JP5234700B2 - Method for producing naphthalenesulfonic acid formaldehyde condensate - Google Patents

Description

  The present invention relates to a method for producing a naphthalenesulfonic acid formaldehyde condensate, a naphthalenesulfonic acid formaldehyde condensate or a water-soluble salt thereof, a cement dispersant containing the same, and a cement composition to which the same is added.

A water-soluble salt of naphthalenesulfonic acid formaldehyde condensate (hereinafter also referred to as naphthalene-based condensate salt) has been polymerized by a condensation reaction with formaldehyde and has been widely used for cement dispersants since the past (patents) Document 1, Non-Patent Document 1). When a naphthalene-based condensate salt is added as a cement dispersant to a cement composition, the fluidity of the composition is increased. As a result, it is known to show favorable effects such as a reduction in the water / cement ratio of the cement composition and an increase in concrete strength. Patent Documents 2 and 3 disclose reducing free or unreacted formalin in the production of a naphthalenesulfonic acid formaldehyde condensate.
Japanese Patent Publication No.41-11737 JP-A-4-211046 JP-A-5-320120 Annual Report on Cement Technology 1964 “Studies on Cement Dispersants” (pages 200-204)

  In recent years, sick house syndrome caused by formaldehyde has become a problem, and it is predicted that remaining unreacted formaldehyde will be a problem for naphthalene-based condensate salts. Such a cement dispersant containing a naphthalene-based condensate salt and a cement composition containing the same may be used as a product with stable quality, reduced formaldehyde released from a cured product, and low environmental impact. Be expected.

  As a method of reducing the amount of unreacted formaldehyde in naphthalene, in the condensation reaction of naphthalene sulfonic acid and formaldehyde, (1) reducing the amount of charged formaldehyde, (2) increasing the reaction temperature and increasing the reaction rate of formaldehyde , Etc. are conceivable.

  However, the method (1) not only prevents the polymerization, but also requires a significant extension of the condensation time to achieve a predetermined molecular weight. In general, in the production of naphthalene condensate, the condensation reaction is carried out in an aqueous system, so that the temperature of 100 to 105 ° C. or higher cannot be achieved by the method (2). In any case, in order to obtain a molecular weight as a cement dispersant, it is difficult to obtain a high molecular weight by the methods (1) and (2), and a predetermined dispersion performance cannot be obtained. It will be necessary to extend the time significantly.

  The present invention provides a method in which the amount of unreacted formaldehyde is reduced, the quality is stable, the load on the environment is small, and a naphthalenesulfonic acid formaldehyde condensate water-soluble salt suitable as a cement dispersant can be easily produced. Let it be an issue.

  The present invention includes a condensation reaction step (I) in which naphthalenesulfonic acid and formaldehyde are subjected to a condensation reaction, a step (II) in which sulfite is added to the reaction system containing the condensate obtained in the condensation reaction step (I), and The present invention relates to a method for producing a naphthalenesulfonic acid formaldehyde condensate having a step (III) of removing water insolubles from the reaction system of the step (II).

  Moreover, it is related with the manufacturing method of the water-soluble salt of a naphthalenesulfonic acid formaldehyde condensate which has these process (I)-(III) and neutralizes a condensate after the said condensation reaction process (I).

  The present invention also provides a naphthalene sulfonic acid formaldehyde condensate obtained by the production method of the present invention or a water-soluble salt thereof, a cement dispersant containing the naphthalene sulfonic acid formaldehyde condensate water-soluble salt, and cement, water And a cement composition containing the cement dispersant.

  Furthermore, the present invention provides a condensation reaction step (I) in which naphthalenesulfonic acid and formaldehyde are subjected to a condensation reaction, a step (II) in which sulfite is added to the reaction system containing the condensate obtained in the condensation reaction step (I), And a method for producing a cement dispersant composition, comprising removing the water-insoluble matter from the reaction system of step (II) (III), and neutralizing the condensate after the condensation reaction step (I) About.

