JP2012153844A - Method for producing rigid polyurethane foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rigid polyurethane foam which has more excellent heat-insulating performance and more excellent dimensional stability and combustion resistance than a rigid polyurethane foam prepared by using an HCFC as a blowing agent.SOLUTION: This invention is characterized in that in producing a rigid polyurethane foam by reacting a polyisocyanate with a polyol in the presence of a blowing agent, a catalyst, etc., the polyol uses 10-100 pts.wt. per 100 pts.wt. entire polyol, of polyether polyol prepared by using aniline as an initiator and having a hydroxyl value of 550-630 mgKOH/g.

Description

  The present invention relates to a method for producing a rigid polyurethane foam having excellent heat insulation performance, dimensional stability, and flammability.

  Rigid polyurethane foam is excellent in heat insulation, moldability, self-adhesiveness, etc., and is used as various heat insulating materials for buildings such as houses and refrigerator-freezer warehouses, and vending machines and refrigerators. The rigid polyurethane foam is obtained by reacting a polyol and a polyisocyanate in the presence of a catalyst, a foam stabilizer, and a foaming agent. Hydrochlorofluorocarbon (HCFC) has been used as a foaming agent for producing rigid polyurethane foam, but HCFC is currently prohibited from being used because it causes environmental problems that destroy the ozone layer.

  In recent years, hydrofluorocarbons (HFC), hydrocarbons such as pentane (HC), water, and the like have been used as foaming agents for producing rigid polyurethane foams in place of the above HCFCs. A method for producing a rigid polyurethane foam using an agent has been proposed.

  However, the foaming agent replacing HCFC has a problem of poor heat insulation performance. Therefore, in order to solve such a problem, a method described in Patent Document 1 has been proposed. Specifically, ethylene oxide and propylene oxide are addition-polymerized to an aromatic monoamine compound, and a predetermined amount of polyol having a hydroxyl value of 250 to 550 mgKOH / g is used.

JP 2004-225044

  However, in the rigid polyurethane foam obtained using a foaming agent such as water, HFC, HC, etc., the thermal insulation performance is superior to the rigid polyurethane foam obtained using HCFC, that is, the thermal insulation performance is an initial value of thermal conductivity: A rigid polyurethane foam having a value of 0.020 W / mK or less and a time-lapse value of 0.022 W / mK or less was not obtained.

  Therefore, an object of the present invention is to provide a rigid polyurethane foam that is superior in heat insulation performance as compared with a rigid polyurethane foam using HCFC as a foaming agent, and also excellent in dimensional stability and flammability.

  In the present invention, when a rigid polyurethane foam is produced by reacting a polyisocyanate and a polyol in the presence of a blowing agent and a catalyst, the polyol is a polyether having an aniline as an initiator and a hydroxyl value of 550 to 630 mgKOH / g. It has been found that by using 10 to 100 parts by weight of the polyol with respect to 100 parts by weight of the total polyol, a rigid polyurethane foam having excellent heat insulation and excellent dimensional stability and flammability can be obtained.

  The rigid polyurethane foam of the present invention can provide a rigid polyurethane foam having excellent heat insulation performance and excellent dimensional stability and flammability without using an HCFC that destroys the ozone layer as a foaming agent.

  According to the method for producing a rigid polyurethane foam of the present invention, when a rigid polyurethane foam is produced by reacting a polyisocyanate and a polyol in the presence of a foaming agent and a catalyst, the polyol uses aniline as an initiator and has a hydroxyl value of 550. 10 to 100 parts by weight of polyether polyol of ˜630 mg KOH / g is used with respect to 100 parts by weight of the total polyol.

  The polyether polyol using aniline of the present invention as an initiator can be obtained by adding an alkylene oxide to aniline and polymerizing it so as to have a hydroxyl value of 550 to 630 mgKOH / g, preferably a hydroxyl value of 560 to 620 mgKOH / g. it can. On the other hand, when the hydroxyl value of the polyether polyol exceeds 630 mgKOH / g, the polyol is solidified and a foam cannot be formed. Conversely, if the polyether polyol has a hydroxyl value of less than 550 mgKOH / g, the initial value of thermal conductivity exceeds 0.0200 W / mK, and the time value of thermal conductivity also exceeds 0.022 W / mK. Further, the dimensional stability becomes insufficient. The molecular weight of the polyether polyol using aniline as an initiator is preferably 205 or less, and preferably 175 to 200.

