RU2060308C1 - Nonwoven filtering material - Google Patents

Abstract

FIELD: nonwoven filtering materials. SUBSTANCE: nonwoven filtering material is made in form of fibrous lap from a blend of staple synthetic fibers and includes low-shrink polyvinylchloride fibers with linear density of 1.0-2.0 tex and other fibers with linear density of 0.4-0.8 tex in ratio of 1: 1. The relation thickness of lap amounts to 530 <H=db <700. The value of specific filtering surface of the material is 27.5 <F <35, where H is thickness of the filtering material and db is average fiber diameter. EFFECT: higher efficiency. 1 tbl

Description

 The invention relates to the production of nonwoven materials and is used in the manufacture of filter material for air filters.

 Known filter material "Cloth non-woven glued volumetric filter" (TU 17-1183-74), which is a fibrous canvas of staple synthetic fibers glued with a binder.

The disadvantages of this filter material are relatively low cleaning efficiency (80%), a large mass of material (460 g / m ² ) and its thickness (30 mm), which makes it impractical to use this material in cell filters, since it has a large initial aerodynamic drag. In addition, the known filter material has a significant drawback, it is combustible.

 Known filter material "Cloth non-woven glued volumetric filter brand FRNK-PG" (TU 17-14-180-82), which is a canvas of a mixture of staple synthetic fibers glued with a binder.

The disadvantage of this filter material is the relatively low cleaning efficiency (87%), large masses (460 g / m ² ) and thickness (30 mm). Moreover, due to the relatively low cleaning efficiency and the large thickness of this material, it is not used in cell filters, where it is in a flat state (perpendicular to the direction of air flow) and, therefore, also has a high initial aerodynamic resistance.

 Also known non-woven filter material (ed. St. USSR N 1673663, CL D 04 H 1/58) containing fibrous canvas from a mixture of staple synthetic fibers glued with a binder.

 The disadvantages of this non-woven filter material adopted for the prototype are the relatively low cleaning efficiency (89%) and a large mass (304.363 g / m).

 The aim of the invention is to eliminate these drawbacks, that is, increasing the cleaning efficiency, reducing the mass of the material while expanding its scope without changing performance.

This goal is carried out in a non-woven filter material containing a fibrous canvas of a mixture of staple synthetic fibers, including low-shrink polyvinyl chloride fibers and other fibers in an equal percentage glued with a binder, while the following features are new in the material: low-shrink polyvinyl chloride fibers in the canvas have a linear density 1.0.2.0 tex and other fibers with a linear density of 0.4.0.8 tex, while the relative thickness of the fibrous canvas is
530 <N / d _at <700, and the value of the specific filtering surface of the material
27.5 <F <35, where H is the thickness of the filter material;
d _{to the} average fiber diameter.

 These new features provide a positive effect, namely increasing the cleaning efficiency, reducing the mass of the material while expanding its scope without changing operational indicators.

 No technical solutions are known that are similar to the features that distinguish the claimed invention from the prototype. Thus, the proposed technical solution meets the criteria of "Novelty" and "Significant differences".

^{* F} (1)
Δ P_н 1 / 2 π * ρ * V $\genfrac{}{}{0ex}{}{\text{2}}{\text{cp}}$ * F * C_д (2)
F 4 * α * H / d_в удельная фильтрующая поверхность материала из гладких синтетических волокон круглого сечения, где η эффективность очистки;
Е степень выноса пыли;
η _Σ ^I коэффициент захвата частиц пыли единицей длины волокна в материале под влиянием всех механизмов осаждения;
F удельная фильтрующая поверхность материала (поверхность волокон, приходящихся на единицу площади материала) из смеси синтетических волокон;
ΔP_н начальное аэродинамическое сопротивление фильтровального материала;
ρ плотность газа (воздуха);
V_ср средняя скорость фильтрации воздуха через материал;
С_д коэффициент лобового сопротивления волокна фильтровального материала;
α плотность упаковки волокон фильтровального материала;
Н толщина фильтровального материала;
d_в средний диаметр волокон.The effect of the filtering surface of a material from a mixture of low-shrink polyvinyl chloride and other synthetic fibers on its cleaning efficiency and initial aerodynamic drag is seen from the following expressions:
η 1 E 1 e ^{- 1 / π * η} Σ

