JPH07188369A - Production of end isocyanate prepolymer - Google Patents

Abstract

PURPOSE:To obtain a prepolymer useful as a rigid urethane foam, etc., free from turbidity, very small polymers, etc., by reacting a polyisocyanate purified by a specific method with an ester bond-containing polyol. CONSTITUTION:This prepolymer is obtained by reacting (A) a polyisocyanate composition having the weight ratio (trinuclear substance/tetranuclear substance and polynuclear substance) of a trinuclear substance ((n)=1) and a tetranuclear substance ((n)=4) and a polynuclear substance of >=1.5 prepared by extracting a polyisocyanate of the formula ((n) is 0 or positive integer) with a >=5C aliphatic and/or alicyclic hydrocarbon with (B) a polyol (polyester polyol) containing an intramolecular ester bond. The component B, for example, is obtained by esterifying a polycarboxylic acid with a compound containing two or more active hydrogen atoms. The equivalent ratio of the component A and the component B is preferably 1:0.01-0.9.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a prepolymer for a polyurethane resin.

[0002]

BACKGROUND OF THE INVENTION Polyester polyols are widely known to be used in the production of polyurethane resins with polyisocyanates and suitable auxiliaries. Further, in order to control the viscosity, the primary structure of the polymer, and the compatibility, a method of prepolymerization in which a polyether polyol or polyester polyol and polyisocyanate are preliminarily reacted is used, and a urethane resin production method using a prepolymer in combination is also used. Is also widely known.

As a method for producing a rigid urethane foam using polyester polyol, for example, US Pat.
16, 529, U.S. Pat. No. 4,636,530, and in a method for producing an isocyanate prepolymer modified with a polyester polyol,
For example, JP-A-63-199720 and JP-A-05-25
241, JP-A 01-69618, and JP-A 02-251.
509 and Japanese Patent Laid-Open No. 04-117419. In these conventional methods for producing prepolymers, polyisocyanate and polyester polyol are mixed at room temperature to 80 ° C. or lower, the reaction temperature is 140 ° C. or lower, and used in urethane chemistry as required. In the presence of catalysts, inert solvents and plasticizers,
The reaction is carried out under atmospheric pressure under an inert nitrogen stream.

As for the polyisocyanate used, commercially available polyisocyanates, namely, toluene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate and xylylene diisocyanate are currently available. , Isophorone diisocyanate, hexamethylene diisocyanate, and the like. Among these, particularly polymethylene polyphenyl polyisocyanate (so-called polymeric MDI), that obtained by phosgenation of a polyamine composition produced by condensation of aniline and formalin is used as it is.

Further, a method for extracting polyisocyanate with a solvent is disclosed in JP-B-61-23180, JP-A-61-63644 and JP-A-1-102052, but these are pure diphenylmethane-4. ，
4'-diisocyanate, diphenylmethane-2,4 '
-A method for obtaining diisocyanates, which is carried out in the state before the MDI of the product is obtained, containing the chlorinated aromatic hydrocarbon which is the solvent during the phosgenation step. Further, as for a method for controlling the nuclide ratio of polyisocyanate, a method is disclosed in JP-A-5-310676. However, a method for producing a urethane resin and a prepolymer from a polyisocyanate and a polyester polyol are produced. There is no description of doing.

[0006]

However, when a prepolymer is produced from a specific polyester polyol having an ester bond in the polyol and a so-called polymeric MDI, the compatibility is poor and the reaction product may become turbid or minute. Happened to deposit a different polymer,
It cannot be said that it is preferable in terms of physical properties and process.
When this prepolymerization reaction is carried out at a high temperature, no turbidity or minute polymer is generated, but by reacting at a high temperature, the urethane bond formed is further reacted with polyisocyanate to give an alohanate. This is not preferable in the urethane resin production process because the bond is considered to be generated in the reaction system. In addition, there is a method of producing an isocyanate prepolymer without producing turbidity or a fine polymer by a method of dissolving a polyester polyol in a solvent and reacting it with a polyisocyanate, and then distilling off the solvent by distillation. The process, that is, the distillation after the reaction is complicated and the cost is very high, which is a big problem.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that by using polymethylene polyphenyl isocyanate having a specific composition as the polyisocyanate, a polyester polyol can be obtained. The present invention was accomplished by finding a method for producing a terminal isocyanate prepolymer without producing a fine polymer without producing a turbidity even when a solvent, a plasticizer, etc. are not used together in the production of the prepolymer (1).

