Extruded sheet and method for its production

Abstract

The application relates to the technical field of building materials, in particular to an extruded sheet and a preparation method thereof, which comprises the following raw materials in parts by weight: polystyrene resin 60-70 parts, copolymer resin 30-40 parts, foaming agent 5-10 parts, antioxidant 0.5-0.8 parts, zinc stearate 1-2 parts and calcium carbonate 0.2-0.5 parts. The gradient segment design of the amphiphilic copolymer and the sodium alginate-calcium ion crosslinking network are utilized, the compression strength and the bending strength of the prepared extruded sheet are improved, and the extruded sheet has good rigidity and anti-deformation capacity. Meanwhile, the water vapor permeability of the extruded sheet is low, which indicates that the prepared extruded sheet can effectively balance the barrier and air permeability requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, in particular to an extruded board and a preparation method thereof. Background Art

[0002] Extruded board is a rigid foam plastic sheet formed by heating and extrusion. It features a continuous, uniform surface and a closed-cell honeycomb structure. It is a key component of third-generation rigid foam insulation materials. With the rapid development of the construction industry and increasing demands for energy conservation and emission reduction, the demand for high-performance insulation materials is growing. Extruded board, with its excellent thermal insulation, compressive strength, moisture resistance, and environmental friendliness, shows great potential for application in building insulation, moisture-proofing, and heat insulation. Extruded board boasts a complete, closed-cell honeycomb structure with no gaps between cells, resulting in low thermal conductivity and high compressive strength. Extruded board is particularly widely used in the construction sector. For wall insulation, extruded board can effectively reduce building energy consumption and improve living comfort. For roof insulation, it effectively prevents roof leaks and frost, extending the service life of buildings. For floor insulation, extruded board effectively controls frost heave and protects foundations. Extruded board is also widely used for moisture and insulation in low-temperature storage floors, parking platforms, airport runways, and highways.

[0003] Extruded board materials are inherently strong, making them brittle and rigid. Their structural flexibility is low, making them difficult to bend and deform, prone to bulging, and even causing the insulation layer to fall off. During construction, drilling holes or performing other processing operations on the board can easily cause cracks, breakage, or splitting. Furthermore, the surface of extruded board is relatively smooth, with poor adhesive absorption and poor adhesion to other materials. During the bonding process, the surface of the extruded board can be easily damaged, resulting in a weak bond and prone to falling off or cracking. Extruded board has a dense foam structure, resulting in poor air permeability. In conditions with large temperature differences and high humidity across the panel, moisture easily accumulates within the extruded board, causing condensation, which affects its insulation effectiveness and service life. Furthermore, the disposal of discarded extruded board is relatively difficult, making it challenging to recycle. Summary of the Invention

[0004] In order to solve the problems mentioned in the above background technology, the present invention provides an extruded board and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] An extruded board comprises the following raw materials in parts by weight: 60-70 parts of polystyrene resin, 30-40 parts of copolymer resin, 5-10 parts of foaming agent, 0.5-0.8 parts of antioxidant, 1-2 parts of zinc stearate and 0.2-0.5 parts of calcium carbonate.

[0007] Further, the foaming agent includes one or more of azodicarbonamide, sodium bicarbonate, azobisisobutyronitrile and cyclopentane.

[0008] Further, the antioxidant includes one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-p-cresol, tris(2,4-di-tert-butylphenyl)phosphite, dilauryl thiodipropionate and N,N'-diphenyl-p-phenylenediamine.

[0009] Furthermore, the copolymer resin is prepared by the following steps:

[0010] S1. Add adipic acid, butanediol, and L-malic acid into a reactor, purge with nitrogen, control the temperature, and stir to react for 2-3 hours. Add tetrabutyl titanate, increase the temperature, increase the vacuum, and react for 4-5 hours. After the reaction, pour the molten copolymer into a polytetrafluoroethylene mold, cool it, and crush it into particles with a particle size of less than 1 mm. Wash it with methanol, and vacuum dry it at 60°C to constant weight to obtain polybutylene adipate-polymalic acid copolymer particles.

