JP2008081555A - Polyol composition for rigid polyurethane foam, method for producing rigid polyurethane foam, and method for applying heat insulation to low-temperature tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyol composition for rigid polyurethane foam, using water as a foaming agent, enabling a polyol composition and an isocyanate component to be easily mixed/stirred, and having a low viscosity to afford high agitation efficiency; to provide a method excellent in operability for producing the rigid polyurethane foam having excellent compression strength and heat insulation characteristics; and to provide a method for applying heat insulation to a low-temperature tank, suitable for filling a gap part of the tank and a heat-insulation material or the like. <P>SOLUTION: The polyol composition for the rigid polyurethane foam comprises a polyol component, a foaming agent, a foam stabilizer and a catalyst. Water is used as the foaming agent, and a polyol compound and a low-molecular weight polyhydric alcohol are contained as the polyol component. The polyol compound has 450-650 mg KOH/g hydroxy value, and average four to six functional groups, and the low-molecular weight polyhydric alcohol is a liquid alcohol, and has four or less functional groups. The ratio of the polyol compound to the low-molecular weight polyhydric alcohol is (0/100)-(55/45) (by weight). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyol composition for rigid urethane foam, a method for producing rigid urethane foam, and a heat insulation construction method for a low-temperature tank.

  Conventionally, in order to improve the heat insulation of a low temperature tank or the like, a method has been adopted in which a panel is bonded to the outer surface of the tank and a hard urethane foam is filled in the gap to improve the heat insulation.

  The rigid urethane foam is formed by mixing a polyol composition containing a polyol component and a foaming agent as essential components and an isocyanate component, and then foaming and curing. Conventionally, a freon compound or an HCFC compound is used as the foaming agent. It was used.

  However, from the viewpoint of environmental conservation, use of pentanes or the like as a foaming agent instead of halogen compounds such as HCFC compounds has been proposed (Patent Document 1). However, the use of pentanes is effective in terms of cost, but has a problem of poor workability because it has high volatility and is easily flammable.

  Therefore, switching to water is required as a foaming agent. However, if water is used as the blowing agent, the viscosity of the polyol composition will increase, and the polyol composition and the isocyanate component cannot be mixed and stirred at the site where power such as a motor cannot be used. It becomes difficult to fill the gap between the tank outer surface and the panel with the hard urethane foam.

JP 2000-125991 A

  Therefore, the object of the present invention is a low viscosity that can easily mix and stir the polyol composition and the isocyanate component without the power of a motor or the like, even when water is used as a foaming agent, and has high stirring efficiency. Polyol composition for rigid urethane foam, manufacturing method of rigid urethane foam excellent in compressive strength and heat insulation properties, workability, and filling of rigid urethane foam in voids such as tanks and heat insulating materials, for example, joints The object is to provide a heat insulation construction method suitable for a low temperature tank.

The present invention provides a rigid urethane foam polyol composition comprising a polyol component, a foaming agent, a foam stabilizer, and a catalyst.
The blowing agent is water;
The polyol component includes a polyol compound and a low molecular weight polyhydric alcohol,
The polyol compound has a hydroxyl value of 450 to 650 mgKOH / g and an average functional group number of 4 to 6,
The low molecular weight polyhydric alcohol is a liquid alcohol having a functional group number of 4 or less,
A ratio of the polyol compound and the low molecular weight polyhydric alcohol is polyol compound / low molecular weight polyhydric alcohol = 0/100 to 55/45 (weight ratio), which is a polyol composition for rigid urethane foam.

  With the above configuration, it is possible to obtain a polyol composition having a low viscosity and a high stirring efficiency that can easily mix and stir the polyol composition and the isocyanate component without the power of a motor or the like.

  The viscosity of the rigid urethane foam polyol composition is preferably 0.8 Pa · s (20 ° C.) or less. In a place where a stirring device using power such as a motor cannot be used, the polyol composition and the isocyanate component need to be stirred and mixed by hand using a shaker or the like, so the viscosity is low. Is preferred.

  In the method for producing a rigid urethane foam of the present invention, it is preferable that the polyol composition for rigid urethane foam and an isocyanate component are mixed and foamed and cured. By the manufacturing method, a rigid urethane foam excellent in compressive strength, heat insulating properties and workability can be obtained.

