JP3432374B2 - Method for producing dispersant for polymerization - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a dispersant for polymerization. More specifically, the present invention relates to a method for producing a dispersant for polymerization suitable for so-called soap-free polymerization, in which a monomer is polymerized without using a surfactant. Polymerization dispersant obtained by the production method of the present invention,
It is preferably used as a dispersant for soap-free polymerization, which is one of the methods for producing styrene resin particles having a narrow particle size distribution and expandable styrene resin particles.

[0002]

2. Description of the Related Art As a method for producing styrene resin particles, a suspension polymerization method in which a suspension stabilizer is added to a styrene monomer in an aqueous medium to carry out polymerization is known. Has been. As the suspension stabilizer used in this suspension polymerization method, a poorly water-soluble inorganic salt is used from the viewpoints of thermal stability, mechanical strength, transparency and the like. Since this poorly water-soluble inorganic salt has a poor affinity with the monomer, a small amount of a surfactant is usually used as a suspension stabilizing aid.

However, in the suspension polymerization method using a poorly water-soluble inorganic salt and a surfactant, it is difficult to arrange particles in a specific particle size range, and only resin particles having a wide particle size distribution range can be obtained. . On the other hand, in order to produce particles with a uniform particle size, a method of polymerizing a styrene-based monomer in the presence of a sparingly water-soluble phosphate without using a surfactant (so-called soap-free weight). (Legal) is known (Japanese Patent Publication No. 46-15112, US Pat. No. 26523).
92). As an additive for soap-free polymerization, a water-soluble sulfite salt is added in JP-B-46-15112 and a water-soluble persulfate salt is added in US Pat. No. 2,652,392. Thus, in these patents, the dispersant, that is, the sparingly water-soluble phosphate is a sparingly water-soluble phosphate used in a general suspension polymerization method using a sparingly water-soluble inorganic salt and a surfactant.

The expandable styrenic resin generally has a particle size of 0.
Particles of 25-2.0 mm are used. Particle size is 0.
The particles of 25 to 0.5 mm have a particle diameter of 0.5 to 1.2 for a hot water container such as a cup or for a full molding method in casting.
Particles of mm are mainly used for various molded articles such as packing, fish boxes, etc., and 0.7 to 2.0 mm are mainly used for lightweight embankment method, heat insulation materials such as roofs, and blocks as cushioning packaging materials. ing.

Therefore, it is necessary to provide particles having a narrow particle size distribution according to each of the above applications. However, in the production of styrene resin particles by a soap-free polymerization method using a conventional poorly water-soluble phosphate, the particle size distribution width is narrower than that of a general suspension polymerization method, but it is still not sufficiently satisfactory. -There are still problems such as complicated inventory management and unnecessary particle processing.

Therefore, it is very important to further narrow the particle size distribution width in terms of productivity and inventory control. However, conventional poorly water-soluble phosphates for suspension polymerization have been improved so as to be suitable for suspension polymerization reaction using a surfactant as a dispersion aid. That is, it has been developed so that the dispersibility of the polymerizable monomer in the aqueous solution is increased. Regarding the improvement, Japanese Patent Publication No. 54-44313 and JP-A-5-222103.
JP-A-6-220108, JP-A-7-10200
No. 5, JP-A No. 7-102006 and the like are known, and the sedimentation half-life and the electric conductivity are used as indicators of the improvement. In this index, the longer the sedimentation half-life and the lower the electric conductivity, the more suitable as the dispersant. Furthermore, investigations have been made to specify the crystal form, make the particles finer, prevent aggregation, and increase the crystallinity when directly analyzed by X-ray diffraction. Further, the present inventors have found that the dispersant is calcined at about 800 ° C. for about 3 hours, and X-ray diffraction analysis shows that it is 100% hydroxyapatite.

However, the above-mentioned dispersant was not suitable as a dispersant for a soap-free polymerization reaction without adding a surfactant.

[0008]

In view of the above problems, the inventors of the present invention have earnestly studied, and as a result, when amorphous calcium phosphate synthesized under certain conditions was used as a dispersant for soap-free polymerization, It has been found that the polymer has a desired particle size, a narrow particle size distribution width, and resin particles of excellent quality can be obtained when the foamed molded product is obtained.

Further, about 8 parts of this amorphous calcium phosphate is added.
It was found to be a mixture of hydroxyapatite and β-TCP by firing at 00 ° C. for about 3 hours and X-ray diffraction analysis. Furthermore, it has been found that this amorphous calcium phosphate is particularly suitable as a dispersant for soap-free polymerization. Then, when the method for synthesizing the above-mentioned dispersant for polymerization was further investigated, a method for producing a dispersant for polymerization stably and with good reproducibility was found, and the present invention was reached.

