JP3344798B2 - Method for producing terminal isocyanate prepolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a prepolymer for a polyurethane resin.

[0002]

BACKGROUND OF THE INVENTION It is widely known that polyester polyols are used in the production of polyurethane resins with polyisocyanates and suitable auxiliaries. A urethane resin production method using a prepolymer in combination with a prepolymerization method in which a polyether polyol or polyester polyol and a polyisocyanate are preliminarily reacted for the purpose of controlling the viscosity and the primary structure and compatibility of the polymer. Are also widely known. As a method for producing a rigid urethane foam using a polyester polyol, for example, US Pat. No. 4,816,529 and US Pat.
No. 6,530, and a method for producing an isocyanate prepolymer modified with a polyester polyol is disclosed in, for example, JP-A-63-19972.
0, JP-A-05-25241, JP-A-01-6961
8, JP-A-02-251509, JP-A-04-1174
19 etc.

[0003] In these conventional methods for producing a prepolymer, the polyisocyanate and the polyester polyol are mixed at room temperature or mixed at 80 ° C or lower, and the temperature is raised and the reaction temperature is 140 ° C or lower. ,
If necessary, the reaction is carried out in the presence of a catalyst used in urethane chemistry, an inert solvent or a plasticizer, and at normal pressure under an inert nitrogen stream. The polyisocyanates used are currently commercially available polyisocyanates, i.e., toluene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, xylylene diisocyanate, and isophorone diisocyanate. And naphthalene, hexamethylene diisocyanate and the like. Among them, particularly for polymethylene polyphenyl isocyanate (so-called polymeric MDI), those obtained by phosgenation of a polyamine mixture formed by condensation of aniline and formalin are used as they are.

The method of extracting polyisocyanate using a solvent is disclosed in Japanese Patent Publication No. 23180/1986 and Japanese Patent Laid-Open Publication No. 61-63644 / 1990, and the like. ,
4'-diisocyanate, diphenylmethane-2,4 '
A method for obtaining a diisocyanate, which is carried out in a state before obtaining a product MDI containing a chlorinated aromatic hydrocarbon which is a solvent in a phosgenation step. Further, a method for controlling the nucleus ratio of the polyisocyanate is disclosed in JP-A-5-310676. However, a urethane resin production method and a method for producing a prepolymer from a polyisocyanate and a polyester polyol are disclosed. There is no statement to do so.

[0005]

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. Or a minute polymer is precipitated, which is not preferable in terms of physical properties and process. In this prepolymerization reaction, when the reaction is carried out at a high temperature, no smudge or fine polymer is generated, but by reacting at a high temperature, the polyisocyanate further reacts with the generated urethane bond to form an allohanate. It is considered that the bond is formed in the reaction system, and thus is not preferable in the urethane resin production process.

Further, there is a method in which a polyester polyol is dissolved in a solvent and reacted with a polyisocyanate, and then the solvent is distilled off, thereby producing an isocyanate prepolymer without generating turbidity or a fine polymer. However, since the purification process, that is, the distillation after the reaction is complicated, and the cost becomes very high, it is a major problem.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, by using polymethylene polyphenyl isocyanate having a specific composition as a polyisocyanate, the polyester polyol and The present inventors have found a method for producing a terminal isocyanate prepolymer without producing a turbid or fine polymer without using a solvent, a plasticizer, and the like in the production of the prepolymer, and reached the present invention.

That is, the present invention is as follows (1) to (5). (1) When a terminal isocyanate prepolymer is produced using a polyisocyanate and a polyester polyol , the polyester polyol has a hydroxyl value of 100 mgK.
OH / g or more and 600 mgKOH / g or less, and polymethylene polyphenyl isocyanate represented by the general formula (1) [formula 2] as a polyisocyanate.

Embedded image (Where n is 0 or a positive integer) 1) The content of binuclear (n = 0) is 50% by weight or less 2) Trinuclear (n = 1) and tetranuclear (n = 2) A method for producing a terminal isocyanate prepolymer, which comprises using a mixture having a weight ratio of 1.5 or more and a pentanuclear compound (n = 3) or more and a content of 8% by weight or less. (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 between 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 at least one compound 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 an alkylene oxide adduct thereof (2). The method for producing the terminal isocyanate prepolymer described above. (5) The method for producing a terminal isocyanate prepolymer according to (1), wherein the equivalent ratio of polyisocyanate to polyester polyol (polyisocyanate to polyester polyol) is 1: 0.01 to 0.9.

The polyisocyanate used in the method of the present invention may be a polyisocyanate obtained by phosgenation of a polyamine mixture formed by the condensation of aniline and formaldehyde in the presence of an acid catalyst, or diphenylmethane diisocyanate from this polyisocyanate. Polyisocyanate (Polymeric M)
DI) is a polyisocyanate extracted with a predetermined solvent, having a value of at least 1.5 trinuclear / tetranuclear (nucleus ratio) and a content of at least 5 nuclei of 8% by weight or less. .