  In the heat insulation construction method for a low temperature tank according to the present invention, a heat insulating material is provided on the outer peripheral surface of the low temperature tank, and the hard portion is provided in the space between the outer peripheral surface of the low temperature tank and the heat insulating material and / or the space between the heat insulating materials. It is preferable to inject a urethane composition obtained by stirring and mixing a polyol composition for urethane foam and an isocyanate component, and to foam and cure.

  By using the heat insulation construction method for the low temperature tank, even a gap between the outer peripheral surface of the low temperature tank and the heat insulation and / or a gap between the heat insulation can be filled with the hard urethane foam. Therefore, excellent compressive strength and heat insulating properties can be imparted, and the workability is also excellent.

  Hereinafter, embodiments of the present invention will be described in detail.

  In the present invention, water is used as a foaming agent. By using water, a rigid urethane foam having excellent strength and effective for environmental protection can be obtained.

  The amount of water added is preferably 1 to 3 parts by weight, more preferably 1.5 to 2.5 parts by weight, based on 100 parts by weight of the total polyol component. If the amount of water added is less than 1 part by weight, the urethane foam density increases and the thermal conductivity deteriorates. On the other hand, when it exceeds 3 parts by weight, the urethane foam density is lowered, and the compressive strength is also lowered accordingly.

  The polyol compound in the present invention has a hydroxyl value of 450 to 650 mgKOH / g or more and an average functional group number of 4 to 6, preferably a hydroxyl value of 500 to 600 mgKOH / g and an average functional group number of 5 to 6, more preferably. Has a hydroxyl value of 500 to 550 mgKOH / g and an average number of functional groups of 5. If the hydroxyl value is less than 450 mgKOH / g, the compressive strength tends to decrease, and if it exceeds 650 mgKOH / g, the exothermic temperature becomes high and scorch (burning) occurs in the urethane foam. Moreover, when the average number of functional groups is less than 4, the compressive strength tends to decrease. When the average number of functional groups exceeds 6, urea bonds increase, the urethane foam tends to become brittle, and the thermal conductivity deteriorates.

  Examples of the polyol compound in the present invention include aliphatic polyester polyols and polyether polyol compounds. Since the aliphatic polyester polyol has good low temperature characteristics, it is effective when used in a low temperature tank or the like.

  In addition, in this invention, since water is used as a foaming agent, there exists a possibility that the ester bond of the said aliphatic polyester polyol may be hydrolyzed. Therefore, the use within the range which does not interfere with the characteristic requested | required by this invention is preferable.

  On the other hand, specific examples of polyether polyol compounds include aliphatic polyols and amine polyols exemplified below.

  As the aliphatic polyol, a polyfunctional active hydrogen compound, that is, an aliphatic or alicyclic polyfunctional active hydrogen compound as a polyol initiator, an alkylene oxide, specifically, propylene oxide (PO), ethylene oxide (EO), Examples include polyfunctional oligomers obtained by ring-opening addition polymerization of one or more cyclic ethers such as styrene oxide (SO) and tetrahydrofuran. In particular, it is preferable to use a polyether polyol obtained by addition polymerization of PO or PO and EO.

  Examples of the initiator of the polyol include glycols such as ethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, neopentyl glycol, and trimethylolpropane. And triols such as glycerin, tetrafunctional alcohols such as pentaerythritol, and polyhydric alcohols such as sorbitol.

  As the amine-based polyol, primary or secondary amine as a polyol initiator, alkylene oxide, specifically, one or more of propylene oxide (PO), ethylene oxide (EO), styrene oxide (SO), tetrahydrofuran, etc. Examples thereof include polyfunctional polyol compounds obtained by ring-opening addition polymerization. In particular, it is preferable to use a polyether polyol obtained by addition polymerization of PO or PO and EO.

  Examples of the initiator for the polyol include aliphatic or aromatic amines such as ethylenediamine, toluenediamine, and diphenylmethanediamine, and alkanolamines such as monoethanolamine and diethanolamine.

  As the polyether polyol compound, an aromatic ring-containing polyether polyol compound obtained by ring-opening addition of at least one of PO, EO, and SO to hydroquinone, bisphenol A, etc., to a polyfunctional active hydrogen compound can also be used.

