DE102014223786A1 - Polymer mixture for barrier film - Google Patents

Abstract

The present invention relates to a biodegradable polyester mixture containing: i) 95 to 99.95 wt .-%, based on the components i and ii, of a polyglycolic acid (PGA) and ii) 0.05 to 5 wt .-%, based on the components i and ii, natural wax. Furthermore, the invention relates to single-layer or multilayer films containing these polymer blends and the use of the films for food packaging.

Description

• i) 95 bis 99,95 Gew.-%, bezogen auf die Komponenten i und ii, einer Polyglykolsäure (PGA) und
• ii) 0,05 bis 5 Gew.-%, bezogen auf die Komponenten i und ii, Naturwachs.

The present invention relates to a biodegradable polyester mixture comprising:

• i) 95 to 99.95 wt .-%, based on the components i and ii, of a polyglycolic acid (PGA) and
• ii) 0.05 to 5 wt .-%, based on the components i and ii, natural wax.

Furthermore, the invention relates to single-layer or multilayer films containing these polymer blends and the use of the films for food packaging.

From the EP 2 336 244 Polymer blends of polyglycolic acid and polylactic acid are known which have improved mechanical properties and an acceptable oxygen barrier. Compared with polyethylene films of comparable thickness, however, these mixtures have an insufficient water vapor barrier.

The aim of the present invention was therefore to provide polymer blends which have an improved water vapor barrier compared to pure polyglycolic acid.

• i) 95 bis 99,95 Gew.-%, bezogen auf die Komponenten i und ii, einer Polyglykolsäure (PGA) und
• ii) 0,05 bis 5 Gew.-%, bezogen auf die Komponenten i und ii, Naturwachs.
• erreicht.

Surprisingly, this is achieved by the polymer mixtures according to the invention comprising:

• i) 95 to 99.95 wt .-%, based on the components i and ii, of a polyglycolic acid (PGA) and
• ii) 0.05 to 5 wt .-%, based on the components i and ii, natural wax.
• reached.

These can be processed by extrusion or coextrusion process capable to produce films with very good barrier properties, in particular a high water vapor and oxygen barrier.

The invention will be described in more detail below.

Polyglycolic acid is to be understood as meaning homopolymer of glycolide or glycolic acid or else copolyester which, in addition to glycolide or glycolic acid, contains up to 30% comonomer, such as lactic acid, lactide, ethylene oxalate or ε-caprolactone. Likewise, these include the same polyesters and copolyesters, regardless of whether the monomers are used as lactones or as aliphatic hydroxycarboxylic acids. Next polyglycolic branched and linear polyesters are understood, with linear are preferred. Insbesondre is under polyglycolic acid products such as Kuredux ^® (Kureha) to understand.

Exemplary are the copolymers: ethylene oxalate, lactide, lactic acid, β-propiolactone, β-butyrolactone, pivalactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, trimethylene carbonate, 1,3-dioxane, dioxanone, ε-caprolactam, 3-hydroxypropionic acid 4-hydroxybutanoic acid and 6-hydroxyhexanoic acid. The hydroxycarboxylic acids or their ester-forming derivatives may be used singly or as a mixture of two or more thereof.

The polyglycolic acid generally have a number average molecular weight (Mn) in the range of 5000 to 500,000, in particular in the range of 10,000 to 250,000 g / mol, preferably in the range of 15,000 to 100,000 g / mol, a weight average molecular weight (Mw) of 30,000 to 1000000, preferably 60000 to 500000 g / mol and a Mw / Mn ratio of 1 to 6, preferably 1 to 4 on. The melting point is in the range of 200 to 250, preferably in the range of 210 to 240 ° C.

The MVR (melt volume rate) to EN ISO 1133 (240 ° C, weight 2.16 kg) of the polyglycolic acid is generally from 0.1 to 70, preferably from 0.8 to 70 and in particular from 1 to 60 cm ^3/10 min.

