FI117757B - Starch acetate composites, process for making them and use in making paper and cardboard - Google Patents

Description

117757 Starch acetate composites, process for their preparation and use in paper and board production 5

Field of the Invention

The present invention relates to novel starch acetate composites which can be used e.g. paper and board, and a process for making composites. The invention also relates to the use of composites as a filler and coating pigment for paper and board. The invention further relates to a process for making paper and board and a method for coating paper and board.

15 Prior Art The purpose of coating is to provide the paper and board with as smooth and homogeneous a surface as possible to improve optical properties and printability. The coating consists of a pigment such as kaolin, powdered calcium carbonate (GCC) and talc, and a binder such as latex and starch, and * · · * »· *; it may also contain additives, such as dispersants, pH adjusters, lubricants and microbicides. The pigment is usually 80 to 95% by weight of the coating, so this is particularly important for the optical properties of the coating, such as opacity, brightness and gloss, low light absorption of the pigment and a high light scattering coefficient of 25 improve the brightness, and the latter also the opacity.

* · Ί *, ···. Gloss is affected by, for example. pigment particle sizes post-• • treatment of paper or board, such as calendering.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * The amount of filler depends on the product being manufactured; - 10% and in pulp paper 15-30% by weight of base paper. Fillers include '2,117,757 for example kaolin, calcium carbonate and titanium dioxide. The filler also affects the optical properties and printability of paper and board. A significant portion of the filler material may be derived from the waste material resulting from papermaking.

5

The optical properties of paper and board can be improved by increasing the proportion of pigments in the coating and the amount of filler in the base paper. However, in this case, the strength properties of the paper and the coating are reduced.

Starch is typically added to the pulp as an aqueous solution in the manufacture of paper and board, primarily to improve the strength properties of the product. If the starch is added to the pulp in granular form, its strength advantage is based e.g. its gelatinization with a drying section. Among other things, limited adsorption, runnability problems, and cost limit the use of cooked starch.

Grinding of pulp and addition of fines can also improve the strength properties of the paper, but at the same time the opacity is often reduced.

A patent application FI20040741 describes a process for the preparation of starch-based pigments. * for the manufacture of a menthol or filler and a starch based pigment or filler product. The presented products are light, biodegradable and suitable for particle size or structure as a coating pigment and filler. One of the products described in · * · * is a spherical starch derivative such as starch acetate. 25 having an average particle size of 90 to 1000 nanometers.

WO 99/16972 describes the use of alkali metal silicates, and in particular sodium silicate.

* · · '· * * Together with starch to improve the strength of paper or cardboard. Both • · * ··· * silicate and starch are added in a finely divided form to the fiber slurry at the wet end before forming the web. The starch is uncooked and the alkali-silicone is selected which is not soluble in water at wet end temperatures but only at the temperature of the drying section.

US 6,623,555 describes a process for making a composite pigment from precipitated calcium carbonate (PCC) and silicate. The composite pigment is prepared by introducing the soluble silicate compound into an aqueous medium containing precipitated calcium carbonate formed by carbonation of lime milk. The insoluble silicon compound is precipitated on the formed calcium carbonate by carbonating the reaction mixture, i.e., bubbling CC 2 into the reaction mixture.

10

Optical properties and pile strength, often described as Scott Bond values, are some of the key features of printing papers. In general, paperboards and papers, especially graphic papers, have a need to improve both optical and strength properties simultaneously.

15

When incineration with energy production, waste paper containing inorganic mineral pigments generates large amounts of ash, the disposal of which causes problems. The EU has set targets for the share of bioenergy in total energy production by 2010. To achieve these goals, it is desirable to use as much organic as possible in paper and board as much as possible.

Inorganic mineral pigments also increase the weight of paper and board. • · * * ** for lighter paper, but with high quality weights. 25 properties, there is a growing need for e.g. in magazines, catalogs and the like.

From the foregoing, it can be seen that there is an obvious need for a newer, lighter paper and board filler and coating pigment. - "· *"; "" which can improve the optical properties of paper and cardboard in particular, but also at the same time the strength properties, and to increase the use of renewable and the proportion of combustible organic materials in paper and board.

Objective 5 of the Invention

It is an object of the invention to provide novel starch acetate composites.

It is also an object of the invention to provide a process for preparing starch glycate acetate composites.

io

A further object of the invention is the use of a starch acetate composite as a filler for paper and board and as a coating pigment in the manufacture of paper and board.

It is a further object of the invention to provide a process for making paper and board.

It is also an object of the invention to provide a method for coating paper and board.

The characteristic features of the starch acetate composites of the invention, their manufacturing process, their use, and the coating and manufacturing processes of paper and board are disclosed in the claims.

