阅读说明：本技术 一种epo发泡珠粒及其制备方法 (EPO (erythropoietin) foamed bead and preparation method thereof ) 是由 曾佳 路骐豪 刘缓缓 朱民 杨亮炯 蒋璠晖 熊业志 何若虚 于 2021-08-05 设计创作，主要内容包括：本发明公开了一种EPO发泡珠粒及其制备方法,一种EPO发泡珠粒,其特征在于：包括复合微粒芯层和复合微粒皮层,所述复合微粒皮层与复合微粒芯层的重量比为3:97～20:80；所述复合微粒芯层包括0.01-0.1%的泡孔成核剂、0-20%的增韧剂、0-20%的工业油性物质和79%-99.9%的聚苯乙烯；所述复合微粒皮层包括55-90%的线性低密度聚乙烯和10-45%马来酸酐接枝改性氢化苯乙烯-丁二烯嵌段共聚物。本发明采用多层包覆式结构作为发泡原料,使得皮层具有良好的熔结性和表观质量,芯层具有优异的发泡效果和刚性以及优异的尺寸稳定性,保证制件的倍率可调性；发泡珠粒制备时采用超临界CO2高温釜式发泡方法,工艺简单、能耗低、污染少、珠粒表观质量优异,还可降低后续制品的成型压力,节约能源。(The invention discloses an EPO (erythropoietin) expanded bead and a preparation method thereof, and the EPO expanded bead is characterized in that: the composite particle core layer comprises a composite particle core layer and a composite particle skin layer, wherein the weight ratio of the composite particle skin layer to the composite particle core layer is 3: 97-20: 80; the composite particle core layer comprises 0.01-0.1% of foam cell nucleating agent, 0-20% of toughening agent, 0-20% of industrial oily substance and 79% -99.9% of polystyrene; the composite particle skin layer comprises 55-90% of linear low density polyethylene and 10-45% of maleic anhydride graft modified hydrogenated styrene-butadiene block copolymer. According to the invention, a multi-layer coating structure is adopted as a foaming raw material, so that the skin layer has good sintering property and apparent mass, the core layer has excellent foaming effect and rigidity and excellent dimensional stability, and the multiplying power adjustability of a workpiece is ensured; the preparation of the foaming beads adopts a supercritical CO2 high-temperature kettle type foaming method, the process is simple, the energy consumption is low, the pollution is less, the apparent quality of the beads is excellent, the molding pressure of subsequent products can be reduced, and the energy is saved.)

1. An EPO expanded bead, characterized in that: the composite particle core layer comprises a composite particle core layer and a composite particle skin layer, wherein the weight ratio of the composite particle skin layer to the composite particle core layer is 3: 97-20: 80; the composite particle core layer comprises 0.01-0.1% of foam cell nucleating agent, 0-20% of toughening agent, 0-20% of industrial oily substance and 79% -99.9% of polystyrene; the composite particle skin layer comprises 55-90% of linear low density polyethylene and 10-45% of maleic anhydride graft modified hydrogenated styrene-butadiene block copolymer.

2. The EPO expanded bead according to claim 1, wherein: the foam cell nucleating agent is selected from one or more of zinc borate, stearate, talc, montmorillonite and fluoride, wherein the specification of the foam cell nucleating agent is 8-20 mu m.

3. The EPO expanded bead according to claim 1, wherein: the toughening agent is one or more of styrene-butadiene-styrene block copolymer SBS, SEBS copolymer and SEPS copolymer.

4. The EPO expanded bead according to claim 1, wherein: the industrial oily substance is colorless and odorless transparent liquidThe kinematic viscosity of the white oil is 30-110mm at 40 DEG C²The flash point is higher than 200 ℃ per second.

5. The EPO expanded bead according to claim 1, wherein: the industrial oily substance is 50-120# industrial white oil.

6. The EPO expanded bead according to claim 1, wherein: the polystyrene is GPPS or HIPS, the molecular weight of the polystyrene is between 20 and 35 ten thousand, the melt index is between 3 and 11g/10min, the bending strength is between 400 and 1000MPa, and the Vicat softening point is between 90 and 110 ℃.

