JPH0196209A - Production of rigid polyurethane foam - Google Patents

Abstract

PURPOSE:To obtain the titled foam at low cost with extremely low density and low thermal conductivity, to be used as e.g., thermal insulating materials for refrigerators, by reaction between each specific polyol component and isocyanate component in the presence of a foaming agent etc. CONSTITUTION:The objective foam can be obtained by reaction between (A) as the polyol component, a blend having an average OH value of 380-410, made up of a) 47-53wt.% of a polyol prepared by adding to sucrose (i) propylene oxide and (ii) ethylene oxide, b) 13-17wt.% of a second polyol prepared by adding to propylene oxide the component (ii), c) 23-27wt.% of a third polyol prepared by adding to tolylenediamine the components (i) and (ii) and d) 23-27wt.% of a fourth polyol prepared by adding to diethanolamine the component (i) and (ii), and (B) as the isocyanate component, a blend having an average NCO% of 32-34, made up of e) 50-60wt.% of polymethylene polyphenyl diisocyanate and f) 40-50wt.% of sucrose tolylenediisocyanate prepolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing closed-cell rigid polyurethane foams having extremely low density and low thermal conductivity.

[Conventional technology]

Rigid polyurethane foams are usually obtained by reacting a polyol component and an isocyanate component in the presence of a blowing agent, a reaction catalyst, and a foam stabilizer. In general, rigid polyurethane foam with closed cells is widely used as a variety of heat insulating materials due to its excellent heat insulating properties. Various improvements have been proposed.

For example, Japanese Patent Application Laid-open No. 59-84913 discloses that in order to produce a rigid polyurethane foam with low density and improved heat insulation properties, 64 to 66% by weight of a tetrafunctional tolylene diamine polyol as a polyol component, A method using a polyol mixture consisting of 14 to 16% by weight of a difunctional propylene polyol, 5 to 7% by weight of an octafunctional sucrose polyol, and 13 to 15% by weight of a jetanolamine polyol is proposed.

[Problem that the invention seeks to solve]

The rigid polyurethane foam obtained by the above method is
Thermal conductivity is 13.0X10-”~14.OX10=
kcal/ugly/h/°C, the low temperature dimensional change rate is less than 11%, and the compressive strength is more than 0.8 kg/aJ, which is very excellent, but the density is 21-22 kg/n at free foam density? Although it has a relatively low density (panel foam density of 29 to 30 kg/rn'), especially in the field of insulation materials for refrigerators, it is necessary to use a material with an even lower density, preferably a free foam density of 20 kg/rn', in order to save resources. rn' (panel foam density: 27kg)
/rd) and low thermal conductivity has been desired for a long time. However, rigid polyurethane foams having closed cells tend to shrink at low temperatures when the free foam density is less than 20 kg/rd, and the compressive strength becomes extremely low.

The object of the present invention is to have extremely low density and low thermal conductivity (13,0XIO1-14,
The object of the present invention is to produce a rigid polyurethane foam having an OX 10-"kcal/m-h."C) without deteriorating its physical properties such as low-temperature dimensional stability and compressive strength.

[Means for solving problems]

The present invention provides a method for producing rigid polyurethane foam in which a polyol component and an isocyanate component are reacted in the presence of a blowing agent, a reaction catalyst, and a foam stabilizer, in which propylene oxide and ethylene oxide are added to (a) sucrose as the polyol component. 47-53% by weight of the polyol obtained.

(b) Polyol 13 obtained by adding propylene oxide and ethylene oxide to propylene glycol
17% by weight.

(C) 8 to 12% by weight of polyol obtained by adding propylene oxide to jetanolamine, and (d) Polyol 23 to 27 obtained by adding propylene oxide and ethylene oxide to tolylene diamine.
% by weight of a polyol mixture, the average O of that polyol mixture is
(A) 50 to 60% by weight of polymethylene polyphenyl diisocyanate;

(B) A method for producing a rigid polyurethane foam, which comprises using a 40 to 50% by weight isocyanate mixture whose average NCO% is 32 to 34. provide.

The invention further provides a rigid polyurethane foam produced by the above method.

The present invention further provides a rigid polyurethane foam forming tissue for use in the above method.

The invention further provides a method of using the rigid polyurethane foam produced by the above method in a refrigerator.

