JPS59191711A - Production of cationic urea-formaldehyde polymer particle - Google Patents

Abstract

PURPOSE:To produce the titled particles useful as a filler exhibiting a high retention even in neutral paper making, by coagulating by reaction a precondensate comprising a basic nitrogen atom-containing compound, urea and formaldehyde with the aid of an acid catalyst. CONSTITUTION:The titled particles are produced by coagulating by reaction a precondensate comprising (A) a basic nitrogen atom-containing compound (e.g., diethylenetriamine), (B) urea and (C) formaldehyde, wherein the ratio of the number of equivalents of the basic nitrogen atoms of compound (A) to that number of moles of compound (B) is 0.05:1-0.6:1, and the ratio of the total number of moles of A and B to the number of moles of C is 1:1.1-1:2.0, with the aid of an acid catalyst (e.g., sulfuric acid). The particulate polymer can be used as a reinforcing filler or a white pigment for rubbers and thermoplastic resins such as PE, is especially useful as a filler for improving the opacity and whiteness of paper, and can exhibit a high retention even in neutral paper making.

Description

[Detailed description of the invention]

The present invention relates to a method for producing urea-formaldehyde polymer particles having cationic properties, and the cationic urea-formaldehyde polymer particles are suitable for use as cationic pigments and paper processing fillers, particularly as neutral papermaking fillers. Relating to a manufacturing method. More specifically, it is characterized in that it is obtained by reacting and coagulating an initial condensate of a compound having a basic nitrogen atom, urea and formaldehyde using an acid catalyst, and then reducing the free formaldehyde in a dispersed state and filtrating and concentrating it. The present invention relates to a method for producing ionic urea-formaldehyde polymer particles. In conventional paper making, sizing agents,
Paper strength agents, fillers, etc. have been used, and aluminum sulfate has been used as a fixing agent to fix these auxiliary materials to the paper layer. This mechanism is thought to be as follows. That is, aluminum sulfate forms a cationic polymer consisting of aluminum hydroxide in the papermaking water system, and this is adsorbed to the above-mentioned paper auxiliary materials having anionic or negative potential, resulting in the ionic or negative potential of the auxiliary materials. The potential is converted to positive. Therefore, the auxiliary raw material that has been converted to a positive potential is easily adsorbed to the pulp fibers having a negative potential. However, the use of aluminum sulfate, which has this fixing mechanism, makes the aqueous system of paper making acidic, so paper made in an acidic system lacks the durability for long-term storage. Therefore, it is desired to develop a method for producing paper in a slightly alkaline environment. On the other hand, it is already known in Tokko Kogyo Sho 51-23601 that urea-formaldehyde polymer particles are useful as paper fillers. However, if aluminum sulfate, which is a fixing agent, is not used during paper making, inorganic B pigments such as clay, titanium dioxide, etc.
