Thermal insulation foaming material and preparation method thereof

Abstract

The invention discloses a heat preservation and insulation foaming material and a preparation method thereof, the heat preservation and insulation foaming material is polyethylene glycol terephthalate foam, the crystallinity of a polymer matrix of the heat preservation and insulation foaming material is 15-25%, the expansion rate is greater than 8, and the heat conductivity coefficient is less than 0.08 W / (m.k). According to the invention, polyethylene glycol terephthalate is used as a base material, the crystallinity is controllable, the expansion rate of the foam material is improved by controlling the crystallinity of PET, and the material is small in overall heat conductivity coefficient and excellent in thermal insulation performance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a thermal insulation foam material and its preparation method. Background Technology

[0002] Thermal insulation foam possesses excellent thermal insulation properties and diverse applications, making it an indispensable material in modern industry and daily life. Currently, thermal insulation foam is typically made from materials such as polystyrene (PS), polyurethane (PU), polyethylene (PE), and polyethylene terephthalate (PET). Among these, PET exhibits reliable stability at high temperatures, excellent mechanical strength, superior chemical resistance, and environmental friendliness, making it outstanding in meeting modern thermal insulation needs and possessing broad application potential.

[0003] In existing technologies, the preparation of PET thermal insulation foam materials usually requires the addition of fillers, chain extenders and other substances to increase melt strength and thus increase expansion ratio, thereby improving its thermal insulation performance. However, these methods require the addition of additives to the material system, which requires precise control of the amount added. Furthermore, they can lead to problems such as increased costs, poor dispersion uniformity, long production cycles, high equipment requirements, and difficulty in recycling. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to develop a PET foam material and preparation technology that enables the material to have excellent thermal insulation properties without the use of additives.

[0005] To achieve the above objectives, the present invention provides a thermal insulation foam material, which is polyethylene terephthalate foam, with a polymer matrix crystallinity of 15%~25%, an expansion ratio greater than 8, and a thermal conductivity of less than 0.08 W / (m·k).

[0006] This invention uses polyethylene terephthalate (PET) as the matrix material, whose crystallinity is controllable. By controlling the crystallinity of PET, the expansion ratio of the foamed material is increased, resulting in a low overall thermal conductivity and excellent thermal insulation performance.

[0007] Furthermore, the relationship between the expansion ratio of the thermal insulation foam material and the crystallinity of the polymer matrix conforms to the following formula: y = 2.1 / x - 2 ± 1.5 Where x is the crystallinity of the polymer matrix and y is the expansion ratio.

[0008] A higher expansion ratio corresponds to a lower thermal conductivity, resulting in better thermal insulation performance of PET foam. This invention improves the thermal insulation performance of PET foam by controlling the expansion ratio of the foaming material through adjusting the crystallinity of the matrix.

[0009] Furthermore, the average pore size of the thermal insulation foam material is 40~130μm. The pore size is controlled as needed by adjusting the crystallinity of the matrix, ensuring that the pore size is uniformly distributed within the design range and that the thermal conductivity is consistent across all parts of the material.

[0010] This invention also provides a method for preparing the above-mentioned thermal insulation foam material, comprising the following steps: S1. Place PET granules in a mold, press them using a flat vulcanizing machine, and then quench them to obtain sheet material. S2. Anneal the sheet material obtained in step S1. After annealing, the crystallinity of PET is 15%~25%. S3. Put the material obtained in step S2 into a high-pressure reactor and saturate it with saturated gas. S4. Transfer the material obtained in step S3 to a foaming medium for heating and foaming, with an expansion ratio greater than 8. S5. Transfer the material obtained in step S4 to ice water for quenching to obtain thermal insulation foam material.

[0011] This invention utilizes cold crystallization technology to control the formation of numerous fine crystals in PET, and controls the expansion ratio through a foaming process, giving the PET foam excellent thermal insulation properties. Furthermore, the above preparation method does not require additional additives, avoiding the negative impact of additives on material properties, simplifying the production process, reducing production costs, and minimizing environmental impact.

