Method for producing a pigmented polymer material

Abstract

Provided is a method for dyeing a polymer material with an aqueous pigment composition containing at least one pigment dispersed therein, wherein the polymer material is a blend including a first polymer composition and a second polymer composition which is compatible with the first polymer composition, which second polymer composition includes a binding agent for the at least one pigment. The method includes the steps of heating the polymer material to an activation temperature below the softening temperature of the polymer material, contacting the polymer material with the aqueous pigment composition at a contact temperature for a period of time sufficient to form a pigmented polymer material, subjecting the pigmented polymer material to a fixation step to fixate the at least one pigment therein by cooling the pigmented polymer material to a fixation temperature which is lower than the temperature at which contacting of the polymer material with the aqueous pigment composition is carried out.

Claims

1. A method for dyeing a polymer material with an aqueous pigment or dye composition containing at least one pigment or dye dispersed therein, wherein the polymer material is a blend comprising a first polymer composition and a second polymer composition which is compatible with the first polymer composition, which second polymer composition comprises a binding agent for the at least one pigment or dye, wherein the binding agent comprises: a) a copolymer, wherein the copolymer has a polyolefin backbone, including a backbone of ethylene, and further comprises acrylic or methacrylic ester and maleic anhydride or an alkyl (meth)acrylate/maleic anhydride copolymer; b) a terpolymer; or c) a polymer containing amine terminated polyamide moieties, including an amine terminated polyamide; wherein the method comprises the steps of: heating the polymer material to an activation temperature below the softening temperature of the polymer material, contacting the polymer material with the aqueous pigment or dye composition at a contact temperature for a period of time sufficient to form a pigmented or dyed polymer material, subjecting the pigmented or dyed polymer material to a fixation step to fixate the at least one pigment or dye therein by cooling the pigmented or dyed polymer material to a fixation temperature which is lower than the temperature at which contacting of the polymer material with the aqueous pigment or dye composition is carried out.

2. The method according to claim 1, wherein the polymer material is heated to the activation temperature simultaneously with or in advance of contacting the polymer material with the aqueous pigment or dye composition.

3. The method according to claim 1, wherein the contact temperature is a temperature which is lower than, equal to or higher than the activation temperature.

4. The method according to claim 1, wherein the fixation temperature is lower than the activation temperature.

5. The method according to claim 1, wherein the activation temperature is a temperature of at least 60° C.

6. The method according to claim 1, wherein the activation temperature is a temperature of below 150° C.

7. The method according to claim 1, wherein heating to the activation temperature is carried out using contact heat, by contacting the polymer material with at least one of steam, heated air, and heated liquid, wherein the heated liquid is heated water, by subjecting it to irradiation with a suitable energy, including UV, IR or visible light irradiation, or a combination of two or more of these techniques.

8. The method according to claim 1, wherein the fixation step is carried out by cooling the pigmented or dyed polymer material to a temperature which is at least 10° below the contact temperature.

9. The method according to claim 1, wherein the aqueous pigment or dye composition has a temperature which is a maximum 30° below the activation temperature.

10. The method according to claim 9, wherein the aqueous pigment or dye composition has a pH of between 2.0 and 12.0.

11. The method according to claim 1, wherein the polymer material is subjected to drying after having been contacted with the aqueous pigment or dye composition and in advance of being subjected to the fixation step.

12. The method according to claim 1, wherein the polymer material is contacted with the pigment or dye composition at atmospheric pressure, or a pressure above atmospheric pressure.

13. The method according to claim 12, wherein the pigment or dye composition is an aqueous dispersion of at least one ionic pigment or dye, one or more anionic pigments or dyes or one or more cationic pigments or dyes, or a mixture hereof.

14. The method according to claim 1, wherein the second polymer composition comprises the first polymer composition including polypropylene.

15. The method according to claim 1, wherein the concentration of the binding agent in the second composition is between 0.05 and 20 wt. with respect to the total weight of the polymer material.

16. The method according to claim 1, wherein the first polymer composition is a synthetic polymer material, selected from the group of a polyolefinic material, a polyester, in particular a semi aromatic polyester including polyethylene terephtalate (PET), a polybutylene terephtalate (PBT), an aliphatic polyester in particular polycaprolactone, polylactic acid, a polyamide, including an aliphatic polyamide, including nylon 6 and nylon 66, a polyphtalamide or an aramide, a polyurethane, or a mixture of two or more of these materials.

17. The method according to claim 1, wherein the first polymer composition is a polyolefin selected from the group of polyethylene, polypropylene, polybutadiene, or a blend or a copolymer of two or more of the afore-mentioned materials including polypropylene.

