The invention relates to a product using a polymer material and a percentage of cellulose material, as well as a method and a device for manufacturing this product.

The manufacturing of polymer products with the use of cellulose materials has been known for many years. Frequently used cellulose materials include wood dust or wood chips. Also known is the manufacturing of textile fabrics, which are formed from spunbond, melt- blown nonwovens or needle punched nonwovens. In addition, laminates of combinations of one or more layers of a nonwoven and a film are known.

The application of film layers of a thermoplastic polymer on textile fabrics is also known. For example, multi-layer fabrics produced using thermobonding are described in WO 95/1 1803.

On the other hand, textile fabrics of polyolefins, polyester, cotton or cellulose extrusion- coated with polyolefins are known from WO96/09165.

In addition, methods are known that increase the thermodynamic compatibility between organic filler or reinforcement materials and polymers, especially non-polar polymers in order to obtain composites with a desired level of properties. Since the processing of fiber materials containing cellulose to make filler materials is very cost-intensive because of their ductile behavior, the application areas of these filler materials in the area of polymer products with moderate or low price level are restricted to products that have a relatively compact form. The object of the present invention consists of making available a polymer product using a polymer material and a cellulose material, which can be manufactured with reasonable financial expense.

This object is achieved with an extruded polymer product with the characteristics of Claim 1 , with a method for use of rice hulls according to Claim 15, with a system for manufacturing an extruded polymer product according to Claim 20, as well as with a master batch to be extruded for manufacturing preferably spun fibers according to Claim 23. Preferred embodiments are defined in the subclaims. However, the characteristics included can also be linked with other characteristics from the following description for further designs and are not restricted solely to the respective claimed further development.

The extruded polymer product has the advantage that relatively thin-walled polymer prod- ucts or polymer products with very small diameters can be manufactured, which have a wood-like character and can be manufactured on the usual plastic processing systems.

An extruded polymer product comprising at least one polyolefin and wherein cellulose material obtained from rice hulls is embedded in the polymer material is suggested. The cellulose material is embedded as a filler material in the polymer material, which acts as a matrix component in the composite that occurs. Preferably the polymer material has at least one polyolefin, preferably a polyethylene or a polypropylene.

In one embodiment of the invention, the extruded polymer product is formed as a film. This film can be designed with one or more layers and be created by means of an extrusion process.

Another embodiment of the invention provides that the extruded polymer product is a spun fiber. Nonwovens that contain these types of fibers can be produced in various ways. Ad- vantageously, the nonwoven is produced according to a spun bond method. A method of this type is described, for example in DE 10322460 and DE 10240191. However, in addition, embodiments are possible for this nonwoven, in which, e.g., a melt-blown process has been used for manufacturing the nonwoven, as is described in DE 19923344. However, the polymer product can have as matrix-forming components, in addition to a polyolefin or its copolymers, other film-forming or spinnable plastics, for example polyam- ides, polyesters, polyurethanes, acrylate-based polymers and similar polymers. If necessary, other additives in the form of processing aids, other fillers, especially of an inorganic nature, like, e.g., calcium carbonate, dyes, pigments or functional additives, for example antioxidants, UV stabilizers, flame inhibitors or antistatics are provided. The polymer products in the following can have a surface treatment, which is carried out during the manufacturing process for the polymer product or can be carried out in a subsequent process step. For example, they can be provided with a hydrophilic coating, which is preferably sprayed on or applied to the polymer product in an immersion process.

For example, as a polymer material, a polyethylene with an MFI between 15 and 35 g/10 min, and preferably between 15 and 20 g/10 min. according to ISO 1 133 and a density of 0.935 to 0.965 g/cm ³ according to ASTM D-792 can be used. Also, the use of an LLDPE with a density between 0.85 and 0.90 g/cm ³ according to ASTM D-762 is possible. In addition, a polymer mixture consisting of polyethylene homopolymers and/or polyethylene copolymers can be used. For example, a polymer mixture of a polyethylene manufactured by the Dow company under the manufacturer designation "ASPUN 6834" can be used as polymer matrix. This has an MFI of 17 g/10 min according to ISO 1 133 at a density of 0.95 g/cm ³ according to ASTM D-792 and a melting point of 130°C according to DSC measurement. This material is suitable for purchase by the manufacturer for the manufacturing of nonwoven fibers and/or polymer fibers. Another polymer that can be used as matrix is the polyethylene sold by the Dow company under the manufacturer designation "ASPUN 6834A." This has a density of 0.955 g/cm ³ according to ASTM D.792, a MFI of 30 according to ASTM D-1238 and a DSC melting point of 131 °C.

