PROCESS FOR MANUFACTURING A WATER-SOLUBLE SHEET

Abstract

The invention relates to a method of manufacturing a water-soluble sheet having an area of structured surface pattern, the structured surface pattern having one or more structural features having a measurement of less than 1000 m wherein the method comprises the steps of: a) providing a substrate having an area of complementary structured surface pattern; b) depositing a solution comprising a water-soluble polymer onto the substrate; and c) drying the solution to form a water-soluble sheet comprising an area of structured surface pattern.

Claims

1. A method of manufacturing a water-soluble sheet having an area of structured surface pattern, the structured surface pattern having one or more structural features having a measurement of less than 1000 m wherein the method comprises the steps of: a) providing a substrate having an area of complementary structured surface pattern; b) depositing a solution comprising a water-soluble polymer onto the substrate; and c) drying the solution to form a water-soluble sheet comprising an area of structured surface pattern.

2. A method of manufacturing a water-soluble sheet having an area of structured surface pattern, the structured surface pattern having one or more structural features having a measurement of less than 1000 m, the method comprising the steps of: a) providing a mixture comprising a water-soluble polymer; b) extruding the mixture through a die; c) contacting the mixture with a substrate having an area of complementary structured surface pattern; and d) forming a water-soluble sheet comprising an area of structured surface pattern from the mixture.

3. The method according to claim 1, wherein the area of complementary structured surface pattern covers from 1-50% of the surface of at least one side of the substrate.

4. The method according to claim 1, wherein the complementary structured surface pattern comprises one or more depressions and/or protrusions.

5. The method according to claim 4, wherein the depression is a groove, a rectangular depression, a circular depression, a cross shaped depression, and/or a hexagonal shaped depression.

6. The method according to claim 4, wherein the protrusion is a groove, a rectangular protrusion, a circular protrusion, a cross shaped protrusion, and/or a hexagonal shaped protrusion.

7. The method according to claim 4, wherein the depressions and/or protrusion have a centre to centre distance between adjacent depressions and/or protrusions of from 1 nm-100 m.

8. The method according to claim 4, wherein the centre to centre distance between adjacent depressions and/or protrusions is substantially the same.

9. The method according to claim 4, wherein the protrusions and/or depressions are parallel.

10. The method according to claim 1, wherein the water-soluble polymer is PVOH.

11. The method according to claim 1, wherein the substrate is a metal, polymeric material, silicon, or silicon derivative.

12. The method according to claim 2, wherein the area of complementary structured surface pattern covers from 1-50% of the surface of at least one side of the substrate.

13. The method according to claim 2, wherein the complementary structured surface pattern comprises one or more depressions and/or protrusions.

14. The method according to claim 13, wherein the depression is a groove, a rectangular depression, a circular depression, a cross shaped depression, and/or a hexagonal shaped depression.

15. The method according to claim 13, wherein the protrusion is a groove, a rectangular protrusion, a circular protrusion, a cross shaped protrusion, and/or a hexagonal shaped protrusion.

16. The method according to claim 13, wherein the depression and/or protrusion have a centre to centre distance between adjacent depressions and/or protrusions of from 1 nm-100 m.

17. The method according to claim 13, wherein the centre to centre distance between adjacent depressions and/or protrusions is substantially the same.

18. The method according to claim 13, wherein the protrusions and/or depressions are parallel.

19. The method according to claim 2, wherein the water-soluble polymer is PVOH.

20. The method according to claim 2, wherein the substrate is a metal, polymeric material, silicon, or silicon derivative.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0099] In order that the invention may be more clearly understood, one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0100] FIG. 1: is an image of a water-soluble sheet according to the present invention described in Example 1 (left) and a water-soluble sheet not according to the present invention described in Reference Example 2 (right).

[0101] FIG. 2: is a digital microscope (Keyence VHX-7000 with lens VHX-E100) image of a film according to the present invention described in Example 1.

[0102] FIG. 3: is a scanning electron microscope image (4800 zoom and 44000 zoom) of a film according to the present invention described in Example 1.

[0103] FIG. 4: is an image of a water-soluble package produced from the water-soluble film described in Example 1.

[0104] FIG. 5: is a digital microscope image (Keyence VHX-7000 with lens VHX-E100) of a film not according to the present invention described in Reference Example 2.

[0105] FIG. 6: is a scanning electron microscope image (830 zoom and 4500 zoom) of a film not according to the present invention described in Reference Example 2.

[0106] FIG. 7: is an image of the surface of a water-soluble sheet according to the present invention described in Example 3.

[0107] FIG. 8: is an image of a water-soluble package produced from the water-soluble film described in Example 3.

[0108] FIG. 9: is an image of a water-soluble sheet according to the present invention described in Example 4.

EXAMPLES

Example 1

[0109] 5 g of PVOH film (SOLUBLON GA film) was dissolved in 25 mL of de-ionised water to form a solution. The solution was then cast on a PET diffraction grating (SKU #01503 from Rainbow Symphony), having a surface pattern of 1000 depressions per mm, using film application device COATMASTER 510 Basic-G. The film was left to dry overnight at a temperature of 20 C. and 37% relative humidity to form a water-soluble film having a structured surface pattern. The film obtained by this process is shown in FIG. 1 (left). As shown, the film possesses iridescent colour regions.

