JPH06329896A - Room temperature curing composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition suitable for sealing material, etc., having high curing rate, excellent storage stability and tensile physical properties comprising a specific polymer, prescribed ground limestone and a specific curing catalyst in a prescribed ratio. CONSTITUTION:The objective composition comprises (A) 100 pts.wt. of a polymer composed of a main chain being essentially a polyether, containing a vulcanizable hydrolyzable silyl group at the end, having 4,000-30,000 molecular weight, (B) >=30 pts.wt. of ground limestone having >=15,000cm<2>/g specific surface are, treated with an organic substance such as higher fatty acid-based organic substance and (C) 0.1-10 pts.wt. of a curing catalyst such as dibutyltin dilaurate.

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 is cured at room temperature into a rubber by reacting with moisture in the atmosphere, and particularly to a room temperature curable composition useful as a sealing material having excellent physical properties after curing. Regarding things.

[0002]

2. Description of the Related Art As a polymer which is cured into a rubber by reacting with moisture in the atmosphere, for example, as described in JP-A-58-41291, an oxy group having an ether type allyl olefin group at its end is used. Alkylene polymer VIII
In the presence of a group transition metal, a compound of the general formula X _3-a SiR _a H (wherein R is a group selected from a monovalent hydrocarbon group and a halogenated monovalent hydrocarbon group, a is 0, 1 or 2, X Is a group or atom selected from a halogen atom, an alkoxy group, an acyloxy group and a ketoximate group.), And is obtained by reacting with a hydrosilicon compound represented by
Polyethers having a hydrolyzable silyl group at the end have been proposed.

A curable composition containing such a polymer has excellent performance, but depending on the compounding composition,
Workability and tensile properties after curing (low modulus, high elongation) are insufficient. Therefore, in order to particularly improve the elongation property, for example, as described in JP-A-59-138259, the use of easily dispersible cubic calcium carbonate having an average particle diameter of 0.01 to 1.0 μm is preferred. Proposed.

[0004]

However, as described in the above publication, the easily dispersible cubic calcium carbonate is a precipitated calcium carbonate, and when such a precipitated calcium carbonate is used, it is synthesized. Due to the problem of the method, it contains a lot of water, and even if it is dried, the water cannot be removed so much, and there is a problem in storage stability. Further, when a dehydrating agent such as vinyltrimethoxysilane or tetraethoxysilane is used, a large amount is required due to the amount of water, and there is a problem that the curing speed becomes extremely slow and the cost becomes very high. .

The present invention solves the above conventional problems, and provides a room temperature curable composition which is useful as a sealant having a high curing rate, excellent storage stability and excellent physical properties after curing. It was made for the purpose of doing.

[0006]

According to the present invention, a polymer (A) having a main chain essentially of a polyether and having a crosslinkable hydrolyzable silyl group at a terminal and having a molecular weight of 4,000 to 30,000. 100 parts by weight and specific surface area 15,000 cm ²
30 g by weight or more of heavy calcium carbonate (B) whose surface is treated with an organic substance in an amount of / g or more, and a curing catalyst (C) of 0.1
It is a room temperature curable composition consisting of 10 to 10 parts by weight.

As the polymer (A) used in the present invention, for example, an oxyalkylene polymer having an ether type allyl olefin group at the terminal is represented by the general formula X _3-a SiR _a H (In the formula, R is a group selected from a monovalent hydrocarbon group and a halogenated monovalent hydrocarbon group, a is 0, 1 or 2, X is a group selected from a halogen atom, an alkoxy group, an acyloxy group and a ketoximate group, or Obtained by reacting with a hydrosilicon compound represented by
A polyether having a hydrolyzable silyl group at the terminal and having a molecular weight of 4,000 to 30,000 is used.

When the molecular weight of the polymer (A) is less than 4,000, the elongation of the cured product obtained is not sufficient, and conversely,
If it exceeds 30,000, the viscosity will be too high and the workability in the compounding step will decrease.

In the present invention, the heavy calcium carbonate (B) used has a specific surface area of 15,000 cm ² / g or more, preferably 18,000 cm ² / g or more, and the surface of which is treated with an organic substance. To be done. If the specific surface area is less than 15,000 cm ² / g, a cured product having good tensile properties cannot be obtained.

As the heavy calcium carbonate (B), calcite-type crystalline limestone is mechanically crushed and further classified, and the heavy calcium carbonate having a large specific surface area, that is, particles. Those having a small diameter and whose surface is treated with an organic substance are preferably used.

[0011] Heavy calcium carbonate does not contain much water like precipitated calcium carbonate and therefore can be easily dried,
Since it is easy to dry, trace amounts of dehydrating agents such as vinyltrimethoxysilane and tetraethoxysilane can be used, so curable substances that have little effect of such dehydrating agents that suppress curing and have good curability That is, it is possible to obtain a fast-curing room-temperature curable composition.

Examples of the surface treatment agent comprising an organic substance for treating the surface of the heavy calcium carbonate (B) include higher fatty acid type organic substances, resin acid type organic substances and aromatic carboxylic acid esters. C8 or higher as the higher fatty acid-based organic matter, for example, saturated fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and alginic acid,
Unsaturated fatty acids such as oleic acid, elaidic acid, linoleic acid and ricinoleic acid, alicyclic carboxylic acids such as naphthenic acid, resin acids such as abietic acid and sodium thereof,
Examples thereof include salts such as potassium and ammonium.

