WO2020051524A1

WO2020051524A1 - Vehicle headlight assembly

Info

Publication number: WO2020051524A1
Application number: PCT/US2019/050053
Authority: WO
Inventors: Hiroyuki Sumi
Original assignee: Dupont Polymers, Inc.
Priority date: 2018-09-07
Filing date: 2019-09-06
Publication date: 2020-03-12

Abstract

This invention relates to a vehicle headlight assembly. A vehicle headlight assembly comprises a light source, a housing supporting the light, a bezel equipped over the front side of the housing, and a transparent cover being equipped over the front side of the bezel, wherein the bezel and optionally the housing comprises 100 parts by weight of a thermoplastic resin and 0.05 to 3.0 parts by weight of a carbon nano tube as a black pigment.

Description

TITLE

VEHICLE HEADLIGHT ASSEMBLY

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to US Provisional Application. Serial No. 62/728,232 filed on September 7, 2018, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The invention relates to a vehicle headlight assembly, more specifically to a bezel used thereof.

TECHNICAL BACKGROUND OF THE INVENTION

A vehicle headlight assembly contains a light, a housing, a bezel and a cover. A bezel of a dark color is requried.

WO2017165263 discloses a vehicle headlight assembly that comprises a light source, a housing supporting the light, a bezel equipped over the front side of the housing, and a transparent cover being equipped over the front side of the bezel. The bezel comprises a thermoplastic resin and a colorant selected from the group consisting of an anthraquinone dye, an amine salt thereof and a mixture thereof.

BRIEF SUMMARY OF THE INVENTION An objective is to provide a vehicle headlight assembly with sufficient blackness.

An aspect of the invention relates to a vehicle headlight assembly

comprising: a light source, a housing supporting the light, a bezel equipped over the front side of the housing, and a transparent cover being equipped over the front side of the bezel, wherein the bezel and optionally the housing comprises 100 parts by weight of a thermoplastic resin and 0.05 to 3.0 parts by weight of a black pigment comprising a carbon nano tube.

Another aspect of the invention relates to a vehicle bezel comprising 100 parts by weight of a thermoplastic resin and 0.05 to 3.0 parts by weight of a carbon nano tube as a black pigment.

Another aspect of the invention relates to a method of manufacturing a vehicle headlight assembly comprising steps of: preparing a thermoplastic resin composition comprising 100 parts by weight of a thermoplastic resin and 0.05 to 3.0 parts by weight of a black pigment comprising carbon nano tube; and forming a bezel by injection-molding the resin composition; equipping the bezel on the front side of a housing holding a light; and equipping a transparent cover on the front side of the bezel.

A vehicle headlight assembly comprising a bezel with sufficient blackness can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts one embodiment of a vehicle headlight assembly.

DETAILED DESCRIPTION OF THE INVENTION

The vehicle headlight assembly comprises a light, a housing, a bezel and a transparent cover. FIG. 1 illustrates one example of the vehicle headlight assembly 100. The housing 105 holds a light 101 . The light 101 contains at least one light source 103. The bezel 111 is equipped on the front side of the housing 105. “Front side” is a side facing toward the front of the vehicle. The bezel 111 has holes 113 that the lights 101 fit in. The transparent cover 121 is equipped on the front side of the bezel 111 to cover the lights 113. The bezel 111 is black. The bezel 111 comprises a thermoplastic resin and a black pigment comprising CNT. The bezel 111 is not plated with a metal in another embodiment. The bezel 111 is formed by injection-molding a thermoplastic resin composition. The thermoplastic resin composition comprises a thermoplastic resin and carbon nano tube as a black pigment.

The housing 105 is black as well in another embodiment. The housing 105 comprises a thermoplastic resin and a black pigment comprising CNT. The housing

105 is not plated with a metal in another embodiment. The housing 105 is formed by injection-molding the thermoplastic resin composition in an embodiment.

Crystallization temperature (Tc) of the thermoplastic resin composition is 196 °C or higher in an embodiment, 199 °C or higher in another embodiment, 200 °C or higher in an embodiment.

Thermoplastic Resin

There is no restriction on the thermoplastic resin. A wide range of thermoplastic resin useful for molding is available. The black pigment is dispersed into the thermoplastic resin to form a resin composition.

The thermoplastic resin is selected from the group consisting of polyamide, polyester, polyphenylene sulfide, polyacetal, polycarbonate, polysulfone,

polyethylene, polyether sulfone, methacrylate, polyamide-imide, fluoroplastic and a mixture thereof in an embodiment. The thermoplastic resin can be selected from the group consisting of polyamide, polyester and a mixture thereof in another embodiment. The thermoplastic resin comprises a polyester resin in another embodiment.

