阅读说明：本技术 用于聚乙烯醇材料熔融改性加工的双螺杆组合与加工工艺 (Double-screw combination and processing technology for melt modification processing of polyvinyl alcohol material ) 是由 钱玉英 冯晓涛 邱守季 于 2021-09-07 设计创作，主要内容包括：本发明涉及高分子材料加工技术领域,特别是涉及一种用于聚乙烯醇材料熔融改性加工的双螺杆组合与加工工艺。本发明根据聚乙烯醇材料的流变特点,限定了螺杆中各功能段的长度占比以及所采用的螺纹元件的型号,使双螺杆组合与聚乙烯醇材料充分匹配,改善了聚乙烯醇材料的熔融混合,有效提升了聚乙烯醇改性加工过程中的塑化效果,使得改性后的聚乙烯醇材料具备更好的力学性能。与传统的更改聚乙烯醇材料的配方的研发思路相比,提供了一种更新颖、普适、环保的解决手段,对PVA材料的双螺杆熔融塑化改性技术的提高和深入开发具有积极的作用。(The invention relates to the technical field of processing of high polymer materials, in particular to a double-screw combination and processing technology for melt modification processing of a polyvinyl alcohol material. According to the rheological characteristics of the polyvinyl alcohol material, the length ratio of each functional section in the screw and the type of the adopted thread element are limited, so that the double-screw combination is fully matched with the polyvinyl alcohol material, the melt mixing of the polyvinyl alcohol material is improved, the plasticizing effect in the polyvinyl alcohol modification processing process is effectively improved, and the modified polyvinyl alcohol material has better mechanical property. Compared with the traditional research and development idea of changing the formula of the polyvinyl alcohol material, the method provides a more novel, universal and environment-friendly solution, and has a positive effect on the improvement and deep development of the double-screw melting plasticizing modification technology of the PVA material.)

1. A twin-screw combination for melt modification processing of polyvinyl alcohol materials, comprising two intermeshing parallel co-rotating screws, wherein the screws comprise the following functional sections in percentage of the total length of the screws:

wherein, the model of the screw element that the reinforced section adopted includes: 24/24, respectively;

the types of the screw elements adopted by the conveying section comprise: 24/24 and/or 20/20;

the types of the thread elements adopted by the conveying compression section comprise: 16/16 and/or 12/12;

the types of the thread elements adopted by the mixing section comprise: one or more of 30 °/7/24, 45 °/5/16, 45 °/5/24, 45 °/5/24L, 60 °/4/16, 60 °/4/24, 90 °/5/16, 90 °/5/24;

the types of the thread elements adopted by the reverse pressure building section comprise: 12/6L, 12/12, 16/16, 45 °/5/24L;

the types of the thread elements adopted by the vacuum conveying section comprise: 24/24 and/or 20/20;

the type of the thread element adopted by the metering pressure build-up section comprises: 16/16 and/or 12/12.

2. The twin screw combination of claim 1, wherein the conveying section comprises at least two conveying subsections, the conveying compression section comprises at least two conveying compression subsections, and the mixing section comprises at least two mixing subsections; the screw comprises at least two subsection combinations, wherein the subsection combinations comprise at least two of the conveying subsection, the conveying compression subsection and the mixing subsection.

3. The twin screw combination of claim 2, wherein the conveying section comprises 2-7 conveying subsections, the conveying compression section comprises 2-6 conveying compression subsections, and the mixing section comprises 2-6 mixing subsections; the screw comprises 2-6 subsegment combinations, wherein each subsegment combination comprises the conveying subsegment, the conveying compression subsegment and the mixing subsegment.

4. The twin screw combination of claim 3, wherein the sub-section combination is formed by arranging the conveying sub-section, the conveying compression sub-section and the mixing sub-section in sequence.

5. The twin screw combination of claim 2, wherein the conveying sub-section comprises 1-5 respective thread elements, the conveying compression sub-section comprises 1-7 respective thread elements, and the mixing sub-section comprises 1-3 respective thread elements.

6. The twin screw combination of any one of claims 1 to 5, wherein the mixing section comprises 8% to 15% of melt mixing section and 8% to 18% of dispersive mixing section, respectively, based on the total length of the screws, wherein the melt mixing section employs screw elements of the type comprising: one or more of 30 °/7/24, 45 °/5/24, 60 °/4/24, 90 °/5/24, the dispersive mixing section employing thread elements of types including: one or more of 45 °/5/16, 45 °/5/24, 45 °/5/24L, 60 °/4/16, 60 °/4/24, 90 °/5/24.