〔Example〕

The present invention is characterized in that a mixed polyol composition having a special composition as a polyol component is used in combination with a mixed isocyanate composition having a special composition as an isocyanate component. The rigid polyurethane foam obtained by using a combination of
In addition to achieving extremely low density, the flowability can be greatly improved, and the difference between panel foam density and free foam density can be reduced to 8 kg/m or less, preferably 7.5 kg/rrt' or less), and thermal conductivity. rate to 14.5X10-'kcal
/l1-h・℃ or less, preferably 14.0X10-'
It can be maintained at ~13.0×1O-3kcal/11・h・℃, the low-temperature dimensional change rate is 13% or less, preferably 11% or less, and the compressive strength is 0.7kg/aJ or more, preferably Q, can be maintained at 8 kg/aJ or more.

The mixed polyol composition used in the present invention consists of the following components: (a) 47 to 53% by weight of a polyol obtained by adding propylene oxide and ethylene oxide to sucrose;

(b) Polyol 13 obtained by adding propylene oxide and ethylene oxide to propylene glycol
17% by weight, (c) 8-12% by weight of a polyol obtained by adding propylene oxide to jetanolamine, and (d) 23-27% of a polyol obtained by adding propylene oxide and ethylene oxide to tolylene diamine.
% by weight and the average OH number of the composition must be between 380 and 410.

In the above mixed polyol composition, component (a) is effective in improving low-temperature dimensional stability, compressive strength, and demoldability, component (b) is effective in improving fluidity and compatibility, and (
It is believed that component C) is effective in improving fluidity, and component (d) is effective in improving thermal conductivity. In addition, the OH value of the mixed polyol composition is 380
If it is less than 410, the low temperature dimensional stability will decrease, and if it exceeds 410, fryability will easily occur, both of which will cause production defects, so the OH number should be 380 to 410 to produce stable rigid polyurethane foam. It is necessary to do so.

On the other hand, the mixed isocyanate composition reacted with the above mixed polyol composition consists of primary components.

(A) Polymethylene polyphenyl diisocyanate 5o
-60% by weight, and (B) sucrose lylene diisocyanate prepolymer - 40-50% by weight, and the average NCO% of this composition should be 32-34.

In the above mixed isocyanate composition, by using a mixture of component (A) and component (B) in the above blending ratio, fluidity can be improved without reducing demoldability, and the skeletal strength of the foam can be improved. It is possible to significantly improve low-temperature dimensional stability when the density is increased and the density is reduced. In addition, if the N00% of the mixed isocyanate composition is less than 32, the fluidity will decrease, and if it exceeds 34, the low-temperature dimensional stability will decrease. Necessary for manufacturing.

If each component of the polyol composition and the isocyanate composition reacted with the polyol composition deviates from the above-mentioned mixing ratio, the object of the present invention will not be achieved.

When considering foam density, thermal conductivity, low-temperature dimensional stability, demoldability, etc., it is most preferable to combine the following polyol composition and isocyanate composition.

Polyol composition (a) 50% by weight of a polyol obtained by adding propylene oxide and ethylene oxide to sucrose (b) 15% by weight of a polyol obtained by adding propylene oxide and ethylene oxide to propylene glycol (C) 15% by weight of a polyol obtained by adding propylene oxide and ethylene oxide to propylene glycol (C) Jetanolamine (d) 25% by weight of a polyol obtained by adding propylene oxide and ethylene oxide to tolylene diamine. An average OH number of the composition is 400°.

(A) Polymethylene polyphenyl diisocyanate-555
weight%, and (B) sucrose trilene diisocyanate prepolymer 45% by weight Average NCO% of the composition 33° Also, the reaction ratio of the polyol component and isocyanate component, the ratio of NGO of the isocyanate to OH of the polyol,
NGO/○H is preferably 1.00 to 1.20, and NGO
10H=1.10 is more preferred.

Rigid polyurethane foam is obtained by reacting the above polyol component and isocyanate component as basic raw materials in the presence of a blowing agent, a reaction catalyst, and a foam stabilizer.

As the blowing agent, water, a combination of water and carbon dioxide or a compound that generates carbon dioxide, or a fluorocarbon blowing agent are often used, but an inert gas such as air may also be used. As a fluorocarbon foaming agent,
For example, trichloromonofluoromethane, dichlorodifluoromethane, trichlorotrifluoroethane, dichlorotetrachloroethane, etc. can be preferably used. When a fluorocarbon blowing agent is used as a blowing agent, it is preferably used in an amount of 20 parts by weight or more, more preferably 30 to 60 parts by weight, based on 100 parts by weight of the polyol component.

In addition, when using water together, polyol component 1
Preferably 0.1 to 3 parts by weight are used per 00 parts by weight.