^{* F} (1)
Δ P _n 1/2 π * ρ * V $\genfrac{}{}{0ex}{}{\text{2}}{\text{cp}}$ * F * C _d (2)
F 4 * α * H / d _{in the} specific filtering surface of the material from smooth synthetic fibers of circular cross section, where η is the cleaning efficiency;
E degree of removal of dust;
η _Σ ^{I the} coefficient of capture of dust particles by the unit length of the fiber in the material under the influence of all the mechanisms of deposition;
F the specific filtering surface of the material (the surface of the fibers per unit area of the material) from a mixture of synthetic fibers;
ΔP _n initial aerodynamic drag of the filter material;
ρ density of gas (air);
V _{cf the} average rate of air filtration through the material;
C _d drag coefficient of the fiber filter material;
α packing density of the fibers of the filter material;
H is the thickness of the filter material;
d _{to the} average fiber diameter.

 (Khlebnikov Yu.P. The method of calculating the resistance, efficiency and dust absorption of fiber filters. Air conditioning. Collection of scientific papers. VNIIkonditsioner. Kharkov, 1977. Issue 6, pp. 64-74.

 Khlebnikov Yu.P. Kachusov G.G. Determination of aerodynamic drag of fibrous filter materials.

 Air conditioning: Sat. scientific tr VNIIconditioner. Kharkiv. 1981. Issue. 10, p. 72-76).

As can be seen from expression (1), the cleaning parameter is significantly affected by the parameter F. The specific filtering surface of the fibers F in turn also depends on the average fiber diameter d _c . With decreasing fiber diameter d increases _in specific surface fibers of the filter, thereby increasing the cleaning efficiency and value of the dust loading it decreases as the exponent of "e" with a negative sign.

From the expression (2) it is seen that the initial aerodynamic drag of the filter material is directly proportional to its specific filter surface F and drag coefficient of fibers C _d .

 In the finished material, its specific filtering surface is determined by calculation as follows.

The length, width and thickness H of a sample of filter material are measured. The mass of the sample is determined. The sample volume and bulk density Q are calculated. In addition, for materials consisting of a mixture of synthetic fibers, for each type of fiber Q _i , the packing density α _i and the specific surface of the fibers F are determined by one of the following formulas:
smooth synthetic round fiber
F _ki 4 * α _i * H / d _i (3) low-shrink polyvinyl chloride fiber with pores on its outer surface
F _PVC K $\genfrac{}{}{0ex}{}{\text{i}}{\text{1}}$ * α _i * H (4) where F _кi , F _{pvc is the} specific surface of each type of fiber of circular and porous section in the material;
K $\genfrac{}{}{0ex}{}{\text{i}}{\text{1}}$ a constant characterizing the cross-sectional area and perimeter of each type of fiber, equal to P _bi / S _bi for low-shrink polyvinyl chloride;
P _{vi the} perimeter of the cross section of the fiber of each type;
S _vi the cross-sectional area of the fiber of each type;
α _i the packing density of each type of fiber in the material;
d _{i the} diameter of each type of fiber in the material.

The total specific surface of the fibers in the material (specific filtering surface of the material), regardless of the cross-section of the fiber, is calculated by the formula;
F = F1 + F2 +. + F _i (5)
The average diameter of the fibers in the material is determined by the equation
d _in = (d1 * F1 + d2 * F2 +. + d _i * F _i / F (6)
The proposed non-woven filter material is a homogeneous (without layers) fibrous canvas made of a mixture of staple (defined length) low-shrink polyvinyl chloride fibers with a linear density of 1.0.2.0 tex and other synthetic fibers with a linear density of 0.4. 0.8 tex in equal percentage glued with a binder.

