JPS59144694A - Composition for enhancing compression strength of 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 The present invention relates to a composition for improving the compressive strength of paper that has high concentration, low viscosity, and excellent workability. The present invention relates to a composition for improving the compressive strength of paper.

Conventionally, improving the compressive strength by increasing the stiffness of paper has been achieved using urea-formaldehyde resin, melamine-polmaldehyde resin,
Thermosetting resins such as phenol-formaldehyde resins,
Polymerizable polymer compounds such as modified starch-based carboxymethyl cellulose and hydroxyethyl cellulose have been studied, but they have not been used because they each have the following drawbacks. That is, when paper is processed with a thermosetting resin such as urea-formaldehyde resin, melamine-formaldehyde resin, or phenol-formaldehyde resin, the paper can be made hard, but it has the disadvantage that it becomes brittle and easily breaks when bent.

Semi-synthetic products such as polyester modified starch, carboxymethyl cellulose, and hydroxyethyl cellulose, and polymerizable polymer compounds such as polyvinyl alcohol and polyacrylamide are generally used as aqueous solutions, but their viscosity is high, so it is necessary to improve workability. Therefore, it becomes necessary to adjust the concentration to a low level by diluting it with water. As a result, in order to impregnate paper with a predetermined amount of semi-synthetic products or polymeric polymer compounds by spraying or coating it, a large amount of dilution water is also impregnated at the same time, and a large amount of drying water is required in the subsequent drying process. This method requires energy and, although the paper can be made hard, it becomes brittle and easily breaks when folded.

In order to solve the above-mentioned drawbacks, the present inventors have continued to conduct intensive research with the aim of obtaining a composition that is highly concentrated, has low viscosity, and can improve compressive strength without increasing brittleness when processed into paper. As a result, it was discovered that a composition obtained by polymerizing methacrylamide in the presence of a polymer latex having a glass transition point of 60°C or less can achieve these objects, and in order to complete the present invention. It has arrived.

That is, the present invention provides a composition obtained by polymerizing methacrylamide (B"l) in the presence of a polymer latex having a glass transition point of 600C or less, which comprises the above (A): (B)
This is a composition for improving the compressive strength of paper, characterized in that the weight ratio is 97:3 to 40:60.

According to a preferred embodiment of the invention, the glass transition temperature is 6
A composition obtained by polymerizing methacrylamide (B) in the presence of water using a radical polymerization method in the presence of a polymer latex (A) at a temperature of 0°C or lower, wherein The gravity ratio is 97:3 to 40:60, preferably 95:5 to 50
:50.

The reason why the composition according to the present invention is able to achieve the object of the present invention is not necessarily clear, but the reason is that methacrylamide, which has a functional group that easily forms a hydrogen bond with the valve fiber, is generated when polymer latex undergoes graft polymerization. It is presumed that this is due to the fact that methacrylamide homopolymer is easily adsorbed to polymer latex, and this is considered to be a contributing factor.

Note that the glass transition point (Tg) is a temperature calculated using the following formula [1].

1 / (T g +273 ) = ΣWi / (T g
i +273 )...(1) The present invention will be described in detail below.

The polymer latex used in the present invention refers to SBR, MBf (,, M-8
Bf also includes Ni2B, CR, III, and synthetic comb latex such as polybutadiene, vinyl acetate emulsion, vinyl acetate-acrylic emulsion, vinyl acetate-ethylene emulsion, and hyacrylate emulsion emulsion latex, vinyl chloride. type latex, vinylidene chloride type latex, etc., and the glass transition point of these polymer latexes is 60°C.
It is necessary that the following is true. Preferably it is 40°C or less. If the glass transition point of the polymer latex exceeds 60'C, there remains the disadvantage that paper processed with the resulting composition tends to crack when folded.

In the polymer latex, the SDR latex contains styrene, butadiene, Mi3 lateratex, methyl stacrylate and butadiene, and the MSBR latex contains methyl methacrylate, styrene, butadiene, and N13.
1 (The latex uses acrylonitrile and butadiene,
C11, latex uses chloroprene, 11 latex uses isoprene, polybutadiene latex uses butadiene, vinyl acetate-acrylic emulsion contains vinyl acetate and acrylic esters (methyl, ethyl, phthyl,
2-ethylhex-carare), methacrylic acid esters (methyl, ethyl, butyl).

