JPS61289198A - Filled 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 [Industrial Applications] The present invention relates to a filled paper, and more particularly to a filled paper that has excellent paper strength and water resistance and has a high yield during paper making. The filled paper of the present invention can be used for printing papers such as wood-free paper, medium-quality paper, and newsprint. Furthermore, the filled paper of the present invention can be used as various coated papers or coated paperboards by coating it with a paper coating color consisting of a pigment and a binder such as carboxyl-modified styrene-butadiene copolymer latex. In addition, 1 wallpaper, sound insulation paper, insulation paper, flame retardant paper,
It can be used for gypsum board base paper, electrical resistance paper, gasket paper, backing material for cushion floors, vibration damping material, sound absorbing material, paperboard, etc.

[Conventional technology]

Various types of printing paper, wallpaper, gypsum board base paper, paperboard, etc. are made from pulp fibers or waste paper using fourdrinier paper machines and cylinder paper machines, followed by wet pressing, drying, and calendering if necessary. Manufactured by K.

In this papermaking process, it is already common in the field of printing paper to add inorganic fillers internally to cellulose fibers such as pulp fibers and waste paper.

The purpose of introducing inorganic fillers in the paper industry is to
Improvements in paper formation, paper opacity, drying speed, and cost reduction due to the use of inexpensive inorganic fillers, etc.

However, in general, when inorganic fillers are added internally to milled fibers and waste paper, the paper strength decreases markedly and the yield of inorganic fillers is low.
For example, the proportion of inorganic fillers used in printing paper is approximately -5
% by weight or less.

Therefore, in the paper manufacturing industry, there is a desire for a filled paper that has a high yield during papermaking and that has less deterioration in paper strength and water resistance due to the internal addition of inorganic fillers.

As a typical method, an attempt has been made to improve paper strength by internally adding latex. for example,
Japanese Patent Publication No. 445-1114L discloses that 0.00% latex is added to a water-dispersible liquid consisting of an inorganic filler and fibrous material. j%
was added to make the latex particles into giant suspended particles, and then 1
A method for producing highly filled paper using conventional papermaking methods is disclosed. However, the nine-filled paper obtained by this method has the drawbacks of insufficient paper strength and water resistance, and low yield. This is considered to be because the surface area of the latex decreases due to the enlargement of the latex particles, and the effect of adding the latex decreases.

Furthermore, Japanese Patent Publication No. 7-Hori TRθ discloses that in the production of paper filled with an inorganic filler with a weight ratio of 0 to 30% by weight, a copolymer latex of 2 to 30'4 is added internally. A method of manufacturing characterized filled paper is disclosed.

However, although the filled paper obtained by this method has considerably high paper strength and is effective in terms of yield, the water resistance strength has not been improved. This is because the fixation of latex particles to pulp fibers is not controlled.
This is thought to be due to the fact that the large latex aggregates are non-uniformly fixed on the surface of the pulp fibers, which reduces the water resistance of the paper sheet due to the water absorption of the uncoated fibers.

Also, Tokukai Akira! According to the publication No. 30 Tata, in a filled paper with an inorganic filler weight ratio of 2 to 50% by weight,
A filled paper characterized in that 0.6 to 20% of carboxy-modified styrene-butadiene latex having a gel content of 0.6 to 20% is internally added is disclosed. This filled paper also has the disadvantage of low water resistance.

Furthermore, the Journal of Applied Polymer Science, Polymer Φ Letter e Edition (J,
Appl, Polym, 5ci-Polym,
Lett, Ed, ) 20, A/ j(/?
fu) According to the description, a method for producing filled paper with superior paper strength and water absorption resistance and a good yield during papermaking is achieved by internally adding 3.0 to 0 parts of cationic acrylic latex. Disclosed.

This method improves yield, paper strength, and water resistance by adding cationic acrylic latex to an aqueous dispersion consisting of pulp fibers and clay so that the latex functions as a binder between pulp fibers and clay particles. It is intended that However, the filled paper obtained by this method has drawbacks such as insufficient water resistance and a significantly low yield of 9 when the paper is made in a neutral region. For example, Charcoal Calcium 1, which is often used in the production of filled paper due to its price, whiteness, and availability, decomposes and foams in acidic regions. However, the above method cannot increase the yield.

