KR20130000912A - Polyisocyanurate foam and products comprising the same - Google Patents

Abstract

PURPOSE: Polyisocyanurate foam is provided to have excellent insulating performance and excellent adhesion while having a good heat-insulating performance and mechanical properties. CONSTITUTION: Polyisocyanurate is formed by foaming a foam composition which comprises an isocyanate component, a polyol component and a foaming agent. The NCO/OH ratio of the isocyanate component and the polyol component is 1.3-2.5. The polyol component is obtained by reacting 40-70 wt% of a polyol which is obtained by reacting glycol to terephthalic acid, 10-30 wt% of a polyol which is obtained by reacting glycol to adipic acid, 10-20 wt% of a polyol obtained by reacting one or more selected from ethylene oxide and propylene oxide to sorbitol, and 10-30 wt% of a polyol obtained by reacting glycol to a phthalic anhydride.

Description

POLYISOCYANURATE FOAM AND PRODUCTS COMPRISING THE SAME}

The present invention relates to a polyisocyanurate foam having excellent adhesiveness and a double tube heat insulating material using the same. More specifically, four kinds of mixed polyols are used as the main raw materials, and the heat resistance and mechanical properties are excellent while having excellent high temperature heat resistance. An improved polyisocyanurate foam and a double pipe insulation comprising the same.

In general, polyisocyanurate (PIR) foam is prepared by foaming with a blowing agent using diisocyanate and polyol as raw materials, and is mainly used as a heat insulating material.

Toluene diisocyanate (TDI) or 4,4'-diphenylmethane diisocyanate (MDI) is used as the diisocyanate, and among these, polymer type 4,4'-di As phenylmethane diisocyanate, polymeric MDI having an average functional group of 2.7 or more is mainly used.

As the polyol, polyether polyols and polyester polyols are largely used. Polyether-based polyols have low viscosity and are easy to process, stable to hydrolysis, and inexpensive. Polyester-based polyols have the disadvantages of poor hydrolysis resistance, but they have the advantages of excellent thermal stability, excellent tensile strength and resistance to oil. Accordingly, polyether-based polyols are mainly used in the production of polyurethane, but polyester-based polyols are frequently used in the production of polyisocyanurate foams in which heat resistance (insulation resistance) is important.

As the blowing agent, water, carboxylic acid, fluorocarbon, and the like are mainly used, and an inert gas such as carbon dioxide or air may also be used as the blowing agent. Although blowing agents have low thermal conductivity and stable chlorofluorocarbons in the atmosphere, hydrochlorofluorocarbons, cyclohexane, water, hydrofluorocarbons, etc. are mainly used as environmental problems of chlorofluorocarbons have recently emerged. In particular, hydrochlorofluorocarbons have a low thermal conductivity and are not easily diffused into the air in polyisocyanurate foams and thus maintain thermal insulation and have no ozone permeability.

In addition, in preparing the polyisocyanurate foam, a reaction catalyst, a bubble stabilizer, a flame retardant, etc. may be additionally used in addition to the diisocyanate, polyol, and blowing agent as described above. As the reaction catalyst, potassium-based and zinc-based are mainly used, and the bubble stabilizer is mainly a silicone-based surfactant. Flame retardants are mainly halogen or phosphorus.

Such polyisocyanurate foams are mainly used in building sandwich panels. However, insulation is also required in the case of a heat insulating tube for transporting a fluid (liquid or gas), especially a double heat insulating tube, and polyisocyanurate foam is not used in such a double heat insulating tube. This is because the high temperature heat resistance is low due to the structural characteristics of the polyisocyanurate foam is poor adhesion. Specifically, the polyisocyanurate foam is difficult to apply as a heat insulating material of the double insulation tube because the shrinkage expansion due to the temperature drop is severe and the adhesive force is poor at the contact interface between the inner tube and the exterior of the double insulation tube.

In addition, the general polyisocyanurate foam is low in mechanical properties. In order to improve the mechanical properties, a method of increasing the density of the foam or using filler such as glass fiber or carbon fiber has been considered. However, all of these methods have a problem that the thermal conductivity is increased and the thermal insulation is lowered.

Accordingly, the present invention is to provide a polyisocyanurate foam having excellent heat-resistance and excellent adhesive strength and improved heat insulation and mechanical properties by using four different mixed polyols as polyols, and a heat insulating material for double pipes using the same. There is a purpose.