Thus, according to the invention, 5 to 25% by weight
CaO / P ₂ O _{5 in} an aqueous slurry of calcium hydroxide
The final pH of the reaction system is such that an aqueous solution of phosphoric acid having an amount (weight ratio) of 0.90 to 1.3 and a concentration of 20% by weight or more can produce amorphous calcium phosphate having the following properties. Is adjusted to 8 or less, and the temperature of the aqueous slurry is adjusted.
At a temperature of 5 ° C to 45 ° C at the start of the addition of the phosphoric acid aqueous solution.
℃, at the end of the addition of phosphoric acid aqueous solution 55 ℃ ± 10
℃, aqueous from the start of addition of phosphoric acid aqueous solution to the end of addition
The temperature of the slurry rises linearly with fluctuations within ± 5 ° C
The following properties (i) have an electric conductivity of 150 μS / cm to 10000 μS / cm when the aqueous slurry of amorphous calcium phosphate is 10% by weight, and 5 when the aqueous slurry of 1.5% by weight is used.
Min to 20 min sedimentation half-life, and (ii) produced hydroxyapatite and β-TCP as main components when crystallized by baking at about 800 ° C for about 3 hours and measured by X-ray diffractometer Polymerization characterized by producing amorphous calcium phosphate satisfying at least one of the peak intensity ratios of β-TCP calculated from the strengths of the strongest peaks of hydroxyapatite and β-TCP. Provided is a method of manufacturing a dispersant for a vehicle.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION According to the production method of the present invention, the following properties (i) and (ii) (i) in the case of an aqueous slurry containing 10% by weight of amorphous calcium phosphate, 150 μS / cm to 10000 μS / cm of electricity are used. 5 for conductivity and 1.5% by weight aqueous slurry
(Ii) When crystallized by baking at about 800 ° C. for about 3 hours, hydroxyapatite and β-TCP as main components are produced and measured by an X-ray diffractometer. Β calculated from the intensity of the strongest peak of hydroxyapatite and β-TCP of
It is possible to produce a dispersant for polymerization composed of amorphous calcium phosphate that satisfies at least one of the peak intensity ratios of TCP of 5% to 100%.

The weight obtained by the manufacturing method of the present invention is
The combined dispersant is CaO / P at the time of compounding. ₂O_Five(Weight ratio)
CaO / P substantially the same as 0.90 to 1.3₂O
_Five(Weight ratio). Obtained by the manufacturing method of the present invention
The resulting dispersant for polymerization is substantially CaO / P₂O_Five(Heavy
Amorphous calcium phosphate with a volume ratio of 0.90 to 1.3
Consists of CaO / P₂O_Five(Weight ratio) is 0.90
If it becomes too small, the dispersion effect will decrease and the polymerization reaction will continue.
It is not preferable because it will not be possible. Also greater than 1.3
The quality of the synthesized dispersant becomes unstable and
Therefore, the particle size of the polymer particles obtained when used as a dispersant
It is not preferable because the distribution becomes wide.

Furthermore, the dispersant for polymerization obtained by the production method of the present invention comprises amorphous calcium phosphate,
(I) 150 μS / cm to 10000 μS / cm in the case of an aqueous slurry containing 10% by weight of amorphous calcium phosphate
(Preferably 300 μS / cm to 8000 μS / cm)
And a settling half-life of 5 minutes to 20 minutes (preferably 5 minutes to 15 minutes) in the case of an aqueous slurry of 1.5% by weight.

If the sedimentation half-life is less than 5 minutes, the particles of the dispersant become large and the effect as the dispersant becomes too poor to complete the polymerization reaction. On the other hand, if it is longer than 20 minutes, the effect as a dispersant becomes too good, so that the effect of protecting droplets is strong and the particle size distribution is wide, which is not suitable.
If the electric conductivity is less than 150 μS / cm, the dispersion effect will be too good, and the particle size distribution of the polymer particles will be broad, which is not preferable. On the other hand, if it is higher than 10000 μS / cm, various influences may be exerted on the polymerization reaction possibly due to the influence of the electrolyte, and the polymerization may not be completed, which is not preferable.

The above properties are properties imparted to the dispersant for polymerization through the production method of the present invention. Furthermore, the dispersant for polymerization obtained by the production method of the present invention is (ii) hydroxyapatite and β-TCP as main components when crystallized by baking at about 800 ° C. for about 3 hours.
And the peak intensity ratio of β-TCP calculated from the intensity of the strongest peaks of hydroxyapatite and β-TCP when measured with an X-ray diffractometer is 5% to 100% (preferably 25% to 100%). is there.

After the production of the dispersant for polymerization, the dispersant for polymerization is filtered, dried at 140 ° C. for 3 hours, and then measured by an X-ray diffractometer, so that the peak cannot be broadly analyzed. This means that the dispersant for polymerization obtained by the production method of the present invention is non-crystallized amorphous calcium phosphate. Therefore, by firing at about 800 ° C. for about 3 hours to crystallize, hydroxyapatite and β-T
CP becomes the main component and analysis becomes possible. Hydroxyapatite and β-TCP as measured by X-ray diffractometer
When the peak intensity ratio of β-TCP calculated from the intensity of the strongest peak is less than 5%, the particle size distribution becomes wide, probably because the dispersion power increases. Similarly, when a dispersant synthesized by a conventional hydroxyapatite production method or a dispersant labeled as TCP on the market was analyzed, it was found to be about 1
It was found to be 00% hydroxyapatite. In addition, in the polymerization dispersant obtained when the production temperature was set to 60 ° C. or higher, a broad peak appeared to be a peak, but it could not be analyzed yet. Furthermore, for example, Japanese Patent Laid-Open No. 6-220108 discloses that hydroxyapatite having a sharp peak on the X-ray diffraction analysis chart is suitable for suspension polymerization. Further, in the experiments conducted by the present inventors, it was found that the peak becomes sharper when the reaction temperature of calcium hydroxide and phosphoric acid is increased.

