High-flame-retardant cryogenic insulating material as well as preparation method and application thereof

Abstract

According to the high-flame-retardant cryogenic insulating material and the preparation method and application thereof, low-hydroxyl-value flame-retardant polyester polyol and a flame retardant are adopted, the dosage of a chemical foaming agent is reduced, a physical foaming agent reduces the foam density and takes away heat, the flame retardance of a polyurethane material is improved, meanwhile, the reaction rate is reduced, the core burning risk is reduced, the oxygen index is larger than 30%, and the heat conductivity is smaller than 0.022 W / mK at 25 DEG C; the flame retardant grade is high; the polyester polyol has activity, so that the requirement on the activity of the catalyst and the dosage of the catalyst are reduced, and the odor grade is lower than 2.5; the low-hydroxyl-value flame-retardant polyester polyol is combined with high-functionality polyether polyol A and B for use, so that the foam size stability is improved, the foam shrinkage risk is reduced, the density of the product is 40-45 kg / m < 3 >, the compression strength is larger than 250 kPa, the tensile strength is larger than 350 kPa, the water absorption rate is smaller than 0.5%, and the size stability is smaller than 1% at-196 DEG C; the catalyst and the retarder balance milky white and gelation time, gentle the foaming rate, prevent core burning and match continuous production at the same time, the process performance is stable, the product performance is excellent, the productivity and efficiency are improved, and the cost is greatly reduced.

Description

Technical Field

[0001] The invention relates to a cryogenic tube shell material, in particular to a highly flame-retardant cryogenic insulation material and a preparation method and application thereof. Background Art

[0002] PIR (Polyisocyanurate) cryogenic insulation shell can effectively isolate external heat and maintain a low temperature environment inside the equipment or pipeline. It is widely used in oil and natural gas transportation, freezers, cold storage rooms, intermediate air conditioning systems, as well as transportation, food processing and civilian rocket industries. Its demand is increasing year by year. The problem of foam core burning cannot be avoided in the current production process. The foaming reaction is an exothermic process. The two components are mixed together and react too quickly, the heat in the core accumulates, and the heat cannot be effectively dissipated, resulting in core burning. At the same time, the reaction is too fast and it is easy to wrap the gas to form closed cells. In a cold environment, it shrinks and causes foam shrinkage, affecting adhesion or causing cracking problems. Water is a necessary component of the foaming reaction. The increase in water consumption leads to an increase in the urea group of the reactant. The increase in heat generated will also cause the heat to be unable to dissipate quickly and cause core burning. If the foam is too fine or too thick during the production process, the heat in the core cannot be effectively dissipated, resulting in core burning. In addition, improper selection of raw materials or excessive metal ion content can also easily cause the foam core to turn yellow and discolor. Secondly, the flame retardant performance of PIR cryogenic insulation shell is not high and cannot be used in scenes with flame retardant requirements. After adding flame retardant ingredients, the viscosity increases, which is also easy to cause foam shrinkage. In addition, there are many volatile substances in the components, which are easy to emit toxic and harmful gases, polluting the environment and endangering health. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to improve the flame retardant properties of PIR cryogenic insulation pipe shells, reduce odor, avoid foam core burning and shrinkage, and provide a highly flame retardant cryogenic insulation material; another purpose of the present invention is to provide a method for preparing the above material; another purpose of the present invention is to provide the application of the above material in pipe shell products.

[0004] Technical solution: The highly flame-retardant deep-cold insulating material of the present invention is composed of component A and component B, in parts by weight, and the weight ratio of component A to component B is 1:1.3-1.35; the component A comprises: 27-33 parts of low-hydroxyl flame-retardant polyester polyol, 8-10 parts of high-official polyether polyol A, 4-6 parts of polyether polyol B, 35-40 parts of flame retardant, 3-4 parts of foam stabilizer, 0.8-1.5 parts of catalyst, 0.6-0.7 parts of chemical foaming agent, 0.6-0.7 parts of delay agent, and 12-13 parts of physical foaming agent; the component B is multiple methyl polyphenyl polyisocyanate; the delay agent is at least one of lactic acid or formic acid.