  According to the present invention, there is provided a method in which the amount of unreacted formaldehyde is reduced, the quality is stable, the burden on the environment is small, and a water-soluble salt of a naphthalenesulfonic acid formaldehyde condensate suitable as a cement dispersant can be easily produced. . For this reason, the amount of unreacted formaldehyde is reduced, the quality is stable, and the load on the environment is small. The water-soluble salt of naphthalenesulfonic acid formaldehyde condensate, the cement dispersant containing the water-soluble salt, and the dispersant are contained. A cement composition can be provided.

  The present invention proposes a method for removing unreacted formaldehyde as a water-insoluble substance with sulfite, unlike the above-mentioned methods (1) and (2).

  That is, in the present invention, a condensation reaction step (I) in which naphthalenesulfonic acid and formaldehyde are subjected to a condensation reaction, and a step (II) in which sulfite is added to the reaction system containing the condensate obtained in the condensation reaction step (I). And a method for producing a naphthalenesulfonic acid formaldehyde condensate comprising a step (III) of removing water-insoluble matter from the reaction system of the step (II), or a condensation reaction step of condensing a naphthalenesulfonic acid and formaldehyde ( I), a step (II) of adding sulfite to the reaction system containing the condensate obtained in the condensation reaction step (I), and a step of removing water-insoluble matter from the reaction system of the step (II) ( III), and a method for producing a water-soluble salt of a naphthalenesulfonic acid formaldehyde condensate, wherein the condensate is neutralized after the condensation reaction step (I). After the condensation reaction completion of phosphate and formaldehyde, it is a reaction to the addition to unreacted formaldehyde sulphite intended to remove as water insolubles.

  The sulfite selected in the present invention is excellent in the ability to form a water-insoluble substance of formaldehyde and has a sufficient removal effect. Such effects cannot be sufficiently obtained with other inorganic salts. Therefore, it is not necessary to extend the conditions for the condensation reaction and the condensation time, and the amount of unreacted formaldehyde can be reduced. In the production method of the present invention, an aqueous solution in which a water-soluble salt of naphthalene sulfonic acid formaldehyde condensate is dissolved can be obtained, and thus it can be preferably used as it is for various uses, in particular, a cement dispersant.

  In the present invention, it is possible to obtain a water-soluble salt of a naphthalenesulfonic acid formaldehyde condensate having a formaldehyde content of 110 ppm (weight ratio basis, the same shall apply hereinafter) or less. That is, according to the present invention, a cement dispersant containing naphthalenesulfonic acid formaldehyde condensate having a formaldehyde content of 110 ppm or less and a weight average molecular weight of 10,000 or more or a water-soluble salt thereof can be provided.

  The sulfite used in the present invention is preferably a monovalent metal salt such as a sodium salt, or a divalent metal salt such as a calcium salt or a magnesium salt. In particular, the calcium salt removes formaldehyde as a water-insoluble substance. preferable.

  The amount of sulfite added is preferably 0.5 to 5 mol, more preferably 0.8 to 3 mol, particularly 1 to 1 mol of unreacted formaldehyde present in the reaction system after the condensation reaction. 3 mol is preferable from the viewpoints of reaction efficiency, burden in the filtration step, and reduction of the amount of unreacted formaldehyde.

  Furthermore, when manufacturing the water-soluble salt of a naphthalenesulfonic acid formaldehyde condensate, it is preferable from a viewpoint of corrosion prevention etc. of a container to neutralize a condensate after condensation reaction process (I). Neutralization is preferably performed before step (III). In step (II), a neutralizing agent is added together with sulfite to form and neutralize water-insoluble matter of unreacted formaldehyde. It is preferable. Neutralization is preferably performed from the viewpoint of suppressing corrosion of the storage container until the pH of the reaction system is in the range of 4 to 12 at 20 ° C. As the neutralizing agent, calcium hydroxide, sodium hydroxide, carbonate Calcium carbonate or the like is preferable from the viewpoint of the effect of adding sulfite and the effect of adding sulfite (effect of making unreacted formaldehyde water insoluble). The neutralizing agent is preferably added in an amount of 1.0 to 1.1 moles per each of naphthalenesulfonic acid and unreacted sulfuric acid. That is, the neutralizing agent is preferably added in an amount of 1.0 to 1.1 mol times relative to naphthalenesulfonic acid, and is preferably added in an amount of 1.0 to 1.1 mol times relative to unreacted sulfuric acid. Such a water-soluble salt is usually obtained as an aqueous solution in which the water-soluble salt is dissolved.

