JP5765669B2 - Method for producing polyester polyol and rigid polyurethane foam - Google Patents

Description

  The present invention relates to a method for producing a polyester polyol and a rigid polyurethane foam.

  In general, a rigid polyurethane foam is composed of a mixed liquid (premix liquid) and a polyisocyanate liquid in which a polyol such as polyether polyol and / or polyester polyol, a foaming agent, a catalyst, a surfactant, and a flame retardant as necessary are mixed. Are prepared, mixed, and foamed and cured in a short time. Rigid polyurethane foam is widely used in the form of spraying, pouring, boarding, and paneling in cold storage rooms, refrigerators, freezing rooms, freezers, heat insulating materials for general buildings, and the like because of its excellent heat insulating properties.

  As a foaming agent for producing rigid polyurethane foam, a low-boiling nonpolar organic solvent is generally used. Specifically, so-called chlorofluorocarbons such as CFC foaming agents, HCFC foaming agents, and HFC foaming agents can be used instead. In addition to Freon, HC foaming agents such as pentane and cyclopentane are used. However, since ozone layer devastation became a problem, HCFC-based blowing agents having a small ozone depletion coefficient from CFC-based blowing agents that have been widely used until then, and HFC-based blowing agents having an ozone depletion coefficient of 0, In particular, HFC-245fa and HFC-365mfc are used. On the other hand, in recent years, there is also a problem related to global warming, and switching to a foaming agent having a small global warming potential, such as water, carbon dioxide, and HFO foaming agent, is required.

  Moreover, there are the following major problems in disseminating the water foaming technology. That is, compared with the foaming formulation using the conventional HFC-based foaming agent, the viscosity reducing effect of the foaming agent cannot be obtained, so that the viscosity of the premix liquid is increased, and the reaction between water and the polyisocyanate component Problems such as increased brittleness of the surface and bottom of the resulting urethane foam due to the influence of increased urea groups, etc., and a tendency to reduce the adhesive strength with the adherend, and worsening of flame retardancy A point is mentioned.

  In order to improve the flame retardancy of the rigid polyurethane foam, it is effective to increase the isocyanate index [(mole number of all isocyanate groups) / (mole number of all active hydrogen groups) × 100]. In this case, it is difficult to increase the amount of polyisocyanate due to the so-called liquid ratio problem of the premix liquid / polyisocyanate liquid, and in order to solve this problem, a polyester polyol having a low hydroxyl value is used to reduce the active hydrogen groups. Is mentioned.

  In order to improve the flame retardancy of rigid polyurethane foam while keeping the viscosity of the premix solution low, it has been proposed to use polyester polyols using terephthalic acid and isophthalic acid as the carboxylic acid component and polyethylene glycol as the alcohol component. Yes. (Patent Document 1)

  However, when a polyester polyol having a low hydroxyl value is synthesized using polyethylene glycol as an alcohol component, the resulting polyester polyol has a high melting point, which causes a problem of freezing in winter. Here, “freezing” refers to a change in state that eliminates fluidity. And when the polyester polyol stored in a tank or the like freezes, it is necessary to heat and keep the tank and piping, etc., it is not efficient, and there is a possibility that the component of the polyester polyol is biased by remelting. is there.

JP 2011-16854 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a polyester polyol having a low viscosity and a low hydroxyl value that does not freeze even in a low temperature period such as winter. Another object of the present invention is to provide a method for producing a rigid polyurethane foam having excellent flame retardancy.

  As a result of intensive studies, the present inventor obtained knowledge that the above object can be easily achieved by using a polyester polyol having a specific structural characteristic as a raw material polyol, and completed the present invention. It came to.

  That is, the first gist of the present invention includes a carboxylic acid component containing isophthalic acid and / or terephthalic acid, a polyethylene glycol having a number average molecular weight of 200 to 1000, and a polypropylene glycol having a number average molecular weight of 200 to 1000. A polyester polyol obtained by an esterification reaction with an alcohol component, having a hydroxyl value of 50 to 150 mgKOH / g and a viscosity at 25 ° C. of 2000 mPa · s or less.

