LOW NOISE BIODEGRADABLE BREATHABLE FILMS

Abstract

The present invention relates to a breathable film comprising at least one biodegradable polymer, a process for producing the breathable film, the use of a surface-treated filler material product as filler in the breathable film, an article comprising the breathable film as well as the use of the breathable film in hygienic applications, medical applications, healthcare applications, filtration materials, geotextile products, agricultural applications, horticultural applications, clothing, footwear products, baggage products, household applications, industrial applications, packaging applications, building applications, or construction.

Claims

1.-16. (canceled)

17. A breathable film comprising at least one biodegradable polymer and from 35 to 65 wt.-%, based on the total weight of the breathable film, of a surface-treated filler material product, 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 0.1 μm to 7 μm, a top cut particle size d.sub.98 of ≤15 μm, a specific surface area (BET) from 0.5 to 150 m.sup.2/g, as measured using nitrogen and the BET method according to ISO 9277, and a residual total moisture content in the range from 0.05 to 0.3 wt.-%, based on the total dry weight of the at least one ground calcium carbonate-comprising filler material B) a treatment layer on the surface of the at least one ground calcium carbonate-comprising filler material comprising i. 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 C2 to C30 in the substituent and/or salts thereof, and/or ii. at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and/or salts thereof, wherein the surface-treated filler material product comprises the treatment layer in an amount of from 0.1 to 3 wt.-%, based on the total dry weight of the at least one ground calcium carbonate-comprising filler material, and wherein the at least one biodegradable polymer has a tensile E-modulus, measured according to ISO 527-3, of below 2100 MPa.

18. The breathable film of claim 17, wherein the at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and/or salts thereof comprises at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and/or a salt thereof.

19. The breathable film of claim 17, wherein the at least one ground calcium carbonate-comprising filler material is a wet ground calcium carbonate-comprising filler material.

20. The breathable film of claim 17, wherein the at least one biodegradable polymer is selected from the group consisting of polylactic acid, polylactic acid-based polymer, polyhydroxyalkanoates (PHA), polyhydroxybutyrate (PHB), poly-3-hydroxybutyrate (P3HB), polyhydroxyvalerate, polyhydroxybutyrate-polyhydroxyvalerate copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), polybutyrate-adipate-terephthalate (PBAT), polyglyconate, poly(dioxanone), polybutylene succinate (PBS), polycaprolactone (PCL), polycaprolactone-poly(ethylene glycol) copolymer, polycaprolactone-polylactic acid copolymer, polyvinylalcohol (PVA), poly(ethylene succinate) (PES), poly(propylene succinate) (PPS), and mixtures thereof.

21. The breathable film of claim 17, wherein the at least one biodegradable polymer is selected from the group consisting of polylactic acid, polylactic acid-based polymer, polybutyrate-adipate-terephthalate (PBAT), and mixtures thereof.

22. The breathable film of claim 17, wherein the at least one biodegradable polymer is a blend of polybutyrate-adipate-terephthalate (PBAT) and polylactic acid.

23. The breathable film of claim 17, wherein the at least one biodegradable polymer is a blend of polybutyrate-adipate-terephthalate (PBAT) and polylactic acid with a weight ratio ranging from 10:1 to 1:9.

24. The breathable film of claim 17, wherein the breathable film comprises the surface-treated filler material product in an amount from 40 to 65 wt.-%, based on the total weight of the breathable film.

25. The breathable film of claim 17, wherein the breathable film comprises the surface-treated filler material product in an amount from 40 to 60 wt.-%, based on the total weight of the breathable film.

26. The breathable film of claim 17, 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.

27. The breathable film of claim 17, wherein the at least one ground calcium carbonate-comprising filler material is natural ground calcium carbonate.