  An example of a method for producing a naphthalenesulfonic acid formaldehyde condensate water-soluble salt as a cement dispersant will be briefly described below.

  First, in order to obtain naphthalene sulfonic acid, it is made to react at 150-165 degreeC for 2 to 5 hours using 1.2-1.4 molar ratio of sulfuric acid with respect to 1 mol of naphthalene, and a sulfonated substance is obtained. Next, formalin is added dropwise at 85 to 95 ° C. over 3 to 6 hours to form 0.95 to 0.99 mol of formaldehyde with respect to 1 mol of the sulfonated product, and a condensation reaction is performed at 95 to 105 ° C. Perform [Step (I)]. Water, a neutralizing agent (for example, calcium carbonate) and sulfite are added to the condensate, and a neutralization step is performed at 80 to 95 ° C. and an unreacted aldehyde is converted into a water-insoluble matter [step (II) and neutralization]. . The neutralizing agent is preferably added in an amount of 1.0 to 1.1 moles per each of naphthalenesulfonic acid and unreacted sulfuric acid. Moreover, it is preferable to add 0.5-5 mol of sulfites with respect to 1 mol of unreacted formaldehyde. The amount of unreacted formaldehyde in the reaction system can be measured by the method of Examples described later. Thereafter, the water-insoluble matter is removed by a conventional method, preferably by filtration [Step (III)] to obtain an aqueous solution of a water-soluble salt of naphthalenesulfonic acid formaldehyde condensate. This aqueous solution can be used as a cement dispersant composition as it is or with other components added as appropriate. The solid content concentration of the aqueous solution is preferably 30 to 45% by weight for a cement dispersant, although it depends on the application. Further, if necessary, the aqueous solution can be dried and pulverized to obtain a powdery naphthalenesulfonic acid formaldehyde condensate water-soluble salt, which may be used as a powdery cement dispersant. Drying and powdering can be performed by spray drying, drum drying, freeze drying, or the like.

  The naphthalenesulfonic acid formaldehyde condensate or water-soluble salt thereof obtainable by the production method of the present invention preferably has a weight average molecular weight of 10,000 or more, more preferably 10,000 to 15,000. This molecular weight is measured by a liquid chromatography method (the standard substance is sodium polystyrene sulfonate).

  Moreover, about the naphthalenesulfonic acid formaldehyde condensate water-soluble salt, water-soluble means that an aqueous solution having a solid content concentration of 10% by weight or more can be prepared.

  When naphthalenesulfonic acid formaldehyde condensate is used as a cement dispersant, it is preferably 0.05 to 3 parts by weight, more preferably 0.1 to 2 parts by weight, and particularly preferably 0.2 to 1 part by weight with respect to 100 parts by weight of cement. .

  A cement composition is obtained by mixing the cement dispersant of the present invention, cement, and water. The water / cement weight ratio (W / C) is preferably 20 to 60%, more preferably 25 to 50%, and particularly preferably 30 to 45%.

  The cements include ordinary Portland cement, Belite cement, moderately hot cement, early strong cement, super early strong cement, sulfuric acid resistant cement, etc., and blast furnace slag, fly ash, silica fume, stone powder (calcium carbonate) Powder) or the like may be added.

  Furthermore, an aggregate can also be contained in a cement composition. Aggregates include sand and gravel. At that time, the hydraulic composition can be used as mortar or concrete.

  The cement composition of the present invention is used in the field of ready-mixed concrete, concrete vibration products, for self-leveling, for refractories, for plaster, for gypsum slurry, for lightweight or heavy concrete, for AE, for repair, for pre-packed, for trayy. It can be used for various concretes such as for grout, ground improvement, and cold.

  Naphthalene-based condensate salts were produced according to the following comparative examples and examples, and performance evaluation as a cement dispersant was performed. The results are shown in Table 1.

