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CA1110019A - Process for manufacturing paper having improved dry strength - Google Patents

Process for manufacturing paper having improved dry strength

Info

Publication number
CA1110019A
CA1110019A CA 302830 CA302830A CA1110019A CA 1110019 A CA1110019 A CA 1110019A CA 302830 CA302830 CA 302830 CA 302830 A CA302830 A CA 302830A CA 1110019 A CA1110019 A CA 1110019A
Authority
CA
Grant status
Grant
Patent type
Prior art keywords
polymer
water
soluble
cationic
pulp
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA 302830
Other languages
French (fr)
Inventor
Kenichi Honma
Toshiaki Sugiyama
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kyoritsu Yuki Co Ltd
Mitsubishi Kasei Corp
Original Assignee
Kyoritsu Yuki Co Ltd
Mitsubishi Kasei Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Grant date

Links

Classifications

    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP 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
    • D21H23/00Processes or apparatus for adding material to the pulp or to the paper
    • D21H23/76Processes or apparatus for adding material to the pulp or to the paper characterised by choice of auxiliary compounds which are added separately from at least one other compound, e.g. to improve the incorporation of the latter or to obtain an enhanced combined effect
    • D21H23/765Addition of all compounds to the pulp
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP 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
    • D21H17/00Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20Macromolecular organic compounds
    • D21H17/33Synthetic macromolecular compounds
    • D21H17/34Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/41Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
    • D21H17/42Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups anionic
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP 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
    • D21H17/00Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20Macromolecular organic compounds
    • D21H17/33Synthetic macromolecular compounds
    • D21H17/34Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/41Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
    • D21H17/42Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups anionic
    • D21H17/43Carboxyl groups or derivatives thereof
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP 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
    • D21H17/00Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20Macromolecular organic compounds
    • D21H17/33Synthetic macromolecular compounds
    • D21H17/34Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/41Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
    • D21H17/44Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups cationic
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP 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
    • D21H17/00Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20Macromolecular organic compounds
    • D21H17/33Synthetic macromolecular compounds
    • D21H17/34Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/41Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
    • D21H17/44Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups cationic
    • D21H17/45Nitrogen-containing groups
    • D21H17/455Nitrogen-containing groups comprising tertiary amine or being at least partially quaternised
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP 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
    • D21H17/00Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20Macromolecular organic compounds
    • D21H17/33Synthetic macromolecular compounds
    • D21H17/46Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/54Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP 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
    • D21H17/00Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63Inorganic compounds
    • D21H17/66Salts, e.g. alums
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP 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
    • D21H21/00Non-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
    • D21H21/14Non-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
    • D21H21/28Colorants ; Pigments or opacifying agents

Abstract

ABSTRACT OF THE DISCLOSURE
Paper having improved dry strength is manufactured from a composition produced by mixing a pulp slurry with a water soluble cationic polymer and then, adding a water soluble anion-ic polymer to the slurry.

Description

The present invention relates to a process for manufac-turing paper. More particularly, the invention relates to a process for improving dry strength of paper with a cationic polymer and an anionic polymer.
It is important to improve paper strength because hard-wood pulp providing lower paper strength must be used as the raw t material because of a shortage af softwood pulp providing higher paper strength. It is known to add a water soluble polymer, such as starch, in the paper manufacture in order to improve the dry paper strength. It is considered that the starch is an adhesive between pulp fibers. However, starch is easily removed in the white water in the paper making process and the use of strength agents as dry anionic polymers has increased. When the anionic polymers are used, the polymers are retained on pulp fibers as water insoluble particles formed by adding aluminum sulfate. L
A method of improving the retention by adding the anion-ic polymer and aluminum sulfate and then adding a water soluble cationic polymer to cause aggregation of the water insoluble particles formed in the deposition of the anionic dry strength agent with aluminum sulfate, has been disclosed in TAPPI Vol. 51 No. 11, 59A - 65A(1968). A method of simultan-eously adding the water soluble anionic polymer and the water soluble cationic polymer is also disclosed in said reference.
In the method, coarse particles formed by reaction in water are deposited on the surface of the pulp. However, on the basis of the adhesive concept, the dry strength agent acting as an adhesive agent should maximize the contact area of pulp fibers.
Accordingly, it is preferably to uniformly cover the surface of the pulp fiber with fine particles in comparison with coarse particles between the pulp fiber.
In the aforesaid methods, the water soluble anionic polymer may be ununiformly distributed on the surface of the pulp fiber and as a result, the improvement in dry paper strength has not been sufficiently high.
It has now been found that dry paper strength can be improved by sequentially adding the water soluble cationic polymer and then the water soluble anionic polymer.
Thus the present invention provides for improving dry paper strength in the manufacture of paper.
According to the present invention there is provided a process for manufacturing paper having improved dry strength which comprises mixing an essentially alum free pulp slurry with a water soluble cationic polymer and subsequently adding a water soluble anionic polymer to the essentially alum free slurry and making the paper from the composition so obtained.
The water soluble cationic polymers used in the process of the present invention include various polymers as homopoly-mers of a cationic monomer or copolymers of at least one cationic monomer and another unsaturated compound. Suitable cationic monomers include vinylpyridine; vinylimidazolidien; diallyl-amine; ethyleneimine; and acrylates and methacrylates having the formula R R
CH2=c-coo-y-N\