18. The method according to claim 1, wherein the polymer material is formed into fibers, into a foamed material, into a film or sheet or molded into an object, in advance of being contacted with the aqueous pigment or dye dispersion.

19. The method according to claim 1, wherein the copolymer comprises acrylic or methacrylic ester and maleic anhydride and further comprises glycidyl methacrylate.

20. The method according to claim 19, wherein the copolymer has a glycidyl methacrylate content of at least 7.0 wt. %.

21. The method according to claim 1 wherein the binding agent is a blend which consists essentially of the terpolymer and the polymer containing amine terminated polyamide moieties, including an amine terminated polyamide; wherein the terpolymer is selected from: (i) a terpolymer selected from: a first terpolymer of ethylene, acrylic or methacrylic ester and maleic anhydride having a maleic anhydride content of at least 2% by weight, or (ii) a second terpolymer of ethylene, acrylic or methacrylic ester and glycidyl methacrylate having a glycidyl methacrylate content of at least 7% by weight, and mixtures thereof.

22. The method according to claim 21, wherein the weight ratio of the terpolymer to the amine-terminated polyamide in the blend is from 3:1 to 1:1 .

23. The method according to claim 1, wherein the first polymer composition comprises a biaxially oriented polypropylene with a melt flow index of maximum 45 g/10 min at 190° C. and 2.16 kg and the binding agent has a melt flow index of maximum 45 g/10 min at 190° C. and 2.16 kg.

24. The method according to claim 1, wherein the concentration of the binding agent in the second polymer composition is between 0.05 and 15 wt. % with respect to the total weight of the polymer composition.

25. The method according to claim 1, wherein the polymer material is a woven or non-woven sheet material of fibers, which fibers are made of a polymer material comprising the first polymer composition comprising polypropylene and the second polymer composition comprising the binding agent.

26. A method for producing a printed polymer sheet material, the method comprising the steps of producing a polymer sheet material by blending a first polymer composition and a second polymer composition comprising a binding agent, wherein the binding agent comprises: a) a copolymer, wherein the copolymer has a polyolefin backbone, including a backbone of ethylene, and further comprises acrylic or methacrylic ester and maleic anhydride or an alkyl (meth)acrylate/maleic anhydride copolymer; b) a terpolymer; or c) a polymer containing amine terminated polyamide moieties, including an amine terminated polyamide; followed by heating the polymer sheet material to an activation temperature below the softening temperature of the polymer material, contacting the polymer sheet material with an aqueous pigment or dye composition and applying a printed image at a contact temperature, subjecting the printed polymer sheet material to a fixation step to fixate at least one pigment or dye therein by cooling the printed polymer material to a fixation temperature which is lower than the temperature at which contacting of the polymer material with the aqueous pigment or dye composition is carried out.

27. The method according to claim 1, wherein the polymer material is subjected to co-extrusion of a multi-layer sheet comprising at least a first layer comprising the first polymer composition and a second layer comprising the second polymer composition comprising the binding agent.

28. The method according to claim 27, wherein the side of the multi-layer sheet comprising the second polymer composition, is printed with a printed image.

29. The method according to claim 27, wherein printing comprises the steps of : heating the multi-layer sheet to an activation temperature below the softening temperature of the polymer material, printing a side of the multi-layer sheet comprising the second polymer composition at a printing temperature which is at least the contact temperature, subjecting the printed polymer material to a fixation step to fixate the at least one pigment or dye therein by cooling the printed multi-layer sheet to a fixation temperature which is lower than the printing temperature.

30. The method according to claim 27, wherein a face of the polymer sheet material is printed, which contains the second polymer composition.

Description

EXAMPLE 1-3

(1) A 3-layer film was produced using co-extrusion of polypropylene supplied by Borrealis, at a temperature of between 240 and 260° C. The first and second layer consisted essentially of polypropylene. The third layer contained varying amounts of binding agent. As the binding agent use is made of a mixture of (1) a first terpolymer of acrylic acid and maleic anhydride having a maleic anhydride content of 4% by weight, (2) a second terpolymer of ethylene, acrylic or methacrylic ester and glycidyl methacrylate having a glycidyl methacrylate content of 10% by weight (3) an amine-terminated polyamide,
in a weight ratio of terpolymer to amine-terminated polyamide of 1.5:1.

(2) The amounts of binding agent were respectively 5 wt. % with respect to the weight of the third layer, 10 wt. % and 20 wt. %. The first layer had a thickness of 80 micron, the second layer had a thickness of 10 micron, the third layer had a thickness of 10 micron.

