CS259682B1 - Conducting plastic mortars - Google Patents

Abstract

The solution relates to the field of construction and solves the technical problem of producing electrically conductive plastic mortars. According to the solution, the plastic mortars consist of 65 to 80 parts of epoxy resin, 20 to 35 parts of 2-ethylhexyl acrylate, 200 to 800 parts of sand, 1 to 6 parts of conductive resins and 8 to 20 parts of polyamine. The solution can be used in particular in the production of conductive parts of buildings.

Description

The present invention relates to conductive plastics based on epoxy acrylate resins.

In modern technology and technology, we often encounter serious problems related to the formation and dissipation of electrostatic charges, which arise in various ways, most often by rubbing masses of low specific conductivity. The charge values are considerably higher and sparks of up to several kV are generated during the discharge. Such discharges are not only physiologically unpleasant, but can cause ignition of vapors of flammable liquids, flammable dusts and the like. Modern electronic devices are very sensitive to the presence of electrostatic fields, which in extreme cases can seriously damage them. The second serious problem of technology and technology are stray currents of different nature and intensity, usually occurring in the vicinity of electric machines and apparatuses, in particular by induction of higher frequency electric fields. Stray currents can often cause malfunctions of sensitive devices such as computers, etc., or cause serious health threats to sensitive persons. Efforts are therefore being made to prevent the formation of electrostatic fields or harmless discharge of charges and stray currents into the ground. There are many known solutions, but none of them guarantees the desired effect in full. In recent years, a relatively good effect has been achieved by the application of conductive plagtbetons containing 40 to 70%. graphite. The binding conductive plastics were usually epoxy resins, especially modified with styrene, or dibutyl lineate or dibutyl phthalate. A serious drawback of this type of conductive plastic concrete is the high content of graphite, which causes both deterioration of the processing parameters of the mass when laying plastic concrete, and high hardness of graphite causes very significant deterioration of mechanical parameters, especially tensile strength, ductility, impact strength bending. The problem has not been solved either by the use of plastic concrete containing powdered conductive metals or by the application of ionogenic compounds such as quaternary ammonium or sulphonium salts, which gradually bloom or swell from the plastic concrete and wash away irreversibly when cleaning, so that the conductivity is constantly decreasing.

With extensive experimental work and tests, we have now found conductive plastics having very good mechanical parameters and full electrical resistance of 1 to 100 kdhm after fully curing. The conductive plastics according to the invention are characterized by a composition of up to 80 parts by weight of an epoxy resin with an average molecular weight of 435 to 670 and a mean epoxy functionality of 2.0 to 35 parts of 2-ethylhexyl acrylate

200 to 800 parts of sands of grain 0.1 to 5 mm 1 to 20 parts of conductive carbon black to 20 parts of polyethylene polyamines or polypropylene polyamines having an average molecular weight of 98 to 360 and an average equivalent weight of 20 to 45.

The conductive plastraalts of the invention are reactive and cure in the range of 15-25 ° C for 3-10 days and cure for about three weeks to achieve 90% strength of the polymer network. At temperatures below 15 ° C, it is advisable to use curing accelerators in an amount of 0.1 to 5), in particular salicylic acid, salicylates, femolic compounds, etc. The conductivity parameter bears usually carbon black having a high structure (high degree of chaining) and low oxygen content. The most suitable type is the business product of Chemical Plants 8 ČSP Chezacarb EC. However, other types of conductive carbon black, in particular acetylene carbon black, may be used, depending on the selected processing conditions and the target mechanical parameters of the cured conductive plastmalt. Curing agents are most often used in amounts of 100 to 120% of theory, in particular diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripropylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, or technical cuts or distillation fractions containing said polyamines.

Conductive graphite-based plastics have a sand fill capacity of not more than 1: 1.2 and a throughput resistance of 50 to 500 kohm.cm, a flexural tensile strength of 14-16 MPa, a fracture strength of 24-28 MPa and a water absorption of up to 2.2%. Tensile strengths of 15 MPa or less, ductility not exceeding 4%, and impact strengths of less than 8 kJ / m ^{2 are also low} .