wherein R represents hydrogen atom or methyl group; R and R are the same or different and represent an alkyl group or an aralkyl group and Y represents an alkylene group having 2 or more of carbon atoms or ahydroxylalkylene group having 2 or more of carbon atoms; such as dimethylaminoethyl acrylate, dimethyl-aminoethyl methacrylate, diethylaminoethyl acrylate, diethyl-aminoethyl methacrylate, dibutylaminoethyl acrylate, dibutyl-aminoethyl methacrylate, methylethylaminoethyl acrylate, and dimethylamino-2-hydroxypropyl methacrylate, and acid salts of ,~ - 2 -Ql9 the cationic monomers. The acids used for the acid salts can be inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid and organic acids such as acetic acid and propionic acid. The cationic monomers can be also quaternary ammonium salts of said cationic monomers obtained by reacting said cationic monomer with a quaternizing agent such as an alkyl halide, an aralkyl halide or a dialkyl sulfate. ~ther suitable unsaturated compounds used for copolymerizing with said cationic monomer include acrylamide or methacrylamide.
The water soluble cationic polymers can be also cationic modifiers of polymers having main component of acrylamide or methacrylamide (hereinafter referring to cationic modified acrylamide polymer). The cationic modified acrylamide polymers can be a Mannich reaction product obtained by reacting the acrylamide polymer with formaldehyde and an amine such as (methylamine, dimethylamine, ethylamine, or diethylamine) and aminomethylating a part of carbamoyl groups of the polymer;
modified polymers obtained by converting a part of carbamoyl groups of the polymer to amino group by Hofmann degradation;
and quaternary compounds obtained by reacting said Mannich reaction product with the ~uaternizing agent. The water soluble cationic polymers can be also cationic polycondensates such as polycondensates of an epoxy compound such as epihalohydrin with at least one of amines such dimethylamine, monoethylamine, ethyl- j enediamine, polyalkylene polyamines such as pentalthylene hexa- ¦
mine, polyamide polyamine, aniline and ammonia (USP 3,738,945) and polycondensates of formaldehyde and said amine or dicyandia-mide. The water soluble cationic polymers can be also cationic modified high molecular natural compounds such as cationic modified starch and glycolchitosan. The optimum water soluble cationic polymers include homopolymers of diallylamine, or ~uaternary salts thereof, dimethyl aminoethyl methacrylate, or t quaternary salts salts thereof; and copolymers of the monomer with acrylamide; partial Mannich reaction products of acrylamide polymer and quaternary ammonium compounds thereof and poly- !
condensates of epichlorohydrin and dimethyl amine. It is es-pecially preferable to use the quaternary ammonium compound since it can be added regardless of pH of the pulp slurry.
.
The retention of the water soluble cationic polymer used in the process of the present invention increases with the in-crease of molecular weight of the water soluble cationic polymer and it is preferably to be of high molecular weight. In the process of the present invention, it is necessary that the viscosity of 10~ aqueous solution of the water soluble cationic polymer be greater than about 5 cps, preferably greater than about 10 cps. The content of the cationic groups in the poly-mer affects to the effect of retention. The optimum cation con- ¦
tent depends upon the molecular weight of the polymer and is usually greater than about 1.0 gram ion/Kg. polymer for the polymer having greater than about 100 cps of viscosity for a 10% aqueous solution and is usually greater than about 3.0 gram ion/Kg. polymer for the polymer having 5 to 100 cps of viscosity for a 10% aqueous solution.
The amount of the water soluble cationic polymer de-pends upon the types of the pulp and the cationic polymer and the dry strength of the desired paper, and is usually more than about 0.01% by weight per dry pulp. The amount of the water soluble cationic polymer can be increased until floating the polymer in water without the retention on the pulp fiber to cause the decrease of the paper strength. The maximum dosage depends upon the type of pulp and the water soluble cationic polymer and is usually about 1 wt.% per dry pulp.
The water soluble anionic polymers used in the present invention can be various anionic polymers used as dry strength agent. ("Strength agents" in Paper and Pulp Technology Times in Japan: Oct. 1976). Suitable water soluble anionic polymers include the polymers having carboxyl groups or carboxylate groups such as partially hydrolyzed products of acrylamide poly-mers and salts thereof, copolymers of acrylamide and maleic acid, acrylic acid or salt thereof, and oxidized starch. It is also possible to use water soluble polymers having sulfonic acid group. The anionic polymers having a viscosity of about less than 50,000 cps as a 10% aq. sol. are preferably used. An anion component in the water soluble anionic polymer is in a range of 2 to 30 mole ~, preferably 4 to 25 mole % as acrylic acid in the case of the copolymer of acrylamide and acrylic acid.
The conversion ratio of hydrolysis is in a range of 2 to 30 mole %, preferably 4 to 25 mole % in the case of partially hydrolyzed product of polyacrylamide wherein the mole % desig-nates the ratio of the hydrolyzed monomer component in total monomer components in the polymer. The anion content corres-ponds to 0.280 to 3.85 gram ion/Kg. polymer preferably 0.556 to 3.26 gram ion/Kg. polymer as the unit of gram ion. In the other water soluble anionic polymer, the anion content may be selected from said range.
The amount of the water soluble anionic polymer is the F
amount used as the conventional dry strength agent and depends upon the types of the pulp and the anionic polymer and the desired dry strength agent and is usually more than about 0.1%
by weight to dry pulp. The ionic e~uivalent ratio of the water soluble cationic polymer to the water soluble anionic polymer is more than about 10 mole ~ preferably more than about 50 mole %.
In the paper manufacture by the process of the present ~0 invention, it is necessary to add the water soluble cationic polymer to the pulp slurry first and then to add the water sol-uble anionic polymer The water soluble cationic polymer and the _ 5 _ ~0019 water soluble anionic polymer are added to the pulp slurry in a desira~ly stage from the preparation of the pulp slurry to the formation of paper sheet, that is, from the preparation of pulp slurry composition to the wet end on a paper machine wire.
The preparation of the paper slurry composition can be attained by conventional processes except sequentially adding the water soluble cationic polymer and the water soluble anionic polymer in that order.
The pulp used in tne paper manufacture is not critical and can be hard wood and soft wood or regenerated pulp obtained from waste paper. It is possible to add the conventional additives such as filler, a sizing agent, a dyestuff and other additive as desired. The additives can be the conventional ones used in the conventional paper manufacture such as kaolin, talc, clay, calcium carbonate and titanium oxide as the filler; rosin sizing agent and synthetic sizing agent as the sizlng agent. The additives can be added before or after the addition of the water '-soluble cationic polymer and the water soluble anionic polymer. E
s~l~se 7ue~f/y D If necessary, aluminum sulfate can be~added in order to improve the retention of the water soluble cationic polymer and anionic polymer and the additives. The pH of the pulp slurry may be it/~
controlled in a range of 4 to 9 as the conventional process. In the optimum example for prearing the pulp slurry, the water soluble cationic polymer is added and dispersed to the pulp slurry with or without a filler and then, the water soluble anionic polymer is added and then a rosin sizing agent is added, and finally, aluminum sulfate is added. The paper making of the pulp slurry can be attained by the conventional process.
The important feature of the present invention is to add ~0 the water soluble cationic polymer to the pulp slurry to charge the surface of the pulp fiber in positive charged and then, to add the water soluhle anionic polymer to uniformly distribute the illOOl9 anionic polymer on the surface of the pulp fiber. When the cationic polymer is added after the addition of the anionic polymer or at the same time adding the anionic polymer as the F
conventional process, the effect of the present invention is not achieved.
When aluminum sulfate is used instead of the water sol- i uble cationic polymer in order to give the positive charge on the surface of pulp fiber, the adsorption of aluminum sulfate on the pulp is weak whereby it is not possible to provide enough 10positive charge. ~hen a large amount of aluminum sulfate is added, aluminum ions remain in water to react aluminum sulfate with the anionic polymer whereby the water insoluble particles are disadvantageously produced. On the contrary, the water soluble cationic polymer is completely retained on the surface of the pulp fiber by vigorously stirring even though a large amount of the cationic polymer is added.
Accordingly, the anionic polymer added later, can be completely retained on the surface. F
The present invention will be further illustrated by F
way of the following examples in which ~a) The dry strength was measured by Japanese Industrial Standard as bursting factor and comprehensive strength. f (b) T}le viscosity of the polymer was shown as the ~.
viscosity of 10% aqueous solution of the polymer measured at l~
25~C by Brookfield viscometer, and (c) The ion content was shown in the unit of gram ion~
Kg. polymer.
Example 1: ~
A water soluble cationic polymer (A), a water soluble d anionic polymer (B) and aluminum sulfate (C) were respectively F
added, in the order shown in Tables, to 0.5% of a pulp slurry of LBI~ ardwood bleached kraft pulp) beaten to CS~ ~Canadian ~ 7 -~Ql9 Standard Freehess) of 400 ml.
The resulting pulp slurry was treated by TAPPI standard sheet machine to make a paper having a basis weight of 50g/m2 F
and the bursting factor of the paper was measured by Japanese Industrial Standard P-8112.
The results are shown in Tables 1 to 3.
The kinds of the polymers and aluminum sulfate and the stirring condition are as follows.
Water soluble cationic polymer (A):

