WO1998004626A2

WO1998004626A2 - Biaxially stretched, biodegradable and compostable foil

Info

Publication number: WO1998004626A2
Application number: PCT/EP1997/003744
Authority: WO
Inventors: Thomas Gernot; Hermann Benkhoff; Helmut Wagner; Rainer Brandt; Gunter Weber
Original assignee: Wolff Walsrode Ag
Priority date: 1996-07-26
Filing date: 1997-07-14
Publication date: 1998-02-05
Also published as: AU731849B2; CA2261971A1; EP0914378A2; BR9710576A; JP2001500174A; DE19630235A1; KR20000029566A; AU3543597A; IL128213A0; WO1998004626A3; CN1226273A

Abstract

A foil with a biaxial orientation consists of one or several polymers which are all biologically degradable and compostable, and possibly of additional additives for improving its processability.

Description

BIAXIAL STRETCHED, BIODEGRADABLE AND COMPOSTABLE FILM

The invention relates to a biaxially stretched, biodegradable and compostable film.

It is known that certain polymeric materials can undergo biodegradation. Mainly materials to be mentioned here are those that are obtained from naturally occurring polymers directly or after modification, for example polyhydroxyalkanoates such as polyhydroxybutyrate, plastic

Celluloses, cellulose esters, plastic starches, chitosan and pullulan. A targeted modification of the polymer composition or the stucts, as is desirable from the part of the polymer application, is difficult and often only possible to a very limited extent due to the natural synthesis process.

On the other hand, many synthetic polymers are not attacked by microorganisms or only very slowly. Mainly synthetic polymers that contain heteroatoms in the main chain are considered to be potentially biodegradable. An important class within these materials are the polyesters. Synthetic raw materials that only contain aliphatic monomers have a relatively good biodegradability, but can only be used to a very limited extent due to their material properties; see Witt et al. in Macrom. Che. Phys., 195 (1994) pp. 793-802. Aromatic polyesters, on the other hand, show significantly deteriorated biodegradability with good material properties.

Various biodegradable polymers have been known recently (see DE 44 32 161). These have the property that they are easy to process thermoplastically and, on the other hand, are biodegradable. H. their entire polymer chain is broken down by microorganisms (bacteria and fungi) via enzymes and completely broken down into carbon dioxide, water and biomass. A corresponding test in a natural environment under the influence of microorganisms, as u. a. prevails in a compost, is u. a. in the

DIΝ 54 900 given. Due to their thermoplastic behavior, these biodegradable materials can be processed into semi-finished products such as cast or blown films. However, the use of these semi-finished products is very limited. On the one hand, these films are characterized by poor mechanical properties and on the other hand, the physical barrier properties with regard to water vapor and gases are very poor in comparison to films made from typical but not biodegradable plastics such as polyethylene, polypropylene or polyamide.

The object of the present invention is to produce a biodegradable and compostable film with improved mechanical and optical properties as well as higher barrier properties. This goal is achieved by subjecting a biodegradable and compostable polymer or a mixture of several biodegradable and compostable polymers to a biaxial orientation. For the purposes of the invention, the terms "biodegradable and compostable polymers or films" are understood to mean goods which are tested for "biodegradability" in accordance with the test according to DIN 54 900 from the 1996 draft.

It was surprising for the inventor that these biodegradable polymers can also be oriented biaxially in addition to thermoplastic processing, and that this orientation process can significantly improve the physical properties of the film. This includes a significant increase in strength, an improvement in the optical properties and an increased barrier effect of the film.

The invention relates to a film which has a biaxial orientation and consists of one or more all biodegradable and compostable polymers and possibly contains additional additives to improve processability. The biaxial orientation takes place with amorphous thermoplastics in temperature ranges above the glass transition temperature as well as with partially crystalline thermoplastics below the crystallite melting temperature.

The invention also relates to the use of certain biodegradable and compostable polymers or a mixture of these polymers for the production of the film.