The urea-formaldehyde polymer particles disclosed in No. 66B6 and the like were insufficiently retained in the paper layer, and as a result, the opacity, whiteness, etc. of the paper were insufficiently improved. The inventors of the present invention have conducted extensive research in order to obtain urea-formaldehyde polymer particles that have a high yield rate even in a system without a fixing agent such as aluminum sulfate, that is, in neutral papermaking. It was discovered that cationic urea-formaldehyde polymer particles obtained by reacting and coagulating an initial condensate of urea and formaldehyde with an acid catalyst exhibit a high yield in neutral papermaking, and the present invention was completed. That is, the present invention provides a compound (A) having a basic nitrogen atom,
Consisting of urea [B] and formaldehyde [c], [A
] Basic nitrogen atom equivalent number (hereinafter referred to as [a]): [B
] The ratio of the number of moles (hereinafter referred to as (b')) is 0.05:1 to 0.6:1, and [a] + [\]: [
A method for producing cationic urea-formaldehyde polymer particles characterized by coagulating an initial condensate having a molar ratio of 1:11 to 1:2o with an acid catalyst; In this method, as in the conventional method, the operation for reducing free formaldehyde is carried out by using urea or ammonia alone or in combination; A method of reusing it in the process before the coagulation operation can be applied. The present invention will be described in detail below. Compounds containing basic nitrogen atoms used in the present invention include, for example, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, propylene diamine, 3-azahexane-1,6
Examples include polyalkylenepolyamines such as diamine, N,N'-bis(3-aminopropyl)ethylenediamine, and hydroxylamines such as dimethylaminoethanol, jetanolamine, and triethanolamine, but only one type of these can be used. Needless to say, two or more of these compounds can be used in combination, and derivatives of these compounds having a basic nitrogen atom can also be used. In particular, polyalkylene polyamines are preferred compounds having a basic nitrogen atom. The initial condensate used in the present invention consists of a compound (A) having a basic nitrogen atom, urea [B] and formaldehyde [C], and the basic nitrogen atom equivalent number [a] of [A]: [B ] The number of moles [b] is 005:1 to 06:1
The reason why it is limited to the range is that (A
), the cationic nature of the cationic urea-formaldehyde polymer particles obtained will be low, and a good retention rate in the paper layer will not be observed when used in a neutral papermaking system. , and [a]:[b] is equivalent to 06:1, so CA]
This is because when the amount of water is high, the resulting polymer has strong hydrophilicity and does not form opaque water-soluble particles. Therefore, the preferable ratio of [a]:[b] is 0.07:1 to 0.5:
The range is 1. Furthermore, in the present invention, [a] used [b]: [C]
The reason why the ratio of the number of moles of [C] is limited to the range of 1:11 to 1:20 is that when the number of moles of [C], that is, the number of moles of formaldehyde, is smaller than 1:11, the final resultant positive This is because the performance of the ionic urea-formaldehyde polymer particles as a filler for paper processing, that is, the effect of improving the transparency and whiteness of processed paper is insufficient. Also, [:a':l +
(b]: The ratio of the number of moles of (0) is 1:20 [C]
This is because if the number of moles of formaldehyde is large, the yield of cationic urea-formaldehyde polymer particles, which is a water-insoluble component, decreases, which is not preferable for industrial production. Therefore (a) +
The preferable ratio of the number of moles of (b):[C] is 1:12 to 1:1
．． The range is 9. Compound CA'l with basic nitrogen atom, urea [PH3
-10°C at a reaction temperature of 20-95°C. The initial condensate thus obtained is usually an aqueous solution with a concentration of 2 to 60% by weight, and is measured by
The liquid viscosity at 5°C is usually less than 200 centipoise, preferably in the range of 2 to 200 centipoise. In addition, for long-term preservation of the initial condensate, acids such as hydrochloric acid, nitric acid, sulfuric acid, formic acid, acetic acid, etc., or caustic soda, caustic potash, ammonia,
The pH can also be adjusted to a range of 6 to 8 using an alkali such as ethanolamine or impropatulamine. As a step after obtaining the initial condensate, an acid catalyst is added for the purpose of reacting and coagulating the initial condensate while stirring. Acid catalysts suitable for this purpose include mineral acids such as sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, organic acids such as formic acid, oxalic acid, maleic acid, succinic acid and chloric acid, sulfamic acid, ammonium hydrogen sulfate, methyl hydrogen sulfate. Examples include acids such as ammonium, ethyl ammonium hydrogen sulfate, and hydroxyethylammonium hydrogen sulfate. The amount of these acids added is generally in the range of 1 to 30 weight percent, particularly 5 to 20 weight percent, based on the solid weight of the initial condensate consisting of a compound having a basic nitrogen atom, urea, and formaldehyde. Ru. When adding an acid catalyst, it is used in a water bath solution, usually 1 to 5