Vinyl acetate-ethylene emulsion latex contains vinyl acetate and ethylene, and acrylic ester emulsion latex contains acrylic esters (methyl, ethyl, etc.).

butyl, 2-ethylhexyl), methacrylate esters (methyl, ethyl, phthyl-2-ethylhexyl), etc. Vinyl chloride-based latex uses vinyl chloride, vinyl acetate, or ethylene, vinylidene chloride-based latex uses vinylidene chloride, vinyl chloride, acrylic acid, etc. Although esters are used as the main raw materials, in addition to these main raw materials, the following monomers that can be copolymerized with these main raw materials can also be used to improve the physical properties of the resulting polymer latex. Needless to say, a polymer latex improved by the above method can also be used as the polymer latex used in the present invention.

In other words, there are a number of monomers that can be copolymerized with the main raw materials of each of the polymer latexes mentioned above, but these are just examples, and there are also monomers that can be copolymerized with the main raw materials. Needless to say, any amount can be used. These monomers for improving physical properties may be copolymerized with the polymer latex in advance, or in some cases, they may be used in combination when methacrylamide is polymerized in the presence of the polymer latex. good.

That is, the above monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itabonic acid, maleic acid, fumaric acid, and crotonic acid, butadiene, isoprene,
Conjugated olefins such as chlorobrene, aromatic vinyl compounds such as styrene and methylstyrene, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl oxacrylate, methyl acrylate, and acrylic. Ethyl acid, Aku I
J) Acrylic acid esters such as butyl phosphate and 2-ethylhexyl acrylate, ethylene-based nitrile compounds such as acrylonitrile and methacrylnitrile, β-hydroxyethinoacrylate, β-hydroxyethyl methacrylate, acrylamide, methacrylamide, I'J
- methylol acrylamide,
To the cloud H N-methylol methacrylamide, N-
Hydrophilic monomers such as butoxymethylacrylamide, glycidyl acrylate, glycidyl methacrylate, cationic vinyl monomers such as dimethylamine ethyl methacrylate, trimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, trimethylaminoethyl methacrylate 1/, --) monomers, vinyl acetate, vinyl chloride, vinylidene chloride, etc.

The feature of the present invention is that in the presence of a polymer latex prisoner with a glass transition point of 60°C or less, methacrylamide [■3] is added at a solid content weight ratio (A, l: CB) of 97:3 to 40:
60, and thus (A3:
(The reason for specifying the ratio of +33 is as follows. That is, the ratio of polymer latex to methacrylamide is 97:3.
When the proportion of polymer latex becomes larger, the compressive strength of the paper processed by the final composition is insufficiently improved. Furthermore, if the ratio of polymer latex to methacrylamide is greater than 40:60, the viscosity of the final composition becomes high, which is unfavorable in terms of workability, and even more unfavorable.

In order to obtain the composition according to the present invention, a method of polymerizing methacrylamide in the presence of a polymer latex can be carried out by a method of polymerizing only methacrylamide. That is, radical polymerization is carried out using only a peroxide such as potassium, sodium, or ammonium salt of persulfate, or hydrogen peroxide, or the above-mentioned peroxide and a reducing agent such as acidic sodium sulfite or sodium thiosulfate. However, radical polymerization is carried out using only the above-mentioned peroxide until the middle of the polymerization, and then the above-mentioned reducing agent or trialkylamines such as trimethylamine, triethylamine, triethanolamine, etc. Polymerization is proceeded by adding trialkanolamines, dialkylamines such as dimethylamine, diethylamine, dialkanolamines such as ethanolamine, monoalkylamines such as butylamine, monoalkanolamines such as monoethanolamine, etc. You can also do that.

The above amine compounds are just examples, and it goes without saying that other primary, secondary, and tertiary amine compounds can be used in the same manner.

The composition according to the present invention obtained after the polymerization is neutralized using caustic soda, caustic potash, ammonia, and the above amine compound acids, or an acid such as sulfuric acid, nitric acid, formic acid, acetic acid, or hydrochloric acid to make it durable for long-term storage. You can also do it.

The composition for improving the compressive strength of paper according to the present invention can be used to improve the compressive strength of paper that undergoes a paper folding process such as a high-quality box process.

It's not something you can do.

