COATING OF A SURFACE

Abstract

This invention describes a dispersion for coating a polymer surface comprising polyglycerol esters and a surfactant being a neutralized or partially neutralised fatty acid or a neutralized or partially neutralized ester of fatty acids. The dispersion can be diluted into a coating composition, which can be applied as a coating on a polymer surface. The coating has anti-static and anti-fogging effects and can be used for for example a variety of different packaging materials.

Claims

1. A dispersion for coating a polymer surface, wherein: the dispersion comprises polyglycerol esters and a surfactant being a neutralized or partially neutralised fatty acid or a neutralized or partially neutralized ester of fatty acids, the dispersion has a solid content of from 10 to 70 wt %, and the dispersion has a viscosity of from 0.01 to 100 Pa s at a temperature of 20° C. and a shear rate of 10/s.

2-3. (canceled)

4. The dispersion according to claim 1, characterized in that, the concentration of said polyglycerol esters is above 10 wt % of the total solid content.

5. The dispersion according to claim 1, characterized in that, said surfactant is sodium stearoyl lactylate (SSL).

6. The dispersion according to claim 1, characterized in that, the dispersion further comprises monoglyceride.

7. The dispersion according to claim 6, characterized in that, the concentration of said monoglyceride is 1-50 wt % of the total solid content.

8. The dispersion according to claim 1, characterized in that, the concentration of said surfactant is 0.1-50 wt % of the total solid content.

9. The dispersion according to claim 1, characterized in that, said dispersion further comprises a co-surfactant.

10. A coating composition for coating a polymer surface comprising a dispersion as described in claim 1.

11. The coating composition as described in claim 10, wherein the coating composition comprises an anti-fogging coating.

12. The coating composition as described in claim 10, wherein the coating composition comprises an anti-static coating.

13. A coated polymer surface comprising a polymer surface coated with a coating composition as described in claim 10.

14. The coated polymer surface according to claim 13, characterized in that, said polymer is a polyester.

15. A packaging material comprising a coated polymer surface as described in claim 13.

16. The dispersion according to claim 1, characterized in that, the solid content of said dispersion is 20-50 wt %.

17. The dispersion according to claim 1, characterized in that, the solid content of said dispersion is 20-40 wt %.

18. The dispersion according to claim 1, characterized in that, the viscosity of said dispersion at a temperature of 20° C. and a shear rate of 10/s is 0.5-1.5 Pa s.

19. The dispersion according to claim 1, characterized in that, the concentration of said surfactant is 1-10 wt % of the total solid content.

20. The coated polymer surface according to claim 13, characterized in that, said polymer comprises polyethylene terephthalate (PET).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0095] FIG. 1 illustrates three different performance ratings for testing of anti-fogging on PET surfaces;

[0096] FIG. 2 illustrates the anti-fogging performance of three different coatings on PET surfaces compared to a surface without coating;

[0097] FIG. 3 illustrates anti-static coatings on PET where static decay times are measured 14 days after coating of the PET films;

[0098] FIG. 4 illustrates viscosity curves for samples ASD15, AFM15, LV42, and LV43.

EXAMPLES

Material and Methods

Preparation of Coating Dispersions

[0099] The aqueous additive dispersions were prepared by heating water in a 2l round bottom flask to 70° C. At this temperature glycerides, polyglycerides and neutralized fatty acid esters were added to the water under stirring with an anchor stirrer at 500 rpm. After one minute of stirring at 70° C. the dispersions were cooled in a water bath to 25° C. The stirring was continued during cooling. In this way translucent to white aqueous dispersions were obtained.

Preparation of Anti-Fogging PET Films

[0100] Aqueous polyglyceride dispersions were diluted with water to a concentration of 0.75 wt %. The translucent coating compositions were applied directly to APET films with a thickness of 60 μm by spray coating. The solid content per surface area on the film after air drying at 25° C. was 150 mg/m.sup.2, 200 mg/m.sup.2 or 250 mg/m.sup.2.

Test Method for Anti-Fogging Performance

[0101] The anti-fog properties were measured under cold and hot fog conditions.

