JP2996366B2 - Dicyandiamide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is used as an intermediate material for producing melamine, guanamine, guanidine derivatives and the like, as well as a flame retardant, a dyeing aid, a nitrification inhibitor for fertilizer,
The dicyandiamide, which can be used as an epoxy curing agent and the like, in which the occurrence of inconvenience such as caking during storage is suppressed, specifically, dicyandiamide obtained by crystallizing dicyandiamide in the presence of modified polyvinyl alcohol, A dicyandiamide whose primary crystal has a specific X-ray diffraction angle intensity ratio in a specific range.

[0002]

2. Description of the Related Art Dicyandiamide (hereinafter sometimes abbreviated as DICY) is an extremely useful compound used for various applications as described above, but has a disadvantage that it is easily condensed during storage. In such a case, there is a problem that economic disadvantages are unavoidable in work such as crushing the solidified material, and several methods have been proposed to solve the problem. DI in the presence of compound
A method using a so-called habit modifier to crystallize CY is also known.

[0003] As a method using the above-mentioned habit modifier, for example, JP-A-59-101455 discloses "dicyandiamide,
A method for improving the crystal form of dicyandiamide characterized by crystallizing in the presence of 0.001 to 10% by weight of polyvinyl alcohol and / or a water-soluble cellulose ether derivative based on dicyandiamide, It is said to be "a slab or rhombohedron and a truncated pyramid or a rice grain crystal".

However, the above proposal only discloses fully saponified PVA or partially saponified PVA as polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) as a habit modifier, but does not disclose sulfonic acid groups or carboxyl groups. There is no disclosure of denatured PVA in which such is introduced into the molecule. In addition, in the additional tests performed by the present inventors on the above proposed method, the reason is unknown, but the obtained DICY
Was not as described above, and the improvement of the solidification during storage was insufficient.

[0005]

SUMMARY OF THE INVENTION The present inventors have conducted research to improve the above-mentioned problem, that is, to improve solidification during storage. As a result, among PVA as a habit modifier, for example, sulfone DICY obtained by crystallizing in the presence of a modified PVA having ionic groups such as acid groups in its molecule often does not cause caking during storage, The primary crystal having no DICY was found to have a specific X-ray diffraction angle intensity ratio in a specific range, and completed the present invention.

[0006]

The present invention relates to a dicyandiamide obtained by crystallizing dicyandiamide in the presence of a modified polyvinyl alcohol, wherein the primary crystal has a diffraction angle intensity at an X-ray diffraction angle 2θ = 14.9 °. _1, it is an object to provide a dicyandiamide, wherein the 2 [Theta] = intensity ratio 1 _{1/1 2} of 26.3 ° diffraction angle strength 1 ₂ is 0.3 or less.

Hereinafter, the present invention will be described in detail.

[0008] The modified PVA used in the present invention is a completely or partially saponified PVA having an ionic group in the molecule. As such modified PVA, as an ionic group,
For example, anionic groups such as sulfonic acid groups and carboxyl groups; for example, primary amine groups, secondary amine groups, tertiary amine groups or quaternary ammonium groups, pyrimidine groups or pyrimidinium groups, imidazole groups or imidazolinium groups, PVA having a cationic group such as a sulfonium group and a phosphonium group; and the like can be exemplified.

Among them, the modified PVA which can be suitably used in the present invention is a modified PVA having an anionic group, and the use of a modified PVA having a sulfonic acid group is particularly preferred.

In place of these modified PVAs, non-modified PVA
When VA is used, even if the obtained DICY crystal satisfies the range of the specific X-ray diffraction angle intensity ratio described below, the effect of improving the solidification during storage is still insufficient. .

The modified PVA having a sulfonic acid group is as follows:
For example, it can be produced by copolymerizing a copolymerizable monomer having a sulfonic acid group with vinyl acetate and then saponifying it by a known method.

Examples of the above-mentioned copolymerizable monomer having a sulfonic acid group include vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, ammonium or alkali metal salts thereof, and monomers of the following general formula (1): The body can be exemplified.

[0013]

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(Where X is O or NH, R ¹ is H or CH ₃ , R ² is a linear or branched alkylene group having 2 to 8 carbon atoms, and M is H, ammonium or an alkali metal. )

Examples of the monomer represented by the general formula (1) include acrylamide ethanesulfonic acid and acrylamide
-1,1-dimethylethanesulfonic acid, acrylamide-1,2-
Dimethylethanesulfonic acid or methacrylamide-2,2-
(Meth) acrylamidosulfonic acids such as dimethylethanesulfonic acid or ammonium salts or alkali metal salts thereof;

For example, acryloxy-1,1-dimethylethanesulfonic acid, acryloxy-1,2-dimethylethanesulfonic acid or methacryloxy-1,1-dimethylethanesulfonic acid, or an ammonium salt or an alkali metal salt thereof. (Meth) acryloxyethanesulfonic acids;
And the like.

