Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D161/00—Coating compositions based on condensation polymers of aldehydes or ketones; Coating compositions based on derivatives of such polymers
  • C09D161/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/17—Amines; Quaternary ammonium compounds

Definitions

• latent curing catalysts The effect of the latent curing catalysts is based on the fact that they are ineffective at normal temperature and only release an acid in the heat or due to a chemical reaction, which accelerates the curing process.
• Typical such curing catalysts are e.g. B. ammonium salts.
• impregnation resin solutions for surface coating or the so-called resin liquors made from them are used to impregnate absorbent carrier materials, e.g. B. paper, nonwoven or fabric; after drying, the impregnated carrier materials can be processed into laminates by hot pressing or for surface coating of materials, e.g. B. chipboard or blockboard.
• the aminoplast resins are usually cured under pressure and heat.
• the curing catalysts have to meet a number of requirements which these normally do not always meet to the required extent at the same time.
• the minimum requirements for a modern, usable coating are that the finished material is resistant to acids and water vapor, has a non-porous surface and is therefore insensitive to dirt and remains crack-free under later temperature loads.
• the surface should appear calm and have the highest possible degree of gloss even when demoulded in the heat (without recooling).
• aqueous solutions of salts of sulfurous acid with primary, secondary or tertiary aliphatic or cycloaliphatic alkanolamines or morpholine have particularly favorable properties as latent hardeners for aminoplast resins.
• Preferred alkanolamines have 1 to 10 carbon atoms.
• aminoplast resins are to be understood as meaning both urea and meiamine formaldehyde resins.
• urea-formaldehyde condensates with one Mol ratio (F: H) of 1.4: 1 to 1.7: 1 or melamine-formaldehyde condensates with a molar ratio (F: M) of 1.5: 1 to 2: 1, which are condensed to or almost to the point of incompatibility with water.
• F: H Mol ratio
• F: M molar ratio
• Etherified or partially etherified (fully water-soluble) condensates and the use of non-aqueous solvents are also common.
• Urea resins are common for soaking so-called primer films to make wood-based materials paintable.
• Urea resins preferably melamine-formaldehyde condensation products, are used for coating wood-based materials with resin-impregnated papers in short pressing times.
• the hardeners known from DE-AS are not fundamentally more advantageous than already used hardeners, such as. B. Morpholine salts.
• Hardener based on salts of certain alkyl or. Alkanolamines also suggest GB-PS 1 049 511, preferred hydrochloric acid and generally sulfonic acids, sulfuric acid and a number of carboxylic acids being given as acid partners.
• GB-PS 937 606 contains the teaching of addition products from u. a. Sulfur dioxide on amines, which are produced in an anhydrous reaction, to be used as hardeners for urea resins.
• these addition products are not to be regarded as salts and are generally insoluble in aqueous solution at room temperature (cf. Example 1 of GB-PS); it was also found that aminoplast solutions to which such adducts are added are not stable; this applies in particular to the adducts with the alkanolamines which are used according to the invention. It can be concluded from this finding that the adducts according to GB-PS do not, in any case under normal conditions, pass into the corresponding salts in an aqueous environment.
• alkanolamines are N-methylethanolamine, N, N-dimethylethanolamine, mono-, di- and triethanolamine, as well as morpholine and 4- (2-hydroxyethyl) morpholine, which, because of their similar structure and low basicity, are to be regarded as equivalents of alkanolamines , used alone or in a mixture for the preparation of sulfuric acid ammonium salts.
• the hardeners according to the invention are the resins or their solutions in conventional amounts, eg. B. 0.1 to 20 weight percent, based on the solids content of the resin solutions, added. This can happen more or less shortly before processing; in general, the solutions are stable for at least a few hours, usually several days. Depending on the desired degree of gloss, the hardener dosage can be adapted to the pressing time, with improved use properties of the finished material being obtained compared to the usual hardeners.
• the products made with the solutions, not yet cured, e.g. B. pre-dried, resin-soaked papers are generally stable for several weeks or months.
• the ratio of sulphurous acid to alkanolamine or amine mixture in the preparations according to the invention is therefore generally between 0.5: 1 and 1: 1.
• the free amine should be present in at least an excess of 5 mole percent, based on the salt. This excess should be up to 300 mole percent depending on the acid partner and is described as essential in order to obtain processable impregnating solutions with a service life of at best 16 hours.
• the hardeners to be used according to the invention are notable for the fact that - even in amounts which are necessary for a short-cycle coating in particularly short pressing times - the usability of the resin liquor is maintained considerably longer than with conventional hardeners, such as pure acids or mineral acid amine salts or Amine salts of strong aliphatic or aromatic carboxylic acids is possible.
• the pressing time can be reduced to less than one minute in the so-called short-cycle method, whereby compared to the impregnating solutions set with conventional hardening agents, much more closed, better hardened, water-vapor-resistant and glossy surfaces are obtained. The surfaces remain completely free of cracks even after exposure to temperature.
• the solution of a melamine resin prepared in a conventional manner in a molar ratio of formaldehyde to melamine of 1.7: 1 with a dry content (2 h / 120 ° C.) of 55% and a water dilutability of 1: 1.3 is divided into samples and each with various hardeners in the form of their approx. 50% solutions set to a gel time (140 ° C in the pressure tube) of 60 to 70 seconds.
• a white, pigmented, absorbent fine cellulose paper with a basis weight of 110 g / m 2 is impregnated with this resin solution in such a way that the carrier web has a basis weight of 270 g / m 2 and a dry value of 6.4 to 7.0%.
• the pressing conditions for the parallel tests are a) 6 min / 145 ° C, b) 3 min / 170 ° C), c) 60 sec / 190 ° C with additional padding (the specified temperature is always the temperature of the press plates).
• a 0.2 N hydrochloric acid stained with rhodamine B is allowed to act on the surface for 15 hours. Acid attack and dye uptake are assessed on a scale from 0 to 6, whereby «no recognizable attack receives the value 0.
• the surface to be tested is treated with black shoe polish and rubbed off again with a clean cloth.
• a value scale from 0 to 6 is used to assess whether the dye can be removed completely (O) or remains more or less in open pores (> 0).
• the chipboard coated with the double-layered film for 6 minutes at 170 ° C. is stored for 16 hours at 100 ° C.
• the surface is then assessed for cracks (scale 0 to 6). (See table 1 page 5 f.)
• Example 1 As described in Example 1, a melamine resin was adjusted to a cloud time at 100 ° C. (in a test tube) of about 270 seconds using known and a hardener according to the invention. The impregnation was carried out as described in Example 1.
• the pressing conditions were: a) 30 s, b) 40 and c) 50 at 190 ° C with an additional cushion.
• Example 1 In order to underline the high effectiveness of the hardeners according to the invention, the resin solution described in Example 1 was adjusted to an even higher reactivity (clouding time at 100 ° C. in a test tube 270 seconds).

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Phenolic Resins Or Amino Resins (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Laminated Bodies (AREA)

Applications Claiming Priority (2)

Publications (3)

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• 1977
  • 1977-08-12 DE DE19772736404 patent/DE2736404A1/de not_active Withdrawn
• 1978
  • 1978-07-21 IT IT25980/78A patent/IT1099017B/it active
  • 1978-08-07 DE DE7878100610T patent/DE2861230D1/de not_active Expired
  • 1978-08-07 EP EP78100610A patent/EP0000780B2/de not_active Expired
  • 1978-08-11 ZA ZA00784570A patent/ZA784570B/xx unknown
  • 1978-08-11 AT AT0585778A patent/AT376987B/de not_active IP Right Cessation

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