RU2444543C2 - Heat-sensitive polymer material for printing - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: heat shrinking film made from thermoplastic has areas with a modified structure and local shrinkage different from shrinkage of the whole film. Said areas appear after heat treatment and differ from the rest of the material on colour, transparency, direction of the lines of the printed pattern and/or are distinguished by surface microrelief.

EFFECT: invention provides printing products and film packaging with protection from copying and forgery and from non-regulated storage of a heat-sensitive product at high temperature.

4 cl, 9 dwg, 4 ex

Description

The invention relates to materials that differ in the structure of the substance (polymer) used for the production of critical printing products that are resistant to counterfeiting, and more specifically, sealed polymer films with a protective watermark, which can be used in the manufacture of original packaging, security stamps, tags and labels.

A data carrier is known which is essentially a sealed polymeric material with a security element for the manufacture of banknotes, identity cards and similar responsible printing products resistant to counterfeiting, equipped with a security element (RF Patent 2384884, IPC G07D 7/12, published 04.01.2006 ) The technical result is to increase the accuracy of the manufacture of protection elements containing a printed image and a laser marking formed by the action of laser radiation on the polymer.

Known two-layer material for the manufacture of packaging products containing a non-woven fabric and a film having a predetermined shrink response in response to heating of the film, the film forming a shell after shrinkage in response to heat applied to the film, and the non-woven fabric has non-continuous bonds with the film to provide the movement of the film and the nonwoven fabric relative to each other as the film shrinks (RF Patent 2001127976, IPC 7 B65D 81/02, publ. 10.10.2003). The material is characterized in that the film is made of thermoplastic, is heat-shrinkable both in the longitudinal and in the transverse direction, and has a shrink response in the longitudinal direction less than the shrink response in the transverse direction.

Closest to the claimed is a thermosensitive printing material with a thickness of 5 to 500 microns from polyethylene, which is a mixture of a homopolymer and an ethylene copolymer having a molecular weight distribution in the range from 5 to 40 and a weight average molecular weight of at least 100 kD. The films satisfy the operational and technological requirements of the printing and packaging industries with regard to melt strength, cold strength and other mechanical properties at the stages of hot, cold shrinkage, and also after shrinkage (Pat. RF 2288238, IPC C08J 5/18, publ. 20.10 .2000).

A disadvantage of the known material is the lack of potential ability to protect responsible printing products from counterfeiting, as well as film packaging and flexible containers made of thermoplastic polymeric materials.

The technical problem to which the invention is directed is to provide copy protection and counterfeiting of critical printing products, as well as film packaging and flexible containers made of thermoplastic polymeric materials marked with a bar code or other bar image, as well as, if necessary, protecting the contents packaging from unregulated storage of heat-sensitive goods at elevated temperatures and / or unacceptable multiple heating before use.

SUMMARY OF THE INVENTION

The stated technical problem is solved in that the known heat-sensitive polymeric material for printing, which is a heat-shrinkable film of thermoplastic, according to the invention contains sections with a modified supramolecular structure and local shrinkage, different from the shrinkage of the entire film, which form a watermark, which manifests itself after heat treatment in reflected light , “To the light” and “to the touch” as a section that differs from the rest of the material in color, transparency, and the direction of the dashed lines printed pattern and / or distinguished by a microrelief of the surface. The proposed material during shrinkage in length has no shrinkage in width and / or has a Poisson's ratio in shrinkage in width of 0 ÷ 0.1. As a thermoplastic for its manufacture, plasticized polyvinyl chloride, polypropylene, low density polyethylene, high density polyethylene, fluorine-containing polyolefins, polyamide, polyethylene terephthalate are used.

The invention is illustrated by a macrograph of a sample of material after heat treatment (Fig. 1), a microphotograph of a printed pattern distorted due to inhomogeneous shrinkage (Fig. 2) and the results of an experimental study of the mechanical properties of heat-sensitive (heat-shrinkable) polymeric materials for printing from different thermoplastics (Figs. 3-4), examples of the form and practical use of "watermarks" with different shrinkage, different from the rest of the material in a larger and smaller direction (Fig.5-9). In Fig.5 and Fig.8, the portion of the film forming a hidden "watermark" in the form of a narrow strip has a shrinkage that differs from the rest of the material in a smaller direction. The shrinkage gradient of the material is directed outward.

6 and 7, the portion of the film forming a hidden "watermark" in the form of a narrow strip has a shrinkage that differs from the rest of the material in a larger direction. The shrink gradient is directed toward the inside of the strip.

Figure 1. A closeup of a cross-linked water-sensitive polyvinyl chloride film with a watermark in the form of a cross after heat treatment and shrinkage.