[Problem that the invention seeks to solve]

With conventional techniques, it has been difficult to obtain cellulose-based filled paper with high water resistance and strength retention. The main object of the present invention is to provide a filled paper that is manufactured with a high filler yield during paper making and has high paper strength and excellent water resistance.

[Means for solving problems]

The present inventors conducted various research experiments to achieve the above-mentioned purpose, and surprisingly found that the yield and p-aqueous property were sufficiently high in the production of filled paper, and the obtained filled paper The present invention has been achieved by obtaining a paper that has good water resistance and suppresses a decrease in paper strength due to the introduction of an inorganic filler.

That is, the present invention relates to a patented paper filled with cellulose fibers, an inorganic filler, and a copolymer latex, characterized in that the cellulose fibers are uniformly covered with the copolymer latex. .

The filled paper of the present invention is made by using an inorganic filler machine to make paper from cellulose fibers that are uniformly coated with copolymer latex.
It is manufactured by drying and, if necessary, calendering.

The uniformly coated cellulose fibers used in the present invention are those in which copolymer latex particles are uniformly fixed over almost the entire surface area of the cellulose fibers, as shown in the micrograph in Figure 7 (magnification: JO60). It can be distinguished from the non-uniform fixation morphology shown in the micrograph in Figure 1 (magnification: 3rOo).

Further, the filled paper made using uniformly coated cellulose fibers has excellent water resistance strength, and has a water resistance strength retention rate of 1j or more. The water resistance strength retention rate referred to here is a value expressed as the ratio tS of the water resistance tearing length to the tearing length after being immersed in pure water at 20° C. for 1 minute, as shown in Example/-G.

As the cellulose fibers used in the present invention, it is preferable to use one or more of pulps such as unbleached kraft pulp, chemical pulp such as bleached kraft pulp, mechanical pulp, semi-chemical pulp, synthetic wood pulp, and recovered waste paper.

The proportion of cellulose fiber used is the solid content of the filled paper io.

It is preferably 2.0 to 5 parts by weight, particularly preferably 5 parts by weight. If it is less than C or O heavy grain, the paper yield and p-water property during paper making will be extremely reduced, which is not preferable. If the amount exceeds 9♂ parts by weight, the internal addition effect of the inorganic filler will be low, which is preferable.

Inorganic fillers used in the present invention include titanium oxide,
Examples include silica, zinc oxide, barium sulfate, calcium sulfate, calcium oxide, calcium carbonate, aluminum sulfate, aluminum hydroxide, minilum, diatomite, clay, magnesium hydroxide, Merck, and mica.

The proportion of the inorganic filler to be used is preferably 1 part by weight per 100 parts by weight of the solid content of the filled paper.
5 parts by weight is preferred. If it is less than -00 parts by weight, the internal addition effect of the inorganic filler is low and is not preferred. 9? If the amount exceeds 1 part by weight, the yield during paper making and p-aqueous property will be extremely reduced, which is not preferable. The copolymer latex used in the present invention is used for the purpose of improving water resistance strength by coating cellulose fibers, improving paper making properties, and suppressing decrease in paper strength by internally adding an inorganic filler. Book.

It plays an important role in achieving invention.

In order to most effectively achieve the above objectives, it is also necessary to specify the proportions and physical properties of KFi and copolymer latex. The proportion of copolymer latex required to produce cellulose fibers uniformly coated with latex particles is 0 parts by weight or more based on the solid content of cellulose fibers/parts by weight of QO, preferably /, j Parts by weight or more. /, If it is less than 0 parts by weight, the covering power to the cellulose fibers will be incomplete and the water resistance strength of the filled paper will be significantly lowered, which is not preferable. In addition, in the present invention, a copolymer latex may be further used in paper making using cellulose fibers uniformly coated with the above latex particles and an inorganic filler. In the present invention, the total usage ratio of the copolymer latex that uniformly covers the cellulose fibers and the copolymer latex that is further used during paper making is 7.0 to 30 parts by weight based on 100 parts by weight of the solid content of the filled paper; Preferably 1. It is preferably 2 to 2 parts by weight, more preferably 2 to 20 parts by weight. If it is less than Oj parts by weight, the paper strength of the filled paper will drop significantly, which is not preferable. If the amount is 30 parts by weight, the filled paper will become too soft, which is not preferable.

