JPH08258233A - Laminated film - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a laminated film useful for a release film and the like, which is excellent in abrasion resistance of the coating film, release characteristics of the coating surface, and excellent in adhesiveness to the silicone resin layer. [Structure] At least one side of the polyester film,
A laminated film provided with a coating film prepared by coating an aqueous liquid containing a silicone-modified polyester polymer having a main chain of a polyester polymer chain and a side chain of a silicone polymer chain, followed by drying and stretching.

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 which is useful as a release film excellent in abrasion resistance and release characteristics of a coating film.

[0002]

2. Description of the Related Art Polyester films made of polyethylene terephthalate, polyethylene naphthalate, etc.
It is widely used as a process material such as a release film (for example, for process release, for protecting an adhesive, etc.).

The above-mentioned release film for releasing the step is a film used in the step of producing a resin sheet such as a vinyl chloride sheet or a polyurethane sheet. In this step, for example, polyurethane sol is formed on the surface of the release film. The resin sheet is manufactured by applying the aqueous liquid of (1) and heating and drying to form a polyurethane sheet on the release film, and then peeling the polyurethane sheet from the release film.

The release film for protecting the adhesive is
For example, it is a film (protective film) used for protecting the surface of an adhesive tape or the like having an adhesive layer as a surface layer.

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.

Various coating agents have been developed for coating a releasable coating film on a polyester film. However, when coating is carried out during the production process of the polyester film, it is usually used for environmental protection or disaster prevention reasons. An aqueous coating agent is used. However, the conventional releasable coating film using an aqueous coating agent has a defect that the coating film is easily scraped and a defect that the release property of the coating film surface is insufficient. Coatings have not yet been developed.

For example, a releasable coating film applied by using an aqueous coating agent containing a composition in which a silicone resin and a binder resin are simply blended has poor compatibility between the silicone resin and the binder resin, and thus is coated. The abrasion resistance of the film is poor, and the release characteristics of the coating film surface cannot be said to be sufficient. Further, in the releasable coating film (Japanese Patent Laid-Open No. 3-99827) using an aqueous coating agent containing a graft polymer having a main chain of an acrylate polymer and a side chain of a silicone polymer, abrasion resistance of the coating film is observed. There is a problem of lack of sex.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional drawbacks and to provide a laminated film excellent in abrasion resistance of a coating film and in releasing property of the coating surface.

[0009]

The object of the present invention is, according to the invention, to at least one side of a polyester film,
Achieved by a laminated film provided with a coating film prepared by applying an aqueous liquid containing a silicone-modified polyester polymer whose main chain is a polyester polymer chain and side chains are silicone polymer chains, and then drying and stretching To be done.
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, hexahydroterephthalic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid and dodecanedicarboxylic acid. Among them, terephthalic acid and 2,6-naphthalenedicarboxylic acid are particularly preferable.

Examples of the glycol component include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol and 1,6-hexanediol. , Cyclohexanedimethanol, polyethylene glycol, polytetramethylene glycol, dipropylene glycol, triethylene glycol, bisphenol, 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, glycol component or the like in order to improve the adhesion between the polyester film and the coating film. It may be a polyester obtained by copolymerizing a small amount of the above polyvalent compound in a range in which the polyester becomes substantially linear (for example, 5 mol% or less).

Such polyester can be produced by a conventional method. Also, the intrinsic viscosity of polyester is 0.45
The above is preferable because mechanical properties such as high rigidity of the film are improved.

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, calcium oxide, titanium oxide, graphite, carbon black, zinc oxide, silicon carbide, tin oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, Preferable examples include crosslinked silicone resin particles.

In addition to the fine particles, colorants, known antistatic agents, antioxidants, organic lubricants (slipping agents), catalysts, optical brighteners, plasticizers, crosslinking agents, ultraviolet absorbers, other resins, etc. It can be added if necessary.

In the present invention, the film to which the aqueous liquid is applied is a film which can be stretched after applying the aqueous liquid. As such a film, an unstretched film, a uniaxially stretched film or a stretchable biaxially stretched film is used. You can 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 a second-order transition point (Tg) of polyester of -10 ° C or higher. Also,
The stretching ratio is 2 to 8 in the uniaxial direction in the case of a uniaxially stretched film.
In the case of a biaxially stretched film which can be stretched and stretched, it is preferably 2 to 8 times, especially 2 to 6 times in each direction.