SUMMARY OF THE INVENTION The invention relates to starch acetate composites. The composite according to the invention comprises: starch acetate particles having a light scattering material on the surface. • Light scattering materials include, for example, silica, silicon "** ϊ 30 coatings, precipitated calcium carbonate (PCC), gypsum, calcium oxalate, • • 5 117757 Dioxide, Aluminum Hydroxide, Barium Sulphate or Zinc Oxide, or Modifications or Combinations thereof, or any other light scattering material.

In the process of the invention for the manufacture of starch acetate composites, the starch acetate is coated by precipitation with a light scattering material as defined above.

The resulting starch acetate composite can be used as a filler for paper and board to improve the combination of optical and strength properties of the product. In addition, the composite of the invention may be used as a coating pigment for paper and board.

In the following, the invention will be illustrated by means of figures and detailed description, and by way of example but not intended to be limited thereto.

15

Figure 1a shows an electron microscope image (1200x magnification) of uncoated starch acetate.

***** Figure Ib shows an electron microscope image (1200x magnification) of a silicate-coated starch acetate composite prepared according to Example I V: 201.

· * · ·

Fig. 2a is a graphical representation of a starch acetate composition according to the invention.

The light scattering coefficient of sheets containing 10% by weight and 20% by weight of SA4 (prepared according to Example 1) or SA2 (prepared by modifying the method of Example 1) as a function of tensile index. By comparison, sheets with uncoated starch, containing 4 wt% and 8 wt% of API (API) and 8 wt% filler, have no filler. SA2 90 ° C, SA4 90 ° C and API 90 ° C represent heat-treated sheets prior to drying at 90 ° C.

·: * ·: 30 • · * · · • · · · 6 117757

Figure 2b is a graph showing the light scattering coefficient of sheets containing starch acetate composite filler of the invention as a function of splitting strength. The filler contents and character descriptions used are as in Figure 2a.

5

Figures 3a, 3b and 4 graphically show the tensile index, light scattering coefficient, and splitting strength of sheets containing starch acetate composite filler according to the invention as a function of filler content. The explanations of the characters are as in Figure 2a.

10

Detailed Description of the Invention

Surprisingly, it has been found that the problems encountered in the prior art solutions can be avoided or at least substantially reduced by using the procedure of the invention. The invention is based on the discovery that starch acetate may be coated with a light scattering material such as silica, silicate, precipitated calcium carbonate (PCC), gypsum, potassium oxalate, titanium dioxide, aluminum hydroxide, barium sulphate, zinc oxide, yielding a starch acetate composite suitable as both a coating pigment and a filler in the manufacture of paper and board.

··· · • ·

The particle size of the starch acetate used in the composite of the invention is in the range of 0.05 to 10 µm. Preferably, the starch acetate is spherical starch acetate. The degree of substitution of starch acetate may be 0.5 to 3, and preferably 1.5 to 3. The higher the degree of substitution of the starch acetate, the better the composite made from it will maintain its shape at higher process temperatures, e.g. light scattering properties are better retained in the wreckage cycle.

· · · ': The starch acetate useful in the invention can be prepared by any of * 30 known production methods, for example, native, hydrolyzed, oxidative. starch, cross-linked or gelatinized starch, e.g. by reaction with acetic acid- 7 7 75757 hydride or acetic acid chloride. The starch may be any starch derived from natural starch, such as potato, wheat, corn, barley, sorghum, tapioca or rice. Starch acetate can be prepared e.g. according to FI 107386, FI20040741 and FI20040743.

5 A light scattering material is selected as the coating material for the starch acetate. Suitable light scattering materials include e.g. silica, silicate, precipitated calcium carbonate (PCC), gypsum, calcium oxalate, titanium dioxide, aluminum hydroxide, barium sulfate, zinc oxide and the like, as well as modifications and combinations thereof. Preferably, the light scattering material is silicate.

The silicate used in the composite is selected from metal silicates, such as alkaline earth metal silicates, alkali metal silicates, alkaline earth metal and alkali metal aluminum silicates, and modifications thereof, e.g. co-salts with alkaline earth metal salts and hydroxides, and the common salts and combinations of the above compounds. Preferably, the silicate is calcium silicate, magnesium silicate, sodium aluminum silicate, sodium magnesium silicate, sodium silicate, or aluminum silicate, and particularly preferably sodium aluminum silicate.

According to the invention, various combinations of coating materials can also be used.

* · · Φ · · ...

The composite according to the invention contains 5 to 95% by weight of the coating material, preferably 5 to 20% by weight or 50 to 80% by weight of the composite. The coating material is 5 · · · »it *" - 20 wt.% Of the composite, preferably when the products utilizing the composite are to be disposed of by incineration and minimizing ash formation. 5 - * ·· * With a coating amount of V * 20 wt.%, An improvement in the combination of optical properties and readability of the product according to the invention is achieved.

"* ·: 30 • · • · · • •» * »g 117757

The thickness of the coating may vary over a wide range, typically between 1 nm and 5 µm.