In contrast, the plastics according to the invention achieve a conductivity characterized by a throughput resistance of 4 to 500 kohm.cm, with a sand filler of up to 1: 7. The flexural tensile strength varies between 16 and 33 MPa, the fracture strength between 28 and 71 MPa, water absorption between υ, Ι to 1,4% »tensile strength 20 to 38 MPa ·, elongation to 35% and impact strength up to 40 kJ / m. A significant advantage of the conductive plastmalt according to the invention is their good workability even at high sand filling and low toxicity.

Example 1 g of an epoxy resin having an average molecular weight of 668 and an average epoxy functionality of 2.0, an epoxy group content of 0.298 mol / 100 g, was melted at 120 ° C and mixed with 35 g of 2-ethylhexyl acrylate and 150 ppm hydroquinone. The homogeneous mixture containing 0.384 mol / 100g of reactive groups was cooled to 25 ° C and 200 g of 0.25-2 mm continuous granulometry quartz sand was added thereto, followed by 2 g of Chezacarb EC conductive carbon black. The mixture is homogenized and mixed with 18.5 g (110% of theory) of technical tetrapropylenepentamine (eq. 43.8) and allowed to cure. The fully cured conductive plm stall has the following parameters:

tensile strength elongation impact strength p r e r o o o o o o o o r water absorption

25.5 MPa 11.5%

25.2 kJ / m ² 61.1 kohm.cm 0.35%

Example 2 g of an epoxide resin having an average molecular weight of 571 and an average epoxy functionality of 2.0 is melted and mixed at 110 ° C in the presence of air with 30% ethylhexyl acrylate and 100 ppm hydroquinone.

The liquid homogeneous mixture has a viscosity of 842 mPa · s / 25 ° C and contains 0.408 mol / 100g of reactive groups. 100 g of the prepared mixture are mixed with 500 g of 0.25 to 2 mm continuous granulometry sand and varying amounts of Ohezacarb EC. It cures when 13.7 g of technical triethylenetetramine (equivalent weight 30.46) is added. Cured conductive plststalts have the following parameters:

Ohezacarb (G) EC parameters of plastics el.resistance (kohm.cm) flexural tensile strength (MPa) fracture strength (MPa) absorbability (%) 2 85.75 20.3 36.6 0.7 3 28.75 28.0 56.2 0.3 4 8,776 30.0 65.4 0.1 5 6,490 33.4 70.8 0.2

Example 3

80 g of epoxy resin with a mean molecular weight of 435 and a mean epoxy functionality of 2.0 is mixed at 105 ° C with ·

20 g of 2-ethylhexyl acrylate and 50 ppm of hydroquinone. The liquid mixture has a viscosity of 672 mPa · s / 25 ° 0 and contains 0.478 mol / 100g of reactive groups. 700 g of quartz sand of 0.5 to 4 mm grain size and 20 g of acetylene carbon black P 1250 and 10 g of diethyletriamine are mixed in this mixture. The mixture is allowed to cure after thorough mixing. The obtained conductive plastmalta has a flexural tensile strength of 21.4 MPa, a fracture strength of 41.6 MPa, a water absorption of 4.4% and an electrical throughput resistance of 1.3 kohm.cm.

Claims (1)

SUBJECT OF THE INVENTION Conductive plastics based on epoxy resins / characterized in that they consist of 65 to 80 parts of an epoxy resin with an average molecular weight of 435 to 670 and an average epoxy functionality of 2.0 20 to 35 parts of 2-ethylhexyl acrylate 200 to 800 parts sand grain 0.1 to 5 mm 1 to 20 parts conductive carbon black 8 to 20 parts of polyethylene polyamines or polypropylene polyamines with an average molecular weight of 98 to 360 and an average equivalent weight of 20 to 45 ·