JPH02245014A - Production of rigid polyurethane foam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for producing rigid polyurethane foam using a novel polyol component.
This invention relates to a method for producing a rigid polyurethane foam with good thermal conductivity, resin strength, demoldability, low-temperature dimensional stability, and brittleness, and well-balanced physical properties.

Rigid polyurethane foam is widely used as a heat insulating material for refrigerators, showcases, thermal warehouses, frozen warehouses, chemical tanks, etc. due to its excellent heat insulating performance.

(Prior art) When using rigid polyurethane foam as a heat insulating material for refrigerators, showcases, etc., it not only provides good insulation, but also causes poor appearance due to peeling between the rigid polyurethane foam and the surface metal plate. It is important that the adhesiveness between the rigid polyurethane foam and the metal plate is good, that is, that the rigid polyurethane foam has low brittleness.It is also important that the rigid polyurethane foam has low brittleness at low temperatures. It is also important that the rigid polyurethane foam has good stability, sufficient resin strength to maintain product strength, and good demoldability from the perspective of improving productivity. All of these physical properties must be satisfied in a well-balanced manner, and improvements in performance of these physical properties are constantly demanded by users and manufacturers.

As a result of studying various rigid polyurethane foam formulations, the present inventors found that rigid polyurethane foams obtained using specific polyol components had a well-balanced thermal conductivity, resin strength, low-temperature dimensional stability, and brittleness. The present inventors have discovered that the present invention is excellent and have completed the present invention.

<Object of the Invention> An object of the present invention is to provide a rigid polyurethane foam that is excellent in thermal conductivity, resin strength, low-temperature dimensional stability, and brittleness in a well-balanced manner.

The object of the present invention is to produce a rigid polyurethane foam by reacting a polyisocyanate and a polyol in the presence of a catalyst, a blowing agent, and a foam stabilizer. Polyol (a) and (bl are 65 to 75% by weight, (al is 30 or more, (b) is 15% or more by weight, polyol (c+ and (d) is 25 to 35% by weight) This is achieved by using a mixed polyol whose dl is greater than or equal to 10% by weight.

(al Toluene diamine polyol with functional group number 4 and hydroxyl value 350 to 500 (b) Average functional group number 2.2 to 3.6 and hydroxyl value 20
0 to 550 aromatic polyester polyol (c+
Sugar polyol (dl) having a functional group number of 8 and a hydroxyl value of 350 to 480 Glycerin, trimethylolpropane or triethanolamine polyol having a functional group number of 3 and a hydroxyl value of 400 to 700 (Constitution of the Invention) The polyisocyanate used in the present invention is - Organic compounds having two or more isocyanate groups in the molecule, including aliphatic and aromatic polyisocyanate compounds, as well as modified products thereof. Examples of aliphatic polyisocyanates include: Examples of aromatic polyisocyanates include toluene diisocyanate, diphenylmethane diisocyanate, and polymeric diphenylmethane diisocyanate. Examples of modified products of these include carbodiimide-modified products and prepolymer-modified products. Preferred polyisocyanates in the present invention are aromatic polyisocyanates or modified aromatic polyisocyanates,
Particularly preferred are diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, and modified products thereof as shown below.

Polymeric diphenylmethane diisocyanate is a polymer of the above diphenylmethane diisocyanate, and N
The CO content is 29-35% and the viscosity is 2500 cps.
(25°C) or below. Examples of these modified products include carbodiimide modified products and prepolymer modified products. Carbodiimide-modified products are those in which carbodiimide bonds are introduced using a known phosphorus-based catalyst, and prepolymer-modified products are those in which isocyanate and polyol are reacted to leave isocyanate groups at the ends. As polyols, all polyols for polyurethane resins can be used.

The polyols used in the present invention include the following (a) to
A polyol mixture consisting of (d) is used in specific proportions.

