JPH08174263A - Laser marking method - Google Patents

Abstract

PURPOSE: To enable marking on the surface of a molding resin by coating the surface of a resin molding body with a resin powder that contains inorganic particles and irradiating the body with a laser beam in a pattern corresponding to a marking. CONSTITUTION: The surface of a resin molding body 1 is coated with a paint which consists essentially of plastics, synthetic rubber, natural rubber or resin and contains inorganic particles such as carbon black and pigments. The surface of the resin molding body 1 is then irradiated with a laser beam 2. The inorganic particles irradiated with the laser beam 2 are fixed or stabilized on the surface of the resin molding body 1 with the resin powder as a binder. After marking, the surface of the resin molding body 1 is wiped with a cloth or the like. The inorganic particles on the part unirradiated with a laser beam 2 are removed from the surface. The stabilized inorganic particles remain, and the pattern is thereby marked.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of laser marking. More specifically, it is possible to mark patterns, letters, figures or symbols of any shape on the surface of resin moldings, which has been difficult to do in the past, and to broaden the applicability of laser marking. Regarding the method.

[0002]

2. Description of the Related Art Laser marking technology has been used in various fields since marking (engraving) patterns, letters, figures or symbols of any shape or their combination can be performed easily at high speed by controlling a computer. It was For example, laser marking is suitable for giving a bar code symbol to control a large number of mass-produced product groups. With such bar code information, it becomes possible to add individual information data for each of a number of products and to accurately identify individual product (group) lots based on the data. It plays an important role in comprehensively controlling physical distribution such as product management and quality control, which effectively controls complicated online shopping routes. 1 laser marking
This is because, for each product, different information can be individually given by a command from a computer, and corresponding different barcodes can be marked on the product.

Further, by laser marking, characters can be marked on the product instead of symbols such as bar codes. Even in this case, it is possible to perform management by a computer, and like the barcode, it is preferably used for POS management of products / commodities.

A laser marker for laser marking which is usually used is a solid laser represented by a YAG laser which is relatively inexpensive and can obtain a high output, and the laser used for irradiation is 400 nm.
A material capable of oscillating light in the visible light range to the near infrared light range of 2,000 nm or less is used. The output of this laser is usually about 30 W at maximum.

Further, the laser marker can be taken out as pulsed laser light in order to increase the energy amount of the irradiation laser light by an oscillator equipped with a resonance system with a Q switch. Furthermore, the laser energy is increased on the irradiation surface by condensing with a lens. As a result, the irradiation energy density on the irradiation surface can be increased to 1 × 10 ⁷ J / cm ² or more. The Q switch frequency that is normally used is 1 kHz or higher, and there is no problem if it has a frequency of 20 kHz or higher.

Further, a long focus type fθ lens is used as the laser, and a laser capable of irradiating a high energy laser beam in a wide area is preferably used by having a focal length as long as possible. . The standard focal length is 10 cm or more and 20 cm or less. For example, when the focal length is 15 cm, a range of about 5 cm in radius on a flat processed surface can suppress the decrease from the laser energy value at the central processing position to 11% or less, and is a markable range.

Further, regarding the control of the laser irradiation position, by changing the irradiation position by controlling the direction of the lens by the controller, the position of the irradiation object is changed by adopting the galvanometer mirror system. The marking can be performed without the need to do so.

However, according to the studies made by the present inventors, the marking characteristics by the laser utilizing the visible light and the near-infrared light are greatly limited in the processing characteristics due to the physical properties of the laser irradiation surface. That is, it was found that marking of metal, ceramic, etc. can be easily performed by irradiation with a high-energy laser, whereas marking cannot be easily performed on the surface of resin, etc.

That is, in general, in the processing of a solid surface using a pulsed laser beam having a high energy density, when the laser beam to be irradiated is irradiated onto the solid,
Part of the energy of laser light is absorbed near the surface of the solid, cracking the molecular bonds inside the solid and giving enough energy to separate the molecules from each other, causing the laser ablation phenomenon to scatter at a stretch. It is done by doing.