It is used in the concentration range of F3-Superior. Further, the solid content concentration range of the initial condensate at this time is 10 to 40% by weight, and the temperature of the initial condensate aqueous solution is set to a range of 5 to 95°C. When reacting and coagulating the initial condensate with an acid catalyst, more preferable results can be obtained by adding a water-soluble organic polymeric substance having a protective colloid effect to the initial condensate in advance. In this case, preferable water-based organic substances having a protective colloid effect (hereinafter referred to as protective colloid agents) include starch, natural products such as methylcellulose, ethylcellulose, and beta-hydroxyethylcellulose, or modified natural products such as polyvinyl alcohol and polyvinylpyrrolidone. Examples include synthetic polymers such as. The amount of protective colloid used is
Generally, a range of 01 to 8 weight units, particularly 02 to 5 weight units, is often used based on the weight of the reaction product of the compound having a basic nitrogen atom, urea, and formaldehyde. The protective colloid agent can be added at any stage before, during or after the formation of the initial condensate. When acidic acid is added to the initial condensate water bath solution under stirring for the purpose of reaction and coagulation, the reaction usually starts and coagulation occurs within a few minutes. Industrially, the initial condensate aqueous solution and the acid catalyst are mixed using an in-line mixer or the like, and immediately before the mixture solidifies, it is fed onto an extruder or a rotating endless belt to advance the reaction solidification. In this case, the time required for reaction and coagulation is within 60 minutes, and usually within several minutes. The thus obtained coagulate is dispersed into a slurry with stirring according to a conventional method, washed with water to reduce residual formaldehyde, neutralized, and coagulated in a pulverizer to an average particle size of 1 to 60μ, preferably 2 to 10μ. The bodies can be ground and used as pigments and fillers for paper processing. However, washing with water to reduce residual formaldehyde is carried out by repeating dispersion of the coagulated material in water and rinsing or centrifugation. - Formaldehyde reactants and water-soluble urea - Formaldehyde - Reactants of compounds with basic nitrogen atoms are removed. Therefore, removing residual formaldehyde by washing with water is not preferred from the viewpoint of improving the yield of the desired cationic urea and formaldehyde polymer particles, and furthermore, the drainage of the sap must be treated, which requires a large amount of cost. Therefore, in the present invention, as a method for reducing residual formaldehyde, after adding urea, ammonia or ammonium salt and reacting with the residual formaldehyde, a dispersion liquid containing water of 90 to 95% by weight is transported and For storage convenience, the liquid is concentrated by 1°C, and the liquid generated in this process contains relatively small amounts of water-bathable basic nitrogen-containing compounds, urea, formaldehyde, etc. Since reactants or reactants of these with ammonia or ammonium salts are included, a preferred method is to return the reaction system to the state before the coagulation of cationic urea-formaldehyde polymer particles is produced. When adding urea as the method for reducing residual formaldehyde described above, urea can be added as a solid bean or a water bath solution, and the pH of the dispersion at this time
is usually 40 or less. The amount of urea added is at least equimolar to the residual formaldehyde present in the aqueous phase of the dispersion, the reaction temperature is 10 to 70°C, and the reaction time is 5 to 30°C.
A range of minutes is sufficient. When the above-mentioned reduction of residual formaldehyde is carried out using ammonia or ammonium salt, ammonia or ammonium salt in the range of 05 to 40 mol per mol of residual formaldehyde is added to reduce the amount of formaldehyde from 10 to 10.
A reaction time of 5 to 100 minutes at 90°C is sufficient. After reducing the residual formaldehyde with urea, ammonia or ammonium salt as described above, the pH of the liquid is adjusted to 5 to 10, preferably 6 to 9, with a caustic soda aqueous solution or a sulfuric acid aqueous solution, and then further adjusted to a pH of 10 to 9,000. 1
A dispersion of cationic urea-formaldehyde polymer particles is obtained by stirring for a DO minute. Next, the above-mentioned dispersion liquid is dehydrated by P in order to make it into a cake shape.