7. A polyvinyl alcohol material melt modification processing technology is characterized by comprising the following steps:

premixing polyvinyl alcohol materials, then putting the polyvinyl alcohol materials into a feeding hopper of a double-screw extruder, and processing the polyvinyl alcohol materials by adopting the double-screw combination as claimed in any one of claims 1 to 6.

8. The process according to claim 7, wherein the polyvinyl alcohol material comprises the following components in parts by mass:

9. the process according to claim 8, wherein the plasticizer comprises the following components in parts by mass:

5-15 parts of mannitol;

1-5 parts of sorbitol; and

1-5 parts of maltitol.

10. The processing technology as claimed in any one of claims 7 to 9, wherein the working temperature of each functional section in the twin-screw combination is as follows:

11. the process of claim 10, wherein the mixing section comprises a melt-mixing section and a dispersive mixing section, the melt-mixing section operating at a temperature of 115 ℃ to 175 ℃ and the dispersive mixing section operating at a temperature of 125 ℃ to 190 ℃.

12. The process of any one of claims 7 to 9, wherein the twin screw assembly has an operating speed of from 80RPM to 300 RPM.

Technical Field

The invention relates to the technical field of processing of high polymer materials, in particular to a double-screw combination and processing technology for melt modification processing of a polyvinyl alcohol material.

Background

Polyvinyl alcohol (PVA) is a water-soluble biodegradable material having good oil resistance, wear resistance and gas barrier properties, and is widely used in the fields of medical treatment, food, washing, toxic packaging, transportation and the like because it is environmentally friendly and has various properties after being modified. PVA has regular molecular structure and high crystallinity, and a large amount of hydroxyl groups on a molecular chain can form strong hydrogen bonds, so that strong intramolecular acting force is provided, the melting processing temperature and the decomposition temperature of PVA are very close, and the PVA is difficult to be directly subjected to thermoplastic processing. Aiming at the problem, PVA modification processing methods such as copolymerization modification, compound blending modification, post-reaction modification, plasticization modification and the like are developed at present; among them, the plasticizing modification method by adding small molecular substances and oligomers is most directly effective for realizing PVA melt processing.

The double-screw extrusion plasticizing melting modification has the advantages of small equipment investment, high production efficiency, low energy consumption, short process flow, low maintenance cost and the like, can greatly expand the production and use of PVA, and is a hotspot of current research. The double-screw melt extrusion needs to directly complete the plasticizing mixing processing of the PVA resin and the modification auxiliary agent component in one step, and besides a proper modification formula, the configuration combination and the extrusion process of the double screws have a vital influence on the melt plasticizing modification of the PVA. However, the current research mainly focuses on improving the plasticization of PVA by formulation modification, and the research on the combination of twin screws and extrusion process is very little, so that a complex formulation is often required to realize the melt modification of PVA with high quality, and moreover, the introduction of too many additives inevitably affects the performance of PVA itself and is not environment-friendly.

Disclosure of Invention

Based on the above, there is a need for a twin-screw combination and processing technology for melt modification processing of a polyvinyl alcohol material, which is designed according to the rheological characteristics of a PVA material, has a good matching degree with PVA, and can greatly improve the quality of a melt-modified PVA product by using a simple modification formula.

In one aspect of the invention, a twin-screw assembly for melt modification processing of polyvinyl alcohol material is provided, which comprises two meshed parallel co-directional screws, wherein the screws comprise the following functional sections in percentage by total length of the screws:

wherein, the model of the screw element that the reinforced section adopted includes: 24/24, respectively;

the types of the screw elements adopted by the conveying section comprise: 24/24 and/or 20/20;

the types of the thread elements adopted by the conveying compression section comprise: 16/16 and/or 12/12;

the types of the thread elements adopted by the mixing section comprise: one or more of 30 °/7/24, 45 °/5/16, 45 °/5/24, 45 °/5/24L, 60 °/4/16, 60 °/4/24, 90 °/5/16, 90 °/5/24;

the types of the thread elements adopted by the reverse pressure building section comprise: 12/6L, 12/12, 16/16, 45 °/5/24L;

the types of the thread elements adopted by the vacuum conveying section comprise: 24/24 and/or 20/20;

the type of the thread element adopted by the metering pressure build-up section comprises: 16/16 and/or 12/12.

