NO176525B - Fiber-containing sheet or web material with vegetable filler, as well as a process for making it - Google Patents

Abstract

In a new process for reducing the density, increasing the bulk, the hand and the porosity of a sheet material containing fibres by means of a vegetable filler, a vegetable filler of density less than 500 kg/m<3> is introduced into the fibrous mass during the manufacture of the material. At least 95 % of the particles of the vegetable filler are less than 150 micrometres in size and at least 80 % of said particles are greater than 10 micrometres in size. The process is particularly useful for obtaining paper and cardboard of low density with improved hand and porosity. It is also attractive since it reduces the cost prices and enhances the thermal and acoustic insulation properties.

Description

This invention relates to a fibrous sheet or web material which in its mass contains a vegetable filler and which is obtained by paper-making techniques from an aqueous suspension containing fibers and a vegetable filler.

The invention likewise relates to a method for producing a fiber-containing sheet or web material by paper-making technology, comprising mixing a powdered vegetable filler into an aqueous dispersion containing fibers.

According to the invention, the material's reduced density and increased thickness also provide specific and advantageous properties, for example opacity and sound, heat and electrical insulation. This particularly applies to the fibrous web.

According to the invention, the use of the above-mentioned vegetable filler also has a beneficial effect on the dewatering rate during the production of the road material and thus has a good effect on productivity. The process also has the advantage of reducing costs.

In papermaking, it is common to use mineral, organic or synthetic fillers or pigments. The most common mineral fillers and pigments are talc, kaolin, natural and precipitated calcium carbonate or calcium carbonate produced by recycling black liquor obtained by boiling kraft pulp, magnesium carbonate, aluminum oxide hydrates, calcium sulphate, colloidal silicon (silicon oxide), barium sulphate, titanium dioxide, magnesium hydroxide and mixtures of these.

The common fillers used in papermaking have variable equivalent sphere diameters as measured by SEDIGRAF, but in general all these fillers have particles smaller than 100 micrometers, especially smaller than 50 micrometers and especially smaller than 30 micrometers.

Thus, 50 percent of the particles in the kaolin to be mixed in the mass have a size of between 6 and 8 micrometers (d5Q = 6-8 micrometers), and 95 percent of the particles have a size of less than 50 micrometers (d95 < 50 micrometers) . The talc to be mixed into the mass has a d5o of between 8 and 10 micrometers and a d95 of less than 50 micrometers, and the calcium carbonate has a d5Q of between 7 and 9 micrometers and a d95 of less than 25 micrometers.

The pigments in the surface layer have a d5Q of between 1 and 3 micrometers and a d95 of less than 10 micrometers. The organic pigments are much finer and have a d5Q of between 0.1 and 1 micrometer.

It is known, in particular from EP-B-0 006 390, EP-B-O 050 316 and FR-A-2 578 870, that mineral fillers contribute to reducing material costs and that, depending on which properties they have, they have a beneficial effect on opacity , particularly within printing/writing substrates and certain special types of paper. If the content of mineral fillers in the material is high compared to the content of cellulose fibres, this can have a beneficial effect on the dimensional stability, which is particularly desirable in base materials for floor and wall coverings. On the one hand, however, the use of these mineral fillers has a negative effect on the thickness of the material, and on the other hand, the increase in the content of residual ash also leads to a significant increase in the density of the material, which is not favorable for the price per square metre.

The paper industry uses certain special fillers or pigments to increase paper thickness, such as diatomite or natural, calcined or activated diatomaceous earth, carbon or glass microspheres, calcium silicates and colloidal silica, but these fillers and pigments are usually very expensive.

The mixing of so-called mechanical cellulose pulp such as thermomechanical or chemimechanical pulp and, to a lesser extent, mercerized pulp and synthetic fibres, especially polyester, polyethylene and polypropylene fibres, also contributes to better fullness (or paper filling or puffing), but the use of these fibers requires significant industrial aids and only applies to very special applications.

This invention recommends a new technical solution to overcome the above problems. This solution makes use of a renewable vegetable raw material of which there is plenty, namely wood and then mainly wood waste as well as other vegetable waste, especially then waste from the production of grain products, especially maize cobs.

It is this vegetable raw material that will be used to produce low-density vegetable fillers that have the desired particle size so that they can be prepared in the pulp, either directly as any other common filler used in papermaking, or preferably in the form of an already flocculated mixture of filler and binder.

It is known that the possibility of using wood powder or wood flour as a filler in the production of paper and cardboard, either prepared in the pulp or coated on the paper surface in a layer, has already been pointed out at an earlier stage.