As the reaction catalyst used in the present invention, reaction catalysts typified by, for example, tetramethylhexamethylenediamine, trimethylaminoethylpiperazine, dimethylaminooxadecane, triethylenediamine, etc. can be preferably used. In particular, it is preferable to use a combination of tetramethylhexamethylene diamine and trimethylaminoethylpiperazine, preferably 1 to 6 parts by weight, more preferably 3 to 4 parts by weight, per 100 parts by weight of the polyol component.

As the foam stabilizer, commonly used organic silicone compounds, fluorine surfactants, etc. can be used. For example, the formula:
H4)b-(OC1Hs)c OCH3, Otsu is-(C
Hz )a - (OC2H4)b (OC3H5)c
-〇CH3, a is an integer of 3, b is an integer of 15 to 25, and C is an integer of 5 to 15, or an integer of O to 7, and y is an integer of 0 to 17, polyalkylene glycol silicone Block copolymers can be used. Among them, both Zi and b are -(CH2)3- (○C2H4) z. −(
OC3) is ) s OC)L3 and X is 2~
4, and when y is 12 to 14, a good balance between thermal conductivity and dimensional stability is achieved, which is particularly preferable.

The foam stabilizer is preferably used in an amount of 0.1 to 5 parts by weight per 100 parts by weight of the polyol component.

The composition for manufacturing rigid polyurethane foam may further contain commonly used additives such as flame retardants, fillers, reinforcing fibers, colorants, etc., if necessary.For rigid polyurethane foam, one-shot method and quasi-prepolymer method are used. , a prepolymer method, a spray method, and various other methods. Among these, the one-shot method is preferably used.

Further, the foaming may be carried out using a common foaming machine used in the industry, such as the IPU-30 model foaming machine manufactured by Plamato. Foaming conditions vary depending on the type of foaming machine, but usually the liquid temperature is 18-24℃ and the discharge pressure is 80-150kg/a.
#, discharge rate 15-30kg/min, mold temperature 35-45℃
is preferable, and more preferably a liquid temperature of 20°C and a discharge pressure of 10°C.
0 kg/a (, discharge rate 25 kg/min, mold temperature 40°C.

The rigid polyurethane foam obtained in this way is
The density is 20 kg/rn' or less in free foam density, especially 18
~19kg/rn', extremely low, and with a thermal conductivity of 14
, 5 X 10-3 kcal/m-h・℃ or less, especially 14.0XIO-" to 13.OXI〇-" kca
l/m-h・'c, the low-temperature dimensional change rate is below -3%, especially -1% or below, and the compressive strength is 0.
It is extremely excellent as a heat insulating material for refrigerators because it can maintain a temperature of 7 kg/d or more, especially 0.8 kg/at or more.

The rigid polyurethane foam of the present invention can also be effectively used as a heat insulating material or a heat insulating molded product for other electric machines, building structures, vehicles, etc.

The present invention will be explained in detail with reference to Examples, where "part r" and "1%" are by weight unless otherwise specified.

Example 1-3, Comparative Example 1-3゜100 parts of the polyol component having an average OH value of 380 to 410 as shown in Table 1 (where P○ = propylene oxide, EO = ethylene oxide, 1.5 to 3゜0 parts of water, As a foam stabilizer, a polyalkylene glycol silicone block copolymer of formula (I) (where X = 3, y = 13) (trade name: 5Z-
1628, manufactured by Nippon Unicar Co., Ltd.) 2 parts (However, Comparative Example 1.
In 2, 1.5 parts of 5Z-1610, manufactured by Hhon Unicar Co., Ltd. was used) The average NCO listed in Table 1 was used as the isocyanate component.
%32-34 (NC○10H=1.10), tetramethylhexamethylene diamine (trade name: Kaolizer No. 1, manufactured by Kao Soap Co., Ltd.) and trimethylaminoethylpiperazine (trade name: Catalyst 3 mixed with Kaorizer No. 8 (manufactured by Kao Soap Co., Ltd.) at a ratio of 2:1
．． 5 parts 1 35 to 46 parts of trichloromonofluoromethane (trade name: R-11, manufactured by DuPont) was used as a blowing agent, and foaming and curing was carried out.

The results are shown in Table 1. In addition, in Table 1, each physical property was investigated as follows.

Free foam density (ρ1): Internal dimensions 200X200X200
I, Density when foaming is performed in the mold of the material plywood (
kg/i).

Panel foam density (ρ2): Internal dimensions 400W x 6゜0LX
Density (kg/rn') when foaming is performed at a mold temperature of 40'C in a 35T++n material AQ (1) type.

Fluidity: the value of (ρ2)−(ρ1) described above.

Low-temperature dimensional stability: Rate of change in thickness when a panel form in the 400W x 600L x 35T area is left at -20°C for 24 hours.