Figure 2. A microphotograph of a line of a printed line drawing on a sample of a heat-sensitive polyvinyl chloride film with a “watermark” after heat treatment and shrinkage. 1 - the width of the lines of the printed pattern in the area of the "watermark", 2 - the width of the lines of the printed pattern in the common areas.

Figure 3. Illustration of the dependence of the relative deformation during shrinkage of the heat-sensitive film on the heat treatment temperature: 1 - polypropylene film; 2 - a film of plasticized polyvinyl chloride, 3 - a film of low density polyethylene.

Figure 4. Illustration of the dependence of the shrinkage voltage of the heat-sensitive film on the heat treatment temperature: 1 - sheet heat-shrink film of plasticized polyvinyl chloride; 2 - shrink sleeve label made of plasticized polyvinyl chloride.

Figure 5. Scheme of a sealed product barcode sample of a heat-sensitive film with a "watermark" with increased shrinkage in the form of a narrow strip, located at an angle to the direction of the strokes. 1 - before heat treatment; 2 - after heat treatment.

6. Scheme of a sealed product barcode sample of a heat-sensitive film with a "watermark" with increased shrinkage in the form of a narrow strip directed parallel to the location of the strokes and passing under a wide space bar code. 1 - before heat treatment; 2 - after heat treatment.

7. Scheme of a heat-sensitive film sample sealed with a product bar code with a "watermark" in the form of a wide strip, parallel to the location of the strokes. 1- before heat treatment; 2 - after heat treatment.

Fig. 8. Scheme of a heat-shrinkable film sealed with a product bar code with a “watermark” that is not capable of shrinkage in the form of a narrow strip directed parallel to the location of the strokes. 1 - the bar code is not read by the scanner before heat treatment; 2 - the bar code after heat treatment is read by the scanner.

Fig.9. Flexible packaging scheme (1) with a printed product bar code from a heat-sensitive film with a “watermark” in the form of a narrow strip (3), parallel to the location of the strokes.

The material may have the following chemical composition, shape, physico-mechanical properties and applications.

As a thermoplastic, plasticized polyvinyl chloride (PVC plastic), polypropylene, low density polyethylene, high density polyethylene, fluorine-containing polyolefins, polyamide, polyethylene terephthalate are used. Films are obtained by extrusion of a melt through a slotted or annular die with cooling, orientation drawing and thermal fixation of the structure to give the films heat-shrink properties. Local areas forming a “watermark” in the material are formed under the influence of concentrated energy flows before or after printing an image that hides the watermark before heat treatment and helps to detect it after it. Local areas forming a “watermark” in the material do not significantly differ from the rest of the film in color, transparency, thickness and roughness and therefore are almost indistinguishable to the naked eye. The areas that form a “watermark” in the material after heat treatment can differ from the rest of the film in color, transparency, thickness and roughness and are clearly distinguishable to the naked eye and “to the touch”. A view of a sample of a heat-sensitive polyvinyl chloride film with a “watermark” in the shape of a cross and a contrasting line pattern printed on it in the form of parallel lines after heat treatment is shown in FIG. 1 and FIG. 2 at different magnifications. It can be seen that the “watermark” is clearly distinguished due to the mismatch of the directions of the lines of the printed pattern in the common areas of the film and the sections of the film forming the “watermark”. The width of the lines of the printed pattern in the areas of the film forming the "watermark" may be more or less than the width of the lines in the common areas of the film and, accordingly, more or less rough, more or less transparent.

The dependence of the relative deformation during shrinkage of the material on temperature (Fig. 2) has an S-shape with a characteristic (average) temperature of reduction of linear dimensions, depending on the type of thermoplastic. For PVC, it is 70 ± 5 ° C, for polypropylene - 80 ÷ 5 ° C, for low-density polyethylene - 35 ± 5 ° C, for polyethylene terephthalate - 115 ± 15 ° C, depending on the average molecular weight of the thermoplastic, orientational drawing conditions and heat fixing structures.

The thermosensitive polymer material can be used for packaging production by various methods and sealed in various ways used in printing. It is proposed to use material for printing labels, control marks, labels or packaging, requiring constant cooling of products, or containers for food that is once heated in a microwave oven. In the latter case, the reduction temperature of linear dimensions, depending on the thermophysical properties of the thermoplastic, determines the scope and technique for detecting violations of the rules for using packaged products. To verify the authenticity of control marks, tags and labels manufactured using the proposed material, it is necessary to provide in their designs the possibility of separating part of the material containing the “watermark” for heating in the free state or under conditions that allow reducing the overall dimensions of the part of the material containing "watermark".

A specific example of the use of the proposed material to protect consumer goods from counterfeiting is the use of a film containing a “watermark” in the form of a longitudinal strip in packaging production.

