DE102005004789A1 - Biodegradable film based on regenerating raw materials, useful as stickers for packing, comprises base material e.g. polylactide, long chain lactic acids, hydroxybutyrate and hydroxyvalerate polyester, which is filled up with aggregates - Google Patents

Abstract

Biodegradable film (I) based on regenerating raw materials, comprises at least one base material such as polylactide, long chain lactic acids, homo and copolyester, hydroxybutyrate and hydroxyvalerate polyester, which is filled up with aggregates. Independent claims are included for: (1) a biodegradable adhesive film as banding material for printable self adhesive bands and labels with (I), comprising an adhesive based on copolyesters obtained by ring-opening polymerization of lactone or polycondensation of hydroxy carboxylic acids; and (2) a biodegradable adhesive film on a banding package, comprising the application of corona discharge on one side for improving the detention of the surface treated substrate film, on which detention-improved side of adhesive mass is applied, drying and/or UV-hardening the free surface, and a separating agent between the untreated side of the substrate film and hardened or dried surface of the adhesive mass.

Description

The The invention relates to a biodegradable film, in particular a printable film with an adhesive layer as an adhesive tape Packaging and a matched film / adhesive system.

Natural adhesives or adhesives based on renewable raw materials consist of only a few basic building blocks, such as proteins (eg elastin, fibronectin, Fibonogen, keratin, collagen, laminin) and polysaccharides, (as in z. B. Cellulose starch or gum arabic), polyphenols (eg lignin, urushiol) and Lipids (eg, Therpenes, Therpenharze).

These four basic building blocks can also be combined, for. To glycoproteins, proteoglycans, Phenol proteins, Finolpolysachariden. The adhesive power of this natural Adhesives is in the shear test in the order of 10-14 MPa and is comparable to that of synthetic adhesives.

you now differentiates two different systems, once the physically setting and the chemically setting adhesive systems. At physically Bonding adhesive systems are either used as an adhesive serving substances dissolved in organic solvents, such as z. As in turpentine oil dissolved Abientinsäuren the balsam resin or they are present as a dispersion, such as. B. the latex milk the rubber.

at chemically setting adhesive systems in nature are often around one-component systems, d. H. a monomer is synthesized by animals (e.g., lacewings) and reacts z. B. in the air with oxygen to a high polymer Material.

But also three-component adhesives, such as the mussel's worm threads, in the essentially on proteins, eg. b. 3,4-dihydroxy-phenyl-L-alanine are known in nature. The strength especially under Water can exceed that of epoxy resin adhesives. Nevertheless, they are biological degradable.

moreover are raw materials from nature, especially polysaccharides, cellulose and strength reasonable alternatives to synthetic polymers. Many proteins fall, z. As in the extraction of natural oils, as by-products at low cost.

task The invention is now, a biodegradable film, in particular as a printable self-adhesive film for use as a sticker for packaging, which in turn are biodegradable, z. B. cardboard bags or biodegradable plastic products from renewable raw materials, to accomplish.

To In particular, there are no current state of the art biodegradable adhesives used in large-scale industrial applications, the for a job on adhesive film, in particular self-adhesive tape, on a roll is stored, are suitable.

biological degradable polymers have disadvantages in their use as adhesives on who are using in different fields at least complicate, if not prevent. Especially if one adhesive-high requirement in terms of thermal or mechanical Stability provided be, z. As polyhydroxy butyrates, polyhydroxyvalerates or Polyactides only a small mechanical and thermal stability compared to commercial hot melt adhesives. This leaves them for the desired applications and for processing at elevated Temperature seems inappropriate.

Further is the adhesion of many biodegradable adhesives Adhesive bond inadequate at low temperatures.

According to the invention will now However, a biodegradable film with a base material from the Group: polylactides, long-chain lactic acids, homo- and copolyesters, Hydroxybutyrate and hydroxyvalerate polyester proposed that with organic and inorganic additives on preferred a solids content of over 90% by weight filled is.