As component ii, the polymer mixture according to the invention contains 0.05 to 5.0 wt .-%, preferably 0.1 to 3.0 wt .-% and particularly preferably 0.1 to 1.0 wt .-%, based on the components i and ii, a natural wax. As a result, the water vapor barrier of the barrier films (single-layer or multilayer film containing this polymer mixture) can be markedly improved again. When using higher amounts of natural wax, the barrier effect decreases again. With a higher amount of natural wax, the adhesive effect of the barrier layer on possibly other layers (multilayer film) also deteriorates.

Under natural wax animal and vegetable waxes such as beeswax, carnauba wax, candelilla wax, Japan wax, Espartograswachs, cork wax, guaruma wax, rice germ oil wax, sugarcane wax, ouricury wax, shellac wax, spermaceti, lanolin (wool wax), crescent fat, Sasol waxes, jojoba wax, or montan wax understood that Lignite can be won and so too of plant origin. Preference is given to carnauba wax, candelilla wax, montan wax and, in particular, beeswax.

Furthermore, 0.5 to 50 wt .-%, based on the components i and ii, of a filler selected from the group consisting of calcium carbonate, talc, kaolin, clay and especially mica or thermoplastic or non-thermoplasticized starch may be added to the polymer mixture. By adding the particularly preferred inorganic fillers calcium carbonate, talc, kaolin, clay and especially mica, the water vapor barrier of the polymer blends can be further improved. Overall, for example, fillers in 5 to 35% by weight, based on the total weight of the polymer mixture, can be added to the polyester mixtures.

Calcium carbonate can be used, for example, in 5 to 25 wt .-%, preferably 10 to 20 wt .-%, based on the total weight of the polymer mixture. Among other things, the calcium carbonate of the company Omya has proven to be suitable. The calcium carbonate typically has an average particle size of 0.5 to 10 microns, preferably 1-5, more preferably 1-2.5 microns.

Talc may for example be used in 3 to 15 wt .-%, preferably 5 to 10 wt .-%, based on the total weight of the polymer mixture. Among other things, the talc from Mondo Minerals has proved suitable. The talc usually has an average particle size of 0.5-10, preferably 1-8, particularly preferably 1-3 micrometers.

By adding thermoplasticized or non-thermoplasticized starch but also calcium carbonate and talc, the tear resistance of the films can be further improved. Starch is also understood as amylose; thermoplasticized means thermoplasticized with plasticizers such as glycerine, sorbitol or water (see EP-A 539,541 . EP-A 575 349 . EP-A 652 910 ) or surface-modified (see EP-A 937120 . EP-A 947559 . EP-A 965615 ). Polymer blends according to the invention which contain from 10 to 35% by weight, based on the total weight of the polymer blend, of thermoplastic or non-thermoplastic starch have both a good degradability in the soil and good mechanical properties, in particular high tear propagation resistance. These starch-containing mixtures are therefore an interesting alternative to the abovementioned filler-containing (calcium- and / or talc-containing), if appropriate also in combination with the filler-containing polymer mixtures.

The polyester mixture may therefore contain other ingredients. The polyester mixture including all other ingredients is referred to below as the polymer mixture.

Furthermore, the polyester film according to the invention may contain further additives known to the person skilled in the art. For example, the usual additives in plastics technology such as stabilizers; nucleating agents; Lubricants and release agents such as stearates (especially calcium stearate); Plasticizers such as citric acid esters (especially acetyltributyl citrate), glyceric acid esters such as triacetylglycerol or ethylene glycol derivatives, surfactants such as polysorbates, palmitates or laurates; Waxes such as erucic acid amide, stearic acid amide or behenamide, beeswax or beeswax esters; Antistatic, UV absorber; UV-stabilizer; Antifog agents or dyes. The additives are usually used in concentrations of 0 to 2 wt .-%, in particular 0.1 to 2 wt .-% based on the polyester film according to the invention. Plasticizers may be contained in 0.1 to 10 wt .-% in the polyester film according to the invention.