In the process of the invention, for the manufacture of a starch acetate composite, the starch acetate is coated with a light scattering material by precipitation.

The coating can be accomplished by adding a precipitant to the suspension containing the starch acetate particles, and optionally adjusting the pH and temperature to a suitable range. Optionally, the starch acetate-containing suspension is combined with an aqueous solution of the precipitating compound and optionally an auxiliary salt before the precipitating agent is added. If necessary, after the addition of the precipitating agent, the precipitating compound is added in the form of an aqueous, alcoholic or alcoholic / aqueous solution or gaseous and / or acid or crystals of the precipitating substance.

The starch acetate used in the process of the invention comprises starch acetate particles having a particle size in the range of 0.05 to 10 µm.

The light scattering material used in the process of the invention may be *! 1 ·: mm. silica, silicate, precipitated calcium carbonate (PCC), gypsum, calcium: V: 20 lettuce, titanium dioxide, aluminum hydroxide, barium sulphate, zinc oxide or the like, their modifications or combinations, - * 1 l can also be coated by adsorption, gas phase coating, 25 spin coating, or the like. Thus, it is also possible to coat • 1 M.1 starch acetate by modifications of these coating methods, such as modified gas phase coating, such as atomic layer epitaxy, ··· ehί i eh ALE (Atomic layer epitaxy). However, these methods are not ·· »covered by the following requirements.

30 • · · • · t ♦ ·· ··· '.

9 117757

Thus, in the manufacture of the starch acetate composite according to the invention, it is possible to coat the starch acetate by contacting the starch acetate particles with the light scattering material and allowing it to adsorb onto the starch acetate particles.

5

Further, in the manufacture of the starch acetate composite according to the invention, it is possible to coat the starch acetate acetate by contacting the starch acetate particles with the gaseous starting materials, dissociating and / or chemically reacting the starting materials with the gaseous phase and forming solid coatings on the starch acetate.

In addition, in the manufacture of the starch acetate composite of the invention, it is possible to coat the starch acetate acetate by coating the aqueous layers comprising starch acetate particles and light scattering material with a spin coa-15 Ting process, letting the layers solidify and result in solidified crumbs.

Precipitation of silica ····· Silica, i.e. silica (SiO 2), can be precipitated, for example, according to the following reaction scheme (1). A suitable precipitant, i.e., a basic metal silicate and an aqueous solution of sodium silicate (water glass) as an example, are reacted with a succulent compound, here mineral acid, typically H 2 SO 4.

• · 4 • f: '.: • · 1 · [Na20: xSi02] + H2SO4 —►xSi02 + Na2SO4 + H2O (1) 25 4 • .i. · Precipitated silica is also obtained by reacting an alkali metal silicate with sulfuric acid. or with sulfur dioxide. In addition, an aqueous solution of alkali metal sulfite or - 4 bisulfite is formed.

4 444 * 1 • 4 * 44 4 • • 1 1 1 4 • 4 • 1 »* · 4 • 4 10 1 1 7757

Alloying of Silicates H

Synthetic silicates are obtained by reacting a silicon compound as a precipitating agent with a precipitating compound. The precipitating compound may also be formed during the in situ reaction. The result is silicates such as sodium aluminum silicate, calcium silicate and aluminum silicate. Of these, especially sodium aluminum silicate is most commonly used in papermaking.

Suitable precipitating agents include precipitated silica, metal silicates such as alkaline earth metal silicates and alkali metal silicates, alkaline earth and alkali metal aluminum silicates, and modifications thereof such as common salts with salts and hydroxides of alkaline earth metals, and combinations of the foregoing compounds.

A silicate, for example sodium aluminum silicate, can be precipitated according to the following reaction formula (2). Aluminum sulfate or alum reacts with an aqueous solution of sodium silicate.

[Na 2 O: xSiO 2] + A 12 (SO 4) 3 -> Na 2 O · Al 2 O 3 - 4 [x SiO 2] -4- 6 H 2 O + Na 2 SO 4 (2) • · · 1 · 1 · 20 Alternatively, alkali metal silicate may be reacted with aluminum sulfite. ; aqueous solution to give a precipitated alkali metal aluminum silicate and *: 1 ·: an aqueous phase containing alkali metal sulphite or bisulphite depending on the pH of the final *: 1 reaction step.

The precipitated alkali metal aluminosilicate is also obtained by treating the alkali metal silicate solution with an alkali metal aluminate in the presence of sulfur dioxide, sulfuric acid solution, or sulfuric acid solution. In addition, an aqueous T-phase containing the alkali metal sulfite is obtained. The precipitating aluminum sulphite reagent is then formed in situ during the reaction.

·· 1 30

····· -'V

♦ · · • · · ··· · 11 117757

The zinc silicate can be precipitated by mixing the sodium silicate solution and the zinc chloride solution so that, at the end of the reaction, the zinc chloride solution is replaced by a sulfuric acid solution.