  The above polyol compounds may be used alone or in combination with two or more types to form a foam having more preferable characteristics.

  The low molecular weight polyhydric alcohol in the present invention is a liquid alcohol having 4 or less functional groups, preferably 3 or less, more preferably 2 functional groups. When the number of functional groups exceeds 4, the crosslinking density increases and the brittleness tends to deteriorate.

  Examples of the low molecular weight polyhydric alcohol include glycols such as ethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, neopentyl glycol, and trimethylol. Examples thereof include triols such as propane and glycerin, and tetrafunctional alcohols such as pentaerythritol. Preferred are glycols and triols, and more preferred are either or both of dipropylene glycol and glycerin.

  The ratio of the polyol compound and the low molecular weight polyhydric alcohol is polyol compound / low molecular weight polyhydric alcohol = 0/100 to 55/45 (weight ratio), preferably 10/90 to 45/55. When the weight ratio exceeds 55/45, the viscosity becomes high, and mixing and stirring of the polyol composition and the isocyanate component using a shaker or the like cannot be performed at a site where the stirring device cannot be used.

  The viscosity of the polyol composition for rigid urethane foam of the present invention is preferably 0.8 Pa · s (20 ° C.) or less, more preferably 0.7 Pa · s (20 ° C.) or less. In the present invention, since the polyol composition and the isocyanate component are stirred and mixed using a shaker or the like at a site where a stirring device cannot be used, the viscosity is preferably low. For example, the polyol component has a low molecular weight and a high molecular weight. In the case of a monohydric alcohol alone, the viscosity can be lowered to that of the low molecular weight polyhydric alcohol alone. On the other hand, when the viscosity exceeds 0.8 Pa · s (20 ° C.), the stirring efficiency deteriorates, and the polyol composition and the isocyanate component cannot be mixed and stirred using a shaker or the like.

  As an isocyanate component that forms a rigid urethane foam by mixing and reacting with the polyol composition in the present invention, it can be used without limitation, but it is easy to handle, the physical properties of the resulting rigid urethane foam are excellent, and low cost. Therefore, it is preferable to use liquid diphenylmethane diisocyanate (liquid MDI). As liquid MDI, Crude MDI (c-MDI) (Sumijoule 44V-10, Sumijoule 44V-20, etc. (manufactured by Sumika Bayer Urethane Co., Ltd.), Millionate MR200 (manufactured by Nippon Polyurethane Industry)), uretonimine-containing MDI (Millionate MTL) Manufactured by Nippon Polyurethane Industry) or the like. In addition to liquid MDI, other isocyanate components may be used in combination. As the isocyanate component used in combination, an isocyanate component and an isocyanate group-terminated prepolymer known in the technical field of polyurethane can be used without limitation.

  In the production of the rigid urethane foam of the present invention, the equivalent ratio (NCO index) of isocyanate groups to active hydrogen groups is preferably 1.0 to 1.3. When the NCO index exceeds 1.3, a large amount of unreacted isocyanate remains, so that the reaction proceeds quickly and the formability of the foam tends to deteriorate. On the other hand, if it is less than 1.0, the compressive strength tends to decrease.

  The reactivity of the urethane composition obtained by stirring and mixing the polyol composition for rigid urethane foam and the isocyanate component in the present invention is 1 to 2 minutes after injecting the urethane composition into the void, and the gel time is It is preferable to use one adjusted to 3 to 6 minutes, a tack free time of 7 to 8 minutes, and a rise time of 7 to 9 minutes. In the field where a stirring device having power such as a motor cannot be used, the foaming / curing reaction of the urethane composition needs to control the curing time and the like. For example, when the reaction time is short, the work may not be completed within the reaction time. On the other hand, when the reaction time is long, it is necessary to fix the low temperature tank and the panel as a heat insulating material until the curing reaction is completed, which causes a decrease in workability.

  In the production of the rigid urethane foam of the present invention, catalysts, thickeners, foam stabilizers, crosslinking agents, flame retardants, colorants, antioxidants and the like well known to those skilled in the art can be used.