[0011] S2. Add the copolymer particles to dimethyl sulfoxide, stir at 55-60°C for 2-3 hours until completely dissolved to obtain solution A, add sodium alginate to water, stir at 40-45°C for 1-2 hours until fully swollen to obtain solution B, slowly drop solution B into solution A, shear and emulsify to form an oil-in-water emulsion, add calcium chloride aqueous solution, continue stirring for 2-3 hours, pour the composite emulsion into water to precipitate the resin, let it stand for 1-2 hours, filter, wash, and dry to obtain a white porous copolymer resin.

[0012] Furthermore, in step S1, the mass ratio of adipic acid, butanediol, L-malic acid and tetrabutyl titanate is (10-11): (7.5-8): (8-9): (0.2-0.3).

[0013] Furthermore, in step S2, the mass ratio of the copolymer particles to dimethyl sulfoxide is (2.5-3): (45-50), the mass ratio of sodium alginate to water is (5-6): (50-60), the mass ratio of calcium chloride to water in the calcium chloride aqueous solution is (2-3): (10-15), and the addition amount is 15-16 wt%.

[0014] Furthermore, in step S1, the temperature is controlled to be 150-160°C, the temperature is increased to 210-220°C, and the vacuum degree is increased to <10Pa.

[0015] Furthermore, in step S2, the shearing speed is 5000-6000 rpm, and the emulsification time is 10-15 min.

[0016] According to another aspect of the present invention, there is provided a method for preparing the above-mentioned extruded board, comprising the following steps:

[0017] A1. Dry the polystyrene resin and copolymer resin by weight at 80-85°C for 4-5 hours, add the dried polystyrene resin, copolymer resin, antioxidant, zinc stearate, and calcium carbonate into a high-speed mixer, mix at 500-600 rpm for 10-20 minutes until uniform, and feed into a twin-screw extruder for zoned heating and extrusion. Inject a foaming agent into the melting section using a high-pressure metering pump at a pressure of 8-12 MPa. After the molten material is extruded through the die, it is rapidly decompressed and expanded to form a closed-cell structure.

[0018] A2. Rapidly cool to below 60°C through a cooling roller and a shaping die, perform corona treatment at a power of 4.5-5kW and a speed of 5-6m / min, and cut to obtain an extruded board.

[0019] Furthermore, in the twin-screw extruder in step A1, L / D=40:1, the screw diameter is 110-120 mm, the zone heating is specifically as follows: feeding section: 180-200°C, compression section: 200-220°C, melting section: 220-240°C, die section: 180-200°C, screw speed is 200-300 rpm, and extrusion speed is 1-2 m / min.

[0020] Beneficial effects of the present invention:

[0021] 1. In the technical solution of the present invention, the amphiphilic gradient block molecular chain (polybutylene adipate-polymalic acid copolymer) forms a microphase separation structure through the gradient distribution of hydrophobic-hydrophilic units. The polybutylene adipate segment provides good flexibility, while the polymalic acid segment increases the rigidity of the molecular chain. The polybutylene adipate segment (hydrophobic segment) is compatible with the polystyrene matrix through van der Waals forces, while the β-hydroxycarboxylic acid group of the polymalic acid segment (hydrophilic segment) forms a dynamic cross-linked network through hydrogen bonds, significantly improving the impact toughness of the material. At the same time, the chelated cross-linked network of sodium alginate and calcium ions forms an interpenetrating structure with the copolymer, making the stress dispersion of the sheet more uniform when punching or cutting.

[0022] 2. In the technical solution of the present invention, the bonding performance and interface bonding ability of the extruded board are significantly improved. When a polyurethane modified adhesive is used, the isocyanate group (-NCO) in its molecular chain undergoes a cross-linking reaction with the hydroxyl group (-OH) on the surface of the extruded board to form a covalent bond, so that the bonding layer does not have hollowing or falling off.

[0023] 3. In the technical solution of this invention, during the emulsification process, the copolymer solution is sheared into tiny droplets and dispersed in the continuous phase, forming multi-level pores, which improves the air permeability of the extruded board. The introduction of a sodium alginate-calcium ion crosslinking layer causes the carboxylic acid groups to dissociate at high humidity, forming hydrophilic channels that accelerate water vapor diffusion. At low humidity, the closed-cell structure is restored, preventing condensation.

