Polyphenylene sulfide composite material for capacitor housing and method for preparing the same

Abstract

The application provides a polyphenylene sulfide composite material for a capacitor shell and a preparation method thereof, and comprises the following raw materials in parts by weight: 100 parts of polyphenylene sulfide, 10-20 parts of bisphenol A type solid epoxy resin, 5-8 parts of a toughening agent, and 60-100 parts of a phenyl silane coupling agent modified filler; the toughening agent is a side chain type epoxy polysiloxane with an epoxy group on a side chain, is prepared by a silicon hydrogen addition reaction of methyl hydrogen-containing silicone oil and allyl glycidyl ether, has an epoxy value of 0.15-0.25, and has a viscosity of 50-120 mpa.s at 25 DEG C. The side chain type epoxy polysiloxane with high heat resistance is used as the toughening agent, the problem of poor high-temperature durability and significant strength reduction of conventional toughening agents is solved, and the polyphenylene sulfide composite material for the capacitor shell which has high-temperature durability, good bonding performance with epoxy pouring sealant and excellent toughness is obtained by using the phenyl silane coupling agent modified filler and the bisphenol A type solid epoxy resin together.

Description

Technical Field

[0001] This invention belongs to the technical field of polyphenylene sulfide composite materials, specifically relating to a polyphenylene sulfide composite material for capacitor casings and its preparation method. Background Technology

[0002] Polyphenylene sulfide (PPS) is a rigid main-chain polymer composed of benzene rings and sulfur atoms. It is crystalline and has excellent mechanical properties, as well as excellent flame retardancy, insulation resistance, thermal stability and chemical corrosion resistance. It is widely used in environmental protection, automotive, electronics, machinery, aerospace and other fields.

[0003] In recent years, the development of high-reliability, high-temperature-resistant organic film capacitors has been rapid, requiring small size, the ability to withstand high frequencies and ambient temperatures, and low distributed inductance. PPS film capacitors possess many superior properties compared to other dielectric capacitors, such as PP, PC, and PET capacitors, in terms of electrical, physical, and chemical properties. These are primarily manifested in their high temperature resistance, low loss tangent, good insulation resistance, and high breakdown field strength. In particular, the temperature and frequency characteristics of PPS film are superior to those of general dielectric film capacitors. Polyphenylene sulfide (PPS) film capacitors are gradually becoming the preferred product in the field of high-temperature, high-stability, and high-precision organic capacitors, especially in high-reliability aerospace systems.

[0004] While PPS film capacitors offer numerous advantages, they also suffer from drawbacks such as poor adhesion to the epoxy potting compound. Researchers have conducted extensive studies to address these issues. For example, patent CN114085526B discloses a polyphenylene sulfide composition, its preparation method, and its application. This polyphenylene sulfide composition comprises: 25-70 parts polyphenylene sulfide; 20-55 parts glass fiber; 5-40 parts filler; 0.1-1 part nucleating agent; 0.5-5 parts epoxy modifier; and 2-6 parts toughening agent; wherein the weight ratio of glass fiber to filler is ≥0.7. Patent CN116218217B discloses a polyphenylene sulfide (PPS) composite material for capacitor encapsulation and its preparation method. This PPS composite material comprises the following components by weight percentage: 30%-40% polyphenylene sulfide resin with a mass flow rate of 200-350 g / 10 min; 35%-45% alkali-free short glass fibers; 10%-20% calcium carbonate; 3%-6% bisphenol A type solid epoxy resin; 1%-3% ethylene-methyl acrylate-glycidyl methacrylate terpolymer toughening agent; 0%-2% color masterbatch; 0-0.5% lubricant; and 0.1%-0.5% coupling agent.

[0005] The above technology employs the method of doping epoxy resin into polyphenylene sulfide (PPS) composite materials, which can improve the bonding strength of PPS composite materials to epoxy potting compounds. However, because PPS itself lacks sufficient toughness, the addition of rigid epoxy resin will further reduce toughness, making the film product prone to breakage during the winding process. Therefore, it is necessary to use toughening agents such as ethylene-methyl acrylate-glycidyl methacrylate terpolymer, nitrile rubber, cis-butadiene rubber, and styrene-ethylene / butene-styrene block copolymer. In particular, the use of ethylene-methyl acrylate-glycidyl methacrylate terpolymer can also improve the dispersibility and compatibility of epoxy resin in the composite material. However, since PPS film capacitors are often used in high-temperature applications such as automotive engine compartments, high-temperature motor drives, high-temperature sensors, power frequency converters, and power inverters, where temperatures reach 100-125°C, the toughening agents soften or even degrade under continuous operation at these high temperatures, causing stress concentration, significantly reducing the strength of the film, and even causing cracking.

[0006] Therefore, it is necessary to develop a polyphenylene sulfide composite material for capacitor housings that has high-temperature durability, good adhesion to epoxy potting compounds, and excellent toughness, in order to improve the overall stability and reliability of capacitors. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a polyphenylene sulfide composite material for capacitor casings and its preparation method. It employs a side-chain epoxy polysiloxane with high heat resistance as a toughening agent, solving the problems of poor high-temperature durability and significant strength reduction associated with conventional toughening agents. Furthermore, it is used in conjunction with a phenylsilane coupling agent-modified filler and bisphenol A type solid epoxy resin to obtain a polyphenylene sulfide composite material for capacitor casings that combines high-temperature durability, good adhesion to epoxy potting compounds, and excellent toughness.

[0008] To achieve the above objectives, the following technical solution is adopted:

[0009] A polyphenylene sulfide composite material for capacitor casings comprises the following raw materials in parts by weight: 100 parts polyphenylene sulfide, 10-20 parts bisphenol A type solid epoxy resin, 5-8 parts toughening agent, and 60-100 parts phenylsilane coupling agent modified filler. The toughening agent is a side-chain type epoxy polysiloxane with epoxy groups on its side chain, which is prepared by hydrosilylation reaction of methyl hydrogen silicone oil and allyl glycidyl ether. The epoxy value is 0.15-0.25, and the viscosity at 25°C is 50-120 mPa·s.

[0010] The phenylsilane coupling agent modified filler is composed of a mixture of phenylsilane coupling agent modified granular inorganic filler and phenylsilane coupling agent modified rod-shaped inorganic filler in a mass ratio of 1:1-1.5. Using granular and rod-shaped phenylsilane coupling agent modified fillers with appropriate particle size and distribution can increase the contact area between the filler and the matrix, thereby enhancing interfacial bonding and further improving the toughness of the material.

[0011] The rod-shaped inorganic filler has an average diameter of 1-20 μm and an aspect ratio of 5-20. It is selected from one or more combinations of glass fiber, insulating potassium titanate whiskers, and basalt fiber, with glass fiber being preferred.

[0012] The granular inorganic filler has an average particle size of 0.1-10μm and is selected from one or more of the following: mica, diatomaceous earth, silica lime, talc, montmorillonite, kaolin, silica, glass microspheres, calcium carbonate, barium sulfate, and titanium dioxide.

[0013] The phenylsilane coupling agent is selected from one or a combination of two or more of 3-phenylpropylmethyldimethoxysilane, 4-phenylbutyltrimethoxysilane, triethoxy(2-phenylpropyl)silane, trimethoxy(2-phenylethyl)silane, 3-phenylpropyldimethylmethoxysilane, and methyldi(ethoxy)(2-phenylpropyl)silane.

[0014] This invention uses a side-chain epoxy polysiloxane with high heat resistance as a toughening agent, which solves the problems of poor high-temperature durability and significant strength reduction of conventional toughening agents. However, it was also found that the bonding performance between the composite material and the epoxy potting compound was not improved by the side-chain epoxy polysiloxane. To address this, the inventors modified inorganic fillers such as glass fiber by using a phenylsilane coupling agent, which successfully solved the bonding performance problem.

[0015] It is speculated that the side-chain epoxy polysiloxane has a larger bond energy, bond length, and bond angle of silicon-oxygen bonds, resulting in higher flexibility. Its molecular chain is easier to bend and deform than that of toughening agents such as ethylene-methyl acrylate-glycidyl methacrylate terpolymer, nitrile rubber, cis-butadiene rubber, and styrene-ethylene / butene-styrene block copolymer. When the composite material system contains a large amount of inorganic fillers such as glass fibers, the side-chain epoxy polysiloxane is concentrated and dispersed around the surface polar glass fibers and other inorganic fillers, which in turn affects the dispersibility of the epoxy resin. The surface polar groups of the glass fibers and other inorganic fillers after the phenylsilane coupling agent surface modification are reduced, and the compatibility with the side-chain epoxy polysiloxane is improved.

[0016] There are no particular limitations on the preparation method of the phenylsilane coupling agent modified filler; any method commonly used in the field is acceptable. Specifically, it can be as follows: prepare a treatment solution of phenylsilane coupling agent and water, add inorganic filler, heat to carry out the reaction, filter, wash, and dry after the reaction to obtain phenylsilane coupling agent modified inorganic filler.

[0017] The concentration of phenylsilane coupling agent in the treatment solution is 1-3 wt%, the mass ratio of inorganic filler to treatment solution is 1:10-12, the temperature is raised to 60-80℃, the reaction time is 1-3 h, and the washing is performed with ethanol 1-3 times.

[0018] The epoxy equivalent of the bisphenol A type solid epoxy resin is 2000-4000 g / eq.

[0019] The polyphenylene sulfide has a weight-average molecular weight of 40,000 to 60,000

[0020] The present invention also provides a method for preparing the above-mentioned polyphenylene sulfide composite material for capacitor casing, comprising the following steps:

[0021] Polyphenylene sulfide, bisphenol A type solid epoxy resin, toughening agent, phenylsilane coupling agent modified filler are mixed evenly, then extruded and granulated, cooled and dried to obtain polyphenylene sulfide composite material for capacitor shells.

[0022] The extrusion granulation conditions are as follows: Zone 11 temperatures: 230-150℃, 250-260℃, 260-270℃, 270-280℃, 280-290℃, 290-300℃, 300-310℃, 300-310℃, 300-310℃, 300-310℃, 300-310℃; Die temperature: 310-320℃; Screw diameter: 30-65mm; L / D ratio: 25-42:1; Screw speed: 250-350rpm.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] This invention uses a side-chain epoxy polysiloxane with high heat resistance as a toughening agent to solve the problems of poor high-temperature durability and significant strength reduction of conventional toughening agents. At the same time, it is used in combination with phenylsilane coupling agent modified filler and bisphenol A type solid epoxy resin to obtain a polyphenylene sulfide composite material for capacitor shells that has high-temperature durability, good adhesion to epoxy potting compound and excellent toughness. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, all "parts" mentioned in the embodiments of the present invention are parts by weight. All reagents used are commercially available in the art.

[0026] The linear polyphenylene sulfide was purchased from Jiangxi Juzhen Technology Development Co., Ltd., with a weight-average molecular weight of 56,000.

[0027] The chopped alkali-free glass fiber was purchased from Xuan Yue Technology New Materials Co., Ltd., with an average diameter of 11 micrometers and a length of 0.15 mm.

[0028] The ultrafine talc powder was purchased from Qingdao Shengyida Talc Powder Co., Ltd., with an average particle size of 1000 mesh.

[0029] The side-chain epoxy polysiloxanes were purchased from Anhui Aiyota Silicon Oil Co., Ltd. IOTA105-2-0.15 has an epoxy value of 0.15 and a viscosity of 61.5 MPa; IOTA105-2-0.25 has an epoxy value of 0.25 and a viscosity of 92.1 MPa.

[0030] E-03 type bisphenol A solid epoxy resin was purchased from Dow Chemical, with an epoxy equivalent of 3300 g / eq.

[0031] Example 1

[0032] 1) Mix trimethoxy(2-phenylethyl)silane and water evenly to prepare treatment solution I with a concentration of 3wt%. Add 100g of ultrafine talc powder to 1kg of treatment solution I, heat to 80℃ and react for 3h. After the reaction is completed, filter, wash 3 times with ethanol, and dry at 100℃ to constant weight to obtain phenylsilane coupling agent modified ultrafine talc powder.

[0033] 2) Trimethoxy(2-phenylethyl)silane and water were mixed evenly to prepare treatment solution II with a concentration of 1wt%. 100g of chopped alkali-free glass fiber was added to 1.2kg of treatment solution II. The mixture was heated to 80℃ and reacted for 2h. After the reaction was completed, the mixture was filtered, washed three times with ethanol, and dried at 100℃ to constant weight to obtain phenylsilane coupling agent modified chopped alkali-free glass fiber.

[0034] 3) Mix 100g of polyphenylene sulfide, 20g of E-03 bisphenol A type solid epoxy resin, 8g of side-chain epoxy polysiloxane IOTA105-2-0.15, 50g of phenylsilane coupling agent modified ultrafine talc powder obtained in step 1), and 50g of phenylsilane coupling agent modified short chopped alkali-free glass fiber obtained in step 2) evenly in a high-speed mixer, then extrude and granulate, cool and dry to obtain polyphenylene sulfide composite material for capacitor shells;

[0035] The extrusion granulation conditions are as follows: zone 1-11 temperatures: 245℃, 255℃, 265℃, 275℃, 285℃, 295℃, 300℃, 300℃, 300℃, 300℃, 300℃; die head temperature: 310℃; screw diameter: 65mm; length-to-diameter ratio: 40:1; screw speed: 350rpm.

[0036] Example 2

[0037] The rest is the same as in Example 1, except that the amount of side-chain epoxy polysiloxane IOTA105-2-0.15 used in step 3) is 5g.

[0038] Example 3

[0039] The rest is the same as in Example 1, except that in step 1), 3-phenylpropylmethyldimethoxysilane is used instead of trimethoxy(2-phenylethyl)silane.

[0040] Example 4

[0041] 1) Prepare a treatment solution with a concentration of 1 wt% for 1.2 kg of trimethoxy(2-phenylethyl)silane and water, add 100 g of ultrafine talc powder, heat to 80 °C and react for 3 h. After the reaction is completed, filter, wash 3 times with ethanol, and dry at 100 °C to constant weight to obtain phenylsilane coupling agent modified ultrafine talc powder.

[0042] 2) Prepare a treatment solution with a concentration of 3wt% for 1.0kg of trimethoxy(2-phenylethyl)silane and water, add 100g of chopped alkali-free glass fiber, heat to 80℃ and react for 2h. After the reaction is completed, filter, wash 3 times with ethanol, and dry at 100℃ to constant weight to obtain phenylsilane coupling agent modified chopped alkali-free glass fiber.

[0043] 3) Mix 100g of polyphenylene sulfide, 20g of E-03 bisphenol A type solid epoxy resin, 8g of side-chain epoxy polysiloxane IOTA105-2-0.25, 50g of phenylsilane coupling agent modified ultrafine talc powder obtained in step 1), and 50g of phenylsilane coupling agent modified short chopped alkali-free glass fiber obtained in step 2) evenly in a high-speed mixer, then extrude and granulate, cool and dry to obtain polyphenylene sulfide composite material for capacitor shells;

[0044] The extrusion granulation conditions are as follows: zone 1-11 temperatures: 245℃, 255℃, 265℃, 275℃, 285℃, 295℃, 300℃, 300℃, 300℃, 300℃, 300℃; die head temperature: 310℃; screw diameter: 65mm; length-to-diameter ratio: 40:1; screw speed: 350rpm.

[0045] Example 5

[0046] The rest is the same as in Example 1, except that in step 3), 100g of polyphenylene sulfide, 20g of E-03 bisphenol A type solid epoxy resin, 8g of side-chain epoxy polysiloxane IOTA105-2-0.15, 40g of phenylsilane coupling agent modified ultrafine talc powder obtained in step 1), and 60g of phenylsilane coupling agent modified short chopped alkali-free glass fiber obtained in step 2) are mixed evenly in a high-speed mixer, and then extruded, granulated, cooled and dried to obtain polyphenylene sulfide composite material for capacitor shells.

[0047] Example 6

[0048] The rest is the same as in Example 1, except that in step 3), 100g of polyphenylene sulfide, 10g of E-03 bisphenol A type solid epoxy resin, 8g of side-chain epoxy polysiloxane IOTA105-2-0.15, 30g of phenylsilane coupling agent modified ultrafine talc powder obtained in step 1), and 30g of phenylsilane coupling agent modified short chopped alkali-free glass fiber obtained in step 2) are mixed evenly in a high-speed mixer, and then extruded, granulated, cooled and dried to obtain polyphenylene sulfide composite material for capacitor shells.

[0049] Example 7

[0050] The rest is the same as in Example 1, except that in step 3), 100g of polyphenylene sulfide, 20g of E-03 bisphenol A type solid epoxy resin, 8g of side-chain epoxy polysiloxane IOTA105-2-0.15, and 100g of phenylsilane coupling agent modified ultrafine talc powder obtained in step 1) are mixed evenly in a high-speed mixer, and then extruded, granulated, cooled and dried to obtain polyphenylene sulfide composite material for capacitor shells.

[0051] Example 8

[0052] The rest is the same as in Example 1, except that in step 3), 100g of polyphenylene sulfide, 20g of E-03 bisphenol A type solid epoxy resin, 8g of side-chain epoxy polysiloxane IOTA105-2-0.15, and 100g of phenylsilane coupling agent modified short chopped alkali-free glass fiber obtained in step 2) are mixed evenly in a high-speed mixer, and then extruded, granulated, cooled and dried to obtain polyphenylene sulfide composite material for capacitor shells.

[0053] Comparative Example 1

[0054] The rest is the same as in Example 1, except that the amount of side-chain epoxy polysiloxane IOTA105-2-0.15 used in step 3) is 3g.

[0055] Comparative Example 2

[0056] The rest is the same as in Example 1, except that the amount of side-chain epoxy polysiloxane IOTA105-2-0.15 used in step 3) is 10g.

[0057] Comparative Example 3

[0058] 100g of polyphenylene sulfide, 20g of E-03 bisphenol A type solid epoxy resin, 8g of side-chain epoxy polysiloxane IOTA105-2-0.15, 50g of ultrafine talc powder, and 50g of chopped alkali-free glass fiber are mixed evenly in a high-speed mixer, and then extruded, granulated, cooled and dried to obtain polyphenylene sulfide composite material for capacitor shells.

[0059] The extrusion granulation conditions are as follows: zone 1-11 temperatures: 245℃, 255℃, 265℃, 275℃, 285℃, 295℃, 300℃, 300℃, 300℃, 300℃, 300℃; die head temperature: 310℃; screw diameter: 65mm; length-to-diameter ratio: 40:1; screw speed: 350rpm.

[0060] Comparative Example 4

[0061] The rest is the same as in Example 1, except that 3-aminopropyltrimethoxysilane is used instead of trimethoxy(2-phenylethyl)silane in equal mass.

[0062] Comparative Example 5

[0063] The rest is the same as in Example 1, except that the side-chain epoxy polysiloxane IOTA105-2-0.15 is replaced with an equal mass of DuPont Elvaloy PTW.

[0064] The composite materials prepared in the above examples and comparative examples were subjected to the following performance tests:

[0065] Tensile strength: The tensile strength was tested in accordance with the standard ISO 527 Plastics - Determination of tensile properties.

[0066] High-temperature durability: In accordance with standard GBT 7141-2008, thermal aging was carried out using a thermal aging oven at 125℃ for 1000 hours. The tensile strength was retested and the strength loss rate was calculated.

[0067] Bond strength test with epoxy potting compound: 170mm*10mm*4mm polyphenylene sulfide composite material sheet was injection molded. Loctite epoxy resin AB glue EA E-60NC was evenly coated on one end of the sheet, with a coating area of ​​30mm*10mm and a thickness of 7mm. Another sheet was then placed on the same position. The sheet was cured at 25℃ for 60 minutes in a constant temperature chamber. Tensile strength was then tested using an XLW-1 intelligent electronic tensile testing machine.

[0068] Impact strength: The impact performance was tested according to the method in ISO 179-1 Plastics - Determination of impact strength of simply supported beams (C-notch).

[0069] Table 1 Performance Test Results

[0070]

[0071]

[0072] As can be seen from the performance test results in Table 1, the polyphenylene sulfide composite material prepared by this invention has good toughness and excellent adhesion to epoxy resin. It can work continuously at high temperatures and is suitable as a capacitor shell material.

[0073] The performance test results of Example 1 and Comparative Example 5 show that the use of side-chain epoxy polysiloxane to replace the conventional ethylene-methyl acrylate-glycidyl methacrylate terpolymer has a significant effect on improving the high-temperature durability of the composite material.

[0074] From the changes in strength and bond strength of Comparative Examples 3 and 4 to Example 1, it can be seen that the bond strength and mechanical strength of the composite material gradually increase from unmodified filler to modified with aminosilane coupling agent to modified with phenylsilane coupling agent, indicating that the epoxy resin and the composite material system gradually become more compatible with each other as the modification progresses.

[0075] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A polyphenylene sulfide composite material for capacitor housings, characterized in that, The raw materials include the following parts by weight: 100 parts polyphenylene sulfide, 10-20 parts bisphenol A type solid epoxy resin, 5-8 parts toughening agent, and 60-100 parts phenylsilane coupling agent modified filler. The toughening agent is a side-chain epoxy polysiloxane with epoxy groups on its side chain, obtained by hydrosilylation reaction of methyl hydrogen silicone oil and allyl glycidyl ether, with an epoxy value of 0.15-0.25 and a viscosity of 50-120 mPa·s at 25°C. The phenylsilane coupling agent modified filler is prepared by a mass ratio of 1:1-1.

5. The material is a mixture of phenylsilane coupling agent modified granular inorganic filler and phenylsilane coupling agent modified rod-shaped inorganic filler; the rod-shaped inorganic filler has an average diameter of 1-20 μm and an aspect ratio of 5-20, and is selected from one or more combinations of glass fiber, insulating potassium titanate whiskers, and basalt fiber; the granular inorganic filler has an average particle size of 0.1-10 μm and is selected from one or more combinations of mica, diatomaceous earth, talc, montmorillonite, kaolin, silica, glass microspheres, calcium carbonate, barium sulfate, and titanium dioxide.

2. The polyphenylene sulfide composite material for capacitor housing according to claim 1, characterized in that, The rod-shaped inorganic filler is glass fiber.

3. The polyphenylene sulfide composite material for capacitor housing according to claim 1, characterized in that, The phenylsilane coupling agent is selected from one or more combinations of 3-phenylpropylmethyldimethoxysilane, 4-phenylbutyltrimethoxysilane, triethoxy(2-phenylpropyl)silane, trimethoxy(2-phenylethyl)silane, 3-phenylpropyldimethylmethoxysilane, and methyldi(ethoxy)(2-phenylpropyl)silane.

4. The polyphenylene sulfide composite material for capacitor housing according to claim 1, characterized in that, The preparation method of the phenylsilane coupling agent modified filler includes the following steps: preparing a treatment solution of phenylsilane coupling agent and water, adding inorganic filler, heating to carry out the reaction, filtering, washing, and drying after the reaction to obtain phenylsilane coupling agent modified inorganic filler.

5. The polyphenylene sulfide composite material for capacitor housing according to claim 4, characterized in that, The concentration of phenylsilane coupling agent in the treatment solution is 1-3 wt%, the mass ratio of inorganic filler to treatment solution is 1:10-12, the temperature is raised to 60-80℃, the reaction time is 1-3 h, and the washing is performed with ethanol 1-3 times.

6. The polyphenylene sulfide composite material for capacitor housing according to claim 1, characterized in that, The bisphenol A type solid epoxy resin has an epoxy equivalent of 2000-4000 g / eq; the polyphenylene sulfide has a weight-average molecular weight of 40,000-60,000.

7. A method for preparing the polyphenylene sulfide composite material for capacitor casings according to any one of claims 1-6, characterized in that, Includes the following steps: Polyphenylene sulfide, bisphenol A type solid epoxy resin, toughening agent, phenylsilane coupling agent modified filler are mixed evenly, then extruded and granulated, cooled and dried to obtain polyphenylene sulfide composite material for capacitor shells.

8. The method for preparing the polyphenylene sulfide composite material for capacitor casing according to claim 7, characterized in that, The extrusion granulation conditions are as follows: Zone 11 temperatures: 230-150℃, 250-260℃, 260-270℃, 270-280℃, 280-290℃, 290-300℃, 300-310℃, 300-310℃, 300-310℃, 300-310℃, 300-310℃; Die temperature: 310-320℃; Screw diameter: 30-65mm; L / D ratio: 25-42:1; Screw speed: 250-350rpm.

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