Polypropylene infrared tabletting mold assembly and manufacturing method thereof

Abstract

The invention provides a polypropylene infrared tabletting mold assembly and a manufacturing method thereof. The mold assembly comprises a first pressing plate, a second pressing plate, a third pressing plate and a fourth pressing plate, at least one film cavity is formed in the second pressing plate, and the distance between the inner walls of the film cavities is larger than the set distance; the surface, far away from the second pressing plate, of the third pressing plate comprises at least one placing area for polypropylene copolymer granules or powder, and each placing area is opposite to the position of one abdominal cavity; and a fourth pressing plate. According to the scheme, the problems that in the prior art, infrared sample wafers of random co-polypropylene and anti-impact co-polypropylene are stuck to a mold, the mold is prone to damage and deformation, the service life is short, and the prepared sample wafers are uneven in thickness are solved.

Description

Technical Field

[0001] The present application relates to the technical field of polyolefin detection, and in particular to a polypropylene infrared tabletting mold assembly and a manufacturing method thereof. Background Art

[0002] Random copolymer polypropylene is modified by adding ethylene monomer. Compared with polypropylene homopolymer, random copolymer has improved optical properties, improved impact resistance, increased flexibility, lower melting temperature, and thus lower melting point. It is used in blow molding, injection molding, extrusion, film and sheet extrusion processing, mainly used in water pipes, food packaging materials, pharmaceutical packaging materials and daily consumer goods. Impact copolymer polypropylene is a product produced by adding ethylene during the production process and copolymerizing ethylene and propylene. Its impact resistance is greatly improved, achieving a balance between rigidity and toughness. It is often used to manufacture car bumpers, baby carriages, sports equipment, luggage, paint buckets and other items.

[0003] In the process of producing random copolymer polypropylene and impact copolymer polypropylene, the amount of ethylene added is an important control indicator in the production process. The ethylene content test process usually requires compression molding to prepare test samples and then infrared spectroscopy detection. The quality of the test sample preparation has a great influence on the test results of the ethylene content in the sample. Therefore, the development of a polypropylene infrared tableting mold is of great significance to this test method. The existing testing technology requires the purchase of a mold with a suitable thickness size first. The mold is a quadrilateral frame. The polypropylene copolymer pellets or powder are placed in the quadrilateral frame. The upper and lower parts of the quadrilateral frame are padded with aluminum foil and then placed in a tablet press for heating and pressurization. After decompression and cooling, an infrared sample of the required thickness is obtained. In this way, the overflow will stick to the surrounding of the four frames and is not easy to remove, resulting in defects such as difficulty in demolding the tablet formed by the tableting, long demolding time, short mold service life, and uneven sample thickness. Summary of the invention

[0004] The technical problem to be solved by the present application is that when preparing random copolymer polypropylene and impact copolymer polypropylene samples, the pressed samples are not easy to demould, the demoulding time is long, the mold service life is short, the sample thickness is uneven, and the like.

[0005] In a first aspect, the technical solution of the present application provides a polypropylene infrared sheeting mold assembly, comprising:

[0006] First pressing plate;

[0007] A second pressing plate, on which at least one membrane cavity is formed, and the inner wall spacing of the membrane cavity is greater than the set distance;

[0008] A third pressing plate, comprising at least one placement area for polypropylene copolymer pellets or powder on a surface away from the second pressing plate, each of the placement areas being opposite to a position of the abdominal cavity;

[0009] Fourth pressure plate.

[0010] In some embodiments of the polypropylene infrared sheet pressing mold assembly, the number of the film cavities on the second pressing plate is 1 to 4, and the film cavities are circular cavities.

[0011] In some schemes, the polypropylene infrared sheet pressing mold assembly described in the circular cavity has an inner diameter as the inner wall spacing, and the inner diameter is (50±a) mm, where a is the allowable error value.

