JP2730812B2 - Laser marking method and laser-marked molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser marking method for providing clear marks such as characters and symbols on the surface of a resin molded product or a molded product coated with a resin by using a laser beam, and to provide a laser marking method using the same. It relates to a molded article on which marking has been performed.

[0002]

2. Description of the Related Art As a method for marking desired characters, symbols, patterns, etc. on the surface of a resin molded article or a resin-coated molded article, a thermosetting ink has been conventionally used. However, this method takes a long time to mark, and the surface of the resin molded product generally has poor chemical activity due to poor chemical activity. There was a problem that it was difficult to perform. On the other hand, a laser marking method for marking characters, symbols, and the like using a laser beam has been proposed as a method for easily and quickly marking with good reproducibility, and has recently attracted attention. Laser marking is performed by irradiating the object with a laser beam and etching the surface to perform marking.A colorant that is easily discolored and decolored by laser irradiation is blended, and this is discolored and decolored by laser irradiation. To perform marking (for example,
60-155493, JP-A-61-192737) and the like have been proposed. However, the method of etching the surface with laser light not only requires a lot of laser energy to etch the surface of the object, but also hardly provides a contrast between the irradiated part and the non-irradiated part of the laser light,
It is difficult to give clear markings. In addition, there is a disadvantage that the irradiated portion is etched and becomes concave, so that the appearance is not preferable. In addition, when a colorant or the like which is easily discolored or bleached is compounded, and the method of irradiating it with a laser is used, the compounded material is liable to be discolored or bleached. There is a problem that it is difficult. Further, the color of the base material is limited by the coloring agent or the like to be blended. As a method for solving this problem, Japanese Patent Application Laid-Open No. 3-10884 discloses a non-white metal titanate, particularly a black-based metal titanate represented by K ₂ O · nTiO _x (1 ≦ x <1.9). A method has been proposed in which a resin containing potassium titanate is irradiated with a laser beam to perform white marking. However, even in this method, since the compounded substance is a non-white substance, particularly a black substance, the color of the molded article is limited to only a black substance, and there is a great limitation in the field of use.

[0003]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the present inventor has proposed a method for producing a clear laser beam on a white molded article or a molded article colored by blending various dyes and pigments with the white molded article. As a result of earnest research for the purpose of performing marking, they have found that this can be achieved by blending a specific substance into a resin, and have reached the present invention.
That is, the present invention K ₂ O · nTiO ₂ (where, n is an integer selected from 2, 4, 6, 8) the resin composition containing 0.1 to 70% by weight of potassium titanate represented by Laser marking method for irradiating a laser beam on a surface of a molded article made of a product or a molded article covered with the resin composition, and molding performed by the laser marking method It is about goods.

According to the present invention, by blending the above-mentioned potassium titanate into a resin, a white resin composition is basically obtained, and a molded article or a coating made of such a resin composition is irradiated with a laser beam. Thereby, a black marking is formed. Thus, the present invention has a very small difference in the chemical composition from the potassium titanate represented by K ₂ O · nTiO _x (1 ≦ x <1.9) disclosed in Japanese Patent Application Laid-Open No. 3-10884. It is completely unexpected and surprising that potassium titanate causes a phenomenon completely opposite to that in JP-A-3-10884, and that black-type highly visible markings are formed on white-type molded products. Met.

[0005] Since the potassium titanate-containing resin composition used in the present invention is basically white, it is easy to further add a dye or pigment to the resin composition for coloring. The laser marking of the present invention can be applied to molded articles and the like.

Hereinafter, the present invention will be described in detail. First, the resin used in the present invention is not particularly limited, and any of moldable known thermoplastic resins and thermosetting resins can be used. Examples of the thermoplastic resin include polyolefin resins such as polyethylene and polypropylene, polystyrene resins, polyvinyl chloride resins, poly (meth) acrylate resins, acrylic resins, polyacetal resins, polyethylene terephthalate, polybutylene terephthalate, and liquid crystal properties. Examples of polyester resin such as polyester, polyamide resin, polycarbonate resin, polyphenylene sulfide resin, polyimide resin and the like, and examples of thermosetting resin include epoxy resin, phenol resin and unsaturated polyester resin. These resins can be used alone or in combination of two or more. Also, various resins or oligomers used for coating by means such as painting can be used. Among these resins, in the present invention, those mainly comprising a polyacetal resin, a polyester resin and a polyarylene sulfide resin are preferable. When such a resin is used, particularly excellent marking is possible.