To quantify the copolymer latex in the filled paper of the present invention, the filled paper is treated with hot sulfuric acid to dissolve cellulose fibers and inorganic fillers, and then separated temporarily with a 200-mesh wire mesh. There is a way.

Furthermore, the copolymer latex used in the present invention has a gel content of 23% by weight or more, and has a Tg of 1≠0°C to 70°C.
It is preferable that The gel content of copolymer latex is 2! If the amount is less than % by weight, the effect of suppressing the decrease in paper strength due to the internal addition of the inorganic filler is undesirably reduced. In addition, the gel content used in the present invention is 30 toluene.
Add o, zg of the copolymer to cC, stir and dissolve for about μ hours using a shaker, pass through a 200-mesh wire mesh, and dissolve on the wire mesh +c? 5. The separated copolymers were dried and weighed, and a room-temperature dry film (23°C, Aj96RH) of the original copolymer latex was dried.
It is expressed as a weight ratio to K (drying for 2 hours under the following conditions). In addition, the Tg of the copolymer latex is -40℃
If the temperature is lower than 70°C or higher than 70°C, the effect of suppressing the decrease in paper strength due to the internal addition of inorganic fillers will be markedly reduced, which is not suitable.

The copolymer latex used in the present invention is not particularly limited as long as the gel content and Tg are within the above-mentioned ranges, but styrene-butadiene latex,
Unmodified and modified diene copolymer latexes such as methyl methacrylate-butanene latex and acrylonitrile-butadiene latex are preferred. Furthermore, acrylic latex, vinyl acetate latex, ethylene-vinyl acetate latex, etc. can also be used as required.

The copolymer latex of the present invention can be easily obtained by conventional emulsion polymerization. Examples of emulsifiers used in emulsion polymerization include anionic emulsifiers such as sodium dodecylbenzenesulfonate, sulfurized lauryl powder, sodium dioctylsulfosacunnate, and disodium dodecyl diphenyl ether disulfonate, and nonionic emulsifiers such as polyoxyethylene alkylphenyl ether. and cationic emulsifiers such as humanedeylamine.

As the polymerization initiator, persulfate or a redox catalyst in combination with a reducing agent such as sulfite or bisulfite, hydrogen peroxide, organic hydroperoxide, etc. are used.

Other chain transfer agents, electrolytes, chelating agents, buffers, adjusting agents, etc. can be used as necessary. These emulsifiers, polymerization initiators, molecular weight regulators, other auxiliary agents, and monomers are either all added before the start of polymerization, or some of them are added before the start of polymerization, and the rest are not continuously added during polymerization. It can be used in a known manner, such as by adding it directly. Also, a must! Seed latex may be used depending on the situation.

Although the method for producing cellulose fibers uniformly coated with latex particles used in the present invention is not particularly limited, it can be produced, for example, as follows.

When using a cationic copolymer latex, add at least 7.0 parts by weight of the cationic copolymer to the fiber suspension dispersed in water based on 100 parts by weight of the solid content of cellulose fibers. Cellulose fibers uniformly coated with can be obtained. In addition, when using an anionic copolymer latex, after pre-treating the fibers dispersed in water with a cationic water-soluble polymer, the anionic copolymer latex is mixed with a cellulose fiber solid content of 100%.
By adding K to 0 parts by weight or more, cellulose fibers uniformly coated with latex particles can be obtained. Additionally, the cationic water-soluble polymer used in the above-mentioned pretreatment of cellulose fibers is not particularly limited, but from the viewpoint of uniformly fixing the latex to the cellulose fibers, it preferably has a molecular weight of 10,000 to 2,000.
7.0 million and the amount of cations is N/≠0 in a colloid titration method using OPvSK (polyvinyl potassium sulfate).
0 to 20 meq/9, more preferably a molecular weight of 2
Cation amount mold at 10,000 to 30,000, O to /rmeq
/9.

