JP3078065B2 - Room temperature curable composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a room temperature curable composition which cures to a rubbery state by reacting with moisture in the atmosphere, and in particular, has excellent slump properties, a low curing rate, and excellent properties after curing. Room temperature curable composition useful as a sealing material.

[0002]

2. Description of the Related Art As a polymer which reacts with moisture in the atmosphere to cure into a rubbery state, for example, as disclosed in Japanese Patent Application Laid-Open No. 50-156599, an oxy group having an ether type allyl olefin group at its terminal is disclosed. In the presence of a Group VIII transition metal, an alkylene polymer is reacted with a compound of the general formula (I) wherein R is a monovalent hydrocarbon group or a halogenated monovalent hydrocarbon group,
a represents an integer of 0, 1 or 2, and X represents a halogen atom, an alkoxy group, an acyloxy group or a ketoxmate group. )), And a polyether having a hydrolyzable silyl group at a terminal obtained by reacting with the hydrosilicon compound represented by the formula (1).

[0003]

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[0004] In order to impart slump properties (anti-sagging properties) to such polymers, thixotropic agents such as anhydrous silica, fatty acid bisamide, castor oil with water and precipitated calcium carbonate are generally added.

[0005] However, when anhydrous silica is used as a thixotropic agent, if an amount necessary to impart sufficient slump properties is added, the polymer after curing becomes brittle, and
The disadvantage of anhydrous silica being very expensive is that the composition is expensive.

[0006] When fatty acid bisamide or castor oil with water is used as a thixotropic agent, thixotropicity does not occur unless the composition is heated to a high temperature in a mixing tank to be in a semi-molten state. The disadvantages are that the production cost increases and the viscosity during storage is not stable.

[0007] When sedimentable calcium carbonate is used as a thixotropic agent, the sedimentable calcium carbonate contains a large amount of water due to production problems, and it is difficult to remove the water even after drying. There is a disadvantage that the storage stability of the obtained polymer is not good.

Further, the water content of the precipitated calcium carbonate can be removed by a dehydrating agent such as vinyltrimethoxysilane or tetraethoxysilane. However, a large amount of the dehydrating agent must be used, so that the curing speed is remarkably high. It has the disadvantage of being slow and expensive.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and has as its object to minimize the use of a dehydrating agent which has excellent thixotropic properties and excellent elongation performance of a cured product and inhibits the curing speed. It is an object of the present invention to provide a room-temperature-curable composition having rapid curability by suppressing the temperature to a minimum.

[0010]

The room-temperature-curable composition of the present invention comprises a polymer (A) 100 whose main chain is essentially a polyether and has a crosslinkable hydrolyzable silyl group at the terminal.
It is characterized by comprising 90 to 300 parts by weight of heavy calcium carbonate (B) having a specific surface area of 20,000 cm ² / g or more and 0.1 to 10 parts by weight of a curing catalyst, thereby achieving the above object. Is done.

Hereinafter, the present invention will be described in detail. The polymer (A) used in the present invention is a polymer whose main chain is essentially a polyether and has a crosslinkable hydrolyzable silyl group at a terminal.

[0012] Such a polyether is, for example, as described in JP-A-50-156599,
In the presence of a Group VIII transition metal, an oxyalkylene polymer having an ether type allyl olefin group at the terminal is converted to a compound represented by the general formula (I) (wherein R is a monovalent hydrocarbon group or a halogenated monovalent hydrocarbon) A is an integer of 0, 1 or 2;
X represents a halogen atom, an alkoxy group, an acyloxy group or a ketoximate group. )).

[0013]

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[0014] The molecular weight of the polymer (A) is preferably in the range of 4,000 to 30,000, because the smaller the molecular weight, the more brittle the cured product, and the higher the molecular weight, the higher the viscosity, which impairs workability.

As the polymer (A), for example, a commercially available product, "Silyl 5A03" manufactured by Kanegafuchi Chemical Co., Ltd. can be used. As the polymer (A), those whose main chain is essentially polyoxypropylene are preferable, and those whose crosslinkable hydrolyzable silyl group at the terminal of the main chain is an alkoxysilyl group are preferable.

The heavy calcium carbonate (B) used in the present invention cannot impart good thixotropic properties to the composition when the specific surface area is small, and the resulting cured product becomes brittle. Those having a specific surface area of 20,000 cm ² / g or more are used, and preferably have a specific surface area of 25,000 c
m ² / g or more.

