JPH09300566A - Polyester film laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film laminate which has outstanding properties such as adhesive force, surface hardness and wear resistance, and further, high transparency and anti-reflection capability. SOLUTION: A paint film comprising a composition composed mainly an aqueous polyester with a secondary transition point of 40-85 deg.C, a fatty acid amide and/or fatty acid bisamide is formed on at least one face of the polyester film. In addition, a hard coat layer and an anti-reflection layer are formed in that order in at least one faces of the paint film. Further, this polyester film laminate has a haze value of 1% or less as a characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film laminate, and more particularly to a polyester film laminate suitable as a surface protective material for window glass, showcases, glasses, instruments, displays, lamps and the like.

[0002]

2. Description of the Related Art Polyester films, especially biaxially stretched films of polyethylene terephthalate and polyethylene naphthalate, have excellent mechanical properties, heat resistance and chemical resistance, and are therefore widely used in various applications.

In recent years, in particular, the use as a surface protective material for window glasses, showcases, glasses, instruments, displays, lamps, etc. has attracted attention, and such applications have excellent surface hardness and abrasion resistance. , Transparent enough,
It is required to have antireflection ability.

In order to meet such requirements, it has been attempted to laminate a hard coat (HC) layer and an antireflection (AR) layer on a polyester film, but the adhesiveness with the polyester film is insufficient. There is no satisfactory result.

As a method of improving the adhesiveness of such a polyester film, for example, the secondary transition point of the base film of the transfer film for in-molding is 40 to 85 ° C.
There is known a method for improving the adhesion to the medium layer by forming a film of the water-based polyester of JP-A No. 7-1.
56358).

However, with this method, although the adhesion between the base film and the medium layer in the transfer film for in-molding is improved, the adhesion in other applications is often not sufficiently improved.

On the other hand, it is also known to form a coating film made of a composition containing a polyurethane or acrylic resin and a fatty acid amide or bisamide on the surface of a polyester film for the purpose of obtaining a flat, slippery polyester film ( JP-A-63-194948).

However, it has not been suggested that the adhesiveness is improved by using the fatty acid amide or bisamide.

Further, it is also known that a polyester resin layer is formed on a polyethylene terephthalate layer, and a radiation-curable layer having a specific composition is formed on the polyester resin layer to obtain a laminate having good surface hardness and abrasion resistance. It is (special fair 7
No. 80281) does not have versatility because it uses a special curable layer, and is not sufficiently satisfactory in terms of adhesiveness.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, is excellent in adhesiveness, has good surface hardness and wear resistance, and has sufficient transparency and antireflection ability. A polyester film laminate having the same is provided.

[0011]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that the surface of a polyester film contains an aqueous polyester and an amide of a fatty acid and / or a bisamide of a fatty acid as main components. The inventors have found that it is sufficient to form a coating film of the composition described above and then laminate the hard coat layer and the anti-reflection layer, and have completed the present invention.

That is, according to the present invention, a coating film comprising, on at least one surface of a polyester film, a composition mainly composed of an aqueous polyester having a second-order transition point of 40 to 85 ° C. and a fatty acid amide and / or a fatty acid bisamide. And a hard coat layer and an anti-reflection layer are formed in this order on at least one surface of the coating film, and the haze value is 1% or less. is there. Hereinafter, the present invention will be described in more detail.

[Polyester Film] In the present invention, the polyester constituting the polyester film is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples of such polyesters include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-naphthalene dicarboxylate, and the like. Also included are coalesced products or blends of these with small proportions of other resins.

These polyesters may optionally contain
Appropriate fillers can be included. Examples of this filler include those conventionally known as a slipperiness-imparting agent for polyester films, and examples thereof include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, carbon black, Examples thereof include silicon carbide, tin oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles and crosslinked silicone resin particles. Furthermore, colorants, antistatic agents, antioxidants, organic lubricants, catalysts and the like can be appropriately added to the polyester.