It is known in particular that Abstract No. 8739 in the journal ABSTRACT BULLETIN OF THE INSTITUTE OF PAPER CHEMISTRY, 48, (No. 8), page 938, (February 1978), American Patent Specification US 3,184,373 and German Patent DE-C-415 675 takes preparation of wood powder into the fibrous mass into consideration.

Summary no. 8739 mentioned above recommends the use of a mixture of 70-95% by weight cellulose pulp (kraft fiber) and 30-5% by weight wood flour for the production of electrically insulating panels, where these panels are said to be more oil absorbent and more resistant to surface discharge. The above document neither describes nor suggests the use of a vegetable filler with the particle size and density that is particular to the present invention.

American patent description US 3,184,373 relates to an improvement in the ability to hold filler in paper and cardboard in place by means of a retention agent such as polyethyleneimine, melamine formaldehyde resins and urea formaldehyde resins, where said "fillers" are defined (see column 2, line 3-34 ) as solid or liquid substances and which in particular consist of the mineral paper fillers themselves, metal powder, thermosetting resin powder, thermoplastic resins, binders, flocculants and wood powder (see column 2, line 27). The particle size in the above-mentioned "fillers" is said to correspond to a mesh size of between 60 and 2000 (see column 1, lines 70-71). However, American patent specification US 3,184,373 does not provide any examples showing the use of said wood powder mixed into the pulp. Furthermore, it neither describes nor suggests the particle size (particle size of between 10 and 150 micrometres) and the density (less than 500 kg/m^) which is particular to the vegetable filler according to the invention.

German patent DE-C-415 675 proposes a smoothing process where (i) a colloidal dispersion of a submicron substance (ie a substance with a particle size of less than 1 micrometer) containing cellulose and which is produced by grinding wood or straw, and further wherein (ii) a flocculating agent is mixed into an aqueous fibrous suspension. This submicron substance, which therefore has a particle size that is well below the vegetable filler according to the invention, fulfills a completely different role than the vegetable filler. In fact, the above-mentioned submicron substance in the German patent document C-415 675 is presented as reducing the porosity in the manufactured paper by blocking and/or filling the pores in the fibrous web, while according to the present invention one seeks to increase the porosity.

Techniques for coating (on a non-fibrous substrate) or surface smoothing (on a fibrous substrate such as paper and cardboard) are known from other sources, in particular from Belgian patent BE-A-425 432, published PCT international application WO 86/05195 and British Patent GB-A-I 464 381, where a blank is coated with a composition containing wood powder. It turns out that these techniques neither describe nor suggest that the vegetable filler with specific particle size and density according to the invention should be mixed into the fibrous mass.

Products which can be mixed into paper and cardboard, which contain cellulose and which are produced by means of physical-chemical treatment of wood chips or cellulose fibres, are also known, in particular from summary no. 1523 in the journal ABSTRACT BULLETIN OF THE INSTITUTE OF PAPER CHEMISTRY, 5.8 (No. 2), page 184 (August 1987), Abstract No. 7191, ibidem 55 (No. 6), page 754, (December 1984) and published French Patent Application FR-A-2 612 828 (which was published on September 30, 1988, after the priority date of this invention). The composition of the above cellulosic products is different from the composition of the vegetable or fibrous source material from which they are derived. In fact, the physical and chemical treatment that the source material undergoes causes the integrity of the components of the source material to be lost.

More specifically, summary no. 1523 mentioned above describes the production of cellulose in the form of micronized particles (with a size of between 5 and 75 micrometres and a degree of crystallinity of over 65 per cent) by means of hydrolytic treatment of cellulose pulp. The cellulose produced in this way differs from the composition of the vegetable filler according to the invention in terms of the nature of the latter's components.

Summary no. 7191 mentioned above describes the use of microfibrillated (micro-untangled) cellulose for the production of coating for cover layers. Here too, cellulose microfibrils differ in structure and composition from the vegetable filler according to the invention.

French patent document FR-A-2 612 828 is misleading in the sense that its claim number 1, as published, refers to the use of wood particles in the production of fibrous webs, when what is actually in question is the use of an extract in powder form which is extracted by treating wood powder, where the treatment consists in particular of the following steps (see descriptive part in the above-mentioned document from page 1, line 28, to page 2, line 12): (i) impregnation of wood powder with a suitable liquid chemical agent (sic), (ii) rapid autolysis (or rapid autohydrolysis) of the impregnated wood powder under a pressure greater than or equal to 30 bar, at a temperature greater than or equal to 230°C, for at least 90 seconds; followed by rapid (sudden) release of pressure, (iii) washing the manufactured product with water or a mixture of water and dioxane to improve the hemicelluloses and most of the wood (lignin), fatty acids and resin acids, and then (iv) drying the extracted the powder product which contains water-insoluble substances and which is free of water-soluble substances.