[0012] Furthermore, in step S2, the annealing temperature is 100~125℃, the annealing time is 2~20min, and the annealing temperature T and time t satisfy the relationship: t=-2 / 3T+(88±10), where T is in ℃ and t is in min.

[0013] Further, in step S2, when the annealing temperature is 100~105℃, the annealing time is 13~20min; when the annealing temperature is 105~110℃, the annealing time is 11~13min; when the annealing temperature is 110~115℃, the annealing time is 8~11min; when the annealing temperature is 115~120℃, the annealing time is 2.5~8min; and when the annealing temperature is 120~125℃, the annealing time is 2~2.5min.

[0014] This invention allows for precise control of the crystallization behavior of PET by adjusting the annealing temperature and annealing time. This enables the alteration of the crystal size and morphology of the PET material, achieving the designed degree of crystallinity, and consequently influencing the foaming behavior and physical properties of the PET material.

[0015] Furthermore, in step S3, the saturated gas is carbon dioxide, the saturation pressure is 2~6 MPa, and the saturation time is 24~72 h.

[0016] Furthermore, in step S4, the foaming temperature is 90~140℃ and the foaming time is 10~30s.

[0017] Using environmentally friendly carbon dioxide as a foaming agent, PET sheet material is intermittently foamed by controlling the foaming conditions to obtain foam material with an expansion ratio that meets the design requirements.

[0018] Furthermore, in step S1, the thickness of the sheet material is 0.25~2mm.

[0019] Furthermore, in step S1, the molding temperature is 270~300℃, the pressure is 5~15MPa, and the time is 5~15min.

[0020] Molding can be used to quickly prepare PET sheets of the designed thickness, which facilitates subsequent annealing and foaming steps.

[0021] In summary, compared with the prior art, the present invention has the following beneficial effects: This invention uses PET as raw material and controls the crystallinity of the polymer matrix through an annealing process, thereby affecting the foaming behavior and physical properties of PET material to obtain a foam material with an expansion ratio that meets design requirements. This material has excellent thermal insulation properties and has broad application prospects in building materials, cold chain transportation, and household appliances.

[0022] The material composition of this invention is pure PET, which does not require additional additives, thus avoiding the adverse effects of additives on material performance. Furthermore, the production process is simple, low-cost, and environmentally friendly. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope image of the PET foam material prepared in Example 3 of the present invention.

[0024] Figure 2 This is a scanning electron microscope image of the PET foam material prepared in Example 6 of the present invention.

[0025] Figure 3 This is a scanning electron microscope image of the PET foam material prepared in Comparative Example 2 of the present invention. Detailed Implementation

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art.

[0029] The present invention provides a thermal insulation foam material and its preparation method, the specific steps of which are as follows: S1. Place PET granules in a mold, use a flat vulcanizing machine for molding, and then quench them to obtain sheet material.

[0030] In a specific embodiment, the size of the sheet material corresponds to the size of the mold cavity, and the thickness of the sheet material is 0.25~2mm. Preferably, the thickness of the sheet material is 0.5~1.5mm. In a specific embodiment, the molding conditions are controlled according to the characteristics of PET. Generally, the molding temperature is 270~300℃, the pressure is 5~15MPa, and the time is 5~15min. Preferably, the molding temperature is 280~290℃, the pressure is 10~15MPa, and the time is 10~15min.

[0031] S2. Place the quenched sheet material into an oven for annealing to crystallize PET. The annealing temperature is 100~125℃ and the annealing time is 2~20min. The annealing temperature T (℃) and time t (min) satisfy the following relationship: t=-2 / 3T+(88±10).