(al Toluene diamine polyol with an average functional group number of 4 and a hydroxyl value of 350 to 500 (b) An average functional group number of 2.2 to 3.6 and a hydroxyl value of 20
Aromatic polyester polyol tel of 0-550
Sugar polyol (DL) with an average functional number of 8 and a hydroxyl value of 350 to 480 Glycerin, trimethylolpropane or triethanolamine polyol with an average functional number of 3 and a hydroxyl value of 400 to 700 (the weight ratio of Al and FBL is 65% of the total polyol) -75%, polyol (al is 30% or more, preferably 40-55%, (b+ is 15% or more,
Preferably it is 20-35%. The weight proportion of polyols (c) and (d) is 25 to 35% of the total polyol, and the polyol fcl is 15% or more, preferably 15 to 35%.
20%, and +dl is 10% or more, preferably 10 to
Used as 15%.

The toluenediamine polyol fa+ is effective in improving thermal conductivity and resin strength. Toluenediamine has four amine active hydrogens, and has four functional groups. The hydroxyl value is 350 to 500, preferably 390 to 460; if it is less than 350, the molecule as a polyol becomes too long, resulting in insufficient resin strength and poor thermal conductivity. The length is short and the form is brittle. If the amount of polyol (a) used is less than the above range, there will be no effect on thermal conductivity, and if it exceeds the above range, problems will arise in resin strength and demoldability. The method for producing toluenediamine-based polyol is the same as the method for producing known polyether polyols, in which alkylene oxide such as ethylene oxide or propylene oxide is added to toluenediamine alone or to a mixture of toluenediamine and glycerin or triethanolamine. Obtained by adding. At this time, a catalyst may or may not be used, and when used, known sodium hydroxide, potassium hydroxide, etc. can be used.

Aromatic polyester polyol (b) has a remarkable effect on lowering thermal conductivity. Hydroxyl value 200-550
, preferably 250 to 450, more preferably 250
~350, and the average number of functional groups is 2.2 to 3.6, preferably 2.2 to 3.0. If the hydroxyl value is less than 200 or the average number of functional groups exceeds 3.6, the viscosity becomes high and handling becomes difficult.

Furthermore, if the hydroxyl value exceeds 550 or the average number of functional groups is less than 2.2, the thermal conductivity, strength, and demoldability of the resulting polyurethane foam will decrease. If the proportion of aromatic polyester polyol used is less than the above range, physical properties such as thermal conductivity and resin strength will be affected.On the other hand, if the proportion used exceeds the above range, the viscosity of the polyol will become high and it will be difficult to handle. , the brittleness of the foam deteriorates.

There are five types of methods for producing aromatic polyester polyols: (A) to (E) below.

(A) Aromatic polycarboxylic acid or its acid anhydride and bifunctional and trifunctional alcohols are heated at 150 ml under normal pressure.
An aromatic polyester polyol is obtained by carrying out an esterification reaction at a high temperature of ~300°C.

In this case, a catalyst may be used or not, and when used, known esterification catalysts or transesterification catalysts such as calcium acetate, magnesium acetate, alkyl tin, etc. can be used.

(B) Aromatic polycarboxylic acid and alkylene oxide are reacted in an amount of less than 2 moles of alkylene oxide per 1 mole of carboxylic acid, and then a trifunctional alcohol or a mixture of trifunctional and difunctional alcohols is reacted in the same manner as in (A). to obtain an aromatic polyester polyol.

(c) an aromatic polycarboxylic acid anhydride and a trifunctional alcohol or a mixture of trifunctional and difunctional alcohols,
0.3 mole or more of alcohol per 1 mole of carboxylic acid2
The reaction is carried out in less than a molar amount, and then an alkylene oxide is added to obtain an aromatic polyester polyol.

(D) A polyester resin such as polyethylene terephthalate is depolymerized with a trifunctional alcohol or a mixture of trifunctional and difunctional alcohols to obtain an aromatic polyester polyol.

(E) An alkylene oxide is further added to the aromatic polyester polyol of (A) (B) (D>).