The polyester film can be obtained by melt-extruding such polyester by a conventional method to form a film, and if necessary, stretching and heat treatment. A biaxially stretched film is particularly preferable.

[Aqueous Polyester] In the polyester film laminate of the present invention, a coating film comprising a composition containing an aqueous polyester and an amide of a fatty acid and / or a bisamide of a fatty acid as main components is formed on at least one surface of the polyester film. Has been done.

The aqueous polyester which is one component for forming the coating film has a second-order transition point (Tg) of 40 to 85 ° C, preferably 45 to 80 ° C. When the second-order transition point (Tg) of the water-based polyester is less than 40 ° C, the obtained film has low heat resistance and poor blocking resistance, which is disadvantageous. On the other hand, when it exceeds 85 ° C, adhesiveness is poor. Not desirable.

The above-mentioned aqueous polyester is a water-soluble or dispersible polyester. Such water-based polyesters include terephthalic acid, isophthalic acid, phthalic acid,
2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4'-diphenyldicarboxylic acid, phenylindanedicarboxylic acid, adipic acid, sebacic acid, 5-
Na sulfoisophthalic acid, trimellitic acid, dimethylolpropionic acid and other polycarboxylic acid components and ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol , Polyesters produced from polyhydroxy compound components such as glycerin, trimethylolpropane, and alkylene oxide adducts of bisphenol A.

The above-mentioned water-based polyester is added to SO ₃ N in the polyester when it is necessary to impart further affinity.
An a group or a COONa group may be introduced, or a polyether component may be introduced.

[Famide of fatty acid, bisamide of fatty acid]
The fatty acid amide and the fatty acid bisamide are represented by R ¹ CONH ₂ , R ¹ CONHR ³ NHOCR ² , respectively, and R ¹ CO— and R ² CO— are fatty acid residues, —NHR ³ NH— Is a diamine residue. This fatty acid is preferably a saturated or unsaturated fatty acid having 6 to 22 carbon atoms, and the diamine has 1 to 15 carbon atoms.
The diamines, especially alkylenediamines are preferred. As the bisamide, N, N'-alkylenebisamide having 13 to 15 carbon atoms and 200 to 800 molecular weight is preferable.

More specifically, N, N'-methylenebisstearic acid amide, N, N'-ethylenebispalmitic acid amide, N, N'-methylenebislauric acid amide, linoleic acid amide, caprylic acid amide, Examples thereof include stearic acid amide. Among these, bisamides represented by the following formulas are particularly preferably used.

[0022]

Embedded image RCONH (CH ₂ ) nNHOCR (where RCO— represents a fatty acid residue, and n is 1 or 2) The amide of these fatty acids and / or the bisamide of the fatty acid is a composition that forms a coating film. It is preferable that the product contains 3 to 10% by weight. If the content of the fatty acid amide and / or the fatty acid bisamide is too small, sufficient adhesive strength cannot be obtained, and the slipperiness and blocking resistance tend to be reduced. Adhesion may be reduced, the coating film may be embrittled, and haze may be increased.

[Coating film] In the present invention, the composition constituting the coating film formed on the surface of the polyester film has an average particle size of 0.15 µm or less, particularly 0.01 to 0.
It preferably contains 1 μm of a surface-roughening substance.

Specific examples of the surface-roughening substance include calcium carbonate, magnesium carbonate, calcium oxide, zinc oxide, magnesium oxide, silicon oxide, sodium silicate, aluminum hydroxide, iron oxide, zirconium oxide, barium sulfate, and oxidation. Inorganic particles such as titanium, tin oxide, antimony trioxide, carbon black, molybdenum disulfide, acrylic cross-linked polymer, styrene cross-linked polymer, cross-linked silicone resin, fluororesin, benzoguanamine resin, phenol resin, nylon resin, polyethylene wax Examples thereof include organic fine particles and the like. Of these,
For the water-insoluble solid substance, it is preferable to select ultrafine particles having a specific gravity of not more than 3 in order to avoid sedimentation in the aqueous dispersion.

