KR101313646B1 - Method for laser-marking on surface of resin article - Google Patents

Abstract

PURPOSE: A method for marking on the surface of a resin product with lasers is provided to enable laser marking proper to characteristics of a resin product and to improve the reliability of a resin product by clearly marking a laser label. CONSTITUTION: A method for marking on the surface of a resin product with lasers includes the following steps of: selecting a target synthetic resin; determining the thermal transformation characteristics of the selected synthetic resin; determining frequencies and a marking speed according to the determined thermal transformation characteristics; setting a focal distance in respect to the set marking speed; and marking by setting an output value. [Reference numerals] (P11) Select a resin; (P12) Determine thermal transformation characteristics; (P13) Determine frequencies and a marking speed; (P14) Set a focal distance; (P15) Determine output and perform marking

Description

Method for Laser-Marking on Surface of Resin Article

The present invention relates to a laser marking method on the surface of a resin product, and more particularly, to a laser marking method on a surface of a bark product in which information is laser-engraved on the surface of a resin product such as polyethylene terephthalate or polystyrene.

Laser marking can be used to imprint information relating to the product on a metal surface, such as, for example, the date of manufacture or information about the manufacturer. However, resins or other thermally modified materials have been recognized to be difficult to laser marking due to bubbles generated when the surface is irradiated with lasers, white markings, or unwanted changes around the markings. However, the necessity of laser marking of resin products has been continuously raised in the related industry in order to use resin products in various fields and to prevent long-term storage and deformation of product labels.

Prior art related to laser marking of a resin product surface is disclosed in Korean Patent Laid-Open Publication No. 2004-0018670, 'A thermoplastic marking composition capable of laser marking'. The prior art is 100 parts by weight of acrylic resin, 0.01 to 5 parts by weight of black dye or pigment, 0.01 to 10 parts by weight of silicate compound, 0.1 ~ high molecular weight surfactant in order to solve the problems caused when laser marking the resin surface 5 parts by weight and 0.1 to 20 parts by weight of a white inorganic filler, the weight ratio of the black dye or pigment and the white inorganic filler is disclosed for a laser marking capable thermoplastic resin composition, characterized in that 0.1 to 50.

Another prior art related to laser marking of resin products is Patent Publication No. 2010-0062643, 'Thermal resin composition for laser marking'. The prior art is 10 to 20 parts by weight of the conjugated diene rubber latex, 40 to 70 parts by weight of (meth) acrylic acid alkyl ester compound, 10 to 40 parts by weight of aromatic vinyl compound, and vinyl cyan compound 1 based on 100 parts by weight of the total copolymer. Graft copolymer prepared by graft copolymer to 20 parts by weight; An acrylic copolymer (B) comprising a copolymer of a mixture of an acrylic monomer, an aromatic vinyl monomer, an acrylonitrile monomer and an acid anhydride with a weight ratio of 55 to 80: 10 to 30: 4 to 15;

Thermoplastic elastomers (C); And it discloses a thermoplastic resin composition for laser marking comprising a colorant comprising at least one of pigments and dyes.

Another prior art related to laser marking of resins is Patent Publication No. 2008-0041184, 'Polyamide Resin Compositions for Laser Marking and Polyamide Resin Molded with Laser Marking.' The prior art contains 0.1 to 100 parts by weight of a halogen-containing organic compound and / or antimony compound with respect to 100 parts by weight of polyamide resin, and when the laser marking is carried out with a polyamide resin molded body, It discloses the polyamide resin composition for laser markings which is darker than the color tone of the surface of the polyamide resin molded object of this invention.

All the above prior arts are characterized in that laser marking is possible on the basis of deformation of the resin composition itself. However, it is difficult to change the material properties of the product for laser marking in the industrial field, and there is a problem that it may affect other properties.

The present invention is to solve the problems of the prior art has the following object.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser marking method on a surface of a resin product that enables laser marking to suit the characteristics of the resin product.

According to a preferred embodiment of the present invention, a laser marking method comprises the steps of selecting a synthetic resin to be marked; Determining heat deformation characteristics of the selected synthetic resin; Determining a frequency and a marking speed according to the heat deformation characteristic; Setting a focal length for a predetermined marking speed; And setting the output value to perform marking.

According to another suitable embodiment of the present invention, the frequency is 25 to 1000 kHz, the marking speed is 100 to 5,000 mm / sec and the focal length is 100 to 300 mm.

According to another suitable embodiment of the present invention, the resin product is polyethylene terephthalate, polystyrene, high density polyethylene or low density polyethylene.

The laser marking method according to the present invention has the advantage of enabling the marking that maintains the original characteristics of the resin product by allowing laser marking without adding a separate composition to the resin. In addition, the laser marking method according to the present invention can improve the reliability of the product by enabling the information display of the resin product that is difficult to remove without being deformed by enabling the clear laser label engraving on the surface of the resin product. Has the advantage of being able to.

