KR100363870B1 - Paper-substituted white porous polyester multilayer film and its manufacturing method - Google Patents

Abstract

The present invention relates to a method for producing a paper-substituted white porous polyester multilayer film, and in producing a white paper-substituted white porous film containing a polyester resin and a polyolefin resin, the film layer comprising a polyester resin layer alone. By separating and laminating the polyester film layer mixed with the polyolefin resin, the surface tension to the film surface layer can be increased to improve printability, and the size, shape and distribution of pores present in the film can be appropriately formed. The present invention provides a porous white polyester multilayer film and a method of manufacturing the same, which not only have excellent whiteness, texture, and light weight, but also greatly improve the stiffness peculiar to the polyester film to exhibit a soft texture similar to paper. Purpose, and to achieve the above The present invention is a resin mixture of 65 to 95% by weight of a polyester resin containing inorganic fine particles and 5 to 35% by weight of a granular polyolefin resin having an average diameter of 8 μm or less, and an elasto graft polymerized with succinic anhydride or maleic anhydride. A polyester resin layer in which a mer copolymer is mixed in an amount of 0.3 to 2.0% by weight based on the total weight of the resin mixture as an intermediate layer (B layer), and at least one side of the intermediate layer (B layer) contains inorganic fine particles. A surface-substituted white porous polyester multilayer film is characterized in that the surface layer (layer A) is laminated and at least uniaxially stretched.

Description

White-colored multipore polyester layered film used in place of paper and the method of producing the same

The present invention relates to a white porous polyester multilayer film, and more particularly, a white porous polyester that can be used as a substitute for paper because of its excellent lightness and texture, good antistatic properties and printability, as well as excellent hiding properties. A multilayer film and a method for producing the same.

In general, a white polyester film prepared by mixing white inorganic particles with a polyester resin maintains polyester's inherent properties in terms of mechanical properties, heat resistance, and numerical stability, and has excellent light blocking property, whiteness, and color and texture similar to paper. Since it can be displayed, it has been mainly used as a paper substitute for calendars, flyers, high-quality wrapping paper, printed decorative paper, wallpaper, and the like.

In addition, since the polyolefin-based film also has advantages of light weight and excellent surface properties, it has been widely used as a substitute for paper in packaging materials and printing materials together with the polyester resin.

However, such a white polyester film has the advantages described above, but has a disadvantage in that the material is stiff and the touch is smooth and does not exhibit a texture similar to paper, and the light weight is insufficient.

In addition, the polyolefin-based film used as a substitute for paper has a disadvantage in that the mechanical and thermal properties are poor.

As a method for compensating the disadvantages of the two resins as described above, it is possible to produce a paper-like texture while maintaining the excellent properties of the polyester film and to reduce the weight per unit area to a weight of polyolefin-based film. Bars Japanese Patent Laid-Open No. 62-243120 and Japanese Patent Laid-Open No. 2-206622 disclose a method of adding inorganic particles to polyester, and Japanese Laid-open Patent No. 58-50625 combine foams with polyester. To reduce the weight is disclosed. In addition, Japanese Unexamined Patent Publication No. 57-49648 discloses that by blending and stretching a polyolefin-based resin in polyester, the disadvantages between dissimilar resins are compensated for, and fine pores are formed on the surface and inside of the film to improve the surface of the film and A method of making itself lighter is disclosed.

The prior art as described above uses such properties because fine pores are formed on the surface and inside of the film due to the incompatibility between the two resins in the process of the polyolefin resin is mixed with the polyester resin and subjected to the extrusion, molding and stretching process. By using polyolefin resin in combination with polyester resin, it is possible to improve the surface property of the film and realize weight reduction. However, there is a limit in the formation of pores and the pores themselves are uneven, so that the pores are partially exposed or recessed on the surface. There are many problems such that printing on the film surface becomes uneven, and when polyolefin resin particles such as polypropylene are exposed to the surface, the surface tension is lowered, which also causes a problem of poor printability.

In addition, the texture and surface characteristics such as paper can be changed very sensitively depending on the shape and distribution of the pores present in the film, the film prepared by the prior art as described above has a pore distribution in the formation of pores If not properly designed, the desired texture of the paper will not be obtained, and the weight and fairness will be adversely affected.

This is because if the size of the pores present in the film is small, the specific gravity becomes high and heavy, whereas if the pores are too large, problems occur in the processability due to breakage, etc., in order to obtain a film that is not sufficient for use as a substitute for paper. Similarly, matters concerning the distribution of pores existing in the film should be properly designed.

