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
  • D21H17/63—Inorganic compounds
  • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
  • D21H17/675—Oxides, hydroxides or carbonates
• • 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
  • D21H17/66—Salts, e.g. alums

Definitions

• the present invention relates to a process for the sizing of paper, suitable for the sizing in the presence of a filler sensible to an acidic environnment, particularly calcium carbonate.
• the paper sizing phase consisting in the adhering to each other of the cellulosic fibers of the material forming the pulp by means of a sizing agent, may essentially take place according to two techniques:
• cellulose-reactive sizing agents comprise Aquapel, manufactured and sold from Hercules Inc., Basoplast of Badische Anilin and Soda Fabrik A.G. (BASF) and Tenoresin of Ciba-Geigy.
• the amount of fibres and of sizing agent retained onto the wire during the sheet forming shall be greater; on the contrary a lesser amount of fibres and of sizing agent shall be lost with the effluent waters under the wire.
• the dispersion is supplemented with properly dosed products or retention agents, such as polyamines, polyacrilamides, polyethylenamines and the like, these products being remarkably expensive.
• the fibre suspension is added with an inert filler, adapted to confer particular properties to the paper.
• kaolin and calcium carbonate can be cited.
• the sizing agent is of conventional type, namely of resinic type
• the combined use of kaolin and aluminum sulphate does not involve particular problems, except that the kaolin must be particularly pure, since possible impurities as calcium carbonate react with aluminum sulphate, whereby part of the precipitating agent is subtracted from the specific action as such.
• the filler consists of calcium carbonate
• the use of aluminum sulphate as the precipitating agent is practically inhibited since a relevant part of calcium carbonate is consumed, to form calcium sulphate, in order to neutralize the dispersion before the calcium carbonate may provide its action.
• the filler reference is generically made to the fact that the starting pulp slurry may contain, if requested, the normal fillers without further detailed indication.
• French Patent No. 2418297 discloses a paper sizing process having the purpose of improving the properties of the sized paper and the filler retention in the paper being manufactured.
• a polyvalent anion for example the anion of a mineral acid such as sulphuric acid.
• the possible fillers are indicated, namely kaolin, calcium carbonate, talc, etc. without establishing any difference amongst them.
• the aluminum polyhydroxychloride has an excellent retention action and at the same time permits calcium carbonate to be used as inert filler since the pH of the fibre dispersion is about 7.
• the aluminum polyhydroxychloride normally used as precipitating agent in the sizing of paper with conventional resinic sizing agents has, in the case of the synthetic cellulose-reactive sizing agents, an action substantially different but important as well in view of the results of the sizing process, namely a retention effect towards the fibres and the additives forming the pulp.
• the process according to the present invention is thus characterized in that to the aqueous dispersion of fibres, supplemented with a synthetic cellulose- reactive sizing agent and possibly with calcium carbonate as the filler, aluminum polyhydroxychloride having the formula: is added.
• the amount of aluminum polyhydroxychloride added to the fibre dispersion is such as to determine a retention, as measured as transparency, of about 40%
• the aluminum polyhydroxychloride useful in the process according to the invention is commercially available (Prodefloc SAB/18, sold by Prodeco Spa) , and is anyhow manufactured as described in the USP 3909439, which is herein referred to for further details.
• the aluminum sulphate had an AlZ03 content of 8.5%, whereas PAC contained 18% Al 2 O 3 .
• the retention was evaluated by measuring the residual turbidity of the filtered water at Shopper-Riegler, by means of a transparent, overturned pyramid, bearing millimetric graduations.
• the retention values were indicated as % of transparency of the drainage waters. As an optimum value, the retention giving place to a transparency percentage of at least 40 was taken.
• the retention value considered as optimum is achieved with a sulphate percentage of 16.2%, but for this amount the pH is lowered to 6.4.
• the tests particularly related to the determination of retention and of freeness and to fibre slurries containing varying percentages of mechanical pulp.
• the slurry had a freeness of 630 ml SCF (3) .
• PAC shows the best values of freeness and of retention in comparison both with alum and with WAC.
• PAC and alum show like retention values for the slurries having the lower content of mechanical pulp, but the freeness values are definitely better for PAC.

Landscapes

• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Paper (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=11188327

Family Applications (1)

Country Status (8)

Cited By (4)

Families Citing this family (3)

Citations (5)

• 1983
  • 1983-07-01 IT IT21893/83A patent/IT1163643B/it active
• 1984
  • 1984-06-28 PT PT78806A patent/PT78806B/pt not_active IP Right Cessation
  • 1984-06-28 ZA ZA844944A patent/ZA844944B/xx unknown
  • 1984-06-28 EP EP84107521A patent/EP0133902A3/fr not_active Withdrawn
  • 1984-06-29 NO NO842651A patent/NO842651L/no unknown
  • 1984-06-29 AU AU30058/84A patent/AU3005884A/en not_active Abandoned
  • 1984-06-29 FI FI842646A patent/FI842646A/fi not_active Application Discontinuation
  • 1984-07-02 JP JP59135375A patent/JPS6034698A/ja active Pending

Patent Citations (5)

Non-Patent Citations (2)

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