KR100426255B1 - Biaxially stretching polyester laminated white film - Google Patents

Abstract

The biaxially stretched polyester laminated white film according to the present invention is not only excellent in surface characteristics as a graphic application, but also aimed at multifunctionality and high functionality so that it can be used in various product applications such as electric and electronic materials.

The biaxially stretched polyester laminated white film of the present invention comprises: a gloss layer (A layer) for forming a surface layer at 60% glossiness of the surface of 100% or more; An opaque layer (B layer) containing 5 to 30% by weight of inorganic particles and 0.5% by weight or less of an optical brightener to form an intermediate layer in polyester; And it is characterized by consisting of a three-layer laminated structure of the matte layer (C layer) to form a back layer with a 60 degree glossiness of the surface of 50% or less. The gloss layer (A layer) and the matte layer (C layer) are made by adding a predetermined amount of silica particles to the polyester. Accordingly, the above-described object can be achieved by improving the surface glossiness and by providing better functions such as different surface characteristics on the front and back surfaces.

Description

Biaxially Stretched Polyester Laminated White Film {BIAXIALLY STRETCHING POLYESTER LAMINATED WHITE FILM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to biaxially stretched polyester laminated white films, and in particular, biaxially stretched polyesters having high whiteness and excellent hiding power and having different surface properties on the front and back surfaces can be widely applied to printing, imaging, advertising, and exhibition applications. It relates to a laminated white film.

Polyesters, primarily polyethylene terephthalates, are widely used in polymer processing because of their excellent physical and chemical properties. For example, polyester white films have been widely developed as substitutes for labels, cards, white plates, photo papers, image papers, and the like. As a method of manufacturing such a white film, a method of making a white film by filling an appropriate amount of inorganic particles into a polymer matrix is widely known. In this case, the inorganic material used as the inorganic particles is typically titanium dioxide, calcium carbonate, barium sulfate and the like.

As examples of white films prepared by filling such an inorganic material into a polyester polymer matrix, British Patent Nos. 1,563,591, 1,563,592 and Japanese Patent Publication No. 1985-30930 include filling barium sulfate with polyester or sulfuric acid. Disclosed is a white film made by simultaneously filling barium and polyolefin with polyester. In addition, Japanese Unexamined Patent Publications 1968-12013, 1987-207337, 1988-137927 and 1988-161029 disclose polyester white films containing calcium carbonate. In addition, Japanese Unexamined Patent Publications 1969-26752 and 1986-118746 disclose polyester white films containing titanium dioxide. In addition, Japanese Laid-Open Patent Publication 1988-193934 discloses a biaxially stretched polyester film in which titanium dioxide containing a zinc compound is blended. In addition, Japanese Laid-Open Patent Publication No. 1988-196632 discloses a biaxially stretched polyester film containing titanium dioxide, silica and an aluminum compound. In addition, Japanese Patent Laid-Open No. 1990-185532 discloses a polyester white film containing particles in which polyolefin is coated on inorganic particles. In addition, Japanese Patent Laid-Open No. 1991-24191 discloses a polyester white film containing calcium carbonate, barium sulfate and strontium. In addition, US Patent No. 5,403,879 discloses a white film imparting antistatic properties, and Korean Patent Publication No. 1998-55562 discloses a white film imparting flame retardant properties.

