KR20100100951A - Process for production of hard polyurethane foam - Google Patents

Abstract

It is an object of the present invention to provide a method for producing a rigid polyurethane foam for after-heat insulation material foamed with cyclopentane, which is excellent in curing properties and capable of demolding in a short time, and is a polyisocyanate (a) and a polyol (b). In the method for producing a rigid polyurethane foam for a material heat insulating material which reacts and foams in the presence of a catalyst (c) and a blowing agent (d), the polyisocyanate (a) is a polymeric MDI (a1-1) and a branched alkyl group. The eggplant contains an isocyanate group-containing prepolymer (a1) and a foam stabilizer (a2) formed by reacting a low molecular polyol (a1-2), and the polyol (b) contains four kinds of polyether polyols (b1 to b4). The catalyst (c) contains a urethanization catalyst (c1) and a trimerization catalyst (c2), and the blowing agent (d) solves the above problems by using cyclopentane (d1) and water (d2) in combination.

Description

PROCESS FOR PRODUCTION OF HARD POLYURETHANE FOAM

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rigid polyurethane foam foamed with cyclopentane for thick materials which is excellent in curing properties and can be molded in a short time.

Since rigid polyurethane foam is excellent in heat insulation performance, dimensional stability, and workability, it is used extensively as a heat insulating material, such as a refrigerator, a freezer, a building material, and a spray use. Conventionally, trichlorofluoromethane (hereinafter referred to as "CFC-11") having low thermal conductivity and a preferable boiling point has been mainly used as a blowing agent of rigid polyurethane foam. However, chlorofluorocarbons (hereinafter referred to as "CFCs") contain chlorine atoms in the molecule and are very stable molecules, reaching the ozone layer by the diffusion effect, and reacting with ozone to destroy the earth's ozone layer. The substance has emerged, and by the end of 1995, the use of CFCs has been completely abolished. Currently, as a blowing agent for rigid polyurethane foams, hydrochlorofluorocarbons (hereinafter referred to as "HCFCs"), which are substitutes thereof, are used. Especially for those requiring heat insulation performance, HCFC- having low thermal conductivity among HCFCs is required. The use of 141b has become mainstream.

In general, rigid polyurethane foam for thermal insulation has an independent bubble structure in which a foaming agent is enclosed in a cell. Therefore, when a blowing agent having a boiling point above room temperature (above 25 ° C) is used, a decrease in the pressure in the cell due to liquefaction of the blowing agent enclosed in the cell occurs at room temperature or at a low temperature. This phenomenon is due to the vapor pressure inherent to the blowing agent, and as a result, the rigid polyurethane foam shrinks. That is, the most difficult problem in practical use of the foaming technique using the foaming agent having the boiling point above these room temperature (25 degreeC or more) is the avoidance of the shrinkage of rigid polyurethane foam below normal temperature, ie, maintaining good dimensional stability.

As a problem associated with a reduction in production cost and energy saving, a reduction in the density of rigid polyurethane foams is required. In order to meet this demand without compromising industrial utility value, it is essential to establish a manufacturing method of a rigid polyurethane foam which is less shrinkable at room temperature or less and can be reduced. In addition, while the demand for protection of the global environment / ozone layer is increasing, since HCFCs also contain chlorine molecules in their molecules, ODP is not zero (“0”) and has already been regulated since 2004. As an alternative compound of HCFCs, hydrocarbons represented by hydrofluorocarbons (hereinafter referred to as "HFCs") and cyclopentane (hereinafter referred to as "CP") (hereinafter referred to as "HC") are described. Foaming agents having an ODP of 0, etc., are being studied. However, among HFCs, 1,1,1,2-tetrafluoroethane (boiling point: -26.2 ° C), 1,1-difluoroethane (boiling point: -24.2 ° C), 1,1,1,2,2 Many compounds having a boiling point of 0 ° C. or lower, such as pentafluoroethane (boiling point: −48.5 ° C.) and the like, require industrial equipment to be treated such as high pressure gas to treat them as blowing agents.

