SURFACE-TREATED FILLERS FOR POLYESTER FILMS

Abstract

The present invention relates to a mono or multi-layer polyester film, a process for producing the mono or multi-layer polyester film, an article comprising the mono or multi-layer polyester film as well as the use of the mono or multi-layer polyester film packaging products, insulating materials, solar, marine or aviation applications, science, electronic or acoustic applications, wires, cables, radio frequency identifications, flexible circuits, graphic arts, stone paper, holograms, filter products, cosmetic products, household products imaging, recording media, or industrial products.

Claims

1. A mono or multi-layer polyester film, wherein at least one layer of the film comprises at least one polyester in an amount ranging from 70.0 to 99.9 wt.-% and a surface-treated filler material product in an amount ranging from 0.1 to 30.0 wt.-%, based on the total weight of the layer, wherein the surface-treated filler material product comprises A) at least one ground calcium carbonate-comprising filler material having a weight median particle size d.sub.50 in the range from 0.5 μm to 3.0 μm, and B) a treatment layer on the surface of the at least one ground calcium carbonate-comprising filler material comprising i. a phosphoric acid ester blend of one or more phosphoric acid mono-ester and salty reaction products thereof and/or one or more phosphoric acid di-ester and salty reaction products thereof, and/or ii. at least one saturated aliphatic linear or branched carboxylic acid and salty reaction products thereof, and/or iii. at least one aliphatic aldehyde and/or salty reaction products thereof, and/or iv. at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C.sub.2 to C.sub.30 in the substituent and/or salty reaction products thereof, and/or v. at least one polydialkylsiloxane, and/or vi. mixtures of the materials according to i. to v., wherein the surface-treated filler material product comprises the treatment layer in an amount of from 0.1 to 2.3 wt.-%, based on the total dry weight of the at least one ground calcium carbonate-comprising filler material.

2. The mono or multi-layer polyester film of claim 1, wherein the at least one polyester and surface-treated filler material product comprising layer of the film comprises the surface-treated filler material product in an amount ranging from 0.5 to 30.0 wt.-%, based on the total weight of the layer.

3. The mono or multi-layer polyester film of claim 1, wherein the at least one polyester is selected from the group consisting of polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyhydroxybutyrate (PHB), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polyethylene furanoate (PEF), bio-based polyesters, polyester-recycling materials and mixtures thereof.

4. The mono or multi-layer polyester film of claim 1, wherein the at least one polyester and surface-treated filler material product comprising layer of the film comprises the at least one polyester in an amount ranging from 70.0 to 99.5 wt. % based on the total weight of the layer.

5. The mono or multi-layer polyester film of claim 1, wherein the at least one ground calcium carbonate-comprising filler material is a wet or dry ground calcium carbonate-comprising filler material.

6. The mono or multi-layer polyester film of claim 1, wherein the at least one ground calcium carbonate-comprising filler material is natural ground calcium carbonate, precipitated calcium carbonate, modified calcium carbonate, surface-treated calcium carbonate, or a mixture thereof.

7. The mono or multi-layer polyester film of claim 1, wherein the at least one ground calcium carbonate-comprising filler material has a) a weight median particle size d.sub.50 from 0.5 μm to 2.5 μm, and/or b) a top cut particle size d.sub.98 of ≤15 μm, and/or c) a fineness such that at least 15 wt. % of all particles have a particle size of <0.5 μm, and/or d) a specific surface area (BET) of from 0.5 to 150 m.sup.2/g, as measured using nitrogen and the BET method according to ISO 9277.

8. The mono or multi-layer polyester film of claim 1, wherein the treatment layer on the surface of the at least one ground calcium carbonate-comprising filler material comprises at least one saturated aliphatic linear or branched carboxylic acid and salty reaction products thereof and/or at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C.sub.2 to C.sub.30 in the substituent and/or salty reaction products thereof.

9. The mono or multi-layer polyester film of claim 1, wherein the surface-treated filler material product comprises the treatment layer in an amount of from 0.2 to 2.0 wt. %, based on the total dry weight of the at least one ground calcium carbonate-comprising filler material.

10. The mono or multi-layer polyester film of claim 1, wherein the at least one polyester and surface-treated filler material product comprising layer of the film further comprises a thermoplastic polymer, the thermoplastic polymer is selected from the group consisting of a polyolefin, a cyclic olefin copolymer (COC), a polyketone, a polysulphone, a fluoropolymer, a polyacetal, an ionomer, an acrylic resin, a polystyrene resin, a polyurethane, a polyamide, a polycarbonate, a polyacrylonitrile and a copolymerized resin and mixtures thereof, which is dispersed in the at least one polyester.

11. The mono or multi-layer polyester film of claim 10, wherein the at least one polyester and surface-treated filler material product comprising layer of the film comprises the thermoplastic polymer in an amount ranging from 0.1 to 29.9 wt. %, based on the total weight of the layer.

12. The mono or multi-layer polyester film of claim 1, wherein the at least one polyester and surface-treated filler material product comprising layer of the film further comprises an inorganic filler material different from the surface-treated filler material product .

13. The mono or multi-layer polyester film of claim 1, wherein the film comprises an additive selected from the group consisting of light stabilizers, anti oxidants, optical brightener, blue dyes, antiblocking agents, white pigments and mixtures thereof.

14. The mono or multi-layer polyester film of claim 1, wherein the film is a cast film, a blown film, or a mono axially oriented polyester film.

15. A process for producing a mono or multi-layer polyester film as defined in claim 1, the process comprising the steps of: a) providing a composition comprising at least one polyester and a surface-treated filler material product, and b) forming a film from the composition of step a), wherein the surface-treated filler material product comprises A) at least one ground calcium carbonate-comprising filler material having a weight median particle size d.sub.50 in the range from 0.5 μm to 3.0 μm, and B) a treatment layer on the surface of the at least one ground calcium carbonate-comprising filler material comprising i. a phosphoric acid ester blend of one or more phosphoric acid mono-ester and salty reaction products thereof and/or one or more phosphoric acid di-ester and salty reaction products thereof, and/or ii. at least one saturated aliphatic linear or branched carboxylic acid and salty reaction products thereof, and/or iii. at least one aliphatic aldehyde and/or salty reaction products thereof, and/or iv. at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C.sub.2 to C.sub.30 in the substituent and/or salty reaction products thereof, and/or v. at least one polydialkylsiloxane, and/or vi. mixtures of the materials according to i. to v., wherein the surface-treated filler material product comprises the treatment layer in an amount of from 0.1 to 2.3 wt.-%, based on the total dry weight of the at least one ground calcium carbonate-comprising filler material.

16. The process of claim 15, wherein the composition provided in step a) is a masterbatch obtained by mixing and/or kneading the at least one polyester and the surface-treated filler material product to form a mixture and continuously pelletizing the obtained mixture or a compound obtained by mixing and/or kneading the at least one polyester and the surface-treated filler material product to form a mixture and continuously pelletizing the obtained mixture.

17. The process of claim 15, wherein the composition provided in step a) is a masterbatch or compound comprising the surface-treated filler material product in an amount of from >30 to 85 wt.-%, based on the total weight of the masterbatch or compound.

18. The process of claim 15, wherein the composition comprising at least one polyester and a surface-treated filler material product of step a) is obtained by adding the surface-treated filler material product to the polycondensation process of the at least one polyester.

19. The process of claim 15, wherein process steps a) and b) are carried out simultaneously.

20. The process of claim 15, wherein the process further comprises a step c) of stretching the film obtained in step b) in only one direction among machine direction (MD) or transverse direction (TD).