The present invention differs from the teaching in the above-mentioned abstracts No. 1523 and No. 7191 and the above-mentioned French patent document FR-A-2 612 828 in that the vegetable filler, which is recommended to be used in the pulp, has retained, so to speak, all the components of the the vegetable source material. In the vegetable filler according to the invention, only the water content and the content of volatile substances (such as the low-boiling essential oils) are affected compared to the original vegetable source material. If the vegetable source material is wood, then practically all the components of the wood, as described in the work of FENGEL et al., WOOD CHEMISTRY ULTRASTRUCTURE REACTIONS, pages 26-33, published by D. GRUYTER (1984), which are included here by virtue of the reference, be found again in the vegetable filler.

Referring to the prior art teaching, which consists of Abstract No. 8739 in the journal ABSTRACT BULLETIN OF THE INSTITUTE OF PAPER CHEMISTRY, 48, (No. 8), page 938, (February 1978), US Patent Specification US 3,184 373 and German patent DE-C-415 675 mentioned above, it should be pointed out that the use of wood flour or wood powder has never worked on an industrial scale according to exact specifications (i) of the density and particle size of the vegetable filler, and (ii) with the purpose of producing webs of fibrous materials which are more economical, have lower density, high porosity and high bulk by means of a papermaking technique.

According to the invention, it is recommended to use a vegetable filler of specific particle size and density in the production of fibrous web materials using a papermaking technique, where a technical solution is used that differs from the teaching in the known technology through the selection of the above-mentioned vegetable filler of specific density and particle size.

In this technical solution, the vegetable filler of specific density and particle size is mixed into the mass.

As a variant, it is recommended to replace part of the fiber (expensive) in the fibrous web material with the above-mentioned vegetable filler of specific density and particle size (cheaper).

According to the invention, a new technical solution is proposed which makes it possible to reduce the density, increase the porosity, increase the density and reduce the production costs for paper and cardboard.

This new technical solution also makes it possible to (i) increase the thickness of the fibrous web material due to reduced density, (ii) improve the bulkiness of the above-mentioned material, and (iii) improve the unwinding of the paper machine during the production of the above-mentioned material.

The fiber-containing sheet or web material according to the invention, which in its mass contains a vegetable filler and which is obtained by papermaking techniques from an aqueous suspension containing fibers and a vegetable filler, is distinguished by the fact that the vegetable filler has such a particle size that (i) at least 95% by weight of said vegetable filler's particles have dimensions less than 150 micrometers, and (ii) at least 80% by weight of said vegetable filler's particles have dimensions greater than 10 micrometers, said vegetable filler being obtained by of a micronization grinding operation from vegetable waste with a residual moisture content of less than 20%, and that said vegetable filler originates from such plant species that the sieve analysis distribution and the micronization-grinding conditions lead to a filler density lower than 500 kg/m^, preferably lower than 300 kg/m^, and that the fibrous sheet or track material comprises a weight ratio between vegetable filler and fibers that lies within a range from 1:100 to 6:1.

According to the invention, the method for producing this fiber-containing sheet or web material is characterized by the use of a vegetable filler with a particle size that is such that (i) at least 95 percent by weight of said vegetable filler's particles have dimensions that are smaller than 150 micrometers, and (ii) at least 80 percent by weight of said vegetable filler's particles have dimensions greater than 10 micrometers, said vegetable filler being obtained by means of a micronization-grinding operation from vegetable waste with a residual moisture content of less than 20%, and that said vegetable filler originates from such plant species that the sieve analysis distribution and the micronization grinding conditions lead to a filler density that is lower than 500 kg/m^, preferably lower than 300 kg/m^, which method allows the density to be reduced, the thickness is increased and the drainage of the fibrous sheet or web material is improved.

Any type of wood can be used to produce the vegetable filler according to the invention, such as for example wood from conifers such as Norway spruce, pine and spruce and wood from deciduous trees such as birch, beech, hornbeam and chestnut. This wood can either come from short felling or tree clearing, after transformation into shavings or strips/sheet cutting using methods that are well known in the paper industry for the production of chemical and chemical mechanical wood pulp. For mainly economic reasons, these vegetable fillers will come from waste products in sawing and planing, such as fresh and dry sawdust, planing shavings, bark and shavings from parquet production, carpentry and furniture making.

