JPH079625A - Release film - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a colored release film which has stable peeling power, has hiding power and transparency, and is not mistaken for other materials. [Structure] A release film comprising a cured silicone resin coating film on at least one side of a plastic film dyed by an anhydrous dyeing method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film, and more specifically, a dyed plastic film provided with a cured silicone resin coating film on at least one side thereof, which can be easily distinguished from other materials during use and can be mistaken. Release film without

[0002]

2. Description of the Related Art In recent years, in accordance with a wide range of applications of adhesives, adhesives, etc., the use of silicone-coated release paper or release film for protecting the adhesive surface has been remarkably expanding in various fields. A composition containing a curable silicone resin as a main component is mainly used for the silicone coating, and as the composition, a composition which is cured by a condensation reaction (JP-A-47-34447, etc.) and a composition which is cured by an addition reaction (special characteristics: Kosho 52-40918) is known.

However, the conventional release film is difficult to distinguish from the plastic film of the same kind, and since it is a film having good see-through property, it is difficult to confirm its loading, mounting, forgetting to peel it, and remaining unpeeled film. Therefore, for example, when the composite material itself used for coloring such as liquid crystal related materials such as polarizing plates, exterior boards for multilayer printed circuit boards, thermosetting resin prepregs that require high temperature molding is colored, or product differentiation is required. In various required fields, problems such as mistakes in peeling occur. Especially when a plastic film of the same kind such as polyethylene or polyester is stuck as a protective film on the other side such as a polarizing plate or a retardation plate, it is quite likely that the protective film is mistaken for a release film during processing. This is one of the fatal problems related to the decrease in yield. For materials such as print boards and prepregs, it is very important to check whether the release film has been loaded, and if the release film is damaged during processing, whether it is attached to the molded material. It is an item.

Therefore, it is desired to color the release film,
It is also being considered. For this coloring, it is necessary to satisfy both contradictory properties such as hiding power (coloring degree) and transparency. The transparency is related to the above-mentioned thing, that the material underneath can be recognized through the release film, for example, what the material is, or reading a character mark or the like written on the composite material. It is necessary because of that.

As a method for coloring a release film, a pigment or dye is directly added to a curable silicone resin composition which is a release agent, or coloring by a pigment dyeing filler has been attempted, but both are cured. Since it acts as a catalyst poison of the hydrophilic silicone resin, the reactivity is rapidly lowered, the curing is insufficient, the peeling force itself is increased, and the level of use has not been reached. On the other hand, as a method of coloring the plastic itself as a base material, a method of mixing a polyester resin with a dye / pigment and then forming a film, a method of coating the ink or dye / pigment with a binder resin after the film formation, and performing a heat treatment, etc. Although the former method is being studied, the former method is not suitable for large-lot, small-quantity production, it also contaminates extruders, film-forming equipment, heat treatment equipment, etc., it is difficult to obtain vivid colors, and dyes and pigments that can withstand high temperatures. However, it has a drawback that it is difficult to adjust the color density. Also, in the latter,
It has drawbacks such as lack of surface smoothness, lack of uniformity of dyeing, difficulty of peeling of binder resin, loss of transparency, and poor fastness.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a strong and clear dyed plastic film as a base, which has a stable peeling force and is excellent in hiding power and transparency. Another object is to provide a colored release film.

[0007]

The object of the present invention is to:
According to the present invention, the release film is obtained by providing a cured silicone resin coating film on at least one side of a plastic film dyed by an anhydrous dyeing method.

In the present invention, examples of the plastic film include polystyrene, polymethyl acrylate, polycarbonate, polysulfone, triacetyl cellulose, cellophane, polyamide, polyimide, polyphenylene sulfide, polyetherimide, polyethersulfone, aromatic polyamide, polyolefin, A transparent film (containing sheet) made of polyester or the like can be preferably mentioned. Of these, polyester biaxially stretched film is preferable.