(3) The film was aged by maintaining it at room temperature 25° C. for 1 week.

EXAMPLE 4

(4) Both sides of the film were printed in ink-jet printing using a water-based ink having a pH of 4.5. Before being subjected to printing, the film was heated to a temperature of respectively 70, 80 and 90° C. using contact heat. After the printing had been finished, the printed image was fixated by cooling the printed film to a temperature of 75° C. The ink had a temperature of 90° C. during the printing process.

(5) The quality of the print was evaluated using a standard ink pull-off tape test immediately after printing of the polymer sheet material had been finished. In such testing no or hardly any ink, pigment or dye could be removed. In a standard ink pull-off tape test, the printed side of the polymer sheet material is covered with adhesive tape, the tape is rubbed and removed, and the presence of ink, pigment or dye on the tape is measured. No or hardly any removal of ink, pigment or dye could be observed from the side of the film which contained the layer comprising the binding agent.

(6) The quality of the print was further evaluated according to ISO 5470-2:2003 by moving a plate to which four plastic wheels are attached, over the printed side of the film. No or hardly any removal of ink, pigment or dye could be observed. No or hardly any removal of ink, pigment or dye could be observed from the side of the film which contained the layer comprising the binding agent.

(7) The opposite side of the film, i.e. the side which did not contain the binding agent, showed a slight release of pigment.

(8) In the ISO 105 X12 test, a color fastness grade of 5 could be observed.

EXAMPLE 5

(9) Example 4 was repeated, with the exception that the ink was used at room temperature, i.e. had a temperature of 25° C. When contacting the film with water, the film maintained hardly any pigmentation, i.e. the majority of the ink that had been applied to the film was removed.

(10) Also, when subjected to a standard ink pull-off tape test, where the printed side of the polymer sheet material is covered with adhesive tape, the tape is rubbed and removed, and the presence of ink, pigment or dye on the tape is measured. The majority of the pigment was removed from both sides of the film, also from the side of the film, which contained the layer comprising the binding agent.

(11) The quality of the print was further evaluated by moving a plate to which four plastic wheels are attached, over the printed side of the film as described above, according to ISO 5470-2:2003. The majority of the pigment present on the side of the film, which contained the layer comprising the binding agent could be removed. Also, the opposite side of the film, i.e. the side which did not contain the binding agent, showed a significant release of pigment.

(12) In the ISO 105 X12 test, a color fastness grade of 1 could be observed.

(13) From this experiment it can be concluded that cooling of the polymer material results in a fixation of the structure and counteracts penetration of pigment from the outside into the polymer material or release of pigment from the polymer material.

EXAMPLE 6

(14) 24 plates were produced having a standardized dimension of a length of 64 mm, a width of 50 mm and a thickness of 2 mm, using polypropylene supplied by Borrealis, by melting of the polypropylene at a temperature of between 240 and 260° C. followed by injection molding of the standardize plates.

(15) The polypropylene contained 10 wt. % of the binding agent of example 5, with respect to the weight of the polymer composition.

(16) Each of the thus produced plates was contacted with a pigment dispersion of a blue and a red pigment, in particular Bemacron pigments, by submerging the plates in the pigment composition for a contact time of respectively 15, 30, 60 and 120 minutes, the pigment composition had a temperature of respectively 70, 80 and 90° C. at atmospheric pressure and at a pressure of 1.5 atm.

(17) The pigment composition had a pH of 3.9.

(18) Varying pigment concentrations were used, in particular 0.0001 wt. %, 0.001 wt. %, 0.01% wt. % and 0.1 wt. % of pigment with respect to the weight of the composition. Thereafter, the plates were removed from the pigment dispersion. The plates that had been contacted with a 70° C. pigment dispersion were cooled to a temperature of 50° C., rinsed with water to remove the excess of pigment dispersion that accumulated on the surface. The plates that had been contacted with an 80° C. and 90° C. pigment dispersion were cooled to a temperature of 70° C., rinsed with water to remove the excess of pigment dispersion that accumulated on the surface.

