EP1732996A2

EP1732996A2 - Use of hydroxypropylated high amylose content potato starches to achieve high kit numbers

Info

Publication number: EP1732996A2
Application number: EP05716393A
Authority: EP
Inventors: Uwe Robben; Thomas Luck; Hermann Seyffer; Wolfgang Alois Hormuth
Original assignee: BASF Plant Science GmbH
Current assignee: BASF Plant Science GmbH
Priority date: 2004-03-31
Filing date: 2005-03-26
Publication date: 2006-12-20
Also published as: WO2005095117A2; JP2007532339A; US20080171213A1; KR20070009657A; WO2005095117A3; BRPI0509311A; CN1938389A; NO20064885L

Abstract

The invention relates to a method for the production of fat-resistant packaging materials with a kit number greater than 21, by the use of hydroxypropylated high amylose content potato starches.

Description

Use of hydroxypropylated high-amylose potato starch to achieve high KIT numbers

description

The invention relates to multilayer, fat-tight packaging materials with a carrier layer, which consist of paper / cardboard or other suitable, polymer-based substances.

Another object of the invention is a process for the production of fat-tight packaging material with a KIT number greater than 21 by using hydroxypropylated high-amylose potato starch with an amylose content of greater than 70%.

It has long been known to provide paper and cardboard containers with coatings that have a blocking effect on aromas or moisture / liquids. Patent application DE 41 09 983 A1 describes a flexible packaging container with a composite of a paper layer and a thermoplastic layer or film. The thermoplastic layer or film material consists of starch, a synthetic, non-polyolefinic, hydroxyl-containing polymer, e.g. an oxygenated polymer, as well as plasticizers of natural origin, e.g. starch-derived polyalcohols. This material can be melted by applying heat and is therefore extrudable. In patent application DE 41 37 802 A1 it is proposed to laminate a cardboard with a coated paper web in order to obtain a rotten, liquid-repellent product. The paper web should be coated on a starch basis. Patent application DE 42 94 110 discloses a coating dispersion which is produced from copolymers of oxidized starch and styrene, butadiene, acrylic acid or similar polymerizable molecules. This dispersion reduces the gas and water permeability of cardboard or paper.

However, it is often necessary to provide packaging materials with high fat tightness. For example, pet food, baked goods, confectionery and chocolate require packaging to have a particularly high level of fat tightness, which is indicated, for example, by the KIT numbers with values between 8 and 12. High KIT numbers stand for high grease tightness.

Corresponding paper / cardboard packaging commercially available has usually been subjected to a grease-repellent surface and / or bulk treatment. Fluoropolymers in particular are currently used for this bulk treatment or surface treatment, with up to 5% by weight of coating material reaching the material. Already fat densities> 6 to 8 can only be achieved by combinations of Layer and mass treatment can be achieved, fat densities with KIT numbers> 12 cannot be guaranteed with the current systems. For example, the packaging of dry animal feed with a low fat content (<10%) requires a treatment of the back in bulk, with a higher fat content a barrier is created by bulk treatment in combination with a surface coating.

Paper, cardboard and cardboard packaging is properly disposed of via the waste paper cycle. The halogen polymers used as a fat barrier thus get either into the new paper or into the process waste water via the paper preparation.

Starch ethers are known as auxiliaries and feedstocks in the paper industry. Properties used here are described in detail in the relevant literature. They are used in surface coating and coating as well as in pigmented paper coatings. According to the BGW, papers, boxes and cardboards approved for food contact may also contain starch ethers (e.g. hydroxyethyl and hydroxypropyl ether). Starch ethers are also used as a component of adhesives because of their good film-forming properties and their water-binding capacity. Literature on this can be found, for example, in Ulimann's encyclopedia of industrial chemistry; W. Baumann / B. Herbe, τg: Paper chemicals - Facts about environmental protection (Springer-Verlag); O.B: Würzburg:

Modified Starches: Properties and Uses (CRC Press).

