Disposable degradable sealed antibacterial meal box

Abstract

The invention discloses a disposable degradable sealed antibacterial meal box, which is prepared from the following ingredients in parts by mass: 40 to 90 parts of PBS (Polybutylene Succinate), 10 to 50 parts of PLA (Polylactic Acid), 1 to 20 parts of reed powder, 1 to 20 parts of antibacterial agents, 0.1 to 2 parts of plasticizers, 1 to 2 parts of coupling agents and 0.1 to 2 parts of antioxidants. The sealing structure of the lunch box comprises a lower clamping edge and an upper clamping edge which are arranged on the inner wall of the upper end of the lunch box body, the degradation and antibacterial effects are combined, a PBS / PLA composite base material serves as a core, reed powder is combined to enhance the degradability, a natural antibacterial agent is introduced to form a hydrogen bond slow release knot, and the degradation rate is increased.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of meal boxes, and particularly relates to a disposable degradable sealed antibacterial meal box. BACKGROUND

[0002] The degradable tableware refers to tableware which can be subjected to biochemical reactions under the action of microorganisms (bacteria, mold, algae) and enzymes in the natural environment, causes appearance mildew to internal quality change, and finally forms carbon dioxide and water.

[0003] The degradable meal box in the prior art has the problems of poor sealing performance, internal food and beverage spilling due to shaking during meal delivery and takeout, and low degradation rate after meal, which greatly affects the environment.

[0004] Therefore, a disposable degradable sealed antibacterial meal box is needed to solve the above problems. SUMMARY

[0005] The application aims to provide a disposable degradable sealed antibacterial meal box to solve the above problems in the prior art.

[0006] In order to achieve the above purpose, the application provides the following technical scheme: The disposable degradable sealed antibacterial meal box comprises the following components and mass fractions: polybutylene succinate PBS 40-90 parts, polylactic acid PLA 10-50 parts, reed powder 1-20 parts, antibacterial agent 1-20 parts, plasticizer 0.1-2 parts, coupling agent 1-2 parts, and antioxidant 0.1-2 parts. Figure 3 The sealing structure of the meal box comprises a lower clamping rib and an upper clamping rib arranged on the inner wall of the upper end of the meal box body, and a flexible leakage-proof plate clamped between the two, and a fixed pull ring on the upper end of the flexible leakage-proof plate. The degradation performance of the meal box satisfies the following formula: Wherein, D is the degradation rate (%) within 180 days, k is the degradation rate constant (0.15-0.25), SPBS is the PBS crystallinity (30-60%), T is the environmental temperature (20-50℃), MPLA is the PLA molecular weight

[0007] Preferably, the mass ratio of the PBS to the PLA is 3-6:1, the PBS density is 1.26 g / cm³, the PBS crystallinity ranges from 30% to 60%, the PLA is one of levorotatory polylactic acid, dextrorotatory polylactic acid or racemic polylactic acid, and the density of the PLA is 1.26 g / cm³; the PLA molecular weight is , the PBS crystallinity is 45%, and the heat resistance of the meal box is improved synergistically.

[0008] Preferably, the reed powder has a particle size of 300-500 mesh and is surface-modified by a silane coupling agent KH-570; the treatment process comprises: placing dry reed powder and the coupling agent in a high-speed mixer at a mass ratio of 100:1, and mixing at a speed of 1000 rpm for 5 minutes, so that the interfacial bonding strength of the reed powder and the PBS / PLA matrix is increased by ≥40%, and the degradation rate coefficient is optimized to 0.08.

[0009] Preferably, the antibacterial agent is one of vanillin, piroctone olamine or zinc pyrithione, and the addition amount is 5-15 parts; wherein the vanillin forms a hydrogen bond complex structure with the PLA, and a slow-release film is formed on the surface of the meal box, so that the release rate of the antibacterial agent satisfies the first-order kinetics equation , Ct is the surface concentration at time t, C0 is the initial concentration, and the sustained antibacterial rate is ≥99%.

