EP2494106A1

EP2494106A1 - Method for recycling paper products glued and/or coated with biodegradable polymers

Info

Publication number: EP2494106A1
Application number: EP10768263A
Authority: EP
Inventors: Motonori Yamamoto; Andreas KÜNKEL; Gabriel Skupin; Rainer Blum
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2009-10-26
Filing date: 2010-10-25
Publication date: 2012-09-05
Also published as: US20120276619A1; BR112012009873A2; CA2777904A1; US8679826B2; WO2011054694A1; ZA201203764B; CN102575423B; CN102575423A

Abstract

The invention relates to a method for recycling paper products glued and/or coated with polymers, wherein the paper products glued and/or coated with polymers are placed in an aqueous wastepaper suspension, said wastepaper suspension a) is broken down in the presence of at least one hydrolase, b) is broken down in an alkaline medium, and/or c) is treated in a de-inking process in an alkaline medium, and the polymers are subsequently separated from the wastepaper suspension, wherein the polymers are biodegradable polymers.

Description

Process for recycling paper products sized and / or coated with biodegradable polymers

description

The present invention relates to a process for recycling paper products sized and / or coated with biodegradable polymers, and to a process for sizing paper with biodegradable polymers and a paper product sized with biodegradable polymers.

Polymer-coated paper products have numerous applications, particularly in paper grades whose ink-jet printability can be improved by the polymer coating, that is, all graphic papers, plain paper, coated papers, or cardboard. In this case, the polymer is applied to the surface of the paper as an aqueous dispersion or aqueous solution, for example, and the paper thus treated is dried.

These polymer dispersions or aqueous solutions of the polymers and the coating process for paper are numerous in the literature, i.a. in

WO 2004/096566 A1, US Pat. No. 6,699,536 and WO2008 / 142003 A1 and the publications cited therein.

Waste paper and the recovery of waste paper from paper products are of particular economic importance in the paper industry, since resources (pulp) can be spared in this way. The term "waste paper" is based on DIN 6730 and is therefore defined as paper or paperboard that is used or recycled from production or processing and recycled as pulp again to a manufacturing process Wastepaper is the secondary raw material used in papermaking and paperboard production, but waste paper can not be recycled any number of times After 4 to 6 cycles, they lose the ability to recombine into a sheet structure, which in turn has a negative impact on paper strength and contamination of recycled paper increases with increasing recycling cycles, as inorganic and especially organic contaminants, such asFor example, polymers, can not be completely separated and thus accumulate.

Some methods are known from the literature, which deal with the production of paper from waste paper. Essentially, this involves the so-called deinking process, in which the paper fiber is recovered by removing the printing ink in the alkaline medium, and the so-called impacting, wherein the aqueous waste paper suspension is optionally concentrated, mechanically in a kneader is pitched and then the impurities and polymers are separated from the paper fiber via a sorting (for example by baskets). Usually In the case of all other types of paper, it is now common practice that they are first pre-cleaned by being whipped before they are allowed to dry Deinking process are fed.

The recovery of fiber material by impact has long been known and described for example in DE 1 761 864 and DE 2 413 159. The particular problem of sorting to separate the contaminants from the paper fiber is i.a. in

EP 1 860 231 A2 and EP 1 462 568 A1. The deinking process is known, for example, from WO 2007/145932 A1.

Regardless of the method of waste paper processing, the separation of impurities and of polymers coated with the paper products has so far been insufficient. Paper products coated with polymers, in particular, are scarcely accessible or only at the expense of problems because the polymers during the papermaking process from waste paper lead to deposits, in particular on parts of the paper machine and to quality losses of the paper products produced. The deposition behavior of such polymers is enhanced by the fact that they are generally poorly water-soluble or even water-insoluble and tend to agglomerate on. Due to the required cleaning work, this leads to a regular shutdown of the machines and in some cases even to a loss of production during the manufacturing process.

In addition to the above-mentioned papers whose ink-jet printability is to be improved by the polymer coating, further polymer-coated paper products are known. These are used, for example, as paper bags for dry foods or for liquids, as cardboard cups, as beverage cartons and containers for liquids. They are characterized by the fact that they give the paper product on the one hand a certain dimensional stability and on the other hand make the paper product impermeable to liquids and thus easy to handle, especially for the end user. Therefore, especially in the food sector such paper products have prevailed.

For a long time, PE (polyethylene) coated packaging and paper products have been known, especially in the areas of foodstuffs (eg beverages), cosmetics and detergents, the PE film being a very thin barrier coating inside, outside and / or between the products different paper layers can be applied. Usually, such a paper product is coated on at least one of the two surfaces with PE film.