According to the rheological characteristics of the polyvinyl alcohol material, the length ratio of each functional section in the screw and the type of the adopted thread element are limited, so that the double-screw combination is fully matched with the polyvinyl alcohol material, the melt mixing of the polyvinyl alcohol material is improved, the plasticizing effect in the polyvinyl alcohol modification processing process is effectively improved, and the modified polyvinyl alcohol material has better mechanical property. Compared with the traditional research and development idea of changing the formula of the polyvinyl alcohol material, the method provides a more novel, universal and environment-friendly solution, and has a positive effect on the improvement and deep development of the double-screw melting plasticizing modification technology of the PVA material.

In some embodiments, the transport section comprises at least two transport subsections, the transport compression section comprises at least two transport compression subsections, and the mixing section comprises at least two mixing subsections; the screw comprises at least two subsection combinations, wherein the subsection combinations comprise at least two of the conveying subsection, the conveying compression subsection and the mixing subsection.

In some embodiments, the conveying section comprises 2-7 conveying subsections, the conveying compression section comprises 2-6 conveying compression subsections, and the mixing section comprises 2-6 mixing subsections; the screw comprises 2-6 subsegment combinations, wherein each subsegment combination comprises the conveying subsegment, the conveying compression subsegment and the mixing subsegment.

In some embodiments, the sub-section combination is formed by arranging the conveying sub-section, the conveying compressed sub-section and the mixing sub-section in sequence.

In some embodiments, the transport subsections include 1-5 corresponding thread elements, the transport compression subsections include 1-7 corresponding thread elements, and the mixing subsections include 1-3 corresponding thread elements.

In some embodiments, the mixing section comprises 8% to 15% of a melt mixing section and 8% to 18% of a dispersive mixing section, respectively, by total length of the screw, wherein the melt mixing section employs a type of flight element comprising: one or more of 30 °/7/24, 45 °/5/24, 60 °/4/24, 90 °/5/24, the dispersive mixing section employing thread elements of types including: one or more of 45 °/5/16, 45 °/5/24, 45 °/5/24L, 60 °/4/16, 60 °/4/24, 90 °/5/24.

In another aspect of the present invention, a melt modification processing technology for a polyvinyl alcohol material is provided, which comprises the following steps:

the polyvinyl alcohol material is premixed and then put into a charging hopper of a double-screw extruder, and the double-screw extruder is adopted for processing.

In some embodiments, the polyvinyl alcohol material comprises the following components in parts by mass:

in some embodiments, the plasticizer comprises the following components in parts by mass:

5-15 parts of mannitol;

1-5 parts of sorbitol; and

1-5 parts of maltitol.

In some embodiments, the operating temperature of each functional section in the twin-screw combination is:

in some embodiments, the mixing section comprises a melt mixing section having an operating temperature of 115 ℃ to 175 ℃ and a dispersive mixing section having an operating temperature of 125 ℃ to 190 ℃.

In some embodiments, the twin screw combination has an operating speed of 80 to 300 RPM.

Drawings

FIG. 1 is a schematic view showing the arrangement of a screw assembly according to example 1;

FIG. 2 is a schematic view showing the arrangement of the screw assembly of comparative example 1;

FIG. 3 is a graph showing the effect of extrusion in example 1;

FIG. 4 is a graph showing the effect of extrusion in comparative example 1;

FIG. 5 is a graph showing the effect of extrusion in comparative example 2;

fig. 6 is a graph showing the effect of extrusion in comparative example 3.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise. In the description of the present invention, "a plurality" means at least one, e.g., one, two, etc., unless specifically limited otherwise.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In one aspect of the invention, a twin-screw combination for melt modification processing of polyvinyl alcohol materials is provided, which comprises two meshed parallel co-directional screws, wherein the screws comprise the following functional sections in percentage by total length of the screws:

wherein, the model of the screw element that the reinforced section adopted includes: 24/24, respectively;

the types of the screw elements adopted by the conveying section comprise: 24/24 and/or 20/20;

the types of the screw elements adopted by the conveying compression section comprise: 16/16 and/or 12/12;

the types of threaded elements employed in the mixing section include: one or more of 30 °/7/24, 45 °/5/16, 45 °/5/24, 45 °/5/24L, 60 °/4/16, 60 °/4/24, 90 °/5/16, 90 °/5/24;

the types of the thread elements adopted by the reverse pressure building section comprise: 12/6L, 12/12, 16/16, 45 °/5/24L;

the types of the screw elements adopted by the vacuum conveying section comprise: 24/24 and/or 20/20;

the types of the thread elements adopted by the metering pressure build-up section comprise: 16/16 and/or 12/12.