[0010] Preferably, the sealing structure satisfies: the flexible leakage-proof plate is made of a degradable starch-based composite material, has a thickness of 0.5-1 mm, and has an edge embedded in a wedge-shaped groove formed by the upper and lower clamping lugs (2), and the groove depth is 1.5 times the thickness of the plate; the inner side of the sealing surrounding ring is provided with a first clamping groove (10) matched with the arc-shaped outer wall of the clamping outer edge plate, and the sealing pressure after clamping is ≥0.2 MPa, and the leakage-proof plate can withstand a 5 kPa liquid level fluctuation.

[0011] Preferably, a detachable first filter screen (241) is additionally arranged in the placing groove of the meal box body, the filter screen has a pore size of 0.5-1 mm, is formed by 3D printing of a PLA / reed powder composite material, and is used for filtering food material soup and reducing the oil adsorption amount by 30%.

[0012] Preferably, a plant fiber reinforced layer is further arranged on the inner wall of the meal box body, is formed by hot pressing of plant fibers (30 parts), antibacterial polypeptides (5 parts) and a mixture of locust bean gum and guar gum (10 parts), and has a thickness of 50-100 μm, so that the tensile strength of the meal box is increased to 25 MPa.

[0013] Preferably, a water absorption structure (202) is integrated in the box cover, and comprises a slidingly installed water absorption plate (204) and a second filter screen (203); the water absorption plate (204) is filled with diatomite wrapped with non-woven fabric, and has a humidity adsorption capacity of 0.5 g / g, so that the condensed water in the meal box can be reduced by 90%.

[0014] Preferably, the degradation formula parameters are defined as: ambient temperature T=37℃, degradation rate constant k=0.2, reed powder filling coefficient α=0.08, reed powder mesh number Rfiber=400 mesh, and the degradation rate D of the meal box in the soil is ≥90% after 180 days.

[0015] Preferably, the preparation process comprises: vacuum drying PBS, PLA and reed powder for 24-48 hours at a temperature of 60-80℃, high-speed mixing with surface-treated reed powder, antibacterial agent, plasticizer and antioxidant; melt blending through a double-screw extruder at a temperature of 160-175℃, and granulation; after injection molding of the meal box body, embedding a flexible leakage-proof plate and a sealing surrounding ring through hot pressing at a hot pressing temperature of 100-120℃ and a pressure of 8-12 MPa.

[0016] In the above technical solution, the disposable degradable sealed antibacterial meal box provided by the application has the following beneficial effects: Compared with the prior art, the application has the following outstanding advantages: (1) By combining degradation and antibacterial effects in one, taking PBS / PLA composite substrate as the core, combining reed powder to enhance degradability, and introducing natural antibacterial agent (such as vanillin) to form a hydrogen bond slow-release knot, the degradation rate is improved; The wedge-shaped groove and the arc-shaped clamping groove sealing design is adopted, the wedge-shaped groove formed by the lower clamping ridge and the upper clamping ridge of the meal box body is embedded with the flexible leakage-proof plate, and the sealing surrounding ring and the arc-shaped outer wall clamping groove of the box cover are combined to realize multi-layer nested sealing, thereby reducing the industry pain point that the degradable meal box is prone to leakage during meal delivery; (3) The double-stage hot pressing embedding sealing structure is adopted to avoid damage to the activity of the degradable material at high temperature, and the interface bonding strength is improved through silane coupling treatment of the reed powder, so that the production efficiency and performance stability are considered. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0018] Figure 1 The three-dimensional schematic view provided for the disposable degradable sealed antibacterial meal box embodiment of the present application.

[0019] Figure 2 The box cover schematic view provided for the disposable degradable sealed antibacterial meal box embodiment of the present application.

[0020] Figure 3 The formula schematic view provided for the disposable degradable sealed antibacterial meal box embodiment of the present application.

[0021] 1 meal box body, 2 lower clamping, 202 water absorption structure, 203 second filter screen, 204 water absorption plate, 241 first filter screen, 3 upper clamping, 4 leakage prevention plate, 5 pull ring, 6 outer edge plate, 7 box cover, 8 sealing surrounding ring, 10 first clamping groove. DETAILED DESCRIPTION

[0022] In order to make the technical personnel in the art better understand the technical solutions of the present application, the present application will be further described in detail below with reference to the drawings.

