EP0399079A1 - Base paper for silicone release paper preparation, processes for the preparation thereof and for the preparation of silicone release paper - Google Patents

Abstract

A process for superficially modifying release papers by addition of various organosiloxanes or organopolysiloxanes having at least three hydrogen atoms bound to silicon per molecule in proportions of about 5 to 10% (calculated as solid) to conventional surface preparations for release papers is described, whereby a substantial acceleration of crosslinking for the subsequent coating with solvent-containing or solvent-free addition-crosslinking silicone systems is achieved.

Description

The invention relates to a method for the surface modification of release paper by adding organic silicon as a primer coat in papermaking.

It is known that special silicone polymers have excellent release properties against sticky substances, e.g. Have pressure sensitive adhesives. These silicone polymers are e.g. in amounts of 0.3 g / m to 3 g / m (calculated), usually only in amounts of 0.5 g / m to 1.0 g / m, applied to the coating base paper as a backing material to give the paper adhesive properties . Approx. 50% highly satinised kraft paper is used as coating base paper, but also a large number of other papers ("Das Papier" (1985), No. 10 A, p. V 92 - V 96).

The silicone polymers applied to the carrier paper as a thin film can
- solvent silicones,
- dispersion silicones (aqueous emulsions or
- Be solvent-free silicones, the polymerization of which
- warmth,
- UV radiation or
- electron radiation
can be done.

With a few exceptions, thermal displacement systems are still used today.

Depending on the choice of the thermal crosslinking system, one runs
- condensation polymerization or
- addition polymerization
from.

Due to the shortest curing times, release papers are mainly coated with addition-crosslinking silicone systems, whereby chain-like polymers with vinyl end groups are crosslinked by reaction with hydrogen siloxanes under the influence of temperature and in the presence of predominantly platinum catalysts (see "Adhesion" (1973), No. 7).

However, the polyaddition requires relatively high minimum temperatures as so-called light-off temperatures. For economic reasons, this minimum temperature is often far exceeded in order to achieve shorter crosslinking times (corresponds to higher coating speeds).

Usual processing temperatures for convection drying are therefore
approx. 180 ° C for silicone systems containing solvents,
approx. 120 ° C to 150 ° C for aqueous silicone systems (emulsions) and
approx. 150 ° C for solvent-free silicone systems.
Depending on the type of silicone system used (including additives) and the temperature level, the curing speed is between 2 and 25 seconds

This results in coating speeds of between 150 m / min and 300 m / min that can be achieved industrially.

The polyaddition can also be disrupted by small amounts of inhibiting constituents in the paper. These so-called "catalyst poisons" can delay or in extreme cases prevent the crosslinking reaction (see "Allgemeine Papierrundschau" (1986), No. 14, pp. 367-368). Likewise, the length of time the silicone systems are stored before using them increases the crosslinking time. In the case of extremely smooth paper surfaces, unfavorable interfacial tensions between paper and silicone systems can also lead to flow disturbances and adhesion problems (see "Paper and plastics processor" (1972), No. 17, p. 30).

In general, the release paper is coated with the various silicone polymers on separate systems. This can be explained above all by the high demands on the surface quality of the carrier material before the silicone coating, in particular low micro-roughness, high solvent tightness and uniform thickness in the longitudinal and transverse directions of the paper web. Therefore the Most of all raw papers smoothed in a separate super calender. This is the only way to later apply a uniform silicone film with a high abhesive effect to the backing paper with relatively small amounts of coating. So far it has not been possible to siliconize abhesive papers for the technical sector with a defined and reproducible release force level within the paper machine. On-line siliconization is only carried out if the abhesive effect is low, for example with baking release papers and sack papers with hydrophobic properties. The dried paper web inside the paper machine is used by means of conventional application devices, such as size press, blade or the like. coated with silicone resins.

For this purpose, aqueous silicone systems (emulsions) are used, to which various film formers and thickeners (e.g. starch, alginates, caboxymethyl cellulose (CMC) or polyvinyl alcohol (PVA) can be added in small proportions according to the technical information sheets of the silicone manufacturers. The silicone resin used always forms the main component , since it primarily affects the abhesive effect of the coated paper The mostly 50% aqueous emulsions with added catalyst, eg based on polydemethylsiloxanes, become crosslinkers, eg based on methylated water Substance siloxanes and often also adhesives (eg water-soluble reactive silane esters) and "controlled release" additives.

