POLYPROPYLENE RESIN COMPOSITION FOR LASER WELDING AND MOLDED PRODUCT FOR VEHICLE INCLUDING THE SAME

Abstract

Disclose herein a polypropylene resin composition for laser welding, which includes a base resin, a thermoplastic elastomer, an inorganic filler, and an organic pigment. The base resin includes an isotactic polypropylene resin and an atactic polypropylene resin.

Claims

1. A polypropylene resin composition for laser welding, comprising: a base resin; a thermoplastic elastomer; an inorganic filler; and an organic pigment, wherein the base resin comprises an isotactic polypropylene resin and an atactic polypropylene resin.

2. The polypropylene resin composition of claim 1, wherein the atactic polypropylene resin is a random copolymer obtained by polymerization of a homopolypropylene resin with one comonomer selected from a group consisting of propylene, ethylene, butylenes, and octene, or a block copolymer of polypropylene and ethylene-propylene rubber.

3. The polypropylene resin composition of claim 1, wherein the atactic polypropylene resin has a weight-average molecular weight of 1,000,000 g/mol to 2,500,000 g/mol.

4. The polypropylene resin composition of claim 1, wherein the polypropylene resin composition comprises the base resin in an amount of 40 to 90 parts by weight, based on 100 parts by weight of the polypropylene resin composition.

5. The polypropylene resin composition of claim 1, wherein the base resin comprises an amount of 50 to 100 parts by weight of the atactic polypropylene resin, based on 100 parts by weight of the isotactic polypropylene resin.

6. The polypropylene resin composition of claim 1, wherein the thermoplastic elastomer comprises an olefin copolymer of ethylene and ?-olefin with a carbon number of 3 to 30, or a styrene-based copolymer.

7. The polypropylene resin composition of claim 1, wherein the polypropylene resin composition comprises the thermoplastic elastomer in an amount of 1 to 50 parts by weight, based on 100 parts by weight of the base resin.

8. The polypropylene resin composition of claim 1, wherein the inorganic filler is formed in a needle shape, and has a mean diameter of 3 to 20 ?m and an aspect ratio of 10 to 100.

9. The polypropylene resin composition of claim 1, wherein the polypropylene resin composition comprises the inorganic filler in an amount of 1 to 50 parts by weight, based on 100 parts by weight of the base resin.

10. The polypropylene resin composition of claim 1, wherein the polypropylene resin composition comprises the organic pigment in an amount of 0.01 to 1 parts by weight, based on 100 parts by weight of the base resin.

11. The polypropylene resin composition of claim 1, further comprising at least one of an antioxidant, a photostabilizer, a thermal stabilizer, and an antistatic agent.

12. A molded product for a vehicle, comprising the polypropylene resin composition for laser welding of claim 1.

13. The molded product of claim 12, wherein the polypropylene resin composition the molded product implements a color to the molded product.

14. The molded product of claim 12, wherein the molded product has a laser transmittance from 30% to less than 100%, and a welding strength of 1000 to 2000 N.

15. A vehicle comprising a molded product of claim 12.

Description

EXAMPLE

[0073] Hereinafter, the present invention will be described in more with reference to specific examples. The following examples are illustrated merely to help understanding of the present invention, and the present invention is not limited thereto.

Example 1

[0074] A polypropylene resin composition was manufactured to include a base resin, which includes JSS-370N (PP, LOTTE Chemical Corp.) as an isotactic polypropylene resin, and UHMW aPP (melting index of 1.5 g/min, LOTTE Chemical Corp.) as an atactic polypropylene resin with a weight-average molecular weight of 1,000,000 g/mol, G-1643 as (SEBS, kraton light transmittance of 65) as a thermoplastic elastomer A, and MICA (d50 12 ?m, aspect ratio of 35) as an inorganic filler A.

[0075] The isotactic polypropylene resin, the atactic polypropylene resin, the thermoplastic elastomer A, the inorganic filler, and the organic pigment were mixed at a ratio of 44:25:15:15:1 parts by weight. The organic pigment was mixed to implement a black color.

[0076] The polypropylene resin composition was extruded under the extrusion condition of an extrusion temperature of 160 to 210? C. and a screw rotation speed of 500 rpm by a two-axis extruder (screw diameter of 32 mm, L/D of 40) to form a specimen using an injection molding machine.

Example 2

[0077] A polypropylene resin composition was manufactured in the same manner as Example 1, except that an isotactic polypropylene resin, an atactic polypropylene resin, a thermoplastic elastomer A, an inorganic filler, and an organic pigment were mixed at a ratio of 54:15:15:15:1 parts by weight.

Comparative Example 1

[0078] A polypropylene resin composition was manufactured in the same manner as Example 1, except for mixing 59 parts by weight of UHMW aPP (melting index of 1.5 g/min, LOTTE Chemical Corp.) as an atactic polypropylene resin with a weight-average molecular weight of 1,000,000 g/mol, and 10 parts by weight of JSS-370N (PP, LOTTE Chemical Corp.) as an isotactic polypropylene resin.

Comparative Example 2

[0079] A polypropylene resin composition was manufactured in the same manner as Example 1, except for mixing 15 parts by weight of talc with a mean diameter of 4 ?m as an inorganic filler B instead of an inorganic filler A.

Comparative Example 3

[0080] A polypropylene resin composition was manufactured in the same manner as Example 1, except for mixing 15 parts by weight of DF640 as a thermoplastic elastomer B.

