Polyester expanded bead, polyester expanded bead molded body and preparation method thereof
阅读说明：本技术 一种聚酯发泡珠粒和聚酯发泡珠粒成型体及其制备方法 (Polyester expanded bead, polyester expanded bead molded body and preparation method thereof ) 是由 翟文涛 于 2021-06-01 设计创作，主要内容包括：本发明公开了一种聚酯发泡珠粒及其制备方法,所述制备方法包括以下步骤：S1.将聚酯发泡珠粒原料经挤出机造粒,得聚酯微粒；S2.将所述聚酯微粒在无水的高压容器中浸渍高压流体a,得浸渍聚酯微粒；S3.将所述浸渍聚酯微粒冷冻并储存于0℃以下的环境中,得冷冻锁气聚酯微粒；S4.对所述冷冻锁气聚酯微粒进行升温发泡处理。本发明所述聚酯发泡珠粒结晶度为15-45％、密度为20-500g/L,具有优异的力学性能和耐热性能。本发明还公开了一种聚酯发泡珠粒成型体及其制备方法,本发明所述聚酯发泡珠粒成型体通过射频成型可达150度以上耐热,50％变形的压缩强度可达3-10MPa。(The invention discloses a polyester expanded bead and a preparation method thereof, wherein the preparation method comprises the following steps: s1, granulating a raw material of polyester foaming beads by an extruder to obtain polyester particles; s2, impregnating the polyester particles with a high-pressure fluid a in an anhydrous high-pressure container to obtain impregnated polyester particles; s3, freezing the impregnated polyester particles and storing the polyester particles in an environment below 0 ℃ to obtain frozen gas-locked polyester particles; and S4, heating and foaming the frozen air-locked polyester particles. The crystallinity of the polyester expanded bead is 15-45%, the density is 20-500g/L, and the polyester expanded bead has excellent mechanical property and heat resistance. The invention also discloses a polyester foaming bead forming body and a preparation method thereof, the polyester foaming bead forming body can resist heat of more than 150 ℃ through radio frequency forming, and the compression strength of 50% deformation can reach 3-10 MPa.)
1. A preparation method of polyester expanded beads is characterized by comprising the following steps:
s1, granulating a raw material of polyester foaming beads by an extruder to obtain polyester particles;
s2, impregnating the polyester particles with a high-pressure fluid a in an anhydrous high-pressure container to obtain impregnated polyester particles;
s3, freezing the impregnated polyester particles and storing the polyester particles in an environment below 0 ℃ to obtain frozen gas-locked polyester particles;
s4, heating and foaming the frozen air-locked polyester particles to obtain polyester foamed beads;
the raw material of the polyester foaming bead comprises the following components in parts by weight: 100 parts of polyester, 0-20 parts of nucleating agent and 0-1 part of antioxidant; the polyester is PET and/or PBT.
2. The method for producing polyester expanded beads according to claim 1, wherein the intrinsic viscosity of the polyester is 0.9 to 1.3 dl/g.
3. The method for preparing polyester expanded beads according to claim 1, wherein the gel content in the polyester is 0 to 30 wt.%, preferably 0 to 15 wt.%.
4. The method for preparing polyester expanded beads according to claim 1, wherein the weight percentage of the high-pressure fluid a in the impregnated polyester particles is 1.0 to 10.0%; preferably, the weight percentage of the high-pressure fluid a in the impregnated polyester particles is 2.0-8.0%.
5. The method for producing polyester expanded beads according to claim 1, wherein the degree of crystallinity of the impregnated polyester fine particles is 0 to 15%; preferably, the degree of crystallinity of the impregnated polyester fine particles is 0 to 12%.
6. The process for producing expanded polyester beads according to claim 1, wherein at least one of the following (a) to (g):
(a) the nucleating agent is an organic nucleating agent and/or an inorganic nucleating agent, and the organic nucleating agent is at least one of PE, PP, PC, nylon and ABS; the inorganic nucleating agent is at least one of calcium carbonate, talcum powder, mica and glass beads;
(b) the high-pressure fluid a is CO2And/or N2；
(c) The pressure of the high-pressure fluid a is 1-10 MPa;
(d) the heating mode is at least one of hot air, hot steam and heat radiation;
(e) the mass weight loss rate of the frozen air-locking polyester particles is less than or equal to 30 percent per day;
(f) the freezing temperature is-20 to-100 ℃;
(g) the mass weight loss of the frozen air-locking polyester particles is less than or equal to 30 percent; the weight loss of the frozen gas-locked polyester particles is (m)1-m2)×100％/(m1-m0) Wherein m is0M is the mass of the polyester fine particles1Mass m of the impregnated polyester particles after desorption at normal temperature and pressure for 10min2The quality of the frozen air-locking polyester particles after being desorbed for 10min at normal temperature and pressure is obtained.
7. A polyester expanded bead produced by the method for producing a polyester expanded bead according to any one of claims 1 to 6.
8. A method for producing a polyester expanded bead molded body, comprising the steps of:
A. introducing a high-pressure fluid b into a high-pressure container for carrying out carrier gas treatment on the polyester expanded beads as claimed in claim 7 to obtain polyester expanded beads after carrier gas treatment;
B. and injecting the polyester expanded beads treated by the carrier gas into a mold, heating by radio frequency, cooling, and demolding to obtain the polyester expanded bead molded body.