The polyester film is added by the film-forming step and contains a lubricant such as clay, kaolin, silica,
The transparency can be easily controlled by adjusting the particle size and amount of calcium carbonate and the like. Also, when the surface is coated, it has excellent solvent resistance, heat resistance, and mechanical properties. In particular, the drying temperature after coating is set to 1 in order to cure the coating of the curable silicone resin.
The temperature is set to 00 to 140 ° C., and there is an advantage that a dimensional change is small when the film is passed in this atmosphere.

Polyester is a general term for polymers having an ester bond as the main chain of the main chain. Particularly preferred polyesters are polyethylene terephthalate, polyethylene-2,6-naphthalate, polyethylene-α, β-bis (2- Chlorphenoxy) ethane-4,4'-dicarboxylate, polybutylene terephthalate and the like. Among these, polyethylene terephthalate is most preferable in view of quality, economy and the like.

The thickness of the plastic is not particularly limited, but, for example, from the waist strength required for the release film,
It is preferable to select an appropriate thickness from the range of about 1 to 500 μm.

The surface roughness and haze of the plastic film are not particularly limited, but the thickness of the coating film described below, the adhesive strength required between the coating film and the plastic film, and the release film are required. The desired value may be set appropriately in consideration of the transparency.

In the present invention, such a plastic film is used after being dyed, and this dyeing is carried out by an anhydrous dyeing method. This anhydrous dyeing method can also be called a solvent dyeing method, and is a method of dyeing a film at a high temperature with a dye dissolved, suspended or dispersed in an organic solvent having a relatively high boiling point. The organic solvent is preferably a hydrophilic organic solvent such as ethylene glycol,
Examples thereof include glycols such as diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, alkyl ethers thereof, phenyl ethers, and polyhydric alcohols such as glycerin.

Disperse dyes are preferably used as dyes, but vat dyes and complex dyes can also be used. For example, benzoanone type, heterocyclic azo type,
Examples thereof include anthraquinone type dyes and condensation type dyes.

The density of the dye, of course, varies depending on the color density, but it varies depending on the dyeing density and the dyeing time, and is usually 3 to 15 g / l. The temperature during dyeing is usually 100
-200 degreeC, Preferably it is 120-180 degreeC. The dyeing time is usually several seconds to several minutes, preferably several seconds to several tens seconds. However, depending on the staining density, a longer time can be taken.

Dyeing is preferably carried out by passing the film through a dye bath at a high temperature. At that time, it is preferable to keep the dye concentration in the dye bath constant, and therefore it is preferable to constantly circulate the dye bath or replenish the fresh liquid to automatically control the dye concentration. The film discharged from the dye bath is treated with a dye bath or solvent adhering to the surface of the film, a chlorinated hydrocarbon solvent having a relatively low boiling point such as CH ₂ Cl ₂ ,
Wash with CCl ₄ , CHCl _3, etc., or with hot or hot water. When recovering and separating each component from the washing liquid, it is preferable to wash with a chlorinated hydrocarbon solvent which is easy to treat.

The degree of dyeing of the plastic film depends on the usage of the release film, but the total light transmittance is 20 to 8.
It is preferably 0%, and more preferably 25 to 70%.

In the present invention, the cured silicone resin coating film is a layer that imparts release characteristics to the plastic film,
The layer is formed by applying a coating liquid containing a curable silicone resin on at least one side of a plastic film, drying and curing.

As the curable silicone resin, any reaction system such as condensation reaction system, addition reaction system, ultraviolet ray or electron beam curing system can be used. One or more of these may be used.

The curing reaction of various silicones can be shown as follows.

[0021]

[Chemical 1]

Examples of the condensation reaction type silicone resin include polydimethylsiloxane having a terminal --OH group and polydimethylsiloxane having a --H group at a terminal (hydrogensilane) 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.

As the addition reaction type silicone resin, for example, polydimethylsiloxane having a vinyl group at the terminal is reacted with hydrogenenesilane using a platinum catalyst,
Examples include those that form a three-dimensional crosslinked structure.

