CN104479165B - A kind of method for preparing polypropylene low temperature solid phase expanded bead - Google Patents
A kind of method for preparing polypropylene low temperature solid phase expanded bead Download PDFInfo
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Abstract
A kind of method for preparing polypropylene low temperature solid phase expanded bead, comprises the following steps：A, by raw materials melt of branched p 0 lypropylene, bubble nucleating agent and antioxidant blending for polypropene composition；Quenching processing is carried out after B, melting mixing immediately；C, quenching is handled after polypropene composition using foaming agent carry out Low Temperature Solid-Phase foaming, obtain expanded polypropylene beads；The branched p 0 lypropylene is at 180 DEG C and more than or equal to 1s‑1Rate of extension under, melt drawn strains Critical fracture value more than 1.5, and tensile stress σ E and tensile deformation ξ relation meet dln σ E/d ξ ＞ 0.5.The polypropylene bead that expansion ratio is 6~40 times is can obtain with the method for the present invention.The various molded foams prepared by raw material of the expanded polypropylene beads have good mechanical performance, recycled advantage, can be widely applied to auto industry, package buffer material of food processing industry and electronic apparatus etc..
Description
Technical field
The present invention relates to polymer, more particularly to a kind of method for preparing polypropylene low temperature solid phase expanded bead.
Background technology
Polypropylene foam product mainly include polypropylene exruded foams sheet material, and by polypropylene foaming beads it is molded into
All kinds of shaped pieces obtained after type.Compared to usually used at present polystyrene, polyurethane and polyethylene, polypropylene bubble
Foam has higher temperature in use, excellent mechanical property, higher impact energy absorbability and degradable, environmental protection etc.
Excellent performance, is widely used in the fields such as buffering package, heat insulator, auto parts and components and building thermal insulation material.So
And, because linear polypropylene is semicrystalline polymer, stick stream temperature and fusing point closely, after melting melt strength it is relatively low and
Without strain hardening behavior, cause foaming when there are problems that substantial amounts of cell collapse, merge and.Improve polyacrylic send out
Bubble property, improves its melt strength, there is many methods in other words, wherein it is by linear polypropylene modification to study more
The method for introducing side chain afterwards.Patent CN101250249B in polypropylene by adding organic peroxide and polyfunctional monomer
Method branched structure is introduced in polypropylene molecular chain；In patent CN101418064A, by polypropylene, initiator, styrene
Extruded in the molten state after monomer, polyfunctional monomer and calcium stearate mixing, you can obtain the high melt containing long-chain branch strong
Spend polypropylene；Patent CN101092500A by polypropylene, organic peroxide evocating agent, polyfunctional monomer, branched accelerator,
Organic clay is pre-mixed uniformly, then feeds and melting extrusion is carried out in double screw extruder, prepare the height for being substantially free of gel
Melt strength polypropylene material.
In terms of result of study, branched structure is introduced, polyacrylic melt strength can be improved really, and improve polyacrylic
It is expandable.However, not all high melt strength, propylene has preferable foam performance, whether polypropylene possesses can
Foaminess determines by many factors, such as the size of molecular weight, the width of molecular weight distribution, the height of the degree of branching, branched
The length of chain and branching density it is high low.Preferable foam performance branched p 0 lypropylene need to meet following condition：Melted at 180 DEG C
The behavior of body draft flowing deformation must have specific strain hardening behavior, i.e., more than or equal to 1s-1Rate of extension under, melt draw
Stretching strain Critical fracture value is more than 1.5, and tensile stress (σ E) and the relation of tensile deformation (ξ) meet dln σE/dξ>0.5.So
And, although such branched p 0 lypropylene has preferable foam performance in terms of preparing polypropylene extrusion foaming sheet material, but itself is simultaneously
It cannot be directly used to Low Temperature Solid-Phase foaming method and prepare polypropylene bead, this is due to its crystalline texture and is not content with polypropylene
Bead is prepared caused by requirement.
