Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
  • D21G3/00—Doctors
  • D21G3/005—Doctor knifes
• • 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
  • D21H25/08—Rearranging applied substances, e.g. metering, smoothing; Removing excess material
  • D21H25/10—Rearranging applied substances, e.g. metering, smoothing; Removing excess material with blades

Definitions

• Blade for a doctor in a paper/board machine and method for simultaneous coating and doctoring of a roll in a paper/board machine
• the invention concerns a blade for a doctor in a paper/board machine, which blade contains compounds that repel impurities and removes any undesirable material from the face of a roll and, at the same time, coats the roll with said compounds.
• doctor blades are employed for removal of undesirable material from the roll faces.
• a method and a device are described for application of a fluoroplastic onto the face of a roll in a paper machine.
• the application of the fluoroplastic takes place by press polishing so that a fluoroplastic disk or bar is pressed against the face of a revolving roll.
• a fluoroplastic beam By means of a fluoroplastic beam, the roll face is press polished, and in this way the properties of detaching of the web are improved and the problems of contamination are reduced.
• a fluoroplastic beam can be mounted in the holder of a doctor, but even then it is used for fluorine treatment of the roll face only, and not for doctoring.
• press polishing is mechanical rubbing of the roll face with a piece of fluoroplastic, and adhering of the fluoroplastic to the roll face varies to a considerable extent, in particular if the roll face is contaminated or it involves other heterogeneity. Also, fluoroplastic adheres to a cold roll face rather weakly and does not stick to the face evenly.
• the object of the present invention is a blade of a doctor for rolls in a line of manufacture of paper/board, which blade, at the same time, removes contaminations and undesirable material from the roll face and coats the roll face with a compound that repels impurities continuously, as well as a method for simultaneous doctoring and coating of a roll with a compound that repels impurities.
• a doctor blade in accordance with the present invention comprises a binder matrix and a coating matrix.
• the binder matrix consists of a thermosetting resin or of a thermoplastic resin.
• suitable thermosetting matrix plastics are epoxy resins, polyesters, vinyl esters, acrylates, methacrylates, and copolymers and terpolymers of same and their mixtures.
• suitable thermoplastic matrix resins are polyamides (P46, PA6, and PA66), polyphenylene sulfide, poly ether ketone, poly ether-ether ketone, polyester thermoplastic resin, polyphtalamide, polyetherimide, poly ether sulfone, polysulfone, etc. thermoplastic materials with good resistance to heat, together with their copolymers and terpolymers and mixtures of same.
• the binder matrix is preferably reinforced with a suitable reinforcement, which includes, advantageously, carbon fibre, fibreglass or boron fibre reinforcements, preferably as an oriented fibre or discontinuous fibre.
• the doctor blade also comprises a coating matrix, which is made of a material that repels impurities, favourably of a halogen polymer compound, which is brought into connection with the binder matrix by physical or chemical means.
• the doctor blade contains 0.5...50 %, preferably 0.5...10 %, of coating matrix.
• the coating matrix is favourably mixed with the binder matrix in particle form, preferably by dispersing into the matrix mix.
• An advantageous coating matrix contains a fluoropolymer, for example FEP, PFA, PTFE, ETFE, etc.
• the melting point of the binder matrix must be equally high as, or higher than, the melting point of the coating matrix. Friction heat that arises in the doctoring process produces melting of the polymer material at the tip of the doctor blade, as a result of which the molten polymer material is separated from the blade and adheres to the roll face, at which the temperature is lower than at the tip of the blade, in which connection the polymer solidifies onto the roll face.
• the melting of the coating matrix must take place first, i.e. its melting point must be lower than the melting point of the binder matrix.
• thermosetting plastic matrix When a thermosetting plastic matrix is used, also the same melting point can be permitted, because thermosetting plastic starts decomposing at its melting point.
• the melting point of coating matrix materials is preferably in the range of about 180...250 °C, and the melting point of binder matrix materials equally high or higher.
• particle mixing the particle size also affects the final result in order that a sufficient sintering on the roll face could be achieved.
• a suitable particle size is 40...120 ⁇ m, preferably about 60...90 ⁇ m, in order that the friction heat should be sufficient for melting the particle and that the particle should be detached from the blade in the molten state.
• the coating matrix can optionally also be prepared so that the binder matrix is subjected to a fluorination treatment under such conditions that oligomer chains and/or polymer chains that contain fluorine are immobilized in the polymer structure of the binder matrix by means of physical or chemical bonds.
• fluorine compounds that are used for fluorination can be mentioned fluorinated macro-oligomers, diols, triols, thiols, and/or polyols, as well as their adducts with various anhydrides.
• the doctor blade is manufactured preferably by means of a pultrusion process.
• a material that repels impurities preferably a fluoropolymer
• a material that repels impurities can be applied to the face of a roll in a paper or board machine in the structure of a well operating doctor blade without loss of the doctoring properties of the doctor blade itself.
• the roll can be coated in a controlled way and homogeneously with a material that repels impurities.
• a fibre-reinforced composite doctor blade has excellent doctoring properties, which are also essential in order that the coating process could be carried out successfully.
• friction heat is utilized, by whose effect the fluoropolymer can be sintered onto the roll face.
• a doctor blade in accordance with the invention can be used for applications of doctoring of rolls in lines of manufacture of paper, rolls in a line of manufacture of board, and of rolls in printing machines and, in general, for simultaneous coating and doctoring of a revolving roll or a moving face in order to prevent contamination.

Landscapes

• Paper (AREA)
• Crushing And Pulverization Processes (AREA)
• Coating Apparatus (AREA)
• Reinforced Plastic Materials (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8547843

Family Applications (1)

Country Status (7)

Cited By (5)

Citations (3)

• 1997
  • 1997-07-15 FI FI970331U patent/FI3131U1/fi not_active IP Right Cessation
• 1998
  • 1998-06-26 AT AT98929468T patent/ATE265574T1/de not_active IP Right Cessation
  • 1998-06-26 CA CA002295611A patent/CA2295611C/en not_active Expired - Fee Related
  • 1998-06-26 EP EP98929468A patent/EP1073793B1/en not_active Expired - Lifetime
  • 1998-06-26 DE DE69823559T patent/DE69823559T2/de not_active Expired - Fee Related
  • 1998-06-26 WO PCT/FI1998/000561 patent/WO1999004091A1/fi not_active Ceased
  • 1998-06-26 AU AU79218/98A patent/AU7921898A/en not_active Abandoned

Patent Citations (3)

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