  The second gist of the present invention is that, in the method for producing a rigid polyurethane foam using at least a polyisocyanate, a polyol, a foaming agent, a catalyst, and a surfactant as a raw material, the polyester polyol is used as a polyol with respect to all the polyols. It exists in the rigid polyurethane foam characterized by using 10 to 90 weight%.

  According to the present invention, a low-viscosity and low hydroxyl value polyester polyol that does not freeze even in a low temperature period such as in winter, and a rigid polyurethane foam excellent in flame retardancy using the polyester polyol are provided. I can do it.

  Hereinafter, the present invention will be described in detail.

(Polyester polyol)
The polyester polyol of the present invention can be obtained by esterifying a carboxylic acid component and an alcohol component. As the carboxylic acid component, isophthalic acid and / or terephthalic acid is used. Isophthalic acid is characterized by faster esterification than terephthalic acid, but terephthalic acid is superior to isophthalic acid from the viewpoint of flame retardancy.

  Further, in order to reduce the viscosity of the polyester polyol and improve the brittleness and adhesiveness of the resulting rigid polyurethane foam, it is preferable to further use adipic acid and / or succinic acid. The amount used is usually 5 to 50% by weight, preferably 10 to 40% by weight, more preferably 15 to 30% by weight of the total carboxylic acid component.

  Examples of carboxylic acids that can be used in addition to the above include monovalent or polyvalent carboxylic acids. Examples of the monovalent carboxylic acid include aliphatic monovalent carboxylic acids such as acetic acid and octylic acid; aromatic monovalent carboxylic acids such as benzoic acid and methylbenzoic acid, and vegetable fats and oils or vegetable oil fatty acids may be used. I can do it.

  Examples of the polyvalent carboxylic acid include aliphatic polyvalent carboxylic acids such as sebacic acid, maleic acid, and fumaric acid; and aromatic polyvalent carboxylic acids such as orthophthalic acid, trimellitic acid, and pyromellitic acid. These aromatic or aliphatic carboxylic acids can be used alone or in combination of two or more.

  As the alcohol component, polyethylene glycol having a number average molecular weight of 200 to 1000 and polypropylene glycol having a number average molecular weight of 200 to 1000 are used.

  Examples of the polyethylene glycol having a number average molecular weight of 200 to 1000 include commercially available polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 400, polyethylene glycol 600, and polyethylene glycol 1000. Of these, polyethylene glycol having a number average molecular weight of 300 to 800 is preferably used, and polyethylene glycol having a number average molecular weight of 400 to 600 is more preferably used.

  The polyethylene glycol 200 refers to a polyethylene glycol having a number average molecular weight of 200, and the polyethylene glycol 400 refers to a polyethylene glycol having a number average molecular weight of 400. Usually, commercially available polyethylene glycol is a mixture of polyethylene glycols having different molecular weights, but is classified according to the difference in number average molecular weight.

  The amount of polyethylene glycol having a number average molecular weight of 200 to 1000 is usually 30 to 80% by weight, preferably 35 to 75% by weight, more preferably 40 to 70% by weight based on the total charged weight of the alcohol component and the carboxylic acid component. %. If it is less than 30% by weight, the effect of lowering the viscosity of the polyester polyol of the present invention is small. On the other hand, if it exceeds 80% by weight, the polyester polyol may freeze in a low temperature period such as winter.

  Examples of the polypropylene glycol having a number average molecular weight of 200 to 1000 include commercially available polypropylene glycol 200, polypropylene glycol 300, polypropylene glycol 400, polypropylene glycol 600, and polypropylene glycol 1000. Of these, polypropylene glycol having a number average molecular weight of 300 to 800 is preferably used, and polypropylene glycol having a number average molecular weight of 400 to 600 is more preferably used.

  The amount of the polypropylene glycol having a number average molecular weight of 200 to 1000 is usually 10 to 60% by weight, preferably 15 to 55% by weight, more preferably 20 to 50% by weight based on the total charged weight of the alcohol component and the carboxylic acid component. %. If it is less than 10% by weight, there is a concern that the polyester polyol will freeze in a low temperature period such as in winter, and if it exceeds 60% by weight, the esterification reaction rate decreases.

