JP3276463B2 - Manufacturing method of rigid polyurethane foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing rigid polyurethane foam used for building materials, structural materials, heat insulating materials or other uses. Specifically, 1,1-dichloro-1-fluoroethane and / or 2,2-
The present invention relates to a method for producing a rigid polyurethane foam having excellent heat insulation performance and other physical properties obtained by using dichloro-1,1,1-trifluoroethane and a specific polyester polyol as a polyol.

[0002]

2. Description of the Related Art Conventionally, rigid polyurethane foam has excellent heat insulation performance, dimensional stability and workability.
It has been widely used as a heat insulating material for refrigerators, freezers, building materials and the like. In recent years, however, chlorofluorocarbons have been regulated to protect the earth's ozone layer. This regulation covers trichlorofluoromethane (hereinafter referred to as CFC-
11) are also included. Therefore, development of a foaming agent replacing CFC-11 is urgently required, and 1,1-dichloro-1-fluoroethane (hereinafter, referred to as HCFC-141b) and / or 2,2-dichloro-1,1,1-trifluoro Hydrochlorofluorocarbons such as ethane (hereinafter referred to as HCFC-123) are considered as candidates for alternative blowing agents. However, when HCFC-141b or HCFC-123 is used as a blowing agent, the conventional CFC-1
Compared to foams foamed using 1, foams have problems such as (1) lower thermal conductivity, (2) lower foaming efficiency, (3) deterioration of foam physical properties such as dimensional stability and compressive strength. No rigid polyurethane foam was obtained. In particular, when used in refrigerators and showcases as insulation materials,
Although the same level of heat insulation performance as when using CFC-11 is required, the thermal conductivity of HCFC-141b and HCFC-123 is inferior to that of CFC-11. However, a practically satisfactory rigid polyurethane foam could not be obtained, for example, the thermal conductivity of the rigid polyurethane foam decreased and the low-temperature dimensional stability also deteriorated.

[0003] HCFC-141 having such a problem
Various improvements have been attempted to improve the heat insulation performance and physical properties of a rigid polyurethane foam using b or HCFC-123 as a foaming agent. For example, Japanese Patent Application Laid-Open No. 03-86735 (Applicant; Mitsui Toatsu Chemicals, Inc.) discloses that in a system using HCFC-141b as a foaming agent, an aromatic polyester polyol or caprolactone other than polyether polyol as a raw material. Ring polyester polyol is 1 to 1 of the total polyol.
The combined use of 60% by weight improves dimensional stability and compressive strength without lowering the thermal conductivity. In this patent, diethylene glycol / phthalic acid ester is used as the aromatic polyester polyol. JP-A-05-
No. 125141 discloses HCFC-141b or HFC-141b.
In a system using CFC-123 as a foaming agent, in addition to the polyether polyol that has been often used in the past,
An aromatic polyester polyol is used in combination with 5% by weight or more of the whole polyol to improve thermal conductivity, dimensional stability and compressive strength. In this patent, as a raw material of an aromatic polyester polyol, a combination of a phthalic anhydride compound with trimethylolpropane, pentaerythritol, glycerin, sorbitol, ethylene glycol, diethylene glycol, and the like is described. JP-A-04-154846 discloses that in a system using HCFC-141b or HCFC-123 as a blowing agent, an aromatic polyester polyol obtained from a difunctional or higher functional polyol and a trifunctional or higher functional aromatic carboxylic acid is used. And improves thermal conductivity, dimensional stability and compressive strength. According to the studies and findings of the present inventors, the prior art described above is based on the conventional methods regarding the moldability in the process of forming the foam, and the physical properties such as heat insulation performance, dimensional stability and compressive strength of the obtained foam. Although improved, it is still insufficient.