  The amount of the polyether polyol having an aniline of the present invention and a hydroxyl value of 550 to 630 mg KOH / g is 10 to 100 parts by weight, preferably 20 to 80 parts by weight, out of 100 parts by weight of the total polyols. Can be used in a range. Moreover, when the usage-amount of this polyether polyol is less than 10 weight part, desired heat insulation performance cannot be obtained.

  In the present invention, the polyol other than the polyether polyol having an aniline as an initiator and a hydroxyl value of 550 to 630 mgKOH / g is other than a polyester polyol or a polyether polyol having an aniline as an initiator and a hydroxyl value of 550 to 630 mgKOH / g. These polyether polyols can be used, and these can be used singly or in appropriate combination of two or more.

  Examples of the polyester polyol include a polyol formed by condensing a polyhydric alcohol with a polyvalent carboxylic acid, and a polyol formed by cyclic ester ring-opening polymerization. Examples of the polyvalent carboxylic acid include succinic acid, glutamic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, and aliphatic polybasic acids that are anhydrides thereof. On the other hand, examples of the polyhydric alcohol include ethylene glycol, propylene glycol, glycerin, trimethylol propane, pentaerythritol, sorbitol, shoelace, and bisphenol A. As the polyester polyol, a polyester polyol having an aromatic ring is particularly preferable. The hydroxyl value of the polyester polyol is not particularly limited, but is preferably 200 to 400 mgKOH / g.

  Examples of polyether polyols other than polyether polyols having aniline as an initiator and a hydroxyl value of 550 to 630 mg KOH / g include alcohols such as aliphatic alcohols, aromatic alcohols and the above polyhydric alcohols; ethanolamine, diethanolamine, triethanol Aliphatic amines such as amine and ethylenediamine; Aromatic amines such as toluenediamine and methylenedianiline; One or more alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide are added to the Mannich condensation product The polyether polyol obtained by superposition | polymerization is mentioned, These polyether polyols can be used individually by 1 type or in combination of 2 or more types as appropriate. As the polyether polyol, an aromatic polyether polyol is particularly preferable in order to reduce the thermal conductivity. The hydroxyl value of the polyether polyol is not particularly limited, but is preferably 250 to 800 mgKOH / g.

  Examples of the polyisocyanate to be reacted with the above polyol include diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, etc .; these modified polyisocyanates, that is, products obtained by partial chemical reaction of polyisocyanate, such as esters, urea, burettes, And polyisocyanates containing groups such as allophanate, carbodiimide, isocyanurate, and urethane. These polyisocyanates can be used alone or in combination of two or more.

The amount of the polyisocyanate used is an amount such that the isocyanate index represented by the following formula (1) is 100 to 300, more preferably 110 to 250.
Isocyanate index (NCO Index) = NCO group / OH group [equivalent ratio] × 100 (1)

  Examples of the blowing agent used in the present invention include hydrocarbons such as normal pentane, isopentane, cyclopentane, and isobutane, and these can be used alone or in combination of two or more. In particular, when normal pentane, isopentane, or cyclopentane is used, it is preferable to use 5 to 30 parts by weight per 100 parts by weight of the polyol component. In addition to the hydrocarbon, water may be used in combination. When the hydrocarbon and water are used in combination, it is preferable to use 0.1 to 3 parts by weight of water per 100 parts by weight of the polyol.

