KR0141317B1 - Improved polyester film - Google Patents

Abstract

The present invention relates to a polymer film having excellent antistatic properties, printability and thermal stability, and having light weight and improved texture, wherein a polyester resin and a polyolefin resin are mixed at a predetermined ratio, and a titanium compound and a fluorescent organic pigment are added thereto. The polymer film prepared by adding, melt-mixing, extruding and stretching, and externally applying a quaternary ammonium salt to the surface of the film has not only improved physical properties, improved antistatic properties, printability and thermal stability, but also beautiful appearance. Good quality texture and weight can be used as a substitute for paper

Description

Improved Polymer Film

The present invention relates to a polymer film, and more particularly, by applying a quaternary ammonium salt to the film surface prepared by mixing a polyester resin and a polyolefin resin and adding a titanium compound and a fluorescent organic pigment, antistatic properties and printability The present invention relates to a polymer film which can be used as a paper substitute because it has excellent and low apparent density, which improves lightness, texture, and film properties such as thermal stability.

Currently, polyolefin-based films containing inorganic particles have been generally used as a substitute for paper used for calendars, advertising papers, and high-quality wrapping papers, but these have poor impact resistance, heat resistance, oil resistance, chemical resistance, and environmental resistance. In recent years, the use of an improved polymer film based on a polyester film as a substitute for paper has been considered.

Polyester, especially polyethylene terephthalate is widely used in the manufacture of medical and various industrial products because of its physical and chemical stability, high mechanical strength, and excellent heat resistance, durability, chemical resistance and electrical insulation. Due to its excellent properties such as elastic modulus, dimensional stability, and activity, it is widely used in various applications such as magnetic recording media, capacitors, photographic films, industrial products, packaging materials, and labeling products. Also. In recent years, as a substitute for paper, the use of label supplies, printer award papers, barcode printer award papers, posters, calendars, maps, dust-free paper, display boards, white boards, photo papers, copy papers, and specialty printed publications has gradually increased. It is increasing.

However, the polyester film is too stiff to be used as a substitute for paper, such as hwahwa, not only different from the texture, but also does not give a paper-like feeling in transparency and color, and due to the high density of the polyester itself, At the same time, it is inconvenient to store and use.

Therefore, attempts have been actively made to develop a polymer film which tends to tend to a soft texture such as paper while utilizing the excellent properties of the existing polyester film. As an example, Japanese Patent Application Laid-Open Nos. 87-243120 and 90-206622 incorporate inorganic particles into polyester, and Japanese Patent Laid-Open No. 83-50625 incorporates a foaming agent into polyester to prepare polyester. Japanese Patent Laid-Open Publication Nos. 82-49648 and 88-168441 disclose a method of reducing weight, and by mixing and stretching a polyolefin resin to polyester to form fine pores on the surface and inside of the film to improve the surface properties of the film, The weight was reduced.

However, according to the conventional manufacturing technology, when the film is prepared by adding a large amount of inorganic particles, the specific gravity of the polyester is increased and the weight of the film is not easily reduced. There is a problem that it is difficult to control the particle size of this poor and added inorganic material, and it is difficult to adjust the physical properties of the film. In addition, in the method of dry blending the polyolefin resin to the polyester, the heat resistance of the polyolefin is poor, not only increases the amount of oligomers generated during the extrusion molding process, but also causes thermal aging to significantly reduce the mechanical properties of the final film. In particular, polyolefins have a disadvantage in that a high amount of static electricity is generated due to their characteristics, causing problems of information loss when used for advanced information recording applications such as magnetic cards.

Accordingly, the present inventors have repeatedly studied to solve the above problems while providing and reducing the quality and quality of paper-like texture and whiteness while improving the properties of the existing polyester film. The resin is mixed and melt mixed by adding a titanium compound and fluorescent organic pigment as an additive, followed by extrusion molding and stretching, and a quaternary ammonium salt is applied to the surface of the film, improving processing characteristics and thermal stability, and smooth texture, excellent antistatic property and printing. The present invention has been completed by discovering that a polymer film suitable as a substitute for a high-functional paper having good aptitude and a beautiful appearance can be produced.

