RU2390004C1 - Method of assessing bonding strength between screen-printing inks and coatings with print media - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method of assessing bonding strength between screen-printing inks, lacquer or some other coatings and print media by tearing away a glued pin with measurement of the tearing force involves cutting a sample of material with coating, preparation of the surface of the pin, depositing a layer of glue on the pin, gluing the pin to the coating of the material sample, putting the sample on an elastic deckle lying on a rigid plate and threading a matrix with an opening on the pin while observing coaxiality of the cylindrical pin and the cylindrical opening in the matrix with subsequent fixation of the assembly through a threaded connection of the matrix and the rigid plate. After gluing the pin to the coating, part of the coating lying under the pin is separated from the coating on the sample.

EFFECT: increased reliability of adhesion force measurement results.

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Description

The technical field to which the proposal relates

The proposal relates to the field of research of materials by mechanical means, and more specifically to devices for determining the adhesive characteristics of non-metallic coatings. The invention can be used in printing and other enterprises for the quantitative assessment of the strength of the fastening of polymer coatings, varnishes, printing, screen or other inks on flexible sealed materials.

State of the art

It is known "device - test sample" for determining the adhesion of coatings containing a matrix with a conical hole, a pin inserted into this hole flush with the working surface of the matrix and the coating applied to the working surface of the matrix and the end face of the pin at the same time (together), and the ratio of the small diameter of the hole and coating thickness is 1.0 ÷ 2.0. The known device implements a test scheme for coating for “clean separation” from the substrate in the normal direction without bending and shear components in a fixed separation force (ed. Certificate of the USSR 180937051, IPC G01N 19/04, published 1993).

Also known is a method of measuring the adhesion strength of a coating to a substrate and a device for determining it, consisting of a matrix with a conical hole and a pin inserted flush into this hole. The method consists in applying the test coating to the working surface of the matrix and the end face of the pin at the same time (together), followed by gluing the union nut on the coating, and rupture in the normal direction at a constant speed of the nut and pin connected by adhesive and coating layers (US Pat. RF 2294531, IPC G01N 19/04, published. 02.27.2007). The device allows to increase the accuracy of measurements in comparison with other known devices, but simultaneously with the measurement of adhesive forces measures the strength of the coating material "shear".

A device is known for determining the adhesion of paints and coatings containing a matrix with a hole, a cylindrical pin with a diameter less than the hole diameter by 1 ÷ 3 mm and inserted flush into this hole, the coating and the adhesive layer deposited on the outer surface of the coating, an elastic decal and a rigid metal plate ( Farenbrukh KV Methodological features of the study of the surface of sealed materials of various nature. // Bulletin of Moscow State University of Printing. No. 6. 2006. S. 52-55).

A disadvantage of the known methods and devices is the inaccuracy of the measurement of adhesive forces when testing sufficiently thick or strong coatings obtained from polymer coatings (LK) materials, due to the significant contribution to the measured value of the cohesive strength of the coating material "tensile along the layer" and / or "across the cross section layer ”, as well as the impossibility of using known methods for assessing the strength of fixing printing ink and other nonmetallic coatings on flexible sealed materials (captive oh oil cloth, foil, etc.).

The essence of the proposal

Solved technical problem is:

- increase the reliability of the measurement results of adhesive forces,

- expanding the scope of the method due to the use in assessing the strength of fastening on flexible sealed materials coatings, varnish layers or layers of printing ink.

The problem is solved in that in the known method for assessing the strength of the connection of screen inks, varnishes or other coatings with sealed materials, including gluing a pin onto a coated material sample, laying the sample on an elastic decal located on a rigid plate and stringing a steel matrix with a hole on the pin subject to the alignment of the cylindrical pin and the cylindrical hole in the matrix, according to the proposal, a sample of the coated material is additionally glued onto an elastic decal and a hard plate, and after sticking the pin on the coating, a part of the coating located under the pin is separated from the coating on the sample. Separate the part of the coating located under the pin from the coating located on the sample by carefully “scratching” the coating with any sharp and thin object, for example, a curved needle or steel wire, excluding touching the pin. In the case of sufficiently thick coatings and strong substrates, a tubular “chemical” drill is put on the pin and, by pressing and rotating the drill, part of the coating located under the pin is cut off coaxially from the coating on the sample.

The problem is also solved by the fact that for gluing the pin to the coating using double-sided tape cut in the form of a disk with a diameter equal to the diameter of the pin. It is also possible to use a pin impregnated with glue and cut in the form of a disk with a diameter equal to the diameter of the pin of filter paper or other non-woven material for gluing the pin to the coating.

The problem is also solved by the fact that the elastic dekel is not used, a sample of coated material is glued to the plate with polyurethane adhesive or double-sided tape.

The proposal is illustrated by an example of the practical implementation of the method and a schematic diagram of a device fixing a sample on a test bench with a variant of a cutting tool used to implement a method for determining the adhesive strength of coatings.

Figure 1. The scheme of the method. The operation of gluing the pin.