The present invention solves the problems of the prior art as described above, in producing a white paper substitute white porous film comprising a polyester resin and a polyolefin resin, a film layer and a polyolefin resin of the polyester resin layer alone By separating and stacking the polyester film layer mixed with each other, it is possible to improve the printability by increasing the surface tension to the film surface layer, and to ensure that the size, shape and distribution of the pores present in the film can be properly formed. It is an object of the present invention to provide a porous white polyester multilayer film and a method for producing the same, which are excellent in texture and lightness, as well as greatly improving the stiffness peculiar to the polyester film to exhibit a soft texture similar to paper.

The present invention for achieving the above object is a resin mixture of 65 to 95% by weight of polyester resin containing inorganic fine particles and 5 to 35% by weight of granular polyolefin resin having an average diameter of 8 μm or less and succinic anhydride or anhydrous The resin layer in which maleic acid graft-polymerized elastomer copolymer is mixed in an amount of 0.3 to 2.0% by weight based on the total weight of the resin mixture is used as an intermediate layer (B layer), and at least one side of the intermediate layer (B layer) is an inorganic fine particle. It provides a paper-substituted white porous polyester multilayer film, characterized in that the surface layer (A layer) made of a polyester resin layer containing is laminated and at least uniaxially stretched.

In addition, a resin mixture was prepared by first mixing 65 to 95% by weight of polyester resin containing inorganic fine particles and 5 to 35% by weight of granular polyolefin resin having an average diameter of 8 μm or less, and then succinic anhydride or maleic anhydride was graft-polymerized. The intermediate layer (B layer) resin and the surface layer (A layer) of the polyester resin containing inorganic fine particles by mixing the prepared elastomer copolymer at 0.3 to 2.0% by weight based on the total weight of the resin mixture. Co-extruded to be laminated on at least one side of (B layer) and at least uniaxially stretched, wherein the thickness ratio (A layer thickness / B layer thickness) of the surface layer and the intermediate layer is 0.01 to 0.2, wherein the white porous poly substitute paper It provides a method for producing an ester multilayer film.

In the present invention, the polyester resin used in the intermediate layer (B layer) and the surface layer (A layer) is a copolymer resin mainly composed of polyethylene terephthalate (Polyethylent Terephthalate) and preferably contains 0.005 to 0.5% by weight of the hindered phenolic compound. . In addition, the polyester resin contains 0.1 to 10% by weight of inorganic fine particles having a diameter of 0.1 to 10μm. Such inorganic fine particles are preferably a mixture of any one or two of titanium dioxide, barium sulfate, calcium carbonate, silica, kaolin, talc or zeolite.

In addition, the content of the polyolefin resin mixed with the polyester resin in the intermediate layer (B layer) is 5 to 35% by weight relative to the total amount of the intermediate layer resin, the melt index is 1 to 25gr / min. In addition, the polyolefin resin is preferably polymerized or copolymerized from at least one monomer selected from ethylene, propylene, butene, pentene, hexene or octene.

Furthermore, in the manufacturing process of the intermediate | middle layer (layer B) which consists of polyester resin and polyolefin resin, it mixes polyester resin and polyolefin resin in the weight ratio of 95: 5-65:35, and manufactures a primary mixed resin. 0.3 to 2.0% by weight of the copolymer grafted with succinic anhydride or maleic anhydride based on the primary mixed resin in step. The primary resin mixture and the polyester resin containing no polyolefin are melt-extruded through different extruders to form a film sheet using a feed block die, and the film sheet is biaxially stretched. The white porous polyester multilayer film of the invention is produced.

In the step of forming the film sheet, the average diameter of the polyolefin in the intermediate layer (B layer) film sheet is 20 µm or less, more preferably 8 µm or less, and the average number of polyolefins in the film sheet 25,000 µm ² is 50 or more, more Preferably, 80 or more are preferable.

Hereinafter, a method of manufacturing a white porous film of the present invention and the principle of the present invention will be described in detail.

The polyester resin used in the present invention can be prepared by polycondensing an acid component having aromatic dicarboxylic acid as a main component and a glycol component having alkylene glycol as a main component as polyethylene terephthalate, and as the aromatic dicarboxylic acid, dimethyl terephthalate , Terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid and the like can be used, among which dimethyl terephthalate and terephthalate Acids are preferred.

In addition, examples of the alkylene glycol may include ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, hexylene glycol, and ethylene glycol is preferable.