In these reactions, the average number of functional groups is determined from the amount of each raw material charged, the amount of aromatic polyester polyol produced, the amount of reaction distillate, etc.

Aromatic polycarboxylic acids used include phthalic acid, trimellitic acid, pyromellitic acid, and acid anhydrides thereof.

The difunctional alcohols used include ethylene glycol, diethylene glycol, triethylene glycol,
Propylene glycol, dipropylene glycol, butanediol, hexanediol, xylene diol, etc. are used, and trifunctional alcohols used include glycerin, trimethylolpropane, etc.

Sugar polyol (c1 is effective for resin strength, demoldability, and brittleness. Sugar has eight hydroxyl active hydrogens and is octafunctional. The hydroxyl value is 350 to 480, preferably 400 to 460. be.

If the hydroxyl value is less than 350, the viscosity of the polyol will become high, making it difficult to handle, or the resin strength of the foam will decrease.
Demovability deteriorates. If it exceeds 480, the resulting foam will become too stiff and will instead become brittle. If the proportion of sugar polyol used is less than the above range, the resin strength, low temperature dimensional stability, and demoldability will be reduced, and if it exceeds the above range, the thermal conductivity will be reduced.

The manufacturing method of sugar polyol is the same as the manufacturing method of known polyether polyol, and sugar polyol can be obtained by adding alkylene oxide such as ethylene oxide or propylene oxide to sugar alone or a mixture of sugar and glycerin or triethanolamine. be able to,
In this case, a catalyst may or may not be used, and when used, known sodium hydroxide, potassium hydroxide, etc. can be used.

A trifunctional polyol (dl) based on glycerin, trimethylolpropane or triethanolamine is necessary to lower the viscosity of the polyol mixture. However, difunctional polyols cannot be used because they reduce resin strength and demoldability. The hydroxyl value is between 400 and 700. If the hydroxyl value is less than 400, the molecule will be too long and the resin strength and demoldability will decrease. If it exceeds 700, the molecule will be too short and the resulting foam will be compromised. The proportion of trifunctional polyol used is 10 to 20% by weight, 10% by weight.
If it is less than % by weight, the viscosity of the polyol mixture will become high. Also, if it exceeds 20% by weight, the resin strength of the foam will decrease.
Demovability deteriorates. The method for producing trifunctional polyol is the same as the method for producing known polyether polyol,
It is obtained by adding alkylene oxide such as ethylene oxide or propylene oxide to glycerin, trimethylolpropane or triethanolamine. In this case, a catalyst may or may not be used, and when used, known sodium hydroxide, potassium hydroxide, etc. can be used.

In addition to the above, the proportions of these four types of polyols are such that the weight proportion of (al + (b) is 65 to 75%, (c
)+(d) is required to have a weight proportion of 25 to 35%. That is, the weight ratio of (a) + (b) is 65
If it is less than 75%, the thermal conductivity will not decrease, and if it exceeds 75%, the resin strength, low-temperature dimensional stability, and demoldability will deteriorate.

As the catalyst used in the present invention, all catalysts commonly used in the production of urethane foam can be used. Examples include N, N, N', N'-tetramethylhexamethylenediamine, pentamethyldiethylenetriamine, triethylamine, N, NN'', N'-1,3-butanediamine, and the like.

As the blowing agent used in the present invention, all blowing agents commonly used in the production of polyurethane foams and polyisocyanurate foams can be used.

For example, fluorocarbon compounds such as trichlorofluoromethane and dichlorodifluoromethane are used as low boiling point inert solvents.
Water, acid amide,
Examples of substances such as nitroalkanes that generate gas when thermally decomposed include sodium bicarbonate and ammonium carbonate. Among these, preferable blowing agents are chlorofluorocarbon blowing agents, particularly trichlorofluoromethane.

The foam stabilizer used in the present invention may be nonionic, anionic, or cationic surfactant, but
Preferably, a nonionic silicone surfactant is used. Examples of silicone surfactants include L-501, L-5420, F-305, and
F-114, 5H-190, 5H-193, TFA-4
There are 200 etc.

