JPH03130497A - Alkaline paper and alkaline aqueous composition - Google Patents

Abstract

PURPOSE: To obtain an alkaline paper inexpensive by displacing a part of expensive pulp fibers with inexpensive materials and high in opacity and tear strength by incorporating polymeric vesiculated granules and a calcium carbonate filler in a fibrous cellulose-based material to be a specific composition. CONSTITUTION: (A) The fibrous cellulose-based material, (B) 1.0-10.0 wt.% polymeric vesiculated granules having 1-100 μm average particle diameter, 20 μm average granule diameter and maximal diameter of the vesicles in the granules and 5-95% volume ratio of the whole vesicles to the granules and (C) 5-35 wt.% sedimentation type calcium carbonate filler are blended, a state-holding auxiliary agent is added and the furnish for papermaking is adjusted and supplied to a sheeted paper making machine after adjusting the pH to 7.8-8.2 using a diluted sodium hydroxide aqueous solution to obtain the objective alkaline paper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to vesiculated polymer granules, and more particularly to paper containing said granules.

The development of paper with high opacity, low cost, and acceptable physical properties has always been of interest to paper manufacturers.

Paper typically contains fibrous materials, sizing agents, dry strength additives,
A suspension (i.e., a papermaking furnish) of wet strength additives, defoamers, biocides, dyes, pigments, retention aids, and/or fillers is drained. (wate
Paper layer forming gold 14 (for
ming wire), i.e., by transferring it to a paper machine screen and condensing it to a solid material. The paper formed on the paper layer forming wire mesh is then heated to a predetermined basis weight ((basis
weight) weight per unit area].

The fibrous materials used in papermaking are cellulosic or non-cellulosic forms such as plants such as wood, cotton, bagasse, and synthetic polymers such as rayon, which may be delignified and/or bleached. You can leave it there.

Fillers are typically added during papermaking to replace some of the expensive valve fibers with cheaper materials. The fillers chosen for alkaline papers (herein meant any paper made from an aqueous fibrous suspension with a pH of 7 or above) are usually clays such as kaolin, and also known as calcium carbonate. Selected from some inorganic fillers.

Calcium carbonate used as paper-making filler belongs to three classes: ground calcium carbonate, chalk calcium carbonate and precipitated calcium carbonate. Ground calcium carbonate occurs naturally in the earth, is mined, and is ground to a predetermined particle size. Chalk-like calcium carbonate is the skeletal remains of marine organisms, while precipitated calcium carbonate is formed by bubbling carbon dioxide gas into an aqueous slurry of calcium hydroxide to form calcium carbonate, then forming calcium carbonate. It is a man-made form of calcium carbonate produced by precipitating it.

Calcium carbonate is not used in acid paper making.

The reason for this is that calcium carbonate causes foaming by producing carbon dioxide in acidic aqueous paper compositions.

- For boat fishing, the filler also has suitable optical properties, i.e. whiteness, brightness.
ess) used to impart opacity and color, as well as surface properties such as smoothness and printability.

The degree of opacity of a particular substrate is the result of the scattering of diffuse light that occurs when visible light is reflected by particles on the surface of the substrate and the substrate medium itself. In alkaline papermaking, it is customary to use the aforementioned inorganic mineral fillers, especially calcium carbonate, to enhance the optical and surface properties of paper sheets.

However, there are practical limits to the amount of inorganic mineral filler that can be added to paper. As the content of inorganic mineral fillers increases, there is a substantial decrease in the physical strength properties of the paper. This decrease in physical properties is due to the strands (s) of the fiber material.
This decrease in physical properties is caused by the hydrogen bonds between the two strands (trans) being obstructed by the above-mentioned fillers, and this decrease in physical properties contributes to the strength present in plain paper due to the increased content of inorganic mineral fillers. This occurs because the amount of R-fibers produced is reduced.

The physical properties mentioned above, e.g. bursting strength index
), % elongation, length at break and tensile energy absorption (TEA
The index (abbreviated as ) is an important consideration in papermaking.

