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
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/18—Paper- or board-based structures for surface covering
  • D21H27/22—Structures being applied on the surface by special manufacturing processes, e.g. in presses
  • D21H27/26—Structures being applied on the surface by special manufacturing processes, e.g. in presses characterised by the overlay sheet or the top layers of the structures
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
  • D21H17/70—Inorganic compounds forming new compounds in situ, e.g. within the pulp or paper, by chemical reaction with other substances added separately
• • 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
  • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
  • D21H25/04—Physical treatment, e.g. heating, irradiating
  • D21H25/06—Physical treatment, e.g. heating, irradiating of impregnated or coated paper

Definitions

• the invention relates to prepregs, a process for their preparation and decorative coating materials obtainable therefrom.
• Decorative films based on prepregs are already more or less deeply soaked within the paper machine, immediately after sheet formation and drying, with a resin mixture, depending on the basis weight of the base paper. After drying and smoothing, usually also within the paper machine, the paper or the film must be crosslinked and thus be gap-resistant, so that during the subsequent processing steps of the finish coating and lamination on corresponding carrier no fiber separation occurs within the decorative film.
• the prepregs for further processing high coverage and surface quality, good printability in rotogravure, good paintability (high paint level), good flatness and bondability with chip and MDF boards (medium-density fiberboard) required.
• the thermally crosslinkable impregnating resins commonly used for the preparation of prepregs are water-dilutable, formaldehyde-containing resin solutions based on urea, melamine or phenolic resins. Since their sole use leads to relatively brittle products, these resin solutions are generally used in combination with water-dilutable, thermally crosslinkable polymer dispersions based on acrylic acid, acrylic acid ester, styrene, butadiene, vinyl acetate or acrylonitrile.
• the resin absorption can be between 5 and 35% by weight, with the proportion of resin solutions generally penetrating deeper into the base paper than the proportion of polymer dispersions. The latter accumulate more or less on the top and bottom of the paper and ensure good smoothability and thus printability and surface impermeability and thus paintability (paint level) of the papers.
• the resin solutions are intended to ensure the good gap strength and flatness of the prepreg by crosslinking the fiber-resin composite during further processing.
• thermosetting, formaldehyde-free resin solution By using a thermosetting, formaldehyde-free resin solution, the first at a heat treatment of the pre-impregnate over a period of about 40 seconds at about 132 ° C according to DE 101 34 302 C1 largely crosslinked (degree of crosslinking of at most 85%), these disadvantages are avoided.
• the resin solution used for this purpose, its production and possible uses, inter alia for the impregnation of papers for decorative applications, are in the DE 197 35 959 A1 described.
• the disadvantage is that such until the H adoptedverpressung on the carrier material (eg chipboard) as the last further processing step completely uncrosslinked pre-impregnate according to the DE 101 34 302 C2 until then has no better or even worse internal strengths than known formaldehyde-free or -contaminated prepregs.
• the carrier material eg chipboard
• it has up to the hot pressing a poorer surface impermeability and thus poorer paint (lower paint level) and a poorer flatness during the lamination (bonding) than previously known formaldehyde-free and -containing pre-impregnate.
• the invention is therefore based on the object to provide partially crosslinked prepregs that already largely avoid the disadvantages mentioned at the end of the paper machine and as far as possible by high surface quality, good printability and higher splitting strength than known formaldehyde-free or prepregs, good paintability (high paint level) , good flatness and bondability with conventional adhesives in the Distinguish subsequent processing steps and thus are almost equivalent in off-line impregnated papers in their properties.
• the prepreg according to the invention is obtainable by impregnating a base paper with an impregnating combination which contains a thermally curable, formaldehyde-free resin solution and a thermally crosslinkable polymer dispersion.
• the impregnated base paper is dried and smoothed. The smoothing is expediently carried out within the paper machine used to produce the prepreg.
• the degree of crosslinking of the prepreg is at least 10% and at most 85%.
• the impregnated base paper has a residual moisture of 2 to 3 wt .-%.