[Silicone-Modified Polyester Polymer] In the present invention, a coating film prepared by coating an aqueous liquid containing a silicone-modified polyester polymer on at least one surface of a polyester film, and drying and stretching the coating film is provided. This silicone-modified polyester polymer (modified copolymer)
Is a copolymer in which the main chain is a polyester polymer chain and the side chain is a silicone polymer chain. The modified copolymer can be obtained, for example, by reacting a polyester polymer having a functional group in the polymer chain with a silicone polymer having a functional group capable of reacting with the functional group at least at one end.

Functionality in the chain of the polyester polymer
Group or silicone polymer Functionality of at least one end
Examples of the group include a hydroxyl group (-OH) and a carboxyl group.
Group (-COOH), amino group (-NH₂), Isocyanate
Group (-NCO), blocked isocyanate group (-
N = C (C₂H_Five) (CH₃)), Unsaturated chain hydrocarbons
Group (vinyl group (-CH = CH₂), An allyl group (-CH₂
CH = CH₂), Etc.), hydroxymethyl group (-CH₂O
H), an alkoxy group (-OCH₃, -OC₂H _Fiveetc),
Alkoxymethyl group (-CH₂OCH₃, -CH₂OC
₂H_FiveEtc.), a polyoxyalkylene group (for example, —O (C
H₂CH₂O) n-H), an oxirane group (the following formula (I)
And a oxazoline group (shown by the following formula (II))
Group), hydrogensilane group (-SiH), etc.
I can do it.

[0022]

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[0023]

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The above-mentioned functional group may be, for example, a blocked isocyanate group, -NHCOON = C (C ₂ H ₅ ).
(CH _3), -CONHCH as alkoxymethyl group
_{As shown by 2} OCH ₃ and —CONHCH ₂ OC ₂ H _5, it may be a group having the above-mentioned functional group at the terminal.

Further, the modified copolymer is a tripolymer in the polymer chain.
Methoxysilyl group (-Si (OCH ₃)₃) With
Condensation of silane coupling agent with polyester polymer
Bond the ends of the polysiloxane obtained by the reaction
It can also be obtained. The modified copolymer is
It may be obtained by a production method other than the above.

The weight ratio of the polyester polymer main chain (E) to the silicone polymer side chain (S) in the modified copolymer is E / S = 10/90 to 90/10 in terms of weight ratio.
Is preferred, and E / S = 20/80 to 80/20 is more preferred. If the E / S is less than 10/90, the abrasion resistance of the coating film is insufficient, and if the E / S is more than 90/10, the releasing property of the coating surface may be insufficient, which is not preferable. still,
The modified copolymer used in the present invention may be partially crosslinked with a crosslinking agent.

[Polyester-based polymer] The polyester-based polymer used for forming the modified copolymer is a linear polyester having a dicarboxylic acid component and a glycol component as constituent components, and is present in a portion other than the terminal groups in the polymer chain. It is a polymer having a plurality of functional groups.

Examples of the functional group include hydroxyl group, carboxyl group, amino group, isocyanate group, blocked isocyanate group, unsaturated chain hydrocarbon group (vinyl group,
Allyl group), hydroxymethyl group, alkoxy group, alkoxymethyl group, polyoxyalkylene group, oxirane group, oxazoline group and the like.

Examples of the dicarboxylic acid component constituting the polyester polymer include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid, Dodecanedicarboxylic acid, 5-Na
Examples thereof include sulfoisophthalic acid, maleic acid and fumaric acid.

Examples of the glycol component include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol and 1,6-hexanediol. , Dipropylene glycol, triethylene glycol, bisphenol, 1,4-cyclohexanedimethanol, polyethylene glycol, polytetramethylene glycol, polyalkylene oxide copolymer, bisphenol / alkylene oxide adduct, and the like.