A disadvantage of the paper products coated with PE is that they are not accessible for reuse of the paper stock in the course of conventional recycling, but only in recycling plants developed for this purpose. Such paper products are disposable materials and can process conventional recycling, as for example for other types of paper such as newspaper and magazine papers is common, not supplied. Usually PE-coated paper products must be burned, as well as composting is not possible. Furthermore, coated packaging, especially as beverage cartons, under the trade name Tetra Pak ^® known. Again, these are plastic-coated cardboard packaging, which as a rule continue to have an aluminum layer as a liquid-repellent layer. Another problem is the reprocessing or recycling of the individual components of a Tetra Pak ^® packaging. These must first be collected separately from the remaining household waste. According to the manufacturer, re-use of the Tetra ^Pak® packaging since 2008 has been possible with a new plasma technique. After dismantling the Tetra ^Pak® into small pieces, the cardboard is first separated from the aluminum foil and the plastic sleeve by means of water. In the following step, the aluminum foil is separated from the plastic casing by means of a plasma jet, without burning the plastic, whereby the packaging can be almost completely separated into all three components cardboard, plastic and aluminum.

A disadvantage of this method is that it is very complicated by the separate collecting and separate recycling. In addition, according to the manufacturer, it is initially only carried out in Brazil, so that it is not recommended for reasons of environmental protection.

In addition, all of the mentioned paper products, regardless of their use as eg graphic papers, PE-coated paper products or Tetra ^Pak®, still contain polymeric sizing agents. These sizing agents, which are known, inter alia, from EP 0 273 770 B1, EP 0 257 412 B2, WO 99/42490 A1 and WO 2007/000420 A1 and the literature cited therein, can not be completely separated off and lead in the known recycling process in the recovery process to the same difficulties as the polymers with which the paper products were coated.

The methods known from the prior art for the recovery of paper fibers from paper products sized and / or coated with polymers thus have disadvantages regardless of the type and composition of the sizing and / or coating polymers, since the polymers are often not completely separated from the paper fiber to let. In particular, the aforementioned polymer-coated paper products which are used in the field of food, cosmetics and cleaning agents are not at all accessible for recycling or can be recycled only with great difficulty. It is an object of the present invention to provide a process for recycling paper-sized and / or coated paper products in which the paper fiber is almost completely separated from the polymer layer and the paper fiber thus obtained can be fed directly to the papermaking process , It is another object of the present invention to provide a process for sizing polymer-sized paper products which can be recycled from the polymeric sizing agent with almost complete separation of the paper fiber. In addition, the sizing effect of the polymeric sizing agents should be comparable to the prior art.

The object is achieved by a method for recycling paper-sized and / or coated paper products, in which the paper-sized and / or coated paper products are initially charged in an aqueous waste paper suspension, this waste paper suspension a) is pitched in the presence of at least one hydrolase, b ) in alkaline medium, and / or c) is treated in an alkaline deinking process, and the polymers are subsequently separated from the waste paper suspension, the polymers being biodegradable polymers.

Furthermore, the object is achieved by a method for sizing paper in which biodegradable polymers are used as the polymeric sizing agent. These biodegradable polymers are suitable both as a bulk and as a surface-sizing agent.

For the purposes of the present invention, the term "paper products" covers all types of paper, cardboard and paperboard .Fibres for the production of these paper products include all the qualities customary for this purpose, eg wood pulp, bleached and unbleached pulp, pulps from all annual plants and waste paper ( These pulps may be used either alone or in any desired mixture with each other to produce the pulps from which the paper products are made. chemo-thermo-mechanical pulp (CTMP), pressure groundwood, semichemical pulp, high yield pulp and refiner mechanical pulp (RMP), for example sulphate, sulphite and soda pulps are suitable pulp Suitable annual plants for the production of pulp include rice, wheat, sugar cane U.N Kenaf.

In the method according to the invention for recycling paper products sized and / or coated with biodegradable polymers, an aqueous waste paper suspension is first produced from these paper products. This waste paper suspension, which usually has a waste paper concentration between 2 and 40 wt .-%, can a) in the presence of at least one hydrolase, b) is beaten in alkaline medium, and / or c) is treated in an alkaline deinking process, wherein the biodegradable polymers are separated from the pulp. In this way, the pulp is almost completely, preferably completely recovered.