  Examples of alcohol components that can be used in addition to the above include monohydric or polyhydric alcohols. Examples of monohydric alcohols include aliphatic monohydric alcohols such as methanol, ethanol, propanol, butanol, octanol and lauryl alcohol; aromatic monohydric alcohols such as benzyl alcohol and phenol; ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, A monohydric alcohol containing an ether bond such as phenoxyethanol can be mentioned.

  Examples of the polyhydric alcohol include aliphatic polyhydric alcohols such as ethylene glycol, propanediol, and butanediol; oxyalkylene glycols such as diethylene glycol, triethylene glycol, and dipropylene glycol; polyethylene glycol (having a number average molecular weight of 200 to 1,000) And polyoxyalkylene glycols such as polytetramethylene ether glycol, polypropylene glycol (excluding polypropylene glycol having a number average molecular weight of 200 to 1000), and the like. In addition, trihydric or higher alcohols such as glycerin and trimethylolpropane may be used. Two or more of these monohydric alcohols and polyhydric alcohols may be used in combination.

  The hydroxyl value of the polyester polyol of the present invention is 40 to 150 mgKOH / g, preferably 45 to 145 mgKOH / g, more preferably 50 to 140 mgKOH / g. When the hydroxyl value is less than 40 mgKOH / g, the viscosity of the polyester polyol increases, making it difficult to handle. On the other hand, when the hydroxyl value exceeds 150 mgKOH / g, a premix is produced when a rigid polyurethane foam is produced using the polyester polyol. It is difficult to increase the amount of polyisocyanate due to the problem of so-called liquid ratio, which is the ratio of liquid to polyisocyanate.

  The viscosity of the polyesterol of the present invention at 25 ° C. is 2000 mPa · s or less, preferably 1800 mPa · s or less, more preferably 1600 mPa · s or less. When the viscosity exceeds 2000 mPa · s, when the rigid polyurethane foam is produced using the polyester polyol, the viscosity of the premix liquid is increased and the handling becomes difficult. On the other hand, the lower limit is not particularly limited, but is about 100 mPa · s considering the preferable range of the hydroxyl value.

  In the production of the polyester polyol of the present invention, an esterification catalyst such as Lewis acid or Bronsted acid is usually used as a catalyst. Examples of the Lewis acid include orthotitanate esters such as tetraisopropyl titanate and tetra-n-butyl titanate; tin compounds such as diethyl tin oxide and dibutyl tin oxide; and metal compounds such as zinc oxide. Examples of Bronsted acid include sulfuric acid, paratoluenesulfonic acid, methanesulfonic acid and the like. Among these, orthotitanate is preferable from the viewpoint that the residual catalyst does not adversely affect the urethanization reaction.

  The amount of the esterification catalyst used is usually 0.1% by weight or less, preferably 0.07% by weight or less, more preferably 0.05% by weight or less, based on the total charge weight of the alcohol component and the carboxylic acid component. Depending on the use of the rigid polyurethane foam, the reaction may be carried out without using an esterification catalyst, or a deactivation treatment may be performed after the reaction, or it may be removed by purification or the like.

  In the production of the polyester polyol of the present invention, the end point of the esterification reaction is usually determined by the amount of unreacted carboxyl groups of the carboxylic acid used. On the other hand, the presence of an acid content in the premix solution may reduce the reactivity of urethanization by the action of an amine catalyst or the like, or may affect the storage stability of the premix solution. Therefore, the amount of unreacted carboxylic acid, that is, the acid value is preferably as low as possible. The acid value of the polyester polyol of the present invention is usually 3 mgKOH / g or less, preferably 2 mgKOH / g or less, more preferably 1 mgKOH / g or less. On the other hand, the lower limit is not particularly limited, but is about 0.1 mgKOH / g in consideration of reaction conditions and reaction time.

  In the method for producing a polyester polyol of the present invention, the reaction conditions such as the reaction temperature and reaction pressure of the esterification reaction are not particularly limited, and known methods can be used.

