Patent Application
20080004378
Practical and presently preferred embodiments of the present invention are illustrated as shown in the following examples.
However, it will be appreciated that those skilled in the art, on consideration of this disclosure, may make modifications and improvements within the spirit and scope of the present invention.
Preparation of Rubber-Modified Styrene Resin
A monomer mixture composed of 8 weight part of butadiene rubber, 77 weight part of styrene and 15 weight part of ethylbenzene was prepared, to which 0.02 weight part of 1,1-bis(t-butyl peroxy)-3,3,5-trimethyl cyclohexane was added as a polymerization initiator. The mixture was put in a continuous polymerizing apparatus wherein 4 stirred tank reactors were serially connected, followed by continuous graft copolymerization. The temperature at the entrance of the polymerizing apparatus was 125° C., and the temperature at the exit was 140° C. The final copolymerization solution was transferred into the devolatilizing tank, where non-reacted monomers and solvent were eliminated at 230° C. under 20 torr, followed by pelleting to give a rubber-modified styrene resin (HIPS) containing 8 weight % of rubber.
Preparation of Flame Retardant Rubber-Modified Styrene Resin
To 100 weight part of the rubber-modified styrene resin prepared above were added 3 weight part of triphenylphosphate (Daihachi, Japan), a flame retardant, 3 weight part of ethylene bis stearamide as a dripping enhancer (Sunkoo Chem., Korea), and 0.3 weight part of an antioxidant (Ciba Specialty Chemicals iganox 1076). The above compounds were mixed well in a Henschel mixer, followed by extrusion at 210° C. using a twin screw extruder to prepare a pellet. The final sample was prepared by injecting.
A flame retardant rubber-modified styrene resin was prepared in the same manner as described in Example 1 except that 0.5 weight part of stearamide (Akzo) was used as a dripping enhancer.
A flame retardant rubber-modified styrene resin was prepared in the same manner as described in Example 1 except that 7 weight part of resorcinol tetraxylyloxy diphosphate PX-200 (Daihachi, Japan) was used as a flame retardant and 5 weight part of ethylene bis stearamide (Sunkoo chem., Korea) was used as a dripping enhancer.
A flame retardant rubber-modified styrene resin was prepared in the same manner as described in Example 1 except that 80 weight part of the rubber-modified styrene resin and 20 weight part of polyethylene ether were used and extrusion was performed at 250° C. without using a dripping enhancer.
A flame retardant rubber-modified styrene resin was prepared in the same manner as described in Example 1 except that 3 weight part of triphenylphosphate was used and a dripping enhancer was not used.
A flame retardant rubber-modified styrene resin was prepared in the same manner as described in Example 1 except that 15 weight part of triphenylphosphate was used and a dripping enhancer was not used.
A flame retardant rubber-modified styrene resin was prepared in the same manner as described in Example 1 except that 12 weight part of ethylene bis stearamide was used.
A flame retardant rubber-modified styrene resin was prepared in the same manner as described in Example 1 except that 3 weight part of zinc stearate was used as a dripping enhancer.
A flame retardant rubber-modified styrene resin was prepared in the same manner as described in Example 1 except that 3 weight part of polyethylene wax was used as a dripping enhancer.
A flame retardant rubber-modified styrene resin was prepared in the same manner as described in Example 1 except that 3 weight part of fatty acid ester compound was used as a dripping enhancer.
The flame retardant rubber-modified styrene resins prepared in Examples 1˜3 and Comparative Examples 1˜7 were tested for impact resistance and weather resistance as follows.
a) Flammability—tested with ⅛″ bar sample according to the UL94 VB flammability test method
b) Impact resistance—tested with ⅛″ notch sample according to ASTM D256 by measuring izod impact strength (kg·cm/cm).
c) Heat resistance—tested with ¼″ sample according to ASTM D648 by measuring heat distortion temperature (HDT).
d) Fluidity—tested under the conditions of 200° C. and 5 kg according to ASTM D1238.
The flame resistance and physical properties measured by the above methods are shown in Table 1.
As shown in Table 1, the flame retardant rubber styrene resins of Examples 1˜3, which were prepared with the addition of a phosphoric ester compound as a flame retardant and aliphatic amide compound a dripping regulator without polyphenylene ether, were confirmed to have stable flame resistance according to UL-94 V-2 and maintained an excellent balance among the mechanical properties including impact resistance, heat resistance and fluidity.
Particularly, the flame retardant rubber-modified styrene resin of Comparative Example 1 had flame resistance for dripping but the total burning time was longer with reduced fluidity. In the meantime, the resins of Comparative Examples 2, 5, 6 and 7 wherein a dripping regulator was not included and a non-aliphatic amide lubricant was included had excellent mechanical properties but unsatisfactory flame resistance. As shown in Comparative Examples 3 and 4, excellent flame resistance for dripping can be achieved by the over-use of a phosphoric ester compound and aliphatic amide compound, which has the disadvantage of a serious reduction in heat resistance.
As explained hereinbefore, the flame retardant rubber-modified styrene resin composition of the present invention can maintain flame resistance according to UL-94 V-2 without any halogen compound or polyphenylene ether and has excellent impact resistance, heat resistance and fluidity. The flame retardant rubber-modified styrene resin composition of the present invention can be applied to various fields particularly to OA devices and TV housings, owing to the slight chance of outward inferiority under various molding conditions.
Those skilled in the art will appreciate that the conceptions and specific embodiments disclosed in the foregoing description may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present invention. Those skilled in the art will also appreciate that such equivalent embodiments do not depart from the spirit and scope of the invention as set forth in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0059559 | Jun 2006 | KR | national |
