Laminate film using polylactic acid-based resin

Abstract

Our invention is a laminate film comprising a water-soluble resin layer and a polylactic acid-based resin layer laminated on at least one side of a substrate film, the water-soluble resin layer has a thickness of 0.1 to 15 m, the polylactic acid-based resin layer has a thickness of 10 to 500 nm. Such a configuration provides a laminate film of which the water-soluble resin layer and the polylactic acid-based resin layer are easily separated from the substrate film and which is excellent in coating ability, adherence and followability to a soft and curved adherend, as well as compatibility to skin and organs such as viscera, so as to be suitable for wound dressing, adhesion prevention material and a skin external agent such as skin-care product.

Claims

1. A laminate film comprising a water-soluble resin layer and a polylactic acid-based resin layer laminated on a polyester or polyolefin substrate film surface, wherein the water-soluble resin layer has a thickness of 0.1 to 15 m, the polylactic acid-based resin layer has a thickness of 10 to 500 nm, and the substrate film surface has a center-line average surface roughness (SRa) of 3 to 50 nm and a ten-point average surface roughness (SRz) of 50 to 1000 nm.

2. The laminate film according to claim 1, wherein the water-soluble resin layer contains a polyvinyl alcohol.

3. The laminated film according to claim 2, wherein the polyvinyl alcohol has a saponification degree of 85 to 98.5 mol %.

4. The laminate film according to claim 1, wherein the polylactic acid-based resin layer contains a polylactic acid-based resin including a poly-D-lactic acid of 4 to 13 mol %.

5. The laminate film according to claim 1, wherein the water-soluble resin layer contains a pullulan.

Description

EXAMPLES

(1) <Evaluation Method of Characteristics>

(2) The characteristics are evaluated as follows.

(3) (1) Thickness

(4) The water-soluble resin layer and polylactic acid-based resin layer are laminated to have a height difference on the substrate film to be observed with a confocal laser microscope (VK-9710 made by Keyence Corp.). Then, the membrane thickness is calculated from the height difference. The confocal laser microscope is a measuring device having the following mechanism. Laser beam emitted from the opening of the light source focuses to a sample by an object lens to get fluorescence emitted from the sample. The fluorescence and the laser reflected light are mixed and condensed again by an object lens. The mixed light is separated by a beam splitter to let the laser reflected light pass through so that only the fluorescence is introduced into the sensing device. The fluorescence that has passed through a pinhole is sensed by a light sensing device (photomultiplier tube or avalanche photodiode) so that the light signal is converted into electrical signal to be recorded to a computer. The laser scans a sample at regular intervals to obtain an overall image.

(5) (2) Peeling Ability of Polylactic Acid-Based Resin Layer

(6) The laminate film provided on the substrate film with the water-soluble resin layer and polylactic acid-based resin layer is evaluated into five grades of production easiness of the polylactic acid-based resin film comprising the polylactic acid-based resin layer.

(7) Evaluation Grade 5 (Easily Peeled):

(8) A layer consisting of the water-soluble resin layer and polylactic acid-based resin layer is easily peeled by hand from the substrate film, and then the water-soluble resin layer is dissolved in water (at 23 C.) to obtain a polylactic acid-based resin film.

(9) Evaluation Grade 4 (Peelable):

(10) Evaluation grade 5 is not reached but a layer consisting of the water-soluble resin layer and polylactic acid-based resin layer is easily peeled by hand from the substrate film, and then the water-soluble resin layer is dissolved in water (at 37 C.) to obtain a polylactic acid-based resin film.

(11) Evaluation Grade 3 (Hardly Peeled):

(12) Evaluation grades 5 and 4 are not reached but the laminate film provided with the water-soluble resin layer and polylactic acid-based resin layer on the substrate film is immersed in water (at 23 C.) and then the water-soluble resin layer is dissolved therein and peeled to obtain a polylactic acid-based resin film.