  As the catalyst used in the present invention, conventionally used amine catalysts, metal catalysts, and the like can be used. Examples of the amine catalyst include N, N, N ′, N′-tetramethylhexanediamine, N, N, N ′, N′-tetramethylpropanediamine, N, N, N ′, N ″, N ′. '-Pentamethyldiethylenetriamine, N, N, N', N'-tetramethylethylenediamine, N, N, -dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, triethylenediamine, N, N ', N '-Trimethylaminoethylpiperazine, N, N-dimethylcyclohexylamine, N, N ′, N ″ -tris (3-dimethylaminopropyl) hexahydro-s-triazine, bis (dimethylaminoethyl) ether, N, N— Aminoethoxyethanol, N, N-dimethylaminohexanol, tetramethylhexanediamine, 1-methyl Imidazole, 1-isobutyl-2-methylimidazole and the like can be used. Examples of the metal catalyst that can be used include stannous octoate; dibutyltin dilaurate; lead octylate; potassium salts such as potassium acetate and potassium octylate. In addition to these amine catalysts and metal catalysts, quaternary ammonium salts of fatty acids such as formic acid and acetic acid can also be used. Each of the above catalysts may be used alone or in combination of two or more. In the present invention, the amount of the catalyst used is preferably about 0.1 to 15 parts by weight per 100 parts by weight of polyol.

  In the production of the rigid polyurethane foam of the present invention, in addition to the polyol, polyisocyanate, catalyst, and foaming agent, a flame retardant, a foam stabilizer, a compatibilizing agent, a thickener, a colorant, Additives commonly used in the production of rigid polyurethane foam, such as an agent, can be used.

  As the flame retardant used in the present invention, for example, phosphate esters such as trimethyl phosphate, triethyl phosphate, trischloroethyl phosphate and trischloropropyl phosphate are suitable. The amount used is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the total polyol. If it is less than 5 parts by weight, it may be difficult to pass the combustion test specified in JIS-A-9511. On the other hand, if it exceeds 30 parts by weight, the plastic action is too strong and the shrinkage of the foam and the mechanical strength may be insufficient. A particularly preferred use amount is 10 to 25 parts by weight.

  Examples of the foam stabilizer used in the present invention include conventionally used silicone compounds and fluorine compounds. The amount of the foam stabilizer is preferably 0.1 to 5 parts by weight.

  The rigid polyurethane foam of the present invention is obtained by reacting a polyol and a polyisocyanate in the presence of a catalyst, a foaming agent, a flame retardant, a foam stabilizer, etc., and is generally used for the production thereof. For example, a polyisocyanate and a mixture of a polyol, a catalyst, a flame retardant, a foam stabilizer, a foaming agent and other auxiliaries in a constant ratio are continuously or discontinuously used. It is possible to use a foaming method to be mixed.

  The rigid polyurethane foam obtained by the production method of the present invention includes rigid polyurethane foams such as urethane-modified rigid polyisocyanurate foams, rigid polyisocyanurate foams and other rigid foams in addition to so-called rigid polyurethane foams.

The rigid polyurethane foam obtained by the production method of the present invention has a density of 25 to 40 kg / m ³ , a cell size of 200 μm or less, a thermal conductivity of an initial value: 0.020 W / mK or less, and a time value of 0. 0.022 W / mK or less, the rate of change in dimensional stability is 5% or less, and the combustibility passes JIS A9511.

  Hereinafter, the present invention will be described in detail with reference to examples.

Examples 1-3, Comparative Examples 1-4
The raw materials used in Examples and Comparative Examples are shown below.
[Raw materials]
Polyisocyanate / polymeric diphenylmethane diisocyanate (Nippon Polyurethane Co., Ltd .: MR200: NCO content 31%)

Polyol / Polyol A: A hydroxyl value of 560 mg KOH / g using aniline as an initiator, and a polyether polyol / polyol B having a molecular weight of 200: A polyether polyol / polyol having a molecular value of 620 mg KOH / g and an molecular weight of 181 using aniline as an initiator. A polyether polyol having a hydroxyl value of 650 mg KOH / g and a molecular weight of 172 using as an initiator * However, since it was a solid, it was used after being dissolved. Polyol D: a hydroxyl value of 500 mg KOH / g having an aniline as an initiator and a molecular weight of 225 Polyether polyol / polyol E: hydroxyl value 420 mgKOH / g with toluenediamine as an initiator, polyether polyol / polyol F with molecular weight 533: hydroxyl value 315 mgKOH / g with phthalic anhydride as initiator, molecular weight 356 Polyester polyol

・ Foam stabilizer: Toray Dow Corning Co., Ltd. Foam stabilizer: SH-193

Catalyst: Tris- (dimethylaminopropyl) -hexatriazine (Air Products Co., Ltd .: Polycat 41)

・ Flame retardant: Trischloropropyl phosphate (manufactured by Daihachi Chemical Co., Ltd .: TMCPP)

Foaming agent / foaming agent A: cyclopentane / foaming agent B: water / foaming agent C: HCFC-141b

[Form production method]
The mixture having the composition shown in Table 1 was stirred at 4500 rpm for 4 seconds using a hand mixer, and then freely foamed in a wooden box of 250 mm × 150 mm × 300 mm to obtain a rigid polyurethane foam. A mixture having the same composition was stirred at 4500 rpm for 4 seconds using a hand mixer, and then freely foamed on a plate adjusted to 45 ° C. to produce a rigid polyurethane foam.
The polyisocyanate and polyol were blended so that the liquid temperature was 30 ° C. and the isocyanate index (NCO Index) was 150.

  About the rigid polyurethane foam obtained by the said manufacturing method, the density, cell size, thermal conductivity, dimensional stability, and combustibility were evaluated with the following method. The results are shown in Table 1.

〔Evaluation methods〕
Density (kg / m ³ ): A test piece of 100 mm × 100 mm × 100 mm was cut out from a rigid polyurethane foam obtained by free foaming in a wooden box, and the density of the test piece was measured according to JIS A9511.

  Cell size (μm): Measured using a scanning electron microscope JCM-5100 manufactured by JEOL Ltd.

  Thermal conductivity (W / mK): A test piece of 200 mm × 200 mm × 25 mm was cut out from a rigid polyurethane foam obtained by free foaming on a plate temperature-controlled at 45 ° C., and a heat flow meter method shown in JIS A1412 Thus, measurement was performed at an average temperature of 23 ° C. using an auto λHC-074 manufactured by Eihiro Seiki. The thermal conductivity measured the day after foaming was used as an initial value, the same sample was stored at room temperature, and the measured thermal conductivity after 30 days was evaluated as a time-dependent value.

Dimensional stability: From a rigid polyurethane foam obtained by free foaming in a wooden box, a test piece of 100 mm × 100 mm × 100 mm was cut out, and when the test piece was left at −20 ° C. for 72 hours or more, it was 72 hours or more at 100 ° C. Investigate the deformation state of the specimen when left standing and when left at 70 ° C., 95% Rh × 72 hours or longer,
○: The dimensional change rate of the foam was within 5%. ×: The dimensional change rate of the foam was evaluated as 5% or more.

Flammability: From a rigid polyurethane foam obtained by free foaming in a wooden box, a test piece of 150 mm × 50 mm × 13 mm was cut out and measured according to JIS A9511.
○: Passed JIS A9511.
X: Fails to JIS A9511.
As evaluated.

  In Examples 1 to 3, a rigid polyurethane foam having good initial values and aging values of thermal conductivity and passing in dimensional stability and flammability was obtained.

  In Comparative Example 1, since a polyol, a catalyst, a flame retardant, a foam stabilizer, a foaming agent, and other auxiliaries were solidified during mixing, a rigid polyurethane foam could not be formed.

  In Comparative Example 2, the initial value and time-lapse value of thermal conductivity were poor, and the dimensional stability at −20 ° C. and 70 ° C. and 95% Rh was poor.

  In Comparative Example 3, the initial value and the time-lapse value of the thermal conductivity were poor, and furthermore, the combustibility was unacceptable.

  In Comparative Example 4, the initial value and temporal value of the thermal conductivity were poor.

Claims (3)

In producing a rigid polyurethane foam by reacting a polyisocyanate and a polyol in the presence of a foaming agent and a catalyst,
A method for producing a rigid polyurethane foam, wherein the polyol uses aniline as an initiator and 10 to 100 parts by weight of a polyether polyol having a hydroxyl value of 550 to 630 mg KOH / g based on 100 parts by weight of the total polyol.   The method for producing a rigid polyurethane foam according to claim 1, wherein the foaming agent uses hydrocarbon. The method for producing a rigid polyurethane foam according to claim 1 or 2, wherein the density of the rigid polyurethane foam is 25 to 40 kg / m ³ .