JP3487706B2 - Papermaking method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking method, and more particularly, to a papermaking method in which a sizing effect is improved by adding a specific polymer when sizing paper with a rosin-based sizing agent.

[0002]

Alkyl ketene dimers (hereinafter referred to as A) are the most widely used sizing agents for neutral papermaking at present.
KD) and alkenyl succinic anhydride (hereinafter A
SA is abbreviated). However, each of these neutral sizing agents has problems. Although ASA can be easily synthesized as a derivative of petroleum products and is available in large amounts as a raw material, it is easily decomposed when it comes into contact with water. It is added to the slurry. The emulsified particles not adsorbed on the papermaking raw material decompose and flow out into white water. The recovered emulsified particles in white water gradually aggregate to cause pitch trouble, or even adsorbed to the raw material does not contribute to the size effect. On the other hand, since AKD is derived from animal fats and oils, it is also limited in terms of raw material. Even if it is adsorbed by a papermaking raw material and stays in papermaking, it does not exhibit a size effect immediately after drying, and is applied on-machine. There are drawbacks such as the fact that it cannot be used as a base paper and that the friction coefficient of the paper is reduced, so that the papers are slippery.

Under such circumstances, a neutral rosin sizing agent (hereinafter abbreviated as neutral rosin) has been developed and gradually spread. However, there are problems with neutral rosin. Since the surface charge is anionic, it reduces the aggregation ability of the filler retention improver added later. To deal with this point, a method of adding a large amount of cation-modified starch to neutralize the surface charge of the neutral rosin is generally used. However, cation-modified starch has a low cationic charge density, so a large amount must be added.
After all, the effectiveness of the retention agent is reduced. If the retention rate is not improved, the retention rate of the size particles adsorbed on the pulp or the fine fibers is not improved and the size effect is not improved.

For the purpose of improving this formulation, a formulation in which a part of the cation-modified starch is replaced with a synthetic low-molecular weight cationic polymer is considered and is applied to AKD (Japanese Patent Laid-Open No. 55-12868). , Not yet applied to neutral rosin. Further, a method of adding sol-like aluminum hydroxide in the neutral and alkaline pH range for fixing the rosin-based sizing agent (JP-A-1-239198),
Alternatively, a method of adding basic polyaluminum sulfate (JP-A-6-17398) or a method of adding calcium carbonate surface-treated with a cationic water-soluble polymer as a filler when a neutral rosin is used (JP-A-6- 92007
However, the present situation is that a formulation capable of expressing a sufficient size has not yet been developed.

[0005]

The rosin-based sizing agent is generally anionic, but in acid papermaking, a large amount of a sulfuric acid band is added, and as a result, the papermaking system becomes acidic. Therefore, there are relatively few factors that hinder the function of the retention aid. However, in neutral and alkaline papermaking, in addition to rosin-based sizing agents, the influence of various anionic substances produced in the process of manufacturing pulp and waste paper is far greater than that in acidic papermaking. As a cationic polymer for controlling the surface charge, a polyamine-epichlorohydrin reaction product is often cited, but the degree of polymerization is not sufficient, and the low molecular weight component produced due to the condensate adversely affects the papermaking system. give. If too much cationically modified starch is added for the purpose of neutralizing the surface charge of the rosin-based sizing agent, the effect of the retention agent added later is reduced. It is presumed that the reason for this is that as a result of adding a large amount, the adsorption sites of the retention agent decrease on the particle surface. Therefore, an object of the present invention is to provide a method for fixing a rosin-based sizing agent that has less influence on the total yield rate on the wire as compared with the conventional fixing method for a rosin-based sizing agent.

[0006]

Means for Solving the Problems The contents of the invention will be described in detail below. The invention of claim 1 uses a rosin-based sizing agent as a raw material for papermaking
When added to the rally and sized , a plurality of kinds of the papermaking raw material slurry containing a monomer represented by the following formula (1) and / or a cationic monomer composed of a dimethyldiallylammonium salt as an essential component A method of making paper, characterized in that a polymer consisting of the above monomer is divided and added twice, and a shearing force is applied to the papermaking raw material slurry during each addition.

