JPS6354730B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a rigid urethane foam having extremely low thermal conductivity. Conventionally, rigid urethane foam has lower thermal conductivity than organic foams such as styrofoam and phenol foam, and inorganic fiber materials such as glass wool and rock wool, and has excellent mechanical strength, so it has been used for electric refrigerators, It is widely used for insulation purposes such as in storage cases, cold storage, and thermal storage. By the way, recently, when these hard urethane foams for insulation are used in refrigerators, for example, the insulation layer is made thinner to increase the internal volume while reducing power consumption.
There is a strong demand for rigid urethane foam used as a heat insulating material to have a high level of heat insulating performance, or in other words, to have extremely low thermal conductivity. Thermal conductivity of conventional rigid urethane foam (23
℃) is usually around 150 to 160 x 10 ^-4 Kcal/m.hr.℃, but it was considered extremely difficult to lower the thermal conductivity below this. In view of these circumstances, the present inventors conducted extensive research and found that when producing a rigid urethane foam, polyol components in a specific ratio of polyether polyol and polyester polyol with a specific structure are added to part or all of the polyol. It was discovered that a foam with extremely low thermal conductivity could be obtained by using , and the present invention was completed based on this knowledge. That is, in the present invention, when manufacturing a rigid urethane foam by reacting an organic polyisocyanate and a polyol in the presence of a catalyst, a blowing agent, and a foam stabilizer, about 80% by weight or more of the polyol component is A aromatic amine. A polyether polyol with a hydroxyl value of 300-550 mgKOH/g obtained by reacting ethylene oxide and propylene oxide with this as an initiator at a weight ratio of 5-50/95-50 and B. Consisting of 550mgKOH/g polyester polyol, and the weight ratio of A to B is 50~90/50~10
The present invention relates to a method for producing a hard urethane foam characterized by the following. A) The polyether polyol used in the present invention uses an aromatic amine as an initiator, and contains ethylene oxide and propylene oxide in a weight ratio of about 5 to 50/95 to 50, preferably about 10 to 30. Examples include polyether polyols having a hydroxyl value of about 300 to 550 mgKOH/g obtained by reacting at a ratio of /90 to 70. Aromatic amines used as initiators include monoamines such as aniline and toluidine, such as phenylenediamine, O-tolylenediamine, m-tolylenediamine, naphthalenediamine, 4,4'-diaminodiphenylmethane, Diamines such as xylene diamine, products obtained by condensation of aniline and formaldehyde, such as distillation residues such as tolylene diisocyanate and diphenylmethane diisocyanate, and products produced using, for example, tolylene diisocyanate and diphenylmethane diisocyanate. Examples include decomposition products obtained by hydrolyzing urethane foam with alkali or amine. Two or more of these aromatic amines may be used in combination. The polyether polyol used in the present invention is obtained by adding ethylene oxide and propylene oxide to these aromatic amines in a block or random manner. As mentioned above, the weight ratio of ethylene oxide and propylene oxide is about 5 to 5.
50/95 to 50, but if the amount of ethylene oxide used exceeds 50%, the compatibility with the blowing agent will deteriorate, the mechanical strength of the resulting rigid urethane foam will decrease, and the wet heat dimensional stability will decrease. Unfavorable properties such as poor quality may be observed. On the other hand, if the amount of ethylene oxide added is less than 5% by weight, the effect of reducing the thermal conductivity of the resulting rigid urethane foam is lost. The hydroxyl value of the polyether polyol used in the present invention varies depending on the type of aromatic amine used, but approximately
300-550mgKOH/g, preferably about 350-500mg
It is about KOH/g. B) Polyester polyol used in the present invention is usually produced by condensing a polyol having a primary hydroxyl group with a polycarboxylic acid or polycarboxylic acid anhydride. Examples of polyols having primary hydroxyl groups include ethylene glycol, diethylene glycol, triethylene glycol, 1,4 butanediol, 1,6 hexane glycol, trimethylolpropane, and pentaerythritol. Examples of polycarboxylic acids and polycarboxylic acid anhydrides include adipic acid, succinic acid, succinic anhydride, maleic acid, maleic anhydride, fumaric acid, phthalic acid, and pyromellitic acid. The polyester polyol used in the present invention comprises one or more of the above-mentioned polyols and one or more polycarboxylic acids or polycarboxylic acid anhydrides under conditions of an excess of hydroxyl groups.
Obtained by heating, dehydration, and condensation. The hydroxyl value of this polyester polyol is usually about 300 to 550 mgKOH/g. In the present invention, the above-mentioned A) polyether polyol and B) polyester polyol have a weight ratio of about 50 to 90/50 to 10, preferably about 60 to 85/40 to 15.
It is used by mixing in the ratio of If the amount of component B) is 10% by weight or less, the thermal conductivity of the resulting rigid urethane foam will not be reduced. On the other hand, if it is used in an amount of 50% by weight or more, the compatibility with the blowing agent such as trichlorofluoromethane becomes poor, making it difficult to obtain a good foam. Further, even if a foam is obtained, the wet heat dimensional stability etc. will be significantly deteriorated, making it difficult to put it into practical use. In the present invention, A) polyether polyol and B)
Mixed polyols consisting of polyester polyols are used in a ratio of about 80% by weight or more, preferably about 90% by weight or more of the polyol components, but as the polyol component mixed with these polyols, ordinary hard A polyether polyol having a functional group number of about 2 to 8 and a hydroxyl value of about 350 to 800 mgKOH/g can be used for producing the urethane foam. In the present invention, a rigid urethane foam is produced by reacting a specific polyol mixture as described above with an organic polyisocyanate in the presence of a catalyst, a blowing agent, and a foam stabilizer. As the organic polyisocyanate used in the present invention, those commonly used in producing ordinary rigid urethane foams can be used as they are. Typical examples are:
