JPH0976442A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent releasability, back surface non-transferability and adhesive properties with a silicone resin layer by providing a releasable coating film formed by coating at least one side surface of a polyester film with aqueous coating liquid containing oligomer of glycidoxyalkyltrialkoxysilane represented by the formula, drying it and orienting it. SOLUTION: A releasable coating film formed by coating at least one side surface of a polyester film with aqueous coating liquid containing oligomer of glycidoxyalkyltrialkoxysilane represented by the formula (where R is 1-4C alkyl group, n is integer of 1 to 6, and m is integer of 0 to 8), drying and orienting it is provided. The release film obtained by laminating a silicone resin layer having high degree release characteristics on at least one surface of the coating film of the laminated film is used for the application required for the high degree releasability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film, and more particularly to a laminated film having less foreign matter on the film surface, excellent releasability, non-transferability on the back surface, and excellent adhesiveness to a silicone resin layer.

[0002]

2. Description of the Related Art Polyester films made of polyethylene terephthalate, polyethylene naphthalate, etc.
It is widely used as a material for release films. The release film is used in the step of producing a resin sheet. For example, an aqueous solution of polyurethane sol is applied to the surface of the release film, and a polyurethane sheet is formed on the release film by heating and drying, and then the release film is peeled off. Thus, a polyurethane sheet can be manufactured. The release film is also used as a film for protecting an adhesive such as an adhesive tape.

It is difficult to use the polyester film as it is as the release film because the polyester film does not have sufficient release characteristics for various resins and adhesives. For this reason, a laminated film in which a release coating film is applied on the surface of a polyester film is usually used as the release film. For applications requiring a high degree of releasability, a release film obtained by laminating a polyester resin with a silicone resin layer having a high releasability is used, but such a silicone resin layer has poor adhesion to the polyester film. Therefore, it is necessary to provide the polyester film with an adhesive layer having excellent adhesiveness to the silicone resin layer.

The coating of the releasable coating film on the polyester film is usually carried out during the manufacturing process of the polyester film, and an aqueous coating agent is usually used for reasons of environmental protection or disaster prevention. However, the conventional releasable coating film using the aqueous coating agent has a defect that the releasability is insufficient, and some of the components constituting the coating film are adjacent to each other while the film is wound into a roll and stored. There are drawbacks such as transfer to the film surface (so-called back surface transfer) and defects that components volatilized from the aqueous coating liquid in the process of applying a coating film adhere to the film surface as foreign matter. No release coating has been developed yet.

For example, a release film having a polyester film provided with a primer layer obtained by crosslinking a silane coupling agent, and a silicone release layer provided thereon (Japanese Patent Application Laid-Open No. 1-1999).
No. 5838) is known, but in this release film, the silane coupling agent is volatilized from the aqueous coating solution in the step of applying the primer layer, and the silane coupling agent is attached to various equipments in the step and then crosslinked or oxidized. Therefore, there is a drawback that the deteriorated silane coupling agent is peeled off and adheres to the surface of the film as a foreign matter, and its improvement is desired.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above drawbacks of the prior art, to reduce the amount of foreign matter on the surface of the film, and to provide excellent releasability, non-transferability on the back surface, and excellent adhesiveness with the silicone resin layer. To provide.

[0007]

The object of the present invention is, according to the invention, to at least one side of a polyester film,
An aqueous coating solution containing an oligomer of glycidoxyalkyltrialkoxysilane represented by the following formula (I) is applied,
This is achieved by a laminated film provided with a release coating film formed by drying and stretching.

[0008]

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(In the above formula (I), R has a carbon number of 1
To 4 alkyl groups, n is an integer from 1 to 6 and m is 0 to 8
Is an integer. ) Hereinafter, the present invention will be described in detail.

[Base Film] In the present invention, a polyester film is used as the base film, and the polyester constituting the base film is a linear polyester composed of a dicarboxylic acid component and a glycol component.

Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid and 4,4'-
Diphenyldicarboxylic acid, phenylindanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,
4′-diphenylmethanedicarboxylic acid, 4,4′-diphenylpropanedicarboxylic acid, hexahydroterephthalic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid and the like can be mentioned. Among these, it is preferable to use, for example, 80 mol% or more of an aromatic dicarboxylic acid, and it is particularly preferable to use terephthalic acid or 2,6-naphthalenedicarboxylic acid.

