RU2800220C1 - Sound-absorbing material for truck sound-absorbing screens with reduced flammability - Google Patents

Abstract

FIELD: sound absorption and heat insulation.

SUBSTANCE: invention relates to the creating sound-absorbing and heat-insulating materials that are intended for sound absorption of a truck and its parts in the frequency range from 100 to 1600 Hz, for example, floors, sound-absorbing screens, where requirements for effective sound absorption, especially where these requirements are coupled with requirements for low flammability of the material. Sound-absorbing material, including polyol and isocyanate components of the urethane-forming mixture, thermally expanding graphite additionally comprises aluminosilicate microspheres and barium sulfate at a ratio of components, wt.h: polyol component 100, isocyanate component 50, thermally expanding graphite 1.5-10, aluminosilicate microspheres 0.5, barium sulfate 1.

EFFECT: reduced flammability.

1 cl, 3 tbl

Description

The invention relates to the field of creating sound-absorbing and heat-insulating materials that are intended for sound absorption of a truck and its parts in the frequency range from 100 to 1600 Hz, for example, floors, sound-absorbing screens, where requirements for effective sound absorption, especially where these requirements are associated with requirements for low combustibility of the material.

The sound-absorbing material of a truck consists of a sheet material based ^on polyurethane foam with a thickness of 12-25 mm and a density of 50 ± 10 kg / m osilicate microspheres, equal to 0.5-10.5 wt.h. reaction mixture. Thermally expandable graphite and aluminosilicate microspheres are initially added to the part of the polyol that contains the activator and water. The particle size of thermally expandable graphite can be from 0.2 to 100 microns. The particle size of aluminosilicate microspheres can be from 0 to 500 microns.

The floor parts are made integrally molded and repeat the surface and outlines of the relief of the body from the specified material. Behind the cab, above the engine, there is a sound-absorbing screen that reduces engine noise. Low-bed delivery truck chassis with engine and gearbox sound-absorbing screens located under the power unit and behind the cab.

The easiest way to reduce the flammability of polyurethane foams is the use of additives to increase fire resistance (flame retardants).

The most common types are halogenated compounds, phosphorus-containing metal hydrates and salts, as well as nitrogen-containing flame retardants and their combinations with phosphorus compounds. Halogenated flame retardants are generally very effective and require relatively small amounts to be added to the final product to obtain outstanding flame retardant properties, but they have been listed as highly hazardous pollutants and their use has been limited.

Expandable graphite and ammonium polyphosphate are known to be flame retardant modifiers for polyurethane foams.

Materials based on intumescent graphite are quite common, the properties of these materials are described in detail in the publication [Kang Shen. Recent advances with expandable graphite in intumescent flame retardant technology / Bernd Schilling // Nyacol Nano Technologies, Inc.]. Physico-chemical foundations of the process of thermal expansion of thermally expanding graphite are considered in detail in the review of Heifets L.I. [Kheifets L.I. Mathematical modeling of the process of thermal expansion of intercalated graphite / Zelenko VL// Methodical guide. IGU them. M.V. Lomonosov. - 2008].

The ability of thermally expanding graphite to thermal expansion is due to the presence in it of well-ordered packets of graphene planes (in sufficient quantities) connected by weak intermolecular (van der Waals) bonds. An increase in the volume of solid particles (significant, up to hundreds of times) is induced by thermally expanding graphite upon heating as a result of an increase in gas pressure inside the graphite matrix, which occurs due to the evaporation of the intercalate or the release of gaseous products of a chemical reaction involving the intercalate and its derivatives. The increase in volume occurs mainly by changing the height of the graphite particle, i.e. along the crystallographic axis, while the particle diameter remains practically unchanged. The result of thermal expansion is a hierarchical pore structure in the final product, which has a pronounced "worm-like" shape. That is, there is a change in the packing density in the initially existing structural elements. In the process of decomposition/evaporation of the intercalate, high pressures develop (according to some estimates, up to 15 atm), but then the gases escape into the surrounding space. Thermally expanded graphite crystallographically remains ordinary graphite.