1 illustrates an embodiment of a laser marking method according to the present invention.
2 illustrates an embodiment to which a laser marking method according to the present invention is applied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the accompanying drawings, but the present invention is not limited thereto. In the following description, components having the same reference numerals in different drawings have similar functions, so that they will not be described repeatedly unless necessary for an understanding of the invention, and the known components will be briefly described or omitted. However, It should not be understood as being excluded from the embodiment of Fig.

1 illustrates an embodiment of a laser marking method according to the present invention.

1, the laser marking method according to the present invention comprises the steps of selecting a synthetic resin to be the target of marking (P11); Determining a thermal deformation characteristic of the selected synthetic resin (P12); Determining a frequency and a marking speed according to the thermal deformation characteristic (P13); Setting a focal length for a predetermined marking speed (P14); And setting the output value to perform marking.

The marking method according to the invention can be done using various types of lasers. The laser is, for example, a fiber laser using an optical fiber resonator, a carbon dioxide laser using a mixture of nitrogen and helium, a solid laser using a Yttrium Aluminum Garnet (YAG) crystal containing Nd ions, and a Diodes (DPSS). Pumped Solid State laser or ultraviolet laser, and the present invention is not limited by the type of laser. In the method according to the present invention, the frequency, focal length and marking speed applied according to the type of synthetic resin need to be adjusted. Therefore, the resin to be marked first must be selected for the adjustment of such factors (P11). The resin can be such as but not limited to polyethylene terephthalate (PET), polystyrene (PS), high density polyethylene (HDPE) or low density polyethylene (LDPE). However, the marking method according to the present invention may be applied to both a thermosetting resin or a thermoplastic resin, but preferably to a thermoplastic resin.

Once the type of synthetic resin is determined, the heat deformation properties of the resin should be determined (P12). Thermal deformation properties can be such as, for example, melting point, softening point, density, thermal conductivity, reflectance and transmittance according to frequency. The thermal deformation characteristics are due to the inherent physical properties of the resin, and the marking factors such as the frequency, focal length and marking speed described above may be determined according to the thermal deformation characteristics. According to the invention the marking factor can be frequency, focal length and marking speed and the resin factor can be density, thermal conductivity, reflectance and frequency. By the correlation of each resin factor and each marking factor, whether marking is possible and the range of marking factors can be determined. For example, the frequency corresponding to one of the marking factors may be determined for the softening point corresponding to one of the resin factors. The time at which the softening point is reached for a specific frequency by forming a focal point at a certain distance can be measured. After that, the allowable frequency range may be determined based on the time that is reached, and the marking factor value for each section may be determined by dividing the predetermined frequency range. In this way, the value of the marking factor is determined for each resin factor, and the frequency and the marking speed can be determined based on the value of the marking factor (P13). The frequency and the marking speed are determined first because the influence on whether the marking can be greatly affected by the frequency and the marking speed. If the frequency and the marking speed are determined (P13), the focal length may be determined (P14). The focal length can be determined by the resin factor described above, but on the other hand it can be determined by the marking interval of the resin surface to be marked. For example, the marking should take into account the depth or marking width that will be marked on the surface. The focal length has to be taken into account after the frequency and marking speed have been determined since this additional factor must be taken into account. Depth and marking width may vary depending on the type or performance of the laser, for example. And the determination of the focal length can be determined in consideration of the resin factor and the like.

The marking factor determined according to the resin factor may vary depending on the type of resin and the type of laser, but appears to be in the following ranges for the presented resin.

Marking Factor Values for PET, PS, HDPE, and LDPE

Frequency: 25 to 1000 kHz

Marking Speed: 100 mm / sec to 5,0000 mm / sec

Focal Length: 100 to 300 mm

The marking factor can be appropriately adjusted according to the type of resin. The marking can be engraved, for example, on the lid of a transparent or opaque bottled water or beverage bottle, a yogurt bottle or a resin product and can be continuously engraved on a large volume of products in an automated manner.

Marking factors can be determined in the same or similar manner for other types of resins. Once the marking factor is determined (P13 and P14), the output value of the laser may be determined. For example, the output value can be 10-30 watts and can be adjusted appropriately according to the marking speed. For example, a faster marking speed can result in a larger output value and a smaller marking speed can result in a lower output value. The output value can be appropriately adjusted according to the type or marking speed of the laser and the present invention is not limited thereto.

Hereinafter, an embodiment of marking by a marking factor according to the present invention will be described.

2, the laser marker 20 for applying the method according to the present invention includes a generator 21 for generating a laser beam, an expander 25 for adjusting the focusing of the beam generated by the generator 21, The focus of the beam transmitted from the X- and Y-direction mirrors L1 and L2 and the X- and Y-direction mirrors L1 and L2 reflecting the beam transmitted from the expander 25 is in the frame F. F-theta lens L3 to be positioned, the control device 22 and the detection module 16 for checking the processing state of the workpiece (W) may be included.

The generator 2 may be, for example, a fiber laser, a carbon dioxide laser, a solid laser, a diode pumped solid state (DPSS) laser or an ultraviolet laser as described above. The workpiece W may also be such as polyethylene terephthalate (PET), polystyrene (PS), high density polyethylene (HDPE) or low density polyethylene (LDPE). However, when the workpiece W becomes polyethylene terephthalate, it is advantageous to be a carbon dioxide laser, and when the workpiece becomes polystyrene, the fiber laser is advantageous. However, any laser can be used for each resin and the laser is not limited to the resin type.