Accordingly, it is an object of the present invention to provide a lightweight polymer film having improved physical properties and exhibiting a texture such as paper and excellent antistatic and printability.

In order to achieve the above object, according to the present invention, a polyolefin resin 5 based on 100 parts by weight of polyester based on a polyester resin having an intrinsic viscosity of 0.4 to 0.9 dl / g consisting of ethylene terephthalate of 60 parts by weight or more of the main repeating unit 5 To 40 parts by weight of the mixture, rutile titanium dioxide having an average particle diameter of 0.1 to 3 ㎛ and fluorescent organic pigments having light emission characteristics in the short wavelength region of visible light 0.1 to 20 parts by weight and 0.05 to 0.30, respectively, based on 100 parts by weight of polyester It is added by weight, and a quaternary ammonium salt of the following general formula (1) is applied to the film surface in an amount of 0.01 to 0.1 g / m 2 to provide a polymer film.

In the above formula

R ₁ is an alkyl group having 10 to 20 carbon atoms,

R ₂ is a hydrocarbon having a chain structure of less than 4 carbon atoms,

R ₃ and R 4 are each independently an alkyl group having less than 5 carbon atoms,

X ⁻ is a counter anion.

The polymer film according to the present invention has an apparent density of 1.0 to 1.2 g / cc to improve light weight, maintain surface resistance of 10 ¹⁰ kPa or less, and have improved adhesion.

In the present invention, the polyester resin and the polyolefin-based resin are mixed in a predetermined ratio, thereby extruding and stretching to improve the surface properties of the film and to improve the surface properties of the film by utilizing fine pores on the surface and inside of the film generated at the compatibility window between the two resins. Lowering the weight, reducing the weight, and improving the heat resistance of the polyolefin, thereby increasing the thermal stability of the film. In addition, by adding the inorganic particles and the optical brightener and applying an antistatic agent on the surface of the film, it was possible to give the film improved whiteness, hiding and excellent antistatic property and printability.

Hereinafter, the present invention will be described in detail.

The polyesters of the present invention have an intrinsic viscosity of 0.4 to 0.9 dl / g, preferably 0.5 to 0.5 dl / g when measured at 35 ° C. at a concentration of 0.3 g per 25 ml of orthochlorophenol. When the intrinsic viscosity is less than 0.4 dl / g, breakage during stretching occurs in the film manufacturing process, thereby significantly lowering productivity, and lowering physical properties such as mechanical strength in the final film. In the case where the intrinsic viscosity exceeds 0.9 dl / g, the productivity in the post process is greatly lowered due to difficulties in the manufacturing process, such as an increase in the melt viscosity and an unstable extrusion process during the film forming process.

As described above, the polyester of the present invention is a resin obtained by condensation of a polyhydric organic acid component and a polyhydric alcohol component, and the organic acid is preferably a carboxylic acid, particularly an aromatic dicarboxylic acid, and the alcohol is preferably a glycol, particularly an alkylene glycol. .

Specific examples of the aromatic dicarboxylic acid include dimethyl terephthalic acid, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, cyclohexane dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl dicarboxylic acid, diphenylether dicarboxylic acid, atracene dicarboxylic acid and α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylic acid, of which dimethy terephthalic acid and terephthalic acid are particularly preferred.

Specific examples of the alkylene glycol include ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol and hexylene glycol, of which ethylene glycol is particularly preferred.

60 weight% or more of the polyester of this invention is a homopolyester of polyethylene terephthalate, and can copolymerize within 40 weight%. The copolymerization copolymer component may be a diol compound such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylene, 1,4-cyclohexanedimethanol, sodium 5-sulforesorcinin, idipic acid, sodium 5 Dicarboxylic acids such as sulfoisophthalic acid and the like, and polyfunctional carboxylic acids such as trimellitic acid, pyromellitic acid and the like.