Certain adhesive tapes, for example carpet adhesive tapes, have lower requirements for the abhesive effect. Methods are also known in which a surface application takes place during paper production with the aim of significantly improving the water resistance, wet strength or hydrophobization of the paper web and / or reducing the tendency of silicone resins to penetrate during a later (separate) coating. Common silicone emulsions such as CMC, PCA and calcium stearates are added (SU 1320315 A1) or silicone emulsions of a defined composition (DE 2 326 828), possibly with the addition of additional film formers ("Paper" (1980), No. 11, pp. 36-37) used.
Before any further (separate) silicone coating, the raw paper pretreated in this way is partly satinized. The subject of these patents is always the achievement of more or less strong adhesive properties of the (on-line) coated base papers.

The object of the present invention is preferably to produce a release paper with modified surface properties within the paper machine, which has better adhesion and faster crosslinking at a lower temperature subsequent separate coatings with customary different silicone systems allowed.
This also enables faster crosslinking at a lower temperature than previously an increase in the previously usual coating speed. Another advantage is the easier use of stored silicone systems, the reactivity of which is already more or less impaired.

In addition, any damage to the paper due to too high or too long exposure to temperature, which leads to a loss in strength of the paper, should be prevented or reduced.

The release paper can be made machine-smooth or subjected to subsequent smoothing, for example in a supercalender, before it is siliconized in a separate coating system. Especially in the case of the latter-mentioned still satinized and thus particularly smooth release base papers, the ideal possibility should thus be opened to coat even surfaces of low micro-roughness in an economically advantageous manner with minimal silicone applications without flow problems and adhesion difficulties. Silicon savings through thinner coatings while securing the desired (usually low) release forces were previously only possible with the use of plastic films, which in turn had the disadvantage of a lower one have thermal resistance.
Another advantage of the desired surface modification of release paper should be the extensive suppression of the negative influence of inhibiting paper components (catalyst poisons) on silicone crosslinking.

This object is achieved according to the invention by the process measures and substances characterized in the claims.

According to the invention, the desired surface modification of release papers by means of silicone additives has a completely different chemical structure and properties than the above-mentioned aqueous silicone systems (emulsions) to the usual impregnation or surface solution, which is applied in the paper machine to the almost dry paper web with a solid moisture content of 2 to 12% with conventional application devices be applied. Roller and doctor blade applicators or dip impregnation devices are known as customary application devices for the surface finishing of release paper.

The silicone additives are silicone compounds from the two main groups
A organosilanes and
B organo polysiloxanes
represents.

The main group B organopolysiloxanes have at least 3 silicon-bonded hydrogen atoms per molecule and are, for example, copolymers of:
Dimethylhydrogensiloxane, methylhydrogensiloxane, dimethylsiloxane and trimethylsiloxane units, copolymers of trimethylsiloxane units, methylhydrogensiloxane units and hydrogensiloxan-, copolymers of trimethylsiloxane, dimethylsiloxane and Methyhydrogensiloxaneinheiten, copolymers of Methyhydrogensiloxan- and trimethylsiloxane units, copolymers of methylhydrogensiloxane, diphenylsiloxane and trimethylsiloxane units, copolymers of methylhydrogensiloxane -, dimethylhydrosiloxane and diphenylsiloxane units, copolymers of methylhydrogensiloxane, phenylmethylsiloxane, trimethylsiloxane and / or dimethylhydrogensiloxane units, copolymers of methylhydrogen units, copolymers of methylhydrogensiloxane, dimethylsiloxane and dimethylsiloxane, Phenylhydrosiloxane, demethylsiloxane and / or phenylmethylsiloxane units.

However, all of the organopolysiloxanes are preferably not removed by hydrogen and siloxane oxygen atoms saturated silicon valences saturated by methyl residues. Processes for the preparation of organopolysiloxanes of this type are generally known.

The organopolysiloxanes used for the purposes of the invention are emulsified in water. All known procedures and dispersants for the emulsification of organopolysiloxanes in water can be used.

