JP2009084411A - Method for producing rigid polyurethane foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing rigid cyclopentane-foamed polyurethane foam, which is friendly to the global environment and has good thermal conductivity and mechanical properties. <P>SOLUTION: In the method for producing rigid polyurethane foam, polyisocyanate A and polyol B react with each other in the presence of a catalyst C, a foaming agent D, and a foam stabilizer E, and the polyol B includes the following polyols B1-B3, while the foaming agent D uses cyclopentane D1 and water D2 together (wherein B1 is a sucrose-based PPG with a hydroxy group value of 250-500 mgKOH/g; B2 is a sorbitol-based PPG with a hydroxy group value of 400-500 mgKOH/g; and B3 is an ehylenediamine-based PPG with a hydroxy group value of 600-700 mgKOH/g). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a rigid polyurethane foam. More particularly, the present invention relates to a method for producing a rigid polyurethane foam that can obtain a rigid polyurethane foam that is excellent in productivity and is compatible with a foaming system using cyclopentane and water that is friendly to the global environment and that has good heat conduction characteristics.

Rigid polyurethane foam is useful as a heat insulating material, and has excellent moldability and processability. From heat insulation of electric refrigerators to insulation of buildings, low-temperature warehouses, storage tanks, freezing ship piping, etc. Used in a wide range of fields. Its thermal conductivity has been improved year by year, and at present, it has reached 0.0215 W / mK (see Non-Patent Document 1) at the product level, and it is said that it has the highest thermal insulation performance as a heat insulating material used near room temperature. It has been broken. However, against the background of the recent increase in energy saving, there is an increasing demand for further lowering the thermal conductivity of the heat insulating material.
Uwa Thermal Engineering Co., Ltd. website, product information, cyclopentane February 1, 2006 Search URL: http://www.uwa-ud.co.jp/cyclopentane.htm

  Conventionally, in order to produce such a rigid polyurethane foam, a foaming process is performed by mixing and reacting a component A mainly composed of a polyol, a catalyst, a foaming agent and a foam stabilizer and a component B mainly composed of an organic isocyanate. A one-shot method is generally used in which a foam is formed by proceeding in parallel with a curing process. In the production of such rigid polyurethane foam, trichloromonofluoromethane (hereinafter abbreviated as R-11) has been mainly used as a foaming agent in the past, but conventional fluorocarbons represented by R-11 have been used. Is known to be chemically stable, diffuses to the stratosphere and destroys the ozone layer, and has recently been banned as a major cause of the destruction of the global environment.

  In recent years, therefore, diligent research has been conducted on a blowing agent that replaces such a fluorocarbon, for example, 1,1-dichloro-1-fluoroethane (hereinafter referred to as HCFC-), which is a hydrochlorofluorocarbon (hereinafter abbreviated as HCFC). 141b) and methylene chloride are listed as candidates for R-11.

  The aforementioned HCFC, etc. still contains chlorine atoms in the molecule, so it has less impact on the ozone layer than R-11, but it still has the property of destroying the ozone layer, so production and use are still discontinued. Has been determined. Therefore, from the viewpoint of protecting the global environment, the use of a foaming agent that does not affect the destruction of the ozone layer has been newly proposed. In some applications, hydrocarbons that do not contain any chlorine atoms and do not risk the destruction of the ozone layer. For example, cyclopentane is introduced and applied (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 3-152160

  However, cyclopentane is optimal as a foaming agent that is friendly to the global environment, but there has been found a method for producing a rigid polyurethane foam that can satisfy all of productivity, mechanical properties of the foam, thermal conductivity, etc. It wasn't.

  An object of the present invention is to provide a process for producing a cyclopentane foamed rigid polyurethane foam which is friendly to the global environment and has good heat conduction characteristics and mechanical properties.

  That is, this invention is shown by the following (1)-(3).