28. The breathable film of claim 17, wherein the at least one ground calcium carbonate-comprising filler material has a) a weight median particle size d.sub.50 from 0.25 μm to 5 μm, and/or b) a top cut particle size d.sub.98 of ≤12.5 μm, and/or c) a fineness such that at least 5 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 50 m.sup.2/g, as measured using nitrogen and the BET method according to ISO 9277.

29. The breathable film of claim 17, wherein the at least one ground calcium carbonate-comprising filler material has a) a weight median particle size d.sub.50 from 0.6 μm to 2 μm, and/or b) a top cut particle size d.sub.98 of ≤6.5 μm, and/or c) a fineness such that at least 9 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 15 m.sup.2/g, as measured using nitrogen and the BET method according to ISO 9277.

30. The breathable film of claim 17, wherein the at least one ground calcium carbonate-comprising filler material has a fineness such that at least 11 wt.-% of all particles have a particle size of <0.5 μm.

31. The breathable film of claim 17, wherein the at least one ground calcium carbonate-comprising filler material has a residual total moisture content of from 0.05 to 0.2 wt.-%, based on the total dry weight of the at least one ground calcium carbonate-comprising filler material.

32. The breathable film of claim 17, wherein the at least one ground calcium carbonate-comprising filler material has a residual total moisture content of from 0.05 to 0.12 wt.-%, based on the total dry weight of the at least one ground calcium carbonate-comprising filler material.

33. The breathable film of claim 17, wherein the treatment layer on the surface of the at least one ground calcium carbonate-comprising filler material comprises 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 C4 to C18 in the substituent and/or salts thereof.

34. The breathable film of claim 17, wherein the surface-treated filler material product has a moisture pick-up from 0.1 to 1 mg/g, at a temperature of 23° C. (±2° C.).

35. The breathable film of claim 17, wherein the surface-treated filler material product has a moisture pick-up from 0.2 to 0.8 mg/g, at a temperature of 23° C. (±2° C.).

36. The breathable film of claim 17, wherein the film has a basis weight from 8 to 40 g/m.sup.2.

37. The breathable film of claim 17, wherein the film has a basis weight from 20 to 36 g/m.sup.2.

38. A process for producing a breathable film comprising at least one biodegradable polymer and from 35 to 65 wt.-%, based on the total weight of the breathable film, of a surface-treated filler material product, the process comprising the steps of: a) providing a composition comprising at least one biodegradable polymer band from 35 to 65 wt.-%, based on the total weight of the composition, of a surface-treated filler material product, wherein the at least one biodegradable polymer has a tensile E-modulus, measured according to ISO 527-3, of below 2100 MPa, and b) forming a film from the composition of step a), and c) stretching the film obtained in step b) into at least one direction, 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 0.1 μm to 7 μm, a top cut particle size d.sub.98 of ≤15 μm, a specific surface area (BET) from 0.5 to 150 m.sup.2/g, as measured using nitrogen and the BET method according to ISO 9277, and a residual total moisture content in the range from 0.05 to 0.3 wt.-%, based on the total dry weight of the at least one ground calcium carbonate-comprising filler material, and B) a treatment layer on the surface of the at least one ground calcium carbonate-comprising filler material comprising i. 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 C2 to C30 in the substituent and/or salts thereof, and/or ii. at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and/or salts thereof, wherein the surface-treated filler material product comprises the treatment layer in an amount of from 0.1 to 3 wt.-%, based on the total dry weight of the at least one ground calcium carbonate-comprising filler material.

39. The process of claim 38, wherein the at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and/or salts thereof comprises at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and/or a salt thereof.

40. The process of claim 38, wherein the composition provided in step a) is a masterbatch or a compound obtained by mixing and/or kneading the at least one biodegradable polymer and the surface-treated filler material product to form a mixture and continuously pelletizing the obtained mixture.

41. An article comprising a breathable film comprising at least one biodegradable polymer and from 35 to 65 wt.-%, based on the total weight of the breathable film, of a surface-treated filler material product according to claim 1, wherein the article is selected from the group consisting of hygiene products, medical products, healthcare products, filter products, geotextile products, agriculture products, horticulture products, clothing, footwear products, baggage products, household products, industrial products, packaging products, building products, and construction products.