[0012] In some embodiments of the polypropylene infrared sheeting mold assembly, the thickness of the second pressing plate is 0.25 mm or 0.5 mm;

[0013] The thickness of the third pressing plate is in the range of 0.05 to 0.35 mm.

[0014] In some embodiments of the polypropylene infrared sheet pressing mold assembly, the first pressing plate, the second pressing plate, the third pressing plate and the fourth pressing plate are all made of metal, and the melting point of the metal material is higher than the heating temperature of the polypropylene copolymer pellets or powder.

[0015] In some embodiments of the polypropylene infrared sheet pressing mold assembly, the first pressing plate, the second pressing plate, the third pressing plate and the fourth pressing plate are all aluminum plates.

[0016] In a second aspect, the technical solution of the present application provides a method for manufacturing a polypropylene infrared sheeting mold assembly, comprising:

[0017] S1: punching the second pressing plate to punch out at least one membrane cavity on the second pressing plate, wherein the inner wall spacing of the membrane cavity is greater than a set distance;

[0018] S2: Pressing the second pressing plate to ensure that the membrane cavity is pressed flat;

[0019] S3: placing a third pressing plate above the second pressing plate, placing polypropylene copolymer pellets or powder in a placement area corresponding to the membrane cavity; then placing a fourth pressing plate above the third pressing plate, placing a first pressing plate below the second pressing plate, and heating and pressurizing the four pressing plates as a whole to achieve sheeting;

[0020] S4: putting the four pressing plates that have been heated and pressurized as described above into a cold press as a whole, and then pressurizing them again for a set time, and then releasing the pressure and taking out the four pressing plates, wherein a pressing plate assembly with a concave hole is formed in the membrane cavity;

[0021] S5: taking out the membrane cavity and the pressing plate assembly, removing the overflow, and obtaining a mold assembly.

[0022] The method for making a polypropylene infrared sheeting mold assembly described in some schemes, in the step S1, the second pressing plate is placed under a pneumatic punching machine, and 1 to 4 circular cavities with a diameter of (50±a) mm are punched out in the middle position as film cavities, where a is the allowable error value.

[0023] In some embodiments, the method for manufacturing the polypropylene infrared tabletting mold assembly comprises: in step S2, placing the second pressing plate into a tabletting machine and pressing at a pressure of 150 to 170 bar for 1 to 2 minutes to flatten the mold cavity;

[0024] In step S3, heating and pressurizing the four pressing plates as a whole to achieve tableting includes:

[0025] Place four pressing plates in a hot press for heating and in a tablet press for pressurization. The temperature of the hot press is 195°C to 205°C, the pressure of the tablet press is 150 to 170 bar, and the tableting time is 1 to 2 minutes.

[0026] In the step S4, the four heated and pressurized pressing plates are placed in a cold press as a whole and pressurized again for a set time, including:

[0027] The pressurization pressure is 150-170 bar, and the setting time is 4-6 minutes.

[0028] In a third aspect, the technical solution of the present application provides a sample preparation method, comprising:

[0029] Place a sample with a mass of m into the concave hole of the mold assembly described in any one of the schemes of the second aspect, place a fifth pressing plate with a thickness of (0.50±c) mm above and below the mold assembly respectively, repeat steps S3 and S4 in any one of the second aspect, and obtain an impact-resistant polypropylene sample or a random copolymer polypropylene sample; wherein c is the allowable error.

[0030] Compared with the prior art, the technical solution of this application has at least the following technical effects:

[0031] The present application provides a polypropylene infrared sheet pressing mold assembly and a manufacturing method thereof, wherein the mold assembly is used to prepare infrared samples of random copolymer polypropylene and impact copolymer polypropylene, since a membrane cavity is opened on the second pressing plate, polypropylene copolymer pellets or powder are placed on the third pressing plate at a position corresponding to the membrane cavity, and after heating or pressurization, the placement area of ​​the third pressing plate will be pressed into the membrane cavity, and overflow will only overflow onto the surface of the third pressing plate, which is easy to clean, thereby solving the problems of infrared samples of random copolymer polypropylene and impact copolymer polypropylene made by the prior art, such as mold sticking, easy damage and deformation of the mold, short service life, and uneven thickness of the prepared samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic structural diagram of a polypropylene infrared sheet pressing mold assembly according to an embodiment of the present application;