The term "cellulose material" is understood to mean organic filler or reinforcement materials, which in addition to other constituents, e.g., lignin, also have a portion of cellulose or hemi-cellulose.

One embodiment of the invention provides that the cellulose material is obtained from a renewable plant material. Polymer products in the sense of this invention are not restricted to cellulose materials of rice hulls. In the dry substance, rice hulls exhibit about 50 weight-% cellulose and hemi- cellulose and 26 weight-% lignin, and thus belong to the so-called lignocellulose- containing materials and with respect to the composition are related to other natural fibers, e.g., wood fibers.

In addition, the cellulose material can also be obtained from wood in the form of sawing or planing chips, peat, kenaf, flax, linen, hulls from seed shells, especially grain hulls, grass seed, bran, compost of rinds, coconut fibers or substances with low or no fiber content, especially rinds or nut shells or mixtures of natural materials containing fiber, with low fiber or free of fiber. Depending on the cell structure, the average raw density of the cellulose fibers, especially the percentage of cell wall substance and the degree of fiber inclusion is between 0.3 to 1.3 g/cm ³ , preferably between 0.4 to 0.8 g/cm ³ and more preferably between 0.4 to 0.6 g/ g/cm ³ . The apparent density of the cellulose fibers lies between 90 and 500 kg/m ³ , preferably between 130 to 330 kg/m ³ , measured according to DIN EN 12580.

In order to be able to embed filler or reinforcement materials, for example rice hulls or other materials containing cellulose in a suitable way in a polymer and process it to a polymer product, it is necessary to pretreat the filler or reinforcement material. This require- ment results, for one thing, from the lack of compatibility of a lignocellulosic fiber to a non- polar surface, as is present in the case of the polyolefins. For another, during filling or reinforcing, an elastic component is created in a visco-elastic component. In load cases, with a characteristic yield point for each material, microcracks and cracks develop at the boundary surface of the multi-phase system, which can lead to failure of the system.

One embodiment of the invention provides that the filler or reinforcement materials for example the cellulose material such as rice hulls are crushed and coated. Since the materials containing cellulose provided in the scope of this invention have a ductile behavior, impact and centrifugal mills are required for their crushing process. Versions of these crushing devices, which have milling elements resting on a rotor that rotate at high speed like impact bars, hammers, arms, pins or tabs, which crush the material in flight by impact and bouncing, but not by cutting or by pressure against a base, are known, for example, from a book by Vauck and Mijller "Basic operations of chemical process technology" 10th Edition (1994) Deutscher Verlag fur die Grundstoffindustrie Leipzig Stuttgart pp. 324-328.

Depending on the required fineness of the milled material for the polymer product to be manufactured, a cooling compound can be used during the crushing process.

One embodiment of the invention provides for a method in which the rice hulls are cryo- genically crushed to a specified average size before they are mixed with the polymer material. In a further development of the invention, the rice hulls are crushed in a cryogenic crushing system in which the crushing mill itself is chilled. A coolant will then especially be preferred if a material containing cellulose used in the sense of this invention requires increased crushing force in order to be brought to the necessary milled fineness or in order to be able to adequately fibrillate the cellulose material.

