Fabric for airtight chemical protective clothing and application method of fabric

Abstract

The invention relates to the field of protective clothing fabrics, and particularly discloses a fabric for airtight chemical protective clothing and an application method of the fabric. Fabric for airtight chemical protective clothing sequentially comprises an outer surface layer, a middle blocking layer, a middle base cloth layer and an inner blocking layer from outside to inside, the middle blocking layer comprises a polyvinyl chloride layer, a polyethylene layer and a polypropylene layer, the middle base cloth layer is an aramid fiber base cloth layer, and the inner blocking layer comprises a polytetrafluoroethylene layer and a polypropylene layer; by means of the multi-layer structure, multiple protection is provided for the protective clothing, permeation of chemical substances is inhibited, and the barrier property and the corrosion resistance of the protective clothing are improved.

Description

Technical Field

[0001] The present application relates to the field of protective clothing fabrics, and in particular to an airtight chemical protective clothing fabric and an application method thereof. Background Art

[0002] Protective clothing, also known as chemical protection clothing, is a protective clothing worn to protect oneself from dangerous chemicals or corrosive substances. It can cover most of the human body and can effectively protect the torso, arms or thighs. In recent years, the demand for protective clothing in the fields of medical and health care, chemical production, microbiological laboratories, petroleum and petrochemicals, nuclear industry, emergency firefighting, etc. has been increasing.

[0003] Most of the existing chemical protective clothing uses imported materials and has the following defects: first, the protective clothing is bulky and inconvenient to carry and use; second, the material has poor chemical resistance and cannot meet the protection requirements well, especially in preventing the penetration of toxic and harmful gases; third, the rubber products used have poor aging resistance and are prone to aging and cracking, which greatly reduces the air tightness. Summary of the invention

[0004] In order to improve the deficiencies of existing protective clothing, the present application provides an airtight chemical protective clothing fabric and an application method thereof.

[0005] In the first aspect, the present application provides an airtight chemical protective clothing fabric, which adopts the following technical solution: The invention discloses an airtight chemical protective clothing fabric, which comprises an outer layer, an intermediate barrier layer, an intermediate base fabric layer and an inner barrier layer from the outside to the inside. The intermediate barrier layer comprises a polyvinyl chloride layer, a polyethylene layer and a polypropylene layer. The intermediate base fabric layer is an aramid base fabric layer. The inner barrier layer comprises a polytetrafluoroethylene layer and a polypropylene layer.

[0006] By adopting the above technical scheme, the outer layer can resist the contamination of chemical substances, the middle barrier layer is bonded to the outer layer, and can block the penetration of toxic gases. The middle barrier layer composed of polyvinyl chloride layer, polyethylene layer and polypropylene layer can block toxic and harmful gases and highly corrosive chemicals, and improve the barrier performance, corrosion resistance and flame retardant performance of the protective clothing. The middle base fabric layer is bonded to the middle barrier layer, and the skeleton support of the barrier material in the middle barrier layer can be utilized, and good mechanical strength, barrier effect and flame retardant performance can be provided. The inner barrier layer can prevent the middle barrier layer from being damaged, provide double protection for the protective clothing to prevent the penetration of chemical substances, and provide double safety for the wearer. The use of a multi-layer structure can improve the problem of poor single-layer chemical resistance of existing protective clothing, and use the inner barrier layer to solve the problem of easy aging and brittle cracking of protective clothing, providing double insurance for chemical protection clothing. The multi-layer composite maintains the overall light weight of the protective clothing at the same time, and realizes the lightweight of the equipment while ensuring the performance of use, and improves the safety and protective performance of the equipment.

[0007] Preferably, the aramid base fabric layer is an aramid base fabric, the aramid base fabric is one of woven fabric, knitted fabric and non-woven fabric, the thickness of the aramid base fabric is 0.1-0.3 mm, and the gram weight of the aramid base fabric is 50 g / m 2 -100g / m 2 .

[0008] By adopting the above technical solution, the aramid base fabric layer has the effects of wear resistance and tear resistance, and has certain flame retardant and corrosion resistance properties, thereby improving the resistance of the protective clothing to chemical substances.

[0009] Preferably, the thickness of the polyvinyl chloride layer is 50-500 μm, and the thickness of the polyethylene layer is 25-300 μm.