5 Calcium carbonate precipitation

Precipitated calcium carbonate, or PCC, is obtained, for example, according to the following reaction formulas (3) to (5).

CaCOi + energy -> CaO + C ()> (3)

CaO + H 2 O - »Ca (OH) 2 + energy (4) 10 Ca (0 H) 2 + CO 2 —► CaCO 3 + H 2 O + energy (5)

In reaction (3), the limestone is heated to decompose to lime, CaO, and carbon dioxide. Next, in reaction (4), lime is mixed with water to form slaked lime, Ca (OH) 2. At this stage, any impurities can be removed, for example, by screening. Calcium carbonate precipitates in the carbonation-15 step where carbon dioxide is introduced into the aqueous slurry of slaked lime in reaction (5). At this stage, the particle size, particle size distribution and particle shape of the precipitated calcium carbonate as well as the surface properties of the particles can be influenced by adjusting the reaction conditions.

* · 20 Calcium carbonate can also be precipitated according to the reaction formula (6). In it ϊ #:: The slaked lime reacts with sodium carbonate. The reaction liquor is neutralized before CaCO.3 is used in papermaking.

..li * Ca (OH) 2 + Na 2 CO 3 -> Ca CO 3 + 2NaOH (6) ** In addition, calcium carbonate can be precipitated by reacting sodium carbonate and calcium chloride according to formula (7):

Na2C03 + CaCl2 - * CaC03 + 2 NaCl (7) · * · • · · · · · · ·

Gypsum Precipitation ····· 30 Calcium sulphate occurs in various aqueous and non-aqueous forms, * ·, · of which calcium sulphate dihydrate, CaSO 4 · 2H 2 O, is commonly referred to as gypsum. Di- • 12 117757 Hydrate is the most stable form of calcium sulphate and is therefore used in coating pigments. The spontaneous precipitation of the dihydrate form is known from the formation of scale, and the precipitation occurs from supersaturated solutions according to the reaction formula (8).

5 Ca2 + + S042 '+ 2H20 -► CaS04-2H20 (8)

The dihydrate is also precipitated from the calcium sulfate hemihydrate, CaSCV / VitLO, when slurried in water, according to reaction formula (9). By adjusting the precipitation conditions, the particle size distribution and particle shape of the gypsum to be precipitated can be influenced.

10 2CaS <V / 2H20 + 3H20 -► 2CaS04-2H20 (9)

In addition, the dihydrate form precipitates when the calcium phosphate is reacted with sulfuric acid in aqueous solution according to the reaction formula (10). Phosphoric acid is also formed in the reaction. ;

Ca3 (PO4) 2 + 3H2SO4 + 6H2O-> 3CaSO4-2H2O + 2H3PO4 (10) 15

Reaction of crude phosphate, Caio (PO4) 6F2, with sulfuric acid in aqueous solution forms the dihydrate of calcium sulfate, phosphoric acid and hydrofluoric acid according to the reaction formula (11):

Caio (PO4) 6F2 + 10H2SO4 + 20H2O —► 19CaSO4-2H2O + 6H3PO4 + 2HF (11) 20 · · · · The dihydrate form of calcium sulfate also precipitates when aqueous hydrogen sulfide and oxygen react according to the reaction formula (12). In addition, sulfuric acid is produced.

Ca (HS03) 2 O) + 02 (g) + 2H2O (1) -► CaS04-2H20 (s) + H2SO4 (12) 25 "• · · '• t · * Precipitation of calcium oxalate ♦ · · * · * ·· · * Calcium oxalate may be prepared by precipitation from oxalic acid in the presence of a calcium-containing compound, for example calcium, calcium carbonate, calcium hydroxide or calcium chloride Preparation of calcium oxalate Calcium oxalate and oxalic acid is described in Reaction Equations (13) to (14).

CaCO 3 + 2HCl -> CaCl 2 + H 2 O + CO 2 (13) t j 13 117757

CaCl2 + H2C204 -> CaC204 + 2HCl (14)

Precipitation of titanium dioxide

Titanium dioxide can be prepared e.g. by the known sulfate process, i.e., Liu-5, taking dried and ground ilmenite or titanium slurry with concentrated sulfuric acid and heating to obtain a solid reaction product cake. The reaction product cake is dissolved in water or dilute sulfuric acid and the solid impurities removed from the resulting titanium sulfate solution, e.g. by filtration. The iron content of the solution can be further reduced by cooling the solution, whereupon the iron precipitates as iron sulphates) as a dehydrate which can be removed by filtration. The solution is concentrated to precipitate titanium as the titanium (IV) oxide hydroxide, which, if necessary, is filtered, washed and converted to the desired crystal size and shape by rebellion. The titanium dioxide thus obtained can be coated on the surface of the starch acetate by, for example, adsorption or spin coating.