In connection with the cellulose material used, the named crushing options supply very different particle shapes, particle sizes, particle size distributions and a different morpho- logical fine structure. These factors have an effect on the pore percentage, the pore size and their distribution, as well as the absorption and swelling behavior of the cellulose material. The milled material obtained can have fibers with a length of up to 200 μηη and a diameter up to 20 μηι. In addition to the particle size and particle shape of the cellulose material used, for uniform metering of these particles in a downstream processing procedure for manufacturing a polymer product, e.g., by extrusion, a uniformity of the material containing cellulose is necessary in order to obtain uniform product qualities. Very large or very small fibers lying at 150 - 250 kg/h, for example with flat products, can lead to metering problems at high production speeds. Since the fiber materials have a high tendency to bridge formation, they are hard to meter. Since the milling process can result in a wide distribution of the fiber grains, during the milling process or immediately thereafter, a sieving of the milled material can be provided in order to ensure uniform flowing of the fiber materials during their further processing.

In a further development of the method, the use of rice hulls is planned, whereby the rice hulls are crushed and added to the polymer material having a polyolefin to form a mixture and extruding a polymer product from the mixture. The rice hulls are crushed to a size that can be specified.

A preferred further development of the invention provides an extruded polymer product, wherein the cellulose material,for instance the rice hulls have a fiftieth percentile (D ₅₀ ) from 1 to 2 μηη. The 90th percentile (D ₉₀ ) of the cellulose material is preferably less than 10 μηη.

In order to ensure processing capability that is as free from interference as possible for the cellulose materials during the forming process during the manufacturing of the polymer product, the diameter of the forming tool, for example a spinning nozzle, should be about three times the diameter of the cellulose fiber. In analogy to this, it also proves to be advantageous if during creation of a polymer product in the form of a film, for example, the thickness of the slot of a wide slit dye is three times the diameter of the cellulose fiber.

At an air temperature of about 25°C and a relative humidity between 50% - 65%, cellulose materials contain a compensating moisture of about 8% to 12%. In order to make the incorporation of the cellulose fibers into the polymer mixture possible such that the resulting composite in the form of the polymer product has adequate bonding properties, it is nec- essary to further reduce the water content of the cellulose material before further processing.

A further development of the invention provides a method in which the rice hulls are dried after they have been crushed.

The effort required for the drying process for the cellulose materials after a crushing process can be very different, depending on the quality of the cell structure and the surface geometry. In the scope of the invention, moisture contents of the cellulose materials after the drying process that lie between 3 weight% to 6 weight-% have proved to be advantageous.

In order to be able to mix polymers with cellulose materials, for example rice hulls, and obtain therefrom an extruded polymer product with a characteristic level suitable for the respective application, a surface treatment of the cellulose materials is provided, which makes it possible to achieve an adequate bonding strength between a non-polar matrix that is present in the case of the polyolefins and a natural fiber, which tends to high water absorption. In this process it is necessary to disperse the cellulose particles, preferably in the polymer matrix in order to prevent agglomeration of the particles.

A further development of the invention provides an extruded polymer product wherein the cellulose material is treated with an additional material and wherein the additional material is embedded in the polymer material.

By using such a surface treatment, an adaptation of the boundary surfaces occurs in the bond between the polymer matrix and the cellulose material, which leads to an improvement of the phase bonding due to the increase in the adhesion forces between the polymer matrix and the plant fibers. In addition to the surface treatment of the fiber material, a modification of the polymer matrix or a combination of the two possibilities can occur. Variations of the adhesion increase of the composite partners polymer matrix and cellulose material consist, for example, in equipping the cellulose material with silanes or substances with hydrophobizing effects or coating with a functionalized polymer material, for example a functionalized polyolefin material or a functionalizing of the polymer matrix cou- pled with a silanized cellulose material. For example, silanes can involve radical reactions with the polymer matrix. Silanes can contribute to an improvement to an improvement of the adhesion between the cellulose fibers and the polymer matrix, but also to better dispersion of the fibers in the matrix. In addition, for example, the option exists of using male- ic acid anhydride for functionalizing the polymer matrix, for example a polyolefin, whereby the binding of the polymer matrix to the cellulose material can occur using the formation of a covalent ester bond by way of available OH groups of the cellulose material or by way of hydrogen bridge bonds between the hydrolyzed maleic acid anhydride, i.e., the acid function and the OH groups of the cellulose material can be affected. In addition, to promote compatibility between cellulose fibers and a polyolefin matrix, stearic acids and salts thereof can be used.