[0023] As Figures 1-3 shown, the disposable degradable sealed antibacterial meal box provided by the embodiment of the present application comprises the following components and mass fractions: polybutylene succinate PBS 40-90 parts, polylactic acid PLA 10-50 parts, reed powder 1-20 parts, antibacterial agent 1-20 parts, plasticizer 0.1-2 parts, coupling agent 1-2 parts, and antioxidant 0.1-2 parts; the sealing structure of the meal box comprises a lower clamping 2 and an upper clamping 3 arranged on the inner wall of the upper end of a meal box body 1, and a flexible leakage prevention plate 4 clamped therebetween, the upper end of the flexible leakage prevention plate 4 is fixed with a pull ring 5, the upper end of the meal box body 1 is provided with a clamped outer edge plate 6, and a box cover 7 is connected with the clamped outer edge plate 6 through a sealing surrounding ring 8; the degradation performance of the meal box satisfies the following formula, as Figure 3 shown; wherein D is the degradation rate % within 180 days, k is the degradation rate constant with a value of 0.15-0.25, SPBS is the PBS crystallinity of 30-60%, T is the environmental temperature of 20-50℃, MPLA is the PLA molecular weight of 10 4 -10 5 g / mol, and alpha is the reed powder filling coefficient of 0.05-0.1, and Rfiber is the reed powder mesh of 300-500 mesh.

[0024] The present application combines the degradation and antibacterial effects in one by taking PBS / PLA composite substrate as the core, enhances the degradation by combining with reed powder, and introduces natural antibacterial agent (such as vanillin) to form hydrogen bond slow-release knot and improve the degradation rate; the wedge-shaped groove and arc-shaped clamping groove sealing design is adopted, the wedge-shaped groove formed by the lower clamping and the upper clamping of the meal box body is embedded with the flexible leakage prevention plate, and the sealing surrounding ring of the box cover is combined with the arc-shaped outer wall clamping groove to realize multi-layer nested sealing and reduce the industry pain point that the degradable meal box is easy to leak during meal delivery. In the embodiment provided by the present application, the mass ratio of PBS to PLA is 3-6:1, the density of PBS is 1.26 g / cm³, the crystallinity range is 30-60%, PLA is one of levorotatory polylactic acid, dextrorotatory polylactic acid or racemic polylactic acid, and the density is 1.26 g / cm³; the PLA molecular weight is 8 x 10 4 g / mol, and the PBS crystallinity is 45%, so as to synergistically improve the heat resistance of the meal box.

[0025] In the embodiment provided by the application, the reed powder has a particle size of 300-500 meshes and is subjected to surface modification treatment by a silane coupling agent KH-570; the treatment process comprises: placing dry reed powder and the coupling agent in a high-speed mixer at a mass ratio of 100:1, and mixing at a speed of 1000 rpm for 5 minutes, so that the interfacial bonding strength of the reed powder and the PBS / PLA matrix is increased by 40% or more, and the degradation rate coefficient is optimized to 0.08.

[0026] In the embodiment provided by the application, the antibacterial agent is one of vanillin, piroctone olamine or zinc pyrithione, and the addition amount is 5-15 parts; wherein the vanillin forms a hydrogen bond complex structure with PLA, and a slow-release film is formed on the surface of the meal box, so that the release rate of the antibacterial agent satisfies the first-order kinetics equation Ct=C0·e−0.05t, Ct is the surface concentration at time t, C0 is the initial concentration, and the sustained antibacterial rate is 99% or more.

[0027] In the embodiment provided by the application, the sealing structure satisfies that the flexible leakage-proof plate 4 is made of degradable starch-based composite material, the thickness is 0.5-1 mm, the edge is embedded in the wedge-shaped groove formed by the upper clamping ledge 3 and the lower clamping ledge 2, and the groove depth is 1.5 times the thickness of the plate; the inner side of the sealing surrounding ring 8 is provided with a first clamping groove 10 matched with the arc outer wall of the clamping outer edge plate 6, the sealing pressure after clamping is 0.2 MPa or more, and the leakage-proof plate can withstand 5 kPa liquid level fluctuation.

[0028] In the embodiment provided by the application, a detachable first filter screen 241 is additionally arranged in the placing groove of the meal box body 1, the filter screen has a pore size of 0.5-1 mm, is formed by 3D printing of PLA / reed powder composite material, and is used for filtering food material soup and reducing oil adsorption by 30%.

