DE4429269A1 - Process for the production of articles from thermoplastic amylose, molding compound for carrying out the process and molded part - Google Patents

Abstract

The invention proposes a simple way of using thermoplastic amylose, in particular amylose made from peas, in the manufacture of articles, in particular injection-moulded articles. The method makes use, in particular, of a moulding compound which includes a hydroxy-group-containing and/or fatty-acid-containing agent that gives optimum products in an injection-moulding process. A particular advantage of the invention is that foamed amylose products can also be manufactured.

Description

The present invention relates to a method for manufacturing provision of objects made of thermoplastic amylose, especially pea amylose, according to the preamble of An Proverb 1, a molding compound according to the preamble of the An Proverb 12 and a molded part according to the preamble of the An Proverbs 16

Due to the increasingly scarce resources available position of plastics of all kinds as well as increasing Problems with the environmentally friendly disposal of plastic fen which, for example in the case of halogenated ver Bindings like polyvinyl chloride are hardly possible in attempts have often been made in the past growing raw materials as raw materials for environmental use inert materials.

As such renewable raw materials, for example Cereals and vegetables are proposed, which are high Polysaccharide content, especially a high starch content, exhibit.

A major problem with industrial raw materials use was due to the fact that the in these herbal Biopolymers contain raw materials on the one hand low salary and on the other hand not like the synthetic polymers in plastics processing Industry could be processed.

Another problem lies in the fact that so far be known biopolymers, such as proteins or polypeptides, poly nucleotides and polysaccharides, which can be found in various vegetable  and animal raw materials occur, only extremely have low resistance to moisture.

Because of the polymeric structure of the starch, these natural polymers as raw materials for a new one to use developing natural product polymer chemistry.

Various methods have been developed to get out of the to isolate various types of plants starch.

In practice, however, it has been found that strength, how it can be isolated from plants in general, has neither thermoplastic properties nor in ir kind of way with those in plastics technology The usual methods can be processed into molded parts which are capable of both moisture and to withstand mechanical stress.

Another disadvantage of strength is that they are highly viscous and strongly adhesive when in contact with water Forms masses, so that, for example, spraying through nozzle is impossible in the water-containing state.

For example, it is known that starch is a basic material for Paste - i.e. adhesives in the form of aqueous swelling pro products, which, in contrast to glues, are already slightly lower Base material concentration a highly viscous, not stringy existing mass forms - form. For those sticky ones Amylopectin is responsible for the creation of starch is an integral part of strength.

In addition to the amylopectin, which occurs in nature Strengthen amylose. This amylose is in the in the Amylopectin starch structures found in nature envelops. Chemical structural analyzes of starch have shown that amylopectin, also called starch granulose, is a strong one branched polysaccharide with molecular weights between  300,000 and 2 · 10⁶ or up to 10⁹. As a result of α-1,6-glycosidic bonds, which result in strong molecule Branches lead to amylopectin relatively frequently it largely resists attack by the enzyme β- Amylase, as it only reaches the so-called border dextrins splits. The α-amylase, on the other hand, converts amylopectin to maltose, Glucose and isomaltose. In addition, it is known that amylopectin is insoluble in cold water, but in hot water swells and forms paste, which cool solid.

Another chemical characterization of amylopectin it is that this with iodine-potassium iodide solution (so-called Lugol's solution) gives a brown-violet color.

In contrast to amylopectin, amylose forms which of Amylopectin is coated with an iodine-potassium iodide solution characteristic blue color, which is another character terization of the chemical difference between amylo pectin and amylose means.

The main difference is green det that the molecular structure of Amylose by Amy lopectin differs strongly, namely in particular by the unbranched structure of amylose, which leads to degradation Oligosaccharides by both α- and β-amylase equips. In addition, amylose has a characteristic tical helical structure, which is rotated around certain angles of C-C single bonds come about and to the characteristic helical conformation leads, their spatial training by amylopectin because of its branched structure is not possible.

In addition, the average molecular weight is importance of amylose between 50,000 and 150,000, however from up to approx. 10⁶.  

Based on the above, there is a clear che Mixing difference between amylapectin on the one hand and Amylose, on the other hand. In addition, in the classic literature based on light and electron microscopy However, studies often do not distinguish between starch on the one hand and their components amylopectin and amylose on the other hand. However, this view is based on due to the biochemical and polysaccharide shown above chemical explanations wrong and thus outdated.