At this stage, polypropylene bead be mainly using general purpose polypropylene or its mixture with other high fondant-strength resins as
Matrix, by made from complicated process route and strict process conditions.Patent ZL01819174.6, ZL02826640.4,
ZL200410061513.X, ZL200410063190.8 in line style acrylic resin bead surface by coating one layer of decomposition temperature
Organic peroxide between polypropylene fusing point and vicat softening point temperature, and make at a certain temperature its decompose 50% with
On, surface is produced a certain degree of crosslinking, under conditions of the presence of other decentralized media, obtained after being foamed with physical blowing agent
Expanded bead；Patent CN201110260389.X in high melt strength, propylene by adding beta nucleater, in certain extrusion
The EXTRUSION FOAMED PP bead with relatively low hot-forming temperature has been obtained after extrusion foaming under process conditions, underwater cutpellet.Specially
Sharp CN201310467949.8 passes through acrylic resin and gathering for being prepared into after the porous material melting mixing with adsorption function
Propylene particulate, after being foamed in autoclave, has obtained the ring for having absorption, purifying air and dispelling bacterium function of certain multiplying power
Guarantor's type polypropylene foaming beads.
In fact, polystyrene, polyethylene and polyurethane foam bead can be with simple devices in wider process conditions
It is lower to prepare, in that these three polymer have the melt rheological property energy or crystalline texture for being suitable for foaming.The present invention is exactly sent out
A kind of method for preparing polypropylene low temperature solid phase expanded bead is showed, under wider foaming condition, it is 6 to have obtained expansion ratio
~40 times of expanded polypropylene beads.
The content of the invention
The purpose of the present invention, exactly prepares polypropylene low temperature solid phase expanded bead to solve the above problems there is provided one kind
Method.
In order to achieve the above object, present invention employs following technical scheme：One kind prepares the foaming of polypropylene low temperature solid phase
The method of bead, comprises the following steps：
A, by raw materials melt of branched p 0 lypropylene, bubble nucleating agent and antioxidant blending for polypropene composition；
Quenching processing is carried out after B, melting mixing immediately；
C, quenching is handled after polypropene composition using foaming agent carry out Low Temperature Solid-Phase foaming, obtain polypropylene pearl
Grain；
The branched p 0 lypropylene is at 180 DEG C and more than or equal to 1s-1Rate of extension under, melt drawn strain Critical fracture
Value is more than 1.5, and tensile stress σ E and tensile deformation ξ relation meets dln σ E/d ξ>0.5.
The parts by weight content of each component is as follows in the polypropene composition：
100 parts of branched p 0 lypropylene；
0-30 parts of bubble nucleating agent but it is not zero；
0-3 parts of antioxidant but it is not zero.
The branched p 0 lypropylene is the branched p 0 lypropylene obtained by ray or electron radiation method, or in propylene polymerization mistake
The branched p 0 lypropylene of branched structure, or the branched p 0 lypropylene by being coupled again after grafting are introduced in journey, or it is multifunctional by adding
Spend the branched p 0 lypropylene that monomer introduces branched structure.
The branched p 0 lypropylene is the branched p 0 lypropylene that is obtained by ray or electron radiation method, or by after grafting again
The branched p 0 lypropylene of coupling.
The temperature of the quenching processing is -50~10 DEG C, is preferably -20~0 DEG C.
The bubble nucleating agent is selected from kaolin, montmorillonite, clay, talcum powder, calcium carbonate, mica, magnesia, oxidation
One or more in zinc, aluminum oxide, carbon black, silica, glass, quartz, titanium oxide；The antioxidant is selected from the uncles of 2,6- bis-
Butyl -4- ethyl -phenols, 2,6- di-tert-butyl-4-methy phenols, 2,6- di-t-butyls-alpha, alpha-dimethyl amino-p-cresol, 2,4,6-
It is tri-butyl-phenol, dilauryl thiodipropionate, thio-2 acid two (octadecyl ester), thio-2 acid two (14 ester), anti-
One or more in oxygen agent 1010, antioxidant CA, antioxidant B215 and antioxidant B225.
Low Temperature Solid-Phase foaming be polypropene composition and foaming agent are added jointly be equipped with foaming agent hold one's breath system,
Saturation, pressure release and hair are carried out in measuring pump, the board-like foaming formwork of the autoclave or vulcanizer of pressure inductor and temperature controller
After bubble, expanded polypropylene beads are obtained；The addition of foaming agent is the 1~20% of polypropene composition gross weight；Saturation temperature
Control is at 130~162 DEG C, and blowing temperature control is at 130~160 DEG C, and saturation pressure is controlled in 5~40MPa, pressure release speed control
In 0.6~13.8MPa/S.