21. An article comprising a mono or multi-layer polyester film according to claim 1, wherein the article is selected from the group consisting of packaging products, flexible packaging products, food contact applications, paper or glass coverings, insulating materials, solar, photovoltaic front or backsheets, marine or aviation applications, science, electronic or acoustic applications, displays, wires, cables, radio frequency identifications, flexible circuits, graphic arts, labels, stone paper, bags, packages, boxes, books, booklets, brochures, loyalty cards, business cards, greeting cards, corrugated boards, envelopes, food trays, labeling, games, tags, magazines, signage, billboards, stationary, diaries, pads or notebooks, and holograms, filter products, cosmetic products, household products imaging, recording media, photographic paper, X-ray film or thermal transfer imaging or industrial products, capacitors, release sheets, fiberglass panels, laminating films, hot stamping foils or insulation facing.

22. The mono or multi-layer polyester film according to claim 1, wherein the mono or multi-layer polyester film is suitable for use in packaging products, flexible packaging products, food contact applications, paper or glass coverings, insulating materials, solar, photovoltaic front or backsheets, marine or aviation applications, science, electronic or acoustic applications, displays, wires, cables, radio frequency identifications, flexible circuits, graphic arts, labels, stone paper, bags, packages, boxes, books, booklets, brochures, loyalty cards, business cards, greeting cards, corrugated boards, envelopes, food trays, labeling, games, tags, magazines, signage, billboards, stationary, diaries, pads or notebooks, and holograms, filter products, cosmetic products, household products imaging, recording media, photographic paper, X-ray film or thermal transfer imaging or industrial products, capacitors, release sheets, fiberglass panels, laminating films, hot stamping foils or insulation facing.

Description

EXAMPLES

1 MEASUREMENT METHODS AND MATERIALS

[0368] In the following, measurement methods and materials implemented in the examples are described.

[0369] Intrinsic Viscosity

[0370] The intrinsic viscosity was measured according to the norm DIN ISO 1628-5. The solvents used were phenol/1,2-dichlorobenzene. For the calculation of the value, the calcium carbonate is reduced from the weighed portion.

[0371] Filter Pressure Value

[0372] The filter pressure test was performed on a commercially available Collin Pressure Filter Test Teach-Line FT-E20T-MP-IS (Dr. Collin GmbH, Germany). The test method was performed in agreement with European Standard EN 13900-5 with each 10 of the corresponding polymer compositions (11.2 g effective calcium carbonate per 200 g of final sample, diluent: PET) using a filter screen as described in the mentioned European Standard EN 13900-5 chapter 6.64 (approx. 15 μm mesh size), wherein melt pump was used at 10 rpm, the extruder speed was regulated in order to keep a constant pressure of 20 bar before the melt pump, and wherein the melt 15 temperature was set to 290° C. The quality of the mineral dispersion in the polymer matrix is judged with the classification: good, medium or and low which corresponds the obtained filter pressure values classified as low, medium and high.

[0373] MFR

[0374] The melt flow rate (MFR) is measured on a CEAST Melt Flow modular line instrument from Instron. The melt flow rate is measured according to ISO 1133 (280° C., 2.16 kg load). Measurement of the samples is made using a capillary die having an inner diameter of 2.095 mm and a length of 8.00 mm. The preheating without load is performed for 300 seconds and the measure length is 30 mm. The sheet samples were dried at 130° C. for 2 h before measurement.

[0375] Particle Size

[0376] The particle distribution of the untreated ground calcium carbonate-comprising filler material was measured using a Sedigraph 5100 from the company Micromeritics, USA. The method and the instruments are known to the skilled person and are commonly used to determine grain size of fillers and pigments. The measurement was carried out in an aqueous solution comprising 0.1 wt.-% Na.sub.4P.sub.2O.sub.7. The samples were dispersed using a high speed stirrer and supersonics.

[0377] Specific Surface Area (BET)

[0378] Throughout the present document, the specific surface area (in m.sup.2/g) of the filler material is determined using the BET method (using nitrogen as adsorbing gas), which is well known to the skilled man (ISO 9277:2010).

[0379] Ash Content

[0380] The ash content in [wt.-%] of the masterbatches and films was determined by incineration of a sample in an incineration crucible which is put into an incineration furnace at 570° C. for 2 hours. The ash content was measured as the total amount of remaining inorganic residues.