[0004]

The problem to be solved by the present invention is that of HCFC-141b or HCFC-12.
3 is to improve the heat insulation performance and physical properties of a rigid polyurethane foam obtained by using the same as a foaming agent.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, HCFC-141b and / or HCFC-1 have been used as main blowing agents.
In producing a rigid polyurethane foam using No. 23, a special polyester polyol component was used to find a method of producing a rigid polyurethane foam having excellent heat insulation performance and good physical properties, and reached the present invention.
That is, the present invention provides the component (A) an organic polyisocyanate,
(B) low molecular weight active hydrogen compound, (C) low molecular weight aromatic polyester polyol, (D) 1,1-dichloro-1-fluoroethane and / or 2,2-dichloro-1,1,1-tri In a process for producing a rigid polyurethane foam from a blowing agent mainly composed of fluoroethane, (E) a catalyst, (F) a foam stabilizer and, if necessary, (G) other auxiliaries, component (C) a low molecular weight aromatic The polyester polyol is a component (a) selected from phthalic anhydride and o-phthalic acid, and
0.7 to 1.4 moles of a triol component (b) obtained by adding 0.8 to 2.5 moles of propylene oxide and / or ethylene oxide to 1 mole of an initiator selected from glycerin and trimethylolpropane, and a diol selected from ethylene glycol and propylene glycol 0.7 to 1.4 mol of component (c) is added to component (a)
The sum of the molar ratios of (b) and (c) ((b) / (a) + (c) /
(a) is an aromatic polyester polyol having an acid value of 5 mg-KOH / g or less obtained by reacting in a range where 2.0) or more, and wherein the ratio of component (C) is component (B) and component (C). ) Is 20 to 80% by weight with respect to the total amount of the rigid polyurethane foam.

The aromatic polyester polyol of component (C) is a component selected from phthalic anhydride and o-phthalic acid.
(a) 1 to 1 mole of an initiator selected from glycerin and trimethylolpropane, and 0.8 to 2.5 moles of a propylene oxide and / or ethylene oxide added to 1 mole, (b) 0.7 to 1.4 moles of a triol component, and An aromatic polyester polyol having an acid value of 5 mg-KOH / g or less obtained by reacting 0.7 to 1.4 mol of a diol component (c) selected from ethylene glycol and propylene glycol. If the number of moles of propylene oxide and / or ethylene oxide in component (b) is less than 0.8, the effect of the present invention is weak, and if it is more than 2.5, the dimensional stability and compressive strength of the obtained foam decrease. The molar ratio of components (b) and (c) to component (a) is in each case from 0.7 to 1.4. If it is less than this range, the resulting polyester polyol will have a higher degree of condensation and the viscosity will be extremely increased, thus making it unusable. Conversely, if it is larger than this, the degree of condensation will be reduced and the dimensional stability and compressive strength of the foam will decrease. The aromatic polyester polyol of the component (C) thus obtained is mixed so as to be 20 to 80% by weight based on the total amount of the components (B) and (C), and the raw material for the rigid polyurethane foam is mixed. But is preferably 40 to 70% by weight. If the number of parts used is less than 20% by weight, the effect of the present invention is weak, and if it exceeds 80% by weight, the viscosity is greatly increased, so an extra thickener is required,
Alternatively, the compatibility with the polyisocyanate or the blowing agent is reduced, and the uniformity of the reaction or the storage stability is impaired. These aromatic polyester polyols are synthesized according to a usual method. The reaction temperature is preferably from 150 to 230 ° C. Water generated during the esterification is gradually removed by reduced pressure or nitrogen bubbles. At this time, if the dehydration is not sufficient, the acid value does not decrease to the target value due to hydrolysis of the ester. The reaction time is suitably 4 to 10 hours. A reaction catalyst may or may not be used, but if not used, the reaction slows down and undesirably increases by-products (ethers) due to dehydration of hydroxyl groups. Catalysts include tetrakis (n-butyl) titanate and other metal catalysts commonly used as esterification or transesterification catalysts. However, when a tertiary amine having a high boiling point is used as an alkylene oxide addition catalyst when synthesizing the component (b), the tertiary amine remains as it is in the component (b) and serves as an esterification catalyst. No need.

