DE1235586B - Hardeners in polyester molding compounds - Google Patents

Description

Hardeners in polyester molding compounds Polyester molding compounds are mixtures of substances the one unsaturated polyester, monomeric compounds that can be polymerized onto it and a catalyst, optionally also an accelerator. Heated you get such masses, then they harden.

A typical representative of a polyester can be prepared in the practice of the invention from the following materials as usual: Dimethyl terephthalate 46 percent equivalents (3 moles) ethylene glycol ...... 31 percent equivalents (2 moles) glycerol (95%) .. .. 23 percent equivalents (1 mol) The aforementioned compounds were placed together with xylene or a similar solvent, which prevents evaporation of the lower dialkyl esters of the acids, in a three-necked flask, which has a thermometer, a stirrer and a Vigreux column with a Dean and Stark template and an additional funnel on the column. In addition, a protective nitrogen atmosphere was created in this system. The system was heated for about 30 minutes, during which time the vessel temperature rose to 130 ° C and the water and xylene distilled off azeotropically. Then 0.03 percent by weight, based on the weight of the dimethyl terephthalate, of lead acetate was added as alcoholysis catalyst and heating was continued for about a further 31/2 hours, reaching a final temperature of 240.degree. The polyester was then cooled and comminuted.

It should also be emphasized that of course - if so desired is - many variations can be made in the aforementioned polyester. For example can the polyesters of the type described above with the condensation products or Reaction products of other polyol materials or with other or similar polybasic ones Acids or acid derivatives are implemented.

The subject of the invention is the use of hydroquinone-bis-trimellitic anhydride as a hardener in customary polyester molding compositions or coating compositions.

In the polyester molding compositions according to this invention, the hydroquinone-bis-trimellitic anhydride is used combined with the polyester in stoichiometric amounts.

Monomers and other catalysts are not needed in the bulk.

A powdered polyester molding compound was produced by that 100 parts of the above-described preferred polyester resin together with 3 Parts of titanium dioxide as a pigment and 2.5 parts by weight of a thixotropic, from the Gas phase produced silica were used.

EXAMPLE 100 g of polyester resin were added to the aforementioned molding material 21 g of hydroquinone-bis-trimellitic anhydride were added, which was thereby produced was that equivalent parts of trimellitic anhydride and hydroquinone diacetate were implemented, although this implementation is not to be protected here. One 3 g sample from finely powdered material of the mass produced in this way was heated to a temperature heated from 197'C, where it was found that the time required for yellowing was about 6 minutes; this test was on a Sunshine Gelatinizer carried out. When the powdered material using a fluidized bed process on wire and splint-like particles of wire coated in this way were assembled and cured for 10 minutes at 220 ° C, a force of 3.5 English pounds are necessary to pull the sapwood-like particles apart at 200'C. The Rockwell hardness of a coating that is at Hardened at 220 ° C was determined to be 43. The Rockwell Hardness Test is a measure of cut through resistance or for the resistance of the coatings to impairments high pressure.

Motor stands that were coated with the molding compounds had dielectric ones Constants greater than 2400 volts per mil and also showed good electrical otherwise Coating and physical characteristics.

Claims (1)

Claim Use of hydroquinone-bis-trimellitic anhydride as a hardener in customarily structured polyester molding or coating compositions.