Single-phase immersed modified organosiloxane cooling liquid and preparation method thereof

Abstract

The invention discloses a single-phase immersed modified organosiloxane cooling liquid. The general formula of the single-phase immersed modified organosiloxane cooling liquid is as follows: R1 (CH3) 2SiO-[(CH3) 2SiO] n (CH3) 2SiR2, wherein n is equal to 1-20, and R1 and R2 are alkyl groups of 8-16. The invention also discloses a preparation method of the single-phase immersed modified organosiloxane cooling liquid, which comprises the following steps: under nitrogen purging and at 20-30 DEG C, uniformly mixing olefin and a catalyst, heating to 35-45 DEG C, dropwise adding hydrogen-containing siloxane, and controlling the temperature of the reaction liquid within the range of 60-150 DEG C; after adding, continuously stirring; and cooling after the reaction is finished, and removing residual olefin to obtain a final product. The prepared single-phase immersion type modified organosiloxane cooling liquid has the performance of high flash point and low viscosity, is low in surface tension, good in fluidity, more comprehensive in coverage, better in heat dissipation effect, good in compatibility with materials of a data center, free of swelling and other damage with related materials and high in safety and long-term effectiveness.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cooling liquid preparation, in particular to a single-phase immersion type modified organosiloxane cooling liquid and a preparation method thereof. BACKGROUND

[0002] In recent years, with the rapid development of technology and digital economy, high-density, high-computing-power and high-energy-consumption data centers have shown explosive growth, and a large amount of data throughput and operation has brought unprecedented challenges of high energy consumption and thermal management system to data centers. In this context, liquid-cooled data centers using new liquid cooling technology and liquid-cooled servers and other equipment have emerged.

[0003] Compared with air cooling, liquid cooling can deploy more high-density storage in limited space, better support heat dissipation of high-power chips, ensure low-temperature operation of chips, be safe and quiet, effectively reduce the PUE (power utilization efficiency) value of data centers, facilitate IT expansion, and greatly reduce operation and maintenance costs without using high-cost components such as centrifugal machines, refrigeration pumps, scroll compressors and precision air conditioners.

[0004] The direct cooling liquids for data center equipment on the market mainly include fluorinated materials, mineral oil, poly-alpha olefin (PAO) synthetic oil and polydimethylsiloxane (PDMS). The fluorinated material has a relatively low boiling point and can quickly vaporize to carry away a large amount of heat. However, the fluorinated material has a relatively low boiling point, and a high vapor pressure will be generated during the cooling and heat exchange process, thereby causing the cooling system to have to withstand a high pressure, which greatly increases the manufacturing and operating costs of the cooling system. SUMMARY

[0005] An object of the present application is to provide a single-phase immersion type modified organosiloxane cooling liquid, which has low viscosity, high flash point and other characteristics.

[0006] A single-phase immersion type modified organosiloxane cooling liquid has the following general formula:

[0007] R1(CH3)2SiO-[(CH3)2SiO] n (CH3)2SiR2;

[0008] The structural formula is:

[0009] wherein n = 1-20, R1, R2 = alkyl groups of 8-16.

[0010] Further, it has a flash point of > 150℃ and a viscosity of < 20 mm 2 / s at 25℃.

[0011] Another object of the present application is to provide a preparation method of the single-phase immersion modified organosiloxane coolant, under nitrogen purging, mixing the olefin and the catalyst uniformly at 20-30 DEG C, increasing the temperature to 35-45 DEG C, adding the hydrogen-containing siloxane drop by drop, controlling the temperature of the reaction solution in the range of 60-150 DEG C, continuing to stir after the addition, cooling after the reaction, and removing the residual olefin to obtain the final product.

[0012] As a preferred scheme of the present application, the alkyl group has 8-16 carbon atoms, which can be linear or branched or phenyl-substituted alkyl.

[0013] As a preferred scheme of the present application, the hydrogen-containing siloxane is

[0014] H(CH3)2SiO-[(CH3)2SiO] n (CH3)2SiH; n = 1-20.

