EP0433413B1 - Porous, micronized, low density vegetable filler with a controlled particle size and low specific physical and hydraulic surfaces, and method of preparation and use of same - Google Patents

Abstract

The invention, as a new industrial product, relates to a porous, micronized, low density vegetable filler with a controlled particle size and low specific physical and hydraulic surfaces. This vegetable filler is characterized in that (1) with a residual moisture content below 20 % and preferably below 15 %, it has (1a) a d95 particle size of less than 200 micrometers (meaning that at least 95 % by weight of the particles of said vegetable filler will pass through a square mesh sieve with openings of 200 x 200 micrometers), (b) a specific physical surface of less 2 m2/g, (c) a specific hydraulic surface of less 2 m2/g, and (d) a density of less than 500kg/m3 and preferably less than or equal to 300kg/m3; and, (2) it will have been obtained by grinding/micronization at a temperature lower than 150°C and preferably at a temperature lower than or equal to 100°C. This micronized vegetable filler is useful in the fields of pulp, paper, cardboard, and nonwovens on the one hand, and in the fields of composites, paints, coatings and construction materials on the other.

Description

FIELD OF THE INVENTION

The present invention relates, as a new industrial product, to a porous, micronized, sparse plant charge, of controlled particle size and of small specific physical and hydraulic surfaces.

It also relates to the process for the preparation of said vegetable charge, as well as to its use in the field of pulp, paper, cardboard, and nonwovens on the one hand, and in the field of plastics, composites, paint, coatings and materials. on the other hand.

ART PRIOR

The paper and non-woven industries use a wide variety of organic, mineral and synthetic raw materials, the use of these raw materials meets different technical and economic objectives depending on the uses.

It is for example well known that articles for sanitary and domestic uses: sanitary napkins, household paper towels, handkerchiefs, napkins and tablecloths, hand towels and industrial wiping articles, fluff products for baby diapers , for periodic linings, hygienic protective articles, absorbent pads, use cellulose base supports, creped or not, possibly embossed, smoothed, calendered and of composition suitable for obtaining the properties required by the market and which are: the water absorption capacity depending on the fibrous structure of the material, its bulk, its porosity, its ability to crepe, its softness, its elasticity, its flexibility, its mechanical resistance, its appearance properties.

In order to meet its technical and economic objectives, the paper industry uses different cellulosic or synthetic fibrous materials, on the one hand, and various organic, mineral or synthetic chemical adjuvants, on the other.

It is well known that the fibrous composition of a paper has a fundamental role on its bulk, and on its porometric and absorption properties.

In papers for household or sanitary use, cellulose wadding, articles called "tissues", the use of mechanical or chemical-mechanical pulp is common. These are, for example, mechanical millstones or refiners, unbleached or bleached, softwood or hardwood pulps, thermomechanical pulps (TMP) and unbleached or bleached chemical-mechanical pulp of softwoods and hardwoods (CMP or B.CMP). . The most spectacular pastas are the unbleached or bleached thermomechanical pulp of softwood or hardwood (CTMP or B.CTMP) which are intermediate between mechanical and chemical pulp. These CTMP or B.CTMP pastes are made from wood chips which undergo after chemical pretreatment with sodium sulfite, baking between 120 ° C and 170 ° C, refining under pressure and, if necessary, bleaching with hydrogen peroxide and oxygen, for example in one stage or two stages.

refining is an important step in the process because the final quality of the dough depends on its level of fattening or refining, also called the drip index. A CIMP paste from 15 to 25 ° SR is particularly intended for the manufacture of absorbent papers or fluff paste. A moderately refined pulp of 30-40 ° SR can be used for the manufacture of multijet cartons and an even more refined pulp of 40-50 ° SR will rather be used for the manufacture of fine papers or printing-writing.

These mechanical, chemico-mechanical or thermomechanical pastes are commonly used in admixture with chemical pulp of softwood or hardwood kraft or bisulfite and it is also usual to incorporate a certain percentage of recycled fibers called old paper pulp. The main drawback of the CTMP process [like other closely related processes: OPCO (process operated in Canada), TCMP (heat treatment first), PAX (process operated in the USA), SCMP (advanced sodium sulfite treatment) ] is its high energy consumption, which can vary, depending on the level of refining required, from 2400 to more than 3000 kWh per ton of dough.

Traditional mechanical pastes have variable characteristics due to their content of fibers, sticks and fines and this high heterogeneity of the composition has an influence on the homogeneity of the formation, on the regularity of the physical and optical properties and these pastes slow down the draining.

Bisulfite chemical pulps, richer in hemicelluloses than kraft pulps, are also used for the manufacture of household and sanitary articles. Fluff pastes are more resistant than chemical mechanical pastes but with much less interesting hydrophilic properties. Bisulfite pastes are obtained from a complex and expensive process.

All of these cellulose paper pulps have specific surfaces greater than 1 m² / g. For example, depending on the degree of fattening (between 20 ° SR and 50 ° SR), the specific surfaces of a fiber pulp of Bleached softwoods vary between 1.3 and 4 m² / g.

The absorption capacity of a paper can also be improved by the incorporation of chemical additives such as wetting agents: polyglycolic ethers of nonylphenol, octylphenol, fatty alcohols, mixed polyglycolic ethers ethylenepropylene, d fatty acids and derivatives, sorbitan esters, polyglycols, glycerol, alkyl aryl sulfonic acid, ammonium lauryl sulfate, ammonium lauryl ethers sulfate, phosphoric esters, ethoxylated fatty amines, derivatives d 'quaternary ammonium for example, but these expensive additives generate foams and can therefore disturb the course of the manufacture of the material.

The use of synthetic fibers, of a much higher cost than that of cellulose fibers, is only reserved for certain special applications and their use calls for particular process conditions for the desired regularity of the formation of the sheet. .

In 1986, superabsorbent agents appeared, allowing in particular the reduction of the quantity of fluff paste in baby diapers, periodical pads, hygiene articles, but these polymers such as those manufactured by Nippon Shokubai Kegaku, Sanyo Chemical, Kao, Arakawa Chemical in Japan or Alco Chemical in the USA significantly affect the cost price of the final material.

