US-12617934-B2 - Low noise biodegradable breathable films

US12617934B2US 12617934 B2US12617934 B2US 12617934B2US-12617934-B2

Abstract

Inventors

Michael Knerr

Assignees

OMYA INTERNATIONAL AG

Dates

Publication Date: 20260505
Application Date: 20210702
Priority Date: 20200703

Claims (20)

1 . 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 50 in the range from 0.1 μm to 7 μm, a top cut particle size d 98 of ≤15 μm, a specific surface area (BET) from 0.5 to 150 m 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 any linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from C2 to C30 in the substituent and/or salts of the at least one mono-substituted succinic anhydride, 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 2,100 MPa.
2 . The breathable film of claim 1 , 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.
3 . The breathable film of claim 1 , wherein the at least one ground calcium carbonate-comprising filler material is a wet ground calcium carbonate-comprising filler material.
4 . The breathable film of claim 1 , 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.
5 . The breathable film of claim 1 , 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.
6 . The breathable film of claim 1 , wherein the at least one biodegradable polymer is a blend of polybutyrate-adipate-terephthalate (PBAT) and polylactic acid.
7 . The breathable film of claim 1 , 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.
8 . The breathable film of claim 1 , 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.
9 . The breathable film of claim 1 , 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.
10 . The breathable 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.
11 . The breathable film of claim 1 , wherein the at least one ground calcium carbonate-comprising filler material is natural ground calcium carbonate.
12 . The breathable film of claim 1 , wherein the at least one ground calcium carbonate-comprising filler material has a) a weight median particle size d 50 from 0.25 μm to 5 μm, and/or b) a top cut particle size d 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 2/ g, as measured using nitrogen and the BET method according to ISO 9277.
13 . The breathable film of claim 1 , wherein the at least one ground calcium carbonate-comprising filler material has a) a weight median particle size d 50 from 0.6 μm to 2 μm, and/or b) a top cut particle size d 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 2 /g, as measured using nitrogen and the BET method according to ISO 9277.
14 . The breathable film of claim 1 , 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.
15 . The breathable film of claim 1 , 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.
16 . The breathable film of claim 1 , 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.
17 . The breathable 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 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 C4 to C18 in the substituent and/or salts of the at least one mono-substituted succinic anhydride.
18 . The breathable film of claim 1 , 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.
19 . The breathable film of claim 1 , 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.
20 . The breathable film of claim 1 , wherein the film has a basis weight from 8 to 40 g/m 2 .

Description

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. The first breathable films for hygiene products were developed as early as 1983 in Japan. Production of breathable films began in the USA in the mid 1990s and later in Europe, where they rapidly commanded a large market share. Currently, breathable films have two main fields of application: personal hygiene products, such as infant diapers, feminine hygiene pads (napkins, panty liners) or adult incontinence products, and construction industry, such as under-roofing membranes, house wraps or wall coverings. However, the specific permeability properties of these films also have uses in other industries, such as disposable clothing in medical and industrial applications. Breathable films typically comprise a blend of thermoplastic polymers and an inorganic filler such as calcium carbonate and are produced by forming a film from said blend by casting or blowing with subsequent stretching of the film. The stretching process delaminates the polymer from the surface of the inorganic filler particles, which produces micropores, often referred to as “voids” in the film's cross section, which allows the passage of water vapour during end-use. However, such films are consumed in multitude and are disposed after use such that it is desirable to use compostable or biodegradable sheets for environmental reasons. Therefore, is desired to produce films which are compostable or biodegradable but without compromising the performance. Such films are well known in the art. For example, US20020098341 refers to a biodegradable breathable film formed by mixing any biodegradable polymer with particles and subsequent stretching. US20100068484 refers to a breathable biodegradable film with two kinds of filler particles of different size. CN102250455 refers to a breathable biodegradable film made from polylactic acid (PLA) and 40-60% calcium carbonate and 1-10% of other auxiliary agents. U.S. Pat. No. 6,660,211 refers to a biodegradable breathable film made with biodegradable film and water soluble polymer which dissolves and creates porosity. US20050112363 refers to a biodegradable breathable film comprising a biodegradable polyester, a biodegradable copolyester and filler. U.S. Pat. No. 8,466,337 refers to a biodegradable breathable film comprising thermoplastic starch, PBAT and filler. However, such biodegradable breathable films typically based on polylactic acid (PLA) provide good mechanical properties but create unpleasant noise in the end product. This would be irritating for the end consumer and is thus not wanted. Other soft polymers such as vinyl acetate copolymers or PBS do not create such noise but have low stiffness, which is then difficult to handle in the film processing, e.g. in the printing and lamination step. Furthermore, it is desired that the film allows sufficient vapour transmission properties, i.e. is breathable, as the non-evaporation of moisture may lead to skin irritations when used e.g. in hygiene products such as diapers. Thus, the provision of biodegradable breathable films providing low noise and having good mechanical properties remains of interest to the skilled man. Accordingly, it is an object of the present invention to provide a breathable film which is biodegradable and provides low noise. It would also be desirable to provide a breathable film having good mechanical properties such as force at break, elongation at break or modulus of elasticity. It would also be desirable to provide a breathable film which retains good breathability and low film defect levels. It would also be desirable to provide a breathable film with good processing characteristics such as low die build-up properties. The foregoing objects and other objects are solved by the subject-matter as defined herein in the independent claims. Advantageous embodiments of the present invention are defined herein and also in the corresponding sub-claims. According to one aspect of the present invention, a breathable film comprising at least one biodegradable polymer is provided. The breathable film comprises 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 havinga weight m