15

Titanium dioxide can also be prepared as described in U.S. Patent No. 6,001,326, that is, by adding ice cubes of water or freezing water to an undiluted titanium tetrachloride solution, diluting the resulting titanyl chloride aqueous solution to the desired concentration and heating the solution to a fine precipitate.

• • • • • • * * ·

Precipitation of Aluminum Hydroxide .. * · * Aluminum hydroxide, also known as aluminum trihydrate, can be made from bauxite by dissolving the aluminum contained in bauxite and separating other mi-25 minerals. The aluminum compounds of the solution are extracted with sodium hydroxide and the insoluble impurities are separated by settling and filtration. Cool the clear sodium · · · · * ♦ ·· * aluminate filtrate and, if necessary, add to it the nucleus crystals, fine alumina crystals and starch acetate which have been specially prepared for this purpose. The aluminate in the filtrate crystallizes on the core crystals and the starch acetate added to the filtrate.

• · • «· • *« • · lvi · '' 'i4 1 1 7757

Precipitation of barium sulphate

Barium sulfate may be precipitated from water-soluble barium compounds by water-soluble compounds containing a sulfate group. The barium compound may be, for example, barium nitrate, sulfide, hydroxide or chloride and the sulfate-containing compound sodium 5 or magnesium sulfate or sulfuric acid. The preparation of barium sulfate from barium chloride and sodium sulfate is described in Reaction Equation (15).

BaCli (aq) + Na 2 SO 4 (aq) -► BaSO * (s) + 2NaCl (aq) (15)

Precipitation of Zinc Oxide Zinc oxide can be precipitated by heating zinc nitrate to form zinc oxide, nitrogen dioxide and oxygen. Zinc oxide can also be precipitated by heating zinc carbonate to form zinc oxide and carbon dioxide.

In addition, zinc oxide may be precipitated with calcium oxide or calcium hydroxide from a solution containing zinc ions, or by hydrolysis of zinc acetate with lithium hydroxide or tetramethylammonium hydroxide in an alcoholic or alcoholic / aqueous solution.

Thus, in one embodiment of the process of the invention, the aqueous suspension containing the starch weapon is optionally combined with an aqueous solution of the precipitating compound and may optionally be added as an excipient, followed by addition of the precipitant as such or in the form of an aqueous solution. or - * as a slurry and optionally precipitating the compound as an aqueous, alcoholic or alcoholic solution, or as an aqueous or gaseous and / or acidic or precipitating substance crystal, * * · * · * ··· * optionally adjusting the pH and temperature area.

The precipitating compound is selected when precipitating silicates and silica, inorganic acids, sulfur dioxide, and salts of alkaline earth metals, alkali metals, earth metals, zinc and aluminum, preferably sulfate. , sulphite, nitrate, and ammonium sulphate salts, preferably by precipitation with aluminum sulphate: aluminum sulphite or alkali metal aluminate in the presence of sulfur dioxide, sulfuric acid or sulfuric acid. can also be filtered through zinc chloride, which is replaced at the end of the reaction with a sulfuric acid solution.

For the precipitation of calcium carbonate, the precipitating compound may be, for example, gaseous carbon dioxide or sodium carbonate.

When gypsum is precipitated from calcium phosphate or crude phosphate, the precipitating compound is sulfuric acid. When precipitating gypsum from calcium hydrogen sulfite in aqueous solution, the precipitating compound is gaseous oxygen. When precipitating from the supersaturated solution, any compound which liberates sulfate ions when dissolved in water can act as the precipitated compound. Alternatively, no precipitating compound is required when precipitating calcium sulfate dihydrate from an aqueous slurry of hemihydrate.

When precipitating calcium oxalate, the precipitating compound is oxalic acid.

15

When titanium dioxide is precipitated, instead of adding the precipitating compound, the precipitated material can be heated to precipitate fine titanium dioxide.

*: * ·: When precipitating aluminum hydroxide, add '•' il 20 crystals of aluminum hydroxide instead of the precipitating compound.

* · • · * • »· * ·· ·

In the precipitation of barium sulphate, the precipitating compound is a sulphate-containing compound such as sodium or magnesium sulphate or sulfuric acid.

For precipitation of zinc oxide, the precipitating compound is, for example, calcium oxide, - * * * *; “* hydroxide, lithium hydroxide or tetramethylammonium hydroxide. When the precipitating agent is zinc nitrate or zinc carbonate, the precipitating compound is not necessarily * * · ♦ required.

• · · * · * * • * · • f ·; The salt used as auxiliary in the precipitation of silicates and silica is selected from alkaline earth metal salts and hydroxides. Suitable salts include earth.

, 6 1 1 7757 Chlorides, sulphates and carbonates of alkali metals such as magnesium and calcium. Magnesium hydroxide is preferably used.