Preferably, in the sense of this invention, substances with hydrophobizing action are provided to treat the cellulose fibers. Especially preferably, in the extruded polymer product fatty acid derivatives are used as coating materials for the crushed rice hulls. The addition of the materials with hydrophobizing action for treating the cellulose fibers can be between 0.05 and 10 weight-% related to the portion of the cellulose fibers. Usual additives, which are added to the polymer as compatibility promoter can lie between 0.05 - 5 weight-% related to the polymer. With the use of polymers, for example polyester or polyamide, which have a lower hydrophobia than polyolefins, the addition of the compatibility promoter preferably lies between 0.05 - 5 weight-% related to the portion of cellulose fibers.

One version of the invention provides that the extruded polymer product can have a cellu- lose material wherein the percentage of the cellulose material of the total weight of the extruded polymer product is larger than or equal to 2 weight-% or 20 weight-% and smaller than or equal to 90 weight-% or 45 weight-%. Preferably, the percentage of the cellulose material is between 20 to 90 weight-%, related to the total weight of the polymer product. In a preferred embodiment the polymer product has a percentage of the second portion of the total weight of the polymer product between 2 weight-% and 45 weight-%.

In another embodiment of the invention, it is provided that the cellulose material is added to the extruded polymer product as a master batch from polymer material and the cellulose material. In this case, the percentage of the cellulose material of the master batch can be between 4 weight-% to 90 weight-%, related to the total weight of the master batch.

Depending on the filler material selected as the second component in the polymer products and the desired material properties of the polymer product, filler contents can be ad- justed as desired.

In addition, the cellulose material can have different arrangements in this product by the selection of the process parameters during manufacturing of the polymer product. In one embodiment of the invention the extruded polymer product is characterized in that a distribution of the cellulose materials over a cross section of the extruded polymer products is not uniform, whereby a first area that is adjustable by the manufacturing of the extruded polymer product has a higher percentage of cellulose material than a second area. The invention provides that a polymer product designed as a spun fiber can be present as a fiber-filled one- or multiple-component fiber. In this case, the components of a multi- component fiber can be present in a mixture or as separate components. In the latter case, bi-component or multi-component fibers with different structures and distributions of the components over the fiber cross section can be formed. The fibers formed in this way can be present as conjugated fibers.

For manufacturing multi-component fibers, there are various known possibilities, which have been described, for example, in US5336552, US5382490, US5759926 and

US5783503. With the requirement that the polymer matrix and/or the cellulose fibers have been prepared and/or pretreated according to the previously named embodiments, the methods described above for manufacturing multi-component fibers can also be used for the manufacturing of the polymer products.

In a further development of the invention, the extruded polymer product is a spun fiber with a core-sheath structure, whereby in the core a higher percentage of cellulose material is arranged than in the sheath. In a preferred version of the invention, the extruded polymer product is designed as a spinnable material. The extruded polymer product comprises a spun fiber manufactured from a single polymer material, wherein the concentration of the cellulose material, preferably of the crushed rice hull material, is larger at its surface than inside the fiber. Preferably spun fibers are formed with a content of cellulose fibers between 10 weight-% and 30 weight-% related to the total weight of the spun fibers.

The fibers were manufactured under the following spinning conditions:

- Spinning package with 105 spinning holes with a diameter of 0.6 mm and a length of 1 .6 mm;

- Melt filter, with sieves having a mesh width of 33 μηη and 80 μηη in two layers;

- Temperatures at the extruder head of 235°C, in the melting line of 240°C, in the spinning pump of 240°C and on the spinning package 240°C;

- Specific throughput, 0.61 g/spinning hole min;

- Temperature of the quenching air: 15°C.