(1) In the process for producing a rigid polyurethane foam in which polyisocyanate (A) and polyol (B) are reacted and foamed in the presence of a catalyst (C), a foaming agent (D), and a foam stabilizer (E).
The polyol (B) contains the following polyols (B1) to (B3),
The blowing agent (D) uses cyclopentane (D1) and water (D2) in combination;
A process for producing a rigid polyurethane foam characterized by
Polyol (B1):
A polyether polyol having a hydroxyl value of 250 to 500 mgKOH / g and obtained by addition of propylene oxide using sucrose as a main initiator.
Polyol (B2):
A polyether polyol having a hydroxyl value of 400 to 500 mgKOH / g and obtained by addition of propylene oxide using sorbitol as a main initiator.
Polyol (B3):
A polyether polyol having a hydroxyl value of 600 to 700 mgKOH / g and obtained by addition of propylene oxide using ethylenediamine as a main initiator.

(2) The mass blending ratio of (B1) to (B3) is (B1) :( B2) :( B3) = 55-75: 15-25: 10-20, (1 ) Of rigid polyurethane foam.

(3) The rigid polyurethane according to (1) or (2) above, wherein the mass blending ratio of (D1) and (D2) is (D1) / (D2) = 85/15 to 95/5 Form manufacturing method.

  According to the present invention, there is provided a method for producing a rigid polyurethane foam capable of obtaining a rigid polyurethane foam excellent in productivity and suitable for a foaming system using cyclopentane and water that is friendly to the global environment and having good heat conduction characteristics. It has become possible.

  The present invention relates to a method for producing a rigid polyurethane foam in which a polyisocyanate (A) and a polyol (B) are reacted and foamed in the presence of a catalyst (C) and a foaming agent (D). It is a method for producing a rigid polyurethane foam, which contains the polyols (B1) to (B4) to be used, and the foaming agent (D) uses cyclopentane (D1) and water (D2) in combination.

  The polyisocyanate (A) used in the present invention is not particularly limited, but polymer MDI is preferable in consideration of mechanical properties of the obtained rigid polyurethane foam, productivity of the rigid polyurethane foam, and the like.

  This polymeric MDI is an organic isocyanate compound having a different degree of condensation obtained by converting a condensation mixture (polyamine) obtained by condensation / isomerization reaction of aniline and formalin into an isocyanate group by phosgenation or the like. It means a mixture, and the composition of the finally obtained polymeric MDI can be changed by changing the raw material composition ratio and reaction conditions during condensation. The polymeric MDI used in the present invention has different numbers of reaction liquids after conversion to isocyanate groups, or removal of the solvent from the reaction liquids, or bottoms obtained by distilling and separating part of the MDI, reaction conditions and separation conditions, etc. It may be a mixture of seeds.

  The average number of functional groups of polymeric MDI is 2.3 or more, and preferably the number of functional groups is 2.3 to 3.1. The isocyanate content is 28 to 33% by mass, preferably 28.5 to 32.5% by mass. The viscosity (25 ° C.) is preferably 50 to 500 mPa · s, particularly preferably 100 to 300 mPa · s.

  Polymeric MDI contains diphenylmethane diisocyanate (MDI) having two benzene rings and two isocyanate groups in one molecule, a so-called dinuclear component. The isomers constituting MDI are 2,2'-diphenylmethane diisocyanate (hereinafter abbreviated as 2,2'-MDI), 2,4'-diphenylmethane diisocyanate (hereinafter abbreviated as 2,4'-MDI), There are three types of 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as 4,4'-MDI). The isomer composition ratio of MDI is not particularly limited, but the 4,4′-MDI content is preferably 70% by mass or more, preferably 90 to 99.9% by mass because the strength of the resulting foam is improved. . The MDI content of polymeric MDI and the isomer composition ratio of MDI can be determined from a calibration curve based on the area percentage of each peak obtained by GPC or gas chromatography (hereinafter abbreviated as GC).

