SU478666A1 - Sand-resin to the mixture for the manufacture of foundry cores and molds - Google Patents

Description

one

The invention relates to the field of sanding mixtures used in foundry production for the manufacture of cores and molds.

Limes are resin-based mixtures in which alkyd resins modified with oils are used as binders.

Oil modification usually increases the cost of the binder. In addition, the physicomechanical properties of rods from these mixtures are not high enough, and gas-permeability, on the contrary, is high.

The purpose of the invention is to increase the physical and mechanical properties and reduce the gas-making ability of the rods.

To do this, an alkyd resin modified with hydroxy acids was introduced into the proposed sand-resin mixture as a binder, and hexamethoxymethylmelamine was introduced as a curing accelerator in the following ratio of components, weight. w .: Quartz sand100

Hexamethoxymethylmelamine 0, 15-0,40 Alkyd resin, modified with hydroxy acids 1,5-4,0.

As hydroxyacids, lactic acid and tartaric acid in the amount of 30% by weight of the resin are introduced into the alkyd resin.

The water soluble lcpdp resin is a co-condensation product of pentaerythritol, glycerol and maleic acid.

Sand-resin mixture was prepared as follows.

100 weight. including quartz sand is thoroughly mixed for 2-5 minutes from 0.15 to 0.4 weight. including hexamethoxymethylmelamine (GM-3), then with stirring, the introduction of g 1.5-4 weight. hours (preferably 2 wt. hours) alkyd resin, pre-modified hydroxy acid, and then the mixture is stirred for another 2-5 minutes.

The rods obtained from the proposed mixture are cured at a temperature of 145-150 ° C for 20-30 minutes, after which they can be used to make castings.

Sterls are distinguished by high strength and low gas-making ability.

Example 1. Prepare a mixture of the following composition, wt. including:

Sand K02A100

Binder - alkyd resin, modified with lactic acid2

Hexamethoxymethylmelamine

(GM-3) 0.2.

The sand is mixed with hexamethoxymethylmelamine (GM-3) for 2 minutes, then, with stirring, the bond is added, and the mixture is further stirred for another 2 minutes. Thereafter, the tensile test specimens ("eights") are made from the mixture and cured in a temperature of 150 ° C for 30, 45 and 60 minutes.

The mixture has the following properties: Vitality, hour24

Tensile strength, kg / cm, at the time of heat treatment, min

3026.6

4525.4

6022, i6

Gas ability at 1100 ° С, through, s

154.8-5.5

305.2-6.0

455.4-6.2

605.7-6.4.

Example 2. Prepare a mixture of the following composition, wt. including:

Sand K02A100

Binder - alkyd resin, modified with viscous acid2 Hexamethoxymethylmelamine

(GM-3) 0.2.

The mixture is prepared as in Example 1. Samples for tensile testing ("eight") are made from the finished mixture and opened at 150 ° C for 20, 30, 45 and 60 minutes.

Mons has the following properties: Vitality, chas24

Tensile strength.

kg / cm, at the time of heat treatment, min. 20 30 45 60

28.9 26.2 24.9 24.3

Gas ability of IEE, cm / g, through.

with a sec

15 30 45 60

3.9-5.0 4.6-5.2 4.4-5.2 4.4-5.2.

Subject invention

Sand-resin to a mixture for making casting cores and heat-curable molds, including a refractory filler, a synthetic alkyd resin binder, and a curing accelerator,

characterized in that, in order to improve the physicomechanical properties and reduce the gas-making ability of the rods, an alkyd resin modified with hydroxy acids was added as a binder, and hexamethoxymethylmelamine was introduced as a curing accelerator at the following ratio of components, weight. including:

Quartz sand100

Hexamethoxymethylmelamine 0.15-0.40

Alkyd resin modified with hydroxy acids 1.5-4.0.