Single-layer films with a thickness of between 5 and 100 μm show water vapor permeabilities measured with the polyester mixture according to the invention ASTM F1249 (from August 1, 2011, 23 ° C, 85% rh) from 0.05 to 2 g 100 .mu.m / ^m.sup.2 d, and preferably 0.1 to 1.5 g, 100 .mu.m / ^m.sup.2 d.

In a preferred embodiment, the monolayer films may contain, in addition to the polyester mixtures according to the invention, further polymers selected from the group consisting of polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoate and biodegradable polyesters based on aliphatic or aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds.

Preference is given to multilayer films, wherein the middle layer is a barrier film and contains a polymer mixture according to any one of claims 1 to 3.

The structure of the multilayer film can be both symmetrical and asymmetrical, but the barrier film is not to be understood as the outermost layer. The layer thicknesses of the individual components are generally between 0.01 and 100 microns, but preferably between 0.1 and 50 microns. The number of repeating layers is unlimited.

• A) Schicht A enthält eine Polymermischung der Zusammensetzung: ai) 95 bis 99,95 Gew.-%, bezogen auf die Komponenten ai und aii, einer Polyglykolsäure (PGA) und aii) 0,05 bis 5 Gew.-%, bezogen auf die Komponenten ai und aii, Naturwachs;
• B) Schicht B enthält: bi) 0 bis 70 Gew.-%, vorzugsweise 5 bis 50 Gew.-%, bezogen auf das Gesamtgewicht der Komponenten bi und bii, mindestens eines Polyesters ausgewählt aus der Gruppe bestehend aus Polymilchsäure, Polyhydroxyalkanoat und Polypropylencarbonat und bii) 30 bis 100% Gew.-%, vorzugsweise 5 bis 50 Gew.-%, bezogen auf das Gesamtgewicht der Komponenten bi und bii, mindestens eines biologisch abbaubaren Polyesters gebildet aus aliphatischen oder aliphatischen und aromatischen Dicarbonsäuren und aliphatischen Diolen.

Particularly preferred is a biodegradable multilayer film comprising the layer sequence (A) (B) or (B) (A) (B), wherein the layers A and B have the following composition:

• A) Layer A contains a polymer mixture of the composition: ai) 95 to 99.95 wt .-%, based on the components ai and aii, of a polyglycolic acid (PGA) and aii) 0.05 to 5 wt .-%, based on the components ai and aii, natural wax;
• B) Layer B contains: bi) 0 to 70 wt .-%, preferably 5 to 50 wt .-%, based on the total weight of the components bi and bii, at least one polyester selected from the group consisting of polylactic acid, polyhydroxyalkanoate and polypropylene carbonate and bii) from 30 to 100% by weight, preferably from 5 to 50% by weight, based on the total weight of components bi and bii, of at least one biodegradable polyester formed from aliphatic or aliphatic and aromatic dicarboxylic acids and aliphatic diols.

In addition to the polymer mixture according to the invention, the multilayer films can also in further layers polymers selected from the group consisting of: polylactic acid (PLA), polycaprolactone (PCL) and polyhydroxyalkanoate, thermoplastic and non-thermoplasticized starch or polyester, prepared from aliphatic and aliphatic or aromatic dicarboxylic acids and a containing aliphatic dihydroxy compound.

• • einer Schmelzvolumenrate (MVR) nach EN ISO 1133 (190°C, 2,16 kg Gewicht) von 0.5 bis 30 insbesondere 2 bis 40 cm³/10min)
• • einem Schmelzpunkt unter 240° C;
• • einem Glaspunkt (Tg) größer 55°C
• • einem Wassergehalt von kleiner 1000 ppm
• • einem Monomeren-Restgehalt (Lactid) von kleiner 0.3%.
• • einem Molekulargewicht von größer 80000 Dalton.

