CS231337B1 - Process for the production of modified melamine-formaldehyde mass - Google Patents

Abstract

Method of producing a modified melamine formaldehyde material suitable for injection molding and extrusion. Wastes resulting from the distillation of 6-caprolactam with an extinction of 1 to 20, with a volatile base content of up to 25 mgeq/kg in an amount of 1 to 100% by weight based on the weight of melamine, were used for modification. Production in one operation with mixing at temperatures of 60 to 150 °C. Good rheological, enthalpic and physical-mechanical properties of the resulting aminoplast were achieved.

Description

(54) Method of producing modified melamine formaldehyde material

Method of producing a modified melamine formaldehyde material suitable for injection molding and extrusion. Wastes resulting from the distillation of 6-caprolactam with an extinction of 1 to 20, with a volatile base content of up to 25 mgeq/kg in an amount of 1 to 100% by weight based on the weight of melamine, were used for modification. Production in one operation with mixing at temperatures of 60 to 150 °C. Good rheological, enthalpic and physical-mechanical properties of the resulting aminoplast were achieved.

The invention relates to a method of producing a modified melamine-formaldehyde material suitable for injection molding and extrusion processing.

Melamine-formaldehyde modified aminoplasts are thermosetting molding compounds that are applied mainly to technically complex and demanding moldings.

One of the most preferred modifiers appears to be 6-caprolactam, or other lactams or omega-aminocarboxylic acids /Czech copyright certificate No. 212 873, German patent 1 595 386,

720 284, 1 576969, 1 594 497 and 2 328 431/. However, the mentioned modifiers have a high selling price and their production is energy-intensive. Therefore, commodifiers, e.g. based on fructose, are used /Swiss patent 540 947, 562 270/. However, this solution requires considerably long polycondensation times and is therefore not economically significantly more advantageous.

The above disadvantages are eliminated by the method of producing melamine formaldehyde mass modified with 6-caprolactam according to the invention, in which polycondensation is carried out in the simultaneous presence of catalysts, melamine, formaldehyde and fillers or in the simultaneous presence of formaldehyde and cellulose catalysts, with melamine and any other fillers being dosed during polycondensation, which takes place at temperatures of 60 to 150 °C.

The essence of the invention consists in using as modifiers waste from the distillation of 6-caprolactam defined by extinction 1 to 20 and volatile base content up to 25 mgeq/kg in an amount of 1 to 100% by weight based on the weight of melamine.

The modified thermoset according to the invention exhibits high physical-mechanical, rheological and enthalpic properties, and is particularly suitable as an injection material for electrical and electronic components. In addition, previously unprocessed waste is utilized, which, among other things, will have a positive effect on the quality of the environment and, due to its possible removal during rectification, on the quality of the produced 6-caprolactam. These waste materials are unusable for the production of polyamides due to the content of bases, oxidation products of 6-caprolactam oxidation and cyclohexanone oxime.

These substances, even in trace amounts, inhibit the polymerization of 6-caprolactam, but do not affect its incorporation into the emerging polymer network of aminoplasts, or are incorporated into this network in a similar manner. The process according to the invention achieves cost savings of approximately 250 to 12,500 CZK per ton of modified aminoplasts produced, depending on the degree of modification.

Design examples

1. The following components are introduced into a stirred reactor at a temperature of 100 °C:

melamine 370g technical formaldehyde 36% 415g 6-caprolactam distillation residue on extinction 1 to 10 mgeq/kg of volatile bases 37 grams H ₃ P°4 5. g ground calcium carbonate 200g beech cellulose 150g titanium white 16 grams zinc stearate 12 grams

Polycondensation takes place within 8.5 minutes, the material is dried under a vacuum of 0.06 MPa and the resulting granulate is ready for further processing by injection molding or extrusion, with its curing enthalpy being 67.5 J/g, bending strength 97 MPa, impact toughness 0.765 J/om and viscosity 4.60.103 ^Pa.s at 120 °C and injection pressure 120 MPa.

2. The following reactants are introduced into an intensively stirred reactor at a temperature of 60 °C:

melamine 370 g formaldehyde technical 36% 500 g distillation waste of 6-caprolactam in extinction 20, mgeq/kg volatile bases 370 g NaOH 7 g triethanolamine 5 g wood flour 900 g

Polycondensation takes place within 30 min, the resulting material is dried under vacuum at 0.05 MPa, ground and is ready for processing. The resulting material is characterized by a curing reaction enthalpy of 149.5 J/g, a flexural strength of 112 MPa, an impact toughness of 0.836 J/cm and a viscosity of 3.92.10 ³ Pa.s at 120 °C and an injection pressure of 120 MPa.

3. The following components are introduced into a stirred reactor at a temperature of 100 °C:

technical formaldehyde 36% 400 g distillation waste of 6-caprolactam with an extinction of 10, mgeq/kg volatile bases 4 g cellulose aspen 200 g triethanolamine 15 g

After 10 min of polycondensation, additional reaction components are added:

melamine 370 g lithopone 250 g verzála zeflof 15 g

During the next 15 minutes, complete polycondensation takes place, the material is dried under vacuum.

0.07 Mpa and after grinding it is ready for further processing, characterized by an enthalpy of curing reaction of 59.1 J/g, a flexural strength of 87 MPa, an impact strength of 0.695 J/cm and a viscosity at an injection pressure of 120 MPa and a temperature of 120 °C of 6.3.10 ³ Pa.s.

4. The following polycondensation components are introduced into an intensively stirred reactor at a temperature of 150 °C:

melamine 370 g

50% solution of distillation waste of 6-caprolactam in formaldehyde in extinction 18, 24 mgeq/kg volatile bases 150 g technical formaldehyde 36% 330 g ground mica 650 g formic acid 7 g zinc stearate 25 g

After 15 min of polycondensation, the resulting granulate is dried under vacuum at 0.05 MPa and is ready for further processing. It is characterized by a curing reaction enthalpy of 74.2 J/g, a flexural strength of 88 MPa, an impact toughness of 0.813 J/cm ² and a viscosity at 120 °C and an injection pressure of 120 MPa of 5.2.10 ³ Pa.s.

SUBJECT OF THE INVENTION

Claims (1)

A process for preparing a modified 6-caprolactam-modified melamine mass prepared in the presence of catalysts, melamine, formaldehyde and fillers, or in the presence of catalysts, formaldehyde and cellulose, wherein the melamine and any other fillers are metered during polycondensation at 60-150 ° C, characterized in that 6-caprolactam distillation waste as defined by extinction 1 to 20 and a volatile base content of up to 25 mg / kg in an amount of 1 to 100% by weight by weight of melamine is used as modifier. Severography, n. P., MOST