Suitable polymers are:

Aliphatic and partially aromatic polyester A) linear bifunctional alcohols, for example ethylene glycol, hexanediol or preferably butanediol, and / or, if appropriate, cyclophatic bifunctional alcohols, for example cyclohexanediol, and additionally, if appropriate, small amounts of high-functional alcohols, for example 1,2,3-propanetriol or neopentyl glycol, as well as from linear bifunctional acids, for example succinic acid or adipic acid, and / or optionally cycloaliphatic bifunctional acids, for example cyclohexanedicarboxylic acid, and / or optionally aromatic bifunctional acids, for example terephthalic acid or isophthalic acid or naphthalenedicarboxylic acid, and additionally optionally small amounts of high functional acid, for example small amounts , or

B) from acid- and alcohol-functionalized building blocks, for example hydroxybutyric acid or hydroxyvaleric acid, or their derivatives, for example ε-caprolactone,

or a mixture or a copolymer of A and B

the aromatic acids make up no more than 50% by weight based on all acids

The acids can also be used in the form of derivatives, for example acid chlorides or esters

Aliphatic polyester urethanes

C) an ester fraction from linear bifunctional alcohols, for example ethylene glycol, butanediol, hexanediol, preferably butanediol, and / or optionally cycloaliphatic bifunctional alcohols, for example cyclohexanedimethanol, and additionally, if appropriate, small amounts of high-functionality alcohols, for example 1,2,3-propanetriol or neopentyl glycol, and from linear bifunctional acids, for example succinic acid or adipic acid, and / or optionally cycloaliphatic and / or aromatic bifunctional acids, for example cyclohexanedicarboxylic acid and terephthalic acid, and additionally if necessary, small amounts of highly functional acids, for example trimellitic acid, or

D) an ester fraction from acid- and alcohol-functionalized building blocks, for example hydroxybutyric acid and hydroxyvaleric acid, or their derivatives, for example ε-caprolactone,

or a mixture or a copolymer of C) and D) and

E) from the reaction product of C) and / or D) with aliphatic and / or cycloaliphatic bifunctional isocyanates and additionally optionally higher-functional isocyanates, for example tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and optionally also with linear and / or cycloaliphatic bifunctional and / or higher functions Alcohols, for example ethylene glycol, butanediol, hexanediol, neopentylglucol, cyclohexanedimethanol,

wherein the ester content C) and / or D) is at least 75% by weight based on the sum of C), D) and E)

Aliphatic-aromatic polyester carbonates

F) an ester fraction from linear bifunctional alcohols, for example ethylene glycol, butanediol, hexanediol, preferably butanediol, and / or cycloaliphatic bifunctional alcohols, for example cyclohexanedimethanol, and additionally, if appropriate, small amounts of highly functional alcohols, for example 1,2,3-propanetriol or neopentyl glycol, as well as from linear bifunctional acids, for example succinic acid or adipic acid, and / or optionally cycloaliphatic bifunctional acids, for example cyclohexanedicarboxylic acid, and additionally optionally small amounts of highly functional acids, for example

Trimellitic acid, or

G) from an ester fraction from acid and alcohol-functionalized building blocks, for example hydroxybutyric acid or hydroxyvaleric acid, or their derivatives, for example ε-caprolactone, or a mixture or a copolymer of F) and G) and

H) a carbonate component which is produced from aromatic bifunctional phenols, preferably bisphenol A and carbonate donors, for example phosgene,

wherein the ester fraction F) and / or G) is at least 70% by weight based on the

Sum of F), G) and H)

Aliphatic polyester amides

I) an ester fraction from linear and / or cycloaliphatic bifunctional

Alcohols, for example ethylene glycol, hexanediol or butanediol, preferably butanediol or cyclohexanedimethanol, and additionally, if appropriate, small amounts of high-functional alcohols, for example 1,2,3-propanetriol or neopentylgycol, and from linear and / or cycloaliphatic bifunctional acids, for example succinic acid, adipic acid, Cyclohexanedicarboxylic acid, preferably adipic acid and additional, if necessary, small amounts of highly functional acids, for example