Further is a matched biodegradable adhesive on the basis of a copolymer proposed. In the used Polyester can basically be any type of polyester act. For example, these are by ring-opening polymerization of Lactones or polycondensations of hydroxy carboxylic acids produced Polyester.

These include hydroxybutyrate and hydroxyvalerate polyesters, polyactides and / or homo- or copolyesters which can be prepared using lactones and / or hydroxy acid. However, even in cases where the initial strength need not be kept stable for very long periods of time, a natural latex based adhesive in the form of latex milk (which may be aqueous based) may be used Base is mixed with rosin and a solid portion) are provided.

In Certain cases, for example, the flexibility to ensure an adhesive bond even at low temperatures are polyesters with a glass transition temperature from about -40 ° C to about -15 ° C especially suitable. In special cases Also suitable are polyesters whose glass transition temperature is less as -40 ° C, z. B. between -40 ° C and -80 ° C.

To the Adjusting certain melt viscosities may make polyester more different Molecular weights (e.g., 8000-400 Dalton) can be used.

The desired and recall the processing properties achieved with the claimed adhesive to those who use glutin glue when bonding book covers have long been used and their use is well controlled. These also have the property below the gelling point, d. H. by a small drop in temperature of a few degrees from liquid to pass into the glassy state (Sol-gel transition).

By this sudden gelability become fast bonds with excellent initial adhesions achieved, so that the glues even in high-speed production machines with capacities of approx. 100 book covers per minute. It is important, even after long storage of the glue is still a good one Initial liability has to stick well immediately after application. In addition, paper is not attacked and machines and tools can be easily cleaned with the help of water. Through a network two copolyester-based adhesives is still an improvement Degradability possible.

Further Can be a biodegradable adhesive based on renewable Raw materials in the form of natural latex mixed with rosin on aqueous Base be used. Despite the expected lower adhesion show tear-off tests with paper labels a cleavage of the paper. Proposed thereby in particular a Zumengung of a few percent rosin related on the amount of latex milk used.

at the carrier film In addition to the usual train and weighing properties for Slides, especially for Labels and release liners (for example, to separate two layers of adhesive film) one possible high mechanical strength desired. Nevertheless, the tenacity should sufficient to deform in thermoforming the film, for example after putting on a cold cuts wrapper (a wrapper for some Sausage or cheese slices about) was applied.

in this connection It is proposed to use a mixture of polylactic acid (PLA) with - under the commercial name Ecoflex (BASF) available copolymer material (a Mixture of aliphatic diols and aliphatic and aromatic dicarboxylic acids) in relation to from 50:50 to a mixing ratio of 1/3 Ecoflex to 2/3 Provide PLA. In particular, by the further addition of mineral Additives, such as chalk and talc, improve the temperature stability and the notched impact strength as well the surface quality. there In particular, talc also improves the modulus of elasticity, the flexural strength and the ability to beat, if it is added with an addition of 6% to 10%. In this case, an aggregate with a total of 6% or more aggregates be added with a total of 20%. It uses one polylactic acid, as marketed for example by the company Cargill Dow.

Instead of of a base material of polylactide are also base materials from homo- and copolyester, hydroxybutyrate and hydroxyvalerate polyester in question, each with aggregates to the desired Solid content of the film are filled. The majority The solids are organic in nature, but 6-20% of them are going through mineral substances such as talc or chalk are formed, in particular in grain size spectra by 1 micron (for talcum 2 micron) with an upper size (D98%) from 4 (or for Talc 15 micron), the desired mechanical properties in terms of elongation at break and tensile strength result. coarser Aggregates give stiffer foils, finer and more flexible foils. The majority The solids are organic in nature, but 6-20% of them are mineral Substances such as talc or chalk are chosen, which are the desired ones Allow properties in terms of elongation at break and tensile strength.

Prefers become solid additives of both chalk and talcum alike Shares, which in turn each account for 7-10% by weight. Particularly preferred is a "blend" of a blend component Ecoflex with PLA and a solids content of 9% each of two mineral Additives, namely Chalk and talc, exposed.