7. The EPO expanded bead according to claim 1, wherein: the melting point of the linear low-density polyethylene is 100-110 ℃, the melt index is 5-12g/10min, the tensile yield stress is more than 9.0MPa, and the Vicat softening point is 70-110 ℃.

8. The EPO expanded bead according to claim 1, wherein: the maleic anhydride graft-modified hydrogenated styrene-butadiene block copolymer may be replaced with an SEBS copolymer or an SBR copolymer.

9. A method for preparing EPO expanded beads is characterized in that: the method comprises the following steps:

(1) preparing formula raw materials of a composite particle core layer and a composite particle skin layer, extruding a composite plastic filament containing the core layer and the skin layer by adopting a co-extrusion process, and cutting the composite plastic filament into composite particles with the length of 1.5-2.5mm and the weight of 1.5-3.0mg by using a granulator;

(2) uniformly mixing the composite particles prepared in the step (1), the aqueous dispersion liquid and the dispersing auxiliary agent, and putting the mixture serving as a dispersion system into a high-temperature-resistant closed kettle for stirring and foaming, wherein the foaming step is as follows:

s1: continuously stirring the dispersion system in a reaction kettle, slowly heating the reaction kettle to T ℃, and introducing CO into the reaction kettle through a booster pump when the temperature in the reaction kettle rises to T-30 DEG C₂When the pressure in the reaction kettle rises to 50-70% P, the booster pump stops working and maintains the pressure in the reaction kettle for 15-30 min;

s2: the reaction kettle is continuously heated, and CO is continuously pumped into the reaction kettle through a booster pump₂When the temperature in the reaction kettle rises to T-0.5 ℃ and the pressure increases to P, stopping heating and suspending the booster pump to work, and maintaining the temperature and the pressure in the reaction kettle for 5-15min after the temperature in the reaction kettle slowly rises to T ℃;

s3: after the treatment of S2, the composite particles in the mixture in the reaction kettle are coated with CO₂Infiltrating gas, and discharging the mixture in the reaction kettle to an atmospheric pressure environment to obtain expanded EPO foamed beads;

s4: the EPO expanded beads obtained in S3 were put into an expansion tube in a steam atmosphere and expanded again.

10. The method for preparing EPO expanded beads according to claim 9, wherein: the dispersing aid in the step (2) is two or three of butter, kaolin and stearic acid, wherein the weight ratio of the butter is 3 per thousand-2% of the composite particles, the weight ratio of the kaolin is 1 per thousand-1% of the composite particles, and the weight ratio of the stearic acid is 3 per thousand-3% of the composite particles.

11. The method for preparing EPO expanded beads according to claim 9, wherein: CO in the step (2)₂The gas can be changed into one or more mixed gas of air, nitrogen, water vapor and carbon dioxide.

12. The method for preparing EPO expanded beads according to claim 9, wherein: the foaming temperature T in the step (2) is 155-170 ℃, the foaming pressure P is 3-5.5MPa, and the bulk density rho is 50-75 g/L; the foam bead has the cells of 100-300 mu m and the skin layer thickness of 5-30 mu m.

13. The method for preparing EPO expanded beads according to claim 9, wherein: the length of the foaming pipe in the step (2) is 1.5-3m, and the temperature in the foaming pipe is 80-110 ℃.

The technical field is as follows:

the invention belongs to the technical field of preparation of foaming materials, and particularly relates to EPO (erythropoietin) foaming beads and a preparation method thereof.

Background art:

EPO is a mixture of expanded polystyrene and polyethylene, which is a copolymer produced by a special polymerization process. EPO material has material toughness and tear strength and better permanent compression set performance that EPS did not have, has intensity and compressive resistance that EPE did not, and is very easily cracked and produce the piece different with EPS under the impact of external force, and EPO can not be cracked and produce the piece after the impact, and sturdiness, durability and toughness are better, and apparent quality is good, has outstanding shock resistance. At present, EPO foaming is mainly chemical foaming, and the problems of complex process preparation flow, high energy consumption, poor appearance quality of bead products and the like exist.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

The invention content is as follows:

the present invention is directed to provide an EPO expanded bead and a method for preparing the same, thereby overcoming the above-mentioned disadvantages of the prior art.

