KR20090072836A - A thermoplastic resin composition and a helmet manufactured by using the same - Google Patents

Abstract

A thermoplastic resin composition is provided to ensure excellent flexural modulus and shock resistance, low specific gravity, and excellent fluidity, and to prepare manufacture high value added helmet while satisfying standard for safety. A thermoplastic resin composition comprises polycarbonate resin 45~74 weight%, styrene/acrylonitrile resin 10~20 weight%, acrylonitrile/butadiene/styrene resin 15~25 weight% and polymethylmethacrylate 1~10 weight%. The molecular weight of the polycarbonate resin is 18,000~30,000. The average molecular weight of the styrene/acrylonitrile resin is 50,000~300,000.

Description

Thermoplastic resin composition and helmet manufactured using the same {A THERMOPLASTIC RESIN COMPOSITION AND A HELMET MANUFACTURED BY USING THE SAME}

The present invention relates to a thermoplastic resin composition and a helmet manufactured using the same, and more particularly, excellent impact strength, high flexural modulus, low specific gravity, which can lower the weight of the final molded product, and is particularly suitable for a motorcycle helmet. A resin composition and a helmet manufactured using the same.

Polycarbonate (PC) resin has excellent impact strength, heat resistance and transparency, but lacks fluidity, making it difficult to form, low temperature impact strength, and lack of chemical resistance.

In order to overcome this disadvantage, PC resin was developed by blending PC resin with acrylonitrile / butadiene / styrene resin (ABS resin), which not only possesses the excellent properties of conventional PC resin, Low temperature impact resistance, chemical resistance, moldability, etc., which were disadvantages, have been improved, and are currently widely used for automotive plastic materials, housings, helmets, and the like for electric and electronic products.

In order to reduce the weight of a helmet (for example, a motorcycle helmet), an attempt has been made to increase the content of ABS having a relatively low density in PC / ABS, but in this case, the density of the material is lowered, but mechanical properties, particularly flexural modulus, are lowered. Therefore, in order to pass the safety standards of the helmet, the thickness of the helmet shell (shell) must be increased, and as a result, it can be said that there was no weight reduction effect.

Therefore, there is a demand for the development of a resin composition that enables the manufacture of a helmet that is light in weight while having excellent flexural modulus and impact resistance enough to pass safety standards.

The present invention is to solve the problems of the prior art as described above, the present invention has excellent flexural modulus and impact resistance, but also a lower density resin composition, in particular excellent flexural modulus and impact resistance that satisfies the helmet safety standards It is a technical problem to provide a resin composition capable of manufacturing a helmet having a lower density and a lighter weight compared to a resin that has been used for a helmet, and a helmet manufactured using the same.

In order to achieve the above object, the present invention provides a polycarbonate resin of 45 to 74% by weight, 10 to 20% by weight of styrene / acrylonitrile resin, 15 to 25% by weight of acrylonitrile / butadiene / styrene resin, and polymethylmethacrylate. It provides a thermoplastic resin composition comprising 1 to 10% by weight.

According to another aspect of the invention, there is provided a helmet comprising a shell (shell) made of the thermoplastic resin composition. As used herein, the term "shell" refers to the main body of the helmet, which is not simply a function of the outer shell as a component that plays the most important role in blocking / absorbing shock from the outside in case of a helmet wearer's accident.

Since the resin composition according to the present invention has excellent flexural modulus and impact resistance and low specific gravity, it can produce a high value-added helmet with light weight while satisfying safety standards. In addition, since the resin composition according to the present invention has excellent fluidity, it may be used to manufacture molded articles having a more complicated shape, and may be applied to other electric and electronic parts or automobile parts in addition to helmets.

Hereinafter, the present invention will be described in detail.

As the polycarbonate (PC) resin included in the resin composition of the present invention, a conventional polycarbonate resin is used. Preferably, a linear polycarbonate resin, a branched polycarbonate resin, a polyester-carbonate resin and a silicone-based resin are copolymerized. At least one aromatic polycarbonate resin selected from the group consisting of copolycarbonates can be used.