WO 02/02412 describes multilayer packaging for greasy goods based on native, modified starch.

It is also known that starch ether derivatives can be processed into foils or films, primarily using a casting technique from an aqueous solution.

If the starch ethers are produced by the slurry process, the aqueous starch suspension is derivatized in alkaline at temperatures up to 50 ° C. The degree of derivatization is usually around 0.2. The preferred derivatization on the C2 atom is characteristic of these processes. Another method, which is known primarily from scientific studies (autoclave method), is based on alkaline-activated starch and, at lower dry substance concentrations, leads to more homogeneous derivatizations, although the degree of derivatization is set similarly. A procedure according to this strategy is described in patent application DE 4223471 A1, the starch ethers obtained in this way being used for film production, in particular for use as overhead, copier and printer films or for the surface finishing of specialty paper. as well as packaging material. In addition, it is mentioned in this publication that the ether derivative films mentioned can also be used in combination with other materials.

The object of the present invention is to provide fat-tight packaging materials with a very high number of KITs that are permitted under food law.

Surprisingly, it has been found that substrates which themselves do not have sufficient fat resistance, such as paper, cardboard, cardboard or other materials made from or with cellulose, are fat-tight if they are coated with alkylene oxide-derivatized starch with an amylose content of greater than 70% ,

The present invention therefore provides multilayer packaging for greasy goods or parts of such packaging, which have a carrier layer made of a polymeric material as the main component and at least one layer applied to the carrier layer that does not form the outside of the packaging, the layer applied to the carrier layer having one contains alkylene oxide-derived starch with an amylose content of greater than 70% as the main component. The alkylene oxide used for this can very suitably be a C ₂ -C ₆ alkylene oxide. C ₂ -C ₄ alkylene oxides are preferred.

The coating of a carrier material with the functional layer "high amylose (HA) - starch derivative" realizes a fat-tight composite system. The HA starch component is responsible for the fat tightness and also has the property of biodegradability. Such a starch can also be incorporated well into coating compositions for the stated purpose since, in contrast to native starch, it does not tend to re-aggregate (retrogradation).

The packaging of the present invention is not limited to specific configurations. An exemplary, preferred area of application is packaging of food and animal feed with low water contents and at the same time high fat contents, in particular folding boxes. Examples of this are packaging for biscuits, chocolates, other confectionery, dry animal feed, in which a particularly good barrier against the passage of water vapor is not necessary. However, packaging for fatty non-food (e.g. cosmetics, oil-based color pigments or the like) can also be designed according to the invention.

Further possible uses are in the coating of polymers other than cellulose with the material proposed according to the invention (for example other packaging plastics) for similar packaging tasks. The coating of paper in the sense of wrapping paper is also a possible application. With the packaging materials of the present invention, high grease-tightnesses can be achieved, which are in the range from a KIT number of 10, preferably at least 17, but as a rule significantly higher. Leakages of a KIT number of over 21 can be achieved, which cannot be guaranteed with the previous, non-biocompatible or - degradable systems.

Further advantages of the packagings according to the invention are that their manufacture is compatible with customary paper or cardboard manufacturing processes and that they are biodegradable, and they are particularly advantageous in terms of economic and / or ecological assessments compared to conventional systems, in particular if the factors price of the coating including process costs and the compatibility with the paper recycling process are to be considered.

Because of their biodegradability, the packaging coated according to the invention ensures good compatibility with the treatment and waste water purification options of waste paper disposal systems. Here, the degradation behavior in the paper cycle is a decisive advantage in terms of avoiding further entry of contaminants. Suitable materials for the backing layer are, in particular, paper, cardboard or cardboard, possibly in a mixture with other suitable substances or substances normally used in food packaging technology such as binders or dyes. However, other materials or plastics, preferably based on natural polymers such as cellulose or the like, can also be used.