In the present invention, the addition amount of the heavy calcium carbonate (B) is 30 parts by weight or more based on 100 parts by weight of the polymer (A). If the amount added is less than 30 parts by weight, a cured product having good physical properties (high elongation) cannot be obtained.

In the present invention, a silanol condensation catalyst is preferably used as the curing catalyst (C), and examples thereof include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin bisacetylacetonate and tin octylate.

The amount of the curing catalyst (C) added depends on the polymer (A).
It is 0.1 to 10 parts by weight with respect to 100 parts by weight. If the addition amount is less than 0.1 part by weight, the effect of promoting curing is small,
This is because when the amount exceeds 10 parts by weight, the modulus of the cured product obtained is significantly reduced.

Various fillers may be added to the room temperature curable composition of the present invention. Examples of such fillers include magnesium carbonate, hydrous silicic acid, anhydrous silicic acid, calcium silicate, silica, titanium dioxide,
Examples include clay, talc, and carbon black. These fillers may be used alone or in combination of two or more.

Further, the room temperature curable composition of the present invention can be further enhanced in elongation property after curing and can have a low modulus by adding a plasticizer. Examples of the plasticizer include phosphates such as tributyl phosphate and tricresyl phosphate, phthalates such as dioctyl phthalate, aliphatic monobasic acid esters such as glycerin monooleate, dibutyl adipate, and dioctyl adipate. Group dibasic acid esters, polyethers such as polypropylene glycol and the like can be mentioned. These may be used alone or in combination of two or more.

The room temperature curable composition of the present invention further comprises
It is possible to add pigments, ultraviolet absorbers, antioxidants and the like.

[0019]

The room temperature curable composition of the present invention comprises a polymer (A) whose main chain is essentially a polyether and which has a crosslinkable hydrolyzable silyl group at its terminal and has a molecular weight of 4,000 to 30,000. 100 parts by weight and specific surface area of 15,000 cm ² /
30 parts by weight or more of heavy calcium carbonate (B) whose surface is treated with an organic substance in an amount of g or more, and a curing catalyst (C) 0.1 to
Since it is composed of 10 parts by weight, dried heavy calcium carbonate does not contain much water like precipitated calcium carbonate, and thus has excellent storage stability. In addition, it is excellent in storage stability such as vinyltrimethoxysilane and tetraethoxysilane. Since a very small amount of such a dehydrating agent can be used, the curing agent is hardly affected by the dehydrating agent that suppresses curing, and the resulting cured product has a specific surface area in the reaction product of the polymer (A). Since the heavy calcium carbonate (B) whose surface is large and whose surface is treated with an organic substance is appropriately dispersed, it has excellent tensile properties.

[0020]

EXAMPLES The present invention will be clarified by giving Examples and Comparative Examples of the present invention. Preparation of calcium carbonate As shown in Table 1, calcium carbonate was prepared.

[0021]

[Table 1]

Examples 1 to 3 and Comparative Examples 1 to 3 As a polymer (A) whose main chain is essentially a polyether and has a crosslinkable hydrolyzable silyl group at the end, a product manufactured by Kanebuchi Chemical Co., Ltd. Example 1 shown in Table 2 using "Cyryl 5A03" (molecular weight 8500), using calcium carbonate ~ shown in Table 1 as calcium carbonate, using dibutyltin bisacetylacetonate as a curing catalyst (C).
3 and the compounding compositions of Comparative Examples 1 to 3 were compounded by the following method.

After the calcium carbonate was dried at 120 ° C. for 2 hours, “Cyryl 5A03” and the plasticizer dioctyl phthalate were mixed by a planetary mixer, and further dried at 110 ° C. under reduced pressure for 3 hours, and the remaining compounding ingredients were added thereto. Blended,
The mixture was uniformly mixed to obtain a room temperature curable composition.

Physical property measurement method Tack free time measurement According to JIS A5758, temperature 23 ° C, humidity 60% R
H. Tensile test of cured product About room temperature curable composition obtained, thickness of 2 m
A m-thick sheet was prepared and cured at 20 ° C. and 60% RH for 1 week, then a No. 3 dumbbell test piece was prepared in accordance with JIS K6301, and a tensile test was performed at a speed of 50 mm / min.
The obtained results are also shown in Table 2.

Storage stability The change in tack free time after 1 week at 50 ° C. was measured in a sealed state. In Table 2, ◯ indicates that the tack free time delay is 1.5 times or less, and x indicates that the tack free time delay exceeds 1.5 times.

[0026]

[Table 2]

As is clear from Table 2, in each of Examples 1 to 3 of the present invention, the tack free time is small, the storage stability is excellent, and the tensile properties are excellent.
On the other hand, when heavy calcium carbonate having a small specific surface area is used as in Comparative Examples 1 and 2, tensile properties are poor, and when colloidal calcium carbonate is used as in Comparative Example 3. , Storage stability is poor.

[0028]

Since the room temperature curable composition of the present invention has the above-mentioned constitution, a cured product having a high curing rate, excellent storage stability and excellent tensile properties can be obtained. It can be preferably used as a sealing material.

Claims (1)

[Claims] 1. A molecular weight 4, the main chain of which is essentially a polyether and which has a crosslinkable hydrolyzable silyl group at its end.
000 to 30,000 polymer (A) 100 parts by weight,
It is characterized by comprising 30 parts by weight or more of heavy calcium carbonate (B) having a specific surface area of 15,000 cm ² / g or more and having a surface treated with an organic substance, and 0.1 to 10 parts by weight of a curing catalyst (C). Room temperature curable composition.