JPH04108854A - polycarbonate molding - Google Patents

Abstract

PURPOSE:To obtain a molded polycarbonate remarkably improved in laser marking properties by blending a polycarbonate with a specific amount of specified carbon black. CONSTITUTION:A molded polycarbonate is obtained by containing 0.01-3wt.%, preferably 0.03-1wt.% carbon black having >=120ml/100g, preferably 170-600ml/100g oil absorption in a polycarbonate having 13000-50000, preferably 15000-35000 viscosity-average molecular weight.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present 5A decoy relates to a polycarbonate molded article for marking with laser light.

<Prior Art> Conventionally, plastic molded products have been marked with laser light. On the other hand, since polycarbonate has excellent performance, it is melt-molded and used for many purposes.

However, even when marking a polycarbonate molded article with a laser beam, it is difficult to obtain a clear mark.

JP-A-1-254743 proposes that titanium oxide or titanium oxide and carbon black be contained in order to improve the laser marking properties of plastics. However, even when this method is applied to polycarbonate, its laser marking properties are not satisfactory.

<Objective of the Invention> An object of the present invention is to provide a polycarbonate molded product that can provide a clear mark with a laser beam.

As a result of intensive studies aimed at achieving the above object, the present inventor has discovered that by incorporating a specific amount of a specific carbon black into polycarbonate, the laser marking properties can be significantly improved, and the present invention has been completed. It is.

<Configuration of the Invention> The present invention has an oil absorption amount of 12o#li! The present invention relates to a polycarbonate molded article for laser marking, which is made of polycarbonate containing 0.01 to 3.0% suspended carbon black of 0.01 to 3.0% or more.

The polycarbonate used in the present invention is produced by reacting a dihydric phenol and a carbonate precursor by a solution method or a melt method.

As the dihydric phenol, 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A) is used, but part or all of it may be replaced with other dihydric phenol. Other dihydric phenols include, for example, 1,
1-bis(4-hydroxyphenyl)ethane, 1.1-
Bis(4-hydroxyphenyl)cyclohexane, 2,
2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-
dibromphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfone, etc. can be given. Examples of carbonate precursors include carbonyl halides, carbonyl esters, and heroformates. Specific examples include phosgene, diphenyl carbonate, and dihaloformates of dihydric phenols.

The degree of polymerization of the polycarbonate is generally 13,000 to 50,000, preferably 15.00, expressed as a viscosity average molecular weight.
000 to 35,000. In producing polycarbonate with such a molecular weight, a suitable molecular weight regulator,
A catalyst or the like may be used to promote the reaction.

The carbon black used in the present invention has an oil absorption of 120
rd/100Q or more, preferably 170-600d/
The oil absorption amount is measured using a Cabot type oil absorption meter using dibutyl phthalate as a vehicle.

The oil absorption amount of carbon black, which is normally used for coloring, is 11
(7/100g or less, and most of them are 10 (
7/100 (+ or less. If such carbon black for coloring is used, the laser marking property of the target polycarbonate molded product cannot be sufficiently improved.The oil absorption amount used in the present invention is 120d
/100g or more of carbon black can be selected from commercially available conductive carbon blacks. For example, Ketchen Black manufactured by Lion Akzo, Carbon Black #305 manufactured by Mitsubishi Chemical Corporation.
0. #3250. #3950 etc. can be given.

If the amount of carbon black used is too small, the laser marking property of the polycarbonate molded product cannot be sufficiently improved, and if it is too large, the mark tends to become unclear. Therefore, the amount should be 0.01 to 3.0% by weight in the resulting polycarbonate molded article, and preferably 0.03 to 1.0% by weight. In addition, if the above-mentioned specific carbon black is used in an amount within the above-mentioned range, other carbon blacks can be further added as necessary. Any method can be used to incorporate carbon black into the polycarbonate molded product. Usually, a predetermined amount of carbon black is added and mixed to polycarbonate powder or pellets to form pellets, or directly molded using a conventional method, or polycarbonate powder or pellets are mixed with several times the predetermined amount. A method is adopted in which carbon black is added and mixed to form master pellets, and the master pellets are mixed with a predetermined amount of polycarbonate powder or pellets and molded according to a conventional method.