Description

EXAMPLES

1 Measurement Methods and Materials

[0303] In the following, measurement methods and materials implemented in the examples are described.

Particle Size

[0304] The particle distribution of the untreated ground calcium carbonate-comprising filler material was measured using a Sedigraph 5120 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.

Specific Surface Area (BET)

[0305] The specific surface area was measured via the BET method according to ISO 9277:2010 using nitrogen as adsorbing gas on a Micromeritics ASAP 2460 instrument from Micromeritics. The samples were pretreated in vacuum (10-5 bar) by heating at 150° C. for a period of 60 min prior to measurement.

Amount of Surface-Treatment Layer

[0306] The amount of the treatment layer on the calcium carbonate-comprising material is calculated theoretically from the values of the BET of the untreated calcium carbonate-comprising material and the amount of the one or more compound(s) that is/are used for the surface-treatment. It is assumed that 100% of the one or more compound(s) are present as surface treatment layer on the surface of the calcium carbonate-comprising material.

Ash Content

[0307] The ash content in [%] of the masterbatches 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 is measured as the total amount of remaining inorganic residues.

Melt Flow Rate

[0308] The “melt flow rate” was measured on a CEAST Melt Flow modular line instrument from Instron. The instruments and the measuring method are known to the skilled person. The melt flow rate was measured according to DIN EN ISO 1133-1:2011 by using procedure A. The samples were pre-dried for 4 hours at 70° C. and then immediately measured.

Force at Break

[0309] Force at Break Determination was Performed According to ISO 527-3. The Film Specimen Width was of 15 mm and the testing length was 5 cm.

Maximum Elongation at Break

[0310] Elongation at break determination was performed according to ISO 527-3. The film specimen width was of 15 mm and the testing length was 5 cm.

Tensile E-Modulus (Modulus of Elasticity)

[0311] Tensile E-modulus determination was performed according to ISO 527-3. The film specimen width was of 15 mm and the testing length was 5 cm. The E-modulus corresponded to the inclination of the tensile test curve between the points at 0.02% and 2% elongation.

[0312] Likewise, the E-modulus of sheets was measured from samples in machine direction. Tensile E-modulus determination was performed according to ISO 527-3. The sheet specimen width was of 15 mm and the testing length was 5 cm. The E-modulus corresponded to the inclination of the tensile test curve between the points at 0.02% and 2% elongation.

Acoustical Evaluation of the Films

[0313] From each film sample a 10 cm×30 cm large sample (with the long side in machine direction) is prepared by cutting. A lab technician holds the film on both 10 cm long ends and pushes his hands together so that they touch each other than the hands are pushed back again, so that the film is folded and unfolded. This folding and unfolding is done every 2 seconds. Another blindfolded lab technician sits on a chair 1 meter away from the film with his face towards the film. The noise created by the film sample is then evaluated on a scale of 10 (very unpleasant) to 1 (not noticeable).

Noise Level of the Films

[0314] From each film sample, a 14.5 cm×14.5 cm large specimen was prepared by cutting. The film was laid on a stainless steel cylinder with 10 cm height and 7.5 cm outer diameter and 4.8 cm inner diameter. The centre of the film was placed on the centre of the cylinder. The cylinder was mounted in a Zwick materials testing machine Z020. A 7.7 cm long steel pin with 2.3 cm diameter and a rounded end with 2.3 cm diameter was mounted on the moveable upper frame 12 cm above the cylinder in the central axis. A microphone (Norsonic Nor150, resolution: 0.125 seconds, time weighting: fast) was placed horizontally in 9 cm distance from the centre of the top base of the cylinder. The upper frame started to move downwards with the pin with a constant speed of 400 mm/min in such a way that the pin pushed the film specimen into the cylinder. By doing that the film deformed and created noise. The noise was measured by the microphone from the time when the pin touched the film specimen until the film was pushed 7 cm into the cylinder. The energetic mean was determined over this time period and the background noise generated e.g. by the Zwick testing machine, the air condition, and the ventilation was subtracted. The background noise was measured before without film specimen. Each specimen was measured 5 times and the energetic mean was calculated. This value was called the noise of level of the film given in dBA.

