KR20040029881A - Polyisocyanurate foam for ultra-low-temperature insulation of pipe, the process for producing it, and insulating material by using it - Google Patents

Abstract

PURPOSE: A polyurethane foam for warming and cooling an ultralow temperature pipe and an insulator using the polyurethane are provided, to improve the heat insulation and the mechanical properties even at an ultralow temperature and the flame retardancy. CONSTITUTION: The polyurethane foam is obtained by reacting a polyol component and an isocyanate compound in the presence of a foaming agent, a catalyst and other additives, wherein the polyol component comprises 40-60 wt% of a polyol obtained by the addition of sorbitol and propylene oxide or ethylene oxide, 20-40 wt% of a polyol obtained by the polymerization of phthalic acid and an alcohol, 10-30 wt% of a polyol obtained by the addition of glycol and propylene oxide or ethylene oxide, and 10-30 wt% of a polyol obtained by the addition of pentaerythritol and propylene oxide or ethylene oxide, and the isocyanate compound is a polymeric MDI having a functional group of 2.6-3.0.

Description

POLYISOCYANURATE FOAM FOR ULTRA-LOW-TEMPERATURE INSULATION OF PIPE, THE PROCESS FOR PRODUCING IT, AND INSULATING MATERIAL BY USING IT}

The present invention relates to a polyurethane foam for pipe cold insulation using water or HFCs as a foaming agent, and to a rigid polyurethane foam and a heat insulator not only exhibiting excellent thermal insulation and mechanical properties even at ultra low temperatures, but also having reinforced flame retardant wires.

LNG, which has recently been spotlighted as clean energy, is stored and transported in ultra-low temperature conditions. Therefore, LNG storage tanks and pipes, which are transportation media, should be insulated to minimize losses during transportation. In particular, since the cryogenic material below -165 ° C flows in the LNG transportation pipeline, the material having a very low coefficient of linear expansion should be used as an insulator so that the insulation of the LNG transportation pipe does not contract or expand due to temperature difference even when it is in contact with the cryogenic temperature. .

In addition, since LNG may cause a large accident in the fire due to the inherent flammability, it is essential to select a material having flame retardancy as a heat insulating material when insulating the LNG transport pipeline.

In the prior art, many polyurethane foams were used. For this reason, polyurethane foam is not only excellent in heat insulation and easy to process, but also has excellent adhesion to all materials used as cryogenic pipe insulation materials such as aluminum foil and asphalt paper, as it does not generate cracks and shrinkage even at very low temperatures. Because. In addition, polyurethane foam is easy to process and can be manufactured according to all pipe dimensions required at LNG take-up base.

However, conventional polyurethane coolant used CFC-11 (trichloro monofluoroethane) or HCFC-141b (dichloro monofluoroethane) as a blowing agent during the manufacturing process. The blowing agent was defined in 1989 under the Montreal Protocol, which is an international convention regulating the production and use of environmentally harmful substances to destroy the ozone layer and cause global warming. In developed countries, CFC-11 was already banned from use and production in 1995, and HCFC-141b will be available under the Montreal Protocol for 2030, but as part of efforts to protect the global environment, the EU and the US In developed countries such as Japan and Japan, the regulations on the use of HCFC-141b are set to 2003 in their own regulations, after which the production, import, export and use of the substances are prohibited.

Therefore, HFCs (hydrofluorocarbons), cyclopentane, water, and the like have recently been in the spotlight as blowing agents to replace CFC-11 and HCFC-141b. However, these alternative blowing agents are basically inferior to the thermal insulation of the blowing agent itself compared to conventional CFC-11 or HCFC-141b. In other words, when the polyurethane is molded with this foaming agent, the mechanical strength becomes weak, causing severe shrinkage at low temperatures, poor adhesion to the face material, and brittleness. Physical properties are inferior to foam.

For example, referring to Korean Patent Registration No. 2783654 "Polyisocyanurate Foam" filed in 1998 by the present applicant, when the foaming agent is used as the foaming agent in the foam manufacturing process, the viscosity of the undiluted solution is increased. Cracking occurred due to poor properties or increased internal foaming rate. In addition, there is a problem that the thickness of the heat insulating material to increase when using the heat insulation is worse than the conventional.

The present invention has been devised to solve the above problems, using water or HFC as a foaming agent, but excellent thermal insulation and easy processing, such as conventional polyurethane foam using a conventional foam material, cracking even at very low temperatures And it does not shrink, the dimensional stability and flame retardancy is good to provide a cryogenic polyurethane foam for cryogenic pipe excellent excellent in various face materials and adhesive strength.