The polyester-based polymer is preferably a copolymer of the above-mentioned constituents in order to make the coating film excellent in abrasion resistance. Further, in order to improve the dispersibility and solubility of the modified copolymer in an aqueous liquid, it is preferable to copolymerize a component having a hydrophilic group. Examples of the hydrophilic group include an alkoxy group, a hydroxyl group,
Examples thereof include an amino group, a sulfonate group, a carboxylate group, a polyoxymethylene group, and a hydroxymethyl group, and an alkali metal sulfonate group is particularly preferable. Examples of the copolymerization component having such a hydrophilic group include aromatic dicarboxylic acid having an alkali metal sulfonate base.

The average molecular weight of the polyester polymer is 5
It is preferably from 0 to 35,000, particularly preferably from 800 to 25,000. If the average molecular weight is less than 500, the abrasion resistance of the coating film may decrease, and if it exceeds 35,000, the release property of the coating film surface may deteriorate, which is not preferable.

[Silicone-based polymer] The silicone-based polymer used for preparing the modified copolymer has a polysiloxane or polydimethylsiloxane skeleton and has a functional group capable of reacting with a functional group in the polyester-based polymer chain at least at one end. It is a silicone-based polymer having a group.

Examples of the functional group include an alkoxy group, an alkoxymethyl group, a hydroxymethyl group, a methoxymethyl group, an oxirane group, a polyoxyalkylene group, an unsaturated chain hydrocarbon group (vinyl group, allyl group, etc.), a hydroxyl group, and a carboxyl group. Group, hydrogensilane group, amino group, isocyanate group, blocked isocyanate group, oxazoline group and the like.

The silicone polymer preferably contains a hydrophilic group in order to improve the dispersibility and solubility of the modified copolymer in an aqueous liquid. Examples of the hydrophilic group include an alkoxy group, a hydroxymethyl group, a methoxymethyl group, a hydroxyl group, an amino group, a sulfonate group, a carboxylate group, and a polyoxymethylene group.

The average molecular weight of the silicone polymer is 50.
It is preferably 0 to 50,000, and particularly preferably 800 to 25,000. If the average molecular weight is less than 500, the release property of the coating film surface is deteriorated, and if it exceeds 50,000, the abrasion resistance of the coating film becomes insufficient.

[Aqueous Liquid] In the present invention, an aqueous liquid containing the above-mentioned modified copolymer is used for applying a coating film to the base film. This aqueous liquid is preferably an aqueous solution of a modified copolymer, an emulsion, a dispersion or the like. A binder resin may be added to the aqueous liquid for the purpose of adjusting the adhesion between the coating film and the base film. As the binder resin, polyester resin, polyurethane resin, acrylic resin, epoxy resin,
Examples thereof include vinyl resin, acrylic modified polyester resin, polyether resin, water-soluble resin (for example, cellulose resin), silicone resin and the like.

Further, in addition to the above components, the aqueous liquid contains lubricants (inorganic or organic fine particles), surfactants, antioxidants, antistatic agents, colorants, pigments, optical brighteners, plasticizers, crosslinking agents, A slip agent (lubricant), an ultraviolet absorber, etc. can be added.

The ratio of the modified copolymer to the total solid components in the aqueous liquid is preferably 50 to 100% by weight. If this ratio is less than 50% by weight, the release characteristics of the coating film,
When a silicone resin layer is further laminated on the coating film, the adhesiveness between the coating film and the silicone resin layer is insufficient.

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

[Coating of Coating Film] In the present invention, a coating film is coated on at least one side of a polyester film by coating the aqueous liquid, followed by heat drying and stretching.
As the coating method of the aqueous liquid, any known coating method can be applied, for example, a gravure coating method, a reverse roll coating method, a die coating method, a kiss coating method, a reverse kiss coating method, an offset gravure coating method, a Mayer bar coating method, a roll. The brush method, the spray coating method, the air knife coating method, the impregnation method, the curtain coating method and the like can be applied alone or in combination. Aqueous liquid WET
The coating amount is 1 to ²⁰ g per 1 m ² of the running film,
Especially, 2 to 12 g is preferable. 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 unstretched film, the uniaxially stretched film or the stretchable biaxially stretched film described above can be used as the polyester film to be coated with the aqueous liquid. Of these, the uniaxially stretched film, particularly the longitudinal direction. It is preferable to use the uniaxially stretched film because the coating film has good abrasion resistance and the laminated film can be efficiently produced. For example, polyester is heat-melted in 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, and then an aqueous liquid is applied. And then heat-dried and then stretched 2 to 9 times in the transverse direction, and if necessary, re-stretching and / or heat treatment in the longitudinal direction and the transverse direction to form a laminated film having good abrasion resistance of the coating film. it can.