The filled paper of the present invention is an aqueous dispersion of cellulose fibers uniformly coated with latex particles and an inorganic filler. I
! The composition is prepared by adding a copolymer latex as necessary to form agglomerates to a degree convenient for paper making using a common coagulant, and then making paper.

The flocculant used here is not particularly limited, but
Examples include inorganic electrolytes such as aluminum sulfate, alum, calcium chloride, and magnesium chloride, cationic water-soluble polymers, anionic water-soluble polymers, and nonionic water-soluble polymers.

As mentioned above, in the filled paper of the present invention, it is necessary that the cellulose fibers be uniformly covered with latex, and the form of fixation of the latex to the inorganic filler is not particularly limited. Uniform fixation of latex to the filler can also be controlled in the same manner as the method for fixing latex to cellulose fibers. That is, if an anionic copolymer latex is added after treating a negatively charged aqueous dispersion of an inorganic filler with a cationic water-soluble polymer, an inorganic filler uniformly coated with latex can be obtained. I can do it.

Additives commonly used in the paper industry in carrying out the present invention, such as cellulose crocodile conductors, antioxidants, fungicides,
Bactericidal agents, conditioning agents, water-soluble organic dyes, water-dispersible colored pigments, starch, nonionic acrylamide copolymers, crosslinkable resins such as melamine formaldehyde resins, urea formaldehyde resins, and epoxy resins, paper strength agents, and alkyl A sizing agent such as a ketene dimer, wax emulsion, or rosin can be used as necessary.

Further, inorganic fibers, synthetic fibers, ceramic fibers, etc. can be used as required.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
All parts and parts in the examples refer to 1 part by weight and % by weight.

Example/-A Polymerization of anionic copolymer latex Temperature-adjustable pressurized reaction m equipped with a nitrogen-substituted stirrer
Add lIC water/lOm, 3 parts of sodium dodecylbenzenesulfonate, 4 parts of sodium bicarbonate, and 7.2 parts of sodium persulfate. A monomer mixture consisting of styrene jr part, butadiene qO part, acrylic acid part and tertiary dodecyl mercap 2,000 parts is continuously added evenly over a period of 2 hours to cause a polymerization reaction. Note that the internal temperature of the reactor is maintained at 70°C. Next, residual upper particles were removed by steam stripping to obtain an anionic copolymer latex having a solid content of about 3 g.

Example/-B Polymerization of cationic copolymer latex 110 parts of water, 0.7 parts of laurylamine, 095 parts of methanesulfonic acid, and ferric chloride were placed in a temperature-adjustable pressurized reactor equipped with a nitrogen-substituted stirrer. o, oj part, hydrogen peroxide O,
Add the S section. Mono 1 of Example/-A - A liquid obtained by removing acrylic acid from the mixed liquid is added continuously and evenly over a period of 7 hours. Note that the internal temperature of the reactor is maintained at 70CK. Next, IC and steam stripping were performed to remove residual monomers to obtain a cationic copolymer latex containing a solid content of about 1A35b.

Example/-C Preparation of cellulose fiber uniformly coated with anionic copolymer latex Bleached kraft pulp (hardwood) was beaten in a beating machine, and the Canadian 7 leanness (JIS Prt2/) was 4c! O
Adjust so that it is dK. The above pulp slurry was adjusted to O.U% without stirring, and the pulp solid content was adjusted to io.

After adding 0 parts of polyamine-based cationic polymer (molecular weight: 10,000, degree of cation / θmeq/g) to 100 parts of pulp solid content, the anionic copolymer latex of Example/-A was added. θ part is added to the target. Also,
The fixation rate of the latex to the cellulose fibers obtained by the above method was determined and was found to be r%. The fixation rate was measured by measuring the turbidity of p water when paper was made from the aqueous dispersion after adding the latex using an ioo mesh.

