JPS59130398A - Composition for enhancing paper rigidity - 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 The present invention relates to a composition for improving the stiffness of paper, which is made by blending water glass with a polymer emulsion or latex.

Conventionally, when improving the stiffness of paper, urea formaldehyde resins, melamine formaldehyde resins, phenol formaldehyde resins, starch and its derivatives, acrylamide polymers, and the like have been used alone or in combination of two or more.

However, all of these are still insufficient in terms of their effect on improving stiffness.

As a result of extensive research into compositions for improving the stiffness of paper, the present inventors discovered that the composition of the present invention has an excellent effect of improving stiffness, and thus arrived at the present invention.

That is, the present invention is a composition for improving the stiffness of paper, which contains water glass and polymer emulsion or latex in a weight ratio of 10:90 to 95:5.

In the present invention, water glass is an alkali silicate, Me is potassium or sodium, and n is 1.0 to 4.
A range of 0 is common, and a range of 20 to 3.6 is more appropriate. These are usually handled as aqueous solutions, and commercially available solutions can be used.

Polymer emulsions or latexes are vinyl acetate emulsions, vinyl acetate-acrylic acid ester emulsions, Fl vinyl-ethylene emulsions, vinyl chloride and vinyl acetate or ethylene as the main raw materials, which are obtained by known polymerization and emulsification methods. vinyl chloride emulsion made from vinylidene chloride and (meth)acrylic acid as main raw materials, polyethylene emulsion, polypropylene emulsion, or styrene-butadiene latex (commonly known as 5B).
II (), methyl methacrylate-butadiene latex (commonly known as MBR), methyl methacrylate-styrene-butadiene latex (commonly known as MSBT ()), acrylonitrile-butadiene latex (commonly known as NBR)
), chloroprene latex (commonly known as CR), isoprene-based latex (commonly known as IR), polybutadiene (commonly known as P
B) is a polymer emulsion or latex, etc., but these polymer emulsions and latexes (hereinafter referred to as emulsions) contain copolymerization with other than the above-mentioned main raw materials in order to improve the physical properties of the resulting emulsion. There are many examples in which possible monomers are used, and it goes without saying that such emulsions can also be used in the present invention. Note that (meth)acrylic acid ester herein refers to an ester of acrylic acid or methacrylic acid and typically the following alcohol. That is, methyl alcohol, ethyl alcohol, methyl alcohol, ethylene glycol, 2-ethylhexyl alcohol, etc., but it goes without saying that esters of other alcohols are also similar.

The following monolayers can be mentioned as monolayers that can be copolymerized with the main raw material of the polymer latex, but these are only representative examples. All parts of the body can be used. That is, ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid, conjugated diolefins such as butadiene, isoprene, and chloroprene, and aromatic vinyl compounds such as styrene and methylstyrene. , the above-mentioned (meth)acrylic acid esters, ethylene-based nitrile compounds such as acrylonitrile, methacrylatetrile, acrylamide, methacrylamide, etc.
Monomers such as meth)acrylic acid amide, vinyl acetate, vinyl chloride, and vinylidene chloride.

In the present invention, the weight ratio of water glass to polymer emulsion and latex (hereinafter expressed as weight ratio unless otherwise specified) is limited to 10:90 to 95:5 for the following reasons. That is, when a composition containing water glass in a smaller proportion than 10:90 of water glass and polymer emulsion or latex is applied to the processing of paper for the purpose of the present invention, the stiffness improvement effect is insufficient. be. Furthermore, when a composition containing a smaller proportion of polymer emulsion or latex than the mixing ratio of water glass and polymer emulsion or latex of 95:5 is applied to the processing of paper for the purpose of the present invention, the purpose of improving stiffness is However, the resulting paper becomes brittle and cracks occur during box making. In other words, polymer emulsions and latexes impart flexibility that impairs the stiffness-enhancing effect of water glass. The blending ratio of water glass, polymer emulsion, and latex is preferably 10:90 to 9.
The range is 0:10. When water glass and polymer emulsion or latex are mixed, water is added directly to the polymer emulsion or latex, or water is added to the polymer emulsion or latex to bring the solid content concentration to 40% by weight, such as latte 5 = sox. The composition of the present invention is obtained by adjusting the concentration below and homogenizing it by adding water glass under stirring. Fluorine-based water repellents, paraffin-based water repellents, fatty acid-based water repellents, and silicone-based water repellents that are blended with resins to impart water resistance, or are water repellency imparting substances. Water repellency can also be imparted by adding a water repellent such as a water repellent.

The composition of the present invention is usually applied by spraying or roll coating after adjusting the solid concentration of polymer emulsion or latex and water glass to a range of 20 to 40% by weight, or by applying a method such as impregnation to paper. It can be used for processing.

The above-mentioned composition of the present invention exhibits usefulness when used in the processing of base paper for box making, such as cardboard atoms, white balls, manila balls, etc., or card atoms and other papers that require stiffness. be.