The reason is that paper with unacceptably low physical properties
This is because they are susceptible to tearing on the paper machine or during the printing process, or the paper grade is below accepted standards.

Although improvements in one physical property, such as tear strength, can usually be achieved at the expense of another physical property, such as tensile strength, there is an economical way to improve all of the physical properties at the same time. It is rare to discover. For optimal operation, especially in paper machines, a blend of good physical properties is desired. Therefore, paper manufacturers have sought to develop paper formulations (f
operation).

A decrease in physical properties during papermaking is observed - as the amount of filler is increased. The amount of filler used in alkaline paper making is considerably higher than in acid paper making. The reason for this is that there are economic benefits to using a large amount of relatively inexpensive calcium carbonate filler. The reduction in physical properties as a result of increasing the amount of filler is more important in alkaline papermaking than in acidic papermaking.

Vesiculated granules of polymers that are carboxylated unsaturated polyesters crosslinked with ethylenically unsaturated monomers
It is already known in the papermaking art that iculated granules can impart advantageous properties such as improved opacity to papers and coating compositions in which they are incorporated. Background on the use of the above-mentioned vesicularized granules in papermaking can be found in the literature, for example Kers.
References by haw (rAustralianOCCA
Proceedings and News J 19
August 1971 issue) and the literature by Treier (rTAP
PI J, Vol. 55, No. 5, 1972). A number of patents have also been issued regarding the aforementioned vesicularized granules, including U.S. Patent No. 3.822.2.
No. 24, No. 4.089.819, No. 4.137.
No. 380, No. 4.321.332, No. 4, 483
．． 945, Canadian Patent No. 1.139.048 and European Patent Application No. 0.204.916 and European Patent Application No. 0.2
No. 68,729.

The technology for producing vesicularized polyester polymer granules has been known for several years, and suitable methods for producing such granules are now well established.

This method is called “double emulsification method”.
In the two-stage emulsification process, water is first dispersed in a solution of a carboxylated unsaturated polyester dissolved in a polymerizable monomer to form a "-secondary emulsion," and then a primary emulsion is formed. The liquid itself is dispersed in water to produce a "secondary emulsion". Radical polymerization is then initiated to produce vesicular granules of cross-linked polyester resin. Pigmented vesicular granules If required, the pigment may be dispersed in either or both of the primary emulsion components using conventional pigment dispersants and antifoaming agents. -L Inc., U.S. Patent No. 4.
808.633.

European Patent Application No. 0.204.916 and European Patent Application No. 0.26
No. 8.729 describes a method for making high bulk calendered paper containing vesicularized beads. European Patent Application No. 0.204.91
No. 6 describes a sublime calendered paper in which vesiculated granules are added in an amount of 0.5 to 15% by weight of the paper produced, preferably 2 to 10%. This increases the opacity of the paper. Paper produced according to European Patent Application No. 0.204.916 has an increased thickness and print resistance.
ce to print show through)
Moreover, the whiteness and opacity of the paper are maintained.

This makes it possible to reduce the amount of titanium dioxide pigment, reducing the cost of the paper obtained.

European Patent Application No. 0.268.729 discloses that European Patent Application No. 0.204.916 has increased thickness and print show-through resistance while retaining whiteness and opacity. It is written whether the paper is similar to the paper described.

Therein, the concentration of vesiculated polymer granules is between 2 and 6%, preferably between 4 and 6%, of the total weight of the paper.

In a preferred embodiment of the invention, a neutralized polycarboxylic acid polymer thickener is added to reduce the proportion of fine powder that passes through the paper layer forming wire gauze.

European Patent Application No. 0.268.729 and European Patent Application No. 0.204.916 both describe paper compositions prepared from acidic papermaking furnishes. has been done. European Patent Application No. 0.268
．． In No. 729, the water-containing raw stock has a pH of 4 to 6.
It is preferable to have Both patent applications also state that physical properties are maintained by replacing titanium dioxide with polymeric vesicular granules. However, neither of these patent applications mentions anything about the use of vesicularized polymer granules in alkaline paper compositions, especially paper compositions containing calcium carbonate fillers.

