JPS63264616A - Preparation of phenol-modified polyurethane foam - Google Patents

Abstract

PURPOSE:To prepare the title substance which is excellent in fire retardance and heat insulation, by mixing a hydroxyalkylated polyol of a specified novolak type phenol resin and polyether polyol and/or polyester polyol with polyisocyanate and a catalyst and foaming the mixture. CONSTITUTION:A novolak type phenol resin (a) having a number-average MW of 350-650, a weight-average MW of 500-1,200 and a dispersion degree index of at most 2.0 and contg. at most 25wt.% of free phenol, which is obtained by reacting phenols with an aldehyde substance in the presence of an acid catalyst, is admixed with alkylene oxide (b) in an amt. of 1-3.8mol. per one OH group to give an hydroxyalkylated polyol of a novolak type phenol resin A having an OH group value of 50-350mgKOH/g. The ingredient A is blended with polyether polyol and/or polyester polyol B in a wt. ratio A/B=20-80/80-20, and the mixture is blended with polyisocyanate C and with a catalyst, a foaming agent and a foam stabilizer D.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a rigid polyurethane foam that has good flame retardancy and excellent heat insulation properties.

[Prior art]

Rigid polyurethane foams are widely used in industry as insulation materials because they generally have excellent water resistance, strength, and adhesion to surface materials. However, it has a drawback that its use as a building material is limited because it has inferior heat resistance compared to phenolic resin foam. Attempts to improve flame retardancy by modifying polyols for rigid polyurethane foams with phenolic resins have been studied for some time. A method of using an oxyalkylated product obtained by adding alkylene oxide to the hydroxyl group of a novolak type phenol resin as a polyol is described in Japanese Patent Publication No. 53-44515 and Japanese Patent Publication No. 54-32.
679, Special Publication No. 57-5245, Special Publication No. 46-379
7, Special Publication No. 46-21228, Special Publication No. 47-1991
1, JP-A-51-105394, JP-A-53-597
No. 92, etc., but even when these were used, a rigid polyurethane foam with excellent flame retardancy comparable to that of phenolic resin foam could not be obtained.

(Object of the Invention) The present inventors have completed the present invention as a result of various researches, particularly on novolac type phenolic resins, in an attempt to obtain a rigid polyurethane foam with greatly improved flame retardance compared to the conventional method. This is what led to this. The objective is to provide a method for producing a phenol-modified polyurethane foam that has excellent flame retardancy and good heat insulation properties.

[Structure of the invention]

The present invention provides a method for manufacturing a rigid polyurethane foam by foaming a foaming material consisting of a polyol, a polyisocyanate, a catalyst, a blowing agent, and a foam stabilizer, in which the polyol has a number average molecular ffi (Mn) of 350 to 650 and a weight average molecular weight of (MW) of 500 to 1200, a dispersity index (Mw/M n > 2.0 or less, and free phenol of 2.5% by weight or less), alkylene oxide per water II 1~
The hydroxyl value obtained by adding 3.8 moles is 50 to 350
It is characterized by the use of a mixture of a novolak type phenol resin oxyalkylated polyol (^) having mgKOH/'j, and a polyether polyol (B) and/or a polyester polyol (C).

The novolac type phenolic resin used in the present invention is a thermoplastic condensation product obtained by reacting one or more phenols with one or more aldehyde substances using an acid catalyst. Phenols used as raw materials for phenolic resin include phenol, cresono 1,
xylenol, resorcinol, hydroquinone, para-t
-butylphenol, etc., and aldehyde substances include formalin, paraformaldehyde, acetaldehyde, etc. Examples of the acid catalyst include inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, and organic acids such as formic acid, oxalic acid, acetic acid, and p-toluenesulfonic acid.

The molar ratio of phenols and aldehydes is usually 1:0.
．． After charging the mixture into a reaction vessel at a ratio of 54 to 0.74, an acid catalyst is added and mixed. 60 at 95-105℃ after gradual heating
Reflux reaction is carried out for about 120 minutes. Next, a vacuum dehydration reaction is carried out, and when the internal temperature reaches 190 to 220'C, the pot is taken out and cooled.

The molar ratio of aldehyde substances to phenols is 0.5
When it is less than 4, the number average molecular weight tends to be less than 350 and the weight average molecular weight tends to be less than 500. A foam obtained using an oxyalkylated product synthesized using this novolak type phenolic resin has low dimensional stability. When the molar ratio exceeds 0.74, the number average molecular weight tends to exceed 650, the dispersity index exceeds 2.0, and the weight average molecular weight tends to exceed 1,200. A foam obtained using an oxyalkylated product synthesized using this novolak type phenolic resin has poor flame retardancy.

