RU2228845C1 - Method of joining of the polymeric material components of different thickness - Google Patents

Abstract

FIELD: production of medical equipment and tools. SUBSTANCE: the invention presents a method of joining of the polymeric materials components of different thickness by welding. It may find application in joining of the polymeric materials used in medicine and in production of the medical equipment and tools, for example, droppers of the device for intravenous introduction of infusion solutions and blood substitutes of single-use application. The method provides for positioning of the polymeric pieces overlapping each other, pressing them in a ring zone of the joint by a heated instrument and heating of the zone of the joint. At that it is possible to join the component parts of the polymeric materials having different softening temperature. In the capacity of a component part with the highest softening temperature is used a grid with a size of a mesh of 40-250 microns. The component parts to be joined are placed at an angle to each other. The instrument is heated up to the softening temperature of the polymeric material with the lowest softening temperature. The heating is conducted through a grid from the internal area of the ring zone. The invention allows to join the component parts of polymeric materials of a different chemical nature and with different softening temperatures, simplifies the technology and decreases the labor input. EFFECT: the invention allows to join polymeric materials of a different chemical nature and with different softening temperatures, simplifies the technology and decreases the labor input. 2 dwg

Description

The invention relates to the field of welding, is intended for the connection of polymeric materials and can find application in medicine in the production of medical equipment and devices, for example, droppers, devices for intravenous administration of infusion solutions and single-use blood substitutes.

A known method of connecting bodies of thermoplastic materials, allowing to connect the body by fusion welding using radiation (patent No. 2116889, Russia, MKI 6 V 29 C 65/14, 63/10, 53/56, application. March 31, 94). In this method, the first body is applied to the second body in the form of a first layer having a first and second major surface. The second main surface of the second body is brought into contact with the main outer surface of the first body. After that, the connected bodies are irradiated in the wavelength range of infrared radiation. When the layers are irradiated, two adjacent main surfaces of the first and second layers are heated to the welding temperature, connecting them together by fusion welding.

The disadvantages of the method are the difficulty of uniform heating of both bodies in the case of unequal absorption of infrared radiation by the bodies, for example, if the body is transparent to infrared rays. In addition, in this joining method, the layers are heated to a welding (melting) temperature, which does not allow joining materials different in chemical nature, having different softening points.

A known method of joining polymer materials (patent No. 2171434, Russia, MKI 6 V 29 C 65/40, 65/02, application. 12.05.97), in which the connected surfaces are clamped in a mold, the material of which has a coefficient of thermal expansion, according to at least equal to the coefficient of thermal expansion of the joined polymer surfaces, the mold has a gap covering the joint of the surfaces, a wedge-shaped protrusion along the perimeter of the heat-affected zone and a channel for injection of the polymer melt. The edges fixed in the mold, crimped by a wedge-shaped protrusion, are heated to the pour point by applying the same polymer under pressure to the melt gap.

The disadvantage of this method is its complexity. The presence of a mold increases the time of the welding cycle associated with opening and closing the mold, complicates the automation of the process, eliminates the possibility of connecting parts if one part is placed in another, and filling should not be done around the perimeter of the heat-affected zone, but inside the part with large diameter.

A known method of assembling blocks of irrigator or water trap cooling towers (patent 2085385, Russia, MKI 6 V 29 C 65/60, application. 06.22.94), in which the fixing of the elements of the blocks and retainers on the tie tubes or rods by contact heating of the ends of the latter to a temperature , 20-50 ° C higher than the melting temperature of the material of the coupling tubes or rods.

The disadvantage of this method is the deformation of the part, which is caused by the melting of the material throughout the thickness of the layer.

Closest to the technical nature of the invention is a method of welding different thickness parts from polyolefins (patent No. 2000208, Russia, MKI 5 B 29 C 65/02, 65/18, claimed. 09.26.91), which consists in placing parts relative to each other overlap, squeezing parts in the annular zone of the connection with a heated tool and heating the specified zone.