9. The process for producing a polyester expanded bead molding according to claim 8, wherein at least one of the following (i) to (iii):
(i) the high-pressure fluid b is air or CO2；
(ii) The pressure of the high-pressure fluid b is 0.1-0.5 MPa;
(iii) the power of the radio frequency heating is 100-2000W.
10. A molded polyester expanded bead product produced by the method for producing a molded polyester expanded bead product according to claim 8 or 9.
Technical Field
The invention relates to the technical field of high polymer materials, in particular to polyester expanded beads, a polyester expanded bead forming body and a preparation method thereof.
Background
Polyethylene terephthalate (PET) is the variety with the largest yield and the lowest price in thermoplastic polyester, has obvious cost performance, and is widely applied to three fields of synthetic fibers, polyester bottles and biaxially oriented films. PET foam materials such as PET continuous extrusion foam boards, PET continuous extrusion foam sheets, and the like have light weight, large specific strength, excellent heat resistance, and good electrical insulation, and have been applied in large scale in the fields of wind power generation, automobiles, high-speed rails, buildings, food packaging, and the like.
The polymer foaming beads such as EPS, EPP, EPE and ETPU are bead-shaped polymer foaming materials, have high expansion rate, can be prepared into low-density and ultralow-density complex special-shaped parts through steam forming, become the main form of foaming materials and are applied to the fields of cache packaging, automobile lightweight parts, building heat preservation, cold-chain logistics, motion protection, home furnishing, toys and the like. However, expanded beads such as EPS, EPE, EPP, ETPU and the like have low heat resistance and are difficult to apply to an environment where the use temperature is higher than 120 ℃. PET is a semi-crystalline polymer with a melting point of 240-260 ℃, and PET expanded beads and molded bodies can be applied to environments with the use temperature of more than 120 ℃ to 180 ℃.
Chinese patent CN103764738A discloses a method for preparing aromatic polyester resin expanded beads and an in-mold forming body, wherein the method comprises the steps of melting and blending polyester and a foaming agent, extruding and foaming through an oral mold, and then cooling and cutting into granules underwater to obtain the aromatic polyester resin expanded beads with the density of 0.05-0.7g/cm3And the polyester expanded beads with the crystallinity lower than 15 percent are subjected to secondary expansion molding by an in-mold molding method. In order to increase the closed cell ratio of the expanded beads, an aromatic polyester having an intrinsic viscosity of 0.8 to 1.1dl/g is used, and 0.01 to 5 parts by weight of a crosslinking agent is added to increase the molecular weight of the polyester resin. The heat resistance of the polyester is related to the crystallinity of the polyester, and the crystallinity of the polyester expanded beads prepared by the method is lower than 15 percent, so that the problem of low heat resistance exists; meanwhile, in the method, the polyester/foaming agent mixed melt can be subjected to decompression foaming at the die of the extruder, the volumes of the foamed beads and products thereof are huge, the cost is high during long-distance transportation, and the transportation radius is small.
Chinese invention patent CN109705542A discloses a preparation method of flame-retardant polyester composition and its expanded beads and plates, the related polyester is PET, PBT, PBS, the invention method adopts an extruder to melt flame-retardant polyester composition wires and cut into particles to obtain flame-retardant polyester composition particles, the polyester particles, a dispersion medium (preferably water), a surfactant, a dispersant, a dispersion reinforcing agent, a foaming agent are stirred and dipped in an autoclave, and the flame-retardant polyester expanded beads are obtained by rapid pressure relief foaming, the selected foaming temperature is 0.1-5 ℃ lower than the melting temperature thereof, and the stirring time under the foaming temperature and pressure is 0.1-2 h. As is well known in the art, polyester resins such as PET are susceptible to hydrolysis and thermo-oxidative degradation, and prolonged high temperature poaching in a water environment will necessarily result in hydrolysis or degradation of the polyester resin, which can affect the performance and appearance color of the polyester expanded beads. Meanwhile, the foaming agent impregnated by the technology needs to be quickly decompressed and foamed, so that the prepared foamed beads have high cost and small transportation radius when moving for a long distance.
Academic literature (J.Appl.Polym.Sci.,2017: 45805.; Polym.Eng.Sci.,2015,55,1528.) reports the intermittent melt foaming behavior of PET particles or flakes or blocks in a supercritical fluid, PET in a high pressure fluid such as CO2Crystallization is easy to occur under the plasticizing effect of the fluid, researchers often select the temperature higher than the melting point of PET, such as 280 ℃ to saturate and melt the PET crystal region, after the PET is melted, the temperature is reduced to 210 ℃ and 280 ℃ to enable the melt to be cooled and crystallized, the crystallinity of the PET is controlled, and then the PET foaming material is prepared through rapid pressure relief. The high-temperature melting process destroys the original geometric shape of the PET material, and in this way it is not possible to obtain fully shaped, particle-free expanded PET beads.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a polyester expanded bead, a polyester expanded bead forming body and a preparation method thereof.
One of the purposes of the invention is to provide a preparation method of polyester expanded beads, which comprises the following steps:
s1, granulating a raw material of polyester foaming beads by an extruder to obtain polyester particles;
s2, impregnating the polyester particles with a high-pressure fluid a in an anhydrous high-pressure container to obtain impregnated polyester particles;
s3, freezing the impregnated polyester particles and storing the polyester particles in an environment below 0 ℃ to obtain frozen gas-locked polyester particles;
s4, heating and foaming the frozen air-locked polyester particles to obtain polyester foamed beads;
the raw material of the polyester foaming bead comprises the following components in parts by weight: 100 parts of polyester, 0-20 parts of nucleating agent and 0-1 part of antioxidant; the polyester is PET and/or PBT.