[0102] A 250 ml glass beaker was filled one third with water at 20° C. The beaker was covered with the spray-coated test film. For cold fog testing the beakers were placed in the refrigerator at 5° C. For hot fog testing they were placed in a water bath at 60° C. The condensation of water on the film was observed and rated at regular intervals over a three hour test period.

[0103] The anti-fogging properties were categorized from A-E, with A and B referring to no or just a small anti-fogging effect (macroscopic water droplets are forming, turbid films), C refers to a medium performance (slightly turbid films) and D and E referring to a good and very good anti-fogging performance (a microscopic water film is forming, enabling full transparency).

Anti-Fogging Coatings on PET Film

Examples of Anti-Fogging Coating Compositions Tested

[0104]

TABLE-US-00001 TABLE 1 Sample name Coating composition* Reference 1 No coating Reference 2 100 wt % Ethoxylated sorbitan ester (PEO(20)-sorbitan monooleate) ACS 35 95 wt % GRINDSTED ® PGE 308 5 wt % sodium stearate ACS 41 95 wt % Tetraglycerol monocaprate 5 wt % sodium stearate ACS 70 95 wt % GRINDSTED ® PGE 909 5 wt % sodium stearate ACS 73 95 wt % Tetraglycerol monomyristate 5 wt % sodium stearate ACS 79 95 wt % Triglycerol monocaprate 5 wt % sodium stearate AFM 15 73 wt % GRINDSTED ® PGE 909 15 wt % DIMODAN ® HP 12 wt % sodium stearoyl lactylate *The coating composition is presented in terms of the total solid content. GRINDSTED ® PGE 308 is a polyglycerol ester in which the polyglycerol moiety is mainly mono-, di-, tri-, and tetraglycerol. GRINDSTED ® PGE 909 is a polyglycerol ester in which the polyglycerol moiety is mainly mono-, di-, tri-, and tetraglycerol. DIMODAN ® HP is a destilled monoglyceride made from edible, fully hydrogenated palm based oil.

[0105] All coating compositions were sprayed on PET films and dried. For the samples in Table 1, the solid content per surface area after drying was 200 mg/m.sup.2.

Preparation of Anti-Static PET Films

[0106] The aqueous polyglyceride dispersions were diluted with water to a concentration of 0.075 or 0.08 wt %. The translucent coating compositions were applied directly to APET films with a thickness of 60 μm by spray coating. The solid content per surface area on the film after air drying at 25° C. was 10 mg/m.sup.2, 15 mg/m.sup.2 or 25 mg/m.sup.2.

[0107] The coated film samples were stored for 14 days at a humidity of 50%.

Static Decay Time Measurements

[0108] Before the measurement, the coated films were conditioned for 24 h at 25° C. at a relative humidity (RH) of 50%. The static decay time (STD) of the samples was measured using an Electrotech Systems Static Decay meter, model 406C, equipped with a humidity chamber. The humidity chamber ensured proper conditioning of samples prior to testing. A voltage of 5 kV was applied to the sample. When the sample surface had reached full charge at 5 kV, the power supply was cut off. The time, measured in seconds, for the accepted charge to dissipate to 10% of its original value (500V) was recorded as the SDT.

[0109] The data was compared to a reference film coated with ethoxylated sorbitan ester (PCD 2) at same solid content per surface area (10 mg/m.sup.2).

Anti-Static Coatings

Examples of Anti-Static Coating Compositions Tested

[0110]

TABLE-US-00002 TABLE 2 Sample name Coating composition* PCD 1 No coating POD 2 100% Ethoxylated sorbitan ester (PEO(20)-sorbitan monooleate) PCD 3 95% Diglycerol monocaprylate 5 wt % sodium stearate PCD 4 95% Triglycerol monocaprate 5 wt % sodium stearate PCD 6 95% GRINDSTED ® PGE 308 5 wt % sodium stearate ASD 15 94% GRINDSTED ® PGE 308 6 wt % sodium stearoyl lactylate *The coating composition is presented in terms of the total solid content.

Measurement of Viscosity

[0111] The viscosity of the dispersions was measured at 20° C. on a Physica MCR301 from Anton Paar (Germany), using bob-cup system CC27. Shear flow viscosity measurements were carried out where the shear rate was first ramped from low to high shear, and then lowered again over the range of 0.01/s-300/s. The waiting time for equilibration of the samples before starting the measurements was 5 min and the measurement time 10 min.