The present invention to achieve the above object,

Isocyanate component;

Polyol component; And

In the polyisocyanurate foam formed by foaming a foam composition comprising a blowing agent,

The polyol component,

(a) 40 to 70% by weight of a polyol obtained by reacting terephthalic acid with glycol;

(b) 10 to 30% by weight of a polyol obtained by reacting adipic acid with glycol;

(c) 10 to 20% by weight of a polyol obtained by reacting sorbitol with at least one selected from ethylene oxide and propylene oxide; And

(d) It provides a polyisocyanurate foam comprising 10 to 30% by weight of a polyol obtained by reacting glycol with muphthalic acid.

At this time, the average OH value of the polyol component is 300 ~ 510, the average NCO% of the isocyanate component is preferably 29 to 32. In addition, it is preferable that the said isocyanate component is polymeric MDI whose functional group is 2.1-3.1.

In addition, the present invention provides a heat insulating material of a double insulation tube using the polyisocyanurate foam of the present invention.

According to the present invention, four different types of mixed polyols are used as the polyols, so that the heat resistance and the mechanical properties are improved while having excellent adhesive strength at high temperatures. Accordingly, it can be usefully used in products such as the double heat insulation tube having a severe temperature drop.

Hereinafter, the present invention will be described in detail.

Polyisocyanurate foam according to the present invention is an isocyanate component; Polyol component; And a foam composition comprising at least a blowing agent is foamed to form (manufacture). The polyisocyanurate foam according to the present invention is preferably rigid.

The isocyanate component is not particularly limited as long as it is a compound having an isocyanate group (-NCO). The isocyanate component may be an aromatic, aliphatic, saturated or unsaturated isocyanate compound. Specific examples of the isocyanate component include 4,4'-diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), xylene diisocyanate, isophorone diisocyanate, cyclohexyl diisocyanate (CHDI) and the like. You can use one or more selected.

As the isocyanate component, it is preferable to use polymer type polyisocyanate. Preferably, polymeric 4,4'-diphenylmethane diisocyanate is preferably used polymeric MDI having a functional group (functional group) number of 2 or more. More preferably, polymeric MDI having a functional group number of 2.1 to 3.1 may be used. In this case, when the number of functional groups is 2.1 or less, the dimensional stability may be somewhat lowered when forming polyisocyanurate foam, and when it exceeds 3.1, fluidity may be lowered due to an increase in viscosity. Moreover, it is good that the average NCO% of the said isocyanate component is 29-32. In this case, when the average NCO of the isocyanate component is less than 29%, the fluidity may be lowered, and when it exceeds 32%, low-temperature dimensional stability may be lowered. Accordingly, the isocyanate component is a polymeric MDI (polymer type 4,4'-diphenylmethane diisocyanate) having a functional group number of 2.1 to 3.1 in consideration of the dimensional stability and fluidity of the polyisocyanurate foam, and the average NCO% is 29 to 32 is good. In addition, the polymeric MDI has an NCO index of 130 to 180.

As the polyol component, a mixed polyol including four different polyols is used. At this time, each polyol is formulated in an appropriate content. Specifically, the polyol component is (a) 40 to 70% by weight of a polyol obtained by reacting terephthalic acid (TPA) with glycol (glycol), (b) 10 to 30% by weight of a polyol obtained by reacting glycol with adipic acid, A mixed polyol comprising (c) 10 to 20% by weight of a polyol obtained by reacting at least one selected from ethylene oxide and propylene oxide with sorbitol, and (d) 10 to 30% by weight of a polyol obtained by reacting glycol with muphthalic acid. do.

In this case, the glycol, that is, the glycol used for the production reaction of the (a) polyol, (b) polyol and (d) polyol is not limited as long as it is glycols. The glycol is preferably at least one selected from diethylene glycol (DEG), dipropylene glycol (DPG), polyethylene glycol (PEG), polypropylene glycol (PPG) and the like.

The polyol components used in the present invention are polyols based on terephthalic acid, muphthalic acid, adipic acid and sorbitol, respectively, which have 2, 2, 2 and 6 functional groups capable of reacting due to their respective structures. When reacted with a linear bond or cross-linking is formed. They differ in their characteristics. For example, the compressive strengths of adipic acid based polyols and sorbitol based polyols differ by more than 10%.