(13) Evaluation Grade 2 (Scarcely Peeled):

(14) Evaluation grades 5, 4 and 3 are not reached but the laminate film provided with the water-soluble resin layer and polylactic acid-based resin layer on the substrate film is immersed in water (at 37 C.) and then the water-soluble resin layer is dissolved therein and peeled to obtain a polylactic acid-based resin film.

(15) Evaluation Grade 1 (not Peeled):

(16) Evaluation grades 5, 4, 3 and 2 are not reached but the laminate film provided with the water-soluble resin layer and polylactic acid-based resin layer on the substrate film is immersed in water and then the water-soluble resin layer is dissolved therein, although the polylactic-acid-based resin layer does not keep a continuous film shape.

(17) (3) Adherence 1

(18) Laminate films evaluated as grades 4 and 5 in the above-described (2) Peeling ability of polylactic acid-based resin layer are cut into size of 1 cm1 cm (1 cm.sup.2). The layers consisting of the water-soluble resin layer and polylactic acid-based resin layer are peeled from the substrate film. The polylactic acid-based resin layer sides are placed on the skin of 12 healthy volunteers whose back of hands are sprayed to be wet with water (37 C.). The layers with the water-soluble resin layer are further sprayed with water (37 C.) to remove the water-soluble resin layer, and then naturally dried for 1 hour.

(19) Further, laminate films evaluated as grades 2 and 3 in the above-described (2) Peeling ability of polylactic acid-based resin layer are cut into size of 1 cm1 cm (1 cm.sup.2). The layers are immersed in water (37 C.) to remove the water-soluble resin layer to obtain the polylactic acid-resin films, which are placed on 12 healthy volunteers' back of hands and naturally dried for 1 hour.

(20) The dried polylactic acid-based resin layers are visually observed to grade the layers. A layer with no rupture, lift and peeling is graded as 5: Very good. A layer with one of rupture, lift and peeling is graded as 4: Good. A layer with two or more of rupture, lift and peeling is graded as 3: Slightly bad. A layer with all of rupture, lift and peeling is graded as 2: Bad. A layer unable to adhere is graded as 1: Very bad. Such grades are averaged among the 12 healthy volunteers to calculate the average score rounded to the closest whole number.

(21) (4) Adherence 2

(22) The polylactic acid-based resin film prepared by the methods of the grades 2 to 5 in the above-described (2) Peeling ability of polylactic acid-based resin layer are cut into discs of 900 mm.sup.2 area and immersed with water (10-15 C.) in a petri dish. Then, at temperature of 235 C. and relative humidity of 6520%, the polylactic acid-based film is taken from the water bath to be placed within 30 sec and naturally dried for more than 1 hour in the center part of a commercially available polyurethane resin skin model (BIOSKIN plate made by Beaulax: skin model No. 10C (woman in her 20's): disc shape having diameter 50 mmthickness 5 mm: hardness level 2: mixing ratio 0.25: black). The hardness level of the skin model is measured under the following condition.

(23) 1: Durometer (GS-721N made by TECLOCK Corporation: E type)

(24) 2: Constant pressure weighter (GS-710 made by TECLOCK Corporation)

(25) 3: Method for measurement (JIS K 6253E)

(26) 4: Measurement time (15 sec)

(27) The dried polylactic acid-based resin films are visually observed to grade the films. A film adhering with area of 750 mm.sup.2 or more and less than 900 mm.sup.2 is graded as 5: Very good. A film adhering with area of 500 mm.sup.2 or more and less than 750 mm.sup.2 is graded as 4: Good. A film adhering with area of 250 mm.sup.2 or more and less than 500 mm.sup.2 is graded as 3: Slightly bad. A film adhering with area of 100 mm.sup.2 or more and less than 250 mm.sup.2 is graded as 2: Bad. A film adhering with area of less than 100 mm.sup.2 is graded as 1: Very bad. Such grades are averaged among 10 times of measurement to calculate the average score rounded to the closest whole number.