The polyamide resin is a condensation product of dicarboxylic acids and diamines, a condensation product of aminocarboxylic acids and ring-opening polymerization products of cyclic lactams in an embodiment. The dicarboxylic acids of polyamide can be adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, isophthalic acid and terephthalic acid in an embodiment. The diamine can be tetramethylene diamine, hexamethylene diamine, octamethylene diamine, nonamethylene diamine, dodecamethylene diamine, 2-methylpentamethylene diamine, 2-methyloctamethylene diamine, trimethylhexamethylene diamine, bis(p- aminocyclohexyl)methane, m-xylene diamine and p-xylene diamine in an

embodiment. The aminocarboxylic acid can be 11-aminododecanoic acid in an embodiment. The cyclic lactam can be caprolactam or laurolactam in an

embodiment. Condensation products and ring-opening polymerization products can be aliphatic polyamide, semi-aromatic polyamide, copolymer thereof or a mixture thereof in another embodiment. The polyamide resin can be selected from the group consisting of nylon 6, nylon 66, nylon 46, nylon 610, nylon 612, nylon 11 , and nylon 12, polymetaxylene adipamide (nylon MXD6), polyhexamethylene

terephthalamide (nylon 6T), polyhexamethylene isophthalamide (nylon 61 ) a polynonamethylene terephthalamide (nylon 9T), nylon 6/66, nylon 66/6I, nylon 6I/6T, nylon 66/6T and a mixture thereof in another embodiment.

The polyester resin is a condensation product of dicarboxylic acids and diols in an embodiment. Dicarboxylic acids of polyester can be selected from the group consisting of adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and diphenyl dicarboxylic acid in an embodiment. Diols can be selected from the group consisting of ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, cyclohexanediol, and bisphenol A in an embodiment.

The polyester is selected from the group consisting of polyethylene terephtalate (PET), polybutylene terephthalate (PBT), Polytrimethylene terephthalate (PTT), polyethylene 2,6-naphthalate (PEN), polybutylene naphthalate (PBN), polycyclohexane dimethylene terephthalate (PCT), a copolymer thereof and a mixture thereof in an embodiment. Examples of the copolymers are some of dicarboxylic acids or some of diols. Polyester may be copolymerized a little amount of components like trimesic acid, trimellitic acid, pyromellitic acid, glycerol, and pentaerythritol which have more than three functional groups in another embodiment.

The thermoplastic resin can be 50 to 99.95 wt. % based on the weight of the thermoplastic resin composition in an embodiment. The thermoplastic resin is 60 wt. % or more in another embodiment, 70 wt. % or more in another embodiment, 80 wt. % or more in another embodiment, 90 wt. % or more in another embodiment, 95 wt. % or more in another embodiment, 99 wt. % or more in another embodiment based on the weight of the resin composition. The thermoplastic resin can be 99.9 wt. % or less in an embodiment, 99 wt. % or less in another embodiment based on the weight of the resin composition.

Black Pigment

The black pigment comprises a carbon nanotube (CNT). The carbon nanotube is an allotrope of carbon with a cylindrical structure with a graphene sheet as a wall which is one-atom-thick sheets of carbon. The carbon nanotube is constructed with length-to-diameter (length: diameter) ratio of 100:1 to 50,000:1 in an embodiment, 300:1 to 10,000:1 in another embodiment, 600:1 to 5,000:1 in another embodiment, 800:1 to 3,000:1 in another embodiment.

The average diameter of the carbon nanotube is 0.1 to 100 nm in an embodiment, 1 to 80 nm in another embodiment, 3 to 60 nm in another embodiment, 5 to 40 nm in another embodiment, 8 to 25 nm in another embodiment. The average length of the carbon nanotube is 0.1 to 100 micron in an embodiment, 1 to 80 micron in another embodiment, 3 to 60 micron in another embodiment, 5 to 40 micron in another embodiment, 8 to 25 micron in another embodiment. The carbon nanotube with the size above would be advantageous to dispersivility in the resin. The diameter and the length can be measured by observing at least 50 of carbon nanotubes with an electron microscope such a scanning electron microscope (SEM) and transmission electron microscope (TEM). There is no restriction on the carbon nanotube. Any carbon nanotube of a commercialized product can be available.

