JPH0768323B2 - Method for producing room temperature curable urethane elastomer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a room temperature curable urethane elastomer useful as a sealing material, a casting material, a filling material, an impact absorbing material, a vibration damping material and the like.

[Prior art]

Room temperature curing type urethane elastomer is a casting material, a waterproof material, a sealing material, a floor material, and a filling material because it has rubber elasticity in addition to excellent properties such as weather resistance, abrasion resistance, oil resistance and adhesiveness. Or, it is widely used as a synthetic leather or the like in various fields such as civil engineering, construction, automobiles, electric appliances and the like.

In particular, sealing materials, filling materials, shock absorbing materials, and anti-vibration materials are required to have low modulus and high elongation properties so that they can expand and contract according to changes in members, and urethane elastomers are ideal for those applications. .

As a material having such characteristics, a prepolymer having an isocyanate group at an end (hereinafter referred to as a prepolymer), which is generally obtained from a high molecular weight polyol and an organic polyisocyanate, is used as a main component, and a high molecular weight polyol and a relatively low molecular weight polyol are A urethane elastomer in which a mixture of polyamines is used as a curing agent and, if necessary, a filler, a pigment, a diluent, a catalyst, an antiaging agent and the like are mixed is used.

[Problems to be solved by the invention]

The characteristics of low modulus and high elongation have functions such as absorption of deformation and increase of safety due to dispersion of concentrated stress, and their effects on sealing materials, filling materials, shock absorbing materials, vibration damping materials, etc. are remarkable.

Conventionally, when trying to obtain a room temperature curable urethane elastomer, as an organic polyisocyanate, mainly a prepolymer using tolylene diisocyanate (hereinafter referred to as TDI) has been used as a main agent, but TDI has a high vapor pressure, Moreover, since it is highly toxic as specified in the second class of specified chemical substances, it was not always considered to be preferable in terms of handling and environmental hygiene.

On the other hand, 4,4'-diphenylmethane diisocyanate (hereinafter referred to as MDI
Is used.

Since this MDI has excellent mechanical properties and good durability, it may be used as a part of auxiliary agent for room temperature curing type urethane elastomer, but it is used only in combination with TDI. There wasn't.

The appearance of high elongation urethane elastomers containing MDI as a main component has been widely expected from the past, but no one satisfying this has yet to appear, and a method of heat curing using a slightly high molecular weight polyol as a crosslinking agent has been proposed. It was only known.

As a urethane elastomer with a low modulus and a high elongation property, a room temperature curable one using a safe material has not been proposed so far, and in terms of energy saving, simplification of work process, site workability, etc. Their appearance is strongly expected.

[Object of the Invention]

The present inventors have tried to cope with this in view of the above-mentioned circumstances, do not cause toxicity during manufacturing, are safe from the viewpoint of environmental hygiene, and have a low modulus and a high elongation property, and are at room temperature. It is an object of the present invention to provide a novel method for producing a room temperature curable urethane elastomer that can be cured.

Another object of the present invention is to provide a method for producing a room temperature-curable elastic urethane elastomer having an extremely excellent impact absorption property by adding a certain amount of a diluent to the above elastomer.

[Main points of the invention]

The present invention, as a high molecular weight polyol, average molecular weight 3000 ~
8,000 triols and 4, as an organic polyisocyanate
A prepolymer having an isocyanate group at the terminal obtained from 4'-diphenylmethane diisocyanate is blended with a caprolactone-based polyol having an average molecular weight of 300 to 1200 as a cross-linking agent, and a method for producing a urethane elastomer obtained by curing the mixture at room temperature is described. This is the main point of the invention.

〔Example〕

 Specific examples of the present invention will be described below.

That is, the present invention is a room temperature curable MDI urethane elastomer, that is, a prepolymer having an isocyanate group at the terminal obtained from a high molecular weight polyol and an organic polyisocyanate, a relatively low molecular weight caprolactone polyol is blended as a crosslinking agent. The high elongation urethane elastomer is obtained by curing the mixture at room temperature.

The polymer polyol used in the present invention has an average molecular weight of 3,000 to 8,000, preferably 4,000 to 3,000, which has three hydroxyl groups in one molecule.
6000 triols may be commercially available, for example, polyoxyalkylene triol obtained by adding one or more kinds of ethylene oxide, propylene oxide, butylene oxide and the like to glycerin, methylolpropane or hexanetriol. Can be mentioned.

