KR100469864B1 - Exellent Laser Markable Thermoplastic Resin Composition - Google Patents

Abstract

The thermoplastic resin composition for laser marking of the present invention is (A) rubber having a mean particle size of 0.1-0.2 μm (a ₁ ) 30-60 wt% (based on solid content) and rubber having a mean particle size of 0.3-0.6 μm 70 (a ₂ ) 70 20-50 parts by weight of a rubbery polymer consisting of -40% by weight (based on solids); (B) 80-50 parts by weight of a monomer mixture consisting of 10-40% by weight of an aromatic vinyl monomer, 3-20% by weight of an unsaturated nitrile monomer, and 40-80% by weight of an alkyl methacrylate monomer; (C) 0.5-1.5 parts by weight of a molecular weight regulator consisting of a mixture of mercaptans and terpinolenic or alphamethyl styrene oligomer; (D) 0.2-1.0 parts by weight of color pigments; And (E) 0.2-1.0 parts by weight of the silicate compound.

Description

Thermoplastic resin composition with excellent laser marking {Exellent Laser Markable Thermoplastic Resin Composition}

Field of invention

The present invention relates to a resin composition for laser marking for white characters excellent in processability and impact strength. More specifically, the present invention relates to a resin composition for laser marking, comprising a monomer mixture composed of two or more rubber polymers having different average particle diameters, an aromatic vinyl, an unsaturated nitrile, and an alkyl methacrylate, a molecular weight modifier, a pigment, and an inorganic compound.

Background of the Invention

Conventionally, when a letter or a symbol is displayed on a plastic molded article used as an electronic component, a printing method such as tampo printing or silk printing is mainly used. However, such a printing method may cause the scattering of the ink, the defect rate is high due to the mismatch of the printing position, the manufacturing cost is high, and there is a problem of polluting the environment due to the use of solvent.

In addition, the method of attaching the printed film is used as one of the other methods, but the method of attaching the printed film also has a problem that the productivity is lowered and the required cost is high.

In order to solve such a problem, a laser marking method is recently performed. Laser marking refers to a method of irradiating a laser beam onto the surface of a molded product to pyrolyze the surface of the molded product or to evaporate a portion to display letters or symbols.

However, even in the case of laser marking, there are cases where the laser marking of letters or symbols may cause a difference in color development or clarity due to the type of resin material or the manufacturing process, and the physical properties such as formability and impact strength may decrease. In particular, in the case of laser marking expressing a white character, there is a problem that a difference occurs in whiteness and clarity due to a difference in the condition of resin production.

In the case of Japanese Patent No. 11001596, laser marking for white characters is improved by a combination of a rubber-reinforced resin and an acrylic resin, but there is a problem that the impact strength is lowered due to the lack of compatibility between the rubber-reinforced resin and the acrylic resin.

In order to solve the above problems, the present inventors mix and add a large particle rubber and a small particle rubber at a predetermined ratio, and the carbon black and titanium dioxide during the composition and compounding manufacturing process of the copolymerization monomer used in the graft emulsion polymerization step. By appropriately combining the combination ratios of the above, the thermoplastic resin for white character laser marking excellent in moldability and impact resistance has been developed.

An object of the present invention is to provide a thermoplastic resin composition with improved laser marking for white characters.

Another object of the present invention is to provide a thermoplastic resin composition for laser marking excellent in impact resistance.

Still another object of the present invention is to provide a thermoplastic resin composition for laser marking having excellent moldability.

Another object of the present invention is to provide a thermoplastic resin composition for laser marking excellent in whiteness and clarity.

The above and other objects of the present invention can be achieved by the present invention described below.

The thermoplastic resin composition for laser marking of the present invention is (A) rubber having a mean particle size of 0.1-0.2 μm (a ₁ ) 30-60 wt% (based on solid content) and rubber having a mean particle size of 0.3-0.6 μm 70 (a ₂ ) 70 20-50 parts by weight of a rubbery polymer composed of -40% by weight (based on solids), (B) 10-40% by weight of an aromatic vinyl monomer, 3-20% by weight of an unsaturated nitrile monomer, and an alkyl methacrylate monomer 40-. 80-50 parts by weight of a monomer mixture composed of 80% by weight, (C) 0.5-1.5 parts by weight of a molecular weight modifier consisting of a mixture of mercaptans and terpinolenic or alphamethylstyrene oligomers, (D) 0.2-1.0 parts by weight of a pigment pigment, and (E) 0.2-1.0 parts by weight of the silicate compound.

