FI104569B - A process for preparing compositions comprising cellulose-based fibers - Google Patents

Description

104569

The present invention relates to a process for the preparation of compositions containing cellulose-based material according to the preamble of claim 1, which comprises mixing the finely divided cellulose-based material with the backbone.

Cellulose-based fibers and other such fine wood and cellulosic raw materials are difficult to combine with other materials. This is due to the chemical composition and hygroscopicity of the material. Thus, for example, sugars contained in wood retard the curing of concrete containing wood fiber. Therefore, the wood fiber has to be pre-treated in different ways to achieve hardening of the concrete. However, prior art treatments based on wood fiber extraction are difficult and slow.

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The properties of asphalt have been improved by blending pulp-based recycled fiber into the asphalt mass. The quality of the recycled fiber varies greatly, which causes great difficulty in the bonding process. The problems are mainly related to the mixability of the fiber; untreated pulp fiber has not been found to mix sufficiently well with the asphalt mass.

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When combining wood and plastic, the hygroscopicity of the wood and the varying humidity of the wood cause great difficulties. For this reason, very little of this type of bonding has been made, although cellulose-based fibers are taxing an interesting and environmentally friendly opportunity to alter the properties of plastic-based materials.

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The object of the invention is to eliminate the drawbacks of the prior art and to provide a completely new solution for the preparation of compositions containing cellulose-based material. In particular, it is an object of the invention to provide a process for increasing the uniform mixing of cellulose-based material with other materials and promoting compatibility between different materials.

The invention is based on the finding that upon heating of a cellulose-based material, such as wood or cellulosic fiber, at a temperature above 150 ° C, the properties of the material 2,104569 change drastically. The hygroscopicity of the fiber is reduced, which substantially enhances the miscibility of the fiber with other substances. In addition, during the heat treatment, the mono- and polysaccharides in the wood as well as the extractives are decomposed and partially removed from the wood fiber.

The wood or cellulosic fiber obtained as a result of the process does not slow down e.g. curing of concrete mass 5. In addition, the moisture elasticity of the wood fiber is reduced, its resistance to decay is improved, and its thermal conductivity is reduced, also improving its compatibility with other materials. with plastics. Thus, such heat-treated cellulose-based material can be well mixed with the backing material to form various compositions.

More specifically, the method according to the invention is essentially characterized in what is stated in the characterizing part of claim 1.

The cellulose-based material used in the process of the invention is, for example, wood fiber, cellulose fiber, wood flour and / or wood chips. The wood raw material is finely divided, which means that the wood flour has a particle size of about 0.01 to 10 mm, preferably about 0.05 to 5 mm. The wood fibers and wood chips also have a cross-sectional or corresponding thickness of about 0.01 to 10 mm, preferably about 0.05 to 5 mm.

According to a preferred embodiment, suitable wood or cellulosic fibers are prepared by grinding a lignocellulosic feedstock. The abrasive grinding effect is achieved by, for example, grinders with grooved blades, such as plate or conical grinders. Examples of suitable materials are wood material for use in the manufacture of fibrous products, such as wood fibers for MDF boards, cellulosic fibers from mechanical pulp production, recycled pulp fibers and sawdust. Wood and cellulose fibers are particularly preferred.

The cellulosic material may be derived from wood, e.g. spruce, pine birch or * wound, or annual or perennial plants. Thus, straw is also suitable as a starting material.

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According to the invention, the cellulose-based material is heated at a temperature of at least 150 ° C to 104569 until the weight of the material is reduced by at least 3% (based on dry matter). Heating can be continued up to a weight loss of about 22% to about 25% without excessively weakening the material strength properties.

It is known in the art to treat fine wood at elevated temperature. EP-A-0 373 726 describes a fibrous cellulosic product in which the fibrous material is softened at a temperature of 150 to 220 ° C with an aqueous softener under elevated pressure, followed by drying and curing at an elevated temperature to form a crosslinked structure. FI Patent Application 920774, in turn, relates to a process for steam treatment of wood pulp to improve its paper technical properties. GB-A-2,185,748 describes a method of making a fibreboard, wherein the wood fibers or chips are first heated in an autoclave at 100-200 ° C for at least one hour before being glued together with a binder to form the sheet. The method can improve the moisture resistance of the board.

A similar process is also disclosed in European Patent Application 0 186 503, in which wood chips are first treated with water vapor at elevated pressure and then formed into a layer to which is added a powdered phenol-formaldehyde resin, which acts as a binder when compressing the chipboard composite sheet.