The viscosity average molecular weight of the PC resin is preferably 18,000 to 30,000. If the viscosity average molecular weight of the PC resin is less than 18,000, there may be a problem that the impact strength of the molded shell is low due to the impact test crack, and if it exceeds 30,000, there is a problem that the unmolding occurs because the viscosity is too high during shell molding There may be.

The said PC resin is 45-74 weight%, Preferably it is 55-65 weight%, More preferably, 60-65 weight% is contained in the resin composition of this invention. If the amount of PC resin in the resin composition is less than 45% by weight, the impact strength is low and the shell is not only broken, but there is a problem that the flexural modulus is lowered to satisfy the safety standard of the helmet. There is a problem of unmolding at the time of molding of the shell due to the deterioration of fluidity and there is a problem of increasing the weight of the helmet itself by increasing the specific gravity.

Although there is no particular limitation on the content of acrylonitrile contained in the styrene / acrylonitrile (SAN) resin included in the resin composition of the present invention as a polymerization unit, preferably 25 to 40% by weight of acryl is contained in 100% by weight of the SAN resin. Nitrile is included as polymerized unit. If the acrylonitrile content in the 100% by weight of the SAN resin is less than 25% by weight may be a problem that the heat resistance of the resin is lowered, if the content exceeds 40% by weight, the compatibility of ABS and blending is lowered to reduce the impact strength There may be.

The weight average molecular weight of the SAN resin is preferably 50,000 to 300,000. If the weight average molecular weight of the SAN resin is less than 50,000, there may be a problem that the impact strength and heat resistance is lowered, and if the weight average molecular weight exceeds 300,000, the viscosity of the resin is too high may be difficult to form the shell.

The resin composition of the present invention contains 10 to 20% by weight of the SAN resin, preferably 12 to 18% by weight, more preferably 13 to 15% by weight. If the amount of the SAN resin in the resin composition is less than 10% by weight, the bending modulus of the final resin composition is lowered, which may not satisfy the safety standard of the helmet. If the amount is more than 20% by weight, the impact strength of the final resin composition is lowered. There is.

The acrylonitrile / butadiene / styrene (ABS) resin included in the resin composition of the present invention preferably has a core-shell structure in which acrylonitrile / styrene resin is grafted to butadiene. There is no particular limitation on the acrylonitrile content included as the polymerized unit in the grafted acrylonitrile / styrene resin, and it is preferable that it is 25 to 40% by weight in 100% by weight of acrylonitrile / styrene resin.

The butadiene content included in the ABS resin is not particularly limited, and is usually 40 to 60% by weight in 100% by weight of the ABS resin.

The particle size of the butadiene is preferably 0.1 ~ 0.3 micrometers. If the particle size of butadiene is less than 0.1 micrometer, the impact strength reinforcing effect may not be sufficient, and the impact strength may be lowered. If the particle size of the butadiene is more than 0.3 micrometer, the dispersibility may be lowered and the impact strength may also be lowered. have.

The resin composition of the present invention contains 15 to 25% by weight of the ABS resin, preferably 16 to 12% by weight, more preferably 18 to 20% by weight. If the amount of the ABS resin in the resin composition is less than 15% by weight, there is a problem that the impact strength is lowered, and when the amount of the ABS resin exceeds 25% by weight, the flexural modulus is lowered and there is a problem that does not pass the safety standard of the helmet.

It is preferable that the weight average molecular weight of polymethyl methacrylate (PMMA) contained in the resin composition of this invention is 50,000-200,000. If the weight average molecular weight of PMMA is less than 50,000, the fluidity is high, but there may be a problem of lowering the impact strength of the final resin composition. If it exceeds 200,000, the impact strength of the final resin composition may not be evenly dispersed during melt processing because the viscosity of PMMA is too high. There may be a problem with little reinforcing effect.

1-10 weight% of said PMMA, Preferably it is 2-8 weight%, More preferably, 4-5 weight% is contained in the resin composition of this invention. If the amount of PMMA in the resin composition is less than 1% by weight, there is little problem in raising the bending modulus of the final resin composition, and if it exceeds 10% by weight, there is a problem of lowering the impact strength of the final resin composition.