The precipitating agent is selected from the group consisting of precipitated silicas, alkali metal and alkaline earth metal silicates, alkali metal and alkaline earth metal aluminum silicates and modifications thereof, such as co-salts with alkaline earth metal salts and hydroxides, and the compounds mentioned above. and combinations.

10 When precipitating silica, the material to be precipitated is selected from alkali metal and alkaline earth metal silicates.

When precipitating calcium carbonate, the precipitating agent is, for example, calcium hydroxide or calcium chloride. Calcium hydroxide is obtained by mixing non-slaked lime with water to react with calcium hydroxide.

When gypsum is precipitated, the precipitated substance is calcium phosphate, potassium sulphate hemi-hydrate, crude phosphate, calcium hydrogen sulphite or any compound which liberates calcium ions when dissolved in water.

: V: 20 • ·: When precipitating calcium oxalate, the precipitating agent is any calcium-containing compound, such as calcium chloride, calcium carbonate or calcium hydroxide ·: * di.

····.

For example, when precipitating titanium dioxide, the precipitated material is too nearly ori di.

The precipitating agent when precipitating aluminum hydroxide is sodium aluminate.

When precipitating barium sulfate, the precipitated substance is a barium compound, for example barium nitrate, sulfide, hydroxide or chloride.

• * t * · • * · # · 17 117757

In the precipitation of zinc oxide, the precipitating agent may be, for example, zinc nitrate, zinc carbonate or zinc acetate.

In the process of the invention, the aqueous suspension of the dispersed or slurried starch acetate 5 is optionally combined with an aqueous solution of the precipitating compound and optionally an excipient salt. The precipitating agent is then added as such or in the form of an aqueous solution or slurry and optionally the precipitating compound in the form of an aqueous, alcoholic or alcoholic / aqueous solution or gaseous and / or acid or core crystals of the precipitating agent. If necessary, the pH and temperature of the reaction mixture is adjusted to a suitable range depending on the precipitating compound and the precipitating agent.

In a preferred embodiment of the process of the invention, the precipitating compound (aluminum sulfate (Al 2 (SC> 4) 3x14.3H 2 O)) is dissolved in an excess of water, which may be in the range of 10 to 99 ° C, preferably 20 to 60 ° C. Starch acetate, which is dispersed in excess water, is then added to the solution. Optionally, a salt, preferably magnesium hydroxide, may be added to the suspension thus prepared to aid in precipitation and the mixture is stirred at a temperature of 10 to 99 ° C. Thereafter, a * '* "· compound (metal silicate and here sodium silicate (Na 2 SiCl 4)) and an aqueous solution of • * V: 20 (aluminum sulphate) are precipitated by precipitation. The desired silicon compound (sodium silicate) is then added. minesilicate) precipitates on the surface of starch acetate particles, resulting in a * suspension containing a silicate coated starch acetate composite.

»· · ····· The viscosity of the suspension is adjusted by adding water. The pH of the suspension is adjusted to 9 or less, preferably in the range of 4-8 using a precipitating compound (aluminum, 25 sulfate). The suspension can be used as is without further treatment / filtration / drying and, optionally, also filtered, washed and dried. If necessary, the particle size can be optimized, for example, by grinding. Excipients such as dispersants may be added to the suspension ··· • «* * · * * if desired.

• · · * · • · ··· * '• · · · | • · • »• · • *

* * V

j i ', 18 117757

In the manufacture of the starch acetate composite according to the invention, it is also possible to coat the starch acetate by adsorbing the light scattering material onto the starch acetate particles.

Further, in the manufacture of the starch acetate composite according to the invention, it is possible to coat the starch acetate with a light scattering material using a gas-phase plating method, or a modified gas phase plating, for example atomic layer epitaxy.

10 In gas phase coating, the coating is formed from gaseous feedstocks by chemical reactions. The reaction may be e.g. pyrolysis, reduction, oxidation, hydrolysis or synthesis. As precursors, halides, hydrides, metal carbonyls, organometallic compounds and the like can be used. When coated with the gas phase coating process, the light scattering material is preferably zinc oxide, silica or titanium dioxide, the preparation of which by the gas phase coating process is illustrated by the reaction formula (16).

TiCl4 + 202 - »Ti02 + 2C12 (16) ·? ** ϊ In addition, in the manufacture of the starch acetate composite of the invention, it is possible to coat the starch 0 *:, V 20 lysacetate with a light scattering material to form a · ·,: · club starch acetate layers by t ***** spin coating or the like. The layers can be layered from 0 to 00 ... J in any order, and their number is not limited. Once the layers • 00 '0 0 * ··. * Have solidified, they can be crushed to the desired grain size for use.

The starch acetate composite according to the invention can be used as a filler for paper and 000 V carton. The filler composite used has a particle size of 0 00 preferably in the range of 1-2 µm. The composite according to the invention is suitable for filler; 30 for both fine papers and mechanical pulp papers, examples include LWC, ULWC, MWC and SC.