This r-liquid is returned to the reaction system before the coagulum of cationic urea-formaldehyde polymer particles is produced. When the P solution is returned to the reaction system before the coagulation of cationic urea-formaldehyde polymer particles is produced, the F solution is returned to the reaction system containing basic nitrogen atoms (Al, urea, etc.). CB] and formaldehyde [C] as described above (al: (b) and [a] + [b
]: In order to satisfy [C], it is necessary to adjust the composition ratio of the initial condensate consisting of [A], [B] and [C] of the mixed oil-containing mixture. Usually, as the step in which the r-liquid is returned, one or both of the steps of diluting the initial condensate and the step of diluting the acid catalyst added to coagulate the cationic urea-formaldehyde polymer particles is employed. The cationic urea-formaldehyde polymer particles thus obtained can be used as reinforcing fillers in natural rubber, synthetic rubber, polyethylene and other thermoplastics, as white pigments, and in particular to improve the opacity and whiteness of paper. Useful as a filler for improvement. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 06 parts by weight of methyl cellulose (the following parts and related parts are based on weight) was dissolved in 660 parts of water (hereinafter referred to as water A), and to this was added 420 parts of a 57% formaldehyde aqueous solution and 15 parts of urea.
2 parts, diethylenetriamine 214 parts and 411 parts of 20q6 sulfuric acid aqueous solution were added, and the mixture was heated at 70°C at pH 7.0.
The reaction was carried out for 2 hours, and the ratio of [a]:[b] was 0.25.
: 1, 100 parts of an initial condensate with a molar ratio of [a]10[b':l:(C'l] of 1=165 was obtained.The concentration of this initial condensate was 664 h, The viscosity of 2500 measured by a Pruckfield viscometer was 5 (centipoise). Next, a 27% sulfuric acid aqueous solution was prepared by using 4 parts of a 98% sulfuric acid bath solution and 140 parts of water (hereinafter referred to as water B) to this initial condensate. After adding 144 parts and mixing, 3 parts at about 40°0.
After standing for 0 minutes, 244 parts of the gel-like material obtained was coarsely crushed using a stainless steel plate. 40 parts of water was added to this, and the mixture was stirred using a propeller type stirring blade for about 2 hours to form a slurry. Add 25 parts of 20% urea water bath solution to this,
After reacting for 20 minutes, caustic soda water bath solution i6. It was neutralized using part o. This was further pulverized in a colloid mill to obtain 325 parts of a dispersion containing cationic urea-formaldehyde polymer particles. This dispersion was separated into P using Toyo 2 Paper 5 people and Bützfner funnel.
76 parts of liquid f and 149 parts of a cake-like product (hereinafter referred to as Example 1 cake-like product) were obtained. As a result of analysis, the dispersion liquid contained 290 ppm of free formaldehyde. The F solution contained 0.07% formaldehyde and 0.67% urea, but most of the formaldehyde existed as a reaction product with urea. The cake-like material contained 173% cationic urea-formaldehyde polymer particles, and when this was dried and observed under an electron microscope, the diameter of the 6-order particles was less than 1 micron. Example 2 Next, an example will be shown in which the P liquid obtained by distributing the dispersion liquid from door to door is reused before the initial condensate is reacted and coagulated using an acid catalyst. First, 176 parts of the f solution obtained in Example 1 was mixed with 36 parts and 1
176 parts of liquid F and 149 parts of a cake-like material were obtained by the same operation and method as in Example 1, except that the mixture was divided into 40 parts and used in place of water A and water B in Example 1. In this case, the ratio of (a):(b) before solidification is 50, 23:1, and the ratio of the number of moles of [a] ten [b]:[c] is 1:1.56. there were. 149 parts of the resulting cake-like material contained 182 parts of cationic urea-formaldehyde polymer particles. This was dried and observed under an electron microscope, and the diameter of the secondary particles was 1 micron or less. Example 0.614 parts of methyl cellulose was dissolved in 440 parts of water, and to this was added 337 parts of formaldehyde aqueous solution No. 67 and 19 parts of urea.
3 parts, 0886 parts of triethylenetetramine and 150 parts of a 20% sulfuric acid aqueous solution to make the solution 7000 at pH 7.2.
The reaction was carried out for 2 hours, and the ratio of [a]:[b] was 0.07.