The thickness of the applied coating film is 0.005 to 3 μm.
m, particularly 0.01 to 1 μm is preferable. If the thickness of the coating film is less than 0.005 μm, the releasing property may be insufficient, and if it exceeds 3 μm, the abrasion resistance of the coating film may be insufficient, which is not preferable.

The thickness of the coated polyester film is preferably 2 to 500 μm for the uniaxially stretched film and 2 to 300 μm for the biaxially stretched film.

[Drying and Stretching Temperature] After the aqueous liquid is applied 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 is 80 to 170 ° C., and the heat treatment temperature is 1
It can be 20 to 260 ° C.

[Silicone resin layer] In the present invention,
In order to obtain a laminated film having excellent release characteristics,
A release layer containing a silicone resin can be further provided on the coating film. Examples of the silicone resin include a polydimethylsiloxane polymer obtained by addition polymerization or condensation polymerization. As a release layer having good adhesion to the coating film, the weight ratio of the silicone polymer unit (S) and the polyester polymer unit (E) in the modified copolymer is S / E ≧ 50/50. Polymers can also be used. Such a release layer can be laminated by, for example, applying a solution in which a silicone resin is dissolved in an organic solvent on the coating film and heating the solution to evaporate the solvent.

[0047]

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. Release characteristics A vinyl chloride sol was applied to the surface of the film sample on which the coating film was applied, and the film was dried to apply a vinyl chloride layer. Next, an adhesive tape was attached to the surface of the vinyl chloride layer to reinforce the vinyl chloride layer, the sample was cut into a width of 72 mm, and the peel strength (g / g / g) between the surface of the coating film and the vinyl chloride layer was measured by a tensile tester.
72 mm) was measured. The release characteristics were evaluated from the obtained peel strength.

2. Scraping resistance Two film samples were laminated so that the coated surface and the non-coated surface faced each other, and after repeatedly rubbing under a load of 145 g / cm ² , the state of the coated surface was observed and Rank. A: Almost no change in the coating film surface .... Good abrasion resistance. B: Slightly scraped coating surface..Slightly good abrasion resistance. C: Slightly scraped coating surface .... Scraping resistance. Poor sex

3. Adhesiveness of release layer Using a film sample in which a silicone release layer is laminated on the coated surface, a cotton cloth is laid on the release layer surface, and a load of 200 g is applied by a Gakken abrasion tester to the release layer surface and the cotton cloth surface. And 300
After sliding back and forth once, the appearance change of the release layer sliding surface was observed and evaluated on a scale of five. It should be noted that 5-level evaluation (5: good to 1:
Inferior), if the evaluation is 3 or more, there is no practical problem.

[Example 1] Polyethylene terephthalate having an intrinsic viscosity of 0.62 was melted by an extruder, and a film-like molten polymer was extruded from a die onto a cooling drum and rapidly cooled to obtain an unstretched film. The film was stretched 3.6 times in the machine direction to obtain a uniaxially stretched film. On one side of this uniaxially stretched film, the acid component was 2,6-naphthalenedicarboxylic acid (23 mol%), terephthalic acid (67 mol%) and 5-Na sulfoisophthalic acid (10 mol%), and the glycol component was ethylene glycol ( 61 mol%), neopentyl glycol (23 mol%), diethylene glycol (10 mol%) and trimethylolpropane (6 mol%) copolyester (E-1: average molecular weight 18,600) 51 parts by weight, and carboxyl Reaction with 49 parts by weight of potassium salt (S-1: average molecular weight 4,650) obtained by neutralizing polydimethylsiloxane having an acid value of 41 and an epoxy value of 965 and having a blocked isocyanate group at one end with an alkali Modified copolymer (K-1: average molecular weight 36,900) 75% by weight, average particle size 48n 4 wt% aqueous solution of silicon oxide 11 wt%, and polyoxyethylene nonylphenyl ether 14 consisting wt% composition was applied with a kiss roll coater. Then, the coated film was dried at 101 ° C., stretched in the transverse direction by 3.7 times, and heat-treated at 229 ° C. to form a laminated film having a thickness of 51 μm and a coating film thickness of 0.032 μm. The characteristics of this laminated film are shown in Table 1.

