JPH05239168A - Production of rigid polyurethane foam - Google Patents

Abstract

PURPOSE:To provide a rigid polyurethane foam excellent in the dimensional stability, heat resistance, profitability and processability and having the same density as those of conventional rigid polyurethane foams even when a specific Freon is largely reduced. CONSTITUTION:When a polyisocyanate component is reacted with a polyol component in the presence of a foaming agent and a catalyst, etc., to produce a rigid polyurethane foam, the NCO/OH equivalent ratio of the components is controlled to 1.2-1.6, and monochlorodifluoromethane (HCFC-22) in an amount of 2-6wt.% based on the whole weight of the polyisocyanate component and the polyol component and water in an amount of 2-5 pts.wt. per 100 pts.wt. of the polyol are simultaneously used as the foaming agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rigid polyurethane foam capable of significantly reducing specific CFCs without impairing the dimensional stability, heat insulation, economy and processability of the rigid polyurethane foam.

[0002]

2. Description of the Related Art Rigid polyurethane foams are usually produced by reacting a polyisocyanate component with a polyol component comprising a polyol, a foaming agent, a catalyst, a foam stabilizer and the like. Trichloromonofluoromethane (CFC-11) is mainly used as the foaming agent, but it is also known to use water, which reacts with the polyisocyanate component to generate carbon dioxide, as an auxiliary foaming agent. The NCO / OH equivalent ratio is usually about 1.0 to 1.2.

[0003]

[Problems to be Solved by the Invention] The above CFC-11
Is a specific CFC regulated by the CFC Regulation Act that came into effect in 1989, and its usage must be reduced in stages. Under this circumstance, the development of CFCs that are not subject to the above regulations has been in progress, but has not yet been put into practical use. For this reason, as a short-term means for reducing the use of specific CFCs, it is said that increasing the amount of water used in combination with CFC-11 is a practical countermeasure for the time being, and 2 parts by weight of water is used per 100 parts by weight of polyol. Used before and after, CFC-
A rigid polyurethane foam having a density of about 30 kg / m ³ in which 11 is reduced by about 30% is being put to practical use. Further, if the amount of water is increased, it is possible to produce a rigid polyurethane foam without using CFC-11.

However, in this case, the gas contained in the foam cell is only carbon dioxide, and carbon dioxide has a higher thermal conductivity than CFC-11, so that the heat insulating property of the foam deteriorates. Also, since carbon dioxide diffuses rapidly from the cell into the atmosphere, the foam tends to shrink even at room temperature, and the foam density should be 4 to obtain good dimensional stability.
It is uneconomical because it must be increased to 0 kg / m ³ or more. Further, in this case, since CFC-11, which has a large effect of reducing the viscosity of the polyol component, is not used, it becomes difficult to supply the polyol component from the container to the foaming machine unless a low-viscosity polyol is used. Further, the rigid polyurethane foam produced with a normal NCO / OH equivalent ratio using a low-viscosity polyol is likely to have poor dimensional stability. The present invention has been made against the background of the above-mentioned problems of the prior art. Even if the specific CFCs are significantly reduced, the density is equivalent to that of the conventional one, and the dimensional stability, heat resistance, economic efficiency and workability are excellent. It is an object to provide a rigid polyurethane foam.

[0005]

According to the present invention, when a polyisocyanate component and a polyol component are reacted in the presence of a foaming agent and a catalyst to produce a rigid polyurethane foam, the NCO / OH equivalent ratio is 1.2. 1 to 1.6, and 2 to 6% by weight of monochlorodifluoromethane (HCFC-22) as a foaming agent based on the total weight of the polyisocyanate component and the polyol component, and the polyol 1
The present invention provides a method for producing a rigid polyurethane foam, characterized in that 2 to 5 parts by weight of water is used in combination with 00 parts by weight.

As the polyisocyanate component used in the present invention, generally used aromatic polyisocyanate or aliphatic polyisocyanate can be adopted.
Specific examples of the polyisocyanate component include diphenylmethane-4,4'-diisocyanate, 3-methyldiphenylmethane-4,4'-diisocyanate and mixtures thereof, tolylene 2,4-diisocyanate,
Any of those commonly used in the production of rigid polyurethane foams such as tolylene 2,6-diisocyanate and mixtures thereof, hexamethylene diisocyanate can be used.