(Method for producing rigid polyurethane foam)
The method for producing a rigid polyurethane foam according to the present invention uses at least polyisocyanate, polyol, foaming agent, catalyst and surfactant as raw materials, and uses the polyester polyol of the present invention as a polyol in an amount of 10 to 90% by weight based on the total polyol. It is characterized by that. When the amount of use of the polyester polyol of the present invention is less than 10% by weight, the flame resistance of the resulting rigid polyurethane foam is lowered, whereas when it exceeds 90% by weight, the mechanical strength of the obtained rigid polyurethane foam is lowered. There is a case. The amount of the polyester polyol of the present invention is preferably 15 to 80% by weight, more preferably 20 to 75% by weight.

  In the present invention, other polyols include known polyester polyols, polyether polyols, polymer polyols and the like having a hydroxyl value of 30 to 800 mg KOH / g and a functional group number of 1.1 to 8. These may be used alone or in combination of two or more.

  Examples of other polyester polyols include aromatic or aliphatic carboxylic acids such as benzoic acid, orthophthalic acid, terephthalic acid, isophthalic acid, succinic acid, adipic acid, maleic acid, fumaric acid, trimellitic acid, and pyromellitic acid. One or more types, octanol, ethylene glycol monomethyl ether, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propanediol, dipropylene glycol, tripropylene glycol, polypropylene glycol, butanediol, pentanediol, hexanediol, glycerin, triglyceride Polyester polyols obtained by esterification reaction with one or more kinds of 1 to 4 valent alcohols such as methylolpropane and pentaerythritol, butyrolacto , Polyester polyols obtained by ring-opening polymerization of caprolactone. The hydroxyl value of these polyester polyols is usually 50 to 500 mgKOH / g, preferably 55 to 450 mgKOH / g, more preferably 60 to 400 mgKOH / g, and the number of functional groups is usually 1.1 to 3.0, preferably 1. It is 2-2.8, More preferably, it is 1.5-2.5.

  Examples of the other polyether polyols include polymers obtained by polymerizing one or more alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran; ethylene glycol, propanediol, glycerin, and trimethylolpropane. Adducts of alcohols such as pentaerythritol, erythritol, sorbitol, and sucrose with the above alkylene oxides; adducts of amines such as ethylenediamine and toluenediamine with the above alkylene oxides; Mannich modified polyols, polymer polyols, etc. It is done. The hydroxyl value of these polyether polyols is usually 30 to 800 mgKOH / g, preferably 35 to 750 mgKOH / g, more preferably 40 to 700 mgKOH / g, and the number of functional groups is usually 2.0 to 8.0, preferably 2. 0.0 to 7.5, more preferably 2.0 to 7.0. These polyether polyols may be used alone or in combination of two or more.

  In the present invention, in addition to the above-mentioned other polyols, alcohols such as ethylene glycol, diethylene glycol, propanediol, butanediol and glycerin, alkanolamines such as diethanolamine and triethanolamine, and the like can be used in combination.

  As the foaming agent, a foaming agent having an ozone depletion coefficient of 0 and a global warming potential of 50 or less is preferable. Specific examples include HFO foaming agents such as water, HFO-1234ze and HFO-1234yf, and HC foaming agents such as pentane and cyclopentane. In particular, water acts as a blowing agent by generating carbon dioxide gas by reaction with polyisocyanate. Therefore, it is preferable to use only water as the foaming agent in consideration of the environment.

  The blending amount of the foaming agent is appropriately selected depending on the density of the target rigid polyurethane foam. When only water is used, it is usually 1 to 25% by weight, preferably 2 to 23% by weight, more preferably based on the polyol. 3 to 20% by weight. If it is less than 1% by weight, the density of the resulting rigid polyurethane foam becomes too high to be practical, while if it exceeds 25% by weight, physical properties such as dimensional stability deteriorate.

