JPS6315935B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyurethane composition for obtaining a cured product that uses a liquid diene polymer and has excellent elasticity and low-temperature properties, as well as excellent low heat generation properties. BACKGROUND ART Recently, there has been a strong demand for simplifying manufacturing processes and improving productivity in tires for vehicles such as automobiles, anti-vibration rubber, etc., and it has been proposed to use liquid rubber instead of solid rubber. Furthermore, there is a strong demand for safety in automobile tires, and non-puncture tires have been proposed to prevent tire blowouts that directly lead to car accidents. This non-puncture tire is a pneumatic tire filled with an elastomer, and filling it with a polyurethane elastomer is being considered. However, all of these uses require excellent physical properties, and in addition to the elastic properties of rubber, low-temperature properties, especially excellent low heat generation properties, are required. A liquid composition for obtaining the body has not been obtained. The present inventors have conducted extensive research to obtain a cured product that has low heat generation properties without impairing the excellent properties originally possessed by liquid diene polymers, and as a result, the terminal isocyanate precipitates identified We have discovered that a polyurethane composition in which a polymer is prepared in advance through a reaction and a castor oil-based polyol having a specified hydroxyl group equivalent or a plasticizer is added to this prepolymer becomes a cured product with excellent low heat generation properties. The invention was completed. That is, the present invention provides a terminal isocyanate obtained by reacting (A) two or more compounds containing a liquid polybutadiene containing a terminal hydroxyl group with polyoxypropylene glycol and/or a castor oil-based polyol, and (B) an organic diisocyanate. Prepolymer and hydroxyl equivalent weight 220 to 500
The present invention relates to a polyurethane composition formed by blending a trifunctional or higher functional castor oil polyol, or a polyurethane composition formed by further blending a plasticizer with this composition. The polyurethane composition according to the present invention is based on a composition consisting of a terminal isocyanate prepolymer containing at least liquid polybutadiene and a trifunctional or higher functional castor oil polyol having a hydroxyl equivalent of 220 to 500, and is formed by a urethane reaction. This gives an elastic hardened body. The present invention will be specifically explained below. The terminal isocyanate prepolymer in the present invention is a compound containing a liquid polybutadiene that essentially contains a terminal hydroxyl group-containing liquid polybutadiene, and optionally contains a polyoxypropylene glycol (including an ethylene oxide adduct) and a castor oil polyol alone or in combination. It can be obtained by reaction with a diisocyanate compound. The liquid diene polymer in the present invention is a liquid polybutadiene containing terminal hydroxyl groups, and has a number average molecular weight of 500 to 500.
25,000. In the present invention, a prepolymer is basically obtained by reacting this liquid polybutadiene with an organic diisocyanate compound, but it also includes the combined use of a polyether polyol and a castor oil polyol as the polyhydroxy compound. . Examples of the polyether polyol include polyoxypropylene glycol and its ethylene oxide adduct. The amount of ethylene oxide added is usually 30% by weight or less. Castor oil polyol is known as an esterified product of ricinoleic acid and polyhydric alcohol (glycerin, trimethylolpropane, pentaerythritol, etc.). Specifically, an esterified product obtained by adding propylene oxide and/or ethylene oxide to a polyhydric alcohol and then reacting it with ricinoleic acid, or an esterified product obtained by reacting ricinoleic acid and a polyhydric alcohol with ethylene oxide and / or products obtained by adding propylene oxide. In any case, the polyhydroxy compound used in the prepolymer of the present invention has two to three functional groups. Next, examples of organic diisocyanate compounds include conventional aromatic, aliphatic and alicyclic compounds, such as tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, liquid modified diphenylmethane diisocyanate, and polymethylene diisocyanate. Examples include polyphenyl isocyanate, xylylene diisocyanate, cyclohexyl diisocyanate, cyclohexanephenylene diisocyanate, naphthalene-1,5-diisocyanate, isopropylbenzene-2,4-diisocyanate, and addition reaction products of polypropylene glycol and tolylene diisocyanate. The reaction for obtaining the terminal isocyanate prepolymer is usually carried out under conditions of an inert gas flow such as dry nitrogen, a reaction temperature of 30 to 100°C, and a reaction time of 10 minutes to 10 hours. The isocyanate group content of this prepolymer is preferably in the range of 5 to 15% by weight. The polyurethane composition of the present invention comprises a trifunctional or higher functional castor oil polyol having a hydroxyl equivalent of 220 to 500, preferably 270 to 450, with respect to the terminal isocyanate prepolymer, and an NCO/OH ratio of the polyurethane composition of the present invention.
It is blended so that the ratio is 0.8 to 1.5, preferably 0.9 to 1.1. In the present invention, it is necessary to use a product whose hydroxyl equivalent (molecular weight per hydroxyl group) is within a specified range. It is not possible to obtain an elastic cured body with heat generating properties. In particular, this is the most important point for this composition because if the hydroxyl equivalent exceeds the range of the present invention, the exothermic properties will deteriorate rapidly. The castor oil polyol used here is as described above as a raw material for the prepolymer, and has three or more functional groups. Usually, three functional groups are used. In the composition of the present invention, it is essential that the terminal isocyanate prepolymer contain a liquid diene polymer chain. Therefore, for example, if a hydroxyl group-containing liquid diene polymer is used as a raw material for a polyhydroxy compound, it is not possible to obtain the desired elastic cured product of the present invention. However, this does not limit the use of a part of the castor oil polyol, for example, a liquid diene polymer in an amount of 40% by weight or less, as a raw material for the polyhydroxy compound. It is also possible to use castor oil diol in combination as a raw material for the polyhydroxy compound. As detailed above, the polyurethane composition of the present invention has excellent low heat build-up properties, but it is clear that the low heat build-up properties are further improved by adding a plasticizer to the composition. Summer. Therefore, the present invention includes the invention of a polyurethane composition containing a plasticizer. Plasticizers used here include phthalates such as dioctyl phthalate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, butylbenzyl phthalate, adipates such as dioctyl adipate, sebacates such as dioctyl sebacate,
These include phosphates such as tris dichloropropyl phosphate and cresyl phenyl phosphate, naphthenic oils, aroma oils, and alkyl aroma oils. The amount of these plasticizers added is preferably 30% by weight or less, particularly preferably 10 to 20% by weight. The method of adding these plasticizers is not particularly limited, and they can be added, for example, during the production of prepolymers. The polyurethane composition of the present invention is usually heated under heating.
By adding a catalyst as necessary, the product is cured by reaction to obtain an elastic product. Examples of the catalyst used here include urethane catalysts such as di-n-butyltin dilaurate, stannath octoate, triethylenediamine, diethylenediamine, triethylamine, naphthenic acid metal salts, and octylic acid metal salts. Furthermore, pigments, stabilizers, fillers, etc. can be added if necessary. As detailed above, the polyurethane composition of the present invention has the elasticity of a liquid diene polymer and excellent properties at low and high temperatures, and also produces an elastic cured product that has extremely low heat generation properties and moderate hardness. This makes it possible to develop new uses for liquid diene polymers. In particular, when a non-puncture safety tire is desired, a safety tire can be obtained by filling a pneumatic tire with the composition of the present invention instead of air and curing the composition. Tires are subjected to severe conditions, and due to dynamic heat generation in particular, conventional liquid elastomers are not sufficiently satisfactory.The present invention makes it possible to obtain satisfactorily safe tires for the first time. be. In addition, we can easily manufacture a wide range of products such as vibration-proof materials where dynamic heat generation is a problem.
Moreover, it enables efficient manufacturing with good productivity. Hereinafter, the present invention will be explained in more detail with reference to Examples. Examples 1 to 4, Reference Examples 1 to 6 Liquid polybutadiene containing terminal hydroxyl groups (number average molecular weight 2800, viscosity 50 poise (30°C), hydroxyl group content
Dry 100 parts by weight of a 60:40 mixture of 0.83meq/g) and polyoxypropylene glycol (number average molecular weight 3000) and 60.4 parts by weight of a liquid modified product of 4,4-diphenylmethane diisocyanate (NCO content 28.75% by weight). The reaction was carried out at 40°C for 3 hours in a nitrogen atmosphere to obtain a terminal isocyanate prepolymer. The NCO content of this prepolymer was 9.0% by weight. Various castor oil-based polyols were added to this prepolymer so that the NCO/OH ratio was 1.05, and di-n-butyltin dilaurate was added as a catalyst at 0.07% by weight based on the prepolymer, and a plasticizer was added and mixed with stirring. After foaming, it was poured into a mold and post-cured at 120°C for 12 hours to create a cured product. Various tests were conducted using this cured product, and the measurement results are shown in Table 1. Furthermore, the influence of the hydroxyl equivalent of the castor oil polyol on the dynamic heat generation is shown in FIG. From FIG. 1, it is clear that when the hydroxyl equivalent of the castor oil-based polyol is in the range of 220 to 500, the exothermic temperature is extremely low and excellent. In addition, various test methods were performed according to the following methods. (a) Dynamic heat build-up (ASTM D-623) Temperature: 100°C, Stroke: 0.175 inch, Load: 22 lbs, Frequency: 1800 rpm Test time: 25
Minutes (b) Permanent strain Calculated from the following formula using samples before and after measurement with a flexometer. The height after the test was measured after the test was left at room temperature for 24 hours. Permanent strain [%] = (Height of sample before test) - (
Height of sample after test) / Height of sample before test x 100 (c) Tensile strength, elongation, 50% modulus: JIS K-
6301 (d) Tear strength: JIS K-6301 (e) Hardness: JIS K-6301 (f) Repulsion modulus: JIS K-6301