The above properties (i) and (ii) are required to have at least one of them, and may have both of them. Hereinafter, the method for producing the polymerization dispersant of the present invention will be described. In the method for producing a dispersant for polymerization of the present invention, the concentration of the aqueous slurry of calcium hydroxide before the addition of the phosphoric acid aqueous solution is preferably 5 to 25% by weight. If it is less than 5% by weight, the concentration of the resulting dispersant becomes low and it is not economical, which is not preferable. If it exceeds 25% by weight, the viscosity becomes too high during the reaction with phosphoric acid, and the resulting dispersant does not exhibit the desired dispersing effect, which is not preferable.

Next, an aqueous phosphoric acid solution is added to calcium hydroxide. The concentration of this phosphoric acid aqueous solution is 20% by weight or more, and preferably 50 to 85% by weight. If it is less than 20% by weight, it is not preferable because it requires further diluting from commercially available phosphoric acid and the number of steps is increased, and the concentration of the dispersant produced becomes thin, and concentration becomes necessary, which is not economical. It is not preferable. Especially 10
When it is at most% by weight, a dispersant having a stronger dispersing effect can be obtained, and a dispersant having the above properties (i) and / or (ii) cannot be obtained, which is not preferable.

When thin phosphoric acid of less than 5% by weight is used and CaO / P ₂ O ₅ (weight ratio) is 1.2 to 1.3, it becomes almost hydroxyapatite when fired, which is desirable. No dispersant can be obtained. Therefore, a concentration of 20% by weight or more is important for stable and reproducible production. Furthermore, in order to reliably obtain the dispersant having the above properties (i) and / or (ii), it is preferable to use phosphoric acid at a concentration of 50% by weight or more.

Particularly, phosphoric acid is generally 75% by weight or 8%.
Since it is commercially available as 5% by weight, it is preferable to use it as it is because it is most economical including storage without extra work such as dilution. Next, the phosphoric acid aqueous solution is added so that the final pH of the reaction system becomes 8 or less at a rate at which amorphous calcium phosphate having the above properties (i) and / or (ii) can be produced.

Here, the addition rate of the phosphoric acid aqueous solution is specifically 10 g / min to 45 g / min (preferably 15 g / min to 4) per kg of calcium hydroxide in terms of diphosphorus pentoxide.
0 g / min) (hereinafter, the addition rate of the phosphoric acid aqueous solution per 1 kg of calcium hydroxide in terms of diphosphorus pentoxide is referred to as the phosphoric acid addition rate). If the addition rate is less than 10 g / min, a phosphoric acid compound having a strong dispersibility may be obtained, which is not suitable. If it exceeds 45 g / min, the synthesis reaction cannot be carried out uniformly, which is not suitable. If outside the above range, it is about 80
When it was calcined at 0 ° C. for about 3 hours and analyzed, a peak of calcium oxide appeared, which revealed that a large amount of unreacted material was contained. From this, in order to produce a dispersant for polymerization having more preferable properties, the phosphoric acid addition rate preferably satisfies the above range.

On the other hand, when the final pH of the reaction system is higher than 8, hydroxyapatite is stably formed and the desired dispersant having the above properties (i) and / or (ii) cannot be obtained, which is not preferable. . In addition, particularly preferable pH
The range is 5 to 7. When CaO / P ₂ O ₅ (weight ratio) is 1.3 or less, the final pH can be 8 or less without any special treatment.

The temperature at which the aqueous solution of phosphoric acid is added to the aqueous slurry of calcium hydroxide and the temperature during the addition are not particularly limited. However, it was found that the addition start temperature and the temperature during the addition affect the quality of the generated dispersant for polymerization, and the particle size of polystyrene-based resin particles obtained by polymerization using the same. Therefore, it is preferable to control the addition temperature of the phosphoric acid aqueous solution to the calcium hydroxide because the same dispersant can be always synthesized.