[0005] Furthermore, the flame retardant is a water-washable liquid flame retardant, which improves the flame retardant performance while reducing the problem of foam core burning. The catalyst and delay agent are practical to reduce the volatilization of toxic and harmful gases, control the reaction speed while ensuring that the components react fully, and prevent the polyurethane reaction process from releasing too much heat too quickly, and the internal foam is too much and too fine, so that the heat in the core cannot be dissipated in time and causes core burning. The use of catalysts combined with delay agents such as lactic acid or formic acid can reduce the odor while also greatly reducing the risk of foam core burning.

[0006] Furthermore, the low hydroxyl flame retardant polyester polyol has a hydroxyl value of 210 and a functionality of 2, and is selected from PS-7001. While improving the flame retardant effect, due to its low hydroxyl value, certain activity, and small amount of catalyst used, the polyurethane reaction rate is stable, toxic and harmful smoke is prevented from escaping during the foaming process, the foam core temperature changes steadily, the foam foams maturely, and the heat is dissipated in time, the foam core is prevented from yellowing, and the tensile strength and dimensional stability are high. At the same time, the low hydroxyl flame retardant polyester polyol reduces the amount of chemical foaming agent deionized water, reduces the heat generation during the foaming process while ensuring the normal reaction, and further prevents the core from burning due to excessive temperature rise inside the foam core.

[0007] Further, the high-functional polyether polyol A is a polyether polyol with sucrose as the initiator, with an average functionality of more than 4.5 and a hydroxyl value of 380-580 mgKOH / g, selected from one of NJ-8238 and NJ-6249; the polyether polyol B is a polyether polyol with ethylenediamine or toluene diamine as the initiator, with a hydroxyl value of 500-750 mgKOH / g, selected from one of NJ-403 and TD405. The combination of the high-functional polyether polyol A and polyether polyol B with flame-retardant polyester polyol in a suitable ratio can foam steadily and evenly, and the foam stabilizer can increase the stability and uniformity of the foam size and reduce the risk of foam shrinkage.

[0008] Furthermore, the flame retardant is selected from at least one of water-washable TCPP, TEP and TDCPP. Compared with the volatility, irritation and toxicity of non-water-washable flame retardants, water-washable flame retardants are selected to reduce the volatile odor of the foam material. When the three flame retardants encounter high temperatures, they will release non-combustible gases to dilute the combustible gases and prevent further development of combustion. Among them, water-washable tris (chloropropyl) phosphate TCPP and tris (dichloropropyl) phosphate TDCPP have high flame retardant properties and good volatility, good oil resistance and hydrolysis resistance, and are more likely to form glass or foam when heated and mixed with other components to make the mixture more uniform. When encountering high temperatures, a uniform covering layer is formed to be flame-retardant, but its solubility is poor and the system viscosity is large, resulting in poor atomization performance, poor thermal conductivity, and reduced oxygen index. Tris(2-chloroethyl)phosphate TCEP has good water solubility, reduces the surface tension of other components and the viscosity of the system, and makes it easier to evenly mix glassy or foamy water-washed tris(chloropropyl)phosphate TCPP and tris(dichloropropyl)phosphate TDCPP into the foam material when mixed with other components, further promoting the uniformity of the flame retardant layer when encountering high temperature, thereby further improving the flame retardant effect, ensuring that the polyurethane foam has excellent atomization performance, and ensuring the stability of the process during continuous production.

[0009] Furthermore, the foam stabilizer is a non-hydrolyzable silicon surfactant or a polysiloxane surfactant, selected from at least one of B8544, B8545, or AK8805. Its good interfacial activity and emulsifying properties make it easier and faster to mix with other components, play a role in the process of foam formation and growth, and promote the stable growth and maturity of foam.

[0010] Furthermore, the catalyst is selected from at least one of potassium isooctanoate K15, potassium acetate PC46 or TMR-5, and has a catalytic effect in the gel process, as well as in the foam generation and maturation process. The catalyst and the delay agent balance and adjust the balance between milky white and gel time, which can better match continuous production and stable process performance, and further prevent the core burning problem. The type and ratio of the delay agent and the catalyst affect the polyurethane foaming rate and the foaming rate, and play a decisive role in the dimensional stability and strength of the polyurethane after foaming. At the same time, the slow foaming rate avoids the foam core burning problem and promotes foam maturation to further prevent foam shrinkage and ensure the stability of the finished product size.

