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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• • 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
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/47—Condensation polymers of aldehydes or ketones
  • D21H17/48—Condensation polymers of aldehydes or ketones with phenols
• • 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
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/47—Condensation polymers of aldehydes or ketones
  • D21H17/49—Condensation polymers of aldehydes or ketones with compounds containing hydrogen bound to nitrogen
  • D21H17/51—Triazines, e.g. melamine
• • 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
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/18—Reinforcing agents
• • 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
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/34—Ignifugeants

Definitions

• the invention relates to resinous papers, their use as resinous preform blanks and to a method of manufacturing resinous papers.
• HPL high-pressure laminating methods
• CPL continuous laminating methods
• Impregnated raw papers are generally used today, which are impregnated with a thermosetting synthetic resin, such as a phenolic resin. Impregnating is carried out by subsequent immersing or coating of the raw paper with a liquid, aqueous or solvent-containing synthetic resin solution. The impregnated or coated paper is dried to a residual volatile content of about 6% to 9%. The surface of the paper is thus no longer sticky, it can therefore be manipulated and stored. At the same time a certain reactivity of the synthetic resin remains, which enables pressing of the resin-coated paper onto the material. So-called core papers are manufactured having a phenolic resin content of 30 to 70 weight % of the solids content of the finished resinous paper. These core papers are then cut to format for the HPL process and stored. For the CPL process, the core papers are processed from a roll.
• Core papers known in the art can only be produced within a certain limited spectrum.
• the weight of the raw paper cannot be varied at will, and a certain raw paper can only be coated with a limited amount of synthetic resin.
• the upper weight limit of impregnated core papers is about 350 g/m 2 . If a material is to be provided with a particularly resistive coating, a plurality of core papers must be superimposed in such cases and pressed onto the material. This is disadvantageous because multi-layered products can only be pressed with difficulty.
• the inventive method comprises the established steps of: preparing an aqueous fiber suspension having a consistency between 0.5 - 8 %, - preparing an aqueous dispersion of a thermosetting resin mixing the aqueous dispersion of the thermosetting resin into the aqueous fiber suspension, preparing an aqueous dispersion of an agent for fixing the thermosetting resin on the fibers of the fiber suspension, - mixing the aqueous dispersion of the fixing agent into the aqueous fiber suspension, adjusting a pH value of the aqueous fiber suspension to below 5, transferring the aqueous fiber suspension to a paper machine, dewatering the fiber suspension for the formation of paper, - drying the paper to a volatile content of 5% to 10%.
• an aqueous fiber suspension is prepared. Natural and/or synthetic fibers or mixtures of these can be used. In practice, usually cellulose fibers or recycled paper fibers or a mixture of these are used. Other natural fibers like hemp or cotton fibers can be used, too. Synthetic fibers, such as viscose or aramide fibers, are also used; however, this is rare due to cost considerations. It is mentioned explicitly that wet laid products e.g. preform blanks that are completely or partially made of synthetic fibers, are "papers" in the sense of this method.
• the fiber concentration of the suspension is mostly between 0.5 % and 8 %, preferably between 1 % and 5 %.
• An aqueous dispersion of a thermosetting resin e. g. a phenolic resin, a melamine resin or a formaldehyde resin or a mixture of thermosetting resins is mixed into the fiber suspension.
• the synthetic resin is not subsequently applied to the finished paper. It is intermixed intensively and homogeneously with the fibers prior to sheet formation.
• This significant feature of the inventive method, to mix the synthetic resin with the fibers prior to sheet formation can be realized technically particularly easily. No complex modifications to the equipment are necessary.
• properties of the core paper that can be adjusted by the respective type of resin can be modified within a wide range.
• thermosetting resins that can be processed in an aqueous dispersion preferably have one or more of the following properties: Alkalinity should be between 2 % and 5 %, advantageously between 2.5 % and 4.5 %. It is therefore lower than the alkalinity of phenolic resins, used for impregnation according to the art (alkalinity 6 % to 8 %). Viscosity should preferably be between 250 mPas and 1000 mPas.