Water Vapour Transmission Rate (WVTR)

[0315] The WVTR value of the breathable films was measured with a Lyssy L80-5000 (PBI-Dansensor A/S, Denmark) measuring device according to ASTM E398.

Hydrostatic Pressure Test (Water Column)

[0316] The hydrostatic pressure test has been carried out according to a procedure which is equivalent to AATCC Test Method 127-2013, WSP 80.6 and ISO 811. A film sample (test area=10 cm.sup.2) was mounted to form a cover on the test head reservoir. This film sample was subjected to a standardized water pressure, increased at a constant rate until leakage appears on the outer surface of the film, or water burst occurred as a result of film failure (pressure rate gradient=100 mbar/min.). Water pressure was measured as the hydrostatic head height reached at the first sign of leakage in three separate areas of the film sample or when burst occurs. The head height results were recorded in centimetres or millibars of water pressure on the specimen. A higher value indicated greater resistance to water penetration. The TEXTEST FX-3000, Hydrostatic Head Tester (Textest AG, Switzerland), was used for the hydrostatic pressure measurements.

Moisture Content

[0317] The residual moisture content was determined according to the Coulometric Karl Fischer measurement method, wherein the filler material is heated to 220° C., and the water content released as vapour and isolated using a stream of nitrogen gas (at 100 ml/min) is determined in a Coulometric Karl Fischer unit.

Moisture Pick-Up Susceptibility

[0318] The term “moisture pick-up susceptibility” in the meaning of the present invention refers to the amount of moisture adsorbed on the surface of the mineral filler and can by gravimetrically determined in mg moisture/g of the dry treated mineral filler product after exposure to an atmosphere of 10% of relative humidity, at a temperature of +23° C. (±2° C.) until equilibrium in weight. Then the humidity is changed to 85% relative humidity until the sample is at equilibrium. The difference in weight is defined as the water pick-up. The equipment used was Gintronic Gravitest 6300.

2 Materials

[0319] CC1 (inventive): Natural ground calcium carbonate, commercially available from Omya International AG, Switzerland (d.sub.50: 1.7 μm; d.sub.98: 6 μm, content of particles<0.5 μm=12%), surface-treated with 0.7 wt. % alkenyl succinic anhydride (CAS [68784-12-3], concentration>93%) based on the total weight of the ground calcium carbonate. BET: 3.4 g/m.sup.2, residual moisture content: 0.09 wt.-%, moisture pick-up: 0.58 mg/g.

[0320] CC2 (inventive): Natural ground calcium carbonate, commercially available from Omya International AG, Switzerland (d.sub.50: 0.8 μm; d.sub.98: 3 μm, content of particles<0.5 μm=35%), alkenyl succinic anhydride (CAS [68784-12-3], concentration>93%) based on the total weight of the natural ground calcium carbonate. BET: 8.5 m.sup.2/g, residual moisture content: 0.15 wt.-%, moisture pick-up: 0.08 mg/g

[0321] CC3 (inventive): Natural ground calcium carbonate, commercially available from Omya International AG, Switzerland (d.sub.50: 1.7 μm; d.sub.98: 6 μm, content of particles<0.5 μm=12%), surface-treated with 1.0 wt.-% stearic acid (commercially available from Sigma-Aldrich, Croda) based on the total weight of the natural ground calcium carbonate. BET: 3.4 m.sup.2/g, residual moisture content: 0.09 wt.-%, moisture pick-up: 0.58 mg/g.