Of the Share of Ecoflex can range from a quarter to a half of Weight fraction of PLA polylactic acid amount. Is preferred a blend with a 25-40 % By weight of Ecoflex as copolymer.

The blending itself is done with the addition of plasticizers, which adjust the toughness of hard plastics, as usual in the art, and Kopp that improve the compatibility of the individual components with each other. As a result, the proportion of PLA decreases, so that a preferred base material (without mineral solids) has 65-80% PLA content.

By the addition of mineral additives such as chalk or talc, improve now in particular the temperature stability, the notched impact strength and the surface quality. at The addition of talc is also the modulus of elasticity, the bending strength and the ability to beat improved.

at 34% mixture Ecoflex with PLA has a simultaneous dose of talc and chalk are particularly preferred A 44% blend of Ecoflex / PLA is the sole donor of Talcum preferable.

Instead of However, a blend with PLA can also be the amorphous polymer cellulose acetate with the additives as described above with regard to its mechanical properties are improved. A slightly higher price of the raw material have its advantages in terms of high transparency, high surface gloss and good grip over. In addition to these haptic advantages exist with improved modulus of elasticity and fracture stress, in particular also advantages in terms of elongation at break, the above 100% bigger as the most suitable copolymer / PLA base materials. The composition the cellulose acetate mixture eventually needs larger amounts Plasticizer (up to ¼ for ¾ cellulose acetate)

The The adhesive to be applied to the film must be biodegradable be and be made essentially of renewable resources, desired To meet requirements. As the solvent, water is preferred and for coating, the adhesive should be pumpable and have a certain shear strength so that it is not damaged by the pumping and conveying processes.

Further should a uniform viscosity exist be that for a uniform adhesive mass order is decisive. In particular, however, should with the selected material for the Foil be entered a good adhesive bond, and already the initial tack (the so-called tack) should be high enough, to securely close cardboard boxes, even if they are cardboard boxes with high lid voltage. Next should be after processing a storage time of 1-2 Years without quality loss possible his and the adhesive must be over a longer one Period secure the bond and have aging stability. It is allowed by heat do not decompose.

Finally, should the film can be printed using the flexographic printing process of clichés of rubber or photopolymer transfer color to the film becomes. In conventional tapes this is based on polypropylene or polyvinyl chloride film with paints whose pigments are dissolved in organic solvents, solved. For the biological degradable film is intended to be an aqueous based ink or a UV curable ink are used, which should adhere well to the film and this not should swell. Applying the paint can be done both before coating be applied in reverse pressure, as well as after coating on the tape top.

at Presentation as a roll of tape is proposed, the back to avoid interactions between the film and the adhesive with a release agent, for. B. to treat a paint or a release. But it can also be interposed a release film, the also made of biodegradable film with double-sided treatment provided with low release forces is.

Vice versa The film should stay where it is connected to the adhesive should be treated with an adhesion promoter, this may be after physical Paths by means of a corona discharge or by chemical means Apply a primer, an adhesion promoter. at Use of an adhesion promoter should be chosen in such where the solvent contained by heat can be evaporated.

The Coating the film with the adhesive to produce a Band material for printable tapes provided adhesive sheet is divided into two essential operations. The application of the adhesive and the drying of the adhesive. The Adhesive has to be used as a solvent Contain water and be suitable for coating, d. H. she must pumpable be and have a certain shear strength, while at the same time it must be ensured that the film is in turn against the in the adhesive contained water is resistant and does not soften or so is changed in their water balance that they are going through Water absorption at the edges curls.

at drying is the solvent contained in the adhesive vaporized by hot air, the temperature profile and the used Air volume are of crucial importance. At too high temperatures or too big Dwell time in the drying channel can shrink the film. Next is one one-sided drying of the film possible, if the film has a high capacity for water. In this case a rewet can be performed.

To After drying, the tape has to return to room temperature to be cooled down, before you wind it up. The cooling Must be done gently to tighten the material due to strong To avoid temperature changes.

The then produced film bales are integrated by rewinding slitter to roles in the desired Width cut. Optionally, a lamination of Adhesive tape on a release film. The subsequent tape printing could in flexographic printing with UV drying, the surface of the Materials may still be pretreated with a primer can and the pressure, if desired, can still be provided with a protective coating.

hub Talc and chalk as a mineral additive can in particular for the Adhesive mass still other additives are used. Otherwise, based the adhesive based on ring-opening polymerization of Lactones or polycondensations of hydroxycarboxylic acids produced Copolyesters, in particular the hydroxybutyrate or hydroxyvalerate polyester.

alternative But it can also be an adhesive based on natural latex in the form of Latex milk based on water with rosin to a 20-60 (preferred 40-50) % By weight of solid content is mixed, find use. Also, an adhesive based on natural resin is in addition to adhesives on the base of latex milk (natural latex) possible.

In the case the creation of tape winding is proposed, one-sided Corona discharge to improve the adhesion of the surface of the carrier film to contribute there where adhesive is applied, which in turn is surface-hardened and / or UV-cured, to make her better on the associated support film and not at the next one Winding layer adheres.

If needed However, this can also be done by a release agent between the untreated Side of the carrier film and the hardened or dried surface the adhesive mass can also be achieved or promoted. The release agent can one on the adhesion improved side of the carrier film opposite Side of the carrier film applied adhesion-reducing layer or a likewise biological degradable separate release film for separating two layers of Adhesive film coated with a coating on at least one, the side facing the adhesive is provided.

Claims (14)

Biodegradable film based on renewable Raw materials, characterized by at least one base material of the group: polylactides, long-chain lactic acids, homo- and copolyesters, Hydroxybutyrate and hydroxyvalerate polyester is provided with additives filled is. Biodegradable film according to claim 1, characterized characterized in that Base material is a blend of 55 to 65% by weight PLA (polylactic acids) and at least one copolyester is provided. Biodegradable film according to claim 1, characterized characterized in that Base material 15 to 40% by weight of a copolyester and up to 2 percent coupler and one percent plasticizer are provided. Biodegradable film according to one of the preceding Claims, characterized in that mineral Aggregates with 6-20 % are provided. Biodegradable film according to one of the preceding Claims, characterized in that talc is intended as a mineral aggregate 6-10%. Biodegradable film according to one of the preceding Claims, characterized in that CaCO (Chalk) is provided as a mineral additive with 6-10%. Biodegradable adhesive film as strip material for printable self-adhesive tapes and labels with a carrier foil according to one of the preceding claims, characterized by a Adhesive based on ring-opening polymerization of Lactones or polycondensations of hydroxycarboxylic acids produced Copolyester. Biodegradable adhesive film according to claim 6, characterized in that the Glue from the group of hydroxybutyrate or hydroxyvalerate polyester chosen is. Biodegradable adhesive film as strip material for printable Labels with a carrier foil after one of the preceding claims 1 to 6, characterized by an adhesive based on natural latex in the form of latex milk. Biodegradable adhesive film as strip material according to claim 9, characterized in that the latex milk, on an aqueous basis with rosin to a 20-60 % By weight solids content is mixed. Biodegradable adhesive film as strip material according to claim 9 or 10, characterized by an adhesive on the Base of natural resins. Biodegradable adhesive film according to one of the preceding claims 7 to 11 on a tape roll, characterized by one-sided treated by corona discharge to improve adhesion of the surface support film Adhesive composition is applied to the adhesion improved side, the on their free surface dried and / or UV-cured was, and a release agent between the untreated side of the support film and the hardened or dried surface the glue mass. Biodegradable adhesive film according to claim 12, characterized in that the Release agent on the adhesion improved side of the carrier film opposite Side of the carrier film applied adhesion-reducing coating. Biodegradable release film according to one of the preceding claims 1 to 6 for the separation of two layers of adhesive film as a release agent according to claim 12 in close superimposed two adhesive films according to claims 7 to 12, characterized by coating at least one, the Adhesive facing side of the release film with a haftvermindernden Coating.