LV 42 and LV 43 for Anti-Static and Anti-Fogging Coatings

[0112] The LV 42 and LV 43 dispersions comprise compositions and solid contents as described in Table 3.

TABLE-US-00003 TABLE 3 Solid content in the Sample name Composition dispersion LV 42 90% GRINDSTED ® PGE 308 25% 9.7% PGPR 0.3% Sodium stearate lactylate LV 43 90% GRINDSTED ® PGE 308 30% 9.85% PGPR 0.15% Sodium stearate lactylate The composition is diluted in water to form the dispersion.

[0113] Coating compositions were prepared by dilution of the dispersions LV 42 and LV 43 in water. Table 4 illustrates the coating compositions prepared and the solid contents hereof.

TABLE-US-00004 TABLE 4 Solid content in the Sample name coating composition LV 42-1 0.08% LV 42-2 0.75% LV 43-1 0.08% LV 43-2 0.75%

[0114] The coating compositions LV 42-1, LV 42-2, LV 43-1 and LV 43-2 were applied to APET films as described above. The solid content per surface area for the obtained coated polymer film samples is described in Table 5.

TABLE-US-00005 TABLE 5 Solid content per Sample name Coating composition surface area LAC 1 LV 42-1 15 mg/m.sup.2 LAC 2 LV 42-1 25 mg/m.sup.2 LAC 3 LV 42-2 150 mg/m.sup.2 LAC 4 LV 42-2 250 mg/m.sup.2 LAC 5 LV 43-1 15 mg/m.sup.2 LAC 6 LV 43-1 25 mg/m.sup.2 LAC 7 LV 43-2 150 mg/m.sup.2 LAC 8 LV 43-2 250 mg/m.sup.2

II. Results

Anti-Fogging Coatings on PET Film

[0115] FIG. 1 illustrates examples of the performance ratings A, C and D where the performance was measured at 5° C. (cold fog) 7 days after coating of the PET film.

[0116] FIG. 2 illustrates the rating of the anti-fogging coatings over time for some of the compositions. After 2 weeks storage at 25° C. the anti-fogging properties were measured in a standard test procedure over 3 h at 4° C.

[0117] The results confirm good and very good anti-fogging performance for the glyceride and polyglyceride dispersions, even exceeding the anti-fogging performance of Reference 2 (ethoxylated sorbitan ester).

[0118] Further results are shown in Table 6, where samples were tested for cold fog performance. These results illustrate that the anti-fogging properties of the coatings were maintained even several days after the production of the coating on the surface of the PET polymer. The solid content per surface area on the film after air drying at 25° C. was 200 mg/m.sup.2.

TABLE-US-00006 TABLE 6 Time in minutes Sample Days after production 1 5 15 60 120 180 Reference 1 7 A A A A A A Reference 2 7 E D C C C C 71 D C C C A A ACS 35 7 E D D D D D 64 E D D D D D ACS 41 7 E E D D D D 64 E E D D D D ACS 70 3 E E D D D E 31 E E E E E E ACS 79 3 E D D D D D 14 E D D D D D AFM 15 14 E E D C D D 30 E D C C D D

[0119] Table 7 illustrates the anti-fogging performance of coatings under hot fog conditions. These results show good anti-fogging performance also for hot fog even after several days after production. The solid content per surface area on the film after air drying at 25° C. was 200 mg/m.sup.2.

TABLE-US-00007 TABLE 7 Time in minutes Sample Days after production 1 5 15 60 120 180 Reference 1 7 A A A A A A Reference 2 7 C C B B B B 71 C C C B B B ACS 70 14 E D D A B B 31 E E E E D C ACS 73 3 E C D B B B 14 E C C B B B AFM 15 14 E C D C C C 30 E D D B B B

[0120] Table 8 illustrates the anti-fogging performance of coatings under cold fog conditions. In comparison to the non-coated sample (reference), very good (D) to excellent (E) antifogging performances were observed. The solid content per surface area on the film after air drying at 25° C. was 150 mg/m.sup.2, respectively 250 mg/m.sup.2 (see Table 5).

