Phosphorus and nitrogen containing resin hardener and a...

Details Phosphorus and nitrogen containing resin hardener and a... Phosphorus and nitrogen containing resin hardener and a...

2000-07-19

2003-09-09

Lovering, Richard D. (Department: 1712)

Stock material or miscellaneous articles

Composite

Of epoxy ether

C252S609000, C428S417000, C428S921000, C523S435000, C525S526000, C558S077000, C528S108000, C528S118000

Reexamination Certificate

active

06617028

ABSTRACT:

FIELD OF THE INVENTION
The present invention discloses a phosphorus- and nitrogen-containing resin hardener, and a flame retarding resin composition containing said hardener.
While the flame retarding resin composition of the present invention does not contain halogen or diantimony trioxide, it has the flame retardant property of the UL94V-0 standard and high heat resistance. Therefore, it is useful in making prepregs, composites, laminates, printed circuit boards, substrates for build-ups of resin coated copper (RCC), epoxy molding compounds and the like.
BACKGROUND OF THE INVENTION
Because of easy processing, high safety, excellent mechanical and chemical properties, the composite material, especially the epoxy resin material, has been widely used in various fields such as coating, electrical insulating, construction building materials, adhesives and laminated products. Since epoxy resins have strong adhesion to reinforcement materials such as glass-fiber fabric, no volatiles while hardening, and small shrinkage in molding, a laminated plate produced by such resins has the advantages of broad range usability, good mechanical strength, good electrical insulation characteristics and excellent resistance to chemicals, etc. In addition, this laminate material is highly reliable. Thus, the laminated plate obtained has been massively applied to electrical and electronic products.
However, since the demand for finer circuits and higher density of the printed circuit board is increasing day by day, the laminated plate has been required to possess better electrical, mechanical, and heat resistant processing properties. Widely used at present, the glass transition temperature (Tg) after hardening of FR4 laminated plate is generally about 130° C. Thus, when the temperature of cutting and drilling rises over 200° C. during the process of producing the printed circuit board and over 270° C. during the welding process, the plate breaks or cracks easily. Therefore, various laminate materials which evince higher heat stability and higher glass transition temperature are constantly being developed. In addition, another important requirement for the laminated plate to possess is flame retarding properties. The flame retarding property of a printed circuit board is absolutely necessary, because safety of life and property is involved as the printed circuit board is frequently used in airplanes, automobiles and all forms of public transportation.
In order to render a flame retarding property to the laminate material, substances that separate the flame and decrease burning should be introduced. For laminated plates of epoxy resin/glass-fiber (or organic fiber) systems, halogen-containing compounds, especially bromine-containing epoxy resins and hardeners, are used, in combination with flame retarding auxiliaries such as diantimony trioxide, etc., so that the strict flame retarding standards (as UL94V-0 level) in the laminated plates can be achieved. Generally, epoxy resins reach the level of UL94V-0 standard, only when the bromine content is as high as 17 to 21%, and combines with diantimony trioxide or other flame retardants. However, the use of high bromine content epoxy resin or diantimony trioxide will doubtlessly endanger human life.
In the first place, diantimony trioxide has been considered as a carcinogen. On the other hand, bromine generates not only erosive free radicals and hydrogen bromide, aromatic compounds with high bromine content also produce toxic brominated furans and brominated dioxines during the burning process. These seriously affected the health of the human body and the environment. Thus, at the present time, it becomes most urgent to find a novel flame retarding material and flame retarding method, in order to improve the pollution and environmental protection problems resulting from using laminated plates made by the brominated epoxy resin. This requirement is especially demanding, since large amounts of FR4 type of epoxy glass fiber laminate are used.
Phosphorus compounds have been extensively studied and applied to the new generation of flame retardants designed for environmental protection. For example, red phosphorus- or phosphorus-containing organic compounds (such as triphenyl phosphonate, triphenylmethyl phosphonate, phosphoric acid and the like) are used as flame retardants to replace halogen compounds to improve the burning properties of the high molecular material or hardened-type resins. However, when these kinds of compounds are added directly to the resin, not only are massive amounts needed because of the limitation of the flame retarding efficiency of these compounds, but also the characteristics of the resin material such as electrical properties are adversely affected because of their low molecular weight and high migration property, resulting in difficulties in practice.
Recently, with the concept of reaction type flame retardant, in combination with considering environmental protection and safety, phospho-epoxy resins have been used to replace bromo-epoxy resins to obtain a flame retarding laminated plate. For example, U.S. Pat. No. 5,376,453 has disclosed a laminated plate made from epoxy-containing phosphates in combination with nitrogen-containing cyclic hardeners. However, various phosphate epoxides have been added in order to make up for the insufficient phosphorus content and to reach the hardly achievable UL94V-0 standard. In U.S. Pat. No. 5,458,978, where epoxy phosphates in combination with nitrogen-containing epoxy resins and metal complexes are used as hardeners, the glass transition temperature of the products is about 175° C., and the flame retarding properties only reach the edge of UL94V-0(42 seconds, as opposed to the critical value of 50 seconds). U.S. Pat. No. 4,973,631 and U.S. Pat. No. 5,086,156 use tri(hydrocarbyl)phosphine oxide derivatives with active hydrogen substituents (such as an amino group) alone, or in combination with other amino hardeners, to harden epoxy resins. However, the disadvantage of using hardeners to introduce phosphorus into resins is low phosphorus content. Besides, the flame retardant effects are not actually measured in these two patents.
The present inventors aim to correct the defects of the conventional techniques, promote the electrical and mechanical properties of the resin composition while decreasing the cost, and have made extensive studies to complete this invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention discloses a phosphorus- and nitrogen -containing resin hardener, which has a structure represented by the following formula:
wherein R
2
represents a hydrogen atom or a group represented by the following formula:
wherein n is an integer of from 0 to 20, and
R represents phenylene, naphthylene or a group represented by the following formula:
wherein A represents —O—, —S—, —SO
2
—, —CO—, —CH
2
—, —C(CH
3
)
2
— or a group represented by the following formula:
provided that at least one R
2
is not a hydrogen atom; and
R
1
represents NHR
2
, C
1-6
alkyl or phenyl.
In the above groups represented by R and A, the aromatic group can be substituted by one or more substituents selected from the group consisting of hydroxy, amino, carboxy and C
1-6
alkyl.
The present invention also relates to a flame retarding resin composition, which comprises (A) an epoxy resin, (B) the above-mentioned phosphorus- and nitrogen-containing resin hardener and (C) a hardening prompter.
The epoxy resin contained in the flame retarding resin composition of the present invention may be any epoxy resin, and is exemplified by glycidyl ethers of bisphenols, glycidyl ethers of biphenols, glycidyl ethers of dihydroxybenzenes, glycidyl ethers of nitrogen-containing hetero rings, glycidyl ethers of dihydroxynaphthalene, polyglycidyl ethers of phenolics, polyglycidyl ethers of polyhydric phenols and the like.
Examples of glycidyl ethers of bisphenols include bisphenol A glycidyl ether, bisphenol F glycidyl ether, bisphenol AD glycidyl ether, bisphenol S glycidyl ether, tetramethyl bisphenol A glycidyl ethe

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