In one embodiment of the invention, the formed spun fibers or polymer fibers with the use of a polypropylene of the type Moplen HP462R and cellulose fiber content between 10 - 20 weight-% exhibit the following properties:

- Filament titers in the range between 1 to 5 dtex, and preferably between 2 to 3.5 dtex,

- a strength in the range between 3,8 - 6 dN/tex and

- a stretching in the range between 100 to 370 % according to DIN 29073-3 The values determined for the stretching and strength of the spun fibers lie in the range of values that are known for spun fibers of polypropylene with average molecular orientation. Also the extruded polymer product can be formed as a coextruded film, comprising coex- trusion layers having different weight percentages of cellulose material. Preferably weight parts between 20 weight-% and 45 weight-% are provided in these film.

In this process, the drying of the cellulose materials can occur in one or several steps.

A preferred version of the invention provides that a system with an extruder is used, whereby the extruder has a degassing system. This has the advantage that a complicated upstream drying step for the cellulose material that is present with an enlarged surface due to the milling process is not necessary. On the other hand, the liquid particles that still adhere in spite of a drying process can be eliminated during the processing method in order to obtain a polymer product free of bubbles.

In another embodiment of the invention, a system for manufacturing a polymer product has a drying unit for the cellulose material that is connected to the extrusion device of the system, whereby the drying unit makes possible the use of waste heat from the drying of the cellulose material. In this case, for example, hot air resulting from the processing step can be used.

A preferred version of the invention provides a system, wherein an extrusion device and a drying unit for drying the crushed rice hulls are connected by heat transport means arranged to transport waste heat of the extrusion device to the drying unit and wherein the drying unit is arranged to dry the crushed rice hulls using the waste heat.

The incorporation of the cellulose material into the polymer matrix can occur in different ways. For example, the crushed and possibly fractionated cellulose materials can be processed together with one or more polymers, which can also be present in a finely divided form, in a mixer, for example, in a heating-cooling mixer combination to an agglomerate. In this process, other additives, e.g., processing aids, can be measured in. These agglomerates are formed, for example, in a subsequent extrusion process to a polymer product in the form of a fiber or film.

The incorporation of the cellulose material into the polymer material can, for example, also take place in a stream of gas, in which mixing and possibly milling of cellulose particles occurs, as well as a batch coating of the cellulose particles with polymer material in the gas stream.

In another embodiment of the invention, a polymer material can result by a direct pro- cessing of the polymer and cellulose fiber components on a double screw extruder with screw shafts running in the same direction or opposite directions.

A preferred version of the invention provides that a system with a double screw extruder is used, whereby the double screw extruder has a degassing system.

Preferable here is a system for manufacturing an extruded polymer product comprising a polymer material comprising at least a polyolefin and a cellulose material obtained from rice hulls, whereby a double screw extruder is used to mix polymer material and dried crush rice hulls. The double screw extruder comprises mixing zones for mixing the poly- mer material and the dried crushed rice hulls. In this direct processing, a polymer mixture can be measured into the extruder and the cellulose material can be supplied by way of a separate hopper, which opens into the supply line to the extruder.

A preferred embodiment of the method provides that a master batch to be extruded is prepared.

A master batch is understood to mean a material produced in granulate form, which has a polymer component and a portion of cellulose material. If necessary, other additive can also be used in the form of processing aids, dyes, pigments or functional additives, for example, flame retardants or antistatics. This master batch can preferably be equipped with a very high content of cellulose materials and manufactured on a double screw extruder with screw shafts running in the same direction, a so-called compounder. This master batch can then be used directly for manufacturing a polymer product or portions can be added to a polymer in order to be able to process it to a polymer product.

In one embodiment, the invention provides a master batch, which is preferably used for manufacturing spun fibers, but also films, whereby in the master batch a polyolefin is provided that contains rice hulls that have been crushed to a maximum size that can be specified.

