JP3284714B2 - Polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film. More specifically, the present invention relates to a polyester film having flexibility, excellent transparency and weather resistance.

[0002]

2. Description of the Related Art As a polyester-based flexible base material, a hard segment such as polyethylene terephthalate is copolymerized with a long-chain aliphatic dicarboxylic acid such as dodecanedicarboxylic acid or dimer acid (Japanese Patent Publication No. 42-8709); A quaternary copolymerization of terephthalic acid and dimer acid as an acid component and 1,4-butanediol and ethylene glycol as an alcohol component (JP-A-3-23193)
0) has been proposed.

[0003]

However, in the method of simply copolymerizing a long-chain aliphatic dicarboxylic acid or a long-chain branched aliphatic dicarboxylic acid with polyethylene terephthalate, the resulting sheet changes its physical properties over time, There is a problem that the appearance changes due to occasional bending whitening or the like. In addition, the sheet obtained from a terpolymer of terephthalic acid and dimer acid as the acid component and 1,4-butanediol and ethylene glycol as the alcohol component has poor weather resistance and particularly severe yellowing. There is a problem of impairing the appearance.

[0004]

SUMMARY OF THE INVENTION The present invention proposes the following constitution in order to solve the above-mentioned problems and to obtain a film having flexibility, excellent transparency and weather resistance. That is, 5 to 30 mol% of an aliphatic dicarboxylic acid residue having an alkylene group having 20 or less carbon atoms as the acid component consists polyesters only the components 1,4-butanediol residue as diol component, benzophenone The present invention relates to a substantially non-oriented polyester film containing 0.05 to 10% by weight of a polyester, benzotriazole-based or indole-based ultraviolet absorber based on polyester.

[0005] (hereinafter abbreviated as polyester A) polyesters of the invention, 5 to 30 mol% of an aliphatic dicarboxylic acid residue having an alkylene group having 20 or less carbon atoms as the acid component, and a diol component of 1,4 Butanediol residue
Only is a constituent. It is preferable that an aromatic dicarboxylic acid component is further included as an acid component constituting the polyester A. As the aromatic dicarboxylic acid component, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyl Examples thereof include sulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, and benzophenone dicarboxylic acid. Of these, terephthalic acid and naphthalenedicarboxylic acid are preferable. Also, these aromatic dicarboxylic acid components,
One type or two or more types may be used in combination.

The content of the aliphatic dicarboxylic acid residue having an alkylene group having 20 or less carbon atoms contained as an acid component is 5 to 30 mol%, preferably 5 to 25 mol%. If the dicarboxylic acid component is less than 5 mol%, the flexibility is lowered, and if it is more than 30 mol%, the heat resistance is lowered, which is not preferable. The aliphatic dicarboxylic acid component used includes oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecadionic acid, dodecadionic acid, brassic acid, and tetradecadione Examples thereof include straight-chain aliphatic dicarboxylic acids such as acid, pentadecadionic acid, hexadecadionic acid, and heptacadionic acid. In particular, adipic acid, sebacic acid, dodecadionic acid and the like can be preferably used for improving the reactivity of the polymer, the weather resistance, the bending whitening property and the like.

Further, polyester A is a diol component
Is composed solely of the 1,4-butanediol component .
Therefore , there is no change with time and no thermal whitening during processing .

Further, a long-chain aliphatic dicarboxylic acid residue having an alkylene group having 21 or more carbon atoms may be contained as long as the desired properties are not impaired.

The polyester A of the present invention has a difference (Tc) between the cold crystallization temperature (Tcc) and the glass transition temperature (Tg).
ΔTcg defined by (c-Tg) is preferably 50 ° C. or lower, more preferably 30 ° C. or lower, and particularly preferably 25 ° C. or lower. If ΔTcg is too large, problems such as an increase in tensile Young's modulus over time occur. Further, it is preferable that the Tg is 10 ° C. or lower because the flexibility is excellent.