(28) (5) Center-Line Average Surface Roughness on Substrate Film; SRa Level: Ten-Point Average Surface Roughness; SRz Level

(29) Three-dimensional surface roughness on substrate film (SRa and SRz) is measured with a three-dimensional contact probe profilometer ET-30HK (made by Kosaka Laboratory Ltd.). The side to laminate the polylactic acid-based resin layer or water-soluble resin layer is subject to the measurement.

(30) Probe curvature radius: 2 m

(31) Measured length: 1 mm

(32) Feeding pitch: 5 m

(33) Measurement times: 81 times

(34) Cutoff level: 0.25 mm

(35) Contact probe load: 10 mg

(36) Speed: 100 m/s

(37) (6) Adhesion to Substrate Film

(38) The laminate film is sampled into size of 15 mm in transverse direction (TD) and 10 cm in machine direction (MD). The peeling strength of the substrate film to the polylactic acid-based resin layer or the water-soluble resin layer laminated on the substrate film is measured with a tensile tester (Autograph AG-1S made by Shimadzu Corporation). Before sampling, the film to be measured is pasted on the side opposite to contact side of the substrate film with a cellophane tape (CELLOTAPE (registered trademark) made by Nichiban Co., Ltd.; CT-18; substrate: cellophane, adhesive: rubber). The peeling test is performed at peeling speed of 200 m/min and peeling angle of 180 degrees as being contacted on the CELLOTAPE side. The MD means a rewind direction in which the substrate film is manufactured as rolled while the TD means a direction orthogonal to the MD. The sampling and the measurement are performed in a room at 275 C. and humidity of 655% RH.

(39) Less than 510.sup.3 [N/10 mm] 0

(40) 510.sup.3 or more and less than 10010.sup.3 [N/10 mm] 5

(41) 10010.sup.3 or more and less than 30010.sup.3 [N/10 mm] 4

(42) 30010.sup.3 or more and less than 1,00010.sup.3 [N/10 mm] 3

(43) 1,00010.sup.3 or more and less than 2,00010.sup.3 [N/10 mm] 2

(44) 2,00010.sup.3 or more and less than 5,00010.sup.3 [N/10 mm] 1

(45) 5,00010.sup.3 or more [N/10 mm] 0

(46) The above-described scores are averaged (to be rounded off to the closest whole number) among 10 times of tests.

(47) (7) Pinhole

(48) The polylactic acid-based resin film prepared by the methods of the grades 2 to 5 in the above-described (2) Peeling ability of polylactic acid-based resin layer are cut into discs of 900 mm.sup.2 area and immersed with water (10-15 C.) in a petri dish. Then, at temperature of 235 C. and relative humidity of 6520%, the polylactic acid-based film is taken from the water bath to be placed within 30 sec and naturally dried for more than 1 hour in the center part of a commercially available polyurethane resin skin model (BIOSKIN plate made by Beaulax: skin model No. 10C (woman in her 20's): disc shape having diameter 50 mmthickness 5 mm: hardness level 2: mixing ratio 0.25: white). A red soakage (AGELESS seal check made by Mitsubishi Gas Chemical Company, Inc.) containing azo-based oil-soluble dye is applied with a soaked cotton swab to the surface of the polylactic acid-based resin film. It is left for 3 min and then the red soakage remained on the surface is removed with a cotton swab. The bleeding stains on the skin model are visually observed and counted as a pinhole number.

(49) Less than five pinholes: 5

(50) 5 or more and less than 10 pinholes: 4

(51) 10 or more and less than 15 pinholes: 3

(52) 15 or more and less than 20 pinholes: 2

(53) 20 or more pinholes: 1

(54) The above-described scores are averaged (rounded off to the closest whole number) among 10 times of tests.

(55) [Substrate Film]

(56) (PET-1)

(57) Biaxially oriented polyester film (Lumirror (registered trademark) made by Toray Industries, Inc.; type: S10; thickness: 100 m).

(58) (PET-2)

(59) Biaxially oriented polyester film (Lumirror (registered trademark) made by Toray Industries, Inc.; type: T60; thickness: 100 m).