If the reflux reaction exceeds 120 minutes, the dispersity index tends to exceed 2.0. When the internal temperature at the end point of the vacuum dehydration reaction is less than 190°C, the amount of free phenol exceeds 2.5% by weight.

If free phenol exceeds 2.5% by weight, the oxyalkylation reaction becomes non-uniform. Normally, 1 q of the novolac type phenol resin in the present invention is obtained under such reaction conditions.

The novolac type phenol resin thus obtained is reacted with an alkylene oxide such as ethylene oxide or propylene oxide in the presence of an alkali metal hydroxide catalyst such as sodium hydroxide at a reaction temperature of 80 to 160°C, After adding 1 to 3.8 moles of alkylene oxide to water Ml of phenol resin, it is neutralized with an acidic substance, and the resulting salt is filtered off to obtain an oxyalkylated novolac type phenol resin (A). The hydroxyl value of the oxyalkylated product (A) obtained at this time is 50 to 350.
Let mffKOH/y.

An oxyalkylated product obtained by adding less than 1 mole of alkylene oxide per hydroxyl group has poor workability during foaming and low dimensional stability of the foam. On the other hand, 3
．． Oxyalkylated products added in excess of 8 moles have poor flame retardant properties.

If the hydroxyl value is less than 5 qmg KOH/9, the resulting foam will have low dimensional stability, and if it exceeds 350 #1 g KOH/g, the foam will become more brittle and have lower flame retardancy.

Polyether polyol (B) used in the present invention
is commonly used in the production of rigid polyurethane foams, and is a combination of polyhydric alcohols such as diols, triols, tetraols, pentols, hexols, and octatools, and compounds with active hydrogens of divalent or higher valences, such as polyamines, as well as ethylene oxide and Polyoxypropylene glycol (PPG) with propylene oxide added
, polyoxypropylene, oxyethylene glycol, polytetramethylene glycol (PTMG), and polymer polyols.

Polyester polyol (C) used in the present invention
These are commonly used in the production of rigid polyurethane foams, and include polyethylene terephthalate polyols, adipate polyols, polycaprolactone polyols, and polycarbonate polyols.

The blending ratio of the polyol is (A)/((B) in weight%.
and/or (C))=20-80/80-20. The blending ratio of (A) is 80
However, if it exceeds 20 parts m%, the thermal insulation properties of the foam will be poor, while if it is less than 20 parts m%, the foam's
decreases. Moreover, these polyols can also be used after being prepolymerized by a conventional method.

The polyisocyanates in the present invention are those commonly used in the production of rigid polyurethane foams, and include tolylene diisocyanate (TD I), diphenylmethane diisocyanate (pure MDI), polymethylene polyphenyl polyisocyanate (crude MDI), and hexamethylene diisocyanate (crude MDI). HDI) and other organic polyisocyanates. The amount of polyisocyanate used is 2≦NCo/○H≦15 in terms of equivalent ratio.

The catalysts used in the present invention are those commonly used in the production of rigid polyurethane foams, such as alkali metal salts of carboxylic acids, tin salts of carboxylic acids, and fatty acid group tertiary amines. As the blowing agent, blowing agents generally used for rigid polyurethane foams, such as monofluorotrichloromethane and difluorodichloromethane, can be used. As the foam stabilizer, commonly known silicone surfactants are used. In addition, various additives such as flame retardants, plasticizers, colorants, etc. that are commonly used in the production of rigid polyurethane foams can also be used in combination.

[Effects of the Invention] The foam obtained by the present invention has particularly excellent flame retardancy and heat insulation properties, and is mainly used for building materials such as heat insulating materials and structural materials.

(Examples) The present invention will be explained below by giving specific examples, but the present invention is not limited only to these Examples. In addition, all "parts" and "%" in Examples and Comparative Examples are "parts by weight."
and “% by weight”.

Example-1 1000 parts of phenol and 475 parts of 37% formalin (formaldehyde/phenol molar ratio -0.55) were charged into a reaction vessel equipped with a reflux device, and then 15 parts of oxalic acid was added and mixed. The mixture was gradually heated and a far current reaction was performed at 95 to 100°C for 90 minutes. Then, a vacuum was applied to dehydrate and heat the mixture, and when the internal temperature reached 210° C., it was taken out of the pot and cooled. White solid, free phenol 0.9%, number average molecule ff136L weight average molecule ff1630, dispersity index 1
．． 930 parts of Novolac type phenolic resin No. 75 was obtained.