[0029] In the embodiment provided by the application, a plant fiber reinforced layer is further arranged on the inner wall of the meal box body 1, is formed by hot pressing of 30 parts of plant fiber, 5 parts of antibacterial polypeptide and 10 parts of mixed glue of sesbania gum and guar gum, and has a thickness of 50-100 μm, so that the tensile strength of the meal box is increased to 25 MPa.

[0030] In the embodiment provided by the application, a water absorption structure 202 is integrated in the box cover 7, and the water absorption structure 202 comprises a slidingly installed water absorption plate 204 and a second filter screen 203; the water absorption plate 204 is filled with diatomite wrapped by non-woven fabric, and has a humidity adsorption capacity of 0.5 g / g, so that 90% of the condensed water in the meal box can be reduced.

[0031] In the embodiment provided by the application, the degradation formula parameters are limited as follows: the environmental temperature T=37℃, the degradation rate constant k=0.2, the reed powder filling coefficient α=0.08, and the reed powder mesh number Rfiber=400 meshes, so that the degradation rate D of the meal box in the soil is 90% or more in 180 days.

[0032] The preparation process in the embodiment provided by the application comprises the following steps: PBS, PLA and reed powder are vacuum dried for 24-48 hours at a temperature of 60-80 DEG C, and then mixed with surface-treated reed powder, antibacterial agent, plasticizer and antioxidant at high speed; melt blending is performed through a double-screw extruder at a temperature of 160-175 DEG C, and then granulation is performed; after injection molding of the body of the meal box, the flexible leakage-proof plate 4 and the sealing surrounding ring 8 are embedded through hot pressing, and the hot pressing temperature is 100-120 DEG C and the pressure is 8-12 MPa.

[0033] The double-stage hot-pressing embedded sealing structure is adopted to avoid damage to the activity of the degradable material at high temperature, and the interface bonding strength is improved through silane coupling treatment of the reed powder, so that the production efficiency and performance stability are considered. Embodiment 1

[0034] The disposable degradable and antibacterial meal box comprises the following components and mass fractions: 40-90 parts of polybutylene succinate (PBS), 10-50 parts of polylactic acid (PLA), 1-20 parts of reed powder, 1-20 parts of antibacterial agent, 0.1-2 parts of plasticizer, 1-2 parts of coupling agent and 0.1-2 parts of antioxidant; the sealing structure of the meal box comprises a lower clamping rib 2 and an upper clamping rib 3 arranged on the inner wall of the upper end of the body of the meal box 1, and a flexible leakage-proof plate 4 clamped between the two; the upper end of the flexible leakage-proof plate 4 is fixed with a pull ring 5; a clamping outer edge plate 6 is arranged on the outer periphery of the upper end of the body of the meal box 1; and a box cover 7 is connected with the clamping outer edge plate 6 through a sealing surrounding ring 8; the degradation performance of the meal box satisfies the following formula, as shown in the formula: Figure 3 The application combines the degradation and antibacterial effects in one through PBS / PLA composite substrate as the core, enhances the degradation by reed powder, and introduces natural antibacterial agent (such as vanillin) to form a hydrogen bond slow-release knot to improve the degradation rate; the wedge-shaped groove and arc-shaped clamping groove sealing design is adopted, the wedge-shaped groove formed by the lower clamping rib and the upper clamping rib arranged on the body of the meal box is embedded with the flexible leakage-proof plate, and the sealing surrounding ring of the box cover is combined with the arc-shaped outer wall clamping groove to realize multi-layer nested sealing and reduce the industry pain point that the degradable meal box is easy to leak during the meal delivery process. Embodiment 2