HA starch derivatives suitable according to the invention are those which have been derivatized with an alkylene oxide such as ethylene oxide or propylene oxide or a longer-chain alkylene oxide. The attached groups increase the distances between the molecular chains and thus increase their mobility. The inner softening effect thus given can only be reversed by destroying the chemical bond.

The HA starch derivative should preferably form a closed film on the carrier layer. If this is the case, even very thin layers from about 6 g / m ² basis weight can be fat-tight, provided the carrier material has a relatively high smoothness.

The coating can be provided as a surface layer on the inside of the packaging and / or as an intermediate layer, possibly also with the function of an adhesive layer between paper or cardboard layers or the like. Several coatings applied directly on top of one another can also be advantageous. Likewise, a so-called primer (e.g. with conventional paper coating agents such as kaolin or starch), which has the purpose of pre-smoothing the surface. Basis weights for

Achieving a defect-free layer can thus be reduced if necessary.

The layer containing the HA starch derivative can optionally be applied to the carrier layer by applying a self-supporting layer made of this material. However, a solution or suspension of the HA starch derivative with a suitable amount of dry substance is preferably produced and applied to the carrier material, preferably from an aqueous solution or suspension. A very suitable amount of dry substance (TS) of the HA starch derivative is in the range from about 5 to about

50% by weight, preferably in the range from about 10 to about 40% by weight, the amount actually to be selected depending on the application method provided. In some cases, an amount down to 4% by weight may be sufficient.

The application can be carried out, for example, with a doctor blade, spraying or roller application, as well as by "die casting" a more concentrated solution and by applying a thermoplastic melt ("extrusion") over the surface. In all cases, the water content of the HA starch derivative should preferably be reduced to <25% by weight after application to the carrier material (for example by drying with IR or convective).

In addition to the HA starch derivative, the layer to be applied to the carrier layer can also contain other additives. On the one hand, the addition of pigments (as is generally the case in the paper industry) lends itself, on the other hand, the addition of glycerin, urea, borax, glyoxal or other additives with similar properties and effects in order to achieve desired values in terms of elasticity and water and achieve long-term stability. The KIT number can also be positively influenced in some cases by adding such substances, e.g. by adding glycerin or crosslinker (e.g. Glyoxal). However, the proportion of high amylose starch derivative should preferably always be so high that the formation of a defect-free film is ensured.

Potato starch with an amylose content of greater than 70% is preferably used as the starting material. A potato starch with an amylose content of over 70% can, for example, be isolated from genetically modified potato plants in which the enzymatic activity of the starch branching enzymes SBE I and II is reduced compared to the non-genetically modified starting plant. A method for producing plants of this type is described by way of example in Example 1. Further descriptions of the production of genetically modified potato plants with an amylose content of greater than 70% can be found in the patent applications WO 92/11375, WO 97/20040, WO 92/14827, WO 95/26407 and WO 96/34968 and the patents US 5,856,467 US 6,169,226 , US 6,469,231, US 6,215,042, US 6,570,066 and US 6,103,893. Potato plants with a reduced enzymatic activity of the starch branching enzymes SBE I and SBE II can alternatively also be obtained by selection of suitable mutagenized potato plants.

Starches with an amylose content of greater than 70% from other crops such as, for example, maize, wheat, peas or tapioca can also be used as starting materials. Plants with an amylose content of greater than 70% can be produced by genetic modification using molecular biological methods and / or by breeding and selection.

HA starch means a starch with an amylose content of at least 70%. The amylose content is preferably at least 80%, particularly preferably at least 90%.

The chemical modification of the potato starch with an amylose content of greater than 70% takes place, for example, with a C ₂ or C ₃ alkylene oxide. Propylene oxide is preferred.

Since the HA starch is suitably modified in the presence of base, but the mass intended for the coating should react favorably in about 3 neutral, so that normally neutralization with acid must take place, the modified HA starch is in the Usually heavily contaminated with salts. It is an advantage if this salinity is not too high. It is therefore recommended that the coating composition in the concentration provided for the application has a conductivity of no more than 4,000 - 5,000 pS / cm, preferably of <2,000 pS / cm.