In S1, the polyester fine particles are preferably prepared by drying and premixing raw materials obtained by granulating the raw materials of the polyester expanded beads in an extruder, and then continuously extruding, strand cutting and granulating or underwater granulating in a twin-screw extruder.
The raw material of the polyester foaming bead comprises polyester, nucleating agent and antioxidant, and the polyester can be PET, PBT or a mixture of PET and PBT; when the polyester is a mixture of PET and PBT, the PBT is present in the mixture of PET and PBT in an amount of 1 to 99 wt.%, preferably 5 to 30 wt.% or 70 to 95 wt.%. Other additives may be added to the raw material for the polyester expanded beads as required. The nucleating agent can be a nucleating agent commonly used in the field, such as an organic nucleating agent and/or an inorganic nucleating agent, preferably, the organic nucleating agent is at least one of PE, PP, PC, nylon and ABS; the inorganic nucleating agent is at least one of calcium carbonate, talcum powder, mica and glass beads. The antioxidant may also be of the type commonly used in the art, such as antioxidant 1010, antioxidant 1076, antioxidant DNP, and the like.
Preferably, the intrinsic viscosity of the polyester is 0.9 to 1.3 dl/g. The use of the above-mentioned intrinsic viscosity polyester enables the preparation of uniform polyester expanded beads. The polyester may contain a branched structure and a crosslinking structure, and the gel content in the polyester is preferably 0-30 wt.%; more preferably 0 to 15 wt.%, said gel content being obtainable by testing.
In S2, the weight percentage of the high-pressure fluid a in the impregnated polyester particles is preferably 1.0-10.0%; more preferably 2.0-8.0%; the high-pressure fluid a is in the impregnated polyesterThe calculation formula of the weight percentage content in the particles is as follows: the weight percentage of the high-pressure fluid a in the impregnated polyester particles is (m)1-m0)×100％/m0(ii) a Wherein m is0Mass of polyester particles, m1The mass of the impregnated polyester particles is the mass of the impregnated polyester particles after the impregnated polyester particles are desorbed for 10min at normal temperature and pressure.
The degree of crystallinity of the impregnated polyester fine particles is preferably 0 to 15%; the degree of crystallinity of the impregnated polyester fine particles is more preferably 0 to 12%. The degree of crystallinity χcIs calculated as xc＝ΔHm/ΔHm100X is 100%; wherein, Δ HmEnthalpy of fusion, Δ H, for impregnating polyester particlesm100The melt enthalpy of the polyester is 140J/g for 100% crystallization.
The solubility and the crystallinity of the high-pressure fluid in the polyester particles can be controlled by controlling the impregnation conditions (temperature, pressure and the like), and the crystallinity is too high and is more than 15 percent, so that the PET particles are difficult to foam; the solubility less than 1% results in too low degree of expansion of the PET expanded beads, and the solubility more than 10% has problems of difficulty in realization and high realization cost. The preparation of the polyester expanded beads can be better realized at the above solubility and crystallinity.
Preferably, the high-pressure fluid a is CO2And/or N2. The pressure of the high-pressure fluid a is preferably 1-10 MPa.
In S3, the freezing is to seal the high pressure fluid in the particles, and the freezing is preferably to use liquid nitrogen or dry ice to rapidly cool the impregnated polyester particles, wherein the boiling point of the liquid nitrogen is minus 196 degrees, and the boiling point of the dry ice is minus 57 degrees. Liquid nitrogen and dry ice are environmentally friendly, inexpensive industrial refrigerants that, when cooled, absorb a large amount of heat from the material and boil into a gas, while the object is rapidly cooled. Preferably, the impregnated polyester particles are placed in a freezing cavity, and the temperature in the freezing cavity is preferably-20 ℃ to-100 ℃, and preferably-20 ℃ to-180 ℃. Due to the fact that
The Tg of PET is 65-75 degrees, and the Tg of PBT is about 60 degrees. After freezing and air locking, the movement of polyester molecular chains is frozen and the movement of high-pressure fluid molecules is greatly confined, so that the impregnated polyester particles can be stored for a long time at minus 20-zero degrees, and the desorption of the high-pressure fluid molecules in the process is obviously reduced, so that the mass weight loss of the impregnated polyester particles in the process is little. The lower the temperature and the shorter the storage time after freezing, the smaller the change of the quality of the stored particles is, the more the high-pressure fluid a in the particles is retained, the more the temperature rise foaming of the particles at S4 is facilitated, but the lower the temperature and the higher the energy consumption are, the freezing storage temperature can be-60 ℃, -40 ℃, -20 ℃, and the appropriate storage temperature can be selected according to actual conditions. The frozen gas-locking polyester particles can be transported in a long distance, wherein cold chain transportation is adopted for transportation, and the temperature of a cold storage is-20-0 ℃, preferably-20-4 ℃, and more preferably-18-8 ℃. And preserving the impregnated polyester particles after cold chain transportation in a refrigeration mode, wherein the refrigeration temperature is minus 18 ℃.
Before S4, the mass weight loss rate of the frozen air-locking polyester particles is preferably less than or equal to 30%/day; the mass weight loss rate of the frozen air-locking polyester particles can be controlled by controlling the storage time and temperature, and the weight loss rate is controlled within the range of 30%/day, so that the foaming stability of the polyester particles can be ensured; preferably 0 to 20%/day, more preferably 0 to 10%/day, and still more preferably 0 to 5%/day.