This vegetable filler can also be produced from vegetable waste material in forestry, for example tree stumps, unused branches of small diameter, cuttings and tops of tree trunks as well as from waste from grain harvesting, for example corn cobs.

As the various vegetable source materials mentioned above have different physical, chemical and morphological properties, the properties which these transfer to the final fibrous web material can vary with respect to density, fullness and porosity, depending on the type of wood used. Nevertheless, in all cases a significant reduction in density and an increase in fullness and porosity is achieved.

It is important that the micronized vegetable filler is in the form of particles with an average size of less than 150 micrometers (d95 < 150 micrometers) and greater than 10 micrometers (dgg > 10 micrometers). In fact, if the particles in the micronized vegetable filler have an average size equal to or greater than 150 micrometers, the manufactured fibrous web product exhibits defects in uniformity, especially molding defects. If the particles in the micronized vegetable filler have average dimensions less than or equal to 10 micrometers, the fibrous web product produced is clearly less porous, as shown in German patent DE-C-415 675 mentioned above. As indicated earlier, the particle size in the micronized vegetable filler will be such that d95 < 150 micrometers (preferably d95 < 100 micrometers) and dgo > 10 micrometers.

Furthermore, it is also important, with regard to the necessary properties that the final web product must have, that the density of the micronized vegetable filler is less than 500 kg/m^ and preferably less than 300 kg/m^.

When producing the vegetable filler according to the invention, it is also important that the vegetable source material, which undergoes micronization grinding, has a particle size that is less than or equal to 5 mm and a residual moisture of less than 20 percent before the above-mentioned micronization grinding.

In the process of this invention, the vegetable waste is micronized to produce the vegetable fillers with the particle sizes necessary for the invention. This is achieved by means of a special micronising grinding technique (vegetable source material with a particle size of less than or equal to 5 mm and a residual moisture of less than 20 percent), in particular by means of a disc mill sieve with impact whisks that through intense collisions at high speed and with pressure changes makes it possible to cause gradual disintegration of the vegetable source material until the desired fineness and density is achieved. Preferably, the residual moisture in the vegetable source material to be micronized should be less than or equal to 15 percent.

If the vegetable source material (or raw material) is thus in the form of strips/sheet clippings, planer shavings, chips, branches, etc., it must first be shredded and possibly dried before micronization to achieve a fineness of less than or equal to 5 mm and a residual moisture of less than 20 percent.

In paper applications, the vegetable fillers according to the invention will therefore have a d95 of less than 150 micrometres (ie at least 95 percent of the particles in the vegetable filler pass through a square-mesh screen of 150 x 150 micrometres), preferably a d95 of less than 100 micrometres. These vegetable fillers will be associated with a natural or common organic binder, fiber and various additives that are usually used for the production of fibrous web.

The weight ratio between powdered vegetable filler and fiber according to the invention will generally lie within the range 1/100 to 6/1. For the production of packaging paper, it would be advantageous to use a weight ratio between vegetable filler and fiber that lies within the range from 1/100 to 2/10 (and preferably from 1/100 to 1/10), for the production of substrates for printing/writing a weight ratio within the range from 2/10 to 5/10 (and preferably from 2.5/10 to 3.5/10), for the manufacture of cardboard a weight ratio within the range from 1/10 to 5/10, for the manufacture of paper for impregnation a weight ratio within the range from 1.5/10 to 5/10 (and preferably from 2/10 to 3/10) and for the production of special paper types a weight ratio within the range from 6/100 to 6/1 (and preferably from 3/10 to 8/10).

The fibers that can be used in these various applications are particularly natural or synthetic-organic fibers such as cellulose fibers, polyamide fibers, polyester fibers, polyalkylene fibers and polyacrylate fibers; mineral fiber such as glass fiber, ceramic fiber, needle-shaped gypsum fiber, coal fiber, etc. rock wool; as well as regenerated cellulose fiber. These fibers can be used by themselves or in a mixture. The fibers that are most used are cellulose fibers from kraft pulp or bisulphite chemical pulp, mechanical pulp, thermomechanical pulp or chemical thermomechanical pulp. Such pulp, produced from conifers or hardwoods, may be unbleached, partially bleached or fully bleached.

It is also possible to use so-called recovered cellulose pulp that comes from waste paper (for example, printing/writing pads, newsprint, cardboard boxes, packaging paper, magazines and the like), alone or in connection with noble cellulose fibres.

In the process according to origin, the vegetable fillers with controlled particle size can be combined with other organic or synthetic mineral fillers or mixtures thereof. The general or special fillers or pigments used in papermaking are those already mentioned above.