 Pores are made in the shrink polyvinyl chloride fibers and on their surface. In these fibers in the process of their production, pores are formed that have two types of arrangement with respect to the cross section of the fiber, some pores are close to the longitudinal arrangement, others are radial, that is, they have channels for the exit of air bubbles from the inside of the fiber to the outer surface. In the latter case, the surface of the fibers becomes coarser (rougher), and therefore, the filtering surface of the material with the content of such fibers increases and thereby the cleaning efficiency is increased.

 The main operational indicators of the nonwoven filter material include the incombustibility of the material, its regenerability and the minimum initial aerodynamic resistance, that is, not more than 80 Pa according to the “Guide materials for central air conditioners and air conditioners-heat exchangers KTZ3. Trud PO Soyuzkonditsioner” (part 1), 1987 , 234 pp. ".

 The proposed filter material is difficult to combust due to the use of 50% low-shrink polyvinyl chloride fibers in the material, which are non-combustible.

 Uniform sizing of the fibrous canvas with a binder over its entire thickness contributes to the creation of a filter material with greater strength, as well as maintaining its shape (structure and thickness), which makes it possible to subject the proposed filter material to multiple wet regeneration (up to six times).

 In the process of filtering, dusty air passes through a non-woven filter material, while dust particles settle on the surface of smooth synthetic and rough, low-shrink polyvinyl chloride fibers.

PRI me R 1. Take 25% of low-shrink polyvinyl chloride (PVC) fibers with a linear density of 2.0 tex and a cutting length of 65.70 mm, 25% of low-shrink PVC fibers with a linear density of 1.0 tex and a cutting length of 65.70 mm, 25% polyester fibers with a linear density of 0.6 tex and a cutting length of 65.70 mm, 25% of nitron fibers with a linear density of 0.7 tex and a cutting length of 65.70 mm and prepare a mixture of them, which is fed to the combing unit and then to the canvas forming device. The formed fibrous canvas of the desired thickness is subsequently uniformly glued over its entire thickness with a binder in the form of an aqueous dispersion of a copolymer of vinyl chloride and vinyl acetate by spraying. The uniformity of the sizing of the canvas over its entire thickness is ensured by the continuous suction through the canvas of air containing an aerosol of atomized binder. The content of the binder in the finished material is 30% of its mass. Moreover, the surface density of the material (mass of 1 m ² material) is 300 g / m ² and its thickness is 19 mm.

PRI me R 2. The fibrous canvas of the material is formed from 50% low-shrink polyvinyl chloride fibers with a linear density of 1.0 tex and a cutting length of 65. 70 mm, 50% polyester fibers with a linear density of 0.6 tex and a cutting length of 65.70 mm. The filter material is obtained as in example 1. The material has a surface density of 260 g / m ² and a thickness of 16 mm.

PRI me R 3. The fibrous canvas of the material is formed from 50% low-shrink polyvinyl chloride fibers with a linear density of 1.0 tex and a cutting length of 65. 70 mm, 50% polyester fibers with a linear density of 0.8 tex and a cutting length of 65.70 mm. The filter material is obtained as in example 1. The content of the binder is 30% by weight of the material. Furthermore, the surface density of the material is 280 g / m ² and the thickness is 19 mm.

PRI me R 4. The canvas of the material is formed from 50% low-shrink polyvinyl chloride fibers with a linear density of 2.0 tex and a cutting length of 65.70 mm, 50% polyester fibers with a linear density of 0.4 tex and a cutting length of 65.70 mm. The filter material is obtained as in Example 1. The surface density of the material is 295 g / m ² and the thickness is 18.5 mm.