As the glycol component, for example, ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, polyethylene glycol. And the like, and ethylene glycol is particularly preferable.

Among such polyesters, polyethylene terephthalate or polyethylene-2,6-naphthalate homopolymer is excellent in mechanical properties such as high Young's modulus and in thermal properties such as good heat resistance and dimensional stability. It is preferable because an excellent film can be obtained.

The above-mentioned polyester may be a polyester obtained by copolymerizing the above-mentioned dicarboxylic acid component or glycol component in order to improve the adhesion between the polyester film and the releasable coating film. Further, a polyester obtained by copolymerizing a trifunctional or higher polyvalent compound in a small amount within a range in which the polyester is substantially linear (for example, 5 mol% or less) may be used. Further, the above-mentioned polyester can be produced by a conventional method, and it is preferable that the intrinsic viscosity is 0.5 or more because the mechanical properties such as the rigidity of the film are good, and the like.

The above polyester has a mean particle size of 0.1 as a lubricant in order to improve the slipperiness of the film.
It is preferable to add organic or inorganic fine particles of about 01 to 20 μm at a blending ratio of, for example, 0.005 to 20% by weight. Specific examples of such fine particles include silica, alumina, kaolin, calcium carbonate, titanium oxide, barium sulfate, carbon black, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, and crosslinked silicone resin particles. .

In addition to the fine particles, a colorant, an antistatic agent,
Antioxidants, organic lubricants (slipping agents), optical brighteners, cross-linking agents, ultraviolet absorbers and the like can be added as necessary.

In the present invention, the film to which the aqueous coating solution is applied is a film which can be stretched after applying the aqueous coating solution. As such a film, an unstretched film, a uniaxially stretched film or a stretchable biaxially stretched film is used. Can be used. Such a film can be obtained by a conventionally known method. For example, an unstretched film can be obtained by melting the polyester in an extruder and extruding it into a film, and cooling it with a rotary cooling drum. By stretching the unstretched film uniaxially in the machine direction or the transverse direction, A uniaxially stretched film can be obtained. Further, the stretchable biaxially stretched film is a method of sequentially biaxially stretching a uniaxially stretched film in the longitudinal direction or the transverse direction in the transverse direction or the longitudinal direction, or simultaneously biaxially stretching an unstretched film in the longitudinal direction and the transverse direction. Can be obtained by the method.

The above-mentioned stretching temperature is preferably higher than the second-order transition point (Tg) of polyester. Further, the stretching ratio is 2 to 8 times in the uniaxial direction in the case of a uniaxially stretched film, and 1.1 to in each direction in the case of a stretchable biaxially stretched film.
It is preferably 8 times, especially 2 to 6 times.

The film coated with a releasable coating film can be re-stretched in the machine direction or the transverse direction if necessary, or can be heat-treated at 120 to 270 ° C. The thickness of the polyester film after coating the releasable coating film is, for example, 2 to
It is preferably 300 μm, and particularly 3 to 260 μm.
It is preferred that

[Oligomer of glycidoxyalkyltrialkoxysilane] In the present invention, an oligomer of glycidoxyalkyltrialkoxysilane represented by the following formula (I) (hereinafter referred to as "silane oligomer") is provided on at least one surface of the polyester film. (Hereinafter abbreviated) is applied, and a releasable coating film formed by drying and stretching is provided.

[0021]

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In the above formula (I), R has a carbon number of 1 to
The alkyl group of 4 is preferable, and a methyl group or an ethyl group is particularly preferable. Moreover, n is an integer of 1 to 6, and is particularly preferably 3 or 4. Further, m is an integer of 0 to 8, and it is particularly preferably 0 to 2.

Preferred examples of such silane oligomers are shown in the following formulas (II) to (V). Of these, a silane oligomer (dimer) of the following formula (II) is particularly preferable.

[0024]

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[0025]

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[0026]

[Chemical 6]

[0027]

[Chemical 7]

As the silane oligomer in the present invention, the above oligomers may be used alone or in combination of two or more kinds.

The silane oligomer in the present invention preferably does not contain a monomer represented by the following formula (VI), but may contain less than 50% by weight.

[0030]

Embedded image

In the above formula (VI), R has a carbon number of 1 to
4 represents an alkyl group of 4 and n represents an integer of 1 to 6.
An example of such a monomer is shown in formula (VII) below.