The organ silanes assigned to main group A, which are also used according to the invention, include both organofunctional alkoxysilanes and alkyl alkoxysilanes. Examples of organofunctional silanes include:
3-glycidyloxypropyl-trimethoxyxilane, N-aminoethyl-3-aminopropyl-trimethoxysilane, 3-aminopropyl-triethoxysilane, 3-aminopropyl-methyldiethoxysilane, 3-aminopropyl-trimethoxysilane, 3-amino-propyl-tris (2-methoxy) ethoxy silane, 3-methacryloxypropyl-trimethoxysilane, 3-mercaptopropyl-triethoxylsilane, 3-mercaptopropyl-trimethoxysilane, 3 mercaptopropylmethyl-dimethoxysilane, 3-chloropropyl-triethoxsilane, 3-chloropropyl-dimethyl-3-chloropropyl-methyl-3-chloropropyl-methoxysilane Vinyltriethoxysilane-viniyltrimetoxysilane and vinylmethyldimethoxysilane.
The following compounds are designated as typical representatives of the alkysilanes:
Methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, propylmethyldimethoxysilane, propylmethyldiethoxysilane, iso-butyltrimethoxysilane and butyltrimethoxysilane.
It is known that organosilanes have the ability to react with an inorganic substrate as well as with organic polymers to form solid bonds. This is due to the structure of the silane molecule, which has alkoxy groups that can react with the active sites of the inorganic material after hydrolysis. In addition, silanes have a functional group that is firmly attached to the silicon atom via a carbon chain. This group can undergo chemical reactions with suitable resins.

The silicone compounds mentioned can be used alone or in combination with conventional impregnation or surface glue compositions for release base papers, which mostly differ from the film formers alginate, starch, CMC, PVA or other polymer solutions and polymer dispersions (latexes) Licher chemical structure exist, are added proportionately.

The silicone compounds are only added in proportions of up to 15% (calculated) of the usual surface preparation in order to avoid any undesirable side effects, e.g. adhesive properties to give the paper. In addition, these silicone additives represent an additional cost factor.

The following examples are intended to explain the invention. In the following examples, all percentages and parts are based on weight (calculated).

example 1 Production of the coating material for surface modification

a. 50 g of a fully saponified polyvinyl alcohol product were placed in a glass container with 500 g of water. The pH of the suspension was adjusted to 4.0 with sulfuric acid, after which the mixture was warmed to 90 ° C. in a water bath. The cooking time of the polyvinyl alcohol (PVA) suspension was 20 minutes, the PVA granules completely dissolving in the water. After the cooking process 5 g of 3-aminopropyl-triethoxysilane were stirred into the PVA solution with the aid of a stirrer, after which the mixture was left to stand at 60 ° C. for one hour. If necessary, the pH was corrected to 4.0 with sulfuric acid after the silane addition. The mixture prepared in this way was later applied with a laboratory size press to unsatinized release paper (silicone base paper) with a weight per unit area of 66 g / m². The application weight was around 1.5 g / m². Before the application, the surface preparation was diluted with water to a solids content of 5%. The untreated raw paper had an air permeability according to Schopper of 62 cm³ / min and a degree of sizing according to Cobb-Unger of 50 g / m².

After drying and rewetting, the paper coated with it was satinized in a two-roll laboratory calender. The line pressure was 4000 dN / cm. The steel roller had a surface temperature of 100 ° C.

b. The paper thus obtained was siliconized in a laboratory process. The siliconization was carried out using a KCC 302 doctor blade applicator, which was ver various wire-wrapped metal rods applies the respective silicone to the paper sheets at a constant speed.

Die Silikonauftragsmenge betrug etwa 1 g/m² (fest ge­rechnet).A conventional solvent-free polysiloxane system with the following composition was used for the silicone coating.

The amount of silicone applied was about 1 g / m² (calculated).

To crosslink the applied silicone layer, the coated paper was placed on a metal sieve in a forced air oven operated at 150 ° C.