When HCs are used as foaming agents, it is necessary to be compatible with explosion-proof equipment, but Resin Premix has an advantage of being relatively easy to handle as a liquid. In particular, CP is exemplified as a low thermal conductivity among HCs. In addition, HCs having 5 to 6 carbon atoms have a boiling point suitable for use as a blowing agent. As an example of using CP or HC as a component in the foaming agent, Patent Document 1 discloses, and by using ester polyol, in particular, thermal conductivity of less than or equal to that of CFC-11 reduced foaming technology is realized while maintaining good physical properties. As an example, Non Patent Literature 1 is known. However, the boiling point of CP is 49.3 ° C, and in order to meet the industrial demand for lowering density, the problem of shrinking below room temperature is inevitable.

In order to solve the problem as mentioned above, the technique regarding patent document 2 is proposed. However, in the technique of Patent Document 2, since the compatibility between the polyol mixture and cyclopentane is not good, it has been found that turbidity and two-layer separation are likely to occur, and further, it is difficult to obtain a uniform foam.

In addition, in a rigid polyurethane foam in a thick heat insulating material (thickness of 100 mm or more), breakage is often generated inside the foam due to lack of curing characteristics. In order to improve this point, there exist methods, such as lengthening molding time, but since such a method leads to the fall of productivity, the fundamental solution is calculated | required. In the present application, the term "thick material heat insulating material" shall refer to a heat insulating material having a thickness of 100 mm or more, and "thickness" shall mean a distance in the target heat insulating direction.

[Patent Document 1] Japanese Patent Application Publication No. Hei 2-91132 [Patent Document 2] Japanese Patent Application Publication No. Hei 10-1827756

 The Society of the Plastics Industry, Inc. Polyurethane Devision (1995) p. 292-295

An object of the present invention is to provide a method for producing a rigid polyurethane foam for a heat insulating material foamed with cyclopentane, which can be molded in a short time because of excellent compatibility with polyols and cyclopentane and curing properties.

That is, the present invention,

In the manufacturing method of the rigid polyurethane foam for after-heat insulation materials which makes polyisocyanate (A) and polyol (B) react and foam in presence of a catalyst (C) and a foaming agent (D),

The polyisocyanate (A) contains an isocyanate group-containing prepolymer (A1) and a foam stabilizer (A2) produced by reacting a polymeric MDI (A1-1) with a low molecular polyol (A1-2) having a side chain alkyl group,

The polyol (B) contains the following polyols (B1 to B4),

Catalyst (C) contains a urethanization catalyst (C1) and a trimerization catalyst (C2),

The foaming agent (D) provides cyclopentane (D1) and water (D2) together, The manufacturing method of the rigid polyurethane foam for thick insulation is provided.

Polyol (B1):

Polyether polyol obtained by addition of propylene oxide to an initiator having sucrose as a main component, and having an average number of functional groups = 3 to 6 and a hydroxyl value = 300 to 600 mgKOH / g

Polyol (B2):

Polyether polyol obtained by addition of propylene oxide to an initiator containing sorbitol as a main component and having an average number of functional groups = 3 to 6 and a hydroxyl group = 300 to 600 mgKOH / g

Polyol (B3):

Polyether polyol which is obtained by addition of propylene oxide to an initiator containing glycerin as a main component and has an average number of functional groups = 2 to 4 and a hydroxyl value = 1000 to 1500 mgKOH / g.

Polyol (B4):

Polyether polyol which is obtained by addition of propylene oxide to an initiator having ethylenediamine as a main component and has an average number of functional groups = 3 to 5 and a hydroxyl group = 400 to 800 mgKOH / g.

According to the present invention, it is possible to manufacture a rigid polyurethane foam for a thick heat insulating material foamed with cyclopentane for thick material, which is excellent in curing characteristics and can be molded in a short time.

The polyisocyanate (A) used in the present invention is an isocyanate group-containing prepolymer (A1) and a foam stabilizer (A2) produced by reacting a polymeric MDI (A1-1) with a low molecular polyol (A1-2) having a side chain alkyl group. ).