Preferably, the mass weight loss of the frozen air-locking polyester particles is less than or equal to 30 percent; the weight loss of the frozen gas-locked polyester particles is (m)1-m2)×100％/(m1-m0) Wherein m is0M is the mass of the polyester fine particles1Mass m of the impregnated polyester particles after desorption at normal temperature and pressure for 10min2The quality of the frozen air-locking polyester particles after being desorbed for 10min at normal temperature and pressure is obtained. The lower the mass loss of the frozen air-locked polyester particles is, the better the foaming can be realized, and when the mass loss of the frozen air-locked polyester particles exceeds 30%, the subsequent foaming is obviously influenced. More preferably, the weight loss of the frozen gas-locked polyester particles is less than or equal to 20 percent, and most preferably, the weight loss of the frozen gas-locked polyester particles is less than or equal to 10 percent.
In S4, the frozen gas-locked polyester particles are subjected to a temperature-raising foaming process, wherein the temperature-raising process is performed by at least one of hot air, hot steam and heat radiation, and after the temperature-raising foaming process is performed on the frozen gas-locked polyester particles, the polyester foamed beads having the required particle size are obtained by cooling, sieving and screening.
Another object of the present invention is to provide a polyester expanded bead prepared by the above method.
Still another object of the present invention is to provide a method for producing a polyester expanded bead molded article, comprising the steps of:
A. introducing high-pressure fluid b into the polyester expanded beads in a high-pressure container for carrying out carrier gas treatment to obtain polyester expanded beads subjected to carrier gas treatment;
B. and injecting the polyester expanded beads treated by the carrier gas into a mold, heating by radio frequency, cooling, and demolding to obtain the polyester expanded bead molded body.
In step A, the high-pressure fluid is preferably air or CO2(ii) a The pressure of the high-pressure fluid is preferably 0.1-0.5 MPa;
in the step B, the power of the radio frequency heating is 100-2000W. Injecting the polyester expanded beads treated by the carrier gas into a mold, injecting the polyester expanded beads treated by the carrier gas into the mold, softening the surface of the polyester expanded beads through radio frequency heating, diffusing through a molecular chain interface, cooling and freezing a molecular chain, and demolding to obtain a polyester expanded bead molding body.
The fourth object of the present invention is to provide a molded polyester expanded bead prepared by the above method for preparing a molded polyester expanded bead.
The invention has the beneficial effects that: the invention provides a polyester expanded bead, a polyester expanded bead molded body and a preparation method thereof. Compared with the prior art, the preparation method of the polyester expanded beads has the advantages that the crystallinity of the polyester expanded beads is 15-45%, the density of the polyester expanded beads is 20-500g/L, and the high crystallinity endows the polyester expanded beads with excellent mechanical property and heat resistance. According to the invention, through a freezing and air-locking technology, polyester molecular chains are frozen in a moving way, so that the desorption of high-pressure fluid molecules is obviously reduced, the impregnated polyester particles can be refrigerated and transported for a long time, the mass weight loss in the process is little, the impregnated polyester particles after refrigerated transportation can be heated and foamed on site to prepare expanded polyester foamed beads, the transportation cost is reduced, and the transportation radius is increased; the invention prepares the polyester expanded beads and the polyester expanded bead forming body by an anhydrous high-pressure fluid impregnation process, heat medium heating foaming and radio frequency heating forming, and water is not contacted or is only contacted in a short time in the process, so that the hydrolysis and thermal-oxidative degradation of polyester are avoided or reduced, and the mechanical properties of the polyester expanded beads and the forming body are improved. The polyester expanded bead forming body provided by the invention is formed by radio frequency, the heat resistance can reach more than 150 ℃, the heat resistance is good, the compression strength of 50% deformation can reach 3-10MPa, the heat resistance and the compression performance are obviously higher than those of the existing bead forming bodies such as EPS and EPP, and the polyester expanded bead forming body can be applied to a plurality of fields such as automobiles, rail transit, wind power generation blades, heat-resistant high-strength fillers and the like.
Drawings
FIG. 1 is an optical photograph showing the appearance of PET expanded beads of example 1 of the present invention.
FIG. 2 is a scanning electron micrograph of a cross section of PET expanded beads of example 1 of the present invention.
FIG. 3 is a scanning electron micrograph of a cross section of PET expanded beads of example 3 of the present invention.
Detailed Description
To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to specific examples.
The materials and reagents used in the examples of the present invention and the comparative examples were purchased from the market, and the information and sources of the raw materials in the examples of the present invention are as follows, unless otherwise specified:
PET particles: purchased from Huarun chemical materials science and technology Co., Ltd, with the model CR-8863 and the intrinsic viscosity of 0.9 dl/g;
PET particles: prepared in laboratory, based on the modification of CR-8863, and has an intrinsic viscosity of 1.1 dl/g;
PET particles: prepared in laboratory, based on the modification of CR-8863, and has an intrinsic viscosity of 1.2 dl/g;
PET particles: prepared in laboratory, based on modification with CR-8863, and has an intrinsic viscosity of 0.8 dl/g;
PET particles: prepared in laboratory, based on the modification of CR-8863, and has an intrinsic viscosity of 1.4 dl/g;
PBT particles: purchased from China petrochemical characterization chemical fiber Limited liability company, with the model number GX112 and the intrinsic viscosity of 0.9 dl/g;
antioxidant: the product is purchased from Jiangsu extremely new material company, and the model is JYANOX-1010;
talc powder: is purchased from Asahon powder materials Co., Ltd, Quanzhou city, and has the model of BHS-505.