The embodiments a) and b) according to the invention are characterized by the method of impacting the waste paper suspension. As described above, water is added to the paper product during whipping in order to initially obtain an old paper suspension, which may optionally be concentrated or whipped up in an unchanged concentration. For impacting the waste paper suspension is treated in a pulper or a drum, whereby by mechanical action, the biodegradable polymers are separated from the paper product. At the same time, the paper product is crushed. The polymeric residues are then sorted, e.g. via baskets, separated from the shredded paper product.

In embodiment a), the impact of the waste paper suspension takes place in the presence of a hydrolase. As hydrolases [EC 3.x.x.x], for example, esterases [EC 3.1.x.x] and proteases [EC 3.4.x.x] are suitable. According to the invention, in particular carboxy esterases [3.1.1.1] and / or lipases [3.1.1.3] and / or cutinase [3.1.1.74] are used. Examples thereof are lipase or cutinase from Achromobacter sp., Aspergillus sp., Candida sp., Candida antarctica, Mucor sp., Penicilium sp., Geotricum sp., Rhizopus sp., Rhizopus arrhizus, Burkholderia sp., Pseudomonas sp. , Pseudomonas cepacia, Thermomyces sp., Porcine pancreas or wheat germ, and carboxyesterases from Bacillus sp., Pseudomonas sp., Burkholderia sp., Mucor sp., Saccharomyces sp., Rhizopus sp., Thermononospora fusca, Thermobifida fusca, Fusarium solani, Thermoanaerobium sp.

Pork liver or horse liver. Further examples of hydrolases are polyhydroxyalkanoate depolymerase and / or proteinase K. According to the invention, at least one hydrolase is used, so it is of course possible to use one of the mentioned hydrolases or a mixture of two or more of the mentioned hydrolases. However, preference is given to using only one of the stated hydrolases in the process according to the invention in embodiment a).

The hydrolases can be used in free form, preferably in aqueous solution, or immobilized.

Preferred in the method according to the invention of embodiment a) is a lipase and / or cutinase from Pseudomonas capacia, Burkholderia capacii, Candida antarctica or Rhizopus arrhizus, Thermomonospora fusca, Thermobifida fusca, Fusarium solani, in free form, preferably aqueous solution, or in immobilized form (for example Novozym ^® 435 Novozymes AS).

The total amount of hydrolase used is generally 0.001 to 40 wt .-%, often 0.01 to 15 wt .-%, preferably 0.1 to 5 wt .-%, each based on the total solution.

A particularly advantageous feature of embodiment a) is that the use of the hydrolase hydrolyzes the biodegradable polymers and thereby separates them completely from the paper fiber, both the polymeric sizing agents and the polymer coatings.

In another embodiment b) of the method according to the invention, the impact of the waste paper suspension in alkaline medium, ie for example in a pH range from 8, for example between 8 and 12, preferably between 10 and 12. To adjust the pH, the waste paper suspension with a base, which is preferably selected from the group of alkali and alkaline earth metal hydroxides. Examples include sodium hydroxide, potassium hydroxide, calcium hydroxide, and magnesium hydroxide. Of course, other hydroxides are possible such. Aluminum hydroxide. Particular preference is given to using sodium hydroxide solution.

Particularly advantageous in the embodiment b) is that the biodegradable polymers dissolve in the alkaline medium and thereby completely separate from the paper fiber.

The embodiments a) and b) are also particularly advantageous for the direct recycling of paper broke. In the manufacture of paper products, this so-called paper scrap regularly occurs, which is a paper product with a lower, undesirable quality. This quality-based production committee is not reusable for the paper manufacturer in the manufacturing process. Rather, this committee must be separated and fed to one of the recycling processes described in the prior art. Embodiments a) and b) now enable the papermaker to deposit his own paper broke in a pulper or a drum dissolver on site. The paper fiber obtained in this way can be fed directly to the process for producing the paper product.

The embodiment c) of the method according to the invention is characterized in that the waste paper suspension in the alkaline medium is treated in a deinking process.

By deinking the skilled person understands the flotation deinking process on the one hand and the washing deinking process on the other hand. According to the invention, both deinking processes can be carried out in embodiment c). It is now common practice that the old Apiersuspensionen, which are fed to a deinking process, are first opened to at least partially reduce the paper fiber already.