[0322] P1: PLA NatureWorks Ingeo 4043D (MFR: 6 g/10 min (190° C., 2.16 kg), density: 1.24 g/cm.sup.3 according to technical data sheet), D isomer content of 3.5 wt.-%, commercially available from NatureWorks, USA

[0323] P2: PBAT BASF ecoflex F Blend C1200 (MVR: 2.5-4.5 ml/10 min (190° C., 2.16 kg); MFR: 2.7-4.9 g/10 min (190° C., 2.16 kg), density: 1.25-1.27 g/cm.sup.3 according to technical data sheet), commercially available from BASF SE, Germany

3 EXAMPLES

Example 1—Preparation of Compounds (CO)

[0324] The Formulations containing 43 wt.-% calcium carbonate CC1 or CC2 were continuously compounded on a Maris™ 20 Hi-Tech lab twin screw extruder with an Econ EW10 underwater pelletizer. The polymers were dried in desiccant based column lab dryers from Motan GmbH at 70° C. for 6 hours. The polymer resins were fed to the main hopper via a loss in weight feeders, another two loss in weight feeders were feeding two side feeders stuffing the carbonates into the extruder barrel. The split of the carbonates was 50:50. The screw speed was 800 rpm. The intake zone was at 15° C. The temperature of the first barrel was 170° C. and 180° C. for the following barrels and the die. The die plate had 2 holes, knife speed was 600 rpm and the cooling water was at 34° C. After 2 hours at ambient temperature the compounded pellets of the polymer composition were put in a sealed plastic bag. The compositions and filler contents of the prepared compounds are compiled in Table 1 below. The precise filler content was determined by the ash content. The results are reported in Table 1.

[0325] The tensile E-modulus of the biodegradeable polymers or polymer blends was measured on (unstretched) cast sheets according to ISO 527-3. The cast sheets were prepared on a Collin Laboratory Film Line (Dr. Collin GmbH, Germany) with a single screw extruder with a diameter of 30 mm. If the polymer blend comprised more than one biodegradeable polymers, the polymers were preblended with a tumbling mixer from Engelsman AG. The biodegradable polymers were then fed into the hopper of the extruder. The sheets were extruded with a 300 mm wide slot die and a take-up system, which had temperature controlled rolls. The slot die had an opening of 230 μm. The distance from the slot die to the gap of the first 2 cooling rolls was 20 mm. The gap between these rolls was 200 μm. The rolls were kept at appropriate low temperature to cool down the melt and form a sheet. In the examples 60° C. adjusted. The screw speed was adjusted to fill the gap without creating a melt bank. By that 200 μm thick sheets with low orientation were extruded. The extruder and die temperatures were consistent throughout the experiment. The die and barrel temperature was set at 190° C., other polymers may need different temperatures according the recommendation of the supplier. The line speed was 0.5 m/min. The tensile E-modulus was measured from samples in machine direction. Tensile E-modulus determination of the sheets was performed according to ISO 527-3. The sheet specimen width was of 15 mm and the testing length was 5 cm. The E-modulus corresponded to the inclination of the tensile test curve between the points at 0.02% and 2% elongation. The results are reported in Table 1.

TABLE-US-00001 TABLE 1 Compositions and properties of prepared compounds. Tensile E- modulus of Ash polymer or P1 P2 content polymer blends Compound Filler [wt.-%] [wt.-%] [wt.-%] [MPa] CO1 (comparative) CC1 57 — 42.5 3200 CO2 (inventive) CC1 34.2 22.8 42.1 2000 CO3 (inventive) CC1 22.8 34.2 41.8 1350 CO4 (inventive) CC1 11.8 45.6 41.6 600 CO5 (inventive) CC1 — 57 41.4 40 CO6 (comparative) CC2 57 — 40.4 3200

[0326] The results shown in Table 1 confirm that compounds with good quality could be produced.

