The powdered polymer composition for the manufacture of abrasive tools

B24D3/30 - for close-grained structure


(57) Abstract:

The inventive powdered polymer composition for manufacturing an abrasive tool comprises, by weight.h.: phenol-formaldehyde Novolac oligomer 100, hexamethylenetetramine 6 - 12, epoxydodecane resin is the condensation product of epichlorohydrin and on-crazyforbargains resin 10 - 100. Based binder made grinding wheels, has a discontinuous speed 123,0 - 132 m/C, grinding coefficient of 2.0 - 2.4 cm2/cm2. 3 table.

The invention relates to composite materials based on phenol-formaldehyde polymers, in which the curing agent is used hexamethylenetetramine (GMHA), and in particular can be used for abrasive tools made both the cold and hot pressing.

A known mass of abrasive tools hot pressing, containing abrasive (54-62.), powdered organic binder (19-30 about. ), mineral filler (6-17 about.) and humidifier (about 2-10.), consisting of a solution of epoxy resin in the furfural concentration 25-75% [1]

A disadvantage of the known solutions is that it is used only for hot squeezes on manufacturability abrasive mass because there is an additional operation preparation of a solution of epoxy resin in the furfural. In addition, the liquid epoxy resin is very time consuming due to their high adhesive ability when in contact with different objects (working capacity, hands working etc).

The closest in technical essence and the achieved effect is a binder for the manufacture of abrasive tools containing Novolac phenol-formaldehyde oligomer and curing agent is hexamethylenetetramine, on 100 wt.h. oligomer add 6-10 wt.h. hexamethylenetetramine. The powder components are mixed in the abrasive mixer and then used as a powdered binder for the manufacture of abrasive tools. Curing of the binder occurs during the subsequent thermal treatment of the products at a temperature of 160-200aboutWith, resulting in a three-dimensional structure of bakelite, which determines the mechanical strength and the heat resistance of the ligament [2]

A disadvantage of the known powder binder (TFP) for the manufacture of abrasive tools is its low strength and heat resistance, when heated tool (circle) in the work the here to get free (0-5% ERP) polymer composition with a high content of binder (up to 40 vol.) cold pressing. Used powdered binder for cold pressing in the heat treatment process provides about 3% of volatile gases, which together with other volatile (e.g. from wetting grinding grain) does not allow to make the instrument more compact structure (pores less than 20 vol.), with increased binder content (up to about 40. ) because it results in heat "sciam", delamination, which dramatically reduces the strength and performance properties of the instrument.

The task of the invention is directed regulatory structure, hardness, strength and performance properties of the instrument, in particular, increased strength and heat resistance, according to his purpose, and reduced emission of volatile gases.

The problem is solved by creating a powder composition comprising a Novolac phenol-formaldehyde oligomer (phenol-formaldehyde resin TFE), and it has been the product of the condensation of epichlorohydrin with articlesinformation Novolac resin type (epoxydodecane mixture EDF) in the following ratio, wt.h. TFP 100 IT HAS BEEN 6-12 ENNS 10-100

All components of the polymer compositions are in a powdered state, therefore, the introduction of the ENS in the abrasive mass does not increase Legalna resin (TFE), It has been and epoxydodecane resin (EDF) are in stoichiometric ratios, providing the most complete passage of the curing reaction (intermolecular crosslinking). The formation of stable chemical bonds in the polymer composition increases strength, heat resistance, etc. outside of these ratios remain unreacted source components, the degree of "matching" smaller, so the mechanical properties and heat resistance is also reduced.

It should be noted that the amount of volatile gases in the recipe is reduced by 2-3 times compared to known due to the fact that during a chemical reaction curing phenol-formaldehyde resin hexamethylenetetramine (it has been) allocated water, ammonia, phenol, formaldehyde.

When participating in the curing reaction epoxydodecane resin is not released ammonia, water and other volatile as between the nitrogen atoms included in the structure it has been, and carbon chemical bond occurs, thereby inhibiting ammonia and formaldehyde, which are products of decomposition of hexamethylenetetramine. Since the curing resin composition is not by the mechanism of polycondensation, the allocation of water as is and with a high content of ligaments as cold and hot pressing, and stitched Enns phenol-formaldehyde resin with it has been to offer high durability, good adhesion, high temperature resistance. Specific example:

Prepare samples of the binder with the maximum, minimum and optimum content of the components (table.3), from which are made the tablet and the molding material for circles HH.

Tablets are made with a diameter of 15 mm, height 7 mm and bakaliaros at 160aboutC. half of the tablets again heated to 300aboutWith a shutter speed of 30 min.

The original samples and samples after heating to 300about(Thermal loading) crush on a bench with a force of 1,000 kg in Parallel manufactured and tested samples for impregnation (example 7, table.1).

The results of the tests are presented in table.2.

Cutting circles HH made of a binder according to examples 1-7 of table.1 according to the following formulation, by weight.h.

Grinding material brand IN 100 Liquid bakelit brand BJ-3 8,2 Binder powder 14 Cryolite 6

Making circles (mixing the molding material, extrusion, heat treatment) produced by the conventional technology.

Made circles have the strength and ekspluatatsionnye of the binder, according to the invention have high strength properties, heat resistance and performance circles.

The POWDERED POLYMER COMPOSITION FOR MANUFACTURING an ABRASIVE TOOL comprising phenol-formaldehyde Novolac oligomer and hexamethylenetetramine, characterized in that it further comprises epoxydodecane resin is the condensation product of epichlorhydrin and on-crazyforbargains resin in the following ratio, wt.h.:

Phenol-formaldehyde Novolac oligomer - 100

Hexamine - 6 - 12

Specified epoxydodecane resin 10 - 100


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