According to the flotation deinking process, the hydrophobized particles separated from the fibers in the waste paper suspension after the fiberization step (impacting) are adsorbed to air bubbles by collector chemicals and transported by them to the surface of the flotation cell. The dirt-laden foam, which may contain fibers and fillers in addition to the impurities and polymer residues, is skimmed off. To reduce the fiber loss, the discharged foam is cleaned before the residue is disposed of after thickening. As chemical additives are usually u.a. about 2 wt .-% sodium hydroxide, about 1 wt .-% hydrogen peroxide, about 3 wt .-% water glass and other additives used in lower proportions. All chemicals are dissolved together in water and added together to the shredded (pitched) waste paper suspension. In some recycling plants, the bleaching is carried out separately. Meanwhile, it is common that the waste paper suspension is fed twice in a row to the flotation deinking process, so as to achieve the best possible separation of impurities and polymers from the paper fiber.

The washing deinking process is very common, especially in North America. In contrast to flotation, the laundry is a drainage and thickening process. The polymer particles detached as far as possible from the fibers must be well dispersed so that no renewed attachment to the fibers can take place when dewatering the suspension. For this purpose, the prescribed pH range must be maintained very precisely throughout the entire process. The dewatering is usually carried out in a multi-stage process, the resulting filtrates, which contain the detached polymer particles in high dilution, are separated. A disadvantage of the washing deinking process is that the filler and fiber discharge is substantially higher than in the flotation.

As mentioned above, the process according to the invention in embodiment c) is possible in both deinking processes. It is essential to the invention that the waste paper squeeze ion is present in the alkaline medium and thus supplied to the deinking process. Alkaline medium means that the waste paper suspension has a pH above 8, preferably between 8 and 12, particularly preferably between 10 and 12. To adjust the pH, the bases described above are suitable, sodium hydroxide being particularly preferably used.

Again, it is particularly advantageous that the biodegradable polymers dissolve in the alkaline medium and thereby almost completely separate from the paper fiber.

The process according to the invention is preferably carried out in only one of the described embodiments a), b) or c). However, it is also possible to carry out any combinations of at least two embodiments. In general, however, enough one of the aforementioned embodiments in order to achieve a complete separation of the biodegradable polymers from the paper fiber.

The present invention likewise provides a process for sizing paper products in which biodegradable polymers are used as polymeric sizing agent. These biodegradable polymers are useful as both bulk and surface sizing agents.

As a sizing agent, the biodegradable polymers are added to the paper before sheet formation. The addition of the biodegradable polymers for thick material (fiber concentration> 15 g / l, for example in the range of 25 to 40 g / l up to 60 g / l) or in the thin material (fiber concentration <15 g / l, eg in the Range of 5 to 12 g / l). The addition point is preferably before sheet formation, may also be between a shear stage and a screen or after. Usually, amounts of biodegradable polymer in the range of 0.05 to 1% by weight, preferably 0.1 to 0.6% by weight, in each case solid, based on dry paper stock, are used as engine size.

When applying the biodegradable polymers as surface sizing agents, these can be processed in all suitable process methods for surface sizing. For example, the polymers may be applied to the surface of the paper to be sized using a size press, a film press, or a gate roll applicator. For use, the polymers are usually added to the size press liquor in an amount of from 0.01 to 3% by weight, preferably from 0.05 to 1% by weight, in each case based on dry paper stock, and are based on the desired degree of sizing of the papers to be equipped. Furthermore, the size press fleet may contain other substances, such. As starch, pigments, dyes, optical brighteners, biocides, solidifiers for paper, fixing agents, defoamers, retention aids, and / or dehydrating agents. The amounts of biodegradable polymer applied to the surface of paper products are, for example, 0.005 to 3.0 g / m ² , preferably 0.01 to 1 g / m ² .

The biodegradable polymers as sizing agent, whether as a mass or surface sizing agent, with known polymeric sizing a comparable Leiungswirkung. However, the paper products sized in this way have the advantage over the known paper products that they are accessible to a recycling process in which the paper fiber can be completely recovered.

The present invention therefore also relates to a paper product sized with biodegradable polymers.

The present invention includes a method of recycling paper products sized and / or coated with biodegradable polymers and a method of sizing paper products with biodegradable polymers. The term "biodegradable" in the context of the present invention is then fulfilled for a substance or a mixture of substances if this substance or the substance mixture according to DIN EN 13432 has a percentage degree of biodegradation of at least 90%.

In general, biodegradability results in polymers and polymer blends (hereinafter also abbreviated to polymer (blends)) decomposing in a reasonable and detectable time. The degradation may be enzymatic, hydro- lytic, oxidative and / or by the action of electromagnetic radiation, such as UV radiation, carried out and usually for the most part be effected by the action of microorganisms such as bacteria, yeasts, fungi and algae. The biodegradability can be quantified, for example, by mixing polymer (mixtures) with compost and storing them for a specific time. For example, according to DIN EN 13432, C02-free air is allowed to flow through ripened compost during composting and this treated compost is subjected to a defined temperature program. Here, the biodegradability is determined by the ratio of the net C02 release of the sample (after deduction of C02 release by the compost without sample) to the maximum C02 release of the sample (calculated from the carbon content of the sample) as a percentage of defined biodegradation. Biodegradable polymers (mixtures) usually show signs of degradation after just a few days of composting, such as fungal growth, cracking and hole formation.