The foaming agent be selected from R410A, R407C, R417A, R404A, R507, R23, R508A, R508B, HFC152a,
HFC-134a, HCFC-22, propane, normal butane, iso-butane, pentane, isopentane, pentamethylene or supercritical CO2In one kind or
It is several.
The polypropene composition can also with using APP, pentaerythrite, melamine as representative expansion type flame retardant；With
HBCD, brominated Polystyrene, brominated epoxy resin, antimony oxide are the bromide fire retardant of representative；With hydroxide
Aluminium is used cooperatively with magnesium hydroxide for the inorganic flame retardant of representative.General light stabilizer, purple can also be added as needed on
Ultraviolet absorbers, lubricant, metal injury survey agent, antistatic additive, filler, colouring agent, antiseptic, reinforcing agent, conductive agent
With brightening agent etc..
The Principle of Process that the present invention obtains expanded bead using Low Temperature Solid-Phase foaming is as follows：
Polyacrylic foaming process is the three-dimensional expansion process of countless abscesses, and melt will be by quick in this process
Stretching action, therefore, the essential condition for preparing high magnification expanded polypropylene is that bubble melt during expansion will not be broken
Split, once melt rupture too early will result in foaming structure generation holes or simultaneously hole in expansion process, reduce expansion ratio,
This requires melt polypropylene not only to bear certain tensile force effect, but also to have larger deformability.In addition,
Polypropylene is in actual foaming process, and the rate of deformation of melt is in 1~10s-1Between.Therefore, in the drawing of test melt polypropylene
When stretching rheological behaviour, rate of extension is more than or equal to 1s-1When the rheological property that shows of melt be closer to actually foam
The expansion behavior of melt in journey, this has actual directive significance really for expandable polypropylene.
Polypropene composition, when carrying out draft flowing deformation test, is 180 DEG C in temperature, rate of extension is more than or equal to 1s-1When
Melt drawn strain Critical fracture value have to be larger than 1.5, preferably more than 2, preferably greater than 3.If melt drawn is strained
Critical fracture value is less than 1.5, then the wall of abscess easily ruptures when foaming, and cannot get the expanded bead of preferable foam structure,
And melt drawn strain Critical fracture value is bigger, then in foaming, steep that wall is just less susceptible to rupture, it is easier to obtain rate of closed hole high
Expanded bead.
In addition, polypropene composition is when carrying out draft flowing deformation test, it is 180 DEG C in temperature, rate of extension is more than or equal to
1s-1When the relation of tensile stress (σ E) and tensile deformation (ξ) must be fulfilled for dln σ E/d ξ>0.5, preferably meet dln σ E/d ξ
≥1.If dln σ E/d ξ≤0, this polypropylene-based resin composition can not foam after being handled through quenching, even if foaming reluctantly
Also result in the rupture of steep that wall and simultaneously hole.If 0<Dln σ E/d ξ≤0.5, although polypropylene-based resin composition through quenching at
Can be foamed after reason, but foam process is interval narrower, the expanded bead performance that can cause to prepare it is unstable.And if
Dln σ E/d ξ >=1, then can reduce the dependence to foaming process conditions after polypropylene-based resin composition is handled through quenching, can be with
Held one's breath system, the board-like foaming of autoclave or vulcanizer of measuring pump, pressure inductor and temperature controller in being equipped with foaming agent
In template, the controllable expanded polypropylene beads of expansion ratio are obtained under wider process conditions.
