Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/80—Paper comprising more than one coating
  • D21H19/82—Paper comprising more than one coating superposed
  • D21H19/824—Paper comprising more than one coating superposed two superposed coatings, both being non-pigmented
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/001—Release paper

Definitions

• the invention relates to a process for the production of release paper, in which the paper is coated with a suspension of film-forming substances before the application of a silicone coating.
• Release papers can also be coated with pigment-binder combinations with the application devices already mentioned.
• pigment-binder combinations mainly latices are used as binders and white pigments such as kaolin and / or calcium carbonate (see “Coating” (1987), No. 10, pp. 366-372 and (1987), No. 11, pp. 396 - 398).
• aqueous silicone systems emulsions
• PVA or CMC aqueous film formers and thickeners
• the silicone resin used always forms the main component, since it primarily influences the adhesive effect of the papers coated in this way with a special purpose (for example baking release papers, sack papers with hydrophobic properties, etc.).
• the aqueous silicone systems contain organopolysiloxanes, e.g. Polydimethylsiloxanes, to which catalysts, crosslinking agents (e.g. based on methylhydrogen siloxanes), optionally also adhesives (e.g. water-soluble reactive silane esters) and controlled release additives are added (see “Adhesion” (1973), No. 7).
• organopolysiloxanes e.g. Polydimethylsiloxanes
• crosslinking agents e.g. based on methylhydrogen siloxanes
• adhesives e.g. water-soluble reactive silane esters
• controlled release additives controlled release additives are added (see "Adhesion" (1973), No. 7).
• the manufacturers of these aqueous silicone systems predominantly already offer the base polymer with crosslinker or catalyst additive (crosslinker or catalyst emulsions).
• the further components are then added by the processor shortly before use (raw paper coating) in order to achieve the desired
• the object of the present invention is Release papers with special surface coatings, but without producing any additional abhesive effects, which enable better adhesion and faster crosslinking of subsequent, conventional, separate coatings with a wide variety of silicone resins.
• This object of producing release papers of the type described at the outset is achieved in that the suspension contains up to 25% (calculated) catalysts for crosslinking the silicone coating in the form of an aqueous emulsion.
• z. B As a catalyst or as a catalyst component for the aqueous emulsion, z. B. the following substances are used: Finely divided platinum, ruthenium, rhodium, palladium, iridium and compounds or complexes of these elements, in particular platinum halides such as PtCl4 platinum (IV) chloric acid and Na2PtCl n ⁇ 4H2O, platinum-olefin complexes, platinum-alcohol or platinum-alcoholate complexes, Platinum-ether complexes, platinum-aldehyde complexes, platinum-ketone complexes and platinum-vinyl-siloxane complexes; also iron, nickel and cobalt carbonyls.
• platinum halides such as PtCl4 platinum (IV) chloric acid and Na2PtCl n ⁇ 4H2O
• platinum-olefin complexes platinum-alcohol or platinum-alcoholate complexes
• 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 catalyst emulsions on the crosslinking and anchoring process.
• Table 1 only the shortest crosslinking times are recorded, during which complete hardening and anchoring (adhesion) of the silicone layer is still guaranteed.
• a paper As a reference paper (blank), i.e. a paper without the addition of catalysts, a paper was used which had also gone through the treatment steps described above, but contained no further additives in the PVA / CMC solution.
• Example 1 The procedure of Example 1 was repeated. After the catalyst emulsion had been added, however, the pH was raised to 9.0 using ammonia. The results of the crosslinking tests are shown in Table 1 below.
• Example 1 The procedure of Example 1 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 20 parts of base polymer silicone 0.2 parts crosslinker 0.8 parts catalyst The siliconization was carried out analogously to Example 1, part b) using a laboratory doctor device, the silicon application again being approximately 1 g / m 2 (calculated). The shortest networking times determined are shown in Table 1.
• Example 2 The procedure of Example 2 was repeated. However, the laboratory siliconization was carried out using the solvent-containing silicone systems described in Example 3. The minimum required networking times are shown in Table 1.
• Example 1 The procedure of Example 1 was repeated. However, instead of 3 g, this time 6 g of catalyst emulsion was added to the solution of 22 g of polyvinyl alcohol and 3 g of carboxymethyl cellulose in 475 g of water. The pH of this mixture was again adjusted to 4.0 with sulfuric acid. The further processing corresponded to the procedure described in Example 1. The results of the crosslinking test are summarized in Table 1.
• Example 5 The procedure of Example 5 was repeated, but the pH of the coating mixture was raised to 9.0 with ammonia. The results of the crosslinking test are shown in Table 1.
• Example 5 The procedure of Example 5 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 3. The results of the crosslinking test are shown in Table 1.
• Example 6 The procedure of Example 6 was repeated. However, laboratory siliconization was carried out using the solvent-containing silicone system described in Example 3. The shortest networking times required can be found in Table 1.

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• Paints Or Removers (AREA)
• Catalysts (AREA)

Priority Applications (6)

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Publications (2)

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• 1989
  • 1989-05-09 AT AT89108274T patent/ATE84087T1/de not_active IP Right Cessation
  • 1989-05-09 EP EP89108274A patent/EP0396789B1/de not_active Expired - Lifetime
  • 1989-05-09 DE DE8989108274T patent/DE58903181D1/de not_active Expired - Fee Related
  • 1989-05-09 ES ES198989108274T patent/ES2036746T3/es not_active Expired - Lifetime
• 1993
  • 1993-02-17 GR GR920300096T patent/GR920300096T1/el unknown
  • 1993-03-24 GR GR930400643T patent/GR3007456T3/el unknown

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