JP2001026615A - Coagulant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a coagulant capable of recovering a good quality polymer from a latex by using calcium acetate having an iron content of not more than a specific value of ppm. SOLUTION: A coagulant is produced by using calcium acetate having an iron content of not more than 0.3 ppm. The calcium acetate is available as either an aqueous solution of calcium acetate or a powder thereof. In the case of the aqueous solution, a concentration thereof is preferably not more than 20 wt.% and a pH value is suitably 7 to 8. Allowing a silicon-containing compound to act in reacting slaked lime with acetic acid can stably inhibit the incorporation of iron into the calcium acetate. As a silicon-containing compound, sodium silicate, silicon dioxide and calcium silicate are enumerated and among them sodium silicate is particularly preferable. Usually, the silicon-containing compound is added in an amount containing 0.05-0.10 wt.% of the Si content based on the amount of slaked lime in the case of sodium silicate or calcium silicate whereas in the case of silicon dioxide it is added in an amount containing 0.5-1.0 wt.% of the Si content based thereon. Quicklime may be used as a substitute for slaked lime. The coagulant is preferably used for an emulsified latex of an acrylic multilayer polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to calcium acetate used as a coagulant when recovering a polymer from an organic polymer latex, and a method for producing the same.

[0002]

2. Description of the Related Art Generally, as a method for recovering a polymer from a polymer latex which is an emulsion polymer, a method of adding an inorganic salt such as aluminum chloride, aluminum sulfate or magnesium sulfate, or a method of adding an acid such as sulfuric acid is used. There are methods.

[0003]

However, depending on the type of the inorganic salt used, the recovered polymer is affected, and the appearance of a molded product obtained by molding a resin composition comprising the polymer (hereinafter simply referred to as the molded product) is described. Appearance or molded appearance). For this reason, it is desirable that the polymer can be recovered by adding a relatively small amount of a coagulant, and that the physical properties of the resin composition obtained when the polymer is added to another resin do not deteriorate. Further, it is desirable that the water content of the coagulated powder (wet polymer) obtained at the time of recovery be low, because the drying efficiency is excellent.

As a method for recovering a polymer latex satisfying such conditions, a method of coagulating a latex obtained using an emulsifier having a specific structure with an aqueous solution of calcium acetate is effective. Proposed to be a means.

[0005] The inventors of the present invention have repeatedly studied the characteristics and the synthesis method when using calcium acetate as a coagulant. As a result, calcium acetate in which iron was mixed in a specific concentration or more from slaked lime as a raw material was converted to an acrylic resin. It has been found that there is a problem that the appearance of a molded article of the resin composition obtained when used as a coagulant is easily impaired.

[0006]

In view of such circumstances, the present inventors have studied calcium acetate capable of obtaining a good molded appearance when used as a coagulant and a method for producing the same. The iron content of 0.
By setting the content to 3 ppm or less, a good molded appearance can be maintained,
In addition, a method has been found in which, when acetic acid is reacted with slaked lime to synthesize calcium acetate, a silicon-containing compound such as sodium silicate acts to stably suppress the incorporation of iron.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The calcium acetate used in the present invention may be either an aqueous solution or a powder. However, the concentration in the case of an aqueous solution is desirably 20% by weight or less. If it exceeds 20% by weight, calcium acetate may precipitate due to saturation due to temperature change, which is not preferable. The powder is stable up to 150 ° C., but gradually decomposes into acetone and carbon dioxide gas at 150 ° C. or higher. In addition, this calcium acetate is 2
Hydrate, monohydrate up to 85 ° C to 100 ° C, dissolved in water of crystallization at 100 ° C and exists as an anhydride.

The pH of the calcium acetate of the present invention when used as an aqueous solution is preferably 7 to 8. At a pH of 7 or less, the free acetic acid content increases, and the acetic acid odor of the aqueous solution becomes strong.
If it is H8 or more, alkali hydrolysis of the polymer occurs during shaping of the polymer obtained after coagulation, and the molding appearance of the obtained resin composition may be easily impaired.

The slaked lime used as a raw material when synthesizing calcium acetate is not particularly limited for industrial use, food use and the like. Also, quicklime may be used instead of slaked lime.
Acetic acid is not particularly limited for industrial use and food use.