In addition, when molding, other additives,
For example, colorants, stabilizers, ultraviolet absorbers, flame retardants, reinforcing materials such as glass fibers and glass peas, etc. may be added in advance.

<Effects of the Invention> The polycarbonate molded product of the present invention can be marked with a clear mark using a laser beam with low energy.
Marking can be done easily and clearly even by an irradiation method that uses a mask that is particularly difficult to mark.

<Example> Examples will be given below for further explanation. In addition, evaluation of laser marking and marks in Examples was performed as follows.

Laser marking: Using 2 tum thick polycarbonate specimens containing a predetermined amount of carbon black, each specimen was marked with a wavelength of 10
, 6μ laser light (carbon dioxide laser) at a pattern reduction rate of 1/2 or 1/3.

When the reduction ratio is 1/2, an area of about 3 x 14# can be marked. Using a mask punched out from 1234567, marking was performed at an output of 30KV, and then the output was increased in steps of 2KV to mark a total of 10 times to 48KV. . The marking conditions at this time are as follows.

Laser mm cover turn area 6 ci cylindrical resin focal length 11ff 3o, ocm
Meniscus lens focal length 12.7cm Distance between cylindrical lenses 15.0ffi Distance between mask and meniscus lens 38.1cm Distance between meniscus lenses 19.30m When the reduction rate is 1/3, use the same mask and mark The range of approximately 2 x 9
# was bound and marked 10 times in the same manner. The marking conditions at this time are as follows.

Laser mm cover turn area 6 d Cylindrical lens focal path @ 30. Ocm Meniscus lens focal length 12.7cm Distance between cylindrical lenses 15.0cm 0m Maskle meniscus lens distance 50.8cm Distance between meniscus lenses 17.2cm Marking evaluation: All 1234567 marked on each specimen become clear Indicated by the lowest irradiation energy density.

The irradiation energy density J (Joule/cm) was determined by the following formula.

J= (E/S)x [Fc/ (Fc-l-)]
(A/B) 2E = 0.21V-4,3 V: Laser output (KV) E: Laser output energy (Joule) S: Laser mm cover turn area (ci) FC Nijilintorical lens focal length (cm) [Niji Lintrical lens
Distance between squares 9 (cm) Distance between mask and meniscus lens (cm) B: Distance between meniscus force and mark plane (IJ) Examples 1 to 10. Comparative Examples 1 to 7 Polycarbonate powder with a viscosity average molecular weight of 22,000 (Teijin Kasei Panlite L-1225) was heated at 120°C.
After drying for 5 hours, various additives listed in Table 1 were mixed in the amount listed in the table, and a 3oMφ vented extruder (Nakatani ■
The pellets were pelletized at a cylinder temperature of 280° C. using vS (manufactured by VS-30). This pellet was dried at 120°C for 5 hours, and a test piece (50 x 80 x 2 am) was prepared using an injection molding machine (J-120SA manufactured by Japan Steel Works, Ltd.) at a cylinder temperature of 19280°C and a mold temperature of 80°C. Laser marking was performed and the results are shown in Table 1. The fact that marks cannot be made in the notes column of the table does not indicate that clear marks could not be obtained even at the highest output of 48 KV (irradiation energy density of 7.51 J/crj at a reduction rate of 1/2).

The symbols indicating the types of additives in the table are as follows.

CB-A: Lion Akzo carbon black (Ketchen Black EC600JD, oil absorption 495m/
100111) CB-B: Carbon black manufactured by Mitsubishi Chemical Corporation (#
3050S oil absorption i 180dl/100σ) CB-C:
Carbon black manufactured by Mitsubishi Chemical Corporation (#3250, oil absorption 180mf/Jug) CB-D: Carbon black manufactured by Mitsubishi Chemical Corporation (#950, oil absorption 80mf!
/ 100(]) CB-E: Carbon black manufactured by Mitsubishi Chemical Corporation (#50, oil absorption 65d/100(+)
Tie: Titanium oxide made by Ishihara Sangyo ■ (Tie Bake CR-60) Table

Claims (1)

[Claims] A polycarbonate molded article for laser marking made of polycarbonate containing 0.01 to 3.0% by weight of carbon black with an oil absorption of 120 ml/100 g or more.