  As a catalyst, the well-known catalyst used for a normal rigid polyurethane foam is used. For example, in addition to amine-based catalysts such as triethylenediamine and N, N-tetramethylhexanediamine, potassium-based quaternary ammonium salts and potassium octylate; tin-based dibutyltin dilaurate and tin octylate; octylic acid Examples thereof include lead-based metal catalysts such as lead. The blending amount of the catalyst is appropriately selected depending on the reactivity and physical properties of the target rigid polyurethane foam, but it is general to combine a foaming catalyst, a resination catalyst, a balanced catalyst, a trimerization catalyst and the like.

  The surfactant may be any of nonionic, anionic and cationic, but is preferably a nonionic surfactant, and particularly preferably a silicone surfactant. The amount of these surfactants used is 0.5 to 10% by weight based on the polyol. If the amount is less than 0.5% by weight, the effect of using the surfactant cannot be obtained. On the other hand, if the amount exceeds 10% by weight, physical properties commensurate with the cost may not be obtained. Surfactants may be used alone or in combination of two or more.

  In the present invention, other auxiliary agents can be used as necessary. As other auxiliaries, various compounds can be used as additives and auxiliaries depending on applications. For example, a flame retardant, a viscosity reducing agent, etc. are mentioned as a typical additive. For example, the flame retardant usually includes chloroalkyl phosphates such as tris (betachloroethyl) phosphate, tris (betachloropropyl) phosphate, and the like. Examples of the viscosity reducing agent include propylene carbonate, ethylene carbonate, and tetraglyme. Additives and auxiliaries other than those described above are not particularly limited.

  The polyisocyanate is not particularly limited as long as it is a compound having two or more isocyanate groups in one molecule. For example, aliphatic, alicyclic, aromatic polyisocyanate or modified products thereof may be used. Specifically, examples of the aliphatic and alicyclic polyisocyanates include hexamethylene diisocyanate and isophorone diisocyanate. Examples of the aromatic polyisocyanate include tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylene polymethylene polyisocyanate and the like, and these carbodiimide modified products and prepolymers can also be used.

  Among these polyisocyanates, preferred polyisocyanates are aromatic polyisocyanates or modified products thereof, and particularly preferred are diphenylmethane diisocyanate, polyphenylene polymethylene polyisocyanate, tolylene diisocyanate, and modified products thereof. As the polyphenylene polymethylene polyisocyanate, those having an isocyanate group content of usually 25 to 35% by weight and a viscosity of usually 500 mPa · s (25 ° C.) or less are preferably used. Among these modified products, carbodiimide modified products are those in which a carbodiimide bond is introduced using a known phosphorus catalyst or the like. The prepolymer is obtained by reacting the above polyisocyanate with a polyol, leaving an isocyanate group at the terminal. In that case, the polyol component used when manufacturing a rigid polyurethane can be used as a polyol component to be used. These polyisocyanates may be used alone or in combination of two or more.

  In the present invention, additives and auxiliaries may be mixed with the polyisocyanate depending on the application. For example, for the purpose of improving the mixing property with the aforementioned polyol, foaming agent, catalyst and surfactant, a surfactant also used in a hard polyurethane foam composition may be used in combination as a compatibilizing agent. In this case, a nonionic surfactant is preferable, and a silicone surfactant is particularly preferable. Moreover, a flame retardant may be used together for the purpose of improving flame retardancy and adjusting viscosity. Usually, chloroalkyl phosphates such as tris (betachloroethyl) phosphate and tris (betachloropropyl) phosphate are used. Additives and auxiliaries other than those described above are not particularly limited, and may be used as long as they are used for the purpose of improving physical properties and operability in ordinary resins and do not have a significant adverse effect. Absent.

  In the present invention, the isocyanate index of the rigid polyurethane foam is usually 50 to 400, preferably 60 to 390, and more preferably 70 to 380. When the isocyanate index is less than 50, the resulting rigid polyurethane foam may not have sufficient strength. On the other hand, when it exceeds 200, the resulting rigid polyurethane foam tends to have high brittleness and lower adhesive strength. It is in.

  In the present invention, foam curing can be performed as follows. That is, practically, polyisocyanate is liquid A, polyol is liquid B (premix liquid), and a foaming agent, a catalyst, a surfactant, and other auxiliary agents as necessary are mixed in liquid B appropriately. Then, the two liquids are mixed, foamed and cured using an apparatus described later. The foaming agent, catalyst, and surfactant are preferably mixed in the B liquid. However, in some cases, the foaming agent, the catalyst, and the surfactant are mixed in the A liquid, or the respective components are not mixed until just before the urethanization reaction, and three or more kinds are mixed. Sometimes handled as a raw material liquid.

  Any apparatus can be used as the above apparatus as long as the A liquid and the B liquid can be mixed uniformly. For example, in addition to small mixers, low pressure or high pressure foaming machines for injection foaming, low pressure or high pressure foaming machines for slab foaming, low pressure or high pressure foaming machines for continuous lines, spraying work A spray foaming machine or the like can be used. In addition, when manufacturing rigid polyurethane foam, each liquid temperature of A liquid and B liquid is normally adjusted to 20-60 degreeC.

In the present invention, the density of the rigid polyurethane foam obtained is represented by the core density of the free foam, and is usually 10 to 50 kg / m ³ , preferably 15 to 45 kg / m ³ , and more preferably 20 to 40 kg / m ³ . When the density is less than 10 kg / m ³ , flame retardancy and mechanical strength are insufficient, and when it exceeds 50 kg / m ³ , the cost is high.

  The rigid polyurethane foam obtained by the production method of the present invention can be provided with an appropriate face material on one side or both sides as required. As the face material, for example, paper, wood, gypsum board, resin, aluminum foil, steel plate and the like are used.

  Hereinafter, specific embodiments of the present invention will be described in more detail by way of examples. However, the present invention is not limited by these examples unless it exceeds the gist.

(Examples 1-4 and Comparative Examples 1-3)
<Synthesis of polyester polyol>
The polyester polyol is synthesized by esterifying the carboxylic acid component and the alcohol component shown in Table 1 at the ratio shown in the same table, and the acid value, hydroxyl value, viscosity (25 ° C.) and moisture are measured by the following methods. In addition, low-temperature storage stability was evaluated. The results are shown in Table 1. In addition, about the comparative example 2, since esterification reaction was not completed, it abandoned on the way.

<Analysis method>
(1) Acid value:
It measured based on JIS K1557 ₁₉₇₀ .
(2) Hydroxyl value:
It measured based on JIS K1557 ₁₉₇₀ .
(3) Viscosity:
Based on JIS K1557 ₁₉₇₀ , it measured at 25 degreeC using the rotational viscometer (B type viscometer).
(4) Moisture:
It measured based on JIS K1557 ₁₉₇₀ .

<Evaluation of low-temperature storage stability>
Polyester polyols A-1 to A-6 were put in a sealed container and stored in a thermostatic bath at -10 ° C for 1 week. The state of the polyester polyols A-1 to A-6 in the container after 1 week storage is visually confirmed. If it is not frozen, it is “◯”, and if it is frozen, it is “x”. evaluated.

<Abbreviations of raw materials in Table 1>
IPA: Isophthalic acid TPA: Terephthalic acid ADA: Adipic acid SCA: Succinic acid PEG400: Polyethylene glycol 400
PEG600: Polyethylene glycol 600
PPG400: Polypropylene glycol 400

(Examples 5 to 8 and Comparative Examples 4 and 5)
<Creation of rigid polyurethane foam>
Using the raw materials shown in Table 2, mixing was performed according to the formulation shown in Table 3 to prepare a premix solution. Next, a predetermined amount of the obtained premix liquid and polyisocyanate liquid are taken into a polycup, mixed at a high speed with an electric mixer, and then poured into a mold prepared with steel plate face materials on the upper and lower surfaces, and clamped to form a rigid polyurethane foam. A steel sheet face material sandwich panel was prepared. Table 4 shows the conditions at that time. As the polyisocyanate liquid, polymeric MDI (“Millionate MR-200” manufactured by Nippon Polyurethane Industry Co., Ltd.) was used, and the isocyanate index was set to 300. And about the said sandwich panel, the corn calorie test and the adhesive strength measurement were done with the following method. The results are shown in Table 3.