Copolymer having 7 0 mole % of acrylamide component and 30 mole % of methacryloyloxyethyl trimethyl ammonium chloride component which had a viscosity of 9800 cps and a cation content of 2 . 68 gram ion/Kg. polymer.
Water soluble anionic polymer (B):
i Partially hydrolyzed product of polyacrylamide which had a hydrolysis rate of 15 mole % and a viscosity of 12, 000 cps and anion content of 2. 02 gram ior~Kg,polymer.
Aluminum sulfate (C): Solid aluminum sulfate Stirring condition:

Each stirring by a propeller stirrer was carried out at 200 r~
r.p.m. for 30 secon~ls after each addition of each of components (A), (B) and (C). The amounts of the components are shown as percen- Ji tages per dry pulp. -Table l:(Reference) _ _ t Order of addition: Component (B) ~Compotlent ~C) ., (A)10 (B)% (C)% _ Bursting factor O 0.1 2.0 2.83 ~
0 0.2 2.0 3.15 `
O 0.;~ 2.0 3.31 F
n 0.4 2.0 3.4~

T.ll)lc ~ r~

Ordcr of addition: Componcnt (B) ~Component (C)~Component (A) (A )~c ( 13)~/o (C )% Bu rst in facto r 0.01 0.2 2.0 3.21 0.0:~ 0.2 2.0 ~.25 0.0~ 0.2 2.0 3.35 0.10 0.2 2.0 3.50 T able 3: ( Invent ion) Order of Iddition: Component(A)~Component(B)~Component (C) __ _ ~ B)% (C)'70 BUrstin factor g 0.01 0.2 2.0 3.23 0.03 0.2 2.0 ~.48 0.06 0.2 2.0 '~.72 0. 1 0 0. 2 2. 0 3. 96 .

In comparison with the results in Tables 1 and 2, the paper made by the process of ttle present invention had significantly high r strength as shown in Table 3.

~xample 2: r A water soluble cationic polymer (Al) was added and mixed ~
to 0. 5% of a pulp slurry of wasted corrugated board beaten to CSF of ~;
400 ml ancl then, a water soluble anionic polymer ~Bl) was added. ~ -The resulting pulp slurry was treated by TAPPI standard slleet machine to make a paper having a basis weight of 150g/m2 and the compressive strength of the paper was measured by Japanese lndustrial Standarcl 1'-8126. The results are shown in Table 5.
As the refercnce. the water soluble anionic polymer (B ) and aluminum sulfate (C) were added and the resulting pulp slurry ~Yas treated to make a paper. The results are shown in Table 4.
The kinds of thc polymers are as follows.

~110Q19 Watcr solul~lc cationic polymc~

Quaternary ammonium compound of Mannich reaction product obtained by reacting polyacrylamide with formamide and dimethylamide, then quaternized with dimethyl sulfate.
Dimethyl aminomethylated component: 50 mole % to acrylamide component Quaternary component: 30 mole % to acrylamide component Viscosity : 13,500 cps Cation content : 3. 51 gram ion/Kg.polymer Water soluble anionic polymer (B~
Copolymer of 10 mole % of sodium acrylate and 90 mole 7a of acrylamide Viscosity: 8, 000 cps (10 % aq. ) A nion c onte nt: 1 . 3 7 gram ion / Kg . polyme r Aluminum sulfate: Solid aluminum sulfate ~;tirring condition:

Each stirring by a propeller stirrer was carried out at 200 r.p.m. for 30 seconds after each addition of each of components (Al), "
(B1) and (C). The amounts of the components are shown as percentages per dry pulp. ~-F
Ta~)lc 4:(l~efcrencc) C)rdcr of ~d(litiOll: Components (Bl)~(C) ,~
~ _ ___._ . ~
(Al)% 1 (13 )% (C)~o C'ompressive strength (~Cg.f) t`
0 0.2 0 15.2 O ~). 3 O 1 . 52 O û.~} O 15.5 0 0.2 2.0 17.5 0 0.3 2.0 18.4 ', 0 0.4 2.0 19.3 L
0.2 3.0 17.6 o o. ~ 3. 0 1~. 6 F
0 0.4 ~.0 19.3 lllQQl9 ~`al~lc 5: (Invcntion) _ _ _ Order of addition: Com~onents~Al)~(B ) >(C) _ . . . _ _ (Al )% ( ~ % (C)% Compressive st rength ( l~e. f) , , 0.01 0.2 U 20.1 0.03 0.2 0 20.5 0.06 0.2 0 - 21.~
0.10 0 2 0 22.5 0.01 0.3 0 20.6 0.03 0 3 0 21.5 0.06 0.:~ O 22.8 0.10 0.3 0 23.4 0.01 0.4 0 21.1 0.0:~ 0.4 0 22.6 0.0~ 0.4 0 23.5 0.10 0.4 0 24.5 0.01 0.2 2 20.8 t 0.03 0.2 2 21.'4 0.06 0, 2 2 22.2 '-0.1 0.2 2 22.8 ,~
0.01 O. 3 2 21.2 ~;
0 03 0 3 2 21.8 P
0.0~ O. :~ 2 22.6 O.1 O.3 2 2 0.01 0.4 2 21.7 0.0;3 0.4 2 22.4 0.0~ 0.4 2 23.0 k 0.1 _ 0 4 2 23. ~ ,1 Example 3:

A water soLuble cationic polymer (A2 - 1), (A2 - 2) and a watcr solublc anionic polymer (B~) and alumillum sul~ate (C) and a sizing agent (D~ were added to 5 % of a pulp slurry of LBKP having C'~ ` of ~00 ml in various ordcrs . The resultin~ pulp slurry was treated to make a papcr in accordance with the process of Exarnple 1 and the ~1~0~19 bu~sling fac~ol~ of the paper was mcasurcd.
'rhe results are shown in Tables 6 to 8.