[0032]

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[Aqueous coating liquid] In the present invention, an aqueous coating liquid (for example, an aqueous solution, an emulsion, or a dispersion) containing the above-mentioned silane oligomer is used to apply a releasable coating film to the polyester film. The concentration of the silane oligomer in the aqueous coating solution is 20 to 100 as the concentration in the solid content.
It is preferably in the weight%. If this concentration is less than 20% by weight, the releasability is insufficient.

In order to adjust the curability of the silane oligomer, the pH of the coating liquid can be changed by adding an acidic substance or an alkaline substance to the aqueous coating liquid. In addition, colloidal silica is preferably added to the aqueous coating liquid in order to suppress volatilization of the components in the coating liquid. Further, in order to improve the adhesion between the releasable coating film and the polyester film, the aqueous coating liquid may contain a binder resin at a concentration of 0 to 80% by weight as a solid content. Examples of the binder resin include polyester resin, acrylic resin,
Examples thereof include acrylic modified polyester resin, polyurethane resin, epoxy resin, vinyl resin, polyether resin, water-soluble resin and the like.

Further, a surfactant may be added to the aqueous coating liquid in order to improve the wettability of the coating liquid on the polyester film. Examples of the surfactant include polyalkylene oxide polymers, alkylene oxide copolymers, aliphatic alcohol alkylene oxide adducts, long chain aliphatic substituted phenol / alkylene oxide addition polymers, polyhydric alcohol fatty acid esters, long chain fats. Group amide alcohols, quaternary ammonium salts, alkylpyridinium salts, sulfonates and the like can be mentioned.

In the aqueous coating liquid, in addition to the above components, lubricants (inorganic or organic fine particles), antioxidants, antistatic agents, colorants, pigments, optical brighteners, plasticizers, crosslinking agents, lubricants (lubricants) ),
An ultraviolet absorber or the like can be added. As the above-mentioned lubricant, for example, silica, alumina, titanium oxide, inorganic fine particles such as carbon, crosslinked polystyrene resin, crosslinked acrylic resin, melamine resin, crosslinked silicone resin, fluorine resin, urea resin, benzoguanamine resin, polyamide resin, polyester resin, etc. The resin fine particles can be mentioned.

The total solid content concentration in the aqueous coating liquid is preferably 1 to 30% by weight, particularly preferably 2 to 20% by weight. The aqueous liquid may contain a small amount of organic solvent.

[Coating of Releasable Coating Film] In the present invention,
At least one surface of the polyester film is coated with the water-based coating solution, dried by heating, to form a releasable coating film by stretching, as the application method of the aqueous coating solution, any known coating method is applied. For example, gravure coating method, reverse roll coating method, die coating method, kiss coating method, reverse kiss coating method, offset gravure coating method, Meyer bar coating method, roll brush method, spray coating method, air knife coating method, impregnation method, curtain The coating method and the like can be applied alone or in combination. WET coating amount of aqueous liquid is 1 m of running film
^It is preferably 1 to 40 g, especially ^{2 to} 12 g per ² parts. When the coating amount is within this range, drying is easy and coating spots are less likely to occur, which is preferable.

In the present invention, the above-mentioned unstretched film, uniaxially stretched film or stretchable biaxially stretched film can be used as the polyester film to which the aqueous coating solution is applied. Of these, a uniaxially stretched film, especially a longitudinal film. It is preferable to use a uniaxially stretched film having a unidirectional orientation because the releasable coating film has good abrasion resistance and a laminated film can be efficiently produced. For example, polyester is heat-melted by an extruder, extruded into a sheet and cooled to obtain an unstretched film, and the unstretched film is stretched 2 to 8 times in the machine direction to form a uniaxially stretched film. After coating, heat-drying, and then stretching in the transverse direction by 2 to 9 times, and if necessary, re-stretching in the longitudinal direction or the transverse direction and / or heat treatment to obtain a laminated film having good abrasion resistance of the release coating film. Can be created.

The thickness of the releasable coating film applied is 0.005 to
0.2 μm, particularly 0.01 to 0.1 μm is preferable. If the thickness of the releasable coating film is less than 0.005 μm, releasability may be insufficient, and if it exceeds 0.2 μm, back surface non-transferability may be insufficient, which is not preferable.