According to the present invention, the polyisocyanurate foam synthesized and foamed from the four polyols (mixed polyols) has the characteristics of each of the four polyols, and thus has high temperature heat resistance and adhesiveness as compared to conventional polyisocyanurate foams. It is improved, and excellent in heat insulation and mechanical properties. In particular, by ensuring heat resistance at high temperatures, when applied to products with a high temperature drop, for example, a double insulation tube, and maintains a strong adhesive force with the inner tube and the appearance, and has excellent heat insulating properties. Accordingly, the polyisocyanurate foam according to the present invention can be usefully used as a heat insulating material of a double heat insulation pipe flowing high temperature fluid as well as a building panel.

In addition, the four polyols (mixed polyols) each have a content in the appropriate range as described above, if the content range of each polyol is out of the above range any one or more of high temperature heat resistance, adhesiveness, heat insulation and mechanical properties This may not be good. In the present invention, the content range of each polyol is considering the characteristics of each of the four polyols, reaction time, viscosity, and high temperature heat resistance, adhesiveness, It is optimized by comprehensively considering the insulation and mechanical properties.

In addition, the NCO / OH ratio of the isocyanate component and the polyol component involved in the synthesis (reaction) of the polyisocyanurate foam is preferably 1.3 to 2.5. In this case, when the NCO / OH ratio is less than 1.3, the heat resistance and adhesion may be slightly lower, and when the NCO / OH ratio exceeds 2.5, the mechanical properties may be lowered. Accordingly, it is preferable to properly adjust the content of the isocyanate component and the polyol component so that the NCO / OH ratio of the isocyanate component and the polyol component has 1.3 to 2.5. Although it does not specifically limit, 120-200 weight part of isocyanate components can be used with respect to 100 weight part of polyol components.

The blowing agent is not limited. The blowing agent may use one or more selected from organic blowing agents, inorganic blowing agents, water and inert gases (carbon dioxide or air). The blowing agent may be used, for example, at least one selected from fluorocarbons and water. Specifically, for example, the blowing agent preferably uses at least one selected from 1,3-pentafluorobutane, 1,3-pentafluoropropane, and the like as fluorocarbons. In this case, the 1,3-pentafluorobutane may be used as a commercial product, such as HFC-365mfc, and the 1,3-pentafluoropropane may be used as a commercial product, such as HFC-227ea. In addition, the foaming agent is not particularly limited, but may be used at 0.1 to 40.0 parts by weight based on 100 parts by weight of the polyol component.

According to a preferred embodiment, the blowing agent is preferably used by mixing the organic blowing agent (fluorocarbon-based, etc.) and water. At this time, the organic blowing agent is preferably used in 5.0 to 35.0 parts by weight based on 100 parts by weight of the polyol component. If the content of the organic blowing agent is less than 5.0 parts by weight, the density may be too high, and if it exceeds 35.0 parts by weight, the density may be too low to be undesirable. By the content of such an organic blowing agent, the density of the polyisocyanurate foam may be 30 to 100 kg / m 3. In the present invention, the density of the polyisocyanurate foam is not limited. The density of the polyisocyanurate foam may be a low density foam of 30 kg / m 3 or less, or a high density foam of 100 kg / m 3 or more, depending on the content of the organic blowing agent. At this time, as the organic blowing agent, it is preferable to use 1,3-pentafluorobutane (HFC-365mfc) and / or 1,3-pentafluoropropane (HFC-227ea) as described above. Facilitating the production of polyisocyanurate foams and having low thermal conductivity can impart excellent thermal insulation to polyisocyanurate foams.

The water can also act as an auxiliary blowing agent. Water reacts with the isocyanate component to release carbon dioxide while forming urea, which is used for the foaming of the polyisocyanurate foam. In addition, the heat of reaction between the water and the isocyanate component is also used for the vaporization of the 1,3-pentafluorobutane (HFC-365mfc) and 1,3-pentafluoropropane (HFC-227ea). At this time, the content of water is preferably 7.0 parts by weight or less, specifically 0.1 to 7.0 parts by weight based on 100 parts by weight of the polyol component. If the water content is too low as less than 0.1 weight, it may be difficult to act as an auxiliary blowing agent. And if the content of water exceeds 7.0 parts by weight, heat aging (scorch) may be generated in the polyisocyanurate foam produced by the excess heat of reaction, the excess carbon dioxide is present in the polyisocyanurate foam, the thermal conductivity of the foam The degree can be raised. For the same reason as above, the blowing agent includes at least water, but preferably 0.1 to 7.0 parts by weight of water based on 100 parts by weight of the polyol component.