Table 6 shows the results of the cases using no water soluble cationic polymer.
Tal)le 7 shows the results of the cases using the water solu-ble cationic polyn~er (A2 - 2) having low viscosity such as 3 cps. (10% aq. ) Even thOUgll ttle order of additions is (~2 - 2)~(B)~(L))~(C).
the results were not superior.
Table 8 shows the results of the cases using the water soluble cationic polymer having a viscosity of 12 cps.

Water solul~le cationic polymer (A2 - 1) l~eaction product of epichlorohydrin and ethylenediamine at equi-molar rat io Viscosity: 12 cps (10% aq~
Cation content: 13.1 gram ion/Kg~polymer Water soluble cationic polymer (A2 - 2):
The same with (A~
Viscosity: 3 cps (lO~o aq) Cation content: 13.1 gram ion/Kg,polymer Water soluble anionic polymer (B2): ~
I'artially hy(lrolyzed ~)roduct of polyacrylami~le tlaving 15 mole % of t anionic component content.
Vlscosity: 12, 000 cps r Alumirlulll sulfate (C): Solid aluminum sulfate ._ Sizing agent (D):
riched rosin size Sizepine E~ ( Manufact-lrcd by ~rakawa ~agaktl 1~. K. ) Stirring condition:

~'ach stirring by a propeller stirrer was carried out at 100 r.p.m. for ~0 SeCOllC~S a~ter each addition of each of component F
(A2 -1~, (A2 - 2), (132), ~l)),(C).The amounts of the components are ~110~19 S~lOWII as l)el`C~llt.lgCS ~)CI` d~y pul~.
TaL)lc 6 ~ fc rcnc~ ) Or~ler of addition: Components (B2)~tD) ~(C) i ( ~32 )~J1o(D )% (C)% Bursting factor 0.1 1.0 3.0 3.02 ;:
0.2 1.0 3.0 3.23 O.J 1.0 , 3.0 1 3.33 Table 7 ~e fe rence ) Ordcr of addition: Components (A2-2)~(B2)~(D)~(C) (A2 2)% ( ~32)% __ __ _ _ __ j_ __ Bursting factor 0.01 0.2 1.0 3.0 ~.30 0.05 0.2 1.0 3.0 3.36 0. 10 0 2 1. 0 1 3. 0 3. 43 Ta~le 8: (Invelltion) ~;

()rdcr of acldition: Components (A2-1) ~(B2) ~(D)~(C) 'O _ _ ~ ~:
~ 132 )% (D)% ( C )% Bursting factor 0.01 0~1 1.0 3.0 3.32 E
0.05 0.1 1.0 3,0 '~.49 0. 1 0 0. 1 1 . 0 3 . 0 3. 62 t`
0.01 0.2 1.0 3.0 3.45 0.05 0.2 1.0 3 0 3.61 F
0.10 0.2 1.0 3.0 3.78 0.01 0.:3 1.0 3.0 3.6~3 ;
~). 05 U. ~3 1 . 0 ~. 0 '3. ~30 0.10 0.3 1.0 _ a.a 3.~5 ~0 I~xamplc 4:
A filler (E) was added to 0. 5 % of a p~llp slurry of Ll3KP having CS~ of 400 mL and then, a water soluble cationic poly-mer (i~3) ~vas acl(lecl an(l th~n a water soluble anionic polymer (~3) was added anc3 t`sle sizing agent (D) was added,and aluminum sulfate (C) was adcled. The resulting pulp slurry was treated by TAPPI standard sheet machine to make a paper having a basis weight of 50 g¦m2 and the bursting factor of the paper was measured by Japanese Industrial Stanclarc3 P-3112.
The results arc shown in Table 11 .
Table 9 sshows the results of the cases using no water soluble cationic polymer (A3). F
Table 10 shows the results of the cases adding the water L0 soluble cationic polyrner (A3) after the addition of aluminum sulfate (C).
The amounts of the components are shown as percentages per (Iry pulp.

Water sol--l)lc cationic polymer (A3): !
i Copolymer of 60 mole % of acrylamide component and 40 mole % of c3imethyl aminoethyl methacrylate. i.
Viscosity: 2300 cps (10% aq. ) Cation content: 4.01 gram ion/Kg.polymer Watc r solublc anionic polymcr (B3):

I'artially hydrolyzed procluct of polyacrylamide r Anionic con-ponc)nt : 20 mole ~/0 V j scc~sity: 3 5 000 cp s ( 1 0 % aq . ) r Anion content: 2~65 gram ion/Kg polymer Slzin~agent (1~ nriched rosin size Sizepine E
Aluminurs~ sulfate (C): Solid aluminum sulfate i_~
I~iller (E~: Talc for paper making Stirring c(>nc3ition:

~ ach stirring by a propeller stirrer w~s carried out at 100 r. p. nl. for 30 scconc3~; aftc r each a(klition of each of components ~A3) (a3~) ((O (I~) (l ). r rhe amouslts of the components are SIIOW51 as perceIltagc s per dry pulp.

