Thermoplastic molding materials stable to thermal oxidation

Details Thermoplastic molding materials stable to thermal oxidation Thermoplastic molding materials stable to thermal oxidation

1997-10-28

2002-11-12

Szekely, Peter (Department: 1714)

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

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S135000, C524S151000

Reexamination Certificate

active

06479572

ABSTRACT:

The present invention relates to thermoplastic molding materials containing
A) from 5 to 97.9% by weight of a polyphenylene ether
B) from 1 to 93.9% by weight of a vinylaromatic polymer
C) from 1 to 50% by weight of an elastomeric polymer
D) from 0.1 to 10% by weight of a stabilizer mixture comprising
d
1
) at least one sterically hindered phenol,
d
2
) at least one phosphonite and
d
3
) at least one alkyl aryl phosphite,
E) from 0 to 70% by weight of a polyamide and
F) from 0 to 60% by weight of further additives and processing assistants,
the sum of the percentages by weight of components A) to F) being 100%.
The present invention furthermore relates to the use of the novel molding materials for the production of fibers, films and moldings and to the fibers, films and moldings obtainable thereby.
Polymer blends comprising polyphenylene ethers (PPE) and vinylaromatic polymers have long been known, cf. for example U.S. Pat. No. 3,383,435, U.S. Pat. No. 4,128,602 and U.S. Pat. No. 4,128,603.
Such blends are widely used for outdoor applications, for example as housing material for the electrical and electronic sector. Effective stabilization to heat and light is required for this purpose. Since the miniaturization of electronic components and circuits is increasing, the requirements for the corresponding housing materials are constantly growing because even very small components should have sufficiently high stability to thermal oxidation.
A number of publications relating to the heat stabilization of polymer blends comprising polyphenylene ethers and polystyrene are known. In U.S. Pat. No. 4,255,321, for example, mixtures of a metal sulfide, a metal oxide and a phosphite are used for the heat stabilization of PPE/HIPS blends.
DE-A 26 54 841 relates to thermoplastic molding materials based on polyphenylene ethers and high impact polystyrene, whose thermal stability is improved by adding a secondary aromatic amine or by combinations of the amine with sulfides and/or phosphites.
Furthermore, use of phosphites which contain substituted phenyl groups was disclosed in JP-A 55/025 347 for stabilizing polyphenylene ethers.
The use of sterically hindered amines in combination with phosphites, benzotriazoles or sterically hindered phenols for UV and heat stabilization of PPE/HIPS blends forms the subject of WO 81/02021.
The literature furthermore discloses that mixtures of sterically hindered phenols and phosphinites effectively protect molding materials comprising polyphenylene ethers and high impact polystyrene from heat aging (eg. EP 36 278 and EP-A 38 183).
U.S. Pat. No. 4,483,953 relates to thermoplastic molding materials comprising PPE and HIPS, which are heat-stabilized by a stabilizer system comprising ZnS, ZnO and a special diphosphite. However, the effect of the diphosphite is demonstrated only on the basis of the discoloration occurring during processing. The improvement in the color stability of thermoplastic molding materials comprising polyphenylene ether and HIPS forms the subject of EP-A 243 761. Here, mixtures of triaryl phosphates and alkyl aryl phosphites result in a better color quality after storage under UV light.
It is an object of the present invention to provide thermoplastic molding materials which have very good thermal stability to oxidation, flowability and good toughness.
These combined properties should also be possessed by mini-components. It is a further object of the present invention to provide a stabilizer combination which ensures good toughness, in particular good low-temperature toughness in the PPE blends, which should be as far as possible independent of the impact modifier used.
We have found that this object is achieved by the molding materials defined at the outset.
Preferred materials of this type and their use are described in the subclaims.
Component A
According to the invention, the polyphenylene ethers A are contained in the compositions in an amount of from 5 to 97.9, preferably from 15 to 88, in particular from 20 to 83, % by weight, based on the total composition.