[0032] Preferably, when the annealing temperature is 100~105℃, the annealing time is 13~20 min; when the annealing temperature is 105~110℃, the annealing time is 11~13 min; when the annealing temperature is 110~115℃, the annealing time is 8~11 min; when the annealing temperature is 115~120℃, the annealing time is 2.5~8 min; and when the annealing temperature is 120~125℃, the annealing time is 2~2.5 min. By precisely controlling the annealing temperature and time, the crystallization behavior of PET is regulated, ensuring that the crystallinity of PET after annealing is 15%~25%.

[0033] S3. Place the annealed sheet into a high-pressure autoclave and introduce saturated gas to saturate it.

[0034] In a specific embodiment, CO2 is selected as the saturated gas, the saturation pressure is 2~6 MPa, and the saturation time is 24~72 h. Preferably, the saturation pressure is 3~5 MPa, and the saturation time is 60~70 h.

[0035] S4. After the saturation process is completed, transfer the sample to an oil bath for heating and foaming.

[0036] In a specific embodiment, the foaming medium can be selected from dimethyl silicone oil, glycerin, vegetable oil, etc., the foaming temperature is 90~140℃, and the foaming time is 10~30s. By controlling the foaming conditions, PET sheet material is intermittently foamed to obtain a foam material with a cell size distribution range of 40~130μm.

[0037] S5. After foaming, the material is transferred to ice water for quenching to fix the cell structure and obtain thermal insulation foam material.

[0038] The above preparation method utilizes cold crystallization technology to control the formation of a large number of fine crystals in PET, and improves the expansion ratio by optimizing the foaming process, giving the PET foam excellent thermal insulation properties. Furthermore, this preparation method does not require additional additives, avoiding the negative impact of additives on material properties, simplifying the production process, reducing production costs, and minimizing environmental impact.

[0039] The PET thermal insulation foam material provided in the specific embodiments of the present invention has a polymer matrix crystallinity of 15%~25% and an expansion ratio greater than 8. The expansion ratio of the PET foam and the crystallinity of the matrix must satisfy the following formula: y=2.1 / x-2±1.5, where x is the crystallinity of the polymer matrix and y is the expansion ratio.

[0040] Preferably, the average cell size of the PET foam material is 40~130μm. The cell size can be controlled as needed by adjusting the crystallinity of the matrix, ensuring that the cell size of the material is uniformly distributed within the design range and that the thermal conductivity of each part of the material is consistent.

[0041] The aforementioned PET foam material has uniformly distributed cells that meet design requirements, giving it excellent thermal insulation properties. Its thermal conductivity is less than 0.08 W / (m·k), making it a promising candidate for applications in building materials, cold chain transportation, and household appliances.

[0042] The technical solution and effects of the present invention will be illustrated below with specific embodiments.

[0043] Example 1

[0044] PET granules were placed in a mold with a design thickness of 1 mm and molded for 10 minutes using a flat vulcanizing machine at a temperature of 285℃ and a pressure of 15 MPa. Afterward, the granules were quenched to obtain PET sheet material. The quenched sheet was then annealed in an oven at 108℃ for 12 minutes, and the polymer matrix crystallinity was measured to be 19.1%. The annealed sheet was then placed in an autoclave, and CO2 was introduced, saturating it at a pressure of 4 MPa for 72 hours. After saturation, the sample was transferred to a dimethyl silicone oil bath pre-set to 90℃, and the foaming time was set to 20 seconds. After foaming, the material was transferred to ice water for quenching to fix the cell structure, resulting in PET foam material with an expansion ratio of 11.8.

[0045] The average cell size of the PET foam material prepared in this embodiment was tested to be 110 μm, and the thermal conductivity was 0.058 W / (m·K).

[0046] Example 2

[0047] PET granules were placed in a mold with a design thickness of 1 mm and molded for 10 minutes using a flat vulcanizing machine at a temperature of 285℃ and a pressure of 15 MPa. Afterward, the material was quenched to obtain PET sheet material. The quenched sheet was then placed in an oven for annealing at 110℃ for 10 minutes, and the polymer matrix crystallinity was measured to be 20.3%. The annealed sheet was then placed in an autoclave, and CO2 was introduced, saturating it at a saturation pressure of 4 MPa for 72 hours. After saturation, the sample was transferred to a dimethyl silicone oil bath pre-set to 90℃, and the foaming time was set to 20 seconds. After foaming, the material was transferred to ice water for quenching to fix the cell structure, resulting in PET foam material with an expansion ratio of 10.7.