In addition, before Low Temperature Solid-Phase foaming is carried out to polypropylene-based resin composition, it is necessary to which it is carried out after melt blending
Quenching processing, to obtain the crystalline texture for being suitable for foaming.In Low Temperature Solid-Phase foaming process, the success of expanded polypropylene beads
Prepare in addition to needing suitable melt strength, its crystalline texture is also required to meet foaming requirement.Because Low Temperature Solid-Phase is sent out
During bubble, polyacrylic crystalline texture has significant impact to the dissolubility and diffusivity of foaming agent gas, possesses relatively low crystallization
Degree, relatively low crystalline region sophistication, the polypropylene of small crystallite dimension has higher gas solubility and diffusion coefficient, this be obtain compared with
The necessary condition of the expanded bead of high foamability；And the less microcrystalline grain of widely distributed, size can also turn into gas
Heterogeneous nucleation point, so that obtained abscess average diameter is smaller, the high-quality expanded bead that cell density is higher.On the other hand, poly- third
A certain amount of crystalline texture in alkene, can increase the drawing of melt in foaming process while not influenceing to prepare expanded bead
Intensity is stretched, the preferable mechanical performances of PP can also be kept, its application prospect is widened.Therefore, polypropene composition Low Temperature Solid-Phase is sent out
Required crystallinity and crystallite dimension are not the smaller the better during bubble, and the polypropylene of too small crystallinity and crystallite dimension can not only drop
Its low mechanical performance, can also be substantially improved preparation cost；So, appropriate quenching condition, suitable crystalling propylene structure is
It obtains one of premise of high-quality expanded bead.
Present invention preferably uses supercritical CO2It is used as foaming agent.Because supercritical CO2Diffusivity with similar gas and
The solvability of liquid, while having low viscosity concurrently, the characteristic of low surface tension can be relatively easy to mixed with polypropylene-based resin
Conjunction obtains homogeneous mixture.On the other hand, supercritical CO2Compatibility with PP is poorer than hydrocarbon gas, molten when pressure release is foamed
Solution CO in matrix2Can also play a part of heterogeneous nucleation, making the quantity of abscess increases, it is easier to obtain high cell density
Expanded bead.On the basis of the polypropylene-based resin composition of 100 mass parts, consumption preferably 3~18 mass of foaming agent
Part, preferably 5~15 mass parts.If the consumption of foaming agent less than 3 mass parts, can make the multiple of expanded bead reduce or
Cell diameter becomes big, and if foaming agent consumption is more than 18 mass parts, expanded bead can then produce more and hole or holes,
Make elastic recovery and the thermal and insulating performance reduction of expanded bead.
The consumption of antioxidant is the 0~3% of branched p 0 lypropylene weight in the present invention, and preferable amount is 0.1%~2%, most
Preferably 0.2%~1%.The addition of antioxidant can prevent polypropylene-based resin from producing excessive degraded in process,
But if addition is more than 3%, not only increase cost, it is also possible to the mechanical property or foaminess of resin matrix can be deteriorated
Energy.
In the present invention consumption of bubble nucleating agent be branched p 0 lypropylene weight 0~30%, preferable amount be 0.05~
10%, more preferably 0.1~5%, most preferably 0.15~2%.The addition of bubble nucleating agent can play heterogeneous nucleation
Effect so that the cell density of expanded bead significantly increases, but if consumption is more than 30%, then have reduction expanded bead into
The mechanical property of type part and the risk for deteriorating polypropylene-based resin composition draft flowing deformation behavior.
The granularity of bubble nucleating agent preferably 300~5000 mesh, further preferred 500~3000 mesh, most preferably 600-1500
Mesh.If the granularity of bubble nucleating agent is less than 300 mesh, larger inorganic filler particle can deteriorate the power of polypropylene-based resin matrix
Learn performance or the abscess of expanded bead is produced more holes, if on the contrary, the granularity of bubble nucleating agent is more than 5000
Mesh, inorganic nanoparticles may reunite, it is impossible to be dispersed in resin matrix, there is reduction and resin matrix compatibility
Danger.
Saturation temperature is set as 130~162 DEG C when Low Temperature Solid-Phase foams in the present invention, preferably 140~160 DEG C, enters one
Step is preferably 150~158 DEG C.If saturation temperature is less than 130 DEG C, crystal region and amorphous area all bases in PP matrix
This does not soften, and foaming agent gas can only have a small amount of dissolving on its surface, it is difficult to internally spread, no matter saturation time how long,
Gas meltage and diffusion coefficient are all very low, and matrix is really up to the mark, it is difficult to obtain expanded bead.And work as saturation temperature and be higher than 162 DEG C,
Although its actual temperature still is below the fusing point of polypropene composition used, due to foaming agent gas, such as supercritical CO2,
After being dissolved in matrix, there is certain plastication to matrix, make the reduction of its fusing point, so as to cause the portion of polypropene composition
Divide melting, make to produce adhesion between polypropylene microparticle, gained expanded material will no longer be expanded bead, but the foaming of a monoblock
Body.