[0010] The iron content in the calcium acetate is 0.3 p
If it is not more than pm, the resin composition obtained by adding an acrylic polymer obtained by coagulation using the same will have a good molded appearance. If the iron content exceeds 0.3 ppm, the appearance of the molded product may become yellowish and impaired. The solidification state and solidified powder properties do not change due to the change in the iron content.

[0011] Iron, which is a problem, is contained as an impurity in slaked lime as a raw material, and reacts with acetic acid and elutes depending on the synthesis conditions. In addition, this phenomenon is closely related to the amount of impurities such as SiO ₂ other than iron contained in slaked lime, and the incorporation of iron can be prevented stably by adding a silicon-containing compound during the synthesis of calcium acetate. A clear solution without coloring is obtained.

Examples of the silicon-containing compound used include sodium silicate, silicon dioxide, and calcium silicate.
Particularly, sodium silicate is preferable. The sodium silicate may be anhydrous or hydrated. The addition amount of these silicon-containing compounds is 0.05% in terms of Si amount with respect to slaked lime in sodium silicate in the synthesis method described later.
０．１0.10% by weight, calcium silicate has a Si amount of 0.05 to 0.10% by weight based on slaked lime, and silicon dioxide has a Si amount of 0.5 to 1.0% by weight based on slaked lime. In any case, if the amount is less than the minimum amount, the eluted iron may not be completely removed. If the amount exceeds the maximum amount, the pH may exceed 8 because the silicon-containing compound is basic, and thus it is not preferable. However, in this case, there is no problem if acetic acid is added again to adjust the pH of the aqueous solution to 7 to 8.

[0013] The effect of suppressing the incorporation of iron when a silicon-containing compound is used is related to the temperature after addition and the standing time other than the addition amount. Therefore, it is desirable that the temperature and the standing time after the addition of the silicon-containing compound are left at 45 ° C. or higher for 30 minutes or more, and preferably 50 ° C. or higher for 60 minutes or more with stirring.

The synthesis of calcium acetate used in the present invention is preferably performed by the following method. (1) Add 10 parts of slaked lime to 100 parts of water, and stir and disperse well. (2) Slowly add acetic acid V ₁ amount (90% or more of the theoretical neutralization amount) to adjust the pH (pH ₁ ) of the solution to 10-11. (3) At this time, the solid content of unreacted slaked lime is drained. (4) Further, acetic acid is added in an amount of V ₂ to pH ₇ to 8 (pH ₂ ).
Adjust to (5) Sodium silicate is added by dissolving 0.05 to 0.1% in terms of Si amount with slaked lime with a small amount of pure water, and stirring is maintained at 50 ° C or higher for 1 hour or more. (6) Stop stirring, and remove slaked lime residue by filtration. (7) The obtained clear calcium acetate aqueous solution is used as it is as a coagulant. In some cases, it may be distilled and taken out as a dry powder.

[0015] Slaked lime reacts quickly with acetic acid,
A part of slaked lime tends to remain as a flour (mamako), and in this state, the fluctuation of pH becomes large due to the effect of the flour and the pH becomes 7
Difficult to neutralize to ~ 8. For this reason, it is necessary to stabilize the neutralization operation by draining or finely pulverizing the joint powder with a strong shearing force such as a homomixer. Further, as described above, the final pH (pH ₂ ) of the calcium acetate solution needs to be 7 to 8.

The elution of iron in slaked lime is related to the amount of impurities (residues) such as SiO ₂ in slaked lime during the neutralization reaction and the amount of acetic acid (V ₁ amount) that neutralizes slaked lime first. Therefore, the calcium acetate solution is adjusted to pH ₇ to 8 (pH ₂ ) without removing the impurities (residues) and leaving the residues. Alternatively, the V ₁ amount of acetic acid, which neutralizes slaked lime first, is 9 times the theoretical neutralization amount.
When it is added in an amount of 5% or more, mixing of iron is easily suppressed.

The organic polymer emulsified latex to which calcium acetate obtained by the present invention is used as a coagulant is not particularly limited, but is preferably used as an emulsified latex of an acrylic multi-layer polymer. Calcium acetate is effective for coagulating an emulsified latex of a polymer having a high graft transition and a relatively high glass transition temperature, since calcium acetate has a relatively high cohesive force of calcium ions, and has a relatively high water content. An excellent coagulated powder with low drying efficiency can be obtained.