The crosslinking time was set differently in order to follow the influence of the silanes on the crosslinking and anchoring process. In Table 1 below only the shortest crosslinking times are recorded, during which a complete hardening and anchoring of the silicone layer is still guaranteed. The paper samples hardened at different times were immediately subjected to a scratch test, with the finger being rubbed 8-10 times over the silicone film. The pressure is selected so that the fingertip heats up significantly when rubbed. A disturbance in the silicone coating shows itself in the form of rubbed-off beads ("rub off") and as a matt area ("smear") if you look at the paper sheet under the slant.

As a reference paper (blank), i.e. a paper without silane additive, a paper was used which had also gone through the treatment stages described above, but contained no addition of the organosilanes mentioned in part a) in the PVA.

Example 2

The procedure of Example 1 was repeated with one exception, only the pH of the PVA mixture was adjusted to 9.5 with ammonia. The minimum crosslinking time for this paper is shown in Table 1.

Example 3

The procedure of Example 1 was repeated, but instead of 5 g of 3-aminopropyl, triethoxysilane in the PVA solution, 5 g of N-aminoethyl-3-aminopropyl trimethoxysilane were added. The shortest crosslinking time for a paper coated in this way is shown in Table 1 below.

Example 4

The procedure of Example 3 was repeated, only the pH of the PVA mixture was raised to 9.5 this time with ammonia. The result of the cross-linking test is shown in Table 1.

Example 5

The procedure of Example 1 was repeated. Instead of 5 g of 3-aminopropyl-triethoxysilane to the PVA solution, 5 g of a mixture of vinyl triacetoxysilane and triemethoxyepoxy-functional silane were added. The shortest crosslinking time for paper provided with such a line can be seen from Table 1.

Example 6

The procedure of Example 5 was repeated, but the pH of the PVA mixture was raised to 9.5 with ammonia. The result of the cross-linking test is recorded in the table below. Table 1 example Amount related to PVA PH value shortest crosslinking time in s, at which a complete hardening is given 1 10% 4.0 13 2nd 10% 9.5 5 3rd 10% 4.0 4th 4th 10% 9.5 4th 5 10% 4.0 5 6 10% 9.5 18th Zero sample 1 4.0 20th Zero sample 2 9.5 20th By adding the organosilanes listed according to the invention to modify the paper surface, the crosslinking time for the subsequent silicone coating was reduced by 10 to 80% compared to the blank samples (without the addition of silicone).

Example 7

Surface-sized raw paper with silane additives was produced on a paper machine. The paper machine had a width of approx. 2.20 m and reached a speed of approx. 410 m / min during the test. The silane-containing surface application was applied to the web in a size press, a two-roll applicator. The paper consisted of 50% each of fully bleached long fiber pulp and short fiber pulp. No fillers were added. The basis weight of the paper produced in this way was 67 g / m. 3-Aminopropyl-triethoxysilane was used as the organosilane component. This had an active ingredient content of 40%. The surface preparation, which was applied to the base paper in the size press of the paper machine, had the following composition: 100 Parts PVA 10th Parts CMC 28 Parts of aminosilane (HW), commercially available. The pH of this mixture was raised to 9.7 with ammonia. This paper finished in this way was additionally satinized in a 16-roll supercalender at a pressure of 330 kN / m and a speed of 300 m / min.

Example 8

The test was repeated according to the manufacturing process described in Example 7, but with a different surface formulation. In this case, organosilane was used. The line recipe used here had the following composition: 100 Parts PVA 10th Parts CMC 11 Parts of silane mixture according to Ex. 5 The pH of this mixture was adjusted to 4.0 with sulfuric acid.

Example 9

The papers produced according to Examples 7 and 8 were siliconized with a width of 1 m on a coating machine of the type Revo 303 A from the Maschinenfabrik Kroenert / Hamburg. This computer system is designed for a maximum speed of 200 m / min. The two surface-refined test papers were made together with a paper product which also corresponds to that in Examples 7 and 8 described method had been produced, but contained no organosilane in the line (zero sample), coated with a silicone system based on solvents having the following composition: 80 Parts white spirit 15 Parts Si-adhesive 930 0.5 Parts of crosslinker V 93 0.05 Parts of catalyst OL The solids content of this coating composition was 5% and the viscosity according to Ford-Becher was 12 s. The silicone was applied to the paper web by means of an anilox roller (40 screen per cm). The air temperature in the float dryer was set to 190 ° C.