According to the invention, in practice the vegetable filler will on the one hand replace part of the essential ingredient in the material, namely the fibers in the paper sector, and on the other hand could replace all or only a fraction of the general filler, especially mineral filler , in the material.

In papermaking, it may be advantageous to mix into the fibrous pulp containing vegetable fillers one or more agents commonly used in papermaking to increase the dry strength properties of the web, such as natural starch or starch treated chemically, enzymatically or with heat, dextrins , polyvinyl alcohols, casein, animal glue water, vegetable proteins, cellulose esters such as carboxymethyl cellulose, alginates, dispersions of synthetic polyamines, carboxylated or non-carboxylated styrene butadiene latexes, acrylic latexes, styrene acrylic latexes, vinyl acetate latexes, neoprene latexes, acrylonitrile latexes, vinyl chloride latexes and mixtures of these.

The amount of these natural or synthetic-organic polymers that act as a mass or surface binder can vary within very wide limits depending on the application, but generally it is between 0.1 and 10 parts by weight of dry binder per 100 parts by weight of fiber for the usual applications and especially for packaging paper and cardboard and printing/writing paper, but it can be much larger, i.e. between 10 and 50 parts by weight and preferably between 10 and 30 parts by dry weight per 100 parts by weight of the fibrous web for special applications such as, for example, base materials for the production of composites, coating and cover layers.

It may also be necessary to improve the wet strength properties of the fibrous webs according to the invention, in particular with additives commonly used in papermaking, for example urea formaldehyde and melamine formaldehyde resins, glyoxal, polyalkylene amines, especially those that are cationic and cross-linked, and condensation products of melamine formaldehyde and aminocaproic acid .

In addition to fiber and vegetable fillers, alone or together with other fillers or pigments, with or without the use of natural or synthetic-organic polymers to improve the dry and wet properties, it is also possible to use: - glue water used in paper industry to reduce the paper's sensitivity to water, such as modified resins, paraffin emulsions and dimeric

alkylketenes;

- pH regulators such as aluminum sulphate and sulfuric acid; and

- anionic and/or cationic retention agents to reduce material loss during the formation of the web.

The following may be mentioned in particular: polyethyleneimine, polyamidoamine and polyalkylamine resins, especially those that are cross-linked, polyacrylamide resins, especially modified polyacrylamide resins, as well as quaternary ammonium compounds.

Other common additives used in papermaking are also possible:

antifoam agents

fluorescent whitening agents

dyes or toners and

fungicidal and/or bactericidal agents.

According to another aspect of the invention, these vegetable fillers can first be chemically treated to give them visual properties and physical or chemical characteristics that they do not have in their natural state, before they are mixed into the mass. Examples that can be mentioned are treatment that helps to modify the color of the wood particles, fungicidal, bactericidal and fire-retardant treatment or treatment that helps to reduce the plant material's sensitivity to water.

Web containing the vegetable fillers according to the invention can be produced on an ordinary paper or cardboard machine with one or more horizontal, inclined or vertical wire sections which can optionally be equipped with round form rollers with single or double wires. This web can be single-layered or multi-layered with layers of the same or different composition, as is particularly the case for cardboard.

The fibrous web according to the invention, which contains vegetable fillers, can also undergo various surface treatments commonly used in papermaking, on or off the paper machine, with the means for surface smoothing, impregnation, coating and surface coating known to paper producers and in further treatment.

The vegetable filler according to the invention can be used in the mass and on the surface during the production of the fibrous paper tap. It is mixed into the pulp either directly, like any other common paper filler, or preferably in the form of a mixture of the vegetable filler and organic binder which is first homogenized and then flocculated (especially using a multi-stage flocculator) before is mixed into the aqueous, fiber-containing suspension before the inlet box. If necessary, the surface of the fibrous paper tap is ironed by means of conventional methods for surface treatment of paper and cardboard, in particular by means of coating, surface coating and/or impregnation according to the known technology mentioned above (specific Belgian patent BE-A-425 432 , International Patent Application WO 86/05 195 and British Patent GB-A-1 464 381).

The vegetable filler according to the invention can be used directly in the production of coating and paint. The main purpose is to reduce the material density. The secondary purposes, which are also of value, are to increase the material thickness and give the material better volume as well as the favorable properties in terms of better opacity as well as sound, heat and electrical insulation.