The disadvantage of the thermally expanded structure formed from thermally expanding graphite is its low strength characteristics. Such a structure is not able to withstand the impact of thermal gas flows generated during any fire for a long time. Thermally expandable graphite is used in conjunction with other additives. It can be used to enhance the effects of intumescent compositions. Usually, vermiculite, foam concrete, aluminosilicates, pumice, lava, etc. are used as such fillers. The listed fillers have a number of additional effects that improve swelling processes. An example would be vermiculite, which has a higher “trigger” temperature than graphite, which gives energy dissipation at high temperatures.

As aluminosilicate microspheres, it is preferable to use glass-crystalline aluminosilicate beads, which are formed during high-temperature combustion of coal. For example, the particle size of aluminosilicate microspheres can be from 0 to 500 microns. The chemical composition of aluminosilicate microspheres can be silicon oxide 58-70%, aluminum oxide 15-38%, iron oxide 1-7%, calcium oxide 1-4%, magnesium oxide 0.5-2%, the total content of potassium and sodium oxides 1.5%. Aluminosilicate microspheres reduce shrinkage and viscosity of compositions.

The object of the present invention is to improve the fire resistance of sound-absorbing materials used for sound-absorbing screens of trucks.

Known RF patent 2714917 which shows the composition for fire-resistant polyurethane foam used as a heat-insulating material for insulation of residential buildings and structures, as well as for the manufacture of decorative elements of interior decoration of buildings. The specified composition contains 11.0-13.5 wt.% polyesterpolyol, 31.0-36.2 wt.% polyisocyanate, 0.9-1.3 wt.% amine activator - triethanolamine, 12.5-15.0 wt.% expanded graphite, water, 10.0-15.0 wt.% melamine phosphate, 12.0-15.0 wt.% modifying additive - zinc carbonate hydroxide and/or zinc borate and/or zinc oxide, 8.6-10.5 wt. % distilled tall oil, 2.0-2.7 wt. , with increased strength and low water absorption values.

RF patent 2560146 is known, which shows a composition suitable for producing polyurethane, containing one mixture for forming polyurethane, one phosphate component selected from the group consisting of ammonium polyphosphate (APP) and melamine phosphates and their mixtures and mixtures thereof, and one type of particles of metal oxide or metalloid with a maximum particle size of less than 300 microns.

RF patent 2556212 is known, which shows a composition suitable for a composition for producing fire-resistant polyurethane foam containing a mixture of polyols, polyisocyanate and fire-retardant additives, characterized in that a mixture of ammonium polyphosphates and ammonium sulfamate is used as additives in an amount of from 10 to 40 wt.% of the total number of components, while the ratio of ammonium polyphosphate to ammonium sulfamate in the mixture is, respectively, from 1: 2 to 7:1 wt.h.

RF patent 2232148 is known, which shows a sound-absorbing material, including hollow microspheres and a phosphate binder, characterized in that it additionally contains a micropowder based on ele ash microspheres are used as hollow microspheres at the ratio of components, wt %: ash microspheres 20-35; phosphate binder 32.5-40; micropowder based on electrocorynde 32.5-40.

RF patent 2268899, selected as a prototype, provides information on fire-resistant polyurethane foam based on a composition including polyester polyol, polyisocyanate, expanded graphite, amine activator, stabilizer and blowing agent, characterized in that the composition additionally contains melamine cyanurate and a modifying additive - polyhydric alcohols, as a blowing agent the composition contains water or freon, polyester polyol before interaction with polyisocyanate pre-mixed with an amine activator, a stabilizer, a modifying additive and a foaming agent, and then expanded graphite and melamine cyanurate are added at a ratio of 1-2:1 and a total amount of 15-30 wt.% of the total number of components.

A disadvantage of existing sound-absorbing materials for sound-absorbing screens of a truck with reduced flammability is the use of only one component to reduce flammability. To increase the synergistic effect to reduce flammability, it is necessary to use a combination of components that reduce flammability.

In the framework of this invention, the problem of reducing the combustibility of sound-absorbing materials based on polyurethane foam is solved.

The essence of the proposed technical solution lies in the fact that to obtain sound-absorbing materials of reduced flammability based on porous polyurethane foam, porous polyurethane foam (PPU) is used with a thickness of 5 to 20 mm and a density of 50±10 kg/ ^m the required value of the density of polyurethane foam at the installation of a "high-pressure machine with plunger pumps" by KraussMaffei Germany.