The organic polyisocyanate of the component (A) is an organic compound having two or more isocyanate groups in one molecule, and includes aliphatic and aromatic polyisocyanates and modified products thereof. included. Specific examples of the aromatic polyisocyanate include 4,4′-diphenylmethane diisocyanate (4,4′-MDI),
4'-Diphenylmethane diisocyanate (2,4'-MD
I), polymethylene polyphenyl polyisocyanate (crude MDI), 2,4-diisocyanate toluene (2,4-
TDI), 2,6-diisocyanatotoluene (2,6-TD
I), crude TDI, aniline / diaminotoluene (TD
Also included are triisocyanates synthesized from A) / formaldehyde, and mixtures thereof. Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate (HDI) and isophorone diisocyanate (I
PDI). Examples of the modified products include an isocyanate prepolymer which is a reaction product of an active hydrogen compound such as a polyol, an amine, or a thiol with the above isocyanate, or a carbodiimide modified product of these isocyanates. Among these, preferred organic polyisocyanates are aromatic polyisocyanates or modified products thereof, and particularly preferred are MDI, crude MD
I and their modified products. These organic polyisocyanates usually have an active hydrogen equivalent of 0.9 to 1.1.
The isocyanate equivalent is doubled, but when it is partially isocyanurated, an amount larger than 1.1 times may be used.

The low molecular weight active hydrogen compound of the component (B)
It is a compound having a functional group that reacts with an isocyanate group. Specific examples include polyols, primary and / or secondary amines, and thiols. These active hydrogen compounds usually have at least two active hydrogen groups and have an active hydrogen equivalent of about 31 to about 200. Among these compounds, a polyol is mainly used as the active hydrogen compound. As the primary and / or secondary amines, specifically, for example, ethylenediamine, diethylenetriamine, piperazine, 4,4′-diaminodiphenylmethane (4,4′-MDA), 2,4′-diaminodiphenylmethane (2, 4'-MDA), 2,4-diaminotoluene (2,4-TD
A) and 2,6-diaminotoluene (2,6-TDA). Specific examples of the thiols include thioglycol, and a polyvalent thiol compound obtained by esterification of β-mercaptopropionic acid and pentaerythritol. However, the preferred low molecular weight active hydrogen compounds used primarily are polyols. Specific examples of the polyol include aliphatic low molecular weight polyols such as ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, α-methylglucoside, sorbitol, and sucrose, and bisphenol-A.
And aromatic polyols such as N, N ', N "-tris (hydroxyethyl) isocyanurate. However, more preferred low molecular weight active hydrogen compounds include these low molecular weight polyols, water, and the above amines. And low-molecular-weight polyether polyols obtained by adding alkylene oxides such as propylene oxide, ethylene oxide and butylene oxide to thiols as initiators, and aliphatic dicarboxylic acids such as adipic acid and low-molecular weight glycols. Examples include aliphatic polyester polyols obtained by esterification or ring-opening polymerization of caprolactone, and polytetramethylene ether glycol obtained by ring-opening polymerization of tetrahydrofuran.

These active hydrogen compounds have at least two active hydrogen groups and preferably have an active hydrogen equivalent of 31 to 200. If used, these polyols can be used in combination. Specifically, for example, there are a high molecular weight polyether polyol, a high molecular weight polyether containing a terminal amino group and a high molecular weight polyethylene ether glycol obtained by addition polymerization of propylene oxide, ethylene oxide or butylene oxide to the above-mentioned initiator. Also, a compound having only one active hydrogen group can be used in combination if it is in a small amount. In addition, basically any active hydrogen compound that can be used in the production of a urethane resin can be used in combination. The reason is that the rigid polyurethane foam obtained by the method of the present invention is a polymer having a firm crosslinked structure, so that a small amount thereof does not significantly affect the polymer skeleton.

