JPH07316341A - Thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To produce a thermoplastic resin composition forming a marked part having excellent whiteness and distinctiveness by laser beam and useful as a molded resin article for laser marking by compounding a thermoplastic resin with carbon and titanium oxide at specific ratios. CONSTITUTION:This resin composition is produced by compounding (A) 100 pts.wt. of a thermoplastic resin such as polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalenedicarboxylate or polycarbonate with (B) 0.001-5 pts.wt. of carbon and (C) 3-15 pts.wt. of titanium oxide which is white powder expressed by formula TiOx ((x) is 1 or 2).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermoplastic resin composition which can be marked with a laser beam.

[0002]

2. Description of the Related Art The prior art of the invention and its problems have attracted attention as a method of marking on the surface of a resin molded product, since printing using ink has been able to perform printing with moderate efficiency. This is a technique in which a filler that absorbs light and heat is mixed in the material in advance so that marking can be performed by foaming, decomposition, or the like during laser irradiation.
No. 246456 proposes that by adding carbon black and / or graphite having high thermal conductivity, white color marking with good contrast is possible. However, when using these carbons,
It is unavoidable that the portion irradiated with laser light is carbonized and the whiteness of the surface of the composition is somewhat lowered, and further improvement has been demanded.
Further, Japanese Patent Laid-Open No. 1-254743 discloses a technique for obtaining a black colored marking by mixing titanium dioxide.

As a result of intensive studies conducted by the present inventor to improve the whiteness of the marking, surprisingly, the thermoplastic resin can be marked with white color. The present inventors have found that the whiteness of a laser-irradiated portion is improved by blending carbon and titanium dioxide which is an auxiliary agent for marking black color development, and arrived at the present invention.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a material capable of clear marking with excellent whiteness by laser light.

[0005]

The thermoplastic resin composition of the present invention comprises (A)
To 100 parts by weight of the thermoplastic resin, 0.001 to 5 parts by weight of (B) carbon and 3 to 3 parts of (C) titanium oxide are used.
It is 15 parts by weight and has excellent laser marking properties.

The present invention will be described in detail below.

The thermoplastic resin as the component (A) used in the present invention is not particularly limited, and general-purpose resins such as polyethylene, polypropylene and ABS, aromatic saturated polyester, polycarbonate, polyamide, polysulfone,
Examples include engineering plastics such as polyacetal. Of these, aromatic saturated polyesters and aromatic polycarbonates are particularly preferable. The aromatic saturated polyester resin used in the present invention uses terephthalic acid or 2,6-naphthalenedicarboxylic acid or an ester-forming derivative thereof as a main acid component, and a glycol having 2 to 10 carbon atoms or a glycol thereof as a main glycol component. It is a linear saturated polyester obtained by using an ester-forming derivative. For example, polyethylene terephthalate (PET), polypropylene terephthalate, polybutylene terephthalate (PBT), polyhexamethylene terephthalate, polycyclohexane-1,
4-dimethylene terephthalate, polyethylene-2,6
-Naphthalate (PBN) etc. are mentioned. Of these, PET, PBT and PBN are particularly preferable.

The term "mainly" as used herein means 80 mol% or more, preferably 90 mol% or more, based on all acid components or all glycol components. Further, a part of the acid component or glycol component may be replaced with another copolymerization component. Such copolymerizable acid components include aromatic dicarboxylic acids other than terephthalic acid and 2,6-naphthalenedicarboxylic acid, such as isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenoxyethanedicarboxylic acid, Diphenyl ketone dicarboxylic acid, diphenyl sulfone dicarboxylic acid, etc., aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, etc., alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, tetralindicarboxylic acid, decalin dicarboxylic acid, etc. are exemplified. It Examples of the copolymerizable glycol component include ethylene glycol, propylene glycol, butylene glycol, hexamethylene glycol, decane diol, 1,4 cyclohexanedimethanol, tricyclodecane dimethylol, bisphenol A, bisphenol S, bishydroxyethoxy bisphenol. For example, Rule A and the like are exemplified. In addition, the aromatic saturated polyester used in the present invention is a copolymer of a polyfunctional compound such as glycerin, trimethylolpropane, pentaerythritol, trimellitic acid, and pyromellitic acid in a range that does not substantially impair the moldability. You may.