For example, toluylene diisocyanate, 4,4'-
Diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate (C-MDI), crude toluylene diisocyanate, and polyisocyanates partially modified by urethanization, trimerization, carbodiimidization, or amidation. can be given. Two or more of these may be used in combination. These polyisocyanates are
It is generally preferred to use NCO/OH equivalent ratios in the range of about 1.03 to 1.15 for the aforementioned polyols. Furthermore, the types and amounts of catalysts, foam stabilizers, and blowing agents used are not particularly limited, and can be used in accordance with conventional techniques. Typical examples of catalysts include tertiary amines such as dimethylethanolamine, triethylenediamine, tetramethylpropanediamine, tetramethylhexamethylenediamine, dimethylcyclohexylamine, stannath octoate, dibutyltin dilaurate, etc. Examples include organic tin compounds. The amount of catalyst is usually about 100 parts by weight of polyol.
It is used in an amount of about 0.1 to 10 parts by weight. Examples of blowing agents used in the present invention include trichloromonofluoromethane, dichlorodifluoromethane, and reactive blowing agents such as:
Water can also be used together. When water is used as a blowing agent, approximately 100 parts by weight of polyol is used.
It is preferable to use an amount of 1.5 parts or less. If more than this is used, the proportion of carbon dioxide gas in the bubbles will increase and the thermal conductivity will often increase. The blowing agent is usually used in an amount of about 10 to 70 parts by weight per 100 parts by weight of the polyol. As the foam stabilizer, various siloxane/polyalkylene oxide block copolymers (silicon foam stabilizers) can be used. The foam stabilizer is usually used in an amount of about 0.2 to 3 parts by weight per 100 parts by weight of the polyol. When producing rigid urethane foam, in addition to the catalysts, blowing agents, and foam stabilizers mentioned above, flame retardants such as trichloroethyl phosphite, trisdichloropropyl phosphate, chlorinated paraffin, tricresyl phosphate, etc. may be used as necessary. Pigments such as carbon black, titanium oxide, red iron oxide, and phthalocyanine blue, stabilizers such as 2-tetrabutylhydroquinone, phenyl salicylate, and 2-hydroxyphenylbenzotriazole may be added in appropriate amounts. As a specific means for manufacturing rigid urethane foam from the above-mentioned raw materials, any device that can uniformly mix the raw materials may be used, but for example, it is possible to uniformly mix the raw materials using a small experimental mixer, a foaming machine, etc. By doing this, a hard urethane foam can be easily obtained. The hard urethane foam obtained by the present invention has an extremely low thermal conductivity, for example, 129 to 132 at 23°C.
×10 ^-4 Kcal/m.hr.℃. The thermal conductivity of conventional rigid urethane foam is typically 150-160×
10 ^-4 Kcal/m.hr.℃, which is about 20% lower. This is extremely important because, for example, if a conventional hard urethane foam was used to create a heat insulating material, the thickness would be 10 cm, but if the hard urethane foam obtained in the present invention is used, only an 8 cm thick heat insulating layer is required. Economical, such as electric refrigerators, show cases, etc.
Used in the manufacture of cold or warm warehouses, insulated partition panels, etc. EXAMPLES The present invention will be explained in more detail with reference to Examples and Comparative Examples below. Reference Example 1 A Synthesis of polyether polyol A 54-necked Kolben equipped with a stirrer, thermometer, alkylene oxide inlet tube, and condenser was used.
- 1240 g of toluylene diamine and 20 g of flaky caustic potash were charged, heated to 95°C, 1200 g of ethylene oxide was reacted at 95 to 110°C, and subsequently 2500 g of propylene oxide was added and reacted at 110 to 115°C. The product was then neutralized with an aqueous solution of oxalic acid, and the crystals that crystallized were separated and dehydrated to obtain 4800 g of polyether polyol. As a result of analysis, this product has a hydroxyl group count of 465mgKOH/g, a pH of 10.3, and a viscosity of
It was 23000cps (25℃). B Manufacture of polyester polyol
1,350 g of trimethylolpropane and 1,500 g of adipic acid were charged, and while nitrogen gas was introduced, the mixture was heated and reacted at 200 to 210° C. for 9 hours. When the acid value of the product was measured, it was found to be 1.2 mgKOH/g, so it was cooled and used as a product. The yield was 3540g, and the hydroxyl value was 477mgKOH/g as a result of analysis. Examples 1 to 3 A silicone surfactant (silicon foam stabilizer F-335 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 parts of a polyol obtained by mixing the two types of polyols obtained in the above reference examples.
1.5 parts, 2.0 parts of tetramethylhexanediamine (TMHDA) as a catalyst, 1138 parts of Freon R-1, and polymethylene polyphenyl isocyanate (C
- MDI, amine equivalent 136) 124 parts mixed, 25 cm
It was foamed in a box measuring 25 cm x 20 cm (height direction) to obtain a hard urethane foam. After leaving this foam indoors for 3 days, it is 20cm x 20cm x 2cm from the inside.
Cut out a foam sample of (thickness) and measure the average temperature using an Anacon Model 88 thermal conductivity meter.
Thermal conductivity was measured at 23°C. The results are summarized in a table along with the following comparative examples. Comparative Examples 1 to 5 In the examples, the polyol component had a hydroxyl value of 460 to
A rigid urethane foam was obtained using the same formulation and method as in the example except that 480 mg KOH/g of general-purpose polyether was used, and the thermal conductivity was measured in the same manner. The results are shown in Table 1. As can be seen in the table, the thermal conductivity of the foam obtained according to the present invention is significantly lower than that using the existing polyether polyol shown in the reference example. Reference Example 2 A polyether polyol having the following composition was synthesized using the same equipment and method as in Reference Example 1, A), by changing the type of initiator and the ratio of amounts of ethylene oxide to propylene oxide, etc.