Polymeric MDI (A1-1) has a degree of condensation obtained by converting a condensation mixture (polyamine) obtained by a condensation reaction between aniline and formalin into an isocyanate group by phosgenation or the like, and isomerization as necessary. By mixing a mixture of different organic isocyanate compounds and changing the raw material composition ratio and reaction conditions during condensation, the composition of the finally obtained polymeric MDI can be changed. The polymeric MDI used in the present invention may be a reaction solution after conversion to an isocyanate group, or a mixture of different kinds of distillates obtained by removing a solvent from the reaction solution or distilling some MDI out, reaction conditions or separation conditions. In addition, a part of isocyanate groups may be modified by biuret, allophanate, carbodiimide, oxazolidone, amide, imide, or the like.

The average number of functional groups of the polymeric MDI (A1-1) is 2.3 or more, and the number of functional groups is preferably 2.3 to 3.1. Isocyanate content is 28-33 mass%, and 28.5-32.5 mass% is preferable. Moreover, as for viscosity (25 degreeC), 50-500 mPa * s is preferable and 100-300 mPa * s is especially preferable.

The polymeric MDI (A1-1) contains the component called diphenylmethane diisocyanate (MDI) which has two benzene rings and two isocyanate groups in 1 molecule, so-called binuclear bodies. Isomers constituting MDI include 2,2'-diphenylmethane diisocyanate (hereinafter abbreviated as 2,2'-MDI), 2,4'-diphenylmethane diisocyanate (hereinafter, 2,4'-MDI). And 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as 4,4'-MDI). Although the isomer constitution ratio of MDI is not specifically limited, It is preferable that 4,4'-MDI content is 70 mass% or more and 90-99.9 mass%, since the intensity | strength of the foam obtained is improved. The MDI content of the polymeric MDI and the isomer composition ratio of the MDI can be obtained from the calibration curve based on the area percentage of each peak obtained by GPC or gas chromatography (hereinafter, abbreviated as GC).

As for polymeric MDI (A1-1) used for this invention, the peak area ratio of the binuclear body (thing which has two benzene rings in 1 molecule) component in gel permeation chromatography (it abbreviates as GPC hereafter) is 20- It becomes 70%, and it is preferable to become 25 to 65%. When the peak area ratio of the binary nucleus exceeds 70%, the strength of the resulting rigid polyurethane foam is lowered and easily broken. On the other hand, when it is less than 20%, the viscosity of the polyisocyanate obtained becomes high and the filling property to a metal mold | die will fall easily.

In the present invention, polyisocyanates other than the polymeric MDI mentioned above can be used as needed. For example, isocyanurate modified substance of MDI, uretonimine modified substance, allophanate modified substance, etc. are mentioned. Moreover, 2, 4- tolylene diisocyanate, 2, 6- tolylene diisocyanate, xylene-1, 4- diisocyanate, xylene-1, 3- diisocyanate, tetramethyl xylene diisocyanate, m-phenylene diisocyanate, p- Aromatic diisocyanates such as phenylene diisocyanate, aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, 3-methyl-1,5-pentane diisocyanate and lysine diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate And alicyclic diisocyanate, such as hydrogenated xylene diisocyanate and hydrogenated diphenylmethane diisocyanate, etc. are mentioned. Moreover, these polymers, urethane, urea, allophanate, biuret, carbodiimide, uretonimide, uretdione, isocyanurate and the like are exemplified. 2 or more types of mixtures are mentioned.

The low molecular polyol (A1-2) used for this invention is a low molecular polyol which has a branched alkyl group. By urethane-modifying polymeric MDI (A1-1) with the low molecular polyol (A1-2) which has a side chain alkyl group, compatibility of an isocyanate group containing prepolymer (A1) and a foam stabilizer (A2) can be improved. As a result, it is not necessary to mix | blend the foam stabilizer (A2) which is incompatible with cyclopentane with a polyol liquid, and the stability of the polyol liquid which mix | blended cyclopentane improves, and a uniform foam can be obtained. . Moreover, it turned out that it contributes also to the improvement of hardening characteristic.