After charging 500 parts of this novolac type phenolic resin into an autoclave, it was heated to 130'C and 500 parts of sodium hydroxide was added.
part was added and mixed. Then propylene oxide 680
After gradually adding 2.7 moles per hydroxyl group,
Time reacted. The reaction product was neutralized with acetic acid and filtered under reduced pressure to obtain an oxyalkylated polyol (A) having a hydroxyl value of 280 my and 0.11 parts g.

Next, 150 parts of this oxyalkylated polyol (A) was added to polyether polyol (B) (rsBυ polyol 0
474J, manufactured by Sumitomo Bayer Urethane ■) 20 parts, polyester polyol YT-350, Asahi Denka Kogyo (l wooden) 30 parts, foam stabilizer rS11-193 manufactured by Toray Silicon ■> 4 parts, potassium octylate 6 parts, Freon- 11.80 parts and flame retardant CEP.

10 parts were adjusted to 20°C and mixed uniformly to obtain a premix.

Next, 200 copies of this premix and rough y ) IDI <
After mixing 320 parts of "44V 20J Sumitomo Bayer Urethane ■" with a foam injection machine,
The mixture was poured into a 250rrvn aluminum mold and foamed.

Then, the mixture was heated at 80° C. for 15 minutes to cure it and then fired to obtain a polyurethane foam.

Example-2 1000 parts of phenol and 535 parts of 37% formalin (formaldehyde/phenol molar ratio = 0.62) were charged into a reaction vessel equipped with a reflux device, and then 3 parts of 20% hydrochloric acid aqueous solution was added and mixed. Gradually heat to 95-100℃9
The reflux reaction was carried out for 0 minutes. Next, a vacuum was applied to dehydrate the container and the container was heated, and when the internal temperature reached 195.degree. C., the container was taken out of the pot and cooled. White solid, free phenol 1.2%,
970 parts of a novolac type phenolic resin having a number average molecular weight of 453, a weight average molecular weight of 725, and a dispersity index of 1.60 was obtained.

After charging 500 parts of this novolak type phenol resin into an autoclave, it was heated to 130°C, and 5 parts of potassium hydroxide was added and mixed. Then, after gradually adding 695 parts of ethylene oxylide (3.5 moles per hydroxyl group), 1.
The reaction took place for 5 hours. The reaction product was neutralized with acetic acid and then filtered under reduced pressure to obtain an oxyalkylated polyol (A) having a hydroxyl value of 320 #IgKOH/g.

Next, 120 parts of oxyalkylated polyol (A) was added to polyether polyol (B) ("sBU polyol 0
474" manufactured by Sumitomo Bayer Urethane ■) 80 parts, foam stabilizer 4
1 part, 4 parts of dimethylcyclohexylamine, 1 part of Freon
1.60 parts and 10 parts of flame retardant TCEP at 20°C
The mixture was adjusted to 9 and mixed uniformly to obtain a premix.

Next, this premix was foamed and cured in exactly the same manner as in Example-1 to obtain a foam.

Example 3 1000 parts of phenol and 604 parts of 37% formalin (formaldehyde/phenol molar ratio = 0.70) were charged into a reaction vessel equipped with a reflux device, and then 10 parts of oxalic acid was added and mixed. The mixture was gradually heated and a reflux reaction was carried out at 95 to 100°C for 90 minutes. Next, a vacuum was applied to dehydrate the container and the container was heated. When the internal temperature reached 210.degree. C., the container was taken out of the pot and cooled. White solid, free phenol 0.6%, number average molecular weight 507, weight average molecular weight 819, dispersity index 1.62
955 parts of novolac type phenolic resin were obtained.

500 parts of this novolac type phenol resin was charged into an autoclave, heated to 130°C, and 5 parts of sodium hydroxide was added and mixed. Then, 560 parts of propylene oxide (2.2 mol per hydroxyl group) was gradually added, and the mixture was reacted for 2 hours. The reaction product was neutralized with acetic acid, reduced, and separated by pressure filtration to obtain an oxyalkylated polyol (A) having a hydroxyl value of 155 my and OH/g.

Next, to 120 parts of this oxyalkylated polyol (A), 30 parts of polyether polyol (B) (SBU Polyol 0474J, manufactured by Sumitomo Bayer Urethane ■), polyester polyol (C) (r Adeka New Ace YT-350, Asahi (manufactured by Denka Kogyo ■) to 50 parts of foam stabilizer (1
A premix was obtained by uniformly mixing 4 parts of "5H-193J (manufactured by Toray Silicone), 6 parts of potassium octylate, 11.80 parts of Freon, and 10 parts of flame retardant TCEP at 20°C.

Next, 200 parts of this premix and crude HDI (r
44V20J (manufactured by Sumitomo Bayer Urethane ■) and 400 parts using a foam injection machine.
The mixture was injected into a 2.50-sized aluminum mold and foamed.

The mixture was then heated at 80° C. for 15 minutes to cure and then molded to obtain a polyurethane foam.

Comparative Example-1 200 parts of the oxyalkylated polyol (A) obtained in Example 1, 4 parts of foam stabilizer, 6 parts of potassium octylate, Freon, -11,8 parts, and flame retardant TCEP.

10 parts were adjusted to 20°C and mixed uniformly to obtain a premix.

Next, this premix was foamed and cured in exactly the same manner as in Example 1 to form a foot.

Comparative Example-2 200 parts of the oxyalkylated polyol (A) obtained in Example-2, 4 parts of foam stabilizer, 4 parts of dimethylsiloxhexylamine, parts of Freon-11,5Q, and flame retardant T
A premix was obtained by uniformly mixing 10 parts of CEP at 20°C.

Next, a foamed and hardened foam was obtained from this premix in exactly the same manner as in Example-1.

Comparative Example-3 1000 parts of phenol and 690 parts of 37% formalin (formaldehyde/phenol molar ratio = 0.80) were charged into a reaction vessel equipped with a reflux device, and then 15 parts of oxalic acid was added and mixed. The mixture was gradually heated and refluxed at 95 to 100°C for 90 minutes. Next, a vacuum was applied to perform dehydration and heating, and when the internal temperature reached 170° C., the pot was taken out and cooled. White solid, free phenol 3.1%, number average molecular weight 573, weight average molecular weight 11237, dispersity index 2.16
985 parts of novolac type phenolic resin were obtained.

Example-1 using this novolac type phenolic resin
Oxyalkylated polyol (
A) was obtained.

Next, to 192 parts of this oxyalkylated polyol (A), 8 parts of polyether polyol (B) (rsBU polyol 0474J), 4 parts of foam stabilizer, 6 parts of potassium octylate, 11.80 parts of Freon, and the flame retardant TCE.
0 parts of PI was adjusted to 20'C and mixed uniformly to obtain a premix.

This premix was then foamed and cured in exactly the same manner as in Example 1 to obtain a foam.

Comparative Example-4 1000 parts of phenol and 431 parts of 37% formalin (formaldehyde/phenol molar ratio = 0.50) were charged into a reaction vessel equipped with a reflux device, and then 15 parts of oxalic acid was added and mixed. The mixture was gradually heated and a reflux reaction was carried out at 95 to 100°C for 90 minutes. Next, a vacuum was applied to dehydrate the container and the container was heated, and when the internal temperature reached 210.degree. C., the container was taken out of the pot and cooled. 880 parts of a novolac type phenolic resin was obtained in the form of a white solid, containing 0.5% free phenol, a number average molecular weight of 224, a small average molecular weight of 324, and a dispersity index of 1.45.

Example-1 using this novolac type phenolic resin
Oxyalkylated polyol (
A) was obtained.

Next, to 8 parts of this oxyalkylated polyol (A), polyether polyol (B) (rsBU polyol 0
474''> 100 parts, polyester polyol (C)
([ADEKA NEW ACE YT-350> 92 parts, 4 parts of foam stabilizer, 4 parts of dimethylcyclohexylamine, 11.60 parts of Freon, and 10 parts of flame retardant TCEP to 20 parts)
℃ and mixed uniformly to obtain a premix.

This premix was then foamed and cured in the same manner as in Example 1 to obtain a foam.

Examples-1, -2 and Comparative Examples-1, -2, -3, -4
Table 1 shows the practical characteristics of each of the foams obtained.

Claims (1)

[Claims] Number average molecular weight (Mn) is 350 to 650, weight average molecular weight (Mw) is 500 to 1200, and dispersity index (Mw/Mn) is 2.0 or less, and free phenol is 2.5% by weight or less. The hydroxyl value obtained by adding 1 to 3.8 moles of alkylene oxide per hydroxyl group to the novolac type phenol resin is 50 to 350 mgKO.
Oxyalkylated polyol (A) of novolac type phenolic resin with H/g and polyether polyol (
A method for producing a phenol-modified polyurethane foam, which comprises mixing B) and/or the polyester polyol (C) with a polyisocyanate, a catalyst, a blowing agent, and a foam stabilizer and foaming the mixture.