As the ultraviolet curing type silicone resin,
For example, as the most basic type, one that uses the same radical reaction as ordinary silicone rubber cross-linking, one that introduces an acrylic group for photo-curing, one that decomposes an onium salt with ultraviolet light to generate a strong acid, and then an epoxy group Examples thereof include those that are cleaved and crosslinked, those that are crosslinked by the addition reaction of thiol to vinylsiloxane, and the like. Electron beams have higher energy than ultraviolet rays, and a crosslinking reaction by radicals occurs without using an initiator as in the case of ultraviolet curing.

The curable silicone resin preferably has a degree of polymerization of about 50 to 200,000, and specific examples thereof include KS-71 manufactured by Shin-Etsu Silicone Co., Ltd.
8, -774, -775, -778, -779H, -8
30, -835, -837, 838, -839, -8
41, -843, -847, -847H, X-62-2
418, -2422, -2125, -2492, -24
94, -470, -2366, -630, X-92-1
40, -128, KS-723A ・ B, -705F,-
708A, -883, -709, -719, TPR-6701, -6702, -67 manufactured by Toshiba Silicone Co., Ltd.
03, -3704, -6705, -6722, -672
1, -6700, XSR-7029, YSR-302
2, YR-3286, DK made by Dow Corning Co., Ltd.
Q3-202, -203, -204, -210, -24
0, -3003, -205, -3057, SFXF-2
560, SD-7226,7 manufactured by Toray Silicone Co., Ltd.
320, 7229, BY24-900, 171, 31
2,374, SRX-375, SYL-OFF23, S
RX-244, SEX-290, SILCOLASE 425 manufactured by IC Japan Co., Ltd. and the like can be mentioned. Further, silicone resins described in JP-A-47-34447 and JP-B-52-40918 can also be used.

In providing the cured silicone resin coating film in the present invention, the coating method includes a bar coating method, a doctor blade method, a reverse roll coating method,
A conventionally known method such as a gravure roll coating method can be used.

The coating film can be dried and cured (heat curing, ultraviolet curing, etc.) individually or simultaneously. At the same time, it is preferably performed at 100 ° C. or higher, although it depends on the heat resistance (thermal dimensional stability) of the plastic film. The dry heat curing condition is preferably 100 ° C. or higher and about 30 seconds. When the drying temperature is 100 ° C. or lower and the curing time is 30 seconds or shorter, the coating film is not completely cured, and the durability of the coating film remains uneasy.

The thickness of the cured silicone resin coating film is not particularly limited, but is preferably in the range of 0.05 to 0.5 μm. If it becomes too thin, the release performance will deteriorate and satisfactory performance will not be obtained. If it is too thick, it takes a long time to cure, which causes inconvenience in production.

The release film of the present invention comprises a liquid crystal-related material such as a polarizing plate, a multilayer printed circuit board exterior plate,
A wide range of fields, such as thermosetting resin prepregs that require high-temperature molding, various fields where the composite materials used there are colored, product differentiation is required, and general-purpose adhesive fields such as adhesive tapes. Applicable.

The release film of the present invention has the following features. 1) Due to the low surface energy of the cured silicone resin coating film, it has good releasability without adhering to various other substances. 2) Despite being colored with various dyes, the transparency and hiding property of the appearance are maintained.

[0031]

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

(1) Film total light transmittance The total light transmittance is expressed as a percentage of the ratio of the incident light quantity to the total light quantity passing through the sample film, and the measurement is performed according to JIS-K.
7105-1981. As a measuring machine, Japan Precision Engineering Co., Ltd. POIC HAZE
METER SEP-HS-D1 was used.

(2) Coatability of the coating film The surface of the silicone coating film was rubbed with five reciprocating fingers, the surface condition was observed, and the cured condition was classified into the following three types for evaluation. X: Silicone does not cure and clouding (smear) occurs. Δ: Silicone is hardened, but the adhesion is poor and there is drop-out (lab-off). ◯: Silicone is hardened and has good adhesion.