The structural chemical differences between Amy Iopectin and amylose are illu marked:

From the figure above it is clearly evident that amylopectin has additional α-1,6-glycosidic bonds, which make up the strong branches of amylopectin, while rend polymeric amylose only linear α-1,4-glycosi  dische bonds and thus unbranched chains with helical spatial structure.

This more recent chemical elucidation of the differences between For example, amylopectin and amylose are also used taken into account by the new EC starch regulation, wel che amylose rightly not considered a starch.

A general process for making starches Vegetable products are described, for example, in DE-A-29 22 247 described.

In addition, EP-A-0 376 201 discloses biologically buildable products from a starch with a high amylose proportion, the strength obviously according to classic Cleaning process for starch was made.

A disadvantage of those described in this prior art Starch with a high amylose content is due to the fact that for the production of products, e.g. B. by extrusion, Injection molding, etc., in any case up to 15 wt .-% egg Nes alkylene oxide with 2 to 6 carbon atoms added have to be if amylose contents of 45% by weight should be stepped.

However, the entire Kon accept the renewable raw materials, which are too biological buildable products, upside down, because here with extremely toxic chemicals so a natural product delt must be processed into commodities can be tet.

That this is not the point of making counter-use booths from natural products, which are fully biodegradable should be, can be, is a matter of course to the expert clear.  

In comparison to this prior art, the German Patent application P 43 01 586.7 for the first time the isolation of a largely pure amylose, which thermoplastic Eigen shafts, and with what items with the help of processes common in plastics technology, such as Extrusion, injection molding and the like, utility item stands of all kinds can be manufactured.

In the case of products made from amylose, the aspect of renewable raw materials and full biodegradation availability of these products interesting.

In practice, however, it has been found that many products - such as drinking cups for the Single use as well as foils and packaging materials - with a rather firm consistency and excellent quality can be produced, but for example softer more flexible molded parts or even foamed molded parts with rei ner amylose could not be produced.

Based on this state of the art, it was therefore the task of the present invention to provide a method which is also the production of flexible and / or foamed molded parts that are still full are biodegradable.

Technically, this task is characterized by the nenden features of claim 1 solved. Regarding one Molding composition for carrying out the method according to the invention the above task is characterized by the characteristics of claim 12 solved and in terms of a molded part the task is ge by the features of claim 16 solves.

By the inventive method according to claim 1 it is possible that amylose, preferably in the form of a Granules, for example processed in injection molding machines  can be tet, the Shore hardness of the desired Pro product both through physical parameters of the processing tion process, for example the injection molding process, such as for example pressure and temperature, especially spray pressure and dynamic pressure, as well as by chemical parameters, such as the concentration of the hydroxyl group and / or fatty acid can be adjusted.

By setting these parameters, almost all are the hardness ranges of the resulting required in practice Amylose product, from soft and flexible to hard and brittle, adjustable as required.

A particularly advantageous consistency of the molding compound and of the resulting amylose product is achieved when at for example glycerin as an agent containing hydroxyl groups is used.

However, if a largely water-resistant product is available is to be, is a fatty acid, at for example soybean oil and / or oil from lupine seeds, preferred.

A particular advantage of the method according to the invention is based on the fact that foamed amylose products can manufacture.

The production of foamed amylose products functio preferred when injection molding, when the spray nozzle not to a dynamic pressure common in plastics technology is set to be significantly greater than atmospheric pressure but when in the tool in which the amylose form mass is pressed to the atmospheric pressure of approx. 1 bar is brought, and the molding material under high pressure is expanded into the mold against this pressure.

However, if you want to receive non-foamed products, do so is usually expanded against a so-called back pressure  dated, for example in the order of 20 bar can lie.

In this case, water and glycerin are as hydroxyl groups Pen-containing agents preferred. This is all the more surprising than conventional thermoplastics in front of one Injection molding must be dried, because there is a What content of 2% unwanted bubbles in the manufactured Form molding.

However, with the present method it is possible to About a third, based on the molding compound, of water clog, with a good mold filling without essential Blistering results.

Thus, by adding suitable hydroxyl groups connections the properties of plasticized and cooled processed amylose material who changed the.

As already shown above, it was surprisingly highlighted found that, contrary to processing syn conventional thermoplastic, such as PP, SB, PS, ABS, PC, PMMA etc., not for blowing during injection molding and extrusion lead education when one of the method of the invention turns.

It should also be noted that the present inven used approximate "approx." - an are given, since it is well known to the person skilled in the art that nature fabrics and the associated analytics certain swan subject to changes.