The polyester film of the present invention needs to contain a benzophenone-based, benzotriazole-based or indole-based ultraviolet absorber, and particularly preferably contains a benzotriazole-based ultraviolet absorber.
Benzophenone-based ultraviolet absorbers are compounds in which one or more oxy groups are present ortho to the carbonyl group in the benzophenone skeleton, such as 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ', 4-trihydroxybenzophenone,
2,2 ', 4,4'-tetrahydroxybenzophenone and derivatives thereof. Examples of the benzotriazole-based ultraviolet absorber include (2'-hydroxyphenyl) benzotriazole, (2'-hydroxy-5'-methylphenyl) benzotriazole,
(2'-hydroxy-5'-octylphenyl) benzotriazole, (2'-hydroxy-3'-tert-
(Butyl-5'-methylphenyl) -5-chlorobenzotriazole and its derivatives.

In the present invention, the content of the ultraviolet absorbent is 0.05 to 10% by weight. Preferably 0.05 to 8
%, Particularly preferably 0.05 to 5% by weight.

In the present invention, it is preferable to provide a heat seal layer on at least one surface of the polyester film, and it is more preferable that this heat seal layer is also made of polyester. For example, polyester constituting the heat seal layer (hereinafter abbreviated as polyester B)
Having a melting point of 120 to 240 ° C.
A temperature of 0 to 220 ° C. is preferable because not only the self-heat adhesion, but also the heat adhesion to other materials such as polyvinyl chloride and polyethylene is improved.

As an acid component constituting polyester B,
Terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfondicarboxylic acid, diphenyletherdicarboxylic acid,
Examples thereof include aromatic dicarboxylic acid components such as benzophenone dicarboxylic acid, and aliphatic dicarboxylic acid components such as sebacic acid and dimer acid. The diol component is at least one diol component selected from aliphatic, alicyclic and aromatic diols having 10 or less carbon atoms, preferably 1,4-butanediol and ethylene glycol. For example, isophthalic acid copolymerized polybutylene terephthalate, dimer acid copolymerized polybutylene terephthalate, and the like can be preferably used.

Particularly, in order to improve the heat sealing property,
The polyester B has 5 to 30 mol% of a long-chain aliphatic dicarboxylic acid residue having an alkylene group having 16 or more carbon atoms, and 80 mol% or more as a diol component has a 1,4-butanediol residue as a main component. It is preferably polyester. The long-chain aliphatic dicarboxylic acid having an alkylene group having 16 or more carbon atoms includes, for example, octadecadionic acid, nonadecadionic acid, eicosandioic acid, heneicosandioic acid, docosandioic acid, tricosandioic acid, tetracosandione Dimer acid obtained by dimerizing acid, pentacosandioic acid, hexacosandioic acid, heptacosandioic acid, octacosandioic acid, nonacosandioic acid, triacontanedioic acid and unsaturated fatty acid having 10 to 25 carbon atoms And its hydrogenated product and its ester-forming derivative. In particular, those containing a dimer acid component are preferable because of their excellent transparency and heat sealability.

It is preferable that polyester A and polyester B have different constitutions.

The intrinsic viscosity of the polyester A is preferably 0.5 to 2.0 dl / g, more preferably 0.7 to 2.0 dl / g.
When it is 1.8 dl / g, both film forming properties and mechanical properties become good.

Although the thickness of the polyester film of the present invention is not particularly limited, it is preferably 1 to 1000 μm.
More preferably, it is 10 to 500 μm, particularly preferably 1 to 500 μm.
5 to 300 μm. Further, the thickness of the heat seal layer is preferably 1/500 to 1/2 of the thickness of the polyester film.

Further, the polyester film of the present invention has
It is preferable that the haze in terms of 00 μm is 0.1 to 20% because the transparency and the appearance after processing are good.
More preferably, it is set to 0.2 to 10%.

The polyester film of the present invention needs to be substantially non-oriented in terms of flexibility. The Young's modulus of the film is preferably in the range of 10 to 200 kg / mm ² , more preferably 30 to 120 kg / m 2.
m ² . Even if the tensile Young's modulus is too small or too large, the winding property when forming a flexible film,
A problem arises in the workability of the film.

Further, the polyester film of the present invention may have a nucleating agent, an antioxidant, an anti-coloring agent, a pigment, a dye, a mold release agent, a lubricant, a flame retardant, an antistatic agent, an inorganic And / or organic particles can be blended.