  The polymeric MDI used in the present invention has a peak area ratio of 20 to 70% of a dinuclear (having two benzene rings in one molecule) component in gel permeation chromatography (hereinafter abbreviated as GPC). And preferably 25-65%. When the peak area ratio of the binuclear body exceeds 70%, the strength of the rigid polyurethane foam obtained is lowered and the brittle body tends to become brittle. On the other hand, when it is less than 20%, the viscosity of the resulting polyisocyanate increases, and the filling property into the mold tends to decrease.

  In the present invention, if necessary, a polyisocyanate other than the above-mentioned polymeric MDI can be used. Examples include MDI isocyanurate-modified products, uretonimine-modified products, allophanate-modified products, and the like. In addition, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, tetramethylxylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, etc. Aromatic diisocyanates, tetramethylene diisocyanates, hexamethylene diisocyanates, 3-methyl-1,5-pentane diisocyanates, lysine diisocyanates and other aliphatic diisocyanates, isophorone diisocyanates, hydrogenated tolylene diisocyanates, hydrogenated xylene diisocyanates, hydrogenated diphenylmethane diisocyanates, etc. And alicyclic diisocyanates. In addition, these polymeric materials, urethanized products, ureaated products, allophanated products, biuretized products, carbodiimidized products, uretoniminate products, uretdioneized products, isocyanurated products, and the like, and a mixture of two or more of these may be mentioned.

The polyol (B) used in the present invention contains the following polyols (B1) to (B4).
Polyol (B1):
A polyether polyol having a hydroxyl value of 250 to 500 mgKOH / g and obtained by addition of propylene oxide using sucrose as a main initiator.
Polyol (B2):
A polyether polyol having a hydroxyl value of 400 to 500 mgKOH / g and obtained by addition of propylene oxide using sorbitol as a main initiator.
Polyol (B3):
A polyether polyol having a hydroxyl value of 600 to 700 mgKOH / g and obtained by addition of propylene oxide using ethylenediamine as a main initiator.

  When there is no polyol (B1), the curing property in the production of rigid polyurethane foam and the adhesiveness of polyurethane foam are lowered.

  When there is no polyol (B2), the increase in the thermal conductivity and the compressive strength of the resulting rigid polyurethane foam are lowered, and the curing property in producing the rigid polyurethane foam is also lowered.

  When there is no polyol (B3), the thermal conductivity of the resulting rigid polyurethane foam is increased, and the compatibility between the polyol premix and cyclopentane (D1) tends to deteriorate.

  In the present invention, a preferable mass blending ratio of (B1) to (B3) is (B1) :( B2) :( B3) = 55 to 75:15 to 25: 10-20.

  As the catalyst (C), a known catalyst usually used for urethane foaming can be used. For example, as a urethanization catalyst, N-methylimidazole, trimethylaminoethylpiperazine, tripropylamine, tetramethylhexamethylenediamine, triethylenediamine, triethylamine, N-methylmorpholine, dimethylcyclohexylamine, dibutyltin diacetate, dibutyltin dilaurate, etc. And metal complex compounds such as acetylacetone metal salts. Trimerization catalysts include 2,4,6-tris (dimethylaminomethyl) phenol, triazines such as 1,3,5-tris (dimethylaminopropyl) hexahydro-s-triazine, 2,4-bis (dimethylamino) Methyl) phenol, amine compounds such as potassium 2-ethylhexanoate, sodium 2-ethylhexanoate, potassium acetate, sodium acetate, 2-ethylaziridine and the like, and quaternary compounds such as tertiary amine carboxylates Examples include ammonium compounds, lead compounds such as diazabicycloundecene, lead naphthenate and lead octylate, alcoholate compounds such as sodium methoxide, phenolate compounds such as potassium phenoxide, and the like. These catalysts can be used alone or in combination of two or more. The amount of the catalyst used is appropriately 0.01 to 15% by mass based on the polyol.

  Furthermore, for example, carbonate compounds such as ethylene carbonate and propylene carbonate can be used as a cocatalyst for promoting the reaction.

  The blowing agent (D) used in the present invention is characterized by using cyclopentane (D1) and water (D2) in combination. The reason why water (D2) is used in combination is that it contributes to the mechanical strength of the rigid polyurethane foam from which the urea group produced during the reaction is obtained.