That is, the aqueous slurry has a temperature of 5 ° C. to 45 ° C. at the start of addition of the phosphoric acid aqueous solution and a temperature of 55 ° C. ± 10 ° C. at the end of addition of the phosphoric acid aqueous solution. It is preferable that the temperature of the aqueous slurry is controlled to rise linearly within a range of ± 5 ° C. from the start of addition to the end of addition. Since the reaction between calcium hydroxide and phosphoric acid is an exothermic reaction, the temperature at the end of the reaction rises without any control. The temperature at the end of the reaction depends on the shape of the reactor, the ambient temperature, and the concentrations of calcium hydroxide and phosphoric acid. For example, in the equipment used by the present inventors, 10 wt% calcium hydroxide aqueous slurry and 75 wt% phosphoric acid were used, and the addition start temperature was 30%.
When the temperature was about 0 ° C, the temperature at the end of the addition was about 55 ° C without control. From this, it is possible to set the reaction start temperature to 30 ° C most economically throughout the four seasons, and to set the reaction end temperature to 55 ° C and control the temperature to increase linearly from 30 ° C to 55 ° C. However, heating and cooling during the process are hardly required, and the seasonal variation can be suppressed most economically to produce the dispersant for polymerization of the same quality. It should be noted that it is not economical because it is necessary to always cool the starting temperature of addition to lower than 5 ° C. Similarly, it is not preferable to set the addition end temperature higher than 65 ° C. because heating is required and control becomes complicated, which is not economical.

As another temperature control method with good reproducibility,
The aqueous slurry is 6 at the start of the addition of the phosphoric acid aqueous solution.
It is preferable that the temperature of the aqueous slurry is 0 ° C. to 130 ° C. and the temperature of the aqueous slurry is controlled to a temperature within ± 5 ° C. at the start of addition until the end of addition of the aqueous phosphoric acid solution. Within this temperature, the heat generated by the addition of phosphoric acid is offset by the heat released from the reactor, and the constant temperature control is simple and economical.

When the reaction is started at a temperature higher than 130 ° C., brushite is formed and the effect as a dispersant is lost, which is not preferable. If the temperature exceeds 95 ° C., there is a risk of boiling, so it is preferable to use a pressure vessel such as an autoclave. The slurry stirring speed at the time of addition is suitably 1.0 to 5.0 m / min at the tip speed of the stirring blade. When the stirring speed is less than 1.0 m / min, the reaction becomes non-uniform and the dispersion force becomes too weak, and when used for the polymerization of the styrene resin, the polymerization reaction cannot be completed, which is not preferable. 100 above 5 m / min
% Hydroxyapatite may occur, which is not preferable.

The dispersant obtained by the above-mentioned production method of the present invention can be used as it is, but it is preferably in the form of a 3 to 20% by weight aqueous slurry or in the form of a powder obtained by subjecting it to a spray dryer treatment. Here, if the amount of the aqueous slurry is less than 3% by weight, the productivity at the time of production decreases, which is not practical. An aqueous slurry exceeding 20% by weight is not preferable because the desired dispersant cannot be produced because the viscosity becomes too high during the reaction between calcium hydroxide and phosphoric acid.

As an additional effect, the dispersant obtained by the production method of the present invention has a result that the polymerization reaction is not affected even by aggregation of the dispersant particles during storage. Since the dispersant of the present invention tends to settle, water and solids are immediately separated in the container. Therefore, it easily aggregates. When a conventional dispersant is agglomerated, the dispersion effect is deteriorated, the reproducibility of the particle size distribution is deteriorated, or the dispersion is poor and the polymerization cannot be completed in some cases. However, the dispersant obtained by the production method of the present invention was found to have no effect on the polymerization even if it aggregates, and it is not necessary to pay attention to storage.
That is, the stabilizing treatment and the stabilizing device are not required for stabilizing the dispersant.

The dispersant obtained by the production method of the present invention is preferably used in a method of polymerizing a monomer (so-called soap-free polymerization method) without using a surfactant. Examples of the monomer include a styrene monomer and a mixture with another monomer containing a styrene monomer as a main component. As another monomer, α-methylstyrene,
Styrene-based monomers such as p-methylstyrene, t-butylstyrene and chlorostyrene, methacrylate monomers such as methyl methacrylate, butyl methacrylate and isobutyl methacrylate, acrylate monomers such as ethyl acrylate and 2-ethylhexyl acrylate, acrylonitrile , Vinyl cyanide-based monomers such as methacrylonitrile, and polyfunctional monomers such as divinylbenzene and polyethylene glycol dimethacrylate.

Next, the measuring method used for the amorphous calcium phosphate of the present invention will be described. [Measurement method of CaO / P ₂ O ₅ (weight ratio) of the dispersant for polymerization] Powder is as it is, slurry is filtered to
After drying at 0 ° C. for 3 hours, the sample was dissolved in 1N nitric acid, and the amounts of calcium and phosphorus were measured using a sequential type high frequency plasma emission spectrophotometer (manufactured by Seiko Denshi Kogyo Co., Ltd.), and CaO / P ₂ O ₅ (weight ratio) was calculated. In addition, CaO / P ₂ O ₅ (weight ratio) at the time of compounding shows a value converted by the concentration of calcium hydroxide and phosphoric acid used.

[Measurement Method of Electric Conductivity] A 10 wt% aqueous slurry was prepared as a sample and measured with a conductivity meter (manufactured by Horiba Ltd.).

[Measurement method of sedimentation half-life] A 1.5% by weight aqueous slurry in which a sample was uniformly dispersed was put in a 100 ml sedimentation tube and allowed to stand at 25 ° C., and the sediment volume became 50 ml. It is a measurement of the time until it becomes.