Trimellitic acid, or

K) from an ester fraction from acid- and alcohol-functionalized building blocks, for example hydroxybutyric acid or hydroxyvaleric acid, or their derivatives, for example ε-caprolactone,

or a mixture or a copolymer of I) and K) and

L) an amide component from linear and / or cycloaliphatic bifunctional and additionally optionally small amounts of higher functional amines, for example tetramethylene diamine, hexamethylene diamine, isophorone diamine, and from linear and / or cycloaliphatic bifunctional acids and additionally optionally small amounts of highly functional acids, for example succinic acid or adipic acid, or

M) from an amide portion of acid- and amine-functionalized building blocks, preferably ω-laurolactam and particularly preferably ε-caprolactam, or a mixture of L) and M) as an amide component,

wherein the ester content I) and / or K) is at least 30% by weight based on the sum of I), K), L) and M).

The biodegradable and compostable raw materials according to the invention can be processed with processing aids and additives, such as

Nucleating agents (for example 1,5-naphthalene disodium sulfonate), stabilizers or lubricants.

The invention furthermore relates to the use of a certain class of materials of the biodegradable and compostable polymers for the production of the film, which material is polyester amide. The film according to the invention can be produced from a polyester amide or a mixture of different polyester amides.

The invention also relates to a method for producing the film according to the invention. This method is characterized in that the biodegradable and compostable material (s) are first used

Exposure to heat and shear, this melt discharged in a tool, cooled to solidification, then tempered to temperatures below the crystallite melt temperature in the case of semi-crystalline materials and above the glass transition temperature in the case of amorphous materials, and then stretched one or more times biaxially. After the or the

The film can optionally be fixed in each of the drawing stages. After the stretching processes and the possibly prevailing fixing stages, the film thus produced can possibly be surface-pretreated in-line. The pretreatment can be carried out with a corona, a flame, a plasma or an oxidative substance or mixture of substances such that a

There is an increase in the surface tension on the film.

The invention also relates to a method for stretching the film. The biaxial stretching can be carried out in the simultaneous stretching process or in the two-stage sequential process, where both first longitudinal and then transverse stretching as well as first transverse and then longitudinal stretching, or in the three-stage sequential process, whereby both first longitudinal, then transverse and finally longitudinal stretching as also stretched crosswise first, then lengthways and finally crosswise can be done, or in the four-step sequential process, whereby both first longitudinally, then laterally, then longitudinally and finally laterally stretched as well as first laterally, then longitudinally, then laterally and finally laterly, each individual stretching can be done if necessary, attach a fixation of the film. The individual stretching in the longitudinal and transverse directions can be carried out in one or more stages

In a preferred form of the film according to the invention, the biaxial stretching is characterized in that it is a sequential process which begins with the elongation

In an even more preferred form of the film according to the invention is the biaxial one

Drawing characterized in that the total stretching ratio in the longitudinal direction is 1 1.5 to 1 10 and the total stretching ratio in the transverse direction is 1 2 to 1 20

In an even more preferred form of the film according to the invention, the biaxial stretching is characterized in that the total stretching ratio in the longitudinal direction is 1 2.8 to 1 8 and the total stretching ratio in the transverse direction is 1 3.8 to 1 15

In an even more preferred form of the film according to the invention, it has a thickness which is less than 500 μm

In an even more preferred form of the film according to the invention, it has a thickness which is less than 80 μm

The invention also relates to the use of the film according to the invention. This film is used as a solo film in pretreated or untreated as well as in printed or unprinted form for packaging in the areas of food and non-food, or as a sofa film in pretreated or untreated form for greenhouse covers or Mulch foals in the fields of horticulture or agriculture or sacked for storage and transport of goods, e.g. biomull, or as a solo film in pretreated or untreated form for protective and separating functions in connection with cosmetics and hygiene articles, for example for baby diapers or sanitary napkins, or as a solo film in pretreated or untreated form for surface protection or surface finishing in the area of cardboard, paper and letter window lamination or as a refined film that can be used in pretreated or untreated as well as printed or unprinted form as well as provided with adhesive as a label or adhesive strip. To improve pressure adhesion or adhesiveness, the film surface can be pretreated with a corona, a flame, a plasma or another oxidative substance or mixture of substances during manufacture and / or subsequently during further processing, so that there is an increase in the surface tension.

