JPS63203894A - Production of internally sized paper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (A>Field of Industrial Use) The present invention relates to a method for manufacturing paper doped with fillers, and more specifically to a method for manufacturing filler-doped paper with excellent opacity and strength. .

(B) Prior Art Usually, fillers are added to paper used for printing or writing for the purpose of improving opacity, whiteness, smoothness, feel, writability, printability, etc. Conventionally, the method for manufacturing paper with internally added fillers has been to add fillers to pulp dispersed in water, and to make fourdrinier from a paper stock prepared by adding fillers and other internal additives commonly used in paper making. Wet paper was formed using a paper machine or twin wire paper machine, and then dried. These internal fillers impede the adhesion between pulp fibers, increase the scattering surface area, or increase the scattering efficiency due to the difference in refractive index, resulting in improved opacity. In order to meet ever-increasing product quality requirements, it has become increasingly important to use fillers more effectively and in larger amounts.

By containing a large amount of filler, the opacity of the paper improves, but the strength of the paper decreases, so there is a limit to the filler content in the paper. A is an attempt to reduce the decrease in paper strength due to the addition of fillers.

J.) (as described by Ayes in the April 1985 issue of Paper Chiklodge and Industry Magazine,
A technique is known in which a filler is agglomerated with a cationic polymer electrolyte and then added to paper stock.

Also, in Japanese Patent Publication No. 57-13680, the refractive index is 1.45 to 1.
．． 65 pigment is aggregated and the pore size of the internal void is 0.11n.
Adding the above agglomerated particles to the pulp slurry to form a large number of internal voids with a size as close to O,'1iin as possible to improve the opacity and whiteness of papermaking,
Furthermore, a paper manufacturing method that can improve the filler yield is disclosed in JP-A-54-116405.
A filled paper product is disclosed in which particles having a size of ~0.3 IIn are agglomerated and the agglomerated particles contain 5 to 80% by weight of the dry pulp. Furthermore, JP-A-60-11
No. 9299 discloses a paper-making method in which heavy calcium carbonate is mixed in advance with an aqueous cation-modified starch solution and then added to the paper stock to improve wire wear.

(C) Problems to be Solved by the Invention Filled paper made by dispersing filler in pulp slurry and adding an internal additive to papermaking using the conventional method can only be produced by increasing the amount of filler. Although opacity is achieved, the filler distributed between the fibers inhibits the bonding between the fibers, resulting in a paper with correspondingly lower strength. In addition, according to the technology of agglomerating filler in advance and adding it to paper stock to make paper, it is possible to reduce the decrease in paper strength due to the addition of filler, but this is one of the purposes of adding filler. It also reduces the opacity of the paper. In this way, the improvement in opacity by fillers and the strength of paper are in a contradictory relationship, and it is quite difficult to achieve both.

(D> Means for Solving the Problems The inventor of the present invention has conducted intensive studies to solve the various problems mentioned above when producing paper with fillers internally added thereto. 2. Excellent opacity and strength can be achieved by dispersing a filler of less than Ota and microfibrous cellulose with a water retention degree of 250% or more in water, mixing them, coagulating them with a flocculant, and then adding them to paper stock. It has been discovered that it is possible to produce a paper containing fillers.

The fillers of the present invention include talc, clay, titanium oxide, precipitated calcium carbonate, ground calcium carbonate, calcium sulfate, barium sulfate, aluminum hydroxide, activated clay, synthetic silicates, and the like, with an average particle size of 2.0 pn or less. Fillers that can be used in ordinary paper, such as kaolin, calcined kaolin, and plastic pigments, can be used alone or in combination. Fillers with an average particle diameter of more than 2.0 tttn do not provide sufficient opacity and strength.

In the present invention, the average particle size refers to the average particle size obtained by dispersing an aqueous filler dispersion using an ultrasonic disperser for 5 minutes, then using a light transmission particle size distribution analyzer (
This is the diameter of particles whose cumulative weight percentage corresponds to 50%, determined using a particle size distribution curve obtained by applying the SKN formula (manufactured by Seishin Enterprise Co., Ltd.).

The microfibrous cellulose having a water retention degree of 250% or more according to the present invention includes JP-A-56-10080'1, JP-A-58
-197400, JP-A No. 59-1206388, manufactured by a special beating means in which pulp fibers are suspended in water and repeatedly passed through a homogenizer under high pressure, or a beater or refiner. It is possible to use any of those produced by ordinary beating means such as. In addition, the water retention degree in the present invention is determined by J, TAPPI paper pulp test method Nα26-78.
This is the value measured according to the following.

As the flocculant in the present invention, among cationic polymer electrolytes, cationic polyacrylamide, cationic starch, cationic guar gum, etc. with a molecular weight of 100,000 or more can be used.

The amount added varies depending on the filler used and the type of pulp fine fiber, but it is 0.01% by weight or more.
10.0 weight percent or less is suitable.