  A preferable mass blending ratio of (D1) and (D2) is (D1) / (D2) = 85/15 to 95/5. When there is too little (D2), the mechanical strength of the rigid polyurethane foam obtained tends to fall. Moreover, when there are too many (D2), it exists in the tendency for the rigid polyurethane foam obtained to become weak, and adhesiveness also falls easily.

  The preferable amount of (D1) is 10 to 20 parts, particularly preferably 13 to 18 parts, relative to 100 parts of polyol (B). Moreover, the preferable amount of (D2) is 1-2 parts with respect to 100 parts of polyol (B), and particularly preferably 1.5-1.8 parts.

  Examples of the foam stabilizer (E) used in the present invention include known silicone surfactants, such as L-5340, L-5420, L-5421, L-5740, L-made by Toray Dow Corning. 580, L-6900, SZ-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 F-305, F-341, F-343, F-374, F-345, F-348, Goldschmitt B-8404, B-8407, B -8423, B-8465, B-8444, B-8467, B-8433, B-8466, B-8870, B-8450 and the like.The amount of (E) used is suitably 0.1 to 5% by weight based on the polyol.

  In the present invention, other additives can be used. Examples of the additives include plasticizers, fillers, colorants, flame retardants, organic or inorganic fillers, antioxidants, ultraviolet absorbers, plasticizers, pigments / dyes, antibacterial agents / antifungal agents, and the like. . In the present invention, it is preferable to use a flame retardant. Examples of the flame retardant include phosphate esters such as triethyl phosphate and tris (β-chloropropyl) phosphate, and phosphate compounds such as phosphite esters such as ethyl phosphite and diethyl phosphite.

  The ratio of isocyanate groups and active hydrogen groups during the reaction is particularly preferably NCO / H (active hydrogen) = 0.7 to 5.0 (equivalent ratio). In order to carry out the present invention, a polyol pre-mix is prepared by mixing predetermined amounts of polyol (B) other than polyisocyanate (A), catalyst (C), foaming agent (D), and foam stabilizer (E). The premix and the polyisocyanate are mixed at a high speed at a constant ratio and injected into the gap or mold. At this time, the liquid ratio of the polyisocyanate and the polyol premix is adjusted so that the equivalent ratio (NCO: H) of the organic polyisocyanate and the active hydrogen of the resin liquid is 0.7: 1 to 5: 1.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these. In Examples and Comparative Examples, “%” indicates “mass%”.

Preparation examples 1-4 of polyol premix
Polyol premixes OH-1 to -4 were prepared with the formulation shown in Table 1.

In Table 1, polyol-1:
Polyether polyol nominal hydroxyl value = 390 mgKOH / g based on polyether polyol obtained by addition of propylene oxide with sucrose as the main initiator
Polyol-2:
Polyether polyol nominal hydroxyl value = 460 mgKOH / g based on polyether polyol obtained by addition of propylene oxide with sorbitol as the main initiator
Polyol-3:
Polyether polyol nominal hydroxyl value = 640 mgKOH / g with ethylenediamine as the main initiator
CAT-1:
Amine-based catalyst, trade name "POLYCAT-8 (manufactured by San Apro)"
CAT-2:
Amine-based catalyst, trade name “TOYOCAT-F40 (manufactured by Tosoh)”
CAT-3:
Amine-based catalyst, trade name “TOYOCAT-ET (manufactured by Tosoh)”
SUR-1:
Silicone foam stabilizer, trade name "B-8423 (Gold Schmidt)"
SUR-2:
Silicone foam stabilizer, trade name "L-6900 (manufactured by Dow Corning Toray)"
BLO-1:
Cyclopentane BLO-2:
Water storage stability: Store the polyol premix at 25 ° C for 1 month, and evaluate the appearance of the liquid. ○ (excellent) → × →

  From Table 1, the polyol premixes OH-1 to 3 had good compatibility with cyclopentane. OH-4 which did not use polyol-3 had poor storage stability.