The degree of curing was determined immediately after the siliconization directly on the coated rolls using the finger abrasion test described in Example 1 and with the aid of Tesa 104 adhesive tape. In this series of tests, the web speed was varied, while the drying temperature remained constant at 190 ° C.

The results of these tests are summarized in Table 2: Table 2 Paper type Silicon application g / m Max. Speed m / min Separation force, mN / cm after 20 h after 4 weeks K-7476 A-8475 K-7476 A-7475 Blank test 0.4 150 303 74 210 103 Paper from example 7 0.4 163 308 69 244 72 Paper from example 8 0.4 165 281 63 197 60 The coating speed could be approx. 10% at approximately the same level of separation forces after siliconization.

The separation forces were measured according to FINAT test method No.10 (FTM 10). A rubber adhesive tape K-7476 and an acrylic adhesive tape A-7475 were used as adhesive tapes. The measurements were carried out in a tensile tester by peeling off the adhesive tape from the silicone-coated test paper at an angle of 180 ° and a clamp speed of 300 mm / min. The silicon application amounts were determined by means of X-ray fluorescence measurements.

Example 10

The test papers produced according to Examples 7 and 8 were also coated on the coating system mentioned above with silicone systems on a solvent-free basis. A four-roll application unit was used for this. Since the maximum speed of the system of 200 m / min was already reached with the reference paper (zero sample), this series of tests looked instead for the minimum temperature for a complete hardening of the silicone coating at a constant maximum speed of 200 m / min.

The following silicone system was used for the paper coating: 100 Parts of Wacker Si-Dehäsiv 920 2.5 Parts crosslinker VP 1524 1.0 Parts of catalyst OL The results of this series of tests are shown in Table 3. Table 3 Paper type Silicon application g / m Minimum temp. ° C for curing Separation force, mN / cm after 20 h after 4 weeks K-7476 A-7475 K-7476 A-7475 Blank test 1.4 150 196 38 164 35 Example 7 paper 1.5 145 205 35 187 36 Example 8 paper 1.5 138 193 32 174 33 With a comparable release force level, the minimum temperature for curing the silicone coatings could be reduced by approx. 5 to 10%.

The silicone application quantities and release force values were determined as in Example 9.

Example 11

The procedure of Example 10 was repeated. Another system, also on a solvent-free basis, was used for the silicone coating. The coating composition had the following composition: 100 Parts of Silcolease 8000 (ICI) base polymer silicone from ICI 2nd Parts Silicone Crosslinker 95 A 2nd Parts Silicone Crosslinker 96 A 4th Parts Catalyst 95 B.

The siliconization of the three test papers was carried out at a speed of 200 m / min, the minimum temperature in the convection drying again being sought for a complete hardening of the silicone films. The results are shown in Table 4. Table 4 Paper type Silicon application g / m Minimum temp. ° C for curing Separation force, mN / cm after 20 h after 4 weeks K-7476 A-7475 K-7476 A-7475 Blank test 1.4 150 192 34 174 43 Example 7 paper 1.5 135 189 37 170 39 Example 8 paper 1.6 140 192 47 168 45 At a comparable level of release force, the minimum temperature for curing the silicone coatings could be reduced by about 5 to 10%.

The release force values and the silicone application quantities were determined as in Example 9.

Example 12

The procedure of Examples 10 and 11 was repeated. The following coating system was used for the solvent-free siliconization: 100 Parts base polymer silicone Rhodorsil 11347 from Rhone-Poulanc 3rd Parts of catalyst 11091 for the base polymer. The test papers were coated at a speed of 200 m / min. The lowest curing temperatures were again determined, as can be seen from Table 5. The separation force values and the silicone application quantities were determined in accordance with Example 9. Table 5 Paper type Silicon application g / m Minimum temp. ° C for curing Separation force, mN / cm after 20 h after 4 weeks K-7476 A-7475 K-7476 A-7475 Zero sample 2.0 150 152 225 140 246 Example 7 paper 2.0 135 151 297 143 239 Example 8 paper 2.1 135 144 253 160 213 As Examples 1 to 12 showed, the addition of various organosilanes according to the invention in proportions of approx. 10 - 15% (calculated) of the usual surface preparations for release paper an improvement in the adhesion and an acceleration of the crosslinking time for subsequent coatings of solvent-containing or solvent-free addition-crosslinking silicone systems. If the silicone film is adequately anchored on the paper surface, measurable increases in the coating speed and / or reductions in the minimum temperature for the silicone curing can be observed. The base paper does not have any inhibiting effects. The level of release force of the silicone coatings was not or only slightly changed by the addition of organosilanes for the surface preparation of the release paper.

