Method and a thermoplastic film for use in a printed packaging of absorbent hygienic articles
The present disclosure relates to a method for establishing the suitability for printing of a thermoplastic film for use in a packaging of absorbent hygienic articles, said thermoplastic film comprising at least 30% recycled polymer material. The method comprises scanning a sample of said film for Gel Spots, defining an Amount of Gel spots and a Relative Gel Spot Coverage area, and, determining that if the Amount of Gel Spots is less than or equal to a first threshold and the Relative Gel Spot Coverage Area is less than or equal to a second threshold, determining that said thermoplastic film is suitable for printing. The disclosure also relates to a method of forming a package from a thermoplastic film, and to a package comprising a thermoplastic film.
1. A method for establishing the suitability for printing of a thermoplastic film for use in a packaging of absorbent hygienic articles, said thermoplastic film comprising at least 30% recycled polymer material, the method comprising:
providing a sample of said thermoplastic film, said sample being 10 cm×10 cm;
scanning said sample to provide a pixelized image of said sample;
computer analyzing said pixelised image using a thresholding method to transfer the image to a binary image in which each pixel is determined as either dark or light;
defining each group of neighbouring pixels deemed to be dark as a Gel Spot;
defining a Gel Spot Size for each Gel Spot being the circle equivalent diameter to the pixel area of the Gel Spot;
determining an Amount of Gel Spots indicative of the number of Gel Spots in said sample, which have Gel Spot Size greater than or equal to 150 μm; and
determining a Relative Gel Spot Coverage Area indicative of the relative area of said sample covered by Gel Spots having a Gel Spot Size greater than or equal to 150 μm, using said circle equivalent diameter; and
if said Amount of Gel Spots is less than or equal to a first threshold and said Relative Gel Spot Coverage Area is less than or equal to a second threshold, determining that said thermoplastic film is suitable for printing; and
if said Amount of Gel Spots is greater than said first threshold and/or said Relative Gel Spot Coverage Area is greater than said second threshold, determining that said thermoplastic film is not suitable for printing.
2. The method according to claim 1 , wherein said first threshold is less than or equal to 450 per 100 cm 2 sample.
3. The method according to claim 1 , wherein said second threshold is less than or equal to 20%.
4. The method according to claim 1 , wherein said film comprises coloured pigments in the film resin.
5. The method according to claim 1 , wherein said film has a thickness of between 20-70 μm.
6. The method according to claim 1 , wherein said film comprises less than 80% recycled polymer material.
7. The method according to claim 1 , wherein said film comprises:
a. a total sum of phthalates being in the range 0.05 to 250 mg/kg (ppm); and/or
b. a total sum of organic tin compounds being in the range 0.0003 to 0.5 mg/kg (ppm); and/or
c. a total sum of heavy metals being in the range 0.1 to 100 mg/kg (ppm); and/or
d. a total sum of Bisphenol A being in the range 0.05 to 20 mg/kg (ppm).
8. The method according to claim 1 , wherein said method comprises determining a haze of said thermoplastic film, and
if said haze is within a haze range, determining that said film is suitable for printing and for a packaging of hygienic absorbent products, and
if said haze is outside of said haze range, determining that said film is unsuitable for printing and for a packaging of hygienic absorbent products,
wherein said haze range is less than 25%, and
wherein haze is measured as the percentage of incident light scattered by more than 2.5° through said film.
9. The method according to claim 8 , wherein said haze range is less than 20%, or 4 to 18%.
10. The method according to claim 1 , wherein said method comprises:
Determining a MD force at 5% elongation in the machine direction of said film, and
if said MD force at 5% elongation is within a MD force at 5% elongation range,
determining that said film is suitable for printing and for a packaging for hygienic absorbent product, and
if said MD force at 5% elongation is outside of said MD force at 5% elongation range,
determining that said film is unsuitable for printing and for a packaging for hygienic absorbent products,
wherein said MD force at 5% elongation range is greater or equal to 3 N/15 mm, and optionally 4 to 9 N/15 mm.