However, all of the white films as described above are monolayer films, which have limitations in providing better functions and characteristics. In order to overcome this, recently, a laminated white film using a coextrusion technique has been proposed. For example, Japanese Patent Application Laid-Open No. Hei 8-252857 discloses a method for producing a polyester laminated white film in which a polyolefin resin is added to polyester, and Japanese Patent Laid-Open No. 9-52335 discloses a zinc compound, an aluminum compound, and an anatase type titanium dioxide. An added coextrusion biaxially stretched polyester laminated film is disclosed. In addition, Japanese Laid-Open Patent Publication No. 9-85918 discloses a polyester-laminated white film characterized by adding anatase type titanium dioxide and rutile type titanium dioxide. In addition, Japanese Laid-Open Patent Publication No. Hei 9-187904 discloses a polyester laminated white film characterized by having an intrinsic viscosity difference of 0.001 to 0.20. In addition, Japanese Laid-Open Patent Publication No. 11-123801 discloses a polyester-laminated white film, characterized in that the transmittance concentration is 0.2 or more, the color b value is less than 2, and the 60 degree glossiness of the surface is 60% or more. Further, Japanese Laid-Open Patent Publication No. 11-157038 discloses a polyester laminated white film containing titanium oxide particles, barium sulfate particles, and a fluorescent brightener. Japanese Laid-Open Patent Publication No. 11-170462 also discloses a polyester-laminated white film containing titanium oxide particles, barium sulfate particles, and a fluorescent brightener, and having an apparent density of 0.5 to 1.3 g / cm 3. In addition, Japanese Laid-Open Patent Publication No. 11-254622 discloses a polyester-laminated white film characterized by containing an anatase type titanium dioxide and a white pigment having a atomic concentration of 50 ppm or less. In addition, US Patent No. 6,143,408 discloses a polyester laminated white film having a transmission concentration of 0.2 or more, a color b value of less than 2, and a primer layer.

In order to use these laminated white films for graphic purposes such as printing, imaging, advertising, and exhibition, the surface characteristics are an important requirement because the color and gloss of the surface show a lot of difference in product preference and quality. Surface characteristics are completed by artificially controlling the surface roughness of the substrate. In addition, the glossiness of the product as the surface characteristics is different depending on the physical properties of the film and the surface design of the substrate, the glossiness of the substrate not only affects the post-process such as printing, but also affects the quality of the product.

Accordingly, an object of the present invention is to provide a multifunctional and highly functionalized biaxially stretched polyester laminated white film which can be used not only for excellent surface characteristics as graphic applications but also for various product applications such as electric and electronic materials.

1 is a partial cross-sectional view showing a laminated structure of a biaxially stretched polyester laminated white film according to the present invention.

Biaxially stretched polyester laminated white film according to the present invention, as shown in Figure 1, the gloss layer (layer A) to form a surface layer with a gloss of 60 degrees or more of the surface of 100 degrees; An opaque layer (B layer) containing 5 to 30% by weight of inorganic particles and 0.5% by weight or less of an optical brightener to form an intermediate layer in polyester; And it consists of a 3-layer laminated structure of the matte layer (C layer) which forms a back surface layer with 60 degree glossiness of 50% or less of the surface.

The biaxially stretched polyester laminated white film according to the present invention can be produced by incorporating coextrusion technology based on a polyester single layer white film processing technology. White film processing technology requires a high level of processing technology in addition to the general polyester film manufacturing technology. In particular, in recent years, wide polyester production line has been generalized in order to manufacture a polyester white film filled with a large amount of inorganic particles, process technology development should be preceded.

Points considered in the preparation of the biaxially stretched polyester laminated white film according to the present invention are as follows.

That is, in the present invention, titanium dioxide is filled into the polyester as the inorganic particles. Since a large amount of the charged titanium dioxide lowers the intrinsic viscosity of the polyester matrix, the intrinsic viscosity of the polyester matrix must be maintained at an appropriate level. If the viscosity is too low, there is a high possibility of breakage during film production. In addition, since the inorganic particles containing a large amount act as a nucleating agent of the polymer melt during the casting process, crystallization control technology is required. In addition, these particles limit the stretchability of the matrix and therefore require a stretching mechanism different from conventional polyester films.

Therefore, the average particle size of titanium dioxide used in the production of the biaxially stretched polyester laminated white film according to the present invention is 0.05 to 5 탆, preferably 0.1 to 0.5 탆. If the particle size is less than 0.05 μm, the particle agglomeration is lowered due to particle aggregation. If the particle size is more than 5 μm, the interaction force between the particles and the particles and between the particles and the matrix is weakened. It may cause instability.

On the other hand, the amount of titanium dioxide to polyester is 5 to 30% by weight, preferably 10 to 20% by weight. If the filling amount is less than 5% by weight, the whiteness is low and the hiding power does not reach the optimum requirement. If the filling amount is more than 30% by weight, for example, the swelling phenomenon of the melt is decreased, and the sagging of the melt is increased. The flow characteristics of the polymer are changed, and the stretchability is lowered, which causes difficulty in the film forming process.