Titanium dioxide compounds added to the polymer film as an inorganic filler are classified into rutile and anatase forms depending on the crystal structure. The anatase type titanium dioxide compound having a cubic crystal structure has high water adsorption, which causes coagulation in the compounding process, thereby lowering optical properties of the film surface, and is easily deteriorated by external environment, especially temperature, sunlight, and moisture. The rutile titanium dioxide compound having a hexagonal crystal structure effectively absorbs ultraviolet rays harmful to the film and changes energy in the form of heat, thereby preventing the organic polymer from being altered by ultraviolet rays. Titanium dioxide compounds are also involved in the concealability of the final film. In order to improve the concealability of the film, it is important to maximize the light scattering effect, and light scattering can be adjusted by the distance and average size of the inorganic material. If the inorganic particles are too large or the spacing is too small, the diffraction hardly occurs. On the other hand, if the inorganic particles are too small, the light just passes through the inorganic particles, so the diameter of the titanium dioxide used is 1 / the wavelength of the light to be scattered. Slightly smaller than two is preferred.

The average particle diameter of the titanium dioxide compound is 0.1 to 3.0㎛, the addition amount is 0.1 to 20 parts by weight based on 100 parts by weight of polyester, the average particle diameter and the amount may vary depending on the thickness and the use of the final film. When the added amount of titanium dioxide is more than 20 parts by weight, not only the mechanical properties such as the strength and flexibility of the film are lowered, but when the input amount is more than a certain amount, the whiteness and light transmittance are almost constant as the input amount is increased, thereby increasing the effect of the large amount. Can't see

The fluorescent organic pigment used in the present invention is a bisbenzoazole-based pigment that absorbs light energy in the ultraviolet region and dissipates the energy to the short wavelength region of visible light to emit light, thereby causing visible light of the film. The short wavelength reflectance fall is suppressed. The reflectance at 440 nm, which is a short wavelength region of visible light, is preferably 75% or more. For this purpose, the amount of the pigment is 0.05 to 0.30 parts by weight based on 100 parts by weight of polyester. If the added amount is less than 0.05 parts by weight, the increase in reflection is hardly observed at 440 nm, and when the amount is more than 0.30 parts by weight, the reflectance at 440 nm is too high, resulting in a bluish white film.

The polyesters used in the polymer films of the present invention may also contain one or more known additives such as dispersants, electrostatic agents, crystallization promoters, nucleating agents, antiblocking agents and the like in an effective amount without impairing the effects of the present invention. It may include.

The polyolefin resin to be used in the present invention is selected from polyethylene, polypropylene, and rollimethylene, and two or more of these may be mixed. The ratio of the stilly polyolefin resin mixed in the polymer film of the present invention is 5 to 40 parts by weight, preferably 8 to 25 parts by weight based on 100 parts by weight of polyester.

The polyolefin-based resin is mixed with the polyester resin to produce a film through compression molding and stretching process, and fine pores are formed on the surface and inside of the film due to poor compatibility between the polyolefin crab resin and the polyester resin. Surface characteristics are improved and at the same time reduced in weight. In order to produce a film having excellent properties, it is preferable that the polyolefin resin used in the present invention has a melt index in the range of 0.1 to 25 (g / 10 min, 200 ° C, 5.0 Kg load).

The polyester resin and the polyolefin-based resin are usually dry blended, and may be biaxially stretched through a direct extruder. However, in the present invention, the first resin is first prepared by mixing the two resins in a compounding melt mixing method, and then the resin is prepared. By using the method of biaxial stretching after remelting extrusion, it was possible to improve the dispersibility between the two resins and to improve the uniformity of physical properties of the produced film.

The compounding melt hop-hip process is preferably melt blended using a compounder having two axes of rotation in the same or two directions. Each additive and the inlet temperature of the compound into which the polyester and polyolefin-based resin is added should be maintained in the range of 200 to 250 ℃, if the respective temperature is lower than the above range, there will be a molten polyester known, When the temperature is higher than the above range, pyrolysis occurs, and a film lightening effect cannot be obtained. In addition, the temperature of the mixed resin discharged should be adjusted to the rotational speed of the compound rotating shaft and the discharge amount of the resin to be 225 to 285 ℃.