The aromatic polycarbonate resin used in the present invention is derived from a dihydric phenol, and its molecular weight is 10,000 to 10 in terms of viscosity average molecular weight.
It is 10,000, preferably 15,000 to 60,000 aromatic polycarbonate resin. It is usually obtained by reacting a dihydric phenol with a carbonate precursor by a solution method or a melting method. Examples of dihydric phenol include 2,2-
Bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A), 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxy-3-)
Methylphenyl) propane, bis (4-hydroxyphenyl) sulfone and the like can be mentioned, bis (4-hydroxyphenyl) alkane is preferable, and bisphenol A is particularly preferable.

The carbon as the component (B) of the present invention preferably has a high thermal conductivity. These are characterized by having a relatively bulky structure such as a crystal structure in which graphitization has progressed or a secondary structure that forms a chain-like aggregate.

When carbon is added, if the amount of carbon is less than 10 ppm (0.001% by weight), sufficient marking properties cannot be imparted even if carbon is added. Further, even if the amount exceeds 5 parts by weight, the marking effect is not improved, so addition of 5 parts by weight is sufficient, and a small amount is desirable in order to prevent unnecessary coloring due to carbon when forming a molded product.

The titanium oxide as the component (C) of the present invention is a white powder, which is represented by TiO _x (X = 1, 2).

The amount of titanium oxide added is usually 3 to 15 parts by weight. If the amount is less than 3 parts by weight, it is not possible to obtain the desired marking with improved whiteness. If it exceeds 15 parts by weight, it is difficult to obtain a synergistic effect with carbon.

If desired, the thermoplastic resin composition of the present invention may contain other additives such as stabilizers, colorants, ultraviolet absorbers, mold release agents, crystallization accelerators, and crystal nuclei, as long as the characteristics are not significantly impaired. Materials, granular or plate-like fillers, impact modifiers, flame retardants, reinforcing materials, antioxidants and the like can be added.

Any compounding method can be used to obtain the resin composition of the present invention. Usually, it is preferable to disperse these blending components more uniformly, and all or part of them may be simultaneously or separately blended, for example, a blender,
A method of mixing and homogenizing with a mixer such as a kneader, a Panbury mixer, a roll or an extruder can be used.
Further, there is a method in which a composition dry-blended in advance is melt-kneaded by a heated extruder, homogenized, extruded into a wire shape, and then cut into a desired length to granulate.

The resin composition obtained by the present invention can be molded very easily by a usual method using a general thermoplastic resin molding machine.

[0017]

EXAMPLES The present invention will be described in detail below with reference to examples. In addition,
The evaluation of various indexes in the examples was performed by the following methods.

For laser processing, marking was performed with a YAG laser (NEC laser marker SL475E2).

The marking property was evaluated by the color of the color-developed portion by laser light and the foaming state.

The color difference is evaluated by a color analyzer TC-1.
The whiteness index WI of the marking portion was evaluated using 800MK-II. Further, it was confirmed that the foaming state was uniform and that fine foaming was formed.

The various raw materials shown in Table 1 were previously uniformly blended in a predetermined amount ratio, and then the temperature of the cylinder was 270 ° C., the screw rotation speed was 160 rpm, and the discharge amount was 40 kg / h using a twin screw extruder with a vent having a screw diameter of 44 mm. Was melt-kneaded, and the thread discharged from the die was cooled and then cut to obtain a molding pellet.

Next, using the pellets, a test piece for laser marking was prepared on an injection molding machine having an injection capacity of 5 ounces under the conditions of an injection pressure of 800 kg / cm ² , a cooling time of 15 seconds, and a total molding cycle of 28 seconds. It was molded and subjected to laser marking.

The results of these experiments are shown in Table 1.

[0024]

[Table 1]

The following materials were used as various raw materials shown in Table 1.

Component (A) PBT ... PBT resin TR from Teijin Ltd.
B-J (B) component-Carbon black ... Electrochemical Co., Ltd. EC600JD (C) component-Titanium dioxide ... Ishihara Sangyo Co., Ltd. CR-80

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 59/00 LML 67/02 KJQ 69/00 KKH 77/00 KKR 81/02 LRG 101/00 LSY // B23K 26/00 B

Claims (3)

[Claims] 1. To 100 parts by weight of a thermoplastic resin (A), 0.001 to 5 parts by weight of carbon (B) and (C)
A thermoplastic resin composition comprising 3 to 15 parts by weight of titanium oxide and having excellent laser marking properties. 2. The laser marking property according to claim 1, wherein the thermoplastic resin is selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalene dicarboxylate, polycarbonate, polyamide, polysulfone, polyacetal, ABS, polyethylene and polypropylene. Excellent thermoplastic resin composition. 3. The thermoplastic resin composition having excellent laser marking property according to claim 1, wherein the thermoplastic resin is at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalene dicarboxylate and polycarbonate. object.