[Table] Reference Example 3 The following polyester polyols were synthesized using the same apparatus and method as in the preparation of polyester polyol

[Table] Examples 4 to 7 Using the polyether polyols obtained in Reference Example 2 and the polyester polyols obtained in Reference Example 3, a free foam foam was obtained in the same manner as in Example 1, and after 3 days, the foam was A 20 cm square sample with a thickness of 20 m/m was cut out from the center, and the thermal conductivity at 23° C. was measured in the same manner as in Example 1. The results are shown in Tables 1 and 2. In addition,
The foaming recipe is as follows. Polyol composition 100 parts Foam stabilizer, F-318 1.5 Catalyst, TMHDA 2.0 Freon R-11 (change) Polyisocyanate, 4040cp.Index 1.05 F-318: Siloxane-polyalkylene oxide block copolymer TMHDA manufactured by Shin-Etsu Chemical Co., Ltd. : Tetramethylhexanediamine 4040cp: Manufactured by Takeda Pharmaceutical Modified C-TDI amine equivalent
137, viscosity 700 cps (25°C) The amount of R-11 was (required amount of polyol + isocyanate) x 0.2. From the table, Examples 4 to 7 and 8 to 10 of the present invention
It can be seen that the thermal conductivity is much better than that of Comparative Examples 6 to 9. In addition, from the table, regarding the polyol composition of the present invention, thermal conductivity is low unless the mixed amount of polyester polyol is within an appropriate range compared to the polyether polyol obtained by adding EO and PO to aromatic amine. It can be seen that the form cannot be obtained.