[0035] The embodiment is further limited on the basis of embodiment 1, and in the embodiment provided by the application, the mass ratio of PBS to PLA is 3-6:1, the density of PBS is 1.26 g / cm3, the crystallinity range is 30-60%, the PLA is one of levorotatory polylactic acid, dextrorotatory polylactic acid or racemic polylactic acid, and the density is 1.26 g / cm3; the molecular weight of PLA is 8*10 4 ​The PBS / PLA composite material has a molecular weight of 100,000 g / mol, the PBS crystallinity is 45%, and the reed powder has a particle size of 300-500 mesh and is surface modified by a silane coupling agent KH-570, so as to synergistically improve the heat resistance of the meal box. The treatment process includes: placing the dried reed powder and the coupling agent in a high-speed mixer at a mass ratio of 100:1, mixing at a speed of 1000 rpm for 5 minutes, so that the interfacial bonding strength of the reed powder and the PBS / PLA matrix is increased by 40%, the degradation rate coefficient is optimized to 0.08, the antibacterial agent is one of vanillin, piroctone olamine or pyrithione zinc, and the addition amount is 5-15 parts; wherein the vanillin forms a hydrogen bond complex structure with the PLA, forming a slow-release film on the surface of the meal box, so that the release rate of the antibacterial agent satisfies the first-order kinetics equation Ct=C0·e−0.05t, Ct is the surface concentration at time t, C0 is the initial concentration, the sustained inhibition rate is ≥99%, the sealing structure satisfies: the flexible leakage-proof plate 4 is made of degradable starch-based composite material, the thickness is 0.5-1mm, the edge is embedded in the wedge-shaped groove formed by the upper and lower clamping 3 and 2, and the groove depth is 1.5 times the thickness of the plate; the inner side of the sealing surrounding ring 8 is provided with a first clamping groove 10 matched with the arc outer wall of the clamping outer edge plate 6, and the sealing pressure after clamping is ≥0.2MPa. The leakage-proof plate can withstand 5kPa liquid level fluctuation, a detachable first filter screen 241 is additionally arranged in the placing groove of the meal box body 1, the filter screen has a pore size of 0.5-1mm, is formed by 3D printing of PLA / reed powder composite material, is used for filtering food material soup and reducing oil adsorption amount by 30%, further includes a plant fiber reinforced layer, is located on the inner wall of the meal box body 1, is formed by hot pressing of plant fiber 30 parts, antibacterial polypeptide 5 parts and mixed glue of sesbania gum and guar gum 10 parts, and has a thickness of 50-100μm, so that the tensile strength of the meal box is increased to 25MPa, the lid 7 is integrated with a water absorption structure 202, including a slidingly installed water absorption plate 204 and a second filter screen 203, the water absorption plate 204 is filled with diatomite wrapped with non-woven fabric, and has a humidity adsorption capacity of 0.5g / g, so as to reduce the condensed water in the meal box by 90%, and the degradation formula parameters are limited as follows: environmental temperature T=37℃, degradation rate constant k=0.2, reed powder filling coefficient α=0.08, and reed powder mesh number Rfiber=400mesh, so that the degradation rate D of the meal box in the soil is ≥90% in 180 days, and the preparation process includes: vacuum drying PBS, PLA and reed powder for 24-48 hours at a temperature of 60-80℃, and high-speed mixing the surface-treated reed powder, the antibacterial agent, the plasticizer and the antioxidant; melt blending by a double-screw extruder at a temperature of 160-175℃, and granulating; after injection molding of the meal box body, embedding the flexible leakage-proof plate 4 and the sealing surrounding ring 8 by hot pressing at a temperature of 100-120℃ and a pressure of 8-12MPa.

[0036] The double-step hot pressing embedding sealing structure is adopted to avoid damage to the activity of the degradable material at high temperature, and the interfacial bonding strength is improved by silane coupling treatment of the reed powder, so as to balance the production efficiency and performance stability.

[0037] Certain exemplary embodiments of the present application have been described above by way of illustration, and it is to be understood that certain modifications can be made without departing from the spirit and scope of the application as set forth in the claims. Accordingly, the above description and drawings are to be construed in an illustrative, and not a restrictive, sense.