According to the rheological characteristics of the polyvinyl alcohol material, the length ratio of each functional section in the screw and the type of the adopted thread element are limited, so that the double-screw combination is fully matched with the polyvinyl alcohol material, the melt mixing of the polyvinyl alcohol material is improved, the plasticizing effect in the polyvinyl alcohol modification processing process is effectively improved, and the modified polyvinyl alcohol material has better mechanical property. Compared with the traditional research and development idea of changing the formula of the polyvinyl alcohol material, the method provides a more novel, universal and environment-friendly solution, and has a positive effect on the improvement and deep development of the double-screw melting plasticizing modification technology of the PVA material.

Preferably, the screw comprises the following functional sections, in percentages of the total length of the screw:

wherein, the model of the screw element that the reinforced section adopted includes: 24/24, respectively;

the types of the screw elements adopted by the conveying section comprise: 24/24 and 20/20;

the types of the screw elements adopted by the conveying compression section comprise: 16/16 and 12/12;

the types of threaded elements employed in the mixing section include: 30 °/7/24, 45 °/5/24, 45 °/5/24L, and 60 °/4/24;

the types of the thread elements adopted by the reverse pressure building section comprise: 12/6L, 12/12, 16/16, 45 °/5/24L;

the types of the screw elements adopted by the vacuum conveying section comprise: 24/24 and 20/20;

the types of the thread elements adopted by the metering pressure build-up section comprise: 16/16, and 12/12.

In some embodiments, the transport section comprises at least two transport subsections, the transport compression section comprises at least two transport compression subsections, and the mixing section comprises at least two mixing subsections; the screw comprises at least two subsection combinations, wherein the subsection combinations comprise at least two of a conveying subsection, a conveying compression subsection and a mixing subsection. Each functional section is divided into a plurality of functional subsections, and then the functional subsections are combined into a plurality of subsections, so that the screw has better melting plasticizing effect on polyvinyl alcohol under the same length than a screw formed by combining the functional sections which are not decomposed into the functional subsections and are continuously arranged.

In some embodiments, the conveying section comprises 2-7 conveying subsections, the conveying compression section comprises 2-6 conveying compression subsections, and the mixing section comprises 2-6 mixing subsections; the screw comprises 2-6 subsegment combinations, wherein each subsegment combination comprises a conveying subsection, a conveying compression subsection and a mixing subsection. Preferably, the conveying section comprises 5-6 conveying subsections, the conveying compression section comprises 4-5 conveying compression subsections, and the mixing section comprises 4-5 mixing subsections. The number of the subsections of each functional section is limited, so that the screw has excellent melting plasticizing capacity in a certain length range.

In some embodiments, the sub-section combination is formed by arranging a conveying sub-section, a conveying compression sub-section and a mixing sub-section in sequence. The arrangement mode of the subsection combination also has direct influence on the melting plasticizing effect of the screw, and the modified polyvinyl alcohol assignment with better performance can be obtained by arranging the subsection combination according to a preset mode.

In some embodiments, the transport subsections include 1-5 corresponding thread elements, the transport compression subsections include 1-7 corresponding thread elements, and the mixing subsections include 1-3 corresponding thread elements.

In some embodiments, the feed section comprises 3 to 5 corresponding threaded elements, the reverse pressure buildup section comprises 1 to 2 corresponding threaded elements, and the metering pressure buildup section comprises 7 to 9 corresponding threaded elements.

In some embodiments, the mixing section comprises 8% to 15% of melt mixing section and 8% to 18% of dispersive mixing section, respectively, by total length of the screw, wherein the melt mixing section employs a type of thread element comprising: one or more of 30 °/7/24, 45 °/5/24, 60 °/4/24, 90 °/5/24, the dispersive mixing section employing types of thread elements including: one or more of 45 °/5/16, 45 °/5/24, 45 °/5/24L, 60 °/4/16, 60 °/4/24, 90 °/5/24.