Therefore, it is preferable that the size of the molecule itself is as small as possible in order that the bound molecules are more easily separated by the irradiation energy of the laser and scattered in the gas phase. From this point, marking of metal, ceramic, etc. by irradiation with a high energy laser is easy.

However, plastics and natural rubber
(Or synthetic rubber) or a paint surface, the structure of the molecule itself is large because at least the surface is composed of polymer, and it is probably local and extremely short like laser irradiation. The inventors have found that depending on the energy applied in time, it is almost impossible for molecules to be removed from the solid surface by evaporation or scattering.

As described above, a solid formed of a substance having a small molecular weight such as metal or ceramic is
The solid surface can be easily marked by irradiation with a laser using visible light or near-infrared light, while it is composed of a polymer such as a coated surface such as plastics, rubber or paint. Laser marking on solid surfaces has been difficult.

Incidentally, in order to break the molecular bonds in the polymer, it is necessary to use a high absorption coefficient in solids, such as in the ultraviolet region.
It can also be performed by using excimer laser light having a short wavelength of 00 nm or less. Therefore, it is considered possible to perform laser marking using an excimer laser. However, a device capable of irradiating a high-power laser, which is capable of marking on a solid surface, is extremely expensive, and the time and effort required for maintenance are far greater than when a solid laser is used. However, it is not practical at all.

[0014]

DISCLOSURE OF THE INVENTION The present invention provides a method of laser marking a pattern, character, figure or symbol of an arbitrary shape by irradiating a high energy pulsed laser, which is difficult to mark with a laser in the past. It is intended to provide a method for making it possible to perform laser marking by applying a resin powder containing an inorganic substance onto the solid surface of a resin molding such as plastics or rubber which has been used.

[0015]

Means for Solving the Problems That is, the present invention is a method for marking a pattern, character, figure or symbol of an arbitrary shape on the surface of a resin molded body by irradiation with a high energy pulse laser, containing inorganic particles. By applying a resin powder to the surface of the resin molded body, by irradiating the pattern corresponding to the marking with a laser, a laser marking method for forming the marking, or at least the surface of the resin molded body is plastics, It is a laser marking method comprising a synthetic rubber, a natural rubber or a coating material containing a resin as a main component, or the inorganic particles are a laser marking method comprising carbon black or a pigment, and the inorganic particles have a color. It is a laser marking method.

In the present invention, the term "resin molding" refers to a plastic or rubber which is given a certain shape, or a coating containing a synthetic or natural resin as a main component. It does not have to be, but may be made of metal, ceramic, leather or glass, mineral, pottery, porcelain, etc.), in short, at least its surface layer is made of resin. Say something.

In the present invention, the resin forming the resin molded body is not particularly limited, but for example, preferred examples include polyethylene, polystyrene,
Polypropylene, polycarbonate, polyarylate,
Plastics such as polyamide, polyimide, acrylic resin, vinyl chloride resin, phenol resin, epoxy resin, urethane resin, ionomer resin, fluororesin, bakelite, celluloid, natural or artificial leather, natural rubber, and plastics Polyisoprene rubber, poly-butadiene-styrene rubber, poly-butadiene-nitrile rubber, polychloroprene rubber, polyisoprene rubber, polyethylene / propylene rubber, polysilicone rubber, polyacrylic rubber, fluorine-based synthetic materials Rubber is suitable.

In addition, metals, ceramics, glass, minerals,
As a paint to be applied to the surface of a molded body made of wood, bamboo, leather, porcelain, pottery, or the like, or the surface of a molded body made of the above resin or rubber, vinyl chloride resin, phenol resin, epoxy resin, alkyd resin, A paint mainly composed of a synthetic resin such as a polyurethane resin or a paint mainly composed of a natural resin such as lacquer can be used.

The term "molded product" as used in the present invention means a plate-like, spherical,
Of course, simple forms such as cylinders, spindles, cones, triangular pyramids, cuboids, cubes, polyhedra, films, sheets, and fibrous shapes,
It may have an irregular curved surface. Further, the shape of the surface of the molded body may be smooth or rough, and further, embosses, depressions, dimples, irregularities, etc. may be formed.