The polyol used is the polyester component Spesflex NS 759, the isocyanate isocyanate component Spesflex NE 138 in a mass ratio of 2:1.

Increased sound damping is achieved with the use of fillers, as finely divided inorganic fillers are often added to foam. Barium sulfate and calcium carbonate of various quality are used as fillers. Since these fillers are heavy, they settle out of the polyol mixture without constant stirring. Some fillers have a significant effect on foam formation reactions and inevitably lead to an imbalance in gas and gel formation reactions. Therefore, it is preferable to use barium sulfate in an amount equal to 0-1 wt.h. reaction mixture.

Reducing the combustibility of the sound-absorbing material is achieved through the use of thermally expanding graphite, aluminosilicate microspheres with a total amount of graphite and aluminosilicate microspheres equal to 0.5-10.5 mass.h. reaction mixture. Thermally expandable graphite and aluminosilicate microspheres are initially added to a portion of the polyol, and the amine activator, stabilizer and water are introduced into the second portion of the polyol. The particle size of thermally expandable graphite can be from 0.2 to 100 mm.

As aluminosilicate microspheres, it is preferable to use glass-crystalline aluminosilicate beads, which are formed during high-temperature combustion of coal. For example, the particle size of aluminosilicate microspheres can be from 0 to 500 microns. The chemical composition of aluminosilicate microspheres can be silicon oxide - 58-70%, aluminum oxide 15-38%, iron oxide 1-7, calcium oxide - 1-4%, magnesium oxide 0.5-2%, the total content of potassium and sodium oxides 1.5%.

Aluminosilicate microspheres reduce shrinkage and viscosity of compositions.

The foamed polymer material may have a face layer which is bonded to the polyurethane foam layer. As the front layer, you can use a metallized polyethylene terephthalate (PET) film with a thickness of 12 to 20 microns on a thermoplastic polymer base with a thickness of 30 microns. The thermoplastic polymer base is a layer of polyethylene, which melts during lamination and connects the polyethylene foam and the metallized polyethylene terephthalate film.

The essence of this invention lies in the fact that according to the first version, the polyol component "A" brand Spesflex NS 759 and the isocyanate component "B" brand Spesflex NE 138 were used as the main components of the urethane-forming mixture in a ratio of 100 wt.h. polyol 50 wt.h. isocyanate. Polyol component "A" was introduced into the isocyanate component "B" and mixed before the start of the interaction reaction; the resulting composition was poured into a preheated tooling, the shaping elements were closed and held for 6 minutes.

Option 2. Polyurethane foam, made according to the method described in option 1, obtained by adding 0.5 wt.h. thermoexpanding graphite brand METOPAC EG 350-50 (80), produced by GK Chemical Systems, 0.5 wt.h. aluminosilicate microspheres and 1 wt.h. barium sulfate. Mixing of the components was carried out manually in the following sequence: thermoexpandable graphite, aluminosilicate microspheres and barium sulfate were added to the polyol component "A" and thoroughly mixed for 5 minutes; the isocyanate component "B" was introduced into the resulting mixture and mixed until the interaction reaction began.

Option 3. Polyurethane foam, made according to the method described in option 2, obtained by adding 1.5 wt.h. thermoexpanding graphite brand METOPAC EG 350-50 (80), produced by GK Chemical Systems, 0.5 wt.h. aluminosilicate microspheres and 1 wt.h. barium sulfate.

Option 4. Polyurethane foam, made according to the method described in option 2, obtained by adding 3.5 wt.h. thermoexpanding graphite brand METOPAC EG 350-50 (80), produced by GK Chemical Systems, 0.5 wt.h. aluminosilicate microspheres and 1 wt.h. barium sulfate.

Option 5. Polyurethane foam, made according to the method described in option 1, obtained by adding 7 wt.h. thermoexpanding graphite brand METOPAC EG 350-50 (80), produced by GK Chemical Systems, 0.5 wt.h. aluminosilicate microspheres and 1 wt.h. barium sulfate.