TABLE-US-00008 TABLE 8 Time in minutes Sample Days after production 1 5 15 60 120 180 Reference 1 4 A A A A A A 10 A A A A A A LAC 3 4 E E D D D D 10 E E D D D D LAC 4 4 E E E D E E 10 E E E E E E LAC 7 4 E E D D D D 10 E E D D D D LAC 8 4 E E E E E D 10 E E E E E E

[0121] Table 9 illustrates the anti-fogging performance of coatings under hot fog conditions. The solid content per surface area on the film after air drying at 25° C. was 150 mg/m.sup.2, respectively 250 mg/m.sup.2 (see Table 5). Over short exposure times up to 15 min excellent (E) or very good (D) antifogging performance was obtained. Overall the antifogging effect under hot fog conditions was not as long lasting than under cold fog conditions.

TABLE-US-00009 TABLE 9 Time in minutes Sample Days after production 1 5 15 60 120 180 Reference 1 4 A A A B B B 10 A A A B B B LAC 3 4 E D D B B B 10 E D D B B B LAC 4 4 E D D B B B 10 E D C B B B LAC 7 4 E C C B B B 10 E D D B B B LAC 8 4 E D D B B B 10 E E C B B B

Anti-Static Coatings on PET-Film (I)

[0122] FIG. 3 illustrates the performance of anti-static coatings on PET, where the static decay times were measured 14 days after coating of the PET films. Good anti-stat performance was generally obtained with SDT readings below 2 seconds.

[0123] These data are furthermore summarized in Table 10 showing the results of anti-static performance for coatings having a solid content per surface area of 10 mg/m.sup.2, where the measurements were performed 14 days after the coatings were applied. The coating composition was applied with a solid content of 0.075 wt %.

TABLE-US-00010 TABLE 10 Sample name Static decay time (SDT)/s PCD 1 >60 PCD 2 48 PCD 3 0.27 PCD 4 0.32 PCD 6 0.38 ASD 15 0.57

Anti-Static Coatings on PET-Film (II)

[0124] The static decay times were measured 4 and 10 days after coating of the PET films. Good anti-stat performance was generally obtained with SDT readings below 2 seconds.

[0125] The data are summarized in Table 11 showing the results of anti-static performance for coatings having a solid content per surface area of 15 mg/m.sup.2, respectively 25 mg/m.sup.2 (see Table 5), where the measurements were performed 4 days and 10 days after the coatings were applied. The coating compositions were applied with a solid content of 0.08 wt %.

TABLE-US-00011 TABLE 11 Static decay time (SDT)/s Sample name 4 days 10 days PCD 1 >60 >60 LAC 1 0.62 0.43 LAC 2 0.51 0.34 LAC 5 0.99 0.53 LAC 6 0.83 0.42

[0126] The data confirm excellent antistatic properties of the films coated with polyglycerides and monoglycerides with static decay times well below 1 s. The best performance is observed with triglycerol caprate (TGC10, STD<0.3 s) and diglycerol caprylate (DGC8, STD<1 s). Also a blend of polyglycerides with monoglycerides (GRINDSTED® PGE 308) enables a very good antistatic performance (STD<1 s).

Viscosity

[0127] The following four samples were measured in duplicates: ASD15, AFM15, LV42, LV43. Shear flow viscosity curves of the four dispersions are illustrated in FIG. 4. During increase or lowering of the shear rate the dispersions show a shear thinning effect. Typical viscosities at a shear rate of 10/s are in the range of 0.1-10 Pa s.