~liO`~19 C)r(l~r of adclition :Componcnts (E)~E33)~(D)~(C) ( E)~ju ( }3 3) t/o (D)~o (C)% Bursting factor 15 0. 1 1. 0 5. 0 1. 92 15 0.2 1.0 5.0 2.08 1 5 0. :~ 1 . 0 5 . 0 2 . 2 1 Table 10:(12eferes1ce) i Orcler of acldition: Components (E)~(B3) ~(D)~(A3) ~1;' ) % ~ O3 ~ 7 ( D ) % ( C 17 l~ 3~$ ~ r~t i~

0. 1 1 . 0 5. 0 0. 01 1. 98 .
1 5 0. 1 1 . 0 5. 0 0. 05 2. 05 0.1 1-0 5.0 ~.10 2.14 0.3 1.0 5.0 0.01 2.27 0.:~ 1.0 5.0 0.05 2.32 0. 3 1. 0 5. 0 0. 10 2. 40 Table ll:(Invention) ~ ' O :~
Or~1er of acklition: Co~nponents (E) ~(A3) >(B3)~(D)- (C) ~:
t`
(I~`)% (A3)% ( 13 )% ~1))% (C)% 13urstin~ factor lS 0.01 0.1 1.0 'j.0 2.15 0.05 0.1 1.~ 5 0 2.34 i.
0.10 0.1 1.0 5.0 2.58 0.01 0,3 1.0 5.0 2.4~3 1 5 0 . 05 0 . 3 1 . 0 5 . 0 Z . 6 0 F
1 5 0. 1 0 ~. 3 l . 0 5. 0 _ 2 . 77 ~'xanlple 5: ~
!s Tlle process of E~ample 1 was repeated ~snder the follow-ing conditions.

lilOOl~

Pul~ lixtur~ of I~UliP (Softwood unbreached kraft pu1p) and LU~;P
(Hardwood unbreached kraft pulp ~1:1) having CSF of 350 ml. i 13asis wcig~lt Or papcr: 60 g/m2 Watcr solublc cationic polymer (A4):
llon-opolymer c~f dinlcthykliallyl ammonium chloride:
~iscosity: 800 cps (10 % aq. ) Cation contcnt: 5. 9~ gram ion/Kg~ polymer Water soluble anionic polymer (B4):
I'arlially hyc3rolyzed product of polyacrylamide:
llydrolyzcd conlponcnt: 8 nole %
Viscosity: 11300 cps ( 10 01O aq. ) Anion content: 1.10 gram ion/Kg. polymer Aluminum sulfatc (C): Solid aluminum sulfate L
~tirring condition:

Each stirring by a propeller stirrer was carried out at 200 r. p. m. for 30 seconds after each addition of each of components (A4), (B4), (C). The amount of the components are shown as percentages per ~' dry pulp.

Table 12: ( Rc fe rcncc ~ ~-Ordcr of acldition: Con~ponents (134~(C~

'O

ll~VOl9 ~A4)ojo (134~`'J (C)% 13ursting factor 0 0.1 1.5 3.13 0 0.2 l.S 3.36 0 0. 3 1 . 5 3. 58 0 0. 4 1 . 5 3. 80 0 0.1 0 2.91 0 0.2 0 2.93 0 0.3 0 2.96 0 0.4 0 2 99 ~O
Table 13: (Reference) Order of ac~dition: Components (B4~(C)~(A4) ___ (A4)~J~o 1134)% (C)% 13ursting factor 0.01 0.2 1.5 3.39 0.03 0.2 1.5 3.46 0.06 0.2 1.5 3.55 0.1 0.2 1.5 3.63 0.01 0. ~ 1.5 3.61 0.0:~ 0.3 l.S 3.69 '`
0.06 0.3 1.5 3.76 0.1 0.3 1.5 3.75 0.01 0.2 O :~.00 0.03 0.2 0 3.07 0.06 0.2 O 3.15 ~,~
0.1 0.2 0 3.~3 0.01 0.~ 0 3.08 k 0.0~ 0.3 0 3.15 0.06 0.3 0 3.23 0.1 û.~ _ l 3.41 I
L

~o r 1110~19 I a ~ v~ i o ll ) Order of addition: Components (A4) )(~34)~(C) (~4)% (L~4)% (C)% ~ursting factor 0.01 0.2 1.5 3.45 0 03 0 2 1 5 ~.59 0 0~ 0 2 1.5 3 71 O I O 2 1.5 3.
0.01 0.:~ 1 5 3.67 0 03 0.3 1 5 3.79 O OG O .3 1.5 ;~ 90 O 1 0 :~ 1.5 4.02 1~ O 01 O 2 O ~ 13 0 0~ 0.2 O 3.35 006 02 O 3.58 0,01 0.3 O ~ 25 0 0;~ 0.3 O ~
0.06 0.~ O ~ ~9 O 1 O. ~ O ~.9~3 I~xample 6:

The process of Example 1 was repeated under the following conditions PulE~: Wasted corrugated board beaten to give CSF of 300 ml ,, l3asis wei~ht of paper: 70 g/m2 Water solul)le cationic polymer (A ) l~ulyetl~ylcnein~in~: ~
Viscosity: 8 cps (1~ % aq. ) r Cation contcnt 23.3 ~ram ion /Kg polymer Water soluble anionic polymer (135) Partially hydrolyzed product of polyacrylamide:
Anis)nic component: 15 mole %
Viscosity: 1200û c~ps ~10 % aq ) Anion contellt: 20 2 gran~ ion /Kg~ polymer Alunlinum sulfate (C): Solid aluminurn sulfate .
3Q ~;
~ti~-ling con(liLion:

Each stirring by a propeller stirrer was carried out at 200 r~p~ for 80 scconcIs after each addition of each of components (A5), (~35),(C). Thc amounts of the components are shown as percentages per dry pulp~ ¦

Table 15: (Reference) Order of addition: Con~poncnts (B5) ~(C) t (A .5) % __ (135)~/o-- ( C)%
0 0~3 0.5 1.83 0 0.4 0~5 1.90 0 0.5 0.5 1.98 0 0.3 l.S 1~95 0 0~4 1.5 2.08 0 0.5 1.5 2.20 Table 16: (Invcntion) t Orde r of addition: (A5) ~ ( B5) ~(C) :
A5)% (~5)% (C)% Bursting factor 0.03 0.3 0.5 1.92 0.06 0.3 0.5 2.04 0.1 0.3 0.5 2.19 0.03 0.4 0.5 2.01 0.06 0.~ 0.5 2.18 ~, 0.1 0.4 0.5 2.30 0.03 0.3 1.5 2.03 t 0.06 0.3 1.5 2.15 0.1 0.3 1.5 2.26 "
0.03 0.4 1.5 2.13 0.06 0.4 1.5 2.25 0.1 0.4 1.5 2.37 3 o Example 7:

The process of Example 1 was repeated under the following conditions.

lll~)Ql~

I'ulp~ lurc of wasted news-paper and wasted corrugated board (1 :1) beatcn to give CS~ of 220 ml.
13axis wei~llt of paper: 80 g/m2 Watcr solublc cationic polyme~ (A6 - 1):
Copolymer of 85 mole % of acrylamide con-ponent and 15 mole % of methacryloyloxy ethyl trimethyl ammonium chloride component.
~iscosity: 9700 cps (10 % ag) Cation contellt: 1. 64 gram ion/Kg- polymer Water solul~lc cationic polymer (A6-2):