[0381] Tensile Strain at Break and Tensile Strength at Break

[0382] The tensile strain at break and tensile strength at break are measured on an Allround Z020 traction device from Zwick Roell. The instruments and the measuring method are known to the skilled person. The tensile strain at break and tensile strength at break is measured according to DIN EN ISO 527-2/1B, with a perforce of 0.1 MPa and a speed of 500 mm/min. The test specimen of the present invention have the geometry 1B with the exception that the thickness of the samples is between 0.8±0.1 mm.

[0383] Sheet Thickness

[0384] The sheet thickness was determined using a digital measuring slide Mitutoyo IP 66 (Mitutoyo Europe GmbH, Neuss, Germany). Measured values were reported in mm.

[0385] Density of a Sheet

[0386] The surface density was determined from a test piece whereby a precise area of film (100 mm×100 mm) is cut and weighed on an analytical balance. The density was calculated and reported in [g/m.sup.2].

2 MATERIALS

[0387] CC1 (inventive): Natural ground calcium carbonate, marble based (d.sub.50: 1.6 μm; d.sub.98: 6 μm) surface-treated with 0.7 wt.-% ASA 1 based on the total weight of the natural ground calcium carbonate. BET: 3.5 m.sup.2/g.

[0388] CC2 (inventive): Natural ground calcium carbonate, marble based (d.sub.50: 1.6 μm; d.sub.98: 6 μm) surface-treated with 1.1 wt.-% Fatty acids mixture 2 based on the total weight of the natural ground calcium carbonate. BET: 3.5 m.sup.2/g.

[0389] CC3 (comparative): Natural ground calcium carbonate, marble based (d.sub.50: 1.6 μm; d.sub.98: 6 μm) without surface-treatment. BET: 3.5 m.sup.2/g.

[0390] CC4 (Comparative): Natural ground calcium carbonate (d.sub.50: 5 μm; d.sub.98: 20 μm) surface-treated with 0.5 wt.-% Fatty acids mixture 2 based on the total weight of the natural ground calcium carbonate.

[0391] The methods for the surface-treatment of CC1 to CC2 and CC4 are known in the prior art. For example, the surface treatment can be carried out by using the methods described in EP 2 722 368 A1.

[0392] P1: Polyethylene terephthalate (PET), Lighter C93 PET, commercially available from Equipolymers GmbH, Germany (intrinsic viscosity: 0.8±0.02 dl/g, crystallinity min. 50%, melting point 247° C., according to the technical data sheet provided by the supplier).

[0393] AO1: Antioxidant, Irganox B215, commercially available from BASF SE, Germany.

[0394] ASA 1: Mono-substituted alkenyl succinic anhydride (2,5-Furandione, dihydro-, mono-C.sub.15-20-alkenyl derivs., CAS No. 68784-12-3) is a blend of mainly branched octadecenyl succinic anhydrides (CAS #28777-98-2) and mainly branched hexadecenyl succinic anhydrides (CAS #32072-96-1). More than 80% of the blend is branched.

[0395] Fatty acids mixture 2: Fatty acid mixture 2 is a 1:1 mixture of stearic acid and palmitic acid.

3 EXAMPLES

Example 1—Preparation of Masterbatches

[0396] PET masterbatches comprising a calcium carbonate filler selected from CC1 to CC4 and the polymer P1 were continuously prepared on a lab scale Maris Twin Screw line (TM20Hi-Tech/448D) at 800 rpm. The polymer P1 was pre-dried prior to processing in an oven at 100° C. for 4 hours. The compositions and filler contents of the prepared masterbatches are compiled in Table 1 below. The precise filler content was determined by the ash content.