The inventors have now discovered that the physical properties of alkaline papers containing calcium carbonate fillers can be improved by the addition of vesicularized polymer granules. These improved physical properties are evident in typical alkaline papers containing 5-35% calcium carbonate and 1-10
Achieved at a particulate concentration of % by weight.

According to the improvement observed in the physical properties of the alkaline paper according to the invention, by further adding an additional amount of calcium carbonate while keeping the physical properties constant, i.e. by further replacing the expensive fiber material. or by increasing the line speed of the paper machine due to the improved physical properties of the paper, i.e. by producing more paper per unit time, it is possible to reduce the cost of the paper produced to the paper manufacturer. It becomes possible.

It is an object of the present invention to provide an alkaline paper with improved physical properties.

Another object of the present invention is to improve the physical properties of alkaline papers containing calcium carbonate while preserving or improving the opacity of the alkaline papers.

Thus, in accordance with the subject matter of the present invention, a fibrous cellulosic material, 1.0-10.0% of the weight of the paper of vesicularized polymeric granules, and 5-35% of the weight of the paper of carbonic acid. There is also provided an alkaline paper as defined above comprising a calcium filler.

According to a preferred embodiment of the invention, there is provided an alkaline paper as defined above, said alkaline paper containing 1 to 5% of the vesicularized polymer granules as defined above.

According to a further preferred embodiment of the present invention, the alkaline paper is provided, wherein the amount of calcium carbonate is 10 to 25% by weight of the paper.

Regarding the calcium carbonate filler used in the practice of this invention, precipitated calcium carbonate or ground calcium carbonate is preferred, and precipitated calcium carbonate is most preferred.

Besides calcium carbonate, other fillers, pigments, extenders and/or
Alternatively, opacifying agents such as titanium dioxide, clay and talc may be added to the paper suspension according to conventional techniques for papermaking, or to the vesiculated granules during the manufacture of the granules.

By vesicular granules is meant polymer granules, preferably spherical granules, which have a cell-like structure and whose walls are constituted by a polymer. The granules contain a large number of cells or vesicles (ie, the granules are not single cellular or balloon-like). And although the vesicles need not be of uniform size, the ratio of the diameter of the granules to the mean diameter of the individual vesicles is generally at least 5:1. Vesicles typically account for 5-95% of the total volume of the granule.
and the maximum diameter of the vesicles is 20 microns. Although the small volume of the vesicles is usually associated with granules having high mechanical strength, which is particularly useful in some applications, for the most effective negative effect the vesicles are typically is at least 20% of the total volume of the granules, preferably from 20 to
It accounts for 75%.

Accordingly, according to a preferred embodiment of the invention, the polymeric polyvesicularized granules have an average diameter of 1 to 1 oo microns, and the ratio of the diameter of the granules to the average diameter in the vesicles is at least 5:l. , the maximum diameter of the vesicles is 20 microns, and the total volume of the vesicles is 5% of the volume of the granules.
~95% alkaline paper is provided.

The vesiculated particulates have a substantially continuous solid wall (sol
id wall) and has a preselected and targeted granularity. Roughly, the granules may have an average diameter of 1-100 microns. - It has been found by the inventors that for boat fishing, granules having an average diameter of 1 to 50 microns are most important as opacifying agents.

In addition, a small amount of polyelectrolyte retention aid (retenti
on aids) to combine the inorganic mineral filler in the sheet formation with any fine fiber fraction (fibrillar) of the cellulosic material.
ne fractions). In alkaline paper making, double
e) It is customary to use retention aid systems.

Cationic retention aids are used in preparation or "conditioning" of the furnish before adding the anionic retention aid.
Dual retention aid systems usually consist of polymeric polyelectrolytes such as polyacrylamide and polyethyleneimine.