[0110] Moreover, as shown in FIGS. 2 and 3, when viewed under a digital microscope and scanning electron microscope, the film exhibited protrusions on the surface of the film. The centre to centre distance of adjacent protrusions is around 950-1050 nm.

[0111] The film was then processed into a water-soluble package. As shown in FIG. 4, the water-soluble package exhibits iridescent colour regions.

Reference Example 2

[0112] 5 g of PVOH film, (SOLUBLON GA film) was dissolved in 25 mL of de-ionised water to form a solution. The solution was then cast on a glass surface having no structured surface pattern. The film was left to dry overnight at a temperature of 20 C. and 37% relative humidity to form a water-soluble film. The film obtained by this process is shown in FIG. 1 (right). As shown, the film does not possess any iridescent colour regions.

[0113] Moreover, as shown in FIG. 5 and FIG. 6, when viewed under a digital microscope and scanning electron microscope the film did not exhibit protrusions on the surface of the film.

Example 3

[0114] 5 g of PVOH film (SOLUBLON GA film) was dissolved in 25 mL of de-ionised water to form a solution. The solution was then cast on a PET diffraction grating (Temilux ID Pure Film in 210 m from Temicon) and the thickness of the film was adjusted using applicator MULTICATOR 411. The film was left to dry overnight at a temperature of 20 C. and 37% relative humidity to form a PVOH film having a structured surface pattern. The film obtained by this process is shown in FIG. 7. As shown, the film possessed corresponding surface pattern and roughness.

[0115] The film was then processed into a water-soluble package. As shown in FIG. 8, the water-soluble package exhibits iridescent colour regions.

Example 4

[0116] A Collin ZK 25*42D twin screw extruder was used to prepare a melt at 185 C. from a mixture comprising 20.4% low molecular weight PVOH resin and 56.4% high molecular weight PVOH resin, 22% plasticizers and 1.2% processing aids. The melt was fed with a melt pump to a flat die for extrusions at a speed of from 5 to 15 kg/h. After extrusion the mixture was formed on 2 chrome plated Chill-Rolls to a film. The first Chill-Roll had a cooling temperature of 60 C. and the second Chill-Roll had a cooling temperature of 20 C. The first Chill-Roll had a structured surface pattern. The film was then wounded with a hall-off system to the desired thickness.

[0117] As shown in FIG. 9, the resulting water-soluble film possessed a structured surface pattern and iridescent colour regions.

Reference Example 5

[0118] A Collin ZK 25*42D twin screw extruder was used to prepare a melt at 185 C. from a mixture comprising 20.4% low molecular weight PVOH resin and 56.4% high molecular weight PVOH resin, 22% plasticizers and 1.2% processing aids. The melt was fed with a melt pump to a flat die for extrusion at a speed of from 5 to 15 kg/h. After extrusion the mixture was formed on 2 chrome plated Chill-Rolls to a film. The first Chill-Roll had a cooling temperature of 60 C. and the second Chill-Roll had a cooling temperature of 20 C. Neither Chill-Roll possessed a structured surface pattern. The film was then wounded with a hall-off system to the desired thickness.

[0119] The resulting water-soluble film did not possess a structured surface pattern and did not possess iridescent colour regions.

Mechanical Properties

[0120] Films with thickness of 90 m were produced according to the method stated in Example 1 and Reference Example 2. The tensile and sealing properties were then tested according to ISO 527-3 and ASTM F88 on a Zwicki-Line testing machine Z1.0. The results are shown in Table 1 below.

TABLE-US-00001 TABLE 1 Maximum Elongation at Maximum force till force/N break/mm seal destroyed/N Example 1 53.2 3.1 199 10 26.6 0.9 Reference 52.9 5.3 196 15 24.5 3.2 Example 2

[0121] From these results, it can be seen that a PVOH film having a structured surface pattern produced according to the first aspect of the present invention displays no discernible difference in tensile and sealing properties, while providing the improved aesthetic effect, as shown in FIG. 1.

[0122] In addition, films with thickness of 90 m were produced according to the method stated in Reference Example 2 and Example 3. The coefficient of friction of these films were tested. The results are shown in Table 2 below.

TABLE-US-00002 TABLE 2 Coefficient of friction Reference Example 2 >10 Example 3 1.0

[0123] As seen from Table 2, PVOH films having a structured surface pattern produced according to the present invention had a much lower coefficient of friction than films not produced by the present process of the invention, and thus not possessing a structured surface pattern. This indicates that the presence of a structured surface pattern may improve the clinginess of the film.

[0124] Films with thickness of 90 m were produced according to the method stated in Example 4 and Reference Example 5. Tensile and sealing properties of these films were then tested according to ISO 527-3 and ASTM F88 on a Zwicki-Line testing machine Z1.0. The results of this test are shown in Table 3 below.

TABLE-US-00003 TABLE 3 Machine direction Transverse direction Maximum force Maximum Elongation Maximum Elongation at till seal force/N at break/mm force/N break/mm destroyed/N Example 89.2 3.8 160 6 57.3 3.5 217 8 44.3 5.0 4 film Example 77.9 9.8 136 15 52.0 5.7 220 15 51.8 3.5 5 film

[0125] As shown in Table 3, PVOH films having a structured surface pattern produced according to the second aspect of the present invention display no discernible difference in tensile and sealing properties, while providing an improved aesthetic effect.

[0126] It is of course to be understood that the present invention is not intended to be restricted to the foregoing examples which are described by way of example only.