JPH06136273A - Resin composition for laser marking - Google Patents

Abstract

PURPOSE:To provide a resin composition capable of easily giving clear and firm markings in a short time. CONSTITUTION:The resin composition comprising (A) a thermoplastic resin and (B) an inorganic compound releasing at least part of the water contained in at 200-1000 deg.C (pref. zinc borate hydrate). Optionally, this composition may be incorporated with carbon black and/or flame retardant.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a resin composition for laser marking.

[0002]

2. Description of the Related Art As a marking method of a thermoplastic resin, there are an ink jet method, an ink spray method, a screen printing method, an ink writing method and the like. Generally, these methods have problems of thermal shock resistance (peeling of ink surface), weather resistance (discoloration of ink), and abrasion resistance (wear of ink surface). Inkjet method and screen printing are those in which ink is applied and dried on the resin surface, but the ink and resin materials are different,
It is difficult to make a perfect close contact, and care must be taken in that point when selecting the ink. In addition, in the ink embedding method, a marking portion of the resin is preliminarily provided with a depression at the time of molding or engraving is performed after molding, and then ink and paint are embedded in the marking portion for marking. However, it is difficult to change the marking shape for each product because the marking shape is limited by the mold in the method of forming a depression during molding, and engraving takes a lot of time in the method of engraving. In addition, it is necessary to embed ink or paint later to remove excess ink or paint, which complicates the process and is not suitable as a marking method for mass-produced products.

For the above reasons, a laser marking method which is non-contact, has a high marking speed, and is easy to automate and process control has been industrially used in recent years. The laser marking method is a method of marking a mark, a bar code, an image, or the like on a surface of metal, ceramics, high molecular weight organic material, or the like by using laser light.

Laser marking is performed by irradiating a target surface with a laser beam and (1) marking by utilizing a change in the surface state (roughening or recessing) due to etching of the irradiation portion,
(2) JP-A-56-144995, JP-A-60-155493, JP-A-60-166488, JP-A-60-172590, JP-A-60-47065, JP-A-60-47065 As described in Japanese Patent Laid-Open No. 62-50360 and Japanese Patent Laid-Open No. 3-10884, marking using decolorization or discoloration of pigments, dyes, etc. in the irradiated area, and (3) Japanese Patent Publication No. 2- As described in Japanese Patent No. 47314, there is a method of marking by using a change in the state of the surface (convex shape) due to foaming of the material resin. here,
In the marking using the state change of (3), unpolymerized monomers and decomposition products contained in the resin in the portion to which the laser beam is remarkably heated are volatilized, and the portion is foamed. Therefore, marking is performed because light is diffusely reflected and resin is raised.

However, in the marking of (1) by roughening or recessing the surface, the boundary between the irradiated and unirradiated portions of the laser light is not clear. Mold different types of resin into a layered structure,
A method of removing only the resin of the surface layer may be adopted, but this method has a very complicated manufacturing process, and there is a problem in which layer is etched. The marking (2) of decoloring or discoloring pigments, dyes and the like has a drawback that the type and color of the resin are limited depending on the types of pigments and dyes.
Further, since pigments, dyes and the like are easily decolorized and colored by heat, the discolored area is widened and the outlines of characters and the like become unclear. In the marking of (3) that utilizes the change of state due to foaming, it is necessary to investigate the optimum conditions for each resin. In addition, considering that the resin is rarely used alone, for example, when marking the surface of a resin composition composed of a plurality of components, it is necessary to examine the appropriate conditions in various compositions one by one. Furthermore, some resins are less likely to foam, so the resins used are limited.

[0006] Therefore, an object of the present invention is to provide a resin composition to which a clear and firm marking can be easily applied in a short time.

[0007]

DISCLOSURE OF THE INVENTION The present inventor has found that when a specific compound is contained in a thermoplastic resin, a resin composition capable of providing clear marking with a very simple operation can be obtained. .

That is, the present invention is a resin composition for laser marking containing A) a thermoplastic resin, and B) an inorganic compound which releases at least a part of water at a temperature of 200 to 1000 ° C.

The thermoplastic resin used in the present invention is not particularly limited, and various known resins can be used. Examples include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PB).
T), polycyclohexene terephthalate (PCT);
Polyphenylene oxide (PPO); Polycarbonate (PC); Polyetherimide (PEI); Polystyrene (PS), for example high impact polystyrene (HIP)
S); polyethylene (PE); polypropylene (P
P); Polyamide (PA); Vinyl chloride resin (PV
C); polyacetal (POM); fluororesin such as polytetrafluoroethylene; acrylic resin; polysulfone; polyphenylene sulfide (PPS); methylpentene resin and the like, but are not limited thereto. Alloys of various thermoplastic resins, for example, alloys of PPO and PS resin can also be used. Preferably, polyester, PPO, PC, PEI or a resin alloy containing these is used.