[0010] Preferably, the polypropylene layer is a polypropylene non-woven fabric, and the thickness of the polypropylene non-woven fabric is 25-300 μm; the polytetrafluoroethylene layer is a microporous membrane, and the thickness of the polytetrafluoroethylene layer is 10-500 μm.

[0011] By adopting the above technical solution, the microporous structure of the polytetrafluoroethylene microporous membrane is uniform and the pore size is small, which can effectively cut off the penetration of chemical liquids, thereby improving the barrier properties and chemical corrosion resistance of the protective clothing.

[0012] Preferably, the outer layer is silica gel, and the thickness of the outer layer is 50-500 μm.

[0013] Preferably, the viscosity of the silica gel is 20000-40000 mPa.s.

[0014] Preferably, the silica gel is pre-grafted with polymethyl methacrylate.

[0015] By adopting the above technical solution, the heat resistance and chemical stability of silica gel can be improved by pre-grafting polymethyl methacrylate with silica gel, and the barrier properties and chemical corrosion resistance of the protective clothing can be further improved.

[0016] Preferably, the polymethyl methacrylate raw material includes 3-mercaptopropyltrimethoxysilane and methyl methacrylate; the grafting method includes the following specific steps: mixing methyl methacrylate with a solvent, then adding 3-mercaptopropyltrimethoxysilane to mix, stirring evenly, heating to 65-75°C under the protection of nitrogen, adding an initiator, keeping the temperature to react, washing, filtering, and drying to obtain polymethyl methacrylate; mixing silica gel with toluene, then adding polymethyl methacrylate, heating to 90-100°C, filtering after reaction, and drying to obtain the grafted modified silica gel.

[0017] By adopting the above technical scheme, polymethyl methacrylate made from 3-mercaptopropyltrimethoxysilane and methyl methacrylate has good chemical stability, better stability and durability in chemical environment, can resist corrosion from a variety of chemical substances, and improve the barrier properties and chemical corrosion resistance of protective clothing.

[0018] In a second aspect, the present application provides an application method for airtight chemical protective clothing fabrics, using the following technical solution: An application method of airtight chemical protective clothing fabrics comprises the following specific steps: The two sides of the polyethylene layer are respectively compounded with the polypropylene layer and the polyvinyl chloride layer to form an intermediate barrier layer, and one side of the polypropylene layer in the intermediate barrier layer is hot-pressed and glued to the intermediate base fabric layer, the gluing temperature is 60-80°C, and the hot-pressing time is 3-15s; the polytetrafluoroethylene layer is hot-pressed and glued to the polypropylene layer, the gluing temperature is 60-120°C, and the hot-pressing time is 2-10s to form an inner barrier layer; one side of the polytetrafluoroethylene in the inner barrier layer is hot-pressed and glued to the intermediate base fabric layer, and then a silicone coating is coated on the surface of the polyvinyl chloride layer of the intermediate barrier layer to form an outer layer, so as to obtain an airtight chemical protective clothing fabric; The airtight chemical protective clothing fabric is sewn to form an integrated protective clothing, which includes a hood, a jumpsuit and boot covers.

[0019] By adopting the above technical solution and compounding the multi-layer structure, the penetration of chemical substances can be prevented while maintaining the overall light weight of the protective clothing, thereby providing the protective clothing with better barrier properties and chemical corrosion resistance.

[0020] Preferably, the seams of the one-piece protective clothing are hot-pressed with polyvinyl chloride strips, the hot-pressing temperature is 200-300° C., and the pressure is 0.2-0.6 MPa.

[0021] In summary, this application has the following beneficial effects: 1. Since the application adopts a multi-layer structure to enhance the protective performance of existing protective clothing, the middle barrier layer is combined with the outer layer, which can double resist the contamination of chemical substances and the penetration of toxic gases, and improve the barrier performance and corrosion resistance of protective clothing. The middle base fabric layer is bonded with the middle barrier layer, which can provide better strength and barrier performance for the protective clothing. The inner barrier layer can prevent the middle barrier layer from being damaged, providing double protection for the protective clothing to prevent the penetration of chemical substances, and providing double safety for the wearer.

[0022] 2. In this application, the protective silicone layer of vinyl silicone is used as the outermost layer of the protective clothing, which effectively resists the contamination of chemical substances and maintains good chemical corrosion resistance and durability. At the same time, the silicone resin is cross-linked with acrylic acid, butyl acrylate, and methyl methacrylate to improve the adhesion and film-forming effect of the silicone outer layer, and improve the barrier effect and durability of the protective clothing. DETAILED DESCRIPTION

[0023] The present application is further described in detail below with reference to the embodiments.

[0024] All raw materials in the examples are commercially available. Example

[0025] Example 1 This embodiment provides a barrier layer which comprises, from the outside to the inside, an outer layer, an intermediate barrier layer, an intermediate base fabric layer and an inner barrier layer, wherein the intermediate barrier layer comprises a polyvinyl chloride layer, a polyethylene layer and a polypropylene layer in sequence, the intermediate base fabric layer is an aramid base fabric layer, the aramid base fabric layer is an aramid base fabric, the aramid base fabric is a knitted fabric, the average thickness of the aramid base fabric is 0.2 mm, and the gram weight of the aramid is 80 g / m 2 The inner barrier layer includes a polytetrafluoroethylene layer and a polypropylene layer in sequence. The adhesive used in this embodiment is Henkel PUR7505 hot melt adhesive, the polypropylene layer is a polypropylene non-woven fabric, the polypropylene non-woven fabric is purchased from Yanshan Petrochemical, the average thickness of the polypropylene non-woven fabric is 200 μm, the polytetrafluoroethylene layer is a microporous membrane with a pore size of 0.3 μm, and the average thickness of the polytetrafluoroethylene layer is 250 μm.

[0026] This embodiment provides an application method of an airtight chemical protective clothing fabric, including the following specific steps: S1: Polyvinyl chloride and polyethylene are cast into films and compounded respectively, the CAS number of polyvinyl chloride is 25702-80-1, and the CAS number of polyethylene is 9002-88-4, to form a polyvinyl chloride layer with an average thickness of 250 μm and a polyethylene layer with an average thickness of 170 μm, and the polyethylene layer and the polypropylene layer are bonded by hot melt adhesive, the gluing temperature is 110°C, and the hot pressing time is 10s to form an intermediate barrier layer.

[0027] S2: Hot-press and glue one side of the polypropylene layer in the middle barrier layer to the middle base fabric layer at a gluing temperature of 80°C and a hot-pressing time of 10s; hot-press and glue the polytetrafluoroethylene layer to the polypropylene layer at a gluing temperature of 110°C and a hot-pressing time of 8s to form an inner barrier layer; hot-press and glue one side of the polytetrafluoroethylene in the inner barrier layer to the middle base fabric layer at a gluing temperature of 110°C and a hot-pressing time of 10s; then apply a layer of silicone coating on the surface of the polyvinyl chloride layer of the middle barrier layer; the silicone viscosity is 20,000 mPa.s; after heating and curing, an outer layer with an average thickness of 250 μm is formed to obtain an airtight chemical protective clothing fabric.

[0028] S3: The airtight chemical protective clothing fabrics prepared above are sewn to form an integrated protective clothing, which includes a hood, a jumpsuit and boot covers. Polyvinyl chloride strips are used for hot pressing and gluing at the seams. The hot pressing temperature is 250°C, the pressure is 0.4MPa, and the gluing speed is 3m / s to form polyvinyl chloride strips with a width of 17mm and a thickness of 130μm.

[0029] Example 2 Embodiment 2 provides an application method of an airtight chemical protective clothing fabric, comprising the following specific steps: S1: Polyvinyl chloride and polyethylene are cast into films and compounded respectively, the CAS number of polyvinyl chloride is 25702-80-1, and the CAS number of polyethylene is 9002-88-4, to form a polyvinyl chloride layer with an average thickness of 50 μm and a polyethylene layer with an average thickness of 300 μm, and the polyethylene layer and the polypropylene layer are bonded by hot melt adhesive, the gluing temperature is 110°C, and the hot pressing time is 10s to form an intermediate barrier layer.

[0030] S2: Hot-press and glue one side of the polypropylene layer in the middle barrier layer to the middle base fabric layer at a gluing temperature of 80°C and a hot-pressing time of 10s; hot-press and glue the polytetrafluoroethylene layer to the polypropylene layer at a gluing temperature of 110°C and a hot-pressing time of 8s to form an inner barrier layer; hot-press and glue one side of the polytetrafluoroethylene in the inner barrier layer to the middle base fabric layer at a gluing temperature of 110°C and a hot-pressing time of 10s; then apply a layer of silicone coating on the surface of the polyvinyl chloride layer of the middle barrier layer; the silicone viscosity is 20,000 mPa.s; after heating and curing, an outer layer with an average thickness of 250 μm is formed to obtain an airtight chemical protective clothing fabric.

[0031] S3: The airtight chemical protective clothing fabrics prepared above are sewn to form an integrated protective clothing, which includes a hood, a jumpsuit and boot covers. Polyvinyl chloride strips are used for hot pressing and gluing at the seams. The hot pressing temperature is 250°C, the pressure is 0.4MPa, and the gluing speed is 3m / s to form polyvinyl chloride strips with a width of 17mm and a thickness of 130μm.

[0032] Example 3 The difference between Example 3 and Example 1 is that the polytetrafluoroethylene layer is a microporous membrane with a pore size of 0.3 μm, the average thickness of the polytetrafluoroethylene layer is 10 μm, and the thickness of the polypropylene non-woven fabric in the polypropylene layer is 300 μm.

[0033] Example 4 The difference between Example 4 and Example 1 is that the polytetrafluoroethylene layer is a microporous membrane with a pore size of 0.3 μm, the average thickness of the polytetrafluoroethylene layer is 500 μm, and the thickness of the polypropylene non-woven fabric in the polypropylene layer is 25 μm.

[0034] Example 5 The difference between Example 5 and Example 1 is that the thickness of the outer layer is 50 μm.

[0035] Example 6 The difference between Example 6 and Example 1 is that the silica gel of the outer layer is pre-grafted with polymethyl methacrylate.

[0036] An application method of airtight chemical protective clothing fabrics comprises the following specific steps: S1: Polyvinyl chloride and polyethylene are cast into films and compounded respectively, the CAS number of polyvinyl chloride is 25702-80-1, and the CAS number of polyethylene is 9002-88-4, to form a polyvinyl chloride layer with an average thickness of 250 μm and a polyethylene layer with an average thickness of 170 μm, and the polyethylene layer and the polypropylene layer are bonded by hot melt adhesive, the gluing temperature is 110°C, and the hot pressing time is 10s to form an intermediate barrier layer.

[0037] S2: Hot-press and glue one side of the polypropylene layer in the middle barrier layer to the middle base fabric layer, the gluing temperature is 80°C, and the hot-pressing time is 10s; hot-press and glue the polytetrafluoroethylene layer to the polypropylene layer, the gluing temperature is 110°C, and the hot-pressing time is 8s to form an inner barrier layer, and hot-press and glue one side of the polytetrafluoroethylene in the inner barrier layer to the middle base fabric layer, the gluing temperature is 110°C, and the hot-pressing time is 10s.

[0038] S3: Mix silica gel and toluene, then add polymethyl methacrylate (CAS No. 9011-14-7), the mass ratio of silica gel, toluene and polymethyl methacrylate is 1:25:1.5, heat to 95°C, react for 3 days, filter and dry to obtain grafted modified silica gel; then apply a layer of silica gel coating on the surface of the polyvinyl chloride layer of the middle barrier layer, heat and cure to form an outer layer with an average thickness of 250μm, and obtain an airtight chemical protective clothing fabric.

[0039] S4: The airtight chemical protective clothing fabrics prepared above are sewn to form an integrated protective clothing, which includes a hood, a jumpsuit and boot covers. Polyvinyl chloride strips are used for hot pressing and gluing at the seams. The hot pressing temperature is 250°C, the pressure is 0.4MPa, and the gluing speed is 3m / s to form polyvinyl chloride strips with a width of 17mm and a thickness of 130μm.

[0040] Example 7 The difference between Example 7 and Example 6 is that the polymethyl methacrylate raw material includes 3-mercaptopropyltrimethoxysilane and methyl methacrylate.

[0041] An application method of airtight chemical protective clothing fabrics comprises the following specific steps: S1: Polyvinyl chloride and polyethylene are cast into films and compounded respectively, the CAS number of polyvinyl chloride is 25702-80-1, and the CAS number of polyethylene is 9002-88-4, to form a polyvinyl chloride layer with an average thickness of 250 μm and a polyethylene layer with an average thickness of 170 μm, and the polyethylene layer and the polypropylene layer are bonded by hot melt adhesive, the gluing temperature is 110°C, and the hot pressing time is 10s to form an intermediate barrier layer.

[0042] S2: Hot-press and glue one side of the polypropylene layer in the middle barrier layer to the middle base fabric layer, the gluing temperature is 80°C, and the hot-pressing time is 10s; hot-press and glue the polytetrafluoroethylene layer to the polypropylene layer, the gluing temperature is 110°C, and the hot-pressing time is 8s to form an inner barrier layer, and hot-press and glue one side of the polytetrafluoroethylene in the inner barrier layer to the middle base fabric layer, the gluing temperature is 110°C, and the hot-pressing time is 10s.

[0043] S3: After methyl methacrylate and solvent are mixed, the solvent is anhydrous ethanol, and then 3-mercaptopropyl trimethoxysilane is added to mix, the mass ratio of methyl methacrylate, solvent and 3-mercaptopropyl trimethoxysilane is 1:8:0.3, and stirred evenly. Under the protection of nitrogen, the temperature is raised to 70°C and the initiator is added. The mass ratio of initiator to methyl methacrylate is 0.01:1, and the initiator is azobisisobutyronitrile. The reaction is kept warm for 24 hours, and polymethyl methacrylate is obtained after washing, filtration and drying; silica gel is mixed with toluene, and then polymethyl methacrylate is added. The mass ratio of silica gel, toluene and polymethyl methacrylate is 1:25:1.5. The mixture is heated to 95°C, reacted for 3 days, and then filtered and dried to obtain the grafted silica gel. S4: A layer of silicone coating is then applied on the surface of the polyvinyl chloride layer of the middle barrier layer, and after heating and curing, an outer layer with an average thickness of 250 μm is formed to obtain an airtight chemical protective clothing fabric.

[0044] S5: The airtight chemical protective clothing fabrics prepared above are sewn to form an integrated protective clothing, which includes a hood, a jumpsuit and boot covers. Polyvinyl chloride strips are used for hot pressing and gluing at the seams. The hot pressing temperature is 250°C, the pressure is 0.4MPa, and the gluing speed is 3m / s to form polyvinyl chloride strips with a width of 17mm and a thickness of 130μm.

[0045] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that no intermediate barrier layer is used in the fabric material of the airtight chemical protective clothing.

[0046] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that no intermediate barrier layer and inner barrier layer are used in the fabric material of the airtight chemical protective clothing.

[0047] Performance testing The one-piece protective clothing made of the airtight chemical protective clothing fabrics provided in Examples 1-7 and Comparative Examples 1-2 of the present application weighed less than 4.1KG and was subjected to the following performance tests. The specific test results are shown in Table 1.

[0048] Detection Methods 1. Chemical resistance With reference to the standard of GB / T 23462-2009 "Test method for penetration of chemical substances in protective clothing", the anti-chemical penetration time of the one-piece protective clothing prepared in this application was tested at concentrations of 30%, 80%, and 600% sulfuric acid and 6.1 mol / L sodium hydroxide.

[0049] 2. Flame retardant properties The flame retardant properties of the one-piece protective clothing prepared in this application were tested with reference to the standard of GB / T 5455-1997 "Vertical method for testing the burning performance of textiles".

[0050] 3. High temperature aging resistance After placing the one-piece protective clothing sample prepared in the present application in an aging test chamber at 125°C for 24 hours, the appearance of the protective clothing was observed.

[0051] Table 1: Performance test results data table Table 1: Performance test results data table According to the performance test results, the protective clothing prepared in the present application can effectively inhibit the penetration of chemicals, and improve the chemical corrosion resistance, barrier properties and flame retardant effect of the protective clothing through multi-layer composite protection.

[0052] By comparing Comparative Examples 1-2 with Example 1, it can be seen that Comparative Example 1 does not use an intermediate barrier layer, and Comparative Example 2 does not use an intermediate barrier layer and an inner barrier layer. From the performance test results, it can be seen that the flame retardant effect of the protective clothing is significantly reduced, and the aging performance at high temperature is also reduced. Comparative Example 2 shows brittle cracking, which further illustrates that the use of an inner barrier layer, an intermediate barrier layer and an intermediate base fabric layer in combination can provide multiple protections for the protective clothing. Compared with traditional protection, the multi-layer protective clothing prepared in the present application has better barrier effect and anti-aging performance.

[0053] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An airtight chemical protective clothing fabric, characterized in that: From the outside to the inside, there are an outer layer, an intermediate barrier layer, an intermediate base fabric layer and an inner barrier layer. The intermediate barrier layer includes a polyvinyl chloride layer, a polyethylene layer and a polypropylene layer. The intermediate base fabric layer is an aramid base fabric layer. The inner barrier layer includes a polytetrafluoroethylene layer and a polypropylene layer.

2. The airtight chemical protective clothing fabric according to claim 1, characterized in that: The aramid base fabric layer is an aramid base fabric, which is one of woven fabric, knitted fabric and non-woven fabric. The thickness of the aramid base fabric is 0.1-0.3 mm, and the gram weight of the aramid base fabric is 50 g / m 2 -100g / m 2 .

3. The airtight chemical protective clothing fabric according to claim 1, characterized in that: The thickness of the polyvinyl chloride layer is 50-500 μm, and the thickness of the polyethylene layer is 25-300 μm.

4. The airtight chemical protective clothing fabric according to claim 1, characterized in that: The polypropylene layer is a polypropylene non-woven fabric, and the thickness of the polypropylene non-woven fabric is 25-300 μm; the polytetrafluoroethylene layer is a microporous membrane, and the thickness of the polytetrafluoroethylene layer is 10-500 μm.

5. The airtight chemical protective clothing fabric according to claim 1, characterized in that: The outer layer is silica gel, and the thickness of the outer layer is 50-500 μm.

6. The airtight chemical protective clothing fabric according to claim 1, characterized in that: The viscosity of the silica gel is 20000-40000 mPa.s.

7. The airtight chemical protective clothing fabric according to claim 6, characterized in that: The silica gel is pre-grafted with polymethyl methacrylate.

8. The airtight chemical protective clothing fabric according to claim 7, characterized in that: The polymethyl methacrylate raw material comprises 3-mercaptopropyltrimethoxysilane and methyl methacrylate; the grafting method comprises the following specific steps: mixing methyl methacrylate with a solvent, then adding 3-mercaptopropyltrimethoxysilane to mix, stirring evenly, heating to 65-75°C under the protection of nitrogen, adding an initiator, keeping the temperature for reaction, washing, filtering and drying to obtain polymethyl methacrylate; mixing silica gel with toluene, then adding polymethyl methacrylate, heating to 90-100°C, filtering after reaction and drying to obtain grafted modified silica gel.

9. A method for applying the airtight chemical protective clothing fabric according to any one of claims 1 to 6, characterized in that: The specific steps include: The two sides of the polyethylene layer are respectively compounded with the polypropylene layer and the polyvinyl chloride layer to form an intermediate barrier layer, and one side of the polypropylene layer in the intermediate barrier layer is hot-pressed and glued to the intermediate base fabric layer, the gluing temperature is 60-80°C, and the hot-pressing time is 3-15s; the polytetrafluoroethylene layer is hot-pressed and glued to the polypropylene layer, the gluing temperature is 60-120°C, and the hot-pressing time is 2-10s to form an inner barrier layer; one side of the polytetrafluoroethylene in the inner barrier layer is hot-pressed and glued to the intermediate base fabric layer, and then a silicone coating is coated on the surface of the polyvinyl chloride layer of the intermediate barrier layer to form an outer layer, so as to obtain an airtight chemical protective clothing fabric; The airtight chemical protective clothing fabric is sewn to form an integrated protective clothing, which includes a hood, a jumpsuit and boot covers.

10. The method for applying the airtight chemical protective clothing fabric according to claim 9, characterized in that: The seams of the one-piece protective clothing are hot-pressed with polyvinyl chloride adhesive strips, the hot-pressing temperature is 200-300° C., and the pressure is 0.2-0.6 MPa.

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