Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-01-24
2003-10-21
Harlan, Robert (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S122000, C524S123000, C524S415000, C524S416000
Reexamination Certificate
active
06635697
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flame-retardant as well as a flame-retarding resin composition incorporated with the flame-retardant. More particularly, it relates to a non-halogen type flame-retardant and a flame-retarding resin composition possessing excellent flame retarding property and being capable of stably exhibiting an outstanding moisture-resisting property.
2. Description of the Prior Art
From the past, various flame-retarding treatments are applied on actual use of a thermoplastic resin for preventing or suppressing fire, and a range of the application is still being spread even now. In general, a variety of flame-retardants have been incorporated into thermoplastic resins for making themselves flame-retardative. The flame-retardants are roughly classified into a halogen type flame-retardant and a non-halogen type flame-retardant.
With respect to the halogen type flame-retardant, toxicity of acidic gas such as hydrogen chloride or hydrogen bromide generated on combustion of the retardant is pointed out from the past. In recent years, moreover, fear of generating extremely toxic dioxin has come into question. Consequently, the non-halogen type flame-retardant now attracts public attention.
The non-halogen type flame-retardant is roughly classified into an endothermic flame-retardant and an adiabatic film-forming flame-retardant. Mentioned as the endothermic flame-retardant are metal hydroxides such as magnesium hydroxide and aluminum hydroxide. As compared with the halogen type flame-retardant, the endothermic flame-retardant is weak in toxicity of a gas evolved at the time of burning but it has to be incorporated in a larger amount into a resinous material such as polyolefin for exhibiting satisfactory flame-retarding effect, thus causing a problem such as deterioration of physical properties of the resin used.
On the other hand, mentioned as the adiabatic film-forming flame-retrdant are a glass film-forming flame-retardant such as a low melting point glass or a silicone and a char-forming flame-retardant containing red phosphorus, a phosphoric ester, an amine salt of phosphoric acid and/or a salt of polyphosphoric acid as an effective ingredient.
For practical use, however, the aforesaid adiabatic film-forming flame-retardant involves a problem to be solved. For example, the low melting point glass and the silicone are not satisfactory in flame-retarding property so that the sort of resins is thus limited, while red phosphorus evolves a toxic gas such as phosphine during combustion for producing char. Further, the phosphoric ester is poor in flame-retarding property and low in melting point, thus creating a problem in molding of a resin used.
Contrary to this, a certain degree of flame-retarding property can be expected in the amine salt of phosphoric acid and the salt of polyphosphoric acid so that these are watched as a non-halogen type flame-retardant.
As the salt of phosphoric acid is inferior in moisture-resisting property, however, a resin composition incorporated therewith involves a problem such that when mixed with a hygroscopic filler, the retardant adheres to a screw or the like parts due to heated steam thereby deteriorating moldability of the resin, or alternatively, the retardant tend to bleed out on the surface of the resultant moldings due to moisture in atmosphere thereby giving rise to a problem of whitening on the surface of the moldings.
Under the aforesaid circumstances, several methods have been proposed for improving moisture-resisting property of the salt of phosphoric acid. For example, a method for preparing ammonium type II crystalline polyphosphate excellent in moisture-resisting property is proposed in Japanese Patent Publn. No. Sho. 60-6885 and a method for improving moisture-resisting property by providing a melamine coating on ammonium polyphosphate is proposed in Japanese Laid-open Patent Appln. No. Hei. 6-263416.
Problem to be Solved by the Invention
However, the flame-retardant thus treated tends to lose moisture-resisting property partially on account of destroy of a water-repellent film, i.e. the melamine layer due to internal shear in the course of melt-kneading and molding. Accordingly, there is a space for improving defect during the molding process and for preventing whitening of the resulting moldings.
It is an object of the present invention to provide a flame-retardant comprising a specific aliphatic amine salt of phosphoric ester and a salt of phosphoric and/or polyphosphoric acid in a specific proportion and being capable of exhibiting excellent flame-retarding property and stable moisture-resisting property.
It is another object of the present invention to provide a flame-retarding resin composition which comprises a thermoplastic resin incorporated with the aforesaid flame-retardant in a specific proportion and is furnished with excellent flame-retarding property jointly with stable moisture-resisting property.
Means for Solving the Problem
As a result of the extensive research made by the present inventors for solving the problem above mentioned, it has now been found surprisingly that conjoint use of a specific aliphatic amine salt of a phosphoric ester with a salt of phosphoric and/or polyphosphoric acid as a flame-retardant ingredients in a specific proportion exhibits excellent flame-retarding effect and that a thermoplastic resin incorporated with the flame-retardant in a specific proportion exhibits excellent flame-retarding property in combination with moisture-resisting property in the course of molding of the resin. The present invention has been accomplished on the basis of the above finding.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a flame-retardant which comprises (a) an aliphatic amine salt of a phosphoric ester with 2-25 carbon atoms in the ester moiety thereof having a melting point of at least 100° C. but not more than a molding temperature of a thermoplastic resin to be used and (b) a salt of phosphoric and/or polyphosphoric acid, the proportion of the component (a) to the component (b), i.e. (a)/(b) being 1/2-5/1 by weight ratio.
In accordance with the present invention, there is also provided a flame-retarding resin composition which comprises 100 parts by weight of a thermoplastic resin incorporated with 15-150 parts by weight of the aforesaid flame-retardant.
As one embodiment of the flame-retarding composition, there may be given a composition which comprises 100 parts by weight of a thermoplastic resin incorporated with (a) 10-100 parts by weight of an aliphatic amine salt of a phosphoric ester with 2-25 carbon atoms in the ester moiety having a melting point of at least 100° C. but not more than shaping temperature of the thermoplastic resin and (b) 5-50 parts by weight of a salt of phosphoric and/or polyphosphoric acid, the proportion of the component (a) to the component (b), i.e. (a)/(b) being 1/2-5/1 by weight ratio.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
As to the salts of phosphoric and/or polyphosphoric acid utilizable for the component (b) of the flame-retardant of the present invention, any of the known salts employed as flame-retardant can be used without limitation. Above all, salts of phosphoric acid and/or polyphosphoric acid with a metal of the Groups IA-IVB of the Periodic Table, ammonia, an aliphatic amine and an aromatic amine is preferable. Illustrative of the typical salt are, for example, metal salts such as lithium, sodium, calcium, barium, iron (ferrous and ferric), and aluminum salts; ammonium salt; aliphatic amine salts such as methylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, and piperazine salts; and aromatic amine salts such as pyridine, triazine and melamine salts.
In the flame-retardant of the present invention, the salts of phosphoric and/or polyphosphoric acid permit the formation of polyphosphoric acid on burning to promote carbonization of polyolefin so that they function to form a protective film on the surface
Kuwaki Tetsuo
Muneuchi Yasuhiro
Nakamura Yasunobu
Armstrong Westerman & Hattori, LLP
Harlan Robert
Idemitsu Petrochemical Co. Ltd.
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