The present invention differs from the prior art described above in that the cellulose-based material according to the invention is formed into compositions in which the cellulose-based material does not form the main component. The main components of the compositions are also referred to as "bulking agent" or "matrix of compositions" within the scope of this invention. Typically, the cellulose-based material constitutes from about 0.1% to about 49%, preferably from about 1% to about 40%, by weight of the dry weight of the composition. The object of the invention is to improve the properties of the cellulose-based material by heat treatment so that it is more suitable for use. * for use in compositions wherein it is mixed with a composition builder. This aggregate may be mixed or dissolved in water or an aqueous solvent or other liquid.

The heat treatment of cellulosic fibers for use as concrete reinforcing agents is known in the prior art from DE-A-3 734 729. According to that publication, cellulosic fibers are treated at elevated temperature and elevated pressure. The present invention differs from the reference in e.g. in that the invention aims to provide about 3% to about 25% weight loss. The heat treatment of the invention affects the chemical properties of wood, removes wood sugars, i.e. mono- and polysaccharides, and wood extractants. At the same time, the hygroscopicity of the wood is reduced and the resistance to decay is improved. Due to the decrease in hygroscopicity, the cellulose-based material mixes well with liquids, especially water and aqueous mixtures. This is also evident from Example 1. By increasing the pressure in the DE patent, it is intended precisely to avoid thermal decomposition of the fibers.

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The heat treatment of the cellulose-based material, e.g. wood fiber, may be performed on dry or wet fiber. If the treatment is carried out on a wet fiber, it must be prevented from lumping during drying. The ignition of the material during the heat treatment is prevented by mechanical treatment in the anoxic state. Therefore, the heat treatment according to the invention is preferably carried out in a humid atmosphere which is, for example, saturated with water vapor.

Unlike prior art processes, the heat treatment of the invention is preferably carried out under non-pressurized conditions.

According to a first embodiment of the invention, the cellulose-based material from fresh wood or plant material 20 is itself subjected to a heat treatment at a temperature of at least 150 ° C.

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According to another embodiment, the moist treatment of the cellulose-based material is carried out in two steps, first of which the product is dried to the desired humidity, usually below 15%. The temperature is then rapidly raised above 150 ° C (typically about 180-300 ° C), at which temperature the treatment is continued until a weight loss of at least 3% is achieved for the product to be treated.

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In said second embodiment, it is possible to start from fresh finely divided material which is dried under any suitable conditions (even outdoors at ambient temperature) to a desired humidity below 15%. However, according to a preferred embodiment of the invention, the product is dried at an elevated temperature, e.g., 90-120 ° C. At the same time the color of the wood product is darkened.

After the product has dried to below 15% humidity, the treatment is continued at elevated temperature.

In the second step of the process, the temperature is kept above the first step. Preferably, the reaction is carried out at a temperature of about 150 to 300 ° C under a saturated vapor atmosphere. The temperature can also be raised during the second stage. The treatment time and temperature are interdependent; at high temperatures, treatment times are shorter than at low temperatures. Typically, the second stage heat treatment takes at least 1 minute, preferably 0.05 to 20 hours, and particularly preferably about 0.1 to 10 hours. By adjusting the weight loss of the product through heat treatment, its mixing properties can be changed as desired. The mold and rot resistance properties of the product also improve with a weight loss of 3%, but said durability can be further increased by continued heating until the product has lost at least about 5%, preferably about 6 or even 8% by weight.

As examples of aggregates of the compositions of the invention, the above-mentioned examples include: cements with possible fillers, such as aggregate; plastics, in particular thermoplastics, preferably polyolefins, polyesters or polyethers, including any fillers, including pigments; as well as bitumen and asphalt, including any aggregate and other aggregates. In many cases, the compositions are cured, e.g., at room temperature or by heat treatment to crosslink or crystallize the aggregate or otherwise stiffen. The proportion of aggregate in the composition to be prepared is typically about 1 to 99.9%, preferably about 10 to 99% (based on dry matter).

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According to a particularly preferred embodiment of the invention, the heat-treated fine wood material can be used to make wood-based moldings, the binder of which at least in part consists of cement or similarly calcium-based binder. In this embodiment, as in the concrete applications mentioned above, the cements may be conventional Portland cements, but rapids cements are also suitable for use. Ferro-slag-based cements of 6 104569 can still be used as cements.

alkali can be separately added to the cement activator. In addition to cement, a suitable resin glue or protein-based binder such as gluten may be used as a binder in the manufacture of moldings.

5 The composition or mixture used to make the moldings can be cured either at room temperature or at elevated temperature. In the latter alternative, the temperature is maintained at about 50-300 ° C. The cure time at room temperature varies with the size of the piece but is usually a few days. At elevated temperature, the mixture is cured within a few hours.