The blowing agent of component (D) may be any of 1,1-dichloro-1-fluoroethane (HCFC-141b) and 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123). It is a foaming agent mixture mainly or both, but other foaming agents may be used in combination with these foaming agents in some cases. Examples of the optional foaming agent include water, carbon dioxide, air (nitrogen), and halogenated hydrocarbon compounds, that is, methylene chloride, trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), Dichlorofluoromethane (CFC-21), chlorodifluoromethane (CF
C-22), trichlorofluoroethane (HCFC-1
31), 2,2-trichloro-1,1,1-trifluoroethane (CFC-113), 1,2,2-trichloro-1,1-difluoroethane (HCFC-122), chloropentafluoroethane (CFC -115). Also, pentane, isopentane, cyclopentane, 2-methylbutane,
Hydrocarbon compounds including hexane, cyclohexane, etc.
Further, there are low boiling compounds such as methyl formate, dimethyl ether and diethyl ether. Of these, water is particularly often used in combination.

The catalyst of component (E) is a conventionally known rigid polyurethane foam catalyst. In particular,
As tertiary amines, triethylamine, triethylenediamine, tetramethylethylenediamine, tetramethylpropanediamine, tetramethylhexanediamine,
Pentamethyldiethylenetriamine, N-methylmorpholine, bis (N, N-dimethylaminoethyl) ether, 2- [N- (dimethylaminoethoxyethyl) -N-methylamino] ethanol, bis (aminoethyl) ethers Examples of the metal catalyst include dibutyltin dilaurate, stannas octoate, and lead octylate. As the trimerization catalyst (isocyanuration catalyst), potassium acetate, potassium octylate,
4,6-tris (dimethylaminopropyl) hexahydro
-1,3,5-triazine, tetraalkylammonium chloride, tetraalkylammonium bromide, tetraalkylammonium iodide and the like. Any other material can be used as long as it can be used as a catalyst for the rigid polyurethane foam. These catalysts are used alone or as a mixture, and the amount of use is suitably 0.01 to 5% by weight based on the total amount of the components (A) and (B).

As the foam stabilizer of component (F), conventionally known silicone derivatives for rigid polyurethane foams are used. For example, L-542 manufactured by Nippon Unicar Co., Ltd.
0, L-5340, SZ-1645, SZ-1627
F-343 and F-347 manufactured by Shin-Etsu Chemical Co., Ltd.
Suitable are F-350S, F-345, F-348, etc., and SH-193, SH-190, etc., manufactured by Toray Dow Corning Co., Ltd. The appropriate amount of these foam stabilizers is 0.5 to 5 parts by weight based on 100 parts by weight of the active hydrogen compound.

Auxiliaries used as needed for component (G) include conventionally known flame retardants, plasticizers, viscosity reducers, stabilizers, inorganic fillers and organic fillers.

As the method for producing the rigid polyurethane foam of the present invention, any molding method conventionally used in the production of rigid foams can be applied. The simplest method is to mix the polyol, the catalyst, the foam stabilizer, the anti-shrinkage agent and the foaming agent in advance (premix resin) with an organic polyisocyanate for 6000.
There is a method in which the mixture is vigorously stirred and mixed with a high-speed rotating lab stirrer of 90009000 rpm and foamed in a specific container. However, as an actual production method, there is a method in which the two liquids are impact-mixed with a high-pressure foaming machine and injected into a mold. It is also possible to produce the foam using a spree foaming machine. In carrying out the present invention, a predetermined amount of a polyol, a foaming agent, a catalyst and a foam stabilizer is mixed to form a resin solution. High-speed mixing of resin solution and organic polyisocyanate at a fixed ratio,
Inject or spray into cavity or mold. At this time, the ratio of the isocyanate equivalent to the active hydrogen equivalent in the resin solution was 0.
Adjust the liquid ratio between the organic polyisocyanate and the resin so that the ratio is 7: 1 to 5: 1.