PRI me R 5. The fibrous canvas of the material is formed from 50% low-shrink polyvinyl chloride fibers with a linear density of 1.56 tex and a cutting length of 65.70 mm, 50% polyester fibers with a linear density of 0.7 tex and a cutting length of 65.70 mm. The canvas is glued with a binder as in example 1, and get a filter material with a surface density of 270 g / m ² and a thickness of 19 mm

PRI me R 6. The fibrous canvas of the material is formed from 50% low-shrink polyvinyl chloride fibers with a linear density of 2.5 tex and a cutting length of 65. 70 mm, 50% polyester fibers with a linear density of 1.2 tex and a cutting length of 65.70 mm. The canvas is glued with a binder as in example 1, and get a filter material with a surface density of 320 g / m ² and a thickness of 25 mm

PRI me R 7. The fibrous canvas of the material is formed from 75% low-shrink polyvinyl chloride fibers with a linear density of 0.8 tex and a cutting length of 65. 70 mm, 25% of polyester fibers with a linear density of 0.4 tex and a cutting length of 65.70 mm. The canvas is glued with a binder, as in example 1, and get a filter material with a surface density of 280 g / m ² and a thickness of 20 mm

PRI me R 8. The fibrous canvas of the material is formed from 60% low-shrink polyvinyl chloride fibers with a linear density of 1.0 tex and a cutting length of 65.70 mm, 40% nitron fibers with a linear density of 0.4 tex and a cutting length of 65.70 mm. The canvas is glued with a binder as in Example 1, and a filter material with a surface density of 290 g / m ² and a thickness of 21 mm is obtained.

 The use in a fibrous canvas of a mixture of staple low-shrink polyvinyl chloride fibers with a linear density of 1.0.2.0 tex and other synthetic fibers with a linear density of 0.4.0.8 tex in an equal percentage ratio leads to a lower consumption of raw materials for the manufacture of the proposed filter material, which allows you to create a material compared with a prototype with reduced material consumption, but with increased cleaning efficiency while expanding its scope (using the proposed filter about the material in both roll and cell filters) without changing performance indicators (initial aerodynamic drag; incombustibility; regenerability).

Despite the use in the proposed non-woven filter material of a fibrous canvas made of a mixture of synthetic fibers with a smaller average fiber diameter compared to the prototype, the value of the initial aerodynamic drag remains the same. This is ensured by reducing the weight of 1 m ^{2 of the} proposed material.

 The proposed material is a filter medium in filters for purifying air from atmospheric dust (air filtration), in particular, used in air conditioning systems and ventilation. In addition, a higher cleaning efficiency (92%) and a relatively small thickness (16.19 mm) allow it to be used in cell filters of air conditioning and ventilation systems.

 The indicated limits of the content of synthetic fibers when creating a filter material with reduced material consumption are optimal and allow you to get a positive effect on the cleaning efficiency while expanding its scope without changing operational indicators. In the manufacture of material with other ratios of incoming synthetic fibers, the cleaning efficiency and operational performance deteriorate, narrowing the scope.

In order to select the optimal ratio of the structural parameters of the material N / d _in , F and the percentage of synthetic fibers, comparative tests of the proposed non-woven filter material were carried out.

 The composition and test results of the proposed and known filter materials are shown in the table.

Tests of the proposed non-woven filter material and known were conducted with a specific air load on the material 3900 m ³ / (h * m ² ). Dust tests were carried out on dust with a specific surface area of 11,000 cm ² / g to a final aerodynamic resistance of 294 Pa, which corresponds to the operating conditions of air filters in KTZ3 air conditioners manufactured by Kharkov Air Conditioner Plant (Guidance materials on central air conditioners and air conditioners-heat exchangers KTZ3. Tr. Production Association Soyuzkonditsioner (part 1), 1987, 234 pp.).