As the polyol used in the present invention, tolylenediamine, ethylenediamine, triethanolamine, Mannich condensation product, sucrose, polyether polyol obtained by adding alkylene oxide to glycerin, or PET scrap or DMT process. Aromatic polyester polyols based on residues, phthalic acid and the like can be used alone or in combination. As the polyol, one having a low viscosity is preferable. The viscosity of the polyol alone or a mixed polyol obtained by combining other polyols is preferably 600 to 2,500 cps.
(25 ° C.), more preferably 800 to 2,000 cp
It is convenient to supply the polyol component from the container to the foaming machine at about s (25 ° C).

In the present invention, the NCO / OH equivalent ratio is preferably 1.2 to 1.6, preferably 1 in order to produce a rigid polyurethane foam having excellent dimensional stability, preferably using a low viscosity polyol. It is a necessary condition that the isocyanate trimer crosslink is partially formed at a higher value than 0.3 to 1.5. When the NCO / OH equivalent ratio is less than 1.2, the dimensional stability of the obtained foam is deteriorated because trimer crosslinks are hardly formed, while 1.
When it exceeds 6, the trimer cross-linking becomes excessive and brittleness of the foam becomes high, resulting in poor adhesiveness.

HCFC-used as a foaming agent
The amount of 22 (monochlorodifluoromethane) used is 2 to 6% by weight, preferably 3 to 5% by weight, based on the total weight of the polyisocyanate component and the polyol component. Below 2% by weight, a large amount of water must be used to obtain a foam having a density of around 30 kg / m ³ , and HCFC-
Since the amount of 22 is small, the effect of promoting the mixing becomes small, resulting in insufficient mixing of the polyisocyanate component and the polyol component, resulting in heat insulation of the foam.
Dimensional stability deteriorates. On the contrary, if it exceeds 6% by weight, a foam having a smooth surface cannot be obtained.

The HCFC-22 is mixed in a liquid state by applying high pressure into a conduit between a compression metering pump of a polyisocyanate component and / or a polyol component and a mixing head, or directly mixed into the mixing head. Good. As a foaming agent, this HCFC
In addition to -22, CFC-11, methylene chloride, pentane and the like, which further lower the viscosity of the polyol component, can be used in combination in an amount of about 15 parts by weight or less based on 100 parts by weight of the polyol.

The present invention is characterized in that water is used. The amount of water used is 2 to 5 parts by weight, preferably 3 to 4 parts by weight, based on 100 parts by weight of the polyol.
If less than 5 parts by weight or more than 5 parts by weight, HCF
Since the amount of C-22 used must be increased or decreased, the same problem as that of the above HCFC-22 used occurs.

The catalyst used in the polyurethane reaction is, for example, an amine-based urethane-forming catalyst such as dimethylethanolamine, triethylenediamine, tetramethylpropanediamine, tetramethylhexamethylenediamine, dimethylcyclohexylamine or pentamethyldiethylenetriamine, dibutyltin. Gilaurylate,
Examples thereof include organometallic urethane-forming catalysts such as lead octylate and trimerizing catalysts such as tris (dimethylaminopropyl) hexahydro-S-triazine and potassium octylate. In particular, when the NCO / OH equivalent ratio is 1.3 or more, it is preferable to use the urethanization catalyst and the trimerization catalyst in combination, but the combination ratio is not particularly limited. These catalysts are usually used in an amount of about 0.1 to 5 parts by weight based on 100 parts by weight of the polyol.

In the production of the rigid polyurethane foam of the present invention, other additives generally used in the production of the rigid polyurethane foam, such as a foam stabilizer, a flame retardant, a coloring agent and a stabilizer, can be added. ..

As a concrete means for producing the rigid polyurethane foam of the present invention from the above raw materials, any device can be used as long as it can uniformly mix the above raw materials. For example, a mixer or a foaming machine is used. The rigid polyurethane foam of the present invention can be easily obtained by uniformly and continuously mixing.