[Chemical 1] (Wherein A is O or NH; B is C2 H4, C
3 H6, C3 H5 OH; R1 is H or CH3; R2 and R3 are C1-4 alkyl groups; R4 is H, C1-4 alkyl groups or benzyl groups. ) The intrinsic viscosity of the invention the polymer of claim 2 [η] (1 25 ° C.
It is characterized in that the limiting viscosity number in N saline is 7 or more. The invention of claim 3 wherein the cationic monomer structural units in the polymer is 10 to 50 mole% residual monomeric structural units, characterized in that the acrylamide. The invention of claim 4 is characterized in that the papermaking pH is in the range of 6.0 to 9.0. The invention of claim 5 is a papermaking raw material slurry.
Characterized in that it contains calcium carbonate as a filler in the. Invention aluminum sulfate in paper stock slurry of claim 6, after adding and mixing a rosin-based sizing agent, characterized by adding further dividing the <br/> polymer. Claim 7
The invention, relative to the polymer addition amount is paper stock solids of which added in portions to the papermaking slurry, the first time is 0.01 to 0.05 wt%, the second time 0. 00
It is characterized by being 5 to 0.03% by weight.

In the present invention, the cationic polymer is added to the papermaking raw material slurry in two divided portions. A possible first addition location is before the fan pump where white water is mixed with the papermaking raw material slurry and diluted to the papermaking concentration. In this case, if the polymer is added at a point closer to the front, for example, in a machine chest, the flocs generated by the addition of the polymer will be over-sheared and the flocs will be destroyed too much. If too much share is applied in the first addition, the state of aggregation during the second addition is also affected, which is not preferable. The first addition of the polymer causes the formation of flocs, and the shear of the papermaking system thereafter breaks the flocs to a proper aggregation state. Then a second addition of polymer is made. Possible points of addition are before and after the screen.

Next, the relationship of the addition order with the rosin-based sizing agent will be described. The current neutral rosin size is susceptible to hydrolysis. Therefore, it is generally established that the addition should be made as close to the paper machine as possible.
Therefore, the neutral rosin may be added between the machine chest and the fan pump or between the fan pump and the screen. In this case, the places where the polymer used in the present invention may be added are as follows. First, there are two cases of adding the polymer prior to the addition of the neutral rosin or after adding the neutral rosin, but preferably after adding the neutral rosin, the polymer used in the present invention is added. Added.

The reason for this is that cation-modified starch is added by a machine chest or the like, and then neutral rosin is added to partially neutralize the surface charge. After this, a polymer is added, a part of the surface charge is neutralized, and flocs are generated. In this case, if the polymer is added first, aggregation will occur, but neutral rosin neutralization will be less likely. Since the polymer used in the present invention has a high molecular weight, it aggregates the papermaking raw material, but has a weak surface charge neutralizing effect. Therefore, the neutralization of the surface charge of the neutral rosin taken into the flocs is unlikely to occur. Therefore, it is preferable that the neutral rosin is added prior to the first addition of the polymer, and it is considered that the place of addition is preferably between the machine chest and the fan pump.

Next, the location of the second addition of the polymer will be described. The flocs produced by the first addition of polymer need to be destroyed by the shear of the papermaking system. The reason for this is that it is mixed by shearing, the neutralization of the neutral rosin is carried out as a complementary charge, and that the paper is prevented from being formed into a floc formation. Therefore, the second addition needs to be performed after the fan pump, which may be before or after the screen. The superiority or inferiority of the two should be decided according to the situation at the papermaking site.

From the above description, it is understood that the papermaking method of the present invention has two advantages. In other words, one is that the cationic charge does not become excessive and the retention rate of the papermaking system does not decrease, and the other is that the high molecular weight retention agent is added twice, so problems such as formation slippage occur. It is difficult to occur. It is expected that the retention rate will be improved if the amount of the high molecular weight retention agent added is increased to a certain degree, but at the same time, the risk of formation failure increases.
The papermaking method of the present invention can prevent this point.

Next, the polymer used in the present invention will be described. The polymer has a high molecular weight with an intrinsic viscosity of 7 or more.
For this reason, high molecular weight polymers primarily agglomerate the suspension by cross-linking adsorption, but partially neutralize the surface charge of the suspension. This complements the cation-modified starch and also prevents excess cation in the papermaking system. That is, it is significant that the polymer used in the present invention contains a small amount of a polymer having a relatively low cationic charge density. Therefore, if the intrinsic viscosity is less than 7, the effect is poor and it cannot be used.
From the above reasons, the copolymerization rate of the cationic monomer contained in the polymer is preferably 10 mol% to 7%.
It is 0 mol%, more preferably 10 mol% to 50 mol%. Specific examples of the monomer represented by the formula (1) include tertiary salts such as dimethylaminoethyl (meth) acrylate and acrylamido-3-dimethylaminopropyl, or 4 salts such as methyl chloride, ethyl chloride and benzyl chloride. Examples include grade reaction products. Further, as nonionic monomers other than acrylamide, acrylonitrile, N-vinylpyrrolidone, vinyl acetate, methyl acrylate and the like can be mentioned as copolymerizable monomers.