(Method for measuring the amount of unreacted formaldehyde)
The amount of unreacted formaldehyde in the reaction system was determined by dissolving 1 g of a reaction product containing a naphthalene-based condensate salt (solid content concentration: 40% by weight) in 100 ml of distilled water, and then adding 2-4-dinitrophenyl to this aqueous solution. A hydradone derivatization treatment was performed and quantified using liquid chromatography. As a standard substance, a 2--4-dinitrophenylhydradon derivative of formaldehyde was used. The measurement conditions of the liquid chromatography method are shown below.
・ Column type: L-Column-ODS (4.6φ × 150mm)
・ Eluent: Water / acetonitrile = 1/1
・ Flow rate: 1.0ml / min
・ Detector: UV360nm

(Molecular weight of naphthalene-based condensate salt)
The molecular weight of the naphthalene-based condensate salt was adjusted to a 0.2% aqueous solution, measured by a liquid chromatography method, and represented by a weight average molecular weight. The standard substance used was sodium polystyrene sulfonate. The measurement conditions of the liquid chromatography method are shown below.
・ Column type: G4000SW _XL + G2000SW _XL (7.8φ × 300mm)
-Eluent: 30 mM sodium acetate aqueous solution / acetonitrile = 6/4
・ Flow rate: 0.7ml / min
・ Detector: UV280nm

(Performance evaluation as cement dispersant)
The performance of naphthalene condensate salt as a cement dispersant was evaluated. 1000 g of ordinary Portland cement (manufactured by Taiheiyo Cement) and 1% by weight (converted to solid content) of a naphthalene-based condensate salt in 300 g of water are dissolved in 300 g of water at a low speed of 1 minute using a mortar mixer based on JIS-R5201. After mixing for 2 minutes at high speed, fill the Vicat needle cone. The cone surface was smoothed and the spread (mm) after lifting was measured.

Comparative Example 1
44 g of water was added to a sulfonated product obtained by reacting 1 mol of naphthalene with 1.28 mol of sulfuric acid at 150 ° C. to 160 ° C. for 3 hours, and 0.98 mol of formalin (37%) (as formaldehyde) Dripping over time. After the dropping, a condensation reaction was performed at 98 to 102 ° C. for 10 hours. The condensate was neutralized by adding water and a neutralizing amount of calcium carbonate. The pH after neutralization was about 6. Then, it filtered and the calcium salt (henceforth Ca salt) density | concentration of a naphthalene type condensate was adjusted to 40 weight% solid content. The amount of unreacted formaldehyde at this time was 660 ppm, and the molecular weight of the Ca salt was 13200. Performance evaluation as a cement dispersant was performed using the obtained aqueous solution.

Comparative Example 2
44 g of water was added to a sulfonated product obtained by reacting 1.28 mol of sulfuric acid with 1 mol of naphthalene at 150 ° C. to 160 ° C. for 3 hours, and 0.95 mol of formalin (37%) was added dropwise at 80 ° C. to 90 ° C. over 3 hours. To do. After the dropping, a condensation reaction was performed at 98 to 102 ° C. for 10 hours. The condensate was neutralized by adding water and a neutralizing amount of calcium carbonate. The pH after neutralization was about 6. Then, it filtered and it was set as Ca salt 40 weight% solid content. At this time, the amount of unreacted formaldehyde was 450 ppm, and the molecular weight of the Ca salt was 8500. Performance evaluation as a cement dispersant was performed using the obtained aqueous solution.

Comparative Example 3
44 g of water is added to a sulfonated product obtained by reacting 1 mol of naphthalene with 1.28 mol of sulfuric acid at 150 ° C. to 160 ° C. for 3 hours, and 0.95 mol of formalin (37%) is added dropwise at 90 ° C. over 3 hours. After the dropping, a condensation reaction was carried out at 98 to 102 ° C. for 18 hours. The condensate was neutralized by adding water and a neutralizing amount of calcium carbonate. The pH after neutralization was about 6. Then, it filtered and it was set as Ca salt 40 weight% solid content. At this time, the amount of unreacted formaldehyde was 410 ppm, and the molecular weight of the Ca salt was 11100. Performance evaluation as a cement dispersant was performed using the obtained aqueous solution.