10 The use of heat-treated wood raw material makes it possible to cure the cementitious mixture at room temperature.

The molded part contains so much wood raw material that it can be made vapor barrier-15 tons of wall. This leads to plastic-free construction. The thermal insulation performance of the products is quite good, usually in the order of 0.05 to 0.08 W / m ° C, which is quite comparable to the value of mineral wool of 0.04 to 0.05 W / m ° C.

There are considerable advantages to the invention. Thus, when normally mixed with cellulose-based material, such as wood fiber, for example, the water will coagulate and form a precipitate at the bottom of the container. By thermally modifying the wood fiber, it is uniformly distributed in the water

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• · 'mixed up. No lumping occurs and the precipitate slowly forms on the bottom of the container. The heat modification reduces the thermal conductivity of the wood fiber so that it can be used in combination with other materials, e.g. frost insulation. During the heat modification, the wood fiber becomes lighter.

Further, the thermal modification of the wood fiber improves the compatibility between the wood fiber and eg concrete. The mixture hardens at room temperature. At the same time, the proportion of wood fiber in the concrete can be increased.

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In the following, the invention will be examined in more detail in a few application examples. 30 kits.

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7 104569,

EsimerkkU

Use of wood fibers for asphalt production

The suitability of the cellulose-based fiber to be added to the asphalt can be tested by a quick-5 test in which the fiber (4-5 g) is added to 200 ml of distilled water. Mix the mixture with a pen. If the pen remains capable of mixing, the mixing can be considered good.

According to the previous rapid test, the heat-treated (3 h, 205 ° C) spruce and aspen fiber mix well. When the same experiment was performed on untreated fiber, the fibers were caked to the bottom of vessel 10 and the pen did not stand up.

Example 2

Use of Wood Fiber in Concrete 15 In the production of normal concrete, curing has been observed to start within 7 days of the preparation of the mixture. The standard compression strength test is carried out after a cure time of 28 days.

By adding normal wood fiber to the concrete mass, the cure of the mass is substantially retarded or does not start at all. With the addition of heat-treated wood fiber to the concrete mass, the curing process proceeds normally without interference.

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Example 3

Use of wood fiber with cement and gluten to produce moldings 25

Molded parts with a gluten and cement binder were prepared as follows; according to recipe: 30 200 g of heat-treated wood fiber (aspen, 205 ° C, 3 h) 200 g of heat-treated cuticle shavings (aspen, 205 ° C, 3 h) 104569 8 100 g of gluten 600 g of cement 1500 ml of water 5 . The water was then added with vigorous stirring to foam the mixture. The mixture is shaped into the desired mold, which is allowed to dry at room temperature for a week. The end product was a lightweight, sheet-like thermal insulation that can be used as a rigid mineral wool board. It can be machined with standard tools (knife, saw).

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Claims (11)

A process for preparing a composition containing a cellulose-based material, according to process 5. A finely divided wood material or cellulose fiber is mixed with a matrix composed of cement with possible fillers, plastics, bitumen or asphalt pulp, characterized by - the wood material or cellulose fiber is made of a moisture content of less than 15%, after which it is poured into a humid atmosphere at a temperature of 150 ° C - 300 ° C until a weight loss of about 3 - about 25% has occurred in the product, and - the heat treated material is mixed with matrix substance. Process according to claim 1, characterized in that the cellulose-based material is dried to a moisture content of less than 15% at room temperature. 15 3. Process according to claim 1, characterized in that the cellulose-based material is dried to a moisture content of less than 15% at a temperature of about 90-100 ° C. Process according to any of the preceding claims, characterized in that the cellulose-based material is treated at a temperature of 180 - 300 ° C for a period of 0.05 to 20 hours, preferably about 0.1 to 10 hours. »· Process according to claim 1, characterized in that the atmosphere in connection with the heat treatment is poured saturated by water vapor. 25 6. A method according to claim 1, characterized in that the heat treatment is carried out in an eating-tone tone substantially under pressure-free conditions. Method according to any of the preceding claims, characterized in that wood fibers, cellulose fibers, wood flour and / or wood buckles are used as cellulose-based material. 12 104569 8. Method according to claim 7, characterized by man-made cellulose-based material using fibers made by refining. i 'i 9. A process according to any of the preceding claims, wherein cement is used as a matrix material, characterized in that it is continued with the heat treatment until at least part of the mono- and polysaccharides of the cellulose-based material are removed. 10. A process according to claim 9, characterized in that the cellulose-based material is prepared from a composition with cement and possibly some other binder, such as gluten, which composition can be cured in the desired form. A process according to any one of claims 1-8, wherein a liquid-containing composition is characterized, characterized by the cellulose-based material being heat-treated to increase its miscibility with liquid. ; i 'I V