Amylose is preferred for the purposes of the present Invention obtained from high-amylose pea varieties, wherein so-called marker peas are typically used, wel  che a particularly high amylose content, preferably to 93% by weight.

Amylose products obtained from such pea varieties white sen generally have the advantage that they are thermoplastic egg properties and thus with those in plastics processing processing technology usual processes to form parts can be processed. This means that none time-consuming mechanical retrofitting of the existing ones plastic processing industrial plants is required so that such products already from this side of the host Consideration of economic feasibility from who manufactured that can.

In addition, there is a particular advantage of the invention appropriate amylose products, especially molded parts, therein be establishes that the price per kilo is of the order of magnitude common plastic thermoplastics lies, at the same time there is no dependency on the raw material "petroleum", son on the contrary, the increasing demand due to renewable Raw materials can be covered, especially in the context of European Community farmers here one get a cutting new task. For example So many peas are grown on about 400 hectares that the harvest a total of about 1.2 tons of amylose results.

It is of extraordinary economic importance tion that the objects of the present invention are full are constantly composed of natural products and therefore are essentially completely biodegradable, so that there are no disposal problems like this with typical Plastic parts are the case.

Rather, the molded parts according to the invention by com positioning, feeding to farm animals, digging into the Er de, not just be disposed of biologically, but above  in addition, they provide a benefit in the sense of a Fertilizer or feed, as ubiquitous in nature occurring bacteria, fungi and other organisms the Amy loose and the hydroxyl groups used according to the invention use containing agents for their own food and thus again in mineral substances usable for plants while animals have the enzymatic apparatus to To gain energy from amylose.

Since it is in the means of the inventive method manufactured molded parts chemically around multiple sugar delt, there are also no toxicological considerations think with regard to application in the food sector and / or disposal.

The moldings according to the invention can for example for Packaging materials, for the manufacture of disposable tableware and in particular for the production of parts for the interior cladding of cars can be used.

The measures of claim 2 have the advantage that with the hydroxyl-containing agents listed there on the other hand, biodegradable molded parts can be produced and on the other hand the properties, especially hardness, Rigidity, tensile strength, etc., of the molded parts produced are adjustable.

The measures of claim 3 have the advantage that here a number of vegetable raw materials are available with which plasticity and The consistency of the desired molded parts can be set can and on the other hand they have the advantage that esp especially for molded parts that have increased resistance to This group of fatty acids must have moisture are essentially insoluble in water, so that they do not move out of the Molding can be leached, such as this  with water-soluble compounds containing hydroxyl groups may be possible.

The measures of claims 4 and 5 have the advantage that the molding composition according to the invention with all in the Plastic technology usual processes are processed can, with injection molding being preferred.

Claims 6 and 7 indicate preferred, but not a restrictive injection molding parameters again, with which advantage adhesive molded parts with favorable properties can be.

Claims 8 and 9 give preferred quantitative information for the hydroxyl group-containing agent.

The sub-claims 10 and 11 give a preferred procedure ren for foaming the molding compound according to the invention again.

It was a surprising finding that a ge white water content of amylose - contrary to all Re of conventional plastic processing technology - can be foamed when the plasticized molding compound is expanded against atmospheric pressure and a certain Has water content.

For example, injection molded foam parts be produced by an open mold, wel have a uniform bubble structure if the Molding compound has about 7% glycerin and about 16% water.

However, it is also possible to inject additional Water in the nozzle or at least near the nozzle Reduce density.

Of course, instead of injecting water, too the injection of inert gases such as CO₂, N₂, noble gases or  Water vapor can be used to special when needed To produce foam parts.

From WO 94/00512 it is known, for example, a ba sische aqueous solution to produce an amylose and this Solution then with enormous chemical effort, as with for example adding a surfactant, cross crosslink, foam stabilizers, etc., mechanically foam, which then becomes products for medical purposes leads, whose cost / benefit analysis only by academic In can be of interest and for a large-scale industrial pro production is certainly unsuitable.

However, it is not possible to use the Technically produced amylose foam, for example in a Injection molding machine to process and thus molded form parts to produce, because the aqueous foam here first is produced and then no longer technically can be processed, but only dried can be processed into medical products becomes.

In addition, WO 92/16584, for example, discloses biodegradable starch compositions, wherein a composition from a melt of another poly mers is produced, and the melt then added starch is set.

Thus, the present invention, and particularly the Possibility of claim 10 for the first time a molded part made from foamed amylose.

Claim 12 describes a molding composition according to the invention Amylose for performing the method according to the invention.