In the polyurethane foam for cryogenic pipe insulation according to the present invention and the heat insulating material using the same according to the present invention for achieving the above object, in the polyurethane foam produced by reacting a polyol component and an isocyanate component in the presence of a blowing agent, a reaction catalyst and other additives, The polyol component is (a) 40 to 60% by weight of polyol obtained by adding propylene oxide or ethylene oxide to sorbitol (b) 20 to 40% by weight of polyol obtained by polymerizing alcohol to phthalic acid (c) propylene oxide or ethylene to glycol 10-30 weight% of polyols obtained by adding an oxide (d) It is a mixed polyol composition containing 10-30 weight% of polyols obtained by adding a propylene oxide and ethylene oxide to pentaerythritol, The said isocyanate component is 2.6-3.0 functional groups. Phosphorus polymeric MDI.

Preferably, the average OH value of the mixed polyol composition is 400 to 500, and the average NCO% of the isocyanate component includes 29 to 32.

In addition, it is preferable that NCO / OH which is NCO ratio of the said isocyanate component with respect to OH of the said polyol component contains 1.0-1.5.

In addition, the blowing agent preferably includes using 2.0 to 5.0 parts by weight of water based on 100 parts by weight of polyol component, or using 0.5 to 1.5 parts by weight of water and 15 to 30 parts by weight of HFC-365mfc based on 100 parts by weight of polyol component. do.

Preferably, the polyurethane foam of the present invention as a additive includes a crosslinking agent for shortening the strength reinforcement and curing time and a flame retardant for reinforcing the flame retardancy.

In addition, the present invention preferably comprises a heat insulating material and a pipe for LNG transportation using the polyurethane foam.

Hereinafter, look at the composition for producing a polyurethane foam according to the present invention. More specifically, it is generally hard polyurethane by reacting a polyol component having a molecular weight of 250 to 650 having at least two hydroxyl groups with a mixture of a polyisocyanate component having at least two isocyanate groups with a blowing agent, a catalyst and other additives. While maintaining excellent thermal insulation, which is a characteristic of the foam, a rigid polyurethane foam having high strength and excellent low temperature dimensional stability even at extremely low temperatures of -165 ° C. and lowered flame retardancy is prepared.

In particular, the polyurethane foam composition of the present invention is 30 to 50 parts by weight of the polyol or more of the functional group 2 or more with respect to 100 parts by weight of the polymeric MDI of 2.5 or more functional groups, 0.2 to 1.0 parts by weight of the reaction catalyst, 5 to 15 parts by weight of the blowing agent and other additives 5 to 15 parts by weight of the polyol component, preferably the polyol component (a) 40 to 60% by weight of a polyol obtained by adding propylene oxide or ethylene oxide (b) 20 to 40% by weight of a polyol obtained by polymerizing alcohol to phthalic acid ( c) 10-30 weight% of polyols obtained by adding a propylene oxide and ethylene oxide to glycol (d) It is a mixed polyol composition containing 10-30 weight% of polyols obtained by adding a propylene oxide and ethylene oxide to pentaerythritol. In addition, the isocyanate component is preferably a polymeric MDI having a functional group of 2.6 to 3.0.

In the mixed polyol composition, the sorbitol component is effective in improving the cryogenic dimensional stability and the mechanical strength of the foam, and the phthalic acid component contributes to the improvement of the thermal conductivity and the uniform formation of foam bubbles. In addition, the glycol component is excellent in the viscosity lowering effect of the stock solution and contributes to increase the fluidity and adhesion during foaming, pentaerythritol component improves the flowability and mechanical strength of the stock solution.

The average 0H value of the mixed polyol component having the above characteristics is preferably 400 to 500 for producing a stable rigid polyurethane foam. If the average OH value of the polyol composition is 400 or less, the cryogenic dimensional stability and the mechanical strength of the product is lowered, and if the average OH value is more than 500, the cracking and thermal conductivity are increased, and the average OH value outside the above-mentioned proper range is The cause of the defect is a decrease in productivity.

Meanwhile, the polymeric MDI (polymethylene polyphenyldiisocyanate) component to be reacted with the mixed polyol composition uses a functional group of 2.6 to 3.0, wherein the polymeric MDI component has an average NCO% of 29% to 32%. desirable. The reason is that the polymeric MDI component is effective for improving mechanical strength, but if the NCO% of the polymeric MDI component is 29% or less, the low temperature dimensional stability is lowered, and if it is 32% or more, fluidity is lowered.