Preferably, in some embodiments, the screw comprises, in order: the device comprises a feeding section, a first conveying subsection, a first conveying compression subsection, a first mixing subsection, a second conveying compression subsection, a second mixing subsection, a third conveying compression subsection, a third mixing subsection, a fourth conveying compression subsection, a fourth mixing subsection, a fifth conveying compression subsection, a fifth mixing subsection, a reverse pressure building section, a sixth conveying subsection, a vacuum conveying section and a metering pressure building section.

Preferably, in some embodiments, the feed section comprises 3 respective screw elements, the first delivery subsection comprises 5 respective screw elements, the first delivery compression subsection comprises 7 respective screw elements, the first mixing subsection comprises 2 respective screw elements, the second delivery subsection comprises 3 respective screw elements, the second delivery compression subsection comprises 2 respective screw elements, the second mixing subsection comprises 2 respective screw elements, the third delivery compression subsection comprises 1 respective screw element, the third mixing subsection comprises 2 respective screw elements, the fourth delivery compression subsection comprises 3 respective screw elements, the fourth mixing subsection comprises 2 respective screw elements, the fifth delivery subsection comprises 1 respective screw element, the fifth delivery compression subsection comprises 3 corresponding thread elements, the fifth mixing subsection comprises 1 corresponding thread element, the reverse pressure buildup section comprises 1 corresponding thread element, the sixth delivery subsection comprises 1 corresponding thread element, the vacuum delivery section comprises 3 corresponding thread elements, and the metering pressure buildup section comprises 8 corresponding thread elements.

In some embodiments, the double-screw combination provided by the invention is applied to a double-screw extruder with the length-diameter ratio of (36-52): 1, and is preferably particularly suitable for a double-screw extruder with the length-diameter ratio of 44: 1.

In another aspect of the present invention, a melt modification processing technology for a polyvinyl alcohol material is provided, which comprises the following steps:

the polyvinyl alcohol material is premixed and then put into a charging hopper of a double-screw extruder, and the double-screw extruder is adopted for processing.

In some embodiments, the polyvinyl alcohol material comprises the following components in parts by mass:

in some embodiments, the plasticizer comprises the following components in parts by mass:

5-15 parts of mannitol;

1-5 parts of sorbitol; and

1-5 parts of maltitol.

In some embodiments, preferably, the polyvinyl alcohol material comprises the following components in parts by mass:

in some embodiments, the operating temperature of each functional section in the twin-screw combination is:

in some embodiments, the mixing section comprises a melt-mixing section and a dispersive mixing section, the operating temperature of the melt-mixing section is 115 ℃ to 175 ℃, and the operating temperature of the dispersive mixing section is 125 ℃ to 190 ℃.

Preferably, in some embodiments, the temperature of the feeding section is 90 ℃ to 120 ℃, the temperature of the first delivery sub-section is 120 ℃ to 140 ℃, the temperature of the first delivery compression sub-section is 130 ℃ to 150 ℃, the temperature of the first mixing sub-section is 120 ℃ to 160 ℃, the temperature of the second delivery compression sub-section is 130 ℃ to 170 ℃, the temperature of the second mixing sub-section is 135 ℃ to 170 ℃, the temperature of the third delivery sub-section is 140 ℃ to 180 ℃, the temperature of the third delivery compression sub-section is 140 ℃ to 180 ℃, the temperature of the third mixing sub-section is 140 ℃ to 180 ℃, the temperature of the fourth delivery compression sub-section is 145 ℃ to 180 ℃, the temperature of the fourth mixing sub-section is 150 ℃ to 180 ℃, the temperature of the fifth delivery compression sub-section is 185 ℃ to 180 ℃, the temperature of the fifth mixing subsection is 150-185 ℃, the temperature of the reverse pressure building section is 150-190 ℃, the temperature of the sixth conveying subsection is 155-195 ℃, the temperature of the vacuum conveying section is 155-195 ℃, and the temperature of the metering pressure building section is 155-200 ℃.

In some embodiments, the twin screw combination operates at a speed of between 80RPM and 300 RPM. Preferably, the operating speed of the twin screw assembly is between 100RPM and 200 RPM.