• thermosetting resins that are used in the manufacturing of resinous papers according to the invention can have a viscosity from 600 mPas to 900 mPas. Therefore, thermosetting resins, e.g.
• thermosetting resins can be used in a significantly wider range of viscosity than before (hitherto: viscosity has varied from 250 mPas to 500 mPas).
• the free formaldehyde content of the thermosetting resin is up to 1.7 %, preferably up to 1.5 %, particularly preferably up to 1.0 %, especially up to 0.5 %, particularly advantageously up to 0.2 %. Therefore, thermosetting resins are used with a free formaldehyde content that is far lower than that of thermosetting resins used to date, which usually have a free formaldehyde content of approx. 2 %.
• Synthetic resins that are preferred according to the invention have an acetone extraction between 10 % and 20 %, preferably, the acetone extraction is between 10 % and 15 %. Resin flow is between 4 % and 12 %, preferably between 5 % and 8 %.
• the resin is present in the aqueous dispersion in a very finely dispersed form, so that it is uniformly mixed with the fibers.
• the fibers and the resin are first present together without there being a bond between the two components.
• the suspension is then adjusted in its acidity to a pH value below 5, preferably to a pH value between 3 and 4, for example by the addition of sulfuric acid.
• the pH value is adjusted by adding acids, e.g. by adding sulfuric acid, hydrochloric acid or organic acids. The lowering of the pH value leads to a precipitation of the phenolic resins. The precipitation of resins does not yet lead to a bond with the fibers.
• an agent for fixing the thermosetting resins is mixed into the suspension.
• the agent for fixing is known in the art. It is preferably added to the suspension before the pH value is lowered.
• the agent(s) for fixing is/are selected primarily with a view to fixing the thermosetting resins as completely as possible on the fiber surfaces so that as little resin as possible, in particular as little phenolic components as possible, remain in the waste water (current limit: 100 mg/l).
• the fibers of the suspension are at least partially coated or covered with synthetic resin. It is not necessary that the fibers are completely covered with synthetic resin. What is essential is that the amount of synthetic resin to be applied is precipitated on the surface of the fibers as completely as possible, so that the fibers and the synthetic resin are attached to each other prior to sheet formation.
• the thus processed fiber material can then be transferred via the conventional headbox to a paper machine, where the coated or resinous fibers are formed into sheets or paper by dewatehng (wet laying).
• a paper or a preform blank is formed in which at the crossing points between the fibers in at least some contact points, often in the majority of the contact points, fibers do not get into direct contact with each other. Rather, there is synthetic resin in between the fibers, since at least one of the intersecting fibers is coated with synthetic resin.
• the paper is then adjusted to a residual volatile content of below 10%, but above 5%, in the drier section of the paper machine. To obtain optimum reactivity of the resinous paper, mostly a paper volatile content of 6% to 8% is adjusted. The reactivity of the paper is a measure for the ability of the thermosetting resin to cure completely under pressure and heat.
• a further advantage is that the fibers and the synthetic resin are now more uniformly distributed; the core paper according to the present invention is more homogeneous overall.
• the synthetic resin is now firmly bonded to the fibers, which avoids "blocking" (accumulation of resin).
• a yet further advantage is that by using the resinous paper or the preform blank of the present invention the cycle time may be reduced by 15 - 25 %, preferably up to 30%.
• a still further advantage is that by using the resinous paper or the preform blank of the present invention there is no need for a backing paper to avoid sticking of the product, for instance in rolling, because resin will not flow out of the paper or preform blank as it does easily with impregnated paper
• the content of the thermosetting resin in the paper is 30 weigth % to 50 weight % of the solids content of the paper. Since the fiber content can be used in a substantially wider range of weights, as a result, despite the otherwise unchanged percentage by weight, the resin amount used can be varied more widely than with prior art core papers.