0 0; '19 1 1 7757

The starch acetate composite of the invention can also be used as a coating pigment for mechanical pulp papers, such as LWC printing papers, and for board, such as FBB board. The particle size of the composite used as the coating-5 pigment is preferably in the range of 0.2 to 1 µm.

Starch acetate is used in the pharmaceutical industry e.g. tablet matrix, tablet coating, and drug-containing microparticles. Starch acetate 10 is also a commonly used food additive. The starch acetate composite of the invention can also be used in the pharmaceutical industry and the food industry, where it is coated in these areas acceptable agent such as sodium aluminum silicate, potassium aluminosilicate, kalsiumalumiinisilikaatilla, aluminum silicate, calcium silicate, magnesium silicate, magnesiumtrisili 15-silicate, silica, calcium sulfate, calcium carbonate, or the like.

In the process of the invention for the manufacture of paper or board, a coated starch acetate composite is added to the

II

"** ϊ in connection with the pulp at a suitable point in the system before the press • · ·. ·. · 20 tin, preferably in a short rotation and particularly preferably near the headbox • ·: as at the suction side of the mixing pump or near the headbox feed pump the filler content, i.e. the amount of coated starch acetate composite in the paper or board is 1-50% by weight, and then the paper or ·· ♦ * «* ··· * board is made in a conventional manner. other fillers, coated starch acetate does not soften or gelatinize at the temperature of the drying • 9 · Drying can be accomplished conventionally by means of • • *; * tactical or cylindrical drying, typically with a surface temperature of 100 ··· ...

V ··· - 160 ° C, but drying can also be accomplished by any other drying method.

·: ··: 30 • ♦ • · · ♦ ·· • *: 20 1 17757

In the process of coating the paper, the coated starch-chelate acetate composite is applied as the above suspension as such or admixed with binders such as starch or latex, thickener such as carboxymethylcellulose or other additives used in known coating pigments. The application to the paper or board web can be accomplished by any known coating method.

The coated starch acetate composite according to the invention has several advantages over fillers and coating pigments known in the art.

The composite can advantageously influence the critical properties of paper and board, in particular optical properties such as opacity, but also strength properties such as pile strength and tensile index. It is particularly advantageous that the composite can improve the combination of light scattering coefficient and column strength. In addition, when compared with conventional starch fillers, the composite improves the properties of the pulp because it does not lose its optical power and its ability to bind to the pulp in the rotation cycle. In addition, the basis weight of paper and board can be reduced using composite.

The composite according to the invention makes it possible to increase the proportion of renewable organic materials in paper and board and to improve the utilization of recovered paper and board by incineration. In the EU, • • • • • • • • • • • • • • • • • • • • • • • • • • Posting of postal material to landfill will be banned in the future, so incineration will remain an important waste disposal option.

25 ♦ · »» · • * 1 1 • · · · · · 1 1 1 1 1 1 1 f 1 f 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • «« • 1 · • · 21 117757

EXAMPLES Example 1 Preparation of Silicate Coated Starch Acetate Composite

A silicate-coated starch acetate composite was prepared on a laboratory scale by precipitating the silicate on starch acetate particles having a particle size of 5-8 µm here in 41 crystallization vessels. The reagents were thermostated before 10 feeds and the pH of the reaction mixture was measured during the reaction. To the crystallization vessel were added 9 g of granular aluminum sulphate having a solids content of 76.2% and 1009.8 g of deionized water, 180.8 g of 20.2% starch acetate slurry, diluted with 466 g of deionized water and additionally 0, 97 g of magnesium hydroxide. The mixture was stirred at 17 ° C. Then, 414 g of sodium silicate having a dry solids content of 43.5% and 91.9 g of aluminum sulfate dissolved in 391.74 g of deionized water were added to the mixture within 4 min and at a starting temperature of 17 ° C, and the mixture was stirred at 17 ° C. The pH was adjusted to 7 or less during the reaction. The so-prepared starch acetate acetate coated with sodium aluminosilicate. the composite SEM image is shown in Figure Ib, which clearly shows the silicate particle precipitated on starch acetate particles (indicated by arrows) * 1 · * ·: ·, chelates. The particle size of the composite was determined by the laser diffraction method. Par-; • · · ··· * · '

Uggs had a mean size of about 9 µm and a size range of 6 to 30 µm including agglomerated particles. The composite contained about 80% by weight of sodium aluminum silicate and 20% by weight. wt% starch acetate.