• the invention also provides a process for producing thermally partially crosslinked, formaldehyde-free prepregs within the paper machine and their use as decorative coating materials.
• the proportion of the impregnating components is from 5 to 35% by weight, preferably from 10 to 30% by weight, based on the weight of the raw paper.
• a resin for impregnating the base paper, a resin can be used which contains the aforementioned components B) and C), but not the component A).
• Such resins are in the DE 197 35 959 A1 disclosed.
• the inventive water-dilutable impregnating mixture of the above-mentioned formaldehyde-free resin solutions A) + B) + C) or B) + C) and usually used polymer dispersions is applied to at least one side of the paper web, then dried to a residual moisture content of 2 to 3% by weight and then smoothed.
• the impregnated base paper is thereby partially crosslinked, the degree of crosslinking depending on the mixing ratio of the impregnating combination between at least 10% and max. 85%.
• this is only partially crosslinked prepreg sufficiently flexible. It is particularly advantageous for the quality of the prepreg if the residual moisture is already set in the paper machine ("on-line"). Under a paper machine is understood in accordance with the general use of the word, the plant for papermaking, starting from the screening of the pulp suspension to the rolling up of the base paper.
• the mixing ratio between formaldehyde-free resin solution (I) and polymer dispersion (II) may be 49:51 to 10:90 (solid: solid), preferably 45:55 to 20:80. Mixture ratios of 35:65 to 30:70 are particularly preferred, since prepregs which have been produced with impregnation combinations having these mixing ratios are particularly easy to print and are sufficiently flexible.
• the concentration of the impregnating mixture according to the invention, which contains further additives if required, can be up to 50% by weight.
• the impregnating combination according to the invention can be applied online to the paper web in an amount of between 5 and 35% by weight, preferably between 10 and 30% by weight, based on the basis weight of the base paper.
• application devices all commonly used within the paper machine units can be used, preferably roller application devices, such as size press or film press.
• the raw papers to be impregnated according to the invention are those which are described, inter alia, in the patents EP 0223 922 A1 .
• EP 0870 872 A1 and DE 101 34 302 A1 are described.
• the impregnation, drying and smoothing methods used in the documents cited and in the trade journal " Kliblatt für Textilfabrikation "No. 6 (2000), pp. 350 to 355 described in detail and known prior art.
• a raw paper of 20% pine sulfate pulp and 80% eucalyptus pulp was produced.
• the freeness was 30 ° SR (Schopper-Riegler).
• 25% titanium dioxide and 4% formaldehyde-free wet strength agent were used on atro pulp.
• This raw paper without engine sizing and with a basis weight of 48 g / m 2 was impregnated on both sides in a laboratory size press with a formaldehyde-free resin solution of about 30% solids content of modified polyacrylic acid and a polyhydric alcohol (Acrodur 950 L Fa. BASF) and then at dried at different temperatures within about 18 seconds to a residual moisture content of about 2%.
• the amount applied after drying was 10 g / m 2 .
• Table 1 shows the degrees of crosslinking of the prepregs dried at different temperatures. This is followed by partial cross-linking of the prepregs up to about 30%, with drying conditions customary in the paper machine (up to 110 ° C., drying time about 300 seconds).
• the order amount was about 12 g / m 2 .
• the degree of crosslinking of the prepreg according to the invention was about 70%.
• the addition of polymer dispersion to the resin solution significantly increases the degree of crosslinking.
• the degree of crosslinking of the classical prepreg was 76% (A) or 84% (B) and is thus significantly higher than that of prepregs according to the invention with proportions of formaldehyde-free resin solutions according to Examples 1 and 2

Landscapes

• Reinforced Plastic Materials (AREA)
• Paper (AREA)
• Glass Compositions (AREA)
• Laminated Bodies (AREA)

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Citations (4)

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• 2003
  • 2003-02-24 DE DE10307966A patent/DE10307966C5/de not_active Expired - Fee Related
• 2004
  • 2004-02-13 EP EP04710840.2A patent/EP1518024B2/fr not_active Expired - Lifetime
  • 2004-02-13 AT AT04710840T patent/ATE338167T1/de not_active IP Right Cessation
  • 2004-02-13 WO PCT/EP2004/001393 patent/WO2004074577A1/fr active IP Right Grant
  • 2004-02-13 CA CA2518942A patent/CA2518942C/fr not_active Expired - Fee Related
  • 2004-02-13 EP EP06119238A patent/EP1757731A3/fr not_active Withdrawn
  • 2004-02-13 BR BRPI0407760-1A patent/BRPI0407760B1/pt not_active IP Right Cessation
  • 2004-02-13 DE DE502004001322T patent/DE502004001322D1/de not_active Expired - Lifetime
  • 2004-02-13 ES ES04710840T patent/ES2271845T5/es not_active Expired - Lifetime

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