RU2770380C1 - Method for manufacturing elastic synthetic medical gloves - Google Patents

Abstract

FIELD: light industry.SUBSTANCE: invention relates to the light industry and is intended for the manufacture of elastic synthetic medical gloves. The method for manufacturing elastic synthetic medical gloves involves immersing a template in the form of a hand covered with a waxy release agent, first in a bath with a powdered or liquid coagulant, then, after partial drying, in a bath with an electrolyte containing synthetic or natural rubber, followed by refinement using leaching and drying processes. At the same time, while the mold is in a bath with electrolyte, the template in the form of a hand is affected by electric and ultrasonic hydroacoustic fields of an asymmetric waveform at frequencies from 10 Hz to 1500 Hz and 20 kHz to 40 kHz, respectively. The effect of the fields is carried out during the entire time the template is in the bath with the electrolyte for 7-15 seconds, depending on the type of coagulant and the composition of the electrolyte.EFFECT: invention makes it possible to reduce the roughness of the surface of medical gloves, reduce the thickness of their walls, while maintaining the strength of gloves.1 cl, 2 dwg

Description

The present invention relates to light industry, namely to polymer industry and is intended for the manufacture of elastic synthetic medical gloves.

Latex and nitrile medical gloves are a mandatory personal protective equipment for clinic, dental and beauty parlor staff. They belong to personal protective equipment and are an indispensable condition for operations, examinations, diagnostics and other manipulations and procedures (injections, blood sampling, work with drugs). The main purpose is to create a protective barrier. Therefore, gloves must first of all be durable, flexible and impervious to water, steam, bacteria and viruses.

Medical gloves are widely used not only in this industry, but also outside it: they are used as protection for the skin of the hands in contact with chemically aggressive, toxic components, hygiene in food production, catering and restaurant business, pharmacology, research works and the like. The correctness of the choice is determined by the nuances of their application.

Gloves differ in materials, manufacturing technologies, inner surface treatment, purpose, on the basis of which they can be grouped as follows.

Natural latex gloves contain more than 60% polyisoprene particles, which makes polyisoprene gloves the closest in properties to conventional latex gloves. The advantages of natural latex are widely known: gloves made of this material fit the hand well, stretch, soft and elastic.

At the same time, they contain a significant amount of proteins that cause allergic reactions and, in turn, are not resistant to oils, alcohols, and esters. The world standard for the presence of proteins in a natural latex glove is less than 50 µg/g, determined by the Lowry method. A number of manufacturers offer gloves with protein levels below 20 µg/g.

Nitrile gloves perfectly withstand the influence of aldehydes, alcohols, phenols and acids, which makes it possible to use nitrile gloves in laboratories when working with aggressive environments. In addition, synthetic gloves do not cause allergenic reactions, as they do not contain proteins, but in some cases they can cause contact dermatitis if used for too long. Due to the low elasticity and extensibility, nitrile gloves are practically unsuitable for surgery.

Polyisoprene and polychloroprene gloves are among the most expensive, so they are mainly used as surgical gloves. There is no reasonable need to use polychloroprene and neoprene examination gloves, as they are similar in chemical resistance to nitrile gloves. At the same time, the use of such gloves during surgical operations allows you to provide the highest level of protection for all members of the surgical team.

Vinyl gloves are quite cheap, but they have one important drawback: they are easily permeable to any proteins (including blood proteins) and microorganisms, which does not allow them to be used even for a short-term examination of patients. Vinyl gloves are widely used to maintain the proper level of sanitation.

The main difference from latex gloves is hypoallergenicity, since they do not contain natural latex.

Synthetic or natural rubber gloves, such as carboxylated nitrile butadiene rubber composition, are typically produced by the process of dipping a hand-shaped template, or mandrel, first into a bath of powdered or liquid coagulant, then dipping the template into a synthetic or natural rubber bath and finishing. through leaching and drying processes.

One of the most important parameters by which the quality of nonwoven products, namely medical gloves, is evaluated is the surface roughness and their elasticity.

A known method for the manufacture of polymer gloves, including applying to the cuff and wrist sections of the template in the form of a hand, respectively, concentrated and diluted solutions of the coagulant by successively dipping the cuff and wrist sections of the template into the appropriate solution and forming a glove by dipping the template into a latex solution, followed by washing the wrist section of the template running water (USSR author's certificate No. 1140991 dated 05.11.1983 [1]).