Comparative Example 4
44 g of water is added to a sulfonated product obtained by reacting 1 mol of naphthalene with 1.28 mol of sulfuric acid at 150 ° C. to 160 ° C. for 3 hours, and 0.98 mol of formalin (37%) is added dropwise at 90 ° C. over 3 hours. After the dropping, a condensation reaction was carried out at 98 to 102 ° C. for 18 hours. The condensate was neutralized by adding water and a neutralizing amount of calcium carbonate. The pH after neutralization was about 6. Then, it filtered and it was set as Ca salt 40 weight% solid content. The amount of unreacted formaldehyde at this time was 440 ppm, and the molecular weight of the Ca salt was 16300. Performance evaluation as a cement dispersant was performed using the obtained aqueous solution.

Comparative Example 5
After performing the condensation reaction by the synthesis method of Comparative Example 1, water and neutralized amount of calcium carbonate and the amount of sodium carbonate relative to the amount of unreacted formaldehyde shown in Table 1 were added to the condensate for neutralization. The pH after neutralization was about 6. Then, it filtered similarly to the comparative example 1 and adjusted Ca salt to 40 weight% solid content. Table 1 shows the amount of unreacted formaldehyde and the molecular weight. Performance evaluation as a cement dispersant was performed using the obtained aqueous solution.

Examples 1-9
After conducting the condensation reaction by the synthesis method of Comparative Example 1, the condensate was neutralized by adding water, a neutralized amount of calcium carbonate, and the type shown in Table 1, an amount of sulfite with respect to the amount of unreacted formaldehyde. The pH after neutralization was about 6. Then, it filtered similarly to the comparative example 1 and adjusted Ca salt to 40 weight% solid content. Table 1 shows the amount of unreacted formaldehyde and the molecular weight. Performance evaluation as a cement dispersant was performed using the obtained aqueous solution.

* In Table 1, the addition amount of sulfite is the addition amount (mol) per mol of unreacted formaldehyde.

Claims (8)

A condensation reaction step (I) in which naphthalenesulfonic acid and formaldehyde are subjected to a condensation reaction;
A step (II) of adding a sulfite selected from calcium sulfite, magnesium sulfite and sodium sulfite to the reaction system containing the condensate obtained in the condensation reaction step (I), and a reaction system of the step (II) Having a step (III) of removing water insolubles by filtration;
In step (II) after the condensation reaction step (I), 0.5 to 5 mol of the sulfite is added to 1 mol of unreacted formaldehyde present in the reaction system after the condensation reaction, and the sulfite is added. In addition, neutralize the condensate by adding calcium carbonate as a neutralizing agent,
A method for producing a water-soluble salt of a naphthalenesulfonic acid formaldehyde condensate.   The method for producing a water-soluble salt of a naphthalenesulfonic acid formaldehyde condensate according to claim 1, wherein the neutralization is carried out until the pH is in the range of 4 to 12 at 20 ° C. The process according to claim 1 or 2, wherein the sulfite is a sulfite selected from calcium sulfite and magnesium sulfite . Calcium carbonate neutralizing agent, 1.0 to 1.1 moles per mol of naphthalene sulfonic acid, adding 1.0 to 1.1 moles per mol of unreacted sulfuric claim 1-3 The manufacturing method of 1 item | term. Claim 1-4 naphthalenesulfonic acid formaldehyde condensate or a water-soluble salt thereof obtained by the method according to any one. A cement dispersant containing the water-soluble salt of naphthalenesulfonic acid formaldehyde condensate according to claim 5 . A cement composition comprising cement, water and the cement dispersant according to claim 6, wherein the cement dispersant is contained in an amount of 0.05 to 3 parts by weight with respect to 100 parts by weight of the cement, and the water / cement weight ratio is Cement composition that is 20-60%. A condensation reaction step (I) in which naphthalenesulfonic acid and formaldehyde are subjected to a condensation reaction;
A step (II) of adding a sulfite selected from calcium sulfite, magnesium sulfite and sodium sulfite to the reaction system containing the condensate obtained in the condensation reaction step (I), and a reaction system of the step (II) Having a step (III) of removing water insolubles by filtration;
In step (II) after the condensation reaction step (I), 0.5 to 5 mol of the sulfite is added to 1 mol of unreacted formaldehyde present in the reaction system after the condensation reaction, and the sulfite is added. In addition, neutralize the condensate by adding calcium carbonate as a neutralizing agent,
A method for producing a cement dispersant composition.