[Table] Examples 5 to 6 Polyols having the formulation shown in Table 2 and liquid modified MDI (4,4-diphenylmethane diisocyanate, liquid modified product, NCO content 28.75% by weight) or TDI (tolylene diisocyanate) 3 hours at 40°C in a dry nitrogen atmosphere (80°C in the case of Example 5)
(for 6 hours) to obtain a terminal isocyanate prepolymer. The NCO content of this prepolymer is
It was 9.0% by weight. This prepolymer was added with purified castor oil (functional group =
3. Viscosity 700cps/25℃, hydroxyl equivalent = 344)
The NCO/OH ratio was added to be 1.05, and the results of measurements conducted in accordance with Example 1 are shown in Table 2.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a graph showing the influence of the hydroxyl equivalent of a castor oil polyol on dynamic heat generation.

Claims (1)

[Claims] 1. A compound obtained by reacting two or more compounds containing (A) a liquid polybutadiene obtained by adding polyoxypropylene glycol and/or a castor oil polyol to a liquid polybutadiene containing terminal hydroxyl groups, and (B) an organic diisocyanate. A polyurethane composition prepared by blending a terminal isocyanate prepolymer with a trifunctional or higher functional castor oil polyol having a hydroxyl equivalent of 220 to 500. 2. (A) A terminal isocyanate prepolymer obtained by reacting two or more compounds containing a liquid polybutadiene obtained by adding polyoxypropylene glycol and/or castor oil-based polyol to a terminal hydroxyl group-containing liquid polybutadiene and (B) an organic diisocyanate. A polyurethane composition containing a trifunctional or higher functional castor oil polyol having a hydroxyl equivalent of 220 to 500 and a plasticizer. 3. The polyurethane composition according to claim 2, wherein the plasticizer is a phthalate plasticizer.