The addition of acids and alkalis should be carried out from the point of view that the salt formed is harmless to food law. Suitable acids are phosphoric acids, a suitable base is sodium hydroxide solution. Desalination can be done, for example, by dialysis.

Coatings with higher derivatized HA starch show more favorable KIT numbers than those with lower degrees of derivatization. However, it is not necessary to achieve high levels of substitution, since even low levels can lead to positive effects. However, these also depend on the origin of the HA starch used. While a degree of derivatization of 0.05 to 1.5 may be suitable in general, ranges between 0.1 to 1.0, very particularly preferably between 0.1 and 0.3, are preferred.

A HA starch ether solution suitable as a coating composition or casting solution for the present invention can be prepared, for example, as follows: the starch with an amylose content of greater than 70% (for example wheat, corn, tapioca, Potato or HA pea starch) is stirred in approximately twice its weight in water for a few hours and then roughly freed from the water, for example by suction filtering. It absorbs about its own weight of water, so that it has about 40 to 60% dry matter. Then it is resuspended in about 1.5 times its wet weight and disintegrated by adding the same amount of about 10% base or lye. Immediately afterwards, about 25-75% by weight of alkylene oxide, preferably propylene oxide, based on the starting weight of the dry HA starch, are added within a few minutes to about 1 hour, with mild temperatures being maintained. Room temperature is well suited. The mixture is allowed to stir for several hours and then left to rest for about 20 hours; then it is neutralized with acid. If desalination is to take place, this is done, for example, by dialysis against water. The desalted solution is gently concentrated if necessary. The degree of derivatization of the HA starch is about 0.2 when using about 50% by weight of propylene oxide, in other cases correspondingly above or below.

Desalination or separation of disruptive inhomogeneities can also be carried out, for example, by means of ultrafiltration. If the product is too concentrated, it can be diluted with deionized water.

After adding the possibly desired additives (e.g. preservatives, fillers, antistatic agents, agents to improve elasticity, crosslinking agents), a mechanical separation can be carried out using a filter or centrifuge if necessary, and at the same time degassing of the solution to be processed can be achieved.

A coating solution which is particularly suitable for the purposes of the invention has the following rheological properties:

A dynamic viscosity of 0.1 Pas to 40 Pas at a temperature of 25 ° C and a shear rate of 30.7 s ^"1. Viscoelastic properties of the polymer solution, the ratio between the viscous and elastic content Tan K values between 1 and 10 ( max. 50) at a temperature of 25 ° C. and a shear rate of 30.7 s ^{' 1.} With the method mentioned as an example, such values can easily be obtained.

The method also offers the advantage that the HA starch is reacted and processed particularly gently and in particular continuously at relatively low temperatures (<60 ^° C.) or completely at room temperature, which has positive effects for the coating of the carrier material. Due to the cold water solubility after neutralization, separation, salt separation and concentration, the starch with an amylose content of 70% can be processed gently so that no or only insignificant degradation reactions occur. The aqueous casting solution can preferably be applied to the material web (paper) to be coated using a suitable application system (for example a doctor blade) at room temperature or slightly elevated temperatures.

The use of hydroxypropyl ether starches produced by the autoclave process, in particular from potato starch with an amylose content of greater than 70%, which have been found to be solutions with dry matter contents of 12 to 20% by weight and preferably with derivatization (DS) ) Degrees of 0.1 to 1.0, more preferably to 0.4, are used. Compared to commercial samples (coated with fluorocarboxylic acids), these show significantly better grease-tightness, especially in areas with kinks, which are particularly critical in folding box applications. Compared to the above-mentioned coatings according to the invention with commercially available starch derivatives, the basis weights used for coating with these starches can be reduced.

example 1

Production of transgenic potato plants with a high amylose content

Potato plants with an amylose content greater than 70% can be produced using antisense or RNAi technology with the aim of. To reduce or eliminate the enzymatic activity of the starch branching enzymes SBE I and SBE II.