[Drying and Stretching Temperature] After applying the aqueous coating liquid in the present invention, the drying temperature is preferably 70 to 120 ° C. because the coating liquid can be dried quickly. The heating for this drying can also serve as the heating during the process of stretching the polyester film. The stretching temperature of the polyester film may be 80 to 170 ° C, and the heat treatment temperature may be 120 to 260 ° C.

[Silicone resin layer] For applications requiring a high degree of releasability, a silicone resin layer having a high degree of releasability is laminated on at least one surface of the releasable coating film of the laminated film of the present invention. A release film can be used.

For this silicone resin layer, for example, a coating liquid containing a curable silicone resin is applied to the surface of the releasable coating film,
It can be formed by drying and curing.

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

As the condensation reaction type silicone resin, for example, polydimethylsiloxane having a terminal --OH group and polydimethylsiloxane having a --H group at a terminal (hydrogensilane) may be used 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, and those that are crosslinked by the addition reaction of thiol to vinylsiloxane. Electron beams have higher energy than ultraviolet rays, and a radical crosslinking reaction occurs without using an initiator as in the case of ultraviolet curing.

When the above-mentioned cured silicone resin layer is applied to the surface of the releasable coating film, the coating method is conventionally known such as bar coating method, doctor blade method, reverse roll coating method or gravure roll coating method. The available methods are available.

The drying and curing (heat curing, ultraviolet curing, etc.) of the silicone resin layer can be carried out individually or simultaneously. When performing simultaneously, it is preferable to perform at 100 degreeC or more. The conditions for drying and heat curing are 10
About 30 seconds is desirable at 0 ° C or higher. Drying temperature is 100 ℃
Below, and when the curing time is 30 seconds or less, the curing of the silicone resin is incomplete, and the durability such as the dropping of the silicone resin layer remains uneasy.

The thickness of the cured silicone resin layer 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 be deteriorated and satisfactory performance cannot be obtained. If it is too thick, it takes a long time to cure, which causes inconvenience in production.

[0051]

EXAMPLES The present invention will be described in more detail with reference to examples. Each characteristic value was measured by the following method. The average molecular weight is the number average molecular weight.

1. A mirror-finished stainless plate was installed in the step of applying the aqueous coating solution to the non-volatile film of the coating solution and then drying, and the drying step was operated for 8 hours and then taken out and the surface of the stainless plate was observed. The degree of cloudiness due to the volatile matter adhering to the surface of the stainless steel plate was observed, and the nonvolatility of the coating liquid component was evaluated according to the following criteria. A: No fog on the surface (good non-volatility of the coating liquid component) B: Slight cloudiness on the surface (slightly non-volatile volatility of the coating liquid component) C: Cloudy on the surface (non-volatile volatility of the coating liquid component) Poor sex)

2. Vinyl chloride sol was applied to the coated surface of the releasable film sample and dried to form a vinyl chloride layer having a thickness of 6 μm. Then, an adhesive tape was attached to the surface of the vinyl chloride layer to reinforce the vinyl chloride layer, and the sample was cut into 1/2 inch width, and then the peel strength (g / In) was measured. The releasability can be evaluated from the peel strength as follows. A: Peel strength is less than 100 (g / in) ... Good releasability B: Peel strength is 100 (g / in) or more and less than 200 (g / in) ...
… Slightly good releasability C: Peel strength is 200 (g / in) or more …… Releasability is poor

3. Backside non-transferability After the coating film coated surface and the coating film non-coated surface of the sample film are overlapped and kept at a temperature of 57 ° C and a humidity of 72% RH for 9 hours, the coating film non-coated surface is contacted with water. The angle (Pa) was measured. Further, the peel strength (P ₀ ) was similarly measured in the case where the polyester film non-coated surfaces were superposed on each other. Then, from the values of P ₀ and Pa, the back surface transfer rate (T)
Was determined by the following formula, and the back surface non-transferability was evaluated according to the following criteria.