In the generator 21, a value for a marking factor according to the type of resin is stored, and if necessary, a control device 22 having a program for determining the marking factor when the resin factor for the resin is input may be installed. The control device 21 can control the beam generated by the laser in consideration of the marking factor according to the resin factor.

The laser generated by the generator 21 may be controlled by the control device 22 and transferred to the expander 25. The expander 25 may be formed of concave lenses and convex lenses spaced apart by a predetermined distance in order to adjust the cross-sectional area of the laser beam. The laser whose focus is adjusted while passing through the expander 25 is determined by the scanning direction at the X-direction mirror L1 and the Y-direction mirror L2, and then passes through the F-theta lens L3 to the frame F. The focus is formed on the surface of the fixed fixed work piece W. The focal point is formed on the surface of the work material W, which can be imprinted in a desired shape, and the isolator 23 has the laser light reflected from the surface of the work material W again. Or it will block the flow into the laser oscillator. The laser engraved condition can be detected by the detection module 26. The detection module 26 may include, for example, a device such as a temperature sensor or a camera, and may transmit the state of the workpiece W to the control device 22 or another device to determine whether the imprint is normal. have. The temperature sensor is installed because it can be determined whether or not the normal stamping by the temperature of the workpiece (W) in the case of the resin. On the other hand, the detection module 26 may include a distance measuring sensor.

In the laser marking process, the work material W may be transported by a transfer device (not shown) included in the frame F to be fixed at a predetermined position. The workpiece W is generally on a uniform X-Y plane, but height differences can occur for a variety of reasons. In detail, the distance between the F-theta lens L3 and the surface of the work material W may be different from the predetermined distance, and thus the focus may not be accurately formed on the surface of the work material W. Such occurrence of height difference and deviation of focus formation can degrade the quality of laser marking.

According to the present invention, the detection module 26 may be provided with a distance measuring device for measuring in real time the distance between the F-theta lens L3 and the surface of the workpiece W. The distance measuring device may be, for example, a photo sensor, a laser sensor, or an ultrasonic proximity angle sensor composed of a light emitting element and a light receiving element, but is not limited thereto. When the photo sensor is used as a distance measuring device, the slope of the surface together with the distance may be measured as necessary.

The value measured in the distance measuring device may be predetermined and stored, for example, according to a position or coordinate in the memory device. The distance measuring device may be moved by an independent drive device (not shown) or in conjunction with the position of the focal point formed at the surface of the workpiece W. FIG. For example, the distance measuring device may measure the distance at a point between the position of the current focus and the position at which the next focus is to be formed. When the value measured by the distance measuring device is stored in advance, when the laser marking device is moved to the position measured on the surface of the workpiece W, the controller 22 adjusts the focus according to the measured distance accordingly. On the other hand, when the distance is measured before the focus of the laser is moved, the focus may be adjusted by the controller 22 simultaneously with the movement of the laser.

The measured distance may be previously stored in the memory device or measured immediately before the laser focal point is moved and transferred to the control device 22. If the memory device is stored in advance in the memory device, the laser focus is moved to the corresponding position, and the control device 22 retrieves the stored value and adjusts the focus of the laser beam accordingly. When the measurement is performed just before the focus is moved, the marking is finished at the current position, and if the focus needs to be adjusted at the next position, the controller 22 adjusts the focus of the laser beam accordingly.

When focus adjustment is required according to the position of the workpiece W to be imprinted, the control device adjusts the focus position by adjusting the expander 25. The focus adjusting means 24 driven by the motor M may be installed to adjust the focus position.

The detected value in the detection module 26 can be passed to the control device 22 and the marking factor can be adjusted accordingly according to the detection status.

2 is illustrative and the method according to the present invention can be applied to various laser devices.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention . The invention is not limited by these variations and modifications, but is limited only by the claims appended hereto.

P11: Resin Selection P12: Heat Strain Characteristics
P13: Determine frequency and marking speed P14: Set focal length
P15: Output Determination and Marking

Claims (3)

In the method of laser marking the surface of the resin product without a separate process for laser marking the inorganic particles or surface,
Selecting a synthetic resin to be marked;
Determining heat deformation characteristics of the selected synthetic resin and determining whether marking is possible and a range of marking factors;
Determining a frequency and a marking speed according to the heat deformation characteristic;
Setting a focal length for a predetermined marking speed; And
Setting the output value and marking it,
Said frequency is 25 to 1000 kHz, marking speed is 100 to 5,000 mm / sec and focal length is 100 to 300 mm. The method of claim 1, wherein the focal length is monitored in real time by a distance measuring device for measuring the distance between the F-theta lens and the surface of the synthetic resin in real time. The method of claim 1, wherein the synthetic resin is polyethylene terephthalate, polystyrene, high density polyethylene or low density polyethylene.

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