The further subclaims represent preferred embodiments form the molding composition of the invention.  

Claim 16 includes a molded part according to the invention, wel ches is obtainable by the process according to the invention.

The subclaims 17 and 18 represent preferred molded parts represents.

However, it should be noted that the manufacture of Molded parts with the molding compound according to the invention only can be obtained by way of example with an injection molding process can.

Of course, the processing of the invention molding compound, for example in extrusion plants, Extrusion blow molding machines, injection molding machines, injection blow molding machines gene, roll melting plants, calender lines and similar Devices for processing thermoplastic materials possible.

Further advantages and features of the present invention result from the description of execution examples play.

example 1

For the production of a molding composition according to the invention from Amy is loosened an amylose granulate which, for example, ge according to a procedure of the German patent application P 43 01 586.7 can be made to the full in this regard reference is made to the content.

As an agent containing hydroxyl groups, trap is used in the example a mixture of approx. 7.3% by weight glycerin and approx. 16% by weight Water, based on the total molding compound from amylose, ver turns.  

This composition results in injection molding on the one hand a good mold filling and blisters will not educated.

Commercially available art is used as an injection molding machine spraying machines for thermoplastic materials ver turns, with a spray pressure of approx. 1500 bar at a Spray speed of 120 mm / s is used. For Promotion of the molding compound or to build up the spray pressure screw conveyors are used. However, too of course the use of piston spray pouring devices possible.

Example 2

A molding composition according to Example 1 is produced with the Provided that the water content is approximately 32% by weight, based on the molding compound is, with otherwise the same glycerine rings stop. The injection molding parameters are the same as in Bei game 1.

This also results in a molding composition excellent filling of the mold and it finds no significant blistering takes place.

Example 3

The present example is intended to demonstrate how by adding suitable hydroxyl group-containing compounds the properties of plasticized and cooled processed molding compound can be changed.

It becomes an injection molding device as in Examples 1 and 2 used using the same injection molding pa parameters as in Example 1 and then under different compositions as glycerin or water  hydroxyl-containing compound used, and the Shore hardness measured according to DIN 53 505 or ASTM D2240 / 64T.

The relationship between the quantitative composition of the Hydroxyl group-containing agent - in the example, glycerin or water or a mixture of both - and the achieved Table 1 shows the Shore hardness.

Table 1

As can be seen in Table 1, the result is increasing Water content an increase in hardness.

A particularly soft product is obtained in the example case ten, if you add about 23 wt .-% glycerol without additional addition be used by water, with Shore hardness increasing by 55 ben.

Example 4

In the present example, only glycerin is used as added hydroxyl group-containing agent to the amylose and based on the spray parameters, how the resulting Molding compound is processable. The results are in Tab. 2 reproduced.  

Table 2

Spray parameters

Example 5

In the present example, an amylose granulate is used as a hydroxyl-containing compound, a polyethylene glycol added and as a fatty acid compound an epoxy added soybean oil and an oil from lupine seeds, the weight percentages of the polyethylene glycol at approx. 10 % By weight, based on the molding composition, and the mixture from soybean oil and lupine oil is also approx. 10% by weight.

With such a molding compound can be in Example 1 described injection molding conditions molded parts Produce amylose, which also has a hardness by the proportion of the fatty acid-containing agent - here Soybean oil and lupine oil - can be adjusted.

A particular advantage of fatty acids is to mention that these are usually not water soluble and the molded parts produced with such a molding compound  increased resistance to moisture and Have wetness, since hardly any leaching of the fatty acid content due to a damp environment.

In Fig. 1, the mold filling capacity in percent compared to the glycerol content in percent, based on the molding composition, is carried. This shows that very good mold filling properties of up to 100% can be achieved with glycerol as the hydroxyl-containing agent if the glycerol content is approximately over 17% by weight.

This is below about 10% by weight of glycerin Mold filling capacity also in about 100% if additional Water with a content of about 16 to 32 wt .-%, based on the molding compound, is added.

It is thus with the inventive method and the Molding composition according to the invention possible for the first time, molded parts Large-scale production of amylose, which in their hardness through physical parameters on the one hand and chemical parameters on the other hand are adjustable and wel can be completely biodegraded.

