PRODUCTION METHOD FOR INCREASING THE REFINEMENT CAPACITIES OF PARTICLE FILTERS

Technical Field

The invention relates to a production method for increasing the filtration efficiency from simple filters "HEPA" used for air refining to high efficiency filters.

State of the Art

The most effective air filtration system currently used is the abbreviation of High Efficiency Particulate Arresting - herein referred to as HEPA. They consist of a mat comprising randomly arranged fibres. The fibres generally consist of glass fibre and have filtration diameters from 0.5 to 2.0 pm. HEPA filters have been designed to scan particles larger than 0.3 pm with 99.95% efficiency, however, they do not filter gases and scent molecules. It is based on air passing through a fine net catching the harmful particles such as pollen, dust mites, organic micro wastes, stack effluents.

ULPA is the abbreviation of Ultra Low Penetration Air-Ultra Low Air Permeability. An ULPA 25 filter can clean at least 99.9999% for particles of 0.12 pm or larger from the air. Virus diameters range between 20-400 nm (0.02-0.4pm). The bacterial diameters are around 02-2.0 pm (micrometer). ULPA filters are closely related to HEPA filters, however they are more efficient. These filters are used in air filtration and refinement systems to control the levels of airborne particles and stop the spread of toxic agents and infectious diseases. They can clean dust, pollen, mold, bacteria and airborne particles. HEPA and ULPA filters are used in applications that require an effective filtering of airborne pathogens that can result in aggravating asthma and allergies or diseases. These filters are also useful in the production environments that require very clean air.

Some of the embodiments are as follows: air pollution, biological safety cabinets, medicine, operating room air cleaning, clinical and health facility air cleaning, vacuum cleaning systems, critical product manufacturing, hazardous substance collection, biotechnology, food processing, airline cabin air filters.

For this purpose, in the invention No. W0 2017/135539 and entitled "electric dust collecting filter production method and electric dust collecting filter production", the method includes the following steps: a dust collecting electrode assembly step for mounting the dust collecting electrode to a mounting hole of the frame body; a discharge frame assembly step for connecting the discharge frame to the frame body by means of an insulation element; and a discharge electrode assembly step for arranging the discharge electrode in the axial direction by means of the discharge frame within the dust collecting electrode and for fixing it. The invention enables to finish the assembly of the dust collecting electrode and to make the dust collecting electrode fine and light, and assembly efficiency. The manufacturing of the dust collection filter can be improved significantly even if a large number of dust collecting electrodes are used.

A dust filter is mentioned in the utility model application No. TR 2012/06122. This filter installation includes at least one filter chamber which has filter hoses inside and an unrefined gas line joined through the throttle lever of a channel-like separation into a gas inlet door of at least one filter chamber. The separated throttle lever distorts a gas flow flowing through the unrefined gas line at least in part in the direction of the gas inlet door of at least one filter chamber. For this purpose, the invention consists of elements and features such as filter hose, filter chamber, inlet door, throttle lever, gas line, gas inlet port, gas flow direction, guide plate.

In the European Patent No. EP1677894B1, a filter configuration has been also described. The invention relates to a clean gas chamber and a dust gas chamber, and a dust filter having a separation base placed between the tubular filters vertically mounted therein; the top of these tubular filters is open to the clean gas chamber. A compressing element is disposed at the open end of each tubular filter at the level of the separation base and it compresses the filter material of the tubular filter between itself and the edge of the opening. The clamping element is equipped with passages of which the upper edges are higher than the upper surface of the separation base, thus it enables the liquid collection to be easily discharged on the upper surface.

However, neither in the mentioned inventions nor in the other descriptions in the state of art, a production method that ensures to increase the filter refinement capacity by melting a carrier and/or solute and/or adhesive consisting of water or solvent and by making the surfaces of filters, preferably one side, adherent is not mentioned.

Further, it can be understood from the names of the inventions carried out for some filter configurations mentioned above that filter configurations do not include any innovations to increase the refinement capacities (particle retention rate) of present filters of our invention and there is no inventive step.