[Measurement Method of Hydroxyapatite and β-TCP Strongest Peak Intensity Ratio] Powder as it is, slurry-like one was filtered and dried at 140 ° C. for 3 hours.
The sample is fired at about 800 ° C. for about 3 hours to crystallize, and measured with an X-ray diffractometer (manufactured by Rigaku Denki Co., Ltd.) to obtain the strongest peak of each [hydroxyapatite (Miller index (211) 2
θ = 31.7 °), tricalcium phosphate (β-TC
P) (Miller index (217) 2θ = 31.0 °)] peak intensities (counts of X-rays per unit time) are compared, and the β-TCP peak intensity ratio (%) is calculated by the following formula.
I asked.

Β-TCP peak intensity ratio (%) = β-
TCP peak intensity / (hydroxyapatite peak intensity + β-TCP peak intensity) × 100

[0035]

EXAMPLES Next, examples of the present invention and comparative examples will be described. Example 1 [Synthesis Method of Amorphous Calcium Phosphate] 4075 g of ion-exchanged water and 355 g of calcium hydroxide were charged into a 5 liter container to prepare a dispersion liquid. Under vigorous stirring, 436.5 g of a 75.1 wt% phosphoric acid aqueous solution was continuously added to this dispersion by a plunger pump in 30 minutes. The temperature at the end of this addition was 40 ° C. After the addition of phosphoric acid was finished, the mixture was left to cool with stirring for 30 minutes to obtain a slurry. The solid content of this slurry was 10.56% by weight, and CaO / P ₂ O
_{When 5} (weight ratio) was measured, it was 1.11. The temperature of the calcium hydroxide dispersion at the start of adding the phosphoric acid aqueous solution is 20
It was ℃.

Similarly, 407.7 g of a 75.1 wt% phosphoric acid aqueous solution was added. In this case, the solid content of the slurry is 1
It was 0.24% by weight, and the weight ratio was 1.20.

Next, examples and comparative examples concerning the polymerization of the present invention will be shown. In addition, in the following, peak 3 sieve is JIS standard sieve opening 2.36 mm (7.5 mesh), opening 2.00 mm (8.6 mesh), opening 1.70 mm (10 mesh), opening 1.40 mm
(12 mesh), opening 1.18 mm (14 mesh), opening 1.00 mm (16 mesh), opening 0.85 mm (18 mesh), opening 0.71 mm
(22 mesh), opening 0.60 mm (26 mesh), opening 0.50 mm (30 mesh), opening 0.425 mm (36 mesh), opening 0.355 m
m (42 mesh), opening 0.300 mm (50 mesh), opening 0.250 mm (60 mesh), opening 0.121 mm (70 mesh), opening 0.180
Particle size (median diameter) at which cumulative weight becomes 50% based on cumulative weight distribution curve after classification with mm (83 mesh)
Is defined as D50, and indicates the ratio of the particle size distribution in the range of the three sieves having a large distribution ratio from the range to which the particle size of D50 belongs.

Examples 2 to 11 and Comparative Examples 1 to 6 [Soap-Free Polymerization Method 1] Aqueous slurry of amorphous calcium phosphate having the properties shown in Table 1 and having a solid content of 120 g as a dispersant in a 100 liter autoclave. (About 10% by weight) was added, and further 0.4 g of sodium bisulfite and 140 g of benzoyl peroxide (purity: 75
%), 30 g of t-butyl peroxybenzoate, 4
0 kg of ion-exchanged water and 40 kg of styrene monomer were mixed and charged, and dissolved and dispersed under stirring to form a suspension.

Next, the styrene monomer was subjected to a polymerization reaction at 90 ° C. for 6 hours and further at 115 ° C. for 2 hours under stirring at 200 rpm. After completion of the reaction, the mixture was cooled, the contents were taken out from the autoclave, subjected to a centrifugation step, and then dried styrene resin particles were obtained. The particle size distribution (peak 3 sieve) of the obtained styrene resin particles is shown in Table 1. Furthermore, FIG.
2 is an X-ray diffraction analysis chart of Comparative Examples 2 to 4 during drying (140 ° C. for 3 hours), FIG. The X-ray-diffraction-analysis chart at the time of baking of 1, 2, and 4 (about 800 degreeC) is shown.

[0040]

[Table 1]

However, Examples 10 and 11 and Comparative Examples 5 and 6
Shows the addition of potassium persulfate as shown in Table 1. In Comparative Examples 3 to 6, TCP-10 manufactured by Taihei Chemical Co., Ltd. and tricalcium phosphate C13-09 manufactured by Boudenheim Chemical Co., which are conventionally known as a dispersant for polymerization used in combination with a surfactant, are used. It was what I had. Conventional dispersants are tricalcium phosphate (T) when crystallized at about 800 ° C.
Even though it is displayed as CP), it was found that it is actually hydroxyapatite. On the other hand, when the polymerization dispersant of the present invention was crystallized at about 800 ° C., it was composed of hydroxyapatite and tricalcium phosphate (β-TCP) or most of tricalcium phosphate (β-TCP).