In particular, it is preferable that particles having an average particle diameter of about 0.01 to 10 μm are contained in the polyester in an amount of 0.01 to 5% by weight in order to provide lubricity. Typical of such particles are talc, kaolin calcium carbonate, titanium oxide, silicon oxide, calcium fluoride, lithium fluoride, alumina, barium sulfate, zirconia,
Mica, calcium phosphate, crosslinked polystyrene particles,
Examples include silicone particles. Further, these particles can be contained in the heat seal layer.

The polyester film of the present invention may have an acrylic resin film formed on at least one side.
Further, an ultraviolet absorber may be blended with the acrylic resin. Examples of the kind of the ultraviolet absorber to be blended include conventionally known ultraviolet absorbers such as salicylic acid compounds, cyanoacrylate compounds, benzophenone compounds, and benzotriazole. And inorganic particles such as zinc oxide. This may be a single type or a combination of two or more types.

Next, a method for producing the polyester film of the present invention will be described, but it is needless to say that the present invention is not limited thereto.

The method for producing polyester is well known in the art, and any method can be employed. For example, a dicarboxylic acid component and a glycol component are subjected to a direct esterification reaction, or, when a dialkyl ester of a dicarboxylic acid component is used, transesterified with a glycol component, and heated under reduced pressure to remove excess glycol component. By removing, polyester can be obtained. At this time, if necessary, a transesterification catalyst or a polymerization catalyst may be used, or a stabilizer such as a phosphorus compound may be added. The polyester thus obtained is supplied to a well-known melt extruder represented by an extruder, and is heated to a temperature equal to or higher than the melting point of the polyester to be melted. The molten polymer is continuously extruded from a slit-shaped die and is forcibly cooled to obtain a film.

In a preferred embodiment of the present invention, in the case of a polyester film provided with a heat seal layer made of polyester B, polyester A and B are dried, and then the polyester A resin and the B resin are separately extruded. And melt-extruded to form an A / B or B / A / B laminate in a polymer manifold that enters the die manifold or die. The laminated body basically composed of the laminated polyesters A and B is melt-extruded into a sheet or a cylindrical shape, and subjected to static application quenching casting to obtain a laminated polyester film.

The ultraviolet absorber can be mixed at any stage from the production of the polymer to the extrusion, but the method of melt-kneading with the polyester to pelletize it and then supplying it to the extruder has the following effects. It is preferable because it increases. Also, crystal nucleating agent, antioxidant, anti-coloring agent, pigment,
Additives such as dyes, mold release agents, lubricants, flame retardants, antistatic agents, particles and the like can also be mixed at any stage.

The film obtained as described above may be subjected to corona discharge treatment, coating, etc., if necessary.

[0028]

[Method of measuring characteristics] The characteristics were measured as follows.

(1) Intrinsic viscosity (IV) Measured at 25 ° C. using o-chlorophenol as a solvent. The unit is dl / g.

(2) Melting point (Tm), glass transition temperature (T
g) It was determined using a differential scanning calorimeter DSC2 (manufactured by PerkinElmer). The mixture was melted and maintained at 280 ° C. for 5 minutes under a nitrogen stream, and then cooled using liquid nitrogen. When the temperature of the sample thus obtained was increased at a rate of 10 ° C./min, the change in specific heat based on the transition from the glassy state to the rubbery state was read, and this temperature was used as the glass transition temperature (Tg).
And The endothermic peak temperature based on the melting of the crystal was defined as the melting point (Tm). ΔTcg is defined by the following equation.

ΔTcg = Tcc−Tg

(3) Mechanical properties Regarding Young's modulus, breaking strength and breaking elongation, AST
It was measured according to the MD-882-81 (A) method.

(4) Haze (H ₁₀₀ ) in terms of 100 μm
(Transparency) It was measured according to JIS-K-6714, and determined by the following equation.

H ₁₀₀ = H × 100 / d where H is the measured haze value (%), and d is the film thickness (μm) of the haze measurement part.

(5) Weather Resistance Irradiation was carried out for 500 hours using a sunshine weather meter, the breaking elongation after irradiation was measured, and expressed as a retention rate (%) with respect to the breaking elongation before irradiation.