[0018]

The present invention will be further described with reference to the following examples.
In the description, “parts” represents “parts by weight”, and “%” represents “% by weight”.

The samples used for evaluation in the examples were those obtained by injection molding a polymer solidified using the obtained calcium acetate under the following conditions.

Injection molding machine: V-17-, manufactured by Japan Steel Works, Ltd.
65 type screw type automatic injection molding machine Injection molding conditions: cylinder temperature 250 ° C, injection pressure 700
kg / cm ² Specimen size: 110 mm × 110 mm × 2 mm (thickness) The evaluation items and the measurement method are as follows.

[Stability of Neutralization Operation] In the neutralization operation during the synthesis of a calcium acetate solution, the neutralization operation is stable with almost no fluctuation in pH, and the neutralization operation is unstable when the pH fluctuation is severe. X.

[0022] [color tone of the calcium acetate solution] (APHA) platinum potassium chloride (PtCl ₄ · 2KCl) 1.245
(g) and 1.009 g of crystalline cobalt chloride were dissolved in 100 ml of hydrochloric acid and diluted with water to make 1000 ml to give a stock solution. Each of the stock solutions 10, 20, 30, 50 and 100 ml was diluted to 500 ml and used as a standard solution of color tone (APHA). (This standard solution is 10, 20, 30, 5 of APHA)
0 and 100 respectively. ) This standard solution was measured for absorption at 417 nm using a spectrophotometer (manufactured by Shimadzu Corporation, UV-160A) to prepare a calibration curve of each color tone (APHA) and absorption. The color tone of the calcium acetate aqueous solution to be used as a sample was similarly obtained from the calibration curve by measuring the absorption at 417 nm.

[Fe Content] The Fe content was determined by a plasma emission spectrometry (ICP) apparatus (manufactured by Nippon Jarrell Ash, I.
CAP-575 MK-II).

[Total transmission] (total light transmittance) ASTM-D-10
03.

[Haze value] Measured according to ASTM-D-1003.

[YI value] The YI value was measured in accordance with ASTM-D-1925.

[Forming appearance] Very good, 極 め て, and slightly poor were evaluated by visual judgment of the molded plate.

Example 1 850 ml of pure water was placed in a glass beaker having a capacity of 2 liters, and 96 g of slaked lime (manufactured by CALCEED Co., Ltd., special name S, the same applies hereinafter) was dispersed. Acetic acid (acetic acid) was stirred with a stirrer. Made by Wako Pure Chemical Industries, Ltd., special grade,
same as below. ), 137 g corresponding to 90% of the theoretical amount of neutralization, was slowly added, and the mixture was left to stir for 5 minutes. Thereafter, the solution was transferred to a separating funnel and allowed to stand for 3 minutes to settle the slaked lime residue and white flour, and then 200 ml of the residue and the like were drained from the bottom. Temperature 50 ° C. At this time the remaining solution, pH ₁ 10.9
Met. Again, the remaining solution was transferred to a glass beaker, and further acetic acid was added while stirring with a stirrer.
H _{2 was set to} 7.0. Neutralization of this time is stable and neutralized to pH ₂ 7.0 could be done quickly.

Next, sodium silicate (sodium adecameta silicate pentahydrate) was added to slaked lime at a Si content of 0.05% (40%).
0 mg) dissolved in 10 ml of pure water and added.
While maintaining the above, the mixture was left for 1 hour with stirring. Thereafter, the residue was filtered under reduced pressure using glass fiber filter paper (Whatman GF / F), and a clear calcium acetate solution (Ca
-Ac. ) Got. This solution has a concentration of 18%, p
H7.4. AP of the obtained calcium acetate solution
Table 1 shows the HA and Fe contents.

[Application Example] Using the calcium acetate solution Ca-Ac obtained in Example 1, the acrylic multi-layer polymer latex is coagulated, and a resin composition obtained by adding the obtained polymer is formed. The appearance was examined.

(1) Production of Acrylic Multilayer Polymer Latex (A) Deionized water 30 was placed in a stainless steel reaction vessel.
After charging 0 parts, the mixture was heated and when the internal temperature reached 80 ° C., a mixture having the following composition ratio was charged into the system.

Deionized water 5 parts Formaldehyde sodium sulfoxylate dihydrate (hereinafter Rongalit) 0.48 parts Ferrous sulfate 0.4 × 10 ^-6 parts Disodium ethylenediaminetetraacetate 1.2 × 10 ⁻ After holding ⁶ parts for 15 minutes, a mixture having the following composition ratio, which had been replaced with nitrogen in advance, was added dropwise over 2 hours, and polymerization was carried out for 1 hour while maintaining at 80 ° C. The polymerization rate of the obtained latex is 9
9% or more.

[0033] A monomer mixture consisting of 54.0% of methyl methacrylate, 5.0% of styrene and 41.0% of butyl acrylate 40 parts 1,3-butylene methacrylate 1.1 parts Diallyl maleate 0.14 parts t- Butyl hydroperoxide 0.08 parts 1: 1 mixture of sodium mono-n-pentylphenylhexaoxyethylene phosphate and sodium di-n-pentylphenylhexaoxyethylene phosphate (hereinafter referred to as emulsifier A) 1.20 Part (B) Subsequently, the mixture (a) having the following composition ratio was charged into the reaction vessel and maintained for 15 minutes. Then, the mixture (b) having the following composition ratio, which had been previously replaced with nitrogen, was added dropwise over 3 hours. Further polymerization was carried out for 3 hours. The polymerization rate of the obtained latex was 99% or more, and the particle diameter was 0.25 μm.

(A) Rongalite 0.2 part Deionized water 5 parts (B) Styrene 10.0 parts Butyl acrylate 50.0 parts 1,3-butylene methacrylate 0.2 parts Diallyl maleate 1.0 part Cumene 0.17 parts of hydroperoxide 1.8 parts of emulsifier A (C) Next, a mixture (C) having the following composition ratio was charged into the above-mentioned reaction vessel, kept for 30 minutes, and then replaced with the following composition which had been replaced with nitrogen in advance. The mixture (d) in the above ratio was added dropwise over 4 hours, and the mixture was further polymerized for 1 hour. The polymerization rate of the obtained latex was 99% or more, and the particle size was 0.27 μm.

(C) Rongalit 0.2 part Deionized water 5 parts (d) Methyl methacrylate 57 parts Methyl acrylate 3 parts t-butyl hydroperoxide 0.1 part Normal octyl mercaptan 0.2 parts (2) weight Coagulation of coalesced latex The 1.8% calcium acetate aqueous solution Ca-Ac obtained in Example 1 was charged into a stainless steel container as a coagulant (recovery agent), and the temperature was raised to 90 ° C. with stirring. The produced latex was continuously added at a linear velocity of 0.5 m / sec or less, and then maintained for 30 minutes. After cooling to room temperature, the polymer was filtered with a centrifugal dehydrator while washing with deionized water to obtain a white wet polymer. This was dried with a fluidized drier to obtain a polymer.

(3) Formation of the resin composition 1280 g of the solidified and recovered polymer powder obtained in the above (2)
And methacrylic resin (PL25: (PLASKO, USA)
LITE) (2,720 g) was mixed with
φ screw type extruder (P-4, manufactured by Japan Steel Works, Ltd.)
0-26AB-V type, L / D = 26), melt-kneaded at 200-260 ° C cylinder temperature and 250 ° C die temperature to form pellets, impact resistance with a multilayer acrylic elastomer content of 20% A methacrylic resin composition was obtained. Table 2 shows the results of evaluation of the total permeability, haze value, and YI of the molded plate.

Example 2 The same operation as in Example 1 was performed until 200 ml of the residue and the like were drained. Temperature of solution remaining after draining 4
8 ° C., was pH ₁ 11.1. The remaining solution was transferred to a glass beaker, further addition of acetic acid while stirring with a stirrer, and a pH ₂ 7.0. Neutralization of this time is stable and neutralized to pH ₂ 7.0 could be done quickly.