As a low molecular polyol (A1-2) which has such a side chain alkyl group, 1, 2- propanediol, 1, 3- butanediol, neopentyl glycol, 3-methyl- 1, 5- propanediol, dipropylene glycol, 2-methyl -1,3-propanediol, hydrogenated bisphenol A, 2,2-diethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 2,2-dimethylolheptane and the like For example. In the present invention, the smaller the molecular weight, the more efficiently the side chain alkyl group can be introduced into the prepolymer, so that 1,2-propanediol is most preferred.

The polyisocyanate (A) used for this invention reacts the above-mentioned polymeric MDI (A1-1) and the low molecular polyol (A1-2) which has a side chain alkyl group at 40-100 degreeC, and isocyanate group containing prepolymer (A1). It synthesize | combines and is obtained by adding the foam stabilizer (A2) mentioned later. As for the ratio of polymeric MDI (A1-1) and the low molecular polyol (A1-2) which has a branched alkyl group, NCO / OH = 50/1-1000/1 is preferable in molar ratio of an isocyanate group (NCO) and a hydroxyl group (OH). Do. When there is too little OH, the effect of hardening characteristic improvement cannot be desired. When there is too much OH, since the viscosity of the polyisocyanate obtained becomes high, the liquid feeding at the time of manufacture becomes difficult. 28-31 mass% is preferable, and, as for the isocyanate content of the polyisocyanate (A) obtained in this way, 29-30.5 mass% is especially preferable.

As a foam stabilizer (A2) used for this invention, a well-known silicone type surfactant is mentioned, For example, L-5340, L-5420, L-5421, L-5740, L-580, and SZ by Toray Dow Corning -1142, SZ-1642, SZ-1605, SZ-1649, SZ-1675, SH-190, SH-192, SH-193, SF-2945F, SF-2940F, SF-2936F, SF-2938F, SRX-294A , Shin-Etsu Chemical Co., Ltd. F-305, F-341, F-343, F-374, F-345, F-348, Gold Schmidt's B-8404, B-8407, B-8465, B-8444, B-8467, B-8433, B-8466, B-8870, and B-8450. As for the usage-amount of foam stabilizer (A2), the quantity used as 0.1-5 mass% with respect to a polyol (B) is suitable.

To the polyisocyanate (A) used in the present invention, various additives and preparations such as antioxidants, ultraviolet absorbers, flame retardants, plasticizers, pigments, dyes, antibacterial agents and antifungal agents can be added as necessary.

The polyol (B) used for this invention contains the following polyols (B1-B4).

Polyol (B1):

Polyether polyol obtained by addition of propylene oxide to an initiator having sucrose as a main component, and having an average number of functional groups = 3 to 6 and a hydroxyl value = 300 to 600 mgKOH / g

Polyol (B2):

Polyether polyol obtained by addition of propylene oxide to an initiator containing sorbitol as a main component and having an average number of functional groups = 3 to 6 and a hydroxyl group = 300 to 600 mgKOH / g

Polyol (B3):

Polyether polyol which is obtained by addition of propylene oxide to an initiator containing glycerin as a main component and has an average number of functional groups = 2 to 4 and a hydroxyl value = 1000 to 1500 mgKOH / g.

Polyol (B4):

Polyether polyol which is obtained by addition of propylene oxide to an initiator having ethylene diamine as a main component and has an average number of functional groups = 3 to 5 and a hydroxyl group = 400 to 800 mgKOH / g.

The most preferable mass compounding ratio of each polyol is (B1) :( B2) :( B3) :( B4) = 60: 20: 15: 5.

