Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Chemical treatment after start or completion of mechanical...
Reexamination Certificate
1999-08-30
2002-02-05
Alvo, Steve (Department: 1731)
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Chemical treatment after start or completion of mechanical...
C162S072000, C162S076000, C162S091000
Reexamination Certificate
active
06344108
ABSTRACT:
The invention relates to a process for producing fibrous materials for the manufacture of cellulose, paper, or boards of wood material, using at least one dicarboxylic acid dialkyl ester and/or a fatty acid polyol mono-, di-, tri-, and/or higher polyester and/or polyester-polyether copolymer, and to the products produced from these fibrous materials, such as cellulose, paper and wood material boards.
Fibrous materials or fiber raw materials such as mechanical wood materials and long-fibered raw materials and, in particular, thermomechanical pulp (TMP) or chemithermomechanical pulp (CTMP) are obtained in mechanical wood pulping by defiberizing reduced wood materials with separation and fibrillation of single fibers according to a thermal or chemical-thermal pretreatment (cf., Römpp Chemielexikon, 9th edition, 1991, pages 3208 and 4345).
Owing to its superior fiber length and brightness, TMP is better suited in replacing cellulose than groundwood pulp and therefore, also with respect to cost, is used in manufacturing bulk printing papers, such as rotary printing paper, light-weight paper, and cardboard articles. In the production of semichemical pulps, and in cellulose recovery as well, one attempts to decrease the substance content of lignin and hemicellulose by delignification and/or oxidative or reductive bleaching processes in order to reduce yellowing in articles produced using these materials. These efforts in bleaching wood materials have been reported in detail by H. U. Süss and W. Eul in Wochenblatt für die Papierfabrikation 9 (1986), pp. 320-325, where it has been determined that yellowing of the materials may occur which depends on the dosage of the bleaching chemicals, affecting the whiteness stabilization of the products. As a variant of the well-known Alcell or Organocell processes, DE 41 03 572 C2 performs the delignification of plant fibrous materials, particularly wood chips, in such a way that initially, the chips are completely impregnated with alcohol in order to avoid a fiber-damaging effect of the subsequent addition of alkali.
WO 94/12721 and WO 94/12722 describe delignification processes using peracetic acid and complex compounds with subsequent bleaching using ozone or sodium dithionite, while DE 195 09 401 A1 subjects wood pulps and secondary semichemical fibrous pulps to a multistage peroxide bleaching under pressure, wherein the complexing agents used are said to improve the effect of the perhydroxy anions on lignin chromophores present in the interior of the fibers.
According to EP 553,649 B1, the delignification of cellulose pulp is performed using a mixture of monopersulfuric acid and sulfuric acid with subsequent neutralization.
As the use of chemicals in the production of CTMP gives rise to waste water problems, the process for manufacturing wood fiber boards according to EP 639,434 B1 omits the removal of the chemicals after pulping.
The bleaching of lignin-containing materials with oxidants, using hydroxylamine and hydroxamic acid compounds, or a large number of compounds including an N-hydroxy, oxy, N-oxy, or N,N′-dioxy function is described in EP 717,143 A1, wherein esters of 1-hydroxybenzotriazole, cinnamic acid and 4-tert-butylbenzoic acid are mentioned as components in the process.
According to WO 95/00704, components of degradation products of native starch are also added to the wood pulp suspension in order to fix resins, which components, however, readily undergo microbiological degradation in the stock circulation, unless countermeasures are provided.
Similarly, products produced by alkoxylation of C
10
-C
22
carboxylic acid derivatives and/or C
10
-C
22
carboxylic acids having OH groups, e.g., those produced from soybean oil or linseed oil, are to be added according to DE 195 15 272 A1 in order to control the settling of resins. The intention in this process probably is to have improved dispersion of the resins in cellulose and/or wood pulp suspensions or primary fiber suspensions in order to avoid trouble during primary fiber processing. There are no indications as to the effectiveness of these compounds.
For the treatment of lignin-containing materials, WO 94/29510 and WO 96/18770 describe multicomponent systems comprised of oxidants and oxidation catalysts, as well as mediators from the group of hydroxylamines, hydroxamic acids, aliphatic, cycloaliphatic, heterocyclic, or aromatic compounds having N-hydroxy, oxime, N-oxy, or N,N′-dioxy functions, and co-mediators containing aromatic alcohols, carbonyl compounds, aliphatic ethers, phenol ethers, and/or olefins.
Accordingly, the well-known processes for manufacturing wood pulps are characterized by the use of a large number of various adjuvants having complex effects, the use which, depending on the manufacturing conditions and the raw materials employed, must be subjected to extensive control, and they are limited in their effectiveness. It was therefore the object to find a process for producing fibrous materials that could be performed without the above-mentioned drawbacks, and wherein fibrous materials having equivalent or improved properties could be obtained.
Also, there was the problem of finding agents for use in the production of fibrous materials that would permit the production of improved fibrous materials, particularly TMP and CTMP, and the production of improved or more inexpensive products on the basis of these raw materials, and in particular, accounting for ecological aspects, such as restrictive use of chemicals polluting the environment, or utilization of low-quality raw materials or waste raw materials.
According to the invention, said object is accomplished by using one or more dicarboxylic acid dialkyl esters and/or one or more fatty acid polyol mono-, di-, tri-, and/or higher polyesters and/or polyester-polyether copolymers in the impregnating pretreatment of reduced wood raw materials.
Accordingly, the invention is directed to a process for producing fibrous materials, preferably mechanical wood pulps such as thermomechanical pulp (TMP) or chemithermomechanical pulp (CTMP) and groundwood pulp, characterized in that at least one dicarboxylic acid dialkyl ester and/or one or more fatty acid polyol mono-, di-, tri-, and/or higher polyesters and/or polyester-polyether copolymers are added during the production process, particularly during the pretreatment for impregnating the reduced wood raw material, or during reduction of the wood raw material.
The invention is directed to an agent for producing fibrous materials, preferably TMP, CTMP and groundwood pulp, characterized by containing one or more dicarboxylic acid dialkyl esters and/or one or more fatty acid polyol mono-, di-, tri-, and/or higher polyesters and/or polyester-polyether copolymers.
Surprisingly, it has been determined that dicarboxylic acid dialkyl esters and/or fatty acid polyol mono-, di-, tri-, and/or higher polyesters and/or polyester-polyether copolymers are effective in the pretreatment of reduced wood and/or plant materials, and that primary fibers produced using same are purified to a higher level from adherent lignin, resin components and other wood constituents, so that materials having improved optical properties are obtained in highest yields. According to the invention, brightness, whiteness, color tone and color saturation of the mechanical wood pulps are improved in particular, without impairing the other properties, particularly the stability properties of the fibrous materials.
According to the invention, dicarboxylic acid dialkyl and/or diisoalkyl esters of C
2
-C
12
dicarboxylic acids with C
1
-C
13
n- and/or isoalkanols, such as di-n-butyl oxalate, din-butyl malonate, di-n-butyl succinate, di-n-butyl glutarate, di-n-butyl adipate, di-n-butyl suberate, di-n-butyl sebacate, dimethyl adipate, diethyl adipate, di-n-propyl adipate, diisopropyl adipate, diisobutyl adipate, di-tert-butyl adipate, diisoamyl adipate, di-n-hexyl adipate, di(2-ethylbutyl) adipate, di(2-ethylhexyl) adipate, diisodecyl adipate, dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, diis
Hänssle Peter
Rajcsanyi Thomas
Von Medvey Ingo
Werres Joachim
Alvo Steve
Stockhausen GmbH & Co. KG
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