The manufacture of paper and cardboard, and in particular that of paper for household and sanitary use or for certain industrial applications such as papers for impregnating resins, also uses various additives for modifying the optical properties. These are, for example, the conventional dyes of the paper industry which belong to 3 groups: basic dyes with a cationic nature having a particularly high affinity for unbleached fibrous materials and mechanical pulps, anionic acid dyes, direct dyes or nouns with anionic or cationic charge.

It is also customary to use opacifying fillers such as titanium oxide. The use of these adjuvants, which affect the appearance properties of the material, require process adaptations to correctly fix these materials on the fibers (anionic or cationic retention agents, pH adjustment, etc.), and this, in order to reduce losses and pollution.

The manufacturers of paper and cardboard also incorporate into the fibrous suspension, various conventional mass additives for strengthening the properties in the dry and wet state such as, for example, natural or synthetic anionic or cationic organic binders, in particular starchy products, polyvinyl alcohols, latex, vegetable proteins, cellulose esters, urea-formaldehyde and melamine-formaldehyde resins, glyoxal, especially cationic and crosslinked polyalkyleneamines, condensation products of melamine-formaldehyde and amino-caproic acid, polyacrylamides. These mass adjuvants can also be used to obtain particular characteristics concerning the aspect: shading, brightening, coloring, special surface effect, or additives favorable to dimensional stability, inertia, fungicidal agents, bactericides or flame retardant. The manufacture of certain special papers also uses chemical reagents for the identification or forging of papers. All these products are generally incorporated directly into the mass with the need to retain them well in the fibrous texture to reduce material losses during the draining operation and the formation of the sheet but also to reduce pollution : mineral and organic fillers are also used which, as a general rule, improve the drying of the sheet, therefore the productivity, but at the expense of the hand and the rigidity.

Conventional mineral fillers such as kaolin, calcium carbonate and talc, which are of high density and greater than that of cellulose, do not affect the absorbency of the material in which they are introduced. Their good fixation on the fibrous texture also requires retention or special additives. We also know that manufacturers of paper and cardboard and in particular those that are integrated into their raw material but also those that use recycled fibers or waste paper often encounter production difficulties related to the presence, in the mass, of organic materials or suspended mineral or pollutants that clog dressings and wet presses and affect productivity. The manufacturers of paper and cardboard also seek for certain applications an increase in the porosity of the paper but this result is often difficult to achieve or is obtained by raising other problems such as: linting and reduction in mechanical strengths.

The manufacture of composites, coatings and building materials also uses a wide variety of organic, mineral, natural or synthetic plant materials to obtain specific characteristics, but these materials are not made from specific plant charges for be favorable to the fixing of polymers, resins and / or which can confer interesting technical and economic properties on the final material such as sound insulation properties, thermal and electrical properties.

We know of the international application filed on December 14, 1988 under No PCT / FR 88/00610 (under the benefit of a French priority No 87 17 400 of December 14, 1987), enforceable only by virtue of novelty and not of inventive step, a method for preparing a fibrous or sheet material by the papermaking route, said method which comprises the introduction of a pulverulent vegetable charge into an aqueous dispersion containing fibers, being characterized in that said vegetable charge is micronized, has a density of less than 500 kg / m³ and has a particle size such that (i) at least 95% by weight of the particles of said plant charge have dimensions less than 150 micrometers, and (ii) at least 80% by weight of the particles of said plant charge have dimensions greater than 10 micrometers.

Advantageously, the micronized vegetable load according to said international application has a density of less than 300 kg / m³ and is obtained by a grinding-micronization operation from plant waste having an average particle size of less than 5 mm and a residual humidity of less than 20 %.

We know that it has already been reported in the past the possibility of using wood powder or flour as a filler introduced into the mass or deposited on the surface by coating during the manufacture of paper and cardboard.

We know in particular that the summary No 8739 of the review ABSTRACT BULLETIN OF THE INSTITUTE OF PAPER CHEMISTRY, 48 , (No 8), page 938, (February 1978), US-A-3,184,373 and the patent German DE-C-415 675 provide for the incorporation of wood powder into the fibrous mass.

The aforementioned summary No. 8739 recommends, for the manufacture of electrically insulating panels, the use of a mixture of 70-95% by weight of cellulose pulp (kraft fibers) and 30-5% by weight of wood flour, these panels being reported as being more absorbent towards oils and more resistant to surface discharges. This document neither describes nor suggests the use of a vegetable filler having the specific particle size and density of the present invention.

US Pat. No. 3,184,373 relates to the improvement of the retention of fillers in paper and cardboard by means of a retention agent such as polyethyleneimine, melamine-formaldehyde resins and urea-formaldehyde resins, said " fillers "being defined (see column 2, lines 3-34) as being solid or liquid substances and comprising in particular the mineral paper fillers proper, metal powders, thermosetting resin powder, thermoplastic resins, binders, flocculants and wood powder (see column 2, line 27). The particle size of said "fillers" is indicated as being between 60 mesh and 2000 mesh (see column 1, lines 70-71). However, document US-A-3,184,373 does not give any example illustrating the use of said wood powder introduced into the mass; moreover, it neither describes nor suggests the specific grain size and density of the plant charge according to the invention.

Document DE-C-415 675 proposes a sizing process according to which a colloidal dispersion of a submicronic substance (that is to say of a particle size less than 1) is incorporated into an aqueous suspension of fibers (i) micrometer) containing cellulose and coming from the grinding of wood or straw, then (ii) a flocculant. Said submicron substance, which therefore has a particle size significantly smaller than that of the plant charge according to the invention, fulfills a role completely different from that of said plant charge; indeed said submicron substance is presented in DE-C-415 675 as reducing the porosity of the resulting paper by sealing and / or filling the pores of the fibrous web, while according to the invention an increase in porosity is sought.

There are also known coating techniques (on non-fibrous support) or surfacing (on fibrous support in sheet form such as paper and cardboard), in particular from Belgian patent BE-A-425,432, from the international PCT application published WO 86 / 05195 and British patent GB-A-1 464 381, according to which a support is coated with a composition containing wood powder. It turns out that these techniques do not describe or suggest the incorporation into the fibrous mass of the plant charge of specific particle size and density according to the invention.