The best mode of carrying out the invention for paper and board applications is set forth below:

Step 1

The cellulose fibers in aqueous suspension are refined in the traditional way to a Schoepper-Riegler freedom (°SR) of between 15 and 70 degrees, depending on the application, at a variable concentration of between 20 and 350 g/l, especially between 20 and 60 g /l, using standard conical or two-disc raflens, or especially between 250 and 350 g/l with special raflens for so-called high-consistency refining used for the production of packaging substrates. If necessary, other types of synthetic or mineral fiber, either alone or in combination, can be mixed in at this stage. Fiberglass is especially useful when it comes to improving the dimensional stability of the track.

At this stage, the fibrous composition can be constant if it is used to produce a single-layer web, or variable if it is used to produce a multi-layer web, which is particularly the case for cardboard.

Step 2

The vegetable fillers are produced from vegetable waste and mainly from waste products from the timber industry and forestry. This waste will usually first be torn and ground when it arrives in large pieces to obtain a vegetable raw material with a par-ticicle size such that d95 < 5 mm before the final micronization grounding. This is usually the case for milling chips, saw shavings, planer chips, small branches, tree stumps, bark and corncobs. The first shredding and grinding treatment is not necessary when the vegetable waste is sawdust. When the vegetable material is wet (average moisture content is usually about 30 percent), it must be dried until the residual moisture is less than or equal to 15 percent before the micronization grinding to produce vegetable fillers with the particle size and density necessary for the applications according to the invention .

These vegetable fillers will have a d95 of less than 150 micrometres and especially a d95 < 100 micrometres, i.e. at least 95 per cent of the wood particles will pass through a square-mesh sieve of 150 x 150 micrometres, or respectively a square-mesh sieve of 100 x 100 micrometres. These vegetable fillers can originate either from a micronizing mill unit at the paper or board manufacturing site, or from an external facility.

The vegetable fillers are easily transported to the storage unit mechanically by conveyor belt or conveyor screw, or by means of pneumatic devices, before they are used at the production site in an integrated plant or before they are delivered to external customers in sacks, in loose weight or partially loose weight.

Step 3

The vegetable fillers with the desired particle size can be prepared directly in the pulp, in the same way as normal paper filler. The amount of vegetable filler can vary from 1 to 50 parts by weight and in particular from 1 to 30 parts by weight per 100 parts by weight of fiber for ordinary packaging or printing and writing paper or cardboard, but it can also vary from 60 to 600 parts by weight of vegetable filler per 100 parts by weight of fiber for special applications such as substrates for coating and impregnating building materials and wall and floor coverings.

These vegetable fillers can also be added to the mass before the filler is mixed, homogenised and possibly flocculated with an organic binder.

This operation takes place continuously in a multi-stage flocculator, which makes it possible to control the homogenization, concentration and dilution conditions so as to achieve the required diameter of the filler-binder floccule before it is fed into the inlet box circuits of the paper or board machine.

Step 4

After the fiber and vegetable filler have been mixed, it is possible to prepare the mass with the other traditional additives and auxiliaries that are necessary, depending on the end product you want to achieve.

The gram weight of the paper or paperboard web can vary between 20 and 500 g/m 2 , but for special applications this gram weight may be much higher, for example 600 to 1000 g/m 2 for certain types of thick paper and coating.

This technology can be advantageously used to produce paper and cardboard, and in particular packaging paper, paper for corrugated cardboard, paper and cardboard for graphic purposes, kraft packaging paper, pressed cardboard, cardboard for liquid packaging, kraft box lining paper, newsprint, printing/writing substrates, substrates for impregnation with resins, paper and cardboard for industrial and special purposes, paper for household purposes, substrates for coating, and coatings.

Incorporation of the micronized vegetable filler according to the process in the invention has a beneficial effect on the dewatering of the paper or cardboard machine and is therefore beneficial for productivity. For heavier track material, the improvement in dewatering is very significant.

Further advantages and distinctive features of the invention will become clearer in the following description of examples, intended as an illustration showing the use of these vegetable fillers particularly in the paper sector.

EXAMPLE 1-3

Manufacture of kraft paper

In order to evaluate the properties that the vegetable fillers according to the invention provide, samples of hand web with a gram weight of approximately 200 g/m^ were prepared as a basis for comparison. Example 1 applies to paper made according to a traditional recipe according to known technology, and examples 2 and 3 apply to paper produced according to the invention. The amount of the various ingredients (expressed in parts by weight) and the method are summarized in Table I below. The results obtained are given in Table II below.

Table II shows that the use of the vegetable filler according to the invention gives the fibrous webs good, general properties in terms of mechanical strength, more specifically when the vegetable filler is preflocculated with a binder. The products in examples 2 and 3 according to the invention show an increase of 16 percent in thickness and a reduction of 12 to 15 percent in density compared to the product in example 1 which was produced according to a traditional recipe according to known technology. It was also found that the products in examples 2 and 3 had better smoothing compared to the product in example 1. The webs in examples 2 and 3, which were produced using the vegetable filler, are more porous and dewater more easily on the hand web wire.

EXAMPLE 4-5

Production of kraft paper for mail bags

In order to have a basis for comparison, two samples of kraft paper with a gram weight of 120 g/m^, intended to be used in the production of mail sacks, were produced according to the quantities (expressed in parts by weight) and methods indicated in Table III below, where the product in example 4 was a paper according to a traditional recipe according to known technology and where the product in example 5 was a paper containing a vegetable filler according to the invention, coated with natural starch. The results obtained, which are summarized in table IV below, show that preparation of the vegetable filler according to the invention is very beneficial for the thickness (8 percent increase in example 5 compared to the control in example 4).

- PURPOSE

One of the most important properties of kraft paper for mail bags, next to the usual mechanical strength properties and appearance of a friction-glazed kraft paper for this type of use (tear factor, burst factor, tensile strength, evenness and gloss level), is the bulkiness. which is important for the machinability of paper converted on modern equipment for the production of envelope bags, as well as for the marketing effect.

- RESULTS

The supply of vegetable material coated with natural starch has a beneficial effect on the thickness of the web: an increase of approximately 8 percent without changing the paper's mechanical properties. The good retention ability that the vegetable filler according to the invention has, should be taken ad notam.

It is also worth noting the good smoothing properties and the significant increase in thickness (thickness is inversely related to bulkiness), which has a very good effect on stiffness, which varies cubically with thickness.

- ECONOMIC BENEFITS

The reduction in product cost according to example 5 compared to the control in example 4 is around 6 percent, without counting the increase in productivity due to better dewatering.

EXAMPLE 6-8

Production of paper to be coated with plastic

Paper webs with a gram weight of approximately 210 g/m 2 were prepared according to the amount of ingredients (expressed in parts by weight) and the procedure in Table V below. The results obtained are summarized in Table VI below.

These results show that in this particular case the products in examples 7 and 8, which contain a vegetable filler according to the invention, have 30 to 40 percent lower density than the product in example 6 which was produced according to the recipe according to known technology.

The compositions in examples 7 and 8 are very economical (waste from sawmills and tree stumps) with less synthetic binder, which explains the slightly poorer properties in terms of mechanical strength, but these physical properties are well above the traditional requirements for substrate materials to be coated with plastic and which are intended to be used in the production of building materials.

It has also been shown that webs with vegetable fillers according to examples 7 and 8 show good heat resistance. The significant increase in thickness and reduced density affects the sound attenuation that the material or coating provides.

EXAMPLE 9-10

Production of feather-light kraft paper

Examples 9 and 10 below show the advantages of micronized vegetable filler according to the invention (cf. example 10 compared to the control in example 9), used in a fibrous composition of unbleached kraft pulp and chemical mechanical pulp for the production of multi-layer cardboard (especially so-called wooden cardboard and gray cardboard) .

It turns out that if approximately 10 percent of chemical mechanical mass is replaced with micronized vegetable filler coated with natural starch, this does not affect the mechanical properties of the final web product, especially the stiffness, for an equal or slightly greater density. The material produced according to example 10 of the invention has greater porosity and better dewatering than the control in example 9. The improvement in dewatering represents a significant advantage with regard to productivity. Generally speaking, the composition in example 10 is five percent more economical than the composition in the control in example 9.

The procedure for producing cardboard in examples 9 and 10 is indicated in table VII below, and the properties of these types of cardboard are compared in table VIII below.

EXAMPLE 11-12

Production of substrates to be impregnated

Substrates to be impregnated with phenolic resin and intended to be used for the production of laminated panels (plates) were produced, where the product in example 11 was produced according to a traditional recipe according to known technology, and where the product in example 12 was produced with a vegetable filler according to the invention. The make-up ratio (expressed in parts by weight) and the procedure are summarized in Table IX below. The results of these experiments are reproduced in Table X below.

Table X shows that the product in example 12 according to the invention is 30 percent thicker and has a 21 percent lower density than the product in example 11. The situation is particularly advantageous because it means that the number of webs (layers) that make up the inner cores of laminated panels (plates) , can be reduced.

EXAMPLE 13

A base material intended for an industrial composite material is coated with a composition consisting of 100 dry weight parts Mobil EF 78 BE hot melt and 20 dry weight parts vegetable filler (particle size d95 < 50 micrometers, dgo < 10 micrometers, moisture content less than 15 percent before preparation in the aqueous fiber suspension ), and where the above-mentioned vegetable filler is mixed in after the hot-melt has been melted. The manufactured product has better opacity.