The polyester resin of the present invention is prepared according to a conventional polyester synthesis method, 70% by weight or more is preferably polyethylene terephthalate and copolymerized within 30% by weight. More preferably 5 to 20% by weight copolymerization. Specific examples of such copolymerization components include diol compounds such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylene glycol, 1,4-cyclohexanedimethanol and 5-sodium sulfolezocin, isophthalic acid and azi And polyfunctional dicarboxylic acid components such as dicarboxylic acid components such as pinic acid and 5-sodium sulfoisophthalic acid, trimethyl acid and pyromethyl acid.

In order to prepare the polyester resin of the present invention, inorganic particles may be added. The inorganic particles are added to the polyester resin for the purpose of controlling optical properties such as light transmittance or color, and controlling friction coefficient, surface roughness and fine touch, and the particle size is preferably in the range of 0.1 to 10 μm, and the amount of addition is 0.1 to 10 % By weight is preferably 0.1 to 5% by weight.

In addition, when the amount is less than 0.1% by weight, the effect of addition is insignificant, and when the amount is more than 10% by weight, the surface characteristics of the film are inferior, and thus a paper-like texture cannot be obtained.

Examples of the inorganic fine particles that can be used include titanium dioxide, calcium carbonate, barium sulfate, silica, kaolin, talc, zeolite and the like.

In addition, polycondensation catalysts, dispersants, electrostatic agents, crystallization accelerators, antiblocking agents and inorganic lubricants may be further added as additives in addition to the main components when preparing the polyester resin of the present invention. Materials used for this purpose are used.

In the present invention, the polyolefin resin mixed with the polyester resin is preferably polymerized from at least one component monomer among ethylene, polymethylpentine, propylene, butene, pentene, hexene, and octene, and in particular, propylene is a main component. It is more preferable that it superposed | polymerized using the monomer as an auxiliary component. In addition, it is preferable that the melt index is 1 to 25 gr / min, which is efficient for pore formation, and occupies 5 to 35% by weight based on the total amount of resin. When it is less than 5% by weight, the formation of pores is generally uneven and the content of total pores. When the film is less, the film becomes stiff, and when the weight ratio is higher than 35% by weight, the formation of pores is sufficient, but the heat resistance and mechanical properties of the polyolefin are reduced, resulting in poor heat resistance and mechanical properties and poor processability.

The core of the present invention is that when the polyester resin and the polyolefin resin are mixed, a large amount of polyolefin resin is uniformly distributed in the polyester resin by the addition of a compatibilizer, and the contact area of the polyolefin in contact with the polyester resin is also increased, thereby increasing the total porosity. Also, these pores are uniformly distributed. Therefore, the density of the finally obtained film is lowered, thereby making it lighter and increasing the flexibility of the film.

As described above, in the case of the intermediate layer (B layer) mixed resin produced by mixing the surface layer (A layer) resin made of polyester resin only, the polyester resin, the polyolefin resin, and the compatibilizer, each extruder Through the melt extrusion, feed block die to obtain a laminated film sheet of A / B or A / B / A in the same manner as conventional polyester production method, and then the sheet in the longitudinal and transverse directions, respectively The stretching is 2 to 5 times, preferably 3 to 3.5 times.

At this time, it is preferable that the thickness ratio of A and B layers becomes 0.01-0.2 of A layer / B layer. When the layer A / B is less than 0.01, the thickness of the layer A is too thin, so that the effect of preventing the lowering of the surface tension of the bar is insignificant. .

The dispersion state of the polyolefin resin in the mixed resin, especially the film sheet before stretching, has a significant influence on the properties of the film finally obtained. The dispersion state of the polyolefin resin can be known by observing a compounding chip or a sheet made after remelting with an electron microscope. In other words, the compounding chip or the remelted sheet can be observed using an electron microscope, and the dispersion state can be evaluated by measuring the average diameter and the number of particles of the polyolefin particles dispersed in the sheet.

When the average diameter of the polyolefin particles is 20μm or less, the uniform dispersibility and the improvement of film properties are apparent, and when the average number of polyolefins is more than 80 in 25000μm ² , the density decrease and the flexibility improvement are apparent.

Hereinafter, the present invention will be described in more detail through examples, comparisons, and experimental examples. However, the scope of the present invention is not limited to the following Examples.