Copolymer of 95 mole % of acrylamide component and 5 mole % of methacryloyloxy ethyl trimethyl ammonium chloride component.
Visco~ity: 9550 cps (10% aq. ) Cation content:0 643 gram ion/Kg- polymer W ate r solu~lc anionic polyme r ( E36 ):
Partially hydrolyzed product of polyacrylamide Anionic con-ponent: 15 mole %
Viscosity: 12000 cps (10 % aq. ) Anion cont~nt : 2. 02 gram ion/Kg- polymer Aluminum sulfate(C): Solid aluminum sulfate Stirring conditioll:

Each stirring ~y a propeller stirrer was carried out at t 200 r. p. m. for 30 seconds after each addition of each of components r (A6 -1) (A6-2) (13) (C). The amounts of the components are shown as E
percentages per dry pulp. &

Tal~le 17:(Reference): F

Ordcr of addition: Components (136~ (C) lu _ (( )% 13u rst ing factor 4 0. 3 15 l.G1 0.~ 15 1.69 0. 5 1 5 1 . 77 111~019 Tal)lc l~ nvcnlioll) Order of addition: Components (A~-l ) or ~A6 _ 2~(B6) ~(C~

G 1)% (13~)% (C)% Bursting factor 0. 01 0. '~ l . 5 1 . 65 0.03 0.3 1.5 1.73 0.06 0.:~ 1.5 `1.81 0. 1 0. 3 1. 5 1. 90 0.01 0.4 1.5 1.72 0.0:~ 0.4 1.5 1.80 o. 06 0. 4 1 . 5 1 . 89 0. 1 0. 4 1. 5 1. 97 (A6-1)% (~ "0 (C)% 13ursting factor 0.01 0.3 1.5 1.63 0.0:~ 0.3 1.5 1.6 0.0~ 0.3 1.5 1.73 0.1 0.3 1.5 1.76 0. 01 0. 6 1. 5 1 71 0.0:~ 0.6 1.5 1.76 0.06 0.6 1.5 1.81 0.1 0.6 1.5 1.86 Sincc lhc cation cc nlcnt of (A6-2) is lower than that of (A6 -1), the formc r give s lowc r effect .

Ex~mple 8:

The process of Example 1 was repeated under the following conditions.
~'ulp: LI~hl' having CSl' of 350 nll.
13asis wci~lt of papcl: 60 g/n12 Water soluble cationic pol~ner (A ) Quaternary ammonium compound of Mannich reaction product obtained by reacting polyacrylamide with forn~aldehyde and dimethyl-111~)Q...

amine th~n quaternized with dimethyl sulfate.
Amino component : 60 mole % to acrylamide component Quaternary component: 32 mole % to acrylamide component Viscosity : 4500 cps (10 % aq.) Cation content : 3.89 gram ion/Kg.polymer Water soluble anionic polyrner (B ) Copolynler of 10 mole % of acrylonitrile, 10 mole % of sodium acry-late, 80 mole % of acrylamide.
Viscosity : 2300 cps (10 % aq. ) Aluminum sulfate (C): Solid aluminum sulfate Stirring condition:

Each stirring by a propeller stirrer was carried out at 200 r. p. m. for 30 seconds after each addition of each of components (A7), (B7), (C). The amount of the components are shown as percen-tages per dry pulp.
Table 19 (Reference):
-Or~3er of ad(3ition: Components (B7) ~C) (B7)% (C)% Bursting factor 0 0.3 1.5 2.16 0 0.5 1.5 2.34 t 0 1 . 0 1 . 5 2. 53 I, Table 20: (Invention Orc~er of a(~clition: Components (A7)~(B7)~(C) (A7)% __ (C)% 13ursting factor r 0. 0:~ O. 1 1. 5 2. 30 0.06 0.1 1.5 2.42 Q. 1 0. 1 1 . 5 2. 54 ,~

0.03 0.3 l.5 2.51 0.06 0.3 1.5 2.67 F
0.1 0.3 1.5 2.79 0.03 0.5 1.5 2.61 ~0019 ~ I `.'-) 1 1.5 1 2.80 0.1 1 0.5 1 1.5 1 3.01 E

Example 9~

Thc process of Example I was repeated under the following conàitions.
Pulp: I~.lixturc of LBKP and SCP (~mi--chemical pulp) having CSF of 280 ml 13asis weight of paper: 55 g/m2 10 Water solul~le cationic polymer (A8 -1):
l~omopolymer of dimctllyl diallyl ammonium chloride Viscosity: 30 cps (10 % aq. ) i Cation contcnt: 5, 99 gram ion/Kg- polymer Water solut~le calionic polymer (A -2):
Copolymer of 20 mole % of dimethyl diallyl ammoniu n chloride compo- t nent and 80 mole % of acrylamide component.
Viscosity; ~3 cps (10 % aq. ) Cation content: 2.21 gram ion/Kg,polymer r Water soluble cationic polymer (A8 3) ~, Copolymer of 20 mole % of dimethyl diallyl ammonium chloride compo-nent and 80 mole % of acrylamide component. t Viscosity: 350 cps (10% aq. ) ~, Cation content: 2. 21 gram ion/Kg polymer ~1ater soluble anionic polymer (B~

Partially hydroly~.ed product of polyacrylamide r Anionic component : 10 mole % F
Viscosity 13500 cps (10 % aq. ) Anion content :1. 37 gram ion/Kg polymer Aluminium sulfate ((~): Solid aluminum sulfate ~tirrmg con~3ili:>n: F
l,ach slirring by a propeller stirrer was carried out at 200 r.p.m. for ~0 seconds after each addition of each of components -- 2 3 ~