The present invention is a technique for suitably carrying out laser marking on the surface of such a resin molding using a resin powder containing inorganic particles. Here, as the inorganic particles, carbon black particles having black color and inorganic pigment particles having white color, black color or other colors are preferable.
Such inorganic pigments include lead white, zinc white, lithopone, titanium white, aureoline, cobalt green, cerulean blue, cobalt blue, cobalt violet, cadmium yellow, cadmium red, ultramarine,
Red, zinc, barium, cobalt, such as red iron oxide and ultramarine
Oxides of chromium, cadmium, iron, magnesium, etc.,
The representative ones are sulfides, carbonates, cyanates, sulfates and phosphates, but not limited to these unless they are decomposed / disappeared by laser irradiation.

As the resin powder containing such inorganic particles, styrene-based, acrylic-based, polyester-based, polyamide-based, etc. are preferably used. However, as long as they can be fixed to the surface of the molded product by laser irradiation, It is not limited to these. The size of the resin powder is not particularly limited, but the particle size is 1 μm or more and 100 μm.
The following is suitable, and more preferably 5μ
It is about m or more and 20 μm or less.

The ratio of the inorganic particles mixed in the resin powder is not particularly limited, but it is preferably about 1% to 20%. The particle size of the inorganic particles is not particularly limited, but is 1 μm or more and 100 μm or more.
A material having a size of about μm or less is suitable, and more preferably,
It is about 5 μm or more and 20 μm or less.

As the resin powder containing inorganic particles, the above-mentioned resin powder and inorganic particles may be arbitrarily mixed and prepared, or a commercially available toner for a so-called PPC copying machine is used as it is. You can also do it. In that case,
As the toner, not only a toner containing carbon black particles for monochrome, but also a color toner for color copying can be preferably used.

Here, to explain the attached drawings,
FIG. 1 is a schematic diagram of an apparatus for performing laser marking used for the present invention. Here, 1 is a resin molded body, 2 is laser light, 31 is a galvanometer scanner (Y direction), 32 is also a galvanometer scanner (X direction), 33 is a laser rod, 34 is a Q switch element, 35 is a shutter, 36 is a rear mirror, 37 is a front mirror, 38 is an fθ lens, 41 is a controller, and 42 is a computer. The laser light 2 emitted is 400
A solid-state laser capable of oscillating light in the visible light range to the near-infrared light range, which is in the range of nm to 2000 nm, is used. If the output of this laser is 10 W, it is enough.
A laser output of 5W is also available.

As the laser equipment itself, conventionally known equipment can be used as it is. Regarding the conditions etc.,
This is as described in the section [Prior Art]. It is essential that the laser to be irradiated can be operated at high speed, and that a CW laser pulsed by a Q switch can be irradiated so that a high output can be obtained. Q-switch frequency for pulsing is 1 kHz
There is no problem as long as it is z or more and has a frequency of 20 kHz or more.

Further, in order to increase the energy amount of the irradiation laser light, the pulse laser by the Q switch is condensed by using a lens as shown in the figure so that it can be taken out as pulsed laser light. As a result, it is preferable that the irradiation energy density on the irradiation surface can be increased to 1 × 10 ⁷ J / cm ² or more. Moreover,
By using the fθ lens so that light can be condensed at a long focal length, it is possible to have a focal length as long as possible. Thus, it is desirable to be able to irradiate high energy laser light over a wider area. The focal length is 10 cm
It is standard that the distance is 20 cm or less. For example, when the focal length is 15 cm, a range of about 5 cm in radius on a flat processed surface can suppress the decrease from the laser energy value at the central processing position to 11% or less, and is a markable range.

Further, regarding the control of the laser irradiation position, by adopting the galvanometer / mirror system 31, 32 which can change the irradiation position by controlling the direction of the lens by the controller, the object to be irradiated can be controlled. Marking can be performed without changing the position.

In the present invention, the resin powder containing the inorganic particles is applied to the surface of the resin molding, and the applied surface is irradiated with a high energy laser, whereby the inorganic particles can be fixed on the irradiated surface. The procedure for applying the resin powder containing the inorganic particles to the surface of the resin molded product will be described.