When the average molecular weight of triol exceeds 8,000, the total degree of unsaturation increases, and as a result, the average number of functional groups also decreases, and it becomes difficult for the resulting urethane elastomer to exhibit its properties as a sealing material or the like. Further, if the average molecular weight is less than 3000, the elongation of the obtained urethane elastomer decreases, which is not preferable.

Furthermore, the prepolymer having an isocyanate group at the terminal used in the present invention is the above-mentioned high molecular weight triol and 4,
It is preferable that 4'-diphenylmethane diisocyanate is reacted by a known technique to have 5 to 15% by weight, preferably 7 to 10% by weight, of isocyanate groups at the terminals.

If the free isocyanate group content exceeds 15% by weight, the elongation of the obtained urethane elastomer decreases, which is not preferable, and if the free isocyanate group content is less than 5% by weight, the viscosity of the prepolymer increases. , It causes troubles in the production of urethane elastomer.

Further, the crosslinking agent used in the present invention, ethylene glycol, propylene glycol, butylene glycol, glycerin, trimethylolpropane, polyhydric alcohols such as pentaerythritol, or ethylene oxide, propylene oxide, butylene oxide,
A caprolactone-based polyester polyol which is a reaction product of a caprolactone and a polyether polyol having a hydroxyl group at the terminal obtained by addition-polymerizing one or more alkylene oxides such as tetrahydrofuran, and an average molecular weight of 300 to 1200, preferably 500. ~ 1000.

If the average molecular weight exceeds 1200, the reaction activity becomes low at room temperature, which is not preferable as a cross-linking agent.
If it is less than 100%, the elongation of the urethane elastomer is lowered, which is not preferable.

When a polyoxyalkylene polyol having the same molecular weight and the same number of functional groups is used as a cross-linking agent, it cannot be cured at room temperature and only a sufficient urethane elastomer can be obtained by heat curing.

Only when a caprolactone-based polyol is used, a room temperature curable urethane elastomer having low modulus and high elongation properties can be obtained.

In order to obtain the above-mentioned urethane elastomer, its accurate theoretical support cannot be mentioned, but in addition to the activity of the terminal primary hydroxyl group of the caprolactone-based polyol,
It is presumed that the strong secondary bondability promotes resinification, and that the slip of the secondary bond contributes to the peculiar high elongation property with respect to the stress acting on the urethane elastomer.

As the urethanization catalyst, those used in ordinary urethanization reactions, that is, tertiary amine compounds and organometallic compounds are used, and examples thereof include triethylenediamine, diazabicycloundecene, N-methylmorpholine, NN-dimethyl. Ethanolamine, tin octylate, tin laurate and the like can be mentioned, and the amount thereof can be widely varied depending on the desired reaction rate.

If necessary, inorganic fillers may be used. Examples of these inorganic fillers include fumed silica, precipitated silica, silicic acid anhydride, reinforcing fillers such as carbon black, calcium carbonate, magnesium carbonate and diatomaceous filler. Fillers such as soil, calcined clay, clay, talc, titanium oxide, bentonite, organic bentonite, ferric oxide, and shirasu balloon, fibrous fillers such as glass fibers and filaments.

Further, in the present invention, a diluent can be used if necessary.

As the diluent to be used, conventional diluents, for example, phthalic acid esters such as dioctyl phthalate and dibutyl phthalate; aliphatic second basic esters such as dioctyl adipate, isodecyl succinate and dibutyl sebacate; diethyl glycol benzoate , Fatty acid esters such as pentaerythritol ester; phosphoric acid esters such as tricresyl phosphate and trioctyl phosphate;
Paraffin chloride and the like can be mentioned.

Further, as other additives, a defoaming agent, an ultraviolet absorber, an antioxidant, a pigment or the like can be used if necessary.

Hereinafter, examples in which the present invention is specifically carried out will be given together with comparative examples, and a concrete comparison of the composition and the physical properties will be shown in Table 1 below.

However, the present invention is not limited to the examples given above.

Example 1 Polyoxypropylene triol 100 having an average molecular weight of 5000
And 53.2 parts of 4,4′-diphenylmethane diisocyanate were reacted at 80 ° C. for 3 hours to give a free isocyanate group content.
A prepolymer having a weight percentage of 9.6% and a viscosity of 8700 cps (23 ° C.) was obtained.

52.9 parts of caprolactone-based polyol having an average molecular weight of 500 to 100 parts of the above prepolymer (main ingredient) (trade name: Praxel L
-205AL / Daicel Chemical Co., Ltd.) and tin laurate
After mixing 0.005 parts (curing agent), the mixture was allowed to stand at room temperature for 24 hours to obtain a urethane elastomer.