As a method for polymerizing the polymer, an aqueous solution of 10 to 50% by weight is adjusted to a pH of 3.0 to 4.0, and then an aqueous solution polymerization, a dispersion polymerization, a reverse phase emulsion polymerization or a pearl is carried out by a radical polymerization initiator. Polymerization is possible, and photopolymerization with addition of a sensitizer is also possible, and the polymerization method is not particularly limited.

Next, the addition rate of the polymer will be described. The polymer used in the present invention is added in two divided portions before the points where the two share points in the papermaking system are applied. The first and second addition ratios are arbitrarily selected according to the situation of the papermaking system. For example, the first addition rate is preferably 0.002% to 0.2%, more preferably 0.005% to 0.1%, and most preferably 0.01% to the papermaking raw material.
It is 0.05%. In addition, the second addition rate is 0.
003% -0.1%, preferably 0.005% -0.
1%, most preferably 0.005% to 0.03%
Is.

Next, the rosin-based sizing agent targeted by the papermaking method of the present invention will be described. The most economical effect is obtained when neutral rosin is used as the rosin-based sizing agent.
In acid papermaking, a large amount of sulfuric acid band is added, so that the effect of the rosin-based sizing agent is very good as compared with neutral to weakly alkaline. At present, there are various types of neutral rosin that exhibit a size effect at a pH lower than around pH 7 and up to around pH 9, but it is more economically advantageous to use it in weak alkaline papermaking in the presence of calcium carbonate. Sizing around pH 6 mainly composed of kaolin and talc is relatively easy as compared with sizing around pH 8 mainly composed of calcium carbonate, and the size effect is easily exhibited even without an auxiliary agent. Therefore, the merit of the present invention is reduced.

To further explain the addition amount of the sulfuric acid band, at present, about 1% is added for neutral to weakly alkaline papermaking, and about 1.5 to 2% is added for papermaking at pH around 7. When the papermaking method of the present invention is applied, the retention rate of the rosin-based sizing agent is improved, so that a slight amount of sulfuric acid band is reduced and alkalinization can be achieved. For example, in neutral to weak alkaline papermaking, 1% is 0.
8% to 0.9%, and 2% is 1.3% for paper making at pH around 7.
It will be 1.8%.

Since the sizing effect is improved by the fixing method of the present invention, the amount of rosin-based sizing agent added can be reduced.
For example, the current 0.4% usage can be reduced to 0.35% and 0.35% can be reduced to 0.3%. Even if the amount of the fixing agent added is 0.02%, for example, since the amount is small, the cost increase due to the fixing agent is less than the reduction amount of the rosin cost, which is economically sufficient.

The polymer used in the present invention is a dye, pigment or defoaming agent, not to mention general papermaking additives such as paper strengthening agent, cation-modified starch, sulfuric acid band, calcium carbonate, kaolin and talc. Coexistence with slime control agents, retention aids, and other fillers such as titanium dioxide, white carbon, fine powder silica, etc. is not a problem.

[0019]

EXAMPLES The contents of the present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these contents as long as the gist thereof is not exceeded.

[Production Examples of Polymers Used in the Present Invention] Table 1
The monomer having the composition described in 1) is dissolved in ion-exchanged water so as to have the concentration described in Table 1, and the pH of the solution is set to 3.5. The monomer aqueous solution is kept at 40 ° C. and nitrogen gas is flowed for 30 minutes to remove oxygen in the solution. Then, 2,2'azobisamidinopropane dihydrochloride (V50) per pair to unit weight
Are added at the indicated mole fractions and maintained at 40 ° C. for 20 hours while flowing nitrogen gas to polymerize. Thereafter, each solution was put into acetone to precipitate a polymer, and then dried under reduced pressure to obtain a corresponding polymer. These solutions were prepared in 4% saline solution at concentrations of 0.1, 0.05, 0.01, and 0.005%, and their reduced viscosities were measured at 25 ° C. using an Ostwald viscometer. The intrinsic viscosity [η] was estimated by extrapolating to. Table 1 shows the measurement results of the mole fraction of each copolymer, the amount of V50 added, and the intrinsic viscosity.