  Examples of the catalyst include triethylenediamine, N-methylmorpholine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetramethylhexamethylenediamine, N, N-dimethylcyclohexylamine, Tertiary amines such as diazabicycloundecene (DBU), and metal catalysts such as dibutyltin dilaurate, dibutyltin diacetate, and tin octylate are exemplified as the urethanization reaction catalyst. In addition, since the polyol composition of this invention uses water as a foaming agent, since an organotin type catalyst is hydrolyzed and deteriorated, use of a tertiary amine catalyst is preferable.

  In the structure of the polyurethane molecule, it is possible to use a catalyst that forms an isocyanurate bond that contributes to the improvement of flame retardancy, and examples thereof include potassium acetate and potassium octylate. Some of the above-mentioned tertiary amine catalysts promote the isocyanurate ring formation reaction. It is also possible to use a catalyst that promotes isocyanurate bond formation and a catalyst that promotes urethane bond formation.

  As the foam stabilizer, a foam stabilizer for rigid urethane foam can be used without limitation. In particular, the average molecular weight is 1000 to 3000, and is a graft copolymer of polydimethylsiloxane, ethylene oxide and propylene oxide copolymer polyether, and the Si content is 30 to 50% by weight. Is preferably used with an ethylene oxide content of 70 to 100 mol%. Examples of commercially available silicone foam stabilizers for rigid urethane foam include SH-193, SF-2937 (manufactured by Toray Dow Corning Silicone), L-5340, SZ-1666, SZ-1668 (manufactured by Nihon Unicar). Is done.

  As the viscosity reducer, a viscosity reducer for rigid urethane foam can be used without limitation. Specific examples include tris (β-chloropropyl) phosphate (TMCPP, manufactured by Daihachi Chemical Co., Ltd.), tributoxyethyl phosphate (TBXP, manufactured by Daihachi Chemical Co., Ltd.), and preferably TMCPP.

Foam density by free foaming of rigid polyurethane foam of the present invention is preferably 75~95kg / ^{m 3,} more preferably from 80~90kg / ^{m 3.} Further, foam density by mold foam (1.5 times the foaming) is preferably 105~125kg / ^{m 3,} more preferably from 110~125kg / ^{m 3.} When the foam density is lower than the above range, the compressive strength is lowered. When the foam density is exceeded, the weight is increased, workability is lowered, and the thermal conductivity is deteriorated.

  As the heat insulation construction method for a low temperature tank of the present invention, for example, when a heat insulating material is provided on the outer peripheral surface of the low temperature tank, a gap between the outer peripheral surface of the low temperature tank and the heat insulating material and / or the heat insulating material. Examples of the method include injecting or applying the urethane composition obtained by hand stirring into the interstitial space, and foaming and curing the urethane composition. By this method, the space between the outer peripheral surface of the low temperature tank and the heat insulating material and / or the space between the heat insulating materials is filled with the hard urethane foam without any gap, and the heat insulating property of the low temperature tank can be ensured higher than before. .

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, the evaluation methods, such as a physical property in an Example etc., are as follows.

  Table 1 shows the raw material composition table, and Table 2 (free foaming) and Table 3 (in-mold foaming) show the physical property evaluation results of the rigid urethane foam.

<Raw materials>
Polyol compound A: sorbitol-based polyether polyol (hydroxyl value 550 mgKOH / g, functional group number 5)
・ Low molecular weight polyhydric alcohol: Dipropylene glycol (DPG), Glycerin ・ Foaming agent: Water ・ Foam stabilizer: SH-193 (made by Toray Dow Corning Silicone)
・ Thickener: TMCPP (Daihachi Chemical)
・ Catalyst: Polycat 8 (manufactured by Air Products)
・ Isocyanate compound: Crude MDI (manufactured by Sumitomo Bayer Urethane)

(Example 1)
<Preparation of urethane composition>
45 parts by weight of polyol compound A, 25 parts by weight of DPG, 30 parts by weight of glycerin, 1.7 parts by weight of water, 15 parts by weight of a viscosity reducing agent, 4 parts by weight of a foam stabilizer, and 0.35 parts by weight of an amine catalyst are placed in a polyester shaker. The mixture was mixed by hand stirring for 3 minutes to prepare a polyol composition. Next, the polyol composition and the polyisocyanate component were blended so that the NCO index was 1.1 and mixed by hand stirring for 1.5 minutes to obtain a urethane composition.