For example, the HA starch producing transgenic potato line Solanum tuberosum AM99-2003 was produced in which the activity of the starch branching enzymes is inhibited. The genetic transformation of the starting variety Dinamo was carried out using a gene construct which contains gene fragments under the control of a GBSS promoter of SBE I and SBE II in an antisense orientation. PBIuescript contains a 1620 base pair fragment of the 3 'end of the SBE I gene between EcoRV and Spei is cut with Spei and Xbal and ligated with a 1243 base pair Sstl-Xbal fragment of the 3' end of SBE II. SBE I and SBE 2 Complex is cut out with the help of EcoRV and Xbal and ligated into the binary vector pHo3.1 opened with Smal and Xbal. The resulting vector is designated pHabe12A, see Figure 1 and nucleic acid sequence SEQ-ID No. 1.

PHo3.1 is based on pGPTVKan (Becker, D. et al., Plant Molecular Biology 20 (1992), 1195-1197) and additionally contains the 987 base pairs GBSS promoter (see EP 0 563 189) of the Hindill site of pGPTVKan cloned and its uidA gene was removed with the help of Smal and Sstl.

The parent line Dinamo is transformed with the construct pHAbe12A using the method described in US Pat. No. 6,169,226, and the transgenic lines on kanamycin-containing ones Media selected. The analysis of the amylose content of the transgenic plants was carried out according to the method described in (Morrison, WR and Laignelet, B., J. Cereal. Sci. 1 (1983), 9-20).

5 transgenic potato plants with an amylose content of at least 70% were selected and grown. The high amylose starch was isolated by conventional methods.

Example 2 10 Hydroxypropylation of Potato Starch Containing High Amylase

Potato starch containing high amylose obtained from genetically modified potato plants - see Example 1 - was hydroxypropylated on a laboratory scale. The potato starch with an amylose content of 70% was modified in accordance with an autoclave or homogeneous process.

After the hydroxypropylation reaction, the solution was prepared for the subsequent coating of cardboard by desalting and concentration. The end product should have a degree of derivatization of approx. 0.2, a dry content (w / w) of approx. 18% 20 and a conductivity of approx. 600 // S / cm.

In the course of the experiments on cardboard coating, different application weights were generated with the hydroxypropylated HA starch by hand knife application.

25. To coat the cardboard (from Cupforma), the HA starch was heated to 40 ° C. The HA starch solution was applied (once or twice) to the coated and uncoated side of the box.

Example 3 30 Characterization of the final product

Starting from 713 g HA starch from potato plants with an amylose content of 70% - produced according to the method described in Example 1 - became 1770 g hydroxyproply HA starch with a dry weight of 27 (w / w)% and a conductivity made from 880 // S / cm. The conductivity could not be reduced further by diafiltration. Example 4

Testing the grease tightness using the 3M-KIT test

In order to check the resistance to non-polar substances, the coating is tested for tightness against mixtures with 2 I test solutions of different concentrations of castor oil, toluene and n-heptane. The KIT solution with the highest number, which stood on the sample for 15 seconds without causing a breakdown or discoloration, is the characteristic KIT number.

Boxes from Cupforma were used.

The table summarizes the results.

In all three cases, the coating with a KIT number> 21 turned out to be fat-tight according to the KIT test according to 3M.

Example 5

713 g of potato starch with an amylose content of 70% are stirred in 1.3 l of distilled water for 4 hours and then sucked off. The moist starch is stirred up with 1.824 l of water and 1,811 g of 10% sodium hydroxide solution, obtained by mixing 376 g of 50%. NaOH with 1,505 g of water. The derivatization is carried out with 323 g of propylene oxide at 23 ° C., which is added with stirring within 20 minutes. The mixture is left to stir for a further 4 h and to rest for 20 h. It is neutralized with 40% phosphoric acid (approx. 700 g). The solution is then filled into dialysis tubes and dialyzed for approx. 4 days with daily water changes. The product is concentrated to over 20% dry matter using a vacuum rotary evaporator.