EXAMPLE 14-15

Production of substrates to be impregnated for the production of laminate

panel (plate)

Example 14 (produced according to a traditional method according to known technology) and example 15 (produced by means of the process in the invention with a micronized vegetable filler) were carried out to produce a kraft substrate which was later to be impregnated with phenolic resin for the production of laminated panels .

The basic properties that are desired in such substrates are: even formation of the fibrous web material as well as the correct porosity and capillary rise for the most even possible resin absorption at the desired level, taking into account the properties required for laminated panels.

The composition of the ingredients and the method for producing the webs in example 14 (control) and example 15 (according to the invention) are summarized in table XI below. The properties of the webs produced are shown in Table XII below.

The numerical values in Tables XI and XII clearly show the advantages of using micronized vegetable filler according to the invention, namely: clearly better fullness (+18 percent when comparing the product in Example 15 with the control in Example 14) absorbent fiber (scrap fiber, junker fiber), which is expensive, is replaced with ordinary softwood fiber on one side and with vegetable filler on the other side, both cheaper than the above-mentioned absorbent fiber, and

the possibility of using less refined fiber (30 degrees SR freedom for the fiber in example 15 instead of 26 degrees SR freedom for the fiber in example 14).

When comparing the product in example 15 with the control web in example 14, these advantages give a significant increase in productivity with regard to (i) the production of substrates to be impregnated on the paper machine (with a view to better dewatering) and (ii) the impregnation device when phenolic resin is used.

In short, according to the invention it is found that the cost of producing the web in example 15 is at least 15 percent lower than the web in example 14.

EXAMPLE 16-17

Manufacture of kraft lining

Example 16 (produced by traditional method according to known technology) and example 17 (produced by means of the process in the invention with a micronized vegetable filler) were carried out to produce a power transmission line. The purpose was to increase the volume while retaining the physical characteristics of the control track in example 16.

The composition of the ingredients and the method for producing the webs in example 16 (control) and example 17 (according to the invention) are summarized in table XHI below. The properties of the webs that were produced are shown in Table XIV below.

The numerical values in Tables XIII and XIV show that the web in example 17 provides 12 percent better density and a 5 percent reduction in burst resistance. This strength reduction can be remedied (when taking into account the wide porosity tolerance in the fibrous web product in Example 17) by means of a small increase in the fiber's SR degree.

Claims (5)

1. Fibrous sheet or web material which in its mass contains a vegetable filler and which is obtained by papermaking techniques, from an aqueous suspension containing fibers and a vegetable filler, characterized in that the vegetable filler has such a particle size that (i) in the at least 95 percent by weight of said vegetable filler's particles have dimensions that are less than 150 micrometers, and (ii) at least 80 percent by weight of said vegetable filler's particles have dimensions that are greater than 10 micrometers, said vegetable filler being obtained by means of a micronization grinding operation from vegetable waste with a residual moisture content of less than 20%, and that said vegetable filler originates from such plant species that the sieve analysis distribution and the micronization grinding conditions lead to a filler density that is lower than 500 kg/m<3>, preferably lower than 300 kg/ m^, and that the fibrous sheet or web material comprises ter a weight ratio between vegetable filler and fibers that lies within a range from 1:100 to 6:1. 2. Process for producing a fibrous sheet or web material by papermaking technology, comprising mixing a powdered vegetable filler into an aqueous dispersion containing fibres, characterized in that a vegetable filler is used with a particle size that is such that (i) in the at least 95% by weight of said vegetable filler's particles have dimensions less than 150 micrometers, and (ii) at least 80% by weight of said vegetable filler's particles have dimensions greater than 10 micrometers, said vegetable filler being obtained by means of a micronization grinding operation from vegetable waste with a residual moisture content of less than 20%, and that said vegetable filler originates from such plant species that the sieve analysis distribution and micronization grinding conditions lead to a filler density that is lower than 500 kg/m^, preferably lower than 300 kg/m^, which procedure allows density a is reduced, the thickness is increased and the drainage of the fibrous sheet or web material is improved. 3. Method as stated in claim 2, characterized in that said vegetable filler is obtained by means of a micronisation grinding operation from vegetable waste with an average particle size of less than 5 mm. 4. Method as stated in claim 3, characterized in that said vegetable filler originates from vegetable waste with a residual moisture content of less than 15%. 5. Method as stated in claim 2, characterized in that said vegetable filler has a particle size that is such that at least 95 percent of said vegetable filler's particles have dimensions that are smaller than 100 micrometres.