Production and Evaluation of Rigid Polyurethane Foam Example 1, Comparative Examples 1-4
A rigid polyurethane foam was produced using MR-200 (described later) as a polyisocyanate. The isocyanate index was blended at 115, the polyol was adjusted to 20 ° C. ± 1 ° C., and the isocyanate was adjusted to 20 ° C. ± 1 ° C., then weighed into a 2.0 liter polyethylene beaker and 2-5 with a stirring mixer at a rotational speed of 5000 rpm. The mixture was stirred and mixed for 2 seconds, mold foaming was performed while a polyethylene bag was set inside an aluminum container that had been kept at 45 ° C., and each performance of the obtained foam was measured. The results are shown in Table 2.

In Example 1, Comparative Examples 1 to 4 and Table 2, MR-200: Millionate MR-200 (trade name)
Polymeric MDI
Made by Nippon Polyurethane Industry
Isocyanate content = 31.1%
* Millionate is a registered trademark

Evaluation methods for rigid polyurethane foam measurement items are as follows.
Thermal conductivity Measured by JIS A1412, flat plate heat flow meter method Measuring device: HC-074-200 (Auto Λ) manufactured by Eihiro Seiki Hot plate / cold plate = 37.7 ° C / 10.0 ° C The isocyanate / polyol mixture is poured into a horizontal mold of 80 mm × 100 mm × 70 mm heated at a pack rate of 180%, and the foam is taken out from the mold after 4 minutes.
Surface property An iron plate is set on the lower surface of the mold in advance, and an isocyanate / polyol mixed solution is poured into a horizontal mold of 80 mm × 100 mm × 70 mm heated to 45 ° C. at a packing rate of 180%, and the foam is taken out from the mold after 5 minutes. Thereafter, the surface of the surface on which the iron plate was not attached was visually evaluated for the unevenness of the surface.
Adhesiveness A polyethylene sheet is set on the inner surface of the mold in advance, and an isocyanate / polyol mixture is poured into a 250 mm × 250 mm × 50 mm vertical mold heated to 45 ° C. at a pack rate of 120%. Take out. Thereafter, the adhesion between the foam and the face material was evaluated.
About evaluation ○ (excellent) → × → × × (defect)

From Table 2, the examples showed good results, but the foam using OH-2 without polyol-1 (Comparative Example 1) had poor surface properties and adhesion, and OH-3 without polyol-2. The foam using Comparative Example 2 (Comparative Example 2) had poor cure properties. Further, the foam using OH-4 without Polyol-3 (Comparative Example 3) had sufficient foam performance, but the storage stability of the polyol was poor.

Claims (3)

In the method for producing a rigid polyurethane foam in which polyisocyanate (A) and polyol (B) are reacted and foamed in the presence of a catalyst (C), a foaming agent (D), and a foam stabilizer (E),
The polyol (B) contains the following polyols (B1) to (B3),
The blowing agent (D) uses cyclopentane (D1) and water (D2) in combination;
A process for producing a rigid polyurethane foam characterized by
Polyol (B1):
A polyether polyol having a hydroxyl value of 250 to 500 mgKOH / g and obtained by addition of propylene oxide using sucrose as a main initiator.
Polyol (B2):
A polyether polyol having a hydroxyl value of 400 to 500 mgKOH / g and obtained by addition of propylene oxide using sorbitol as a main initiator.
Polyol (B3):
A polyether polyol having a hydroxyl value of 600 to 700 mgKOH / g and obtained by addition of propylene oxide using ethylenediamine as a main initiator.   The hard blend according to claim 1, wherein a mass blending ratio of (B1) to (B3) is (B1) :( B2) :( B3) = 55 to 75:15 to 25:10 to 20. A method for producing polyurethane foam. The mass blending ratio of (D1) and (D2) is (D1) / (D2) = 85/15 to 95/5, The manufacturing method of the rigid polyurethane foam of Claim 1 or 2 characterized by the above-mentioned.