As a method of applying the resin powder onto the surface of the resin molded body, basically, a resin powder containing inorganic particles may be basically spread thinly on the surface and lightly pressed from above to be held on the surface of the resin molded body. This pressurization may be performed with a roller or the like, or an operation such as rubbing with finger pressure is sufficient. In some cases, in order to improve operability, a solvent capable of dissolving the resin powder or a solvent capable of dispersing the resin powder is added, and this is applied in an emulsion or slurry state, and then dried after application to form a solvent. The coating film may be formed by removing. At that time, a resin binder or a surfactant may be added in order to improve the coating property of the coating film.

The thickness of the resin powder containing inorganic particles to be applied to the surface is not particularly limited, but is usually preferably 0.3 mm or less, more preferably 0.1 mm or less and 0.001 mm or more. . As described above, even if the solid surface of the resin molding has an uneven shape, if the degree of the unevenness is not excessive and is within about 0.3 mm, the present invention is applied. It is quite possible to mark it.

In the present invention, it is considered that by irradiating with a high energy laser in this state, the inorganic particles are fixed or fixed on the surface of the irradiated surface by using the resin powder as a binder. The marking width by the laser is not particularly limited, but is usually 0.1 mm or more and 2.0 mm or less, preferably about 0.3 mm or less.
This is because it is necessary to increase the output of the laser energy densified by the condenser lens as high as possible, and if the marking width is within the above range, the marked part can be clearly confirmed by visual observation. is there. When the marking is not sufficiently fixed in one irradiation, the marking is more completely performed by repeating irradiation several times, if desired.

In the present invention, after marking by the laser irradiation as described above, the surface of the resin molding is wiped with a soft paper, cloth, brush or the like, or is irradiated with the laser so as to be vibrated. Inorganic particles in the non-exposed area are easily removed from the surface, and patterns, letters, figures, etc. consisting of inorganic particles fixed on the laser-irradiated surface
Alternatively, a pattern consisting of symbols is marked. That is, the inorganic particles are fixed only in the portion irradiated with the laser, and the marking shape or pattern can be clearly confirmed by visual inspection.

Any marked pattern, character, figure or symbol obtained according to the present invention is sufficiently strong that it does not easily come off, disappear or become thin even when the marking surface is rubbed. . In addition, it was confirmed that the markings did not disappear even if they were washed with water.

In the present invention, when the resin molding is, for example, a sphere, the range in which laser marking can be performed becomes extremely narrow. In such a case, the resin molding to be irradiated with the laser is installed on a device capable of rotating, and the irradiation distance is arranged so that the output of the laser is kept within, for example, about 10% so that the entire surface of the sphere is It can be marked. Further, also in the case of other forms of resin molding having a curved surface, by using a similar device that appropriately rotates or moves the molded body in a manner similar to a spherical body, it is similarly suitable for a curved surface. Can be marked.

[0035]

【Example】

Example 1 Hereinafter, the present invention will be described based on examples. In the examples, a commercially available golf ball is selected as the resin molded product, and the outer skin (outermost shell surface) of the golf ball is marked with characters using a YAG laser processing machine. .

The outer skin of the golf ball is of a usual type made of polyisoprene rubber, and the surface thereof is coated with polyurethane paint. In this example, the surface color was white and orange. As the resin powder containing inorganic particles, PPC toner used in a copying machine was used. The PPC toner used is a mixture of carbon black and styrene-based powder.

As the laser marker, a laser marker (manufactured by Mitsui Toatsu Chemicals, Inc.) equipped with a YAG laser was used. This laser marker is
It is a CW type that can oscillate a laser beam with a wavelength of 1064 nm, which has a maximum energy of 30 W, and from 1 kHz to 50 kHz by a Q switch.
A pulsed laser can be oscillated. Also, fθ
Using a lens, the working distance that can be marked, that is, the distance from the lower end of the lens to the marking surface is 150
mm. Furthermore, marking speed is from 1 mm / s to 4
It is variable at 00 mm / s.