The polyisocyanurate foam according to the present invention is foam-molded based on an isocyanate component, four mixed polyols and a blowing agent as basic raw materials as described above, and in some cases, additional components in consideration of reactivity, foam structure and functionality, etc. It may further include a foam molding. The additional component may be used, for example, one or more selected from reaction catalysts, bubble stabilizers, chain extenders, flame retardants and the like.

The reaction catalyst is commonly used in the production of polyisocyanurate foam, and may be selected from, for example, an amine catalyst and a potassium catalyst. In addition, the reaction catalyst can be used as a used product, 1 type (s) or 2 or more types chosen from normal PC-8, T-45, TMR, etc., and mixing. The reaction catalyst is not particularly limited, but may be used in an amount of 1.0 to 3.0 parts by weight based on 100 parts by weight of the polyol component. At this time, when the content of the reaction catalyst is less than 1.0 or not used, it is difficult to improve the reaction rate, and the physical properties may be lowered due to the presence of unreacted material. It may not be big and economically undesirable.

In addition, a bubble stabilizer can use a silicone type surfactant. Specific examples include polysiloxane ethers. The foaming agent vaporized due to the heat of reaction in the preparation of the polyisocyanurate foam foams the reactant with the urethane bond while forming bubble bubbles. The bubble droplets may aggregate at their internal pressure to form large droplets, in which case the thermal insulation and mechanical properties may be degraded. In this case, when the silicon-based surfactant is used as the bubble stabilizer, the silicon-based surfactant supplies electric charges to the bubble drop surface to form cells having a small and uniform size with the electrostatic repulsive force. Such a bubble stabilizer is not particularly limited, but may be used in an amount of 0.01 to 2.0 parts by weight based on 100 parts by weight of the polyol component. In this case, when the content of the bubble stabilizer is less than 0.01 parts by weight, it may be difficult to stabilize the bubble drops, and when the content of the bubble stabilizer exceeds 2.0 parts by weight, the mechanical properties of the polyisocyanurate foam (such as compressive strength and load resistance) may be lowered.

The chain extender may improve the mechanical properties of the polyisocyanurate foam. The chain extender has a low molecular weight, for example, a molecular weight of 400 or less, and preferably has two or more functional groups capable of reacting with an isocyanate group (-NCO). Such chain extenders may be selected from low molecular weight hydroxy compounds, amine compounds and the like, for example diethanolamine, 1,4-butylenediamine, 1,6-hexamethylenediamine, diisopropanolamine, ethylene glycol One or more crosslinkable low molecular compounds selected from butanediol, 1,6-hexanediol, 1,4-cyclohexanediol and the like can be used. In addition, the chain extender is not particularly limited, but may be used in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the polyol component. At this time, if the content of the chain extender is less than 0.1 part by weight, the effect of improving the physical properties according to its use may be insignificant, and if it exceeds 20 parts by weight, the adhesive strength may be lowered.

In addition, the flame retardant is used to improve the flame retardancy of the polyisocyanurate foam, which can be used that is commonly used in the production of polyisocyanurate foam. The flame retardant may be halogen-based or phosphorus-based, and specific examples thereof may include phosphorus-based flame retardants such as tricresyl phosphate. Although such a flame retardant is not specifically limited, It is preferable to use 5.0-15.0 weight part with respect to 100 weight part of polyol components. In this case, when the content of the flame retardant is less than 5.0 parts by weight, the flame retardant effect of the use thereof is insignificant, and when the content of the flame retardant exceeds 15.0 parts by weight, the effect of improving the flame retardancy due to the excessive use may not be so great and economically undesirable.

The polyisocyanurate foam according to the present invention can be produced in the same manner as usual using the above ingredients as raw materials. The method for producing a polyisocyanurate foam may be divided into, for example, a one shot method, a prepolymer method, a spray method, and the like according to a method of reacting raw materials. In this, the said one-shot method is a method of making all the raw materials used, such as an isocyanate component and a polyol component, into a foaming machine at the time of making it react. While the one-shot method has the advantages of simple and easy operation, it is difficult to control the reaction rate and a large amount of heat of reaction may occur to generate uniformity inside the foam. The prepolymer method is a method in which a part of the polyol component is subjected to a slight reaction of an isocyanate component, followed by further reaction of another raw material. Such a prepolymer method has a relatively slow reaction rate and the reaction rate is low, the viscosity of the other foam in the reaction is slow to increase the advantage of being able to be filled in every corner even in a complex structure, while the manufacturing step may be slightly higher price.