The process for producing a film from the mixed resin obtained as described above is not particularly stable, and the polymer chip is mixed by extrusion compounding by the compounding melt mixing method according to the present invention to obtain a polymer chip, which is then a conventional method. Extruded into an unstretched sheet. Subsequently, an aqueous solution of ammonium salt of the following general formula (1) is externally applied to the sheet surface, and then biaxially stretched according to a conventional polyester film stretching method to prepare a biaxially oriented polymer film.

In the above formula,

R ₁ is an alkyl group having 10 to 20 carbon atoms,

R ₂ is a hydrocarbon having a chain structure of less than 4 carbon atoms,

R ₃ and R 4 are independently of each other an alkyl group having less than 5 carbon atoms,

X ⁻ is a counter anion.

Conventionally, in the production of a polymer film, an internally added antistatic agent has sometimes been used to remove static electricity on the surface of a film caused by mixing of polyolefin resins. However, when the internal additive antistatic agent is required to apply a magnetic material such as a barcode or a magnetic card, it is difficult to use as a magnetic recording medium because it causes irregular projections on the surface of the film, causing recording loss. There is also a limit. Therefore, in the present invention, the quaternary ammonium salt of the general formula (1) as an antistatic agent is applied to the film surface with an external coating agent. The quaternary ammonium salt is dissolved in purified water or alcohol and used as an aqueous solution at a concentration of 0.1 to 10% by weight, preferably 2 to 5% by weight, and the solid active ingredient is contained in an amount of 0.01 to 0.1 g / m ^{2 on} the surface of the film. Apply to exist. If the solid active ingredient of the antistatic agent is applied to the surface of less than 0.01g / m ² can not not only give sufficient antistatic properties to the film, but also the uncoated site is generated, there is a possibility that the variation of physical properties between sites, 0.1g When applied at a concentration higher than / m ² , undissolved particles may be present, resulting in poor appearance of the film and deterioration of post-printing strength.

Representative examples of the quaternary ammonium salts include, but are not limited to, butyloxyethyl hydroxyethyl orthodecyloxy ammonium salt, bishydroxydecyl propyl ammonium salt, hydroxybutyl dodecyloxybutyl ethyl ammonium salt, and the like.

The ammonium salt aqueous solution of the general formula (1) may be applied to the unstretched sheet or to the surface of the uniaxially or biaxially stretched film. The stretching process is carried out at a stretching ratio of 2.5 to 6.0 times in the longitudinal and transverse directions, respectively, at a stretching temperature of 60 to 150 ° C., in accordance with a conventional polyester film stretching process.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. In Examples and Comparative Examples of the present invention, various performance evaluation of the produced film was carried out by the following method.

(1) apparent density

The apparent density of the film was measured by the immersion method keeping a density gradient tube consisting of carbon tetrachloride and n-heptane at 25 ℃.

(2) glossiness

The glossiness of the film was measured according to the method of ASTM D523 using black green as a reference diameter at a measurement angle of 60 °.

(3) Antistatic characteristics

The antistatic property of the film was measured by using an insulation resistance meter of Huhlett Packard of the United States under the applied voltage condition of 500V at 20 ℃ and 65% relative humidity. The smaller the surface resistance, the better the antistatic property of the film.

(4) Color-b value

The color-b value (color b value, yellowness) of the film was measured using a C light source as a measurement light source at a measurement angle of 2 ° using a light source color difference meter (Japan Color Industry Co., Ltd., Model: SZS-80).

(5) breaking strength

The breaking strength of the film was obtained by measuring the tensile strength of the film according to ASTMD882 using Instrong.