Similar effects were also found in a subsequent coating of release papers coated with such a surface with aqueous silicone systems.

Similar effects cannot be ruled out when using cold-curing silicone systems (UV or electron beam curing systems).

In contrast, no improvement in the adhesion and / or crosslinking of silicone films is to be expected in the case of condensation-crosslinking silicone systems (thermal crosslinking).

B organ polysiloxanes (having at least 3 silicon-bonded hydrogen atoms per molecule) Example 13

3.5 g of at least 3 Si-bonded hydrogen atoms were added to a mixture of 22 g of polyvinyl alcohol and 3 carboxymethyl cellulose in 475 g of water, which had been treated by the methods described in Example 1 for the preparation and cooking of the abovementioned polymers, with stirring per molecule of organ polysiloxane in the form of an emulsion (solids content: 35%). The pH of this mixture was adjusted to 4.0 with sulfuric acid. The person produced in this way was applied with a laboratory size press to unsatinated silicone base paper with a basis weight of 66 g / m.

The application weight was around 1.5 g / m (calculated). The uncoated base paper had an air permeability according to Schopper of 62 cm / min and a degree of sizing according to Cobb-Unger of 50 g / m.

After drying and rewetting, the paper treated with it was satinized in a laboratory calender. The line pressure was 4000 dN. The surface temperature of the steel roller was 100 ° C.

The further processing of the test paper was carried out as described in part b) of Example 1. The results of the cross-linking test are summarized in Table 6.

Example 14

The procedure of Example 13 was repeated. After adding the organoprobysiloxane emulsion, the pH was 5.5. The results of the crosslinking test are shown in Table 6 below.

Example 15

The procedure of Example 13 was repeated, but instead of coating the test paper with the solvent-free silicone system described in part b) of Example 1, a solvent-containing system with the following composition was chosen: 74 Parts white spirit 20th Parts of Silcolease 7420 (ICI) base siloxane 0.2 Share Crosslinking Agent 91 A crosslinker 0.8 Share Catalist 90 B The siliconization was carried out analogously to Example 1, part b) a laboratory doctor device, the silicon application again being about 1 g / m (calculated). The shortest networking times determined are shown in Table 5.

Example 16

The procedure of Example 14 was repeated. However, the laboratory siliconization was carried out using the solvent-containing silicone system described in Example 15. The minimum required networking times are shown in Table 6.

Example 17

The procedure of Example 13 was repeated. However, instead of 3.5 this time, 7 g of the organoprobysiloxane emulsion were added to the solution of 22 g of polyvinyl alcohol and 3 g of carboxymethyl cellulose in 475 g of water, with stirring. The pH of this mixture was again adjusted to 4.0 with sulfuric acid. The further processing corresponded to the procedure described in Example 13. The results of the crosslinking test are summarized in Table 6.

Example 18

The procedure of Example 17 was repeated, the pH However, the value of the line mix was set to 5.5. The results of the crosslinking test are shown in Table 6.

Example 19

The procedure of Example 17 was repeated. However, the test paper was coated with a solvent-containing silicone system from ICI. The composition of this coating composition has already been described in Example 15. The results of the crosslinking test are shown in Table 6.

Example 20

The procedure of Example 18 was repeated. However, the laboratory siliconization was carried out using the solvent-containing silicone system described in Example 15. The required shortest networking times are shown in Table 6.