The data relating to the examples of the invention and the comparative examples were obtained according to the following test methods:
density: the polyester expanded beads are obtained by weighing a 1L measuring cup, and the apparent density of the polyester expanded bead forming body is obtained by testing according to the method provided by GB/T6343-2009;
degree of crystallinity: the degree of crystallinity χcIs calculated as xc＝ΔHm/ΔHm100X is 100%; wherein, Δ HmEnthalpy of fusion, Δ H, for impregnating polyester particlesm100Melt enthalpy of 100% crystalline polyester 140J/g;
heat resistance: testing according to GB/T8811-2008. Placing a sample with the size of 100mm multiplied by 25mm at 150 ℃ for 6h under a no-load state, taking out the sample and testing the size change rate of the sample in each direction;
50% compressive strength: the compression test was carried out according to ASTM Standard D3575-08 of the United states of America, and a compression test was carried out using a compression rate of 10mm/min, to obtain a compression strength at which the molded body was compressed by 50%.
Example 1
The preparation method of the polyester expanded beads in the embodiment comprises the following steps:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 0.9dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 5.0% and a crystallinity of 0%;
s3, rapidly freezing the impregnated polyester particles by adopting liquid nitrogen, wherein the temperature of a cooling cavity is minus 60 ℃, and then storing the impregnated polyester particles subjected to freezing and air locking treatment in an environment of minus 20 ℃ for 1 day to obtain the frozen air-locked polyester particles; the content of the high-pressure fluid in the frozen gas-locked polyester particles is 5.0 percent, and the mass weight loss of the high-pressure fluid in the frozen gas-locked polyester particles is 0 percent;
and S4, heating and foaming the frozen air-locked polyester particles, and cooling and screening to obtain the polyester foamed beads.
The research shows that: the prepared polyester expanded beads are ellipsoidal, have 100% closed cell structure, have cell size of 80 microns, crystallinity of 32% and density of 100 g/L.
The method for preparing the polyester expanded bead molding body of the embodiment comprises the following steps:
injecting the polyester foaming beads into a high-pressure tank, and passing through CO with high pressure of 0.2MPa2And (3) carrying out fluid impregnation carrier gas treatment for 12h, injecting the polyester expanded beads subjected to carrier gas treatment into a mold, heating the polyester expanded beads in the mold by using a radio frequency with the power of 1000W, and carrying out molecular chain interface diffusion, cooling and demolding to obtain a polyester expanded bead molded body.
The research shows that: the density of the polyester bead-molded article was 110g/L, the crystallinity was 40%, the dimensional change did not occur after the 150 degree treatment for 6 hours, and the 50% compressive strength was 4.5 MPa.
Example 2
The preparation method of the polyester expanded beads in the embodiment comprises the following steps:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 1.1dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 9.0% and a crystallinity of 5%;
s3, rapidly freezing the impregnated polyester particles by adopting liquid nitrogen, wherein the temperature of a cooling cavity is minus 60 ℃, and then storing the impregnated polyester particles subjected to freezing and air locking treatment in an environment of minus 20 ℃ for 7 days to obtain the frozen air-locked polyester particles; the content of the high-pressure fluid in the frozen gas-locked polyester particles is 8.2 percent, and the mass weight loss of the high-pressure fluid in the frozen gas-locked polyester particles is 8.9 percent;
and S4, heating and foaming the frozen air-locked polyester particles, and cooling and screening to obtain the polyester foamed beads.
The research shows that: the prepared polyester expanded beads are ellipsoidal, have 100% closed cell structure, cell size of 100 microns, crystallinity of 35% and density of 60 g/L.
The method for preparing the polyester expanded bead molding body of the embodiment comprises the following steps:
injecting the polyester foaming beads into a high-pressure tank body, and passing CO with high pressure of 0.2MPa2And (3) carrying out fluid impregnation carrier gas treatment for 12h, injecting the polyester expanded beads subjected to carrier gas treatment into a mold, heating the polyester expanded beads in the mold by using a radio frequency with the power of 1000W, and carrying out molecular chain interface diffusion, cooling and demolding to obtain a polyester expanded bead molded body.
The research shows that: the density of the polyester bead-molded article was 70g/L, the crystallinity was 40%, the dimensional change did not occur after the 150 degree treatment for 6 hours, and the 50% compressive strength was 2.3 MPa.
Example 3
The preparation method of the polyester expanded beads in the embodiment comprises the following steps:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 1.2dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 5.0% and a crystallinity of 15%;
s3, rapidly freezing the impregnated polyester particles by adopting liquid nitrogen, wherein the temperature of a cooling cavity is minus 60 ℃, and then storing the impregnated polyester particles subjected to freezing and air locking treatment in an environment of minus 20 ℃ for 15 days to obtain the frozen air-locked polyester particles; the content of the high-pressure fluid in the frozen gas-locked polyester particles is 4.0 percent, and the mass weight loss of the high-pressure fluid in the frozen gas-locked polyester particles is 20 percent;
and S4, heating and foaming the frozen air-locked polyester particles, and cooling and screening to obtain the polyester foamed beads.
The research shows that: the prepared polyester expanded beads are ellipsoidal, have 100% closed cell structure, have cell size of 15 microns, crystallinity of 42% and density of 250 g/L.