Furthermore, anionic polymer electrolytes that form complexes with these cationic polymer electrolytes to strengthen aggregation, such as anionic polyacrylamide, or anionic inorganic fine particles such as colloidal silica or bentonite aqueous dispersion. Furthermore, it is also possible to form an aggregate of the filler and pulp fine fibers by using an amphoteric polymer electrolyte, an amphoteric inorganic fine particle aqueous dispersion, or the like.

Average particle size of the present invention2. The content ratio (A/B) of the filler below Otsn (A> and the microfibrous cellulose (B) with a water retention degree of 250% or more is preferably 0.5 or more and 20° or less by weight. (A/B) ) is less than 0.5, sufficient opacity improvement effect and strength cannot be obtained, and (A/B) is less than 20.
．． The effect of opacity enhancement above 0 is significantly reduced.

The filler-added paper in the present invention includes additives commonly used in paper making, such as sizing agents, antifoaming agents, slime control agents, dyes, colored pigments, fluorescent agents, dry paper strength improvers, and wet paper strength improvers. , a drainage improver, a retention improver, etc. can be included as necessary.

It is also possible to smear starch, polyvinyl alcohol, various surface sizing agents, etc. on the surface of the filler-added paper of the present invention.

(E) The reason why filler-added paper with excellent opacity and strength can be produced by pre-agglomerating the functional filler and microfibrous cellulose and then adding them to the paper stock during papermaking is because only the filler is agglomerated. However, since microfibrous cellulose, which has a different refractive index from the filler, is aggregated with the filler, it is thought that the number of interfaces that are effective for light scattering is less likely to be reduced. .

Furthermore, since the filler is held between the fibers as aggregates, there is less fine filler that inhibits the bonding between the fibers, which is thought to reduce the decrease in strength.

(F) Example The present invention will be described in detail below with reference to Examples.

Note that the present invention is not limited to the examples.

In the examples, all parts and percentages are by weight.

Reference Example A 2% dispersion of microfibrous cellulose was prepared by the following method. Purified sulfide pulp (α-cellulose content 9
2 to 93% and a polymerization degree of 1050 to 1070), water was added to make a 2% slurry, and the slurry was slurried to about 500% using a Uonton-Gaulin homogenizer according to the method disclosed in JP-A-56-100801. The slurry was circulated 40 times under high pressure of J/lri. The water retention degree of the obtained microfibrous cellulose was 300%. Note that by changing the number of passes, microfibrous cellulose having different degrees of water retention can be obtained.

The obtained 2% dispersion of microfibrous cellulose was used in the examples, and the amount of microfibrous cellulose added in the examples is the solid content@calculated value.

Example 1 A hardwood tallow pulp slurry was prepared by beating it to a depth of 350 m using a beater at Canadian standard freeness. Separately, precipitated calcium carbonate (A) with a particle size of 1.0IIn
and reference example microfibrous cellulose (B) at a weight ratio (A
/B) at 10/1, and after dispersing and mixing in water at a solid content concentration of 10%, preheated and dissolved cationic starch (cato2 manufactured by Tamago National Co., Ltd.) was added to the total amount of precipitated calcium carbonate and microfibrous cellulose. The mixture was added and stirred so that the concentration was 1% per minute to obtain a slurry of aggregates. Next, 45 parts of the above aggregate was added in terms of solid content to the previously prepared pulp slurry (100 parts in terms of pulp solid content).

Paper of tsubo m60'j/rd is made by hand from this slurry,
7. On wet paper. Example 1
samples were obtained.

The fill valve in the paper for this sample was about 25%.

Comparative Example 1 Instead of the aggregates of Example 1, the same cationic starch as in Example 1 was added to an aqueous dispersion of precipitated calcium carbonate with an average particle size of 1.0 mm at a solid content concentration of 10% based on the weight of calcium carbonate. Aggregates were obtained by adding 0.5%.

To a slurry of the same pulp as that used in Example 1, 41 parts of the aggregate was added as a solid content based on 100 parts of the pulp solid content, and then 4 parts of the microfibrous cellulose of Reference Example was added. Next, 0.23 parts of the above cationic starch solution was added in terms of solid content, and a sample was obtained by hand-sheeting in the same manner as in Example 1. This sample is referred to as Comparative Example 1. The filler force in the paper of this sample was approximately It was 25%.

Comparative Example 2 Same pulp slurry as Example 1 (pulp solid content '100
part), the same average particle diameter as used in Example 1, 1.0 II
The solid content of 45 parts of precipitated calcium carbonate of n, 4 parts of microfibrous cellulose of reference example, and cationic starch solution was 0.4 parts.
5 parts were added and mixed separately to prepare a paper stock. Next, a sample of Comparative Example 2 was obtained by hand-papering in the same manner as in Example 1. The filler power in paper for this sample was approximately 25%.