Other methods of determining biodegradability are described, for example, in ASTM D 5338 and ASTM D 6400-4.

Paper products coated with biodegradable polymer (blends) are known from European Patent Application Serial No. EP 09010388.8. These are usually multi-layer coatings, usually 2 to 7 layers and preferably 2 to 3 layers are used in the paper coating. For such coated paper products and their production is at this point expressly to the older European application with the file number

EP 09010388.8.

Biodegradable polymers are already known to the person skilled in the art and are disclosed, inter alia, in Ullmann ^'s Encyclopedia of Industrial Chemistry (online version 2009), Polymers, Biodegradable, Wiley-VCH Verlag GmbH & Co. KG, Weinheim, 2009, pages 131. In particular, biodegradable polymers within the meaning of the present invention include biodegradable, aliphatic-aromatic polyesters as described in the earlier European application with the file reference EP 09010388.8.

In the process according to the invention for recycling are paper products which are mixed with a polyester with a melt volume rate (MVR) according to EN ISO 1133 (190 ° C, 2.16 kg weight) from 2 to 50 cm ^3/10 min and / or polymer mixtures containing such polyester be coated.

Particular suitable are paper products, the volume rate with a polyester having a melt (MVR) according to EN ISO 1133 (190 ° C, 2.16 kg) of 5 to 25 cm ^3/10 min and particularly preferably from 5 to 12 cm ³ / 10 min to be coated.

Of course, it is also possible to recycle paper products which have been coated with polymer blends of the polyesters with other biodegradable polymers, in particular polylactic acid. It has proven to be advantageous that these polymers have a high flowability.

For example, polylactic acid has a melt volume rate (MVR) according to EN ISO 1133 (190 ° C, 2.16 kg weight) from 5 to 70 cm ^3/10 min, more preferably 9-50 cm ^3/10 min and especially preferably from 5 to 25 cm ^3/10 min proved mixing partners in such polymer blends. Furthermore, mixtures of flowable polyesters with the abovementioned flowable polymer mixtures are suitable for paper coating. Partly aromatic polyesters based on aliphatic diols and aliphatic / aromatic dicarboxylic acids are also understood as meaning polyester derivatives, such as polyether esters, polyester amides or polyetheresteramides. Partially aromatic polyesters include linear non-chain-extended polyesters (WO 92/09654 A1). In particular, aliphatic / aromatic polyesters of butanediol, terephthalic acid and aliphatic Ce- cis-dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid and brassylic acid (for example as described in WO 2006/097353 to 56) suitable mixing partners. Preferred are chain-extended and / or branched partially aromatic polyesters. The latter are known from documents WO 96/15173 to 15176, 21689 to 21692, 25446, 25448 or WO 98/12242, to which reference is expressly made. Mixtures of different partially aromatic polyesters are also suitable for coating paper products.

Biodegradable, aliphatic-aromatic polyesters as sizing and / or coating compositions for paper products are preferably understood to mean those which are i) 40 to 70 mol%, based on the components i to ii, of one or more dicarboxylic acid derivatives or dicarboxylic acids selected from Group consisting of succinic acid, adipic acid, sebacic acid, azelaic acid and brassylic acid, ii) 60 to 30 mol%, based on the components i to ii, of a terephthalic acid derivative, iii) 98 to 102 mol%, based on the components i to ii, a C2-C8-alkylenediol or C2-C6-oxyalkylenediol, 0.00 to 2 wt .-%, based on the total weight of components i to iii, of a chain extender and / or crosslinker selected from the group consisting of a di- or polyfunctional isocyanate, isocyanurate, oxazoline, epoxide, carboxylic anhydride and / or a at least trifunctional alcohol or at least trifunctional carboxylic acid,

0.00 to 50% by weight, based on the total weight of components i to iv, of an organic filler selected from the group consisting of native or plasticized starch, natural fibers, wood flour and / or an inorganic filler selected from the group consisting of chalk , precipitated calcium carbonate, graphite, gypsum, conductive carbon black, iron oxide, calcium chloride, dolomite, kaolin, silica (quartz), sodium carbonate, titanium dioxide, silicate, wollastonite, mica, montmorillonite, talc, glass fibers and mineral fibers, and vi) from 0.00 to 2 wt. %, based on the total weight of components i to iv, of at least one stabilizer, nucleating agent, lubricant and release agent, surfactant, wax, antistatic agent, antifogging agent, dye, pigment, UV absorber, UV stabilizer or other plastic additive, and a melt volume rate (MVR) according to EN ISO 1133 (190 ° C, 2.16 kg weight) from 3 to 50 cm ^3/10 min have.

As described above, the biodegradable, aliphatic-aromatic polyesters are known from the earlier European application with the file number EP 09010388.8. This document and the literature cited therein are expressly incorporated by reference for both the composition of these polyesters and the processes for their preparation.

From the compounds described there are preferred as copolymer mixtures, the

(a) 5 to 95% by weight, preferably 30 to 90% by weight, more preferably 40 to 70% by weight of a biodegradable aliphatic-aromatic polyester, and (b) 95 to 5% by weight, preferably 70 to 10 wt .-%, particularly preferably 60 to 30 wt .-% of one or more polymers selected from the group consisting of polylactic acid, polycaprolactone, polyhydroxyalkanoate, chitosan and gluten and one or more polyesters based on aliphatic diols and aliphatic / aromatic Dicarboxylic acids such as polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene succinate sebacate (PBSSe), polybutylene terephthalate-co-adipate (PBTA) and

(c) 0 to 2 wt .-% of a compatibilizer included. Compatibilizers of group (c) are carboxylic acid anhydrides, such as maleic anhydride, and in particular epoxide group-containing copolymers based on styrene, acrylates and / or methacrylates. The epoxy groups bearing units are preferably glycidyl (meth) acrylates. The epoxy-containing copolymers of the above type are sold for example by BASF Resins BV under the trademark Joncryl ^® ADR. Particularly suitable as compatibility agent, for example, Joncryl ^® ADR 4368. Particularly preferred copolymer blends therefore contain

(a) 20 to 90% by weight, preferably 30 to 50% by weight, particularly preferably 35 to

45% by weight of a biodegradable, aliphatic-aromatic polyester,

(B) 80 to 10 wt .-%, preferably 70 to 50 wt .-%, particularly preferably 65 to

55 wt .-% of one or more polymers selected from the group consisting of polylactic acid and polyhydroxyalkanoate and

(C) 0 to 2 wt .-% of an epoxy-containing poly (meth) acrylate.

The polylactic acid of group (b) is preferably one which has the following property profile:

a melt volume rate MVR at 190 ° C. and 2.16 kg according to EN ISO 1133 of 0.5 to 100 ml / 10 min, preferably 5 to 70 ml / 10 min, particularly preferably 9 to

50 ml / 10 min,

a melting point below 240 ° C,

a glass transition point (Tg) greater than 55 ° C,

- a water content of less than 1000 ppm,

a residual monomer content (lactide) of less than 0.3 wt.% And

a molecular weight greater than 10,000 daltons.

Preferred polylactic acids are, for example NatureWorks ^® 6201 D, D 6202, D 6251, D 3051, and particularly 3251 D (polylactic acid from. Nature Works).

Polyhydroxyalkanoates of group (b) are understood to mean primarily poly-4-hydroxybutyrates and poly-3-hydroxybutyrates, furthermore copolyesters of the abovementioned hydroxybutyrates with 3-hydroxyvalerates or 3-hydroxyhexanoate are included. 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 Fa. Kaneka. 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 ^®.

The polyhydroxyalkanoates generally have a molecular weight M _{w of} from 100,000 to 1,000,000 daltons, and preferably from 300,000 to 600,000 daltons. Such polymers and polymer mixtures are distinguished by the fact that they are biodegradable and are suitable for coating paper products, as are suitable in the earlier European application with the file reference EP 0901388.8. Moreover, in the process according to the invention, they are distinguished by the polymers and polymer mixtures in that they can be completely separated off from the paper products sized and / or coated therewith, so that the paper product can be recycled. In principle, the method according to the invention is suitable for all types of paper which are glued and / or coated with biodegradable polymers. In particular, the method according to the invention is suitable for recycling paper products sized and / or coated with biodegradable polymers, which are known as

single- or double-coated paper products for foodstuffs (for example, fresh food),

Paper bags for dry foods such as Coffee, tea, soup powder, sauce powder; for liquids such as e.g. Cosmetics, Detergents, Beverages, Dairy products,

Tube laminates,

- paper bags,

Paper laminates and coextrudates for ice cream, confectionery (for example chocolate and cereal bars),

Paper tape,

Cardboard cups (for example paper cups for cold and hot drinks), yoghurt cups, - menu cups,

wrapped cardboard containers (cans, barrels),

wet-strength or moisture-resistant cartons for outer packaging (wine bottles, food),

Fruit crates made of coated cardboard,

- fast food plates,

Clamp Shells,

Beverage cartons and cartons for liquids such as detergents and cleaners, frozen food cartons, ice packs (eg ice cream cups, conical ice cream waffle wrappers),

- paper labels and banderoles,

Flower and plant pots,

Special papers (eg sandpaper, filter paper)

can be used. The following examples are intended to illustrate but not limit the present invention.

