Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
  • D21F11/02—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the Fourdrinier type
  • D21F11/04—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the Fourdrinier type paper or board consisting on two or more layers
• • 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
  • D21H27/30—Multi-ply
  • D21H27/38—Multi-ply at least one of the sheets having a fibrous composition differing from that of other sheets

Definitions

• Multi-layer paper and method of making the same are Multi-layer paper and method of making the same
• This invention relates to a mult-layer paper, which for increasing the adhesion between the layers has been supplied with a binder, and to a method of making such paper.
• the paper is manufactured by the couching of separately formed paper webs.
• problems can arise if the adhesion forces between .the layers are not sufficiently great.
• To-day the problems are coped with primarily either by increased beating of the pulps for each layer or by supplying starch in each layer or between the layers prior to couching.
• Increased beating primarily involves the disadvantages of higher energy consumption, loss of bending stiffness of the cardboard due to decrease in thickness, and reduced machine capacity.
• the addition of starch causes disadvantages such as high material, equipment and handling costs and clogging of the nozzles in spray installations.
• the object of the present invention is to overcome the said disadvantages.
• the principle of the invention is in a separate head box, spray nozzle or other application device to add a cellulose-based thin layer between two layers already formed.
• the material in this thin layer can consist of intensely beaten papermaking pulp, fine material made separately, sedimented fine material or fibres and fine material from white water or other waters containing cellulose and fibres. It is essential that the material has a beating degree of at least 40°SR. The amount of added material must not exceed 10 g/m 2 .
• the thin cellulose-based layer has the capacity of acting as a size layer increasing the adhesion capacity between the two layers formed.
• the layer adhesion between two formed layers has a strength equal to the inner strength in each layer
• the layer adhesion does not limit the general strength level.
• the beating degree in each layer thus, can be chosen so that optimum bending stiffness is obtained.
• Fig. 1 shows a machine design for making the paper according to the invention
• Fig. 2 shows the Scott-bond value for different test conditions.
• Fig. 1 shows a twin wire machine with the wires 1 and, respectively, 2.
• a first pulp suspension is supplied through a head box 3 and results in a web 5.
• a web 6 web 6 is formed by supplying a second pulp suspension through the head box 4.
• the binder according to the invention consisted of an intensely beaten papermaking pulp with a beating degree of about 6 ⁇ °SR and was sprayed between the two already formed layers through the nozzle 7.
• the amount of material applied was 5 g/m 2 .
• the material was applied in a concentration of about 1% .
• Each layer consisted of 75 g/m 2 unbleached sulphate pulp beaten to 18 or 27°SR. After the layers had been combined in usual manner, a web 8 was obtained which subsequent to its pressing in a number of rolls 8,9 yielded the two-layer paper 11.
• Sheets of the paper were dried off-machine partially freely and partially clamped in frames. The results were compared to application of starch in the same amount and only water.
• the diagram in Fig. 2 show-s the Scott-bond value (a measure of layer adhesion) for different test conditions.
• the figure shows the Scott-bond values MD (machine direction) at constant press conditions (50 + 60 + 70 KN/m pressure applied). Besides, two drying methods have been used. As can be seen, the Scott-bond increases substantially with said additions and shows an effect equal to or better than with starch addition.

Landscapes

• Paper (AREA)
• Diaphragms For Electromechanical Transducers (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20350729

Family Applications (1)

Country Status (5)

Families Citing this family (3)

Family Cites Families (1)

• 1983
  • 1983-04-11 SE SE8301973A patent/SE436140B/sv not_active IP Right Cessation
• 1984
  • 1984-04-10 WO PCT/SE1984/000131 patent/WO1984004115A1/en not_active Application Discontinuation
  • 1984-04-10 BR BR8407280A patent/BR8407280A/pt unknown
  • 1984-04-10 EP EP19840901816 patent/EP0172819A1/en not_active Withdrawn
• 1985
  • 1985-05-09 FI FI851852A patent/FI851852A0/fi not_active Application Discontinuation

Non-Patent Citations (1)

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