These surface-roughening substances not only roughen the surface of the coating film, but also have the function of reinforcing the coating film by the fine powder itself, and further the function of imparting blocking resistance to the coating film and the slipperiness on the polyester film. It exerts an imparting action.

The rough surface substance is preferably contained in the composition forming the coating film in an amount of 5 to 30% by weight. Particularly, when using relatively large particles having an average particle size of 0.1 μm or more, the range is 5 to 10% by weight, and when using particles having an average particle size of 0.01 to 0.1 μm, 8 to 30%.
It is preferable to select from within the range of weight%. If the content of these surface-roughening substances in the coating film becomes too large, the haze value of the obtained laminate will exceed 1%, and the transparency will be deteriorated.

The above composition of the present invention is used in the form of an aqueous solution, an aqueous dispersion or an emulsion to form a coating film. In order to form a coating film, a resin other than the above-mentioned aqueous polyester, an antistatic agent, a colorant, a surfactant, an ultraviolet absorber, etc. can be added, if necessary.

The coating liquid can be applied to the polyester film at any stage, but it is preferable to apply the coating liquid to the polyester film during the production process, and further, the coating liquid is applied to the polyester film before orientation crystallization is completed. It is preferably applied.

Here, the polyester film before the crystal orientation is completed means an unstretched film, a uniaxially oriented film obtained by orienting the unstretched film in either the longitudinal direction or the transverse direction, and further in the longitudinal direction and the transverse direction. And a biaxially stretched film which has been stretched and oriented in two directions at a low ratio (before the biaxially stretched film is finally re-stretched in the longitudinal direction or the transverse direction to complete the oriented crystallization).

Among them, it is preferable to apply a coating solution of the above composition to an unstretched film or a uniaxially stretched film oriented in one direction, and carry out longitudinal stretching and / or transverse stretching and heat setting as it is.

When the coating liquid is applied to the film, the film surface is subjected to physical treatment such as corona surface treatment, flame treatment, plasma treatment or the like as a pretreatment for improving the coatability, or with the coating composition. It is preferable to use a chemically inert surfactant together with this. This surfactant is to promote the wetting of the aqueous coating liquid to the polyester film, for example, polyoxyethylene alkyl phenyl ether, polyoxyethylene-fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, Examples thereof include anionic and nonionic surfactants such as alkyl sulfates, alkyl sulfonates and alkyl sulfosuccinates.

The coating amount of the coating liquid is 0.02 when the thickness of the coating film is 0.02.
The amount is preferably in the range of 0.3 μm, preferably 0.07 to 0.25 μm. If the thickness of the coating film is too thin, the adhesive strength will be insufficient, and conversely if it is too thick, blocking may occur or the haze value may increase.

As a coating method, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method and the like can be used alone or in combination. The coating film may be formed on only one side or both sides of the film, if necessary.

[Hard Coat Layer] In the present invention, the hard coat layer is laminated on at least one surface of the coating film of the polyester film coated with the above coating film (hereinafter sometimes referred to as “easy adhesive polyester film”). .

As the hard coat layer, a hard coat layer which is usually used, such as a radiation curing type or a silane type, can be used. A radiation-curable hard coat layer is particularly preferable, and a UV-curable hard coat layer is particularly preferably used.

Examples of the UV curable composition used for forming the hard coat layer include UV curable compositions such as urethane-acrylate, epoxy-acrylate and polyester-acrylate.

In order to form a hard coat layer on the coating film of the easily adhesive polyester film, the composition is coated on the coating film, and the composition is cured by heating, irradiation with radiation (for example, ultraviolet rays) or the like. Good. The thickness of the hard coat layer is not particularly limited, but usually about 1 to 15 μm is suitable.

[Anti-reflection layer] An anti-reflection layer is further formed on the hard coat layer thus formed.