In order to achieve the purpose, the invention provides EPO (erythropoietin) expanded beads, which comprise a composite particle core layer and a composite particle skin layer, wherein the weight ratio of the composite particle skin layer to the composite particle core layer is 3: 97-20: 80; the composite particle core layer comprises 0.01-0.1% of foam cell nucleating agent, 0-20% of toughening agent, 0-20% of industrial oily substance and 79% -99.9% of polystyrene; the composite particle skin layer comprises 55-90% of linear low density polyethylene and 10-45% of maleic anhydride graft modified hydrogenated styrene-butadiene block copolymer.

The foam cell nucleating agent is selected from one or more of zinc borate, stearate, talc, montmorillonite and fluoride, wherein the specification of the foam cell nucleating agent is 8-20 mu m.

The toughening agent is one or more of styrene-butadiene-styrene block copolymer SBS, SEBS copolymer and SEPS copolymer.

The industrial oily substance is colorless and odorless transparent white liquid oil with kinematic viscosity of 30-110mm at 40 deg.C²The flash point is higher than 200 ℃ per second.

The industrial oily substance is 50-120# industrial white oil.

The polystyrene is GPPS or HIPS, the molecular weight of the polystyrene is between 20 and 35 ten thousand, the melt index is between 3 and 11g/10min, the bending strength is between 400 and 1000MPa, and the Vicat softening point is between 90 and 110 ℃.

The melting point of the linear low-density polyethylene is 100-110 ℃, the melt index is 5-12g/10min, the tensile yield stress is more than 9.0MPa, and the Vicat softening point is 70-110 ℃.

The maleic anhydride graft-modified hydrogenated styrene-butadiene block copolymer may be replaced with an SEBS copolymer or an SBR copolymer.

A preparation method of EPO expanded beads comprises the following steps:

(1) preparing formula raw materials of a composite particle core layer and a composite particle skin layer, extruding a composite plastic filament containing the core layer and the skin layer by adopting a co-extrusion process, and cutting the composite plastic filament into composite particles with the length of 1.5-2.5mm and the weight of 1.5-3.0mg by using a granulator;

(2) uniformly mixing the composite particles prepared in the step (1), the aqueous dispersion liquid and the dispersing auxiliary agent, and putting the mixture serving as a dispersion system into a high-temperature-resistant closed kettle for stirring and foaming, wherein the foaming step is as follows:

s1: the dispersion system is continuously stirred in the reaction kettle, the temperature of the reaction kettle is slowly increased to T ℃, and when the temperature in the reaction kettle is increased to T-30 ℃, the dispersion system is fed into the reaction kettle through a booster pumpIntroducing CO into the reaction kettle₂When the pressure in the reaction kettle rises to 50-70% P, the booster pump stops working and maintains the pressure in the reaction kettle for 15-30 min;

s2: the reaction kettle is continuously heated, and CO is continuously pumped into the reaction kettle through a booster pump₂When the temperature in the reaction kettle rises to T-0.5 ℃ and the pressure increases to P, stopping heating and suspending the booster pump to work, and maintaining the temperature and the pressure in the reaction kettle for 5-15min after the temperature in the reaction kettle slowly rises to T ℃;

s3: after the treatment of S2, the composite particles in the mixture in the reaction kettle are coated with CO₂Infiltrating gas, and discharging the mixture in the reaction kettle to an atmospheric pressure environment to obtain expanded EPO foamed beads;

s4: placing the EPO foamed beads prepared by the S3 into a foaming pipe in a steam environment for foaming again;

s5: if beads with a high expansion ratio (bulk density < 50g/l) are required, after step S4, the expanded EPO beads are placed in a precompression tank, compressed air is introduced into the precompression tank to repress the pressure, and then the expanded EPO beads are heated by steam to continue to expand to a desired density.

The dispersing aid in the step (2) is two or three of butter, kaolin and stearic acid, wherein the weight ratio of the butter is 3 per thousand-2% of the composite particles, the weight ratio of the kaolin is 1 per thousand-1% of the composite particles, and the weight ratio of the stearic acid is 3 per thousand-3% of the composite particles.

CO in the step (2)₂The gas can be changed into one or more mixed gas of air, nitrogen, water vapor and carbon dioxide.