TABLE-US-00001 TABLE 1 Composition and filler content of prepared masterbatches. PET (P1) Antioxidant Filler content content (AO1) content Masterbatch Filler [wt.-%] [wt.-%] [wt.-%] MB1 (inventive) CC1 50 49.7 0.3 MB2 (inventive) CC2 50 49.7 0.3 MB3 (comparative) CC3 50 49.7 0.3 MB4 (comparative) CC4 50 49.7 0.3

[0397] Masterbatches MB1, MB2 and MB4 could be produced in good quality, whereas the processing of masterbatch MB3 was not possible (Melt pressure too high, output too low).

[0398] Table 2 presents the characterization of the masterbatches.

TABLE-US-00002 TABLE 2 Compounding and characterization of masterbatches. MB1 MB2 MB3 MB4 Masterbatch (inventive) (inventive) (comparative) (comparative) Output [kg/h] 14 14 <5 14 Melt pressure 51 30 >80 (alarm) 28 [bar] Ash content 48.9 49.1 — 49.3 [wt.-%] Intrinsic 0.57 0.50 — 0.51 viscosity [dL/g] Moisture [ppm] 58 83 — 72 MFR (280° C./ 47 >100 — >100 2.16 kg) [g/10 min] FPV (16 g 0.02 0.12 — >10 CaCO.sub.3/14 μm) [bar/g]

Example 2—Preparation of Polyester Sheets Via Masterbatch

[0399] PET films were prepared on a single screw extruder (diameter: 45 mm, screw length: 1330 mm) equipped with a die having a die gap of 0.85 mm and a take-up system, which had temperature controlled chill-rolls (40° C.). Screw speed: 47-52 rpm. Extruder temperatures: 245-250-250-255° C. PET sheets having a thickness of around 800 μm (±50 μm) and a density of about 1100 g/m.sup.2 (±20 g/m.sup.2) were produced. The extruder and die temperatures were consistent throughout the experiment. The die temperature was set at 250° C. (all zones); the line speed was 1.8 m/min (±0.1 m/min). The PET was dried at 110° C. for 4 h and the masterbatches were dried at 70° C. for 12 h before extrusion.

[0400] Concentrations of the PET films are summarized in Table 3.

TABLE-US-00003 TABLE 3 Compositions and properties of prepared sheets Filler content Sheet Sample Masterbatch [wt.-%] 1.1 (inventive) MB1 5 1.2 (inventive) MB1 10 1.3 (inventive) MB1 15 1.4 (inventive) MB1 20 2.2 (inventive) MB2 10 2.4 (inventive) MB2 20 4.4 (comparative) MB4 20

[0401] All polyester films shown in Table 3 are cast films which were produced in good quality with visual good appearance.

[0402] Table 4 and 5 show the melt flow comparison and the compounding data of the prepared polyester films

TABLE-US-00004 TABLE 4 Melt flow comparison of the polyester films MFR (280° C./2.16 kg) Film Sample [g/10 min] 1.4 (inventive) 65.4 2.4 (inventive) 89.5

TABLE-US-00005 TABLE 5 Compounding data of the polyester films Melt Melt Film Film Pressure Temperature thickness density Sheet Sample [bar] [° C.] [mm] [g/m.sup.2] 1.1 (inventive) 76 269 0.8 1101 1.2 (inventive) 73 269 0.81 1114 1.3 (inventive) 65 270 0.76 1088 1.4 (inventive) 61 270 0.76 1094 2.2 (inventive) 64 269 0.78 1101 2.4 (inventive) 58 270 0.75 1095 4.4 (comparative) 60 270 0.76 1105

TABLE-US-00006 TABLE 6 Tensile strength and tensile strain at break Tensile strain at break Tensile strength at break Sheet Sample [%] [N/mm.sup.2] 1.2 (inventive) 787 67.7 1.4 (inventive) 442 35.7 2.2 (inventive) 676 56.1 2.4 (inventive) 199 26.1 4.4 (comparative) <180 <25

[0403] Table 6 shows that the mechanical properties of the prepared polyester films are good. Polyester films comprising CC1 (1.2 and 1.4) show the highest elongation at break and highest strength at break followed by polyester films comprising CC2 (2.2 and 2.4).