Soft polymer containers can be made from the proposed polymeric material for any product, the falsification of which is not difficult, is economically profitable and therefore is carried out by “pirates” in bulk quantities. Counterfeiting harms developers, manufacturers, and consumers. The image is printed on the protected packaging (Fig. 9) from the proposed polymer material (1) in such a way that at least one stroke (2) is in the zone of abnormal shrinkage (3), i.e. was printed on top of the “watermark” in the form of a narrow strip. Authentication can be carried out by the consumer or the controller after emptying the container if it is not possible to heat it protected to a shrink temperature. The use of direct printing of the verification barcode on flexible packaging is advisable, for example, on valuable deep-frozen foods that must not be thawed or warmed to 20 ± 2 ° C before use.

Information confirming the possibility of carrying out the invention

Example 1. The thermosensitive polymer packaging material for food that is heated once in a microwave oven has a one-sided printed pattern — regularly alternating stripes of dark color with gaps of equal width. The demo sample under study in Example 1 is a heat-shrinkable roll of polyvinyl chloride film with a maximum overall (overall) heat shrink in the direction across the roll of 60%, in the direction along the roll of 6%, i.e. has a Poisson's ratio of 0.1 in width shrinkage. The film has narrow and long sections that form “watermarks” in the form of a repeating cross that is not visible to the naked eye on the film. The lines forming the cross are located at an angle of 45 degrees to the stripes of the printed pattern. The line width is 2 mm, the local shrinkage of the polyvinyl chloride film at the location of the watermark lines is not more than 10%. After heat treatment in hot water at 85 ° C and overall (overall) shrinkage of the film under these conditions, about 45% on it in reflected light and “in the light”, “watermarks” in the form of a repeating cross are clearly visible (Fig. 1).

If the film is used as a packaging for food, once heated in a microwave oven, the appearance of "watermarks" on the packaging will indicate to the consumer that this is an attempt to reheat and the product may be spoiled.

Example 2. The heat-sensitive polymeric material for printing according to example 1, but intended for the manufacture of the top layer of a multilayer label, partially detached from the substrate by the principle of “peel and read”. The material has a printed pattern according to example 1, on the outer or inner side of the label element partially detached from the substrate - regularly alternating stripes of dark color with gaps of equal width. To verify the authenticity of the label, packaging and product as a whole, it is necessary to bend and heat up the label element with a “watermark” to 70-80 ° C. The appearance of a disturbed printed pattern (FIG. 1 and FIG. 2) is a sign of genuine packaging, which can be written on this side of the label.

Example 3. Thermosensitive polymeric material for printing from polyvinyl chloride, intended for the manufacture of a single-layer self-adhesive film label with an adhesive layer for temporary fixation. The film during shrinkage in length has no shrinkage in width. The film has narrow and extended sections that form “watermarks” in the form of stripes that are not visible to the naked eye on the film. The label has a one-sided printed drawing - a bar code. The stripes forming the “watermarks” are directed at an angle to the strokes of the code and intersect part of its strokes and spaces. After removing the label from the container and its heat treatment in hot water at 70 ° C and above, "watermarks" are clearly visible on it (in it) in reflected light and "in the light" (Fig. 5).

Example 4. A heat-sensitive polymer material for printing from polyvinyl chloride, intended for the manufacture of a single-layer self-adhesive film label with an adhesive layer for temporary fixation according to example 3. The film has narrow and extended sections that form a "watermark" in the form of stripes that are not visible to the naked eye on film. The label has a one-sided printed drawing - a bar code. The stripes that form the “watermarks” are parallel to the strokes of the code and break one space or some part of its strokes and spaces. After removing the label from the container and its heat treatment in hot water at 70 ° C and above, “watermarks” appear on it, which allow using the scanner to read the information contained in the bar code (Fig. 6), or, conversely, to note the loss of this information (Fig.7 and 8), which is a sign of genuine packaging.

Claims (4)

1. Heat-sensitive polymeric material for printing, which is a heat-shrink film made of thermoplastic, characterized in that it contains areas with a modified structure and local shrinkage, different from the shrinkage of the entire film, which are not visible to the naked eye, but appear after applying a bar-printed image and heat treatment, as a section that differs from the rest of the material in transparency, the direction of the lines of the printed pattern and / or stands out with a microrelief of the surface. 2. The thermosensitive polymeric material for printing according to claim 1, characterized in that it contains sections with a modified structure and local shrinkage, different from the rest of the material, in the form of parallel stripes. 3. The heat-sensitive polymer material for printing according to claim 1, characterized in that it contains areas with a modified structure and local shrinkage in the form of intersecting strips. 4. The thermosensitive polymeric material for printing according to claim 1, characterized in that plasticized polyvinyl chloride, polypropylene, low density polyethylene, high density polyethylene, fluorine-containing polyolefins, polyamide, polyethylene terephthalate are used as a thermoplastic for its manufacture.

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