[Examples 2-8, Comparative Examples 1-3] A laminated film or a single film obtained in the same manner as in Example 1 except that the composition of the coating liquid and the coating film thickness were changed as shown in Table 1. The characteristics of the layer film are shown in Table 1.

Example 9 6 parts by weight of polydimethylsiloxane having the structure of the following formula (III) and a crosslinking agent having the structure of the following formula (IV) were formed on the coating film surface of the laminated film obtained in the example 1. 4 parts by weight and 90 parts by weight of a methyl ethyl ketone / toluene solvent were applied to the solution by a bar coater, and 1
The solvent was evaporated by heating at 10 ° C. for 2 minutes to apply a crosslinked silicone resin release layer having a thickness of 7 μm. As a result of evaluating the adhesiveness of the release layer, it was good (evaluation: 5).

[0054]

Embedded image

In the above formula (III), m = 3 (the number of side chain vinyl groups is 3 per molecule), and the average molecular weight is about 9.00.
0.

[0056]

[Chemical 4]

In the above formula (IV), m = 3 (the number of vinyl groups in the side chain is 3 per molecule), and the average molecular weight is about 7,50.
0.

[Comparative Example 4] On the coating film surface of the laminated film obtained in Comparative Example 2, a crosslinked silicone resin release layer was applied in the same manner as in Example 9. As a result of evaluating the adhesiveness of the release layer, it was found to be defective (evaluation: 2).

[0059]

[Table 1]

In the coating composition of Table 1, [K-2], [K
-3], [K-4] and [K-5] are the following polymers, respectively.

[K-2]: 50 parts by weight of E-2 (copolymerized polyester having the same component ratio as E-1 and an average molecular weight of 16,500) and S-1 (average molecular weight of 4,650) 5
Modified copolymer obtained by reacting with 0 parts by weight (average molecular weight: 33,000) [K-3]: E-2 (a copolymer having the same component ratio as E-1 and an average molecular weight of 16,500). Modified polyester (average molecular weight) obtained by reacting 49 parts by weight of polymerized polyester) with 51 parts by weight of S-2 (silicone polymer having the same component ratio as S-1 and an average molecular weight of 3,130). : 32, 9
40) [K-4]: Alkali-neutralized potassium salt of polydimethylsiloxane having a carboxyl group having an acid value of 41 and an epoxy group having an epoxy value of 965 (average molecular weight: 8,860) [K-5]: Methyl methacrylate (43 mol%), butyl acrylate (8 mol%), methyl acrylate (34 mol%), 2-hydroxyethyl acrylate (8 mol%), acrylamide (4 mol%) and N-methylol acrylamide (3 mol%). %) Obtained from the copolymer (A
-1: average molecular weight 19,100) 50% by weight and acid value 3
8. Alkali-neutralized sodium salt of polydimethylsiloxane having an epoxy value of 764 and a blocked isocyanate group at one end (S-3: average molecular weight 2,330) 50
Copolymer obtained by reacting with wt% (average molecular weight:
37,950)

[0062]

In the present invention, the silicone-modified polyester polymer constituting the coating film has a main chain of a polyester polymer chain having excellent adhesion to the base film, and a side chain of the silicone resin layer and a releasing property. Is a silicone-based polymer chain having excellent adhesiveness, and a polyester-based polymer chain and a silicone-based polymer chain are bonded to each other. Therefore, the laminated film of the present invention is excellent in the abrasion resistance of the coating film, and in the releasing property of the coating film surface and the adhesiveness with the silicone resin layer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 83/04 LRM C08L 83/04 LRM

Claims (3)

[Claims] 1. A polyester film, which is prepared by applying an aqueous solution containing a silicone-modified polyester polymer having a main chain of a polyester polymer chain and a side chain of a silicone polymer chain on at least one side, followed by drying and stretching. A laminated film provided with a coating film. 2. The laminated film according to claim 1, which is used as a release film for releasing a process or protecting an adhesive. 3. The laminated film according to claim 1, which is used for a release film in which a release layer containing a silicone resin is further provided on the coating film.