(60) (PET-3)

(61) Biaxially oriented polyester film (Lumirror (registered trademark) made by Toray Industries, Inc.; type: X10S; thickness: 50 m).

(62) [Polylactic Acid-Based Resin]

(63) (PLA-1)

(64) Poly-D-lactic acid of 12 mol %; melting point of 150 C.; poly-L-lactic acid-based resin (4060D made by NatureWorks LLC) of weight average molecular weight of 220,000 in terms of PMMA.

(65) (PLA-2)

(66) Poly-D-lactic acid of 4.8 mol %; melting point of 150 C.; poly-L-lactic acid-based resin (4042D made by NatureWorks LLC) of weight average molecular weight of 220,000 in terms of PMMA.

(67) (PLA-3)

(68) Poly-D-lactic acid of 1.4 mol %; melting point of 150 C.; poly-L-lactic acid-based resin (4032D made by NatureWorks LLC) of weight average molecular weight of 220,000 in terms of PMMA.

(69) [Water-Soluble Resin]

(70) (PVA-1)

(71) Polyvinyl alcohol (GOHSENOL EG-05P made by Nippon Synthetic Chemical Industry Co., Ltd.) of saponification degree 88 mol %; viscosity 5 mPa.Math.s (4 mass % water solution; 20 C.).

(72) (PVA-2)

(73) Polyvinyl alcohol (functional polymer KM-118 made by Kuraray Co., Ltd.) of saponification degree 97 mol %; viscosity 30 mPa.Math.s (4 mass % water solution, 20 C.).

(74) (PVA-3)

(75) Polyvinyl alcohol (GOHSENOL N-11 made by Nippon Synthetic Chemical Industry Co., Ltd.) of saponification degree 99 mol %; viscosity 15 mPa.Math.s (4 mass % water solution; 20 C.).

(76) (Pullulan-1)

(77) Pullulan (pullulan PI-20 made by Hayashibara Co., Ltd.) of weight average molecular weight 26359 kilo Daltons, polymerization degree (=weight average molecular weight/number average molecular weight) 23.8; viscosity 100-180 mm.sup.2/s (temperature 30 C.; 10 mass % water solution of solid content concentration).

Example 1

(78) Water-soluble resin PVA-1 was dissolved in water with a heating-type homogenizer and mixed with isopropyl alcohol by 20 mass % to prepare a water-soluble resin emulsion liquid, which was applied to a side of substrate film PET-1 by the applicator method to have dry membrane thickness of 15 m and dried for 10 sec in a hot wind dryer at 90 C. to prepare a laminate film. Further, a solution in which polylactic acid-based resin PLA-1 was dissolved in ethyl acetate was applied to it with a metaling bar to have dry membrane thickness of 10 nm, and was dried for 5 sec in a hot-wind dryer at 70 C. to prepare a laminate film provided with a polylactic acid-based resin layer. Characteristics of thus obtained laminate film are shown in Table 1. As shown in Table 1, the laminate film had a polylactic acid-based resin layer having 5th grade of peeling ability and 5th grade of adherence.

Example 2

(79) A laminate film was prepared by the same method as Example 1, except that the polylactic acid-based resin layer had thickness of 50 nm. Characteristics of thus obtained laminate film are shown in Table 1.

Example 3

(80) A laminate film was prepared by the same method as Example 1, except that the polylactic acid-based resin layer had thickness of 500 nm. Characteristics of thus obtained laminate film are shown in Table 1.

Example 4

(81) A laminate film was prepared by the same method as Example 1, except that the water-soluble resin layer had thickness of 0.1 m. Characteristics of thus obtained laminate film are shown in Table 1.

Example 5

(82) A laminate film was prepared by the same method as Example 1, except that the water-soluble resin layer had thickness of 0.1 m and the polylactic acid-based resin layer had thickness of 500 nm. Characteristics of thus obtained laminate film are shown in Table 1.

Example 6

(83) A laminate film was prepared by the same method as Example 1, except that substrate film/polylactic acid-based resin layer/water-soluble resin layer were laminated in this order. Characteristics of thus obtained laminate film are shown in Table 1.