[0015] As a preferred scheme of the present application, the metal catalyst is a complex containing palladium, rhodium or platinum, and the addition amount is 1-300 ppm; preferably, the metal catalyst is a complex of platinum, including one or more of isopropanol solution of chloroplatinic acid, platinum-divinyl disiloxane Karstedt platinum catalyst, platinum-allyl polyether Karstedt catalyst and supported solid platinum catalyst, and the addition amount is 1-100 ppm.

[0016] The single-phase immersion modified organosiloxane coolant prepared by the present application has the advantages of high flash point, low viscosity, low surface tension, good flowability, more comprehensive coverage, better heat dissipation effect, good material compatibility with the data center, no swelling and other damage to the related materials, safety and long-term effect.

[0017] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. DETAILED DESCRIPTION

[0018] In order to make the objects, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below.

[0019] In the examples, the specific techniques or conditions not specified are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. The reagents or instruments not specified by the manufacturer are all conventional products that can be obtained by purchase.

[0020] It should be noted that the most preferred catalyst is Karstedt catalyst, the chemical name of which is platinum(0)tetramethyldivinyl disiloxane.

[0021] Hydrogen-containing siloxane: H(CH3)2SiO-[(CH3)2SiO]1(CH3)2SiH (n = 1) Preparation

[0022] In a dry 2000 mL three-necked flask, 800 grams of tetramethyl disiloxane, 400 grams of dimethyl siloxane mixed ring, then 10 grams of concentrated sulfuric acid were added, and reacted for 6 hours under stirring, neutralized with 18 grams of sodium carbonate, filtered, dried, and the mixture was distilled, and the fraction of 70-90 °C was taken, and the viscosity was tested to be 0.8 mm / s, and the hydrogen content was 0.96%. 2

[0023] Example 1

[0024] Under nitrogen purge, 269.3 grams of 1-hexadecene and 124 milligrams of Karstedt catalyst were added to a four-necked flask at 25 °C. While stirring, 104.3 grams of H(CH3)2SiO-[(CH3)2SiO]1(CH3)2SiH were added dropwise at 40 °C, controlling the reaction liquid temperature to be within the range of 80-120 °C. After the addition was completed, the reaction was continued for 4 hours under stirring. The product was distilled under reduced pressure to remove residual 1-hexadecene. 37 grams of activated carbon were added, and after stirring for 1 h, it was filtered.

[0025] H(CH3)2SiO-[(CH3)2SiO]1(CH3)2SiH, controlling the reaction liquid temperature to be within the range of 80-120 °C. After the addition was completed, the reaction was continued for 4 hours under stirring. The product was distilled under reduced pressure to remove residual 1-hexadecene. 37 grams of activated carbon were added, and after stirring for 1 h, it was filtered.

[0026] The product was: (C 16 H 33 )(CH3)2SiO-[(CH3)2SiO]1(CH3)2Si(C 16 H 33 ), and the product was marked as CH-1.

[0027] Example 2

[0028] Under nitrogen purge, 202.0 grams of 1-dodecene and 102 milligrams of Karstedt catalyst were added to a four-necked flask at 25 °C. While stirring, 104.3 grams of H(CH3)2SiO-[(CH3)2SiO]1(CH3)2SiH were added dropwise at 40 °C, controlling the reaction liquid temperature to be within the range of 80-120 °C. After the addition was completed, the reaction was continued for 4 hours under stirring. The product was distilled under reduced pressure to remove residual 1-dodecene. 31 grams of activated carbon were added, and after stirring for 1 h, it was filtered.

[0029] H(CH3)2SiO-[(CH3)2SiO]1(CH3)2SiH, controlling the reaction liquid temperature to be within the range of 80-120 °C. After the addition was completed, the reaction was continued for 4 hours under stirring. The product was distilled under reduced pressure to remove residual 1-hexadecene. 37 grams of activated carbon were added, and after stirring for 1 h, it was filtered.