That is, the present invention is as follows (1) to (5). (1) When a polyisocyanate and a polyester polyol are used to produce a terminal isocyanate prepolymer, a polyisocyanate represented by the general formula (1)
The polyisocyanate represented by

[Chemical 2] (In the formula, n represents 0 or a positive integer.) Trinuclear (n) obtained by extracting at a temperature of less than 40 ° C. using an aliphatic and / or alicyclic hydrocarbon having 5 or more carbon atoms =
1) Production of a terminal isocyanate prepolymer characterized by using a polyisocyanate composition having a weight ratio of trinuclear (n = 2) or more (trinuclear / 4 tetranuclear or more) of 1.5 or more Method. (2) The method for producing a terminal isocyanate prepolymer according to (1), wherein the polyester polyol is a polyester polyol obtained by an esterification reaction of a polycarboxylic acid and a compound having two or more active hydrogens. (3) The method for producing a terminal isocyanate prepolymer according to (2), wherein the polycarboxylic acid is one or more compounds selected from the group consisting of phthalic anhydride, maleic anhydride, succinic anhydride, and terephthalic acid. (4) The compound having two or more active hydrogens is one or more compounds selected from the group consisting of ethylene glycol, diethylene glycol, glycerin, trimethylolpropane, sorbitol, sucrose and alkylene oxide adducts thereof (2) A method for producing the described terminal isocyanate prepolymer. (5) The method for producing a terminal isocyanate prepolymer according to (1), wherein the equivalent ratio of polyisocyanate and polyester polyol (polyisocyanate to polyester polyol) is 1: 0.01 to 0.9.

The polyisocyanate used in the method of the present invention is a polyisocyanate obtained by phosgenation of a polyamine composition produced by condensation of aniline and formaldehyde in the presence of an acid catalyst, or diphenylmethane diisocyanate from this polyisocyanate. A polyisocyanate composition in which a weight ratio of a trinuclear compound to a tetranuclear compound or more is 1.5 or more, which is obtained by extracting a polyisocyanate (so-called polymeric MDI) from which a part of the isocyanate is removed with a solvent. .

The polyester polyol used in the present invention is a polyester polyol obtained by polycondensing a polycarboxylic acid and a compound having two or more active hydrogens to form an ester, or a polyester polyol obtained by addition-polymerizing an alkylene oxide with a polycarboxylic acid. Can be used.

As the polycarboxylic acid used in the production of polyester polyol, for example, phthalic anhydride, maleic acid, succinic anhydride, terephthalic acid, dimethyl terephthalic acid, isophthalic acid, fumaric acid, oxalic acid, malonic acid, glutaric acid, Examples thereof include adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, citric acid, trimellitic acid, trimellitic anhydride, and pyromellitic acid. In addition, examples of compounds having two or more active hydrogens used in the same manner include, for example, ethylene glycol, diethylene glycol, triethylene glycol, butylene glycol, glycerin, trimethylolpropane, sorbitol, pentaerythritol, sucrose, diglycerin. , Dipropylene glycol,
Examples thereof include 1,3- or 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and 1,2-cyclohexanediol, and alkylenes such as ethylene oxide, propylene oxide and butylene oxide. Compounds added with oxides, alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, triisopropanolamine and diisopropanolamine, aliphatic polyamines such as ethylenediamine, diethylenetriamine and triethylenetetramine, 2,4-tolylenediene Amine,
A compound obtained by addition-polymerizing an alkylene oxide with an aromatic polyamine such as 2,6-tolylenediamine, aniline, or 4,4′-diphenylmethanediamine can also be used. In addition, these compounds having active hydrogen can be used alone or as respective compositions. The hydroxyl value of the polyester polyol used in the present invention is not particularly limited, but 10 mgKOH
/ G or more and 600 mgKOH / g or less are suitably used for the production of the polyurethane resin.