[0048] The average cell size of the PET foam material prepared in this embodiment was tested to be 98 μm, and the thermal conductivity was 0.068 W / (m·K).

[0049] Example 3

[0050] PET granules were placed in a mold with a designed thickness of 1 mm and molded for 10 minutes using a flat vulcanizing machine at a temperature of 285℃ and a pressure of 15 MPa. Afterwards, quenching was performed to obtain PET sheet material. The quenched sheet was then placed in an oven for annealing at 112℃ for 10 minutes, and the polymer matrix crystallinity was measured to be 22.5%. The annealed sheet was then placed in an autoclave, CO2 was introduced, and the material was saturated at 4 MPa for 72 hours. After saturation, the sample was transferred to a dimethyl silicone oil bath pre-set to 90℃, and the foaming time was set to 20 seconds. After foaming, the material was transferred to ice water for quenching to fix the cell structure, resulting in a PET foam material with an expansion ratio of 9.1. Its cell structure is shown below. Figure 1 As shown.

[0051] The average cell size of the PET foam material prepared in this embodiment was tested to be 77 μm, and the thermal conductivity was 0.071 W / (m·K).

[0052] Example 4

[0053] PET granules were placed in a mold with a design thickness of 1 mm and molded for 10 minutes using a flat vulcanizing machine at a temperature of 285℃ and a pressure of 15 MPa. Afterward, the granules were quenched to obtain PET sheet material. The quenched sheet was then placed in an oven for annealing at 110℃ for 10 minutes, and the polymer matrix crystallinity was measured to be 20.3%. The annealed sheet was then placed in an autoclave, and CO2 was introduced, saturating it at a pressure of 4 MPa for 72 hours. After saturation, the sample was transferred to a dimethyl silicone oil bath pre-set to 95℃, and the foaming time was set to 20 seconds. After foaming, the material was transferred to ice water for quenching to fix the cell structure, resulting in PET foam material with an expansion ratio of 14.5.

[0054] The average cell size of the PET foam material prepared in this embodiment was tested to be 117 μm, and the thermal conductivity was 0.049 W / (m·K).

[0055] Example 5

[0056] PET granules were placed in a mold with a design thickness of 1 mm and molded for 10 minutes using a flat vulcanizing machine at a temperature of 285℃ and a pressure of 15 MPa. Afterward, the material was quenched to obtain PET sheet material. The quenched sheet was then placed in an oven for annealing at 110℃ for 10 minutes, and the polymer matrix crystallinity was measured to be 20.3%. The annealed sheet was then placed in an autoclave, and CO2 was introduced, saturating it at a pressure of 4 MPa for 72 hours. After saturation, the sample was transferred to a dimethyl silicone oil bath pre-set to 100℃, and the foaming time was set to 20 seconds. After foaming, the material was transferred to ice water for quenching to fix the cell structure, resulting in PET foam material with an expansion ratio of 16.4.

[0057] The average cell size of the PET foam material prepared in this embodiment was tested to be 126 μm, and the thermal conductivity was 0.038 W / (m·K).

[0058] Example 6

[0059] PET granules were placed in a mold with a design thickness of 1 mm and molded for 10 minutes using a flat vulcanizing machine at a temperature of 285℃ and a pressure of 15 MPa. Afterwards, quenching was performed to obtain PET sheet material. The quenched sheet was then placed in an oven for annealing at 110℃ for 10 minutes, and the polymer matrix crystallinity was measured to be 20.3%. The annealed sheet was then placed in an autoclave, CO2 was introduced, and the material was saturated at 4 MPa for 72 hours. After saturation, the sample was transferred to a dimethyl silicone oil bath pre-set to 105℃, and the foaming time was set to 20 seconds. After foaming, the material was transferred to ice water for quenching to fix the cell structure, resulting in a PET foam material with an expansion ratio of 15.9. Its cell structure is shown below. Figure 2 As shown.