PLA with the following property profile is preferred:

• • a melt volume rate (MVR) after EN ISO 1133 (190 ° C, 2.16 kg weight) from 0.5 to 30 especially 2 to 40 cm ^3/10 min)
• • a melting point below 240 ° C;
• • a glass point (Tg) greater than 55 ° C
• • a water content of less than 1000 ppm
• • a residual monomer content (lactide) of less than 0.3%.
• • a molecular weight of more than 80,000 daltons.

Preferred polylactic acids are, for example Ingeo ^® 8052D, 6201D, 6202D, 6251D, 3051D, and particularly Ingeo ^® 4020D, 4032D or 4043D (polylactic acid of Fa. Nature Works).

By adding PLA in the claimed quantitative range, the properties of the polyester film (puncture resistance and tear propagation resistance) produced from the polymer mixture can be significantly improved again. It is also possible to use mixtures of readily flowing and more viscous PLA.

Polyhydroxyalkanoates are understood as meaning primarily poly-4-hydroxybutyrates and poly-3-hydroxybutyrates and copolyesters of the abovementioned polyhydroxybutyrates with 3-hydroxyvalerate, 3-hydroxyhexanoate and / or 3-hydroxyoctanoate. Poly-3-hydroxybutyrate are sold for example by the company. PHB Industrial under the brand name Biocycle ^® and by the company. Tianan under the name Enmat ^®. Poly-3-hydroxybutyrate-co-4-hydroxybutyrates are known in particular from Metabolix. They are marketed under the trade name Mirel ^®. Poly-3-hydroxybutyrate-co-3-hydroxyhexanoates are known from the company P & G or Kaneka. Poly-3-hydroxybutyrate-co-3-hydroxyhexanoates generally have a 3-hydroxyhexanoate content of from 1 to 20 and preferably from 3 to 15 mol%, based on the polyhydroxyalkanoate. The polyhydroxyalkanoates generally have a molecular weight Mw of from 100,000 to 1,000,000, and preferably from 300,000 to 600,000.

Polyesters based on aliphatic or aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds are referred to below as aliphatic or partially aromatic (aliphatic-aromatic) polyesters. Common to these polyesters is that they are biodegradable according to DIN EN 13432 are. Of course, mixtures of several such polyesters are suitable.

According to the invention, partially aromatic (aliphatic-aromatic) polyesters are also to be understood as meaning polyester derivatives which contain up to 10 mol% of functions other than ester functions, such as polyether esters, polyesteramides or polyetheresteramides and polyesterurethanes. Suitable partially aromatic polyesters include linear non-chain extended polyesters ( WO 92/09654 ). Preferred are chain-extended and / or branched partially aromatic polyesters. The latter are from the documents mentioned above, WO 96/15173 to 15176 . 21689 to 21692 . 25446 . 25448 or the WO 98/12242 , to which express reference is made. Mixtures of different partially aromatic polyesters are also possible. Interesting recent developments are based on renewable raw materials (see WO-A 2006/097353 . WO-A 2006/097354 such as WO 2010/034689 ). In particular, under partly aromatic polyesters products such ecoflex ^® (BASF SE) and Eastar ^® Bio to understand Origo-Bi ^® (Novamont).

Aliphatic polyesters are understood as meaning polyesters of aliphatic diols and aliphatic dicarboxylic acids such as polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene succinate adipate (PBSA), polybutylene succinate sebacate (PBSSe), polybutylene sebacate (PBSe) or corresponding polyesteramides or polyester urethanes. The aliphatic polyesters are marketed, for example, by the companies Showa Highpolymers under the name Bionolle and by Mitsubishi under the name GSPla. Recent developments are in the WO 2010034711 described. Preferred aliphatic polyesters are polybutylene succinate sebacate (PBSSe) and most preferably polybutylene sebacate (PBSe).

The polypropylene carbonate can be analogous, for example WO 2003/029325 . WO 2006/061237 or WO 2007 2007/127039 getting produced.

The polyester used may be the same polyester as the previously described aliphatic or aliphatic-aromatic polyester aii, but it is also possible to use different polyesters ai and bii.