The antireflection layer is formed by alternately laminating a plurality of layers having different refractive indexes, and its structure is generally well known. For example, a low refractive index layer (SiO ₂ , 30
nm) -high refractive index layer (TiO ₂ , 30 nm) -low refractive index layer (SiO ₂ , 30 nm) -high refractive index layer (TiO ₂ , 1
00 nm) -those having a layer structure of low refractive index layer (SiO ₂ , 100 nm), high refractive index layer (ITO, 20 nm)-
Low refractive index layer (AlSiO, 20 nm) -high refractive index layer (I
TO, 88nm) -Low refractive index layer (AlSiO, 88n)
m), a high refractive index conductive layer (ITO,
20 nm) -Low refractive index layer (SiO ₂ , 20 nm) -High refractive index conductive layer (ITO, 93 nm) -Low refractive index layer (SiO
₍₂ , 93 nm) is known.

In the present invention, any antireflection layer can be applied, and it is usually laminated on the hard coat layer by sputtering.

[0041]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. In the following examples and comparative examples, haze value, adhesive strength, abrasion resistance, and reflectance were evaluated by the following methods.

(1) Haze value The haze value was measured using a haze measuring instrument (NDH-20) manufactured by Nippon Denshoku Industries Co., Ltd. The haze value was evaluated according to the following criteria. ⊚: Haze value ≤ 0.5% …… very good haze value ◯: 0.5% <haze value ≦ 1.0% …… good haze value ×: 1.0% <haze value …… bad haze value

(2) Adhesive strength: 5 μm thick on the surface of the coating film of the easily adhesive polyester film.
m hard coat layer is formed and cross cut (100 squares of 1 mm ² ) is applied, and 24 is cut on it.
Stick a cellophane tape (made by Nichiban Co., Ltd.) with a width of mm,
After rapidly peeling at a peeling angle of 180 degrees, the peeled surface was observed and evaluated according to the following criteria. 5: Peeling area is less than 10% ...... Adhesive strength is extremely good 4: Peeling area is 10% or more and less than 20% ...... Good adhesion strength 3: Peeling area is 20% or more and less than 30% …… Adhesive strength is slightly good 2: Peeling Area is 30% or more and less than 40% ...... Adhesive strength is poor 1: Peeling area exceeds 40% ...... Adhesive strength is extremely poor

(3) Abrasion resistance The surface was rubbed with steel wool # 0000 to examine whether or not it was scratched. Those without scratches were evaluated as good abrasion resistance, and those with scratches were evaluated as poor abrasion resistance.

(4) Reflectance The ratio of the reflected light flux to the incident light flux perpendicular to the surface of the laminate is measured in the wavelength range of 400 nm to 570 nm, and the average is taken as the reflectance.

[Example 1] Molten polyethylene terephthalate ([η] = 0.65) was extruded from a die, cooled by a cooling drum by a conventional method to give an unstretched film, and then stretched by a factor of 3.6 in the machine direction. After that, an aqueous liquid having a concentration of 8% of the following coating composition was uniformly applied to one surface thereof with a roll coater.

[Coating film composition] The acid components are terephthalic acid (90 mol%), isophthalic acid (6 mol%) and 5-
Copolyester of potassium sulfoisophthalate (4 mol%), glycol component of ethylene glycol (95 mol%) and neopentyl glycol (5 mol%) 80% by weight N, N′-ethylene bis Caprylic acid amide 5% by weight Acrylic resin fine particles (average particle size 0.03 μm) 10% by weight Polyoxyethylene nonylphenyl ether 5% by weight

Thereafter, while being dried at 95 ° C., the film was stretched in the transverse direction at 120 ° C. by a factor of 3.8, and heat-set at 220 ° C. to obtain an easy-adhesive film having a thickness of 40 μm. The thickness of the coating film was 0.15 μm.

Next, UV having the following composition was formed on the coating film.
The curable composition was uniformly applied using a roll coater so that the film thickness after curing would be 5 μm.