The foaming temperature T in the step (2) is 155-170 ℃, the foaming pressure P is 3-5.5MPa, and the bulk density rho is 50-75 g/L; the foam holes of the foam beads are 100-300 mu m, and the skin layer thickness of the foam beads is 5-30 mu m;

the length of the foaming pipe in the step (2) is 1.5-3m, and the temperature in the foaming pipe is 80-110 ℃.

When beads with high foaming ratio (the bulk density is less than 50g/l) are needed, the expanded EPO beads are placed in a pre-pressing tank, compressed air is pressurized in the pre-pressing tank, and then the EPO beads are heated by steam and continuously expanded to the needed density.

Compared with the prior art, one aspect of the invention has the following beneficial effects:

according to the invention, a multi-layer coating structure is adopted as a foaming raw material, so that the skin layer has good sintering property and apparent quality, the core layer has excellent foaming effect, and the multiplying power adjustability of a workpiece is ensured; the preparation of the foaming beads adopts a high-temperature kettle type foaming method of a supercritical CO2 system, the process is simple, the energy consumption is low, the pollution is less, the apparent quality of the beads is excellent, the molding pressure of subsequent products can be reduced, and the energy is saved.

The specific implementation mode is as follows:

the following detailed description of specific embodiments of the invention is provided, but it should be understood that the scope of the invention is not limited to the specific embodiments.

Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.

Example 1:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight proportion of the composite particle skin layer is 10%, and the weight proportion of the core layer is 90%; the composite particle core layer comprises 0.1% of zinc borate, 3% of 50# industrial white oil, 20% of toughening agent SBS and the balance of PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE model B1 and 45% maleic anhydride branched modified SEBS.

A preparation method of EPO expanded beads comprises the following steps:

(1) preparing formula raw materials of a composite particle core layer and a composite particle skin layer, extruding a composite plastic filament containing the core layer and the skin layer by adopting a co-extrusion process, and cutting the composite plastic filament into composite particles with the length of 1.5-2.5mm and the weight of 1.5-3.0mg by using a granulator;

(2) uniformly mixing the composite particles prepared in the step (1), the aqueous dispersion liquid and the dispersing auxiliary agent, and putting the mixture serving as a dispersion system into a high-temperature-resistant closed kettle for stirring and foaming, wherein the foaming step is as follows:

s1: continuously stirring the dispersion system in a reaction kettle, slowly heating the reaction kettle to 165 ℃, and introducing CO into the reaction kettle through a booster pump when the temperature in the reaction kettle rises to 135 DEG C₂When the foaming pressure of the gas is 3.5MPa, and the pressure in the reaction kettle is increased to 1.75-2.45 MPa, the booster pump stops working, and the pressure in the reaction kettle is maintained for 15-30 min;

s2: the reaction kettle is continuously heated, and CO is continuously pumped into the reaction kettle through a booster pump₂When the temperature in the reaction kettle rises to 164.5 ℃ and the pressure in the reaction kettle increases to 3.5MPa, stopping heating and suspending the work of the booster pump, and after the temperature in the reaction kettle slowly rises to 164 ℃, maintaining the temperature and the pressure in the reaction kettle for 5-15 min;

s3: after the treatment of S2, the composite particles in the mixture in the reaction kettle are coated with CO₂Infiltrating gas, and discharging the mixture in the reaction kettle to an atmospheric pressure environment to obtain expanded EPO foamed beads;

s4: and placing the EPO foamed beads prepared by the S3 into a foaming pipe in a steam environment for foaming again, wherein the length of the foaming pipe is 1.5-3m, and the temperature in the foaming pipe is 80-110 ℃.

The EPO beads prepared by the above method have a bulk density of 60g/L, have a small number of pinholes, pits and other defects on the surface, and have a good degree of adhesion between particles of a molded product.

Example 2:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight proportion of the composite particle skin layer is 10%, and the weight proportion of the core layer is 90%; the composite particle core layer comprises 0.1% of fluoride, 3% of 50# industrial white oil, 20% of toughening agent SBS and the balance of PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE model B1 and 45% maleic anhydride branched modified SEBS.

The preparation was carried out in the same manner as in example 1, except that the foaming temperature T was 167 ℃ and the foaming pressure was 3 MPa.

The EPO beads obtained by the above method have a bulk density of 65g/L, a large number of pinholes, pits and other defects on the surface, and a good degree of adhesion between particles of a molded product.