It is considered that the conventional dispersants (Comparative Examples 3 to 6) have a strong effect of protecting the dispersion of the monomer and monomer droplets in the polymerization reaction system. However, it was found that in the polymerization method of the present invention, the weak dispersion protection effect of the monomer droplets has the effect of narrowing the particle size distribution. Also, FIG.
From 4 to 4, it was found that the commercially available dispersants of Comparative Examples clearly show absorption of hydroxyapatite, but the dispersants of Examples have a broad peak and are a mixture of a plurality of substances. Furthermore, it was found that the dispersant of the examples was a mixture of hydroxyapatite and β-TCP.

Examples 12 to 14 [Method for synthesizing amorphous calcium phosphate] 4075 g of ion-exchanged water and 355 g of calcium hydroxide were charged into a 5 liter container to prepare a dispersion liquid. After keeping this dispersion at a constant temperature, 450 g of a 75.1 wt% phosphoric acid aqueous solution (temperature: 25 ° C.) was continuously added with a plunger pump over 30 minutes under stirring at 360 rpm (CaO / P ₂ O
₅ (weight ratio at the time of compounding, hereinafter referred to as compounding weight ratio) 1.
1). After the addition of phosphoric acid was completed, the mixture was left stirring for 30 minutes and cooled to obtain a slurry. Solid content of this slurry is about 10% by weight
Met. Table 2 shows the temperature of the calcium hydroxide dispersion at the start of the addition of phosphoric acid, the temperature of the slurry at the end of the addition, and the properties of the obtained dispersant.

[Soap-free polymerization reaction 2] A solid content of 120 g as a dispersant was added to a 100-liter autoclave.
A considerable amount of an aqueous slurry of amorphous calcium phosphate prepared under the conditions shown in Table 1 (about 10% by weight) was added, followed by 0.65 g of sodium bisulfite, then 14
0 g benzoyl peroxide (purity 75%), 30 g t-
Butyl peroxybenzoate, 40 kg of ion-exchanged water and 40 kg of styrene monomer were mixed and charged,
It was dissolved and dispersed under stirring to form a suspension.

Then, the suspension was subjected to polymerization reaction of styrene monomer at 90 ° C. for 6 hours and further at 115 ° C. for 2 hours under stirring at 200 rpm. After completion of the reaction, the mixture was cooled, the contents were taken out from the autoclave, subjected to a centrifugation step, and then dried styrene resin particles were obtained. Table 2 shows the average particle size (D50) and particle size distribution (peak 3 sieve) of the obtained styrene resin particles.

[0046]

[Table 2]

From Table 2, it was found that the dispersant of the present invention can provide resin particles having a narrow particle size distribution when used in a soap-free polymerization reaction.

Examples 15 to 17 [Method for synthesizing amorphous calcium phosphate] In winter (February), spring (April), summer (August), 4075 g of ion-exchanged water and 355 g of hydroxylation were added to a 5-liter autoclave. Calcium was added to prepare a dispersion liquid. After heating this dispersion to 30 ° C. to make it constant, 430 g under stirring at 360 rpm
75.1% by weight phosphoric acid aqueous solution was continuously added by a plunger pump for 30 minutes (CaO / P ₂ O ₅ (blending weight ratio) 1.15). After the addition of phosphoric acid was completed, the mixture was left stirring for 30 minutes and cooled to obtain a slurry. The solid content of this slurry was about 10% by weight. Table 3 shows the temperature of the slurry after the addition of phosphoric acid and the properties of the synthesized dispersant.

[Soap-Free Polymerization Reaction 3] An aqueous slurry (about 10% by weight) of amorphous calcium phosphate produced under the above conditions in an amount of 120 g in terms of solid content was added as a dispersant to a 100 liter autoclave, and further added to 0.1. 3 g of potassium persulfate was added, then 140 g of benzoyl peroxide (purity 75%), 30 g of t-butyl peroxybenzoate, 40 kg of ion-exchanged water and 40 kg of styrene monomer were mixed and charged, and the mixture was stirred. Dissolved and dispersed below to form a suspension. Next, this suspension was subjected to a polymerization reaction in the same manner as in Examples 12 to 14 to obtain styrene resin particles. Average particle diameter (D50) of the obtained styrene resin particles,
The particle size distribution (Peak 3 sieve) is shown in Table 3.

[0050]

[Table 3]

From Table 3, it can be seen that even if the synthesis temperature of the dispersant varies depending on the season, the advantage that the soap-free polymerization reaction has a narrow particle size distribution does not change, but the particle size is affected.

Examples 18 to 20 Slurry temperature during addition of aqueous phosphoric acid solution when synthesizing amorphous calcium phosphate in a 5 liter autoclave under conditions where the ambient temperature around the reactor is 4 ° C, 23 ° C and 34 ° C Was controlled to linearly rise from 30 ° C. at the start of addition to 55 ° C. at the end. Others were processed similarly to Examples 15-17, and the slurry was obtained. The properties of this synthesized dispersant and the average particle size (D5 of the styrene resin particles obtained by carrying out the soap-free polymerization similar to Examples 15 to 17)
0) and the particle size distribution (peak 3 sieve) are shown in Table 4.