Next, silicon dioxide (99.9%, manufactured by Wako Pure Chemical Industries, Ltd.) was added to slaked lime by 1.5% (1440 m
g) was added, and the mixture was kept at 50 ° C. or higher while stirring for 1 hour. Thereafter, the residue was separated under reduced pressure using a glass fiber filter paper (Whatman GF / F) to obtain a clear calcium acetate solution (referred to as Ca-Ac). The solution concentration of 18%, and a pH ₁ 7.3. Table 1 shows the APHA and Fe contents of the obtained calcium acetate solution.

Using the obtained calcium acetate solution Ca-Ac, coagulation was carried out in the same manner as in the applied example, and the appearance of the resin composition obtained by adding the obtained acrylic polymer was examined. Table 2 shows the results of the evaluation of the total permeability, haze value, and YI of the obtained molded plate.

Example 3 The same operation as in Example 1 was performed until 200 ml of the residue and the like were drained. Temperature of solution remaining after draining 5
1 ° C., was pH ₁ 11.0. The remaining solution was transferred to a glass beaker, further addition of acetic acid while stirring with a stirrer, and a pH ₂ 7.0. Neutralization in this case stabilized, neutralized to pH ₂ 7.2 was done quickly.

Next, 0.4 g of calcium silicate (manufactured by Nacalai Tesque, Inc.) was added, and the mixture was kept at 50 ° C. or higher for 1 hour with stirring. Thereafter, the residue was separated under reduced pressure using a glass fiber filter paper (Whatman GF / F) to obtain a clear calcium acetate solution (referred to as Ca-Ac). This solution had a concentration of 18% and a pH of 7.3. Table 1 shows the APHA and Fe contents of the obtained calcium acetate solution.

Using the obtained calcium acetate solution Ca-Ac, coagulation was carried out in the same manner as in the applied example, and the appearance of the resin composition obtained by adding the obtained acrylic polymer was examined. Table 2 shows the results of the evaluation of the total permeability, haze value, and YI of the obtained molded plate.

Example 4 850 ml of pure water was placed in a 2 liter glass beaker, and 96 g of slaked lime was dispersed therein.
While stirring with a stirrer, 137 g corresponding to 90% of the theoretical amount of acetic acid was slowly added, and the mixture was left to stir for 5 minutes.
Then, the stirring of the stirrer was stopped, and instead, using a homomixer (M type manufactured by Tokushu Kika Kogyo Co., Ltd.), 5000 r
By rotating at pm for 5 minutes, slaked lime residue and white flour were pulverized. At this time, the temperature of the solution was 52 ° C. and the pH was ₁
10.8. Again, acetic acid was added while stirring with a stirrer, it was pH ₂ 7.0. The neutralization operation at this time was stable, and the neutralization to pH ₂ 7.0 was promptly performed. Here, sodium silicate (Adecameta sodium silicate 5)
Water salt) 0.05% (400 m
g) was dissolved in 10 ml of pure water and added, and the mixture was kept at 50 ° C. or higher while stirring for 1 hour.

Thereafter, the residue was filtered under reduced pressure using glass fiber filter paper (Whatman GF / F) to obtain a clear calcium acetate solution (referred to as Ca-Ac). This solution had a concentration of 19% by weight and a pH of 7.3. Table 1 shows the APHA and Fe contents of the obtained calcium acetate solution.

Using the obtained calcium acetate solution Ca-Ac, coagulation was carried out in the same manner as in the applied example, and the appearance of the resin composition obtained by adding the obtained acrylic polymer was examined. Table 2 shows the results of the evaluation of the total permeability, haze value, and YI of the obtained molded plate.

Comparative Example 1 The same operation as in Example 1 was performed until 200 ml of the residue and the like were drained. Temperature of solution remaining after draining 4
9 ° C., was pH ₁ 10.9. The remaining solution was transferred to a glass beaker, further addition of acetic acid while stirring with a stirrer, and a pH ₂ 7.2. Neutralization in this case stabilized, neutralized to pH ₂ 7.2 was done quickly.
Then, separation of the residue was performed using glass fiber filter paper (Whatman GF).
/ F) to obtain a clear calcium acetate solution (referred to as Ca-Ac). This solution had a concentration of 18% and a pH of 7.2. Table 1 shows the APHA and Fe contents of the obtained calcium acetate solution.