<Preparation of free foamed rigid urethane foam>
In the case of producing a free foamed rigid urethane foam, 500 g of the urethane composition is injected into a mold (mold size: height 10 cm × length 18 cm × width 18 cm), foamed and cured, Obtained.

<Production of in-mold foamed rigid urethane foam>
When producing in-mold foaming (1.5 times foaming) rigid urethane foam, mold (four circumferential surfaces: molded polyurethane foam, top surface: fireproof plate, bottom surface: aluminum plate, mold dimensions: height 10 cm x length 20 cm x width The urethane composition was injected at 530 g (including 50 g of loss) into 20 cm and an injection volume of 4000 cm ³ ), and the volume was set to 1.5 times when the urethane foam was free-foamed. After curing for 3 hours from the start of foaming, in-mold foamed rigid urethane foam was obtained.

  In addition, Example 2 obtained the rigid urethane foam by the same method as Example 1 except having increased the water which is a foaming agent with respect to the free foaming of Example 1. FIG. A rigid urethane foam was obtained in the same manner as in Example 1 except that the urethane composition was changed to 560 g (including a loss of 50 g) with respect to in-mold foaming in Example 1.

  In Example 3, a rigid urethane foam was obtained in the same manner as in Example 1 except that the blending amount was changed.

About comparative example 1, although mix | blended based on Table 1, the viscosity was high and could not be stirred and the rigid urethane foam could not be evaluated.

(Measurement and evaluation method)
<Foam density>
It measured based on JISK9511. Incidentally, the foam density by free foaming, Example 1 77~83kg / ^{m 3,} Example 2 is 83~89kg / ^{m 3,} Example 3 is 77~83kg / ^{m 3,} foam density by mold foam, Example 1 was adjusted to 110 to 120 kg / m ³ , Example 2 to 120 to 130 kg / m ³ , and Example 3 to 110 to 120 kg / m ³ .
<Compressive strength>
It measured based on JIS A 9511.
<Thermal conductivity>
A thermal conductivity measuring device AUTO-Λ HC-074 (manufactured by Eihiro Seiki Co., Ltd.) was used, and the thermal conductivity (W / m · K) was measured according to JIS A 9511 as the measurement conditions. The initial value is a measured value of the thermal conductivity at room temperature without pretreatment of the test piece, and the time-lapse value is a measured value of the test piece processed at 70 ° C. × 120 minutes.

<Table 1> Compounding raw materials

<Table 2> Evaluation results of physical properties in free foaming

<Table 3> Evaluation results of physical properties in in-mold foaming

<Evaluation results>
From the evaluation results shown in Tables 2 and 3, the examples using the rigid urethane foam shown in the present invention have a viscosity low enough to allow manual stirring using a shaker even when water is used as a foaming agent. It was possible to obtain a highly effective polyol composition for rigid urethane foam, and it was confirmed that the rigid urethane foam using the polyol composition was excellent in compressive strength, heat insulating properties and workability.

Claims (4)

In the polyol composition for rigid urethane foam containing a polyol component, a foaming agent, a foam stabilizer and a catalyst,
The blowing agent is water;
The polyol component includes a polyol compound and a low molecular weight polyhydric alcohol,
The polyol compound has a hydroxyl value of 450 to 650 mgKOH / g and an average functional group number of 4 to 6,
The low molecular weight polyhydric alcohol is a liquid alcohol having a functional group number of 4 or less,
The polyol composition for rigid urethane foam, wherein the ratio of the polyol compound and the low molecular weight polyhydric alcohol is polyol compound / low molecular weight polyhydric alcohol = 0/100 to 55/45 (weight ratio).   The polyol composition for rigid urethane foam according to claim 1, wherein the viscosity of the polyol composition for rigid urethane foam is 0.8 Pa · s (20 ° C) or less.   The manufacturing method of the rigid urethane foam which mixes the polyol composition for rigid urethane foams of Claim 1 or 2, and an isocyanate component, and makes it foam and harden | cure.   A polyol composition for rigid urethane foam according to claim 1 or 2, wherein a heat insulating material is provided on an outer peripheral surface of the low temperature tank, and a gap between the outer peripheral surface of the low temperature tank and the heat insulating material and / or a gap between the heat insulating materials. Insulation method for low-temperature tanks in which a urethane composition in which a product and an isocyanate component are stirred and mixed is injected, foamed and cured.