[0024] 4. In the technical solution of the present invention, the polybutylene adipate and polymalic acid segments in the copolymer resin are both aliphatic polyesters, which have good biodegradability, help reduce waste generation, improve resource utilization efficiency, and reduce environmental pollution and resource waste. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market.

[0027] Preparation Example 1

[0028] The copolymer resin is prepared by the following steps:

[0029] S1. Add 1 kg of adipic acid, 0.75 kg of butanediol, and 0.8 kg of L-malic acid into a reactor, protect with nitrogen, control the temperature at 150° C., stir and react for 2 h, add 0.02 kg of tetrabutyl titanate, raise the temperature to 210° C., increase the vacuum degree to 8 Pa, and react for 4 h. After the reaction, pour the molten copolymer into a polytetrafluoroethylene mold, cool it, crush it into particles, wash it with methanol, and vacuum dry it at 60° C. to constant weight to obtain polybutylene adipate-polymalic acid copolymer particles;

[0030] S2. Add 0.25 kg of copolymer particles to 4.5 kg of dimethyl sulfoxide, stir at 55 ° C for 2 hours until completely dissolved to obtain solution A, add 0.5 kg of sodium alginate to 5 kg of water, stir at 40 ° C for 1 hour until fully swollen to obtain solution B, slowly drop solution B into solution A, shear emulsification at a speed of 5000 rpm for 10 minutes, add 0.2 kg of calcium chloride to 1 kg of water to prepare a calcium chloride aqueous solution, add 15 wt% calcium chloride aqueous solution dropwise, continue stirring for 2 hours, pour the composite emulsion into water to precipitate the resin, let it stand for 1-2 hours, filter, wash, and dry to obtain a white porous copolymer resin.

[0031] Preparation Example 2

[0032] The copolymer resin is prepared by the following steps:

[0033] S1. Add 1.05 kg of adipic acid, 0.78 kg of butanediol, and 0.85 kg of L-malic acid into a reactor, protect with nitrogen, control the temperature at 155° C., stir and react for 2.5 hours, add 0.025 kg of tetrabutyl titanate, raise the temperature to 215° C., increase the vacuum degree to 8 Pa, and react for 4.5 hours. After the reaction is completed, pour the molten copolymer into a polytetrafluoroethylene mold, cool it, crush it into particles, wash it with methanol, and vacuum dry it at 60° C. to constant weight to obtain polybutylene adipate-polymalic acid copolymer particles;

[0034] S2. Add 0.28 kg of copolymer particles to 4.7 kg of dimethyl sulfoxide, stir at 57 ° C for 2.5 hours until completely dissolved to obtain solution A, add 0.55 kg of sodium alginate to 5.5 kg of water, stir at 42 ° C for 1.5 hours until fully swollen to obtain solution B, slowly drop solution B into solution A, shear emulsification at a speed of 5500 rpm for 12 minutes, add 0.25 kg of calcium chloride to 1.25 kg of water to prepare a calcium chloride aqueous solution, add 15.5 wt% calcium chloride aqueous solution dropwise, continue stirring for 2.5 hours, pour the composite emulsion into water to precipitate the resin, let it stand for 1.5 hours, filter, wash, and dry to obtain a white porous copolymer resin.

[0035] Preparation Example 3

[0036] The copolymer resin is prepared by the following steps:

[0037] S1. Add 1.1 kg of adipic acid, 0.8 kg of butanediol, and 0.9 kg of L-malic acid into a reactor, protect with nitrogen, control the temperature at 160° C., stir and react for 3 h, add 0.03 kg of tetrabutyl titanate, raise the temperature to 220° C., increase the vacuum degree to 8 Pa, and react for 5 h. After the reaction is completed, pour the molten copolymer into a polytetrafluoroethylene mold, cool it, crush it into particles, wash it with methanol, and vacuum dry it at 60° C. to constant weight to obtain polybutylene adipate-polymalic acid copolymer particles;