(19) The following observations were made: when comparing the experiments carried out at the same temperature, same pressure, and same pigment concentration, with a varying contact time, the longer the contact time, the more intense the coloration of the polypropylene plates. The biggest difference in coloration was observed between a contact time of 15 minutes and 60 minutes. At a contact time of 60 minutes, intensively colored plates were obtained. Increasing the contact time to 120 minutes resulted in further increase in the coloration of the plates, but the difference was less pronounced than with 15-60 minutes. when comparing the experiments carried out at the same pressure, same contact time and same pigment concentration, with a varying contact temperature, using a higher temperature increased the intensity of the coloration of the polypropylene plates when comparing the experiments carried out at the same temperature, same contact time and same pigment concentration, the use of a higher pressure increased the intensity of the coloration of the polypropylene plates when comparing the experiments carried out at the same temperature, the same pressure, same contact time, but increasing the pigment concentration, increased the coloration of the polypropylene plates. With a concentration of 0.0001 wt. %, at atmospheric pressure only a faint coloration of the plate could be obtained. When cutting through the plates, it was observed that the pigment had penetrated the plates over a thickness of about 0.5 mm from all sides of the plates. In particular it has been observed that the plates were penetrated over about 30% of their over-all thickness.

(20) When subjecting the pigmented plates to the ISO 105 X12 test, a color fastness grade of 5 could be observed.

EXAMPLE 7

(21) The same plates were used as in example 6, which contained 10 wt. % with respect to the total weight of the polymer material of the binding agent. The procedure was repeated as described in example 6, using a temperature of 90° C., and 120 minutes of contact time. As a pigment use was made of a green fluorescent pigment, of microbial origin.

(22) It has been observed that a stable binding of the green fluorescent pigment in the polypropylene plates of embodiments of this invention could be obtained. This is surprising as incorporation of fluorescent materials into polymer materials did not yet lead to satisfactory results.

(23) When subjecting the pigmented plates to the ISO 105 X12 test, a color fastness grade of 5 could be observed.

EXAMPLE 8

(24) The plates produced in example 4 were subjected to an after treatment to test the quality of the pigmentation.

(25) To that end each of the plates was submerged for 15 minutes in a solution at 60° C. of 2 g/l of Redulit Gin, a reduction agent 2 g/l of Sarabid DLO, an anionic surfactant A mixture of 2 g/l of Sarabid DLO, 4 mg/l of NaOH and 3 g/l of hydrosulfite A mixture of 2 g/l of Sarabid DLO, 4 mg/l of NaOH and 2 g/l of Redulit F.

(26) None of these treatments caused release of pigment contained in any of the plates. It can therefore be concluded that the pigmented polymer material obtained with embodiments of the present invention is suitable for use with food, as no pigment release occurs when the pigmented side of the polymer material is contacted with chemical compounds frequently used with food.

EXAMPLE 9

(27) 7 plates were produced having a standardized dimension of a length of 64 mm, a width of 50 mm and a thickness of 2 mm, using polypropylene supplied by Borrealis, by melting of the polypropylene at a temperature of between 240 and 260° C. followed by injection molding of the standardize plates.

(28) The polypropylene contained varying amounts of binding agent, in particular 1.0 wt. %, 2.5 wt. %, 5 wt. %, 7.5 wt. %, 10 wt. %, 12.5 wt. %, 15 wt. %, with respect to the weight of the polymer composition.

(29) Each of the thus produced plates was contacted with a pigment dispersion of Bemacron E, by submerging the plates in the pigment composition of 120° C. for a contact time of 60 minutes. The pigment composition had a pH of 3.9. Thereafter, the plates were removed from the pigment dispersion and cooled to a temperature of 70° C., rinsed with water to remove the excess of pigment dispersion that accumulated on the surface.

(30) All plates had a similar color and intensity of coloration. It is assumed that at a temperature of 120° C., either optimal permeability of the polymer material for the pigment dispersion may be achieved, or that the affinity of the polymer material for the pigment dispersion is optimal at that temperature, or that the pigment shows enhanced mobility at that temperature, or a combination of two or more of these factors.

(31) When subjecting the pigmented plates to the ISO 105 X12 test, a color fastness grade of 5 could be observed.

EXAMPLE 10

(32) A sheet was produced of a woven material, made by weaving of polypropylene fibers which contained respectively 5.0 and 8.0 wt. % of the binding agent used in example 1. The fibers were woven to form a cloth.

(33) The woven fiber cloth was dyed with a grey pigment and thereafter subjected to printing using an aqueous low energy sublimation disperse ink. Before printing the woven fiber cloth, the cloth was heated to a temperature of 90° C., by contacting it with a heated metal plate. Then the cloth was printed, and after printing cooled to a temperature of 110° C.

(34) The quality of the printed cloth was evaluated as excellent, the highest standard of abrasion resistance, color fastness could be obtained.

(35) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

(36) For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. The mention of a “unit” or a “module” does not preclude the use of more than one unit or module.