Definition of the invention

The present invention includes an application for increasing the refinement capacities of simple fibre filters, cloth filters, filters composed of active carbon, mineral structures such as perlite, gas concrete, zeolite, kieselguhr, vermiculite or artificial or natural sponge structures, natural or artificial fibre filters, HEPA and ULPA filters.

The invention is a new production method that increases the filtration capacity and prevents the passage of smaller particles with the application after manufacturing without changing the structure of the filters. High efficiency can be obtained with this method by using larger cellular and cheaper filter systems instead of narrower and more costly filter systems that make air passage difficult. Utilizing another method allows for increasing the performance of products having reduced waste load and poor filtering capabilities, thereby enabling the manufacturing of cost-efficient and environment friendly filtering systems from natural fibers.

The method of the invention is defined by the adhesion of all kinds of physical particles to the chamber walls of the filters and preventing them from passing during the air passage.

Adhesion is provided with adhesives having high adhesive force called PSA (Pressure Sensitive Adhesive). These adhesive agents do not dry, do not change too much in hot and cold, do not rot and disintegrate and they are environmentally friendly products.

Pressure sensitive adhesive PSA is also known as self-adhesive substance. In pressure sensitive adhesives, no solvent, water or heat is required to activate the adhesive. The connection with the adhesive is directly related to the pressure to be applied on the surface of the adhesive. Pressure sensitive adhesives (PSA) are used in many different applications with new uses discovered almost every day.

Generally, there are three types of PSA group.

Rubber: They are adhesives that are based on natural or synthetic rubbers and formulated with adhesive resins, oils and antioxidants. Rubber is the most cost-effective PSA and presents fast adhesion feature. Rubber adhesive is not recommended for high temperature applications.

Acrylic: They are adhesives that are formulated with acrylic polymers and generally have better long term aging and greater resistance to solvents and environmental factors. Acrylic adhesives typically develop a stronger connection than conventional rubber adhesive and can take higher temperatures.

Silicone: They are formulated with a single adhesive that adheres well with silicone polymers and silicone substrates. Silicone adhesives are relatively expensive and have a very low initial adhesion, but they can resist higher temperatures than both rubber and acrylic adhesive. Apart from these, there are products such as polybutens, rosin esters, bio-based products, EVA copolymers in intermediate class.

The type of solvent in relation to each group of products is based on the formulation of the manufacturer, and the product concentration suitable for this type of solvent is prepared.

Different functions can be achieved for the product obtained by the method of the invention.

Different disinfectants and biocides can be added to the PSA for the destruction of a bacteria or virus adhered to the chamber wall. These are cationic disinfectants, iodine etc. halides, Polyvinylpyrolidone-lodine (PVPI), colloidal silver, scent-retaining compounds, chemicals that are reactive to certain types of contaminants.

Description of the invention

The invention is related to the production method increasing the filtration efficiency by providing function to the physical filters used for air cleaning and comprises the following steps:

-Preparing a pressure sensitive adhesive (PSA) solution to be applied to the inner and/or outer surface of the filter in a concentration suitable for the type of filter to be used,

-Providing disinfective feature by placing antimicrobial agents in the prepared PSA solution,

-Coating said PSA solution on the surfaces of cell homogeneously by impregnating it to the porous/fibrous structures of filter,

-Coating the carrier solvent with the adhesive material by taking it from said filter and PSA as all of the cell surfaces of the filter structure will be homogen,

-Packaging the solvent-backed filter material having adhesive fibres or cell walls.

The invention is essentially a similar method to enable the filter surfaces produced in different technologies from sponge to ULPA to be adhesive like surface of a packing tape by melting the carrier (water-solvent) or solute or adhesive.

In the preparation of PSA solution, which is the first step of the invention, the aim is to cover the inner and outer surfaces of the filter with the PSA solution. The suitable concentration may vary for each filter type and PSA type. For example, a 25% concentration in an acrylic-based PSA solution is sufficient, whereas a 10% concentration in a rubber or polybuten-based PSA solution can be sufficient. There are also types of PSA fluidized by temperature. Filter structures and PSA selection need to be compatible. These rates and PSA types are optional for the manufacturer and the user.