[0038] S2. Add 0.3 kg of copolymer particles to 5 kg of dimethyl sulfoxide, stir at 60 ° C for 2-3 hours until completely dissolved to obtain solution A, add 0.6 kg of sodium alginate to 6 kg of water, stir at 45 ° C for 2 hours until fully swollen to obtain solution B, slowly drop solution B into solution A, shear emulsification at a speed of 6000 rpm for 15 minutes, add 0.3 kg of calcium chloride to 1.5 kg of water to prepare a calcium chloride aqueous solution, add 16 wt% calcium chloride aqueous solution dropwise, continue stirring for 3 hours, pour the composite emulsion into water to precipitate the resin, let it stand for 2 hours, filter, wash, and dry to obtain a white porous copolymer resin.

[0039] Example 1

[0040] A method for preparing an extruded board comprises the following steps:

[0041] A1. 60 parts of polystyrene resin and 30 parts of the copolymer resin obtained in Preparation Example 1 were dried at 80° C. for 4 h, and the dried 60 parts of polystyrene resin, 30 parts of the copolymer resin obtained in Preparation Example 1, 0.5 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1 part of zinc stearate and 0.2 parts of calcium carbonate were added to a high-speed mixer, mixed at 500 rpm for 10 min until uniform, and fed into a twin-screw extruder. The length-to-diameter ratio (L / D) of the extruder is 40:1, the screw diameter is 110 mm, and the twin-screw extruder is divided into a feeding section, a compression section, a melting section, and a die section. The temperature settings of each section are as follows: feeding section: 180°C, compression section: 200°C, melting section: 220°C, and die section: 180°C. Extrusion is performed in different zones. 5 parts of cyclopentane are injected into the melting section via a high-pressure metering pump at a pressure of 8 MPa. After the molten material is extruded through the die, it is rapidly decompressed and expanded to form a closed-cell structure.

[0042] A2. Rapidly cool to 50°C through a cooling roller and a shaping die, perform corona treatment at a power of 4.5kW and a speed of 5m / min, and cut to obtain an extruded board.

[0043] Example 2

[0044] A method for preparing an extruded board comprises the following steps:

[0045] A1. 65 parts of polystyrene resin and 35 parts of the copolymer resin obtained in Preparation Example 2 were dried at 82° C. for 4.5 h. The dried 65 parts of polystyrene resin, 35 parts of the copolymer resin obtained in Preparation Example 2, 0.6 parts of 2,6-di-tert-butyl-p-cresol, 1.5 parts of zinc stearate and 0.4 parts of calcium carbonate were added to a high-speed mixer and mixed at 550 rpm for 15 min until uniform. The length-to-diameter ratio (L / D) of the twin-screw extruder was 40:1, the screw diameter was 115 mm, and the twin-screw extruder was divided into a feeding section, a compression section, a melting section and a die section. The temperature of each section was set as follows: feeding section: 190° C., compression section: 210° C., melting section: 230° C., die section: 190° C., zone heating and extrusion, 8 parts of azodicarbonamide were injected into the melting section by a high-pressure metering pump at a pressure of 10 MPa. After the molten material was extruded through the die, it was rapidly decompressed and expanded to form a closed-cell structure.

[0046] A2. Rapidly cool to 50°C through a cooling roller and a shaping die, perform corona treatment at a power of 4.8kW and a speed of 5.5m / min, and cut to obtain an extruded board.

[0047] Example 3

[0048] A method for preparing an extruded board comprises the following steps:

[0049] A1. 70 parts of polystyrene resin and 40 parts of the copolymer resin obtained in Preparation Example 3 were dried at 85° C. for 5 h, and 70 parts of the dried polystyrene resin, 40 parts of the copolymer resin obtained in Preparation Example 3, 0.8 parts of tris(2,4-di-tert-butylphenyl)phosphite, 2 parts of zinc stearate and 0.5 parts of calcium carbonate were added to a high-speed mixer and mixed at 600 rpm for 20 min until uniform. The length-to-diameter ratio (L / D) of the twin-screw extruder was 40:1, the screw diameter was 120 mm, and the twin-screw extruder was divided into a feeding section, a compression section, a melting section and a die section. The temperature of each section was set as follows: feeding section: 200° C., compression section: 220° C., melting section: 240° C., and die section: 200° C. The sections were heated and extruded in different zones. 10 parts of sodium bicarbonate were injected into the melting section by a high-pressure metering pump at a pressure of 12 MPa. After the molten material was extruded through the die, it was rapidly decompressed and expanded to form a closed-cell structure.

