolet curing, etc.) individually or simultaneously. When carried out at the same time, it is preferably carried out at 120 ° C. or higher, though it depends on the heat resistance (thermal dimensional stability) of the plastic film.

The coated release film of the present invention comprises:
Adhesive tape protection for electronic parts material processing, resin sheet forming film, and other adhesive protection film, which show stable release property and antistatic property of coating adhesion over a long period of time.

[0030]

The present invention will be described in more detail with reference to the following examples. The various properties of the film were measured by the following methods.

(1) Love offset Rub the coated surface several times with your fingertips to see if the film comes off or adheres: ○ No omission x Yes omission

(2) Surface resistivity The surface resistivity (ρs) is measured with a super insulation resistance meter (RM-214 manufactured by Yokogawa Electric) according to ASTM D-257.

(3) Releasability A polyester pressure-sensitive adhesive tape (Knit-31B) was laminated on the cured silicone overcoat layer, and after being pressure-bonded with a 2 kg pressure roller for 20 minutes, it was cut into a tape width (1 inch), Peel in 180 ° direction with an Instron type tensile tester, and display the resistance value (g / inch) at that time.

[0034]

Comparative Example 1 Molten polyethylene terephthalate ([η]
= 0.65) is extruded from the die and rapidly cooled by adhesion while being electrostatically applied on a rotating cooling drum maintained at about 40 ° C. to obtain a film. Subsequently, the film is longitudinally multiplied by 3.6 times,
Subsequently, the film was stretched in the transverse direction by 3.7 times and then heat-set at 235 ° C. to obtain a biaxially stretched polyester film having a thickness of 50 μm.

Colcoat EC-920 manufactured by Colcoat Co., Ltd., which is a partial hydrolyzate of tetraalkoxysilane containing a metal compound, is replaced with isopropyl alcohol (I).
PA) to prepare a solution having a solid content of 1.5%.

This coating solution was coated on the polyester film at a coating amount of 6 g / m ² (wet), and the drying temperature was 1
It was dried at 20 ° C. and a residence time of 1 minute.

Further, 2 parts by weight of a curing agent [Toshiba Silicone Co., Ltd., trade name CM-670] is added to 100 parts by weight of addition reaction type silicone [Toshiba Silicone Co., Ltd. trade name TPR-6700], and methyl ethyl ketone (MEK) and toluene are added. To prepare a solution having a solid content of 1.5%, which was coated on the film coated with Colcoat EC-920 at a coating amount of 12 g / m ² (wet), and the drying temperature was 120 ° C. It was dried with a residence time of 1 minute.

The characteristics of the release film thus obtained are shown in Table 1.

[0039]

Example 1 Molten polyethylene terephthalate ([η]
= 0.65) was extruded from the die and adhered and rapidly cooled while applying static electricity on a rotary cooling drum maintained at about 40 ° C. to obtain a film, which was then stretched in the longitudinal direction by a factor of 3.6. Then, γ-glycidoxypropylmethyldiethoxysilane [Toshiba Silicone Co., Ltd., trade name TSL-83]
A 4% aqueous solution containing 90 parts by weight of 50] and 10 parts by weight of a nonionic surfactant [Nippon Yushi Co., Ltd., trade name NS-240] was prepared and coated with a coating amount of 5 g / m ² (wet). Subsequently, the film was stretched 3.7 times in the transverse direction at 105 ° C., and heat-set at 235 ° C. to obtain an undercoating film having a thickness of 50 μm.

Except for using this undercoating film,
A release film was obtained in the same manner as in Comparative Example 1.

The characteristics of the obtained release film are shown in Table 1.

[0042]

Example 2 To 100 parts by weight of condensation reaction type silicone [Toshiba Silicone Co., Ltd., trade name YSR-3022], 5 parts by weight of a curing agent [Toshiba Silicone Co., Ltd., trade name YC-6831] was added, and MEK and methyl isobutyl ketone were added. , Xylene was diluted to prepare a solution having a solid content of 1.5%.

Except that the condensation reaction type silicone described above is applied instead of the addition type silicone used in Example 1,
A release film was obtained in the same manner as in Example 1.

The characteristics of the obtained release film are shown in Table 1.

[0045]

Example 3 As an alcohol-added silicone, an isocyanate silicone [Matsumoto Pharmaceutical Co., Ltd. trade name Organix SIC-003], which is a mixture of a silane triisocyanate compound and polydimethylsiloxane, was used as an IP.
Diluted with A to prepare a solution having a solid content of 1.5%.

A release film was obtained in the same manner as in Example 1 except that the above-mentioned alcohol-added silicone was used instead of the addition silicone used in Example 1.

The characteristics of the obtained release film are shown in Table 1.

[0048]

[Example 4] Instead of the addition type silicone used in Example 1, a UV-curable silicone [Toshiba Silicone Co., Ltd. trade name TUV6000] was coated to a thickness of 1 µm, and an 8 KW (160 W / cm) ozone generation high pressure mercury lamp was applied. At a distance of 10 cm, 2000 mj / cm ² of UV was irradiated for 2 seconds to cure and obtain a release film.

The characteristics of the obtained release film are shown in Table 1.

[0050]

[Table 1]

From the above table, it can be seen that the release films of the examples have excellent antistatic properties and release properties with long-term coating film adhesion.

[0052]

According to the present invention, it is possible to provide a release film which secures long-term coating adhesion, has stable antistatic properties, and has excellent releasability.

Claims (1)

Claim: What is claimed is: 1. A subbing layer comprising a water-soluble organic silane compound on at least one side of a polyester film, and a tetraalkoxysilane having a metal compound and a charge transfer complex formed thereon and / or the same. A release film having antistatic properties, comprising an antistatic layer using a partially hydrolyzed product, and a release layer using a curable silicone formed on the antistatic layer.