The disadvantages of the method are:

- the fact that the connection is possible only from the same type (of the same chemical nature) materials, the connection of which occurs due to the melt and mutual penetration of the layers of materials into each other - the diffusion of sections of molecular chains,

- activation of the surface of parts by corona discharge is required.

The aim of this invention is to provide a method for connecting parts from polymeric materials with different chemical nature, with different softening points.

This goal is achieved due to the fact that in the known method, including placing the parts overlap relative to each other, squeezing them in the annular connection zone with a heated tool, heating the connection zone, the connected parts are made of polymer materials with different softening temperatures, while the mesh is made with a value cells of 40-250 microns from a material with a high softening temperature, the connected parts are placed at an angle to each other, the tool is heated to the softening temperature of the material of the part, having minimal boiling softening temperature, and heating is carried out through the mesh with the inner portion of the annular zone.

The proposed method allows you to connect parts made of various materials, such as plasticized PVC and nylon, polyethylene and polyester fabric, polyethylene and polycarbonate. This is achieved due to the fact that heat transfer is not carried out on the entire thickness of the parts to be joined, but only on their part, which allows you to save the shape of the parts. In addition, the proposed method simplifies the technology of connecting the filter mesh with the body of the product, eliminates expensive injection equipment for the manufacture of the mandrel of the mesh, reduces the complexity of the process, shortens the process cycle, simplifies automation and reduces economic costs.

Figure 1 shows a General view of the dropper;

Figure 2 - the contact point of the materials to be joined.

The implementation of the proposed method is shown in the examples.

Example 1

The dropper case 2, made of plasticized PVC with a softening temperature of 135 ° C, is placed in the holder 1. In the case with a wall thickness of 1.2 mm, a grid 3 of a thickness of 0.08 mm, with a mesh size of 100 μm, made of nylon with a softening temperature is placed 200 ° C. Heater 4 is heated up to the softening temperature of PVC (T = 135 ° C), and the mesh is pressed against the wall of the housing. In the place of contact of the heater and the mesh material 5, the mesh material is heated only in a limited area of contact with the heater to a temperature of 135 ° C, while the central part of the mesh practically does not warm up. The heated part of the mesh, in contact with the dropper body, transfers heat to the material of the wall of the body, while only in the contact area does the material of the body go into a plastic state. Under the influence of external pressure, the edges of the mesh penetrate into the softened material of the dropper body wall. Softened PVC flows into the mesh cells. After depressurization and heating, the PVC hardens, forming a strong connection to the nylon mesh.

Example 2

The same as in example 1, but the heater is heated to T = 180 ° C.

Example 3

The same as in example 1, but the dropper body is made of polyethylene, the mesh is made of polyester fabric, and the heater is heated to T = 120 ° C.

Example 4

The same as in example 1, but the mesh is made of a polyester fabric, and the heater is heated to T = 180 ° C.

Example 5

The same as in example 1, but the dropper body is made of polyethylene, the mesh is made of polycarbonate, and the heater is heated to T = 120 ° C.

Example 6. The same as in example 1, but the cell size of 40 microns.

Example 7. The same as in example 1, but the cell size of 250 microns.

The choice of cell size is explained by the fact that, within the specified cell size limits, the grid performs the filter functions necessary to prevent the penetration of mechanical inclusions or blood clots through it. A mesh size of less than 40 microns does not allow the softened material of the housing to pass through the mesh cells and, connecting with the housing, create a strong connection. A cell size greater than 250 microns is not acceptable, because the grid will not function as a filter.

Thus, the proposed method allows you to connect different thickness parts from polymeric materials having different chemical nature and different softening temperatures.

Claims (1)

A method of connecting different thickness parts from polymer materials, including placing the parts overlap relative to each other, squeezing them in the annular connection zone with a heated tool, heating the connection zone of the parts, characterized in that the parts to be joined are made of polymeric materials with different softening temperatures, while the quality of the part with a high softening temperature, a mesh with a cell size of 40-250 microns is used, the connected parts are placed at an angle to each other, and the tool is heated to ry softening material parts, having minimal temperature value, the heating is carried out through the mesh with the inner portion of the annular zone.

Images