JPH06503127A - Inorganic material slurry - Google Patents

Abstract

There is disclosed a high solids, aqueous suspension of a cationically dispersed particulate inorganic material, characterised in that the particulate inorganic material has a particle size distribution such that not more than 10 % by weight of the particles have an equivalent spherical diameter (esd) smaller than 0.25 microns.

Description

[Detailed description of the invention] Inorganic material slurry The present invention provides a cationic dispersion of inorganic pigments or fillers such as calcium carbonate. Lid relates to aqueous suspensions.

Dispersed inorganic pigments and fillers are known in which the particles have an overall positive charge.

Such cationic dispersion suspensions are used in the paper industry (EP-0278602A) and Useful for coating paper.

The use of inorganic pigments or fillers with a specific particle size distribution improves their cationic dispersion. It was found that one of the nology of the suspension can be improved.

Therefore, according to the present invention, the equivalent spherical diameter (e sd) or having a particle size distribution of less than 0.25 microns. 1. High solids aqueous suspension of ionic dispersed particulate inorganic material Preferably, the suspension has a solids content of at least 60% by weight.

Inorganic materials, when ground into granular agglomerates, are regular particles with a low average particle aspect ratio. , the material is preferably present in the form of spherical particles. Therefore, the material Calcium carbonate may be in either natural or synthetic form. precipitated calcium carbonate (FCC) and chalk can be used, but particularly preferred is crushed marble. Ru. Other possible inorganic materials are gypsum, talc and calcined kaolin clay.

However, other materials with flat plate structures, such as layered lattice silicates such as kaolin clay, It should be recognized that the following examples are within the scope of the present invention.

Preferably, the inorganic material used in the present invention has a , less than about 7.5 ml g−1, more preferably less than about 6.5 m”g−1 and preferably has a specific surface area of at least 2I112 g-1.

The particulate material has an esd of 1% or less of the particles greater than 10 microns and at least 6 It is also preferred to have a particle size distribution with an esd of less than 5% or 2 microns. .

Prior to dispersion, the inorganic material may be ground to the desired particle size distribution. The grinding conditions are prepared in a manner known per se in order to produce materials of varying distribution. I can do it.

The cationic slurry produced by the present invention has a broader particle size distribution in which the inorganic material has a broader particle size distribution. forming a slurry with a predetermined viscosity that has a higher solids content than the slurry with Can be done.

Inorganic materials or pigments or fillers that retain a neutral or positive charge, such as marble, tar, etc. If it is gypsum or calcined kaolin clay, the particles of the material are anionic polymer electrolytically may be dispersed using a dispersant containing a combination of electrolytes and cationic polyelectrolytes. stomach. Here, the cationic polyelectrolyte is added in sufficient amount to make the particles cationic. used in Due to the natural anionic species absorbed on the particle surface when in the raw state , the chalk particles do not have an i-t charge or are treated with a titanium to remove such anionic species. The yolk can be stirred vigorously, and anionic polyelectrolytes and cationic polyelectrolytes can be The tendency for chalk to be effectively dispersed in high solids using a combination of molecular electrolytes. It's across the street.

The high solids aqueous suspensions of the present invention contain at least 45% by weight (if required) dilution to a solids concentration of Paper coatings can be "formulated" by the addition of adhesives.

A thorough discussion of the components of paper coatings and methods of applying such coatings to paper can be found in James P.

By Ca5ey, -Pulp and Paper: Chemistry and In the second board of the book entitled ``Technology,'' Volume 111, Chapter XIX. It is shown. Further consideration, The Br1tish Paper and B oard Industry Federation, London, 19 “An 0perato” by T. W. R. Dean published in 1979. r’s Guide to Apueous Coating for Pa per and Board＋■■■ It is.

The aqueous suspensions of the invention are preferably vigorously stirred before or after suspension. general In addition, vigorous mixing imparts at least 10 kJ of energy per kg of inorganic material. 50kJ per kg or less, preferably about 50kJ or less per kg . Generally, the energy input is 18 to 36 kJ per kg of inorganic material. Dew.

Paper paints can be used in methods of coating sheet members. this Coated papers so formed are particularly suitable for recycling.

Ground marble for use in the present invention contains a chemical dispersant using granular grinding media. is formed by first crushing a lot of marble in an aqueous suspension preferable. Additionally, grinding involves dehydrating a suspension of ground marble, e.g. filtration without additives followed by drying of the pigment and drying in a conventional mill. This is achieved by comminution of the dried product.

Granular pigments are separated using a combination of anionic and cationic polyelectrolytes. Scatter. Preferably, the anionic polyelectrolyte is a water-soluble vinyl polymer, Alkali metal salts or ammonium salts of polysilicic acid or alkali metal salts of polysilicic acid It is an ammonium salt. Most preferably, the anionic polyelectrolyte is poly(acrylic). lylic acid), poly(methacrylic acid), substituted poly(acrylic acid) or substituted poly(methacrylic acid) acrylic acid) or the alkali metal or ammonium salts of any of these acids. . The substituted poly(acrylic acid) may be a partially sulfonated polymer.

