KR19990080662A - Laminated porous polyester film and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a porous layer comprising a polyolefin resin and a polyester number formed on at least one surface of the porous layer and including 0.01-15% by weight of inorganic fine particles with respect to the total amount of the polyester resin and the polyester resin. In the layered porous polyester film of the layered layer, the polyolefin resin is copolymerized from at least one monomer selected from the group consisting of ethylene, propylene, butene, pentene, hexene, octene and methylpentene, and the melt index is 1-25 g / min. 80% by weight or more of the polyester-based repeating unit is a resin consisting of ethylene terephthalate, butylene terephthalate, ethylene naphthalate or butylene naphthalate, and the inorganic fine particles are titanium dioxide, calcium carbonate, barium sulfate, Group consisting of silica, kaolin, talc and zeolite The present invention relates to a laminated porous polyester film having a diameter of 0.1-10 μm, wherein the polyester film according to the present invention is light, and has excellent mechanical strength, heat resistance and numerical stability. It can be used in various fields, such as advertising paper, high-quality wrapping paper, printing paper, wallpaper.

Description

Laminated porous polyester film and method of manufacturing the same

The present invention relates to a laminated porous polyester film and a method for manufacturing the same, and more particularly, to a laminated porous polyester film having excellent lightness and antistatic properties and printability as well as mechanical strength, heat resistance and numerical stability, and a method of manufacturing the same. It is about.

As the industrial fields and life patterns are diversified, there is a growing interest in the development of a variety of materials that can replace paper, in particular, a polymer resin film having good moldability due to its light weight and excellent mechanical strength.

The polymer resin has various advantages according to the type, and can be produced as a polymer film having the required physical properties through processing methods such as copolymerization and coextrusion.

As the polymer film that is commonly used, polyester films and polyolefin films have been widely used. Among these, polyester has a stable chemical structure and large mechanical strength, and has excellent heat resistance, durability, and chemical resistance, but has a problem in that light weight and buffer resistance are inferior.Polyolefin-based films have good surface properties and light weight, while mechanical and thermal It has the disadvantage of significantly deteriorating characteristics.

In general, when the amount of pores in the film is small, the specific gravity is increased to be heavy, and the buffering property is also decreased. On the other hand, when the amount of pores is increased, the specific gravity is decreased, so the weight is excellent, but the mechanical strength is weakened, which may cause process problems such as breaking during film stretching. There is.

Therefore, it is light and excellent in mechanical strength, and not only has good process stability but also has heat resistance, light blocking property, and beautiful whiteness, so that it can be used for various purposes such as digital camera photo paper, printing decorative paper, interior and exterior wall paper of buildings, etc. The demand for film is growing.

The technical problem to be achieved by the present invention is to provide a laminated porous polyester film having excellent lightness and buffering properties as well as improved process stability.

Another object of the present invention is to provide a method for producing the film.

In order to achieve the above technical problem, the present invention is formed on at least one surface of the porous layer and the porous layer containing a polyolefin-based resin, 0.01-15% by weight relative to the total amount of the polyester-based resin and the polyester-based resin In the laminated porous polyester film comprising a polyester resin layer containing inorganic fine particles, the polyolefin resin is copolymerized from at least one monomer selected from the group consisting of ethylene, propylene, butene, pentene, hexene, octene and methylpentene. The melt index is 1-25 g / min, and the polyester resin is a resin composed of ethylene terephthalate, butylene terephthalate, ethylene naphthalate or butylene naphthalate at least 80% by weight of the repeating unit, and the inorganic fine particles are discretized. Titanium, calcium carbonate, barium sulfate, silica, De, with at least one selected from the group consisting of talc and zeolite, there is provided a multi-layer porous polyester film, it characterized in that the diameter 0.1-10㎛.

In the present invention, the inorganic fine particles are added for the purpose of adjusting optical properties such as light transmittance or color and for controlling friction coefficient, surface roughness and fine touch, the particle size is 0.1-10㎛, the content of the poly It is 0.01-15 weight% with respect to ester resin, Preferably it is 0.5-5 weight%.

When the particle size of the inorganic fine particles is less than 0.1㎛ the effect on the optical properties and surface properties is insignificant, while when the particle size exceeds 10㎛ the surface roughness of the film is excessively increased to give a rough feeling.

In addition, when the amount of the inorganic fine particles added is less than 0.01% by weight, the effect of addition is insignificant, whereas when the amount of the inorganic particles exceeds 15% by weight, the optical or surface properties are inferior to obtain a paper-like texture. Due to the blockage, the pressure increase is accelerated, reducing the life of the filter, reducing the production efficiency, worsening the dispersibility, increasing the breakage, and poor mechanical properties and light weight.

