Cylindrical expandable polystyrene molds and their applications

Abstract

This invention discloses a cylindrical expandable polystyrene mold, comprising: a mold body, the mold body including a first mold body and a second mold body, the first mold body being sleeved on and fixedly disposed with the second mold body; the first mold body having a plurality of first through holes circumferentially spaced for bolts to pass through, thereby fixing the mold to an expandable polystyrene preparation device; the second mold having a circular hole in the center, and a plurality of second through holes circumferentially arranged near the circular hole, the second through holes being used to fix a conical guide to the mold; and a plurality of outlet molds located away from the circular hole. Expandable polystyrene is also produced by this mold. The cylindrical expandable polystyrene prepared using this mold exhibits strong bonding and excellent mechanical strength. Helmets made using this cylindrical expandable polystyrene also possess excellent mechanical strength.

Description

Technical Field

[0001] This invention relates to the field of chemical production equipment technology, and in particular to cylindrical expandable polystyrene molds and their applications. Background Technology

[0002] Expandable polystyrene (EPS) is a foam material prepared by physical foaming. It has advantages such as low thermal conductivity, good electrical insulation, low water absorption, excellent sound insulation performance, shock resistance, moisture resistance, and simple molding process. Therefore, it is widely used in sound insulation materials, shock-absorbing materials, and thermal insulation materials.

[0003] Patent document CN1662589A relates to the extrusion manufacturing of spherical expandable polystyrene. Polystyrene and the blowing agent pentane are melted in an extruder and conveyed as a melt through a perforated die at a temperature range of 140-300°C, preferably 160-240°C. The die is heated to at least the temperature of the polystyrene melt containing the blowing agent before extrusion and pelletizing. The die temperature is preferably 20-100°C higher than the temperature of the polystyrene melt containing the blowing agent. This prevents polymer deposition on the die and ensures that the pelletizing process is salt-free. To obtain a commercially viable pellet size, the die orifice diameter (D) at the die exit should be in the range of 0.2-1.5 mm. Besides molecular weight distribution, die swell is also affected by die geometry. Length (L) represents the die region whose diameter corresponds at most to the die exit diameter (D). The die preferably has orifices with an L / D ratio of at least 2. L / D is preferably in the range of 3-10.

[0004] Patent document CN102272223A also relates to extruded circular expandable polystyrene, but adds polyolefins with melting points in the range of 105 to 140°C, or block copolymers or graft copolymers with a minimum weight-average molecular weight (Mw) of 100,000 g / mol to the polystyrene to increase the toughness of the expandable polystyrene.

[0005] Patent document CN108864468B, which describes in detail the bonding force between particles of expandable polystyrene material when R2=R1 (i.e., cylindrical expandable polystyrene material), and its excellent mechanical strength, has been published. However, the production mold for cylindrical expandable polystyrene has not yet been disclosed. Summary of the Invention

[0006] The purpose of this invention is to provide a cylindrical expandable polystyrene mold and its application, thereby solving one or more of the problems in the prior art mentioned above.

[0007] In a first aspect, the cylindrical expandable polystyrene mold provided by the present invention includes:

[0008] The mold body includes a first mold body and a second mold body, wherein the first mold body is sleeved on the second mold body and is fixedly disposed with the second mold body;

[0009] The first mold body is provided with a plurality of first through holes circumferentially spaced, and the first through holes are used for bolts to pass through, and the mold is fixedly connected to the expandable polystyrene preparation device by bolts.

[0010] The second mold body has a circular hole in the middle, and a number of second through holes are arranged circumferentially near the circular hole. The second through holes are used to fix the conical guide to the mold. A number of outlet molds are arranged away from the circular hole.

[0011] In some embodiments, the ratio of the length L of the exit mold to the diameter D of the exit mold is 10-30.

[0012] In some embodiments, the ratio of the length L of the exit mold to the diameter D of the exit mold is 20-30.

[0013] In some implementations, the inlet angle of the outlet mold is less than 30°.

[0014] Secondly, the present invention provides a method for preparing expandable polystyrene, wherein the expandable polystyrene is obtained using the aforementioned mold, comprising the following steps:

[0015] S1. The mixture of polystyrene and pentane is melted through an extruder to obtain a melt;

[0016] S2. The melt is discharged through the exit mold of the mold, and the discharged material is cut into cylindrical shapes by a high-speed pelletizer;

[0017] S3. Solid-liquid separation is carried out by circulating water to obtain expandable polystyrene.