An important requirement of the present invention is to use as one component of the resin composition an inorganic compound which releases at least a part of water at a temperature of 200 to 1000 ° C. As a result, a resin (composition) which could not be marked by the method described in Japanese Patent Publication No. 2-47314 can be marked. Moreover, the markings are very clear because they do not affect the unirradiated portions of the laser light. Incidentally, according to the research conducted by the present inventor, as described in Japanese Patent Publication No. 2-47314, from the viewpoint of foaming the laser light irradiation part, an aliphatic hydrocarbon,
When a compound such as a chlorinated compound, a fluorinated compound, or a bicarbonate, which is usually used as a foaming agent, is included, foaming occurs during the production of a resin composition, or even the laser non-irradiated area foams and marks. It causes inconvenience such as blurring. Further, even if a compound that does not release water such as anhydrous zinc borate is used, the sharpness of the marking is hardly improved. That is, according to the present invention, only a resin composition containing an inorganic compound that releases at least a part of water at a temperature of 200 to 1000 ° C. gives a clear marking by laser light irradiation. This is totally unexpected.

Inorganic compounds that release at least a part of water at a temperature of 200 to 1000 ° C. (hereinafter, sometimes referred to as water-releasing inorganic compounds) are known per se, for example, Chemical Handbook Basic Edition (Maruzen, Nihon Kagaku). Edited by the Society). As an example, 2ZnO · 3B ₂ O ₃ · 3.5H ₂ O, Z
nB ₄ O ₇ · 4H ₂ O, zinc borate hydrate, etc., other Ce
_{2 (SO 4) 3 · 8H} 2 O, MgSO 4 · H 2 O, Li
Inorganic compounds having water of crystallization, such as I · 3H ₂ O and Ba (OH) ₂ · 8H ₂ O; Al (OH) ₃ , Ca (O
Examples thereof include, but are not limited to, compounds such as H) ₂ and Mg (OH) ₂ that decompose to release water at the above temperature. If there is no problem even if the resin composition is colored, CoSO ₄ .7H ₂ O, CrPO ₄
-A colored compound such as 6H ₂ O can also be used. It is also possible to use two or more water-releasing inorganic compounds in combination. It is preferable that these water-releasing inorganic compounds hardly release water at a temperature of less than 200 ° C. If a compound that releases a considerable amount of water at a temperature of less than 200 ° C is used, water will be released during the production of the resin composition and molding cannot be performed satisfactorily. It causes inconvenience such as. Even when a compound that does not release water even at a high temperature of more than 1000 ° C. is used, the sharpness of marking is hardly improved as compared with the case where no inorganic compound is added. More preferably, compounds that release water only within the temperature range of about 300-600 ° C are used. As a preferred example, zinc borate hydrate,
Particularly, 2ZnO.3B ₂ O ₃ .3.5H ₂ O can be mentioned. These water-releasing inorganic compounds are thermoplastic resins 1
It is preferably used in an amount of about 0.1 to 50 parts by weight, more preferably about 1 to 10 parts by weight, based on 00 parts by weight.

The resin composition of the present invention may contain carbon black as an optional component. By including carbon black together with the water-releasing inorganic compound, clearer marking can be applied to the resin composition. In the present invention, the carbon black may be any carbon black, and various known carbon blacks can be used. Carbon black is generally produced by a furnace method, a contact method, an impact method, and as a raw material, mainly creosote oil, heavy oil, ethylene bottom oil, natural gas, acetylene gas, naphthalene, anthracene, oil, coal gas, Pitch oil etc. can be mentioned. Depending on the manufacturing method and raw materials used, it is called furnace black, lamp black, thermal black, acetylene black, German furnel black, channel black, roller black, German naphthalene black, gas black, oil black and the like. An example of commercially available carbon black is Degussa
FW18 manufactured by Mitsubishi Kasei Co., Ltd., # 8500 manufactured by Tokai Carbon Co., Ltd., and the like. You may use 2 or more types of carbon black. Carbon black
It is preferably 0.01 to 3 with respect to 100 parts by weight of the thermoplastic resin.
It is used in an amount of about parts by weight, more preferably about 0.05 to 1.5 parts by weight.

The resin composition for laser marking of the present invention may further contain any known substance. For example, styrene-butadiene copolymer (SB), styrene-acrylonitrile copolymer (SAN), styrene-butadiene-styrene copolymer (SBS), styrene-ethylene-butadiene-styrene copolymer (SEBS), ethylene-propylene It may contain a rubber component such as a copolymer (EP), an ethylene-propylene-diene copolymer (EPDM), and an acrylonitrile-butadiene-styrene copolymer (ABS).