Fluorescent whitening agent filled in polyester with titanium dioxide is bisbenzoxazole-based, preferably 2,2 '-(1,2-ethenediyldi-4,1-phenyline) bisbenzazole, and the addition amount is 0.005 0.5 weight%, Preferably it is 0.05-0.2 weight%. When the addition amount of the fluorescent brightener is less than 0.005% by weight, the whitening effect is insignificant, and when the addition amount is more than 0.5% by weight, the whiteness decreases due to excessive reflectance.

In order to control the surface properties of the film, the present invention obtains the required glossiness by inputting the film surface roughness using a coextrusion technique and an inorganic particle design technique. The problems associated with extrusion instability such as two and three layers and different substrates of the present invention having different material rheological properties can be solved by understanding the respective material flow mechanisms. To this end, in the gloss layer (A layer) and the matte layer (C layer), silicon dioxide is added to the polyester, and the average particle size of the silicon dioxide used is 1 to 10 µm, preferably 2 to 5 µm. . The addition amount of silicon dioxide is 0.1 to 5 weight%, Preferably it is 0.5 to 1 weight%. Even if the addition amount of silicon dioxide is large, if the average particle size is less than 1 µm or if the addition amount is less than 0.1% by weight, sufficient matting and printability are obtained. On the contrary, when a relatively large particle | grain exceeding 10 micrometers contains a large amount exceeding 5 weight%, film forming property is inferior.

In the present invention, 60 degree glossiness was measured by the method of ASTM D 523 as main physical properties.

Example 1

Polyethylene terephthalate having an intrinsic viscosity of 0.65 dl / g without particles is called raw material PM1, and polyethylene terephthalate containing 50 wt% of titanium dioxide having an average particle size of 0.3 μm and 0.15 wt% of a fluorescent brightener (OB-1). Is called raw material PM2, and polyethylene terephthalate containing 5 wt% of silicon dioxide having an average particle size of 4 μm is called raw material PM3, and polyethylene terephthalate containing 5 wt% of silicon dioxide having an average particle size of 2 μm is called raw material PM4. do.

Sheets were prepared by drying the raw materials PM1 to PM4 in weight percent at the ratios shown in Table 1, followed by lamination into three layers in the feed block and extrusion through a coextrusion die and cooling in a casting drum.

This sheet was stretched 3.0 times in the longitudinal direction at a temperature in the range of 75 to 130 ° C., then stretched 3.3 times in the transverse direction at a temperature in the range of 90 to 145 ° C., and heat-treated in the temperature range of 215 to 235 ° C. to an average thickness of 50 μm. Films were obtained in turn.

The thickness of A layer, B layer, and C layer which comprise each film manufactured by applying raw material PM1-PM4 in order was 3 micrometers, 44 micrometers, and 3 micrometers in order.

TABLE 1

division layer Layer thickness (㎛) Content (% by weight) Remarks PM1 PM2 PM3 PM4 Example 1 A 3 90 0 0 10 Lamination B 44 70 30 0 0 C 3 55 0 45 0 Example 2 A 5 90 0 0 10 Lamination B 40 70 30 0 0 C 5 55 0 45 0 Example 3 A 3 90 0 0 10 Lamination B 44 70 30 0 0 C 3 35 0 65 0 Example 4 A 5 90 0 0 10 Lamination B 40 70 30 0 0 C 5 35 0 65 0 Comparative Example 1 - 50 70 30 0 0 fault Comparative Example 2 - 50 0 30 10 0 fault

Example 2

By applying the weight% raw materials PM1 to PM4 shown in Table 1 in the same manner as in Example 1 to obtain a film having an average thickness of 50㎛. The thickness of A layer, B layer, and C layer which comprise each film manufactured by applying the raw materials PM1-PM4 in order was 5 micrometers, 40 micrometers, and 5 micrometers in order.

Example 3

By applying the weight% raw materials PM1 to PM4 shown in Table 1 in the same manner as in Example 1 to obtain a film having an average thickness of 50㎛. The thickness of A layer, B layer, and C layer which comprise each film manufactured by applying raw material PM1-PM4 in order was 3 micrometers, 44 micrometers, and 3 micrometers in order.

Example 4

By applying the weight% raw materials PM1 to PM4 shown in Table 1 in the same manner as in Example 1 to obtain a film having an average thickness of 50㎛. The thickness of A layer, B layer, and C layer which comprise each film manufactured by applying the raw materials PM1-PM4 in order was 5 micrometers, 40 micrometers, and 5 micrometers in order.

Comparative Example 1

Polyethylene terephthalate having an intrinsic viscosity of 0.65 dl / g without particles was called raw material PM1, and polyethylene terephthalate containing 50 wt% of titanium dioxide having an average particle size of 0.3 μm and 0.15 wt% of an optical brightener (OB-1). Is called the raw material PM2.

Sheets were prepared by drying the raw materials PM1 and PM2 in weight percent in the ratios shown in Table 1 below, followed by extrusion into a single layer and cooling in a casting drum.

The sheet was stretched 3.0 times in the longitudinal direction at a temperature in the range of 75 to 130 ° C., then stretched 3.3 times in the transverse direction at a temperature in the range of 90 to 145 ° C., and heat-treated in the temperature range of 215 to 235 ° C. to obtain a thickness of 50 μm. The films were obtained in turn.

Comparative Example 2

A film having a thickness of 50 μm was obtained in the same manner as in Example 1 by applying the wt% raw materials PM1 and PM2 shown in Table 1.

The particle types, particle amounts and glossiness of the films according to the present invention of Examples 1 to 4 obtained as described above and the films of Comparative Examples 1 and 2 are shown in Table 2 below. .

TABLE 2

division layer Layer thickness (㎛) Titanium dioxide content (% by weight) 4 μm silica content (% by weight) 2 μm silica content (% by weight) Glossiness (%) Example 1 A 3 0 0 0.1 141 B 44 15 0 0 C 3 0 2.25 0 39 Example 2 A 5 0 0 0.1 138 B 40 15 0 0 C 5 0 2.25 0 28 Example 3 A 3 0 0 0.1 143 B 44 15 0 0 C 3 0 3.25 0 24 Example 4 A 5 0 0 0.1 135 B 40 15 0 0 C 5 0 3.25 0 18 Comparative Example 1 - - 15 0 0 75 Comparative Example 2 - - 15 0.5 0 45

As can be seen from Table 1, even if the same amount of titanium dioxide is added, the film of the present invention obtained by Examples 1 to 4, the surface glossiness is remarkable as compared to the film obtained by Comparative Examples Has been improved.

In addition, in the biaxially stretched polyester laminated white film according to the present invention, an opaque layer (B layer), which is the middle layer among the three layers, is made by adding inorganic particles and a fluorescent brightener to polyester, and the opaque layer (B layer) The surface and It was found that different surface properties were given to the back surface.

In the biaxially stretched polyester-laminated white film according to the present invention configured as described above, the surface glossiness is improved, and better functions such as different surface properties are provided on the front and back surfaces, so that printing, imaging, Not only can be used as a highly functional material for advertising and exhibition purposes, but also can be used for various product applications such as electric and electronic materials. Therefore, the quality of the material and the general purpose can be achieved.

Claims (5)

A gloss layer (A layer) which forms a surface layer with a 60 degree glossiness of the surface of 100% or more; An opaque layer (B layer) containing 5 to 30% by weight of inorganic particles and 0.5% by weight or less of an optical brightener to form an intermediate layer in polyester; And, biaxially stretched polyester laminated white film, characterized in that consisting of a three-layer laminated structure of the matte layer (C layer) to form a back layer with a 60 degree glossiness of the surface of 50% or less. The method of claim 1, The average particle size of the inorganic particles is biaxially stretched polyester laminated white film, characterized in that 0.1 to 10㎛. The method according to claim 1 or 2, The inorganic particles are biaxially stretched polyester laminated white film, characterized in that at least one selected from the group consisting of titanium dioxide and barium sulfate. The method of claim 1, The gloss layer (A layer) is a biaxially stretched polyester laminated white film, characterized in that the silica particles having an average particle size of 0.05 to 5㎛ added to the polyester 0.5% by weight or less. The method of claim 1, The matte layer (C layer) is a biaxially stretched polyester laminated white film, characterized in that the addition of 0.5 to 10% by weight of silica particles having an average particle size of 0.5 to 20㎛ to the polyester.