The present invention will be described in further detail with reference to specific examples and comparative examples. It is understood that the following examples are more specific in terms of apparatus and materials, and in other specific examples, the invention is not limited thereto, and may be, for example, not limited to stearic acid as a lubricant, nor aluminum hydroxide as a stabilizer.

Preparation of polyvinyl alcohol material:

80 parts of polyvinyl alcohol resin, 10 parts of mannitol, 4 parts of sorbitol, 3 parts of maltitol, 0.6 part of stearic acid, 0.4 part of aluminum hydroxide were added to a high-speed premixer and mixed at 1300RPM for 10 min.

The specific extrusion process comprises the following steps:

adding the prepared polyvinyl alcohol material into a feeding hopper of a double-screw extruder with the length-diameter ratio of 44:1, then carrying out modification processing according to the double-screw combination, the working temperature and the rotating speed adopted in each embodiment and comparative example, and after extruding strips, carrying out air cooling, granulating, sealing and storing.

Example 1:

total length: 1002mm, the total ratio of each functional section is as follows:

the specific screw distribution is arranged in the order of appearance of the screw elements in the table (see also fig. 1):

example 1 the rotational speed was set to 200RPM to 300 RPM.

Example 2

Example 2 substantially corresponds to example 1 with the difference that each sub-section in each fifth sub-section combination is merged into a corresponding fourth sub-section, i.e. example 2 has a total of four sub-section combinations, the first three sub-section combinations correspond to example 1, and the fourth sub-section combination becomes: the fourth delivery subsection: 24/24, 24/24, 20/20; fourth transport compression subsection: 16/16, 16/16, 16/16, 12/12, 12/12, 12/12; fourth mixing subsection (dispersive mixing): 45 °/5/24, 45 °/5/24L, 45 °/5/24L.

Example 3:

total length: 1002mm, the total ratio of each functional section is as follows:

the specific screw distribution is arranged in the order of appearance of the screw elements in the table:

example 3 the rotational speed was set to 100RPM to 200 RPM.

Example 4

Total length: 1002mm, the total ratio of each functional section is as follows:

example 4 the rotational speed was set to 80RPM to 130 RPM.

Comparative example 1

Total length: 1002mm, the total ratio of each functional section is as follows:

the specific screw distribution is arranged in the order of appearance of the screw elements in the table (see also fig. 2):

the rotation speed of comparative example 1 was set to 80RPM to 130 RPM.

Comparative example 2

Total length: 1002mm, the total ratio of each functional section is as follows:

the specific screw distribution is arranged in the order of appearance of the screw elements in the table:

comparative example 2 was set to a rotation speed of 200RPM to 300 RPM.

Comparative example 3

Total length: 1002mm, the total ratio of each functional section is as follows:

the specific screw distribution is arranged in the order of appearance of the screw elements in the table:

comparative example 3 the rotation speed was set to 100RPM to 200 RPM.

Characterization and performance testing:

(1) PVA extrusion blending effect:

TABLE 1

Residence time: and starting timing when the feeding of the double-screw feed opening is started, and ending timing when the neck ring mold starts to extrude the sample strips.

(2) PVA injection molding sample strip test effect:

tensile strength test standard: GB/T1040.2

Elongation at break test standard: GB/T1040.2

TABLE 2

As is clear from tables 1 and 2, the extruded specimens of the examples of the present invention are smooth and free from bubbles and have good tensile strength and elongation at break, and particularly, example 1, in which the ratio of each functional segment is in the preferred range, has a tensile strength of 55MPa or more and an elongation at break of 160% or more. In comparative example 1, the ratio of the conveying section to the mixing section is not within the preset range, so that the extruded surface of a sample strip is rough, the bamboo joint lines are serious, the sample strip is yellow, and foaming is serious, so that the tensile strength and the elongation at break are greatly reduced; in comparative example 2, the ratio of the conveying compression section to the mixing section is not within the preset range, so that the sample strip outlet die is layered and is light yellow, the plasticizing effect is poor, the melt strength is not high, the strip cannot be drawn, and the sample cannot be prepared; in comparative example 3, the ratio of the conveying stage and the conveying compression stage is not within the predetermined range, and although the color of the sample bar is not significantly changed as in comparative examples 1 and 2, there is a problem that the latter stage is seriously foamed, and therefore the tensile strength and the elongation at break are also poor, and the actual production requirements cannot be satisfied.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims, and the description and the drawings can be used for explaining the contents of the claims.