In the method of the present invention, a suitable additive such as a catalyst may be used in combination, and the catalyst may be a catalyst known in urethane chemistry, for example, N, N, N ', N'-tetramethylhexamethylene. Diamine, pentamethyldiethylenediamine, trimethylaminoethylpiperazine,
Triethylamine, tolylenediamine, N, N, N ',
N'-tetramethylpropanediamine, N, N, N ',
N'-tetooramethylhexamethylenediamine, N,
N, N ′, N′-1,3-butanediamine, N, N-dimethylcyclohexyldiamine, bis (2-dimethylaminoethyl) ether, N, N ′, N ″ -tris (dimethylaminoethyl) hexahydrotriazine , 2,4-
Bis (dimethylaminomethyl) phenol, 2,4,6
-Tris (dimethylaminomethyl) phenol, tetramethylguanidine, tin octoate, tin oleate,
Examples thereof include dibutyltin dilaurate, lead naphthenate, cobalt 2-ethylhexanoate, potassium acetate, sodium propionate, potassium octanoate and the like. Also,
Examples of the special amine compound include dimethyloctylamine, trioctylamine, dimethyldecylamine, dimethyllaurylamine, dimethylmyristylamine, dimethylpalmitylamine, dimethyloleylamine, dimethylstearylamine, and dimethyllinolenicamine. The amount of such a catalyst used is not particularly limited, but is 0.01 to the amount of product produced after the reaction is completed.
An amount of 5.0% by weight, preferably 0.1-1.0% by weight is used.

The equivalent ratio of the polyisocyanate to the polyester polyol varies depending on the raw material system used, but when the polyisocyanate is set to 1.00, if the polyester polyol is 0.01 equivalent ratio or less, a prepolymer should be formed in order to produce a urethane resin. The effect is not seen, and when it exceeds 0.90, the viscosity sharply increases, which is not preferable in the production of urethane resin. That is, the polyester polyol / polyisocyanate equivalent ratio is suitably 0.01 to 0.90.

The reaction temperature is not particularly limited, but if it exceeds 160 ° C., a by-product reaction such as an allophanate bond in which the isocyanate group further reacts with the urethane bond formed in the reaction system is likely to occur, and the physical properties of the prepolymer are deteriorated. There is a fear that it is not preferable, and it is normal temperature to 160
It is desirable to carry out the reaction at a temperature of preferably 80 to 120 ° C.

In the prepolymerization reaction, a predetermined amount of polyisocyanate and an additive are charged into a reaction vessel, the atmosphere is replaced with nitrogen, and then the temperature is adjusted to a predetermined temperature, that is, 80 ° C to 120 ° C. At that time, if necessary, the polyester polyol is also adjusted to a predetermined temperature, that is, room temperature to 120 ° C. Then, the polyester polyol is charged into a reactor containing polyisocyanate to start the reaction. The reaction may be carried out in a nitrogen stream or may be carried out under pressure. The reaction time is determined by the raw material system, temperature and pressure, and the method preferably used is a method of reacting for 15 minutes to 10 hours.

[0016]

The present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

The polyisocyanates used are as follows. Isocyanate A; 100 parts by weight of 41% binuclear MDI
(2,4'-MDI: 4,4'-MDI = 8: 92),
150 parts by weight of hexane was added to polyisocyanate containing 28% trinuclear MDI and 31% tetranuclear MDI or more, stirred at 20 ° C. for 3 minutes, and allowed to stand for 30 minutes, and then the lower layer was separated. did. When the solvent was distilled off from the upper layer, 13 parts by weight of polyisocyanate was obtained. Polyisocyanate (NCO%; 33.0) isocyanate B; polymethylene polyphenyl polyisocyanate (NCO%; 31.1, viscosity; 185 cps / 2) obtained by such a purification method.
5 ° C) (trade name; Cosmonate M-200, manufactured by Mitsui Toatsu Chemicals, Inc.)

The polyester polyols used are as follows. Polyol A; hydroxyl value 481 obtained by dehydration condensation of carboxylic acid ester reacted with phthalic anhydride and ethylene glycol and ethylene glycol
(MgKOH / g), viscosity 4200 (cps / 25 ° C)
Polyester polyol. Polyol B: Hydroxyl value 584 (mgKOH / g), viscosity 2200 obtained by dehydration condensation of carboxylic acid ester reacted with glycerin added with propylene oxide and ethylene glycol
0 (cps / 25 ° C) polyester polyol.

Example 1 500 g of isocyanate A was placed in a glass separable flask having an internal volume of 1 liter, and the heating temperature was adjusted to 60 ° C. On the other hand, the heating temperature of polyol A was adjusted to 60 ° C. After adjusting the heating temperature, Polyol A was charged into a separable flask and reacted in a nitrogen stream. The reaction temperature was 60 ° C. and the reaction time was 1 hour. After cooling, the kettle was opened and passed through a 100 and 200 mesh stainless net to evaluate the degree of adhesion to the kettle and the amount of fine polymer. Moreover, the viscosity (cps / 25 ° C.) and NCO% were measured.

Examples 2 to 5 Temperature control temperature and reaction temperature are 80, 100, 120, 14
A terminal isocyanate prepolymer was produced from isocyanate A and polyol A in the same manner as in Example 1 except that the temperature was changed to 0 ° C.

Comparative Example 1 As in Example 1, 500 g of isocyanate B was placed in a glass separable flask having an internal volume of 1 liter, and the heating temperature was adjusted to 60 ° C. Polyol A also 6
The heating temperature was adjusted to 0 ° C. After adjusting the heating temperature, Polyol A was charged into a separable flask and reacted in a nitrogen stream. The reaction temperature was 60 ° C. and the reaction time was 1 hour. After cooling, the kettle was opened and passed through a 100 and 200 mesh stainless net to evaluate the degree of adhesion to the kettle and the amount of fine polymer. Also, viscosity (cps / 25 ° C) and NC
O% was measured.

Comparative Example 2 Temperature control temperature and reaction temperature were 80, 100, 120, 14
A terminal isocyanate prepolymer was produced from the isocyanate B and the polyol A in the same manner as in Comparative Example 1 except that the temperature was changed to 0 ° C.

The production results are summarized in Table 1. A rigid urethane foam was prepared using the terminal isocyanate prepolymer prepared in Example 2 and the terminal isocyanate prepolymer prepared in Comparative Example 5, and the reaction rate was
The density, compressive strength and thermal conductivity were measured. The foaming operation was performed by a conventional method. The foaming formulation and the foaming results are summarized in Table 2.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

INDUSTRIAL APPLICABILITY Compared with the case where a prepolymer is produced by using a polyisocyanate which is not specially purified by the method of the present invention, which is characterized in that a reaction is carried out by using a polyisocyanate purified by a specific method. It was possible to lower the lower limit of the temperature for producing a terminal isocyanate prepolymer having neither turbidity nor fine polymer. The physical properties of the rigid urethane foam are good, both mechanical properties and thermal conductivity, and the terminal isocyanate prepolymer produced by the method of the present invention can be suitably used for producing polyurethane foam using polyester polyol. It is a thing.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Takayanagi 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (5)

[Claims] 1. A polyisocyanate and a polyol having an ester bond in the molecule (hereinafter referred to as a polyester polyol) are used, and a prepolymer having an isocyanate group at the terminal (hereinafter referred to as a terminal isocyanate prepolymer). ), A polyisocyanate represented by the general formula (1) [Chemical Formula 1] is used as a polyisocyanate: (In the formula, n represents 0 or a positive integer.) Trinuclear body (n obtained by extracting at a temperature of less than 40 ° C. using an aliphatic and / or alicyclic hydrocarbon having 5 or more carbon atoms (n =
1) A polyisocyanate composition having a weight ratio of trinuclear (n = 2) or more (trinuclear / 4 tetranuclear or more) of 1.5 or more is used, which is a terminal isocyanate prepolymer. Production method. 2. The method for producing a terminal isocyanate prepolymer according to claim 1, wherein the polyester polyol is a polyester polyol obtained by an esterification reaction of a polycarboxylic acid and a compound having two or more active hydrogens. 3. The production of a terminal isocyanate prepolymer according to claim 2, wherein the polycarboxylic acid is one or more compounds selected from the group consisting of phthalic anhydride, maleic anhydride, succinic anhydride and terephthalic acid. Method. 4. A compound having two or more active hydrogens is ethylene glycol, diethylene glycol, glycerin,
The method for producing a terminal isocyanate prepolymer according to claim 2, which is one or more compounds selected from the group consisting of trimethylolpropane, sorbitol, sucrose and alkylene oxide adducts thereof. 5. The method for producing a terminal isocyanate prepolymer according to claim 1, wherein the equivalent ratio of polyisocyanate to polyester polyol (polyisocyanate to polyester polyol) is 1: 0.01 to 0.9.