Example 1 720 parts of vinylizohene chloride latex (Tg is 32°C) with a solid content of 45 parts and a pH of 6.8 (Tg is 32°C) consisting of 60% by weight of vinyl chloride and 40% by weight of vinylidene chloride, and 25 parts by weight of distilled water.
1 part of methacrylamide and 17 parts of methacrylamide were placed in a flask equipped with a condenser, a stirrer, and a thermometer, and the following operations were performed while stirring. First, warm the flask and bring the temperature of the liquid inside the flask to 5.
Raise the temperature to 0'C. Next, 6.0 parts of potassium persulfate and 5
Adding 6.0 parts of 0% by weight triethanolamine to 1
Carry out the polymerization reaction for 0 hours. As a result, the solid content was 35% by weight.
, a composition for improving the compressive strength of paper according to the present paper invention having a Pulckfield viscosity of 180 centivoids at 25°C (hereinafter referred to as
100 parts of composition (denoted as ■) were obtained.

Example 2 Styrene 30% by weight, methyl methacrylate 30% by weight,
Solids content 50% by weight consisting of 38.5 parts by weight of butadiene and 1.5 parts by weight of acrylic acid, I) MS of 117.0
T3 R latex (T g is -1°G) 475.
3 parts, distilled water 408.8 parts, methacrylamide 101.
Pour 9 parts into a flask equipped with a cooling tube, a stirrer, and a thermometer, and perform the following operations while stirring.

First, the flask is heated to raise the temperature of the liquid inside the flask to 50°C. Next, 7.0 parts of potassium persulfate was added and 1
．． After carrying out the polymerization reaction for 5 hours, 7.0 parts of 50% by weight jetanolamine was added and the polymerization reaction was further carried out for 8.5 hours. As a result, a composition for improving the compressive strength of paper according to the invention of this paper (hereinafter referred to as Composition-II) had a solid content of 35% by weight and a Pulckfield viscosity of 190 centivoise at 25°C.
100 parts were obtained.

Example 3 Methi 9F 25% by weight, methyl methacrylate 10% by weight,
Solid content: 45% by weight, consisting of 58% by weight of butyl acrylate, 2% by weight of β-hydroxyethyl methacrylate, 2% by weight of methacrylic acid, and 3% by weight of acrylamide, P) 16
．． 8 acrylic ester latex (Tg is -10
G) 372.2 parts, 167.5 parts of methacrylamide, and 440.3 parts of distilled water are placed in a flask equipped with a cooling tube, a stirrer, and a thermometer, and the following operations are performed while stirring.

First, the flask is heated to raise the temperature of the liquid inside the flask to 50°C. Next, 10 parts of potassium persulfate and 10 parts of 50% diethylamine were added, and a combination reaction was carried out for 10 hours. As a result, the composition for improving the compressive strength of paper according to the present invention (hereinafter referred to as composition = I11) had a solid content of 35 weight - 11 t (%) and a Pulckfield viscosity of 250 centivoids at 25°C.
Obtained 1000 copies.

Comparative Example 1 Styrene 40% by weight, methyl methacrylate 42tt%,
An acrylic acid ester latex of PI-16,8 (Tg: 69°C) with a solid content of 50% by weight consisting of 3% by weight of acrylic acid and 15% by weight of butyl acrylate was used as the SB Silatex in Example 2. 1000 parts of a comparative composition (hereinafter referred to as Comparative Example-1 composition) was obtained in exactly the same manner except that Tg was used instead of -1°C. Comparative Example - The composition had a solids content of 35% by weight and a Pulckfield viscosity of 195 centiboise at 25°C.

Comparative example 2 A case where the amount of tacrylamide is small will be exemplified.

That is, the MSBR used in Practical Example 2 (Tg is -1°C) 68
0 parts, 310 parts of distilled water, and 7 parts of methacrylamide were added to the flask used in Example 2, and the following operations were performed while stirring.

First, the flask is heated to raise the temperature of the liquid inside the flask to 50°C. Next, add 2 parts of potassium persulfate (1.
After carrying out the polymerization reaction for 5 hours, 2 parts of 50% by weight jetanolamine was added and the polymerization reaction was further carried out for 8.5 hours.

As a result, 100 parts of a comparative composition (hereinafter referred to as Comparison Example-11 composition) having a solid content of 35% by weight and a Pulckfield viscosity of 3.5 centivoise at 25° C. was obtained.

Comparative example 3 A case where the amount of tacrylamide is large will be exemplified.

