NL1007735C2 - Biodegradable mouldings e.g. pot - Google Patents

Abstract

Use of potato skins as starting material, instead of starch, in production of biodegradable moulded articles. Process comprises subjecting potato skins, preferably in presence of plasticiser, e.g., polyol or urea, to thermo-mechanical treatment, preferably comprising extrusion, followed by shaping, preferably carried out in presence of blowing agent such as steam or carbon dioxide. An Independent claim is also included for the moulding made of potato skin.

Description

Biodegradable moldings

The invention relates to moldings of biological residual material, such as potato steam peels.

For numerous applications, such as profiles, pipes, gutters, pots and other containers, there is a need for biodegradable moldings that can be manufactured from inexpensive materials. For such applications it has been proposed to process starch, optionally mixed with other polymers and fillers, and by shaping, for example, extrusion. Examples thereof are described in WO 92/02559 and EP-A-707034. However, such products have a number of drawbacks, including high production costs and high processing temperatures.

Surprisingly, it has now been found that potato steam husks can be processed in a relatively simple and inexpensive process into sturdy, yet readily degradable moldings. The method according to the invention therefore involves the processing of potato steam peelings or similar material by using thermomechanical treatment and shaping. It is believed that the combination of starch, cellulose, pectin and inorganic materials are responsible for the favorable mechanical properties of the moldings.

Potato peelings are used as the starting material, i.e. the residual material that is released during any peeling process of potatoes. The most common method of peeling 20 is steam peeling, in which potatoes are heated with steam under elevated pressure for about half a minute, after which the peels are removed from the potatoes with a water jet. The peeling material obtained thereby does not need to be further pretreated, at most residues of sand or earth are removed if necessary. Instead of or in combination with potato peelings, one can also start from residual material from other crops, such as cassava peels and wheat or other grain chaff.

In addition to the residual material, other biodegradable material can also be used, such as, starch, cellulose (derivatives), guar gum, locust bean flour, tarragon, pectin, gum arabic or other gums, natural rubber, polyesters such as polycaprolactone and polylactic acid, proteins such as gluten and casein. For cost reasons, this additive will generally be kept below 25% by weight relative to the skins. The peeling material can also be chemically modified, for example by oxidation.

1007735¾ 2

The peels can be comminuted prior to the thermomechanical treatment. This comminution can be done in any usual manner, for example by grinding, sieving, mashing, scraping. A plasticizer such as a polyol (glycol, diethylene glycol or another alkylene glycol or polyalkylene glycol, glycerol, glycerol monoester, etc.), citric acid ester or urea is then preferably added to the peels, but water alone may also suffice. The amount of water is preferably 3-35% by weight relative to the total degradable polymer. The amount of additional plasticizer such as glycerol is preferably 0-25% by weight. Furthermore, an emulsifying agent such as lecithin or a monoglyceride, a release agent such as an oil (e.g. castor oil), fatty acid or metal salt thereof (e.g. calcium stearate) can be added. In order to increase the strength or and / or the volume of the moldings, a filler material such as a natural fiber, for example flax, straw, elephant grass, cotton, jute or paper, can be added, for example in an amount of 5-50 wt. .% relative to the peeling material. Inorganic fillers such as lime or chalk can also be added. The addition of lime can further increase the water resistance of the final product by lowering the solubility of pectin. Other possible additives are dyes, preservatives, and in particular swelling or blowing agents such as sodium bicarbonate and nucleating agents such as talc.

The mixture of comminuted shells and additives is then thermomechanically treated. In addition, it can be granulated / pelletized in accordance with known granulation or pelletization processes, for example by extrusion in a twin screw extruder at elevated temperature (60-180 ° C, in particular 100-150 ° C). The size of the grains is determined by the speed of granulation and any grinding steps after granulation. Depending on the presence of other plasticizers, the water content during extrusion can vary from 3 to 35% by weight.

The product obtained can be conditioned at an optimum moisture content for the process. Depending on the content of other plasticizers, the moisture content after conditioning varies between 4 and 30%. Subsequently, the conditioned product can be placed in a mold with the shape of the final shaped article to be manufactured. If the conditioned product is in the form of granules, an amount of adhesive (for example, a mixture of a native starch and glycerol) 100773 5 "^ 3 can be added to promote adhesion between the granules during molding.