[UV Curing Composition] Pentaerythritol acrylate 45% by weight N-methylolacrylamide 40% by weight N-vinylpyrrolidone 10% by weight 1-hydroxycyclohexylphenyl ketone 5% by weight

Then, a high pressure mercury lamp having an intensity of 80 W / cm was used to irradiate the composition with ultraviolet rays for 30 seconds to cure it, thereby forming a hard coat layer. The adhesive strength at this time was 4.

On this hard coat layer, a low refractive index layer (SiO ₂ , 30 nm) and a high refractive index layer (TiO ₂ , 30 nm)
nm), low refractive index layer (SiO ₂ , 30 nm), high refractive index layer (TiO ₂ , 100 nm), low refractive index layer (SiO ₂ ,
100 nm) was formed in this order by sputtering.

The resulting laminate had a haze value of ⊚, a refractive index of 0.7%, little reflection, no scratches even when strongly rubbed with steel wool, and good abrasion resistance.

[Comparative Example 1] In Example 1, N, N '
-A laminate was prepared under the same conditions as in Example 1 except that the coating film composition containing no ethylenebiscaprylic acid amide was used. Table 2 shows the evaluation results of the laminate. This stack is
The haze value, abrasion resistance, and reflectance were the same as in Example 1, but the adhesive force evaluated in the same manner as in Example 1 was 2,
The adhesive strength was poor.

[Examples 2-9, Comparative Examples 2-4] Example 1
A laminate was obtained in the same manner as in Example 1 except that the composition of the coating composition was changed as shown in Table 1. Table 2 shows the evaluation results of the laminate.

[0056]

[Table 1]

In Table 1, the symbols (P, Q, R, S, T, A, B, C, D, G, H, Y and Z) of the coating composition are the following polymers or Indicates a compound.

[Aqueous polyester] P: acid component is terephthalic acid (90 mol%), isophthalic acid (6 mol%) and potassium 5-sulfoisophthalate (4 mol%), glycol component is ethylene glycol (95 mol%) And a copolymerized polyester of neopentyl glycol (5 mol%) (Tg = 68 ° C.)

Q: 2,6-naphthalenedicarboxylic acid (50 mol%), terephthalic acid (46 mol%) and sodium 5-sulfoisophthalate (4 mol%) as the acid component, and ethylene glycol (70 mol%) as the glycol component. ) And bisphenol A ethylene oxide 2 mol adduct (30 mol%) copolyester (Tg = 80 ° C.)

R: terephthalic acid (85 mol%) as the acid component
And isophthalic acid (15 mol%), glycol component is ethylene glycol (57 mol%), 1,4-butanediol (40 mol%), diethylene glycol (2 mol%) and polyethylene glycol (molecular weight 600)
Copolymerized polyester (Tg = 47 ° C.) (1 mol%)

S: acid component of terephthalic acid (70 mol%), isophthalic acid (28 mol%) and sodium 5-sulfoisophthalate (2 mol%), glycol component of ethylene glycol (70 mol%) and bisphenol A Ethylene oxide 4 mol adduct (30 mol%)
Copolyester (Tg = 30 ℃)

T: 2,6-naphthalenedicarboxylic acid (81 mol%), isophthalic acid (15 mol%) and sodium 5-sulfoisophthalate (4 mol%) as the acid component, and ethylene glycol (70 mol%) as the glycol component. ) And a copolymerized polyester of bisphenol A with 2 mol of ethylene oxide (30 mol%) (Tg = 90 ° C.)

[Fatty acid amide, fatty acid bisamide] A: N, N'-methylenebissutheric acid amide B: N, N'-ethylenebispalmitic acid amide C: caprylic acid amide D: stearic acid amide

[Roughening Material] G: Acrylic resin fine particles (average particle size 0.03 μm) H: Silica (average particle size 0.12 μm)

[Surfactant] Y: polyoxyethylene nonylphenyl ether Z: polyoxyethylene / polyoxypropylene copolymer The obtained results are shown in Table 2.

