JP3150379B2 - Curable 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 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 Conventionally, as a curable prepolymer from which an elastomer having high elasticity and heat resistance can be obtained, tolylene diisocyanate (hereinafter referred to as TDI) is used.
Naphthylene diisocyanate (hereinafter abbreviated as ND)
I) and an organic polyisocyanate compound such as polytetramethylene ether glycol, polyoxypropylene glycol, polyester polyol and the like, and a prepolymer having an isocyanate group at a molecular terminal obtained by reacting the compound with a polyhydroxy compound. And marketed under the trademark of Hyprene (manufactured by Mitsui Toatsu Chemicals, Inc.) and Vibracene (manufactured by Uniloyl).

In recent years, attempts have been made to improve the dynamic heat generation characteristics for the purpose of improving the heat resistance of an elastomer obtained by curing such a curable prepolymer with an amine compound. USP 4,556,703, U
SP 4,722,989 is a typical example, and discloses that the heat resistance is improved by making the composition distribution of the prepolymer as narrow as possible.

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

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

[0006]

The elastomer obtained from the urethane-based curable prepolymer has excellent abrasion resistance, mechanical strength, rebound resilience, etc.
Widely used for solid tires, belts, etc. However, it has a disadvantage that it melts and breaks due to internal heat generation when it receives a dynamic repetitive load. Urethane elastomers produced from prepolymers whose performance in terms of heat resistance are not sufficiently improved have a strong tendency for this, and there is much room for improvement.

It is an object of the present invention to provide a curable prepolymer from which a heat-resistant elastomer can be produced.

[0008]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that 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 is obtained. The inventors have found that the heat resistance of an elastomer obtained by adding and hardening a curing agent and the like is improved, and reached the present invention.

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

The carboxylic anhydride used in the present invention includes, for example, 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, by adding propylene oxide or ethylene oxide to water, ethylene glycol, propylene glycol, glycerin, or trimethylolpropane. And polyalkylene 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. The preferred range of the average molecular weight of these compounds is from 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)
Or a polyfunctional derivative or derivative of these isocyanates. These compounds can be used alone or as a mixture of two or more.

Method for Prepolymer Production First Step Reaction The reaction between the carboxylic anhydride and the polyhydroxy compound is as follows:
This is performed in a normal pressure system 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. If it is less than 1, the effect of improving heat resistance will be 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 from 100 to 120C. In this case, in order to shorten the reaction time, it is preferable to use an alkyl tertiary amine compound such as triethylamine and dimethylpalmitylamine as a catalyst, and among them, triethylamine is preferable. When a catalyst is used, the amount added is preferably less than 0.1% by weight based on the total raw materials. For example, when 0.05% by weight of triethylamine was used based on the total amount of the raw materials, the reaction time at a temperature of 100 ° C. was 3 hours.

Further, the carboxylic acid anhydride of -CO.OC.
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 anhydride or the catalyst is evaporated in a thin film. To remove. The evaluation of the reaction product is performed based on the acid value.

Second-Step Reaction The reaction between the compound having a carboxylic acid group at the molecular terminal generated in the first step and the organic polyisocyanate is carried out in an excess of isocyanate groups in a nitrogen gas stream at normal pressure. After the completion of the first-stage reaction, the temperature in the reactor is cooled to 50 ° C. or lower, and the entire amount of the organic polyisocyanate is charged. If 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 in an amount of 0.03% by weight based on the total amount of the raw materials, the reaction time at a temperature of 150 ° C. was 8 hours. NC for evaluation of reaction products
O%.

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

[0018]

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

Examples 2 to 4 and Comparative Example 1 A 3 L reactor equipped with a stirrer, thermometer and nitrogen inlet tube was
The polyether polyol or polyester polyol described in [Table 1] is represented by [Table 1] parts by weight, phthalic anhydride or maleic anhydride is represented by [Table 1] parts by weight, and triethylamine is represented by [Table 1]. And reacted in the same manner as in Example 1. The equivalent ratio between -CO.O.CO- of the carboxylic anhydride and -OH of the polyhydroxy compound is shown in [Table 1]. The acid value of the produced compound is shown in [Table 1]. Next, similarly to the first embodiment,
The polyisocyanate described in [Table 1] was charged in parts by weight described in [Table 1], and mixed and stirred at 50 ° C for 30 minutes.
The temperature in the reactor was raised to the temperature shown in [Table 1] over 30 minutes and reacted at the temperature shown in [Table 1] for the time shown in [Table 1] to obtain a prepolymer. The NCO group content and the viscosity of the obtained prepolymer are described in [Table 1].

[0020]

[Table 1]

2. Evaluation of cured product Reference Examples 1 to 5 Prepolymer 10 obtained in Examples 1 to 4 and Comparative Example 1
0 parts by weight was degassed under reduced pressure at 100 ° C.
Methylene bis (o-chloroaniline) (MO
CA) or 2,4,6-tris (dimethylaminomethyl) -phenol (DMP-60) is added by weight as described in [Table 2].
A mold (2) having a sheet thickness of 2 mm preheated to 00 ° C.
(00 mm × 200 mm × 2 mm) and cured at 100 ° C. for 24 hours. The results of measuring physical properties 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. The resulting cured product has high elasticity and excellent durability in a temperature range over 100 ° C. It is ideal for applications requiring high elasticity and heat resistance, such as papermaking rolls.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-49-129895 (JP, A) JP-A-60-69117 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 18 / 10,18 / 32,18 / 42

Claims (2)

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