Test results show the following:
known filter material has a relatively low cleaning efficiency, a large mass;
the best technical indicators are for the proposed non-woven filter material containing fibrous canvas from a mixture of staple, low-shrink polyvinyl chloride fibers with a linear density of 1.0.2.0 tex and other synthetic fibers with a linear density of 0.4.0.8 tex in an equal percentage ratio (examples 1,2, 3,4,5);
the content of low-shrink polyvinyl chloride fibers within 50% of the total mass of the material allows you to maintain a positive effect on incombustibility, that is, the filter material remains difficult to combust (does not burn on its own, flows and melts);
in the manufacture of a non-woven filter material with other ratios of the presented set of features, the indicated indicators of effect deteriorate (examples 6, 7, 8).

So, for the material of example 6 from the table, only two signs are observed that the value of its relative thickness H / d _in = 634, i.e. corresponds to a ratio of 530 <N / d _at <700, and an equal percentage contains fibers with different linear densities, but the rest of the signs are not fulfilled, namely this material is made from a mixture of staple, low-shrink polyvinyl chloride fibers with a linear density of 2.5 tex, linear polyester fibers density 1.2 tex, and the specific filtering surface of the material F = 25, i.e. not selected from the optimal inequality 27.5 <F <35. Therefore, this material has a relatively low cleaning efficiency of 84%, although the initial aerodynamic drag is 69 Pa.

An increase in the percentage density compared with a higher linear density of low-shrink polyvinyl chloride fibers in the material up to 75% increases the specific filtering surface of the material and its relative thickness (for example 7 F = 36.1 and N / d _in = 812; for example 8 F = 38.0 and N / d _in = 828), i.e. the specific filtering surface of the material was not selected from the optimal inequality of 27.5 <F <35 and does not correspond to the optimal ratio of the relative thickness of the material 530 <H / d _to <700, which leads to a decrease in cleaning efficiency (for example 7 88% for example 889% ) and an increase in the initial aerodynamic drag (for example 7 90 Pa and for example 8 91 Pa).

A decrease in the relative thickness of the material N / d _in leads to a comparative decrease in cleaning efficiency (for example 2 N / d _in = 604, and the cleaning efficiency of 91%). When the value of H / d _to 700 increasing initial pressure drop and the thickness of the nonwoven filter material, resulting in inappropriate use it in of cellular filters (for example, 7 H / d _B = 812, H = 20 mm, Δ R _n = 90 Pa; for example, 8 N / d _in = 828, N = 21 mm, Δ P _n = 91 Pa);
a decrease in the specific filtering surface of the material F leads to a comparative decrease in the cleaning efficiency (for example 2, F = 30.2 and a cleaning efficiency of 91% for example 6 F = 25, and the cleaning efficiency of 84%). When the F value is more than 35, the initial aerodynamic drag and thickness of the nonwoven filter material increase (for example 7, F = 36.1 and Δ P _n = 90 Pa; for example 8, F = 38, ΔP _n = 91 Pa).

 The positive effect of the introduction of the proposed non-woven filter material in comparison with the prototype (ed. St. USSR N 1673663, class D 04 H 1/58 "Non-woven filter material") is to increase the cleaning efficiency, reducing the weight of the material while expanding its scope without changing performance.

 A comparative analysis and patent research conducted on patentability confirmed that the proposed non-woven filter material meets the criterion of "Novelty."

 The present invention has an inventive step, as it for a specialist does not explicitly follow from the existing level of technology.

 The present invention is industrially applicable, since the technical solution and equipment used are individually tested in the industry, and the use of non-woven filter material as a filter medium in filters for cleaning air from dust remains relevant.

Claims (1)

A non-woven filter material containing a fibrous canvas of a mixture of staple synthetic fibers, including low-shrink polyvinyl chloride fibers and other fibers in an equal percentage glued with a binder, characterized in that the low-shrink polyvinyl chloride fibers in the canvas have a linear density of 1.0 to 2.0 tex, and other fibers have a linear density of 0.4 0.8 tex, and the relative thickness of the fibrous canvas is 530 <H / _{d b} <700, and the specific filtering surface of the material is 27.5 <F <35.0, where H is the thickness of the filter material, d _{is the} average fiber diameter.

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