The invention also relates to the use of the film according to the invention in a film composite. The other films in the composite can also be biodegradable and compostable films or non-degradable films. The adhesives used can also belong to the biodegradable and compostable raw materials as well as normal non-degradable systems.

In a particularly preferred form of use of this film according to the invention, only substances which are biodegradable and compostable are used to produce a film composite, so that the overall composite is also biodegradable and compostable.

The invention furthermore relates to the use of the film according to the invention as a starting material for the production of a bag, which releases its contents after the disintegration by the biodegradation process. The bag can be produced by gluing and sealing the film and can both be closed and have an opening with a corresponding closure or connection.

The invention also relates to the use of the film or composites according to the invention as a starting material for the production of a packaging or separating or surface protection film with very high water vapor permeability by piercing this film with a cold or tempered needle roller. The purpose of this film is the packaging of moisture-releasing goods, for example bread or various types of vegetables, or as a separating and protective film in the hygiene area. example 1

A biodegradable polyester amide with a melt viscosity of 250 Pas at 190 ° C (measured according to DIN 54 81 1 - B) and a melting point of 125 ° C measured according to ISO 3146 / C2 was stretched biaxially under the following process parameters. The maximum extrusion temperature was 205 ° C

Accordingly, the extruder temperature zones were heated to a maximum of 182 ° C and the mold to a maximum of 205 ° C. The melt was cooled as a flat film on a cooling roll mill at roll temperatures of 20 ° C. A solid thick film was formed, which in the next process step was heated to stretching temperature by tempering rolls at temperatures of 65 ° C. The actual stretching rollers were operated at a temperature of 70 ° C. The flat film was first stretched in two stages in the longitudinal direction, once by a ratio of 1: 1.5 and then by a ratio of 1: 2.5. This resulted in a total stretch ratio of 1.75 in the longitudinal direction. The post-heating rollers over which the film then ran had a temperature of 85 ° C.

Preheating zones of the transverse stretching oven were heated to 100 ° C. The temperature in the actual transverse stretching section was 95 ° C. Here the film was stretched by the ratio 1 5 in the transverse direction. This resulted in a calculated area ratio of 1. 18.75 After the transverse stretching, the film was fixed at a temperature of 105 ° C. The production speed at the outlet of the

Lateral stretch was 32.0 m / min. A film with a thickness of 46 μm could be produced.

Example 2

The same biodegradable polyesteramide from Example 1 was biaxially oriented under the process conditions described in Example 1

Processed film By lowering the extrusion speed, a film with a thickness of 24 μm was produced in this case

Comparative Example 1

The same biodegradable polyester amide from Examples 1 and 2 was processed on a film blowing system. The melt temperature measured on

The nozzle outlet was 152 ° C. The cylinder temperature of the extruder was regulated to a maximum of 145 ° C and the nozzle to 145 ° C. The diameter of the used Nozzle was 400 mm. The lying width of the finished film was 950 mm. It was produced with a take-off speed of 6.3 m / min. The thickness of the blown film was 30 μm.

The following physical properties and compostability were measured on the manufactured samples as follows

Mechanical properties:

The mechanical parameters tensile strength and elongation at break were determined in the longitudinal and transverse directions in accordance with DIN 53 455 on the samples. The modulus of elasticity in the longitudinal and transverse directions was determined in accordance with DIN 53 457. The thickness of the individual samples was determined according to DIN 53 370

Determination of the puncture force and the puncture path were analyzed after the biaxial puncture test according to DIN 53 373

Permeation

The oxygen permeability of the samples was determined in accordance with DIN 53 380 at a test temperature of 23 ° C and 0% relative humidity. The water vapor permeability was carried out in accordance with DIN 53 122 at a test temperature of 23 ° C and 85% relative humidity