The method for preparing the polyester expanded bead molding body of the embodiment comprises the following steps:
injecting the polyester foaming beads into a high-pressure tank body, and passing CO with high pressure of 0.4MPa2And (3) carrying out fluid impregnation carrier gas treatment for 12h, injecting the polyester expanded beads subjected to carrier gas treatment into a mold, heating the polyester expanded beads in the mold by selecting a radio frequency with the power of 1400W, and carrying out molecular chain interface diffusion, cooling and demolding to obtain a polyester expanded bead molding body.
The research shows that: the density of the polyester bead-molded article was 300g/L, the crystallinity was 45%, the dimensional change did not occur after the 150 degree treatment for 6 hours, and the 50% compressive strength was 8.8 MPa.
Example 4
The preparation method of the polyester expanded beads in the embodiment comprises the following steps:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 1.2dl/g), 15 parts by weight of PBT particles (the intrinsic viscosity is 0.9dl/g) and 0.8 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 7.0% and a crystallinity of 10%;
s3, rapidly freezing the impregnated polyester particles by adopting liquid nitrogen, wherein the temperature of a cooling cavity is minus 60 ℃, and then storing the impregnated polyester particles subjected to freezing and air locking treatment in an environment of minus 18 ℃ for 1 day to obtain the frozen air-locked polyester particles; the content of the high-pressure fluid in the frozen gas-locked polyester particles is 6.9 percent, and the mass weight loss of the high-pressure fluid in the frozen gas-locked polyester particles is 1.4 percent;
and S4, heating and foaming the frozen air-locked polyester particles, and cooling and screening to obtain the polyester foamed beads.
The research shows that: the prepared polyester expanded beads are spherical, have a 100% closed cell structure, a cell size of 50 microns, a crystallinity of 35% and a density of 120 g/L.
The method for preparing the polyester expanded bead molding body of the embodiment comprises the following steps:
injecting the polyester foaming beads into a high-pressure tank body, and passing CO with high pressure of 0.3MPa2And (3) carrying out fluid impregnation carrier gas treatment for 12h, injecting the polyester expanded beads subjected to carrier gas treatment into a mold, heating the polyester expanded beads in the mold by selecting a radio frequency with the power of 1100W, and carrying out molecular chain interface diffusion, cooling and demolding to obtain a polyester expanded bead molded body. The research shows that: the density of the polyester bead-molded article was 140g/L, the crystallinity was 43%, the dimensional change did not occur after 150 degrees treatment for 6 hours, and the 50% compressive strength was 3.2 MPa.
Example 5
The preparation method of the polyester expanded beads in the embodiment comprises the following steps:
s1, drying, premixing and carrying out twin-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 1.2dl/g), 10 parts by weight of PBT particles (the intrinsic viscosity is 0.9dl/g), 2 parts by weight of talcum powder and 0.8 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 12.0% and a crystallinity of 12%;
s3, rapidly freezing the impregnated polyester particles by adopting liquid nitrogen, wherein the temperature of a cooling cavity is minus 60 ℃, and then storing the impregnated polyester particles subjected to freezing and air locking treatment in an environment of minus 18 ℃ for 1 day to obtain the frozen air-locked polyester particles; the content of the high-pressure fluid in the frozen gas-locked polyester particles is 11.8%, and the mass weight loss of the high-pressure fluid in the frozen gas-locked polyester particles is 1.6%;
and S4, heating and foaming the frozen air-locked polyester particles, and cooling and screening to obtain the polyester foamed beads.
The research shows that: the prepared polyester expanded beads are spherical, have a 100% closed cell structure, a cell size of 40 microns, a crystallinity of 35% and a density of 130 g/L.
The method for preparing the polyester expanded bead molding body of the embodiment comprises the following steps:
injecting the polyester foaming beads into a high-pressure tank body, and passing CO with high pressure of 0.3MPa2And (3) carrying out fluid impregnation carrier gas treatment for 12h, injecting the polyester expanded beads subjected to carrier gas treatment into a mold, heating the polyester expanded beads in the mold by using a radio frequency with the power of 1200W, and carrying out molecular chain interface diffusion, cooling and demolding to obtain a polyester expanded bead molded body.
The research shows that: the density of the polyester bead-molded article was 140g/L, the crystallinity was 45%, the dimensional change did not occur after 150 degrees treatment for 6 hours, and the 50% compressive strength was 3.8 MPa.
Example 6
The preparation method of the polyester expanded beads in the embodiment comprises the following steps:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 0.9dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 5.0% and a crystallinity of 0%;
s3, rapidly freezing the impregnated polyester particles by adopting liquid nitrogen, wherein the temperature of a cooling cavity is minus 20 ℃, and then storing the impregnated polyester particles subjected to freezing and air locking treatment in an environment of minus 20 ℃ for 15 days to obtain the frozen air-locked polyester particles; the content of the high-pressure fluid in the frozen gas-locked polyester particles is 3.8 percent, and the mass weight loss of the high-pressure fluid in the frozen gas-locked polyester particles is 24 percent;
and S4, heating and foaming the frozen air-locked polyester particles, and cooling and screening to obtain the polyester foamed beads.
The research shows that: the prepared polyester expanded beads are ellipsoidal, have 100% closed cell structure, cell size of 100 microns, crystallinity of 32% and density of 110 g/L.