Examples 21-24

Paper samples were used as a comparison (zero sample), which had been surface-finished with a mixture consisting of 22 g of polyvinyl alcohol and 3 g of carbosymethyl cellulose in 475 g of water, but without any addition of organoprobysiloxane emulsion. The pH values of these surface preparations were adjusted to 4.0 as well as 5.5. The laboratory siliconization was carried out using the silicone systems described in part b) of Example 1 and in Example 15. The required minimum crosslinking time is shown in Table 6. Table 6 Test paper pH value of the surface preparation minimum required crosslinking time, s (150 ° C) 4.0 5.5 LF * LH * 1.Example 13 X 8th 2. Example 14 X 12 3.Example 15 X 15 4.Example 16 X 18th 5.Example 17 X 5 6.Example 18 X 8th 7.Example 19 X 15 8.Example 20 X 18th 9. Sample 1 as a comparison (Ex. 21-22) X 10th 20th 10.Null sample 2 as a comparison (Ex. 23-24) X 15 20th * LF = solvent-free silicone system) approx. LH = solvent-containing silicone system) 1 g / m (solid) silicone application.

Claims (7)

1. A method for the surface modification of release papers by applying a coating composition, characterized in that a suspension of film-forming substances is applied to the paper web, which up to 20% (calculated) silicone compounds from the two main groups
A) organosilanes and / or
B) Organopolysiloxanes
which have at least three silicon-bonded hydrogen atoms. 2.The method according to claim 2, characterized in that the coating composition is applied in the paper machine. 3.The method according to claim 1 + 2, characterized in that the organosilanes are both organofunctional alkoxysilanes, such as 3-glycidyloxypropyltrimethoxysilane, N-aminoethyl-3-aminopropyl-trimethoxysilane, 3-aminopropyl-triethoxysilane, 3-aminopropylmethyl-di -ethoxysilane, 3-aminopropyl-trimethoxysilane, 3-amino-propyl-tris (2-methoxy-ethoxy) silane, 3-methacryloxypropyl-trimethoxysilane, 3-mercaptopropyl-trie thoyxsilane, 3-mercaptopropyl-trimethoxysilane, 3-mercaptopropyl-methyl-dimethoxysilane, 3-chloropropyl-triethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyl-methyldimethoxysilane, α-chloromethyl-dimethyl-methoxysiloxysilane, such as methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, propyltrimethoxysilane, propylmethyldimethoxysilane, propylmethyldiethoxysilane, iso-butyltrimethoxysilane and butyltrimethoxysilane. 4. The method according to claim 1, characterized in that the organosiloxanes have at least 3 silicon-bonded hydrogen atoms per molecule and are copolymers
Dimethylhydrogensiloxane, methylhydrogensiloxane, dimethylsiloxane and trimethylsiloxane units, copolymers of trimethylsiloxane, dimethylhydrogensiloxane and methylhydrogensiloxane copolymers of trimethylsiloxane, dimethylsiloxane and methylhydrogensiloxane units, copolymers of methylhydrogensiloxane and trimethylsiloxane units, copolymers of methylhydrogensiloxane, diphenylsiloxane and trimethylsiloxane units, copolymers of methyl hydrogensiloxane, dimethylhydrogensiloxane and diphenylsiloxane units, copolymers of methylhydrogensiloxane, phenylmethylsiloxane, trimethylsiloxane and / or dimethylhydrogensiloxane units, copolymers of methylhydrogen siloxane, dimethylsiloxane and trimethylsiloxane and trimethylsiloxane and trimethylsiloxane Phenylmethylsiloxane units
acts, preferably all silicon valences not saturated by hydrogen and siloxane oxygen atoms are saturated by methyl radicals. 5.The method according to claim 1 to 4, characterized in that the silicone compounds in proportions of 1 to 25% (calculated), preferably in proportions of 3 to 15% surface preparations from film-forming substances for release papers such as polyvinyl alcohol, carboxymethyl cellulose, starch derivatives, alginate , or polymer dispersions (latices) alone or in combination and in a pH range from 2 to 11, preferably 4 to 9.5, are added. 6. The method according to claim 1 to 5, characterized in that the surface application by means of application units, based e.g. on the roller (e.g. size press) or squeegee (e.g. blade) principle, on an already formed paper web with a residual moisture content of between 1 and 14%, preferably 2 to 8%. 7. The method according to claim 1-6, characterized in that the surface coating additionally contains a white pigment, e.g. Calcium carbonate, kaolin, talc, titanium dioxide and the like.