[0055]

[Equation 1] T = [(P ₀ −Pa) / P ₀ ] × 100 A: T ≦ 5 …… good backside non-transferability B: 5 <T <8 …… somewhat good backside nontransferability C: 8 ≦ T: Back surface non-transferability defect

4. Adhesiveness of silicone resin layer A coating film of addition polymerization type silicone resin with a thickness of 4 μm is applied on the coated surface, and after drying, a cotton cloth is laid on the silicone coated surface and a load of 200 g is applied with a Gakken abrasion tester. In addition, after sliding the silicone coating surface and the cotton cloth surface back and forth 300 times, the appearance change of the sliding surface of the silicone coating was observed and evaluated as follows. A: There is almost no change in the sliding surface. … Good adhesion of silicone resin layer B: Slight scratches of friction marks on sliding surface… Slightly good adhesion of silicone resin layer C: Strong scratches of friction on sliding surface… Poor adhesion of silicone resin layer

5. Foreign matter on film surface Foreign matter on film surface was measured with an optical microscope, and the average number of foreign matter was converted per 1 m ² and evaluated as follows.
The particles having a particle size of 0.5 μm or more were measured as foreign matter. A: The number of foreign matter 1/1 m ² or less ...... good B: The number of foreign matter 2-3 / 1 m ² ...... slightly better C: ...... defective number of foreign matter 4/1 m ² or more

[Example 1] Polyethylene terephthalate having an intrinsic viscosity of 0.64 was melted by an extruder, and a film-like molten polymer was extruded from a die onto a rotating cooling drum and rapidly cooled to obtain an unstretched film. The stretched film was stretched 3.6 times in the machine direction to obtain a uniaxially stretched film.
On one side of the uniaxially stretched film, 76% by weight of the dimer of the formula (II), 13% by weight of the trimer of the formula (III) and 11% by weight of an ethylene oxide / propylene oxide block copolymer (average molecular weight: 5,290). A 3% by weight aqueous coating solution having a composition of was applied by a gravure coater. Then, the coated film was dried at 110 ° C., stretched 3.9 times in the transverse direction, and heat-treated at 231 ° C. to give a total thickness of 43.
A laminated film having a coating thickness of 0.04 μm was prepared. Table 1 shows the results of evaluation of nonvolatility of the coating liquid components in the drying step of the aqueous coating liquid. In addition, Table 2 shows the evaluation results of the characteristics of the obtained laminated film.

Comparative Example 1 A polyester film was obtained in the same manner as in Example 1 except that no coating film was applied. Table 2 shows the evaluation results of the characteristics of the obtained film.

[Examples 2 to 8 and Comparative Example 2] The same as Example 1 except that the components of the aqueous coating solution were changed as shown in Table 1 and the coating film thickness was changed as shown in Table 2. To obtain a laminated film. Table 1 shows the results of evaluation of nonvolatility of the coating liquid components in the drying step of the aqueous coating liquid. In addition, Table 2 shows the evaluation results of the characteristics of the obtained laminated film.

[0061]

[Table 1]

[0062]

[Table 2]

As is clear from the results shown in Tables 1 and 2, the laminated film of the present invention has excellent releasability, non-transferability on the back surface, and adhesiveness with a silicone coating film, and has little foreign matter on the film surface. Met.

In Table 1, the formula (II), the formula (III) and the formula (VII) are the compounds of the formula (II), the formula (III) and the formula (VII), respectively, and (A) is
Methyl methacrylate component (43 mol%), ethyl methacrylate component (29 mol%), ethyl acrylate component (1
4 mol%), glycidyl methacrylate component (5 mol%), 2-hydroxyethyl acrylate component (3 mol%), N-methoxymethylacrylamide component (3 mol%) and acrylic acid component (3 mol%) Copolymer (T
g = 51 ° C.).

[0065]

EFFECTS OF THE INVENTION Since the release coating film of the present invention is applied by using an aqueous coating liquid containing a specific glycidoxyalkyltrialkoxysilane oligomer, the release property and the back surface non-transfer are Excellent in adhesiveness and adhesiveness with silicone coating film, and less foreign matter on the film surface.

Claims (3)

[Claims] 1. A releasable coating prepared by coating an aqueous coating solution containing an oligomer of glycidoxyalkyltrialkoxysilane represented by the following formula (I) on at least one side of a polyester film, drying and stretching. Laminated film provided with a film. Embedded image (In the above formula (I), R is an alkyl group having 1 to 4 carbon atoms, n is an integer of 1 to 6 and m is an integer of 0 to 8.) 2. The laminated film according to claim 1, wherein the aqueous coating liquid contains colloidal silica. 3. The laminated film according to claim 1, which is used for a releasing film having a silicone resin layer laminated on at least one surface of a releasing coating film.