Example 3:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight proportion of the composite particle skin layer is 10%, and the weight proportion of the core layer is 90%; the composite particle core layer comprises 0.1% of zinc borate, 3% of 120# industrial white oil, 20% of toughening agent SBS and the balance of PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE model B1 and 45% maleic anhydride branched modified SEBS.

The preparation is identical to example 1, except that the foaming temperature T is 164 ℃ and the foaming pressure is 3.3 MPa.

The EPO beads prepared by the above method have a bulk density of 58g/L, a small number of pinholes, pits and other defects on the surface, and a good degree of adhesion between particles of a molded product.

Example 4:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight proportion of the composite particle skin layer is 10%, and the weight proportion of the core layer is 90%; the composite particle core layer comprises 0.1% of zinc borate, 3% of 50# industrial white oil and the balance of PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE model B1 and 45% maleic anhydride branched modified SEBS.

The preparation process is identical to that of example 1, except that the foaming temperature T is 168 ℃ and the foaming pressure is 3.7 MPa.

The EPO beads obtained by the above method have a bulk density of 56g/L, and have a small number of pinholes, pits, and other defects on the surface, resulting in poor adhesion between particles of the molded article.

Example 5:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight proportion of the composite particle skin layer is 10%, and the weight proportion of the core layer is 90%; the composite particle core layer comprises 0.1% of zinc borate, 3% of 50# industrial white oil and the balance of PS model A1; the composite particle skin layer includes 55% of linear low density polyethylene PE type B1 and 45% of compatibilizer SBR.

The preparation was carried out in the same manner as in example 1, except that the foaming temperature T was 165 ℃ and the foaming pressure was 3.6 MPa.

The EPO beads obtained by the above method have a bulk density of 60g/L, a large number of pinholes, pits and other defects on the surface, and a good degree of adhesion between particles of a molded article.

Example 6:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight proportion of the composite particle skin layer is 10%, and the weight proportion of the core layer is 90%; the composite particle core layer comprises 0.1% of zinc borate, 3% of 50# industrial white oil, 20% of toughening agent SBS and the balance of PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE type B2 and 45% compatibilizer SEBS.

The preparation was carried out in the same manner as in example 1, except that the foaming temperature T was 165 ℃ and the foaming pressure was 3.5 MPa.

The EPO beads obtained by the above method have a bulk density of 64g/L, and have a small number of pinholes, pits, and other defects on the surface, and the degree of adhesion between particles of a molded article is good.

Example 7:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight proportion of the composite particle skin layer is 10%, and the weight proportion of the core layer is 90%; the composite particle core layer comprises 0.1% of zinc borate, 3% of 50# industrial white oil, 20% of toughening agent SBS and the balance of PS model A2; the composite particle skin layer included 55% linear low density polyethylene PE type B2 and 45% compatibilizer SEBS.

The preparation is identical to example 1, with the difference that the foaming temperature T is 158 ℃ and the foaming pressure is 3.8 MPa.

The EPO beads prepared by the above method have a bulk density of 55g/L, a small number of pinholes, pits and other defects on the surface, and a good degree of adhesion between particles of a molded product.

Example 8:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight percentage of the composite particle skin layer is 20%, and the weight percentage of the core layer is 80%; the composite particle core layer comprises 0.1% of fluoride, 3% of 50# industrial white oil, 20% of toughening agent SBS and the balance of PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE type B1 and 45% compatibilizer SEBS.

The preparation is identical to example 1, except that the foaming temperature T is 166 ℃ and the foaming pressure is 3.5 MPa.

The EPO beads obtained by the above method have a bulk density of 58g/L, and have a small number of pinholes, pits, and other defects on the surface, and the degree of adhesion between particles of the molded article is very excellent.

Example 9:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight percentage of the composite particle skin layer is 20%, and the weight percentage of the core layer is 80%; the composite particle core layer comprises 0.1% of zinc borate, 3% of 50# industrial white oil, 20% of toughening agent SBS and the balance of PS model A2; the composite particle skin layer includes 55% of linear low density polyethylene PE type B2 and 45% of compatibilizer SBR.