It is also possible to achieve retention in the alkaline furnish using a single polymeric retention aid, such as polyacrylamide.

Another subject of the invention is the above-mentioned alkaline aqueous composition (by which is meant any composition with a pH of 7 or above) used for the production of the alkaline paper of the invention.

Accordingly, in accordance with another aspect of the invention, an alkaline aqueous composition comprising a fibrous material, 1.0 to IO% by weight of vesicularized polymeric granules, and 5 to 35% by weight of calcium carbonate filler. (provided that the above weight percentages are based on the weight of paper made from the composition).

Aqueous slurries of vesicularized polyester polymer granules formed according to the method described in U.S. Pat. No. 4,808,633 can be used directly in wet-end applications. The aqueous slurry of vesicularized polyester granules can also be dewatered by any convenient means, such as the method described in U.S. Pat. is,
It is then incorporated into the furnish.

The pulp components of the alkaline paper of the present invention to be produced are:
It may be produced in part or in whole from hardwoods, softwoods and, if desired, reclaimed valve and/or waste paper with internal sizing agents such as alkylketene dimer emulsions or alkylsuccinic anhydrides.

In general, it has been found by the inventors that for purposes of the present invention, the upper limit of effectiveness of vesiculated polymer granules should be 10% by weight of total paper solids. The amount of granules is less than 5% by weight, more preferably because of the cost of the vesicularized polymer granules and because amounts of granules greater than 10% by weight reduce the degree of improvement in physical properties. 3% by weight
It is preferable that it is less than

The present invention will be explained in detail by the following examples.

The following examples are given by way of example only, and all parts in the examples represent parts by weight.

Example 1 Pigmented vesicularized polyester resin granules having a maximum diameter of 10 microns (percentile 95) and a mean mean diameter of 5.2 microns used in the practice of the present invention were prepared as follows: U.S. Patent No. 4.808.6 except that the formulation of
It was prepared in the same manner as in Example 1 of No. 33 specification.

Group component part (
Weight/Weight) A Water 3
．． 088 Surfactant Note (1) 1.595 Antifoaming agent Note (2) 0.016B Titanium dioxide pigment Note (3) 10.601C Water
1.029D Polyester Note (418,686 Styrene 4.817 Magnesium Oxide 0.045E
Water 1.647F
Hydroxyethyl cellulose Note (514,117 Poly(vinyl alcohol) solution Note (6) 6.175 Surfactant Note (1) 0.103 Water
30.934G water
24.701H Cumenehydroyloxide 0.206 Diethylenetriamine 0.0
51 Ferrous sulfate 0.003I Biocide Note (710,021 Ammonia solution Note (8)
0.165 Thickener Note (9)
2.000 Notes (1) to (9) above indicate the following.

(1) Ammonium salt of sulfated alkylphenoxypoly(ethyleneoxy)-ethanol with a solid content of 28% by weight (
GAFCo as product name “Adipal” Co-436
(commercially available from RP) (2) Antifoaming agent, trade name Foamaster' NS [(
(commercially available from Diamond Shamrock) or product name Bevaloid" 60 ([mperia
l chemical (industries PLC)
(3) Titanium dioxide pigment (trade name: TiPure” R90)
0 (commercially available from Du Pont) (4)
Propylene glycol/maleic anhydride/phthalic anhydride 3.74/2.3410.912 (mol) styrene solution with a solid content of 65% by weight (5)
Product name: Natrosol” 250HR (Hercul
(6) An aqueous solution of 7.5% solids content of Poval" 224G (commercially available from es company) with a solid content of 1.5% by weight. (7) Biocide, trade name Proxel" GXL (
Imperial chemical industry
(commercially available from es PLC) (8) Commercially available concentrated 0.
9 Ammonia solution (9) Product name Acrysol” A
SE-60 (commercially available from Rohm & Hass) An asterisk (*) indicates a registered trademark.