The reaction ratio of the polymeric MDI component and the mixed polyol component is preferably NCO / OH, which is a ratio of NCO of the polymeric MDI component and OH of the polyol, of 1.0 to 1.5, more preferably 1.1 to 1.3. When the ratio of NCO / OH is 1.0 or less, the polyurethane foam is weakened, so that low-temperature dimensional stability is lowered and mechanical strength is reduced. When the ratio of NCO / 0H is more than 1.5, a foaming phenomenon occurs.

Therefore, when the blending ratio of the polyol component and the polymeric MDI component to be reacted is outside the above range, the object of the present invention cannot be achieved.

According to the present invention, a polyurethane foam can be obtained by reacting a blowing agent, a reaction catalyst and other additives using a mixed polyol component having a special composition as described above and a polymeric MDI component as a basic raw material.

Blowing agents generally used in polyurethane foams are water, carboxylic acids, fluorocarbon-based blowing agents or inert gases such as carbon dioxide and air.

According to the present invention, as the blowing agent, HFCs as water or fluorocarbon blowing agents are used. use. When water is used alone, 2.0 to 5.0 parts by weight based on 100 parts by weight of the polyol component is employed, and when water and HFC are mixed, 0.5 to 1.5 parts by weight of water and 15 to 30 parts by weight of HFC are preferable. In this case, when water is used alone as the blowing agent, the desired density does not come out when the water usage is 2.0 or less, and when the water content is 5.0 or more, the insulation of the polyurethane foam is inferior, and the foam is brittle, and the adhesion to the face member is also weakened.

Reaction catalysts used in the present invention are typical catalysts that can be used to obtain polyurethane foams, for example triethylamine, tripropylamine, triisopropanolamine, tributylamine, trioctylamine, hexadecyldimethylamine, N Methyl morpholine, N-ethyl morpholine, N-octadecyl morpholine, monoethanolamine, diethanolamine, dimethylethanolamine, triethanolamine, N-methyl diethanolamine, N, N-dimethylethanolamine, diethylene Triamine, N, N, N ', N'-tetramethylbutanediamine, N, N, N', N'-tetramethyl-1,3-butanediamine, N, N, N ', N'-tetraethyl Hexamethylenediamine, bis [2- (N, N-dimethylamino) ethyl] ether, N, N'-dimethylbenzylamine, N, N-dimethylcyclohexylamine, N, N, N ', N', n ' -Pentamethyldiethylenetriamine, triethylenediamine, formic acid and other salts of triethylenediamine, amino groups and oxyalkylene adducts of the first and second amines, N, N-dialkylpipera Acids and the like aza ring compounds, a number of the N, N ', N'- trialkyl-amino-alkyl-hexahydro-triazol jinryu of β- aminocarbonyl-amine-containing catalyst of the catalyst and the like.

These catalysts are used individually or in mixture, The usage-amount is 0.3-1.5 weight part with respect to 100 weight part of polyol components, More preferably, it is 0.5-1.2 weight part.

In addition, as the surfactant used in the present invention, a polyalkylene glycol silicone copolymer is used as the organosilicon compound generally used in polyurethane foam production. At this time, the amount of the surfactant used is preferably 1.0 to 4.0 parts by weight, more preferably 1.5 to 3.0 parts by weight based on 100 parts by weight of the polyol component.

In addition, in the polyurethane foam of the present invention, a crosslinking agent may be used to reinforce the strength of the polyurethane foam and to shorten the curing time. Generally as a crosslinking agent, the well-known crosslinking agent used for manufacture of a polyurethane foam is used. For example, compounds, such as ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, glycerol, butanediol, are mentioned, These can also be used individually or in mixture of 2 or more types. In particular, a preferable crosslinking agent is polyethylene glycol or butanediol, and the usage-amount is 2-15 weight part with respect to 100 weight part of polyol components, More preferably, it is 3-5 weight part.

In addition, a flame retardant may be added to enhance the flame retardancy of the rigid polyurethane foam of the present invention. Examples of the flame retardant used in the present invention include tris (2-chloroethyl) phosphate, tris (chloropropyl) phosphate, tris (dipropopropyl) phosphate, and the like. When the flame retardant is used, the amount thereof is preferably 10 to 20 parts by weight, more preferably 5 to 15 parts by weight based on 100 parts by weight of the polyol component.