Flyability: According to ASTM-C-421-61 method.

Thermal conductivity: Panel form of 200W x 200L x 50Twm was used at an average temperature of 2 using model 88 manufactured by Anacon.
Measured at 3.8°C.

Compressive strength: Strength when a 50φ×35Tnm foam is compressed by 10%.

Demolding time: The time from the start of injection to demolding.

As is clear from Table 1, 6% of the polyol obtained by adding propylene oxide and ethylene oxide to sucrose and 65% of the polyol obtained by adding propylene oxide and ethylene oxide to tolylene diamine.
In Comparative Example 1, in which polymethylene polyphenyl diisocyanate was combined with a polyol mixture containing rn
”1, which is inferior to the density targeted by the present invention.On the other hand, polyol 69% obtained by adding propylene oxide and ethylene oxide to sucrose and polyol 6 obtained by adding propylene oxide and ethylene oxide to tolylene diamine. In Comparative Examples 2 and 3, an isocyanate mixture containing 40% of the total isocyanate components was combined with a polyol mixture containing 40% of the total isocyanate components,
Although the free foam density is extremely low at 17.8 to 18.7 kg/-, the thermal conductivity is 14.7X10-' to 1
5゜7 x 10 = kcal/m-h·''c, which is high and undesirable.

On the other hand, in Examples 1 to 3, the free foam density was lower than 19 kg/rri, and the thermal conductivity was 13
．． 5X10-~13.7X10-”kcal/m-h・
It can be seen that the temperature is excellent. Furthermore, as in Example 2, when 45% of the total inocyanate component contains sucrose lylene diisocyanate prepolymer, the free foam density decreases to 18.5 kg/m3, and the fluidity improves (panel foam density The difference between the free foam density and the free foam density is 7.
．． The smallest value is 1 kg/rn', which is preferable. ) It can be seen that the panel foaming density is extremely low at 25°6 kg/m, and the most favorable effect can be obtained.

In the end, 1, as shown in Example 2, polyol 5 in which PO and EO were added to shoerose as a polyol component.
0%, 15% polyol made by adding PO and EO to propylene glycol, 10% polyol made by adding PO to jetanolamine, PO and EO added to tolylene diamine
The combination of a mixture of 25% polyol with added polyol and a mixture of 55% polymethylene polyphenyl diisocyanate and 45% sucrose trilene diisocyanate prepolymer as isocyanate components improves foam density, fluidity, low-temperature dimensional stability, and thermal conductivity. The balance of ratio, compressive strength, and demoldability was the best.

As shown in the examples above, by combining the polyol and incyanate, a rigid polyurethane foam with extremely low density and low thermal conductivity can be produced with good moldability.
Moreover, the form properties are the same as conventional ones (low-temperature dimensional stability -1).
% or less and compressive strength of 0.8 kg/alt or more). Furthermore, by lowering the density, the amount of heat generated by the urethane per unit volume can be suppressed, which reduces the foaming pressure and has the effect of shortening demolding time.

〔Effect of the invention〕

As described above, according to the present invention, the foam density is 20 kg/- or less in terms of free foam density, more preferably 18 to 19
The density can be extremely low as kg/rd, and the thermal conductivity is 14.
．． 5×1O-skca1/m-h・℃ or less, more preferably 13.0X10-” to 14.OX10-”kca
It can be maintained at l/m-h・℃. Therefore, the amount of heat insulating material used can be reduced by 10% or more compared to the conventional method, and a product with the same performance and quality as the conventional method can be obtained, resulting in a significant cost reduction.

Claims (1)

[Claims] 1. The polyol component and the isocyanate component are combined with a blowing agent,
In the method for producing rigid polyurethane foam, which is reacted in the presence of a reaction catalyst and a foam stabilizer, the polyol component includes (a) 47 to 53% by weight of a polyol obtained by adding propylene oxide and ethylene oxide to sucrose; (b) ) Polyols obtained by adding propylene oxide and ethylene oxide to propylene glycol 13~
17% by weight, (c) 8-12% by weight of a polyol obtained by adding propylene oxide to diethanolamine, and (d) 23-27% of a polyol obtained by adding propylene oxide and ethylene oxide to tolylene diamine.
% by weight of a polyol mixture, the average O of that polyol mixture is
(A) polymethylene polyphenyl diisocyanate 50
~60% by weight, and (B) sucrose trilene diisocyanate prepolymer 40 to 50% by weight, and the average NCO% of the isocyanate mixture is 32 to 34. Method of manufacturing polyurethane foam.