Hereinafter, each component of this invention is demonstrated in detail.

(A) rubbery polymer

The rubber-like polymer is a butadiene-based rubber latex is preferred, and the rubber has an average particle diameter 0.1-0.2 ㎛ (a ₁₎ 30-60% by weight of rubber (based on solids) and a mean particle diameter of 0.3-0.6 ㎛ (a ₂₎ 70- 40% by weight (based on solids) is used as a mixture. As such, when the small particle size rubber (a ₁ ) and the large particle size rubber (a ₂ ) are mixed and added under appropriate conditions, the effect of rubber on impact resistance can be exhibited to the maximum.

When the rubber (a ₁ ) having the average particle diameter of 0.1-0.2 μm is added in less than 30% by weight or 60% by weight or more, the impact resistance rapidly decreases. In addition, even when the rubber (a ₂ ) having an average particle diameter of 0.3-0.6 μm is used less than 40% by weight, the impact reinforcing effect is significantly lowered. When the rubber (a ₂ ) having an average particle diameter of 0.3-0.6 μm is used in excess of 70% by weight, the polymerization stability tablet is sharply dropped, thereby causing coagulation and deterioration of glossiness due to the large particle size.

In the present invention, the rubbery polymer is used in 20-50 parts by weight. If the total amount of rubbery polymer used is less than 20 parts by weight, the impact strength decreases due to the decrease in the impact reinforcement efficiency of the graft polymer when the final ABS product is manufactured. And there is a problem of poor drying due to the formation of coarse particles during the solidification process.

(B) monomer mixture

In the present invention, the monomer mixture is composed of 40-80% by weight of alkyl methacrylate monomer, 10-40% by weight of aromatic vinyl monomer and 3-20% by weight of unsaturated nitrile monomer.

Even if the ratio of the monomer mixture is out of the range there is a problem that the impact strength is lowered. In the present invention, the monomer mixture is used in the range of 80-50 parts by weight.

(C) molecular weight regulator

As the molecular weight modifier used in the present invention, an alkyl mercaptans conventionally used and one or two or more substances selected from terpinolene and alpha methyl styrene oligomer are mixed and used in an appropriate ratio. This is important in the present invention, when using a molecular weight modifier of compounds such as mercaptans such as t-dodecyl mercaptan, normal dodecyl mercaptan, t-butyl mercaptan, and halogenated hydrocarbons such as carbon tetrachloride, which are common chain transfer agents. The high impact resin composition required by the present invention cannot be obtained.

As for the appropriate combination ratio of a molecular weight modifier, the ratio of mercaptans, terpinolenic or alphamethyl styrene oligomer is 1: 1 to 1: 2. When the combination ratio of mercaptans and terpinolenic or alpha methyl styrene oligomer molecular weight is less than 1: 1, the impact increase effect by the terpinolenic or alpha methyl styrene oligomer is reduced, and when the combination ratio is 1: 2 or more, Impact increase effect by the pinolene or alpha methyl styrene oligomer, but there is a problem that the productivity is sharply reduced due to the decrease in the polymerization rate.

In addition, the total content of the molecular weight modifier is preferably 0.5 to 1.5 parts by weight, more preferably 0.7 to 0.1 parts by weight based on the total weight of the rubbery polymer latex and monomer mixture of the graft polymer. If the total injection amount of the molecular weight regulator is less than 0.5 parts by weight, the graft ratio is excessively increased, resulting in a decrease in the appearance and fluidity of the final product. When it is used in excess of 1.5 parts by weight, the graft ratio is lowered. There is a problem that the impact property is lowered.

(D) toning pigment

In the present invention, a compounding pigment and an inorganic compound are used in compounding the resin composition. The color pigment is used in a combination ratio of carbon black and white pigment in a ratio of 2: 1 to 3: 1, 0.2 to 1.0 parts by weight.

If the combination ratio of carbon black and white pigment is less than 2: 1, the sharpness of text is reduced due to excessive hiding power of the white pigment. If the combination ratio is 3: 1 or more, there is a problem that the whiteness is reduced due to carbonization of carbon black.

As the black dye or pigment used in the production of the resin composition of the present invention, a dye or pigment of an organic or inorganic component is used. These black dyes / pigments convert the laser light into thermal energy to foam the surface of the resin to improve the sharpness of the marked text.

Specific examples of the black dyes / pigments include carbon black, titanium black, black iron oxide, and the like, or may be used alone or in combination. In the present invention, the particle diameter of the black dye / pigment is preferably 10 nm-3 μm.