Optics

The optical properties of the films were the surface gloss in accordance with DIN 67 530 at a test angle of 20 ° and the haze in accordance with

ASTM D 1003 determined. The gloss measurement was carried out on both sides of the film. From the values determined here, a mean was subsequently formed and reported as the result

Compostability The compostability was carried out in accordance with the test specification of the DIN standard draft DIN 54 900 part 3 from 1996. Based on the test results, the film samples were classified into the appropriate class in accordance with the DIN specifications

The results of the tests on the samples from Examples 1 and 2 and Comparative Example 1 are shown in Table 1 Table 1

Example 1 Example 2 Comparative Example 1

Mechanical properties

Thickness [μm] 46 24 30

Young's modulus along [MPa] 226 252 296

E-module transverse [MPa] 292 306 392

Longitudinal tensile strength [MPa] 90 91 61

Tear strength across [MPa] 109 111 50

Elongation at break along [%] 224 186 388

Elongation at break across [%] 1 1 1 75 639

Puncture force [N] 227 151 47

Piercing distance [mm] 18 16 38

Permeation

Oxygen 23 ° C / 0% r. F. 384 690 1270 [cm ^Λ 3 / m / d / bar]

Water vapor 23 ° C / 85% r. F. 200 300 360 [g / m ^Λ 2 / d]

Optics

Gloss 110 110 3.1

Turbidity [%] 14 3.3 38.9

Compostability

Biodegradability yes yes yes

Claims

claims

1 film, characterized in that it has a biaxial orientation and that it consists of one or more all biodegradable and compostable polymers and possibly contains additional additives to improve processability

2 film, according to claim 1, characterized in that it is in the or the biodegradable polymers to aliphatic and partially aromatic polyester

aliphatic and partially aromatic polyester

A) linear bifunctional alcohols and / or optionally cycloaliphatic bifunctional alcohols and additionally optionally small amounts of highly functional alcohols and from linear bifunctional acids and / or optionally cycloaliphatic bifunctional acids and / or optionally aromatic bifunctional acids and additionally optionally small amounts of highly functional acids or

B) from acid and alcohol functionalized building blocks or their derivatives

or a mixture or a copolymer of A) and B),

wherein the aromatic acids make up no more than 50% by weight based on all acids, or from

aliphatic polyester urethanes

C) an ester fraction of linear bifunctional alcohols and / or optionally cycloaliphatic bifunctional alcohols and additionally optionally small amounts of more highly functional ones

Alcohols and from linear bifunctional acids and / or optionally cycloaliphatic and / or aromatic bifunctional tional acids and in addition, if necessary, small amounts of highly functional acids or

D) from an ester portion of acid and alcohol functionalized building blocks or their derivatives

or a mixture or a copolymer of C) and D) and

E) from the reaction product of C) and / or D) with aliphatic and / or cycloaliphatic bifunctional isocyanates and additionally optionally higher-functional isocyanates and optionally additionally with linear and / or cycloaliphatic bifunctional and / or higher-functional alcohols,

wherein the ester fraction C) and / or D) is at least 75% by weight based on the sum of C), D) and E), or from

aliphatic-aromatic polyester carbonates

F) an ester fraction from linear bifunctional alcohols and / or cycloaliphatic bifunctional alcohols and additionally, if appropriate, small amounts of high-functionality alcohols and from linear bifunctional acids and / or optionally cycloaliphatic bifunctional acids and additionally optionally small amounts of highly functional acids or

G) from an ester portion of acid and alcohol functionalized building blocks or their derivatives

or a mixture or a copolymer of F) and G) and

H) a carbonate fraction which is produced from aromatic bifunctional phenols and carbonate donors,

wherein the ester fraction F) and / or G) is at least 70% by weight based on the sum of F), G) and H), or from aliphatic polyester amides