[0060] The average cell size of the PET foam material prepared in this embodiment was tested to be 129 μm, and the thermal conductivity was 0.043 W / (m·K).

[0061] Example 7

[0062] PET granules were placed in a mold with a design thickness of 1 mm and molded for 10 minutes using a flat vulcanizing machine at a temperature of 285℃ and a pressure of 15 MPa. Afterward, the material was quenched to obtain PET sheet material. The quenched sheet was then placed in an oven for annealing at 118℃ for 5 minutes, and the polymer matrix crystallinity was measured to be 17.3%. The annealed sheet was then placed in an autoclave, and CO2 was introduced, saturating it at a pressure of 4 MPa for 72 hours. After saturation, the sample was transferred to a dimethyl silicone oil bath pre-set to 95℃, and the foaming time was set to 20 seconds. After foaming, the material was transferred to ice water for quenching to fix the cell structure, resulting in PET foam material with an expansion ratio of 12.7.

[0063] The average cell size of the PET foam material prepared in this embodiment was tested to be 118 μm, and the thermal conductivity was 0.054 W / (m·K).

[0064] Example 8

[0065] PET granules were placed in a mold with a design thickness of 1 mm and molded for 10 minutes using a flat vulcanizing machine at a temperature of 285℃ and a pressure of 15 MPa. Afterward, the granules were quenched to obtain PET sheet material. The quenched sheet was then annealed in an oven at 104℃ for 15 minutes, and the polymer matrix crystallinity was measured to be 16.9%. The annealed sheet was then placed in an autoclave, and CO2 was introduced, saturating it at a pressure of 4 MPa for 72 hours. After saturation, the sample was transferred to a dimethyl silicone oil bath pre-set to 95℃, and the foaming time was set to 20 seconds. After foaming, the material was transferred to ice water for quenching to fix the cell structure, resulting in PET foam material with an expansion ratio of 11.2.

[0066] The average cell size of the PET foam material prepared in this embodiment was tested to be 104 μm, and the thermal conductivity was 0.061 W / (m·K).

[0067] Comparative Example 1 PET granules were placed in a mold with a designed thickness of 1 mm and molded for 10 minutes using a flat vulcanizing machine at a temperature of 285℃ and a pressure of 15 MPa. Afterward, the material was quenched to obtain PET sheet material. The quenched sheet material was placed in an autoclave, CO2 was introduced, and the material was saturated at a pressure of 4 MPa for 72 hours. After saturation, the sample was transferred to a dimethyl silicone oil bath pre-set to 90℃, and the foaming time was set to 20 seconds. After foaming, the material was transferred to ice water for quenching to fix the cell structure, resulting in PET foam material with an expansion ratio of 5.9.

[0068] The average cell size of the PET foam material prepared in this comparative example was 75 μm, and the thermal conductivity was 0.090 W / (m·K).

[0069] Comparative Example 2 PET granules were placed in a mold with a designed thickness of 1 mm and molded for 10 minutes using a flat vulcanizing machine at a temperature of 285℃ and a pressure of 15 MPa. Afterwards, quenching was performed to obtain PET sheet material. The quenched sheet material was placed in an autoclave, CO2 was introduced, and saturation was carried out at a saturation pressure of 4 MPa for 72 hours. After saturation, the sample was transferred to a dimethyl silicone oil bath pre-set to 120℃, and the foaming time was set to 20 seconds. After foaming, the material was transferred to ice water for quenching to fix the cell structure, resulting in PET foam material with an expansion ratio of 7.8. Its cell structure is as follows: Figure 3 As shown.