The molding can be done by casting, injection molding, pressing and the like techniques. If bulky products are desired, shaping can be done by foaming using a bias agent, such as carbon dioxide, lower alkanes or, in particular, water. A suitable manner of foaming is, for example, foaming using electromagnetic radiation, in particular that in the microwave region (frequency between 20 MHz and 10 GHz and in particular between 50 MHz and 5 GHz). Use is made here of the radiant energy absorption of water, glycerol or other dipolar substance present in the product, whereby this substance warms up in a very short time and turns into vapor form. Two processes take place simultaneously: firstly the foaming as a result of the evaporation of water or the other dipole-containing substance. The advantage here is that no thermal energy has to be supplied from the outside. Second, the loose material is "welded" together to form a three-dimensional foam molding. It is important for this that the outside of the granules is fusible, for which an at least partial thermoplastic behavior of the processed shell material is required. Such a foaming process should take place quickly, i.e. within seconds. This can be accomplished by using a high power (up to, for example, 50 kW) microwave source or by using a combination of microwave generator and die in which the pressure can be varied rapidly. After the material has thus been brought into the desired foam form, the mold is opened and the product is taken out.

The products obtained by the method according to the invention can have any desired shape. An important application is that of continuous moldings, such as profiles, tubes, gutters, plates, etc. Such moldings can be porous, for instance when used as an enclosure for an article to be swollen in water environment. Discontinuous objects such as pots, boxes, etc. can also be manufactured. An example thereof is a packaging means, for example for fragile devices, glassware, mail items, etc. The product can also be in the form of spheres, discs, etc., which can be used as filler in packaging. Advantages of this material are the naturally anti-static behavior, the fact that water-soluble variants are possible and the biodegradability and convertibility. In the case of foamed material, the low density is also an advantage for many applications.

Depending on the desired application, it may be useful to apply a protective layer to the resulting molding. Such a layer can for example be a wax layer or a polymer layer. Polymers that can be used for this purpose are thermoplastic or thermosetting polymers, depending on the processing and the application, such as a natural rubber or a polyester, preferably a degradable polyester such as a polylactic acid or poly-e-caprolactone.

Example 10 Drying the peels

Before the potato peels were dried, their moisture content was determined by putting 200 grams of peel slurry in an oven and leaving it at 120 ° C for 3 days. The moisture content was determined from the weight loss of the shell slurry.

The way in which the peels were dried was using a drum dryer. Wet skin slurry was scooped onto a drum at a temperature of 150 ° C, causing the water to evaporate and dry skin of potato slurry to form on the drum. The skin was scraped from the drum and collected.

Pressing

To investigate the flowability of the dried potato peels, some pressing experiments with dried product were performed. The press experiments were conducted with a Pasadema Hydraulics Inc. PHI 75U pers. The material was pressed for 10 minutes at a temperature of 110 ° C and a pressing pressure of 20 tons. The press was then cooled for 10 minutes, after which the product was removed from the press. The press experiments were performed with different glycerol and water contents. The glycerol and water contents were both varied from 0 to 20%.

Extrusion

The potato skins were granulated with 2 different extruders: 30 - the Berstorff ZE 40, a self-cleaning rotating twin screw extruder with a diameter (D) of 40 mm and a length (L) of 38 D.

1007735 · 5 the Extruco TSE 76, a form-fitting, counter-rotating twin screw extruder with a diameter (D) of 76 mm and a length (L) of 33.8 D.

Batches of about 5 kg were prepared per composition. The batches were first premixed for 10 minutes with a bear vari mixer (a kind of 5 large kitchen mixer, Peter Stuut). The premixes were added to the extruder with a hopper. The screw speed for the experiments was 35 ipm. The extrudate was collected in a container and chopped into granules with a granulator. During extrusion, the plasticizer type, the plasticizer amount, the type of waste shells and the amount of added lime were varied. io - plasticizer type: glycerol, urea plasticizer amount: 0, 5, 7.5, 10, 15% (based on the weight of the peel) type of peel: steam peel, homogenized steam cut material, gray starch (this is also potato steam peel waste product) 15 lime: 0, 5, 10%.