Also, the polymer mixtures, in particular the polylactic acid-containing mixtures 0 to 1 wt .-%, preferably 0.01 to 0.8 wt .-%, particularly preferably 0.05 to 0.5 wt .-%, based on the total weight of the components i to vi, an epoxy group-containing co-polymer based on styrene, acrylic acid esters and / or methacrylic acid esters are added. The epoxy groups bearing units are preferably glycidyl (meth) acrylates. Particularly useful is the Joncryl previously described ^® ADR 4368th

The production of the monolayer or multilayer films according to the invention can be carried out by means of the customary production methods, such as lamination or extrusion processes, such as, for example, in US Pat J. Nentwig "Plastic Films", 2nd edition, Hanser Verlag, Berlin (20000), pages 39 to 63 described. For the multilayer films, production by means of coextrusion has proved to be particularly suitable, for example in US Pat J. Nentwig "plastic films", 2nd edition, Hanser Verlag, Berlin (20000), pages 58 to 60 described.

These slides can u. a. used for food packaging to ensure a longer shelf life of these. For example, here are meat, fish, cheese, chocolate packaging, but also the packaging of coffee, tea and spices. In this case, the films can be used, for example, as outer packaging or as cover film.

The water vapor barrier was after the ASTM F-1249 standard in the updated version of 1 August 2011.

Component i:

• i-1: polyglycolic Kuredux ^® 100E35 Fa Kureha..

Component ii:

• ii-1: beeswax.
• ii-2: canauba wax
• ii-3: Candellila Wax

I. Compounding of the polymer mixture

General procedure (example 1):

The compounding was carried out on an extruder at a temperature of 230 ° C. Mixtures of components i-1 and ii-2 are prepared. To ensure a good mixing of the components was mixed at a speed of 80 revolutions / minute for three minutes. After this time, the melt was drained and the strand processed into smaller pieces.

Comparative Example 1a:

Here, as described in Example 1 100 wt .-% of component i-1 was used.

Example 1b:

Here, as described in Example 1, 99.8% by weight of component i-1 and 0.2% by weight of component ii-1 were used.

Example 1c:

Here, as described in Example 1, 99.0% by weight of component i-1 and 1.0% by weight of component ii-1 were used.

Example 1d:

Here, as described in Example 1, 95.0% by weight of component i-1 and 5.0% by weight of component ii-1 were used.

Comparative Example 1e:

Here, as described in Example 1, 90.0% by weight of component i-1 and 10.0% by weight of component ii-1 were used.

Example 1f:

Here, as described in Example 1, 99.0% by weight of component i-1 and 1.0% by weight of component ii-2 were used.

Example 1g:

Here, as described in Example 1, 95.0% by weight of component i-1 and 5.0% by weight of component ii-2 were used.

Comparative Example 1h:

Here, as described in Example 1, 90.0% by weight of component i-1 and 10.0% by weight of component ii-2 were used.

Example 1i:

Here, as described in Example 1, 99.0% by weight of component i-1 and 1.0% by weight of component ii-3 were used.

Example 1j:

Here, as described in Example 1, 95.0% by weight of component i-1 and 5.0% by weight of component ii-3 were used.

Comparative Example 1k:

As described in Example 1, 90.0% by weight of component i-1 and 10.0% by weight of component ii-3 were used here.

II. Production of Press Films

Polyester blends of Example 1 were pressed into press films (100 .mu.m) on a hot press Hy 1086 IWK. Compounds with component i-1 were processed at a temperature of 230 ° C. The composition for pressing was used as follows. Between the press jaws came from the bottom up a steel plate, a Teflon foil, a steel frame and in this the plastic, a Teflon foil and finally again a steel plate. The granules were melted for 10 minutes, then incubated at 50 bar for 1 minute, at 100 bar for 1 minute and at 200 bar for 2 minutes. It was cooled under pressure and the film was separated from the mold.