[0015]

The present invention is a non-specific chlorofluorocarbon HC as a foaming agent.
CFC-11 (trichloromonofluoromethane) by using FC-22 (monochlorodifluoromethane) and water together and increasing the NCO / OH equivalent ratio higher than usual
Even if the number is significantly reduced, it is possible to obtain a rigid polyurethane foam with the same density as the conventional one, without impairing the dimensional stability, heat insulating property, economical efficiency and processability.

[0016]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the examples, parts and% are based on weight unless otherwise specified. Further, in the examples, the hydroxyl value is the mg number of potassium hydroxide corresponding to the OH group in 1 g of the polyol. Also, density, compressive strength, adhesive strength,
The thermal conductivity was measured according to the method of JIS A9526. Furthermore, the dimensional stability (high-temperature volume change rate, low-temperature volume change rate) is 7 × 100 × 30 mm.
The rate of change in volume after standing for 24 hours at temperatures of 0 ° C and -20 ° C was measured and expressed.

Reference Example (Preparation of Raw Material) Polyisocyanate; Mitsui Toatsu Chemical Co., Ltd., Cosmonate M-100 Polyol A; Ethylenediamine + PO / EO, Hydroxyl Value = 355, Viscosity = 1,000 cps (25 ° C.) Polyol B: triethanolamine + PO / EO, hydroxyl value = 200, viscosity = 500 cps (25 ° C.) Polyol C: ethylenediamine + PO, hydroxyl value = 7
60, viscosity = 45,000 cps (25 ° C.) Polyol D; ethylenediamine + PO / EO, hydroxyl value = 450, viscosity = 1,300 cps (25 ° C.) Polyol E; Mannich condensation product + PO, hydroxyl value = 5
30, viscosity = 15,000 cps (25 ° C)

Foam stabilizer: Nippon Unicar Co., Ltd., L-5420 Catalyst A; Dainippon Ink and Chemicals Co., Ltd., Pb-OC Catalyst B; Activator Chemical Co., Ltd., L-1020 Catalyst C; Sancatro Co., Ltd., Polycat 41 flame retardant; Daihachi Chemical Co., Ltd., TMCPP (Tris monochloropropyl phosphate) Foaming agent A; HCFC-22 (monochlorodifluoromethane) Foaming agent B; CFC-11 (trichloromonofluoro) methane)

Examples 1 to 5 and Comparative Examples 1 to 5 In the formulation shown in Tables 1 and 2, polyols, additives, foam stabilizers, catalysts, water, etc. were blended to prepare a polyol component.
A polyisocyanate component was added so that the NCO / OH equivalent ratios in Tables 1 and 2 were obtained, and a Binks Model G foaming machine (manufactured by Binks Manufacturing Company) and HCFC- were used.
No. 22 Gasmer auxiliary pump (manufactured by Gasmer) was used for spray foaming to obtain a hard polyurethane foam having a thickness of 50 mm. The temperature of the polyisocyanate component and the polyol component was 45 ° C. Tables 1 and 2 show the results of measuring the density, compressive strength, adhesive strength, and high temperature / low temperature dimensional stability of the obtained rigid polyurethane foam.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

EFFECTS OF THE INVENTION According to the present invention, a rigid polyurethane foam can be obtained at the same density as the conventional one, without impairing the dimensional stability, heat insulating property, economical efficiency, and processability even if the specific CFCs are greatly reduced. ..

Claims (1)

[Claims] 1. When producing a rigid polyurethane foam by reacting a polyisocyanate component and a polyol component in the presence of a foaming agent, a catalyst and the like, NCO / OH is used.
The equivalent ratio is 1.2 to 1.6, and 2 to 6 parts by weight of monochlorodifluoromethane as a foaming agent based on the total weight of the polyisocyanate component and the polyol component, and 2 to 5 parts by weight based on 100 parts by weight of the polyol. A method for producing a rigid polyurethane foam, which is characterized in that the water is used together.