The position of the marking can be planarly operated in the X and Y directions by a galvanometer system, and an arbitrary shape can be obtained on the irradiation surface by computer control of a galvanometer scanner which operates the directions of the folding mirrors in both X and Y. It is possible to mark patterns, symbols, or characters.

Now, on the surface of the outer surface of the golf ball, PPC
After the toner was applied, it was lightly pressed with a dust-free cloth by finger pressure to keep it from falling even if the application surface was down. At this time, a large amount of PPC toner adhered to the dimples of the golf ball, and thinly adhered to the skin portion other than the dimples.

In this state, the golf ball was placed at a position 150 mm directly below the fθ lens so that the surface of the golf ball on which the PPC toner was applied faced up, and laser irradiation was performed in this state. Laser irradiation conditions and operating conditions are as follows. That is, the energy per pulse of the irradiation laser was 3 × 10 ⁸ J / cm ^2, and the processing width by marking was controlled to be 0.2 mm. Further, the Q switch frequency was set to 5 kHz, and the moving speed of the movable stage was set to 100 mm / s.

The letters of the marking are "MT" which means Mitsui Toatsu Chemical Co., Ltd. so that the total length is within 10 mm.
Three letters "C" were marked. Even when the laser was irradiated once, the three marked characters could be read, but by making the irradiation three times, the marked characters became clearer.

After the laser irradiation, excess toner was similarly wiped off with a dust-free cloth. By this wiping, the toner remaining on the surface of the golf ball could be removed cleanly while leaving the marked characters clear.
The marking obtained was one in which the letters "MTC" were clearly and vividly engraved.

When this marked golf ball was washed with water, the sharpness of the characters did not change at all. Moreover, the marked characters were rubbed with the finger several times, but the sharpness thereof was not changed at all. In addition, 10 times of trial hits were carried out at an indoor simple golf driving range at an ordinary golf club, but the sharpness of the marked characters changed completely in the area other than the area where the golf ball was scratched. There was no In this example, the white golf ball and the orange color golf ball were both examined, but there was no difference in the sharpness of the marking characters in both.

Comparative Example 1 Similar to the case of the example, the comparative example was also examined using a white golf ball and an orange color golf ball. However, in the comparative example, the resin powder containing the inorganic particles was not applied to the outer surface of the golf ball, but laser irradiation was performed as it was.

The laser was used in the same apparatus as in the example, and the operating conditions were almost the same.
However, in this comparative example, it was not possible to carry out marking that could be visually confirmed regardless of the color of the surface of the golf ball. Then, the output of the laser was increased and the examination was conducted under the condition of 5 × 10 ⁸ J / cm ² , but it was not possible to make the marking which could be visually confirmed.

[0046]

EFFECTS OF THE INVENTION The present invention has hitherto been considered to be difficult in a method of marking a pattern, symbol or character of arbitrary shape by irradiation with a high energy pulse laser, by applying a resin powder mixed with inorganic particles. It is possible to mark on the surface of molding resin, and it will open the way to various application areas of laser marking.

[Brief description of drawings]

1 is a schematic diagram of an apparatus for performing laser marking used for the present invention.

[Explanation of symbols]

 1 Molding resin 2 Laser light 31 Galvanometer scanner (Y direction) 32 Galvanometer scanner (X direction) 33 Laser rod 34 Q switch element 35 Shutter 36 Rear mirror 37 Front mirror 38 fθ lens 41 Controller 42 Computer

Claims (4)

[Claims] 1. A method for marking a pattern, a character, a figure or a symbol of an arbitrary shape on a surface of a resin molded body by irradiation with a high energy pulse laser, wherein resin powder containing inorganic particles is applied to the surface of the resin molded body. A laser marking method in which the marking is completed by applying and irradiating a laser on a pattern corresponding to the marking. 2. The laser marking method according to claim 1, wherein at least the surface of the resin molding is made of plastics, synthetic rubber, natural rubber, or a coating material containing resin as a main component. 3. The laser marking method according to claim 1, wherein the inorganic particles are carbon black or a pigment. 4. The laser marking method according to claim 1, wherein the inorganic particles have a color.