[0015]

The present invention will be specifically described below with reference to examples. <Raw Materials Used> The raw materials used in the examples are as follows. Isocyanate A: Cosmonate M-200 (crude MDI) manufactured by Mitsui Toatsu Chemical Co., Ltd.
NCO% = 28.9 in polyisocyanate obtained by mixing 100 (2,4-TDI) modified products. Polyol A: 460 mg of hydroxyl value obtained by adding propylene oxide to a mixture of sorbitol / glycerin
-KOH / g polyether polyol. HCFC-141b: 1,1-dichloro-1-fluoroethane. HCFC-123: 2,2-dichloro-1,1,1-trifluoroethane. PMDETA: Kaolyzer No-3 (N, N, N ', N ", N" -pentamethyldiethylenetriamine) with a urethane foaming catalyst manufactured by Kao Corporation. SZ-1645: Polydimethylsiloxane derivative manufactured by Nippon Unicar Co., Ltd., silicone foam stabilizer.

[0016] Polyester polyols were produced according to the following Reference Examples. Reference Example 1 Synthesis of Triol A In a 2-liter autoclave, 920 g (10 mol) of glycerin was added.
And 7.5 g of dimethyl palmitylamine as a catalyst and heated to 110 ° C., then 626 g of propylene oxide
(1.08 mol) was added for 3 hours. The hydroxyl value of the obtained triol A was 1090 mg-KOH / g. Reference Example 2 Synthesis of Triol B In a 2-liter autoclave, 920 g (10 mol) of glycerin was added.
And 8.0 g of dimethyl palmitylamine as a catalyst and heated to 110 ° C., followed by 870 g of propylene oxide (15 g).
Mol) was reacted for 3 hours. The hydroxyl value of the obtained triol B was 945 mg-KOH / g. Reference Example 3 Synthesis of Triol C A 2-liter autoclave was charged with 1070 g (8 mol) of solid trimethylolpropane, and dimethylpalmitylamine was added.
After 6.5 g was added as a catalyst and the temperature was raised to 110 ° C., 464 g (8 mol) of propylene oxide was subjected to an addition reaction over 5 hours. The hydroxyl value of the obtained triol C is 880mg-KOH / g
Met. Reference Example 4 Synthesis of Polyester Polyol A 26.6 kg (180 mol) of phthalic anhydride and 27.8 kg of triol A
Kg (180 mol) is charged to 50 liter autoclave and 120
After raising the temperature to ℃, the reaction was carried out for 1 hour. Thereafter, 15.6 kg (251 mol) of ethylene glycol was added, the temperature was raised to 200 to 220 ° C, and the reaction was carried out for 3 hours while dehydrating. Since the distillation of water ceased, the reaction was continued for 7 hours while bubbling nitrogen through. The hydroxyl value of the obtained polyester polyol A is 50
0 mg-KOH / g, acid value 0.48 mg-KOH / g, moisture 0.025% by weight,
The viscosity was 24000 cps / 25 ° C. When the content of ethylene glycol and glycerin in the polyester polyol was examined by gas chromatography, it was 5.4% each.
And 3.1% by weight. Reference Example 5 Synthesis of polyester polyol B 26.6 kg (180 mol) of phthalic anhydride and triol B32.2
Kg (180 mol) is charged to 50 liter autoclave and 120
After the temperature was raised to ° C., the reaction was carried out for 1 hour. Thereafter, 15.6 kg (251 mol) of ethylene glycol was added, and the reaction was carried out in the same manner as in Reference Example 4. The hydroxyl value of the obtained polyester polyol B was 475 mg-KOH / g, and the acid value was 0.53 mg-KOH / g.
g, water content 0.023% by weight, and viscosity was 18000 cps / 25 ° C. The content of ethylene glycol and glycerin in the polyester polyol is 5.1 and 3.
3% by weight. Reference Example 6 Synthesis of polyester polyol C 26.6 kg (180 mol) of phthalic anhydride and triol C34.6
Kg (180 mol) is charged to 50 liter autoclave and 120
After the temperature was raised to ° C., the reaction was carried out for 1 hour. Thereafter, 15.6 kg (251 mol) of ethylene glycol was added, and the reaction was carried out in the same manner as in Reference Example 4. The hydroxyl value of the obtained polyester polyol C was 465 mg-KOH / g, and the acid value was 0.48 mg-KOH / g.
g, water content 0.025% by weight, viscosity 26000 cps / 25 ° C. The content of ethylene glycol in the polyester polyol was 5.5% by weight. Comparative Reference Example Synthesis of Polyester Polyol D (Prior Art) 27.2 kg (184 mol) of phthalic anhydride, 16.9 kg (184 mol of glycerin)
Mol) and 15.9 kg (257 mol) of ethylene glycol in the same manner as in Reference Example 4. The hydroxyl value of the obtained polyester polyol D was 573 mg-KOH / g, the acid value was 0.93 mg-KOH / g, the water content was 0.06% by weight, and the viscosity was 65000 cps / 25.
° C. The contents of ethylene glycol and glycerin in the polyester polyol were 6.2 and 7.9% by weight, respectively.