Inorganic materials used in the white pigments include calcium carbonate, titanium oxide, zinc oxide, zinc sulfide, and the like. These white inorganic pigments enhance the hiding power of the resin and scatter the laser light to assist in increasing the clarity of the black dyes / pigments. Do it.

(E) Inorganic Compound

In the present invention, a silicate compound is used as the inorganic compound to improve whiteness and sharpness. The silicate compound is used in 0.2 to 1.0 parts by weight. If the silicide compound is used in an amount less than 0.2 part by weight, there is a problem that the degree of whiteness is lowered due to the lack of an absolute amount of white to express high temperature generated during laser marking, and when used in excess of 1.0 part by weight, it acts as an excessive inorganic filler. There is a problem of lowering the impact strength of the resin.

The silicate compound is an inorganic or organic silane compound containing SiO ₂ or silicate. As the inorganic material containing the silicate, inorganic materials such as SiO ₂ , montmorillonite, hectorite, and saponite may be used alone or in a mixture.

In the present invention, the silicate compound forms a film on the resin surface when the laser light is irradiated to improve the whiteness of the marked text.

Laser marking method for producing a thermoplastic resin composition is a rubber having an average particle diameter of 0.1-0.2 ㎛ of the present invention (a ₁₎ 30-60 wt.% Of rubber (based on solids) and a mean particle diameter of 0.3-0.6 ㎛ (a ₂₎ 70 20-50 parts by weight of a rubbery polymer composed of -40% by weight (based on solids) is charged with ion exchange water, an emulsifier, a water-soluble co-initiator, a chelating agent, and a redox catalyst to a reaction vessel, and then the reactor temperature is 50-80 ° C. When the temperature in the reactor reaches the appropriate temperature, the monomer mixture 80-50 consisting of 10-40% by weight of an aromatic vinyl monomer, 3-20% by weight of an unsaturated nitrile monomer, and 40-80% by weight of an alkyl methacrylate monomer. It is prepared by graft polymerization by mixing parts by weight and continuously supplying 0.5-1.5 parts by weight of the molecular weight regulator mixture together with the monomer at a constant rate.

In the present invention, the polymerization temperature is not limited, and a range of 50-80 ° C. which is common conditions is appropriate. If the temperature is less than 50 ° C., the polymerization reaction rate is slow and not practical. On the other hand, if the polymerization temperature is 80 ° C. or more, the amount of coagulum is increased due to the deterioration of the stability of the polymerization system.

The invention can be better understood by the following examples, which are intended for the purpose of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

Example

Example 1

15 parts by weight of a polybutadiene rubber latex (a ₁ ) with an average particle diameter of 0.1-0.2 μm, with a stirring impeller, a temperature control thermometer, a mantle and a cooling water circulator in a 10L glass reaction vessel, and an average particle diameter of 0.3 20 parts by weight of polybutadiene rubber latex (a ₂ ) having a thickness of -0.6 μm (based on solids), 40 parts by weight of methyl methacrylate, 20 parts by weight of styrene, 5 parts by weight of acrylonitrile, 150 parts by weight of ion-exchanged water, potassium rosinate 0.7 parts by weight, tetrasodium ethylenediaminetetraacetate 0.3 parts by weight, sodium formaldehyde 0.4 parts by weight, ferrous sulfate 0.005 parts by weight, t-dodecyl mercaptan 0.5 parts by weight, alpha methyl styrene dimer 0.5 parts by weight in a reaction vessel and stirred well After raising the reactor internal temperature to 70 ℃ and proceeded with the reaction. When the reactor temperature reached the set temperature, 0.4 parts by weight of cumene hydroperoxide was added thereto for polymerization for 3 hours, and the reaction was terminated when the conversion rate reached 95%. The graft polymerization latex after the reaction was completed was cooled to room temperature, solidified, dehydrated and dried to obtain graft ABS powder. 0.2 parts by weight of carbon black, 0.4 parts by weight of titanium dioxide, and 0.5 parts by weight of silicon oxide were mixed together with a stabilizer and a lubricant, and then an ABS resin was prepared through melt extrusion and injection molding. Impact strength and the like of the prepared specimens were evaluated, and laser marking properties were evaluated using LBU2001 of Basel. The laser was Nd: YAG laser (wavelength 1.06 ㎛) and the results are shown in Table 1.

Example 2-5

The polymerization was carried out in the same manner as in Example 1, except that the amount of each component was changed as shown in Table 1.

Comparative Example 1-5

Specimens were prepared in the same manner as in Example 1-5 except for changing the composition of each component as described in Table 1.