The manufactured polymer product can be designed alone or as a composite with other nonwovens or materials, for example, with another polymer product in the form of a film or several films. In particular it can be connected with the other material to form a layered material. After it is manufactured, the resulting flat monolayer or multilayer fabric can also be embossed, bonded, laminated and/or mechanically treated, especially connected with another material. For example, this can occur physically, chemically and/or with form fitting. For example, thermal and/or ultrasonic connection possibilities can be used in order to connect the individual layers to each other. In embossing-bound polymer products in the form of monolayer or multilayer nonwovens or nonwoven-film laminates, embossing surfaces can be provided with a percentage of 10%-50%, related to the entire surface of the flat fabric. Manufacturing of a laminate of several layers of a nonwoven from spunbond or melt-blown fibers or combinations thereof can be manufactured according to the tech- nical teaching disclosed, for example, in US5178931 , US3704198, US3849241 and

US5188885, whereby the polymer product has a first portion of a polymer material and a second portion of cellulose material.

In addition, an adhesive, for example a spray adhesive or a so-called hot-melt adhesive, latex-based adhesive or other adhesive can be used.

In a further development of the invention, several spun bonds of the same or different types can be combined and formed to make a laminate of these spun bonds. Advantageously, a laminate can also be formed in which at least one film is combined with at least one nonwoven.

For laminate formation, different types of processing are possible. For example, individual layers can be manufactured as nonwoven or film in separate processing steps, which are joined in another processing step, for example a calendering step, to form a laminate, whereby different calender roller arrangements can be provided that cause a thermal compacting of the laminate. A calendering method such as this is described, for example, in US 3,855,046. Usually, smooth or profiled calender rollers are used, which can be combined with each other according to the planned usage purpose and required characteristics profile for the laminate. With the use of embossing rollers, discrete embossed bonds can be formed in the laminate. Methods for manufacturing separate layers and lam- inate produced from them are described, for example, in DE 431 1867.

Another possibility for laminate formation can consist in that a nonwoven is formed and this nonwoven is coated in-line with a film. On the other hand, a film can be extruded first, which, for example, is placed on a holding line, whereby a created nonwoven is deposited in-line on this film. The composite formation can also occur here using a calendering arrangement. In addition, other types of composite formation are also possible, for example by needling or water stream compacting. Special variations for the formation of this flat fabric can be seen, for example, in DE10360845A1 , US 4,021 ,284 and US 4,024,612. In one embodiment of the invention, the manufactured polymer product in the form of a nonwoven fabric is characterized, for example, by the following characteristic values:

- Thickness of the nonwoven fabric between 50 μηη and 2000 μηη

- weight per surface area between 7 and 500 g/m ² , and preferably between 10 and 200 g/m ² ,

- Product of the weight per surface area (g/m ² ) and the air permeability (1/m ² s, acc. to DIN EN ISO 9237) in the range of 1 10,000 +- 20%,

- Values for the quotients from the water column (according to DIN EN 2081 1 ) and the weight per surface area of 2.5 +- 20%,

- Filament surface is hydrophilized and has values for penetration times, measured according to EDANA ERT 150, of less than 5 s.

- Values for the quotient of maximum tensile force (according to DIN 29073-3) and weight per surface area in machine direction of 1.7 +- 20%, and in transverse direction of 1.0 +- 20%.

- Values for the quotient of maximum tensile force extension (according to DIN 29073-3) and weight per surface area in machine direction of 3.3 +- 20%, and in transverse direction of 4.0 +- 20%. In another embodiment of the invention, a polymer product created in the form of a film can have densities between 0.60 to 0.9 g/cm ³ .

In addition, with the use of cellulose materials, in the majority of which the cell structure has become broken up due to the preparation, for example by milling of the fibers, and a majority of the cell wall substance is available for further processing, the polymer product manufactured from it, for example, in the form of a film, has densities from 0.9 to 1 .2 g/cm ³ .

Depending on the finishing of the polymer products created, these can be used in all dif- ferent types of application areas, for example, for:

- Packages,

- Covers, e.g., CD cases,

- Decorations, for example trim materials for covering objects to create a wood-like char- acter of the object,

- Covering material in the area of agriculture or for environmental purposes,

- Coating, roofing, heat or noise insulation or filter material,

- Wall covers in the building area, - Cleaning cloths,

which are given here only by way of example without any claim to completeness.