The carbon nanotube can be a basic CNT or an acid CNT in an embodiment. The pH at 20 °C. of an aqueous dispersion of the basic CNT is more than 7.0. The pH at 20 °C. of an aqueous dispersion of the acid CNT is lower than 7.0.

The black pigment can further comprise an additional pigment besides the black pigment in an embodiment. The additional pigment can be selected from the group consisting of an azo dye, perinone dye, carbon black and a mixture thereof in an embodiment.

The black pigment can be 3 parts by weight or less in an embodiment, 2.5 parts by weight or less in another embodiment, 2.1 parts by weight or less in another embodiment, 1.5 parts by weight or less in another embodiment, 1.1 parts by weight or less, 0.8 parts by weight or less in another embodiment, 0.5 parts by weight or less in another embodiment, as the thermoplastic resin is 100 parts by weight. The black pigment can be 0.05 parts by weight or more in an embodiment, 0.09 parts by weight or more in another embodiment, 0.2 parts by weight or more in another embodiment, 0.5 parts by weight or more in another embodiment, 0.8 parts by weight or more in another embodiment, as the thermoplastic resin is 100 parts by weight.

Inorganic Filler The bezel and optionally the housing can further comprise inorganic filler in an embodiment. The inorganic filler is a thermal conductive filler in an embodiment. The thermal conductive filler is selected from the group consisting of talc, kaolin, wollastonite, silica, silicon, calcium carbonate, potassium titanate, mica, magnesium oxide, calcium fluoride and a mixture thereof in another embodiment. The thermally conductive filler is selected from the group consisting of talc, mica, kaolin and a mixture thereof in another embodiment. The bezel and optionally housing comprises no inorganic filler in another embodiment.

The inorganic filler is 1 to 80 parts by weight in an embodiment, 3 to 70 parts by weight in an embodiment, 4 to 50 parts by weight in another embodiment, 5 to 25 parts by weight in another embodiment as the thermoplastic resin is 100 parts by weight.

The inorganic filler can be a reinforcing agent in another embodiment. The reinforcing agent can be selected from the group consisting of a glass fiber, a carbon fiber, a glass flake, a glass bead and a mixture thereof in an embodiment. The reinforcing agent can be a glass fiber in another embodiment.

Additive

One or more optional compounds selected from a wide variety of materials tailored for different applications of the resin compositions can be contained in the composition according to the present invention. Typically, additive compounds can include flame retardants, impact modifiers, viscosity modifiers, heat resistance improvers, lubricants, antioxidants and UV-and other stabilizers. The compositions of the present invention may have such additive compounds in such amounts that they do not harm their characteristic properties. These and other additives are used in accordance with accepted practices as understood by those having skill in the art. Resin Composition

The thermoplastic resin and the black pigment are mixed together to form a thermoplastic resin composition in an embodiment. The thermoplastic resin composition is extruded in the form of strands, cooled, chopped into granules to form pellets of the polyester resin composition in an embodiment. The thermoplastic resin composition is molded into a shape of the bezel and/or the housing.

EXAMPLES

The present invention is illustrated by, but is not limited to, the following examples.

The thermoplastic resin composition was prepared with the following procedure. 100 parts by weight of PBT pellets (Crastin^®, E.l. DuPont de Nemours and Co.), 0.2 to 1 .0 parts by weight of a black pigment and 0.4 parts by weight of a lubricant were mixed in a stainless tumble mixer with stirring for 15 minutes. The amount of these materials is shown in Table 1. The black pigment was a micron size carbon black, a carbon nanotube (average dinameter:12 nm, average length: 10 micron, PBT-based CNT masterbatch CP-240-10, Cnano Technology Limited) or a black dye. The black dye was a mixture of an anthraquinone blue dye (C. I. Solvent blue 87), an anthraquinone yellow dye (C. I. Solvent yellow 163) and a perinone dye (C. I. Solvent red 179). The mixed materials prepared above were mixed in a twin screw extruder to make a polyester resin composition. The barrel temperature was set at approximately 260 °C. The polyester resin composition was extruded in the form of strands, cooled, chopped into granules to form polyester resin pellets. The resin composition was then injection molded to form a plate, 100 mm wide, 100 mm long and 2 mm thick, using 180t-electric injection molding machine. The cylinder temperature was set to 260 °C. Mold temperature was 60 °C.

Measurement

Crystallization temperature (Tc) of the pellet above was measured by a differential scanning calorimetry (DSC) (DSC Q100, TA-lnstruments) according to ISO 3146. The resin composition having a higher Tc can be molded with a shorter- cycle time.

