JPH05105735A - Curable prepolymer - Google Patents

Abstract

PURPOSE:To obtain the subject prepolymer showing a high elasticity and excellent in thermal resistance by reacting an organic polyisocyanate compound with a compound having a carboxylic acid at the molecular terminal. CONSTITUTION:(A) A terminal carboxylic acid-containing compound synthesized by reacting (i) a carboxylic acid an hydride with (ii) a polyhydroxy compound in >=1 equivalent ratio of COOCO in the component (i) to OH in the component (ii) is reacted with (B) an organic polyisocyanate compound (e.g. tolylene diisocyanate) to obtain the objective curable prepolymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable prepolymer which can be cured with an amine compound or an isocyanate polymerization catalyst to obtain an elastomer having high elasticity and heat resistance.

[0002]

2. Description of the Related Art Tolylene diisocyanate (hereinafter referred to as TDI) has hitherto been used as a curable prepolymer capable of obtaining an elastomer having high elasticity and heat resistance.
Naphthylene diisocyanate (hereinafter referred to as ND)
Abbreviated as "I") and a polyhydroxy compound such as polytetramethylene ether glycol, polyoxypropylene glycol, polyester polyol, etc., and a prepolymer having an isocyanate group at the molecular end is known. It is marketed under the trademark Hyprene (manufactured by Mitsui Toatsu Chemicals, Inc.) and Vibrasen (manufactured by Uniloyl).

In recent years, attempts have been made to improve the dynamic exothermic properties for the purpose of improving the heat resistance of the elastomer obtained by curing this type of curable prepolymer with an amine compound. USP 4,556,703, U
SP 4,722,989 is a typical example thereof, and it is disclosed that the heat resistance is improved by narrowing the composition distribution of the prepolymer as much as possible.

Further, Japanese Patent Laid-Open No. 61-212215 discloses that a specific curable prepolymer having 2,6-TDI at the end is effective for improving heat resistance.

However, the conventional curable prepolymer is 10
In the temperature range exceeding 0 ° C, the elastic modulus of the cured product is decreased, which is not practical.

[0006]

Elastomers obtained from curable prepolymers based on urethane have excellent wear resistance, mechanical strength, impact resilience, etc.
Widely used in solid tires, belts, etc. However, it has a drawback that it melts and fractures due to internal heat generation when it receives a dynamic repeated load. This tendency is strong and there is a lot of room for improvement in the urethane elastomer produced from a prepolymer whose performance in terms of heat resistance is not sufficiently improved.

An object of the present invention is to provide a curable prepolymer capable of producing a heat resistant elastomer.

[0008]

Means for Solving the Problems As a result of intensive studies by the present inventors, a prepolymer having an isocyanate group at the molecular end obtained by reacting a compound having a carboxylic acid group at the molecular end with an organic polyisocyanate compound The present invention has been found to improve the heat resistance of an elastomer obtained by adding a curing agent or the like and curing it.

That is, the present invention has an isocyanate group at the molecular end obtained by reacting a compound having a carboxylic acid group at the molecular end obtained by reacting a carboxylic anhydride and a polyhydroxy compound with an organic polyisocyanate compound It is a prepolymer.

Examples of the carboxylic acid anhydride used in the present invention include phthalic anhydride, malonic acid, maleic acid and the like.

The polyhydroxy compound used in the present invention is a compound having two or more hydroxyl groups. For example, water, ethylene glycol, propylene glycol, glycerin, trimethylolpropane are subjected to addition polymerization with propylene oxide or ethylene oxide. Examples thereof include polyether polyols, alkylene glycols such as ethylene glycol, propylene glycol, butylene glycol and hexylene glycol, polytetramethylene ether glycols, polycaprolactone polyols and polyester polyols such as polyethylene adipate. These compounds can be used alone or as a mixture of two or more kinds. The preferred average molecular weight range of these compounds is 200 to 10,000.

The organic polyisocyanate compound used in the present invention is, for example, tolylene diisocyanate (TD).
I), diphenylmethane diisocyanate (MDI),
Naphthylene diisocyanate (NDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), cyclohexane diisocyanate (CHDI), xylylene diisocyanate (XDI)
Etc. or polyfunctional compounds and derivatives of these isocyanates. These compounds can be used alone or as a mixture of two or more kinds.

Prepolymer Production Method First Stage Reaction The reaction between the carboxylic acid anhydride and the polyhydroxy compound is
Performed under normal pressure under a nitrogen stream. -C of carboxylic anhydride
The equivalent ratio of the O.O.CO-group to the -OH group of the polyhydroxy compound is preferably 1 or more. When it is less than 1, the heat resistance improving effect is small.

The reaction is carried out in a batch system, and the raw materials are charged all at once at room temperature. The reaction temperature is preferably 100 to 120 ° C. At this time, in order to shorten the reaction time, it is preferable to use an alkyl tertiary amine compound such as triethylamine or dimethylpalmitylamine as a catalyst, and among them, triethylamine is preferable. When using a catalyst, the addition amount is preferably less than 0.1% by weight based on the total raw materials. For example, when triethylamine was used in an amount of 0.05% by weight based on the total raw material, the reaction time at a temperature of 100 ° C. was 3 hours.