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[Table] Example 18 Experiment (1) Synthesis of polyether polyol J) A 54-necked Kolben equipped with a stirrer, thermometer, alkylene oxide inlet tube, and condenser was used.
- 1115 g of toluylene diamine and 15 g of flaked caustic potash were charged, heated to 95°C, 1000 g of ethylene oxide was reacted at 95 to 110°C, and subsequently 2550 g of propylene oxide was added and reacted at 110 to 115°C. Then, the product was neutralized with an aqueous solution of oxalic acid, and the crystals that crystallized were separated and dehydrated to obtain 4,450 g of polyether polyol. As a result of analysis, this product has a hydroxyl group count of 440 mgKOH/g, a pH of 10.6, and a viscosity of
It was 20,000cps (25℃). Production of polyester polyol a) Diethylene glycol 1100 was added to a 5-capacity reactor equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, a partial condenser, and a condenser for condensed water.
1,350 g of trimethylolpropane and 1,500 g of adipic acid were charged, and while nitrogen gas was introduced, the mixture was heated and reacted at 200 to 210° C. for 9 hours. When the acid value of the product was measured, it was found to be 2.0 mgKOH/g, so it was cooled and used as a product. When the yield was 3500g, the hydroxyl value was analyzed and found to be 450mgKOH/g. Production of polyester polyols b) to e) Polyester polyols b) to e) were obtained using the same equipment and method as polyester polyol a) and the following process. b Ethylene glycol 660g Trimethylolpropane 1350g Adipic acid 1500g c Trimethylolpropane 1350g Diethylene glycol 1270g Adipic acid 2200g d Trimethylolpropane 1350g Diethylene glycol 1100g Adipic acid 2200g e Ethylene glycol 400g Diethylene glycol 6 00g Trimethylolpropane 1350g Adipic acid 1500g Polyester polyol a) and polyester Table 1 shows the hydroxyl values of polyols b) to e).

[Table] Polyether polyols used in the production of regular urethane foam 1 Actocol GR-84 (propylene oxide added to sucrose/glycerin paste, hydroxyl value 460 mgKOH/g, manufactured by Takeda Pharmaceutical) 2 Actocol GR -35 (propylene oxide added to sucrose/amine base, hydroxyl value 400mgKOH/g, manufactured by Takeda Pharmaceutical) Experiment (2) Comparison of electricity consumption of refrigerators based on JIS C9607 Hard material used as insulation material for refrigerators The thermal insulation properties of urethane foam are determined based on power consumption (power consumption per month) based on JIS C-9607 using the same model and cabinet, but with different hard urethane foam formulations. Γ Cabinet used: 240 two-door fan cool type, refrigerator/freezerΓ Test prescription

【table】 Γ Foaming machine used Manufactured by EMB, PU-50 high pressure foaming machine Γ Foaming conditions