Color L^* value of the plate was measured by a color meter (ColorFlex 45/0 Spectrophotometer, HunterLab Instruments) according to ISO 7724/1.

Volume resistivity of the plates was measured by a resistivity meter

(Hiresta-UP, Mitsubishi Chemical Analytech) according to ISO 2951.

Results

The result is shown in Table 1 . Crystallization temperature (Tc) was over

200 °C when using CNT as a black pigment in Example 1 to 3 while it’s below 200 °C when using the carbon black in Comparative Example 1 to 4. L^* value was 4.1 , 2.9 and 2.5 sufficiently low in Example 1 to 3 while it’s 7.0 or higher in Comparative Example 1 to 4. The volume resistivity was 1x10¹⁴ ohm -cm sufficiently high in both Examples and Comparative Examples.

Further, CNT is known as an additive to increase electronic conductivity of a resin composition. However, existed art would teach to increase electronic conductivity, a larger amount of CNT is needed. This is in contrast compared with the amount in the present invention; see Table 1. Resistivity of Examples 1 -3 and Comparative Example 4 are the same (>1x10¹⁴ ohm -cm), therefore, as provided in the present invention, 0.3-1.0 parts by weight of CNT does not increase electronic conductivity of the resin composition. No prior art discloses a resin composition comprising such small amount of CNT; distinguishing the present invention. This results in the composition of the present invention, or an article formed from the composition, would have properties including a lower L value (compare with carbon black) recognizing the black color is darker / deeper, a higher Tc

(crystallization temperature) contributing easier processability (short cycle time) when the article is formed by injection-molding and a higher mechanical property (as provided in Table 1 ).

Table 1

Claims

CLAIMS What is claimed is:

1. A vehicle headlight assembly comprising:

a light source,

a housing supporting the light,

a bezel equipped over the front side of the housing, and

a transparent cover being equipped over the front side of the bezel,

wherein the bezel and optionally the housing comprises 100 parts by weight of a thermoplastic resin and 0.05 to 3.0 parts by weight of a black pigment comprising a carbon nano tube.

2. The vehicle headlight assembly of claim 1 , wherein the thermoplastic resin comprises polyamide, polyester, polyphenylene sulfide, polyacetal, polycarbonate, polysulfone, polyethylene, polyether sulfone, methacrylate, polyamide-imide, fluoroplastic and a mixture thereof.

3. The vehicle headlight assembly of claim 1 , wherein the thermoplastic resin comprises a polyester resin.

4. The vehicle headlight assembly of claim 1 , wherein the thermoplastic resin comprises a polybutylene terephthalate (PBT) resin.

5. The vehicle headlight assembly of claim 1 , wherein diameter of the carbon nanotube is 1 to 100 nm.

6. The vehicle headlight assembly of claim 1 , wherein L^* value of the bezel is 5.0 or lower.

7. The vehicle headlight assembly of claim 1 , wherein volume resistivity of the bezel is 1x10¹³ ohm -cm or higher.

8. A bezel comprising 100 parts by weight of a thermoplastic resin and 0.05 to 3.0 parts by weight of a carbon nano tube as a black pigment.

9. The bezel of claim 8, wherein the thermoplastic resin comprises polyamide, polyester, polyphenylene sulfide, polyacetal, polycarbonate, polysulfone, polyethylene, polyether sulfone, methacrylate, polyamide-imide, fluoroplastic and a mixture thereof.

10. The bezel of claim 8, wherein the thermoplastic resin comprises a polyester resin.

11. The bezel of claim 8, wherein the thermoplastic resin comprises a polybutylene terephthalate (PBT) resin.

12. The bezel of claim 8, wherein diameter of the carbon nanotube is 1 to 100 nm.

13. The bezel of claim 8, wherein L^* value of the bezel is 5.0 or lower.

14. The bezel of claim 8, wherein volume resistivity of the bezel is 1x10¹³ ohm -cm or higher.

15. A method of manufacturing a vehicle headlight assembly comprising steps of: preparing a thermoplastic resin composition comprising 100 parts by weight of a thermoplastic resin and 0.05 to 3.0 parts by weight of a black pigment comprising carbon nano tube; and

forming a bezel by injection molding the thermoplastic resin composition; equipping the bezel on the front side of a housing holding a light; and equipping a transparent cover on the front side of the bezel.

16. The method of 15, wherein crystallization temperature (To) of the thermoplastic resin composition is 196 °C or higher.

17. A resin composition comprising (a) 100 parts by weight of a thermoplastic resin and (b) 0.05 to 1.1 parts by weight of a black pigment comprising carbon nanotube.