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, or a polyester polyol obtained by addition-polymerizing an alkylene oxide to a polycarboxylic acid. Can be used.

The polycarboxylic acids used in the production of polyester polyols include, for example, phthalic anhydride, maleic acid, succinic anhydride, terephthalic acid, dimethyl terephthalic acid, isophthalic acid, fumaric acid, oxalic acid, malonic acid, glutaric acid, Adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, citric acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, and the like. Further, similarly used compounds having two or more active hydrogens include, for example, ethylene glycol, diethylene glycol, triethylene glycol, butylene glycol, glycerin, trimethylolpropane, sorbitol, pentaerythritol, sucrose,
Diglycerin, dipropylene glycol, 1,3- or 1,4-butanediol, 1,5-pentanediol,
1,6-hexanediol 1,2-cyclohexanediol and the like, and ethylene oxide,
Compounds to which alkylene oxides such as propylene oxide and butylene oxide have been added, and alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, triisopropanolamine and diisopropanolamine, and aliphatics such as ethylenediamine, diethylenetriamine and triethylenetetramine Compounds obtained by addition polymerization of alkylene oxide to polyamines, aromatic polyamines such as 2,4-tolylenediamine, 2,6-tolylenediamine, aniline, and 4,4′-diphenylmethanediamine, and the like can also be used. . Also,
Each of these compounds having active hydrogen can be used alone or as a mixture thereof. Although the hydroxyl value of the polyester polyol used in the present invention is not particularly limited, it is 100 mgKOH / g or more.
Those having a concentration of not more than 00 mgKOH / g are suitably used for producing a 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'-tetoolamethylhexamethylenediamine, 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, and potassium octanoate. Also,
Specific amine compounds include, for example, dimethyloctylamine, trioctylamine, dimethyldecylamine, dimethyllaurylamine, dimethylmyristylamine, dimethylpalmitylamine, dimethyloleylamine, dimethylstearylamine, dimethyllinolenic amine, and the like. The use amount of such a catalyst is not particularly limited, but is 0.01 to
An amount of 5.0% by weight, preferably 0.1-1.0% by weight, is used.

The equivalent ratio between the polyisocyanate and the polyester polyol differs depending on the raw material system used. When the equivalent ratio is 1.00 when the polyisocyanate is 1.00, when the equivalent ratio is 0.01 or less, the prepolymerization of the urethane resin is difficult. No effect is observed, and if it exceeds 0.90, the viscosity rises sharply, which is not preferable for urethane resin production. That is, an equivalent ratio of 0.01 to 0.90 is used. The reaction temperature is not particularly limited, but if it exceeds 160 ° C., a by-product reaction such as an allophosphate bond in which an isocyanate group is further reacted with a urethane bond generated in the reaction system is likely to occur, which may reduce physical properties of the prepolymer. For this reason, it is not preferable, and the reaction is desirably carried out at room temperature to 160 ° C, preferably 80 to 120 ° C.

In the prepolymerization reaction, a predetermined amount of an organic polyisocyanate and an additive are charged into a reaction vessel, and after nitrogen replacement, a predetermined temperature, that is, 80 ° C. to 120 ° C.
Adjust the temperature to ° C. At that time, if necessary, the polyester polyol is also adjusted to a predetermined temperature, that is, from room temperature to 120 ° C. Thereafter, the polyester polyol is charged into the reactor containing the polyisocyanate to start the reaction. The reaction may be performed in a nitrogen stream, or may be performed under a pressurized state.
The reaction time is determined by the raw material system, temperature and pressure, and the method preferably used is a method in which the reaction is carried out for 15 minutes to 10 hours.

[0015]

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

The polyisocyanates used are as follows. Isocyanate A; 100 parts by weight of 41% dinuclear MDI
(2,4′-MDI: 4,4′-MDI = 8: 92),
150 parts by weight of hexane was added to a polyisocyanate containing 28% of trinuclear MDI and 31% of MDI of 4 or more nuclei, stirred at 20 ° C. for 3 minutes, allowed to stand for 30 minutes, and the lower layer was separated and removed. did. When the solvent was distilled off from the upper layer, 13 parts by weight of polyisocyanate was obtained. Polyisocyanate (NCO%; 33.0) subjected to such a purification method isocyanate B; polymethylene polyphenyl isocyanate (NCO%; 31.1, viscosity: 185 cps / 25)
C) (trade name; Cosmonate M-200, manufactured by Mitsui Toatsu Chemicals, Inc.) Isocyanate C: polyisocyanate obtained by adding an equal amount of diphenylmethane 4,4 'diisocyanate to polyisocyanate A (NCO%; 33.3)

The polyester polyols used are as follows. Ester polyol A; hydroxyl value 481 (mg KOH / g) obtained by dehydration condensation of carboxylic acid ester reacted with phthalic anhydride and ethylene glycol and ethylene glycol, viscosity 4200 (cps / 2)
5 ° C.) polyester polyol. Polyol B; hydroxyl value 584 (mgKOH / g), viscosity 2200 obtained by dehydrating and condensing carboxylic acid ester reacted with glycerin to which phthalic anhydride and propylene oxide are added 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 temperature was adjusted to 80 ° C. On the other hand, the heating temperature of polyol A was also adjusted to 70 ° C. After the heating temperature was adjusted, the polyester polyol A was charged into a separable flask and reacted in a nitrogen stream. The reaction temperature was 80 ° C., and the reaction time was 1 hour. After the temperature was lowered, the kettle was opened and the degree of adhesion to the kettle and the amount of the fine polymer were evaluated through a stainless steel net of 100 and 200 mesh. In addition, viscosity (cps / 25 ° C) and N
CO% was measured.