11. The method according to claim 1 , wherein said method comprises:
Determining a CD force at 5% elongation in the cross direction of said film, and
if said CD force at 5% elongation is within a CD force at 5% elongation range,
determining that said film is suitable for printing and for a packaging for hygienic absorbent product, and
if said CD force at 5% elongation is outside of said CD force at 5% elongation range,
determining that said film is unsuitable for printing and for a packaging for hygienic absorbent products,
wherein said CD force at 5% elongation range is greater or equal to 3 N/15 mm, and optionally 4 to 9 N/15 mm.
12. The method according to claim 1 , wherein said method comprises:
Determining a CD 2% secant modulus in the cross direction of said film, if said CD 2% secant modulus is within a CD 2% secant modulus range, determining that said film is suitable for printing and for a packaging for hygienic absorbent product, and
if said CD 2% secant modulus is outside of said CD 2% secant modulus range,
determining that said film is unsuitable for printing and for a packaging for hygienic absorbent products,
wherein said CD 2% secant modulus range is from 200 to 600 MPa.
13. The method according to claim 1 , wherein said method comprises:
Determining a MD 2% secant modulus in the machine direction of said film, and if said MD 2% secant modulus is within a MD 2% secant modulus range, determining that said film is suitable for printing and for a packaging for hygienic absorbent product, and if said MD 2% secant modulus is outside of said MD 2% secant modulus range,
determining that said film is unsuitable for printing and for a packaging for hygienic absorbent products,
wherein said MD 2% secant modulus range is from 200 to 550 MPa.
14. A method of forming a package for absorbent articles comprising:
providing a thermoplastic film material;
determining said thermoplastic film to be suitable for printing for use in a packaging for hygienic absorbent articles by performing the method according to claim 1 ; and
forming a package for hygienic absorbent articles comprising said thermoplastic film.
15. The method according to claim 14 , comprising
at least a portion of said film.
16. The method according to claim 14 , wherein said step of forming a package comprises forming a package of said thermoplastic film such that said thermoplastic film forms an outer surface of said package.
17. The method according to claim 14 , wherein said package comprises said thermoplastic film as a co-extruded monolayer film.
18. The method according to claim 14 , wherein said step of forming a package comprises folding said thermoplastic film to form a pocket or bag.
19. The method according to claim 14 , comprising filling said package with absorbent hygienic articles.
20. The method according to claim 19 , wherein said absorbent articles is a stack of sanitary articles.
21. The method according to claim 19 , wherein said absorbent articles comprise absorbent tissue paper or nonwoven.
22. A package for an absorbent article made by the method according to claim 14 .
23. The package according to claim 22 , wherein said thermoplastic film comprises at least 30 to 80% by weight recycled polymers, and said thermoplastic film has a continuous unprinted area (4) of at least 10×10 cm, wherein said thermoplastic film has a Gel Spot Amount being less than or equal to 450 per 100 cm 2 sample and a Gel Spot Relative Coverage Area being less than or equal to 20%, as determined by the method according to any one of claims 1-12 .
24. The package according to claim 23 , wherein, in said package, said thermoplastic film has a printed area outside of said continuous unprinted area.
25. The package according to claim 23 , wherein said thermoplastic film, at least in said unprinted area, is transparent.
26. The package according to claim 22 , wherein said thermoplastic film comprises coloured pigment in the film resin.
27. An array of at least 1000 packages according to claim 22 , the packages having similar appearance and content.
28. The package according to claim 22 comprising an absorbent hygienic article.
29. The method according to claim 1 comprising forming an array of packages of said film, said array comprising at least 1000 packages.
30. The method according to claim 1 , wherein said first threshold is less than or equal to 300 per 100 cm 2 sample.
31. The method according to claim 1 , wherein said second threshold is less than or equal to 12%.
32. The method according to claim 1 , wherein a total sum of phthalates is in the range 0.05 to 100 mg/kg (ppm) or 0.05 to 20 mg/kg (ppm); and/or
a total sum of organic tin compounds is in the range 0.0003 to 0.1 mg/kg (ppm) or 0.0003 to 0.02 mg/kg (ppm); and/or
a total sum of heavy metals is in the range 0.1 to 60 m/kg (ppm) or 0.1 to 30 mg/kg (ppm); and/or
a total sum of Bisphenol A is in the range 0.05 to 10 mg/kg (ppm) or 0.05 to 5 mg/kg (ppm).
33. The method according to claim 1 , comprising forming an array of packages of said film, said array comprising at least 10,000 packages.