Further, as the modified PVA having an anionic group which can be preferably used as a habit modifier in the present invention, a part of the above-mentioned vinyl acetate is, for example, ethylene,
Olefin monomer such as propylene; for example, a vinyl monomer of saturated fatty acid other than vinyl acetate such as vinyl formate, vinyl propionate, vinyl versatate (trade name, saturated branched fatty acid vinyl having an average carbon number of 9 to 10) Body; for example, (meth) acrylate monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate;
And the like can be exemplified.

Further, the average degree of polymerization of the modified PVA which can be suitably used in the present invention is generally from 150 to 5,000, especially from 50 to 5,000.
It is good to be 0-2000.

The DICY of the present invention is generally obtained by crystallizing ordinary DICY such as a commercial product in an aqueous solvent in the presence of modified PVA.

As the above-mentioned aqueous solvent, in addition to water, about 10
Up to% by weight of a water-soluble organic solvent, for example, lower alcohols such as methyl alcohol, ethyl alcohol, and i-propyl alcohol; ketones such as acetone, methyl ethyl ketone; and dioxane (1,3- or 1,4
-), Cyclic ethers such as tetrahydrofuran;
Other water-soluble organic solvents such as dimethylformamide, dimethylacetamide, dimethylsulfoxide and the like; water alone or a mixed solvent containing water may be mentioned.

The above-mentioned modified PVA is generally used in an aqueous solution of DICY containing the PVA in an amount of 50 to 2000 PPM, particularly 80 to 1000 PPM.
It is preferable to use PM. The concentration of DICY in the aqueous solvent solution is generally 8 to 25% by weight, and particularly preferably 10 to 20% by weight.

Next, a method for crystallizing DICY in the present invention will be described.

The crystallization method of DICY can be a batch method or a continuous method. According to the batch method, the aqueous solvent is adjusted to about 60 to 80 ° C., and the amount of the modified PVA and the amount of DICY are adjusted.
The modified PVA and the raw material DICY are dissolved so that the concentration falls within the above range. The resulting aqueous solvent solution is adjusted to a pH of about 9 to 12 using, for example, sodium hydroxide, potassium hydroxide, or the like, and is cooled at a cooling rate of 5 to 50 ° C / Hr, preferably about 10 to 40 ° C / Hr. Cool the aqueous solvent solution to about 25-45 ° C. The generated DICY crystals are separated by a known means such as suction filtration and centrifugal filtration, and dried by a known drying means such as hot air drying and reduced pressure drying. The filtrate can be reused by elevating the temperature to about 60 to 80 ° C. to further dissolve the raw material DICY and, if necessary, replenishing an aqueous solvent, modified PVA or the like.

According to the above continuous method, an aqueous solvent solution of DICY containing modified PVA at about 60 to 80 ° C. and pH of about 9 to 12 prepared in the same manner as the batch method is mixed with about 25 to 25 45 ℃
Is continuously added to the aqueous solution of the DICY aqueous solvent held in the column, and the precipitated DICY crystal slurry is continuously extracted. At this time, the average residence time of the precipitated DICY crystal is preferably adjusted to be generally 1 to 10 hours, particularly preferably about 2 to 8 hours. The extracted DICY crystal slurry is treated in the same manner as in the above batch method to obtain dry DICY crystals.

[0025] DICY of the present invention includes an X-ray diffraction angle 2 [Theta] = 14.9 ° diffraction angle strength 1 ₁ of the primary crystal, the intensity ratio 1 _{1/1 2} of 2 [Theta] = 26.3 ° diffraction angle strength 1 ₂ 0.3 It must be: When the strength ratio is too large, exceeding 0.3, it is difficult to say that the caking property during storage has been sufficiently improved even if the DICY is obtained by crystallization in the presence of modified PVA.

The measurement of the X-ray diffraction angle intensity is carried out, for example, by using DI
The primary crystal powder obtained by dispersing the aggregate of CY crystals is filled in a diffraction holder, and an automatic recording type powder X-ray diffractometer (type JDX-8SH; Cu-Kd line as X-ray source, output 30K)
V, 14 mA; manufactured by JEOL Ltd.]. X-ray diffraction angle 2 [Theta] = 14.9 ° diffraction angle strength 1 _1, a 2 [Theta] = 26.3 ° diffraction SumiTsutomu of 1 ₂ is obtained by calculation the intensity ratio 1 _{1/1 2.}

Here, the primary crystal of DICY is the DICY crystal itself precipitated from an aqueous solution of DICY, or the DICY crystal itself.
When the DICY crystal is an aggregate, it refers to a DICY crystal obtained by performing a dispersion treatment with such a force as not to destroy the crystal itself, such as breaking the aggregate by hand.

[0028]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. The measurement of the crystal form and the degree of consolidation of the DICY crystal was performed by the following method.