In addition to the above, other auxiliary agents may be added as necessary.

These auxiliaries include phosphorus and/or halogen-containing organic compounds, halogen-containing resins, additive flame retardants such as antimony oxide, colored powders such as pigments and dyes, short glass fibers, carbon fibers, alumina fillers, etc. fibrous filler, talc, graphite, melamine,
Examples include clay, granular fillers such as aluminum hydroxide, other inorganic fillers, and organic solvents.

To produce polyurethane foam using the various raw materials mentioned above, the NGO10H equivalent ratio is 1.00-1.35, preferably 1.03-1. Perform in step 5. It is permissible to introduce isocyanurate bonds as long as the brittleness of the obtained foam does not become a problem.

To produce rigid polyurethane foam from each of these raw materials, each raw material is brought to the required temperature (usually 15
~25°C) and mix and stir. At this time, each of the original families may be mixed in advance with those that do not react with each other, or may be mixed one after another.

<Examples> Examples of the present invention are shown below, but the present invention is not limited to these Examples.

The raw materials used in the examples are shown below.

(a) Toluene diamine polyol: Addition of propylene oxide to toluene diamine. Hydroxyl value 460, viscosity 5000 cps/25°C, number of functional groups 4°fbl Aromatic polyester polyol: Phthalic anhydride is esterified with propylene glycol, dipropylene glycol, and glycerin. Hydroxyl value 260, viscosity 800,000cpS725°C1 average number of functional groups 2.4
゜(c1 sugar polyol; propylene oxide added to sugar. Hydroxyl value 450, viscosity 7000 cps
/25°C, number of functional groups: 8° (d) Triethanolamine polyol: Propylene oxide is added to triethanolamine. Hydroxyl value 480, viscosity 400cps/25℃
, Number of functional groups: 3°・Foam stabilizer: L-5420 (manufactured by Nippon Unicar Co., Ltd.)・Catalyst:
Tetramethylhexanediamine/Blowing agent: Freon R-
11,E Polyisocyanate: PAPI-135 (manufactured by M.D. Kasei Co., Ltd., polymeric diphenylmethane diisocyanate NGO content 31° 3% by weight, viscosity 180 cp
s/25°C) Examples 1 to 7. Comparative Examples 1 to 4 The above polyisocyanate and polyol preminx (a uniform mixture of all raw materials other than polyisocyanate) were mixed at room temperature using a hand drill with stirring blades at the compounding ratio shown in Table 1. , 40℃ before cream time
A rigid polyurethane foam panel was produced by pouring into a 30 x 60 x 5 CI11 mold. The demolding time was 4 minutes from the start of stirring.

Table 1 shows each formulation and physical property values.

<Effects of the Invention> According to the present invention, a rigid polyurethane foam with good thermal conductivity, resin strength, demoldability, low-temperature dimensional stability, and brittleness and with well-balanced physical properties can be obtained.

applicant

Claims (1)

[Claims] (1) When producing a rigid polyurethane foam by reacting a polyisocyanate and a polyol in the presence of a catalyst, a blowing agent, and a foam stabilizer, the polyol is a polyol consisting of the following (a) to (d): , 65 to 75% by weight of polyols (a) and (b), provided that (a)
is 30% by weight or more, (b) is 15% by weight or more, polyols (c) and (d) are 25 to 35% by weight, provided that (c) is 15% by weight or more and (d) is 10% by weight or more. A method for producing rigid polyurethane foam, characterized by using mixed polyols. (a) Toluene diamine polyol with 4 functional groups and hydroxyl value 350-500 (b) Average functional group number 2.2-3.6 and hydroxyl value 200-500
550 aromatic polyester polyol (c) Sugar polyol with 8 functional groups and hydroxyl value 350 to 480 (d) Glycerin, trimethylolpropane or triethanolamine polyol with 3 functional groups and hydroxyl value 400 to 700