At 5:1, (a) +CM+:

100 parts of an initial condensate having a molar ratio of [0] of 1:12 was obtained. The concentration of the initial condensate with
The viscosity at 5°C was 48 centipoise. Next, 144 parts of a 27% sulfuric acid aqueous solution was added to this initial condensate, mixed, and left at about 40'O for 30 minutes to obtain a gel-like product 2.
44 parts were roughly crushed with a stainless steel rod. To this was added 640 parts of water and stirred for 2 hours to form a slurry. This slurry dispersion contains 5.
It contained 500 ppm free formaldehyde. Add 198 parts of 20% ammonia water to 200 parts of this dispersion.
(The molar ratio of ammonia to free formaldehyde at this time was 2:1) and the mixture was stirred at 40°C for 1 hour. Next, the dispersion 20 containing cationic urea-formaldehyde polymer particles was finely pulverized in a colloid mill.
Got 2 copies. By separating this dispersion liquid, 124 parts of R liquid and 78 parts of a cake-like material (hereinafter referred to as Example 6-cake-like material) were obtained. As a result of the analysis, the dispersion liquid contained 250
1) Contained I)m free formaldehyde. The cake-like material contained 20 inches of cationic urea-formaldehyde polymer particles, and when these were dried and observed under an electron microscope, the diameter of the primary particles was 1 micron or less. Example 4 065 parts of methylcellulose was dissolved in 297 parts of water, and 471 parts of a 37% formaldehyde aqueous solution and 122 parts of urea were added to the solution.
1 part, 685 parts of tetraethylenepentamine and 68 parts of a 20% sulfuric acid water bath solution were added, and the reaction was carried out at 70°C for 2 hours, and the ratio of [a]:[\] was 05:1, [a] ]+[\]:100 parts of an initial condensate having a molar ratio of [C] of 1=19 was obtained. The concentration of this initial condensate was 338 mm, and the viscosity at 25°C measured by a Pulckfield viscometer was 36 centipoise. Next, 2.7 polysulfuric acid water bath solution 144 was added to this initial condensate.
After mixing, 244 parts of the gel-like material obtained was left to stand at about 40°C for 30 minutes, and the resulting gel-like material was roughly crushed with a stainless steel rod. 40 parts of water was added to this and stirred for 2 hours to form a slurry. This slurry dispersion contained 8600 ppm of free formaldehyde. To 200 parts of this dispersion, 17 parts of a 20% urea water bath solution was added, and after reacting for 20 minutes, 487 parts of a 20% ammonia solution was added.
(The molar ratio of urea:ammonia:free formaldehyde at this time was 1:1:1) and stirring was carried out at 40°0 for 1 hour. The mixture was then finely pulverized in a colloid mill to obtain 222 parts of a dispersion containing cationic urea formaldehyde polymer particles. By separating this dispersion by f, 1455 parts of f
A liquid and 765 parts of a cake (hereinafter referred to as Example 4-cake) were obtained. As a result of analysis, the dispersion liquid contained 2701)l)m free formaldehyde. The cake contained 20% cationic urea-formaldehyde polymer particles, and when this was dried and observed under an electron microscope, the diameter of the primary particles was 1 micron or less. Comparative Example 1 Without using diethylenetriamine in Example 1,
[b]: [The amount of urea was increased to 188 parts so that the mole ratio of Ca was 1:165, and 20% caustic soda 05 was used instead of 411 parts of 20% sulfuric acid aqueous solution. A cake-like product (
149 parts (hereinafter referred to as Comparative Example 1 - cake-like product) were obtained. In addition, the dispersion liquid contains 295
Contained ppm of free formaldehyde. When the cake-like material was dried and observed under an electron microscope, the diameter of the primary particles was 1 micron or less. Comparative Example 2 A case where there are many compounds having basic nitrogen atoms will be exemplified. Dissolve 06 parts of methylcellulose in 284 parts of water and add 3 parts to this.
45.3 parts of formaldehyde water bath solution in Section 7, 120 parts of urea, 48 parts of diethylenetriamine, and 9 parts of sulfuric acid bath solution in Section 20.
Add 2 parts of Ca: ]: (b) to pH 7.3 and react for 2 hours at 70°C to obtain a ratio of 07=1.