III. Determination of the water vapor barrier

The water vapor transmission was based on a Permatran 3/33 from Mocon ASTM F-1249 measured at 23 ° C against a gradient of 85% rh. Material thicknesses for calculating the permeability of the specimens were correspondingly DIN 53370 determined by mechanical scanning. The permeability was given in g 100 μm / m ² d. In order to achieve the best possible comparability with other materials, the measured value was related to a layer thickness of 100 μm. The permeability of oxygen was also measured at 23 ° C, but 0% rh (O ₂ gradient 1 bar). The permeability of oxygen is determined with the unit cm ³ 100 microns / m ² d bar. V-1a 1b 1c 1d V-1e 1f 1g V-1h 1i 1j V-1k Component i-1 [% by weight] 100 99.8 99 95 90 99 95 90 99 95 90 Component ii-1 [% by weight] - 0.2 1 5 10 Component ii-2 [% by weight] 1 5 10 Component ii-3 [% by weight] 1 5 10 Compounding Temp. [° C] 230 230 230 230 230 230 230 230 230 230 230 Processing Temp. [° C] 230 230 230 230 230 230 230 230 230 230 230 Permeability H ₂ O _g [g 100 μm / m ² d] 23 ° C, 85% rh 2.6 0.21 0.43 0.63 1.90 0.36 0.60 2.30 0.43 0.67 2.10

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2336244 [0003]
• EP 539541 A [0017]
• EP 575349 A [0017]
• EP 652910A [0017]
• EP 937120 A [0017]
• EP 947559 A [0017]
• EP 965615 A [0017]
• WO 92/09654 [0031]
• WO 96/15173 [0031]
• WO 15176 [0031]
• WO 21689 [0031]
• WO 21692 [0031]
• WO 25446 [0031]
• WO 25448 [0031]
• WO 98/12242 [0031]
• WO 2006/097353 A [0031]
• WO 2006/097354 A [0031]
• WO 2010/034689 [0031]
• WO 2010034711 [0032]
• WO 2003/029325 [0033]
• WO 2006/061237 [0033]
• WO 20072007/127039 [0033]

Cited non-patent literature

• EN ISO 1133 [0011]
• ASTM-F1249 [0020]
• EN ISO 1133 [0026]
• DIN EN 13432 [0030]
• J. Nentwig "Kunststoff-Folien", 2nd ed., Hanser Verlag, Berlin (20000), pages 39 to 63 [0036]
• J. Nentwig "Kunststoff-Folien", 2nd edition, Hanser Verlag, Berlin (20000), pages 58 to 60 [0036]
• ASTM F-1249 Standard [0038]
• ASTM F-1249 [0052]
• DIN 53370 [0052]

Claims (6)

Biodegradable polyester mixture comprising: i) 95 to 99.95 wt .-%, based on the components i and ii, of a polyglycolic acid (PGA) and ii) 0.05 to 5% by weight, based on the components i and ii, of natural wax. A polyester mixture according to claim 1, containing 0.1 to 1.0 wt .-%, based on the components i and ii, natural wax. A polyester mixture according to claim 1 or 2, containing 0.5 to 50 wt .-%, based on the components i and ii, of a filler selected from the group consisting of calcium carbonate, talc, kaolin, clay and mica. A biodegradable film comprising a polymer mixture according to claims 1 to 3.  A biodegradable multilayer film comprising the layer sequence (A) (B) or (B) (A) (B), wherein the layers A and B have the following composition: A) Layer A contains a polymer mixture according to claims 1 to 3; B) Layer B contains: bi) 0 to 70 wt .-%, based on the total weight of the components bi and bii, at least one polyester selected from the group consisting of polylactic acid, polyhydroxyalkanoate and polypropylene carbonate and bii) from 30 to 100% by weight, based on the total weight of components bi and bii, of at least one biodegradable polyester formed from aliphatic or aliphatic and aromatic dicarboxylic acids and aliphatic diols.  Use of the films according to claims 4 and 5 for the packaging of foods.