Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-03-26
2001-09-11
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C523S200000, C523S205000, C523S210000
Reexamination Certificate
active
06288155
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel thermal stabilizer for halogen-containing resins, a halogen-containing resin composition blended with the thermal stabilizer, and a halogen-containing resin-molded article produced by molding the resin composition. More specifically, the invention relates to a compound of the dolomite-type, which is surface treated with a specific compound, a novel thermal stabilizer for halogen-containing resins, which contains the compound of the dolomite-series and the zinc salt of an organic acid, and a halogen-containing resin-molded article produced by molding such a resin composition.
2. Description of the Background
Halogen-containing resins such as vinyl chloride resin are highly flame retardant and have excellent properties including light resistance, recycling potency and chemical resistance. Therefore, the resins are widely used in building materials, pipes, cable coating materials, various sheets, various films and containers.
During molding with the application of heat, the quality of these halogen-containing resins deteriorates. For example, thermal coloring of the resin occurs and the physical properties of the resin such as strength deteriorate because of thermal decomposition of the resin which is accompanied by dehydrohalogenation. In order to overcome such problems, generally, stabilizers are incorporated into halogen-containing resins in order to improve the thermal stability of resins. Suitable such stabilizers (referred to as “thermal stabilizers” hereinbelow) conventionally include metal salts of organic acids such as fatty acids, aromatic carboxylic acids and amino acids. More specifically, lead salts and cadmium salts thereof have been widely used because of their satisfactory property as a thermal stabilizer. Very large amounts of lead-series stabilizers have been used. Because of the seriousness of the toxic problems encountered by using lead salts, their use has been limited. Attention is now focused on organic acid salts of zinc as a safe, alternative thermal stabilizer to the lead stabilizers. However, the thermal stabilization effect of zinc based thermal stabilizer is not satisfactory in comparison to lead based stabilizers. A need, therefore, continues to exist for a zinc based thermal stabilizer for halogen containing resins which exhibits high safety and at the same time exhibits good thermal stabilizing properties.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a halogen-containing resin composition with a great safety profile and excellent thermal stability.
Briefly, this object and other objects of the present invention as hereinafter will become more readily apparent can be attained by a thermal stabilizer for halogen-containing resins which is a blend of a dolomite compound an organic acid salt of zinc.
Another aspect of the invention is a halogen-containing resin composition stabilized with the thermal stabilizer of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In order to prepare the thermal stabilizer of the present invention a compound of the dolomite series is surface treated with at least one compound selected from inorganic zinc compounds, organic acids, metal salts of organic acids, and polyhydric alcohol compounds.
In accordance with the invention, any compound of the dolomite series may be employed, including dolomite from natural diverse sources, which have been used in the manufacture of wall materials and refractory materials for the iron industry. However, the dolomite used in the invention is not limited to these sources. Because dolomite is of a chemical composition of a complex salt of calcium carbonate and magnesium carbonate, additionally, a chemically synthesized complex salt of calcium carbonate and magnesium carbonate, namely synthetic dolomite, may also be used as the dolomite of the invention. A synthetic dolomite with any composition at a certain ratio of calcium and magnesium may be satisfactorily used in the invention. The weight ratio of calcium and magnesium in the synthetic dolomite used in the invention is preferably within a range of 5:95-95:5 on the basis of MgO and CaO. If a synthetic dolomite outside the constituency range above is employed, the product obtained does not exhibit a satisfactory thermal stabilization effect.
Derivatives of these natural and/or synthetic dolomites, as produced by modifying the dolomites by burning or slaking with no great modification of the composition of the metal elements, may also be used. More specifically, the derivatives include dolomite cement produced by heating the dolomites at 700-800° C., a lightly burned dolomite produced by heating the dolomites at 900-1000° C., a deadly burned dolomite produced by hard burning the dolomites at a high temperature of 1600-1800° C., and dolomite slaked lime produced by adding water to a lightly burned dolomite for digestion, and synthetic magdoloclinker. Other derivatives which may be used include those produced by modifying natural minerals and synthetic complex salts, within the same range of the calcium/magnesium ratio of the synthetic dolomite, in the same manner as described above. Suitable such materials are Acherumanite (Ca
2
MgSi
2
O
7
), transparent pyroxene (CaMg (SiO
3
)
2
) and various slags. Furthermore, appropriate mixtures thereof may be satisfactory as well.
In the specification, these dolomites and derivatives are generically referred to as compounds of the dolomite series. These compounds are industrially produced on a large scale in various fields and are used in very diverse industries including the iron industry, the porcelain industry, the building materials industry and agriculture. Because of their stable quality, these materials are readily available economically. When used, especially, the lightly burned dolomite, can produce halogen-containing resin compositions having great thermal stability.
In accordance with the invention, compounds of the dolomite-series which have been surface treated with a specific compound are preferably used. The compounds which are used for the surface treatment (treating agent) include inorganic zinc compounds, organic acids, organic acid metal salts, and polyhydric alcohol compounds. These compounds may be used singly or in appropriate mixtures.
Suitable inorganic zinc compounds include, for example, zinc oxide, zinc carbonate, zinc sulfate, zinc phosphate, zinc sulfite, zinc phosphate and zinc hydroxide. Further, appropriate mixtures of these compounds or complex salts thereof may be employed.
Suitable organic acids include, for example, saturated aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, octanoic acid, lauric acid, stearic acid, behenic acid; saturated aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, terephthalic acid; unsaturated aliphatic carboxylic acids such as acrylic acid, oleic acid, crotonic acid, fumaric acid; carbocyclic carboxylic acids such as benzoic acid, camphoric acid, phthalic acid, toluic acid, hydratropic acid, cinnamic acid; heterocyclic carboxylic acids such as furoic acid, thenoic acid, pyrrolidone carboxylic acid, nicotinic acid; hydroxycarboxylic acids or alkoxycarboxylic acids such as lactic acid, malic acid, benzilic acid, salicylic acid, anisic acid, vanillic acid, protocatechuic acid, gallic acid; amino acids or amino acid derivatives such as glutamic acid, lysine, aspartic acid, glycine, N-stearoyl glycine, N-acetyl glutamic acid, N-lauroyl leucine, &ggr;-methyl glutamate, and the like.
Suitable organic acid metal salts include the metal salts of the organic acids described above. These metals include zinc, calcium, magnesium, potassium, sodium, lithium, iron, aluminum, nickel, copper, and manganese. Furthermore, an appropriate mixture of these organic acid metal salts or a complex salt thereof may also be satisfactory. Surface treatment of the dolomite compound with these organic acid zinc salt
Atarashi Yasunori
Miyachi Yasuyoshi
Tanaka Takeo
Yasuda Naoki
Ajinomoto Co. Inc.
Cain Edward J.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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