The disadvantage of polymer gloves obtained by the method [1] is insufficient elasticity, which limits the possibility of their use in medical practice.

There is also known a method for manufacturing gloves, in which a concentrated solution of a coagulant is first applied to the cuff section of a mold fixed on the holder and the wrist section of the mold is dipped into a diluted coagulant solution, and then the product is molded in a latex solution. A concentrated coagulant solution is applied to the cuff area by spraying using a special device (England Patent R 1378131, class B 5 A, 1974 [2]).

However, this method [2] does not ensure uniform application of the coagulant solution to the cuff area, which leads to uneven deposition of the latex layer. In addition, complex equipment is required to implement this method.

Also known is a method for producing multilayer medical gloves from nitrile rubber latex, described in published application for US patent No. 2008/0138723 A1 [3], where the thickness of the multilayer glove is between 0.01 mm and 0.3 mm. This method involves repeatedly dipping the template into a latex solution to form thin, multi-layered gloves, which adds significant complexity and expense to the manufacturing process and overwhelms the cost advantages provided by making a thinner product. Significantly, the scarcity of thin nitrile rubber medical examination gloves on the market is actually highlighting the difficulty of dealing with these problems economically and effectively.

The closest in technology to the claimed object is a method for manufacturing elastic synthetic latex medical gloves, described in RF patent No. 2498784 C2 dated 27.08.2009 [4]. This method involves immersing a hand-shaped template 1 coated with a waxy separating agent first into a bath 2 with powdered or liquid coagulant 3, as a result of which a thin layer 4 of coagulant 3 will cover the wrist part of the template 1 (Fig. 1). Then template 1 is immersed in bath 5 with electrolyte 6 containing synthetic or natural rubber, as a result of which a thin layer of electrolyte 7 containing latex will settle on the brush part of template 1, covered with a thin layer of coagulant 3. Next, template 1 is removed from bath 5, followed by finishing section 7 with leaching and drying processes, resulting in a thin elastic glove-shaped latex layer on the template 1. After drying, the finished elastic synthetic glove is removed from template 1.

The disadvantage of this invention [4] is the presence of large pores in finished products, technological complexity and the inability to control the coagulation process.

The aim of the invention is to reduce the surface roughness of medical gloves, reduce the thickness of their walls, while maintaining the strength of the gloves.

The technical result of the invention is expressed in the expansion of the arsenal of methods and technical means for the manufacture of elastic synthetic medical gloves. It is achieved by the method of manufacturing elastic synthetic medical gloves, by immersing a hand-shaped template coated with a waxy release agent, first in a bath with powder or liquid coagulant, then, after partial drying, in a bath with an electrolyte containing synthetic or natural rubber, with subsequent refinement using leaching and drying processes, while the mold is in a bath with an electrolyte containing synthetic or natural rubber, a hand-shaped template is exposed to electric and ultrasonic hydroacoustic fields of an asymmetric signal shape at frequencies from 10 Hz to 1500 Hz and 20 kHz to 40 kHz, respectively, during the entire time the template is in the electrolyte bath 7-15 seconds, depending on the coagulant and electrolyte composition.

In FIG. 2 schematically shows the distinctive features of the proposed method.

In contrast to the closest analogue [4], described above and in Fig. 1, in our method, a template 1 immersed in a bath 5 with an electrolyte 6 containing synthetic or natural rubber is exposed to electric and ultrasonic hydroacoustic fields of an asymmetric signal shape at frequencies from 10 Hz to 1500 Hz and 20 kHz to 40 kHz, respectively (Fig. 2).

Ultrasonic action is produced by two generators 8 with an operating frequency of 20 kHz to 40 kHz, the signal from which is fed through amplifiers 9 to acoustic emitters 10 immersed in a bath 5 filled with electrolyte 6 containing synthetic or natural rubber. Ultrasonic emitters 10 consist of two perforated metal plates 11 - stators and vibrators 12, which are high-resistance membranes made of an elastic thin film coated with a conductive material.

The source of electrical signals of an asymmetric shape contains the generator 13 itself with a frequency from 10 Hz to 1500 Hz, a high-voltage amplifier 14 and two electrodes immersed in the bath 5. Conductive vibrators 12 are used as electrodes.

Generators (electric and ultrasonic) act on section 7 of template 1, located in bath 5, with electrolyte 6 for 7-15 seconds, depending on the type of coagulant and electrolyte composition.

