JPS61261093A - Method of marking plastic material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for marking plastic materials by applying a dye to the plastic material using a heat transfer medium.

Marks that are clearly readable and resistant to handling and whose composition and dimensions can be changed as the case may be are used for measurements, UR clauses, switches and service.
sing) equipment is often required. This applies in particular to the keys of input devices such as typewriters.

Transfer printing is known in which a paper substrate or "carrier" on which a dye is provided is compressed against a plastic material using a hot pressure stamp with slight application of pressure so that the dye is transferred onto the surface. be done.

The disadvantages of this method are that it requires specific stamps for each symbol, so it is inflexible in terms of graphics and is expensive for small quantities of products. Also, it is difficult to maintain temperature using such stamps,
These variabilities, in turn, can adversely affect coverage and surface properties of plastic materials.

Methods for marking plastic products using laser light are also known, in which the laser light is guided according to the mark.

A disadvantage of this method is that the energetic action of the laser beam leads to irreversible reactions in plastic materials, which are generally accompanied by considerable discoloration. The discoloration is adjustable to a limited extent, in other words only a light image on a dark background or only a dark image on a light background.

It is an object of the present invention to create a well-defined, friction-resistant symbol that can be easily produced by drafting or electronic adjustment on any background in the desired color and size and economically without damaging the plastic material. The objective is to find a method for marking plastic materials that is both practical and flexible.

This purpose is to diffuse at least one sublimation dye according to the invention into the surface of the plastics material via the gas phase and as a heat transfer medium capable of directing it according to the schematic symbol.
This is achieved by heating the seeds at each point with a laser beam.

Surprisingly, sublimation dyes can be diffused into the surface of plastic materials, which are then applied according to the desired sign, by means of a difference in partial pressure, with virtually no discoloration despite a change in phase. is heated by short-wave irradiation, particularly by laser beams, to a depth sufficient to produce a well-defined, friction-resistant, clearly readable colored symbol, where the color is indicative of significance (e.g. bright red) and It has been found that it can be selected as desired according to the background. Another advantage of the method according to the invention is its flexibility, since the material is not damaged due to the short, directed, uniform irradiation and non-contact energy transfer, and the laser beam can be adjusted by guidelines (drafting) or by EDV programs. It is in.

too ~1500nm, especially 1000~150Onm
It has been proven that a laser beam with a wavelength λ of , is suitable for color printing. 0.2~O, a second/mm2
．． Especially 0.5-0.7 seconds/mm2. When using an operating time of
4-150J/cm2. It is. 0.05~0.1mm
with a focal diameter between . Nd-YAG solid phase laser (
current intensity of 10-25 A and 5-50 mm at a repetition frequency of 0.5-15 KHz using input = t, o6JLm)
Advantageous results are obtained using speeds of 5 to 15 mm/sec, especially 5 to 15 mm/sec. The amount of diffusion depends on the current intensity time mode number due to speed.

The softening temperature of the plastics material must be at least 30° C. higher than the sublimation temperature of the dye.

A particular embodiment of the method involves diffusing a sublimation dye that is deposited directly onto a surface.

By applying the dye to the surface by flowing, spraying, painting or printing, each symbol can be transmitted using a laser beam according to a predetermined step.

Undiffused dye residue is then removed.

In another embodiment of the method, a sublimated dye on a substrate is directed onto the surface of a plastics material.

A substrate, which can be made of paper, textile or film, is used to guide the sublimation dye to the point where the laser beam strikes. A device with an intermittently moving belt that can be unwound from a spool before use and unwound onto the next spool after marking is advantageous for this purpose.

In an advantageous embodiment of the method, the path opposite to the direction of propagation of the laser beam is shielded from the gaseous dye.

The gas phase of the sublimation dye can only be moved towards the plastics material to be marked by means of a gas-permeable layer which can simultaneously act as a substrate.

In a useful embodiment of the method, the sublimation dye is delivered via the substrate directly onto the plastic material.