We also know, in particular from summary No 1523 of the review ABSTRACT BULLETIN OF THE INSTITUTE OF PAPER CHEMISTRY, 58 (No 2), page 184 (August 1987), from summary No 7191, ibidem 55 (No 6), page 754, (December 1984), and of published patent application FR-A-2 612 828 (which was made public on 30.09.1988) of products likely to be incorporated into paper and cardboard, containing cellulose and obtained by physico-chemical treatments of wood shavings or cellulose fibers. Said products containing cellulose have a composition different from that of the vegetable or fibrous source from which they are derived. In fact, the physical and chemical treatments to which said source has been subjected do not preserve the integrity of the components of said source.

More specifically, the abovementioned summary No. 1523 describes the production of cellulose in the form of micronized particles (having a particle size between 5 and 75 micrometers and a degree of crystallinity greater than 65%) by a hydrolytic treatment of cellulose pulps. The cellulose thus obtained is different from the composition of the vegetable filler according to the invention having regard to the nature of the components of the latter.

The aforementioned summary No. 7191 describes the use of microfibrillated cellulose for the production of coating plasters. Here again, the cellulose microfibrils are different by their structure and their composition of the plant charge according to the invention.

The document FR-A-2 612 828 is disappointing in the sense that its claim 1, as published, states the use of wood particles in the preparation of fibrous sheets, when it is in fact a question of the use of an extract, in pulverulent form, obtained by treatment of wood powder, said treatment comprising (see description of this document on page 1, line 28, on page 2, line 12) in particular (i) l impregnation of the wood powder with an appropriate liquid chemical agent, (ii) flash autolysis (or flash self-hydrolysis) of the wood powder thus impregnated under a pressure greater than or equal to 30 bars at a temperature greater than or equal at 230 ° C for at least 90 seconds, then rapid (brutal) expansion, (iii) washing the resulting product with water or a water-dioxane mixture in order to remove the hemicelluloses and most of the lignin, fatty acids and resin acids, then (iv) drying the pro powdery extract thus extracted containing materials insoluble in water and devoid of water-soluble materials.

The present invention differs from the teaching of said summaries No 1523 and No 7191 and of said document FR-A-2 612 828 by the fact that the vegetable load, the use of which is recommended in the mass, has preserved substantially all of it. components from the plant source; in the vegetable load according to the invention only the water content and the content of volatile substances (such as essences of low boiling point) could be affected with respect to the starting vegetable source. So if the vegetable source is wood, we will find in the vegetable load practically all the components of wood as described in the book by FENGEL et al., WOOD CHEMISTRY ULTRASTRUCTURE REACTIONS, pages 26-33, editor D. GRUYTER (1984 ), incorporated here for reference.

OBJECT OF THE INVENTION

The present invention recommends a new technical solution which uses a micronized vegetable filler of particular characteristics for use in the manufacture of pulp, paper, cardboard, nonwovens, plastics, composites, paints, coatings and building materials.

This vegetable load is obtained for economic reasons from vegetable waste which can be mainly wood waste.

• (1) à une teneur en humidité résiduelle inférieure à 20 % et de préférence inférieure à 15 %, elle présente
  • (1a) une granulométrie d₉₅ inférieure à 200 micromètres (c'est-à-dire que au moins 95 % en poids des particules de ladite charge végétale passent à travers un tamis à mailles carrées d'ouverture 200 x 200 micromètres),
  • (1b) une surface spécifique physique inférieure à 2 m²/g,
  • (1c) une surface spécifique hydraulique inférieure à 2 m²/g, et
  • (1d) une densité inférieure à 500 kg/m³ et de préférence inférieure ou égale à 300 kg/m³; et,
• (2) elle a été obtenue par broyage-micronisation à une température inférieure à 150°C et de préférence à une température inférieure ou égale à 100°C.

The new porous micronized vegetable charge which is recommended according to the invention is characterized in that,

• (1) at a residual moisture content of less than 20% and preferably less than 15%, it has
  • (1a) a particle size d₉₅ of less than 200 micrometers (that is to say that at least 95% by weight of the particles of said vegetable load pass through a sieve with square mesh of opening 200 x 200 micrometers),
  • (1b) a specific physical surface of less than 2 m² / g,
  • (1c) a specific hydraulic surface of less than 2 m² / g, and
  • (1d) a density of less than 500 kg / m³ and preferably less than or equal to 300 kg / m³; and,
• (2) it was obtained by grinding-micronization at a temperature below 150 ° C and preferably at a temperature below or equal to 100 ° C.

This new charge according to the invention is prepared according to a process which is characterized in that a plant source to be micronized is subjected to a grinding-micronization operation at a temperature below 150 ° C., preferably at a lower temperature. or equal to 100 ° C, and better at a temperature less than or equal to 70 ° C.

Advantageously, for the final micronization, it is possible to start from a vegetable source having undergone a preliminary treatment for an average particle size less than or equal to 5 mm evaluated at a residual humidity of less than 20%.

DESCRIPTION DETAILED OF THE INVENTION

One of the fundamental characteristics of the invention resides in the fact that the micronized vegetable load has, at a residual moisture content of less than 20% and preferably less than 15% by weight relative to the total weight of said vegetable load, a particle size d₉₅ less than 200 micrometers, and preferably a particle size d₉₅ less than or equal to 150 micrometers [that is to say, in the latter case at least 95% of the particles (percentage expressed by weight) pass through a square mesh sieve in stainless steel opening 150 x 150 micrometers, according to French standard NF X 11501].

In practice at least 80% by weight of the particles have an average particle size greater than 10 micrometers.

According to another characteristic, the vegetable load according to the invention has, at a residual moisture content of less than 20% and preferably less than 15% by weight relative to the total weight of said vegetable load, a specific physical surface and a surface specific hydraulic less than 2 m² / g and preferably less than 1 m² / g.

The specific physical surface can be determined by means of a mercury porosimeter such as the "Micrometric 9200" device which can reach a maximum pressure of 60,000 psi (or about 4.137 x 10⁸ Pa). This technique essentially allows the determination of the dimensions and quantities of the empty spaces and (open) pores of the porous material as well as its specific surface and its density. Mercury is penetrated by immersing the material in the mercury and increasing the isostatic pressure.

où

T =

tension superficielle du mercure,

A =

angle de contact du mercure avec le matériau.

The relation between the pore diameter D and the applied pressure P is settled by the equation: $$\text{(1) D = -4TP⁻¹ cosA}$$

or

T =

mercury surface tension,

A =

mercury contact angle with the material.

This physical specific surface can also be measured by the BET method (designated by the initials of the authors Brunauer, Emett, Teller) by adsorption of krypton in liquid nitrogen.

$$\text{(3) c = W/AL}$$

$${\text{(4) (c/R}}_{\text{p}}{\text{)}}^{\text{1/3}}{\text{= (1/kS}}_{\text{h}}{\text{²)}}^{\text{1/3}}\text{(1-vc)}$$

où

R_p

= résistance spécifique d'une éprouvette (constituée par une matière à tester) à se faire traverser par un fluide (eau), exprimée en cm/g,

A

= surface de l'éprouvette exprimée en cm²,

D_p

= variation de pression exprimée en dynes/cm² [une dyne correspond à 10⁻⁵ N],

q

= débit exprimé en cm²/s,

W

= poids de l'éprouvette exprimé en g,

v

= viscosité exprimée en poises (g/cm/s) [une poise correspond à 0,1 Pa.s],

L

= épaisseur de l'éprouvette exprimée en cm,

k

= constante,

S_h

= surface spécifique hydraulique de la matière à tester exprimée en cm²/g,

v

= volume spécifique de la matière à tester exprimé en cm³/g, et

c

= densité de l'éprouvette à tester exprimée en g/cm³.

The hydraulic specific surface is determined by the Pulmac method from the equations: $${\text{(2) R}}_{\text{p}}{\text{= A²D}}_{\text{p}}\text{/ q (W) v}$$

$$\text{(3) c = W / AL}$$

$${\text{(4) (c / R}}_{\text{p}}{\text{)}}^{\text{1/3}}{\text{= (1 / kS}}_{\text{h}}{\text{²)}}^{\text{1/3}}\text{(1-vc)}$$

or

R _p

= specific resistance of a test piece (consisting of a material to be tested) to being traversed by a fluid (water), expressed in cm / g,

AT

= surface area of the test piece expressed in cm²,

D _p

= pressure variation expressed in dynes / cm² [one dyne corresponds to 10⁻⁵ N],

q

= flow rate expressed in cm² / s,

W

= weight of the test piece expressed in g,

v

= viscosity expressed in poise (g / cm / s) [one poise corresponds to 0.1 Pa.s],

L

= thickness of the test piece expressed in cm,

k

= constant,

S _h

= hydraulic specific surface of the material to be tested expressed in cm² / g,

v

= specific volume of the test material expressed in cm³ / g, and

vs

= density of the test specimen expressed in g / cm³.

The hydraulic specific surface is, given equations 2-4, given by the relation: $${\text{(5) S}}_{\text{h}}{\text{= [(1-vW / AL) ³A²D}}_{\text{p}}{\text{/ qWvck]}}^{\text{½}}$$

A specific physical or hydraulic surface of less than 2 m² / g and better still less than 1 m² / g, which is in particular less than that measured on the cellulose fibers constitutes an important characteristic in terms of drainage. It has in fact been found that the smaller the specific physical and hydraulic surfaces, that is to say less than 1 m² / g, the more the drainage is improved.

According to another characteristic of the invention, the density of the micronized plant charge, measured by means of a mercury porosimeter, at a residual moisture content of less than 20% and preferably less than 15% by weight relative to the weight total of said plant load, is less than 500 kg / m³ and preferably less than 300 kg / m³.

It has surprisingly been found that the micronized vegetable filler according to the invention has a strong adsorbent or absorbent capacity.

In view of this property, it is recommended according to the invention to use the present micronized vegetable filler as a support, vehicle or fixer for various conventional or special mass adjuvants in the paper industry in order to improve homogenization, distribution and retention in the fibrous texture of said adjuvants. These adjuvants can be introduced directly into the fibrous pulp containing the micronized vegetable filler or preferably into said micronized vegetable filler before incorporating it into the aqueous suspension of fibers. The strong adsorptive or absorbent power of the micronized plant filler according to the invention is advantageously exploited for strengthening the mechanical properties in the dry state and in the wet state by fixing on said micronized plant filler polymers, binders, organic resins natural or synthetic. This strong adsorptive or absorbent power can also be used for modifying the appearance of the material and its optical properties by fixing dye, shading agents, brightening agents, fluorescent agents or else on said micronized vegetable charge. specific chemical reagents.

The strong adsorbent or absorbent power can be advantageously used in the field of identification or forging of papers and in particular so-called security papers. The micronized plant charge can also fix certain specific additives such as bactericidal means, fungicidal means and enzymes in order to give the finished material the special characteristics sought such as rot-proofing; the fixation of enzymes, proteins, antibodies or antigens is also useful in the field of microbiological assays using in particular reactions of the antigen / antibody type.

The high adsorbent or absorbent power of the micronized vegetable filler according to the invention is also useful for fixing oils and fats and in particular thus making it possible to manufacture materials for packaging, wiping or even combating pollution.

The strong adsorptive or absorbent power of the micronized vegetable filler according to the invention also makes it possible to fix the organic and / or mineral matter suspended in the dough such as pitch, sticky substances and other undesirable pollutants liable to disturb productivity by fouling of dressings, wet presses, on the one hand, and likely to disturb production on paper and / or cardboard machines due to dusting and linting of fibrous webs.

It has also surprisingly been discovered that the micronized vegetable filler according to the invention can be subjected to a chemical treatment, in particular to a bleaching operation according to a conventional papermaking technique, without giving rise to any re-agglomeration.

Thus, the micronized plant filler according to the invention can be subjected to a chemical treatment or associated with an organic or mineral, natural or synthetic material to give said micronized plant filler appearance characteristics which it does not have to natural state and to modify the optical properties of said micronized vegetable charge or of any material containing said micronized vegetable charge. These characteristics aspects relate in particular to whiteness, opacity, color and regularity of surface. The term “chemical treatment” is understood here to mean, in particular, bleaching, coloring or any mixture with a mineral or organic, natural or synthetic material, such as for example titanium oxide used as a means of increasing opacity.

The micronized vegetable filler according to the invention improves the bulk of the fibrous materials containing it in particular paper and cardboard and is favorable to the rigidity of said paper and cardboard.

In pulp fluff applications for products for household and sanitary uses, the micronized vegetable load according to the invention allows, after incorporation into the aqueous suspension of fibers, a significant reduction in dusting and linting compared with the other conventional solutions using mechanical, chemomechanical and chemothermomechanical fluff pastes.