··· 25 • i Ψ m · • · · · 1 ** · • · M · • 1 1 * • · ···· '«» «· * • ♦ · • 1 • ·» 1 t «· ···· · * · • · »· 22 117757

Example 2

Use of silicate coated starch acetate composite as paper filler

Pulp containing 70% bleached birch pulp and 30% bleached softwood pulp was made of sheets containing the composite filler SA2 and SA4 of the inventive starch acetate. Correspondingly, sheets without filler (filler-free) and sheets with uncoated starch acetate as filler (API) were used for comparison. Sheets weighing 60 g / m 2 were prepared using SCAN C 26:76. The concentration of uncoated starch lysacetate in the control sheets was 4 wt% and 8 wt%. In the case of composite fillers, the total filler contents were 10 wt% and 20 wt%. Some of the filler sheets were heat treated at 90 ° C for 10 minutes before drying the sheets, which were performed under normal conditions. The light scattering coefficients of the sheets, the peel strengths as Scott Bond values and the tensile indexes were examined by methods SCAN-P 8:93, TAPPI T 569 and SCAN-P 67:93.

"** · Figure 2a is a graph showing the light scattering coefficient as a function of tensile index.

Fig. 2a shows that the composites of the invention can improve the light scattering coefficient of * * compared to uncoated starch acetate without substantially reducing the tensile index. Figure 2b shows the light scattering coefficient ··· * ··· as a function of the splitting strength. This figure clearly shows that the combination of light scattering coefficient 25 and the shear strength property of the uncoated starch gun can be improved by using the composite fillers of the invention · · · · *****. Obviously, the coating improves the optical properties of • • • · * · * uncoated starch acetate. Figures 2a and 2b further show that the composites of the invention achieve good light scattering coefficients * ·· • * * “* and strength properties in both heat-treated (90 ° C) and untreated *” ”30 sheets.

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Claims (16)

1, Starch acetate composite, characterized in that the composite comprises starch acetate coated with a light scattering material. 5 Composite according to Claim 1, characterized in that the starch acetate comprises starch acetate particles having a particle size in the range of 0.05 to 10 µm. Composite according to claim 1 or 2, characterized in that the starch acetate comprises spherical starch acetate. Composite according to one of Claims 1 to 3, characterized in that the light scattering material is selected from silica, silicate, PCC, gypsum, calcium oxalate, titanium dioxide, aluminum hydroxide, barium sulphate, zinc oxide, modifications and combinations thereof. Composite according to one of Claims 1 to 4, characterized in that it contains 5 to 95% by weight of light scattering material, preferably 5 to 20% by weight or 50 to 80% by weight, 20% by weight. * · «• · · Composite according to one of Claims 1 to 5, characterized in that the * * * light scattering material is a silicate selected from alkaline earth metal silicates, alkali metal silicates, alkaline earth metal aluminosilicates, alkali metal. , 25 of aluminum silicates, their modifications, one of the above compounds * * * “I. *, and preferably the light scattering material is • *" ** sodium aluminum silicate. 7, A process for the preparation of a starch acetate composite, characterized in that the process comprises the steps of coating the starch acetate with a light scattering material. 117757 Process according to Claim 7, characterized in that, during the precipitation, a precipitating agent is added to the starch acetate-containing suspension and the pH and temperature are optionally adjusted to a suitable range. 5 Process according to Claim 8, characterized in that the starch acetate-containing suspension is combined with an aqueous solution of the precipitating compound and optionally an auxiliary salt before the addition of the precipitating agent. Process according to claim 8 or 9, characterized in that after the addition of the precipitating agent, the precipitating compound is added in the form of an aqueous, alcoholic or alcoholic / aqueous solution or gaseous and / or an acid or crystals of the precipitating substance. ; A process according to any one of claims 7 to 10, characterized in that the starch acetate comprises starch acetate particles having a particle size in the range of 0.05 to 10 µm. *** ': 12. A method according to any one of claims 7 to 11, characterized in that the light scattering material is selected from silica, silicate, PCC, gypsum, calcium oxide. ί · ί! Salad, Titanium dioxide, Aluminum hydroxide, Barium sulphate, Zinc oxide, ·· 1 1 · Modifications and combinations thereof. * · · • · ·: • 1 · 1 • · * · 2 A starch acetate composite according to any one of claims 1 to 6. . 25 use as a filler in paper or board. • · 1 ♦ · «· ♦ · · • · · · Use of the starch acetate composite ** according to any one of claims 1 to 6 as a coating pigment for paper and board. • · 9 · · 9 · * 2 ♦ ·· «• · · 9 · • 91 9 9 · 9 · ’25 117757 Process for producing paper or board, characterized in that the starch acetate composite according to any one of claims 1 to 6 is added to the pulp and the paper is made in a conventional manner. A process for coating paper or board, characterized in that the starch acetate composite according to any one of claims 1 to 6 is applied as a suspension or mixed with coating adjuvants by a known method on a paper or board web. ·· ♦ · 1 * · · • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · '- · • 1 ··· • · • 1 · • 1 · · 2 · • 1 · • • • • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · VAT · 2 • «* · · • · 117757