(A~ 3-2), (A~ -3), ( 13~), (C).
The an~ounts of Lhe components are shown as percentages per dry pulp.
Table 21(1~efcrencc):
Ordcr of at~clitiorl: Componcnts (n8) >(C):
(A8 1) (A~3 - 3 ) ~0 ( ~3 )% (C)% Bursting factor 0 0.2 1.5 1.83 0 0.4 1.5 2.14 0 0. 6 _ 1 . 5 2, 46 Ta~)le 22:(Invention) ()rt3cr of A~ltlition: (A~3-l),(A -2),(A -3)~(B8)~(C):
.
(A~3-1)% (B8)% (C)% Bursting factor 0.03 0.2 1.5 1.98 0.06 0.2 1.5 2.16 0.1 0.2 1.5 2.30 p 0.03 0.4 1.5 2.28 0.06 0.4 1.5 2.45 r-O . 1 0. 4 1 . 5 2 . 60 1,`
~0 (A8 2)% (B8)o10 (C)% Bursting ~actor r o.03 0.2 1.5 1.90 0 06 Q.2 1.5 1.96 i~
0. 1 0. 2 1 . 5 2. 01 r, 0.03 0.4 1.5 2.21 0.06 0.4 1.5 2.27 0. 1 0. 4 1. 5 2. 32 (A -3)/)!o (B~)% (C)% Bursting factor ; g 0.03 0.2 1.5 1.97 0.06 Q.2 1.5 2.14 0. 1 0. 2 1. 5 2. 28 a , 0 0 . 03 0 . 4 1 . 5 2 . 25 0 1~ 0 4 1 5 2 57 _ 1' ;

l~Wl9 Since ~l~c cation conte~lt of (A8-2j is lower than that ot ( A8-10 t}le el`fect of strengthening is inferior~
Since the viscosity of (A~-3) is higher though the cation contcnts of (A8-2) and (A8-3) are the same, the effect of strengthening is superior.

I~xample 1 0:

A water soluble cationic polymer (A9), a water soluble anionic polymer (B ), a sizing agent (D~, aluminum sulfate (C) were sequentially added to 0. 5 % of pulp slurry of LBKP beaten to give CSF of 400 ml. in the order. The resulting pulp slurry was treated by TAPPl Standard Sheet Machine to make a paper having a basis weight of 50 g/m2. ~, The bursting factor of the paper was measured. The results are shown in Table 25. r As the reference, the cationic polymer (A9) was not used, or the order of addition was changed and the bursting factor of the paper was measured. The results are shown in Tables 23 and 24. L
The following components were used.
Water soluble cationic polymer (A9):

Mannich compound of polyacrylamide Cationic component : 50 mole %
Viscosity: 15,000 cps (10 % aq. ) Watcr soluble anionic polymer (13 ) Partially hy~lrolyzed product o polyacrylamide Hydrolyzed component: 11. 3 mole %
Viscosity: 7, 700 cps (10 % aq. ) Aluminun- sulfate (C): Solid aluminum sulfate b _, ~
Sizing agcnt(r)): Enriched rosin r The amounts of the components are shown as percentages per dry pulp.
St irring condition:

Each stirring hy a propeller stirrer was carried out at 20G
r. p. m for 30 secs~nc3s after each addition of each of components (A9), (~3'3), (C), (1~).

1~10019 T ~ 2 ~ r~

Order of .a(ldition: ('omponcnts (B9) ~(D) ~ (C) (A9)% (B9)% (D)% (C)% ~3ursting factor 0 0.1 1.0 2.0 3.31 0 0. 15 1. 0 2. 0 3. 58 0 0.2 1.0 -2.0 3.79 O O. :~ 1. 0 2. 0 4. 02 Tablc 24~ cfercncc) Ordcr of ac3dition: Componcnts (D)~(E39)~(C)~(A9) E

(L))~lu (T3 )% (C)% (A )% Bursting factor 1 . 0 0. 15 2. 0 0. 03 3. 60 1.0 0.15 2.0 0.06 3.64 l . 0 0. 15 2. 0 0. 1 3. 70 Tablc 25:(1nvention) Ordcr of additiol1: Components (A9)~(B9)~(D)~(C): .
_ ~
(A )% ( B )% (I))% (C)% E3urstin factor -- __ g 0,~3 0. 1 1.0 2.0 3.61 ;-0.15 0.l 1.0 ~.0 3.43 '' 0. 06 0.1 1. 0 2. 0 3. 81 r 0. 1 0. 1 1 . 0 2. 0 4. 05 ().03 0.15 1.0 2.0 3.94 0.06 0.15 1.0 2.0 4.18 0.1 0.15 l.0 _ 2.0 4.43 _ Note: The ion equivalent of A9 to I39 is 50 % in the casc of A = 0. 015%
ancl 139 = 0.1"~

xamplc 11:

The proccss of Examp1e 10 was repeated under the follow- -ing conditions. The rcsulas arc shown in Tablcs 26 to 28.

~1~0019 Watcr soll~>lc cationic polylllcr (~10) Copolymer of 70 molc ~0 of acrylamide component and 30 mole % of dime- !
thylanlino etllyl methacrylate component Viscosity : 53, 000 cps (10% aq. ) Watcr solublc anionic polymcr ~ ):
Parlially hydrolyzec3 product of polyacrylamide llydrolyzed component: 20 mole %
Vi~cosity: 12, 500 cps (10 % aq. ) Alwninum sulfate (C): ~olid aluminum sulfate L ;:J
Sizing agent (D): L,nriched rosin Tal~le 26;(1~cference) Or~cr of adc3ition: Components (D)~(B10) ~C)~(A

(D)% (B10)% (C)% (A 10)% Bursting factor 1 . 0 0. 2 2. 0 0. 03 3. 71 1.0 0.2 2.0 0.06 3.77 - 1. 0 0. 2 2. 0 0. 1 3. 80 Tal~le 27'(I~eferencc) Or(3er of a(l(~ition: C~mponcnt~ (1310)~(D)~(C) (~1û)% (B10)% (C)% (D)% Bursting facto~r (~ 0.1 1.0 2.0 3.g5 0 0.2 1.0 2.0 3.67 0 0. 3 1. 0 _ 2. 0 3. 86 Table 28:(1nvention) Orcler of aclc~ition: Con-pon~nts ~A10) ~ (B10) ~(D)~(C) (A 10)% ( l~l O)~o (D)% (C)% Bursting factor 0.0:3 0.1 1.0 2.0 3.71 0.0~ 0.1 1.0 2.0 3.83 ~1~19 0~1 0.1 1.0 2.0 4.13 0.03 0.2 1.0 2.0 3.88 0.06 0.2 1.0 2.0 4.09 0. 1 0. 2 1. 0 2. 0 4. 33 Note: The ion equivalcnt of (A10) to ~B10) is 35 % in the case of Al = - 03 % ancl 1~1 = 0.1 %.

