RU2434745C2 - Method of producing granulated armor composition based on thermoplastic elastomer (tpe) - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of multi-component granulated armor compositions and may be used in armoring rocket solid propellants and civil structures coated by TPE-based polymer envelopes. Proposed method comprises dry mixing of armor composition components, plastification, homogenisation and extrusion in auger extruder. Note here that dry mixing is carried out for at least 15…20 minutes. Thereafter, 4-5%-solution of poly(vinyl butyral) in ethanol is added in 1…2 steps in amount of 15…20% of armor composition to mix it after every step for 5…7 minutes. Then armor composition is unloaded onto pans with layer thickness of not over 10 mm and dried at 15…35°C for 12…24 h. Then, armor composition is loaded into auger extruder to be plastified, homogenised and extruded, extruded armor cord being cut into granules.

EFFECT: higher homogeneity of armor composition.

1 dwg, 1 tbl, 1 ex

Description

The invention relates to a method for manufacturing a multicomponent granular armored personnel carrier and can be used in the reservation of solid rocket fuel (TRT) charges for rocket engines, as well as in the manufacture of civilian products coated with a protective polymer shell.

When booking TPT charges with multicomponent compositions, it is preferable to use them in granular form. This greatly simplifies the process of booking charges, improves the accuracy of dosing of granular armored personnel when booking charges, which generally increases the manufacturability of the booking process and the quality of armor plating of TRT charges.

Known formulations of armored compositions based on butadiene methylstyrene thermoplastic elastomers (TEP) and inden-coumarin resin (IKS): Pat. RU 2208007 using asbestos chrysotile and aluminum hydroxide as fillers and US Pat. RU 2366641 using micronized mica as a filler and polyvinyl butyral (PVB) as a heat stabilizer, as well as a method for the manufacture of granular armor based on these formulations - US Pat. RU 2305629, which was adopted by the authors as a prototype.

A significant disadvantage of the prototype is the difficulty of ensuring the homogeneity of the granules. The specified disadvantage is associated with a varying degree of dispersion of the dry mix components subjected to dry mixing and subsequent extrusion. Finely dispersed components: asbestos and aluminum hydroxide (according to US Pat. RU 2208007), micromica (according to US Pat. RU 2366641) after the dry mixture of components is introduced into the hopper of the extruder mainly accumulate in the lower part of the screw press and are unevenly introduced into the extruded armor cord.

An object of the invention is the development of a method for granulating a multicomponent polydisperse armored composition based on thermoplastic elastomer and inden-coumaron resin to ensure increased homogeneity of the obtained granules.

The technical result of the invention lies in the development of a method of granulating a multicomponent armor based on TEC, as well as ICS in combination with other finely dispersed components according to US Pat. RU 2366641, while carrying out preliminary dry mixing of the components of the armored composition in the mixer at a temperature of 15 ... 35 ° C for 15 ... 20 minutes, after which, in portions, in 1 ... 2 doses, a 4 ... 5% solution of PVB in ethanol is introduced into the mixer the amount of 15 ... 20% in relation to the weight of the armor and mix the armored mass after each reception for 5 ... 7 minutes. After that, the armored mass is unloaded onto baking sheets to ensure that the armored mass layer thickness is not more than 10 mm and the latter is dried at a temperature of 15 ... 35 ° C for 12 ... 24 hours. Upon completion of drying, the armored mass is loaded into the screw press, plasticization and homogenization of the composition and extrusion of the armor cord are made with its cutting into granules.

The invention is illustrated in graphic materials.

The drawing shows a flow diagram of the manufacture of granular armored personnel according to the patented method.

The essence of the invention is to provide a more uniform, compared with the prototype, input of all components of the armored composition into the extrudable cord of the latter, which can significantly increase the homogeneity of the granules. The indicated effect is achieved by introducing, upon dry mixing of the components of the armor composition, an alcohol solution of polyvinyl butyral for bonding small components with larger ones (finely dispersed components “stick” to the larger TEC fraction). This allows you to provide a more uniform in comparison with the prototype input of all components of the armored personnel into the extrudable cord and thus ensure the homogeneity of the granules of the armored personnel.

When using solutions of other components, for example, a solution of TEP in butyl acetate, clotting of the armored mass moistened by it and its adhesion both to the walls of the mixer and to the blades of the mixer occurs, which is due to the solubility in butyl acetate of both TEP and ICS. After unloading such crumpled armored mass from the mixer onto a baking sheet, it is necessary to grind it before drying and further processing into granules.

The use of an alcoholic PVB solution for bonding small fractions of an armored composition with a larger fraction eliminates clumping of the wetted mixture of components in the mixer, its adhesion to the mixer blades and the walls of the mixer, and there is no need to grind the mass discharged from the mixer before drying.

For bonding small fractions of an armored compound with a larger one, we used, as the most technologically advanced, a 4-5% solution of PVB in ethyl alcohol.

When using the “PVB-ethyl alcohol” solution with a concentration of less than 4%, satisfactory adhesion of small fractions of the armor composition to a larger one is not ensured, and with a concentration of more than 5%, the PVB solution becomes thick, which significantly impairs the wettability of the mixture of dry components.