<Example 1>

Ethylene glycol is mixed with dimethel terephthalate 1 at an equivalent ratio of 2, and then transesterified by adding a transesterification catalyst to the compound. Titanium dioxide having an average particle diameter of 0.8 μm was added to the polyester base to 2% by weight and a polycondensation catalyst to complete the polycondensation reaction, thereby preparing a surface layer (A layer) polyester resin having an ultimate viscosity of 0.66 dl / gr. .

85 wt% of the polyester resin thus prepared and 15 wt% of the homopolypropylene resin having a melt index of 3.5 were mixed, and then 1 wt% of the maleic anhydride-grafted elastomer was added thereto, followed by compounding to form an intermediate layer (B layer). ) Resin was prepared.

Each of these resins were melted and extruded through a coextruder through an extruder according to a conventional polyester film production method to form a sheet, and then stretched at a ratio of 3.5 times the longitudinal stretch ratio and 3.8 times the transverse stretch ratio to a thickness of 100 μm, and A layer / B. A biaxially oriented multilayer film having a thickness ratio of 0.1 expressed by layers was prepared. The characteristics of this film were measured in the following experimental example, the size and number of pores, the average particle diameter of the inorganic fine particles, the apparent density, the flexibility and the surface tension of the film and the results are shown in Table 1 below.

Experimental Example

Pore size and number

The cross section is observed using an electron scanning microscope manufactured by JEOL of Japan, and then measured by an image analyzer.

Average particle size of inorganic particles

The slurry of the inorganic fine particles dispersed in ethylene glycol was measured using the centrifugal particle size measuring device of Shimadzu, Japan, and is represented as a volume average particle diameter.

-Apparent density-

A density gradient tube consisting of carbon tetrachloride and normal heptane is maintained at 25 ° C. and measured by ups and downs.

Film Flexibility

Compared to paper, the flexibility of the porous film was classified into good, normal, and poor.

Surface tension

After 10 seconds of applying the Nure reagent to the film surface, the surface tension was measured based on the aggregation of the reagent.

Printability

An oil-based evaluation ralca consisting of 27 parts by weight of water, 10 parts by weight of n-butanol, 25 parts by weight of methyl cellosolve, 10 parts by weight of methyl ethyl ketone, 25 parts by weight of cellulose acetate butyrate, and 3 parts by weight of rhodamine ratio (dye) It is applied to the film surface to be coated with wire bar # 18, sufficiently dried in a dryer at 90 ° C. for 1 minute, and then drawn 100 scales on the surface using a cross cutter, and then peeled off with an adhesive tape. In this case, the evaluation was performed based on the remaining number of scales which did not peel out of 100 scales. The larger the number of scales, the better the printability (ink).

Good: No peeling off at all

Normal: 1 to 10 peeled

Poor: Exfoliates more than 10

<Examples 2 to 5>

A multilayer film was obtained by the same method as Example 1 except that the thickness ratio (A layer / B layer) of the A layer and the B layer was changed as shown in Table 1 below. Toxicity was evaluated and the results are shown in Table 1 below.

<Comparative Examples 1 to 5>

A multilayer film was obtained by the same method as Example 1 except that the thickness ratio (A layer / B layer) of the A layer and the B layer was changed as shown in Table 1 below. Toxicity was evaluated and the results are shown in Table 1 below.

division Floor thickness ratio additive Olefin Resin Pore distribution Printability Final Film Properties Inorganic particulates Compatibilizer Type content Average number Average diameter density Surface tension flexibility (A floor / B floor) Kinds wt% wt% Copolymerization component wt% 2500 μm ² μm - g / cm ³ kg / cm kg / mm ² Example 1 0.1 TiO ₂ 2 1.0 PP 15 90 7.5 Good 1.100 40 Good Example 2 0.5 TiO ₂ 2 1.0 PP 15 95 7.5 Good 1.050 41 Good Example 3 0.13 TiO ₂ 2 1.0 PP 15 110 7.3 Good 1.130 40 Good Example 4 0.8 BaSO ₄ 2 1.0 PP-PE 15 120 7.2 Good 1.080 42 Good Example 5 0.1 BaSO ₄ 2 1.0 PP-PE 15 115 7.0 Good 1.110 41 Good Comparative Example 1 0.21 TiO ₂ 2 1.0 PP 15 82 7.9 Good 1.200 40 Good Comparative Example 2 0.25 TiO ₂ 2 1.0 PP 15 92 7.5 Good 1.250 41 Bad Comparative Example 3 0.22 TiO ₂ 2 1.0 PP 15 88 7.5 Good 1.230 40 Bad Comparative Example 4 0.008 TiO ₂ 2 1.0 PP 15 110 7.4 Bad 1.050 35 Good Comparative Example 5 0.005 TiO ₂ 2 1.0 PP 15 90 7.1 Bad 1.020 32 Good

The compatibilizer in Table 1 above is (styrene-ethylene / butylene-styrene) -maleic hydride.