Option 6. Polyurethane foam, made according to the method described in option 1, obtained by adding 10 wt.h. thermoexpanding graphite brand METOPAC EG 350-50 (80), produced by GK Chemical Systems, 0.5 wt.h. aluminosilicate microspheres and 1 wt.h. barium sulfate.

Physical and mechanical properties of materials obtained according to options 1 - 6 are shown in tables 1-3.

Table 1 presents the results of a study of the effect of intumescent graphite on the normal sound absorption coefficient.

Table 1

Normal sound absorption coefficient of polyurethane foam from 100 to 6300 Hz*

Frequency Compound 1 2 3 4 5 6 100 0.003 0.001 0.002 0.009 0.008 0.058 200 0.000 0.000 0.000 0.004 0.000 0.064 250 0.008 0.004 0.007 0.012 0.009 0.075 315 0.014 0.007 0.014 0.016 0.012 0.099 400 0.021 0.015 0.025 0.023 0.020 0.135 500 0.026 0.020 0.028 0.027 0.024 0.187 630 0.031 0.024 0.029 0.034 0.028 0.257 800 0.032 0.032 0.025 0.035 0.028 0.219 1000 0.051 0.038 0.041 0.046 0.039 0.355 1250 0.075 0.048 0.054 0.054 0.045 0.373 1600 0.109 0.065 0.082 0.068 0.052 0.410 2000 0.140 0.140 0.111 0.095 0.057 0.591 2500 0.168 0.108 0.084 0.127 0.064 0.733 3150 0.059 0.057 0.041 0.055 0.048 0.834 4000 0.068 0.066 0.046 0.062 0.055 0.643 5000 0.083 0.085 0.058 0.076 0.068 0.482 6300 0.111 0.121 0.082 0.106 0.095 0.397

* - the values of the arithmetic mean tests of three samples are presented

table 2

Thermal conductivity coefficient of polyurethane foam

Parameter Compound 1 2 3 4 5 6 (W/(m*K)) 0.061 0.062 0.066 0.055 0.058 0.056

Table 3

Data obtained from TGA examination of samples in air

Compound T _5% (°C) _Tmax (°C) Weight loss rate at T _max (mass%/min) 1 222 302 10.7 2 223 302 10.2 3 238 306 8.5 4 190 294 7.9 5 202 299 7.5 6 218 300 7.3

Thermal studies in air showed that the introduction of 0.5 wt.h. intumescent graphite did not change the basic decomposition characteristics of polyurethane foam. Introduction 1.5 wt.h. intumescent graphite in the composition of polyurethane foam leads to an increase in thermal stability in an oxidizing environment, such indicators as T _5% and T _max increase. So, T _5% increases by 16°C and is 238°C, and T _max =306°C, while the rate of weight loss decreases to 8.5 wt%/min. With an increase in the content of intumescent graphite from 3.5 wt.h. up to 10 wt.h. markedly reduced indicators such as T _5% by about 23-48°C and T _max by about 5-12°C. The lower values of T _5% and T _max were attributed to the influence of residual acid inside the layers of thermally expandable graphite, which leads to accelerated decomposition of the polyurethane foam.

Thus, in the composition of polyurethane foam containing intumescent graphite up to 10 wt.h. denser foam particles are formed, reducing the rate of mass loss, and accordingly, thermal stability is improved and flammability is reduced.

The highest physical and mechanical characteristics are possessed by compositions according to options 3-6 of polyurethane foam, which, in comparison with the original polyurethane foam, allow: to increase an average of 1.5-3 times the normal sound absorption coefficient in the frequency range from 100 to 1600 Hz; reduce the thermal conductivity coefficient by 6-8%; reduce the rate of weight loss at the maximum decomposition temperature to 7.3 wt.%/min.

The materials described above can be used to manufacture sound-absorbing parts of a truck, in particular a sound-absorbing screen, and mount them in places with an increased fire hazard.

Claims (6)

Sound-absorbing material, including polyol and isocyanate components of the urethane-forming mixture, thermally expanding graphite, characterized in that it additionally contains aluminosilicate microspheres and barium sulfate at a ratio of components, wt.h: Polyol component - 100, Isocyanate components - 50, Thermally expanding graphite - 1.5-10, Aluminosilicate microspheres - 0.5, Barium sulfate - 1.