(6) Appropriate processing and change in appearance A PVC film with white and black colors was heated at 180 ° C. and 3 kg /
mm ² , heat-sealing with a heating time of 5 seconds, heat-sealing power and whitening property, bending whitening property when the film after heat-sealing is bent 90 degrees, change in appearance after leaving indoor for about 3 months Was visually judged to be appropriate for use.

[0037]

【Example】

Example 1 Polybutylene terephthalate / dodecanedicarboxylic acid (hereinafter abbreviated as D) copolymer (D component amount = 20 mol%, Δ
Tcg = 11.3 ° C., melting point = 190 ° C., IV = 0.8
0) After vacuum drying 10 kg of the resin at 150 ° C. for 3 hours,
150 g of (2′-hydroxy-5′-octylphenyl) benzotriazole was added, fed to a counter-rotating twin-screw extruder, melted at 310 ° C., extruded from a 3 mmφ die, quenched, cut into pellets, A polyester containing an ultraviolet absorber was obtained.

The obtained polyester was melted at 230 ° C. with an extruder having a diameter of 40 mm, and the length was 400 m.
m and a T-die having a linear die with an interval of 1 mm was cast on a metal drum whose surface was kept at 15 ° C. by electrostatic application and cooled and solidified to obtain a polyester film.

The film thus obtained has a Young's modulus of 5
2 kg / mm ² , haze 0.9%, elongation retention after exposure to sunshine weather meter for 500 hours was 92%. Further, a film having no change in appearance after three months was obtained.

COMPARATIVE EXAMPLE 1 The film of Example 1 was prepared except that no ultraviolet absorber was added.
The film obtained in the same manner deteriorates so that the elongation at break after 500 hours of irradiation with the sunshine weather meter cannot be measured.

Examples 2 and 3 In Example 1, the amount of the ultraviolet absorber added was 0.8% by weight.
A film was obtained in the same manner as in Example 1 except that the content was changed to 3.0% by weight.
The elongation retention after irradiation for 0 hour was 88% and 94%, respectively.

Example 4 A film was obtained in the same manner as in Example 1 except that 1.5% by weight of an ultraviolet absorber was added to 2,2 ', 4 trihydroxybenzophenone. Elongation retention rate after irradiation for 500 hours is 76
%Met.

Example 5 The polyester containing the ultraviolet absorbent used in Example 1 was used for the core layer (layer A), and (2'-hydroxy-5'-octylphenyl) benzotriazole was used for the surface layer (layer B).
Polybutylene terephthalate / hydrogenated dimer acid (hereinafter abbreviated as DA) copolymer containing 5% by weight and 0.1% by weight of silica particles (average particle size 2 μm) (DA component amount = 17 mol%, melting point = 190) C., IV = 0.80) After drying each resin, it was melt extruded using a separate extruder, and laminated into three layers in a die so as to have a B / A / B (lamination ratio of 1: 8: 1). And extruded into a sheet. The thus obtained film had a Young's modulus of 40 kg / mm ² , a haze of 1.0%, and a retention of elongation after 500 hours of sunshine weather meter of 90%. Also, PVC film and 1
When heat sealing was performed at 80 ° C., 3 kg / mm ² and a heating time of 5 seconds, the heat sealing property was good.

[0044]

[Table 1]

[Table 2]

[0045]

The polyester film of the present invention not only has flexibility but also has excellent weather resistance, so that it can be suitably used as a seal for affixing it to agricultural films, decorative boards, walls and the like.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-216830 (JP, A) JP-A-4-202439 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 67/00-67/02

Claims (2)

(57) [Claims] 1. A 5-30 mol% of aliphatic dicarboxylic acid residues having an alkylene group having 20 or less carbon atoms as the acid component, and a diol component of 1,4-butanediol residues
A benzophenone-based, benzotriazole-based or indole-based ultraviolet absorber in an amount of 0.05 to 10% by weight based on the polyester, and is substantially non-oriented. Polyester film. 2. The polyester film according to claim 1, wherein the ultraviolet absorbent is a benzotriazole type.