Blowing temperature is set as 130~160 DEG C when Low Temperature Solid-Phase foams, and preferably 140~158 DEG C, is more preferably
145~156 DEG C.Blowing temperature can both be equal to saturation temperature, can also be less than saturation temperature, and this depends on Polypropylene compositions
The softening situation of thing matrix.
Low Temperature Solid-Phase foam when saturation pressure be set as 5~40MPa, preferably 10~30MPa, more preferably 15~
25MPa.When saturation pressure is less than 5MPa, the solubility of foaming agent gas at this pressure is relatively low, the gas flow mistake in matrix
It is small, it is used for the nucleation of bubble without enough gas and grows up, gas is more likely to spread into existing abscess when pressure release is foamed, from
And obtaining that abscess number is few, the uniformity is poor, and with the presence of the expanded bead of big abscess, its mouldability and rebound performance are all excessively poor.
When saturation pressure is higher than 40MPa, solubility is larger at this pressure for foaming agent gas, but its plastication simultaneously is also relatively strong,
The fusing point of polypropene composition, which can be made, further to be reduced, and causes the adhesion between polypropylene microparticle；In addition, too high saturation pressure
It can cause to merge increasing for phenomenon between abscess, make the expanded bead hydraulic performance decline of preparation.
The length of saturation time depends on the required expansion ratio for preparing expanded bead when Low Temperature Solid-Phase foams.When required hair
When bubble multiplying power is relatively low, under above-mentioned saturation temperature, blowing temperature and saturation pressure, shorter saturation time can be obtained by required times
The expanded bead of rate, this is highly profitable for improving the economy of production；When required expansion ratio is higher, saturation time
Also it is unsuitable long, reach that saturation is adsorbed as standard in the base with foaming agent gas, not only long saturation time can not increase
The meltage of aerating body, can also increase production cost, reduce production efficiency.
The speed of pressure release speed depends on the required abscess pattern for preparing expanded bead when Low Temperature Solid-Phase foams.By practice
Prove, the speed of pressure release speed influences little to the expansion ratio of such polypropylene-based resin composition, but to its abscess pattern
There is significant impact.When pressure release speed is very fast, the thermodynamic phase of gas-polymeric system is high, bubble nucleating
It hurry up, substantial amounts of complex forms that cell diameter is smaller after growing up, cell density is high and the abscess pattern that is evenly distributed, such abscess
The expanded bead of pattern, is suitable for the profiled pieces such as shaping bolster, heat preservation member and auto parts and components, assigns its excellent performance.
When pressure release speed is slower, the thermodynamic phase of gas-polymeric system is relatively low, and bubble nucleating is slower, limited quantity
Complex forms that cell diameter is larger after growing up, cell density is relatively low and has the abscess pattern of part open, such abscess pattern
Expanded bead, be suitable for be molded sound-absorbing material and filtering material etc. profiled piece.
The specific example of the expanded bead of controllable multiplying power is prepared with the method for the present invention, is by polypropylene-based resin and nucleation
Agent, fire retardant and antioxidant carry out quenching processing on extruder after melt blending immediately, by material pelletizing be put into autoclave or
In the board-like foaming formwork of vulcanizer, cleaned after the air in autoclave or foaming formwork, reinjected a certain amount of with foaming agent gas
Foaming agent, then the temperature of autoclave or foaming formwork is increased to the saturation temperature of setting, and adjust pressure to setting
Saturation pressure, after saturation certain time, blowing temperature is reduced to by temperature, and keeps pressure constant, finally treats stable system one
After fixing time, carry out obtaining required expanded bead after pressure release, cooling and shaping with given pace.
Expanded bead open cell content prepared by the polypropylene-based resin composition of the present invention is less than 20%, more preferably below
15%, it is preferably capable of being less than 10%.Open cell content is higher than in the case of 20%, the elastic recovery of expanded bead and insulation
Heat-proof quality does not reach specific requirement.
The expanded bead prepared using the method for the present invention, mean cell diameter is 10~120 μm, more preferably 10~100 μ
M, preferably 10~80 μm, thermal conductivity preferably 20~34mw/mK, preferably 20~25mw/mK.