Claims (18)

1. A process for the production of articles made of thermoplastic amylose, in particular peas loose, by means of a device which puts the amylose under increased pressure and temperature, so that the amylose becomes moldable; characterized in that the amylose is mixed with a hydroxyl group-containing and / or fatty acid-containing agent before or during its processing. 2. The method according to claim 1, characterized in that the hydroxyl group-containing agent is selected from the group consisting of:
Alcohols, especially alcohols with several hydroxyl groups, preferably glycerin, polyethylene glycol; their alkyl ethers with free hydroxyl groups, especially methyl, ethyl and propyl ether; their esters with lower alkanoic acids, especially acetic acid; Monosaccharides, in particular glucose, fructose, lactose; Disaccharides, especially sucrose; Oligosaccharides, in particular special trisaccharides; concentrated aqueous solutions of the saccharides; Saccharide ethers, especially methyl, ethyl and propyl ether; Water;
as well as their mixtures. 3. The method according to claim 1, characterized in that the fatty acid-containing agent is selected from the group consisting of:
Vegetable oils, especially soybean oil, preferably epoxidized soybean oil, oil from lupine seeds, sunflower oil, olive oil, nut oil, rapeseed oil; whose esters with lower alcohols, in particular esters with alcohols which have several hydroxyl groups, preferably glycerides, particularly preferably di- and triglycerides; Saccharide ester;
as well as their mixtures. 4. The method according to any one of claims 1 to 3, characterized in that the device is selected from the group consisting of:
Extrusion systems, extrusion blow molding systems, injection molding systems, injection molding systems, injection blow molding systems, roll melting systems, calender lines; and the same. 5. The method according to any one of claims 1 to 4, characterized characterized in that the amylose by injection molding is processed. 6. The method according to claim 5, characterized in that the amylose injection molding at an injection pressure of up to approx. 1800 bar, in particular approx. 1200 to 1800 bar, preferably about 1500 bar, and a dynamic pressure from approx. 20 to 380 bar, in particular approx. 20 bar, is carried out. 7. The method according to any one of claims 1 to 6, characterized characterized in that the temperature during injection molding approx. 90 to 120 ° C and the spraying speed is approx. 50 to Is 120 mm / s.   8. The method according to any one of claims 1 to 7, characterized characterized in that as a hydroxyl group Medium glycerin is used, the proportion of which the molding compound based on its total weight of approx. 15 to 25 wt .-%, in particular about 23 wt .-%, be wearing. 9. The method according to any one of claims 1 to 8, characterized characterized in that as a hydroxyl group Medium a mixture of glycerin and water ver is used, the glycerol content in the form mass based on their total mass in particular from about 5 to 15% by weight, preferably about 7% by weight, is, and the proportion of water in the molding composition be drew on their total mass in particular of approx. 10 up to 35% by weight, preferably about 15% by weight. 10. The method according to any one of claims 1 to 9, characterized characterized in that the amylose is foamed. 11. The method according to claim 10, characterized in that expansion is achieved by Expandie ren the molding composition against atmospheric pressure, wherein Glycerin and / or water as hydroxyl group preferred agent is preferred. 12. Amylose molding compound for carrying out the process rens according to one of claims 1 to 11, characterized in that the molding compound contains and / or contains hydroxyl groups contains fatty acid.   13. Molding composition according to claim 12, characterized in that the hydroxyl group-containing agent is selected from the group consisting of:
Alcohols, especially alcohols with several hydroxyl groups, preferably glycerin, polyethylene glycol; their alkyl ethers with free hydroxyl groups, especially methyl, ethyl and propyl ether; their esters with lower alkanoic acids, especially acetic acid; Monosaccharides, in particular glucose, fructose, lactose; Disaccharides, especially sucrose; Oligosaccharides, in particular special trisaccharides; concentrated aqueous solutions of the saccharides; Saccharide ethers, especially methyl, ethyl and propyl ether; Water;
as well as their mixtures. 14. Molding composition according to claim 12, characterized in that the fatty acid-containing agent is selected from the group consisting of:
Vegetable oils, especially soybean oil, preferably epoxidized soybean oil, oil from lupine seeds, sunflower oil, olive oil, nut oil, rapeseed oil; whose esters with lower alcohols, in particular esters with alcohols which have several hydroxyl groups, preferably glycerides, particularly preferably di- and triglycerides; Saccharide ester;
as well as their mixtures. 15. Molding composition according to one of claims 12 to 14, there characterized in that the molding composition is foamable is.   16. molding, characterized in that it is after a Method according to one of claims 1 to 11 er is stable. 17. Molding according to claim 16, characterized in that the molded part is an injection molded part. 18. Molding according to claim 16 or 17, characterized records that the molded part is a foamed molded part is.