Other fillers commonly used in urethane chemistry, stabilizers such as antioxidants, ultraviolet absorbers and the like can be added as necessary.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail with a comparative example and an Example. Unless otherwise specified in the following Examples and Comparative Examples, "part" and "%" are by weight.

[Comparative Examples 1 and 2]

In this comparative example, 100 parts of a polyol component having an average OH value of 370-460 (25 wt% of sorbitol + PO / EO, 40 wt% of phthalic anhydride + OH, 15-20 wt% of glycol + PO / EO, pentaerythritol + 2.1-2.5 parts of water was used as the mixed polyol component which consists of 15-20 weight% of PO / EO) and a blowing agent. For example, in Comparative Example 1, 2.5 parts of water was used to adjust the density to about 45 Kg / m ³ , and Comparative Example 2 used 2.1 parts of water to adjust the density to about 55 Kg / m ³ . In Comparative Example 1, 175 parts of polymeric MDI having an average NCO% of 29 to 32 were used, and in Comparative Example 2, foaming and curing were performed to prepare a sample of polyurethane foam using 168 parts. Table 1 shows.

[Comparative Examples 3 and 4]

In this comparative example, 100 parts of a polyol component having an average OH value of 370-460 (25 wt% of sorbitol + PO / EO, 30 wt% of phthalic anhydride + OH, 10-15 wt% of glycol + PO / EO, pentaerythritol + Mixed polyol component consisting of 30 to 35% by weight of PO / EO) and 1.0 part of water and HCFC-141b were used as the blowing agent. In Comparative Example 3, 20 parts of HCFC-141b and 0.8 parts of water were used to adjust the density to about 45 Kg / m ³ , and in Comparative Example 4, 16 parts of HCFC-141b and 0.7 parts of water were adjusted to adjust the density to 55 Kg / m ^3. Wealth was used. In Comparative Example 3, 148 parts of polymeric MDI having an average NCO% of 29 to 32 were used, and in Comparative Example 4, 147 parts of foaming and curing were performed to prepare a sample of the polyurethane foam. Table 1 shows.

Example 1

In Example 1, 100 parts of a polyol component having an average OH value of 400 to 500 (40 wt% of sorbitol + PO / EO, 27 wt% of phthalic anhydride + OH, 15 wt% of glycol + PO / EO, and pentaerythritol + PO / Polyether component consisting of 12% by weight of EO and 3% by weight of a crosslinking agent) and 2.5 parts of water as a blowing agent, and a sample of polyurethane foam was prepared using 175 parts of polymeric MDI having an average NC0% of 29 to 32. In order to perform foaming and curing, the results are shown in Table 1.

Example 2

In Example 2, 100 parts of a polyol component having an average OH value of 400 to 500 (40 wt% of sorbitol + PO / EO, 27 wt% of phthalic anhydride + OH, 10 wt% of glycol + PO / EO, and pentaerythritol + PO / Polyethylene component consisting of 20% by weight and 3% by weight of a crosslinking agent) and 2.1 parts of water as a blowing agent, and a sample of polyurethane foam was prepared using 168 parts of polymeric MDI having an average NC0% of 29 to 32. In order to perform foaming and curing, the results are shown in Table 1.

Example 3

In Example 3, 100 parts of a polyol component having an average OH value of 400 to 500 (30 wt% of sorbitol + PO / EO, 21 wt% of phthalic anhydride + OH, 15 wt% of glycol + PO / EO, and pentaerythritol + PO / EO 30% by weight of mixed polyol component and 4% by weight of crosslinking agent) and 0.8 parts of water and 20 parts of HFC-365mfc as blowing agent, and 148 parts of polymeric MDI having an average NC0% of 29 to 32. Foaming and curing were carried out to prepare a sample of urethane foam and the results are shown in Table 1.

Example 4

As shown in Table 1, 100 parts of a polyol component having an average OH value of 400 to 500 (40 wt% of sorbitol + PO / EO, 21 wt% of phthalic anhydride + OH, 15 wt% of glycol + PO / EO, pentaeryte Mixed polyol component consisting of 20% by weight of lithol + PO / EO and 4% by weight of crosslinking agent), and 0.7 parts of water and 16 parts of HFC-365mfc as foaming agents, and 147 parts of polymeric MDI having an average NC0% of 29 to 32 Foaming and curing were carried out to prepare samples of polyurethane foam using the results shown in Table 1.

In addition, the comparative results of the comparative example and the embodiment are shown in the section of 'physical properties' of Table 1, the physical properties are defined as described below.