The resin composition for laser marking of the present invention may also contain various flame retardants and flame retardant aids. There is no particular limitation on the flame retardant and the flame retardant auxiliary agent, and preferred examples include halogen-based flame retardants such as imide bromide, polycarbonate bromide, epoxy compound bromide, bisphenol A bromide (Br-BPA), and polyphenylene oxide bromide; Phosphorus-based flame retardants such as triphenyl phosphate (TPP),
And flame retardant aids such as Sb ₂ O ₃ can be cited, but the invention is not limited thereto. The amount of these flame retardants and flame retardant aids can be arbitrarily set according to the type of the thermoplastic resin and the intended resin composition, but generally, the amount of the flame retardant is 100 parts by weight of the thermoplastic resin. It is preferable that the amount is about 5 to 30 parts by weight and the amount of the flame retardant auxiliary is about 0 to 15.

The resin composition for laser marking of the present invention may further contain a reinforcing agent such as glass fiber, carbon fiber or aramid fiber. The amount thereof may also be set arbitrarily depending on the kind of the thermoplastic resin and the intended resin composition, but in general, it is about 0 to 100 parts by weight, particularly about 0 part by weight based on 100 parts by weight of the thermoplastic resin. It is preferably about 50 parts by weight.

Optional components other than the above, for example, inorganic or organic fillers such as glass, silica and talc, plasticizers,
One or more conventional additives such as lubricants, heat stabilizers, weather stabilizers, antistatic agents, slip agents, antiblocking agents, antifog agents, pigments, dyes, natural oils, synthetic oils, waxes, etc. It can be contained in the resin composition of the present invention as long as the above purpose is not impaired.

The resin composition for laser marking of the present invention can be obtained by mixing the above components. The mixing method is not particularly limited, and the mixing order of each component is arbitrary. For example, other optional components such as a water-releasing inorganic compound and carbon black may be added to and mixed with the thermoplastic resin in a molten state, and the solution of the thermoplastic resin may be mixed with the water-releasing inorganic compound and carbon black. You may knead by adding other arbitrary components, such as. More specifically, a method in which a water-releasing inorganic compound and an optional component are separately or simultaneously added to a thermoplastic resin in a molten state and kneading, or a pellet of the thermoplastic resin is water-releasing. A method of melt kneading by supplying to an uniaxial or biaxial extruder with an inorganic compound and optional components, or a thermoplastic resin in an appropriate solvent (for example, methylene chloride, chloroform,
And a water-releasing inorganic compound and optional components are added to this solution separately or simultaneously and stirred. Of these, for the melt-kneading method, one of the preferred embodiments is exemplified by using a uniaxial or twin-screw extruder having D = 30 to 90 mm, and using a temperature suitable for the thermoplastic resin used (for example, about 260 for PBT resin). ℃, about 280 for PCT resin
℃, about 280 ℃ for a mixture of PPO resin and PS resin,
The resin composition of the present invention can be obtained in the form of pellets by extrusion at a temperature of about 270 ° C. for PC resin and about 330 ° C. for PEI resin). Further, the method for producing a molded product from the resin composition of the present invention is not particularly limited, and various known methods such as injection molding, extrusion molding, blow molding and vacuum molding can be used. There are also no particular restrictions on the molding conditions, the components used,
Any temperature according to the target molded product, molding method, etc. (for example, about 260 ° C for PBT resin injection molding, about 280 ° C for PCT resin injection molding, injection molding of a mixture of PPO resin and PS resin) In this case, the temperature can be set to about 260 ° C, the temperature can be set to about 270 ° C for the injection molding of PC resin, and the temperature can be set to about 320 ° C for the injection molding of PEI resin), but the molding can be performed under conditions such as pressure. Those skilled in the art will be able to easily select an appropriate kneading method and molding method depending on the components used, the intended product, and the like.

Laser marking can be performed on the resin composition of the present invention by any method. As an example, a carbon dioxide gas laser and a YAG laser can be used, but not limited to these. The resin composition of the present invention,
By irradiating with laser light, clear marking can be performed. In the marking on the resin composition of the present invention, unlike the marking in which the dye or pigment is decolored or discolored, the influence of the laser beam does not affect the portions other than the irradiated portion.
Therefore, it is possible to draw a fine line with a width of about 10 μm, for example. In addition, marking can be performed quickly, and for example, a line with a width of about 1.0 mm can be drawn at a speed of 200 mm / sec or more. Although the present invention includes resin compositions having various compositions, it is not necessary to examine the optimum conditions of irradiation for each composition one by one, and the resin used as a component is not limited. The resin composition of the present invention further has the advantage that the manufacturing process can be simplified.

