JPS599573B2 - Manufacturing method of rigid polyurethane foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing rigid polyurethane foam.

[Technical background of the invention and its problems]

Conventionally, closed-cell rigid polyurethane foams have been widely used as heat insulators and cold insulators.

In the production of rigid polyurethane foam, fluorotrichloromethane (hereinafter referred to as Freon-1) is used as a blowing agent.
It is called 1.

) Alternatively, dichlorodifluoromethane (hereinafter referred to as Freon-12) C02 produced by the reaction of water and isocyanate is used. The method of foaming by adding Freon-11 and Freon-12 and water as necessary is called the frothing method, and when the foaming stock solution is discharged from the foaming machine, it comes out in the form of a cream, so it is not heat-insulating. The liquid flow rate in the box is small, and
Since the foaming ratio of the creamy liquid at the time of discharge is small, the compressive strength ratio between the foaming direction and the direction perpendicular to the foaming direction is small, that is, the foam has little anisotropy.

Furthermore, since Freon-12 is used, the internal pressure of the foam increases. Both of these characteristics combine to reduce foam shrinkage upon cooling. but,
In this floss method, since Freon-12 is used, a large amount of rice board (rice-grain-sized bubbles) is generated in the foam, resulting in uneven foam bubbles and a thermal conductivity of 0.017 kcal/m. In addition, in the floss method using high-pressure foaming, since the two liquids are mixed only once when they collide, Freon-12 is dispersed during discharge, making it possible to reduce the density to 25 kg/d or less. It has the disadvantage of being difficult.・ [Objective of the Invention] The present invention improves the drawbacks of the conventional manufacturing method described above, and makes it possible to manufacture rigid polyurethane foam with low thermal conductivity and low density while maintaining the characteristics of the conventional flossing method. For the purpose of providing law.

[Summary of the invention]

The present invention is characterized in that: )-(a) dichlorotetrafluoroethane (hereinafter referred to as Freon-114);

) 2 to 80% by weight and (b) 20 to 98% by weight of one or more compounds selected from the group consisting of Freon-11, Freon-12 and water. This is a method of manufacturing foam.

In the present invention, Freon-114 refers to 1,1-dichloro-1,2,2,2-tetrafluoroethane or 1,2-dichloro-1,1,2,2-tetrafluoroethane or their It is a mixture. Freon 11
The amount of 4 used is 2 to 80% by weight, preferably 5 to 30% by weight, based on the total blowing agent. Isocyanates used in the present invention include 4,4'-diphenylmethane diisocyanate (MDI), toluene diisocyanate (
TDI), hexamethylene diisocyanate, and many others, and their NCO content is generally 25 to 40%.
are used.

Examples of polyether polyols include those of Shugar type, glycerin type, and amine type, among which those having a hydroxyl value (OH) of 350 to 600 are preferred. Examples of catalysts include amine catalysts such as triethylamine and triethylenediamine, and metal salts such as potassium oleate, stannous chloride, stannic chloride, and butyl tin dilaurate, which depend on the type of isocyanate and polyether polyol used. Therefore, it is preferable to use them in appropriate combinations. The total amount of blowing agent used is 10
0 parts by weight, it may be 30 to 75 parts by weight, and 4 parts by weight.
It is preferably 0 to 60 parts by weight. In addition, if the content of Freon-114 is less than 2% by weight based on the total blowing agent, the characteristics of the floss method cannot be utilized because cream-like formation is small, and if it exceeds 80% by weight, compatibility with polyether polyol may occur. Solubility decreases, separation occurs, rice boards appear in the polyurethane foam, and bubbles become uneven. [Examples of the Invention] Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Examples 1 to 8 Crude MDI (NCO%: 3
1%) 120 parts by weight as polyether polyol,
Shuyuga series polyether polyol (0HV:470)
100 parts by weight, 2 parts by weight of an amine catalyst as a catalyst, 2 parts by weight of a silicone foam stabilizer as a foam stabilizer, 0.5 parts by weight of water as a blowing agent, and Freon-11 and Freon-1
By changing the blending ratio of 14, the density of polyurethane foam was 2.
5~26VS1! /M3, Freon-11
A mixture of and Freon-114 was added and foamed using a high-pressure foaming machine.

The results are shown in Table 1. Examples 9 to 14 Crude MDI (NCO%: 3
1%) 145 parts by weight as polyether polyol,
Shuyuga series polyether polyol (0HV:470)
100 parts by weight, 0.1 parts by weight of tin catalyst and 2 parts by weight of amine catalyst as catalyst, 2 parts by weight of silicone foam stabilizer as foam stabilizer, blending ratio (weight ratio) as blowing agent, 80 parts by weight.
The amount of the mixture of Freon-11 and Freon-114 in Example 20 was varied and foamed using a high-pressure foaming machine.

The results are shown in Table 2. Comparative Examples 1 to 7 In Examples 1 to 8, instead of Freon-114,
Freon-112 was used, and the other procedures were the same.

The results are shown in Table 3. Example 15 and Comparative Example 8~
10 Examples 1 to 8 were carried out in the same manner except that the mixture shown below was used as the blowing agent.

(a) Freon-1 1150 parts by weight, Freon-1 1143 parts by weight
0 parts by weight and 20 parts by weight of water (Example 15) (b) 1170 parts by weight of Freon-1 and 30 parts by weight of water (Comparative Example 8) (c
) Freon-111440 parts by weight and trichlorotrifluoroethane (hereinafter referred to as Freon-113).

) 60 parts by weight (Comparative Example 9) (d) 1,140 parts by weight of Freon-1, 11,420 parts by weight of Freon-1, and 11 parts by weight of Freon-1
340 parts by weight (Comparative Example 10) The thermal conductivity at each temperature was measured for each of the obtained polyurethane foams, and the results are shown in the figure.

〔Effect of the invention〕

According to the manufacturing method of the present invention, even if a high-pressure foaming machine is used, the foaming stock solution at the time of discharge becomes cream-like, and a polyurethane foam with uniform foam bubbles with few rice boards can be obtained, and the density is low. At about 20 kg/I, one with a low thermal conductivity of 0.014 kcal/m-Hr·°C or less can be obtained.

That is, it is possible to provide a rigid polyurethane foam that has low thermal conductivity and low density while taking advantage of the characteristics of the floss method. In particular, the rigid polyurethane foam obtained by the present invention has extremely low thermal conductivity in the low temperature range compared to conventional foams, making it ideal as a heat insulating material for refrigerators and freezers.

BRIEF DESCRIPTION OF THE DRAWINGS The figure shows the results of Example 15 and Comparative Examples 8 to 10.

Claims (1)

[Claims] 1(a) Dichlorotetrafluoroethane 2-80% by weight
and (b) production of a rigid polyurethane foam characterized by using a blowing agent consisting of 20 to 98% by weight of one or more compounds selected from the group consisting of fluorotrichloromethane, dichlorodifluoromethane, and water. Law.