Injection molding

The injection molding of the various test bars was performed with an Ergotech NCIV injection molding machine. Injection molding of the flower pots was performed with a Demag D60NCII-K injection molding machine. The molds used were a mold for 20 test bars and a flower pot mold for thin-walled flower pots. The granulate types, made by extrusion, were dried before injection molding and processed at a temperature of 120 ° C. The injection molding pressure was between 1000 and 2500 bar, the cycle time was between 27 and 37 seconds, depending on the granulate type. The mold temperature was kept at 20 ° C.

The mechanical properties of obtained test bars are summarized in the table below. The E-modulus is a measure of the stiffness, Max. load the maximum force exerted on a bar during the bending test, L at max. load the elongation at the moment of maximum load and L at break the elongation at the moment of breakage of the material. All samples contained 3% lecithin.

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Table: Results bending tests composition mechanical properties glycerol urea lime E-modulus Max. load L on max. L at (%) (%) (%) (N / mm2) (N / mm2) load (%) fracture (%) 5 5 - - 72 1.8 6.8 13.1 7.5 - - 34 1.0 7.5 13.2 10 - 46 1.5 8.2 13.2 12.5 23 0.8 7.4 13.1 15 - - 29 1.1 8.7 13.2 10 25 6 0.3 9.0 13.4 - 5 10 10 0.4 12.0 20.8 - 10 10 6 0.3 11.8 23.0 5 10 6 0.3 11.1 19.0 10 3 ^ 35¾

Claims (9)

A method according to claim 1, wherein the thermomechanical treatment is carried out in the presence of a plasticizer, such as a polyol or a urea. The method of claim 1 or 2, wherein the thermomechanical treatment comprises extrusion. 4. Process according to any one of claims 1-3, wherein shaping is carried out in the presence of a blowing agent, such as water vapor or carbon dioxide. Process according to any one of claims 1-4, wherein 1-50 wt.%, In particular 5-25 wt.%, Of a fibrous material such as finely divided paper, straw, flax, elephant grass, cotton or jute is added to the potato steam peelings . 6. A method according to any one of claims 1-5, wherein the potato skins are mixed with a polysaccharide or a protein. A method according to any one of claims 1-6, wherein 0.5-5% by weight of lime is added to the potato steam peelings. A method according to any one of claims 1-7, wherein a layer of a wax or a polymer is applied to the shaped product. 1 2 3 4 5 6 - 5 ^> 9. Process according to any one of claims 1-8, wherein the polymer is brought into the form of the granules / pellets by extrusion. 3 A method according to claim 9, wherein the granules / pellets contain 5-25% by weight of water just before foaming. 5 II. Molding of thermoplastic treated potato steam peels, obtainable by the method according to any one of the preceding claims. COOPERATION TREATY (PCT) REPORT ON NEWNESS RESEARCH OF INTERNATIONAL TYPE OF LOAN IDENTIFICATION OF OE NATIONAL APPLICATION Characteristic * of the applicant at van ae gemacntigce j N.O. 41642 TM_ | Neoenanase Application No. | indieongsdaum j 1007735 December 8, 1997 | in 90 calls priority I - _ - - —'I "_ _ '' I Applicant (Name) RODENBURG VEEVOEDERS BV. j Da urn of the request for an examination of miaaaaiai type By oe insanse for International Research (ISA) reconciled to an onaerzoeic of intemaoonaa sewing type aegewnd nr. SN 30473 NL t I I. CLASSIFICATION OF THE SUBJECT (under Deceasing of versi ciassiAcaoes. specify all aassificaoes symbols) | According to the Inoemaoonafe aassi / icaoe (IPC> Int.Cl.6: C 08 B 30/10, C 08 L 3/00 II. RESEARCHED FIELDS OF TECHNIQUE _______ Unassigned minimum documentation _.___ | Classification system | ___ Classifications of freights _'_ j II Int.Cl.6: C 08 B, C 08 L ji _ i Unsupported ancillary documentation to the minimum documentation enter as far as such documents are subtracted So-called 1 included y; 1 1 i I i I 'III! I I_! J lil., NO UNCERVIEW SIMILAR FOR CERTAIN CONCLUSIONS (oomerxmaen oo sanvutlirgsolad) IV. LACK OF UNITY OF OUT FINDING (CcmerKtrcen cc supplementirtcsoiaa ',' v 2C '' a: Cc t 59m