Claims

1. A disposable, degradable, sealed, antibacterial meal box, characterized by, The meal box is made of the following components and mass parts: polybutylene succinate PBS 40-90 parts, polylactic acid PLA 10-50 parts, reed powder 1-20 parts, antibacterial agent 1-20 parts, plasticizer 0.1-2 parts, coupling agent 1-2 parts, and antioxidant 0.1-2 parts. ；； Wherein, D is the degradation rate in 180 days, k is the degradation rate constant, S is the content of PBS, T is the ambient temperature, M is the molecular weight of PLA, and R is the content of reed powder. PBS Wherein, D is the degradation rate in 180 days, k is the degradation rate constant, S is the content of PBS, T is the ambient temperature, M is the molecular weight of PLA, and R is the content of reed powder. PLA Wherein, D is the degradation rate in 180 days, k is the degradation rate constant, S is the content of PBS, T is the ambient temperature, M is the molecular weight of PLA, and R is the content of reed powder. Wherein, D is the degradation rate in 180 days, k is the degradation rate constant, S is the content of PBS, T is the ambient temperature, M is the molecular weight of PLA, and R is the content of reed powder. fiber Wherein 2. The disposable, degradable, sealed, antibacterial meal box according to claim 1, wherein, The mass ratio of the PBS to the PLA is 3-6:1, the PBS has a density of 1.26 g / cm3 and a crystallinity in a range of 30-60%, the PLA is one of levorotatory polylactic acid, dextrorotatory polylactic acid or racemic polylactic acid and has a density of 1.26 g / cm3; the PLA has a molecular weight of , and the PBS has a crystallinity of 45%, so that the heat resistance of the meal box is synergistically improved.

3. The disposable, degradable, sealed, antibacterial meal box according to claim 2, wherein, The reed powder has a particle size of 300-500 mesh and is surface-modified by a silane coupling agent KH-570; the treatment process includes: placing dry reed powder and the coupling agent in a high-speed mixer at a mass ratio of 100:1, and mixing at a speed of 1000 rpm for 5 minutes, so that the interfacial bonding strength of the reed powder and the PBS / PLA matrix is increased by ≥40%, and the degradation rate coefficient is optimized to 0.

08.

4. The disposable, degradable, sealed, antibacterial meal box according to claim 2, wherein, The antibacterial agent is one of vanillin, piroctone olamine or zinc pyrithione, and the addition amount is 5-15 parts; wherein vanillin forms a hydrogen bond complex structure with PLA, forms a slow-release film on the surface of the lunch box, and makes the release rate of the antibacterial agent meet the first-order kinetics equation , Ct is the surface concentration at time t, and C0 is the initial concentration.

5. The disposable, degradable, sealed, antibacterial meal box according to claim 3, wherein, The sealing structure satisfies that the flexible leakage-proof plate (4) is made of a degradable starch-based composite material, has a thickness of 0.5-1 mm, and its edges are embedded in wedge-shaped grooves formed by the upper and lower clamping blocks (2) and (3), and the groove depth is 1.5 times the thickness of the plate; the inner side of the sealing surrounding ring (8) is provided with a first clamping groove (10) matched with the arc-shaped outer wall of the clamping outer edge plate (6).

6. The disposable, degradable, sealed, antibacterial meal box according to claim 1, wherein, A first filter screen (241) is additionally arranged in the placing groove of the meal box body (1).

7. The disposable, degradable, sealed, antibacterial meal box according to claim 1, wherein, A plant fiber reinforced layer is further arranged in the inner wall of the meal box body (1) and is formed by hot pressing of plant fibers (30 parts), an antibacterial polypeptide (5 parts), and a mixed glue of sesbania gum and guar gum (10 parts), and has a thickness of 50-100 μm.

8. The disposable, degradable, sealed, antibacterial meal box according to claim 1, wherein, The box cover (7) is integrated with a water absorption structure (202) including a slidingly mounted water absorption plate (204) and a second filter screen (203), and the water absorption plate (204) is filled with diatomite covered by non-woven fabric.

9. The disposable, degradable, sealed, antibacterial meal box according to claim 1, wherein, The degradation formula parameters are limited as follows: environmental temperature T=37℃, degradation rate constant k=0.2, reed powder filling coefficient α=0.08, and reed powder mesh number Rfiber=400 mesh.

10. The disposable, degradable, sealed, antibacterial meal box according to claim 1, wherein, The preparation process includes: vacuum drying PBS, PLA, and reed powder for 24-48 hours at a temperature of 60-80℃, and high-speed mixing the PBS, PLA, reed powder, antibacterial agent, plasticizer, and antioxidant; melt blending by a double-screw extruder at a temperature of 160-175℃, and pelletizing; after injection molding of the meal box body, embedding the flexible leakage-proof plate (4) and the sealing surrounding ring (8) by hot pressing at a temperature of 100-120℃ and a pressure of 8-12 MPa.

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