Catalyst (C) used in the present invention is characterized by containing a urethanization catalyst (C1) and a trimerization catalyst (C2). Examples of the urethanization catalyst (C1) include N-methylimidazole, trimethylaminoethylpiperazine, tripropylamine, tetramethylhexamethylenediamine, triethylenediamine, triethylamine, N-methylmorpholine, dimethylcyclohexylamine, And tin compounds such as dibutyltin diacetate and dibutyltin dilaurate, and metal complex compounds such as acetylacetone metal salts. Examples of the trimerization catalyst (C2) include triazines such as 2,4,6-tris (dimethylaminomethyl) phenol, 1,3,5-tris (dimethylaminopropyl) hexahydro-s-triazine, and 2,4- Amine compounds such as aziridine such as bis (dimethylaminomethyl) phenol, potassium 2-ethylhexanoate, sodium 2-ethylhexanoate, potassium acetate, sodium acetate, 2-ethylaziridine, and carboxylates of tertiary amines; And quaternary ammonium compounds, diazabicycloundecene, lead naphthenate, lead octylate and the like, alcoholate compounds such as sodium methoxide, and phenolate compounds such as potassium phenoxide. These (C1) and (C2) can be used 1 type or in combination or 2 or more types. As for the usage-amount of all the catalysts (C), the quantity used as 0.01-15 mass% with respect to a polyol is suitable.

Moreover, as a promoter for reaction promotion, carbonate compounds, such as ethylene carbonate and a propylene carbonate, can be used, for example.

The blowing agent (D) is cyclopentane and water. When the blowing agent is only cyclopentane, the foam obtained is likely to shrink. The usage-amount of a blowing agent is 0.1-30 mass% of cyclopentane, and 0.1-3 mass% of water with respect to a polyol.

In the present invention, additives other than those mentioned above can be used. As this additive, a plasticizer, a filler, a coloring agent, a flame retardant, an organic or inorganic filler, antioxidant, a ultraviolet absorber, a plasticizer, a pigment, a dye, an antibacterial agent, an antifungal agent, etc. are mentioned. In this invention, it is preferable to use a flame retardant. Examples of the flame retardant include phosphate compounds such as phosphate esters such as triethyl phosphate and tris (β-chloropropyl) phosphate, and phosphite esters such as ethyl phosphite and diethyl phosphite.

The specific procedure of the manufacturing method of the rigid polyurethane foam of this invention uses the polyisocyanate (A) containing the above-mentioned isocyanate group terminal prepolymer, and the above-mentioned polyol (B), a catalyst (C), a foaming agent (D), and a foaming agent. In the presence of (E) and other additives, it is a method of mixing, foaming and curing using an apparatus described later.

The rigid polyurethane foam obtained by this invention has a chemical bond like a urethane bond and a urea bond. Moreover, depending on manufacturing conditions, an isocyanurate group can be produced | generated at the time of foaming. An isocyanurate group is produced by trimerizing an isocyanate group with a catalyst, and can improve mechanical strength, heat resistance, etc.

The isocyanate index at this time (all isocyanate groups / all active hydrogen groups x100) is 50-800, and 80-300 are preferable.

In manufacturing a rigid polyurethane foam, any device can be used as long as it can mix each raw material liquid uniformly. For example, small mixers or low pressure or high pressure foamers for injection foam, slab foam low or high pressure foamers for use in the production of general urethane foam, low pressure or high pressure foamers for continuous lines, spray construction Spray foaming machine can be used.

The rigid polyurethane foam obtained by the present invention is optimal as a material insulation material, but in addition, boards, panels, refrigerators, sunshades, doors, shutters, chassis, concrete houses, bathtubs, low temperature tank equipment, refrigerated warehouses, pipe covers, and plywood It is applicable to various heat insulating material applications, such as spraying to a dew condensation prevention, slab, etc.

[Example]

Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these. And in an Example and a comparative example, "%" represents the "mass%."

[Synthesis of Polyisocyanate for Rigid Polyurethane Foam]

Synthesis Example 1

983 kg of P-MDI (1) was thrown into the reactor provided with the stirrer, the cooling tube, the nitrogen introduction tube, and the thermometer, and it heated at 40 degreeC, stirring. Subsequently, 5 kg of 1,2-PD was added and reacted at 80 ° C. for 4 hours while stirring. Then, 1.83 kg of L-6900 and 7.31 kg of B-8466 were added thereto, followed by uniformly mixing to form a polyurethane foam. Isocyanate NCO-1 was obtained. The NCO content of NCO-1 was 30.1%. In appearance of NCO-1, no turbidity or precipitation was observed.

Synthesis Example 2

983 kg of MR-200 was thrown into the reactor provided with the stirrer, the cooling tube, the nitrogen introduction tube, and the thermometer, and it heated at 40 degreeC, stirring. Next, 5 kg of 1,2-PD was added and reacted at 80 ° C for 4 hours with stirring to obtain polyisocyanate NCO-2 for hard polyurethane foam. The NCO content of NCO-2 was 30.2%. In appearance of NCO-2, no turbidity or precipitation was observed.

Synthesis Example 3

983 kg of MR-200 was thrown into the reactor provided with the stirrer, the cooling tube, the nitrogen introduction tube, and the thermometer, and it heated at 40 degreeC, stirring. Subsequently, 1.83 kg of L-6900 and 7.31 kg of B-8466 were added and mixed uniformly to obtain polyisocyanate NCO-3 for hard polyurethane foam. The NCO content of NCO-3 was 30.0%. In appearance of NCO-3, it was confirmed that it was turbid.

In Synthesis Examples 1 to 3,

MR-200: polymeric MDI from Nippon Polyurethane Industries

        Brand name, Millionate (registered trademark) MR-200

Isocyanate Content = 31.1%

MDI content = 40%

Isomer content other than 4,4'-MDI in MDI = 0.1%

         Viscosity at 25 ° C = 130 mPas

1,2-PD: 1,2-propanediol

L-6900: Silicone Foaming Agent from Dow Corning

B-8466: silicone foam stabilizer from Gold Schmidt

[Formulation of Polyol Premix]

It mixed at the mass mix ratio shown below, and obtained polyol premix OH-1,2.

OH-1

 Polyol-1: 60 kg

 Polyol-2: 20 kg

 Polyol-3: 5 kg

 Polyol-4: 15 kg

CAT-11: 1.5 kg

CAT-12: 0.15kg

CAT-21: 0.3 kg

 Water: 1.9kg

 Cyclopentane: 16.1kg

OH-2

 Polyol-1: 60 kg

 Polyol-2: 20 kg

 Polyol-3: 5 kg

 Polyol-4: 15 kg

CAT-11: 1.5 kg

CAT-12: 0.15kg

CAT-21: 0.3 kg

 Water: 1.9kg

 Cyclopentane: 16.1kg

 L-6900: 0.3kg

 B-8466: 1.2 kg

In the combination example,

Polyol-1:

 Polyether polyol obtained by addition of propylene oxide to an initiator having sucrose as a main component, average number of functional groups = 4.4, hydroxyl value = 400 mgKOH / g

Polyol-2:

 Polyether polyol obtained by addition of propylene oxide to an initiator based on sorbitol, average number of functional groups = 5.0, hydroxyl value = 460 mgKOH / g

Polyol-3:

 Polyether polyol obtained by addition of propylene oxide to an initiator containing glycerin as a main component, average number of functional groups = 3.0, hydroxyl value = 1120 mgKOH / g

Polyol-4:

Polyether polyol obtained by addition of propylene oxide to an initiator containing ethylenediamine as a main component, average number of functional groups = 4.0, hydroxyl value = 640 mgKOH / g

CAT-11:

 N, N-dimethylcyclohexylamine

CAT-12:

 Pentamethyldiethylenetriamine

CAT-21:

 Tris (dimethylaminopropyl) hexahydro-S-triazine

L-6900:

 Doore Corning Products Silicone Foaming Agent

B-8466:

Gold Schmidt Silicone Foaming Agent

Appearance defects such as cloudiness of OH-1 were not confirmed, but cloudiness of OH-2 was confirmed.

[Manufacture and Evaluation of Rigid Polyurethane Foam for Thick Insulation]

Example 1, comparative example 1, comparative example 2

 Isocyanate is 45 ° C ± 1 ° C by the combination of NCO-1 and OH-1 (Example 1), NCO-2 and OH-2 (Comparative Example 1), and NCO-3 and OH-1 (Comparative Example 2) After adjusting a polyol at 20 degreeC +/- 1 degreeC, it mix | blends with an isocyanate index 120 in a 2.0-liter polyethylene beaker, stirring-mixing for several seconds with a stirring mixer at a rotation speed of 5000rpm, and heat-preserved at 45 degreeC 500x In a mold made of aluminum of 500 × 100 mm, in Example 1, the curing time was 3 minutes, and in the Comparative Examples 1 and 2, the curing time was 3 minutes, 4 minutes, and 5 minutes to mold foam, and the obtained foam was obtained. The curing characteristics were confirmed. The packing rate was 130%. The results are shown in Table 1.