[0033] Figure 2 This is a schematic diagram of the separation structure of a polypropylene infrared sheet pressing mold assembly according to an embodiment of the present application;

[0034] Figure 3 This is a process flow chart of a method for manufacturing a polypropylene infrared sheet pressing mold assembly according to an embodiment of the present application. DETAILED DESCRIPTION

[0035] The specific implementation of the present application is further described below with reference to the accompanying drawings.

[0036] It is easy to understand that according to the technical solution of the present application, without changing the essential spirit of the present application, a variety of structural modes and implementation modes that can be replaced by those skilled in the art can be replaced with each other. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present application, and should not be regarded as the entirety of the present application or as a limitation or restriction on the technical solution of the application.

[0037] The directional terms such as up, down, left, right, front, back, front, back, top, bottom, etc. mentioned or may be mentioned in this specification are defined relative to the structures shown in the drawings. They are relative concepts and may change accordingly according to different positions and different usage conditions. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0038] The present application embodiment provides a polypropylene infrared tabletting mold assembly, such as Figure 1 and Figure 2As shown, it includes a first pressing plate 101, a second pressing plate 102, a third pressing plate 103 and a fourth pressing plate 104 arranged in sequence. The second pressing plate 102 is formed with at least one membrane cavity 1021, and the inner wall spacing of the membrane cavity 1021 is greater than the set distance; the third pressing plate 103 includes at least one placement area for polypropylene copolymer pellets or powder 105 on the surface away from the second pressing plate 102, and each of the placement areas is opposite to the position of one of the abdominal cavities 1021.

[0039] The mold assembly provided in the present application is used to prepare infrared samples of random copolymer polypropylene and impact copolymer polypropylene, and can ensure that the thickness of the sample meets the test requirements. In addition, since the film cavity 1021 is opened on the second pressing plate 102, the polypropylene copolymer granules or powder 105 are placed at the position corresponding to the film cavity 1021 on the third pressing plate 103. When heated or pressurized, the placement area of ​​the third pressing plate 103 will be pressed into the film cavity 1021, and the overflow will only overflow onto the surface of the third pressing plate 103, which is easy to clean, thereby solving the problems of infrared samples of random copolymer polypropylene and impact copolymer polypropylene made by the prior art sticking to the mold, the mold being easily damaged and deformed, the service life being short, and the thickness of the prepared samples being uneven.

[0040] In the above solution, the membrane cavity 1021 on the second pressing plate 102 includes a plurality of, specifically 1 to 4, which can be selected according to actual conditions. The shape of the membrane cavity 1021 is not limited, and preferably the membrane cavity 1021 is a circular cavity. The number of the membrane cavity 1021 can be selected according to the difficulty of the process. Specifically, selecting two circular membrane cavities can facilitate processing, maximize the use of the material of the pressing plate, and reduce waste.

[0041] Furthermore, the inner diameter of the circular cavity is used as the inner wall spacing, and the inner diameter is (50±a) mm, wherein a is the allowable error value, that is, the inner diameter of the circular cavity is about 50 mm, and can also be adjusted according to the requirements of the sample size during specific implementation.

[0042] In some schemes of the polypropylene infrared sheeting mold assembly, the thickness of the second pressing plate 102 is 0.25mm or 0.5mm, and other thicknesses can be selected according to needs; the thickness of the third pressing plate 103 is in the range of 0.05 to 0.35mm. Such a design can make the thickness of the infrared sample prepared by the mold assembly of this scheme meet the test requirements, that is, the thickness of the random copolymer polypropylene sample is 500±30μm, and the thickness of the impact copolymer polypropylene sample is 250±20μm.