[0018] The mold includes:

[0019] The mold body includes a first mold body and a second mold body, wherein the first mold body is sleeved on the second mold body and is fixedly disposed with the second mold body;

[0020] The first mold body is provided with a plurality of first through holes circumferentially spaced, and the first through holes are used for bolts to pass through, and the mold is fixedly connected to the expandable polystyrene preparation device by bolts.

[0021] The second mold body has a circular hole in the middle, and a number of second through holes are arranged circumferentially near the circular hole. The second through holes are used to fix the conical guide to the mold. A number of outlet molds are arranged away from the circular hole.

[0022] In some implementations, the melt temperature in step S1 is 190-210°C.

[0023] In some implementations, the melt is cooled to 90-150°C when it reaches the exit mold in step S2.

[0024] In some implementations, the pressure is controlled at 10-25 MPa when the melt reaches the outlet mold in step S2.

[0025] In some implementations, in step S3, the temperature of the circulating water is controlled at 50-90°C and the water pressure at 0.5-0.9 bar.

[0026] In some implementations, in step S3, the temperature of the circulating water is controlled at 60-80°C and the water pressure is controlled at 0.5-0.9 bar.

[0027] In some implementations, the cylindrical product has an average length ranging from 2 to 3 mm, an average diameter of 0.5 to 0.7 mm, and an aspect ratio of 2.9 to 6.

[0028] In some implementations, the length-to-diameter ratio of the pre-expanded product is 0.8-3, preferably 0.9-1.5.

[0029] Thirdly, the application of expandable polystyrene provided by this invention in the manufacture of helmets. Cylindrical expandable polystyrene material is pre-expanded in a pre-expanding machine to a loose density of 60 g / L, then aged at room temperature for 5 hours, and finally pressed into expandable polystyrene sheets with a density of 70 g / L using a press, which can then be used to manufacture helmets.

[0030] Beneficial effects: This invention uses this mold to prepare cylindrical expandable polystyrene, a simple preparation method that is conducive to large-scale industrial production. Expandable polystyrene with a uniform structure is obtained by foaming the polystyrene. Furthermore, the resulting cylindrical expandable polystyrene exhibits strong bonding and excellent mechanical strength. Helmets made using this cylindrical expandable polystyrene also demonstrate excellent mechanical strength. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the cylindrical expandable polystyrene mold of the present invention;

[0032] Figure 2 It is along Figure 1 A sectional view taken at position B in the middle;

[0033] Figure 3 It is along Figure 1 A sectional view taken at position C in the middle;

[0034] Figure 4This is a schematic diagram of the structure of the export mold of the present invention;

[0035] Figure 5 yes Figure 4 Enlarged view of section I in the middle. Detailed Implementation

[0036] The present invention will be further described in detail below through embodiments.

[0037] Example 1

[0038] like Figure 1-3 As shown, a cylindrical expandable polystyrene mold includes: a mold body 1, a first mold body 11, a second mold body 12, a first through hole 111, a circular hole 121, a second through hole 122, and an outlet mold 123.

[0039] Specifically, the mold body 1 includes a first mold body 11 and a second mold body 12, wherein the first mold body 11 is sleeved on the second mold body 12 and is fixedly disposed with the second mold body 12;

[0040] The first mold body 11 has a plurality of first through holes 111 arranged circumferentially at equal intervals. The first through holes 111 are used for bolts to pass through, and the mold is fixedly connected to the expandable polystyrene preparation device by bolts.

[0041] The second mold body 12 has a circular hole 121 in the middle, and a number of second through holes 122 are provided around the circular hole 121. The second through holes 122 are used to fix the conical guide to the mold. A number of outlet molds 123 are provided away from the circular hole 121.

[0042] like Figure 4-5 The image shown is of the export mold;

[0043] Wherein: the ratio of the length L of the exit mold 123 to the diameter D of the exit mold 123 is 10-30, preferably 20-30.

[0044] The inlet angle of the exit mold 123 is less than 30°.

[0045] Example 2

[0046] The preparation method of expandable polystyrene includes the following steps:

[0047] S1. The mixture of polystyrene and pentane is melted through an extruder to obtain a melt, and the melt temperature is controlled at 190°C;

[0048] S2. When the melt reaches the exit mold, it is cooled to 90°C. Because the temperature is low, the pressure at the exit mold is high, which is 25 MPa. The melt is discharged through the exit mold of the mold in Example 1. The discharged material is cut into cylindrical shapes by a high-speed pelletizer.

[0049] S3. Solid-liquid separation is carried out by circulating water, with the water temperature controlled at 50°C and the water pressure at 0.9 bar, thereby obtaining the expandable polystyrene.

[0050] Among them, the average length of the produced cylindrical products is 2.2mm, the average diameter is 0.5mm, and the length-to-diameter ratio is 4.4; the average length-to-diameter ratio of the pre-formed products becomes 1.2.