Example/-D Creation of water-dispersible fiber uniformly coated with cationic copolymer latex Bleached kraft pulp (hardwood) was beaten in a beating machine to obtain Canadian freeness (JISP♂lλ/).
Adjust so that it becomes 10-. While stirring the above pulp slurry, Dilute to lI'4 and adjust the pH with hydrochloric acid! Further, 0 parts of the cationic copolymer latex of Example/-B is added to 100 parts of pulp solid content.

Example/-E Preparation of filler Pulp slurry IJ-6O part K uniformly coated with the latex prepared in Example/-C Example/-A 2 parts of copolymer Latin 2 and inorganic filler ( Carunium carbonate (dual grade 1! μ diameter) was added one by one while stirring, and finally o and t until the water in the slurry became transparent.
% polyacrylamide-based cationic polymer flocculant (
Molecular weight/0 million, cation degree/, Omeq/9
) gradually. The aqueous dispersion thus obtained was transferred to a square sheet machine, water was added to adjust the slurry concentration to 0.1%, the water was removed to obtain wet paper, and the wet paper was transferred to a wet-pressed waste drum dryer. and dried.

The resulting filled paper had a basis weight of about 939 to 3.0 cm and a yield of 3 cm.

Example/-F Measurement of Paper Strength Example Breaking strength when the filled paper obtained in Example/-E was cut into 6 cm wide strips and pulled at a speed of 20 w/min using a tensile tester. Kp//jm) is the basis weight and sample width (
/j) multiplied by 1000 (rupture length)≠J'h.・Example/-G Measurement of water resistance strength retention Example/-Filled paper t/,! Example of water resistance tearing length after cutting into strips of cm width and immersing them in pure water at 20°C for VCt minutes / Value F expressed as the ratio of -F to the tearing length
iU≦I am sorry.

Comparative Example/-A Preparation of Filled Paper Canadian Freeness Gabi 30- Bleached Kraft Pulp (Hardwood) To part adjusted to O.4t Example/-A Anionic Copolymer Utex J Part and Examples After adding 3j parts of the calcium carbonate used in Example 1, the polymer flocculant used in Example 1 was added until the water in the water slurry became transparent. Next, the slurry was diluted to 0.1%, and then paper was made and dried in the same manner as in Example 2 to produce filled paper.

Yield 20%, basis weight 9j9/r? Met.

(Margins below) Comparative Example/-B Regarding the filled paper obtained in Comparative Example/-A, Examples/-F, /
When the paper strength and water resistance retention rate were determined by the method of -G, the paper strength strength and water resistance strength retention rate were 7.

Comparative Example - A sample was prepared in the same manner as Comparative Example/-A except that the copolymer latex was removed. Yield 0%, tsubo weighing 9/ff/
A filled paper was obtained. Paper strength 1g~/? F/, water resistance strength retention rate -1.

Example Co Anionic copolymer latex a consisting of monomers having the monomer composition shown in Table/Ic was prepared in the same manner as in Example/-A.
-i was obtained. The gel fraction and Tg of the latex are also listed in the table.

D]3V: Divinylbenzene Tg: A calculated by Tobolsky's formula
, A, : Acrylic acid 1, A, : Itaconic acid Example 3 and Comparative Example 3 Using the anionic copolymer latex prepared in Example 2, the same as Example /-C and Example /-E was carried out. Filled papers 3A to 3E and 3F to 3■ were obtained by the method. In addition,
The anionic copolymer latex used in Example
The same latex used in Example 1 was selected. The physical properties of the filled paper are shown in the table.

Example V and Comparative Example ≠ Example /-E except that the number of parts of the anionic copolymer latex used was changed as shown in Table 3 in preparing the uniformly coated pulp fiber of Example /-C. In the same manner as in Filled Paper Hiro A-≠E and! Created on r1. Table 3 shows the physical properties of the filled paper.