[0043] In order to facilitate processing, the polypropylene infrared pressing plate mold assembly, the first pressing plate 101, the second pressing plate 102, the third pressing plate 103 and the fourth pressing plate 104 are all made of metal material and the melting point of the metal material is higher than the heating temperature of the polypropylene copolymer pellets or powder. In this way, the occurrence of situations such as the pressing plate melting when the polypropylene copolymer pellets or powder are heated is avoided. Preferably, the first pressing plate 101, the second pressing plate 102, the third pressing plate 103 and the fourth pressing plate 104 are all aluminum plates. The mold assembly provided by this solution overcomes the defects of the existing method, uses low-cost aluminum plates to make the mold and can adjust the size of the sample, improves the accuracy of the test method and the efficiency of the detection work, and achieves cost reduction and efficiency improvement.

[0044] In some schemes, such as Figure 3 As shown, a method for manufacturing a polypropylene infrared tabletting mold assembly is provided, comprising:

[0045] S1: Punching the second pressing plate to punch out at least one membrane cavity on the second pressing plate, wherein the inner wall spacing of the membrane cavity is greater than a set distance.

[0046] The shape of the membrane cavity can be selected according to the sample requirements, such as quadrilateral, ellipse, circle, etc. The inner wall spacing is defined according to the shape of the membrane cavity. For example, if it is a quadrilateral, the length of the long side is used as the inner wall spacing, if it is an ellipse, the length of the long axis is used as the inner wall spacing, and if it is a circle, the inner diameter length is used as the inner wall spacing. When punching, a pneumatic punching machine can be used.

[0047] S2: Press the second pressing plate to ensure that the membrane cavity is pressed flat.

[0048] This step can be carried out in a tablet press.

[0049] S3: Place a third pressing plate above the second pressing plate, and place the polypropylene copolymer pellets or powder in the placement area corresponding to the membrane cavity; then set the fourth pressing plate above the third pressing plate, and set the first pressing plate below the second pressing plate, and heat and pressurize the four pressing plates as a whole to achieve sheeting.

[0050] This step can be carried out in a hot press and / or a tablet press, and the pressure needs to be released when taking out.

[0051] S4: Put the four pressing plates that have been heated and pressurized as mentioned above into a cold press as a whole, and then pressurize them again for a set period of time, then release the pressure and take out the four pressing plates, wherein a pressing plate assembly with a concave hole is formed in the membrane cavity.

[0052] Same as step S3, pressure relief is required when taking out.

[0053] S5: taking out the membrane cavity and the pressing plate assembly, removing the overflow, and obtaining a mold assembly.

[0054] Since the third pressing plate is pressed into the concave hole formed by the membrane cavity, the polypropylene copolymer pellets or powder placed in the concave hole will still be on the third pressing plate even if it overflows, and is very easy to remove. This solves the problems of infrared samples of random copolymer polypropylene and impact copolymer polypropylene made by the prior art sticking to the mold, the mold being easily damaged and deformed, the service life being short, and the thickness of the prepared samples being uneven.

[0055] Preferably, in step S1, the second pressing plate is placed under a pneumatic punching machine, and 1 to 4 circular cavities with a diameter of (50±a) mm are punched out in the middle position as film cavities, where a is the allowable error value. That is, the inner diameter of the circular cavity is about 50 mm, which can also be adjusted according to the requirements of the sample size during specific implementation.

