Flame retardant polybutyleneterephthalate resin

Details Flame retardant polybutyleneterephthalate resin Flame retardant polybutyleneterephthalate resin

2002-05-10

2003-08-26

Acquah, Samuel A. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C528S275000, C528S279000, C528S280000, C528S281000, C528S283000, C528S285000, C528S298000, C528S302000, C528S307000, C528S308000, C528S308600, C528S287000, C525S437000, C524S408000, C524S409000, C524S413000, C524S424000, C524S425000, C524S430000, C524S431000, C524S432000, C524S433000, C524S434000, C524S436000, C524S437000, C524S442000, C524S445000, C524S449000, C524S451000, C524S777000, C524S783000, C524S784000, C524S785000, C524S786000, C524S788000, C524S791000

Reexamination Certificate

active

06610796

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a flame retardant polybutyleneterephthalate resin and, more particularly, to a non-halogen-based reaction type phosphorus-based fire retardant retardant and flame retardant polybutyleneterephthalate resin thereof applicable to the frame, housing, socket and connector of electric/electronic equipment or office machines.
BACKGROUND ART
In general, polybutyleneterephthalate is applied to the frame, housing, socket and connector of electric/electronic equipment, electric home appliances or office machines because of its excellent chemical resistance, appearance, mechanical properties and electric insulation. Polybutyleneterephthalate, which is useful for various types of products, is required to have fire retardancy for the use purpose in a wide range of applications, awhile fire retardancy is necessary to polyethyleneterephthalate only used for special cases such as fire retardant thread. However, polybutyleneterephthalate is susceptible to combustion in the air because of its limited oxygen index(LOI) being 23, and thus relatively poor in fire retardancy.
There are two known methods for providing fire retardancy to the polybutyleneterephthalate combustible in the air: the one is a blend method in which a fire retardant is added during preparation or molding of polybutyleneterephthalate; and the other is a copolymerization method in which a fire retardant is incorporated with a polybutyleneterephthalate unit through copolymerization.
The blend method utilizes a halogen-based fire retardant, a red phosphorus-based fire retardant, an antimony oxide compound, a phosphorus-based flame retardant, and hydrated metal oxide, which are used either alone or in combination of two or more. In the blend method, however, the flame retardant is slowly released from the product to deteriorate the flame retardancy and a large amount of flame retardant is required even in combination with a flame retardancy synergistic agent or a flame retardant assistant agent, resulting in deteriorated properties and raised costs. The halogen-based flame retardant readily produces a large amount of halogen compounds, especially, halogenated dioxin, which is at issue in recent years. The red phosphorus-based fire retardant is also not an environment-friendly compound because it produces toxic phosphine gas.
Conventionally, halogen compounds having an ester-forming group or phosphorus compound are known as a flame retardant that can be used in the copolymerization method. Especially, phosphorus compounds are superior to halogen compounds in that they have excellent light resistance and hardly produce halogenated compounds such as halogenated dioxin during combustion.
The phosphorus compounds are known to be of a polyester copolymerization type. As disclosed in U.S. Pat. No. 4,157,436, the phosphorus compounds can be used in the preparation of copolymer type flame retardant polybutyleneterephthalate without any problem but cause many problems in the preparation of polybutyleneterephthalate. More specifically, the use of the phosphorus compound in the preparation of polybutyleneterephthalate may deteriorate the polymerization reactivity and cause a reaction of the phosphorus compound and the polymerization catalyst to form a gel and hence deteriorate the catalytic activity of the catalyst. The phosphorus compound also reacts with a diol component of the material, 1,4-butanediol to yield tetrahydrofuran and water, which deteriorate the polymerization rate and prevent the progress of the polymerization reaction. Hence there is no report on the preparation of copolymerization type flame retardant polybutyleneterephthalate.
Unlike the case of polyethyleneterephthalate, the choice of a flame retardant and the polymerization conditions are of great significance in the preparation of flame retardant polybutyleneterephthalate that has excellent flame retardancy, properties and environment-friendly property.
Recently, major electric/electronic companies in Japan are restraining the use of halogen-based flame retardant polybutyleneterephthalate and expect an alternative of the red phosphorus-based flame retardant polybutyleneterephthalate which is still used in many companies. The Japanese government is planning to restrict the use of halogen- or red phosphorus-based flame retardant polybutyleneterephthalate. Furthermore, the use of polybrominated biphenyl, decaphenyl, octaphenyl and pentaphenyl is legally restricted in German and Holland. Nevertheless, halogen- or red phosphorus-based flame retardant polybutyleneterephthalate is still in use, since there is no substitute available in the market.
DISCLOSURE OF INVENTION
It is an object of the present invention to solve the problems in preparation of polybutyleneterephthalate using the copolymerization method and to provide a polybutyleneterephthalate resin that is incorporated with an economical and environment-friendly non-halogen-based flame retardant containing no halogen and prepared by copolymerization of a phosphorus-based flame retardant and a butyleneterephthalate unit to have good flame retardancy and remarkably improved properties.
It is another object of the present invention to provide a polybutyleneterephthalate resin in which a deterioration of crystallization rate caused by the use of the phosphorus-based flame retardant is avoidable.
It is further another object of the present invention to provide a polybutyleneterephthalate resin in which a deterioration of mechanical properties caused by the use of the additive type phosphorus-based flame retardant is avoidable.
To achieve the objects of the present invention, there is provided a flame retardant polybutyleneterephthalate resin being prepared by: (a) performing a transesterification reaction of a dicarboxylic acid or its ester derivative and a 1,4-butanediol to yield a oligomer; (b) adding the oligomer with 0.5 to 30 parts by weight of a phosphorus-based flame retardant represented by the following formula I with respect to 100 parts by weight of the dicarboxylic acid or its ester derivative; and (c) reacting a polycondensation reaction in the presence of a polycondensation catalyst to prepare a polybutyleneterephthalate:
wherein R
1
and R
2
are same or different and are methyl or butyl including a hydroxyl group.
In another aspect of the present invention, the flame retardant polybutyleneterephthalate resin further comprises a deposited particle-forming material or an inorganic particle material incorporated during the polymerization reaction or after the preparation of the resin lest incorporation of the phosphorus-based flame retardant having the formula I should impair the crystallization rate.
In further another aspect of the present invention, the flame retardant polybutyleneterephthalate resin further comprises a reinforcing material, which is added to the polybutyleneterephthalate resin obtained using the phosphorus-based flame retardant having the formula I.
Now, the present invention will be described in further detail as follows.
The flame retardant polybutyleneterephthalate of the present invention is prepared by reacting dicarboxylic acid or its ester derivative with 1,4-butanediol as starting materials to produce an oligomer, adding 0.5 to 30 parts by weight of the phosphorus-based flame retardant represented by the formula I to the oligomer with respect to 100 parts by weight of the dicarboxylic acid or its ester derivative, and adding a polycondensation catalyst.
Conventionally, a blending method of incorporating a large amount of a red phosphorus type compound as a flame retardant has been adapted to make polybutyleneterephthalate show flame retardancy. In this case, the flame retardant is simply dispersed in the polymer to result in a deterioration of flame retardancy and properties. So, the blending method requires a large amount of the flame retardant or additionally a flame retardant assistant agent.
Only if the phosphorus compound exists in the polymer chain, polybutyleneterephthalate can be more excellent in flame retardancy with a sm

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