[0053]

[Table 4]

From Table 4, it was found that even when the dispersant obtained by controlling the synthesis temperature is used in the soap-free polymerization reaction, resin particles having a narrow particle size distribution can be provided.

Examples 21 to 24, Comparative Examples 7 to 11 [Method for synthesizing amorphous calcium phosphate] 4075 g of ion-exchanged water and 355 g of calcium hydroxide were charged into a 5 liter autoclave to prepare a dispersion liquid. 2 this dispersion
After heating to 5 ° C, under stirring at 360 rpm, 390 g of 75.
A 1% aqueous phosphoric acid solution was continuously added by a plunger pump (CaO / P ₂ O ₅ (blending weight ratio) 1.27). After the addition of phosphoric acid was completed, the mixture was left stirring for 30 minutes and cooled to obtain a slurry. The solid content of the slurry was about 10% by weight. The phosphoric acid addition time (addition rate) and the properties of the synthesized dispersant are shown in Table 5.

[Soap-Free Polymerization Reaction 4] To an autoclave of 100 liters, an aqueous slurry (about 10% by weight) of amorphous calcium phosphate produced under the above conditions in an amount equivalent to 120 g in terms of solid content was added as a dispersant, and further added to 0.1. 16 g
Of sodium bisulfite and 0.16 g of potassium persulfate are added, then 140 g of benzoyl peroxide (purity 75
%), 30 g of t-butyl peroxybenzoate, 4
0 kg of ion-exchanged water and 40 kg of styrene monomer were mixed and charged, and dissolved and dispersed under stirring to form a suspension. Next, this suspension was subjected to a polymerization reaction in the same manner as in Examples 12 to 17 to obtain styrene resin particles. The particle size distribution (Peak 3 sieve) of the obtained styrene resin particles is shown in Table 5.

[0057]

[Table 5]

From Table 5, the ratio of β-TCP is 5 to 100.
It has been found that the dispersant of the present invention within the range of% can provide resin particles having a narrow particle size distribution in the soap-free polymerization reaction.

Example 25, Comparative Example 12 The dispersant of Example 14 and TCP-10 (10 manufactured by Taihei Chemical Co., Ltd.)
(Wt% aqueous slurry) was placed in a 2 liter container and left in a cool dark place for 1 year. After standing, the mixture was thoroughly stirred by hand to return the precipitate to a slurry state again. The particle size distribution of this was measured with a centrifugal sedimentation type particle size distribution analyzer SA-CP3 type (manufactured by Shimadzu Corporation) to evaluate the state of aggregation. Further, using these dispersants, a soap-free polymerization reaction and a general suspension polymerization reaction similar to those in Examples 15 to 17 were carried out to measure the particle size distribution (peak 3 sieve). The results are shown in Table 6.

[General Suspension Polymerization Reaction] To an autoclave of 100 liters, 60 g of solid content of an aqueous slurry of amorphous calcium phosphate (about 10% by weight) was added, and 2.2 g of α- was added as a suspension stabilizer. Olefin sulfonate was added, then 140 g benzoyl peroxide (purity 75%), 30 g t-butyl peroxybenzoate, 40 kg deionized water and 40 kg styrene monomer were mixed and charged, and the mixture was stirred. And dissolved and dispersed to form a suspension. Next, this suspension was subjected to polymerization reaction of styrene monomer at 115 ° C. for 6 hours at 90 ° C. and further for 2 hours at 115 ° C. under stirring at 115 rpm. At 2 and 3 hours in the middle of the reaction, 6 g of the same dispersant in solid content was additionally added. After the completion of the reaction, the same treatment as in Examples 12 to 20 was carried out to obtain styrene resin particles. The results are shown in Table 6.

[0061]

[Table 6]

From Table 6, it was found that the dispersant of the present invention is particularly preferably used in the soap-free polymerization reaction. Further, 50 g of the dispersant slurry before being left is used as filter paper No. 2.
An X-ray diffractometer (Rigaku Denki Co., Ltd.) was used to sample a sample after filtering with (Toyo Roshi Kaisha) and drying the residue at 140 ° C. for 3 hours, and a sample crystallized by further baking this sample at about 800 ° C. for about 3 hours. (Manufactured by the company). The chart of the measurement result is shown in FIG.
~ (D). FIG. 5A and FIG.
FIG. 5B is a chart of Example 25 and Comparative Example 12 dried at 3 ° C. for 3 hours, and FIGS.
15 is a chart of Example 25 and Comparative Example 12 which were fired for about 3 hours.

In FIGS. 5C and 5D, Comparative Example 12
It was found that the above dispersant was 100% hydroxyapatite. On the other hand, the dispersant of the present invention is considered to be composed of various mixtures because the peak is not clear in FIG. 5 (a), but in FIG.
It has been shown to be a mixture of TCP and hydroxyapatite.