The polyisocyanurate foam according to the present invention may be prepared by the above method, or by various other known methods. Considering workability, productivity and price, the one-shot method is used. At this time, the polyol component and additives are appropriately adjusted so that thermal aging or cracking of the foam inner circumference due to a large amount of heat of reaction does not occur. In addition, when the structure of the applied product is complicated, the prepolymer method is used. And the foaming machine used for foaming can use the high pressure or low pressure foaming machine conventionally used.

On the other hand, the product according to the present invention comprises the polyisocyanurate foam of the present invention as described above. The product according to the present invention may have a multi-layered structure of two or more layers, and may be selected from, for example, a building panel or a heat insulating tube. The building panel may include one or two or more base plates, and may be used as an interior or exterior material of a building. In addition, the heat insulating tube is for transporting a fluid (liquid or gas), which may be, for example, a double heat insulating tube including an inner tube and an outer tube. At this time, the polyisocyanurate foam of the present invention can be used as a heat insulating material of the products.

According to an exemplary form, a product according to the invention comprises a first member; Second member; And a heat insulating material formed between the first member and the second member. At this time, the heat insulating material is composed of the polyisocyanurate foam of the present invention as described above.

The first member and the second member are not limited. The first member and the second member may be made of metal, ceramic or synthetic resin. For example, when the product according to the present invention is a building panel having a sandwich structure, the first member may be an upper plate (surface plate), and the second member may be a lower plate (back plate). According to a preferred embodiment, the product according to the invention is a double insulation tube comprising an inner tube and an outer tube. In this case, the first member may be an inner tube, and the second member may be an outer appearance.

As described above, the polyisocyanurate foam according to the present invention may be usefully used as a heat insulating material of a double heat insulation tube having a high temperature drop due to excellent heat insulation and mechanical properties, in particular, high temperature heat resistance. In other words, it maintains a strong adhesive force with the inner tube and the appearance without deteriorating the adhesive strength even at high temperatures.

Hereinafter, embodiments of the present invention will be exemplified. The following examples are merely provided to aid the understanding of the present invention, whereby the technical scope of the present invention is not limited.

Example 1

50.0 g of polyol obtained by reacting terephthalic acid (TPA) with diethylene glycol (DEG), 25.0 g of polyol obtained by reacting diethylene glycol (DEG) with adipic acid, polyol 10.0 obtained by reacting ethylene oxide and propylene oxide with sorbitol g and 15.0 g of a polyol obtained by reacting diethylene glycol (DEG) with phthalic anhydride (PA) were mixed.

Next, 2.0 g of polysiloxane ether as a bubble stabilizer, PC-8 0.6 g, T-45 0.4 g and TMR-3 2.0 g, tricresyl phosphate 10.0 g as a flame retardant, 0.7 g of water as a blowing agent were added to the mixed polyol. 21.0 g of 1,3-pentafluorobutane (HFC-365mfc) was added to obtain a resin solution, and 160.0 g of polymeric MDI (polymer 4,4'-diphenylmethane diisocyanate) was mixed and reacted to foam. Thereby producing a polyisocyanurate foam.

[Example 2]

50.0 g of polyol obtained by reacting diethylene glycol (DEG) with terephthalic acid (TPA), 20.0 g of polyol obtained by reacting diethylene glycol (DEG) with adipic acid, polyol 15.0 obtained by reacting ethylene oxide with propylene oxide in sorbitol g and 15.0 g of a polyol obtained by reacting diethylene glycol (DEG) with phthalic anhydride (PA) were mixed.

Next, 2.0 g of polysiloxane ether as a bubble stabilizer, PC-8 0.6 g, T-45 0.4 g and TMR-3 2.0 g, tricresyl phosphate 10.0 g as a flame retardant, 0.7 g of water as a blowing agent were added to the mixed polyol. 21.0 g of 1,3-pentafluorobutane (HFC-365mfc) was added to obtain a resin solution, and 160.0 g of polymeric MDI (polymer 4,4'-diphenylmethane diisocyanate) was mixed and reacted to foam. Thereby producing a polyisocyanurate foam.