[0030] The product was: (C 12 H 25 )(CH3)2SiO-[(CH3)2SiO]1(CH3)2Si(C 12 H 25 ), and the product was marked as CH-2.​

[0031] Example 3

[0032] Under a nitrogen purge, 269.3 g of 1 -hexadecene and 164 mg of Karstedt catalyst were added to a four-necked flask at 25°C. While stirring, 222.5 g of

[0033] H(CH3)2SiO-[(CH3)2SiO]1(CH3)2SiH, controlling the reaction temperature in the range of 80-120°C. After the addition was complete, stirring was continued for 4 hours. The product was distilled under reduced pressure to remove residual 1 -hexadecene. 49 g of activated carbon was added, and after stirring for 1 h, it was filtered.

[0034] The product was: (C 17 H 17 )(CH3)2SiO-[(CH3)2SiO]

[0035] Hydrogen-containing siloxane: H(CH3)2SiO-[(CH3)2SiO] 4.19 (CH3)2SiH (n = 4.19) was prepared.

[0036] In a dry 2000 mL three-necked flask, 720 g of octamethylcyclotetrasiloxane (D4), 320 g of tetramethyl disiloxane, and then 20 g of concentrated sulfuric acid were added, and stirred for 6 hours, neutralized with 40 g of sodium carbonate, filtered, dried, and tested for viscosity 2 mm 2 / s, hydrogen content 0.45%.

[0037] Example 4

[0038] Under a nitrogen purge, 269.3 g of 1 -hexadecene and 164 mg of Karstedt catalyst were added to a four-necked flask at 25°C. While stirring, 222.5 g of

[0039] H(CH3)2SiO-[(CH3)2SiO] 4.19 (CH3)2SiH, controlling the reaction temperature in the range of 80-120°C. After the addition was complete, stirring was continued for 4 hours. The product was distilled under reduced pressure to remove residual 1 -hexadecene. 49 g of activated carbon was added, and after stirring for 1 h, it was filtered.

[0040] The product was: (C 16 H 33 )(CH3)2SiO-[(CH3)2SiO] 4.19 (CH3)2Si(C 16 H 33 ), product labeled CH-4.

[0041] Example 5

[0042] Under a nitrogen purge, 202.0 grams of 1-dodecene and 141 milligrams of Karstedt catalyst were added to a four-necked flask at 25°C. While stirring, 222.5 grams of

[0043] H(CH3)2SiO-[(CH3)2SiO]4(CH3)2SiH, controlling the temperature of the reaction liquid to be within the range of 80-120°C. After the addition was complete, stirring was continued for 4 hours. The product was distilled under reduced pressure to remove residual 1-dodecene. 42g of activated carbon was added, and after stirring for 1 hour, it was filtered.

[0044] The product was: (C 12 H 25 )(CH3)2SiO-[(CH3)2SiO] 4.19 (CH3)2Si(C 12 H 25 ), and the product was labeled CH-5.

[0045] Example 6

[0046] Under a nitrogen purge, 134.6 grams of 1-octene and 118 milligrams of Karstedt catalyst were added to a four-necked flask at 25°C. While stirring, 222.5 grams of

[0047] H(CH3)2SiO-[(CH3)2SiO]4(CH3)2SiH, controlling the temperature of the reaction liquid to be within the range of 80-120°C. After the addition was complete, stirring was continued for 4 hours. The product was distilled under reduced pressure to remove residual 1-octene. 35g of activated carbon was added, and after stirring for 1 hour, it was filtered.

[0048] The product was: (C8H 17 )(CH3)2SiO-[(CH3)2SiO] 4.19 (CH3)2Si(C8H 17 ), and the product was labeled CH-6.

[0049] Hydrogen-containing siloxane: H(CH3)2SiO-[(CH3)2SiO] 4.93 (CH3)2SiH (n = 4.93) was prepared.

[0050] In a dry 2000 mL three-necked flask, 760 grams of octamethylcyclotetrasiloxane (D4), 280 grams of tetramethyl disiloxane, and then 20 grams of concentrated sulfuric acid were added, and under stirring, it was reacted for 6 hours, neutralized with 40 grams of sodium carbonate, filtered, dried, and tested for viscosity 5 mm 2 / s, hydrogen content 0.40%.