(6) Ink and Coating Liquid Adhesive

The degree of cohesion of the Rheji index standard solution of the Japanese Hwagwang Pharmaceutical Co., Ltd. was checked to evaluate the adhesion of the film according to the following host.

○: When no aggregation occurs

Δ: 2 to 4 aggregations per unit area (10 cm x 10 cm) occur

X: 5 or more aggregations per unit area (10 cm x 10 cm) occur

Example 1

Terephthalic acid and ethylene glycol were mixed in an equivalent ratio of 1 to 2, and the reaction was carried out by adding a transesterification catalyst to obtain a polyethylene terephthalate monomer, i.e., bis-2-hydroxyethyl terephthalate, and then a conventional polycondensation catalyst was added thereto. The polycondensation reaction was performed to prepare a polyester resin having an intrinsic point of 0.610 dl / g. Subsequently, 10 parts by weight of a conventional sheet-forming polypropylene resin was mixed with 100 parts by weight of polyester, and 5 parts by weight of rutile titanium dioxide having a hexagonal crystal structure having an average particle diameter of 0.5 μm and oxa were obtained. 0.10 parts by weight of a fluorine-based optical brightener was added and melt mixed in a compounding manner under a compound rotation rpm of 350 and a discharge resin temperature of 285 ° C. to prepare a primary mixed resin. Next, the obtained mixed resin was dried and melt-extruded in a conventional manner to form an unstretched sheet, and then an aqueous solution of 2% by weight of butyloxyethyl hydroxyethyl orthodecyloxy ammonia sulfide salt was externally formed on the sheet surface. After application, the biaxially stretched film was biaxially stretched at 2.5 times the longitudinal draw ratio and the transverse draw ratio in the usual manner to prepare a biaxially stretched film having a thickness of 50 μm, and various performance evaluations were performed. The film prepared as described above had good overall physical properties as shown in Table 1.

[Examples 2 to 6]

The polyester film was prepared by repeating the procedure of Example 1 while changing the final loading concentration of each additive and the mixing ratio of the polypropylene resin as shown in Table 1 below. The physical properties of the thus prepared film were generally good as shown in Table 1.

[Comparative Examples 1 to 8]

The polyester film was prepared by repeating the procedure of Example 1 while changing the final loading concentration of each additive and the mixing ratio of the polystyrene resin as shown in Table 1 below. The physical properties of the film thus prepared were generally poor as shown in Table 1.

As described above, according to the present invention, a polyester resin and a polypropylene resin are mixed, and a titanium compound and a fluorescent organic pigment are added thereto, followed by melt mixing in a compounding method to prepare a mixed resin, followed by extrusion molding and stretching. Polymer films prepared by external application of quaternary ammonium salts on the surface of the film have not only improved physical properties of the film, improved antistatic properties, printability and thermal stability, etc., but also good quality texture and light weight, which are useful as paper substitutes.

Claims (3)

At least 60% by weight of the main repeating unit is mixed with 5 to 40 parts by weight of a polyolefin resin based on 100 parts by weight of the polyester resin having an intrinsic viscosity of 0.4 to 0.9 dl / g consisting of ethylene terephthalate and an average particle diameter of 0.1. 0.1-20 parts by weight and 0.05-0.30 parts by weight of the rutile type titanium dioxide compound having a light emission property in the short wavelength region of the visible light and the fluorescence-based titanium dioxide are added, respectively, based on 100 parts by weight of polyester. A polymer film, characterized in that the quaternary ammonium salt of 1) is applied to the film surface in an amount of 0.01 to 0.1 g / m 2: In the above formula, R ₁ is an alkyl group having 10 to 20 carbon atoms, R ₂ is a hydrocarbon having a chain structure of less than 4 carbon atoms, R ₃ and R 4 are each independently an alkyl group having less than 5 carbon atoms, X ⁻ is a counter anion. The film according to claim 1, wherein the polyolefin resin has a melt index in the range of 0.1 to 25 (g / 10 minutes). The film according to claim 1, wherein the polymer film has an apparent density of 1.0 to 1.2 g / cc.