1) an ester fraction from linear and / or cycloaliphatic bifunctional alcohols and additionally, if appropriate, small amounts of high-functionality alcohols and from linear and / or cycloaliphatic bifunctional acids and additional, if appropriate, small amounts of high-functionality acids or

K) from an ester portion of acid and alcohol functionalized building blocks or their derivatives

or a mixture or a copolymer of I) and K) and

L) an amide content of linear and / or cycloaliphatic bifunctional and additionally optionally small amounts of highly functional amines and of linear and / or cycloaliphatic bifunctional and additionally optionally small amounts of highly functional acids or

M) from an amide portion of acid and amine functionalized building blocks

or a mixture of L) and M) as an amide component,

wherein the ester content I) and / or K) is at least 30% by weight based on the sum of I), K), L) and M)

3 film, according to claims 1 and 2, characterized in that it is in the biodegradable or compostable polymers or polyester amides

4 film according to claims 1 to 3, characterized in that the or the biodegradable and compostable materials are first digested by the action of heat and shear, this melt in one

Tool removed, cooled until solidification, then at temperatures below the melting point of partially solid materials and above amber materials at amorphous materials Transition temperatures tempered and then one or more biaxially stretched and possibly fixed after the individual stretching or and possibly surface pretreated after these stretching and fixing processes

5. Film according to claims 1 to 4, characterized in that the biaxial

Stretching in the simultaneous stretching process or in the two-stage sequential process, where both longitudinal and then transverse stretching can be carried out first, as well as transverse and then slow stretching first, or in the three-stage sequential process, where both longitudinal, then transverse and finally slow stretching and first transverse stretching -, then can be stretched longitudinally and finally, or in the four-step sequential process, whereby both first longitudinally, then laterally, then longitudinally and finally laterally stretched, and first laterally, then longitudinally, then laterally and finally later stretched , takes place and possibly a fixation of the film can follow every single stretching

6 film according to claims 1 to 5, characterized in that the biaxial stretching is carried out in a sequential process starting with the longitudinal stretching

7 film according to claims 1 to 6, characterized in that the total stretching ratio in the longitudinal direction 1. 1.5 to 1 10 and the total stretch ratio in the transverse direction is 1 2 to 1 20

8 film according to claims 1 to 7, characterized in that the total stretching ratio in the longitudinal direction 1 is 2.8 to 1 ^• 8 and the total stretching ratio in the transverse direction is 1 ^• 3.8 to 1 15

9 film according to claims 1 to 8, characterized in that the film thickness is less than 500 microns

10 film according to claims 1 to 9, characterized in that the film thickness is less than 80 microns

1 1 Use of the film according to claims 1 to 10 as a solo film in pretreated or untreated as well as in printed or unprinted Form for packaging in the areas of food or non-food or as a solo film in pretreated or untreated form for greenhouse covers or mulch films in the areas of horticulture or agriculture or refined into sacks for the storage and transport of goods or as a solo film in pretreated or untreated as well as printed or unprinted form for protective and separating functions in connection with cosmetics and hygiene articles or as a solo film in pretreated or untreated form for surface protection or surface finishing in the area of cardboard, paper and letter window lamination or as a refined film in pretreated or untreated as well as in printed or unprinted form and provided with adhesive as a label or adhesive strip.

Use of the film according to claims 1 to 10 for the production of composites and / or laminates from the same or other biodegradable and compostable films or with other non-biodegradable film types, the adhesives used not necessarily being biodegradable and compostable

Use of the film according to claim 12, characterized in that all the films and adhesives used in the composite and / or laminate are biodegradable and compostable, and thus the composite or the laminate itself is also biodegradable and compostable

Use of the film according to claims 1 to 10 and 12 and 13, characterized in that a bag is formed from this film or the composite or the laminate, which releases its contents after the disintegration by the biological degradation process.

Use of the film according to Claims 1 to 10 as well as 12 and 13, characterized in that the film or composites according to the invention serves as the starting material for the production of a packaging or release or protective film with very high water vapor permeability, by using this film with a cold or tempered needle roller is punctured