In the resin composition of the present invention, additives such as phosphite-based antioxidants, stearate-based or fatty acid-based lubricants, or conventional UV stabilizers and mold release agents may be used alone within the range capable of achieving the object of the present invention in addition to the above-described components. Alternatively, two or more kinds thereof may be mixed and used, and may be included in an amount of 0.1 to 2 parts by weight, per 100 parts by weight of the resin composition.

The resin composition of the present invention may be prepared by a conventional method of mixing and extruding the components as described above with an extruder, but is not limited thereto. In addition, the resin composition of the present invention may be molded by a conventional method such as injection molding, but is not limited thereto. According to one embodiment of the present invention, by using a twin screw extruder (twin screw extruder) mixed extrusion of the components as described above, after drying for 6 hours at 100 ℃ can be produced the desired molded article.

The resin composition of the present invention can be suitably used particularly as a material of a helmet, preferably a motorcycle helmet. Accordingly, according to another aspect of the present invention, there is provided a helmet comprising a shell made of the thermoplastic resin composition.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the following Examples are only illustrative to help understanding of the present invention, but the present invention is not limited thereto.

Example  And Comparative example

By using a twin screw extruder (twin screw extruder) in a composition as shown in Table 1, the compositions of Examples 1 and 2 and Comparative Examples 1 and 2 were mixed and extruded, and after injection molding at 100 ℃ 6 hours.

TABLE 1

PC Resin: Samyang Corporation TRIREX 3022PJ

SAN Resin: Kumho Petrochemical SAN360A

ABS resin: Kumho Petrochemical HR150F

PMMA Resin: LG Chem IH830

For each specimen obtained by injection molding, specific gravity was measured with a specific gravity meter (SD-200L, Mirage), flexural modulus was measured with UTM (Instron), and impact strength was measured with an Izod impact tester (CEAST).

On the other hand, the weight of the PC / ABS helmet (shell) shell manufactured by injection molding the resin composition of each of Examples and Comparative Examples was measured by electronic balance. The molded shell was tested in accordance with the Snell M2005 impact management test standard, and then it was determined whether or not it could be used as a motorcycle helmet. Measurement and judgment results are shown in Table 2 below.

TABLE 2

As can be seen in Table 2, in Examples 1 and 2 according to the present invention, the flexural modulus was 19,000 or more and the impact strength was 40 or more. The weight of the helmet shell was 861g and 875g, respectively, and the results of the Snell impact management test were all passed. When the PC content is the same as 65% but PMMA is added (Example 2) and when it is not (Comparative Example 2), it was found that the addition of PMMA was higher in both flexural modulus and impact strength. This is because PMMA itself has a high flexural modulus and PMMA acts as a compatibilizer between PC and ABS, increasing the compatibility of the resin blend. In the case of Comparative Example 2, the reason for failing as a result of the Snell impact management test is considered to be due to the low bending modulus. In Comparative Example 1, the PC content was relatively high, the flexural modulus and impact strength were high, and the result of the Snell impact management test was also passed. Did not fit at all.

Claims (7)

Thermoplastic comprising 45-74 wt% polycarbonate resin, 10-20 wt% styrene / acrylonitrile resin, 15-25 wt% acrylonitrile / butadiene / styrene resin, and 1-10 wt% polymethyl methacrylate Resin composition. The thermoplastic resin composition of claim 1, wherein the polycarbonate resin has a viscosity average molecular weight of 18,000 to 30,000. The thermoplastic resin composition of claim 1, wherein the weight average molecular weight of the styrene / acrylonitrile resin is 50,000 to 300,000. The thermoplastic resin composition according to claim 1, wherein the particle size of butadiene contained in the acrylonitrile / butadiene / styrene resin is 0.1-0.3 micrometers. The thermoplastic resin composition according to claim 1, wherein the weight average molecular weight of the polymethyl methacrylate is 50,000 to 200,000. The thermoplastic resin composition of claim 1, further comprising at least one selected from an ultraviolet stabilizer, an antioxidant, a lubricant, and a release agent. A helmet comprising a shell made of the thermoplastic resin composition according to claim 1.