【table】 foam machine reactivity

[Table] Injecting foam into the cabinet Preheat the foaming jig to 45-48℃ and attach the cabinet 3 minutes before injecting the foam. Using the above-mentioned foaming machine, a predetermined amount of foam material is injected through injection ports (two locations) provided on the back of the cabinet. After injecting the raw materials, after curing for 8 minutes while open at 60℃, remove the cabinet from the jig. In this way, seven samples each of formulation A and formulation B were obtained. The raw material injection amount is Prescription A.
4.45Kg to 4.53Kg range, 4.48Kg to 4.60Kg/for prescription B
It was within the range of the table. Γ Measurement of thermal conductivity and power consumption Measurement of injected foam with the above formulations A and B, disassembled each cabinet, obtained foam samples from each part, and measured the density and thermal conductivity at 23℃. It was measured. The results were as follows.

[Table] Measurement of power consumption Among the cabinets obtained by injection foaming, five each of formulation A and formulation B were fitted with compressors, doors, and other components to make them operable as normal refrigerators. These were actually operated under the conditions stipulated by JIS C9607, and the power consumption was investigated. As a result, the average electricity consumption of a refrigerator obtained by injection foaming with Formulation B was 29.7KWH/month, whereas
The average amount obtained with prescription A was 27.7KWH/month, and the refrigerator obtained by injection with prescription A was
It has become clear that it is possible to save energy by 2KWH/month. Experiment (3) Examination of the usage ratio of polyether polyol and polyester polyol Urethane foam was manufactured by changing the usage ratio of polyether polyol J) and polyester polyol a) as shown in Table 2. The manufacturing conditions are as follows. For 100 parts of a mixture of polyether polyol and polyester polyol, add 1.5 parts of silicone surfactant (silicon foam stabilizer F-335 manufactured by Shin-Etsu Chemical).
2.0 parts of tetramethylhexanediamine (TMHDA) as a catalyst, 38 parts of Freon R-11, and polymethylene polyphenyl isocyanate (C ₄ MDI, amine equivalent weight 136) were mixed so that the NCO/OH ratio was 1.1, and a 25 cm× A hard urethane foam was obtained by foaming in a box measuring 25 cm x 20 cm (height direction). After leaving this foam indoors for 3 days, we cut out a 20 cm x 20 cm x 2 cm (thickness) foam sample from the inside and measured its thermal conductivity at an average temperature of 23°C using an Anacon Model 88 thermal conductivity meter. did. The foam density was also measured. The results are summarized in Table 2 and Figure 1.

[Table] Experiment (4) Examination of OH value of polyester polyol Polyol obtained by mixing polyether polyol J), polyester polyols a) to e), and two types of ordinary polyether polyols at a ratio of 80:20, respectively. A hard urethane foam was obtained according to the above-mentioned polyurethane foam formulation. After leaving this foam indoors for 3 days,
A foam sample of 20 cm x 20 cm x 2 cm (thickness) was cut out, and its thermal conductivity was measured at an average temperature of 23°C using an Anacon Model 88 thermal conductivity meter. The foam density was also measured. The results are shown in Table 3 and FIG.

【table】 [Brief explanation of the drawing]

FIG. 1 shows the relationship between the mixing ratio of polyether polyol and polyester polyol and the thermal conductivity of the obtained urethane foam. Figure 2 shows the relationship between the OH value of polyester polyol and the thermal conductivity of the obtained urethane foam.

Claims (1)

[Claims] 1. When producing a rigid urethane foam by reacting an organic polyisocyanate and a polyol in the presence of a catalyst, a blowing agent, and a foam stabilizer, about 80% by weight or more of the polyol component is A aromatic. A polyether polyol with a hydroxyl value of 300-550 mgKOH/g obtained by reacting ethylene oxide and propylene oxide with amine as an initiator in a weight ratio of 5-50/95-50 and B hydroxyl value 300 ~550mgKOH/g polyester polyol, and the weight ratio of A to B is 50~90/50~10
A method for producing a hard urethane foam characterized by: