JPH0454688B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing rigid polyurethane foams using novel polyether polyols (hereinafter simply referred to as novel polyols). Conventionally, polyethers for rigid polyurethane foams include sucrose, sorbitol, pentaerythritol, glycerin, ethylenediamine, etc. with alkylene oxide added thereto.
These polyethers have poor compatibility with polyisocyanates and chlorofluorocarbons, and it often occurs that a good foam cannot be obtained. To improve this, polyethers using aromatic diamines such as diaminodiphenylmethane have been used. Among them, polyether obtained by adding propylene oxide to a mixture of 2,4-diaminotoluene and 2,6-diaminotoluene, which is commonly used, has good compatibility with polyisocyanates and CFCs. Although a fine cell foam can be produced using this method, the disadvantage is that the viscosity is very high and workability is poor, and the cost of raw materials is high. Furthermore, the polyol obtained by adding alkylene oxide to a mixture of 2,3-diaminotoluene and 3,4-diaminotoluene has a high viscosity and poor compatibility with CFC blowing agents, and when injected into panels etc. Since the liquid spreads poorly, it is necessary to increase the amount of injection, and the resulting foam has disadvantages such as high flyability and rapid deterioration under moist heat and high temperature. Furthermore, addition polymerization of ethylene oxide to increase the hydroxyl value or lower the viscosity caused problems such as scorch formation and microcracks inside the foam. The present inventors conducted various studies in view of these drawbacks, and as a result, arrived at the present invention. That is, the present invention is as follows. In producing a rigid polyurethane foam by reacting an organic polyisocyanate with an active hydrogen-containing compound in the presence of a catalyst, a blowing agent, and a foam stabilizer, 2,4-diaminotoluene and/or 2,6 as a polyether polyol are used. -Diaminotoluene 20~
Addition polymerization of alkylene oxide to a mixture consisting of 45 parts by weight, 20 to 45 parts by weight of 2,3-diaminotoluene and/or 3,4-diaminotoluene, and 60 to 10 parts by weight of a compound having 2 to 4 active hydrogen atoms. A method for producing a rigid polyurethane foam, characterized by using a polyol having a hydroxyl value of 300 to 550 obtained by The weight ratio of the total amount of diaminotoluene to the compound having active hydrogen used in the present invention is preferably 40/60 to 90/10. If the blending ratio of diaminotoluene is less than 40 to 60, the compatibility of the new polyol with crude diphenylmethane diisocyanate (hereinafter referred to as crude MDC) will be poor and the liquid spread will be poor. If the ratio is 90/10 or more, the viscosity of the polyol becomes high, which impairs workability, increases flyability, and lengthens the demolding time of the molded foam. The ratio of the amount of 2,4- and/or 2,6-diaminotoluene to the amount of 2,3- and/or 3,4-diaminotoluene is from 20/45 to 45/20, preferably from 30/45 to It's 40/20. This ratio is
If the ratio is smaller than 20/45, scorch will easily occur when producing urethane foam, and if the ratio is larger than 45/20, the viscosity of the polyol will increase, reducing workability and increasing the price. . Examples of compounds having 2 to 4 active hydrogen atoms used in the present invention include water, ethylene glycol, propylene glycol, glycerin, polyhydric alcohols such as trimethylolpropane and bentaerythritol, monoethanolamine, dipropanolamine, and triethanol. These include alkanolamines such as amines and ethylenediamine. In the present invention, ethylene oxide (hereinafter simply referred to as EO) and propylene oxide (hereinafter referred to as PO) are generally used as alkylene oxides (hereinafter, when these oxides are collectively referred to as alkylene oxide), EO is a polyol. It is preferable to use it because it reduces the viscosity and improves the elongation of the liquid. Although the method and order of addition of the alkylene oxide are not limited, preferably, the alkylene oxide is added to the base material without a catalyst,
After adding the catalyst, alkylene oxide is further added,
Add an amount such that the desired polyether has a hydroxyl value of 300 to 550. Also, regarding the addition of EO,
There are no particular restrictions on the addition position and addition method, but it is preferable to add the EO and PO into an alkylene oxide to be added without a catalyst, and either block addition or random addition of EO and PO may be used. If the hydroxyl value of the present invention is lower than 300, the obtained foam will shrink at low temperatures, and if it is higher than 550, the viscosity of the polyol will increase and scorch will easily occur. Polyisocyanates used when producing polyurethane foams that are harder than polyether are conventionally known and are not limited, but include, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and 2,4-tolylene diisocyanate. Conventionally known modification modified with a mixture of 2,6-tolylene diisocyanate with an isomer ratio (weight ratio) of 80/20 or 65/35, crude tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, carbodiimide, etc. 4,4'-diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, o
-, m- or p-xylylene diisocyanate,
Examples include hexamethylene diisocyanate, dimers and trimers thereof, and polyisocyanates partially modified with known low-molecular polyols or known polyethers, which may be used alone or in combination. The amount of polyisocyanate used is such that NCO/H (active hydrogen) is 0.7 to 1.4 (equivalent ratio). As the foaming aid, a foaming catalyst, a foaming agent, and a foam stabilizer are used. As the blowing catalyst, conventionally known amine compounds, organic tin compounds, etc. are used, and as the blowing agent, water, trichloromonofluoromethane, dichlorodifluoromethane, dichlorotetrafluoroethane, monochlorofluoromethane, methylene chloride, etc. are used. It will be done. As the foam stabilizer, a conventionally known silicone foam stabilizer is used. When a rigid polyurethane foam is obtained from the polyether of the present invention, foaming can be carried out by a one-shot method, a prepolymer method, or a semi-prepolymer method. The polyether of the present invention has a relatively low viscosity;
It has good liquid flowability and good compatibility with fluorocarbons and polyisocyanates, and the resulting foam has good scorch resistance regardless of the hydroxyl value and EO content, has low fryability, and is resistant to wet heat deterioration. Good physical properties with little deterioration at high temperatures can be obtained. The polyether of the present invention is useful as a raw material for rigid polyurethane foam in a wide range of fields such as electric refrigerators, freezers, cold storage boxes, cold and heat insulation materials for buildings, sound absorbing materials, synthetic wood, and structural materials. Next, the present invention will be specifically explained with reference to Production Examples, Comparative Production Examples, Examples, and Comparative Examples, but the present invention is not limited to these in any way (hereinafter, % indicates weight %). Production Example 1 3.5 kg of 2,3- and 3,4-diaminotoluene mixture (hereinafter referred to as o-TDA), 3.5 kg of 2,4- and 2,6-diaminotoluene mixture (hereinafter referred to as m-
TDA) 3.5Kg, triethanolamine 3.0Kg
was placed in a reaction vessel and the mixture was heated and melted. First, 66.5 kg of PO was added, and then 66.6 kg of EO was added.
Added. Next, add caustic potash to the finished amount at 0.4%.
After the reaction temperature was raised to 110°C, 149.5 kg of PO was further added. After the reaction was completed, it was neutralized with phosphoric acid, the precipitated crystals were filtered, and the filtrate was used as a product. The obtained polyol (1) has a hydroxyl value of 40 and a viscosity of
It was 4600cps/25℃. Production Example 2 The same base material as in Production Example 1 was placed in a reaction vessel, and after melting, first 6.81Kg of EO was added, then 6.6Kg of PO,
Next, after adding 0.2% by weight of caustic potash to the finished amount,
The reaction temperature was raised to 110°C, and 10.25 kg of PO was added. The reaction solution was then treated in the same manner as in Production Example 1 to obtain polyol (2) having a hydroxyl value of 455 and a viscosity of 6500 cps/25°C. Production Example 3 6.11Kg of EO and 7.80Kg of PO were added to a mixture of 3.5Kg of m-TDA, 3.5Kg of o-TDA, and 3.0Kg of triethanolamine in the same manner as in Production Example 1.
After adding 0.2% of caustic potassium, 5.0 kg of PO was added to obtain a polyol (3) having a hydroxyl value of 540 and a viscosity of 14,600 cps/25°C. Production Example 4 9.84Kg of PO and 5.2Kg of EO were added to a mixture of 3.5Kg of m-TDA, 4.5Kg of o-TDA, and 2.0Kg of triethanolamine in the same manner as in Production Example 1. After adding 0.3% caustic potash, 15.2Kg of PO was added,
Polyol (4) with hydroxyl value 401 and viscosity 6800cps/25℃
I got it. Production example 5 m-TDA4.5Kg, o-TDA2.5Kg, glycerin
PO was added to 3.0 kg of the mixture in the same manner as in Production Example 1.
6.32Kg and 4.92Kg of EO were added. Caustic potash 0.2
%, 20.4 kg of PO was added to obtain a polyol (5) with a hydroxyl value of 405 and a viscosity of 12,500 cps/25°C. Production example 6 m-TDA3.5Kg, o-TDA3.5Kg, glycerin
EO was applied to 33.0 kg of the mixture in the same manner as Production Example 1.
2.52Kg and 8.84Kg of PO were added. Caustic potash 0.2
%, 19.33 kg of PO was added to obtain a polyol (6) with a hydroxyl value of 420 and a viscosity of 9200 cps/25°C. Comparative Production Example 1 5.1Kg of EO was added to a mixture of 7.0Kg of o-TDA and 3.0Kg of triethanolamine in the same manner as Production Example 1.
Added. After adding 0.2% caustic potash, PO
Added 17.74Kg, hydroxyl value 450, viscosity 8000cps/
A polyol (comparison 1) at 25°C was obtained. Comparative Production Example 2 10 kg of o-TDA was heated to 80°C, and 7.21 kg of EO was added. After adding 0.4% of caustic potash to the finished amount, the temperature was raised to 100℃, and 16.06 kg of PO was added.
After the reaction, it was treated in the same manner as in Production Example 1, and the hydroxyl value was 410.
A polyol (comparison 2) with a viscosity of 8200 cps/25°C was obtained. Examples 1 to 6 and Comparative Examples 1 and 2 500g each of polyols (1) to (6) and (Comparison 1) to (Comparison 2) produced as above were taken, and PO was added to the sucrose amine mixture. The hydroxyl value obtained by
450 and 500 g of polyol with a viscosity of 44,000 cps/25°C. To these polyol mixtures were added trischloroethyl phosphate (TCEP) flame retardant, water, tetramethylhexanediamine (TMHD) catalyst, silicone foam stabilizer, Freon-11 blowing agent, and crude diphenylmethane in the amounts shown in Table 1. It was sequentially mixed with diisocyanate (MDI-CR). Further, 330 g of the above mixed stock solution was injected into the bottom of the vertical surface of an inverted L-shaped panel having a thickness of 330 mm, a width of 350 mm, and a side length of 500 mm. The stock solution foams inside the panel,
After rising in the vertical plane of the panel, it spread and hardened in the horizontal plane. The liquid elongation was compared based on the distance the foam traveled. Separately, a box with a length of 400 mm, a width of 200 mm, and a height of 400 mm is heated to 45°C.
The above-mentioned mixed stock solution was poured into the solution and foamed. The foamed and cured foam was allowed to stand overnight, then cut at the center, and the degree of scorch in the foam core was examined. The liquid elongation and scorch conditions of each mixed stock solution are shown in Table 1, and it is clear that the polyol of the present invention is excellent in terms of liquid elongation and scorch. 【table】

Claims (1)

[Claims] 1. In producing a rigid polyurethane foam by reacting an organic polyisocyanate and an active hydrogen-containing compound in the presence of a catalyst, a blowing agent, and a foam stabilizer,
2,4-diaminotoluene and/or 2,6-diaminotoluene20 as polyether polyol
~4 5 parts by weight, 2,3-diaminotoluene and/
or 3,4-diaminotoluene, 20 to 45 parts by weight and 60 to 1 compound having 2 to 4 active hydrogen atoms
A method for producing a rigid polyurethane foam, comprising using a polyol having a hydroxyl value of 300 to 550 obtained by addition polymerizing an alkylene oxide to a mixture consisting of 0 parts by weight.