The preparation is identical to example 1, except that the foaming temperature T is 155 ℃ and the foaming pressure is 3.8 MPa.

The EPO beads obtained by the above method have a bulk density of 60g/L, few surface defects, and excellent adhesion between particles of molded articles.

Example 10:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight percentage of the composite particle skin layer is 20%, and the weight percentage of the core layer is 80%; the composite particle core layer comprises 0.1% of zinc borate, 3% of 50# industrial white oil and the balance of PS model A2; the composite particle skin layer included 55% linear low density polyethylene PE type B2 and 45% compatibilizer SEBS.

The preparation is identical to example 1, except that the foaming temperature T is 157 ℃ and the foaming pressure is 3.9 MPa.

The EPO beads obtained by the above method have a bulk density of 59g/L, a small number of pinholes, pits and other defects on the surface, and the degree of adhesion between particles of the molded article is very excellent.

Example 11:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight proportion of the composite particle skin layer is 10%, and the weight proportion of the core layer is 90%; the composite particle core layer comprises 0.01% of zinc borate, 3% of 50# industrial white oil, 20% of toughening agent SBS and the balance of PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE type B1 and 45% compatibilizer SEBS.

The preparation is identical to example 1, except that the foaming temperature T is 170 ℃ and the foaming pressure is 5 MPa.

The EPO beads obtained by the above method have a bulk density of 65g/L, a large number of pinholes, pits and other defects on the surface, and poor adhesion between particles of a molded article.

Example 12:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight percentage of the composite particle skin layer is 3%, and the weight percentage of the core layer is 97%; the composite particle core layer comprises 0.1% of zinc borate, 3% of 50# industrial white oil, 20% of toughening agent SBS and the balance of PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE type B1 and 45% compatibilizer SEBS.

The preparation process is identical to that of example 1, except that the foaming temperature T is 168 ℃ and the foaming pressure is 3.7 MPa.

The EPO beads obtained by the above method have a bulk density of 59g/L, a large number of pinholes, pits and other defects on the surface, and poor adhesion between particles of the molded article.

Example 13:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight proportion of the composite particle skin layer is 10%, and the weight proportion of the core layer is 90%; the composite particle core layer comprises 0.1% of zinc borate, 20% of 50# industrial white oil, 20% of a toughening agent SBS and the balance of PS model A1; the composite particle skin layer includes 55% of linear low density polyethylene PE type B1 and 45% of compatibilizer SBR.

The preparation was carried out in the same manner as in example 1, except that the foaming temperature T was 165 ℃ and the foaming pressure was 4 MPa.

The EPO beads obtained by the above method had a bulk density of 54g/L, had many defects such as pinholes and pits on the surface, and the degree of adhesion between particles of the molded article was very poor.

Example 14:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight proportion of the composite particle skin layer is 10%, and the weight proportion of the core layer is 90%; the composite particle core layer comprises 0.1% of zinc borate, 3% of 50# industrial white oil, 20% of toughening agent SBS and the balance of PS model A1; the composite particle skin layer included 90% linear low density polyethylene PE type B1 and 10% compatibilizer SEBS.

The preparation is identical to example 1, except that the foaming temperature T is 160 ℃ and the foaming pressure is 5.5 MPa.

The EPO beads obtained by the above method have a bulk density of 60g/L, a large number of pinholes, pits and other defects on the surface, and poor adhesion between particles of a molded article.

Comparative example 1:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight percentage of the composite particle skin layer is 20%, and the weight percentage of the core layer is 80%; the composite particle core layer comprises 0.1% of stearate, 3% of 50# industrial white oil, 20% of a toughening agent SEBS and the balance PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE type B1 and 45% compatibilizer SEBS.

The preparation process is identical to that of example 1, except that the foaming temperature T is 168 ℃ and the foaming pressure is 5.5 MPa.

The EPO beads obtained by the above method have a bulk density of 70g/L, a large number of pinholes, pits and other defects on the surface, and poor adhesion between particles of a molded article.

Comparative example 2:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight percentage of the composite particle skin layer is 20%, and the weight percentage of the core layer is 80%; the composite particle core layer comprises 0.1% of stearate, 20% of toughening agent SEBS and the balance PS model A2; the composite particle skin layer includes 55% of linear low density polyethylene PE type B1 and 45% of compatibilizer SBR.