So the ratio of moles of Ca) + [X): [0) is 1
: 100 parts of an initial condensate having a concentration of 1.65 were obtained. The concentration of this initial condensate is 33. At 5%, the viscosity at 25°C was 68 centiboise using a Pruckfield viscometer. Next, this initial condensate was added with a 27% sulfuric acid aqueous solution 14%
After adding 4 parts and mixing, the gel-like product obtained by leaving it for 30 minutes at about 4o0C was clear and opaque, whereas the gel-like products of Examples 10 to 4 and Comparative Example 1 were clearly opaque gel-like products. It was found that the sample was a transparent gel-like substance, and no particles, which is the object of the present invention, were formed. Comparative Example 3 A case where the amount of formaldehyde used is small will be illustrated. A cake-like product containing 17.D% of cationic urea-formaldehyde polymer particles (hereinafter referred to as Comparative Example 3-cake-like product) was prepared using the same conditions and method as in Example 1 except that 255 parts of 67% formalin was used in Example 1. 9)
Obtained 21 copies. When this was dried and observed under an electron microscope, the diameter of the primary particles was 1 micron or less. Comparative Example 4 A case where a large amount of formaldehyde is used will be illustrated. 1266 parts of a cake containing 19 parts of cationic urea-formaldehyde polymer particles was obtained under the same conditions and method as in Example 1, except that 536 parts of 37% formalin were used in Example 1. When this was observed under an electron microscope, the diameter of the primary particles was 1 micron or less. APPLICATION EXAMPLES The usefulness of the cationic urea formaldehyde polymer particles of the present invention obtained in Examples 1 to 4 will be illustrated by comparing them with the polymer particles obtained in Comparative Examples 13 and 4. Example 1 - cake-like 1156 parts (L, relative to the absolutely dry state of BKP) with a beating degree of a, s, p (Canadian, standard. After adding cationic urea-formaldehyde polymer particles (Part 10) and stirring for 2 minutes, paper is made using a square sheet machine and then dewatered using a press roll. Continued to press 3.0k
After 15 minutes of dehydration with ti/crA, the surface temperature was 1.
Dry with a drum dryer at 10°C. B
Each polymer particle-added paper was obtained by adding 10 parts to KP in an absolutely dry state. An additive-free paper was also obtained under the same conditions and method as the additive paper, except that no polymer particles were added. The obtained paper was conditioned for 24 hours in a constant humidity room with a humidity of 65% and a temperature of 20°C, and the basis weight, opacity, and yield rate of polymer particles on the paper were measured.Table 1 It was shown to. The basis weight of the obtained papers was 45.0, j9/n.
It was f. Also, the opacity is rIs (A of p-8138
Act). The retention rate of polymer particles in paper is calculated by determining the amount of polymer particles contained in the paper after paper making by nitrogen analysis with respect to the proportion of polymer particles added at the time of paper making. At the same time, the zeta of each polymer particle?
The 1N level was measured using a particle zeta potential measuring device (PEN, manufactured by Chem Co., Ltd.). In addition, the yield was determined by calculating the yield of polymer particles for compounds having basic nitrogen atoms, organic substances used as raw materials for initial condensation such as urea-formaldehyde, and protective colloid agents, and urea used to reduce free formaldehyde. . Both of these zeta potentials and yields are shown in Table 1. As shown in Table 1, the urea-formaldehyde polymer particles obtained from the examples according to the present invention have a positive zeta potential and are positive, and have a high yield, and can be used as paper fillers. In this case, it is recognized that the yield is high and the opacity is greatly improved. 4

Claims (1)

[Claims] (1) Compound (A) having a basic nitrogen atom, urea [B
] and formaldehyde [0], the ratio of the number of basic nitrogen atom equivalents [a] of [A]: the number of moles (b) of [B] is 0.05: 1-06: 1 (a:] + (
b): A method for producing cationic urea-formaldehyde polymer particles, which comprises reacting and coagulating an initial condensate with a mole ratio of (0) of 1=11 to 1:2o using an acid catalyst.