[0056] Further preferably, in step S2, the second pressing plate is placed in a tablet press and pressed at a pressure of 150 to 170 bar for 1 to 2 minutes to flatten the mold cavity; in step S3, the four pressing plates are heated and pressurized as a whole to achieve tableting, including: placing the four pressing plates in a hot press for heating and in a tablet press for pressurization, the pressing table temperature of the hot press is 195°C to 205°C, the pressure of the tablet press is 150 to 170 bar, and the tableting time is 1 to 2 minutes; in step S4, the four pressing plates after the above heating and pressurization are placed in a cold press as a whole and pressurized again for a set time, including: the pressurization pressure is 150 to 170 bar, and the set time is 4 to 6 minutes. In specific implementation, aluminum plates are selected for the four pressing plates, and the parameters of each step are set as follows:

[0057] S1-Put an aluminum plate (second pressing plate) with a thickness of 0.25mm or 0.50mm under a pneumatic punching machine, and select 0.5mm for the random copolymer polypropylene infrared tabletting mold assembly, and select 0.25mm for the impact copolymer polypropylene infrared tabletting mold assembly; punch out 1-4 circular mold cavities with a diameter of about 50mm in the middle position, preferably two; S2: Put the aluminum plate (second pressing plate) punched in S1 into the tablet press and press at a pressure of 160bar for 1-2min to press the circular mold cavity flat; S3: Place an aluminum plate (third pressing plate) with a thickness of about 0.1mm-0.25mm on the aluminum plate (second pressing plate), and put the polypropylene copolymer granules or powder into the corresponding cavity hole on the aluminum plate position, and then place aluminum plates (the first and fourth pressing plates) with a thickness of 0.50 mm on the aluminum plate (the third pressing plate) and under the aluminum plate (the second pressing plate), respectively, and put the entire mold into a tablet press for heating and pressurization. The temperature of the upper and lower pressing tables of the hot press or tablet press is 195°C to 205°C, the pressure is 160 bar, and the tableting time is 1-2 min; S4: after the pressure is released and the mold is taken out, it is placed in a cold press and pressurized to 160 bar again for 5 min, and then the pressure is released and the mold is taken out; S5: after taking out the sample, remove the excess overflow, weigh the sample, and obtain the sample mass m required for the next target thickness sample preparation by recording the sample mass and thickness, and at the same time obtain a mold assembly consisting of a mold cavity and an aluminum plate with a concave hole.

[0058] Based on this, this embodiment also provides a sample preparation method, comprising: placing a sample with a mass of m into the concave hole of the mold assembly described above, padding a fifth pressing plate with a thickness of (0.50±c) mm above and below the mold assembly, and repeating steps S3 and S4 to obtain an impact-resistant polypropylene sample or a random copolymer polypropylene sample; wherein c is the allowable error. In specific implementation, a 0.50 mm aluminum plate is padded above and below the mold assembly, and steps S3 and S4 are repeated to obtain an impact-resistant polypropylene sample with a thickness of 0.23-0.27 mm or a random copolymer polypropylene sample with a thickness of 0.47-0.53 mm.

[0059] When preparing the random copolymer polypropylene infrared sample, after obtaining the results of two samples, the thickness test was performed on different positions of the same sample, and the results are shown in Table 1 below.

[0060] Table 1 Thickness of random copolymer polypropylene infrared sample

[0061]

[0062] When preparing the impact-resistant copolymer polypropylene infrared sample, after obtaining the results of two samples, the thickness test was performed on different positions of the same sample, and the results are shown in Table 2 below.

[0063] Table 2 Thickness of impact copolymer polypropylene infrared sample

[0064]

[0065] The data in the above table prove that the mold assembly provided in this application is not only made of inexpensive aluminum plates, with low manufacturing cost and simple process, the mold assembly can be reused and has a long service life, but also the prepared samples have uniform thickness and are easy to demold. It is suitable for the preparation of random copolymer polypropylene and impact copolymer polypropylene infrared samples, and can improve the preparation quality and detection efficiency of infrared samples.

[0066] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0067] The above are only the principles and preferred embodiments of the present application. It should be noted that, for ordinary technicians in this field, on the basis of the principles of the present application, several other modifications can be made, which should also be considered as the protection scope of the present application.