As shown in Table 1, the films prepared from Examples 1 to 5 according to the present invention had excellent texture, flexibility, and good appearance, and included pores as long as the amount of various additives was maintained in a limited range in the present invention. It can be seen that the distribution is maintained at a desirable level so that the lightness and printability of the film are very good.

However, as can be seen from Table 1, unlike the case of the embodiment, when the amount of the additives added is outside the preferred range defined in the present invention, the obtained film was found to be poor in at least one or more of the various properties evaluated. In particular, in Comparative Examples 1 to 3, in which the thickness of the A layer / B layer was 0.2 or more and the thickness of the A layer was too thick, flexibility was very poor. On the other hand, the thickness ratio of the A layer was less than 0.01. In Comparative Examples 4 to 5 having the following thicknesses, the surface tension was very low, indicating that the printability was poor.

As described above, the present invention provides a polyester film layer comprising a polyester resin layer alone and a polyester film layer mixed with a polyolefin-based resin in the manufacture of a white paper substitute white porous film containing a polyester resin and a polyolefin-based resin. By separating and laminating, it is possible to improve the printability by increasing the surface tension on the film surface layer, and to ensure that the size, shape, and distribution of pores present in the film can be appropriately formed. In addition, it is a porous white polyester multilayer film and its useful invention which can greatly improve the stiffness peculiar to a polyester film to exhibit a soft texture similar to paper.

Claims (9)

Elastomer copolymer graft-polymerized resin mixture of 65 to 95% by weight of polyester resin containing inorganic fine particles and 5 to 35% by weight of granular polyolefin resin having an average diameter of 8 μm or less and succinic anhydride or maleic anhydride A surface layer made of a polyester resin layer containing inorganic fine particles on at least one side of the intermediate layer (B layer), wherein the resin layer mixed at 0.3 to 2.0% by weight based on the total weight of the resin mixture is used. A white porous polyester multilayer film for paper substitutes, wherein (A layer) is laminated and at least uniaxially stretched. The paper-substituted white porous polyester multilayer film of claim 1, wherein the thickness ratio of the A layer thickness and the B layer thickness (A layer thickness / B layer thickness) is 0.01 to 0.2. The paper-substituted white porous polyester multilayer film according to claim 1 or 2, wherein the resin mixture of the intermediate layer comprises 65 to 95% by weight of polyester resin and 5 to 35% by weight of polyolefin resin. 4. The paper-substituted white porous polyester multilayer film of claim 3, wherein the polyolefin resin has a melt index of 1 to 25 gr / min. The paper-substituted white porous polyester multilayer film of claim 4, wherein the polyolefin-based resin is copolymerized from at least one monomer selected from ethylene, methylpentine, propylene, butene, pentene, hexene, and octene. 6. The paper-substituted white porous polyester multilayer film of claim 5, wherein the average particle diameter of the inorganic fine particles added to the polyester resin is 0.01 to 10 µm and added at 0.01 to 10 wt% based on the total weight of the polyester resin. The paper-substituted white porous polyester multilayer film of claim 6, wherein the inorganic fine particles are a single or a mixture of titanium dioxide, calcium carbonate, barium sulfate, silica, kaolin, talc, zeolite. 8. The white porous polyester multilayer film for paper substitutes according to claim 6, wherein the longitudinal draw ratio in the drawing process is 2 to 5 times, the transverse draw ratio is 2 to 5 times, and the density of the entire film is 0.8 to 1.20 gr / cm ³ . . 65 to 95% by weight of the polyester resin containing inorganic fine particles and 5 to 35% by weight of the granular polyolefin resin having an average diameter of 8 μm or less were first mixed to prepare a resin mixture, followed by graft polymerization of succinic anhydride or maleic anhydride. Intermediate layer (B layer) resin obtained by mixing an elastomer copolymer at 0.3 to 2.0% by weight based on the total weight of the resin mixture, and a surface layer (A layer) made of a polyester resin containing inorganic fine particles. Coextruded to be laminated on at least one side of layer B) and at least uniaxially stretched, wherein the thickness ratio (A layer thickness / B layer thickness) of the surface layer and the intermediate layer is 0.01 to 0.2. Manufacturing method of multilayer film