• the synthetic resin used can be dispersed in water, and is preferably water-soluble.
• the synthetic resin is typically provided with a solids content of 50% +/- 2% in an aqueous solution. It can be further diluted based on the delivered form, up to a ratio of resin to water of 1 :20.
• the inventive method is flexible regarding the solid content of the synthetic resin, since it is used for wet laying highly diluted anyhow. This diluted resin dispersion or resin solution is easily dosable and can be quickly and uniformly mixed with the fiber mass suspension, which is particularly advantageous in a continuous manufacturing process.
• agents are required for fixing the resin on the surface of the fibers. These agents act by means of charging the surfaces involved and therefore cause different charges on the surfaces, so that the resin is deposited and fixed on the oppositely charged fiber surface.
• cationically acting agents are used for fixing, but anionic, non-ionic and bi-ionic fixing agents are also well known and available.
• Typical examples of cationic fixing agents are high-molecular polyethylene imines or condensated organic amides with formaldehyde. Such agents for fixing can be used alone or in a mixture together with each other.
• fire-protection additives can be added to the fiber suspension prior to sheet formation. These additives can also be very uniformly distributed when they are added prior to sheet formation. This is important in particular with high sheet weights of the resinous paper, because the fire-retardant characteristics of the paper are particularly good if the fire-protection additives are uniformly distributed, so that there are no weak points.
• Another object of the invention is a resinous paper.
• the inventive paper is characterized in that the fibers and the thermosetting resin are related to each other in a different way than in known papers, especially core papers.
• the fibers of the inventive paper are at least partially coated with a thermosetting resin, e.g. phenolic resin, melamine resin or urea resin. Coating with the resin is carried out prior to sheet formation.
• the fibers thus coated with resin attach to each other during sheet formation in contact points in such a way that in at least some of the contact points resin-coated sections of the fiber surfaces rest against each other.
• resin-coated sections of the fiber surfaces rest against each other in the majority of the contact points.
• thermosetting resin (0026) It must be highlighted as a special advantage of the invention that both light and heavy papers can be produced from the fibers at least partially coated with thermosetting resin.
• the inventive papers can be manufactured in a wider weight range than papers known in the art.
• the amount of thermosetting resin applied to the fibers can be varied within a wide range, as has been depicted above by the example of the inventive process. It is possible to produce papers with a grammage up to 300 g/m 2 , as is possible with papers according to the art.
• inventive paper in particular with a grammage of more than 400 g/m 2 , preferably more than 500 g/m 2 , particularly preferably of more than 700 g/m 2 , advantageously of more than 900 g/m 2 , especially preferably of up to 1000 g/m 2 .
• the grammage of the inventive paper can basically be adjusted within a wide range; it is mainly limited by the amount of thermosetting resin applicable to the fibers and the workability during sheet formation as well as during pressing of the resinous paper.
• the fibers of the inventive paper can be natural fibers as well as synthetic fibers or mixtures of these. Fibers can be used for the inventive paper if they can be processed by wet laying and if thermosetting resin can be precipitated onto the surface of the fibers.
• thermosetting resin that can be applied to the resinous paper is up to 50 weight % based on the solid content of the paper. It can also be adjusted to a lower value, e.g. 30 weight % based on the solid content of the paper.
• the upper limit of the amount of thermosetting resin is determined by the adsorption capacity of the available fiber surface. The lower limit is determined mainly by requirements on the use of the resinous paper. For technical reasons, small amounts of thermosetting resin can be applied as well. However, in order to produce a resilient, usable surface on the material coated with the resinous paper, a thermosetting resin content of 30 weight % or more is usually necessary.
• thermosetting resin After sheet formation, the thermosetting resin has dried to the extent that it is blockfree. It is, however, reactive at elevated temperatures (e. g. 160
• the use of the resinous paper as a resinous preform blank has also been claimed which preform blank is used for the production of formed objects.