<Cone calorie test>
A test piece was prepared by cutting the center part of a steel panel face material sandwich panel of rigid polyurethane foam into 99 × 99 mm, and flame retardancy was evaluated by a cone calorie test. The corn calorie test was performed in accordance with ISO 5660-1 (2002), and the test time was 10 minutes (semi-incombustible). Judgment criteria are as follows.

<Cone calorie test (quasi-incombustible) criteria>
(1) The total calorific value for 10 minutes after the start of heating is 8 MJ / m ² or less.
(2) There should be no cracks or holes penetrating to the back side, which is harmful to fire protection, for 10 minutes after the start of heating.
(3) The maximum heat generation rate should not exceed 200 kW / m ² for 10 minutes after the start of heating for 10 seconds or more.

<Measurement of adhesive strength>
A panel using a 5 × 5 cm steel sheet surface material was separately prepared on the upper surface, and the adhesive strength between the steel sheet surface material and the rigid polyurethane foam was measured using a tensile tester. Judgment criteria are as follows.

<Adhesion strength criteria>
◎: 200 kPa or more ○: 100 kPa or more, less than 200 kPa ×: less than 100 kPa

  From the above results, the following is mainly clear.

(1) Comparison results between Examples 1 to 4 and Comparative Examples 1 and 3:
While the polyester polyols (A-1 to A-4) of Examples 1 to 4 have good low-temperature storage stability, the polyester polyol (A-5) of Comparative Example 1 using only polyethylene glycol as the alcohol component. Became frozen and low-temperature storage stability became poor. The polyester polyol (A-6) of Comparative Example 3 using only adipic acid as the carboxylic acid component has good low-temperature storage stability, but the rigid polyurethane foam obtained using this as a raw material is Comparative Example 5 described later. The corn calorie test fails as evaluated in.

(2) Comparison results between Examples 5 to 8 and Comparative Examples 4 and 5:
The hard polyurethane foams of Examples 5 to 8 obtained using the polyester polyols (A-1 to A-3) of Examples 1 to 3 as raw materials pass the corn calorie test and have good adhesion. The rigid polyurethane foam of Comparative Example 4 using only the terephthalic acid-based polyester polyol (“Maximol RFK-505” manufactured by Kawasaki Kogyo Co., Ltd.) as the alcohol component has poor adhesion. The rigid polyurethane foam of Comparative Example 5 obtained as the polyester polyol (A-6) raw material of Comparative Example 3 fails the corn calorie test.

Claims (6)

  It is obtained by esterifying a carboxylic acid component containing isophthalic acid and / or terephthalic acid and an alcohol component containing polyethylene glycol having a number average molecular weight of 200 to 1000 and polypropylene glycol having a number average molecular weight of 200 to 1000. A polyester polyol having a hydroxyl value of 50 to 150 mgKOH / g and a viscosity at 25 ° C. of 2000 mPa · s or less.   The amount of polyethylene glycol having a number average molecular weight of 200 to 1000 is 30 to 80% by weight and the amount of polypropylene glycol having a number average molecular weight of 200 to 1000 is 10 to 60 based on the total charged weight of the alcohol component and the carboxylic acid component. The polyester polyol according to claim 1, wherein the polyester polyol is in% by weight.   The polyester polyol according to claim 1 or 2, wherein adipic acid and / or succinic acid is further used as the carboxylic acid component in an amount of 5 to 50% by weight based on the total carboxylic acid component.   In the manufacturing method of the hard polyurethane foam which uses a polyisocyanate, a polyol, a foaming agent, a catalyst, and surfactant as a raw material at least, the polyester polyol in any one of Claims 1-3 is 10-90 with respect to all the polyols as a polyol. A method for producing a rigid polyurethane foam, characterized by using% by weight.   The method for producing a rigid polyurethane foam according to claim 4, wherein a foaming agent having an ozone depletion coefficient of 0 and a global warming coefficient of 50 or less is used as the foaming agent.   The method for producing a rigid polyurethane foam according to claim 4, wherein only water is used as the foaming agent, and the amount used is 1 to 25 parts by weight with respect to 100 parts by weight of polyol.