Particularly effective anionic polyelectrolytes include acrylic acid and sulfonic acid derivatives of acrylic acid. Alkali metal or ammonium salts of conductor copolymers, sulfonic acid derivatives The proportion of body monomers is preferably 5% to 20% of the total number of monomer units.

The number average molecular weight of the anionic polyelectrolyte is at least 500, preferably 10 Preferably, it is 0,000 or less. The amount used is based on the weight of dry pigment. It is generally about 0.01% to about 0.5% by weight, and about 0.1% to 2% by weight. is preferred.

The cationic polymer electrolyte is a water-soluble substituted polyolefin containing quaternary ammonium groups. It may be Can the quaternary ammonium group be present in the linear polymer chain? It may also be in the branches of the polymer chain. The number average molecular weight of substituted polyolefins is It is preferable that it is at least 1500, and preferably less than I, 000.00 OpI. More preferably, it is in the range of 50,000 to 500,000. necessary and from about 0.01% to about 1.5% by weight based on the weight of the dry pigment. It is common that there is. Beneficial results indicate that substituted polyolefins are (hydrogen or lower alkyl) ammonium salts).

Lower alkyl groups, which may be the same or different, have e.g. up to 4 carbon atoms. and each is preferably methyl. For example, ammonium Salts include chloride, bromide, iodide, salts with HSO, -, salts with CH, SO, - Or it may be a nitrite. Preferably the salt is a chloride. most preferably , the cationic polyelectrolyte is poly(diallyldimethylammonium chloride) ). Alternatively, water-soluble substituted polyolefins include shrimp chlorohydrin and aliphatic It may also be a product obtained by copolymerizing a secondary amine, and the product has the following general formula: Motsu.

In the formula, R and R' may be the same or different, and each represents hydrogen or a carbon atom. A lower alkyl group having 1 to 4 children, preferably methyl or ethyl, X is C1-, Br-11-, H3O,-, CH! So, - or nitrite ion be. The preferred number average molecular weights of this shrimp chlorohydrin product are so, oo o~300.000.

In addition, cationic polymer electrolytes are water-soluble organic compounds whose majority are basic groups. It is preferable that the number average molecular weight is at least io, ooo, It is preferable if it is 1,000.000 or less. Most preferably, the number average molecular weight is At least 50,000. These water-soluble organic compounds can be used as polyacid organic bases. Compounds containing only carbon, hydrogen and nitrogen are preferred; their solubility increases and therefore their possible desorption from the clay in aqueous suspension. It does not contain additional functional groups such as hydroxy or carboxylic acid groups. preferably is an organic compound having a number average molecular weight of 50.000 to 1.000.000. Liethylenimine (PED).Additionally, water-soluble organic compounds that may be used Examples include ethylene dihalide or formaldehyde and ethylene diamine. Mention may be made of polyethylenediamine, which may be a copolymer.

A cationic polyelectrolyte is used in an amount sufficient to render the inorganic particles cationic. Ru. It is common for the zeta potential of the particles to be at least +20 mV after treatment. is typically +30 to +40 mV, usually more than +50 to +60 mV. It's below. These potentials are measured using a “Pen Ken La5er Z” meter. diluted using an indicator electrolyte of potassium chloride (10-'N+) (0,02 % by weight) was measured using a solids suspension.

The weight ratio of cationic polyelectrolyte to anionic polyelectrolyte used is: 21 to 20 l is preferable, and 21 to IO:I is more preferable.

In the method for producing slurry of the present invention, the raw pigment is mixed with a relatively high solids content or a relatively high filtrate. In general, it is obtained as a terque. You can mix it vigorously afterwards. This case was used to provide a dispersed high solids slurry (45-80% solids by weight). Add dispersant to the solution.

Where pigments are to be dispersed using a combination of anionic and cationic polyelectrolytes If so, mix with the anionic polyelectrolyte before mixing with the cationic polyelectrolyte. . This appears to result in a more fluid suspension at higher solids concentrations. .

When an aqueous suspension is to be used for paper coating, other conventional paper coating adjuvants, e.g. such as insolubilizers (e.g. melamine formaldehyde resins), lubricants such as stearyl catalyzes the crosslinking of calcium phosphate and, if present, cationic latex. It may also contain a catalyst, where a preferred such catalyst is sodium bicarbonate. . The amounts of these adjuvants required are known to those skilled in the art.