[0011] Choose low hydroxyl value flame retardant polyester polyol PS-7001, which has relatively large activity and can reduce the use of catalysts. The low hydroxyl value of the system reduces the amount of catalyst used and can also reduce the risk of foam heartburn. The small amount of catalyst used makes its odor low, improves the comfort of workers in production and operation, and avoids environmental pollution.

[0012] Furthermore, the physical foaming agent is selected from at least one of pentafluoropropane HFC 245fa or monofluorodichloroethane HFC-141B, which reduces density and promotes foam growth during the foaming process to prevent the foam from being solidified and forming closed cells before it grows. At the same time, it combines with the foam stabilizer to take away the heat generated during the foaming process along the direction of foam growth, thereby reducing the risk of heartburn.

[0013] Furthermore, the multi-methyl polyphenyl polyisocyanate is selected from at least one of M20S, 44V20L or PM-200, has a moderate acid value, a low impurity content, and a low chlorine content. It is mixed with component A in a suitable ratio, foams evenly, has a moderate physical viscosity, and the material is evenly sprayed out of the spray gun. The polyurethane curing and maturation process is moderate, the hard foam strength is high, it is not easy to shrink and deform due to thermal expansion and contraction, and the hard foam compression strength and tensile strength are improved.

[0014] The present invention also provides a method for preparing the above-mentioned highly flame-retardant cryogenic insulation material, comprising the following steps:

[0015] (1) Stir and mix component A evenly;

[0016] (2) After being mixed with component B by high-pressure spraying, it is then stirred and foamed at high speed by a mace mixing head to obtain a highly flame-retardant deep-cold insulating material.

[0017] Furthermore, the mixing and foaming conditions in the step (2) are as follows: raw material temperature 20±2°C, mixing head pressure 0.4-05 bar, mixing head speed 2500-3000 rpm, conveyor belt speed 4-5 m / min, continuous foaming for 3-5 min, cutting into foam blocks according to a width of 1±0.1 m, aging for 10-14 days, and engraving on an engraving machine to obtain the desired product.

[0018] The present invention also provides application of the highly flame-retardant cryogenic insulation material in tube and shell products.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. Flame-retardant polyester polyols with low hydroxyl values ​​and liquid flame retardants reduce the usage of chemical foaming agent deionized water. Physical foaming agents reduce foam density and take away the heat generated by the foaming reaction, thereby improving the flame retardant properties of polyurethane materials while reducing the reaction rate to avoid the risk of heartburn. The oxygen index is greater than 30%, the thermal conductivity is less than 0.022W / mK@25℃, and the flame retardant grade can be greater than B1 grade; 2. Polyester polyols are active, which reduces the requirements and dosage of catalyst catalytic activity, and the odor grade is lower than 2.5; 3. The combination of low hydroxyl flame-retardant polyester polyols and high-official polyether polyols A and B increases the dimensional stability of the foam and reduces the risk of foam shrinkage. The density of the product is 40-45kg / m 3, compression strength>250kPa, tensile strength>350kPa, water absorption<0.5%, dimensional stability<1%@-196℃; 4. Catalysts and delay agents improve the balance between milky and gel time, slow down the rate of foaming reaction, further prevent core burning, and better match continuous production, with stable process performance, excellent product performance, greatly improved production capacity and efficiency, and significantly reduced costs. DETAILED DESCRIPTION

[0020] The technical scheme of the present invention is further described below in conjunction with the examples. The raw materials used in the examples are all commercially available, as shown in Table 1. The chemical foaming agent deionized water is homemade and meets the quality specifications of GB / T 6682-2016 grade 3 water.

[0021] Table 1 List of raw materials

[0022]

[0023] Table 2 shows the components and proportions (parts by weight) of Examples 1 to 3 and Comparative Examples 1 to 5, and a blank space indicates that the component is not added.