[0050] A2. Rapidly cool to 50°C through a cooling roller and a shaping die, perform corona treatment at a power of 5 kW and a speed of 6 m / min, and cut to obtain an extruded board.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 1 is that polybutylene adipate is used instead of the copolymer resin, and the remaining steps are the same as those in Example 1.

[0053] Comparative Example 2

[0054] The difference between this comparative example and Example 2 is that polymalic acid is used instead of the copolymer resin, and the remaining steps are the same as those in Example 2.

[0055] Comparative Example 3

[0056] The difference between this comparative example and Example 3 is that polystyrene is used instead of the copolymer resin, and the remaining steps are the same as those in Example 3.

[0057] (I) Compression strength test: Prepare the samples of Examples 1-3 and Comparative Examples 1-3 respectively with reference to GB / T 8813-2020 “Determination of compression properties of rigid foam plastics”. Condition them at 23±2°C and 50±5% RH for 88 h. Set the universal testing machine (Instron 5967) to a loading rate of 2 mm / min, adjust the distance between the compression plates to the initial thickness of the sample, center the sample, and compress it at a constant rate until it deforms by 10%. Record the maximum load and calculate the compressive strength d. m , compression strength = maximum load / initial cross-sectional area, the results are shown in Table 1:

[0058] Table 1. Compressive strength test results of Examples 1-3 and Comparative Examples 1-3

[0059] sample Maximum load (kN) <![CDATA[Initial cross-sectional area (cm 2 )]]> <![CDATA[d m (kPa)]]> Example 1 4.81 25 192.4 Example 2 4.86 25 194.4 Example 3 4.92 25 196.8 Comparative Example 1 3.14 25 125.6 Comparative Example 2 2.85 25 114.0 Comparative Example 3 3.36 25 134.4

[0060] (II) Flexural strength test: Specimens (80 × 20 × 4 mm) of Examples 1-3 and Comparative Examples 1-3 were prepared according to ISO 178 "Plastics — Determination of flexural properties." A universal testing machine (KZ-DSC-20, equipped with a three-point bending fixture) was set with a support roller spacing of 200 mm and a loading rate of 1 mm / min. A displacement meter was fixed below the midpoint of the specimen and conditioned at 23 ± 2°C, 50 ± 5% RH for 48 h.

[0061] The specimen was placed in the center of the three-point bending fixture, and an initial load of 5N was applied. The displacement meter was reset to zero, and the load was applied at a constant rate of 1mm / min until the specimen broke. The maximum load (F m ), calculate the bending strength (σ f ), Where L = 200 mm, b is the width of the sample, and h is the thickness of the sample. The results are shown in Table 2:

[0062] Table 2. Bending strength test results of Examples 1-3 and Comparative Examples 1-3

[0063] sample Maximum load (N) Flexural strength (MPa) Example 1 385 56.4 Example 2 389 57.7 Example 3 397 58.9 Comparative Example 1 233 34.6 Comparative Example 2 214 31.8 Comparative Example 3 258 38.3

[0064] (III) Water Vapor Permeability Test: Referring to GB / T 17146-2015 "Test Method for Water Vapor Permeability of Building Materials and Their Products," circular specimens with a diameter of 70 mm and a thickness of 32 mm were prepared for Examples 1-3 and Comparative Examples 1-3, respectively. These specimens were conditioned at 23±2°C and 50±5% RH for 48 hours. Anhydrous calcium chloride was placed in the permeability cup of a cup-type water vapor transmission rate tester (WVTR-RC6). Each specimen was covered with the cup opening and sealed with wax. The distance between the specimen and the desiccant was 6 mm. The temperature was set at 38±0.5°C and the relative humidity was maintained at 90%±2% RH (high-humidity side) versus the dry side. The test was conducted for 1 hour, and the water vapor permeability (WVP) was calculated. Where Δm is the mass increment of the moisture permeable cup (g), d is the thickness of the sample (m), and A is the effective area of ​​the sample (m 2 ), t is the test time (s), and ΔP is the water vapor pressure difference (Pa). The results are shown in Table 3:

[0065] Table 3. Water vapor permeability test results of Examples 1-3 and Comparative Examples 1-3

[0066]

[0067]

[0068] As can be seen from Tables 1 and 2, the compressive strength (192.4–196.8 kPa) and flexural strength (56.4–58.9 MPa) of Examples 1-3 are significantly higher than those of the comparative examples (compressive strength 114.0–134.4 kPa, flexural strength 31.8–38.3 MPa). The examples use polybutylene adipate-polymalic acid copolymer (PBA-PLA), while the comparative examples use a single polymer (e.g., polystyrene, polybutylene adipate, or polymalic acid).

[0069] In the PBA-PLA copolymer, polybutylene adipate (the hydrophobic segment) may be compatible with the polystyrene matrix through van der Waals forces, providing flexibility. The β-hydroxycarboxylic acid groups of polymalic acid (the hydrophilic segment) may form a dynamic crosslinking network through hydrogen bonding, enhancing rigidity. The carboxylic acid groups of polymalic acid and the hydroxyl groups of sodium alginate may form hydrogen bonds, further forming an interpenetrating network at the interface, dispersing stress and potentially preventing fracture caused by stress concentration. Comparative Examples 1-3 may suffer from performance degradation due to the lack of such interactions in the single polymers.

[0070] In step S2 of the preparation example, sodium alginate and calcium chloride are embedded in the copolymer matrix through ionic crosslinking to form a three-dimensional network structure, which may form a physical reinforcement phase. The embodiment forms a uniform closed-cell structure through high-pressure foaming, which may reduce open-cell defects. The closed-cell structure disperses the compressive load and improves deformation resistance. However, the comparative example has a high open porosity and reduced strength due to the poor foaming compatibility of the single polymer (pure polystyrene in comparative example 3).

[0071] As can be seen from Table 3, the WVP (4.26–4.65 ng / Pa·s·m) of Examples 1-3 is much lower than that of the comparative example (9.68–10.84 ng / Pa·s·m). The polar carboxylic acid groups of polymalic acid may form hydrogen bonds with water molecules, delaying the diffusion path of water vapor. At the same time, the regularity of the copolymer molecular chain may reduce the molecular gap and reduce the permeation channel. When the humidity is high, the carboxylic acid groups of the sodium alginate-calcium ion cross-linked network dissociate to form hydrophilic channels, which may accelerate the diffusion of water vapor (prevent condensation); when the humidity is low, the closed-cell structure recovers and blocks water vapor. The comparative example may lack such a dynamic response mechanism and have a higher permeability. The embodiment uses a high-pressure metering pump to precisely control the injection of the foaming agent to form uniform closed cells, while the comparative example has poor compatibility of the foaming agent of the single polymer (the polybutylene adipate of the comparative example 1 may be incompatible with cyclopentane), resulting in an increase in connected channels and an increase in permeability.

[0072] In Comparative Example 1, the lack of rigid segments and hydrogen-bonded crosslinking networks of polymalic acid may have resulted in excessive molecular chain flexibility, making it susceptible to plastic deformation upon compression (compressive strength was only 125.6 kPa). In Comparative Example 2, the excessive presence of carboxylic acid groups may have led to excessive crosslinking of the molecular chains, forming a brittle structure (flexural strength 31.8 MPa), and the strong hydrophilicity further reduced the strength after moisture absorption.

[0073] Comparative Example 3 has poor compatibility with sodium alginate, and phase separation may lead to interface defects. In addition, the closed porosity is low (WVP=10.07 ng / Pa·s·m), and both mechanical and barrier properties are deteriorated.