Some of the physical parameters of the granules obtained are shown in Table A.

Table A Density of dry granules 0.59 g/m1
% vesicularization rate (Ves 1culat 1on) Note (1165%
Solid content weight 21.2% solid content volume fi
36% maximum particle size Note (2)
12 micron median particle size
) 5.2 micron minimum particle size
Pore size of 3 micron vesicles Note (3)
Surface pores of 0.5-3.0 micron particles
< 0.2 micron particle wall thickness
0.1 to 0.5 micron Note (1) Vesiculation rate measured by mercury porosimetry (2) Particle size measured by laser diffraction granulometer (3) Inner diameter measured using scanning electron microscope In this example, the following terms are used.

The freeness (also called freeness) of a valve is a measure of the drainage rate from the valve, and the TA
PP 1 [Valve and Paper Technology Association (Technical
As5ociation of Pu1p and P
aper Industry) ) Standard T227a
m-75, called the Canadian Standard Freeness, and is measured in milliliters (-).

The opacity of paper 5sheet is expressed as contrast ratio opacity (C/R opacity) and is 572
Measured according to TAPP I standard T425om-81 using nanometer wavelength light.

The term handsheet is TAP
It is used for plain paper produced according to the PI standard T2O5om-81 and using the equipment described in that standard.

paper-like condition) is TAP
P [Exposure temperature of plain paper according to standard T405om-83 23.0°C ± 1°C and relative humidity 50.0% ± 2
．． 0% conditioned atmosphere.

The handsheet shown in Example 2 was made according to the following general method. The solids content in the final valve slurry is determined by macerating hardwood or softwood in water for 4 hours to obtain Canadian Standard Freeness (CS)
F) 400mj' or 600me I: Constructed of ref 1ned, fully bleached kraft hardwood or softwood bulbs. After refining, the bulbs were mixed together and then sectioned into individual pulp samples intended to yield target weights when loaded with fillers. The resulting valve sample was dispersed in water, and a cationic polymeric retention aid was added. The anionic polymeric retention aid was added after the filler, which included calcium carbonate and vesicularized polymeric granules, was added. The pH of the obtained papermaking furnish was adjusted to pH 7.8-8.2 by adding a predetermined amount of dilute sodium hydroxide.

The furnish is then passed through a sheet machine and the resulting handsheet is pressed and then conditioned.
(ned)

Example 2 The general method for making handsheet paper described above was carried out to prepare a number of different samples for testing of physical properties. The furnish for papermaking is fully bleached kraft hardwood/softwood (501
50) Valves and Polymeric Vesicularized Granules (abbreviated as PVG), Precipitated Calcium Carbonate (abbreviated as FCC)
and/or a filler or filler blend containing titanium dioxide (TiO□). C3F of hardwood valve is 4
00 ml, and the softwood C3F was 600 ml. FCC has an average grain size of 1.2 microns and has scalenohedral (scarfedron) crystal shape. Retention aids were commercially available cationic and anionic polyacrylamides. The physical properties of the various handsheets obtained were tested according to the TAPPI standard paper test method below.

T2200M-88 valve handmade paper physical test T403
Bursting strength T of 0M-85 paper 4940M-88 Tensile strength The results obtained are shown in Table B.

Handsheet Na16 in Table B is composed solely of fibrous material without containing pigments, fillers or vesicularized polymer particles and exhibits superior physical properties compared to other handsheets produced. However, this handmade paper is the most expensive of all of the above handmade papers because it consists only of pulp fibers, and it also has the lowest C/R opacity.

Handsheets kl-Nα15 are composed of calcium carbonate, titanium dioxide and/or vesicularized polymer granules, and their opacity is approximately equal, with opacity generally increasing as the total amount of filler is increased.