[0024] Table 2 Weight parts of each component raw material in the embodiments and comparative examples

[0025]

[0026] The preparation method of the polyurethane spray foam material of the above embodiment and comparative example comprises the following steps:

[0027] (1) Stir and mix component A evenly;

[0028] (2) Component A and component B are stirred, mixed and foamed to obtain a highly flame-retardant deep-cold insulating material. The foaming operation process parameters are as follows: raw material temperature 20±2°C, mixing head pressure 0.4-05 bar, mixing head speed 2500-3000 rpm, conveyor belt speed 4-5 m / min. After high-pressure jet mixing, the mixture is continuously foamed for 3-5 minutes by high-speed stirring and mixing with a mace mixing head. The mixture is cut into foam blocks according to a width of 1±0.1 m, aged for 10-14 days, and then carved on an engraving machine to obtain the desired product.

[0029] Comparative Example 1: Based on Example 1, all low hydroxyl flame retardant polyester polyol PS-7001 was replaced with polyester polyol HF-8730, and the remaining steps were the same.

[0030] Comparative Example 2: Based on Example 1, the delay agent was removed and the remaining steps were the same.

[0031] Comparative Example 3: Based on Example 1, all low hydroxyl flame retardant polyester polyol PS-7001 was replaced with polyester polyol PS-3152, and the remaining steps were the same.

[0032] Comparative Example 4: Based on Example 1, the two or more flame retardants are replaced by one of them, and the remaining steps are the same.

[0033] Comparative Example 5: Based on Example 1, the low hydroxyl value flame retardant polyester polyol PS-7001 was partially replaced with polyester polyol PS-3152, and the remaining steps were the same.

[0034] The prepared polyurethane spray foam material was subjected to physical property tests, and the data are shown in Table 3.

[0035] Comparative Examples 1 to 3, the product density is 40 to 45 kg / m 3 , thermal conductivity <0.022W / mK@25℃, compression strength >250kPa, tensile strength >350kPa, water absorption <0.5%, under liquid nitrogen conditions, dimensional stability <1%@-196℃, oxygen index >30%, odor level <2.5, the product performance is not only excellent, but also the production capacity and efficiency are greatly improved, and the cost is greatly reduced. The flame retardant is a water-washable flame retardant, which improves the flame retardant performance while reducing the problem of foam core burning. The catalyst and delay agent are practical to reduce the volatilization of toxic and harmful gases, control the reaction speed while ensuring that the components react fully, and prevent the polyurethane reaction process from releasing too much heat and too fast, and the internal foam is too much and too fine, so that the heat of the core cannot be dissipated in time to cause core burning; the appropriate ratio of catalyst and delay agent improves the balance between adjusting milky white and gel time, which can better match continuous production and stable process performance, and further prevent core burning problems. Select flame-retardant polyester polyols to enhance the flame-retardant effect. At the same time, they have a certain activity that reduces the amount of catalyst used. Together with the low hydroxyl value system, they make the polyurethane reaction rate more stable, further avoiding the risk of core burning. The combination of high-official polyether polyol A and polyether polyol B with flame-retardant polyester polyols in appropriate proportions produces stable and uniform foaming. The combination with foam stabilizers can increase the stability and uniformity of foam size and reduce the risk of foam shrinkage.

[0036] Example 1 has the best flame retardant insulation performance, the lowest odor level, and the highest compression strength and tensile strength. The weight ratio of polyurethane white material component A to polyurethane black material component B is 100:132. After mixing in a suitable ratio, component A and component B are uniformly foamed, the physical viscosity is moderate, and the materials in the spray gun are uniformly sprayed. Too much component A will cause the polyurethane to cure too quickly, the hard foam strength is low, the curing process is slow, and it is easy to expand and contract due to heat and contraction; too much component B will cause the hard foam to be brittle, and the compression strength and tensile strength will be reduced; adjust the amount of catalyst and delay agent, control the formation and growth rate of foam while foaming, adjust the balance between milky white and gel time, prevent foam core burning, stabilize foam size, and improve compression strength and tensile strength.

[0037] Table 3 Performance test data of embodiments and comparative examples

[0038]

[0039] Comparing Comparative Examples 1, 3, and 5 with Example 1, the low hydroxyl flame retardant polyester polyol PS-7001 is completely or partially replaced with polyester polyol HF-8730 or polyester polyol PS-3152. Due to the high hydroxyl value of HF-8730 and PS-3152, the amount of catalyst used is increased, the rate of polyurethane reaction is increased, the foam core temperature is increased, the foam is fine, and the curing is too fast to easily form more closed cells, the foam core turns yellow and burns, the odor increases, and the tensile strength and dimensional stability decrease; the thermal conductivity increases, the oxygen index decreases, and its flame retardant performance deteriorates. At the same time, the flame retardant polyester polyol with a low hydroxyl value reduces the amount of chemical foaming agent deionized water, reduces the heat generation during the foaming process while ensuring the normal reaction, and further prevents the foam core from heating up too fast and causing the core to burn.