In order to achieve another technical object of the present invention, a polyolefin resin having a melt index of 1-25 g / min as copolymerized from at least one monomer selected from the group consisting of ethylene, propylene, butene, pentene, hexene, octene and methyl pentene is used as a blowing agent. Preparing a first mixed resin with a mixture of 97: 3-90: 10; 80% or more by weight of the repeating unit is a group consisting of titanium dioxide, calcium carbonate, barium sulfate, silica, kaolin, talc and zeolite in a polyester resin composed of ethylene terephthalate, butylene terephthalate, ethylene naphthalate or butylene naphthalate Preparing a second mixed resin by dispersing and mixing an inorganic fine particle having a diameter of 0.1-10 μm with at least one selected from 0.01-15 wt% based on the total amount of the polyester resin; Melting and coextruding the first and second mixed resins to produce an unstretched sheet having a second mixed resin layer formed on at least one surface of the first mixed resin layer; And biaxially stretching the unstretched sheet is provided.

In the manufacturing method of the laminated porous polyester film according to the present invention, in the manufacturing step of the unstretched sheet co-extruded so that the thickness of the second mixed resin layer is 3-20% of the thickness of the first mixed resin layer, If less than 3%, the breaking strength of the final film is lowered, but process stability is poor, while if it is more than 20%, there is a problem that the light weight is poor.

Further, the stretching ratio in the longitudinal and transverse directions in the biaxial stretching step is 2-5 times, preferably 3-4.5 times. If the draw ratio is lower than the above range, the amount of pore formation is insufficient to increase the specific gravity and the mechanical properties are poor, whereas if the draw ratio exceeds the above range, the film may be easily broken, which is not preferable.

Hereinafter, the laminated porous polyester film of the present invention and a manufacturing method thereof will be described in detail.

A polyolefin resin and a blowing agent are mixed in a ratio of 97: 3-90: 10 to prepare a mixed resin, and then melted and coextruded to form bubbles in the film, thereby forming a porous layer. At this time, the polyolefin resin is polymerized from one or more monomers of ethylene, propylene, butene, pentene, hexene, octene and methyl pentene as described above, the melt index is preferably 1-25 g / min, in particular propylene It is still more preferable to polymerize with a main component and other monomers as an auxiliary component. In addition, the blowing agent is foamed through the melting and co-extrusion process to form bubbles in the film, if used in general, can be used without particular limitation, but preferably chlorofluoro such as dichloromethane dichloride Aliphatic hydrocarbons such as carbon, methylene chloride, propane and butane, and azo compounds such as azodicarbonamides may be used alone or in combination.

On the other hand, when the mixing ratio of the polyolefin-based resin and the blowing agent is less than the above range, the formation of pores is generally non-uniform and the content of the total pores is small, so there is no effect on the light weight, whereas if the above range is exceeded, the pores are excessively. There is a problem that the heat resistance, the numerical stability and the mechanical properties are formed and the process stability during coextrusion is inferior.

In addition, the polyester resin is the polyester resin is prepared according to a conventional polyester synthesis method ethylene terephthalate of the repeating unit of the polyester resin is terephthalic acid or dimethyl terephthalate condensation polymerization of ethylene glycol, butylene terephthalate Is condensation polymerization of terephthalic acid or dimethyl terephthalate and tetramethylene glycol, ethylene naphthalate is condensation polymerization of 2,6-naphthalenedicarboxylic acid or dimethyl-2,6-naphthalenedicarboxylate and ethylene glycol, butylenenaphthalate is It is formed by polycondensation of 2,6-naphthalenedicarboxylic acid or dimethyl-2,6-naphthalenedicarboxylate and tetramethylene glycol.

In addition, the polyester resin may include a third copolymerization component in less than 20% by weight of the repeating unit. Monomers that can be used to form the copolymerization component are isophthalic acid, dimethyl-2,5-naphthalenedicarboxylate, 2,5-naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, diphenoxyethanedicar Acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, anthracenedicarboxylic acid or α, β-bis (2-chlorophenoxy) ethane-4,4-dicarboxylic acid, adipic acid Dibasic or polybasic acids such as 5-sodium sulfoisophthalic acid, trimellitic acid and pyromellitic acid, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, hexylene glycol, neopentylene glycol, polyethylene glycol, p-xylene And diols such as glycol, 1,4-cyclohexanedimethanol, and 5-sodium sulfolesosinol.

Further, in the production of polyester resins, tetrakis 3,5-di-t-butylhydroxyphenylpropanoyloxymethylmethane, octadecyl 3,3,5-di-t-butyl-4-hydroxyphenyl One or more selected from propanoate, 2-hydroxy-4-n-octacybenzophenone, 2,4-di-t-butylphenyl, 3,5-di-t-butyl-4-hydroxybenzoate, and the like The hindered phenol compound is added at 0.005-0.5% by weight based on the polyester resin.

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 in the preparation of the polyester resin of the present invention.

In the polyester resin prepared as described above, inorganic particles having a particle size of 0.1-10 μm and one or two or more mixtures selected from titanium dioxide, barium sulfate, calcium carbonate, silica, kaolin, talc and zeolite are polyester-based. 0.01-15% by weight, preferably 0.5-5% by weight of the resin is dispersed and mixed to prepare a resin mixture, which is then melted and coextruded to form a polyester resin layer.

In the present invention, a compounding melting and mixing method is used as a mixing method of the resin to prepare the first mixed resin and the second mixed resin, and then melted and coextruded to at least one surface of the first mixed resin layer. An unstretched sheet having a mixed resin layer was prepared. Subsequently, the non-oriented sheet is biaxially stretched to improve the dispersibility of the resins and to improve the uniformity of the film properties.

In biaxial stretching, it is appropriate to adjust the stretching ratio in the longitudinal and transverse directions to 2-5 times, preferably 3-4.5 times. If the draw ratio is too small, the formation of pores is poor, the specific gravity is increased, the mechanical properties are insufficient, the whiteness is reduced. If the draw ratio is too large, film breakage is frequently caused.

The present invention has a great advantage in that the process stability is improved while increasing the light weight and the buffering property by manufacturing the laminated film by co-extrusion of the porous film layer resin and the general polyester film layer resin into two to three layers.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited to the following Examples. Performance evaluation of the film produced in the following Examples was carried out in the following manner.

(1) film thickness

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

(2) Average particle diameter of inorganic fine particles

The slurry of the inorganic fine particles disperse | distributed to ethylene glycol was measured using the centrifugal particle size analyzer of Shimadzu Corporation, Japan, and is shown as a volume average particle diameter.

(3) apparent density

The density gradient tube consisting of carbon tetrachloride and n-heptane was kept at 25 ° C. and measured by the ups and downs method.

(4) breaking strength

The tensile strength of the film is measured according to ASTM D 882 using UTM 4206 from Instron, USA.

(5) Process stability

It is evaluated as follows by measuring the frequency of breakage of the film for 12 hours during the film forming process and the discharge state and the chip cutting performance under the same process / cooling conditions during the compounding process of the film.

Compounding Fairness:

A: Both discharge / chip cutting are good

B: One of the discharge / chip cutting conditions is bad

C: Bad discharge / chip cutting

Production Process Fairness:

A: One break occurs, B: 2-3 breaks occured, C: Four or more breaks occur

(6) heat shrinkage rate

The total shrinkage length over 30 minutes at 150 ° C. is determined.

<Example 1>

A first mixed resin was prepared by compounding a melt polypropylene resin having a melt index of 4.0 and azodicarbonamide in a ratio of 95: 5, respectively.

Dimethyl terephthalate and ethylene glycol were mixed in a 1: 2 equivalent ratio, and then a transesterification catalyst was added to the mixture to form bis-2-hydroxyethyl terephthalate as a monomer of polyethylene terephthalate. To this, 0.05 parts by weight of tetrakis-3,5-di-t-butylhydroxyphenylpropanoyloxymethylmethane and an ordinary polycondensation catalyst were added, and the polycondensation was completed to obtain a polyethylene tere having an intrinsic viscosity of 0.610 dl / gr. Phthalate was obtained. A second mixed resin was prepared by mixing titanium dioxide having a cubic crystal structure having an average particle diameter of 0.5 μm with the polyethylene terephthalate by 5 wt% based on the total amount of polyethylene terephthalate.

The two resins were dried according to the polyester film production method, and then the two resins were used in a conventional polyester film production method by using an extruder and a feed die fitted with a feed block adjusted to have a thickness ratio of two layers of 97: 3. And melted and extruded to form a sheet, and then stretched four times in each of the longitudinal draw ratio and the transverse draw ratio to prepare a biaxially stretched film having a thickness of 50 μm. The physical properties of the film were evaluated according to the method as described above for this film, and the results are shown in Table 1 below.

<Example 2>

Example 1, except that the polyethylene naphthalate resin having an extreme viscosity of 0.59 dl / gr prepared using dimethyl-2,5-naphthalenedicarboxylate instead of dimethyl terephthalate as a dicarboxylic acid component, After the film was produced in the same manner, the physical properties thereof were evaluated and the results are shown in Table 1.

<Examples 3 to 5>

Except for changing the thickness ratio of the Ti die as shown in Table 1, after the film was prepared in the same manner as in Example 1, the physical properties were evaluated and the results are shown in Table 1.

<Example 6>

Example 1, except that a porous film resin in the intermediate layer and a general polyester resin on both sides of the interlayer, using a die-die equipped with an extruder and a feed block adjusted to a thickness ratio of 3: 94: 3. After the film was produced in the same manner, the physical properties thereof were evaluated and the results are shown in Table 1.

<7 to 9 Examples>

Except for changing the thickness ratio of the Ti die as shown in Table 1 after the film was prepared in the same manner as in Example 6, the physical properties were evaluated and the results are shown in Table 1.

Polyester film Porous film Laminated Porous Polyester Film Fairness Final Film Properties Polyester Inorganic particulates thickness Polyolefin thickness Compounding Production density Heat shrinkage Breaking strength Example Kinds Kinds Parts by weight Μm Kinds Μm - - g / cm ³ % kg / ㎠ One 2 floor type PET TiO ₂ 5 3 PP 97 A A 0.680 0.1 1500 2 PEN TiO ₂ 5 3 PP 97 A A 0.700 0.1 1690 3 PET TiO ₂ 5 10 PP 90 A A 0.715 0.1 1890 4 PET TiO ₂ 5 15 PP 85 A A 0.722 0 2000 5 PET TiO ₂ 5 20 PP 80 A A 0.780 0 2100 6 3-layer type PET TiO ₂ 5 6 PP 94 A A 0.690 0 1850 7 PET TiO ₂ 5 10 PP 90 A A 0.720 0 1900 8 PET TiO ₂ 5 15 PP 85 A A 0.746 0 2100 9 PET TiO ₂ 5 20 PP 80 A A 0.760 0 2250

In Table 1, the blowing agent used 5% by weight of azodicarbonamide based on the total weight of the porous film.

As can be seen from the above, the laminated porous polyester film according to the present invention having a porous film layer and a general polyester film layer is excellent in processability and physical properties of the final film as a substitute for paper, calendars, flyers, high-quality packaging, printing It can be used in various fields such as decorative paper and wallpaper.

Claims (4)

A porous layer containing a polyolefin resin and a polyester resin layer formed on at least one surface of the porous layer and containing 0.01-15% by weight of inorganic fine particles relative to the total amount of the polyester resin and the polyester resin. In the laminated porous polyester film, The polyolefin resin is copolymerized from one or more monomers selected from the group consisting of ethylene, propylene, butene, pentene, hexene, octene and methylpentene and has a melt index of 1-25 g / min, 80% by weight or more of the polyester-based resin is a resin consisting of ethylene terephthalate, butylene terephthalate, ethylene naphthalate or butylene naphthalate, The inorganic fine particles are laminated porous polyester film, characterized in that the diameter of 0.1-10㎛ at least one selected from the group consisting of titanium dioxide, calcium carbonate, barium sulfate, silica, kaolin, talc and zeolite. The laminated porous polyester film according to claim 1, wherein the polyester resin layer has a thickness of 3-20% of the thickness of the porous layer. A polyolefin resin having a melt index of 1-25 g / min, copolymerized from at least one monomer selected from the group consisting of ethylene, propylene, butene, pentene, hexene, octene and methylpentene, with a blowing agent of 97: 3-90: 10. Mixing to prepare a first mixed resin; 80% or more by weight of the repeating unit is a group consisting of titanium dioxide, calcium carbonate, barium sulfate, silica, kaolin, talc and zeolite in a polyester resin composed of ethylene terephthalate, butylene terephthalate, ethylene naphthalate or butylene naphthalate Preparing a second mixed resin by dispersing and mixing an inorganic fine particle having a diameter of 0.1-10 μm with at least one selected from 0.01-15 wt% based on the total amount of the polyester resin; Melting and coextruding the first and second mixed resins to produce an unstretched sheet having a second mixed resin layer formed on at least one surface of the first mixed resin layer; And A method of manufacturing a laminated porous polyester film comprising the step of biaxially stretching the unstretched sheet. 4. The laminated porous polyester film of claim 3, wherein the second mixed resin layer is coextruded to have a thickness of 3-20% of the thickness of the first mixed resin layer in the step of manufacturing the unstretched sheet. Manufacturing method.