Example 2—Preparation of Breathable Films

[0327] Breathable films were produced with a pilot-extrusion cast-film line with integrated MDO-II unit (Dr. Collin GmbH, Germany) the extruder temperature settings were 175° C.-185° C.-200° C.-200° C.-200° C. for the barrels and 210° C. for the die. The rotation speed of the extruder was 35 rpm. Compounds of Example 1 were used to produce the stretched breathable films. All compounds were again dried at 70° C. for 6 hours. The initial film speed of the cast roll was at 5 m/min. The cast roll temperature was at 45° C. The speed difference in % between the two rolls at each of the two stretching gaps units was increased until a homogeneous stretched and uniform film was achieved. The stretching settings are given in table 2. The preheating roll was at 55° C. the slow and fast draw rolls were at 70° C., the annealing rolls were at 50° C.

[0328] The film quality of the obtained breathable films was inspected visually and the films were tested regarding their water vapour transmission rate (WVTR) and their hydrostatic pressure. The results are shown in Table 2 below.

TABLE-US-00002 TABLE 2 Compositions and properties of prepared breathable films. Hydro- Stretching Basis WVTR static Noise settings weight Film [g/(m.sup.2 × pressure level Sample gap1/gap2 Compound [g/m.sup.2] quality day)] [mbar] Noise [dBA] 1 (comparative) 70%/70% CO1 28.6 ok 1243 746 6 66.6 2 (inventive) 70%/70% CO2 28.6 ok 1078 408 5 59.8 3 (inventive) 70%/70% CO3 31.4 ok 804 442 4 56.7 4 (inventive) 70%/70% CO4 31.9 ok 1342 293 3 51.3 5 (inventive) 70%/70% CO5 33.5 ok 1024 336 3 45.3 6 (comparative) 70%/70% CO6 29.9 ok 1214 616 6 63.0 7 (comparative) 60%/60% CO6 36.4 ok 1212 >1000 7 nm* *nm = not measured

[0329] The results shown in Table 2 confirm that the breathable films have good quality and membrane properties. Samples 1, 2, 6 and 7 created rather unpleasant noise when folding the films. In applications like in back sheets for baby diapers this is an important criteria as such noise is created every time the baby is moving. Therefore these samples would not be accepted by consumers in such applications. Samples 3, 4 and 5 show that by increasing the content of the polymer P2 the noise level can be reduced significantly to a much more pleasant noise and would allow the application in diaper back sheets and other noise sensitive applications.

[0330] The mechanical properties, such as the force at break, E-modulus as well as the elongation at break in machine and cross direction, of the obtained breathable films are outlined in Tables 3 and 4. The results prove that the mechanical properties are on a good level for most hygiene film applications.

TABLE-US-00003 TABLE 3 Compositions and mechanical properties of prepared breathable films. Film samples taken in machine direction (MD). Max. Force at Elongation break E-modulus at break Sample Compound [N] - MD [MPa] - MD [%] - MD 1(comparative) CO1 29.5 1730 23.5 2 (inventive) CO2 24.5 1330 31.4 3 (inventive) CO3 23.8 1110 43.5 4 (inventive) CO4 21.1 741 55.9 5 (inventive) CO5 14.2 196 115.8 6 (comparative) CO6 28.5 1980 26.5 7 (comparative) CO6 37.9 2330 7.9

TABLE-US-00004 TABLE 4 Compositions and mechanical properties of prepared breathable films. Film samples taken in cross direction (CD). Max. Force at Elongation break E-modulus at break Sample Compound [N] - CD [MPa] - CD [%] - CD 1 (comparative) CO1 5.8 500 15.2 2 (inventive) CO2 4.1 405 23.9 3 (inventive) CO3 3.7 363 48 4 (inventive) CO4 3.2 230 318.5 5 (inventive) CO5 4.0 126 537.5 6 (comparative) CO6 4.8 459 9.8 7(comparative) CO6 6.1 561 11.3