[Table-1]

[Examples 1 to 22] Hardwood kraft pulp (LBKP) was beaten to CSF-400 ml to a concentration of 0.8.
Adjust to 75%. After collecting 500 ml of this dispersion and introducing it into a brit type dynamic jar, light calcium carbonate, cation-modified starch, sulfuric acid band, neutral rosin NT-80 (manufactured by Arakawa Chemical Co., Ltd.), a polymer used in the present invention (trial No. 2) No. 12) was added at the addition amount shown in the bottom of Table 2 at 10-second intervals by stirring at 800 rpm, and the first polymer was added after the above chemical addition and then 3
The mixture was stirred for 0 second, and then added for the second time, and 15 seconds after the addition of the polymer, the paper stock remaining on the wire was collected by filtering with a 20-mesh wire, and the basis weight 60 g /
The m ² paper was made with a Tappy Standard handmade paper machine. Each paper is sandwiched between three filter papers, 5 kg / cm
^It was pressed twice under the condition of 2.5 minutes. After that, it was dried by a rotary drum dryer at 100 ° C. for 1.5 minutes,
After adjusting for 18 hours in a thermo-hygrostat at RH and 20 ° C., the sizing degree was measured by the Steckigt method (JIS8122). The above results are summarized in Table 2.

[Table-2]

[Comparative Examples 1 to 20]
Trial production No. 1 and No. 13 and trial production No. 1 to 6 and trial production No. in the case of adding the polymer at a time without dividing
12 and 13 were tested. The above results are summarized in Table 3.

[Table-3]

[Examples 23 to 44] In the same manner as in Examples 1 to 22, the filler was set to a mixing ratio of kaolin and talc of 1: 1 and the neutral rosin was changed to CC-164 (manufactured by Japan PMC), and trial production was carried out. No. 2 to 12 were tested. The results are summarized in Table 4.

[Table-4]

[Comparative Examples 21 to 40] In the same manner as in Examples 23 to 44, trial Nos. 1 and 13 and trial Nos. 1 to 6 and trial Nos. 12 and 13 were tested in the case where the polymer was added at one time without being divided. . The above results are summarized in Table 5.

[Table-5]

[0025]

When the papermaking method of the present invention is applied, the sizing effect is improved if the addition amount of the sizing agent is the same. Therefore, since the amount of the sizing agent added can be reduced, the papermaking cost and pitch troubles can be reduced, which greatly contributes to the papermaking industry.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (7)

(57) [Claims] 1. A rosin-based sizing agent in a papermaking raw material slurry.
When added to and sized, the polymer represented by the following formula (1) and / or a polymer composed of plural kinds of monomers containing a cationic monomer composed of dimethyldiallylammonium salt as an essential component Is divided into two parts and added, and a shearing force is applied to the papermaking raw material slurry between the additions. [Chemical 1] (Wherein A is O or NH; B is C2 H4, C
3 H6, C3 H5 OH; R1 is H or CH3; R2 and R3 are C1-4 alkyl groups; R4 is H, C1-4 alkyl groups or benzyl groups. ) 2. The papermaking method according to claim 1, wherein the polymer has an intrinsic viscosity [η] (intrinsic viscosity number in 1N saline solution at 25 ° C.) of 7 or more. Wherein the claim 1 or請polymer in cationic monomer structural units is 10 to 50 mole% residual monomeric structural units, characterized in that acrylamide <br/> The papermaking method according to claim 2. 4. The papermaking method according to claim 1 , wherein the papermaking pH is in the range of 6.0 to 9.0. 5. The papermaking method according to claim 1 , wherein calcium carbonate is contained as a filler in the papermaking raw material slurry . 6. The papermaking method according to claim 1 , wherein a sulfuric acid band and a rosin-based sizing agent are added to and mixed with the papermaking raw material slurry, and then the polymer is dividedly added. 7. Before the divided and added to the papermaking raw material slurry
Against serial polymer amount added paper stock solid matter, the first time is 0.01 to 0.05 wt%, the second time 0.0
05 to 0.03 claim 1, wherein the percentages by weight
The papermaking method described in.