Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-03-10
2002-04-23
Barts, Samuel (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S303000, C568S350000, C568S382000, C568S383000, C560S174000, C560S178000
Reexamination Certificate
active
06376719
ABSTRACT:
TECHNICAL FIELD
This is the National phase Application of PCT/J199/03653, filed Jul. 6, 1999.
The present invention relates to an alkaline earth metal salt of a &bgr;-diketo compound which is used as an auxiliary for resin molding, and to a method for producing the same.
BACKGROUND ART
Alkaline earth metal salts of &bgr;-diketo compounds (hereinafter, referred to as &bgr;-diketo compound salts or salts of &bgr;-diketo compounds) are utilized as auxiliaries for resin molding, particularly, as nonpoisonous or nontoxic stabilizers for vinyl chloride resin molding.
Various methods for producing the &bgr;-diketo compound salt are known. For example, Zh. Neorg. Khim. (1990), 35(11), 2776-80 discloses a method for producing a &bgr;-diketo compound salt by a reaction between acetylacetone and calcium chloride or calcium nitrate. However, the method is disadvantageous in terms of quality, because it is necessary to remove impurities such as a chloride and a nitrate (or anitric acid salt) contaminating the resulting &bgr;-diketo compound salt (acetylacetonato).
Japanese Patent Publication No. 24777/1985 (JP-B-60-24777) describes a method for producing a &bgr;-diketo compound salt by adding an alkaline earth metal hydroxide to a &bgr;-diketo compound (e.g., acetylacetone) in a ratio of 1 mol of the former to the equivalent (2 mol) of the latter. However, according to this method, the viscosity rises in the latter half of the reaction, increasing the load on the power that the mixer requires. For such reasons, the method involves an expensive reactor, and thus is industrially disadvantageous. Further, the &bgr;-diketo compound salt thus obtained is not suitable for use as a stabilizer, because the salt contains about 6 to 7% by weight of moisture (corresponding to one molecule of water of crystallization). For example, when a stabilizer containing water of crystallization is used in molding a vinyl chloride resin, bubbling due to water vapor remarkably deteriorates the strength and clarity (transparency) of the vinyl chloride resin. Furthermore, since the stability of the &bgr;-diketo compound salt produced in accordance with the process of the literature is low, the salt cannot be preserved for long periods of time. For example, when a calcium salt of acetylacetone produced according to the method is dried to a water (moisture) content of 1% by weight or less, the purity of the salt is remarkably lowered from 97% by weight to 86% by weight in a month.
Furthermore, German Patent DE96-19610320 describes a method for producing a &bgr;-diketo compound salt by adding a &bgr;-diketo compound (e.g., acetylacetone) to an alkaline earth methyl hydroxide in the absence of a solvent using 1 mol of the latter and the equivalent (2 mols) of the former. In the method described in this literature, the &bgr;-diketo compound is added to the alkaline earth metal hydroxide and reacted at 40° C. or lower, thus preventing the viscosity of the reaction mixture from becoming too high and making it possible to react the reaction mixture in the form of particles or powder. However, according to the method of the literature, the &bgr;-diketo compound needs to be added slowly in order to prevent the viscosity from becoming too high. Therefore, it takes time to complete the reaction, the conversion is low (for example, about 94% when hydrated lime is used), and the resulting &bgr;-diketo compound salt is of lower purity.
Accordingly, it is an object of the present invention to provide highly stable &bgr;-diketo compound salts of higher quality and a method for producing the same.
It is another object of the present invention to provide, regardless of a reactant being reacted in powdery form (or in the form of particles), a method whereby &bgr;-diketo compound salts of high purity can industrially advantageously be produced at high conversions without an increase in viscosity.
It is still another object of the present invention to provide a method for effectively producing &bgr;-diketo compound salts within a short period of time without lowering the conversion and purity.
DISCLOSURE OF INVENTION
The inventors of the present invention have found that, when an alkaline earth metal hydroxide such as calcium hydroxide remains unreacted, the purity of a &bgr;-diketo compound salt is remarkably decreased during its preservation probably because of the condensation of an acetylacetone unit of the &bgr;-diketo compound salt. Based on such knowledge, the inventors did intensive research to achieve the above objects, and finally found that, when an aliphatic &bgr;-diketo compound is used in an excess amount relative to the amount of an alkaline earth metal compound, the resulting &bgr;-diketo compound salt is of high purity and highly stable. The present invention was accomplished based on the above findings.
In summary, the present invention is a method for producing an alkaline earth metal salt of a &bgr;-diketo compound from a powdery alkaline earth metal compound and an aliphatic &bgr;-diketo compound, wherein 2.04 mol or more of the aliphatic &bgr;-diketo compound is used relative to 1 mol of the alkaline earth metal compound. The reaction may be carried out while supplying the alkaline earth metal compound and the aliphatic &bgr;-diketo compound continuously or intermittently, or by adding one component to the other continuously or intermittently. The total amount of each component used need only be within the above range, and the amount of each component in a reaction stage or a supply stage need not be within the above range. Furthermore, the highest temperature throughout the reaction may be 50° C. or higher, and a drying operation may be conducted at 100 to 180° C. in an atmosphere of an inert gas. The alkaline earth metal compound may be calcium hydroxide, magnesium hydroxide, or barium hydroxide. Moreover, the aliphatic &bgr;-diketo compound may be represented by the following formula (1):
wherein R
1
and R
2
are same or different, each representing hydrogen atom, a C
1-6
alkyl group, or a C
1-10
alkoxy group,
or may be an acetoacetic acid C
1-4
alkyl ester or acetylacetone.
Furthermore, the alkaline earth metal salt of the &bgr;-diketo compound of the present invention is produced according to the method as described above. The alkaline earth metal salt of a &bgr;-diketo compound contains 1% by weight or less of water (moisture) and has a purity of not less than 98% by weight.
BEST MODE FOR CARRYING OUT THE INVENTION
[Alkaline earth metal compound]
As the alkaline earth metal compound, there may be exemplified hydroxides of alkaline earth metals (for example, magnesium hydroxide, calcium hydroxide, and barium hydroxide). These alkaline earth metal compounds may be used singly or as a combination of two or more species.
The alkaline earth metal compound may be used in the form of particles or in powdery form. Those commercially available for industrial use may be used as they are. The mean particle size of the alkaline earth metal compound is about 0.1 to 300 &mgr;m, preferably about 0.1 to 150 &mgr;m.
Further, it is preferred that the alkaline earth metal compound contains little or no impurities (e.g., silica, alumina, alkaline earth metal carbonates). The amount of impurities is, for example, 2% by weight or less, preferably 1% by weight or less, more preferably 0.5% by weight or less.
[Aliphatic &bgr;-diketo compound]
As the aliphatic &bgr;-diketo compound, compounds of the formula (1) may be used. In the formula (1), R
1
and R
2
may be same or different, each representing a hydrogen atom, a C
1-6
alkyl group (for example, C
1-4
alkyl groups such as methyl and ethyl groups), or a C
1-10
alkoxy group (for example, C
1-6
alkoxy groups such as methoxy, ethoxy, propoxy and butoxy groups). For example, there are exemplified compounds having a 2,4-alkanedione or acetoacetic acid ester structure.
Preferred aliphatic &bgr;-diketo compounds are compounds represented by the formula (1) wherein R
1
is a C
1-4
alkyl group (e.g., methyl group, ethyl group) and R
2
is a C
1-4
alkyl grou
Barts Samuel
Birch & Stewart Kolasch & Birch, LLP
Daicel Chemical Industries Ltd.
Prize Elvis O.
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