[0074] In summary, the gradient segment design of the amphiphilic copolymer and the sodium alginate-calcium ion crosslinking network improve the compressive and flexural strengths of the examples, resulting in extruded boards with excellent rigidity and deformation resistance. Furthermore, the water vapor permeability of the examples is over 60% lower than that of the comparative examples, demonstrating that the extruded boards produced in the examples effectively balance barrier and breathability requirements.

[0075] Throughout the specification, reference to terms such as "Preparation," "Example," or "Examples" indicates that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or preparation are included in at least one embodiment or preparation of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or preparation. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or preparations.

[0076] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An extruded board, characterized in that: The following raw materials are included in parts by weight: 60-70 parts of polystyrene resin, 30-40 parts of copolymer resin, 5-10 parts of foaming agent, 0.5-0.8 parts of antioxidant, 1-2 parts of zinc stearate and 0.2-0.5 parts of calcium carbonate; Wherein, the copolymer resin comprises the following steps to prepare: S1. Add adipic acid, butanediol, and L-malic acid to a reactor, pass nitrogen protection, control the temperature, and stir to react for 2-3 hours. Add tetrabutyl titanate, increase the temperature, increase the vacuum degree, and react for 4-5 hours. After the reaction, pour the molten copolymer into a polytetrafluoroethylene mold, cool it, crush it into particles, wash it with methanol, and vacuum dry it to constant weight to obtain polybutylene adipate-polymalic acid copolymer particles; S2. Add the copolymer particles to dimethyl sulfoxide and stir at 55-60°C for 2-3 hours to obtain solution A. Add sodium alginate to water and stir at 40-45°C for 1-2 hours to obtain solution B. Slowly drop solution B into solution A, shear and emulsify, add calcium chloride aqueous solution dropwise, continue stirring for 2-3 hours, pour the composite emulsion into water to precipitate the resin, let it stand for 1-2 hours, filter, wash, and dry to obtain the copolymer resin.

2. An extruded board according to claim 1, characterized in that: The blowing agent includes one or more of azodicarbonamide, sodium bicarbonate, azobisisobutyronitrile and cyclopentane.

3. An extruded board according to claim 1, characterized in that: The antioxidant includes one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-p-cresol, tris(2,4-di-tert-butylphenyl)phosphite, dilauryl thiodipropionate and N,N'-diphenyl-p-phenylenediamine.

4. An extruded board according to claim 1, characterized in that: The mass ratio of adipic acid, butanediol, L-malic acid and tetrabutyl titanate in step S1 is (10-11): (7.5-8): (8-9): (0.2-0.3).

5. An extruded board according to claim 1, characterized in that: In step S2, the mass ratio of the copolymer particles to dimethyl sulfoxide is (2.5-3): (45-50), the mass ratio of sodium alginate to water is (5-6): (50-60), the mass ratio of calcium chloride to water in the calcium chloride aqueous solution is (2-3): (10-15), and the addition amount is 15-16 wt%.

6. An extruded board according to claim 1, characterized in that: In step S1, the temperature is controlled at 150-160° C., the temperature is increased to 210-220° C., and the vacuum degree is increased to <10 Pa.

7. An extruded board according to claim 1, characterized in that: In step S2, the shearing speed is 5000-6000 rpm, and the emulsification time is 10-15 min.

8. A method for preparing an extruded board according to any one of claims 1 to 7, characterized in that: The following steps are involved: A1. Dry the polystyrene resin and copolymer resin by weight at 80-85°C for 4-5 hours, add the dried polystyrene resin, copolymer resin, antioxidant, zinc stearate and calcium carbonate to a high-speed mixer, mix for 10-20 minutes until uniform, and feed into a twin-screw extruder for zone heating and extrusion. Inject a foaming agent during the extrusion process. A2. Rapidly cool to below 60°C through cooling rollers and shaping dies, perform corona treatment, and cut to obtain extruded boards.

9. The method for preparing an extruded board according to claim 8, characterized in that: In step A1, the L / D of the twin-screw extruder is 40:1, the screw diameter is 110-120 mm, the zone heating is specifically as follows: feeding section: 180-200 ° C, compression section: 200-220 ° C, melting section: 220-240 ° C, die section: 180-200 ° C, screw speed is 200-300 rpm, and extrusion speed is 1-2 m / min.

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