(3) Releasability (3-1) Initial peeling force Sample film and polyester adhesive tape (knit-
31B) are stuck together and pressure bonded with a 5 kg pressure roller,
The peel strength after standing for 20 hours is measured by a tensile tester. (3-2) Peeling force over time Sample film and polyester adhesive tape (knit-
31B) are stuck together and pressure bonded with a 5 kg pressure roller,
The peeling force after standing for 1000 hours is measured by a tensile tester.

(4) Roll Contamination State While the release film wound into a roll is being rewound by a rewinding machine, the presence or absence of stains on each roll is determined by observing a particular roll in contact with the silicone resin coating film surface. To do.

(5) Residual Adhesion Rate A polyester adhesive tape (knit-31B) was specified by JIS
Cold rolled stainless steel plate (SUS3 specified in G4305
The peeling force after sticking to (04) was measured, and the basic adhesive force (f
₀ ). Further, the polyester adhesive tape is pressure-bonded to the cured silicone resin coating film surface of the sample film with a pressure roller of 5 kg, left for 30 seconds, and then the adhesive tape is peeled off. Then, the peeled adhesive tape was attached to the above stainless steel plate, the peeling force of the attached portion was measured, and the residual adhesive force (f)
And For each of these adhesive strengths, the residual adhesion rate is calculated from the following equation.

[0037]

[Equation 1]

(6) Blocking property After the front surface and the back surface of the polyester film are put together, 10
After cutting into squares of 15 cm × 15 cm and applying a load of 50 kg / cm ² for 17 hours in an atmosphere of 50 ° C. × 50% RH, sandwich the two overlapping samples with your thumb and forefinger, and then use your fingertips. The state of blocking when the two are peeled off by the force of is classified into the following three and evaluated. X: Sticky and difficult to peel off, and after peeling off, the surface of the silicone resin coating film becomes rough. Δ: There is considerable resistance. ◯: Peels easily with little resistance with fingertips.

[0039]

Example 1 A polyester film (thickness: 38 μm) dyed by an anhydrous dyeing method having a total light transmittance of 27.5% was coated with a coating solution having the following composition so that a coating amount was 8 g / m ² (wet). Then, a curing reaction was performed at a drying temperature of 130 ° C. and a residence time of 30 seconds to prepare a release film having a dry film thickness of 0.24 μm. The characteristics of this release film are shown in Tables 1 and 2.

<Composition of coating liquid> Curable silicone resin (KS847H) 100 parts by weight Curing agent (CAT PL-50T; manufactured by Shin-Etsu Silicone Co., Ltd.) 2 parts by weight Methyl ethyl ketone / methyl isobutyl ketone / xylene 898 parts by weight

[0041]

[Example 2] The dye film has a total light transmittance of 3
A release film was prepared in the same manner as in Example 1 except that a dyed polyester film of 9.5% and a coating liquid having the following composition was used as the coating liquid. The characteristics of this release film are shown in Tables 1 and 2.

<Composition of coating liquid> Curable silicone resin (TPR6712) 100 parts by weight Curing agent (CM670; manufactured by Toshiba Silicone Co.) 2 parts by weight Methyl ethyl ketone / methyl isobutyl ketone / xylene 1398 parts by weight

[0043]

Comparative Example 1 A release film was prepared in the same manner as in Example 1 except that a non-dyed transparent polyester film was used in place of the dyed polyester film in Example 1. The characteristics of this release film are shown in Tables 1 and 2. The release film had almost the same quality as the dyed polyester film except for coloring and transparency.

[0044]

Comparative Example 2 A release film was prepared in the same manner as in Example 2 except that a non-dyed transparent polyester film was used in place of the dyed polyester film in Example 2. The characteristics of this release film are shown in Tables 1 and 2. It was a release film with almost no difference in quality other than the dyed polyester film and the color and transparency.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

The release film of the present invention is excellent in releasability and its stability over time, smear, blocking property and the like, has both hiding power and see-through property, and can be easily distinguished from other materials. It is useful in various fields.

Claims (1)

[Claims] 1. A mold release film comprising a cured silicone resin coating film on at least one side of a plastic film dyed by an anhydrous dyeing method.