The method for preparing the polyester expanded bead molding body of the embodiment comprises the following steps:
injecting the polyester foaming beads into a high-pressure tank body, and passing CO with high pressure of 0.2MPa2And (3) carrying out fluid impregnation carrier gas treatment for 12h, injecting the polyester expanded beads subjected to carrier gas treatment into a mold, heating the polyester expanded beads in the mold by using a radio frequency with the power of 1000W, and carrying out molecular chain interface diffusion, cooling and demolding to obtain a polyester expanded bead molded body.
The research shows that: the density of the polyester bead-molded article was 130g/L, the crystallinity was 40%, the dimensional change did not occur after the 150 degree treatment for 6 hours, and the 50% compressive strength was 4.9 MPa.
Example 7
The preparation method of the polyester expanded beads in the embodiment comprises the following steps:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 0.9dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 5.0% and a crystallinity of 0%;
s3, rapidly freezing the impregnated polyester particles by adopting liquid nitrogen, wherein the temperature of a cooling cavity is minus 20 ℃, then transporting the impregnated polyester particles subjected to freezing and gas locking treatment in a refrigeration house with the temperature of minus 20 ℃ for 1000 kilometers, and then storing the impregnated polyester particles in the refrigeration house with the temperature of minus 18 ℃ for 7 days to obtain the frozen gas-locking polyester particles; the content of the high-pressure fluid in the frozen gas-locked polyester particles is 4.7 percent, and the mass weight loss of the high-pressure fluid in the frozen gas-locked polyester particles is 6 percent;
and S4, heating and foaming the frozen air-locked polyester particles, and cooling and screening to obtain the polyester foamed beads.
The research shows that: the prepared polyester expanded beads are ellipsoidal, have 100% closed cell structure, cell size of 100 microns, crystallinity of 32% and density of 100 g/L.
The method for preparing the polyester expanded bead molding body of the embodiment comprises the following steps:
injecting the polyester foaming beads into a high-pressure tank body, and passing CO with high pressure of 0.2MPa2And (3) carrying out fluid impregnation carrier gas treatment for 12h, injecting the polyester expanded beads subjected to carrier gas treatment into a mold, heating the polyester expanded beads in the mold by using a radio frequency with the power of 1000W, and carrying out molecular chain interface diffusion, cooling and demolding to obtain a polyester expanded bead molded body.
The research shows that: the density of the polyester bead-molded article was 110g/L, the crystallinity was 40%, the dimensional change did not occur after the 150 degree treatment for 6 hours, and the 50% compressive strength was 4.5 MPa.
Example 8
The preparation method of the polyester expanded beads in the embodiment comprises the following steps:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PBT particles (the intrinsic viscosity is 0.9dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 5.0% and a crystallinity of 0%;
s3, rapidly freezing the impregnated polyester particles by adopting liquid nitrogen, wherein the temperature of a cooling cavity is minus 60 ℃, and then storing the impregnated polyester particles subjected to freezing and air locking treatment in an environment of minus 20 ℃ for 1 day to obtain the frozen air-locked polyester particles; the content of the high-pressure fluid in the frozen gas-locked polyester particles is 5.0 percent, and the mass weight loss of the high-pressure fluid in the frozen gas-locked polyester particles is 0 percent;
and S4, heating and foaming the frozen air-locked polyester particles, and cooling and screening to obtain the polyester foamed beads.
The research shows that: the prepared polyester expanded beads are ellipsoidal, have 100% closed cell structure, cell size of 100 microns, crystallinity of 25% and density of 150 g/L.
The method for preparing the polyester expanded bead molding body of the embodiment comprises the following steps:
injecting the polyester foaming beads into a high-pressure tank, and passing through CO with high pressure of 0.2MPa2And (3) carrying out fluid impregnation carrier gas treatment for 12h, injecting the polyester expanded beads subjected to carrier gas treatment into a mold, heating the polyester expanded beads in the mold by using a radio frequency with the power of 1000W, and carrying out molecular chain interface diffusion, cooling and demolding to obtain a polyester expanded bead molded body.
The research shows that: the density of the polyester bead-molded article was 180g/L, the crystallinity was 40%, the dimensional change did not occur after the 150 degree treatment for 6 hours, and the 50% compressive strength was 4.2 MPa.
Comparative example 1
This comparative example differs from example 1 only in that step S3 is not included, and the polyester microparticles described in this comparative example were prepared by:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 0.9dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 5.0% and a crystallinity of 0%;
s3, after the impregnated polyester particles are placed for 1 day at normal temperature and normal pressure, the content of the high-pressure fluid in the impregnated polyester particles is reduced to 1.5%, and the mass weight loss of the high-pressure fluid in the process is 70%. The resulting impregnated polyester microparticles became only white when heated in a heat medium, the shape of the particles was substantially retained, and the density was 780 g/L.
Comparative example 2
This comparative example is different from example 1 only in step S3, and the polyester fine particles described in this comparative example were prepared by:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 0.9dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 5.0% and a crystallinity of 0%;
s3, storing the impregnated polyester particles for 1 day at minus 18 ℃, wherein the content of the high-pressure fluid in the impregnated polyester particles is 3.2 percent, and the mass weight loss of the high-pressure fluid in the impregnated polyester is 36 percent;
s4, heating and foaming the frozen air-locked polyester particles, and cooling to obtain polyester foamed particles; the obtained impregnated polyester particles can be foamed at an elevated temperature in a heat medium, and the density is 320g/L, which shows that the CO is obviously increased by only storing at a low temperature without low-temperature gas locking treatment2The escape of fluid during low temperature storage reduces the degree of expansion of the impregnated polyester particles during elevated temperature foaming.