[0070] The average cell size of the PET foam material prepared in this comparative example was 81 μm, and the thermal conductivity was 0.085 W / (m·K).

[0071] The physical property test results of the PET foam materials obtained in Examples 1 to 8, Comparative Examples 1 and 2 are shown in Table 1 below. It can be seen that the PET sheet after annealing has a suitable degree of crystallinity and a foam material with uniformly distributed cell size that meets the design requirements is obtained. The thermal conductivity of this PET foam material is significantly reduced.

[0072] Table 1 Performance test results of PET foam materials in the examples and comparative examples sample Crystallinity (%) Expansion ratio Cell size (μm) Thermal conductivity (W / (m·K)) Example 1 19.1 11.8 110 0.058 Example 2 20.3 10.7 98 0.068 Example 3 22.5 9.1 77 0.071 Example 4 20.3 14.5 117 0.049 Example 5 20.3 16.4 126 0.038 Example 6 20.3 15.9 129 0.043 Example 7 17.3 12.7 118 0.054 Example 8 16.9 11.2 104 0.061 Comparative Example 1 / 5.9 75 0.090 Comparative Example 2 / 7.8 81 0.085 While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the scope of protection of this invention.

Claims

1. A thermal insulation foam material, characterized in that, The thermal insulation foam material is polyethylene terephthalate foam, with a polymer matrix crystallinity of 15%~25%, an expansion ratio greater than 8, and a thermal conductivity of less than 0.08 W / (m·k).

2. The thermal insulation foam material according to claim 1, characterized in that, The relationship between the expansion ratio of the thermal insulation foam material and the crystallinity of the polymer matrix conforms to the following formula: y = 2.1 / x - 2 ± 1.5 Where x is the crystallinity of the polymer matrix and y is the expansion ratio.

3. The thermal insulation foam material according to claim 1 or 2, characterized in that, The average pore size of the thermal insulation foam material is 40~130μm.

4. A method for preparing a thermal insulation foam material as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Place polyethylene terephthalate granules in a mold, press them using a flat vulcanizing machine, and then quench them to obtain sheet material. S2. Anneal the sheet material obtained in step S1. After annealing, the crystallinity of polyethylene terephthalate is 15%~25%. S3. Put the material obtained in step S2 into a high-pressure reactor and saturate it with saturated gas. S4. Transfer the material obtained in step S3 to a foaming medium for heating and foaming, with an expansion ratio greater than 8. S5. Transfer the material obtained in step S4 to ice water for quenching to obtain thermal insulation foam material.

5. The method for preparing the thermal insulation foam material according to claim 4, characterized in that, In step S2, the annealing temperature is 100~125℃, the annealing time is 2~20min, and the annealing temperature T and time t satisfy the relationship: t=-2 / 3T+(88±10), where T is in ℃ and t is in min.

6. The method for preparing the thermal insulation foam material according to claim 5, characterized in that, In step S2, when the annealing temperature is 100~105℃, the annealing time is 13~20min; when the annealing temperature is 105~110℃, the annealing time is 11~13min; when the annealing temperature is 110~115℃, the annealing time is 8~11min; when the annealing temperature is 115~120℃, the annealing time is 2.5~8min; and when the annealing temperature is 120~125℃, the annealing time is 2~2.5min.

7. The method for preparing the thermal insulation foam material according to claim 4, characterized in that, In step S3, the saturated gas is carbon dioxide, the saturation pressure is 2~6MPa, and the saturation time is 24~72h.

8. The method for preparing the thermal insulation foam material according to claim 4, characterized in that, In step S4, the foaming temperature is 90~140℃ and the foaming time is 10~30s.

9. The method for preparing the thermal insulation foam material according to claim 4, characterized in that, In step S1, the thickness of the sheet material is 0.25~2mm.

10. The method for preparing the thermal insulation foam material according to claim 4, characterized in that, In step S1, the molding temperature is 270~300℃, the pressure is 5~15MPa, and the time is 5~15min.

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