By means of a mechanical lamp device or by applying a vacuum in the case of gas-tight substrates, a very short path for the diffusion of the dye is created.

In a preferred embodiment of the method, the substrate is compressed against the plastic material by a transparent device through which the laser beam passes substantially unimpeded.

For example, transparent PU objects undergo virtually no irradiation changes at wavelengths in the range 1000-1500 nm, where e.g. and the fluid can act, for example, as an energy carrier for preheating the dye, resulting in a relatively rapid conversion to the gas phase.

In another embodiment of the method, a sublimated dye in the gas phase is guided at high speed while being simultaneously compressed onto the area struck by the laser beam.

By feeding the dye in the gaseous phase at high speed and under compression through the funnel-shaped structure of the gas conduit, a powerful effect can be obtained such that the excess dye is immediately and repeatedly suctioned off and recycled.

In one embodiment of the method, sublimation dyes are diffused into thermoplastically processable, flowable, or compressible plastic materials.

The method is particularly suitable for example for acrylonitrile butadiene styrene (Novodur), cellulose acetate (Cell).
idor■), polyamides (Durethan■),
Polycarbonate (Makrolon■), polyesters, and polybutylene terephthalate (P o c
a n ■), or mixtures of said polymers, and preferably PC/ABS blends (Bayblend ■), PC
/PBTP formulations (Makroblend ■) and materials such as polyurethane and silicone rubbers. In particular, it can process thermoplastic materials.

Heat diffusion dyes and sublimation dyes (RESIRENT■)
are suitable as dyes.

Example 1 A transfer printing paper with a blue color printed on the surface with Resiren T was transferred to a Novodur (N
It was placed on a typewriter key made of PH-AT (ABS). A focused laser beam (input = 1.06 gm) was generated and guided onto the paper (annular shape). After removing the paper, the dye had penetrated into the plastic material in the irradiated area. .

Example 2 A polyester film (HO5taphan REO, 050 mm) printed in red on the surface with Resylene T
) is placed under the laser optics of the Nd-YAG solid phase laser using a Pocan B1505 (
It was placed on a switch cover made of PBTP). A focused laser beam (λ=1.06 lumens) was generated and directed onto the film (annular shape). After removing the film, the dye had penetrated into the plastic material in the irradiated areas.

Polyester film (Hostaphan REO, 050m
m) is placed under the laser optics of the Nd-YAG solid phase laser.
It was placed on a plastic housing made of BKV30. Focused laser beam (input = 1.06pm
) was generated and directed onto the film (annular shape). After removing the film, the dye had penetrated into the plastic material in the irradiated areas.

Claims (1)

Claims: 1. A method for marking plastic materials by applying a dye onto the plastic material by means of a heat transfer medium, comprising: diffusing a sublimation dye into the surface of the plastic material through a gas phase; A method characterized in that it is heated at each point by at least one laser beam as a heat transfer medium which can be directed according to a graphical symbol. 2. Process according to claim 1, characterized in that the sublimation dye is applied flat directly onto the surface and diffused into it. 3. Process according to claim 2, characterized in that the sublimation dye on the substrate is introduced onto the surface of the plastics material. 4. The method according to claim 2 or 3, characterized in that the path opposite to the propagation direction of the laser beam is shielded from the gaseous dye. 5. Process according to claims 3-4, characterized in that the sublimation dye is compressed directly onto the plastic material by means of a substrate. 6. Claims 3 to 5, characterized in that the substrate is compressed against the plastic material by a transparent device through which the laser beam passes substantially unhindered.
The method described in section. 7. A method according to claim 1, characterized in that the sublimation dye in the vapor phase is directed onto the part where the laser beam impinges at high speed while compressing the surface of the plastics material at the same time. 8. Process according to claims 1 to 7, characterized in that the sublimation dye is diffused into a thermoplastically processable, flowable or compressible plastics material.