[0051] Example 7

[0052] Under a nitrogen purge, 269.3 grams of 1-hexadecene and 173 milligrams of Karstedt catalyst were added to a four-necked flask at 25°C. While stirring, 250.0 grams of

[0053] H(CH3)2SiO-[(CH3)2SiO] 4.93 (CH3)2SiH, controlling the reaction temperature to be in the range of 80-120°C. After the addition was complete, stirring was continued for 4 hours. The product was distilled under reduced pressure to remove residual 1-hexadecene. 51 g of activated carbon was added, and after stirring for 1 h, it was filtered.

[0054] The product was: (C 16 H 33 )(CH3)2SiO-[(CH3)2SiO] 4.93 (CH3)2Si(C 16 H 33 ), product labeled CH-7.

[0055] Example 8

[0056] Under a nitrogen purge, 202.0 grams of 1-dodecene and 150 milligrams of Karstedt catalyst were added to a four-necked flask at 25°C. While stirring, 250.0 grams of

[0057] H(CH3)2SiO-[(CH3)2SiO] 4.93 (CH3)2SiH, controlling the reaction temperature to be in the range of 80-120°C. After the addition was complete, stirring was continued for 4 hours. The product was distilled under reduced pressure to remove residual 1-dodecene. 45 g of activated carbon was added, and after stirring for 1 h, it was filtered.

[0058] The product was: (C 12 H 25 )(CH3)2SiO-[(CH3)2SiO] 4.93 (CH3)2Si(C 12 H 25 ), product labeled CH-8.

[0059] Example 9

[0060] Under a nitrogen purge, 134.6 grams of 1-octene and 128 milligrams of Karstedt catalyst were added to a four-necked flask at 25°C. While stirring, 250.0 grams of

[0061] H(CH3)2SiO-[(CH3)2SiO] 4.93(CH3)2SiH, controlling the temperature of the reaction liquid to be within the range of 80 to 120°C. After the addition, stirring is continued for 4 hours. The product is distilled under reduced pressure to remove residual 1-octene. 38 g of activated carbon is added, and after stirring for 1 hour, it is filtered.

[0062] The product is: (C8H 17 )(CH3)2SiO-[(CH3)2SiO] 4.93 (CH3)2Si(C8H 17 ), and the product is labeled CH-9.

[0063] The product is: (C8H 11.03 (CH3)2SiH (n = 11.03) is prepared.

[0064] In a dry 2000 mL three-necked flask, 900 grams of octamethylcyclotetrasiloxane (D4), 145 grams of hydrogen-containing bis-capped, and then 20 grams of concentrated sulfuric acid are added, and after stirring for 6 hours, it is neutralized with 40 grams of sodium carbonate, filtered, dried, and tested for viscosity 9 mm 2 / s, and hydrogen content 0.21%.

[0065] Example 10

[0066] Under nitrogen purge, 202.0 grams of 1-dodecene and 225 milligrams of Karstedt catalyst are added to a four-necked flask at 25°C. While stirring, 475.0 grams of

[0067] The product is: (C 11.03 (CH3)2SiH, controlling the temperature of the reaction liquid to be within the range of 80 to 120°C. After the addition, stirring is continued for 4 hours. The product is distilled under reduced pressure to remove residual 1-dodecene. 67 g of activated carbon is added, and after stirring for 1 hour, it is filtered.

[0068] The product is: (C 12 H 25 )(CH3)2SiO-[(CH3)2SiO] 11.03 (CH3)2Si(C 12 H 25 ), and the product is labeled CH-10.

[0069] Example 11

[0070] Under nitrogen purge, 134.6 grams of 1-octene and 203 milligrams of Karstedt catalyst are added to a four-necked flask at 25°C. While stirring, 475.0 grams of

[0071] H(CH3)2SiO-[(CH3)2SiO] 11.03 (CH3)2SiH, controlling the temperature of the reaction liquid to be within the range of 80 to 120°C. After the addition, stirring is continued for 4 hours. The product is distilled under reduced pressure to remove residual 1-octene. 61 g of activated carbon is added, and after stirring for 1 h, it is filtered.

[0072] The product is: (C8H 17 )(CH3)2SiO-[(CH3)2SiO] 11.03 (CH3)2Si(C8H 17 ), the product is labeled CH-11.