Example 26 A 100-liter autoclave was charged with 60 kg of ion-exchanged water and 5 kg of calcium hydroxide to prepare a dispersion liquid.
The dispersion was heated to 20 ° C. under stirring at 200 rpm,
A 25 wt% phosphoric acid aqueous solution was continuously added by a plunger pump (phosphoric acid addition rate was 1 kg of calcium hydroxide).
20.8 g / min in terms of diphosphorus pentoxide). During this reaction, about 300 g of the reaction slurry was sampled, kept in a water bath at 50 ° C. for 30 minutes with stirring, and then cooled to obtain a dispersant. After filtering a part of it and drying at 140 ° C. for 3 hours, the sample was baked at about 800 ° C. for about 3 hours to crystallize, and measured by an X-ray diffractometer (manufactured by Rigaku Denki Co., Ltd.).

Table 7 shows the sampling timing and the properties of the dispersant. Further, an X-ray diffraction analysis chart is shown in FIG.
~ (E). 6A to 6E respectively show 1
The charts at the 8th minute, the 27th minute, the 30th minute, the 33rd minute, and the 46th minute are shown. [Soap-Free Polymerization Reaction 5] Aqueous slurry of amorphous calcium phosphate prepared under the above conditions in a solid content of 6 g as a dispersant in a 5 liter autoclave (about 10
%), Followed by 0.06 g sodium bisulfite, and then 7 g benzoyl peroxide (purity 75
%), 1.5 g of t-butyl peroxybenzoate,
2 kg of ion-exchanged water and 2 kg of styrene monomer were mixed and charged, and dissolved and dispersed under stirring to form a suspension. Next, this suspension was subjected to a polymerization reaction in the same manner as in Examples 12 to 17 to obtain styrene resin particles. The particle size distribution (peak 3 sieve) of the obtained styrene resin particles is shown in Table 7.

[0066]

[Table 7]

From the above results, in the reaction between calcium hydroxide and phosphoric acid, hydroxyapatite is stable when the reaction system is alkaline, but β-TCP is stabilized as the condition changes from weakly acidic to acidic. I understood it. Furthermore, it was found that the hydroxyapatite once formed was changed to β-TCP as well under acidic conditions. It was found that when further phosphoric acid was added and the acidic conditions became stronger, it changed to another calcium phosphate compound.

[0068]

EFFECT OF THE INVENTION According to the present invention, it is possible to provide resin particles having a desired particle size, a narrow particle size distribution width, and excellent quality when formed into a foamed molded product, which is composed of amorphous calcium phosphate for polymerization. It is possible to provide a method for producing a dispersant for polymerization stably and with good reproducibility.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction analysis chart of a dispersant in Examples 3, 5 and 6 during drying.

FIG. 2 is an X-ray diffraction analysis chart of dispersants during drying of Comparative Examples 2 to 4.

FIG. 3 is an X-ray diffraction analysis chart during firing of Examples 3, 5 and 6.

FIG. 4 is an X-ray diffraction analysis chart during firing of Comparative Examples 1, 2, and 4.

5 is an X-ray diffraction analysis chart of the dispersant after drying and firing in Example 25 and Comparative Example 12. FIG.

FIG. 6 is an X-ray diffraction analysis chart showing changes in the crystalline state of the dispersant with respect to the sampling time.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-194205 (JP, A) JP-A-7-102006 (JP, A) JP-A-9-142817 (JP, A) JP-A-5- 222103 (JP, A) JP 7-1118311 (JP, A) JP 7-102005 (JP, A) JP 6-220108 (JP, A) JP 9-194505 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B01F 17/14 C01B 25/32 C08F 2/18 C08F 12/06 C08J 9/20

Claims (2)

(57) [Claims] 1. A CaO / P ₂ O ₅ (weight ratio) of 0.90 to an aqueous slurry of 5 to 25 wt% calcium hydroxide.
The amount a and the concentration of phosphoric acid aqueous solution of 20% by weight or more equivalent to 1.3, at a rate capable of forming an amorphous calcium phosphate illustrating the following properties, the final pH of the reaction system was added to a 8 below , The temperature of the aqueous slurry, the addition of phosphoric acid aqueous solution
At the start of addition, 5 ° C to 45 ° C, the end of addition of the phosphoric acid aqueous solution
At the end of 55 ℃ ± 10 ℃, start adding phosphoric acid aqueous solution
Temperature of the aqueous slurry from ± 5 ℃
By controlling to increase linearly with the fluctuation of
The following properties (i) have an electric conductivity of 150 μS / cm to 10000 μS / cm in the case of an aqueous slurry containing 10% by weight of amorphous calcium phosphate and 5 in the case of an aqueous slurry of 1.5% by weight.
Min to 20 min sedimentation half-life, and (ii) produced hydroxyapatite and β-TCP as main components when crystallized by baking at about 800 ° C for about 3 hours and measured by X-ray diffractometer Polymerization characterized by producing amorphous calcium phosphate satisfying at least one of the peak intensity ratios of β-TCP calculated from the strengths of the strongest peaks of hydroxyapatite and β-TCP. For producing a dispersant for use in food. 2. A phosphoric acid aqueous solution is calcium hydroxide 1k.
The production method according to claim 1, wherein the addition is performed at a rate of 10 g / min to 45 g / min in terms of diphosphorus pentoxide per g.