To compare the effect of vesicularized polymer granules on the physical properties of the handsheets produced, graphs of total amount of filler versus various physical properties are shown in Figures 1-6. That is, Figure 1 is a graph of filler content (%) versus tensile strength index, Figure 2 is a graph of filler content (%) versus length at break, and Figure 3 is a graph of filler content (%) versus % elongation. It is a graph of content (%), and Figure 4 is a graph of TE
Figure 5 is a graph of filler content (%) versus A index; Figure 5 is a graph of filler content (%) versus burst strength index; Figure 6 is a graph of filler content (%) versus tear strength index. It is a graph.

From FIG. 1, it can be seen that the tensile index of the tested handmade paper decreases as the amount of filler increases. The solid line shows the results obtained for handsheets Nα13 to Na15. Handmade papers Na13 to Na15 use only filler, and the filler used is precipitated calcium carbonate.

The dashed line shows the tensile strength index of handmade paper N (17 to Nα12). Handmade paper Nα7 to Nα12 contains calcium carbonate and titanium dioxide. The remaining points marked with Δ shown in FIG. The results are the tensile strength index of handsheets containing polymeric particulates.The handsheets are numbered N (L 1 to Magnetic 6) in Table B.

It is very clear that the above handsheets have better tensile strength than handsheets containing no particulates in the total amount of fillers.

Similarly, Figures 2 to 6 show the results obtained for length at break, % elongation, TEA index, bursting strength index and tear strength index against filler content (%) and vesiculation weight. Handsheets containing coalescing grains were in most cases superior to handsheets containing no grains.

[Brief explanation of the drawing]

The accompanying drawing is a graph of the total amount of filler for various physical properties to compare the effect of vesicularized polymer granules on the physical properties of the handsheet produced in Example 2;
Figure 1 shows the filler content (
%), Figure 2 is a graph of filler content (%) versus length at break, Figure 3 is a graph of filler content (%) versus % elongation, and Figure 4 is a graph of TEA Figure 5 is a graph of filler content (%) versus bursting strength index;
FIG. 6 is a graph of filler content jlt (%) versus tear strength index. The solid lines in FIGS. 1 to 6 are the results obtained for handmade paper N (L13 to 15) produced in Example 2, the broken lines are the results obtained for handmade paper Nα7 to Nα12, and △ is the result obtained for handmade paper Nα7 to Nα12. These are the results obtained for paper N11l-N (16). Length at break (K) Elongation (%) Tensile energy absorption index ○～○

Claims (1)

[Claims] 1. Alkaline paper containing a fibrous cellulose material, 1.0 to 10.0% by weight of vesicular polymer granules, and 5 to 35% by weight of calcium carbonate filler. . 2. The vesiculated granules have an average diameter of 1 to 100 microns, and the ratio of the diameter of the granules to the average diameter of the vesicles therein is at least 5:1; Paper according to claim 1, wherein the maximum diameter is 20 microns and the total volume of the vesicles is 5 to 95% of the volume of the granules. 3. The paper of claim 2, wherein the vesicularized granules have an average diameter of 1 to 50 microns. 4. The paper according to claim 1, containing 1.0 to 5.0% by weight of the vesicularized granules. 5. The paper according to claim 1, containing 10 to 25% by weight of calcium carbonate. 6. Claim 1, wherein the calcium carbonate is of a precipitated type.
, 2 or 3. 7. Paper according to claim 1, 2 or 3, which additionally contains a retention aid. 8. Paper according to claim 1, 2 or 3, additionally containing conventional papermaking fillers or pigments. 9. An alkaline aqueous composition comprising a fibrous material, 1.0 to 10% by weight of polymeric vesicularized granules, and 5 to 35% by weight of calcium carbonate filler, provided that the above weight % is the percentage based on the weight of paper produced from said composition). 10. The vesiculated granules have an average diameter of 1 to 100 microns, and the ratio of the average diameter of the granules to the average diameter of the vesicles therein is at least 5:1; 10. The alkaline aqueous composition of claim 9, wherein the maximum diameter of the vesicles is 20 microns and the total volume of the vesicles is 5 to 95% of the volume of the granules.