Example 7

(84) A laminate film was prepared by the same method as Example 1, except that the water-soluble resin was PVA-2 while the polylactic acid-based resin layer had thickness of 100 nm. Characteristics of thus obtained laminate film are shown in Table 1.

Example 8

(85) A laminate film was prepared by the same method as Example 1, except that a solution in which polylactic acid-based resin PLA-2 was dissolved in ethyl acetate heated at 90 C. was employed. Characteristics of thus obtained laminate film are shown in Table 1.

Examples 9-11

(86) A laminate film was prepared by the same method as Example 1, except that the polylactic acid-based resin layer and the water-soluble resin layer had thicknesses as shown in Table 2. Characteristics of thus obtained laminate film are shown in Table 2.

Examples 12-14

(87) A laminate film was prepared by the same method as Example 1, except that the substrate film was PET-2 and the polylactic acid-based resin layer and the water-soluble resin layer had thicknesses as shown in Table 2. Characteristics of thus obtained laminate film are shown in Table 2.

Example 15-16

(88) A laminate film was prepared by the same method as Example 1, except that the substrate film was PET-2 and water-soluble resin pullulan-1 was not mixed with isopropyl alcohol to prepare a water soluble resin emulsion while polylactic acid-based resin layer and the water-soluble resin layer had thicknesses as shown in Table 3. Characteristics of thus obtained laminate film are shown in Table 3.

Comparative Example 1

(89) A laminate film was prepared by the same method as Example 1, except that the water-soluble resin layer had thickness of 30 m. Characteristics of thus obtained laminate film are shown in Table 4.

Comparative Example 2

(90) A laminate film was prepared by the same method as Example 1, except that the polylactic acid-based resin layer had thickness of 5 m. Characteristics of thus obtained laminate film are shown in Table 4.

Comparative Example 3

(91) A laminate film was prepared by the same method as Example 1, except that the water-soluble resin layer had thickness of 0.05 m and the polylactic acid-based resin layer had thickness of 500 nm. Characteristics of thus obtained laminate film are shown in Table 4.

Comparative Example 4

(92) A laminate film was prepared by the same method as Example 1, except that the water-soluble resin layer is PVA-3 while the water-soluble resin layer had thickness of 17 m and the polylactic acid-based resin layer had thickness of 100 nm. Characteristics of thus obtained laminate film are shown in Table 4.

Comparative Example 5

(93) A laminate film provided with the water-soluble resin layer was prepared by the same method as Example 1. Then, the polylactic acid-based resin PLA-3 was not able to dissolve in ethyl acetate heated at 90 C., so that the coating was not performed.

Comparative Example 6

(94) A laminate film was prepared by the same method as Comparative Example 3, except that the substrate film is PET-3. Characteristics of thus obtained laminate film are shown in Table 4.

(95) TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Substrate film Type PET-1 PET-1 PET-1 PET-1 PET-1 PET-1 PET-1 PET-1 SRa [nm] 30 30 30 30 30 30 30 30 SRz [nm] 640 640 640 640 640 640 640 640 Water-soluble Resin type PVA -1 PVA -1 PVA -1 PVA -1 PVA -1 PVA -1 PVA -2 PVA -1 resin layer Saponification 88 88 88 88 88 88 97 88 degree of polyvinyl alcohol [mol %] Thickness after 15 15 15 0.1 0.1 15 15 15 drying [m] Polylactic Resin type PLA-1 PLA-1 PLA-1 PLA-1 PLA-1 PLA-1 PLA-1 PLA-2 acid-based resin Poly-D-lactic 12 12 12 12 12 12 12 4.8 layer acid [mol %] Thickness after 10 50 500 10 500 10 100 10 drying [nm] Laminating order PET/PVA/ PET/PVA/ PET/PVA/ PET/PVA/ PET/PVA/ PET/PLA/ PET/PVA/ PET/PVA/ PLA PLA PLA PLA PLA PVA PLA PLA Peeling ability 5 5 5 3 3 5 4 4 of polylactic acid-based resin layer Adherence 1 5 5 5 3 3 5 4 4 Adherence 2 5 5 3 5 3 5 5 5 Adhesion to 4 4 4 5 5 3 4 4 substrate film Pinhole 4 5 5 3 3 4 5 4