The polyphenylene ethers A are known per se. They are compounds based on substituted, in particular disubstituted, polyphenylene ethers, the ether oxygen of one unit being bonded to the benzene nucleus of the neighboring unit. Polyethylene ethers substituted in the 2- and/or 6-position relative to the oxygen atom are preferably used. Examples of substituents are halogen, such as chlorine or bromine, and alkyl of 1 to 4 carbon atoms which preferably has no a tertiary hydrogen atom, eg. methyl, ethyl, propyl or butyl. The alkyl radicals may in turn be substituted by halogen, such as chlorine or bromine, or by hydroxyl. Further examples of possible substituents are alkoxy, preferably of up to 4 carbon atoms, or phenyl which is unsubstituted or substituted by halogen and/or by alkyl. Copolymers of different phenols, for example copolymers of 2,6-dimethylphenol and 2,3,6-trimethylphenol, are also suitable. Mixtures of different polyphenylene ethers may of course also be used.
Examples of polyphenylene ethers B are poly(2,6-dilauryl-1,4-phenylene ether), poly(2,6-diphenyl-1,4-phenylene ether), poly(2,6-dimethoxy-1,4-phenylene ether), poly(2,6-diethoxy-1,4-phenylene ether), poly(2-methoxy-6-ethoxy-1,4-phenylene ether), poly(2-ethyl-6-stearyloxy-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenylene ether), poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2,6-dibenzyl-1,4-phenylene ether), poly(2-ethoxy-1,4-phenylene ether), poly(2-chloro-1,4-phenylene ether), poly(2,5-dibromo-1,4-phenylene ether).
Preferably used polyphenylene ethers are those in which the substituents are alkyl of 1 to 4 carbon atoms, such as poly(2,6-dimethyl-1,4-phenylene ether), poly(2,6-diethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-propyl-1,4-phenylene ether), poly(2,6-dipropyl-1,4-phenylene ether) and poly(2-ethyl-6-propyl-1,4-phenylene ether).
For the purposes of the present invention, polyphenylene ethers are also to be understood as meaning those which are modified with monomers such as fumaric acid, maleic acid or maleic anhydride.
Such polyphenylene ethers are described, inter alia, in WO 87/00540 and are suitable in particular for blends of PPE with a polyamide.
With regard to the physical properties of the polyphenylene ether, those which have a weight average molecular weight M
W
of from 8000 to 70,000, preferably from 12,000 to 50,000, in particular from 20,000 to 49,000, are used in the compositions.
This corresponds to a limiting viscosity of from 0.18 to 0.7, preferably from 0.25 to 0.55, in particular from 0.30 to 0.54 dl/g, measured in chloroform at 25° C.
The molecular weight distribution is determined in general by means of gel permeation chromatography (Shodex separation columns 0.8×50 cm of the type A 803, A 804 and A 805 with tetrahydrofuran as eluent at room temperature). The polyphenylene ether samples are dissolved in tetrahydrofuran under superatmospheric pressure at 110° C., 0.16 ml of a 0.25% strength by weight solution being injected.
Detection is effected in general by means of a UV detector. Calibration of the columns was carried out using polyphenylene ether samples whose absolute molecular weight distributions were determined by a GPC/laser light scattering combination.
Component B
According to the invention, component B is contained in the compositions in amounts of from 1 to 93.9, preferably from 10 to 83, in particular from 15 to 78, % by weight, based on the total weight of the composition.
Components B are vinylaromatic polymers which are preferably compatible with the polyphenylene ether used.
Both homopolymers and copolymers of vinylaromatic monomers of 8 to 12 carbon atoms are suitable and are prepared in the presence of a rubber. The rubber content is from 5 to 25, preferably from 8 to 17, % by weight.
Toughened polystyrenes or copolymers of styrene and other vinylaromatic compounds are particularly suitable. Such toughened polystyrenes are generally known as HIPS, are for the most part commercially available and have a v

Affiliated with

Also associated with

Rating

Thermoplastic molding materials stable to thermal oxidation does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Thermoplastic molding materials stable to thermal oxidation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermoplastic molding materials stable to thermal oxidation will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2937254