Claims

1. A polypropylene infrared tabletting mold assembly, characterized in that: Including the following arranged in sequence: First pressing plate; A second pressing plate, on which at least one membrane cavity is formed, and the inner wall spacing of the membrane cavity is greater than the set distance; A third pressing plate, comprising at least one placement area for polypropylene copolymer pellets or powder on a surface away from the second pressing plate, each of the placement areas being opposite to a position of the abdominal cavity; Fourth pressure plate.

2. The polypropylene infrared sheet pressing mold assembly according to claim 1, characterized in that: The number of the membrane cavities on the second pressing plate is 1 to 4, and the membrane cavities are circular cavities.

3. The polypropylene infrared sheet pressing mold assembly according to claim 2, characterized in that: The inner diameter of the circular cavity is used as the inner wall spacing, and the inner diameter is (50±a) mm, where a is the allowable error value.

4. The polypropylene infrared sheet pressing mold assembly according to claim 1, characterized in that: The thickness of the second pressing plate is 0.25 mm or 0.5 mm; The thickness of the third pressing plate is in the range of 0.05 to 0.35 mm.

5. The polypropylene infrared sheet pressing mold assembly according to any one of claims 1 to 4, characterized in that: The first pressing plate, the second pressing plate, the third pressing plate and the fourth pressing plate are all made of metal material, and the melting point of the metal material is higher than the heating temperature of the polypropylene copolymer pellets or powder.

6. The polypropylene infrared sheet pressing mold assembly according to claim 5, characterized in that: The first pressing plate, the second pressing plate, the third pressing plate and the fourth pressing plate are all aluminum plates.

7. A method for manufacturing a polypropylene infrared tabletting mold assembly, characterized in that: include: S1: punching the second pressing plate to punch out at least one membrane cavity on the second pressing plate, wherein the inner wall spacing of the membrane cavity is greater than a set distance; S2: Pressing the second pressing plate to ensure that the membrane cavity is pressed flat; S3: placing a third pressing plate above the second pressing plate, placing polypropylene copolymer pellets or powder in a placement area corresponding to the membrane cavity; then placing a fourth pressing plate above the third pressing plate, placing a first pressing plate below the second pressing plate, and heating and pressurizing the four pressing plates as a whole to achieve sheeting; S4: putting the four pressing plates that have been heated and pressurized as described above into a cold press as a whole, and then pressurizing them again for a set time, and then releasing the pressure and taking out the four pressing plates, wherein a pressing plate assembly with a concave hole is formed in the membrane cavity; S5: taking out the membrane cavity and the pressing plate assembly, removing the overflow, and obtaining a mold assembly.

8. The method for making a polypropylene infrared sheeting mold assembly according to claim 7, characterized in that: In the step S1, the second pressing plate is placed under a pneumatic punching machine, and 1 to 4 circular cavities with a diameter of (50±a) mm are punched out in the middle position as film cavities, where a is the allowable error value.

9. The method for making a polypropylene infrared sheeting mold assembly according to claim 7, characterized in that: In the step S2, the second pressing plate is placed in a tablet press and pressed at a pressure of 150 to 170 bar for 1 to 2 minutes to flatten the mold cavity; In step S3, heating and pressurizing the four pressing plates as a whole to achieve tableting includes: Place four pressing plates in a hot press for heating and in a tablet press for pressurization. The temperature of the hot press is 195°C to 205°C, the pressure of the tablet press is 150 to 170 bar, and the tableting time is 1 to 2 minutes. In the step S4, the four heated and pressurized pressing plates are placed in a cold press as a whole and pressurized again for a set time, including: The pressurization pressure is 150-170 bar, and the setting time is 4-6 minutes.

10. A method for preparing a sample, characterized in that: include: Place a sample with a mass of m into the concave hole of the mold assembly described in any one of claims 7 to 9, place a fifth pressing plate with a thickness of (0.50±c) mm above and below the mold assembly, respectively, repeat steps S3 and S4 in any one of claims 7 to 9, and obtain an impact-resistant polypropylene sample or a random copolymer polypropylene sample; wherein c is the allowable error.

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