Further, carboxylic acid anhydride --CO.O.C.
When the equivalent ratio of the O-group to the -OH group of the polyhydroxy compound exceeds 1.1, or when, for example, a triethylamine catalyst is used in an amount of 0.1% or more, excess unreacted carboxylic acid anhydride or catalyst is thin-film evaporated. To remove. The reaction product is evaluated by the acid value.

Second-Step Reaction The reaction between the compound having a carboxylic acid group at the terminal of the molecule produced in the first step and the organic polyisocyanate is carried out in an excess of isocyanate groups in a normal pressure system under a nitrogen stream. After the completion of the reaction in the first stage, the temperature inside the reactor is cooled to 50 ° C. or lower, and the whole amount of organic polyisocyanate is charged. When the temperature is 170 ° C. or higher, the reaction proceeds even without a catalyst, but the reaction time can be shortened by using a tertiary amine compound as a very slight catalyst. For example, when isophorone diisocyanate was used as the organic polyisocyanate and triethylamine was used at 0.03% by weight based on the total raw materials, the reaction time at a temperature of 150 ° C. was 8 hours. Evaluation of reaction products is NC
O%.

The aromatic polyamine used as a curing agent together with the prepolymer of the present invention in order to obtain a highly elastic elastomer as a final product is methylenebis (o-
Chloroaniline) (MOCA), trimethylene glycol-p-aminobenzoate (Polacure 74
0) and the like. Examples of the isocyanate polymerization catalyst include potassium acetate and an isocyanate trimerization catalyst such as 2,4,6-tris (dimethylaminomethyl) -phenol.

[0018]

EXAMPLES The present invention will be described below with reference to examples. 1. Production of Prepolymer Example 1 A 3 L reactor equipped with a stirrer, thermometer, and nitrogen inlet tube was charged with O
Polyoxypropylene glycol having an H value of 56.1 was added to 20
00 parts by weight (1 mol), 296 parts by weight of phthalic anhydride (2 mols), and 0.8 parts by weight of triethylamine were charged. Under a nitrogen stream, the temperature inside the reactor is 100 ° C in 30 minutes.
The temperature was raised to 100 ° C. and the reaction was carried out at 100 ° C. for 4 hours. The acid value of the produced compound was 48 mgKOH / g. Next, under a nitrogen stream, the temperature inside the reactor was cooled to 50 ° C., 466 parts by weight (2 mol) of isophorone diisocyanate was charged, and after mixing and stirring at 50 ° C. for 30 minutes, the inside of the reactor was stirred for 30 minutes. The temperature was raised to 150 ° C. and reacted at 150 ° C. for 8 hours to obtain a prepolymer. The NCO group content of the obtained prepolymer was 3.2% and the viscosity was 550,0 at 25 ° C.
It was 00 cps.

Examples 2 to 4 and Comparative Example 1 In a 3 L reactor equipped with a stirrer, a thermometer, and a nitrogen introducing tube,
The polyether polyol or polyester polyol described in [Table 1] is used in parts by weight described in [Table 1], phthalic anhydride or maleic anhydride is used in parts by weight described in [Table 1], and triethylamine is selected in [Table 1]. In the same manner as in Example 1, the parts were charged and the reaction was carried out. The equivalent ratio of -CO.O.CO- of the carboxylic acid anhydride to -OH of the polyhydroxy compound is shown in [Table 1]. The acid value of the produced compound is shown in [Table 1]. Next, as in Example 1,
After charging the polyisocyanate described in [Table 1] in parts by weight described in [Table 1] and mixing and stirring at 50 ° C. for 30 minutes,
The temperature in the reactor was raised to the temperature shown in [Table 1] in 30 minutes, and the reaction was carried out at the temperature shown in [Table 1] for the time shown in [Table 1] to obtain a prepolymer. The NCO group content and viscosity of the obtained prepolymer are shown in [Table 1].

[0020]

[Table 1]

2. Cured Product Evaluation Reference Examples 1 to 5 Prepolymer 10 obtained in Examples 1 to 4 and Comparative Example 1
Degassed 0 parts by weight under reduced pressure at 100 ° C and 120 ° C in advance.
Melted methylene bis (o-chloroaniline) (MO
CA) or 2,4,6-tris (dimethylaminomethyl) -phenol (DMP-60) in parts by weight as shown in [Table 2], and after stirring and mixing so as not to involve bubbles, 1
A die (2
(00 mm × 200 mm × 2 mm) and cured at 100 ° C. for 24 hours. The results of physical property measurements according to JIS K-6301 are shown in [Table 2].

[0022]

[Table 2]

[0023]

The curable prepolymer of the present invention can be cured with an amine compound or an isocyanate polymerization catalyst, and the resulting cured product has high elasticity and excellent durability in the temperature range over 100 ° C. It is ideal for applications requiring high heat resistance and high elasticity such as papermaking rolls.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keisuke Fukuda 2-1, Tango-dori, Minami-ku, Nagoya-shi, Aichi Mitsui Toatsu Chemical Co., Ltd.

Claims (2)

[Claims] 1. A molecular terminal obtained by reacting an organic polyisocyanate compound with a compound having a carboxylic acid group at the molecular end obtained by reacting a carboxylic acid anhydride and a polyhydroxy compound. A curable prepolymer having an isocyanate group at the end. 2. A carboxylic acid anhydride --CO.O.CO--.
The curable prepolymer according to claim 1, wherein the carboxylic acid anhydride and the polyhydroxy compound are reacted at an equivalent ratio of 1 or more to the -OH group of the polyhydroxy compound.