Papermaking using modified sheet silicates as microparticles

1 . A process for making paper, wherein the paper retention and/or drainage step is done in the presence of a microparticle which is a sheet silicates containing amino groups, sulphonic acid groups and/or mercapto groups.

2 . The process according to claim 1 , wherein in that the sheet silicates are modified with a silane which has, bonded to a silicon atom, a group of the formula I and/or II and/or III

—B—(SO 3 M) p —  (I),

—B—(SH) p —  (II),

—B—(NH 2 ) p   (III),

in which

B denotes a (p+1)-valent bridge member,

p is a number from 1 to 3 and

M represents hydrogen, alkali metal or ammonium.

3 . The process according to claim 1 , wherein the sheet silicate, contains at least 0.02 mmol, based on 100 g of solid sheet silicate of an alkylsilane of the general formula

(CH 3 ) q Si(OR) m (OH) p —CH 2 ) n —X

in which

X denotes SO 3 M, SH or NH 2 and

m and p each denote a number from 0 to 3,

q is 0 or 1 and

the sum of q and m and p is 3,

n=1 to 15,

M represents an element from the group consisting of the alkali metals, alkaline earth metals or ammonium,

R represents C 1 -C 3 -alkyl.

4 . The process according to claim 1 , wherein the sheet silicate is of the montmorillonite type or of the sheet silicate type containing montmorillonite, contains at least 0.02 mmol, based on 100 g of solid montmorillonite, of an alkylsilane of the general formula

(CH 3 ) q Si(OR) m (OH) p —CH 2 ) n —X

in which

X denotes SO 3 M, SH or NH 2 and

m and p each denote a number from 0 to 3,

q is 0 or 1 and

the sum of q and m and p is 3,

n=1 to 15,

M represents an element from the group consisting of the alkali metals, alkaline earth metals or ammonium,

R represents C 1 -C 3 -alkyl, in particular methyl or ethyl.

5 . The process according to claim 1 , wherein the sheet silicate contains at least 0.02 mmol, based on 100 g of solid sheet silicate, of an alkylsilane of the general formula

Si(OH) 3 —(CH 2 ) 3 —X

in which

X denotes SO 3 M, SH or NH 2 .

6 . The process according to claim 1 , wherein the sheet silicate comprises sheet silicates or clay minerals or clay mineral-containing allevardite, amesite, beidellite, bentonite, fluorohectorite, fluorovermiculite, mica, halloysite, hectorite, illite, montmorillonite, muscovite, nontronite, palygorskite, saponite, sepiolite, smectite, stevensite, talc, vermiculite and synthetic talc types and the alkali metal silicates maghemite, magadiite, kenyaite, makatite, silinaite, grumantite, revdite and the hydrated forms thereof and the associated crystalline silicic acid and other inorganic sheet compounds.

7 . A sheet silicate containing sulphonic acid groups and/or mercapto groups and having a sulphur content, based on SiO 2 of the sheet silicate, of 0.02 mmol to 1000 mmol, based in each case on 100 g of sheet silicate (mmol/100 g).

8 . A sheet silicate according to claim 7 containing sulphonic acid groups and/or mercapto groups and having a sulphur content, based on SiO 2 of the sheet silicate, of 0.2 mmol to 400 mmol, based in each case on 100 g of sheet silicate (mmol/100 g).

9 . Inorganic sheet silicate compounds wherein they contain at least 0.02 mmol, based on 100 g of solid sheet, of an alkylsilane of the general formula

(CH 3 ) q Si(OR) m (OH) p —(CH 2 ) n —X

in which

X=SO 3 M, SH or NH 2 and

m and p each denote a number from 0 to 3,

q is 0 or 1 and

the sum of q and m and p is 3,

n is 1 to 15,

M represents an element from the group consisting of the alkali metals, alkaline earth metals or ammonium,

R represents C 1 -C 3 -alkyl.

10 . The inorganic sheet silicate compound according to claim 9 which is of the montmorillonite type or of the sheet silicate type containing montmorillonite.

11 . The sheet compounds according to claim 9 , wherein they contain at least 0.02 mmol, based on 100 g of solid sheet, of an alkylsilane of the general formula

Si(OH) 3 —(CH 2 ) 3 —X

in which

X has the meaning stated in claim 7 .

12 . Sheet silicate compounds according to claim 9 , wherein the unmodified forms are used as a basis of the inorganic sheet compounds modified according to the invention, it being possible for these to be both synthetic and naturally occurring sheet compounds, such as the sheet silicates or clay minerals or clay mineral-containing allevardite, amesite, beidellite, bentonite, fluorohectorite, fluorovermiculite, mica, halloysite, hectorite, illite, montmorillonite, muscovite, nontronite, palygorskite, saponite, sepiolite, smectite, stevensite, talc, vermiculite and synthetic talc types and the alkali metal silicates maghemite, magadiite, kenyaite, makatite, silinaite, grumantite, revdite and the hydrated forms thereof and the associated crystalline silicic acids and other inorganic sheet compounds.

13 . Modified sheet silicate compound according to claim 9 , wherein the zeta potential thereof is equal to or greater than the zeta potential of the unmodified sheet compound.

14 . Modified compounds according to claim 7 to 9 , wherein the colloidal stability is increased in comparison with the unmodified samples.

15 . A process for making paper, wherein the paper retention and/or drainage step is done in the presence of a microparticles which is a inorganic sheet silicates according to claim 7 or 9 .

16 . A process for the preparation of the compounds according to claim 7 or 9 , wherein inorganic sheet compounds which have cationic exchange capacities between 10 and 200 meq/100 g and alkali metal or alkaline earth metal ions as opposite ions are used and these sheet compounds are used in aqueous dispersions or dispersions in mixtures of water and polar solvents having mass concentrations <30%, and aqueous silane solutions (corresponding to 1-6) having mass contents of <20% are added to these dispersions, the ratio of silane to sheet compound corresponding to 0.02 to 5 times the cationic exchange capacity of the sheet compound used and the preparation temperatures being between 0 and 100° C. and the pH of the dispersions being between 1 and 10.