The preparation is identical to example 1, except that the foaming temperature T is 160 ℃ and the foaming pressure is 5.3 MPa.

The EPO beads obtained by the above method have a bulk density of 68g/L, a large number of pinholes, pits and other defects on the surface, and poor adhesion between particles of a molded article.

Comparative example 3:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight percentage of the composite particle skin layer is 20%, and the weight percentage of the core layer is 80%; the composite particle core layer comprises 0.1% of talc, 3% of 50# industrial white oil, 20% of a toughening agent SEBS and the balance of PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE type B1 and 45% compatibilizer SEBS.

The preparation process is identical to that of example 1, except that the foaming temperature T is 169 ℃ and the foaming pressure is 5 MPa.

The EPO beads obtained by the above method had a bulk density of 67g/L, had many defects such as pinholes and pits on the surface, and the degree of adhesion between particles of the molded article was very poor.

Comparative example 4:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight percentage of the composite particle skin layer is 20%, and the weight percentage of the core layer is 80%; the composite particle core layer comprises 0.1% of stearate, 3% of 120# industrial white oil, 20% of a toughening agent SEBS and the balance PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE type B1 and 45% compatibilizer SEBS.

The preparation is identical to example 1, except that the foaming temperature T is 170 ℃ and the foaming pressure is 5.5 MPa.

The EPO beads obtained by the above method had a bulk density of 73g/L, had many defects such as pinholes and pits on the surface, and had very poor adhesion between particles of the molded article.

Comparative example 5:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight percentage of the composite particle skin layer is 20%, and the weight percentage of the core layer is 80%; the composite particle core layer comprises 0.1% of stearate, 3% of 50# industrial white oil, 20% of a toughening agent SEPS and the balance of a PS model A1; the composite particle skin layer included 55% linear low density polyethylene PE type B1 and 45% compatibilizer SEBS.

The preparation process is identical to that of example 1, except that the foaming temperature T is 168 ℃ and the foaming pressure is 5.4 MPa.

The EPO beads obtained by the above method had a bulk density of 67g/L, had many defects such as pinholes and pits on the surface, and the degree of adhesion between particles of the molded article was very poor.

Comparative example 6:

an EPO (erythropoietin) expanded bead comprises a composite particle core layer and a composite particle skin layer, wherein the weight percentage of the composite particle skin layer is 20%, and the weight percentage of the core layer is 80%; the composite particle core layer comprises 0.1% of stearate, 3% of 50# industrial white oil, 20% of a toughening agent SEBS and the balance PS model A1; the composite particle skin layer includes 55% of linear low density polyethylene PE type B1 and 45% of compatibilizer SBR.

The preparation was carried out in the same manner as in example 1, except that the foaming temperature T was 167 ℃ and the foaming pressure was 5.4 MPa.

The EPO beads obtained by the above method have a bulk density of 69g/L, a large number of pinholes, pits and other defects on the surface, and poor adhesion between particles of the molded article.

EPO preparations were prepared from EPO beads prepared in examples 1-14 and comparative examples 1-6, respectively, by the following specific methods:

filling EPO particles into a mold cavity through a vacuum pipeline, expanding the particles and fusing the epidermis under the action of high-temperature steam, cooling and shaping through a flowing medium (generally water) on the surface of the mold to obtain an EPO molded part, and further curing and shaping in a hot air curing chamber at the temperature of 50-80 ℃ after the part is demoulded to obtain a usable EPO part product.

The raw material ratios and process parameters of the above examples 1 to 14 are as follows:

and the raw material ratios and the process parameters of comparative example 1 to comparative example 6 are as follows:

description of the drawings:

1. surface state:

v: the surface has more defects, such as needle holes or pits;

v: the surface has a small number of defects, such as pinholes or pits;

v √: the surface is basically free of defects;

2. adhesion degree:

v: the particle bonding proportion of the formed product is 20-40%;

v: the particle bonding proportion of the formed product is 40-70%;

v √: the particle bonding proportion of the formed product is 70-100%;

wherein the A1, A2, B1 and B2 performances are as follows:

from the above experimental results, the EPO expanded beads prepared according to the raw material ratios of examples 8 to 10 are most advantageous.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.