[0066]

[Table 2]

As is clear from the results of Example 1 and Comparative Example 1 and the results shown in Table 2, the laminates of the present invention (Examples 1 to 9) have transparency, adhesive strength, abrasion resistance and antireflection. All of the performances were good, but when an aqueous polyester having a secondary transition point of more than 85 ° C. was used (Comparative Example 2), the adhesive strength was poor, and an aqueous polyester having a secondary transition point of less than 40 ° C. was used. In the case (Comparative Example 3), the adhesive strength was insufficient and the blocking resistance of the film before forming the hard coat layer was insufficient. Further, when the fatty acid amide and the fatty acid bisamide were not included (Comparative Example 4), the adhesive strength was poor.

[Examples 10 to 13] In Example 4,
A laminate was obtained in the same manner as in Example 4 except that the compounding amount of N, N'-methylenebisstearic acid amide in the coating composition was changed as shown in Table 3. The results are shown in Table 3, and particularly good adhesive strength was obtained when the blending amount of the fatty acid bisamide was 3 to 10% by weight (Examples 11 and 12).

[0069]

[Table 3]

[Examples 14 to 17 and Comparative Examples 5 and 6] In Example 4, the roughening substance and the addition amount thereof were changed as shown in Table 4 to obtain films having different haze values. The results are shown in Table 4, and when the haze value exceeds 1% (Comparative Examples 5 and 6), the transparency was poor and it was unsuitable for a surface protective material that requires transparency. On the other hand, the laminate of the present invention having a haze value of 1% or less (Examples 14 to 1)
7) showed good transparency and slipperiness.

[0071]

[Table 4]

Example 18 On the coating film of the easily adhesive polyester film obtained in Example 5, UV having the following composition was used.
The curable composition was uniformly applied using a roll coater so that the film thickness after curing would be 5 μm.

[UV Curing Composition] Pentaerythritol triacrylate 20 wt% N-methylol acrylamide 40 wt% Trimethylol propane triacrylate 25 wt% N-vinylpyrrolidone 10 wt% P-phenoxydichloroacetophenone 5 wt%

Then, a high pressure mercury lamp having an intensity of 80 W / cm was used to irradiate ultraviolet rays for 30 seconds to cure them, thereby forming a hard coat layer. The stacking force at this time was 4. A high refractive index layer (ITO,
20 nm), low refractive index layer (AlSiO, 20 nm), high refractive index layer (ITO, 80 nm), low refractive index layer (AlSi
O, 88 nm) was formed in this order by sputtering. The obtained laminate has a haze value of ⊚ and a reflectance of 0.
At 7%, there was little reflection and wear resistance was good.

[0075]

Industrial Applicability According to the present invention, it is possible to provide a polyester film laminate having excellent adhesive strength, good surface hardness and abrasion resistance, and having sufficient transparency and antireflection property. .

Claims (5)

[Claims] 1. A coating film is formed on at least one surface of a polyester film, the coating film being composed of an aqueous polyester having a second-order transition point of 40 to 85 ° C. and a composition containing a fatty acid amide and / or a fatty acid bisamide as main components. Further, a hard coat layer and an anti-reflection layer are formed in this order on at least one surface of the coating film, and the haze value is 1
% Or less, a polyester film laminate. 2. The polyester film laminate according to claim 1, wherein the composition contains 3 to 10% by weight of a fatty acid amide and / or a fatty acid bisamide. 3. The polyester film laminate according to claim 1, wherein the composition is mainly composed of an aqueous polyester and a bisamide of a fatty acid. 4. The polyester film laminate according to claim 1, wherein the fatty acid bisamide is a bisamide represented by the following general formula. Embedded image RCONH (CH ₂ ) nNHOCR (where RCO— represents a fatty acid residue, and n is 1 or 2) 5. The polyester film laminate according to claim 1, wherein the hard coat layer is a radiation-curable hard coat layer.