Although the reason why the resin composition of the present invention is clearly marked by laser light is not clear, water is separated and vaporized from the water-releasing inorganic compound in the resin composition at the portion irradiated with laser light. It is conceivable that the resin composition in that portion becomes convex / concave and diffuse reflection of light occurs.
The more vivid marking by inclusion of carbon black would be that carbon black enhances the heat conversion efficiency of the laser light energy and at the same time enhances the visual effect.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[0021]

EXAMPLE The components shown in Tables 1 to 3 were selected from the following components and extruded using an extruder to produce pellets. Using this pellet, a 50 mm × 50 mm × 3 mm molded product was injection molded. A) As a resin Aa): PBT [VALOX (trademark) manufactured by Japan GE Plastics Co., Ltd.] Ab): PCT [VALOX (trademark) manufactured by Japan GE Plastics Co., Ltd.] Ac): PPO and PS Mixture with resin [NORYL (trademark) made by Nippon GE Plastics Co., Ltd.] Ad: PC [made by Nippon GE Plastics Co., Ltd.
LEXAN (trademark)] Ae): 100 parts by weight of PEI [ULTEM (trademark) manufactured by Nippon GE Plastics Co., Ltd.], B) Zinc borate hydrate as a water-releasing inorganic compound [Sanyo Chemical Industries ( ZB2335 (trademark), 2ZnO / 3B ₂ manufactured by
O ₃ · 3.5H ₂ O], amounts shown in Tables 1 to 3 (parts by weight)
B ') Anhydrous zinc borate as an inorganic compound that does not release water (obtained by heating zinc borate hydrate of B above at 600 ° C.), the amount shown in Tables 1 to 3 (weight Part), C) carbon black [FW18 (trademark) manufactured by Degussa), used in the amounts (parts by weight) shown in Tables 1 to 3, D) flame retardant Da): imide bromide [ethyl] BT-9 made by Corporation
3 (trademark)] 15 parts by weight Db): Brominated PC [ML4365 (trademark) manufactured by Japan GE Plastics Co., Ltd.] 15 parts by weight Dc): PS bromide [Pyrocheck (trademark) manufactured by Ferrochemical Co., Ltd.] 15 parts by weight Dd): brominated epoxy compound [SR-T5000 manufactured by Sakamoto Yakuhin Co., Ltd.
(Trademark)] 15 parts by weight De): BPA bromide oligomer [FR-53 (trademark) manufactured by Mitsubishi Gas] 15 parts by weight Df): BPA bromide oligomer (FR-53) 12 parts by weight and S
Mixture with 5 parts by weight of b ₂ O ₃ Dg): 12 parts by weight of TPP, and E) glass fiber, used in the amounts (parts by weight) shown in Tables 1 to 3.

The surface of the obtained molded product was marked with a CO ₂ gas laser or a YAG laser. Marking conditions are as follows: CO ₂ gas laser: 6 to 24 J / cm ² YAG laser: moving speed 100 to 400 mm / s Bit size 10 to 140 μm The sharpness of the marking was visually evaluated. The results are shown in Tables 1 to 3. The symbols in the table mean the following: ⊚: extremely clear, ○: clear, Δ: slightly unclear, ×: unclear.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3] From the above, it is clear that, according to the present invention, a composition containing a water-releasing inorganic compound produces clearer marking by laser light irradiation than a composition containing no water-releasing inorganic compound. Further, it can be said that clear marking cannot be obtained in a composition containing an inorganic compound that is not water-releasing, whereas clear marking is obtained in a composition containing a water-releasing inorganic compound according to the present invention. Is clearly stated.

[0026]

The resin composition of the present invention can be marked clearly and firmly by irradiation with laser light. In the resin composition of the present invention, the influence of the laser beam does not affect the parts other than the irradiated part. Therefore, for example, 10 μm
It is also possible to draw fine lines of about the width. Although the present invention includes resin compositions having various compositions, it is no longer necessary to examine the optimum conditions of irradiation for each composition one by one. The resin composition of the present invention further has the advantage that the manufacturing process is simplified.

Claims (4)

[Claims] 1. A resin composition for laser marking containing A) a thermoplastic resin, and B) an inorganic compound which releases at least a part of water at a temperature of 200 to 1000 ° C. 2. The resin composition for laser marking according to claim 1, wherein the inorganic compound is zinc borate hydrate. 3. The resin composition for laser marking according to claim 1, further comprising carbon black. 4. The composition according to claim 1, further comprising a flame retardant.
The resin composition for laser marking according to any one of 1.