The HA starch ether obtained has a degree of derivatization of about 0.2. The conductivity of the coating material is around 1100 pS / cm.

The coating compositions below are produced analogously to this example and applied with a 20 // m doctor blade onto chromo duplex cardboard (GD2), 310 g / m ² , thickness approx. 420 // m, coated on one side. After drying the first a second layer is applied slowly (dry to the touch, approx. 2 h duration) and dried at room temperature and about 50% room humidity for about 1 week, possibly even longer.

The application mass is determined on three cardboard sheets of the coated samples by weighing (according to DIN 53 104: testing of paper and cardboard, determination of the basis weight, September 1971) and the thickness using a thickness measuring device (probe: flat / spherical, 30 SKT, MB = I μm). In addition, the KIT number for non-polar substances is determined according to the 3M KIT test. Solvent mixtures of castor oil, toluene and heptane are used as test liquids. The KIT solution with the highest number, which is on the sample for 15 seconds without causing a breakdown or discoloration, is the characteristic KIT number.

Claims

claims

1. Multi-layer packaging for greasy goods or part of such packaging, comprising a carrier layer made of a polymeric material as the main component and at least one layer applied to the carrier layer and not forming the outside of the packaging, which is a highly amylose starch derivative with an amylose content of at least 70% contains as the main component, characterized in that the highly amylose starch derivative is a starch derivative modified with a C ₂ -C ₆ alkylene oxide.

2. Multi-layer packaging according to claim 1, characterized in that the highly amylose starch derivative is a starch derivative modified with a C ₂ -C ₄ alkylene oxide.

3. Multi-layer packaging or part of such packaging according to claim 1, characterized in that the C ₂ -C ₆ alkylene oxide is propylene oxide.

4. Multi-layer ner pack or part of such a package according to one of the preceding claims, characterized in that the high amylose starch derivative is obtained by modifying optionally partially degraded corn, wheat, potato, HA pea or tapioca starch.

5. Multi-layer packaging or part of such packaging according to one of the preceding claims, characterized in that the degree of derivatization of the starch derivative is 0.1 to 1, more preferably 0.1 to 0.4.

6. Multi-layer packaging or part of such packaging according to one of the preceding claims, characterized in that the polymeric material of the carrier layer is a naturally occurring polymer, preferably cellulose.

7. Multi-layer packaging or part of such packaging according to one of the preceding claims, characterized in that the layer containing a high amylose starch derivative as the main component influences additional components selected from pigments, plasticizers, agents that increase long-term stability, agents that increase water stability and elasticity - Sending means, contains.

8. Use of a high amylose starch derivatized with a C ₂ -C ₆ -alkylene oxide as the main component of a layer of a multilayer packaging, which is applied to a carrier layer of this packaging from a polymeric material, in order to produce greaseproofness of the multilayer packaging.

9. Use according to claim 8, characterized in that the C ₂ -C ₆ alkylene oxide is propylene oxide.

10. Use according to one of claims 8 or 9, characterized in that the starch derivative is obtained by modification of high amylose potato starch and optionally has a degree of derivatization from 0.1 to 1, more preferably from 0.1 to 0.4.

11. Use according to one of claims 8, 9 or 10, characterized in that a highly amylose potato starch with an amylose content of at least 70% is used for modification.

12. Use according to one of claims 8 to 11, characterized in that said layer prefers additional constituents selected from pigments, plasticizers, agents which increase long-term stability, agents which increase water stability, agents which increase the KIT value and agents which influence elasticity selected from glycerin, urea, borax or glyoxal.

1.1

Figure 1

pHAbe12A 7756 bp