In the present invention, K ₂ O · nTiO ₂ (where n is 1, 2, 2)
(An integer selected from 4, 6, 8). Above all, K ₂ O ・ 6TiO
Potassium titanate represented by ₂ is preferable because it enables clear and highly visible laser marking and also has a high resin reinforcing effect. In particular, those having a tunnel structure and low free potassium are preferred. These potassium titanates used in the present invention may contain water of crystallization. Further, it can be used after being surface-treated with a coupling agent of silane type, titanium type, aluminum type or the like. In the present invention, the amount of the potassium titanate is 0.1 to 70% by weight. If the amount of potassium titanate is less than 0.1% by weight, sufficient marking cannot be performed. Conversely, if the amount exceeds 70% by weight, the physical properties of the resin composition deteriorate and the marking control becomes difficult. Taking into account the provision of clear markings and the balance of physical properties as a resin composition, the amount of potassium titanate is preferably 0.5 to 50% by weight, particularly preferably 1 to 40% by weight.
% By weight.

In the present invention, if necessary, known additives and the like are added to the above-mentioned resin composition which is molded or coated and provided for laser marking as long as the marking by laser irradiation is not significantly impaired. be able to. For example, stabilizers such as antioxidants, heat stabilizers, ultraviolet absorbers, light stabilizers, antistatic agents, flame retardants, flame retardant assistants, coloring agents such as dyes and pigments, lubricants, plasticizers, mold release Agent,
A surfactant, a crystallization accelerator, a crystal nucleating agent, a curing agent, a cross-linking agent, a fluidity adjusting agent, and the like can be added. Further, a fibrous, plate-like, or granular inorganic compound such as glass fiber, glass flake, mica, and glass beads may be used in combination.

In the present invention, a laser beam is applied to a desired position on a molded article made of such a resin composition or a resin, ceramic, metal or the like coated with the resin composition by printing, coating, multiple molding, or the like. Just by irradiating, clear marking is easily performed. In order to perform marking of a desired shape, for example, a method of scanning a surface of an object by using a laser beam as a spot of an appropriate size, a laser beam of a desired shape by masking the laser beam, There is a method of irradiating the surface of an object. The type of laser used is not particularly limited, and examples thereof include a carbon dioxide gas laser, a ruby laser, a semiconductor laser, an argon laser, an excimer laser, and a YAG laser. Above all, Nd: YAG
Lasers are preferred, particularly preferred scanning Nd:
YAG laser.

[0010]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Examples 1 to 6 and Comparative Examples 1 and ₂ Potassium titanate represented by K ₂ O.6TiO ₂ was added to a polyacetal resin (POM) and a polybutylene terephthalate resin (PBT) in the proportions shown in Table 1. The compounded resin composition was prepared and injection-molded to obtain a flat plate having a size of 50 mm × 70 mm and a thickness of 3 mm. Next, marking was performed on this flat plate using a scanning Nd: YAG laser. The marking conditions are as follows. On the other hand, for comparison, a flat plate was similarly molded for a polyacetal resin and a polybutylene terephthalate resin not containing potassium titanate,
I tried marking with Nd: YAG laser. Table 1 shows the results. [Marking conditions] Equipment: NEC Corporation Laser Marker SL475E Number of marking characters: 40 characters Marking method: One-stroke writing method Power at the marking part: 3W Scan speed: 100mm / sec Byte size: 30μm Q switch frequency: 3kHz Processing time : 3 sec Examples 7 to 9 and Comparative Examples 3 to 5 The same laser marking was performed on a flat plate formed by adding various coloring agents to the resin composition of Example 2. For comparison, the same laser marking was attempted on a flat plate formed by adding various coloring agents to a polyacetal resin containing no potassium titanate. Table 2 shows the results.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

As is apparent from the above description and Examples, according to the laser marking method of the present invention, K
_Since a resin composition mixed with potassium titanate represented by ₂ O · nTiO ₂ is used, a black-based molded product is basically provided with a black-based extremely high-contrast marking. Also, since the resin composition containing potassium titanate represented by K ₂ O.nTiO ₂ is basically white,
It is also easy to mix and color dyes and pigments with this, and it is also characterized in that a molded article colored in a desired color can be marked. As described above, the laser marking method of the present invention has features such as a wide applicable range, a high marking speed, automation, and easy process control, and is extremely practical.

Claims (6)

(57) [Claims] 1. A resin composition containing 0.1 to 70% by weight of potassium titanate represented by K ₂ O.nTiO ₂ (where n is an integer selected from 1, ₂ , 4, 6, and 8). A laser marking method comprising irradiating a laser beam onto a surface of a molded article made of a product or a molded article covered with the resin composition to perform marking. 2. The laser marking method according to claim 1, wherein the potassium titanate is represented by K ₂ O · 6TiO ₂ . 3. The laser marking method according to claim 1, wherein the laser beam is a Nd: YAG laser. 4. The laser marking method according to claim 3, wherein the laser beam is a scanning type Nd: YAG laser. 5. The resin constituting the resin composition is mainly composed of a polyacetal resin, a thermoplastic polyester resin or a polyarylene sulfide resin.
The laser marking method according to any one of claims 1 to 4. 6. A molded product which has been marked by the laser marking method according to claim 1.