(Example 2) 86.7 parts of caprolactone-based polyol having an average molecular weight of 800 (manufactured by Praxel L-208AL, manufactured by Daicel Chemical Co., Ltd.) was added to 100 parts of the prepolymer shown in Example 1 (main ingredient).
And 0.005 parts tin laurate (curing agent), and then mix at room temperature.
After standing for 4 hours, a urethane elastomer was obtained.

Comparative Example 1 100 parts of the prepolymer shown in Example 1 (base compound) was mixed with 51.9 parts of polyethylene glycol having an average molecular weight of 500 and 0.002 part of tin laurate (curing agent), and the mixture was allowed to stand at room temperature for 24 hours to obtain urethane. An elastomer was obtained.

(Comparative Example 2) 100 parts of the prepolymer shown in Example 1 (base compound) was mixed with 83.1 parts of polyethylene glycol having an average molecular weight of 800 and 0.02 part of tin laurate (curing agent), and the mixture was allowed to stand at room temperature for 24 hours to obtain urethane. An elastomer was obtained.

(Comparative Example 3) 100 parts of the prepolymer shown in Example 1 (main component) was mixed with 1,4-
After mixing 9.1 parts of butanediol and 0.005 part of tin laurate (curing agent), the mixture was allowed to stand at room temperature for 24 hours to obtain a urethane elastomer.

(Comparative Example 4) 100 parts of the prepolymer shown in Example 1 (main component) was mixed with 3,3 '
After mixing 27.8 parts of -dichloro-4,4'-diaminophenylmethane and 0.005 part of tin laurate (hardening agent), mix at room temperature for 24 hours.
After standing for a time, a urethane elastomer was obtained.

(Comparative Example 5) 100 parts of the prepolymer shown in Example 1 (main component) was mixed with 1,4-
After mixing 7.5 parts of butanediol, 32.8 parts of polyoxypropylene glycol having an average molecular weight of 3000, 32.8 parts of polyoxypropylene triol having an average molecular weight of 5000 and 0.02 part of tin laurate (curing agent), the mixture is allowed to stand at room temperature for 24 hours to give a urethane elastomer. Obtained.

(Comparative Example 6) 100 parts of the prepolymer shown in Example 1 (main component) was mixed with 3,3 '
18.5 parts of -dichloro-4,4'-diaminophenylmethane,
Polyoxypropylene glycol with an average molecular weight of 3000 54.8
Parts, polyoxypropylene triol with an average molecular weight of 5000
After mixing 54.8 parts and tin laurate 0.02 part (curing agent), the mixture was allowed to stand at room temperature for 24 hours to obtain a urethane elastomer.

[Effects of the invention] As is clear from Table 1, when polyethylene glycol having the same molecular weight is used as the cross-linking agent, it is not possible to obtain a sufficiently satisfactory urethane elastomer by room temperature curing, and most of the cross-linking agents are used. Often used
Even when 1.4-butanediol or 3.3-dichloro-diaminophenylmethane was used, it was not possible to obtain a urethane elastomer having low modulus and high elongation properties.

Further, the above-mentioned general-purpose crosslinking agent 1,4-butanediol or
In the cross-linking agent using 3,3-dichloro-diaminophenylmethane and high-molecular-weight polyoxyalkylene polyol in combination, the elongation is 700 although the decrease in modulus is recognized.
% Urethane urethane was not obtained.

Contrary to this, the present invention, in urethane elastomers obtained from prepolymers based on MDI, by using a relatively low molecular weight caprolactone-based polyol as a cross-linking agent, could not be obtained until now by room temperature curing. It is now possible to manufacture urethane elastomers with low modulus and high elongation characteristics, and it is extremely effective urethane as a sealing material, casting material, filling material, shock absorbing material, vibration damping material, etc. It has an excellent characteristic that it is possible to provide an elastomer.

Claims (2)

[Claims] 1. An average molecular weight of 3000 as a high molecular weight polyol.
~ 8,000 triols and as an organic polyisocyanate
A urethane elastomer characterized in that a prepolymer having an isocyanate group at the terminal obtained from 4,4′-diphenylmethane diisocyanate is blended with a caprolactone-based polyol having an average molecular weight of 300 to 1200 as a crosslinking agent, and these mixtures are cured at room temperature. Manufacturing method. 2. The method for producing a room temperature curable urethane elastomer according to claim 1, wherein the isocyanate group content in the prepolymer is 5 to 15%.