That is, 232.4 parts of the MSf3R latex used in Example 2 (Tg is -1°C), 527.8 parts of distilled water, and 215.8 parts of methacrylamide were added to the flask used in Example 2 and stirred. While doing so, perform the following operations.

First, the flask is heated to raise the temperature of the liquid inside the flask to 50°C. Next, 12 parts of potassium persulfate was added and a polymerization reaction was carried out for 1.5 hours.
The polymerization reaction was further carried out for 8.5 hours. As a result, 1000 parts of a comparative composition (referred to as 1-T Comparative Example-111-composition) having a solid content of 35% by weight and a Pulckfield viscosity of 1050 centipoise at 25°C was obtained.

Application Examples Regarding the usefulness of the compositions for improving the compressive strength of paper of the present invention obtained in Examples 1 to 3 Comparative Example 1 Comparative Examples obtained in Examples 1 to 3 and the following compositions This will be illustrated by comparison with conventionally used polyacrylamide and melamine-formaldehyde resins.

The solid content of polyacrylamide, which has been considered so far, is 2.
At 0 weight it%, the Pruckfield viscosity is 250G and 350
0 centimeters (product name: Xantax C8-18)
: manufactured by Mitsui Toatsu Chemical Co., Ltd.) and a melamine-formaldehyde resin with a solid content of 80% by weight and a Purckfield viscosity of 1050 centibois at 25°C (trade name Neelamine P-6300: manufactured by Mitsui Toatsu Chemical Co., Ltd.) )
was used.

First, Examples 1 to III compositions, Comparative Examples I to III
= The composition, polyacrylamide, and melamine-formaldehyde resin are each diluted with distilled water to a solid content of 5 g. Next, the weight ratio of SCP to cardboard waste paper was 50:50, basis weight 125 g/m'', JI
A base paper with a Steckigt sizing degree of 15 to 16 seconds as defined in the S standard (P-8122) was cut into 25 CrIL x 30 cIn squares and the weight was measured, and the weight was 9,375. Next, the above-mentioned cut base paper was immersed in a 5% diluted composition (solid content weight) for 5 minutes, squeezed between two rolls, and its weight was measured, and the result was 18.759. This was dried for 30 minutes at room temperature and then dried for 2.5 minutes using a drum dryer with a surface temperature of 110°C to obtain a composition-① processed paper. In addition, in this operation, instead of using a diluted solution of the above-mentioned composition -1 with a solid content of 5% by weight, compositions -1, Elf, and Comparative Example-
■～III Unless a diluent with a solid content of 5% by weight is used for MJ products, polyacrylamide, melamine-formaldehyde resin, etc., the weights measured by squeezing between rolls after being immersed in the diluted solution may also be the same. Composition = II, Ill, Comparative Example -■, 1■,
III. Each processed paper with composition, polyacrylamide and melamine-formaldehyde resin was obtained. These processed papers were seasoned for 24 hours in a constant humidity and constant room at a relative humidity of 65 degrees and a temperature of 20°C, and then tested for compressive strength and cracking.

The compressive strength was measured according to the compressive strength testing method specified in the JIS standard (P-8125). For the cracks, cut each piece of processed paper into a 57B,
After bending 180° to form a corner and pressing for 5 minutes at a pressure of 3 kl/d, the piece was removed from the press and the degree of cracking at the bent portion was visually judged.

It can be seen that the glass transition point of the polymer latex affects the cracking of the processed paper, demonstrating the superiority of the present invention. Furthermore, it is clear from the composition (1) and the comparative example (2) that the usefulness differs greatly depending on the solid weight ratio of polymer latex and methacrylamide, and furthermore, there is a clear difference in usefulness.
It can be seen that the scope of the present invention is excellent. Conventionally studied polyacrylamide and melamine-formaldehyde resins are inferior to the composition of the present invention in terms of cracking of processed paper, and polyacrylamide is also inferior in terms of high viscosity.

It is clear from this example that the composition according to the invention has a low viscosity and can impart high compressive strength to the paper without leaving it brittle enough to break easily.

Claims (1)

[Claims] Polymer latex (A) with a glass dislocation point of 60°C or less
A composition obtained by polymerizing methacrylamide [13] in the presence of a paper, characterized in that the solid weight ratio of (A):(B) is 97=3 to 40:60. Composition for compressive strength.