Examples In the examples, the following papers were used which were prepared from 100% pulp by the method as described in the earlier European application with application number EP 09010388.8. These papers had a thickness of in each case 400 μm and were coated with different polymers (all MVR values used below are determined according to EN ISO 1133 (190 ° C., 2.16 kg weight)):

Paper 1

Paper coated with Ecoflex ^® FBX701 1 (polybutylene adipate-co-terephthalate having an MVR of about 3 cm ^3/10 min, BASF SE), layer thickness 20 μιτι

Paper 2

Paper coated with Ecoflex ^® FS (polybutylene sebacate-co-terephthalate having an MVR of about 3 cm ^3/10 min, BASF SE), layer thickness 20 μιη paper 3

Paper coated with a mixture of 55% Ecoflex ^® FBX7011 and 45% polylactic acid, with a MVR of 10 cm ^3/10 min, BASF SE, layer thickness 20 μιη

Paper 4

Paper coated with Ecoflex ^® FBX7011 (BASF SE), layer thickness 50 μιτι paper 5

Paper coated with a mixture of 55% Ecoflex ^® FBX7011 and 45% polylactic acid, with a MVR of 10 cm ^3/10 min, BASF SE, layer thickness 40 μιη

Comparative paper 1

Paper coated with polyethylene, layer thickness 20 μm Example 1

In a 250 ml flask, in each case 4 g of the described papers (about 1 × 1 cm ² ) and 100 ml of aqueous solution (containing 1% by weight sodium hydroxide solution and 2% by weight sodium silicate) were vigorously stirred at 50 ° C. (stirring speed 300 rpm). The pH of the mixture was 10. Each time after 15 and after 30 minutes, the condition of the test pieces was visually examined. The results are summarized in Table 1.

Table 1

Recycling polymer-coated paper in alkaline medium

Condition after 15 min condition after 30 min

Paper 1 A A

Paper 2 A A

Paper 3 A A

Paper 4 A A

Paper 5 AA Comparative paper 1 BB

In Table 1,

A = complete decomposition of the paper to pulp fiber, complete decomposition of the polymer films

B = complete decomposition of the paper to pulp fiber, no decomposition of the polymer films, film completely inert and floats.

Example 2

The following solutions were used:

Solution 1

0.1% strength by weight aqueous solution of lipase from Candida antarctica solution 2

0.1% by weight aqueous solution of Rhizopus arrhizus lipase

In a 250 ml flask, in each case 4 g of the described papers (about 1 × 1 cm ² ) and in each case 100 ml of one of the aqueous lipase solutions described were stirred at 40 ° C. (stirring speed 100 rpm). After 30 minutes and after 1 hour, the condition of the specimens was visually examined. The results are summarized in Table 2.

Table 2

Recycling of polymer-coated paper in the presence of a lipase

In Table 2,

A = detachment of the polymer film from the paper, complete decomposition of the polymer films B = no change, paper further coated with polymer film or only partially detached but not decomposed

Claims

claims

Process for recycling paper-sized and / or coated paper products, in which the paper products sized and / or coated with polymers are placed in an aqueous waste paper suspension, this waste paper suspension a) is whipped in the presence of at least one hydrolase, b) is beaten in an alkaline medium , and / or c) is treated in an alkaline deinking process, and the polymers are subsequently separated from the waste paper suspension, characterized in that the polymers are biodegradable polymers.

A method according to claim 1, characterized in that the hydrolase is a carboxyesterase [3.1.1.1] and / or a lipase [3.1.1.3] and / or cutinase [3.1.1.74].

