DD216036A1 - PROCESS FOR PREPARING AFTERMARKING AROMATICS, GOOD FLUIDABLE, HITENABLE AMINO ILLUMINATING MASSES - Google Patents

Abstract

The invention relates to a process for producing low-postage, readily flowable, heat-retardant aminoplast molding compositions. The aim and the object of the invention is to develop such a process which, by the homogeneous incorporation of a suitable modifier, leads via a chemical modification reaction to products having the stated properties. For this purpose, acryloguanamine copolymers are incorporated into known molding compositions of melamine / formaldehyde or melamine / urea / formaldehyde type. The heat-retardant aminoplast molding compositions obtained are nachschwindungsarm and are characterized at the same time by a very good flow behavior. They can be processed by compression molding or injection molding into moldings, which can be used in particular in the electrical industry.

Description

Dr. Hannelore Herma Teltow * the 18.05.1983

Dr. Ulrich Gohlke, Dr * Slaus Dietrich Wolfgang Teige

Sitel of the invention

Process for the preparation of low shrinkage, good flowable, high curability aminoplast molding compounds

Field of application of the invention

The invention relates to a process for the preparation of molding compositions of thermosetting amino resin, which are suitable as molding or injection molding compounds, in particular for use in the electrical industry.

Characteristic of the known technical solutions

Shaped bodies which are produced from thermosetting Äminoplastformmassen vrie melamine, urea, guanarnine resins and their mixtures or mixed condensation products containing molding compositions

have the disadvantage that they considerably disappear and disappear.

Therefore, to eliminate this deficiency u. Attempts have been made to use modified thermosetting resins for the preparation of the molding compositions. , So z. B. in GB-PS 557 557 the addition of 'phenolhar'

... · ι

The disadvantages are the pronounced undesired tendency to discolour phenolic resin-containing molding compositions and the deterioration of some electrical properties, such as tracking resistance and dielectric strength. It is known from US Pat. No. 2,582,303 discloses the use of acrylonitrile-acrylate copolymers and US Pat. No. 3,081,277 and US Pat. No. 3,081,278 of polyacrylamide as additives for reducing shrinkage and improving mechanical and electrical properties. Der.Einsatz of these products, in addition to the limited availability to a considerable increase in the price of the products · Also known is the production of low-shrinkage, heat-curing Aminoplastformmassen. »The incorporated as a modifier polyvinyl acetate is in the aminous but in finely divided form. in front·

Aim of the invention; ,

The aim of the invention is, on the basis of conventional technologies, to develop a technologically simple and economically advantageous process for the preparation of low-expansion, readily flowable, thermosetting Arndnoplastformmassen by incorporation of a modifier.

Explanation of the essence of the invention; ''

- Task

The. Invention has for its object to develop a process for the preparation of such nachschwindungsarmen, good flowable, thermosetting'Aminoplastförmmassen, the

no longer have the disadvantages of the already known technical solutions produced, wherein the hodifier used for this purpose should be incorporated via a chemical modification reaction in a completely homogeneous Porm.

Features of the invention

The task can be solved according to the invention by employing an acrvloguanamine copolymer as modifier in an amount of 1 to 10% by mass, preferably 10% by mass , based on the resin content of the dry aminoplast molding composition, resulting in thermosetting It has surprisingly been found that homogeneous incorporation of the modifier into the aminoplast molding composition achieves the desired properties by a chemical modification reaction only if a very specific regimen according to the invention with respect to the type and time Thus, it is necessary that the modifier is introduced together with the amino compound at the beginning of the condensation reaction in the initially adjusted to a pH of 9.0 Pormaldehydlösung and wä During the duration of the condensation reaction, the pH is lowered by neutralization of the reaction solution to 8.0. The further processing of the amino resin solution according to the invention for Aminoplastformmasse by incorporation of customary organic and / or inorganic pulps such. 3. cellulose ,. Wood flour, kaolin, chalk, barium sulfate and optionally further additives and / or processing aids. Vorteilteilhafterweise after the known ITaßimprsgni erverfahren.

The other composition of the aminoplast molding composition corresponds to the molding compositions known per se, which consist of melamine or melamine / urea-formaldehyde as the main constituent of the resin component.

The acryloguanamine copolymers used as modifiers can be inexpensively prepared from waste polyacrylonitrile by reaction with dicyandiamide in basic medium and exclusive acid hydrolysis. ,

Sample embodiments . t '

The stated amounts in the form of γόη parts (T.) always mean mass fractions. , '·. - Preparation of amino resin solutions

Type A (standard & type / same type)

922 parts of 30 % aqueous solution of formaldehyde are heated to 85 ^° C. and added by adding a 2-molar aqueous solution

Potassium carbonate solution adjusted to a pH value of 8.5, the addition of 580 T ,. Melamine will b.ei a pH of

8.5 and a temperature of 85 ⁰ G 20 min condensed and drained the resulting resin solution.

Type B.. ,

922T * 30%. aqueous formaldehyde solution are heated to 85 ⁰ C and adjusted by addition of a 2 molar aqueous potassium carbonate solution to a pH of 9, Q, Nach. Addition of 580 T. melamine and 42.8 T.Modifikator is condensed with stirring for 20 min at 85 ⁰ C, wherein the pH of the reaction solution 5 by addition of 1 U-SaIz-. acid is lowered to 8.0, and then drained the Harslösung won.

Type C

The preparation of the resin solution takes place as in type B,

but by using 85.6 T. modifier.

Production of Aminoplastformmassen ..

Example 1 (Comparative Example)

340 parts of cellulose and 2.65 parts of magnesium stearate (as lubricant) are impregnated with 1 liter of resin solution (type A) by intensive kneading. *

Example 2 . '% . , ,

The procedure is as in Example 1, but using the resin solution type B.

Example 3.

The procedure is as in Example 1, but using the Harzlö-

Solution type C. '

The Aminoplastformmassen prepared in the individual embodiments. were conventionally pressed and tested according to TGL H 073/01, 25 571, H 067. The results are shown in Tables 1 and 2.

Table 1: Properties of the pressing males

Used molding compound after Bel- play Total Volatile .T *]. (sec Flow Md _A behavior fsec7 ^J I 1 2 3 1.1.25 10.04 9.13 47 40 43 5.75 5.6 6.8 72 112 104 .90 133 125

Table 2; Properties of the specimens

Used molding compound according to example Shrinkage [*] Slowdown in Deflection [mm] E module [MPaJ Bending strength f MPaJ Breaking force f n7 1 2 3 0.59 + 0.02 0.65 + 0.02 0.54 + 0.02 1.71 - 1.73 + 0.05 1.36 + 0.02 2.34 2.26 2.45 8.49 x 10 ³ 8.9 x 10 ³ 9.0 x 10 ³ 210 204 236 123 122 138

Claims (1)

invention claim A process for the preparation of low shrinkage, readily flowable thermosetting Aminoplastformmassen consisting of a melamine / formaldehyde or melamine / urea / Pormaldehyd ^ resin, organic and / or inorganic fillers and ggt * further additives and / or processing aids, characterized in that an acryloguanamine copolymer ^l in an amount of 1 to 10% by weight, based on the resin content of the dry aminoplast molding compound, together with the amino compound at the beginning of the condensation reaction in the initially adjusted to a pH of 9 formaldehyde solution, during the duration of this reaction, the pH lowered by neutralization to 8.0 and the recovered amino resin solution is further processed in a conventional manner to Aminoplastformmasse.