Summary Paragraphs

[0128] The present invention will now be described by way of numbered paragraphs. [0129] 1. A dispersion for coating a polymer surface comprising polyglycerol esters and a surfactant being a neutralized or partially neutralised fatty acid or a neutralized or partially neutralized ester of fatty acids. [0130] 2. The dispersion according to paragraph 1, wherein the concentration of said polyglycerol esters is above 10 wt % of the total solid content. [0131] 3. The dispersion according to paragraph 2, wherein the concentration of said polyglycerol esters is between 10-60 wt % of the total solid content. [0132] 4. The dispersion according to any of the paragraphs 2-3, wherein the concentration of said polyglycerol esters is between 10-30 wt % of the total solid content. [0133] 5. The dispersion according to any of the preceding paragraphs, wherein said fatty acids of said surfactant is one or more of lactic acid, citric acid, stearic acid, tartaric acid or a mixture of one or more hereof. [0134] 6. The dispersion according to any of the paragraphs 1-4, wherein said surfactant is sodium stearoyl lactylate (SSL). [0135] 7. The dispersion according to any of the preceding paragraphs, wherein the dispersion further comprises monoglyceride. [0136] 8. The dispersion according to paragraph 7, wherein the concentration of said monoglyceride is 1-50 wt % of the total solid content. [0137] 9. The dispersion according to any of the preceding paragraphs, wherein said dispersion is an aqueous dispersion. [0138] 10. The dispersion according to any of the preceding paragraphs, wherein the number of glycerol units in said polyglycerol is at least two. [0139] 11. The dispersion according to any of the preceding paragraphs, wherein said polyglycerol esters are made of fatty acids being C2-C24. [0140] 12. The dispersion according to any of the preceding paragraphs, wherein the concentration of said surfactant is 0.1-50 wt % of the total solid content. [0141] 13. The dispersion according to paragraph 12, wherein the concentration of said surfactant is 1-10 wt %. [0142] 14. The dispersion according to any of the preceding paragraphs, wherein said dispersion further comprises a co-surfactant. [0143] 15. The dispersion according to paragraph 13, wherein said co-surfactant is an alcohol. [0144] 16. The dispersion according to paragraph 14, wherein said co-surfactant is isopropanol or ethanol. [0145] 17. The dispersion according to any of the paragraphs 14-16, wherein the concentration of said co-surfactant is below 50 wt %. [0146] 18. The dispersion according to paragraph 17, wherein the concentration of said co-surfactant is 0.1-20 wt %. [0147] 19. The dispersion according to any of the preceding paragraphs, wherein the hydroxyl value of said polyglycerides of said dispersion is above 200. [0148] 20. The dispersion according to paragraph 17, wherein the hydroxyl value of said polyglycerides is between 200-500. [0149] 21. The dispersion according to any of the preceding paragraphs, wherein said dispersion further comprises an additive being an antioxidant, a biocide and/or a rheological modifier. [0150] 22. A coating composition for coating a polymer surface comprising a dispersion as described in any of the paragraphs 1-21. [0151] 23. The coating composition according to paragraph 22, wherein said coating has a solid content below 10 wt %. [0152] 24. The coating composition according to paragraph 22, wherein said coating has a solid content below 5 wt %. [0153] 25. The use of said coating composition as described in any of the paragraphs 22-24 as an anti-fogging coating. [0154] 26. The use of said coating composition as described in any of the paragraphs 22-24 as an anti-static coating. [0155] 27. A polymer surface comprising a coating formed by a coating composition as described in any of the paragraphs 22-24. [0156] 28. The polymer surface according to paragraph 27, wherein said coating has a solid content per surface area of 5-500 mg/m.sup.2. [0157] 29. The polymer surface according to paragraph 28, wherein said coating has a solid content per surface area of 5-50 mg/m.sup.2. [0158] 30. The polymer surface according to paragraph 29, wherein said coating has a solid content per surface area of 10-20 mg/m.sup.2. [0159] 31. The polymer surface according to paragraph 28, wherein said coating has a solid content per surface area of 50-500 mg/m.sup.2. [0160] 32. The polymer surface according to paragraph 31, wherein said coating has a solid content per surface area of 50-200 mg/m.sup.2. [0161] 33. The polymer surface according to any of the paragraphs 27-32, wherein said polymer is a polyester. [0162] 34. The polymer surface according to paragraph 33, wherein said polyester is polyethylene terephthalate (PET). [0163] 35. A use of a polymer surface as described in any of the paragraphs 27-34 for packaging materials. [0164] 36. The use of a polymer surface according to paragraph 35, wherein said packaging material is a food packaging material. [0165] 37. The use of a polymer surface according to any of the paragraphs 35-36, wherein said packaging material is a bottle.