1 - pin; 2 - sealed material (film); 3 - coating or layer of paint on a sealed material; 6 - a layer of glue; 10 - elastic dekel; 19 - mounting aids (tripod with holder).

Figure 2. The scheme of the method. The operation of trimming the working area of the coating under the pin with a tubular drill.

1 - pin; 2 - sealed material (film); 3 - coating or coat of paint; 6 - a layer of glue; 15 - tubular drill.

Figure 3. Scheme of the sample prepared for peel tests 4 - part of the coating or paint layer under the pin after separation from the rest.

Figure 4. The scheme of the device in the assembly for testing the sample for peeling of the coating in the constant speed mode of movement of the pin relative to the matrix (separation in dynamics).

1 - pin with a hole for flexible traction; 2 - sample, sealed material (film with one-sided coating); 3 - coating or layer of paint on the sample; 4 - part of the coating or layer of paint under the pin: 6 - layer of glue; 7 - hard (metal) plate; 8 - matrix with a hole for the pin; 9 - flexible traction; 10 - elastic dekel; 12 - bolts; 13 - nuts with flywheels ("lamb")

Figure 5. The scheme of the device in the assembly for testing the sample for peeling of the coating under the action of a constant load (peeling in static).

9 - flexible traction; 16 - fixed mount in the upper tripod clamp; 17 - platform for cargo;

Example 1. The preparation of the sample for testing is as follows. 15 × 50 mm samples are cut out of a printing impression, a polymer product uniformly sealed with ink or varnished.

The surface of the pin is cleaned with a flat grinding wheel, degreased with ethyl alcohol and coated with cyanoacrylate adhesive. The pin is fixed in a vertical tripod, on the subject table under the pin is laid an elastic dekel and a sample of material coated with the tested (sealed) side up. The pin is clamped vertically with a layer of glue to the coating and held under pressure until the glue is completely cured (50 ÷ 70 s).

The pin with the sample and glued on is removed from the clamping device and laid on the bottom metal plate. Holes (pierce) holes for screeds. On top of the entire assembly, a metal (steel) matrix is put on the pin with a hole in the center and two holes for the couplers. The diameter of the central hole in the matrix is 3 mm larger than the diameter of the pin. After laying the matrix, a visual centering of the pin in the hole is carried out by moving the matrix in a horizontal plane. Insert the bolts and fix the device in the assembly. After centering and fixing the assembly, the tubular drill is lowered onto the pin on the pin until the cutting edge of the drill comes into contact with the coating. The rotation of the drill cut off part of the coating under the pin from the rest of the part under the matrix. The drill is removed, and the device in the assembly is attached to a dynamometer or tensile testing machine for stretching at a constant speed.

Example 2. Preparation of the sample for testing and the detachment of the pin is carried out as in example 1, but the elastic dekel is not used, the sample of coated material is glued to the plate with polyurethane adhesive or double-sided tape, and the part of the coating located under the pin is separated from the coating located on the sample, carry out by scratching a curved needle.

Example 3. Preparation of the sample for testing and detachment of the pin is carried out as in example 2, but to fix the glued sample, the steel matrix and the coupler of assembly parts are not used with a threaded connection.

Example 4. The sample preparation for testing and the detachment of the pin is carried out as in example 1, but when testing the adhesion tensile strength of the adhesive contact, the device in the assembly is turned over, the rigid plate is fixed in a fixed tripod clamp, and a platform with a load is attached to the pin. Gradually increasing the mass of the load on the platform, determine the force of separation of the coating from the substrate "in static", corresponding to the adhesive strength of the coating.

Claims (5)

1. The method of assessing the strength of the connection of screen inks, varnishes or other coatings with sealed materials by tearing off a glued pin with a measurement of the tearing force, including cutting a sample of the coated material, preparing the surface of the pin, applying a layer of glue to the pin, gluing the pin on the coating of the material sample, laying a sample on an elastic dekel located on a rigid plate, and stringing the matrix with the hole on the pin, while observing the alignment of the cylindrical pin and the cylindrical hole in the matrix with osleduyuschey threaded fixation assembly template compound and the rigid plate, characterized in that in the coating after application of the coating separated pin located under the pin, the coating located on the sample. 2. The method of assessing the strength of the connection of screen inks, varnishes or other coatings with sealed materials according to claim 1, characterized in that the laying of the sample on an elastic decal or a rigid plate is combined with its additional fixing by gluing. 3. The method of assessing the strength of the connection of screen inks, varnishes or other coatings with sealed materials according to claim 1, characterized in that they separate the part of the coating located under the pin from the coating on the sample by scratching with a sharp object. 4. The method for assessing the strength of the connection of screen inks, varnishes or other coatings with sealed materials according to claim 1, characterized in that they separate the part of the coating located under the pin from the coating on the sample by rotating the tubular drill, worn on the glued pin. 5. The method of assessing the strength of the connection of screen inks, varnishes or other coatings with sealed materials according to any one of claims 1, 2, characterized in that they separate the part of the coating located under the pin from the coating on the sample by scratching with a sharp object or by rotation a tubular drill, put on a glued pin after completion of assembly and connection of the matrix with a metal plate.

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