The introduction of a solution of PVB in an amount of 15 ... 20% in ethanol provides satisfactory bonding of finely dispersed components with a large fraction of TEC:

- the lower limit (15%) determines the necessary level of adhesion during bonding;

- exceeding the upper limit (20%) requires additional time for drying the armored material.

The drying time within 12 ... 24 hours is due to:

- the lower limit (12 hours) ensures the removal of a sufficient amount of solvent;

- the upper limit (24 h) excludes overdrying of the armored mass.

Dry mixing of the components in the mixer is carried out within 15 ... 20 minutes, since 15 minutes is sufficient for the uniform distribution of small fractions of the armor composition between the larger TEC fraction; exceeding the mixing time of more than 20 minutes leads to excessive energy consumption.

An example implementation of the method.

We subject granulation to the armored composition of the following formulation (wt.%):

- TEP (butadiene-methylstyrene thermoplastic elastomer) grade DMST-R - 35.0 - indene-coumarone resin - 35.0 - micromica - 26.0 - polyvinyl butyral - 1.0 - stearic acid - 2.0 - calcium stearate - 1.0

The components are mixed in a mixer for 20 minutes, after which we introduce a 5% solution of PVB in ethyl alcohol in an amount of 18% in two parts in a mixture of components in relation to the weight of the armor. After entering the solution, we mix the components mixture for 5 minutes. After mixing, unload the mass on baking sheets and evenly distribute on the surface. The layer thickness is ~ 10 mm. The mass was dried at a temperature of 17 ° C for 18 hours. Then we load the mass into the screw press, where we plasticize and homogenize it, and then granulate it. In this case, we determine the melt flow rate according to GOST 11645-73 at T _melt = 175 ° C, the mass of the cargo is 3.8 kg, the diameter of the capillary is 1.18 mm.

The mixing and drying parameters of the armored mass as a whole are given in the table.

From the results shown in the table, it follows that the optimal parameters for processing the armored mass correspond to examples 8, 9, 10, where a positive effect was obtained, consisting in increasing the manufacturability of the granulation process of the armor composition, obtaining better armor plating of the TRT charge, due to the implementation of the optimal melt flow rate (MFR) armored vehicles.

Using the pellets of a thermoplastic armored composition made in accordance with this technical solution by extrusion method, ballistic-type TPT charges with the dimensions:

- outside diameter - 72.5 mm; - channel diameter - 33 mm; - length - 575 mm; - thickness of armor plating - 1.0 mm.

The quality of charges in appearance, geometric dimensions and the level of adhesion of the armor to TPT is satisfactory.

Table No. at
measure Continued
resident of-
nost
dry
shifting
shiva
niya
min The number of techniques for introducing a solution of PVB in
ethyl. alcohol The concentration of the solution of PVB in ethyl. alcohol,% The number of injected solution of PVB in ethyl. alcohol in a dry mixture,% Tempe
ratrata
drying
armored
masses,
° C Continued drying hours MF g / 10 min The appearance of the mass Features of the technological process one fifteen one 2 eighteen 19 twenty 1,5 Evenly moistened mass in the form of flakes A low concentration of PVB solution has led to poor bonding of components with DMST (P) 2 7 2 four fifteen 23 eighteen 1.8 Also The dry mixture is not sufficiently mixed; mass uniformity is not achieved 3 eighteen 2 four 12 25 10 1.7 Also Insufficient amount of injected PVB solution, poor bonding of components with DMST (P) four twenty 2 5 26 twenty 45 2.5 Also High amount of injected PVB solution, the duration of the drying of the mass, solvent overrun 5 19 one 5 19 22 fifty 2.1 Also The armored mass is overdried, difficult granulation 6 fifteen 2 four twenty 12 24 2.7 Also Drying temperature is low, the mass is under-dried, difficult metering into the hopper 7 twenty 2 8 17 eighteen 22 2.0 Also The PVB solution was too thick, it was difficult to introduce into the dry mixture 8 16 one four 16 twenty fifteen 4.2 Also Satisfactory processability and homogeneity of granules 9 twenty 2 5 eighteen 17 eighteen 5.5 Also Also 10 fifteen 2 4,5 twenty 25 twenty 5.2 Also Also

Claims (1)

A method of manufacturing a granular armored composition based on thermoplastic elastomer, including dry mixing of the components of the armored composition and subsequent plasticization, homogenization and extrusion of the armored mass in the screw press, characterized in that the dry mixing of the components is carried out for at least 15-20 minutes, after which the components are mixed in 1 -2 doses, a 4-5% solution of polyvinyl butyral in ethanol is introduced, in an amount of 15-20% relative to the weight of the armor, mix it after each dose for 5-7 minutes, after which I carry out unloading bronemassy on trays with a layer thickness of not more than 10 mm, and dried at a temperature of 15-35 ° C for 12-24 hours and then charged in screw-bronemassu press and produce plasticizing, homogenizing and extruding broneshnura by cutting it into pellets.

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