[0073] Hydrogen-containing siloxane: H(CH3)2SiO-[(CH3)2SiO] 12.38 (CH3)2SiH (n = 12.38) is prepared.

[0074] In a dry 2000 mL three-necked flask, 925 grams of octamethylcyclotetrasiloxane (D4), 145 grams of hydrogen-containing bis-capped, then 20 grams of concentrated sulfuric acid are added, and reacted for 6 hours under stirring, neutralized with 40 grams of sodium carbonate, filtered, dried, and tested for viscosity 11 mm 2 / s, hydrogen content 0.19%.

[0075] Example 12

[0076] Under nitrogen purge, 101.0 grams of 1-dodecene and 121 milligrams of Karstedt catalyst are added to a four-necked flask at 25°C. While stirring, 263.0 grams of

[0077] H(CH3)2SiO-[(CH3)2SiO] 12.38 (CH3)2SiH, controlling the temperature of the reaction liquid to be within the range of 80 to 120°C. After the addition, stirring is continued for 4 hours. The product is distilled under reduced pressure to remove residual 1-dodecene. 38 g of activated carbon is added, and after stirring for 1 h, it is filtered.

[0078] The product is: (C 12 H 25 )(CH3)2SiO-[(CH3)2SiO] 12.38 (CH3)2Si(C 12 H 25 ), the product is labeled CH-12.

[0079] Example 13

[0080] Under nitrogen purge, 67.3 grams of 1-octene and 110 milligrams of Karstedt catalyst are added to a four-necked flask at 25°C. While stirring, 263.0 grams of

[0081] H(CH3)2SiO-[(CH3)2SiO] 12.38 (CH3)2SiH, controlling the temperature of the reaction liquid to be within the range of 80 to 120°C. After the addition, stirring is continued for 4 hours. The product is distilled under reduced pressure to remove the residual 1-octene. 43 g of activated carbon is added, and after stirring for 1 h, it is filtered.

[0082] The product is: (C8H 17 )(CH3)2SiO-[(CH3)2SiO] 12.38 (CH3)2Si(C8H 17 ), and the product is labeled CH-13.

[0083] Hydrogen-containing siloxane: H(CH3)2SiO-[(CH3)2SiO] 17.45 (CH3)2SiH (n = 17.45) is prepared.

[0084] In a dry 2000 mL three-necked flask, 933 grams of octamethylcyclotetrasiloxane (D4), 150 grams of hydrogen-containing bis-capped, and then 20 grams of concentrated sulfuric acid are added, and after stirring for 6 hours, it is neutralized with 40 grams of sodium carbonate, filtered, dried, and tested for viscosity 14 mm 2 / s, and hydrogen content 0.14%.

[0085] Example 14

[0086] Under nitrogen purge, 67.3 grams of 1-octene and 141 milligrams of Karstedt catalyst are added to a four-necked flask at 25°C. While stirring, 357.2 grams of

[0087] H(CH3)2SiO-[(CH3)2SiO] 17.45 (CH3)2SiH, controlling the temperature of the reaction liquid to be within the range of 80 to 120°C. After the addition, stirring is continued for 4 hours. The product is distilled under reduced pressure to remove the residual 1-octene. 43 g of activated carbon is added, and after stirring for 1 h, it is filtered.

[0088] The product is: (C8H 17 )(CH3)2SiO-[(CH3)2SiO] 17.45 (CH3)2Si(C8H 17 ), and the product is labeled CH-14.

[0089] Hydrogen-containing siloxane: H(CH3)2SiO-[(CH3)2SiO] 20.66 (CH3)2SiH (n = 20.66) is prepared.

[0090] In a dry 2000 mL three-necked flask, 950 grams of octamethylcyclotetrasiloxane (D4), 150 grams of hydrogen-containing double caps, then 20 grams of concentrated sulfuric acid were added, and reacted for 6 hours under stirring, neutralized with 40 grams of sodium carbonate, filtered, dried, and tested for viscosity 15 mm 2 / s, hydrogen content 0.12%.