Comparative example 3
This comparative example is different from example 1 only in step S3, and the polyester fine particles described in this comparative example were prepared by:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 0.9dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 5.0% and a crystallinity of 0%;
s3, rapidly freezing and impregnating the polyester particles by adopting liquid nitrogen, wherein the temperature of a cooling cavity is minus 60 ℃, then placing the impregnated polyester particles subjected to freezing and air locking treatment for 1 day in a normal-pressure room-temperature environment, wherein the content of high-pressure fluid in the impregnated polyester particles is 2.0%, and the mass loss of the high-pressure fluid in the process is 60%;
s4, heating and foaming the frozen air-locked polyester particles, and cooling to obtain polyester foamed particles; the obtained impregnated polyester particles can be foamed at an elevated temperature in a heat medium, and the density is 400g/L, which shows that the CO can be inhibited to a certain extent by low-temperature gas-locking treatment2Escape of fluid, but only through low temperature lockThe reason that no low temperature storage will result in significant CO2The escape of fluid, which reduces the degree of expansion of the impregnated polyester particles during elevated temperature foaming.
Comparative example 4
The preparation method of the PET foam of the comparative example comprises the following steps:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 0.9dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, subjecting polyester particles to high-pressure CO2Stirring fluid, water and a dispersing agent, heating to the temperature near the melting point, soaking, and quickly decompressing and foaming to obtain the PET foam.
The foam obtained in this comparative example was an irregular, pale yellow, agglomerate with a density of 150g/L and an intrinsic viscosity of 0.2dl/g, indicating significant degradation of the PET resin during the foaming process.
Comparative example 5
The preparation method of the PET foam of the comparative example comprises the following steps:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 0.9dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, subjecting polyester particles to high-pressure CO2Fluid and PET are soaked at the temperature near the melting point, and the PET foaming body is obtained by rapid decompression and foaming.
The foam obtained in this comparative example was an irregularly shaped, expanded agglomerate having a density of 100g/L and an intrinsic viscosity of 0.8dl/g, indicating that the PET resin had melt-agglomerated during the foaming process, since expanded beads having a completely isolated form, a spherical shape or an ellipsoidal shape, could not be obtained.
Comparative example 6
The comparative example, in which the intrinsic viscosity of the PET pellets was 0.7dl/g, was different from example 1 in the intrinsic viscosity of the PET pellets.
The preparation method of the polyester expanded beads in the comparative example comprises the following steps:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 0.7dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 5.0% and a crystallinity of 5%;
s3, rapidly freezing the impregnated polyester particles by adopting liquid nitrogen, wherein the temperature of a cooling cavity is minus 60 ℃, and then storing the impregnated polyester particles subjected to freezing and air locking treatment in an environment of minus 20 ℃ for 1 day to obtain the frozen air-locked polyester particles; the content of the high-pressure fluid in the frozen gas-locked polyester particles is 5.0 percent, and the mass weight loss of the high-pressure fluid in the frozen gas-locked polyester particles is 0 percent;
and S4, heating and foaming the frozen air-locked polyester particles, and cooling and screening to obtain the polyester foamed beads.
The research shows that: the prepared polyester expanded beads are cylindrical and have a 100% closed cell structure, a cell size of 40 microns, a crystallinity of 40% and a density of 380 g/L.
The expanded polyester beads obtained in the comparative example are cylindrical, have a density of 380g/L, and show that the PET resin with the characteristic viscosity of less than 0.9dl/g is difficult to foam by heating, and the obtained expanded polyester beads have high density and small expansion ratio.
Comparative example 7
The comparative example differs from example 1 only in the intrinsic viscosity of the PET pellets, which in this comparative example is 1.4 dl/g.
The preparation method of the polyester expanded beads in the embodiment comprises the following steps:
s1, drying, premixing and carrying out double-screw continuous extrusion and grain cutting on 100 parts by weight of PET (polyethylene terephthalate) particles (the intrinsic viscosity is 1.4dl/g) and 0.5 part by weight of antioxidant to obtain polyester particles;
s2, dipping the polyester particles in anhydrous high-pressure fluid to obtain high-pressure CO2Fluidizing to obtain impregnated polyester particles having a high pressure fluid content of 5.0% and a crystallinity of 6%;
s3, rapidly freezing the impregnated polyester particles by adopting liquid nitrogen, wherein the temperature of a cooling cavity is minus 60 ℃, and then storing the impregnated polyester particles subjected to freezing and air locking treatment in an environment of minus 20 ℃ for 1 day to obtain the frozen air-locked polyester particles; the content of the high-pressure fluid in the frozen gas-locked polyester particles is 5.0 percent, and the mass weight loss of the high-pressure fluid in the frozen gas-locked polyester particles is 0 percent;
and S4, heating and foaming the frozen air-locked polyester particles, and cooling and screening to obtain the polyester foamed beads.
The research shows that: the prepared polyester expanded beads are cylindrical and have a 100% closed cell structure, a cell size of 30 microns, a crystallinity of 42% and a density of 450 g/L.
The polyester expanded particles obtained in the comparative example are cylindrical, the density is 450g/L, the condition that the PET resin with the characteristic viscosity higher than 1.3dl/g is difficult to foam by heating is shown, and the obtained polyester expanded beads have high density and small expansion ratio.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.