Example 12:

The process of Example 10 was repeated under the follow-L0 itlg conditions and the relative bursting strength was measured, by Japanese Industrial Standard. t Water soluble cationic polymer (All):

The rcaction product of epichlorohydrin. dimethylamine and hexa-methylene diamine Viscosity: 12 cps. (10% aq. ) Water soluble anionic polymer (B11):
Copolymer of 85 mole % of acrylamide component and 15 mole % of sodium acrylate component Viscosity: 6. 300 cps (10% aq. ) Sizin~ agcnt (C): 13nriched rosin Aluminum ~ulfate (1)): Solid aluminum sulfate !

Tal)le 29' (~eference) ()rdcr of adc3ition: Components (D)~(Bll)~(C)~(All) I

(D)% (L~11)% (C)%(A11)% ~urstin factor g 1`
1.0 0.2 2.0 0.06 3.66 1.0 0.2 _ 2.0 0.09 3.70 Tablc 30 !~) Ordcr of acl(litioll: Components (A~ ) ~(D)~(C) ~0019 (A11)% 11 (D)% ((~)% Bursling factor 0 0.1 l.C 2.0 3.40 0 0.2 1.0 2.0 3.62 0 0.3 1.0 2.0 3.85 0. 03 0. 15 1. 0 2. 0 3. 83 0. 0~ 0. 1 5 1 . 0 2 . 0 3. 98 Note: T lC ion equivalen of (~11) to ( 311) in the c lse of A =0. 03 %
an~ 1:3=0.15%.

2 0 f L
i~ F

Claims (14)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for manufacturing paper having improved dry strength which comprises mixing an essentially alum free pulp slurry with a water soluble cationic polymer, subsequently adding a water soluble anionic polymer to the essentially alum free slurry and then making the paper from the composition obtained.
2. A process according to Claim 1 wherein the water soluble cationic polymer has a viscosity of greater than about 5 cps. as a 10% aqueous solution at 25°C.
3. A process according to Claim 2 wherein the water soluble cationic polymer has a viscosity of greater than about 100 cps. as a 10% aqueous solution at 25°C and a cation content of greater than about 1.0 gram ion/Kg. polymer.
4. A process according to Claim 2 wherein the water soluble cationic polymer has a viscosity in a range of 5 up to 100 cps. as a 10% aqueous solution at 25°C and a cation content of greater than about 3.0 gram ion/Kg. polymer.
5. A process according to Claim 1, 2 or 3 wherein the amount of the water soluble cationic polymer is more than about 0.01% by weight to the dry pulp.
6. A process according to Claim 1, 2 or 3 wherein the amount of the water soluble anionic polymer is more than about 0.1% by weight to the dry pulp.
7. A process according to Claim 1, 2 or 3 wherein the ratio of the water soluble cationic polymer to the water soluble anionic polymer is more than about 10 mole % as ion equivalent.
8. A process according to Claim 1, 2 or 3 wherein the water soluble cationic polymer is selected from the group con-sisting of homopolymers and copolymers of dimethyl diallyl ammonium chloride and polyethyleneimine.
9. A process according to Claim 1, 2 or 3 wherein the water soluble cationic polymer is a polyacrylamide partial Mannich reaction product produced by reacting polyacrylamide with formaldehyde and dimethylamine and a quaternary ammonium salt thereof.
10. A process according to Claim 1, 2 or 3 wherein the water soluble cationic polymer is a copolymer of acrylamide and an acrylate or methacrylate having the formula wherein R represents hydrogen atom or methyl group; R1 and R2 are the same or different and represent an alkyl group, and Y
represents an alkylene group having 2 or more of carbom atoms or hydroxyalkylene group having 2 or more of carbon atoms; or a quaternary ammonium salt of said copolymer.
11. A process according to Claim 1, 2 or 3 wherein the water soluble cationic polymer is a polycondensate of an epihalohydrin and at least one of monoamines, polyamines, amide amines and polyamide amines.
12. A process according to Claim 1, 2 or 3 wherein the water soluble cationic polymer is a polycondensate of epichloro-hydrin and ethylenediamine or a polycondensate of epichlorohydrin, dimethylamine and pentaethylenehexamine.
13. A process according to Claim 1, 2 or 3 wherein the water soluble anionic polymer is a polyacrylamide partially hydrolyzed product or copolymer of acrylamide and acrylic acid.
14. A process according to Claim 1, 2 or 3 in which alum is added after the addition of the water soluble anionic polymers thereby improving the retention of the cationic and anionic polymers in the pulp.
CA 302830 1978-04-24 1978-05-08 Process for manufacturing paper having improved dry strength Expired CA1110019A (en)

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US4795531A (en) * 1987-09-22 1989-01-03 Nalco Chemical Company Method for dewatering paper
US4808267A (en) * 1986-03-03 1989-02-28 Felix Schoeller, Jr. Gmbh & Co. Kg Waterproof photographic paper support
EP0337310A1 (en) * 1988-04-15 1989-10-18 Air Products And Chemicals, Inc. Poly(vinyl alcohol-vinylamine)copolymers for improved moist compressive strength of paper products
US5098520A (en) * 1991-01-25 1992-03-24 Nalco Chemcial Company Papermaking process with improved retention and drainage
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US5185062A (en) * 1991-01-25 1993-02-09 Nalco Chemical Company Papermaking process with improved retention and drainage
US5338406A (en) * 1988-10-03 1994-08-16 Hercules Incorporated Dry strength additive for paper
US5350796A (en) * 1991-05-03 1994-09-27 Henkel Corporation Wet strength resin composition
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US5633300A (en) * 1991-12-23 1997-05-27 Hercules Incorporated Enhancement of paper dry strength by anionic and cationic guar combination
US5744001A (en) * 1993-03-03 1998-04-28 Basf Aktiengesellschaft Aqueous pigment slurries for production of filler-containing paper
WO1999005361A1 (en) * 1997-07-25 1999-02-04 Hercules Incorporated Dry strength additive for paper
US6228217B1 (en) 1995-01-13 2001-05-08 Hercules Incorporated Strength of paper made from pulp containing surface active, carboxyl compounds
EP1285993A1 (en) * 2001-08-20 2003-02-26 Armstrong World Industries, Inc. Fibrous sheet binders
WO2009138457A1 (en) * 2008-05-15 2009-11-19 Basf Se Method for producing paper, paperboard and cardboard with a high dry strength
US7922867B2 (en) 2006-03-16 2011-04-12 Basf Se Method for producing paper, paperboard and cardboard having high dry strength
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Cited By (26)

* Cited by examiner, † Cited by third party
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EP0193111A3 (en) * 1985-02-27 1987-05-20 Basf Aktiengesellschaft Process for producing paper with a high dry strength
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