Physical properties of the standard specimens prepared in Examples 1-5 and Comparative Examples 1-5 were measured, and the results are shown in Table 1.

Example Comparative example One 2 3 4 5 One 2 3 4 5 Rubber polymer (a ₁ ) 15 20 10 10 15 30 10 15 20 20 (a ₂ ) 20 15 25 25 20 10 30 20 15 15 Monomer MMA 40 33 46 40 49 40 10 40 40 40 SM 20 20 13 20 13 15 30 20 20 20 AN 5 13 7 5 3 5 20 5 5 5 Molecular weight regulator TDM 0.5 0.5 0.2 0.3 0.4 0.5 0.5 1.5 0.2 1.0 AMS 0.5 0.5 0.4 0.6 0.4 0.5 0.5 One 0.4 1.5 additive Carbon black 0.4 0.4 0.6 0.6 0.3 0.4 0.4 0.4 0.5 0.2 TiO ₂ 0.2 0.2 0.2 0.2 0.1 0.2 0.2 0.2 1.0 0.4 SiO ₂ 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0 2 Properties IZOD 20 21 20 20 20 10 12 11 20 12 Whiteness 0 0 0 0 0 0 0 0 4 4 definition 0 0 0 0 0 0 0 0 4 4

TDM: t-dodecyl mercaptan, AMS: alphamethylstyrene dimer.

(1) The graft ratio (%) and coagulum generation amount (%) of the polymer were respectively calculated by the following formulas.

(2) IZOD impact strength (kg · cm / cm) was based on ASTM D-256.

(3) Fluidity: Measured based on ASTM D1238.

(4) Laser marking property: The sharpness and whiteness of the marking were graded by Cheil Industries' own evaluation.

Marking clarity and whiteness Very good Good usually Inadequate Very poor Rating 0 One 2 3 4

From the results of Table 1, the impact strength of Comparative Example 1 in which the mixing ratio of the rubbery polymer is out of the range of the present invention and Comparative Example 2 in which the monomer mixing ratio is out of the range of the present invention are very low. Comparative Example 3 in which the mixing ratio of the molecular weight modifier is out of the range of the present invention can be seen that the impact strength is inferior, and the ratio of the black pigment and the white pigment is out of the scope of the present patent and the amount of the pigment input is excessive and the comparison is performed without using SiO ₂ It turns out that Example 4 falls in whiteness and sharpness. The use of the molecular weight regulator is beyond the scope of the present invention, Comparative Example 5 in which the ratio of black pigment and white pigment is added 1: 2 and excessively added SiO ₂ shows that impact strength is lowered and whiteness and clarity are lowered. have.

According to the present invention, a large diameter rubber and a small particle rubber are mixed and mixed at a predetermined ratio, and the composition of the copolymer monomer used in the graft emulsion polymerization step is appropriately combined with the combination ratio of carbon black and titanium dioxide during the compounding manufacturing process. Has the effect of the invention to provide a thermoplastic resin for white character laser marking excellent in impact and impact resistance.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (4)

(A) rubber having a mean particle size of 0.1-0.2 μm (a ₁ ) 30-60 wt% (based on solids) and rubber having a mean particle size of 0.3-0.6 μm (a ₂ ) 70-40 wt% (based on solids) 20-50 parts by weight of rubbery polymer; (B) 80-50 parts by weight of a monomer mixture consisting of 10-40% by weight of an aromatic vinyl monomer, 3-20% by weight of an unsaturated nitrile monomer, and 40-80% by weight of an alkyl methacrylate monomer; (C) 0.5-1.5 parts by weight of a molecular weight modifier consisting of mercaptans and terpinolenic or alpha methyl styrene oligomer in a ratio of 1: 1 to 1: 2; (D) 0.2-1.0 parts by weight of color pigments; And (E) 0.2-1.0 parts by weight of the silicate compound; A thermoplastic resin composition for laser marking, characterized in that consisting of. The thermoplastic resin composition according to claim 1, wherein the color pigment has a combination ratio of carbon black and white pigment at 2: 1 to 3: 1. The thermoplastic resin composition for laser marking according to claim 2, wherein the white pigment is selected from the group consisting of calcium carbonate, titanium oxide, zinc oxide, and zinc sulfide. According to claim 1, wherein the silicate-based compound is SiO ₂ , an inorganic or organic silane compound containing silicate, the inorganic material containing the silicate is SiO ₂ , montmorillonite, hectorite, saponite and mixtures thereof A thermoplastic resin composition for laser marking, which is selected from the group consisting of: