Laminated aluminum sheet for drilling of printed circuit board and preparation method of laminated aluminum sheet

Abstract

The invention provides a laminated aluminum sheet for drilling a printed circuit board and a preparation method thereof. The laminated aluminum sheet for drilling the printed circuit board comprises an aluminum sheet and a modified polyvinyl alcohol laminated film sprayed on the surface of the aluminum sheet, wherein the modified polyvinyl alcohol spraying film is prepared from the following raw materials: polyvinyl alcohol, a fluxing agent, a medium-low molecular weight polymer, a lubricating agent, a heat stabilizer and an antioxidant. The polyvinyl alcohol is subjected to thermoplastic blending modification, so that the melting point, the melt viscosity and the film forming hardness of the polyvinyl alcohol are reduced, the thermal stability of a melt and the lubricating property after film forming are improved, and film spraying production operation and subsequent drilling performance improvement are facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit boards, and in particular to a coated aluminum sheet for drilling holes in a printed circuit board and a preparation method thereof. Background Art

[0002] At present, coated aluminum sheets occupy a large market in the field of printed circuit board drilling cover sheets due to their high production efficiency and high cost performance. The most common materials for the surface coating of coated aluminum sheets are polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), etc., which are all water-insoluble. During the drilling process of such coated aluminum sheets, the film layer will melt due to the high local drilling temperature, adhere to the holes of the printed circuit board, and is not easy to be washed off by the water washing process, which seriously affects the client's later processing operations; the used products are not easy to peel off from the aluminum sheet because the film layer is not easy to be recovered and utilized; and the film layer cannot be harmlessly degraded, which has a great impact on the natural environment and the balance of the ecosystem, and is not in line with the national green and sustainable development strategy.

[0003] Polyvinyl alcohol (PVA) has many advantages such as good film-forming property, good adhesion, good water solubility, biodegradability and low price. However, the melting temperature of PVA is relatively high (230-240°C), and oxidative dehydration reaction begins to occur when the temperature is above 200°C but not yet in a molten state. The thermal decomposition reaction is more significant near the melting temperature, and it is not easy to obtain a melt with stable performance for subsequent coating operations. In addition, the hardness of polyvinyl alcohol after film formation is relatively high, which will increase the risk of deflection of the drill bit during drilling, which is not conducive to improving the hole position accuracy.

[0004] Therefore, it is necessary to perform thermoplastic blending modification on polyvinyl alcohol (PVA) and develop a new type of coated aluminum sheet for drilling printed circuit boards and a preparation method thereof. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a coated aluminum sheet for drilling holes in a printed circuit board and a preparation method thereof, wherein the coated aluminum sheet for drilling holes in a printed circuit board comprises an aluminum sheet and a modified polyvinyl alcohol coating sprayed on the surface thereof; wherein the raw materials for preparing the modified polyvinyl alcohol coating comprise: polyvinyl alcohol, a fluxing agent, a medium and low molecular weight polymer, a lubricant, a thermal stabilizer, and an antioxidant. The present invention reduces its melting point, melt viscosity, and film hardness by thermoplastic blending modification of polyvinyl alcohol, improves the thermal stability of the melt and the lubricating properties after film formation, and is more conducive to the coating production operation and the subsequent improvement of drilling performance.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a coated aluminum sheet for drilling holes in a printed circuit board, the coated aluminum sheet for drilling holes in a printed circuit board comprising an aluminum sheet and a modified polyvinyl alcohol coating sprayed on the surface thereof;

[0008] Wherein, in parts by mass, the raw materials for preparing the modified polyvinyl alcohol coating include:

[0009] 40-60 parts of polyvinyl alcohol, for example 40 parts, 43 parts, 45 parts, 47 parts, 50 parts, 52 parts, 55 parts, 57 parts or 60 parts, etc.;

[0010] 10-40 parts of fluxing agent, for example, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts or 40 parts, etc.;

[0011] 10-30 parts of medium and low molecular weight polymers, such as 10 parts, 15 parts, 20 parts, 25 parts or 30 parts;

[0012] 1-5 parts of lubricant, for example, 1 part, 2 parts, 3 parts, 4 parts or 5 parts, etc.;

[0013] 1-5 parts of heat stabilizer, for example, 1 part, 2 parts, 3 parts, 4 parts or 5 parts, etc.;

[0014] 1-5 parts of antioxidant, for example, 1 part, 2 parts, 3 parts, 4 parts or 5 parts, etc.

[0015] The present invention reduces the melting point, melt viscosity, and film hardness of polyvinyl alcohol (PVA) by thermoplastic blending modification, improves the thermal stability of the melt and the lubricating properties after film formation, and is more conducive to the film coating production operation and the improvement of subsequent drilling performance. Specifically, the present invention destroys the regularity of the PVA molecular structure by adding a fluxing agent and medium and low molecular weight polymers, significantly reduces its crystallinity, and the isolation and shielding effect of the low molecular weight substance greatly weakens the interaction force between the hydrogen bonds of the PVA polymer chain; as the temperature rises, the molecular motion intensifies, and the aggregation effect between the PVA molecular chains is significantly weakened, which is manifested as a decrease in the melting point, melt viscosity, and hardness after film formation; and by adding a heat stabilizer and an antioxidant, the occurrence of oxidative decomposition reaction of PVA after heating is reduced, and a melt with more stable performance can be obtained for subsequent film coating operations; the addition of a lubricant improves the lubricating properties of the film layer, which is conducive to the improvement of hole position accuracy and the extension of the life of the drill bit.

[0016] As a preferred technical solution of the present invention, the fluxing agent includes any one of propylene glycol, neopentyl glycol, diethylene glycol, triethylene glycol, ethylene glycol, dioctyl phthalate, di(2-ethylhexyl) phthalate, dioctyl terephthalate, dioctyl adipate, dioctyl azelaic acid, dibutyl sebacate, dioctyl sebacate, dibutyl maleate, dioctyl maleate, octyl epoxy stearate, triphenyl phosphate, trioctyl phosphate, and diphenyl carbonate, or a combination of at least two of them.

[0017] As a preferred technical solution of the present invention, the molecular weight of the medium and low molecular weight polymer is less than 10,000, including any one of polyvinyl pyrrolidone, polyethylene glycol, polybutylene succinate, polyamide, thermoplastic polyurethane, polyvinyl chloride, and polyethylene, or a combination of at least two thereof.

[0018] As a preferred technical solution of the present invention, the lubricant includes any one of butyl stearate, octyl stearate, stearic acid amide, ethylene bisstearamide, oleic acid amide, erucic acid amide, glyceryl trihydroxystearate, microcrystalline paraffin, solid paraffin, polyethylene wax, polypropylene wax, oxidized polyethylene, Fischer-Tropsch wax, and stearyl alcohol, or a combination of at least two of them.

[0019] As a preferred technical solution of the present invention, the heat stabilizer includes any one of tribasic lead sulfate, tribasic lead maleate, dibasic lead phosphite, dibasic lead stearate, dibasic lead phthalate, basic lead carbonate, zinc stearate, calcium stearate, magnesium stearate, barium stearate, lead stearate, phosphite, and pentaerythritol, or a combination of at least two thereof.

[0020] As a preferred technical solution of the present invention, the antioxidant includes any one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester (antioxidant 1010), tris[2,4-di-tert-butylphenyl]phosphite (antioxidant 168), β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester (antioxidant 1076), 2,6-di-tert-butyl-4-methylphenol (antioxidant 264), tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester (antioxidant 264), n-octadecanoic acid alcohol ester, triphenyl phosphite, tributyl sulfite, disalicylidene diamine, and oxamide, or a combination of at least two thereof.

[0021] As a preferred technical solution of the present invention, the thickness of the aluminum sheet is 70-150μm, for example, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm or 150μm, and the thickness of the modified polyvinyl alcohol coating is 20-100μm, for example, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm, etc.

[0022] In a second aspect, the present invention provides a method for preparing a coated aluminum sheet for drilling a printed circuit board according to any one of claims 1 to 7, the preparation method comprising the following steps:

[0023] (1) mixing polyvinyl alcohol particles and a fluxing agent uniformly according to a mass ratio and then allowing the mixture to stand until the polyvinyl alcohol particles swell and the particle surfaces are dry;

[0024] (2) uniformly mixing the swollen polyvinyl alcohol particles obtained in step (1), a medium- and low-molecular-weight polymer, a lubricant, a heat stabilizer, and an antioxidant, and sequentially performing melt mixing and extrusion granulation to obtain modified polyvinyl alcohol particles;

[0025] (3) The modified polyvinyl alcohol particles obtained in step (2) are heated and melted, and the obtained low-viscosity melt is sprayed on the surface of the aluminum sheet, and after cooling, a coated aluminum sheet for drilling holes in a printed circuit board is obtained.

[0026] It should be noted that in the preparation method of the present invention, step (1) is to mix the polyvinyl alcohol particles and the fluxing agent evenly and then let it stand until the polyvinyl alcohol particles swell to the surface of the particles and dry. This is a process of penetration of the small molecule fluxing agent into the polymer, which is more conducive to uniform melt blending in the later stage. The melt mixing and extrusion granulation performed in sequence in step (2) cannot be omitted. On the one hand, this process is a process of blending after the solid material is melted into a liquid. Without this process, the solid material will not be mixed evenly. On the other hand, the modified polyvinyl alcohol particles obtained are easier to store and transport, and can be heated and melted for spraying when needed.

[0027] As a preferred technical solution of the present invention, the uniform mixing in step (1) includes: stirring at a stirring speed of 300-500 r / min, such as 300 r / min, 350 r / min, 400 r / min, 450 r / min or 500 r / min, for 10-30 min, such as 10 min, 15 min, 20 min, 25 min or 30 min, etc.

[0028] Preferably, the standing time in step (1) is 10-15 h, for example, 10 h, 11 h, 12 h, 13 h, 14 h or 15 h.

[0029] As a preferred technical solution of the present invention, the target temperature of the melt mixing in step (2) is 120-180°C, for example, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C, etc.

[0030] Preferably, the target temperature of the heating and melting in step (3) is 120-200°C, such as 180°C, 185°C, 190°C, 195°C or 200°C.

[0031] It should be noted that, in general, a twin-screw extruder for melting is divided into temperature zones, and the target temperature refers to the highest temperature that can be reached.

[0032] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0033] The present invention provides a coated aluminum sheet for drilling holes in a printed circuit board and a preparation method thereof, wherein the coated aluminum sheet for drilling holes in a printed circuit board comprises an aluminum sheet and a modified polyvinyl alcohol coating sprayed on the surface thereof; wherein the raw materials for preparing the modified polyvinyl alcohol coating comprise: polyvinyl alcohol, a flux, a medium and low molecular weight polymer, a lubricant, a heat stabilizer, and an antioxidant. The present invention reduces the melting point, melt viscosity, and film hardness of polyvinyl alcohol by thermoplastic blending modification, improves the thermal stability of the melt and the lubricating properties after film formation, and is more conducive to the coating production operation and the improvement of subsequent drilling performance. DETAILED DESCRIPTION

[0034] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0035] The reagents used in the specific embodiments of the present invention are all conventional commercially available products. For the same reagent, all embodiments and comparative examples use the same type of reagent.

[0036] Example 1

[0037] This embodiment provides a method for preparing a coated aluminum sheet for drilling holes in a printed circuit board, the method comprising the following steps:

[0038] (1) 50 parts of polyvinyl alcohol particles and 20 parts of a fluxing agent (ethylene glycol, dioctyl adipate, and dioctyl maleate in a mass ratio of 5:3:2) were placed in a stirrer, stirred at a stirring speed of 300 r / min for 10 min, and sealed after being mixed evenly. The mixture was placed at room temperature for 10 h until the polyvinyl alcohol particles swelled and the particle surface was dry;

[0039] (2) mixing the swollen polyvinyl alcohol particles obtained in step (1) and 20 parts of medium and low molecular weight polymers (polyvinyl pyrrolidone, polybutylene succinate, polyvinyl chloride in a mass ratio of 4:3:3), 3 parts of lubricants (microcrystalline wax and polypropylene wax in a mass ratio of 1:1), 3 parts of heat stabilizers (dibasic lead phosphite and zinc stearate in a mass ratio of 1:2), and 3 parts of antioxidants (antioxidant 264 and antioxidant 264 in a mass ratio of 1:2) uniformly, adding the mixture to a twin-screw extruder with a target temperature set at 170°C for melt mixing and extrusion granulation to obtain modified polyvinyl alcohol particles;

[0040] (3) The modified polyvinyl alcohol particles obtained in step (2) are heated and melted at a target temperature of 170° C., and the obtained low-viscosity melt is sprayed on the surface of an aluminum sheet with a thickness of 100 μm by a laminating machine, and the laminating thickness is controlled to be 50 μm. After cooling, a laminated aluminum sheet for drilling printed circuit boards with a fully water-soluble, degradable laminating film is obtained.

[0041] Example 2

[0042] This embodiment provides a method for preparing a coated aluminum sheet for drilling holes in a printed circuit board, the method comprising the following steps:

[0043] (1) 40 parts of polyvinyl alcohol particles and 10 parts of a fluxing agent (propylene glycol, dioctyl phthalate, and dioctyl azelate in a mass ratio of 7:1:2) were placed in a stirrer and stirred at a stirring speed of 300 r / min for 10 min. After the mixture was evenly mixed, it was sealed and placed at room temperature for 10 h until the polyvinyl alcohol particles swelled and the particle surface was dry;

[0044] (2) mixing the swollen polyvinyl alcohol particles obtained in step (1) and 10 parts of medium and low molecular weight polymers (polyvinyl pyrrolidone, polyethylene glycol, polyamide in a mass ratio of 4:3:3), 2 parts of lubricants (butyl stearate, octyl stearate in a mass ratio of 1:1), 1 part of heat stabilizer (tribasic lead sulfate), and 2 parts of antioxidants (antioxidant 1010, antioxidant 168, antioxidant 1076 in a mass ratio of 1:0.5:0.5) evenly, adding the mixture to a twin-screw extruder set at a target temperature of 180° C., melting and mixing, and extruding and granulating to obtain modified polyvinyl alcohol particles;

[0045] (3) The modified polyvinyl alcohol particles obtained in step (2) are heated and melted at a target temperature of 180° C., and the obtained low-viscosity melt is sprayed on the surface of an aluminum sheet with a thickness of 100 μm by a laminating machine, and the laminating thickness is controlled to be 50 μm. After cooling, a laminated aluminum sheet for drilling printed circuit boards with a fully water-soluble, degradable laminating film is obtained.

[0046] Example 3

[0047] This embodiment provides a method for preparing a coated aluminum sheet for drilling holes in a printed circuit board, the method comprising the following steps:

[0048] (1) 60 parts of polyvinyl alcohol particles and 30 parts of a fluxing agent (triethylene glycol, di(2-ethylhexyl) phthalate, and octyl epoxy stearate in a mass ratio of 8:1:1) were placed in a stirrer and stirred at a stirring speed of 300 r / min for 10 min. After the mixture was evenly mixed, it was sealed and placed at room temperature for 10 h until the polyvinyl alcohol particles swelled and the particle surface was dry;

[0049] (2) mixing the swollen polyvinyl alcohol particles obtained in step (1) and 30 parts of medium and low molecular weight polymers (polyvinyl pyrrolidone, thermoplastic polyurethane, polyethylene in a mass ratio of 6:3:1), 3 parts of lubricants (stearic acid amide, ethylene bisstearamide, Fischer-Tropsch wax in a mass ratio of 1:1:1), 4 parts of heat stabilizers (dibasic lead phthalate, barium stearate in a mass ratio of 1:1), and 3 parts of antioxidants (antioxidant 1010, antioxidant 168, antioxidant 264 in a mass ratio of 1:1:1) uniformly, adding them to a twin-screw extruder set at a target temperature of 180°C for melt mixing and extrusion granulation to obtain modified polyvinyl alcohol particles;

[0050] (3) The modified polyvinyl alcohol particles obtained in step (2) are heated and melted at a target temperature of 180° C., and the obtained low-viscosity melt is sprayed on the surface of an aluminum sheet with a thickness of 100 μm by a laminating machine, and the laminating thickness is controlled to be 50 μm. After cooling, a laminated aluminum sheet for drilling printed circuit boards with a fully water-soluble, degradable laminating film is obtained.

[0051] Comparative Example 1

[0052] This comparative example provides a method for preparing a coated aluminum sheet for drilling holes in a printed circuit board. Compared with Example 1, the only difference is that the fluxing agent in step (1) is completely omitted, that is, 50 parts of polyvinyl alcohol particles are directly mixed with the raw materials in step (2).

[0053] Comparative Example 2

[0054] This comparative example provides a method for preparing a coated aluminum sheet for drilling holes in a printed circuit board. Compared with Example 1, the only difference is that the medium and low molecular weight polymers in step (2) are completely omitted.

[0055] Comparative Example 3

[0056] This comparative example provides a method for preparing a coated aluminum sheet for drilling holes in a printed circuit board. Polyvinyl alcohol particles are directly heated and melted, and the obtained melt is sprayed on the surface of an aluminum sheet with a thickness of 100 μm by a coating machine. The coating thickness is controlled to be 50 μm, and after cooling, a coated aluminum sheet for drilling holes in a printed circuit board is obtained.

[0057] The following tests were conducted on the above-mentioned embodiments and comparative examples: the melting point of the polymer particles before spraying by the laminating machine, the pencil hardness of the laminating film, and the water solubility of the laminating film; wherein the water solubility test method of the laminating film includes: cutting the laminating aluminum sheet into long strips and inserting it into water to a depth of about 5 cm and starting the timing, taking it out after 5 minutes, and observing the dissolution of the film layer at the soaked part. The specific test results are summarized in Table 1.

[0058] Table 1

[0059]

[0060]

[0061] In summary, the present invention provides a coated aluminum sheet for drilling holes in a printed circuit board and a preparation method thereof, wherein the coated aluminum sheet for drilling holes in a printed circuit board comprises an aluminum sheet and a modified polyvinyl alcohol coating sprayed on the surface thereof; wherein the raw materials for preparing the modified polyvinyl alcohol coating comprise: polyvinyl alcohol, a flux, a medium and low molecular weight polymer, a lubricant, a thermal stabilizer, and an antioxidant. The present invention reduces the melting point, melt viscosity, and film hardness of polyvinyl alcohol by thermoplastic blending modification, the melting point is reduced to 120-200°C, the film hardness is ≤8B, the thermal stability of the melt and the lubrication properties after film formation are improved, and it is more conducive to the coating production operation and the improvement of subsequent drilling performance.

[0062] The present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A coated aluminum sheet for drilling holes in a printed circuit board, characterized in that: The coated aluminum sheet for drilling holes in a printed circuit board comprises an aluminum sheet and a modified polyvinyl alcohol coating sprayed on the surface thereof; Wherein, in parts by mass, the raw materials for preparing the modified polyvinyl alcohol coating include: 40-60 parts of polyvinyl alcohol; 10-40 parts of fluxing agent; 10-30 parts of medium and low molecular weight polymers; 1-5 parts of lubricant; 1-5 parts of heat stabilizer; 1-5 parts of antioxidants.

2. The coated aluminum sheet for drilling printed circuit boards according to claim 1, characterized in that: The fluxing agent includes any one of propylene glycol, neopentyl glycol, diethylene glycol, triethylene glycol, ethylene glycol, dioctyl phthalate, di(2-ethylhexyl) phthalate, dioctyl terephthalate, dioctyl adipate, dioctyl azelaic acid, dibutyl sebacate, dioctyl sebacate, dibutyl maleate, dioctyl maleate, octyl epoxy stearate, triphenyl phosphate, trioctyl phosphate, and diphenyl carbonate, or a combination of at least two thereof.

3. The coated aluminum sheet for drilling printed circuit boards according to claim 1, characterized in that: The molecular weight of the medium and low molecular weight polymer is less than 10,000, and includes any one of polyvinyl pyrrolidone, polyethylene glycol, polybutylene succinate, polyamide, thermoplastic polyurethane, polyvinyl chloride, and polyethylene, or a combination of at least two thereof.

4. The coated aluminum sheet for drilling printed circuit boards according to claim 1, characterized in that: The lubricant includes any one of butyl stearate, octyl stearate, stearic acid amide, ethylene bis stearamide, oleic acid amide, erucic acid amide, glyceryl trihydroxystearate, microcrystalline wax, solid paraffin, polyethylene wax, polypropylene wax, oxidized polyethylene, Fischer-Tropsch wax, and stearyl alcohol, or a combination of at least two thereof.

5. The coated aluminum sheet for drilling printed circuit boards according to claim 1, characterized in that: The heat stabilizer includes any one of tribasic lead sulfate, tribasic lead maleate, dibasic lead phosphite, dibasic lead stearate, dibasic lead phthalate, basic lead carbonate, zinc stearate, calcium stearate, magnesium stearate, barium stearate, lead stearate, phosphite, and pentaerythritol, or a combination of at least two thereof.

6. The coated aluminum sheet for drilling printed circuit boards according to claim 1, characterized in that: The antioxidant includes any one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester, tris[2,4-di-tert-butylphenyl] phosphite, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol ester, 2,6-di-tert-butyl-4-methylphenol, tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester, n-octadecanoic acid alcohol ester, triphenyl phosphite, tributyl sulfite, disalicylidene diamine, and oxamide, or a combination of at least two thereof.

7. The coated aluminum sheet for drilling printed circuit boards according to claim 1, characterized in that: The thickness of the aluminum sheet is 70-150 μm, and the thickness of the modified polyvinyl alcohol coating is 20-100 μm.

8. A method for preparing a coated aluminum sheet for drilling printed circuit boards according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: (1) mixing polyvinyl alcohol particles and a fluxing agent uniformly according to a mass ratio and then allowing the mixture to stand until the polyvinyl alcohol particles swell and the particle surfaces are dry; (2) uniformly mixing the swollen polyvinyl alcohol particles obtained in step (1), a medium- and low-molecular-weight polymer, a lubricant, a heat stabilizer, and an antioxidant, and sequentially performing melt mixing and extrusion granulation to obtain modified polyvinyl alcohol particles; (3) The modified polyvinyl alcohol particles obtained in step (2) are heated and melted, and the obtained low-viscosity melt is sprayed on the surface of the aluminum sheet, and after cooling, a coated aluminum sheet for drilling holes in a printed circuit board is obtained.

9. The method for preparing the coated aluminum sheet for drilling printed circuit boards according to claim 8, characterized in that: The step (1) of mixing uniformly comprises: stirring at a stirring speed of 300-500 r / min for 10-30 min; Preferably, the standing time in step (1) is 10-15 hours.

10. The method for preparing the coated aluminum sheet for drilling printed circuit boards according to claim 8 or 9, characterized in that: The target temperature of the melt mixing in step (2) is 120-180°C; Preferably, the target temperature of the heating and melting in step (3) is 120-200°C.

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