Examples 1-4 Predetermined amounts of the polyol, foaming agent, catalyst and foam stabilizer shown in Table 1 were mixed in advance, put into a tank of a foaming machine, and kept at 20 ° C. The amount of CFC-based blowing agent used is 15 per urethane resin.
%. Further, polyisocyanate A was put in another tank and kept at 20 ° C. Thereafter, a molding test was carried out by injecting into a mold by mechanical foaming. Type is box type (250 × 2
A 50 x 250 mm wooden box) and a vertical aluminum panel (size: 400 x 400 x 30 mm in thickness) preliminarily adjusted to 45C were used. After 6 minutes, the foam was demolded, and the physical properties of the obtained foam were measured. The measured values of the foaming density, dimensional stability, compressive strength and thermal conductivity are shown in Table 1, and all the values are average values measured at several locations. The measurement conditions of the physical properties of the rigid foam are as follows. Free density: 100 × 100 × 100mm This is the density of the core of the foam obtained by free foaming. Thermal conductivity: 200 × 200 × 20mm, (Auto-λ EKO) Dimensional stability: 95 × 95 × 95mm, -30 ° C × 24 hours

Comparative Examples 1-2 By the same operation as in the examples, rigid polyurethane foams were obtained according to the formulations shown in Table 1. Table 1 shows the physical property values of the obtained rigid foam.

[0019]

As is clear from the comparison between Examples 1-4 and Comparative Examples 1-2, HCFC-141b or HCFC-141b
When an aromatic polyester polyol is used as a part of the active hydrogen compound when producing a rigid polyurethane foam using 123, a foam having excellent heat insulation performance (thermal conductivity), dimensional stability and compressive strength can be obtained. Was.

[0020]

[Table 1]

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-154846 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 18/00-18/87

Claims (1)

(57) [Claims] 1. Component (A) an organic polyisocyanate, (B) a low molecular weight active hydrogen compound, (C) a low molecular weight aromatic polyester polyol, (D) 1,1-dichloro-1-fluoroethane and / or Alternatively, a rigid polyurethane foam is prepared from a foaming agent mainly composed of 2,2-dichloro-1,1,1-trifluoroethane, (E) a catalyst, (F) a foam stabilizer and, if necessary, (G) other auxiliaries. In the production method, component (C) the low-molecular-weight aromatic polyester polyol comprises phthalic anhydride and o-
Triol component (b) obtained by adding 0.8 to 2.5 mol of propylene oxide and / or ethylene oxide to 1 mol of initiator selected from glycerin and trimethylolpropane per 1 mol of component (a) selected from phthalic acid 0.7 to 1.4 moles and a diol component selected from ethylene glycol and propylene glycol
(c) 0.7 to 1.4 moles, and the sum of the molar ratios of components (b) and (c) to component (a) ((b) / (a) + (c) / (a)) is 2.0
The acid value obtained by reacting in the above range is 5 mg-KOH /
g or less aromatic polyester polyol, and
A process for producing a rigid polyurethane foam, wherein the ratio of the component (C) is 20 to 80% by weight based on the total amount of the components (B) and (C).