[0051] Example 3

[0052] The preparation method of expandable polystyrene includes the following steps:

[0053] S1. The mixture of polystyrene and pentane is melted through an extruder to obtain a melt, and the melt temperature is controlled at 195°C;

[0054] S2. When the melt reaches the exit mold, it is cooled to 100°C. Because the temperature is low, the pressure at the exit mold is high, which is 22 MPa. The melt is discharged through the exit mold of the mold in Example 1. The discharged material is cut into cylindrical shapes by a high-speed pelletizer.

[0055] S3. Solid-liquid separation is carried out by circulating water, with the water temperature controlled at 60°C and the water pressure at 0.8 bar, thereby obtaining the expandable polystyrene.

[0056] Among them, the average length of the produced cylindrical products is 2.0 mm, the average diameter is 0.55 mm, and the length-to-diameter ratio is 3.6; the average length-to-diameter ratio of the pre-expanded products becomes 0.9 mm.

[0057] Example 4

[0058] The preparation method of expandable polystyrene includes the following steps:

[0059] S1. The mixture of polystyrene and pentane is melted through an extruder to obtain a melt, and the melt temperature is controlled at 200℃;

[0060] S2. When the melt reaches the exit mold, it is cooled to 110°C. Because the temperature is low, the pressure at the exit mold is high, which is 20 MPa. The melt is discharged through the exit mold of the mold in Example 1. The discharged material is cut into cylindrical shapes by a high-speed pelletizer.

[0061] S3. Solid-liquid separation is carried out by circulating water, with the water temperature controlled at 80°C and the water pressure at 0.7 bar, thereby obtaining the expandable polystyrene.

[0062] Among them, the average length of the produced cylindrical products is 2.5mm, the average diameter is 0.5mm, and the length-to-diameter ratio is 5; the average length-to-diameter ratio of the pre-formed products becomes 3.

[0063] Example 5

[0064] The preparation method of expandable polystyrene includes the following steps:

[0065] S1. The mixture of polystyrene and pentane is melted through an extruder to obtain a melt, and the melt temperature is controlled at 205℃;

[0066] S2. When the melt reaches the exit mold, it is cooled to 130°C. Because the temperature is low, the pressure at the exit mold is high, which is 15 MPa. The melt is discharged through the exit mold of the mold in Example 1. The discharged material is cut into cylindrical shapes by a high-speed pelletizer.

[0067] S3. Solid-liquid separation is carried out by circulating water, with the water temperature controlled at 70°C and the water pressure at 0.6 bar, thereby obtaining the expandable polystyrene.

[0068] Among them, the average length of the produced cylindrical products is 2mm, the average diameter is 0.65mm, and the length-to-diameter ratio is 3.1; the average length-to-diameter ratio of the pre-formed products becomes 0.9.

[0069] Example 6

[0070] The preparation method of expandable polystyrene includes the following steps:

[0071] S1. The mixture of polystyrene and pentane is melted through an extruder to obtain a melt, and the melt temperature is controlled at 210℃;

[0072] S2. When the melt reaches the exit mold, it is cooled to 150°C. Because the temperature is low, the pressure at the exit mold is high, which is 10 MPa. The melt is discharged through the exit mold of the mold in Example 1. The discharged material is cut into cylindrical shapes by a high-speed pelletizer.

[0073] S3. Solid-liquid separation is carried out by circulating water, with the water temperature controlled at 90°C and the water pressure at 0.5 bar, thereby obtaining the expandable polystyrene.

[0074] Among them, the average length of the produced cylindrical products is 3mm, the average diameter is 0.5mm, and the length-to-diameter ratio is 6; the average length-to-diameter ratio of the pre-formed products becomes 1.5.

[0075] Comparative Example 1

[0076] The preparation method is the same as in Example 2, except that the mold is changed to the mold in patent document CN1662589A to prepare spherical expandable polystyrene. The preparation method is as follows:

[0077] S1. The mixture of polystyrene and pentane is melted through an extruder to obtain a melt, and the melt temperature is controlled at 190°C;

[0078] S2. When the melt reaches the exit mold, it is cooled to 90°C. Because the temperature is low, the pressure at the exit mold is high, which is 25 MPa. The melt is discharged through the exit mold of the mold. The discharged material is cut into circles by a high-speed pelletizer with an average diameter of about 1.2 mm.

[0079] S3. Solid-liquid separation is carried out by circulating water, with the water temperature controlled at 50°C and the water pressure at 0.9 bar, thereby obtaining the expandable polystyrene.