Comparative Example 1 In the same manner as in Example 1, 500 g of isocyanate B was placed in a 1-liter glass separable flask, and the heating temperature was adjusted to 80 ° C. On the other hand, the heating temperature of polyol A was also adjusted to 70 ° C. After adjusting the heating temperature, the polyol A was charged into a separable flask and reacted in a nitrogen stream. The reaction temperature is 80 ° C and the reaction time is 1
After the temperature was lowered, the kettle was opened and passed through stainless steel nets of 100 and 200 mesh to evaluate the degree of adhesion to the kettle and the amount of the fine polymer. Also, viscosity (cps / 25 ° C)
And NCO% were measured.

Comparative Example 2 In the same manner as in Example 1, 500 g of isocyanate C was placed in a glass separable flask having an internal volume of 1 liter, and the heating temperature was adjusted to 80 ° C. On the other hand, the heating temperature of polyol A was also adjusted to 70 ° C. After adjusting the heating temperature, the polyol A was charged into a separable flask and reacted in a nitrogen stream. The reaction temperature is 80 ° C and the reaction time is 1
After the temperature was lowered, the kettle was opened and passed through stainless steel nets of 100 and 200 mesh to evaluate the degree of adhesion to the kettle and the amount of the fine polymer. Also, viscosity (cps / 25 ° C)
And NCO% were measured.

Comparative Example 3 In the same manner as in Example 1, 500 g of isocyanate B was placed in a 1-liter glass separable flask, and the temperature was adjusted to 140 ° C. On the other hand, the heating temperature of polyol A was also adjusted to 70 ° C. After adjusting the heating temperature, the polyol A was charged into a separable flask and reacted in a nitrogen stream. The reaction temperature was 140 ° C. and the reaction time was 40 minutes. After the temperature was lowered, the kettle was opened, and the degree of adhesion to the kettle and the amount of the fine polymer were evaluated through 100 and 200 mesh stainless steel nets. In addition, viscosity (cps / 2
5 ° C.) and NCO%.

Table 1 summarizes the production results. A rigid urethane foam was produced using the terminal isocyanate prepolymer prepared according to Example 1 and the terminal isocyanate prepolymer prepared according to Comparative Example 3, and the reaction rate,
The density, compressive strength, and thermal conductivity were measured. The foaming operation was performed by a conventional method. Table 2 summarizes the foaming formulation and the foaming results.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

According to the method of the present invention, the terminal isocyanate having no turbidity, crystallization, fine polymer, etc., compared with the case of producing a prepolymer using a polyisocyanate having a nucleus composition ratio other than the above. The temperature for producing the prepolymer could be reduced. The physical properties of the rigid urethane foam, mechanical properties, thermal conductivity, and both are good, and the terminal isocyanate prepolymer produced by the method of the present invention can be suitably used for polyurethane foam production using a polyester polyol. Things.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-296818 (JP, A) West German Patent Application Publication 3245678 (DE, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 18/00-18/87

Claims (5)

(57) [Claims] 1. A prepolymer having a polyisocyanate and a polyol having an ester bond in a molecule (hereinafter, referred to as a polyester polyol) and having a terminal isocyanate group (hereinafter, referred to as a terminal isocyanate prepolymer). When manufacturing polyester polyols
Has a hydroxyl value of 100 mgKOH / g or more and 600 mgKO
H / g or less, and polymethylene polyphenyl isocyanate represented by the general formula (1) [formula 1] as a polyisocyanate: (Where n is 0 or a positive integer) 1) The content of binuclear (n = 0) is 50% by weight or less 2) Trinuclear (n = 1) and tetranuclear (n = 2) A method for producing a terminal isocyanate prepolymer, which comprises using a mixture having a weight ratio of 1.5 or more and a pentanuclear compound (n = 3) or more and a content of 8% by weight or less. 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 between 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 at least one compound selected from the group consisting of phthalic anhydride, maleic anhydride, succinic anhydride, and terephthalic acid. Method. 4. The 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, wherein the compound is at least one compound selected from the group consisting of trimethylolpropane, sorbitol, sucrose, and an alkylene oxide adduct thereof. 5. The method of claim 1, wherein the equivalent ratio of polyisocyanate to polyester polyol (polyisocyanate to polyester polyol) is 1: 0.01 to 0.9.
The method for producing the terminal isocyanate prepolymer described above.