WO2000031182A1 - Polystyrene-based resin composition for injection molding - Google Patents
Polystyrene-based resin composition for injection molding Download PDFInfo
- Publication number
- WO2000031182A1 WO2000031182A1 PCT/KR1999/000003 KR9900003W WO0031182A1 WO 2000031182 A1 WO2000031182 A1 WO 2000031182A1 KR 9900003 W KR9900003 W KR 9900003W WO 0031182 A1 WO0031182 A1 WO 0031182A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- polystyrene
- injection molding
- styrene
- composition
- based resin
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F279/00—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00
- C08F279/02—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00 on to polymers of conjugated dienes
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
- C08L25/02—Homopolymers or copolymers of hydrocarbons
- C08L25/04—Homopolymers or copolymers of styrene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F291/00—Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00
- C08F291/02—Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00 on to elastomers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
- C08L25/02—Homopolymers or copolymers of hydrocarbons
- C08L25/04—Homopolymers or copolymers of styrene
- C08L25/06—Polystyrene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
Definitions
- the present invention relates to a polystyrene-based resin composition for an injection molding and more particularly, to a polystyrene-based resin composition for an injection molding for reducing exterior defects such as a weld line formed during the injection molding and for eliminating a post-processing treatment such as a painting treatment.
- polystyrene is produced b> the radical polymerization of styrene using an initiator such as an organic peroxide.
- polystyrene has a straight chain structure and has a good transparenc) .
- the specific gravitv of the poh styrene is low and an insulating characteristic on electricity and high frequency is good.
- the poh styrene has some defects of having a low softening temperature and being hard and so liable to break.
- Polystyrene-based resin has a low melting point viscosity in relatively low temperature range. And the decreasing degree of the viscosity according to the decrease of the temperature, is slow and the range of the molding temperature is wide. Moreover, the transparency and a molding characteristic of the polystyrene-based resin are good.
- High impact polystyrene (HIPS) and ABS resin are widely used as a case for household electric and electronic products.
- the ratio (L/t) of the fluid length L of the resin and the building thickness t of the mould product is 230-250 for the GPPS resin. 220-230 for the HIPS resin and 190-200 for the ABS resin. Accordingly, the fluidity of the resins are good in order of the ABS resin, the HIPS resin and the GPPS resin. However, since the ABS resin is more expensive than the GPPS resin or the HIPS resin, the HIPS resin is widely used for the common electronic products such as television cases. However, since the HIPS resin is not good in fluidity, a weld line is generated in the manufactured mould product through the injection molding. Therefore, post-processing treatment such as painting treatment should be implemented after the injection molding.
- the weld line is formed as a thin solid line at the position where two melted and separated resins flow together.
- the main reason of the generation of the weld line is the incomplete mixing of two melted resins at the meeting portion.
- the weld line also can be generated b ⁇ moisture or a volatile matter contained in the resin, or by a mold release used during the injection molding.
- a gate for supplying the resin into the mold is needed.
- two or more gates are needed. In these cases, the weld line is liable to be formed.
- the weld line may be generated when an inserting component or a hole is present in the mould product or when the building thickness of the mould product is different each other.
- FIGs. 1A and I B are typical views for explaining the generating process of the weld line.
- the melted resin is supplied into the cavity through two gates 12 and 14 and the weld line is generated where the two separated portions of the resin flow together.
- the weld line is not formed even though the separated and melted resins flow together near gates 12 and 14 but the weld line is formed far from gates 12 and 14.
- the melted resin gets cool through the mold and the two resin portions far from gates 12 and 14 could not mix together completely because of the low temperature of the resin, thereby generating the weld line.
- the weld line 16 is generated even though the melted resin is supplied through one gate 12 when a hole 18 is provided in the mould product. Because the melted resin is separated around the hole 18 and then How together, the weld line is generated.
- the weld line is inevitably generated when butadiene is included in the HIPS resin for increasing the high intensity and the fluidity of the resin, because the fluidity is lowered.
- the generated weld line lowers the strength of the mould product and the degree of the exterior quality for the mould product. Accordingly, the weld line should be eliminated after the injection molding process through a painting process.
- a polystyrene-based resin composition for an injection molding comprising a mixture of a first and a second styrene compositions having rubbers of different particle sizes.
- the first styrene composition includes 6-8% of the rubber ha ⁇ ing the particle diameter of 3-5 ⁇ m.
- the second styrene composition includes 7-9% of the rubber having the particle diameter of l -3 ⁇ m.
- the polystyrene-based resin composition comprises 70-90% of the first styrene composition, 9-29% of the second styrene composition, a thermo- stabilizer and a silicon oil.
- the fluid characteristic of the resin is improved by mixing polystyrene resin compositions including rubbers having different particle sizes. Therefore, the generation of the weld line is restrained and the exterior view of the mould product is improved.
- FIG. 1A is a typical view for illustrating the forming process of a weld line
- FIG. IB is a typical view for illustrating another forming process of a weld line.
- the polystyrene-based resin composition for the injection molding will be explained in more detail with reference to the accompanying drawings.
- the polystyrene resin includes the particles of a synthetic rubber, only the large-sized rubber particles alone or only the small-sized rubber particles alone have been used.
- the rubber particles are distributed in the fiber structure of the butadiene, which is present in the base of the polystyrene.
- the stress coincides on the fiber structure and minute crazing is generated. Through this, the impact can be absorbed.
- the fluidity during the injection molding is proportional to the amount of the used particles.
- the amount of the using rubber particles is as little as possible, while reinforcing the impact-resistance.
- the size of the rubber particles included in the polystyrene is only one kind of particle size among the large one or the small one. a homogeneous distribution of the rubber particles in the polystyrene becomes difficult.
- the rubber particles can be mixed homogeneously and both of the impact-resistance and the fluidity can be satisfied for the polystyrene. Accordingly, the molding characteristic during the injection molding can be improved and the exterior view of the mould product also can be improved.
- the present invention will be explained in detail with the following preferred embodiments. 1 ) examples 1 -5
- the first polystyrene composition was obtained by mixing styrene with 7% of a rubber having the mean particle diameter of 3-5 ⁇ m.
- the second polystyrene composition was obtained by mixing styrene with 8% of a rubber having the mean particle diameter of l-2 ⁇ m.
- the first and the second styrene compositions and other additives were mixed with the mixing ratios as illustrated in Table 1.
- Test pieces were manufactured by injection molding the mixed compositions under the temperature of 190-220 °C for the cylinder of the injection molder and 50 °C for the molder. with the injection pressure of 100 ton. The size of the test pieces were 450mm x 250mm. The test pieces were melted and filled up in the mold having one insert hole 18 at the center portion as one gate, as illustrated in FIG. I B. Table 1
- the polystyrene-based resin composition was obtained by using only the first styrene composition.
- the added amount of the second styrene composition was gradually increased. It is shown that the swelling index is decreased as the cross linking ratio increases through increasing the mixing ratio of the styrene compositions having different particle sizes.
- Table 2 The obtained testing results with respect to the test pieces manufactured by using two compositions in different mixing ratios and in the shape illustrated in FIG. I B. are illustrated in Table 2.
- the length is long and the width is wide for the weld line.
- the length and the width of the weld line are reduced in examples 2-5 which include the second styrene composition.
- the width of the weld line increases in example 5 which includes a lot of the second styrene composition.
- the gloss characteristic is better for examples 2-5 than that for example 1.
- the stain characteristic is not good for example 5 which includes a lot of the second styrene composition.
- the generating amount of the gas is measured by weighing the reduced amount of the test species after standing the test species at 230 °C for 30 minutes. The gas generating amount is little for examples 2 and 3.
- the exterior view of the mould product can be improved by using the mixed composition of the first styrene composition having the large-sized rubber particles and the second styrene composition having the small- sized rubber particles at a predetermined ratio.
- the first and the second polystyrene composition were simply mixed. In fact, they were mixed and then injection-mould. Therefore, the large-sized rubber particles and the small-sized rubber particles contact closely and the exterior view of the mould product can be further improved.
- the exterior view 7 of the mould product can be improved through injection molding the composition obtained by mixing the polystyrene composition including the large-sized rubber particles and the polystyrene composition including the small-sized rubber particles in the present invention.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP99901225A EP1198514A1 (en) | 1998-11-24 | 1999-01-04 | Polystyrene-based resin composition for injection molding |
JP2000584004A JP2002530504A (en) | 1998-11-24 | 1999-01-04 | Polystyrene resin composition for injection molding |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1998/50390 | 1998-11-24 | ||
KR1019980050390A KR100302128B1 (en) | 1998-11-24 | 1998-11-24 | Polystyrene resin compound for injection molding |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2000031182A1 true WO2000031182A1 (en) | 2000-06-02 |
Family
ID=19559447
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/KR1999/000003 WO2000031182A1 (en) | 1998-11-24 | 1999-01-04 | Polystyrene-based resin composition for injection molding |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1198514A1 (en) |
JP (1) | JP2002530504A (en) |
KR (1) | KR100302128B1 (en) |
WO (1) | WO2000031182A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6579946B2 (en) | 2001-02-02 | 2003-06-17 | Dow Global Technologies Inc. | Low-gloss biaxially oriented films comprising vinyl aromatic polymers and substantially non-spherical rubber particles |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4493922A (en) * | 1980-09-20 | 1985-01-15 | Basf Aktiengesellschaft | Impact-resistant thermoplastic molding material |
US5334658A (en) * | 1990-06-07 | 1994-08-02 | Basf Aktiengesellschaft | Thermoplatic molding materials |
US5491195A (en) * | 1993-09-02 | 1996-02-13 | The Dow Chemical Company | Rubber modified polystyrene |
-
1998
- 1998-11-24 KR KR1019980050390A patent/KR100302128B1/en not_active IP Right Cessation
-
1999
- 1999-01-04 EP EP99901225A patent/EP1198514A1/en not_active Withdrawn
- 1999-01-04 WO PCT/KR1999/000003 patent/WO2000031182A1/en not_active Application Discontinuation
- 1999-01-04 JP JP2000584004A patent/JP2002530504A/en active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4493922A (en) * | 1980-09-20 | 1985-01-15 | Basf Aktiengesellschaft | Impact-resistant thermoplastic molding material |
US5334658A (en) * | 1990-06-07 | 1994-08-02 | Basf Aktiengesellschaft | Thermoplatic molding materials |
US5491195A (en) * | 1993-09-02 | 1996-02-13 | The Dow Chemical Company | Rubber modified polystyrene |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6579946B2 (en) | 2001-02-02 | 2003-06-17 | Dow Global Technologies Inc. | Low-gloss biaxially oriented films comprising vinyl aromatic polymers and substantially non-spherical rubber particles |
Also Published As
Publication number | Publication date |
---|---|
EP1198514A1 (en) | 2002-04-24 |
JP2002530504A (en) | 2002-09-17 |
KR20000033502A (en) | 2000-06-15 |
KR100302128B1 (en) | 2001-10-29 |
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