(96) TABLE-US-00002 TABLE 2 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Substrate film Type PET-1 PET-1 PET-1 PET-2 PET-2 PET-2 SRa [nm] 30 30 30 15 15 15 SRz [nm] 640 640 640 370 370 370 Water-soluble Resin type PVA -1 PVA -1 PVA -1 PVA -1 PVA -1 PVA -1 resin layer Saponification 88 88 88 88 88 88 degree of polyvinyl alcohol [mol %] Thickness after 10 4 4 0.1 0.1 4 drying [m] Polylactic Resin type PLA-1 PLA-1 PLA-1 PLA-1 PLA-1 PLA-1 acid-based Poly-D-lactic 12 12 12 12 12 12 resin layer acid [mol %] Thickness after 160 200 160 10 500 160 drying [nm] Laminating order PET/PVA/PLA PET/PVA/PLA PET/PVA/PLA PET/PVA/PLA PET/PVA/PLA PET/PVA/PLA Peeling ability 5 5 5 3 3 5 of polylactic acid-based resin layer Adherence 1 5 5 5 3 3 5 Adherence 2 5 5 5 5 3 5 Adhesion to 4 5 5 5 5 5 substrate film Pinhole 5 5 5 4 4 5

(97) TABLE-US-00003 TABLE 3 Example 15 Example 16 Substrate film Type PET-2 PET-2 SRa [nm] 15 15 SRz [nm] 370 370 Water-soluble Resin type Pullulan-1 Pullulan-1 resin layer Saponification degree of 4 4 polyvinyl alcohol [mol %] Thickness after drying PLA-1 PLA-1 [m] Polylactic acid- Resin type 12 12 based resin layer Poly-D-lactic acid 200 160 [mol %] Thickness after drying PET/ PET/ [nm] pullulan-1/ pullulan-1/ PLA PLA Laminating order 5 5 Peeling ability of 5 5 polylactic acid- based resin layer Adherence 1 5 5 Adherence 2 5 5 Adhesion to 5 5 substrate film Pinhole 5 5

(98) TABLE-US-00004 TABLE 4 Comparative Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Substrate film Type PET-1 PET-1 PET-1 PET-1 PET-1 PET-3 SRa [nm] 30 30 30 30 30 72 SRz [nm] 640 640 640 640 640 1,088 Water-soluble Resin type PVA -1 PVA -1 PVA -1 PVA -3 PVA -1 PVA -1 resin layer Saponification 88 88 88 99 88 88 degree of polyvinyl alcohol [mol %] Thickness after 30 15 0.05 17 15 0.05 drying [m] Polylactic Resin type PLA-1 PLA-1 PLA-1 PLA-1 PLA-3 PLA-1 acid-based Poly-D-lactic 12 12 12 12 1.4 12 resin layer acid [mol %] Thickness after 10 5 500 100 500 drying [nm] Laminating order PET/PVA/PLA PET/PVA/PLA PET/PVA/PLA PET/PVA/PLA PET/PVA/PLA Peeling ability 4 5 5 4 5 of polylactic acid-based resin layer Adherence 1 4 5 5 4 5 Adherence 2 5 3 4 4 4 Adhesion to 0 4 5 4 5 substrate film Pinhole 3 2 2 2 1

INDUSTRIAL APPLICATIONS OF THE INVENTION

(99) Our invention provides a laminate film of which the water-soluble resin layer and the polylactic acid-based resin layer are easily separated from the substrate film. The laminate film comprising the water-soluble resin layer and the polylactic acid-based resin layer is excellent in covering ability, adherence and followability to a soft and curved adherend, as well as compatibility to skin and organs such as viscera, so as to be suitable for a skin external agent such as wound dressing, adhesion prevention material and skin-care product.