JP3508967B2 - Size processing 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 sizing method, and more specifically, in producing a papermaking raw material slurry containing a ketene dimer sizing agent, a (co) polymer of dimethyldi (meth) allyl ammonium salt. The present invention relates to a size treatment method in which the rise of size is accelerated after drying in the dryer part by using together.

[0002]

The most widely used sizing agent for neutral papermaking is the ketene dimer sizing agent (hereinafter referred to as A).
(Abbreviated as KD). Since AKD can be stored for a certain period of time even when prepared as an emulsion dispersion, it is easier to handle and has a stable size effect compared to alkenyl succinic anhydride sizing agents. However, the biggest problem of AKD is that the size effect is not fully exhibited immediately after drying in the dryer part, which is an obstacle when it is further processed as a coated base paper. In order to improve this point, the secondary diallylamine-based polymer is contained to accelerate the onset of the size effect.
A method for producing a KD dispersion has been filed (Japanese Patent Laid-Open No. 6-29).
9494). However, AKD is a sizing agent for neutral papermaking, and the pH of a papermaking system using calcium carbonate as a filler is as high as 7.5 to 8.2, dissociation of secondary amine is suppressed, and its effect is far insufficient. Is. Also A
There is already a formulation in which a polydiallylammonium salt polymer and a dicyandiamide-formalin condensate are used together for the purpose of improving the KD size effect (Japanese Patent Publication No. 3-164).
37). However, this is because no improvement in the size effect is observed unless one of the dicyandiamide-formalin condensate and the polydiallylammonium salt polymer is added.
No mention is made of the onset of the size effect.
The most important reason considered to be that the effect is not sufficiently expressed unless it is used together with the dicyandiamide-formalin condensate is that the dimethyldi (meth) allylammonium salt polymer has a low intrinsic viscosity and the effect is insufficient.

[0003]

The ketene dimer sizing agent exhibits a stable sizing effect in neutral and alkaline papermaking and is sufficiently practical, but the size rise is slow immediately after drying in the dryer part and It is a major obstacle to processing. Therefore, it goes without saying that if this point is improved, it will lead to a great improvement in productivity in the paper manufacturing industry.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that when making a papermaking raw material containing AKD , ketene dimer size
Each of the (co) polymers of cation-modified starch and dimethyldi (meth) allyl ammonium salt is added prior to the addition of the agent.
The present invention was found by discovering that papers having a rapid onset of the size effect can be produced by adding them in this order .

Although the reason for this is not yet clear, it is speculated that the addition of the dimethyldi (meth) allylammonium salt (co) polymer used in the present invention accelerates the sizing reaction of AKD. AKD is an alkylketene dimer, but with this composition as it is, the size effect is not exhibited even when adsorbed to pulp. The theory that sizing is completed only when this is decomposed into another substance is influential. That is, to promote this decomposition reaction (co)
It can be considered that the polymer works. Another possibility is that the AKD fixing rate is improved. That is, various anionic substances present in the papermaking system are electrically neutralized to adjust the charge on the surface of AKD particles to an appropriate value.

The (co) polymer of dimethyldi (meth) allyl ammonium salt used in the present invention can be easily produced by radical polymerization. That is 10 to 5 by weight percent
After being adjusted to 0%, aqueous solution polymerization, dispersion polymerization, reverse phase emulsion polymerization pearl polymerization, etc. are possible with a radical polymerization initiator, and photopolymerization with addition of a sensitizer is also possible, and the polymerization method is not particularly limited. . Further, examples of the nonionic monomer copolymerized with the dimethyldi (meth) allyl ammonium salt include acrylamide, acrylonitrile, N-vinylpyrrolidone, vinyl acetate, alkyl acrylate, N-vinylcarboxylic acid amide and the like. The copolymerization ratio of these nonionic monomers in all monomers is preferably in the range of 0 to 50 mol%, more preferably 0 to 20 mol%. When the copolymerization ratio of the dimethyldi (meth) allyl ammonium salt is 50 mol% or less, the cationic charge density is lowered and the functions are deteriorated, and the rise of the size effect is not promoted. Further, it is essential that the polymer of the present invention has an intrinsic viscosity [η] of 0.6 dl / g or more in 1N saline solution at 25 ° C. If it is less than this, the effect decreases.

Next, the place where the polymer is added will be described. Machine chests are the primary candidates for polymer additions. In machine chest, general additives for papermaking such as paper strengthening agent, cation modified starch, sulfuric acid band, calcium carbonate, kaolin, talc, titanium dioxide, white carbon, fine powder silica, dye, pigment, defoaming agent, slime control. Agents and the like are added. In addition, AKD is often added in this machine chest, but AKD is added before the (co) polymer of dimethyldi (meth) allyl ammonium salt.
When KD is added, the paper-making anionic substance and the like react with AKD, and the effect of adding the (co) polymer is not exhibited. Therefore, ideally, the (co) polymer of dimethyldi (meth) allyl ammonium salt is added first, and then AK
It is effective to add D. In this case AKD is added between the machine chest and the fan pump.