1.Free foam density: Foam density of foam foamed in injection foam into open box of plywood with internal dimension 200 × 200 × 200mm (kg / ㎥)

2. Density of product: Foam density of actual product (kg / ㎥)

3. Thermal Conductivity: Measured using the Enter Thermal Conductivity Meter (Model No. 2031) (according to ASTM C-518).

4. Compressive strength: measured using Lloyd's universal testing machine at room temperature and ultra low temperature (according to ASTM D-1621)

5. Tensile strength: measured using Lloyd's universal testing machine at room temperature and ultra low temperature (according to ASTM D-1623)

6. Independent bubble ratio: Based on ASTM D-2856

7. Hygroscopicity: Based on KSM 3809

8. Low temperature impact test: Check for crack occurrence after immersion in liquid nitrogen for 1 hour (-195 ℃)

9. Flame Retardant: Based on JIA AS-9511

division ingredient Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 Example 3 Example 4 Polyol Sorbitol + PO / EO 25 25 25 25 40 40 30 40 Phthalic anhydride + OH 40 40 30 30 27 27 21 21 Glycol + PO / EO 20 15 15 10 15 10 15 15 Pentaerythritol + PO / EO 15 20 30 35 12 20 30 20 Crosslinking agent - - - - 3 3 4 4 blowing agent HFC-365mfc - - 20 16 - - 20 16 water 2.5 2.1 0.8 0.7 2.5 2.1 0.8 0.7 Surfactants 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 catalyst 0.8 0.7 1.2 1.1 0.8 0.7 1.2 1.1 Flame retardant 10 10 10 10 10 10 10 10 Polymeric MDI 175 168 148 147 175 168 148 147 Foam property Free Foam Density (kg / m ³ ) 41 54 45 55 43 55 44 54 Product Density (kg / m ³ ) 43 55 46 57 45 56 46 56 Thermal Conductivity (kcal / m · hr · ℃) 0.0310 0.0320 0.0290 0.0295 0.0200 0.0200 0.0170 0.0172 Compressive strength (kg / m ³ ) 20 ℃ 1.2 1.6 1.3 1.7 2.2 2.7 2.3 2.7 -170 ℃ 2.3 2.8 2.5 2.9 3.4 4.1 3.5 4.3 Tensile strength (kg / m ³ ) 20 ℃ 2.1 2.6 2.2 2.5 3.0 3.6 3.1 3.7 -170 ℃ 2.4 2.9 2.6 3.1 3.5 4.1 3.5 4.4 Independent Bubble Rate (%) 92 94 93 95 94 95 94 96 Hygroscopicity (g / 100cm ² ) 1.5 1.4 1.7 1.3 1.1 1.0 1.2 1.1 Low temperature shock crack - crack - No crack Flame retardant (Combustion distance: mm Burning time: sec) 4569 3261 5281 4079 3059 2863 4772 3676

PO: propylene oxide, EO; Ethylene oxide, polymeric MDI: polymethylene polyphenyl diisocyanate, HCFC-141b: dichloromonofluoroethane.

As described above, the polyurethane foam obtained by the present invention has a density of 40 to 60 kg / m 3, a thermal conductivity of 0.02 kcal / m · hr · ° C. or less, an independent bubble ratio of 90% or more, and a compressive strength at room temperature and ultra low temperature of −170 ° C. It is preferably at least 2.2 kg / cm 2 and 3.1 kg / cm 2, and the tensile strength is preferably at least 2.7 kg / cm 2 and 3.1 kg / cm 2 at room temperature and ultra low temperature, respectively. In particular, the flame retardance of the polyurethane foam of the present invention has self-extinguishing according to the provisions of JIS A-9511.

Referring to Table 1, Comparative Examples 1 to 4 is a result of applying the water and HFC-365mfc, which is an alternative blowing agent to the polyol composition applied when the blowing agent is HCFC-141b. In particular, the free foam density of Comparative Examples 1 and 3 has a satisfactory result of about 45kg / ㎥, it can be seen that the thermal conductivity is not good because the thermal conductivity is higher than 0.0310kcal / m · hr · ℃. . In addition, the mechanical properties such as compressive strength and tensile strength are significantly reduced at room temperature and ultra low temperature, such that problems such as cracking may occur when used as a cryogenic insulation for cryogenic temperatures.