[0040] Comparing Comparative Example 2 with Example 1, not using a delay agent results in a too fast reaction rate of the polyurethane, a high core temperature, too fast curing, too many closed-cell bubbles, severe core burning of the material, and poor tensile strength and dimensional stability.

[0041] Comparing Comparative Example 4 with Example 1, only one flame retardant TDCPP is used, which has poor solubility and high system viscosity, resulting in poor atomization performance, poor thermal conductivity, reduced oxygen index, and poor flame retardant performance.

Claims

1. A highly flame-retardant cryogenic insulation material, characterized in that: The invention is composed of component A and component B in weight proportion of 1:1.3-1.35; the component A comprises: 27-33 parts of low hydroxyl flame retardant polyester polyol, 8-10 parts of high-functional polyether polyol A, 4-6 parts of polyether polyol B, 35-40 parts of flame retardant, 3-4 parts of foam stabilizer, 0.8-1.5 parts of catalyst, 0.6-0.7 parts of chemical foaming agent, 0.6-0.7 parts of delay agent and 12-13 parts of physical foaming agent; the component B is multi-methyl polyphenyl polyisocyanate; the delay agent is at least one of lactic acid or formic acid.

2. The highly flame-retardant cryogenic insulation material according to claim 1, characterized in that: The low hydroxyl flame retardant polyester polyol has a hydroxyl value of 210 and a functionality of 2, and is selected from PS-7001; the high-functional polyether polyol A is a polyether polyol with sucrose as the initiator, has a hydroxyl value of 380 to 580 mgKOH / g, and is selected from one of NJ-8238 and NJ-6249; the polyether polyol B is a polyether polyol with ethylenediamine or toluenediamine as the initiator, has a hydroxyl value of 500 to 750 mgKOH / g, and is selected from one of NJ-403 and TD405.

3. The highly flame-retardant cryogenic insulation material according to claim 1, characterized in that: The flame retardant is selected from at least one of water-washed tris(chloropropyl) phosphate TCPP, tris(2-chloroethyl) phosphate TCEP, and tris(dichloropropyl) phosphate TDCPP.

4. The highly flame-retardant cryogenic insulation material according to claim 1, characterized in that: The foam stabilizer is a non-hydrolyzable silicon surfactant or a polysiloxane surfactant, and is selected from at least one of B8544, B8545 or AK8805.

5. The highly flame-retardant cryogenic insulation material according to claim 1, characterized in that: The catalyst is selected from at least one of potassium isooctanoate K15, potassium acetate PC46 or TMR-5.

6. The highly flame-retardant cryogenic insulation material according to claim 1, characterized in that: The physical foaming agent is selected from at least one of pentafluoropropane HFC 245fa and dichloromonofluoroethane HFC-141B.

7. The highly flame-retardant cryogenic insulation material according to claim 1, characterized in that: The polymethyl polyphenyl polyisocyanate is selected from at least one of M20S, 44V20L or PM-200.

8. A method for preparing a highly flame-retardant cryogenic insulation material according to any one of claims 1 to 7, characterized in that: The steps include: (1) Stir and mix component A evenly; (2) After being mixed with component B by high-pressure spraying, it is then stirred and foamed at high speed by a mace mixing head to obtain a highly flame-retardant deep-cold insulating material.

9. The method for preparing a highly flame-retardant cryogenic insulation material according to claim 8, characterized in that: The mixing and foaming conditions in step (2) are as follows: the temperature of the component materials is 20±2° C., the pressure of the mixing head is 0.4-0.5 bar, the speed of the mixing head is 2500-3000 rpm, the conveyor belt speed is 4-5 m / min, the continuous foaming is 3-5 min, and the cutting and ripening is 10-14 days.

10. Use of the highly flame-retardant cryogenic insulation material according to any one of claims 1 to 7 in tube and shell products.

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