Comparative Example 3

After adjusting the isocyanate at 45 ° C ± 1 ° C and the polyol at 20 ° C ± 1 ° C by the combination of milionate MR-200 (described above) and OH-2, the isocyanate index 120 was added to a 2.0-liter polyethylene beaker. The resulting foam was obtained by mixing and stirring at a rotational speed of 5000 rpm for several seconds with a stirring mixer, and in a mold of 500 × 500 × 100 mm aluminum previously heated at 45 ° C. with a curing time of 6 minutes. The curing characteristics were confirmed. The packing rate was 130%.

TABLE 1

The hardening characteristic cut | disconnected the center part of the foam taken out from the mold, and evaluated that the "cracking" of the cross section of the foam was not confirmed, and that "cracking" was confirmed as rejection.

In hardening characteristic, even if it made the prescription of Example 1 into hardening time 3 minutes, "cracking" of a foam cross section is not recognized, and shows favorable hardening characteristic. In addition, the thermal conductivity was also good.

In the prescription of the comparative example 1, since the "cracking" was confirmed by the cross section of a foam in 3 minutes of hardening time, hardening characteristic is disqualified, and when the hardening time is made into 4 minutes, fine "cracking" was confirmed by a foam cross section, The hardening characteristic was disqualified, and hardening characteristic was only passed in 5 minutes of hardening time. In the prescription of this comparative example, productivity can be considered very low compared with the prescription of an Example.

In the prescription of the comparative example 2, since the unmodified polymeric MDI and the foam stabilizer were mixed previously, since foam is not uniformly disperse | distributed in a foam, thermal conductivity is not good. In addition, the curing characteristics were also insufficient compared with the examples.

In the comparative example 3, although the hardening time was considerably lengthened by 6 minutes, since the "cracking" was confirmed by the foam cross section, hardening characteristic was disqualified. In addition, since the compatibility between the polyol premix and the cyclopentane was insufficient, since the foam was not uniformly dispersed in the foam, the thermal conductivity was not good. In this prescription, it can be said that productivity is very low compared with the comparative example 1 mentioned above.

Claims (1)

In the manufacturing method of the rigid polyurethane foam for thick insulation materials which makes polyisocyanate (A) and polyol (B) react and foam in presence of a catalyst (C) and a foaming agent (D),
The polyisocyanate (A) contains an isocyanate group-containing prepolymer (A1) and a foam stabilizer (A2) produced by reacting a polymeric MDI (A1-1) with a low molecular polyol (A1-2) having a side chain alkyl group,
The polyol (B) contains the following polyols (B1 to B4),
Catalyst (C) contains a urethanization catalyst (C1) and a trimerization catalyst (C2),
Process for producing rigid polyurethane foam for thick insulation material, in which the blowing agent (D) uses cyclopentane (D1) and water (D2) together:
Polyol (B1):
Polyether polyol obtained by addition of propylene oxide to an initiator having sucrose as a main component and having an average number of functional groups = 3 to 6 and a hydroxyl group = 300 to 600 mgKOH / g
Polyol (B2):
Polyether polyol obtained by addition of propylene oxide to an initiator containing sorbitol as a main component and having an average number of functional groups = 3 to 6 and a hydroxyl group = 300 to 600 mgKOH / g
Polyol (B3):
Polyether polyol obtained by addition of propylene oxide to an initiator having glycerin as a main component, and having an average number of functional groups = 2 to 4 and a hydroxyl value = 10001500 mgKOH / g
Polyol (B4):
Polyether polyol obtained by addition of propylene oxide to the initiator which has ethylene diamine as a main component, and whose average number of functional groups is 3-5, and hydroxyl value is 400-800 mgKOH / g.