In addition, Comparative Example 2 and Comparative Example 4 has a polyol composition similar to Comparative Examples 1 and 3, but the composition of the blowing agent was changed to increase the density of the polyurethane. Since the density of polyurethane specifications currently commonly used is 40 to 60 kg / m 3, the composition of the foaming agent to suit this is preferably 2.0 to 5.0 parts by weight of water based on 100 parts by weight of polyol component when only water is used. When mixed with water and HFC-365mfc, it is preferable to use 0.5 to 1.5 parts by weight of water and 15 to 30 parts by weight of HFC-365mfc based on 100 parts by weight of the polyol component. Deviation from the above values deviates from the specification of the required density. When the polyurethane foam was prepared in the composition of Comparative Example 2 and Comparative Example 4 by mixing the foaming agent as described above, although the physical properties are improved compared to the Comparative Examples 1 and 3, the required physical properties are still not satisfied. Not suitable for use as cryogenic insulation.

On the other hand, in the case of Examples 1 to 4 it can be seen that it does not use the conventional HCFC-141b as a foaming agent, but generally has excellent properties despite using water or the next-generation foam HFC-365mfc. At Yenken, room temperature and ultra low temperature, the tensile strength is 2.7kg / cm 2 and 3.1kg / cm 2 or more, respectively, and the compressive strength at room temperature and ultra low temperature is 2.2kg / cm 2 and 3.1kg / cm 2 or more, respectively. In addition, the thermal conductivity, which is one of the important characteristics of the polyurethane foam, is similar to HCFC-141b and does not drop significantly, thereby satisfying the specification required as the cryogenic insulator. In particular, according to the embodiment of the present invention it can be seen that the crack does not occur under the ultra-low temperature below -165 ℃ exhibits excellent mechanical properties.

The polyurethane foam of the present invention is produced by slabstock method. The slabstock method is to discharge and foam the mixture of the polyurethane composition in a predetermined ratio on the conveyor, the foam internal structure is uniformly distributed by receiving less external resistance when forming the foam. Foam foam is manufactured by using flexible products such as synthetic resin film, paper, asphalt paper, and metal film as upper and lower face materials on the polyurethane foam prepared as described above.

The cured foam is cut into block foam of a desired size and then processed into a heat insulating material having a shape of a pipe cover, an elbow, a pipe, a support, etc. according to the purpose.

As mentioned above, although this invention was demonstrated by the limited Example, this invention is not limited by this and it is various in the range of equality of a common technical idea in the technical field to which this invention belongs, and a claim described below. Of course, modifications and variations are possible.

According to the cryogenic pipe insulation polyurethane foam of the present invention and the heat insulating material using the same, it exhibits excellent mechanical strength without cracking while maintaining excellent heat insulation inherent in the polyurethane foam even under ultra low temperature, and particularly excellent flame retardancy can be obtained. .

Claims (7)

Polyurethane foams produced by reacting a polyol component with an isocyanate component in the presence of a blowing agent, reaction catalyst and other additives, The polyol component is (a) 40 to 60% by weight of polyol obtained by adding propylene oxide or ethylene oxide to sorbitol (b) 20 to 40% by weight of polyol obtained by polymerizing alcohol to phthalic acid (c) propylene oxide or ethylene 10-30 weight% of polyol obtained by adding an oxide (d) It is a mixed polyol composition containing 10-30 weight% of polyol obtained by adding a propylene oxide and ethylene oxide to pentaerythritol, The isocyanate component is a cryogenic polyurethane foam for cold pipes, characterized in that the functional group is a polymeric MDI of 2.6 ~ 3.0. The method of claim 1, The average OH value of the mixed polyol composition is 400 ~ 500, the average NCO% of the isocyanate component is 29 ~ 32 cryogenic polyurethane foam for cold insulation. The method of claim 1, NCO / OH, the ratio of NCO of the isocyanate component to OH of the polyol component, is a cryogenic polyurethane foam for cryogenic pipes, characterized in that 1.0 to 1.5. The method of claim 1, The foaming agent is a polyurethane foam for cryogenic pipe cold, characterized in that using 2.0 to 5.0 parts by weight of water based on 100 parts by weight of the polyol component. The method of claim 1, The foaming agent is a polyurethane foam for cryogenic pipe cold, characterized in that using 0.5 to 1.5 parts by weight of water and 15 to 30 parts by weight of HFC-365mfc based on 100 parts by weight of the polyol component. The method of claim 1, Ultra-low temperature polyurethane cold insulation polyurethane foam comprising a crosslinking agent for reinforcing strength and shortening the curing time and a flame retardant for reinforcing flame retardancy as the additive. Insulation material formed using the cryogenic polyurethane foam for cold storage of claim 1.