Brief description of the drawings
Fig. 1 is the SEM sectional drawings of the expanded bead of embodiment 1；
Fig. 2 is the SEM sectional drawings of the expanded bead of comparative example 1.
Embodiment
Example below is that the present invention is further illustrated, but is not limited the scope of the invention.
The measure and computational methods of various physical properties in embodiment and comparative example are as follows：
Mean cell diameter：Brittle failure after first expanded bead is cooled down with liquid nitrogen, then with ESEM (SEM) to expanded bead
Section observed, calculate the diameter of 10 abscesses respectively using given scale, then seek its average value.
The rate of closed hole of abscess：It is measured according to ASTM-D2856 standard.
Expanded bead density：Expanded bead weight is first weighed up with electronic balance, then sample is sunk with superfine wire
Enter into the graduated cylinder equipped with known water amount, according to the actual volume of the change determination sample of water level, its is calculated by formula (1) close
Degree.
Expanded bead density=sample quality/sample volume (1)
Expansion ratio：The density of expansion ratio=polypropylene-based resin composition/expanded bead density.
Light weight：Evaluated with zero (excellent), △ (qualified), × (unqualified) 3 grades.
Thermal insulation：Evaluated with zero (excellent), △ (qualified), × (unqualified) 3 grades.
Bead outward appearance (surface smoothness)：Evaluated with zero (excellent), △ (qualified), × (unqualified) 3 grades.
Bead outward appearance (has non-wrinkled)：Evaluated with zero (excellent), △ (qualified), × (unqualified) 3 grades.
Embodiment 1
Use twin-screw intermingling apparatus as described below：The screw diameter (D) of extruder is Φ 35mm, draw ratio (L/D)
For 48, quenching device has been installed additional outside mouth mold, the device can be immediately carried out at the quenching at -50~10 DEG C to extrusion blend
Reason.
Also use foam device as described below：Foaming agent is equipped with to hold one's breath system, measuring pump, pressure inductor and temperature
The autoclave and the board-like foaming formwork of vulcanizer of controller are spent, to prepare expanded bead.
In addition branched p 0 lypropylene as described below is also used：Branched p 0 lypropylene used is in 180 DEG C and rate of extension
1s-1When, melt drawn strain Critical fracture value is 3.5, tensile stress (σ E) and the relation dln σ E/d ξ of tensile deformation (ξ)>1,
Melt flow rate (MFR) is 2.5g/10min.On the basis of 100g branched p 0 lypropylenes, added with 0.5g antioxidant 1010s and 1g conducts
1000 mesh talcum powder of bubble nucleating agent.Said components are sufficiently mixed in high mixer, it is stand-by.
The above-mentioned polypropylene-based resin composition mixed is added melt zone temperature in 190 DEG C of extruder, to extrude
Machine rotating speed is 80r/min, through circular die extrusion after being well mixed, then carries out the quenching under 0 DEG C of environment immediately to mixture
Polypropylene microparticle is obtained after processing, and cleaved machine-cut grain.Then this polypropylene microparticle is put into autoclave, and faced with super
Boundary CO2For foaming agent, set after 157 DEG C of saturation temperature, 154 DEG C of blowing temperature, saturation pressure 20MPa, saturation 1h, with
5.7MPa/S pressure release speed pressure release, obtains expanded polypropylene beads.The expanded bead of preparation uses SEM after carrying out brittle failure with liquid nitrogen
The foam structure of section is observed, as shown in Figure 1.As shown in table 1, prepared expanded bead is bubble to the various characteristics of expanded bead
Hole is uniform, average diameter is less than 80 μm, and surface is round and smooth, does not have crisp high-quality expanded bead.
Comparative example 1
Polypropene composition after melt blending, does not carry out quenching processing to it in an extruder, makes its natural cooling (temperature
About 27 DEG C), other are same as Example 1.The expanded bead of preparation carries out being observed the bubble of section with SEM after brittle failure with liquid nitrogen
Pore structure, as shown in Figure 2.As shown in table 1, the expanded bead holes of preparation is serious, closed pore for the various characteristics of gained expanded bead
Rate is low, and resilience is poor.
Embodiment 2
Using pentamethylene as foaming agent, other are same as Example 1.The various characteristics of the gained expanded bead such as institute of table 1
Show, the expanded bead of preparation is uniform foam cell, and surface is round and smooth, do not have crisp high-quality expanded bead.