Using the obtained calcium acetate solution Ca-Ac, coagulation was carried out in the same manner as in the application example, and the appearance of the resin composition obtained by adding the obtained acrylic polymer was examined. Table 2 shows the results of the evaluation of the total permeability, haze value, and YI of the obtained molded plate.

Comparative Example 2 The same operation as in Example 4 was performed until the slaked lime residue and the white flour were finely pulverized. Temperature 50 ° C. At this time the solution was pH ₁ 10.6. Acetic acid was added with stirring using a stirrer again, pH ₂ 7.
0 was set. Neutralization in this case is neutralized to a stable pH ₂ 7.0 was done quickly.

Thereafter, the residue was filtered under reduced pressure using a glass fiber filter paper (Whatman GF / F) to obtain a clear calcium acetate solution (referred to as Ca-Ac). This solution had a concentration of 19% by weight and a pH of 7.0. Table 1 shows the APHA and Fe contents of the obtained calcium acetate solution.

Using the obtained calcium acetate solution Ca-Ac, coagulation was carried out in the same manner as in the application example, and the appearance of the resin composition obtained by adding the obtained acrylic polymer was examined. Table 2 shows the results of the evaluation of the total permeability, haze value, and YI of the obtained molded plate.

[Comparative Example 3] 850 ml of pure water was taken in a 2 liter glass beaker, 96 g of slaked lime was dispersed, and 145 g corresponding to 95% of the theoretical amount of acetic acid was slowly added while stirring with a stirrer, followed by stirring for 5 minutes. I left it. Thereafter, the solution was transferred to a separating funnel and allowed to stand for 3 minutes to allow slaked lime residue and white flour to settle.
1 was drained. Temperature 50 ° C. At this time the remaining solution, pH ₁
10.2. Again, the remaining solution was transferred to a glass beaker. Add acetic acid while stirring with a stirrer,
It was a pH ₂ 7.2. The neutralization operation at this time is stable, and p
Neutralization of the H ₂ 7.2 was done quickly. Thereafter, the residue was filtered under reduced pressure using glass fiber filter paper (Whatman GF / F), and a clear calcium acetate solution (Ca-A
Called c. ) Got. This solution has a concentration of 18.2%, p
H7.2. AP of the obtained calcium acetate solution
Table 1 shows the HA and Fe contents.

Using the obtained calcium acetate solution Ca-Ac, coagulation was carried out in the same manner as in the application example, and the appearance of the resin composition obtained by adding the obtained acrylic polymer was examined. Table 2 shows the results of the evaluation of the total permeability, haze value, and YI of the obtained molded plate.

[Comparative Example 4] 850 ml of pure water was taken in a 2 liter glass beaker, 96 g of slaked lime was dispersed, and 148 g corresponding to 97% of the theoretical amount of neutralized acetic acid was slowly added with stirring with a stirrer. in continuing the addition of acetic acid with stirring, and the pH ₂ 7.2. PH ₂ because the change at this time is affected undissolved lumps pH increases
Struggling to neutralize to 7.2 took time.

Thereafter, the residue was separated under reduced pressure using glass fiber filter paper (Whatman GF / F) to obtain a clear calcium acetate solution (referred to as Ca-Ac). This solution had a concentration of 18.5% and a pH of 7.2. Table 1 shows the APHA and Fe contents of the obtained calcium acetate solution.

Using the obtained calcium acetate solution Ca-Ac, coagulation was carried out in the same manner as in the application example, and the appearance of the resin composition obtained by adding the obtained acrylic polymer was examined. Table 2 shows the results of the evaluation of the total permeability, haze value, and YI of the obtained molded plate.

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

According to the present invention, calcium acetate containing a very small amount of iron can be easily synthesized, and by using it as a coagulant for an organic polymer latex, a polymer having good quality can be obtained. Can be recovered from

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takatoshi Kubo 20-1, Miyukicho, Otake City, Hiroshima Prefecture Inside the Central Research Laboratory, Mitsubishi Rayon Co., Ltd. (72) Inventor Jun Nakauchi 20-1, Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Otake Office

Claims (1)

[Claims] 1. A coagulant for an organic polymer latex, comprising calcium acetate having an iron content of 0.3 ppm or less.