• the inventive preform blank can have the same technical properties as the paper described above.
• a particularly thick, sheet-like preform blank having a weight of up to 1000 g/m 2 can be manufactured according to the present invention, which preform blank is composed of fibers and thermosetting synthetic resin, dried, but not yet hardened..
• This preform blank can be inserted in molds, for example, and shaped and hardened under the effect of pressure and heat to produce two- or three-dimensional molded parts, which can be used, for example, in the automotive industry, in the construction of housings or items of daily use and for numerous other applications.
• the conditions for curing are the same as during pressing of the papers according to the present invention on a substrate.
• the preform blank according to the present invention can be more easily handled, for example, it can be cut to size or provided with holes prior to insertion into the mold. In particular, injection of the mass to be molded into the injection mould, which can be bothersome, can be eliminated.
• inventive preform blanks that consist of fibers whose surface is at least partially provided with a thermosetting resin can be used for a wide range of applications. They can be used for indoor and outdoor construction, as furniture or parts thereof, as housings, as casings, for automotive construction, for mold making and similar purposes, while the grammage and the simple and variable workability by pressing makes it applicable not only for two-dimensional, but also particularly for three- dimensional objects.
• a fiber suspension is created.
• 700 kg unbleached softwood kraft pulp is mixed into 16 m 3 of water.
• the fiber material in the suspension is ground to a SR degree between 30 ° and 35 °.
• 450 kg aluminium hydroxide is mixed into 40 m 3 water.
• Fiber suspension and aluminium-trihydrate solution are blended and 150 kg of a polychlorbutadiene polymer is added as retention means.
• 1050 kg of a phenol-resol synthetic resin in an aqueous-alkaline solution with a solid content of 48 % is added.
• the viscosity of the synthetic resin is between 600 mPas and 900 mPas (viscosity at 20° C; DIN 53015).
• the alkalinity of the resin is 4.0 % (DIN 169 16-02-G) and components that are precipitatable by sulfuric acid with a pH value of 3,5 amount to at least 30 %.
• the synthetic resin may be diluted up to a resin-to-water ratio of 1 : 20 (DIN 169 16-02) i.e. the resin concentration is at least about 5%.
• the phenol- resol resin is acid active and heat reactive. It has a low monomer content. After addition of the phenol-resol synthetic resin, the pH value of the fiber suspension is adjusted to 3.5 using 20% sulfuric acid. After addition of 3 kg of a commercial defoamer (Afranil ® MG ex BASF), the fiber concentration is adjusted to approx. 3%.
• the fiber suspension is dewatered on a paper machine wire with a web-width of approx. 2.30 m at a wire speed of 35 m/min to a paper with a grammage of 500 g/m 2 OD.
• a carbamide-containing combination of organic sulfonic acid with inorganic salts as flame retardant is applied in an amount of 50 g/m 2 to the dewatered, but not completely dried paper having a volatile content of approx. 40%.
• the paper thus treated is dried at a temperature of 120° C to a residual volatile content of 6 % to 9 %.
• the thus produced paper can, for example, be put on a wooden material board and pressed 20 to 25 minutes at 130 0 C and 60 bar in a press. If pressing times are to be shortened, pressing can be carried out at e.g. 160° C to 180° C and 80 bar.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paper (AREA)
• Reinforced Plastic Materials (AREA)

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• 2008
  • 2008-05-27 DE DE102008025269A patent/DE102008025269A1/de not_active Ceased
• 2009
  • 2009-05-27 WO PCT/FI2009/050449 patent/WO2009144379A2/en active Application Filing
  • 2009-05-27 EP EP09754032A patent/EP2297399A2/de not_active Withdrawn
  • 2009-05-27 US US12/994,585 patent/US20110220309A1/en not_active Abandoned

Non-Patent Citations (1)

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