TABLE-US-00001 TABLE 1 Comp. Comp. Comp. Sort Ex. 1 Ex. 2 Ex. 1 Ex. 2 Ex. 3 Isotactic PP Parts by 44 54 10 44 44 weight Atactic PP Parts by 25 15 59 25 25 weight Thermoplastic Parts by 15 15 15 15 elastomer A weight Thermoplastic Parts by 15 elastomer B weight Inorganic Filler A Parts by 15 15 15 15 weight Inorganic Filler B Parts by 15 weight Organic Pigment Parts by 1 1 1 1 1 weight

Evaluation

Test Example 1

Specific Gravity

[0081] The specific gravities of the specimens obtained from Examples 1 and 2 and Comparative examples 1 to 3 were measured according to ASTM D792, and their results are indicated in the following Table 2.

Test Example 2

Melting Index (g/10 min)

[0082] The melting indexes of the polypropylene resin compositions obtained from Examples 1 and 2 and Comparative examples 1 to 3 were measured at a temperature of 230? C. and under a load of 2.16 kg according to ASTM D1238, and their results are indicated in the following Table 2.

Test Example 3

Tensile Strength

[0083] The tensile strengths of the specimens obtained from Examples 1 and 2 and Comparative examples 1 to 3 were measured at a temperature of 23? C. according to ASTM D638 wherein the standard of each specimen is 165?13?3.2 mm and a crosshead has a speed of 50 mm/min, and their results are indicated in the following Table 2.

Test Example 4

Modulus of Flexural Elasticity

[0084] The moduli of flexural elasticity of the specimens obtained from Examples 1 and 2 and Comparative examples 1 to 3 were measured according to ASTM D790 wherein the standard of each specimen is 12.7?127?6.4 mm and a crosshead has a speed of 10 mm/min, and their results are indicated in the following Table 2.

Test Example 5

IZOD Impact Strength

[0085] The IZOD impact strengths of the specimens obtained from Examples 1 and 2 and Comparative examples 1 to 3 were measured at room temperature (23? C.) according to ASTM D256 wherein the standard of each specimen is 63.5?12.7?6.4 mm, and their results are indicated in the following Table 2.

Test Example 6

Transmittance

[0086] The specimens obtained from Examples 1 and 2 and Comparative examples 1 to 3 were measured wherein the standard of each specimen is 60?60?1.5 mm, a laser irradiation wavelength was 980 nm?2%, an irradiation power was 10 mW?2%, and an irradiation distance (distance between a light source and a specimen) was 48?2 mm, and their results are indicated in the following Table 2.

Test Example 7

Bond Strength

[0087] The bond strengths of the specimens such as those of Test Example 6 obtained from Examples 1 and 2 and Comparative examples 1 to 3 were measured under the condition that a maximum load was in the range of a load cell of 15 to 85% by a tensile tester in the state in which the overlap portions of a transmissive material and an absorbent material were welded with laser. The bond strengths of the specimens were measured under the welding condition that a wavelength is 980 nm?2%, a power was 200 W, and a speed was 10 m/s, at an inter-clamp distance of 60 mm, and at a tension speed of 50 mm/min, and their results were indicated in the following Table 2.

Test Example 8

External Appearance of Weld Intersection

[0088] The laser welding portion of the specimen manufactured in Test Example 6 was observed by an optical microscope with ?50 magnifications, and a minimum of three different surfaces are cut to expose the intersection of the welding portion and then whether each of the cut surfaces is defective is checked. Their results are indicated in the following Table 2.

TABLE-US-00002 TABLE 2 Comp. Comp. Comp. Sort Ex. 1 Ex. 2 Ex. 1 Ex. 2 Ex. 3 Melting Index g/10 29 29 6.5 26 28 min Specific Gravity 1 1 1 1 1 Tensile Strength MPa 20.1 20.1 18.9 21 19.2 Modulus of MPa 2,160 2,360 1,600 2,120 1,780 Flexural Elasticity IZOD (@23? C.) J/m 311 281 429 284 314 Transmittance % 39 34 55 24 26 Bond Strength N 1191 1081 1289 841 845 External N Good Good Good Wrinkle Not Appearance of Defor- welded, Weld Intersection mation Crack

[0089] As indicated in the Table 2, when the atactic polypropylene resin with a high weight-average molecular weight was not used, the laser transmittance was low and the strength of the welding portion is reduced. When each component was included alone in the composition, the properties such as tensile strength, modulus of flexural elasticity, and impact strength of the molded product manufactured of the polypropylene resin composition were not evenly satisfied. In addition, the materials of Comparative Examples 2 and 3 were not suitable for a material for laser welding since the light transmittance of the molded product was low and the bond strength and external appearance of the laser welding portion occurred due to the difference in light transmittance of the selected inorganic filler and thermoplastic elastomer even though mechanical properties are excluded.

[0090] On the other hand, in Examples 1 and 2 of including both the isotactic polypropylene resin and the atactic polypropylene resin, they had a high light transmittance over 30% while having excellent mechanical properties, and high bond strength, and the external appearance of the welding portion was excellent.

[0091] According to various exemplary embodiments of the present invention, the polypropylene resin composition for laser welding may be suitable for laser welding, have high transmittance while keeping mechanical strength high, and implement a color.

[0092] The molded product for a vehicle according to various exemplary embodiments of the present invention may have high transmittance while keeping mechanical strength high, and implement a color.

[0093] The invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.