Comparative example 2
The polypropylene used is 1s in rate of extension-1When, melt drawn strain Critical fracture value is 1.5, tensile stress (σ
E) relation with tensile deformation (ξ) meets dln σ E/d ξ ≈ 0, and melt flow rate (MFR) is 3g/10min.In addition with implementation
Example 2 is identical.As shown in table 1, there are a large amount of pits on the expanded bead surface of preparation to the various characteristics of gained expanded bead, and holes is tight
Weight, expansion ratio is relatively low, lacks light weight and thermal insulation.
Embodiment 3
Saturation temperature when foaming is set as 158 DEG C, blowing temperature is 154 DEG C, and other are same as Example 1.Gained is sent out
Steep the various characteristics of bead as shown in table 1, the expanded bead of preparation is uniform foam cell, and surface is round and smooth, do not have crisp high-quality to foam
Bead.
Comparative example 3
Saturation temperature and blowing temperature during setting foaming are all 158 DEG C, and other are same as Example 3.Gained expanded beads
As shown in table 1, the expanded bead rate of closed hole of preparation is low, and resilience is poor, and there is one layer of obvious hard skin on surface for the various characteristics of grain
Layer.
Embodiment 4
Saturation pressure when foaming is set as 25MPa, other are same as Example 1.The various characteristics of gained expanded bead are such as
Shown in table 1, the expanded bead of preparation is that expansion ratio is higher, and surface is round and smooth, does not have crisp high-quality expanded bead.
Comparative example 4
Saturation pressure when foaming is set as 40MPa, other are same as Example 4.The various characteristics of gained expanded bead are such as
Shown in table 1, the expanded bead of preparation has residual adhesion, and holes is serious, and rate of closed hole is low, and resilience is poor.
Embodiment 5
Pressure release speed when foaming is set as 10MPa/S, other are same as Example 1.The various characteristics of gained expanded bead
As shown in table 1, the expanded bead cell diameter of preparation is smaller, and rate of closed hole is high, and resilience is very good.
Comparative example 5
Pressure release speed when foaming is set as 1.5MPa/S, other are same as Example 5.The various characteristics of gained expanded bead
As shown in table 1, the expanded bead cell diameter of preparation is larger, and resilience is poor, and rough surface.
Controllable multiplying power can be prepared using the method for the present invention on better simply foam device and under wider process conditions
Polypropylene foaming beads, overcome before prepare the difficulty of polypropylene foaming beads heavy dependence foaming machine, while also making
Foaming process is obtained to become more stable.The expanded polypropylene beads of the controllable multiplying power manufactured in the process of the present invention are raw material, are prepared
Various molded foams be the good mechanical performances such as a kind of low-density, thermal insulation, heat resistance, rigidity, and can circulate
The green foaming body utilized, can substitute polyurathamc, polystyrene and polyethylene applied to general field, and due to poly-
Propylene molded foam unique rigidity and heat resistance, can be widely applied to auto industry, food processing industry and electronics electricity
Package buffer material of device etc..
Claims (7)
1. a kind of method for preparing polypropylene low temperature solid phase expanded bead, it is characterised in that comprise the following steps：
A, by raw materials melt of branched p 0 lypropylene, bubble nucleating agent and antioxidant blending for polypropene composition；
Quenching processing is carried out after B, melting mixing immediately；
C, quenching is handled after polypropene composition using foaming agent carry out Low Temperature Solid-Phase foaming, obtain expanded polypropylene pearl
Grain；
The branched p 0 lypropylene is at 180 DEG C and more than or equal to 1s-1Rate of extension under, melt drawn strain Critical fracture value surpasses
1.5 are crossed, and tensile stress σ E and tensile deformation ξ relation meets dln σ E/d ξ>0.5；
The temperature of the quenching processing is -50~10 DEG C；
Low Temperature Solid-Phase foaming is to add polypropene composition and foaming agent jointly to be equipped with foaming agent and hold one's breath system, metering
Carried out in pump, the board-like foaming formwork of the autoclave or vulcanizer of pressure inductor and temperature controller after saturation, pressure release and foaming,
Obtain expanded polypropylene beads；The addition of foaming agent is the 1~20% of polypropene composition gross weight；Saturation temperature control exists
130~162 DEG C, blowing temperature control is at 130~160 DEG C, and saturation pressure is controlled in 5~40MPa, and pressure release speed control is 0.6
~13.8MPa/S.
2. the method as claimed in claim 1 for preparing polypropylene low temperature solid phase expanded bead, it is characterised in that：The polypropylene
The parts by weight content of each component is as follows in composition：
100 parts of branched p 0 lypropylene；
0-30 parts of bubble nucleating agent but it is not zero；
0-3 parts of antioxidant but it is not zero.
3. the method as claimed in claim 1 for preparing polypropylene low temperature solid phase expanded bead, it is characterised in that：It is described branched poly-
Propylene is the branched p 0 lypropylene obtained by ray or electron radiation method, or the introducing branched structure in propylene polymerization processes
Branched p 0 lypropylene, or the branched p 0 lypropylene by being coupled again after grafting, or introduce branched structure by adding polyfunctional monomer
Branched p 0 lypropylene.
4. the method as claimed in claim 3 for preparing polypropylene low temperature solid phase expanded bead, it is characterised in that：It is described branched poly-
Propylene is the branched p 0 lypropylene that is obtained by ray or electron radiation method, or the branched p 0 lypropylene by being coupled again after grafting.
5. the method as claimed in claim 1 for preparing polypropylene low temperature solid phase expanded bead, it is characterised in that：At the quenching
The temperature of reason is -20~0 DEG C.
6. the method as claimed in claim 1 for preparing polypropylene low temperature solid phase expanded bead, it is characterised in that：The bubble into
Core agent is selected from kaolin, montmorillonite, clay, talcum powder, calcium carbonate, mica, magnesia, zinc oxide, aluminum oxide, carbon black, dioxy
One or more in SiClx, glass, quartz, titanium oxide；The antioxidant is selected from 2,6- di-t-butyl -4- ethyl -phenols, 2,
It is 6- di-tert-butyl-4-methy phenols, 2,6- di-t-butyls-alpha, alpha-dimethyl amino-p-cresol, 2,4,6- tri-butyl-phenols, thio
Dipropionic acid dilauryl, thio-2 acid two (octadecyl ester), thio-2 acid two (14 ester), antioxidant 1010, antioxidant CA,
One or more in antioxidant B215 and antioxidant B225.
7. the method as claimed in claim 1 for preparing polypropylene low temperature solid phase expanded bead, it is characterised in that：The foaming agent
Selected from R410A, R407C, R417A, R404A, R507, R23, R508A, R508B, HFC152a, HFC-134a, HCFC-22, third
Alkane, normal butane, iso-butane, pentane, isopentane, pentamethylene or supercritical CO2In one or more.
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| CN113912901A (en) * | 2021-09-13 | 2022-01-11 | 无锡敬仁电子材料科技有限公司 | Tubular bead foaming polymer wave-absorbing material and preparation method thereof |
| CN116333423B (en) * | 2023-03-03 | 2024-08-27 | 广东奔迪新材料科技有限公司 | High strength and high toughness polyolefin plastomer expanded bead articles and methods of making the same |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102372855A (en) * | 2010-08-20 | 2012-03-14 | 哈尔滨鑫达高分子材料工程中心有限责任公司 | Supercritical method for preparing pre-foamed polypropylene |
| CN102617926A (en) * | 2011-01-27 | 2012-08-01 | 上海富元塑胶科技有限公司 | Polypropylene resin composition and method for using polypropylene resin composition in preparation of high ratio foamed sheet |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102372855A (en) * | 2010-08-20 | 2012-03-14 | 哈尔滨鑫达高分子材料工程中心有限责任公司 | Supercritical method for preparing pre-foamed polypropylene |
| CN102617926A (en) * | 2011-01-27 | 2012-08-01 | 上海富元塑胶科技有限公司 | Polypropylene resin composition and method for using polypropylene resin composition in preparation of high ratio foamed sheet |
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| "Effect of the Crystallinity and Morphology on the Microcellular Foam Structure of Semicrystalline Polymers";CHUL B.PARK等;《Polym.Eng.Sci》;19961231;第36卷(第21期);2645-2662 * |
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