Solvent type, filter type and solute suitable for PSA type are used in placing the antimicrobial agents of PSA solution. It is aimed to transfer the adhesive material homogeneously to the filter. Antimicrobial agents used in the step of placing antimicrobial agents are the whole products under the name of disinfectants (Polyvinylpyrolidone-lodine solution, cationic disinfectants, halogen-based disinfectants, oxidants, phenolics, anilides, aldehydes, cresols, water-soluble gases). There are hundreds of different types of disinfectants. Germicides and biocides are also disinfectants classified according to different usage areas. Some of the scent-retaining and neutral compounds (sodium bicarbonate solution, micronized calcium hypochlorite, calcium hydroxide, EDTA, glycols etc.) can also be used for the purpose of disinfecting contribution. Further, there are types that are liquidized by heat. In this type of PSAs, the solution consistency can be applied to the filter by using heat instead of the step of placing antimicrobial agents. In some cases, placing antimicrobial agents can be skipped by observing the condition of the filter and PSA.

In a preferred embodiment of the invention, reactive components that can be placed in the PSA for the filter types aimed according to the application areas can be used in the step of placing antimicrobial agents. For example, disinfectant solutions can be used in the applications for the operating room. If the contaminant is certain, the component for it can be added to the PSA as a standard.

PSA is produced as water-based emulsion solutions or in the form of solvent-based solutions or in the form of solid or liquid by companies. After placing the antimicrobial agents and/or the heating process, the prepared mixture will be applied to the filter structures. A consistent PSA solution cannot be applied to the porous structure homogenously, and it may also obstruct the excessive amount and viscosity filter holes. Applying the mixture to the filter is performed by the impregnation method. Again, a solvent suitable for PSA and filter type are used here. Some of the PSA formulations are water based, and the other formulations are solvent based. PSA manufacturers sell these products readily. Water-based PSA emulsions can be diluted with water. Solvent-based PSA types can also be diluted with the solvent type of the solution prepared by the manufacturer. These can be hydrocarbon solvents, chloric solvents, aromatic solvents, ester or ketone solvents, turpentines, essential oils, alcohols or glycol ethers or thinner mixtures thereof. Some of the PSA types can be applied in a hot form and solvent may not be required. The homogeneous coating is based on the impregnation of the solution in a way that the PSA solution penetrates into all surfaces of the mesh type or porous type filtration material. These methods can be physical methods such as immersing into the solution, spraying, diffusion, vacuum diffusion, penetration with pressure. If the filter is a soft structure like a sponge, the material can be allowed to take the liquid completely by repetitive compressing and realising. Products are introduced into PSA solution in rigid structures such as kieselguhr, pearlite, fabric HEPA and ULPA, and subsequently the air is extracted from the container by means of vacuuming and in this way, all the pores are wetted with the PSA solution. PSA types vary based on water or solvent. Since the sponge structure is deformed, a sponge structure made of polyurethane should not be treated with a type of PSA dissolved in methylene chloride. Treating with a water-based PSA or a solvent that will not lead to deformation will be appropriate. Therefore, the interaction of the filter type to be treated according to water or solvent must be determined in advance. Further, PSA types that are liquefied by heat can be applied to filter structures that will not be affected by heat.

After the process of adhesive impregnation, the solvent is partially or completely withdrawn from the filter. This is the process of carrying an adhesive to the desired target surface. This carriage is performed with a solute. These solvent types are water or organic solvents. After applying the filter tissue homogeneously without a performance loss, the solute should be withdrawn. These can be methods such as clamping, pressing, drying, vacuum or removing with air.

The most of said filters are used in the field of health. Therefore, they should be protected from the production environment without microbiological or toxic contaminants. Thus, it is important that the filter surfaces of which the solute is removed during the packaging process is not contaminated.