The present invention makes it possible to influence the intensity of flow mixing by exposure to electric and ultrasonic hydroacoustic fields with an asymmetric signal shape, which in turn directly affects the coagulation process and allows you to control the layer thickness, create different sublayers due to selective control of the movement of ions and larger ones compared to ions, coagulant globules and the concentration of metal salts in the process of coagulation, thus zoning affecting the thickness, roughness, strength and elasticity of the final product, depending on the characteristics of the field, and also allows you to draw Chladni figures not only on the surface, but also in the volume of the layer.

The required frequencies of the electric field can be calculated from the work (M.A. Kazaryan, I.V. Lomov, I.V. Shamanin, Electrophysics of structured salt solutions in liquid polar dielectrics (M., Fizmatlit, 2011), 190 s), depending from the original raw material.

From the work Synthetic rubber [Text] / Ed. collegium: G.S. Whitby (chapter, ed.) [and others]; Per. from English. ed. I.V. Garmonov. - Leningrad: Goshimizdat. [Leningr. Department], 1957. - XIV, 998 s It is known that the technological parameters of the coagulation process taken into account include: the type, concentration and amount of electrolyte used in coagulation, which ensures not only complete coagulation of the latex during its contact with the electrolyte, but also the formation of a stable dispersions of rubber in the aqueous phase with particles (crumb) of the required size; temperature; the degree of dilution of the resulting crumb and the intensity of mixing flows; the duration of contact of the electrolyte with the latex and the duration of the individual stages of chemical reactions required in the process of coagulation.

There is a phenomenon of selective drift of solvated ions under the action of an external "asymmetric" electric field (M.A. Kazaryan, I.V. Lomov, I.V. Shamanin, Electrophysics of structured solutions of salts in liquid polar dielectrics (M., Fizmatlit, 2011), 190 s), which allows selective control of the diffusion rate and the concentration of metal salt ions.

Ultrasonic hydroacoustic waves generated between the stators and the membrane due to the creation of an electric field between the stators of the electrodes and electric waves between the vibrators of the hydroacoustic wave generator, in turn, directly affect the coagulation process and allow you to control the layer thickness, create different sublayers due to the selective control of the movement of ions and concentration of metal salts in the process of coagulation, thus zoning affecting the thickness, roughness, strength and elasticity of the final product, depending on the characteristics of the field.

Let's take the use of our proposed method of manufacturing an elastic synthetic glove. First, the hand-shaped template treated with the waxy release agent was immersed in a coagulant solution bath, the coagulant solution having a calcium ion concentration of 4% based on the mass of calcium ions in the coagulant solution. This procedure was followed by partial drying of the template area covered with the coagulant solution and the waxy release agent. Next, the template was immersed in an electrolyte bath with an emulsion of nitrile butadiene rubber latex having a dry matter content in the latex of about 12 wt. %, for a holding time of about 7 seconds, to form a layer of coagulated nitrile butadiene rubber latex on the surface of the template. The coagulation process was influenced by electric and ultrasonic waves of asymmetric shape, created by generators. The electrical signal generator operates at frequencies from 10 Hz to 1500 Hz, and the ultrasonic wave generators, respectively, at 20 kHz to 40 kHz.

Electric and ultrasonic fields of asymmetric shape, affecting the coagulation process, allow you to control the layer thickness, create different sublayers due to the selective control of the movement of ions and the concentration of metal salts during the coagulation process, thereby zoning the thickness, roughness, strength and elasticity of the final product, in field characteristics.

After the template was removed from the nitrile butadiene rubber latex emulsion, the template containing the coagulated nitrile butadiene rubber latex was immersed in a water bath to remove excess calcium ions, and then the coagulated nitrile butadiene rubber latex was dried to form a glove body on the template.

At the final stage, the glove body was removed from the template by turning the glove body inside out.

Claims (1)

A method of manufacturing elastic synthetic medical gloves by immersing a hand-shaped template coated with a waxy release agent, first in a bath with a powder or liquid coagulant, then, after partial drying, in an electrolyte bath containing synthetic or natural rubber, followed by finishing with leaching and drying processes, characterized in that while the mold is in a bath with an electrolyte containing synthetic or natural rubber, a hand-shaped template is exposed to electric and ultrasonic hydroacoustic fields of an asymmetric signal shape at frequencies from 10 Hz to 1500 Hz and 20 kHz up to 40 kHz, respectively, during the entire time the template is in the electrolyte bath 7-15 seconds, depending on the type of coagulant and electrolyte composition.

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