Next, the addition method and addition rate of the polymer used in the present invention will be described. The (co) polymer of dimethyldi (meth) allyl ammonium salt is an acrylic retention agent,
Since it has a lower viscosity than drainage improving agents, it can be added after being diluted several times to 10 times the product. At this time, since dilution can be easily performed, there is a labor-saving merit that it can be directly added to a papermaking line by using a line mixer or the like. The addition rate of the polymer is generally 0.002 to 0.4% by weight based on the solid content of the papermaking raw material, preferably 0.01.
Is about 0.2%. If the addition rate is less than 0.002%, there is no size rising promotion effect, and if it is more than 0.4%, the surface charge of the pulp and filler in the papermaking system is too positively inclined, and unadsorbed polymer is released into the papermaking system. However, the one-pass retention on the wire will be adversely affected.

The polymer used in the present invention may be added by a general wet end additive such as paper strengthening agent, cation-modified starch, sulfate band, calcium carbonate, kaolin, talc, titanium dioxide, white carbon, fine powder silica. Needless to say, it can be used in combination with dyes, pigments, defoaming agents, slime control agents and the like.

[0010]

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

[Production Example of Polymer 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. Add 2,2 ′ azobisamidinopropane dihydrochloride (V50) per monomer in the indicated mole fractions and add nitrogen gas at 20 ° C. for 20 at 40 ° C.
Hold for time and polymerize. Thereafter, each solution was put into acetone to precipitate a polymer, and then dried under reduced pressure to obtain a corresponding polymer. These were added to 4% saline 0.1, 0.05,
Prepare 0.01 and 0.005% of each concentration solution at 25 ℃
In Example 1, the intrinsic viscosity [η] was estimated by measuring the reduced viscosity using an Ostwald viscometer and then extrapolating to zero concentration. Table 1 shows the measurement results of the molar fraction of each copolymer, the V50 addition rate, and the intrinsic viscosity.

[Table-1]

[Examples 1 to 20] Hardwood kraft pulp (LBKP) was beaten to CSF-400 ml to a concentration of 0.
Adjust to 875%. After adding 500 ml of this dispersion to a brit type Dynamixer, light calcium carbonate, cation-modified starch, and (co) polymer of the present invention (trial NO1-10) were added at 800 rpm at the addition amounts shown in Table 2 and below. Each at 10-second intervals by stirring, followed by stirring for 30 seconds after addition of the (co) polymer, addition of ketene dimer sizing agent (AS-261, made by Japan PMC) 20 seconds, stirring market, addition of yield improver 30 After stirring for 2 seconds, the mixture was put into a dynamic jar, filtered through a wire of 60 mesh to collect the paper material remaining on the wire, and a paper having a basis weight of 60 g / m ² was paper-made by a tapi standard handmade paper machine. Each paper is sandwiched between two pieces of filter paper, and 1 is made under the condition of 5 Kg / cm ^2.
Pressed twice. Then 1 by rotary drum dryer
It was dried at 00 ° C. for 2 minutes, and the size degree was immediately measured by the Steckigt method (JIS8122) in a thermo-hygrostat at 65 RH and 20 ° C. Similarly, the sizing degree after 1 hour and 24 hours was also measured. The above results are shown in Table 2.

Comparative Examples 1 to 5 Paper-making tests were carried out in the same manner as in the examples using the following comparative products and no addition. (Comparative product 1) Dimethylamine-epichlorohydrin-pentaethylenehexamine condensate (cation equivalent value 8.0
meq / g, intrinsic viscosity 0.1 dl / g) (Comparative product 2) Acryloyloxyethyl trimethyl ammonium chloride 30 mol%, acrylamide 70 mol% copolymer (cation equivalent value 2.5 meq / g, intrinsic viscosity 1.0 dl / g) The above results are summarized in Table 2.

[Table-2]

[Examples 21 to 40] In the same manner as in Examples 1 to 20, tests were carried out by changing the filler to one having a mixing ratio of kaolin and talc of 1: 1. The results are summarized in Table 3.

[Comparative Examples 6 to 10] A papermaking test was conducted using the same additives as in Comparative Examples 1 to 5 under the same test conditions as in Examples 21 to 40. The results are summarized in Table 3.

[Table-3]

[0016]

EFFECTS OF THE INVENTION When the size treatment method of the present invention is applied, the size start-up after drying in the dryer part is accelerated, the subsequent processing such as coating can be operated on-machine, and the productivity is improved. The contribution to the paper industry is enormous.

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Claims (4)

(57) [Claims] 1. A Upon papermaking papermaking raw material slurry containing ketene dimer system sizing agent, ketene dimer system Sai
Each of the (co) polymers of cation-modified starch and dimethyldi (meth) allylammonium salt prior to the addition of the cooling agent.
Is added in this order . 2. The sizing method according to claim 1, wherein the dimethyldi (meth) allylammonium salt (co) polymer has 50 to 100 mol% of dimethyldi (meth) allylammonium salt structural units. . 3. dimethyldi (meth) allyl ammonium salt (co) according to claim 1 or claim intrinsic viscosity in 1N saline 25 ° C. of the polymer [η] is characterized in that it is 0.6 dl / g or more Item 3. The sizing method according to Item 2. 4. Papermaking containing a ketene dimer size.
When making a raw slurry, a cation-modified demp
(Co) of dimethyldi (meth) allylammonium salt
Add polymer and ketene dimer sizing agent in this order
The sizing method according to claim 1, wherein: