We all know that the modification method of PS has chemical modification and physical modification. The properties obtained by the modification are different. Below we introduce the application examples of PS modification.
Example 1: Application of SBS modification
SBS has two blocks of plastic segment and elastic segment in series structure. PS is at both ends of the macromolecule, and polybutadiene is soft segment in the middle, showing high elasticity.
For example, SBS toughened PS, SBS added amount is 25%, SBS selects linear structure, of which S:B=40:60, oil filling amount is 0%, Mooney viscosity is 160. The star SBS effect is slightly worse. As the amount of SBS increases, the degree of anisotropy of the blend also increases. When blending, the mixing time should be extended or the secondary mixing process should be better, which is beneficial to the uniform mixing between the two phases. If the processing fluidity of the blend is improved, oil-saturated SBS can be used (for example, the oil filling amount is 33% linear or star SBS).
SBS toughened LDPE, the general SBS addition amount is 10%, and the impact strength is increased by 50%.
SBS toughened HDPE, when the SBS incorporation is 5%, the impact impact strength is doubled.
SBS toughened PP, SBS added 50%, the impact strength of pure PP at low temperature increased from 0.8 to 8 kJ / m2, the hardness is not significantly reduced, can be used in car steering wheel, washing machine liner Wait.
SBS can be blended and modified with transparent PS and silica filler with lower molecular weight and lower softening point to make sole material, replacing traditional vulcanizate and PVC material. In addition to blending with PS, it can also be blended with materials compatible with SBS such as PE, PP, EVA, etc. In addition to silica, fillers such as calcium carbonate can also be used. In order to improve the aging resistance, 0.5% of dilauryl thiopropionate, 0.3% of antioxidant, and 0.2% of anti-UV agent should also be added to the shoe mixture. An ultraviolet shielding agent such as titanium dioxide or zinc oxide may be added to the white sole.
Example 2: Blending modification of high styrene
High styrene (HS) is generally produced by latex co-coagulation. Generally, the styrene content is between 60-90%, and if the styrene content is above 95%, it is similar to PS; if it is lower than 50%, it is similar to styrene-butadiene rubber (SBR).
HS can be blended with PE, EVa, styrene butadiene rubber, butadiene rubber, neoprene, nitrile rubber and natural rubber, and its dosage is generally 10-50%.
HS made a composite imitation leather base recipe as follows:
Face glue: HS 30, natural glue 30, styrene butadiene 40, calcium carbonate 100
Primer: HS, natural rubber 22, reclaimed rubber 220, carbon black 90
Lubricants, accelerators, pigments and other additives are also included in the topping and the primer.
The HS made micro-hole sole formula is as follows:
HS 60, natural rubber 100, three composite fillers 115 and other additives.
The HS modified EVA emblem hole bottom formula is as follows:
EVa80, HS20, crosslinker DCPI, foaming agent aC2.5, zinc oxide 1, stearic acid 0.5, appropriate amount of pigment.
The HS modified LDPE microporous bottom formulation is as follows:
LDPE90, HS10, calcium carbonate 10, aC4.5, DCP0.9, three salt slurry 2, the right amount of pigment.
Example 3: aS refrigerator fruit and vegetable box
aS is SaN, the relative density is 1.06-1.08, and its impact strength is three times that of ordinary PS impact strength, and the low temperature impact performance is good.
aS water absorption rate of 0.66%, should be dried at 75-85 ° C for 4 hours before injection molding, injection barrel temperature 240-260, 240-260, 200-230, 200 ° C injection pressure 8-10 MPa, the mold used Large gate feed, clamping pressure 8-10 MPa, pre-plastic pressure 5-6 MPa (both oil pressure).
The nozzle adopts a straight-through extension type, and the nozzle is heated by a heating coil to separately control the temperature.
When using recycled materials, the temperature and injection pressure can be appropriately reduced. At the same time, the material in the barrel should be stirred frequently to prevent the "bridge" phenomenon and the blanking.
Example 4: Flame retardant high impact polystyrene
High impact polystyrene (HIPS) flame retardants are: phosphorus, halogens, nitrogen, antimony, boron, sulfur, and the like. In most cases, the combined effect of various elemental compounds is superior to the effect of using alone.
The addition amount of aluminum hydroxide in HIPS needs to be more than 50% to see the effect, and the physical and mechanical properties of HIPS are seriously reduced. Therefore, the use of decabromodiphenyl ether and antimony trioxide, silica, and synergistic flame retardant effect.
Generally, 10 parts of the resist agent, 8 parts of the rubber toughening agent, 10 parts of the silica, and 0.2 parts of the titanate coupling agent are added, so that the impact strength, the heat distortion temperature, and the molding process fluidity of the composite material are not affected. Large, but the flame retardant performance is greatly improved.
Example 5: HIPS replaces aBS plastic
HIPS can produce broadcast TV accessories for aBS plastics, such as TV sets and tape recorder housings, reducing material costs. HIPS can be directly injection molded without drying. The insert preheating temperature is 110-130 °C.
The temperature of the four zones of the injection cylinder is: 150, 180, 220, 220 ° C, nozzle temperature 210 ° C, mold temperature 50 ° C, rapid injection time 8 seconds, slow injection time 12 seconds, dampening time 15 seconds, cooling time 35 seconds The whole molding cycle time is 70 seconds, the injection pressure is 70-140 MPa, the mold release slope is 0.5-1.5 degrees, and the product is allowed to stand at a temperature of 100-120 ° C for 2 - 4 hours, and post-treatment is performed to eliminate internal stress.
In order to increase the appearance of the product, the method of spraying and hot stamping metal can be used, and the effect is slightly worse than that of aBS plating.
Example 6: Recycling of waste PS foam
In addition to burning, waste PS foam can also be recycled and granulated. The process flow is:
Electric baking block → crushing → extrusion drawing → cooling → pelletizing → metering packaging
The electric baking block oven is selected from the electric blast drying oven, the temperature is controlled at 140 ° C, the pulverized material should be between 60-80 mesh, and should be dried at 80-100 ° C before extrusion, and the extruder is three-stage. The temperature is: 130-140, 160-180, 200-220 ° C, the head temperature is 170-190 ° C, and the cooling can be air-cooled.
The recycled PS material can be blended with the new material, and the addition amount is preferably 20% or less.
It also cleans and pulverizes the used PS foam, and then undergoes a certain chemical reaction to produce a finishing agent, which can be used as a moisture-proof finish for corrugated boxes to reduce product cost.
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