The adhesives used to make paper coatings may be non-ionic or cationic adhesives. Should. Such adhesives are commonly used in paper coatings where the pigments are anionic. Contrast with anionic adhesives used in Therefore, cationic casein and cationic casein Use onic starch adhesives as well as cationic or non-ionic latex I can do it. Such cationic and nonionic adhesives are readily available for purchase. . The particular cationic or nonionic adhesive used will depend on the printing method to be used, for example. Depends on the method, for example offset printing requires an adhesive that should be water insoluble . For paper to be used for offset printing methods, the amount of adhesive depends on the weight of the pigment. As a standard, it is preferably 7 to 25% by weight, but for gravure printing paper, contact The binder should be used in an amount of 4 to 15% by weight, based on the weight of the pigment. Essential The exact amount of adhesive required depends on the nature of the adhesive and the material being coated. This can be easily determined by one skilled in the art.

The paint is coated on the sheet material using a regular paper coating machine under standard paper coating conditions. It's okay. Paper coated with a cationic paint according to the invention can be coated with a conventional anionic paint. It was found that the paper provided generally similar results to the paper obtained with the spin-on system.

The coated paper that can be made using the present invention can be used as a “waste paper” in the paper manufacturing process. ” or when used as recycled paper, it is a convenient paper.Generally, large quantities of paper are recycled at some point in their manufacture for one reason or another. Also, Lisa The advantages of the paper of the present invention are of paramount importance to the paper industry. That's it Unagami recycled paper uses a process to reduce paper to a fibrous, recyclable state. and paper-making compositions. Including the step of adding fibers.

Such papermaking compositions may include conventional papermaking valves, such as bleached sulfite valves. In general, waste paper fibers and valves are 10: 90 to 60: 40 will be used in the ratio of

Also included in the paper making composition are fillers such as calcium carbonate fillers and and retention aid. The waste paper fibers are derived from paint. of calcium carbonate, so the loading is between 5 and 20% by weight of the total papermaking composition. Is it possible to reduce the amount of calcium carbonate filler to give the full amount of filler? be. The weight of dry broken paper (fibers and fillers) added is approximately 5-30% by weight of the fibers. Preferably within the range.

When the broken paper fibers used are obtained from the coated paper according to the invention, the papermaking composition allows for a reduction in the amount of retention aid used in the product.

The aqueous slurry of the present invention is particularly suitable for paper fillers and is described in Applicant's EP-278 602A' is also incorporated herein by reference.

The present invention will be specifically explained by the following examples.

Example Two calcium carbonate pigments by grinding the low solid sand of marble powder. Manufactured. By adjusting the grinding conditions, we compared products with different distribution widths. . Sedigraf data were obtained as shown in Table I below (percentages are by weight). be): 0.3% >10. [ZIII O, 8%>108m75.5%<2μm 70.2 <2 μm 44.5% <1 μm 48.0 <1 μm 20.0% < 0.5 am 28.5 <0.5 urn6.7% <0.25 μm 14. 3 <0.25μm surface area (BET Nt) 5, Otn"g-' 8.6m" g-' Both samples were filtered to yield a filter cake of 70-75% solids. So After that, this cake was pretreated with sodium polyacrylate (molecular weight 4000). to disperse the cations, followed by a large amount of Boridadmac (with a molecular weight of 500.000). That is, poly(diallyldimethylammonium chloride)) was added. Yang Maintain the weight ratio of ionic polymer to anionic polymer between 3.2 and 3.5:1. did. When measured using a Brookfield viscometer at 1100 rpm, the viscosity is Dilute the suspension with water until it reaches a viscosity of approximately 600 mPa, s, and reduce the solid content of the suspension. The suspension was measured.

Table 0 Amount of dispersed anionic poly Boridadmac in sample A in high speed mixer Solid content Amount of Brookfield acrylate Weight % Weight % Viscosity m Pa, s weight% 0, 11 0.36 70.3 600 Table III Sample 81 variance Polyacrylate amount Polydadomac amount Solid content Brookfield weight % Weight% Weight% Viscosity mPa, sO, II O, 3465,0600 0,1250,4466,6660 0, 1350, 4766, 3635 Therefore, in this example, the crushed marble with a wide particle size distribution is When dispersed, approximately 4 units lower solid bone was obtained for a given rheology.

International Investigation Report Romon/Michi@1/nri+in

Claims (3)

[Claims] 1. A high solids aqueous suspension of a cationic dispersed particulate inorganic material, the particulate inorganic The material has an equivalent spherical diameter (esd) of less than 10% by weight of the particles less than 0.25 microns. The above suspension is characterized in that it has a particle size distribution that is small. 2. High solids according to claim 1, wherein the particulate inorganic material is particulate calcium carbonate. Aqueous suspension. 3. When measured by the BETN2 method, the specific surface area of the granular inorganic material is 7.5 m2g- 3. A high solids aqueous suspension according to claim 1 or 2, wherein the solids aqueous suspension is less than 1.