[0091] Example 15

[0092] Under nitrogen purging, 67.3 grams of 1-octene and 161 milligrams of Karstedt catalyst were added to a four-necked flask at 25°C. While stirring, 416.7 grams of

[0093] H(CH3)2SiO-[(CH3)2SiO] 15.04 (CH3)2SiH, and the reaction liquid temperature was controlled in the range of 80-120°C. After the addition was completed, stirring was continued for 4 hours. The product was distilled under reduced pressure to remove the residual 1-octene. 48g of activated carbon was added, and after stirring for 1h, it was filtered.

[0094] The product was: (C8H 17 )(CH3)2SiO-[(CH3)2SiO] 20.66 (CH3)2Si(C8H 17 ), and the product was labeled as CH-15.

[0095] For the above examples, the test results are shown in Table 1.

[0096] As can be seen from Table 1, the alkane-modified organosiloxane has lower viscosity (except for CH-7, CH-12, CH-15 viscosity > 20 mm 2 / s) and higher flash point (except for CH-3 flash point < 150°C), low surface tension, good flowability, more comprehensive coverage, better heat dissipation effect, and good compatibility with materials in the data center, without swelling and other damage to related materials, with safety and long-term effectiveness. It is suitable for making cooling liquid.

[0097] Comparing CH-1, CH-4, CH-7, when the number of alkane carbon atoms is 16, n = 1-4 is preferred.

[0098] Comparing CH-2, CH-5, CH-8, CH-10, CH-12, when the number of alkane carbon atoms is 12, n = 1-11 is preferred.

[0099] Comparing CH-3, CH-6, CH-9, CH-11, CH-13, CH-14, CH-15, when the number of alkane carbon atoms is 8, n = 2-20 is preferred.

[0100] When the examples in Table 1 (CH-7, CH-12, CH-15 viscosity > 20 mm 2 / s, CH-3 flash point < 150°C except) alone are suitable as coolants. In the same way, their combination with other examples gives suitable coolants with viscosity < 20 mm 2 / s, flash point > 150°C. We therefore prefer n = 1-20, the number of carbon atoms in the alkane being 8-16.

[0101]

[0102]

[0103] The above-described examples only express several embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application. It should be pointed out that for those skilled in the art, according to the above described technical solutions and ideas, other various corresponding changes and deformations can also be made, and all these changes and deformations should belong to the protection scope of the claims of the present application.

[0104] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0105] The above-described examples only express several embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application. It should be pointed out that for those skilled in the art, under the premise of not departing from the concept of the present application, several deformations and improvements can also be made, which belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A single-phase immersion modified organosiloxane coolant, characterized by, R1(CH3)2SiO-[(CH3)2SiO] n (CH3)2SiR2; wherein n = 1-20, R1, R2 = alkyl group of 8-16.

2. A single phase immersion modified organosiloxane coolant according to claim 1, wherein, which has a flash point of > 150°C and a viscosity of < 20 mm 2 at 25°C.

3. A process for the preparation of a single-phase immersion modified organosiloxane coolant, characterized in that, The olefin and the catalyst are mixed at 20-30℃ under nitrogen purging, the temperature is raised to 35-45℃, the hydrogen-containing siloxane is added drop by drop, the temperature of the reaction solution is controlled in the range of 60-150℃, after the addition is completed, the stirring is continued, after the reaction is completed, the residual olefin is removed, and the final product is obtained.

4. A single phase immersion modified organosiloxane coolant according to claim 3, wherein, The alkyl group has 8-16 carbon atoms, which can be linear or branched or phenyl-substituted alkyl.

5. A single phase immersion modified organosiloxane coolant according to claim 3, wherein, said hydrogen-containing siloxane is H(CH3)2SiO-[(CH3)2SiO] n (CH3)2SiH; n = 1-20.

6. A process for the preparation of a single phase immersion modified organosiloxane coolant fluid according to claim 3, characterised in that, The metal catalyst is a complex containing palladium, rhodium or platinum, and the addition amount is 1-300 ppm; preferably, the metal catalyst is a complex of platinum, including one or more of isopropyl alcohol solution of chloroplatinic acid, platinum-divinyl disiloxane Karstedt platinum catalyst, platinum-allyl polyether Karstedt catalyst and supported solid platinum catalyst, and the addition amount is 1-100 ppm.

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