The heavy calcium carbonate (B) is
Those that have not been subjected to surface treatment are preferred. In the present invention, when the added amount of the heavy calcium carbonate (B) is small, good thixotropic properties are not imparted to the composition, and the obtained cured product becomes brittle. Conversely, when the added amount is large, the viscosity becomes high. As a result, the workability is deteriorated, and mixing with the polymer (A) is stopped.
It is limited to 0 to 300 parts by weight.

As the curing catalyst of the present invention, a silanol condensation catalyst is preferable. For example, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin diacetylacetonate, tin octylate and the like are used.

When the amount of the curing catalyst added is small, a sufficient catalytic effect cannot be obtained, and when the amount is more than a certain amount, the catalytic effect becomes saturated. Therefore, based on 100 parts by weight of the polymer (A),
It is limited to 0.1 to 10 parts by weight.

The composition of the present invention may contain one or more fillers such as magnesium carbonate, hydrous silicic acid, anhydrous silicic acid, calcium silicate, silica, titanium dioxide, clay, talc and carbon black. It may be used in a mixture.

Further, a plasticizer may be added in order to increase the elongation of the cured product of the composition of the present invention or to reduce the modulus of the cured product. Examples of the plasticizer include phosphoric acid esters such as tributyl phosphate and tricresyl phosphate; phthalic acid esters such as dioctyl phthalate; fatty acid monobasic acid esters such as glycerol monooleate; dibutyl adipate; The basic acid esters are used alone or in a mixture of two or more.

Further, in addition to the above-mentioned filler and plasticizer, for example, a pigment, an ultraviolet absorber, an antioxidant and the like may be added to the composition of the present invention as needed.

[0023]

The room temperature curable composition of the present invention has a specific surface area of 20,
By adding heavy calcium carbonate of 000 cm ² / g or more, it has excellent thixotropic properties and can give a cured product excellent elongation performance. In addition, since heavy calcium carbonate has a low water content and can be dried relatively easily, the use of a dehydrating agent such as vinyltrimethoxysilane can be suppressed to a very small amount, and The fast-curing properties are not impaired.

[0024]

Embodiments of the present invention will be described below. (Examples 1 to 3, Comparative Examples 1 to 3) 1) Preparation of Room Temperature Curable Composition Polymer (A) whose main chain is essentially a polyether and has a crosslinkable hydrolyzable silyl group at a terminal. As "Silyl 5A03" (Kanebuchi Chemical Co., Ltd.) (number average molecular weight 8500)
And calcium carbonate having a specific surface area shown in Table 1 was preliminarily dried at 120 ° C. for 2 hours before use.

The polymer (A), calcium carbonate and a plasticizer (dioctyl phthalate) were mixed at the ratio shown in Table 2 and kneaded with a three-roll mill. Next, the above kneaded material was dried under reduced pressure for 3 hours, and then a dehydrating agent (vinyltrimethoxysilane) and a curing catalyst (dibutyltin diacetylacetonate) in the proportions shown in Table 2 were added to prepare a room-temperature curable composition. did. 2) Physical properties of the room temperature curable composition (a) Tack-free and slump Both were evaluated according to JIS A-5758.

The slump was evaluated as ○ when the droop was 3 mm or less, and as × when the droop exceeded 3 mm. (B) Storage stability After being kept in a sealed state and allowed to stand at 50 ° C. for one week, the viscosity was measured with a B-type viscometer.

With the blank immediately after the preparation as a blank, those with a change in viscosity after one week of 1.3 times or less were rated as ○, and those with a change in viscosity of more than 1.3 times were rated as x. 3) Physical properties of cured product of room temperature curable composition The room temperature curable composition was spread to a thickness of about 2 mm,
A sample cured for one week under the condition of 60% RH was subjected to JIS K6301 (No. 3 dumbbell, tensile speed of 50).
mm / min), the 50% modulus, the maximum stress and the maximum elongation were measured, and the results are shown in Table 2.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

According to the present invention, the specific surface area is 20,000.
By adding heavy calcium carbonate of not less than cm ² / g, a room-temperature curable composition having excellent thixotropic properties can be obtained, and the cured product can have excellent elongation performance.

In addition, heavy calcium carbonate contains a small amount of water due to its production method and can be easily dried, so that the amount of a dehydrating agent that inhibits curability can be suppressed to a very small amount. A room-temperature-curable composition having rapid curability can be obtained.

Claims (1)

(57) [Claims] 1. The method according to claim 1, wherein the main chain is essentially a polyether.
Polymer having a crosslinkable hydrolyzable silyl group at the end
(A) 100 parts by weight, specific surface area 20,000 cm ^Two/ G
90 to 300 parts by weight of the above heavy calcium carbonate (B)
And 0.1 to 10 parts by weight of a curing catalyst.
Room temperature curable composition.