[0080] Performance testing

[0081] The expandable polystyrene obtained in Examples 2-6 and the circular expandable polystyrene material obtained in Comparative Example 1 were pre-expanded in a pre-expanding machine to a loose density of 60 g / L. Then, they were aged at room temperature for 5 hours and then pressed into expandable polystyrene boards with a density of 70 g / L using a plate press. The boards were then cut into expandable polystyrene boards with a size of 300 × 300 × 30 mm for impact testing.

[0082] The impact test was conducted according to GB 24429-2009. The expandable polystyrene boards prepared in Examples 2-6 and Comparative Example 1 were fixed on a flat anvil, and a spherical object was allowed to fall freely from a height of 180 cm onto the expandable polystyrene board. The weight of the spherical object was 5.002 kg. The expandable polystyrene board had dimensions of 300 × 300 × 30 mm and a density of 70 g / L. The peak acceleration was measured, i.e., the peak acceleration when the spherical object's velocity decreased to zero upon free fall onto the expandable polystyrene board. The results are shown in Table 1.

[0083] Table 1

[0084]

[0085] As shown in Table 1, compared with Comparative Example 1, the expandable polystyrene boards made using the expandable polystyrene from Examples 2-6 of this application exhibit lower peak acceleration and superior impact performance. Theoretical studies have found that if the true density of a solid material is 1 g / cm³ (PS specific gravity is close to 1), its close-packed density is approximately 0.63 g / cm³ if it is spherical, approximately 0.81 g / cm³ if it is cylindrical, and approximately 0.63-0.81 g / cm³ for an ellipsoidal shape (between spherical and cylindrical). This means that cylindrical shapes have the smallest residual gaps. Therefore, in the helmet industry, cylindrical or ellipsoidal materials have a higher natural bulk density, resulting in denser helmets with higher impact strength and resistance. As is well known, a ball can roll in any direction on a plane, but a cylinder can only roll in two directions. In order to increase the natural packing density of the strip material in the mold cavity, its length / diameter ratio needs to be limited to a range of 0.8-3, preferably 0.9-1.5.

[0086] In summary, this invention utilizes this mold to prepare cylindrical expandable polystyrene, a simple preparation method that facilitates large-scale industrial production. Expandable polystyrene with a uniform structure is obtained through foaming. Furthermore, the resulting cylindrical expandable polystyrene exhibits strong bonding and excellent mechanical strength. Helmets made using this cylindrical expandable polystyrene also demonstrate excellent mechanical strength.

[0087] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these should also be considered within the scope of protection of the invention.

Claims

1. A method for preparing expandable polystyrene, wherein the expandable polystyrene is obtained using a cylindrical expandable polystyrene mold, characterized in that, Includes the following steps: S1. The mixture of polystyrene and pentane is melted through an extruder to obtain a melt; S2. The melt is discharged through the exit mold of the mold, and the discharged material is cut into cylindrical shapes by a high-speed pelletizer; S3. Solid-liquid separation is carried out by circulating water to obtain the expandable polystyrene; The mold includes: The mold body (1) includes a first mold body (11) and a second mold body (12), wherein the first mold body (11) is sleeved on the second mold body (12) and fixedly disposed with the second mold body (12); The first mold body (11) is provided with a plurality of first through holes (111) circumferentially spaced. The first through holes (111) are used for bolts to pass through, and the mold is fixedly connected to the expandable polystyrene preparation device by bolts. The second mold body (12) has a circular hole (121) in the middle, and a number of second through holes (122) are provided around the circular hole (121). The second through holes (122) are used to fix the conical guide to the mold. A number of outlet molds (123) are provided away from the circular hole (121). The ratio of the length L of the outlet mold (123) to the diameter D of the outlet mold (123) is 20-30; The inlet angle of the outlet mold (123) is less than 30°; The length-to-diameter ratio of the pre-released product is 0.8-3.

2. The method for preparing expandable polystyrene according to claim 1, characterized in that, The melt temperature in step S1 is 190-210℃.

3. The method for preparing expandable polystyrene according to claim 1, characterized in that, In step S2, the melt is cooled to 90-150°C when it reaches the exit mold.

4. The method for preparing expandable polystyrene according to claim 1, characterized in that, In step S2, the pressure is controlled at 10-25 MPa when the melt reaches the outlet mold.

5. The method for preparing expandable polystyrene according to claim 1, characterized in that, In step S3, the temperature of the circulating water is controlled at 50-90℃ and the water pressure is controlled at 0.5-0.9 bar.

6. The method for preparing expandable polystyrene according to claim 1, characterized in that, In step S3, the temperature of the circulating water is controlled at 60-80℃ and the water pressure is controlled at 0.5-0.9 bar.

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