[Example 3]

The polyisocyanurate foam prepared according to Example 2 was aged for 1,500 hours at 200 ° C. according to the EN253 method as a specimen according to Example 3.

Example 4

45.0 g of polyol obtained by reacting polyethylene glycol (PEG200) with terephthalic acid (TPA), 15.0 g of polyol obtained by reacting diethylene glycol (DEG) with adipic acid, 15.0 g of polyol obtained by reacting ethylene oxide with propylene oxide in sorbitol And 25.0 g of a polyol obtained by reacting diethylene glycol (DEG) with phthalic anhydride (PA).

Next, 2.0 g of polysiloxane ether as a bubble stabilizer, PC-8 0.6 g, T-45 0.4 g and TMR-3 2.0 g, tricresyl phosphate 10.0 g as a flame retardant, 0.7 g of water as a blowing agent were added to the mixed polyol. 21.0 g of 1,3-pentafluorobutane (HFC-365mfc) was added to obtain a resin solution, and 160.0 g of polymeric MDI (polymer 4,4'-diphenylmethane diisocyanate) was mixed and reacted to foam. Thereby producing a polyisocyanurate foam.

The physical properties of the polyisocyanurate foam specimens according to Examples 1 to 4 were evaluated. Physical property evaluation results and evaluation methods are shown in the following [Table 1].

           <Property Evaluation Results and Evaluation Methods of Foam Specimen> Item Example 1 Example 2 Example 3 Example 4  Assessment Methods Density [kg / ㎥] 82 78 78 80 ASTM D1622 Thermal conductivity [kcal / m · h · ℃] 0.0217 0.0192 0.0218 0.0201 ASTM C518 Compressive strength (MPa) 6.6 7.0 7.4 6.8 ASTM D1621 Bending strength [MPa] 6.4 7.4 4.9 7.7 KS M3830 Inner Tube Adhesion [MPa] 2.8 2.8 2.5 3.1 ASTM D4986 Independent bubble rate [%] 94.9 91.8 91.5 92.5 ASTM D2856

As shown in Table 1, the polyisocyanurate foam specimens prepared as described above showed good results in all physical properties. In particular, when comparing Example 2 (before aging) and Example 3 (after aging), despite the aging for a long time at a high temperature of 200 ℃ it was found that the heat resistance is excellent and the width of the decrease in adhesion strength is low. The independent bubble ratio in the physical properties affects properties such as thermal conductivity, water vapor transmission rate, and moisture absorption rate of the polyisocyanurate foam. In general, independent bubble ratio also serves as a measure of quality control and quality of polyisocyanurate foams. At this time, the conventional conventional polyisocyanurate foam has a level of 90% independent foam, as shown in Table 1, the polyisocyanurate foam according to an embodiment of the present invention is 91% or more, as much as It was found that it has a very high independent bubble ratio as 94% or more.

As confirmed in the above embodiment, when using the four types of polyol according to the present invention in an appropriate content, it can be seen that not only good thermal insulation and mechanical properties, but also particularly excellent heat resistance to maintain excellent adhesion at high temperatures. In addition, it can be seen that it has a very high independent bubble ratio.

Claims (5)

Isocyanate component;
Polyol component; And
In the polyisocyanurate foam formed by foaming a foam composition comprising a blowing agent,
The polyol component,
(a) 40 to 70% by weight of a polyol obtained by reacting terephthalic acid with glycol;
(b) 10 to 30% by weight of a polyol obtained by reacting adipic acid with glycol;
(c) 10 to 20% by weight of a polyol obtained by reacting sorbitol with at least one selected from ethylene oxide and propylene oxide; And
(d) 10 to 30% by weight of a polyol obtained by reacting glycol with muphthalic acid,
Polyisocyanurate foam, characterized in that the NCO / OH ratio of the isocyanate component and the polyol component is 1.3 ~ 2.5.
The method of claim 1,
The isocyanate component is a polyisocyanurate foam, characterized in that the functional group is a polymeric MDI having 2.1 to 3.1.
The method of claim 1,
The foaming agent polyisocyanurate foam, characterized in that containing 0.1 to 7.0 parts by weight of water based on 100 parts by weight of the polyol component.
The method of claim 1,
The average OH value of the polyol component is 300 to 510, the polyisocyanurate foam, characterized in that the average NCO% of the isocyanate component is 29 to 32.
A double pipe insulation comprising a polyisocyanurate foam according to any one of claims 1 to 5.