Judgment of crystal form: A sample is photographed by a scanning electron microscope according to a standard method, and the crystal form of the sample is observed from the obtained photograph, and the judgment is made as follows. − ・ ・ ・ ・ ・ ・ Scaly crystals, flat prismatic crystals or plate-like crystals + ・ ・ ・ ・ ・ ・ Cubic crystals or corners mainly composed of aggregates of scale-like crystals, flat prismatic crystals or plate-like crystals Columnar crystal ++ ・ ・ ・ ・ ・ ・ Cubic crystal, prismatic crystal or spindle crystal

Consolidation degree test: Approximately 2.5 g of a sample was pressed for 20 seconds at a gauge pressure of 15 kg / cm ² using a 180 kg hydraulic press for approximately 15 m.
Create a disk of mφ. The piercing part of a precision force gauge (Model PG 1-50; manufactured by Marubishi Chemical Machinery Works) is applied vertically to the center of the plane of the disk and pressurized to consolidate the value of the gauge pressure when the disk breaks. Take the value of degrees.

Example 1 100 parts by weight of water was placed in a vessel equipped with a stirrer, heated to about 65 ° C. while stirring, and added with DICY and a sulfonic acid group-containing anion-modified PVA [Gohselan L-3266 (trade name). ; Partially saponified PVA; average degree of polymerization 250; manufactured by Nippon Synthetic Chemical Industry Co., Ltd.]
Was dissolved to obtain about 17% by weight of D containing 100 PPM of the modified PVA.
An ICY aqueous solution was obtained. This aqueous solution was adjusted to pH 11 with a 30% by weight aqueous sodium hydroxide solution, and cooled to 35 ° C. over about 1 hour (cooling rate: about 30 ° C./Hr) to obtain an aqueous slurry in which DICY crystals had precipitated. The aqueous DICY slurry was filtered by suction using a Nutsche filter to separate the precipitated DICY and dried to obtain dry DICY crystals. Table 1 below shows the measurement results of the X-ray diffraction angle intensity ratio and the degree of consolidation of the obtained crystals.

Example 2 and Comparative Example 1 In Example 1, anionic modified PVA containing a sulfonic acid group was used.
Dry crystals of DICY were obtained in the same manner as in Example 1 except that the amount of dissolved was changed or not used. Table 1 below shows the measurement results of the X-ray diffraction angle intensity ratio and the degree of consolidation of the obtained crystals.

Comparative Example 2 In Example 1, anionic modified PVA containing a sulfonic acid group was used.
Instead of using non-denaturing PVA [Gohsenol K-17E
(Trade name); partially saponified PVA, average polymerization degree 1700; manufactured by Nippon Synthetic Chemical Industry Co., Ltd.]
A dry crystal of CY was obtained. Table 1 below shows the measurement results of the X-ray diffraction angle intensity ratio and the degree of consolidation of the obtained crystals.

Example 3 100 parts by weight of the DICY slurry obtained in Example 1 was placed in a crystallization tank having a stirrer, a DICY aqueous solution supply means and a produced DICY aqueous slurry liquid take-out means.
It was kept at 5 ° C. In another container, the same sulfonic acid group-containing anion-modified PVA at about 70 ° C. as used in Example 1 was added at 100 PPM.
A DICY aqueous solution of about 17% by weight was prepared and adjusted to pH 11 with a 30% by weight aqueous solution of sodium hydroxide. Then this DI
While maintaining the temperature of the CY aqueous solution at about 70 ° C., it was continuously added to the slurry liquid in the crystallization tank. The slurry liquid in the crystallization tank was maintained at about 35 ° C. while stirring, and a part of the slurry liquid was continuously withdrawn so that the average residence time of the precipitated DICY was 3 hours. Thereafter, a dried crystal of DICY was obtained in the same manner as in Example 1. Table 1 below shows the measurement results of the X-ray diffraction angle intensity ratio and the degree of consolidation of the obtained crystals.

Examples 4-5 Dried crystals of DICY were obtained in the same manner as in Example 3, except that the average residence time of the deposited DICY was changed. Table 1 below shows the measurement results of the X-ray diffraction angle intensity ratio and the degree of consolidation of the obtained crystals.

[0036]

[Table 1]

[0036]

As is evident from the results in Table 1, DICY was obtained by using a modified PVA as a habit modifier, and precipitating crystals from a DICY aqueous solvent solution in the presence of the modified PVA. Having an X-ray diffraction angle intensity ratio in a specific range according to the present invention.
CY is an excellent one with a consolidation degree of 3.0 or less and a low consolidation property, but does not use a habit modifier, or instead of using a modified PVA as the habit modifier, Saponification P
When VA was used, the degree of consolidation was high and the consolidation was poor or not sufficiently improved.

Claims (1)

(57) [Claims] (1) Dicyandiamide is converted to a sulfonic acid group-containing aniline.
On-modified polyvinyl alcohol - a dicyandiamide present obtained crystallized under Le, the diffraction angle strength 1 ₁ X-ray diffraction angle 2 [Theta] = 14.9 ° of the primary crystal, the diffraction angle strength of 2 [Theta] = 26.3 ° 1 dicyandiamide intensity ratio 1 _{1/1 2} and _2, characterized in that less than 0.3.