The present invention will be explained in more detail below using Examples and Comparative Examples. In addition, parts and percentages below are based on the weight basis unless otherwise specified.

Example 1 Vinyl acetate-ethylene emulsion 8102 with a solid content of 50% and pH 5.5 consisting of 85% vinyl acetate and 15% ethylene and Japanese Industrial Standards (hereinafter referred to as JTS)
Sodium silicate solution (SiO234-36%, Na2014-15
%) 11El and 72 liters of water were mixed at room temperature with stirring to obtain 100 [1f] of composition 1 for improving stiffness of paper (hereinafter abbreviated as composition 1) of the present invention.

This was a milky white aqueous solution with a solid content of about 45% and a Brookfield viscosity of 500 centiboise at 25°C.

Example 2 MSBR latex 42 with a solid content of 50% and a pi-T of 7.0 consisting of 30% styrene, 30% methyl methacrylate, 385% butadiene and 1.5% acrylic acid.
61, Sodium silicate solution 977, which is designated as Sodium Silicate No. 6 according to JTS, and water 4777 are mixed under stirring at room temperature to obtain a silk composition (hereinafter abbreviated as "composition") 1oooy for the stiffness of the paper of the present invention. Obtained.

This was a milky white aqueous solution with a solids content of approximately 25% and a Brookfield viscosity of 55 centipoise at 25°C.

Example 6 Styrene 25%, methyl methacrylate 10%, butyl acrylate 58%, β-hydroxyethyl methacrylate 2
%, methacrylic acid 2%, acrylamide 3% solid content 45%, pi (acrylic acid ester emulsion 589f of 7,2 and silicate soda 6 according to JIS)
A composition for improving the stiffness of paper (hereinafter referred to as composition ①) 1000!7' of the present invention was obtained by mixing 197 vol of a sodium silicate solution designated as No. 1 and 4147 ml of water under stirring at room temperature. This was a milky white aqueous solution with a solids content of about 25% and a Brookfield viscosity of 50 centipoise at 25°C.

Example 4 MSBR latex 607 with a solid content of 50% and a pH of 7.0, consisting of 60% styrene, 30% methyl methacrylate, 38.5% butadiene and 1.5% acrylic acid.
Sodium silicate solution 7117, which is designated as silica soda No. 6 according to JIS, and water 2291 were mixed under stirring at room temperature to obtain a composition for improving paper stiffness (hereinafter abbreviated as composition M) 1oooy of the present invention. This is a milky white aqueous solution with a solids content of approximately 60% and a Brookfield viscosity of 4 at 25°C.
It was 5 centipoise.

Application Examples The usefulness of the compositions for improving the stiffness of paper of the present invention obtained in Examples I to (2) was demonstrated in comparison with the comparative products shown below.

Here, as comparative materials, only the sodium silicate solution used in Example 111TIIIV (hereinafter referred to as comparative material 1), and then only the vinyl acetate-ethylene emulsion used in Example 2 (hereinafter referred to as comparative material 2). 20, further consisting of 95% acrylamide and 5% acrylic acid.
% solids The Brookfield viscosity of an aqueous solution is 6 at 25°C.
500 centipoise polyacrylamide polymer only (hereinafter referred to as comparative material 3), solid content 50% consisting of 60% styrene, 60% methyl methacrylate, 385% butadiene, and 1.5% acrylic acid. MSB of %l-11-I7.0
The test results are shown for the case where only R (hereinafter referred to as Comparative Material 4) was used and for the base paper.

Table 1 shows application examples of compositions 1 to 2 obtained in Examples 1 to 4 and comparative products 1 to 4 described above. Here, the base paper contains S
Composition 1 was prepared using a CP core with a basis weight of 12017 m.
~■, Comparatives 1 to 4 were each added to the base paper at a solid content of 10 f/
m' using a coating roll bar, and then curing the composition and comparative materials through a drum dryer at 110°C for 2 minutes, and then curing them at a constant temperature of 20°C and a constant humidity of 5% for 24 hours. Seasoned, JIS
- The compressive resistance value was measured by a ring crush test at a coating amount of 10 f'/m2 according to P8126.

In addition, for the cracking test, the above-mentioned paper material (coating amount: 10 r/m") was cut into test pieces of ID crn in the vertical direction and 5 m in the horizontal direction, and the test pieces were folded from the center and one metal plate was placed on each of the top and bottom. , press for 3 hours at a load of 5 Ky/cr;
A cracking test was conducted at a constant temperature of 20° C. and a constant humidity of 65%. The results are shown in Table 1.

Table 1 As shown in Table 1, the paper modification composition according to the present invention is
It is clear that this material has an excellent effect of improving stiffness.

Patent applicant Mitsui Toatsu Chemical Co., Ltd. 11- 606-1

Claims (1)

[Claims] A composition for improving the stiffness of paper, which is made by blending water glass and polymer emulsion or latex in a weight ratio of 10:90 to 95:5.