Example: Filled paper jA was prepared in the same manner as in Example /-E, except that the carbonaceous calcium used in Example /-E was changed to talc: imported talc with a diameter of 7 μm and clay kaolin clay.
- Created a jc and mourned. The physical properties of the filled paper are shown in Table μ.

Example 6 Bleached kraft valve used in Example/-C (≠jO-:
Filled papers G and +c were prepared in the same manner as in Example/-E, except that the hardwood (hardwood) was changed to mechanical pulp and recycled newspaper pulp. The physical properties of the filled paper are shown in Table jK.

Example 7 A filled paper was prepared in the same manner as in Example /-E, except that the cellulose fibers obtained in Example /-0 were changed to those obtained in Example 1-. The physical properties of the filled paper are 3 cm in yield and 9 in basis weight? , paper strength 3. water resistance strength retention rate 30
%Met.

Example! A cardboard with a high basis weight is made by the method of Example/-E. The uniformly coated cellulose fibers used herein are Examples/-
According to method C, bleached kraft pulp (softwood, ≠r
o, 1) 0 parts of the anionic copolymer obtained in Example/-A was used based on 10 parts of solid content. Filled paper was prepared by the method of Example/-E using 10 parts of cellulose fibers coated with the latex, 1 part of barium sulfate (t), and λ part of the anionic copolymer tex obtained in Example/-A. The physical properties of the filled paper include a yield of 3 cm and a basis weight of λ1009/rr? ,
Paper strength λ, /IC11% water resistance strength retention rate etc.

Comparative Example Comparing with Example 1, Comparative Example/-A filled paper with a high tsubo I was prepared by a method similar to AK. However, 70 parts of bleached kraft bulb, ♂♂ parts of barium sulfate, and 2 parts of the anionic copolymer latex obtained in Example/-A were used. The physical properties of the filled paper are: yield 90 tai, tsubo i 1200 θ9 i,,I
! , paper strength/, /Km, and water resistance strength retention rate//chi.

In addition to making paper from cellulose fibers and inorganic fillers uniformly coated with copolymer latex in this example, we also created filled paper without using all of the copolymer latex. The preparation method was used in Example ♂ (-★ Cellulose fibers not uniformly covered with latex, '0 parts, barium sulfate 9
The procedure was the same as in Example ♂, except that 0 part was used and the copolymer latex portion was not used. The physical properties of the obtained filled paper are as follows: yield 70%, basis weight, 2Q30/-
The paper strength was 1/J'Ks, and the water resistance strength retention rate was 3 g.

〔Effect of the invention〕

As is clear from the above Examples and Comparative Examples, the filled paper of the present invention using cellulose fibers evenly coated with latex has excellent yield, paper strength, and water resistance.

Furthermore, the cellulose fibers uniformly covered with the latex that constitutes the entire filled paper of the present invention are 7 times larger than the filled paper after preparation.
Take out the fibers from the book 1. It can be easily distinguished by observation using transmission microcasting. Figure 3 shows a microscopic photograph (magnified by SOO) of the fibers taken out from the packed paper obtained in Example ♂. It is shown in figure j.

[Brief explanation of drawings]

Figure 1 is a micrograph (rooo magnification) of cellulose fibers uniformly coated with the copolymer latex of the present invention.
, Fig. 2 is a micrograph of cellulose fibers uniformly coated with copolymer latex 1 (0600x), Fig. 3
The figure is a microscopic photograph (00x magnification) of the surface of the pulp fiber taken out from the packed paper of Example ZA, and Figure q is a microscopic photograph (!t) of the surface of the pulp fiber taken out from the packed paper of Comparative Example J.
00 times). Figure 1 Figure 3 Figure 4

Claims (2)

[Claims] (1) In a filled paper containing cellulose fibers, an inorganic filler, and a copolymer latex as main components, the weight ratio of the copolymer latex is 1.0 to 30 parts by weight based on 100 parts by weight of the filled paper, A filled paper characterized in that the cellulose fibers are uniformly coated with a copolymer latex. (2) The filled paper according to claim 1, wherein the water resistance retention rate of the filled paper is 15% or more.