A method according to claim 2, characterized in that it is a lipase and / or cutinase from Achromobacter sp., Aspergillus sp., Candida sp., Candida antectica, Mucor sp., Penicilium sp., Geotricum sp., Rhizopus sp , Rhizopus arrhizus, Burkholderia sp., Pseudomonas sp., Pseudomonas cepacia, Thermomyces sp., Porcine pancreas or wheat germ, and carboxyesterases from Bacillus sp., Pseudomonas sp., Burkholderia sp., Mucor sp., Saccharomyces sp., Rhizopus sp., Thermomonospora fusca, Thermobifida fusca, Fusarium solani, Thermoanaerobium sp., Pig liver or horse liver.

A method according to claim 1, characterized in that the hydrolase is a polyhydroxyalkanoate depolymerase and / or a proteinase K.

Method according to one of the preceding claims, characterized in that the total amount of hydrolase used from 0.001 to 40 wt .-%, based on the total solution.

Method according to one of the preceding claims, characterized in that the waste paper suspension is pitched in a pulper or drum dissolver.

A method according to claim 1, characterized in that the pH of the waste paper suspension in the alkaline medium is between 8 and 12.

8. The method according to claim 1 or 7, characterized in that the waste paper suspension is added to adjust the pH with a base selected from the group of alkali and alkaline earth metals.

9. The method of claim 1, 7 or 8, characterized in that the waste paper suspension is pitched in a pulper or drum reel.

10. The method according to claim 1, characterized in that the deinking process is the flotation deinking process or the washing deinking process.

11. The method according to claim 1 or 10, characterized in that the pH of the waste paper suspension in the alkaline medium is between 8 and 11.

12. A method for sizing of paper products, characterized in that are used as polymeric sizing agent biodegradable polymers.

13. The method according to claim 12, characterized in that the biodegradable polymers are used as a mass and surface sizing agent.

14. The method according to claim 12 or 13, characterized in that the biodegradable polymers are used as engine size in the range of 0.05 to 1 wt .-%, solid, based on the dry pulp.

15. The method according to claim 14, characterized in that the addition of the biodegradable polymers takes place as a sizing agent in the thick material or in the thin material.

16. The method according to claim 12 or 13, characterized in that the amount of biodegradable polymers as surface sizing agent in the range of

0.0005 to 3.0 g / rri ² .

17. gelled paper products prepared by a process according to claims 12 to 16.

18. The method according to any one of claims 1 to 16, characterized in that as biodegradable polymers aliphatic-aromatic polyesters are used which i) 40 to 70 mol%, based on the components i to ii, of one or more

Dicarboxylic acid derivatives or dicarboxylic acids selected from the group consisting of succinic acid, adipic acid, sebacic acid, azelaic acid and brassylic acid, ii) 60 to 30 mol%, based on the components i to ii, of a terephthalic acid derivative, iii) 98 to 102 mol%, based on the components i to ii, of a C 2 -C 8 -alkylenediol or C 2 -C 6 -oxyalkylenediol, iv) from 0.00 to 2% by weight, based on the total weight of components i to iii, of a chain extender and / or crosslinker selected from the group consisting of a di- or polyfunctional isocyanate, isocyanurate, oxazoline, epoxide, carboxylic anhydride and / or an at least trifunctional alcohol or an at least trifunctional carboxylic acid, v) from 0.00 to 50% by weight, based on the total weight of components i to iv, of an organic filler selected from the group consisting of natural or plasticized starch, natural fibers , Wood flour and / or an inorganic filler selected from the group consisting of chalk, precipitated calcium carbonate, graphite, gypsum, conductive carbon black, iron oxide, calcium chloride, dolomite, kaolin, silica (quartz), Na from 0.00 to 2% by weight, based on the total weight of components i to iv, of at least one stabilizer, nucleating agent, glid- and release agents, surfactants, waxes, antistatic agents, antifoggants, dyes, pigments, UV absorbers, UV stabilizers or other plastic additives and a melt volume rate (MVR) according to EN ISO 1133 (190 ° C, 2.16 kg weight) of 3 to 50 cm ^3/10 min have.

19. Process according to claim 18, characterized in that the biodegradable polymers are copolymer blends which

(a) 5 to 95% by weight, preferably 30 to 90% by weight, particularly preferably 40 to 70% by weight, of a biodegradable aliphatic-aromatic polyester and

(B) 95 to 5 wt .-%, preferably 70 to 10 wt .-%, particularly preferably 60 to 30 wt .-% of one or more polymers selected from the group consisting of polylactic acid, polycaprolactone, polyhydroxyalkanoate, chitosan and gluten and one or polyesters based on aliphatic diols and aliphatic / aromatic dicarboxylic acids, such as, for example, polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene succinate sebacate (PBSSe), polybutylene terephthalate-co-adipate (PBTA) and

(c) 0 to 2% by weight of a compatibilizer contain.