Example 2 The precipitated calcium carbonate used in Example 1 had an average particle size of 2.
An aggregate was obtained in the same manner as in Example 1, except that Oan's heavy calcium carbonate was used. In addition, the same pulp slurry as prepared in Example 1 (pulp solid content '100 parts)
To this, 45 parts of the above-mentioned aggregate was added as a solid content, and 0.05 part of an alkyl ketene dimer sizing agent was added as a solid content to obtain a paper stock. Paper with a basis weight of 609/m was handmade from this stock, water was extracted by applying a pressure of 7°0 Ky/rti to the wet paper, and the paper was dried for 3 minutes in a cylindrical dryer at 95°C.
samples were obtained. The filler power in paper for this sample was approximately 25%.

Comparative Example 3 The heavy calcium carbonate used in Example 2 had an average particle size of 5.
A sample was obtained in the same manner as in Example 2 except that Optrr heavy calcium carbonate was used. The paper weight of this sample was 25%. This sample is referred to as Comparative Example 3.

Examples 3 to 7 100 parts of the same pulp as in Example 1 was added with an average particle size of 0.3
The mixing ratio (A/B) of the precipitated calcium carbonate (A> of tttn) and the fine LLI fibrous cellulose (B) of the reference example was 0.25, 0.50, 1.0, 20.0, and 50.
0.05% of cationic polyacrylamide (Percoll 292, Allied Colloids) was added to the weight of the filler and microfibrous cellulose in each mixture to make five types of aggregates. Five types of handmade sheets were prepared in the same manner as in Example 1, such that the filler content in each sheet was 10%. These samples were mixed with different proportions of filler and microfibrous cellulose.
Examples 3.4.5.6.7, respectively.

Example 8.9 The water retention degree of the microfibrous cellulose used in Example 1 was 25
Samples were obtained by hand-shaping in the same manner as in Example 1, except that the paper was changed to two levels, 0 and 280%.

These samples are designated as Examples 8 and 9, respectively, due to the difference in water retention of the microfibrous cellulose.

Comparative Example 4 The water retention degree of the microfibrous cellulose used in Example 1 was 23
All the paper was made by hand in the same manner as in Example 1 except that it was 0%.
A sample was obtained.

Example 10 A sample was obtained in the same manner as in Example 1 except that the microfibrous cellulose used in Example 1 was obtained by beating softwood kraft pulp with a Ritziner to a water retention value of 300%.

The above results are summarized in Table 1.

(Margin below) (G) Effect of the invention Normally, the characteristics required for printing paper with a basis weight of 60 g/Td are opacity of 78% or more and internal bond strength of 300 g cm.
/ cm or more, but it is more preferable that the opacity is 82% or more and the internal bond strength is 350 g·cm / crA or more.

Example 1 in Table 1. The results of Comparative Examples 1 and 2 show that by adding the filler and microfibrous cellulose after flocculating in advance, a sheet having higher opacity and strength can be obtained at the same time than when only the filler is flocculated or added separately. ing. Looking at Examples 1 and 2 and Comparative Example 3, the particle size of the filler was 2. It shows that O/l #71 or lower is excellent. From the results of Examples 3 to 7, it was found that the filler (A>
It is clear that the weight ratio (A/B) of microfibrous cellulose (B) and microfibrous cellulose (B) is particularly preferably 0.50 or more and 20.0 or less.

From the results of Example 1.8.9 and Comparative Example 4, water retention degree 250
% or more, it is clear that high opacity cannot be obtained due to aggregation with the filler. Example 10 shows that even when the pulp that has been heavily beaten in a sofiner is used as the microfibrous cellulose J, the same effects as those of the homogenizer-treated pulp and the like can be obtained.

As in the present invention, microfibrous cellulose with an average particle size of 2.0 pn or less and a water retention degree of 250% or more.

4! which was aggregated with a cationic polymer electrolyte. By adding it to the stock, a filled paper with excellent opacity and strength can be obtained. This is extremely superior to the conventional technique ↑, which suffers from a decrease in either indistinctness or strength.

Claims (3)

[Claims] (1) A filler with an average particle diameter of 0.1 μm or more and 2.0 μm or less and microfibrous cellulose with a water retention degree of 250% or more are mixed and dispersed in water, pre-agglomerated with a flocculant, and then added to paper stock. A method for manufacturing filler-added paper, which comprises papermaking. (2) The content weight ratio (A/B) of the filler (A) with an average particle diameter of 0.1 μm or more and 2.0 μm or less and the microfibrous cellulose (B) with a water retention level of 250% or more is 0.5 or more and 20 ．．
0 or less, the method for producing a paper with filler incorporated therein according to claim 1. (3) The method for producing a filled paper according to claims 1 and 2, wherein the flocculant is a cationic polymer electrolyte.