To obtain the micronized plant charge according to the invention, all plant sources are suitable, in particular the softwood species such as fir, pine, spruce, hardwoods such as birch, beech, hornbeam, chestnut, and others. For essentially economic reasons, the vegetable source will come from vegetable waste and in particular wood waste. Wood waste can for example come from logging (bark, stumps, slash, crowns, small branches which together represent 65% by weight of the standing tree), from the primary or secondary wood processing industry , sawing industry, planing, veneer (crusts, edging, sawdust, planing shavings, scraps of machining, cutting, cutting, slicing and unwinding in parquetry, industrial carpentry, cabinet making, manufacturing particle board and fibrous board). Wood waste usable as a vegetable source can also come from the industries of the use or transformation of wood products, in particular light wooden packaging (crates, crates, boxes, trays), and heavy wooden packaging (boxes, pallets, demolition and construction wood and the like). Wood waste can also come from installations for the production of chemical pulp, these installations produce sawdust, small chips or matches, which as a general rule must be eliminated in order not to affect the yields of cooking and the quality of said pulp. The vegetable source can also come from vegetable waste from the harvest of cereals such as notably corn cob.

When implementing the preparation process of the invention for the preparation of the micronized vegetable filler, it is important to carry out the grinding-micronization operation at a temperature below 150 ° C. Above 150 ° C, the grinding-micronization operation deeply denatures the composition of the plant source and the resulting plant charge, denaturation by heat treatment above 150 ° C being liable to lead to the re-agglomeration of said micronized vegetable charge. In addition, the grinding-micronization operation at a temperature of the order of 200-400 ° C is likely to cause the ignition of the vegetable source and load.

Preferably, the grinding-micronization temperature will be less than or equal to 100 ° C., and better said temperature will be less than or equal to 70 ° C.

As indicated above, depending on the desired applications, the micronized vegetable load according to the invention of natural off-white color can be subjected to a conventional bleaching treatment in the stationery field in order to obtain a vegetable load having a desired whiteness. situating for example between 60 and 90 degrees of white (the measurement of the degree of white being carried out in accordance with the determination of the diffuse reflectance factor of paper and cardboard according to French standard Q 03039; said degree of white being expressed as a percentage relative to a witness with a value of 100%).

According to another aspect of the invention, the unbleached micronized vegetable filler can be subjected to a coloring treatment with conventional dyes from the stationery industry, in particular by means of cationic basic dyes with good affinity for unbleached vegetable matter.

These different treatments can be carried out either after micronization, or even during the use of said micronized plant charge.

By the term "material" is meant here any paper product such as pulp, paper, cardboard, sheets, rolls or any other form of complexes and particularly any product for domestic and sanitary use known as "dish" presented in sheets or reels, or any product called "fluff", that is to say any complex product composed of various ingredients arranged around or in an absorbent mattress composed partially or entirely of defibrated wood pulp "fluff", on the one hand, and any product not stationer chosen from the group consisting of composites, paints, coatings, coatings and construction articles, on the other hand.

One of the important features of this new micronized plant charge, is its excellent ability to disperse or paste in water at very variable concentrations, and this feature will in particular be advantageously exploited according to the invention for the coloring of the plant charge. with small amounts of water (the vegetable load / colorant pasting can be carried out at a concentration greater than 60% and in particular at a concentration of 70-80%). This feature will advantageously be exploited according to the invention for the manufacture of paints, coatings or solutions (aqueous or non-aqueous) for impregnation or coating, on the one hand, but also for the manufacture of composites or colored materials of low density, d 'somewhere else.

Thus, the micronized vegetable filler according to the invention can be combined, as a paper filler, with other conventional additives in the paper and cardboard industry, such as in particular mineral fillers, bonding agents, resins and polymers for reinforcing mechanical properties in the dry or wet state, retention agents, etc.

The micronized vegetable filler according to the invention can be combined with all organic or synthetic paper fibers, that said paper fibers are alone or mixed together. It is therefore in particular possible to introduce the micronized vegetable filler according to the invention into a mixture of fibers made up of so-called recovery cellulose fibers or into a mixture of recovery cellulose fibers and noble cellulose fibers.

As indicated above, the micronized vegetable filler according to the invention can be introduced into the pulp before the manufacture of fibrous sheets, or into the aqueous suspension of fibers at the head circuits of the paper machine during the manufacture of said sheets. fibrous. In addition, said micronized vegetable filler can be incorporated into the dough before or after refining of said dough.

All the known devices for the manufacture of fibrous sheets, such as paper, cardboard and nonwovens, are suitable for the use of the micronized vegetable filler according to the invention, such as for example machines at one table or with several flat tables, machines with single-jet or multi-jet formation, machines with inclined or vertical formation.

The weight ratio of pulverulent plant charge / fibers according to the invention will generally be in the range from 1/100 to 6/1. Advantageously, a vegetable load / fiber weight ratio in the range of 1/100 to 2/10 (and better still from 1/100 to 1/10) will be used for the production of wrapping paper, for that of printing media. writing a weight ratio in the range from 0.3 / 10 to 5/10 (and better from 0.3 / 10 to 2/10), for that of the boxes a weight ratio in the range from 0.5 / 10 to 5 / 10, for that of papers for impregnation a weight ratio in the range from 1.5 / 10 to 5/10 (and better still from 2/10 to 3/10) and for that of special papers a weight ratio in the range of 6/100 to 6/1 (and better from 3/10 to 8/10).

The fibers which can be used for these various applications are in particular natural or synthetic organic fibers such as cellulosic fibers, polyamide fibers, polyester, polyalkylene fibers, polyacrylate fibers, mineral fibers such as glass fibers, ceramic fibers, acicular gypsum fibers, carbon fibers and rock wool, and finally regeneration fibers cellulose. These fibers can be used alone or as a mixture. The most commonly used fibers will be cellulosic fibers originating from kraft or bisulfite chemical pulps, mechanical, thermomechanical or chemico-thermomechanical pulps. These pastes produced from softwood or hardwood species can be unbleached, semi-bleached or bleached.

It is also possible to use so-called recovery cellulose pulp from old paper (such as print-writing media, newspapers, cardboard boxes, packaging paper, magazines and the like), alone or in combination with fibers. noble cellulosics, as indicated above.

According to the invention, the vegetable fillers of controlled particle size can be associated with other mineral, organic or synthetic fillers or their mixtures, these fillers or pigments usual or special from the stationery industry are those which have already been mentioned above.

In practice, according to the invention, the plant charge will replace part of the essential ingredient of the material, namely fibers in the paper industry, on the one hand, and will be able to replace all or only a fraction of the charge. usual including mineral material, on the other hand.

Thus, the micronized vegetable filler can also usefully intervene in the composition of household and sanitary papers to replace part or all of the mechanical, thermomechanical and CTMP pulps.

For a good optimization, when using a fibrous mixture constituted by a chemical pulp in association or not with old paper fibers and mineral fillers, it is recommended to advantageously use 5 to 25% by weight of micronized vegetable filler compared to fiber weight. It has indeed been found that the use of 5 to 25% by weight of micronized vegetable filler relative to the weight of the fibers has a very favorable influence on the overall quality of the finished product, in particular as regards the absorption properties and this at a more attractive cost price.

The micronized vegetable load can also replace in particular 5 to 25% by weight of the TMP and CTMP pulp during the production of newsprint with a beneficial effect in terms of productivity without harming the properties essentially sought for this type of product. , namely: hand, tear resistance, tensile strength, surface roughness and surface resistance for good printability. The surface and absorption properties of the micronized plant filler also allow prior fixing of the binding agent, mainly starch binders, to the plant filler for the overall optimization of the mechanical performance of the final product.

The micronized vogetal load according to the invention provides an improvement in the bulk and rigidity of the packaging papers with a very favorable impact on the cost price. Depending on the destination: manufacture of kraft fibrous sheets, unbleached or bleached, manufacture of flexible packaging, of pouches, envelopes, "kraft liner" and "test liner", it is recommended to use 3 to 15% by weight of filler micronized vegetable according to the invention, relative to the weight of the fibers.

The vegetable load is also interesting in the manufacture of printing-writing papers with or without wood, magazine papers, L.W.C. In this case, said plant charge in particular allows the regulation of the formation of the fibrous sheet to be regulated while promoting bulk and opacity.

The manufacture of multi-jet cartons is also in the field where the vegetable load according to the invention favorably satisfies a large number of important applications in particular with regard to the technical and economic plans. In this case of use, it is recommended to use 3 to 30% by weight of said micronized vegetable filler, optionally combined with a starchy binder, for the improvement of bulk and rigidity.

The micronized vegetable filler according to the invention offers the advantage of dispersing or of becoming very easily impaled in water without any particular additive, in particular up to concentrations up to 85% of dry extract. This property is advantageously used in the field of the coloring of said vegetable load, on the one hand, and in the manufacture of paints and coatings comprising said vegetable load, on the other hand. For this type of application, the unbleached, bleached or colored vegetable load confers on the material into which it is introduced or on which it is applied, particular properties of appearance, bulk, opacity and may, as required, contribute to the improvement of sound, thermal and electrical insulation properties.

In the field of manufacturing papers for laminated panels, the use of 8 to 30% by weight of said micronized vegetable filler according to the invention is recommended, in order to have a very favorable effect on the quality (better absorption) and lower production costs.

The vegetable filler which is the subject of the invention can also bring a certain number of advantages in the manufacture of filtration papers: homogeneity of the porometric properties, increase in the absorbent power, reduction of fluff or dusting, by better optimization of the refining and reduction of the cost of composition, because these papers are produced from expensive special pulp and delicate processing.

It is also advantageous for the manufacture of paper and cardboard with integrated pulp, to incorporate into the machine head circuits, a small percentage of vegetable load object of the invention, to minimize the problems of clogging of the coverings and of fluff with wet presses. For this use, the quantity of vegetable fillers which is recommended is in particular from 2 to 8% relative to the weight of the fibers. At this quantity and at an appropriate level of refining, the vegetable fillers can also increase the porosity of the papers and this result is appreciated for the manufacture of certain packaging krafts, such as in particular the krafts for large capacity bags.

In practice, according to the invention, the micronized vegetable filler will replace part of the essential ingredient of the material, namely paper fibers, on the one hand, but also depending on the destination, part of the other ingredients of the composition of the fibrous sheet such as fillers, mineral and organic pigments, clouding agents and the like, on the other hand.

• (1) présente, à une teneur en humidité résiduelle inférieure à 20 % et de préférence inférieure à 15 %,
  • (1a) une granulométrie d₉₅ inférieure à 200 micromètres (c'est-à-dire que au moins 95 % en poids des particules de ladite charge végétale passent à travers un tamis à mailles carrées d'ouverture 200 x 200 micromètres),
  • (1b) une surface spécifique physique inférieure à 2 m²/g,
  • (1c) une surface spécifique hydraulique inférieure à 2 m²/g, et
  • (1d) une densité inférieure à 500 kg/m³ et de préférence inférieure ou égale à 300 kg/m³; et,
• (2) et a été obtenue par broyage-micronisation à une température inférieure à 150°C et de préférence à une température inférieure ou égale à 100°C.

The process for preparing a fibrous sheet which is recommended according to the invention by the papermaking process and which comprises the aqueous dispersion of fibers and a micronized plant filler, is characterized in that said porous and micronized plant filler

• (1) present, at a residual moisture content of less than 20% and preferably less than 15%,
  • (1a) a particle size d₉₅ of less than 200 micrometers (that is to say that at least 95% by weight of the particles of said vegetable load pass through a sieve with square mesh of opening 200 x 200 micrometers),
  • (1b) a specific physical surface of less than 2 m² / g,
  • (1c) a specific hydraulic surface of less than 2 m² / g, and
  • (1d) a density of less than 500 kg / m³ and preferably less than or equal to 300 kg / m³; and,
• (2) and was obtained by grinding-micronization at a temperature below 150 ° C and preferably at a temperature below or equal to 100 ° C.

In this preparation process, the vegetable filler has been previously incorporated into the fibrous pulp or is introduced into the aqueous suspension of fibers during the operations for manufacturing the material.

In addition, said vegetable charge is likely to have been bleached, colored or to have undergone a particular chemical treatment to obtain specific properties.

For convenience, the following table A lists the units and standards for assessing the characteristics of paper and board.

Other advantages and characteristics of the invention will be better understood on reading which will follow examples of preparation which are in no way limitative but given by way of illustration.

FIRST SERIES TEST COMPARATIVE

The influence of the incorporation of micronized vegetable fillers according to the invention on the absorption properties of a paper pulp used in products for household and sanitary uses has been evaluated.

The corresponding tests were carried out compared to Kraft chemical pulp, bisulfite and a CTMP fluff pulp, at three levels of fattening (or refining).

Operating conditions :

• Disintegration and aqueous suspension of pasta at a concentration of 5% and refining in a Valley stack at 2%.
• Manufacture of fibrous sheets for the control of physical characteristics and absorption on Franck form.
• Pressing according to standard conditions of the form and drying for 4 minutes at 93 ° C.
• 60 g / m² sheets.
• The vegetable fillers are incorporated into the dough after refining.
• Plant charge rate = 25%, unbleached and bleached quality.
• Qualities of the vegetable load:
  WRITTEN QUALITY = CV1 :
  d₉₅ <150 micrometers.
  Specific physical surface = 0.80 m² / g.
  Specific hydraulic surface = 0.55 m² / g.
  Density = 300 kg / m³.
  Whiteness = 48%.
  Humidity = 12%
  BLANCHED QUALITY = CV2 :
  Bleached vegetable load produced from maritime pine wood waste from the Landes.
  d₉₅ <150 micrometers.
  Specific physical surface = 0.65 m² / g.
  Hydraulic specific surface = 0.52 m² / g.
  Whiteness = 70% obtained by bleaching with 4% hydrogen peroxide, with 2% soda, 3% silicate and 0.25% DTPA.
  Pasta tested :
  Dough 1: unbleached kraft of maritime pine from the Landes.
  Dough 2: Bisulfite fluff paste, whiteness = 87%.
  Pulp 3: Swedish softwood CTMP pulp,
  Whiteness = 70%.
  Pulp 4: Bleached softwood kraft, whiteness = 80%.

The compositions used and the results obtained are listed in Tables 1, 2 and 3 below.

• 1°) la charge végétale a un effet très favorable sur les propriétés hydrophiles de la pâte;
• 2°) à un très faible niveau de raffinage, se situant entre 15 et 20°SR, tel que requis en règle générale pour la fabrication des papiers à usages domestiques et sanitaires, le remplacement de 25 % de pâte chimique par de la charge végétale est sensiblement favorable aux propriétés d'absorption qui se retrouvent à un niveau comparable à celles des pâtes fluff bisulfite ou CTMP avec des avantages pour les résistances mécaniques d'ensemble et notamment de la résistance à la déchirure; ledit mélange pâte-charge végétale micronisée est également moins sensible au poudrage et au peluchage et a une meilleure aptitude à l'égoutrage qu'une pâte CTMP et ce résultat est particulièrement important pour la productivité d'autant plus que ladite charge végétale micronisée se disperse très facilement dans l'eau et peut donc être aisément incorporée dans la pâte avec une bonne homogénéisation d'ensemble.

The results of the first series of tests illustrated by Tables 1, 2 and 3, relating to the introduction of vegetable fillers into an unbleached or bleached chemical pulp (without optimization of the process and of the quantity produced), show that:

• 1) the vegetable load has a very favorable effect on the hydrophilic properties of the dough;
• 2) at a very low level of refining, between 15 and 20 ° SR, as required as a general rule for the manufacture of papers for household and sanitary use, the replacement of 25% of chemical pulp by vegetable load is appreciably favorable to the absorption properties which are found at a level comparable to those of bisulfite or CTMP fluff pastes with advantages for the overall mechanical strengths and in particular the resistance to tearing; said micronized vegetable paste-filler mixture is also less sensitive to dusting and fluffing and has a better ability to drain than a CTMP paste and this result is particularly important for productivity, all the more so since said micronized vegetable charge disperses very easily in water and can therefore be easily incorporated into the dough with good overall homogenization.

It is important to note that the loss of whiteness measured with the Suntest UV filter for 30 minutes on the CTMP paste is 4 to 6 points while the loss of whiteness is 2.5 points on the unbleached natural vegetable load.

SECOND SERIES TEST Obtaining tissue paper

Tissue paper is prepared from a weakly refined bleached softwood and leafy Kraft fibrous composition, in which a certain content of bleached vegetable fillers CV2 of the type used in the previous series of tests with other adjuvants is incorporated. usual for this product: softening and shading agents and the characteristics of this paper are checked in relation to a fabric of conventional formulation. These compositions and results are shown in Table 4 below.

The small specific surface area of the plant charge allows a slight increase in the refining of the dough without harming the absorption and resistance properties of the final product. The composition comprising the micronized vegetable filler according to the invention is more economical.

THIRD SERIES TEST Obtaining a high hand print-write paper

A fibrous sheet of high bulk for printing-writing of 70 g / m² is prepared with either a conventional fibrous composition chemical pulp / CTMP or mechanical pulp, or with the vegetable load object of the invention produced from sawmill waste in mixture of softwood / hardwood: unbleached vegetable load of 49.3 whiteness with a d₉₅ <150 micrometers, a density = 280 kg / m³ for a humidity of 14%, a specific physical surface = 0.47 m² / g. The sheets are produced on a pilot machine.

The plant load is favorable for the hand, with improved physical characteristics. This new formulation drips better and is more economical.

The compositions and results are shown in Table 5.

FOURTH SERIES OF TESTS Obtaining unbleached paper for packaging

A paper with vegetable fillers is prepared in order to improve the bulk and the rigidity and compared to a conventional formula. The sheets are drawn on a dynamic form.

Table 6 below highlights the advantage of using the micronized vegetable filler according to the invention.

FIFTH SERIES OF TESTS

The micronized vegetable filler is used as an additive to improve productivity (reduction of linting and clogging of coatings) and mechanical performance.

We incorporate into the fibrous suspension [100% unbleached softwood kraft (refining 20 ° SR)] 3% of vegetable fillers type CV1 and we measure the advantages of the paper made with this new raw material:

Compared to the control test, the following improvements are obtained with the micronized plant filler according to the invention:
Main = + 10%;
Tensile strength = + 3%;
Dynamic stiffness = + 15%;
Static stiffness = + 9%;

Such a result is advantageously exploitable in the field of flexible packaging papers such as pouches, envelopes, corrugated cardboard box covers, corrugated papers and cardboard in particular. It should be noted, for these applications, the advantage of the low specific surface area of the plant charge, which allows better drainage and the fixing of pollutants in the mass which generally affect productivity.

SIXTH SERIES TEST

Use of a micronized vegetable filler for the production of security papers.

Is incorporated into a conventional composition for security paper 1% bleached vegetable fillers CV2 type previously pasted at high concentration (between 60 and 85%), with a fluorescent agent at a dose of 0.3% relative to the charge and 0.01% cationic polyacrylamide. The regular distribution of the particles in the fibrous texture and their specific shape allows easy identification of the paper. The filler can be combined with any other falsification chemical (conventional or specific dyes).

SEVENTH SERIES TEST

Use of a colored micronized vegetable filler for composites or paints and coatings.

The natural plant charge type CV1 above is subjected, after micronization, or before its use in the material, to a prior coloring treatment with a cationic dye and to a high concentration (80-85%); the composition then being: CV1 = 100% and Astraphoxin Red = 0.5% relative to the vegetable load. This can also be obtained with other dyes depending on the desired hues.

This colored vegetable charge is useful in many materials: composites, construction materials, coatings for the reduction in particular of the density or of obtaining specific thermal insulation, acoustic and electrical properties.

EIGHTH SERIES OF TESTS

A pigmented composition for coating is prepared containing a micronized vegetable filler according to the invention, in order to improve the insulation properties of the coated material and to reduce the density.

Sample composition

Kaolin: 80 parts by weight
Alumina hydrate: 20 parts by weight
Acrylic dispersant: 0.15 parts by weight
Polyvinyl alcohol: 4 parts by weight
Acrylic binder: 20 parts by weight
Carboxymethylcellulose: 3 parts by weight
Calcium stearate: 2 parts by weight
Auxiliary agents for shading, anti-oxidation and anti-foam: qs
Water: qs

Test composition

One portion (20 parts by weight) of the kaolin is replaced by 20 parts by weight of vegetable load CV2. This substitution does not affect the rheological properties of the coating bath and the coating allows a decrease in the density of the coated material and improves its characteristics of dimensional stability and insulation.

TENTH SERIES TEST

The present series of tests relates to obtaining a kraft intended for the impregnation of phenolic resins for laminated panels. The compositions and results are shown in Table 7.

the micronized vegetable load contributes in said series of tests to a significant improvement in the hand and absorption characteristics with identical physical properties. This result is interesting for productivity, the new composition according to the invention with CV1 also allows a significant reduction in the price.

Claims (13)

1. A micronized and porous vegetable filler, wherein

   (1) at a residual moisture content of less than 20% and preferably of less than 15%, it has

   (1a) a particle size d₉₅ of less than 200 micrometers (that is to say at least 95% by weight of the particles of said vegetable filler pass through a square-mesh sieve having openings of 200 × 200 micrometers),

   (1b) a physical specific surface area of less than 2 m²/g,

   (1c) a hydraulic specific surface area of less than 2 m²/g, and

   (1d) a density of less than 500 kg/m³ and preferably of less than or equal to 300 kg/m³; and

   (2) it has been obtained by grinding/micronization at a temperature of below 150°C and preferably at a temperature of below or equal to 100°C.
2. The vegetable filler as claimed in claim 1, which has, at a residual moisture content of less than 20%, a physical specific surface area of less than 1 m²/g and a hydraulic specific surface area of less than 1 m²/g.
3. The vegetable filler as claimed in claim 1, which has, at a residual moisture content of less than 15%, a physical specific surface area of less than 1 m²/g and a hydraulic specific surface area of less than 1 m²/g.
4. The vegetable filler as claimed in claim 1, which has been obtained by grinding/micronization at a temperature of less than or equal to 100°C.
5. The vegetable filler as claimed in claim 1, which has been obtained by grinding/micronization at a temperature of less than or equal to 70°C.
6. The vegetable filler as claimed in claim 1, wherein

   (1) at a residual moisture content of less than 15%, it has

   (1a) a particle size d₉₅ of less than 150 micrometers (that is to say at least 95% by weight of the particles of said vegetable filler pass through a square-mesh sieve having openings of 150 × 150 micrometers),

   (1b) a physical specific surface area of less than 1 m²/g,

   (1c) a hydraulic specific surface area of less than 1 m²/g, and

   (1d) a density of less than or equal to 300 kg/m³; and

   (2) it has been obtained by grinding/micronization at a temperature of less than or equal to 100°C and preferably at a temperature of less than or equal to 70°C.
7. A process for the preparation of a porous and micronized vegetable filler as claimed in claim 1, which comprises subjecting a vegetable source to be micronized to a grinding/micronization operation at a temperature of less than 150°C, preferably at a temperature of less than or equal to 100°C and preferentially at a temperature of less than or equal to 70°C.
8. The process as claimed in claim 7, wherein the grinding/micronization operation has been carried out at a temperature of less than or equal to 70°C.
9. A process for preparation by paper-making means of a fibrous sheet, which comprises the production of an aqueous dispersion of fibers and a micronized vegetable filler is a process and wherein said porous and micronized vegetable filler

   (1) has, at a residual moisture content of less than 20% and preferably of less than 15%,

   (1a) a particle size d₉₅ of less than 200 micrometers (that is to say at least 95% by weight of the particles of said vegetable filler pass through a square-mesh sieve having openings of 200 × 200 micrometers), and preferably a particle size d₉₅ of less than 150 micrometers,

   (1b) a physical specific surface area of less than 2 m²/g,

   (1c) a hydraulic specific surface area of less than 2 m²/g, and

   (1d) a density of less than 500 kg/m³ and preferably of less than or equal to 300 kg/m³; and

   (2) and has been obtained by grinding/micronization at a temperature of below 150°C and preferably at a temperature of below or equal to 100°C.
10. The process as claimed in claim 9, wherein said micronized vegetable filler has previously been incorporated in the pulp.
11. The process as claimed in claim 9, wherein said micronized vegetable filler is introduced into the head circuits of the aqueous suspension of fibers.
12. The process as claimed in claim 9, wherein said micronized vegetable filler has been previously bleached.
13. The process as claimed in claim 9, wherein said micronized vegetable filler has been previously colored.