JPH04126768A - Room temperature-curable organopolysiloxane composition - Google Patents

Abstract

PURPOSE:To provide the subject composition having a suitable pot life and giving cured products having good physical properties by compounding a silanol group-containing organopolysiloxane, a specific organosilane or organosiloxane, an organic fatty acid and a curing catalyst. CONSTITUTION:A composition comprises (A) 100 pts.wt. of an organopolysiloxane having two or more silanol groups in the molecule, preferably dimethylpolysiloxane having a viscosity of 300-100000cst at 25 deg.C and terminated with hydrosilyl groups at both the molecular ends, (B) 0.5-20 pts.wt. of an organosilane or organosiloxane having three or more Si-bonded hydrolyzable groups (e.g. methyltrimethoxysilane), (C) 0.01-10 pts.wt. of a >=2C organic fatty acid, preferably 6-30C monocarboxylic acid, and (D) a curing catalyst (e.g. dibutyltin dilaurate) in an amount of 0.01-10 pts.wt. per 100 pts.wt. of the sum of the components A, B and C.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to an organopolysiloxane having at least two silanol groups in one molecule and at least three hydrolyzable groups bonded to silicon atoms in one molecule. The present invention relates to an organopolysiloxane composition containing an organopolysiloxane.

(Prior Art) Organopolysiloxane compositions as described above have been conventionally known as condensation-curable, room-temperature-curable compositions. This composition cures at room temperature to form an elastomer-like cured product, and is widely used in applications such as insulating materials, sealing materials, botting materials, molding materials, and tampon printing materials. ing.

In order to put such a composition into practical use, it is necessary to have a suitable usable time (pot life). Without pot life, these compositions would begin to cure before they could be shaped into the required shape or filled into suitable molds, making them virtually impossible to use. .

Conventional methods for ensuring a certain pot life for such compositions include (1) adjusting the amount of catalyst, (2) adding silane or siloxane containing a relatively low molecular weight silanol group, etc. known from. Incidentally, as these silanes and siloxanes, RR (] R35iOH,HO+5iO-h-H,)10-(-5
iO+-rSiR3RR R I (wherein R is a monovalent hydrocarbon group such as a methyl group,
p is an integer of 2 to 50, q is an integer of 4 to 8), etc. are used.

(Problems to be Solved by the Invention) However, although the method of adjusting the amount of catalyst as in (2) above can ensure a certain pot life, it has the problem that it takes too long for the composition to completely cure. be.

In addition, the method of adding a specific silane or siloxane compound as in (2) above is preferable in terms of ensuring a suitable pot life, but since these compounds are incorporated into the crosslinked structure of the cured elastomer, the resulting There have been problems such as the hardness of the elastomer being increased and the elongation being reduced, or the number of functional groups contributing to the crosslinking reaction being increased, resulting in a decrease in the stability of the mechanical properties of the elastomer.

Therefore, the present invention aims to solve the above-mentioned problems and provide a room-temperature curable composition that can ensure an appropriate bond life without adversely affecting the mechanical properties of the resulting cured product. purpose.

(Means for Solving the Problems) The composition of the present invention comprises: (a) an organopolysiloxane having at least two silanol groups in one molecule; (b) a hydrolyzable group bonded to a silicon atom in one molecule; (c) an organic fatty acid having 2 or more carbon atoms; (d) a curing catalyst; and such (a) to (d)
By using a combination of components, the above-mentioned problems have been successfully solved.

Component (8) In the room temperature curable composition of the present invention, the organopolysiloxane of component (a) used as the base polymer is:
It has at least two silanol groups in one molecule, and usually has the following formula (1), HO-(-3iO-)
-1,H (I) In the formula, R1 represents an unsubstituted or substituted monovalent hydrocarbon group, and n is an integer of 2 or more. used in

In this formula (1), the unsubstituted or substituted monovalent hydrocarbon group R1 is, for example, a methyl group, an ethyl group,
lower alkyl groups having 8 or less carbon atoms such as propyl group and butyl group; alkenyl groups such as vinyl group, allyl group, isopropenyl group, butenyl group, hexenyl group, and acrylic group;
Cycloalkyl groups such as cyclohexyl groups, phenyl groups,
Aryl group such as tolyl group and naphthyl group, benzyl group, 2
-Aralkyl groups such as phenylethyl groups, and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen etc., such as chloromethyl groups, 3,3.3-trifluoropropyl groups, etc., usually carbon Examples include those having 1 to 10 atoms, preferably 1 to 8 carbon atoms. In addition, a portion of these unsubstituted or substituted monovalent hydrocarbon groups R1 may be substituted with a hydroxyl group, if particularly required for characteristics.

In addition, in the above formula CI), n is on average 100 to
Preferably, it is an integer of 1000, and in conjunction with such a value of n, the temperature of the organopolysiloxane at 25°C
The viscosity at is preferably in the range of 300 to 100,000 cSt.

The organopolysiloxane represented by the above general formula [1] is generally obtained by equilibrating organocyclopolysiloxane with an alkali catalyst or an acid catalyst using water or a low molecular weight compound containing a silanol group as a terminator. . Examples of the alkali catalyst used here include potassium hydroxide, tetraalkylphosphonium high F oxide, tetraalkylammonium hydroxide, etc., and examples of the acid catalyst include sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, etc. Illustrated.

In the present invention, the organopolysiloxane suitably used is specifically exemplified by, but not limited to, the following.

(Here, ph is a phenyl group, l, l″9m, n
are positive integers, n and m+n are 100 to 1000, and 1 and 1' are 1
That's all. ) Charcoal separation In the present invention, the organosilane or polysiloxane used as component (b) acts as a crosslinking agent, and for this purpose it contains at least 3 hydrolyzable groups bonded to silicon atoms in one molecule. It is necessary to have one. That is, this hydrolyzable group reacts with the silanol group in the organopolysiloxane of component (a) to form a cured product having elastomeric properties with a three-dimensional structure.

Examples of such hydrolyzable groups include methoxy groups,
Alkoxy groups such as ethoxy group, propoxy group, butoxy group, methoxyethoxy group, ethoxyethoxy group; Acyloxy group such as acetoxy group, propenoxy group, butyroxy group, benzoyloxy group; isopropenyloxy group, isobutenyloxy group, 1 -Alkenyloxy groups such as ethyl-2-methylvinyloxy group; iminoxy groups such as dimethylketoxime group, methylethylketoxime group, diethylketoxime group, cyclopentanoxime group, cyclohexanoxime group; N-methylamino group, Amino groups such as N-ethylamino group, N-propylamino group, N-butylamino group, N,N-dimethylamino group, N,N-diethylamino group, cyclohexylamino group; N-methylacetamide group, N- Examples include amide groups such as ethylacetamido group and N-methylbenzamide group; aminooxy groups such as N,N-dimethylaminooxy group and N,N-diethylaminoxy group.

In the present invention, examples of such organosilanes or polysiloxanes that act as crosslinking agents include methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, vinyltriethoxysilane, tetraethoxysilane, and tetraethoxysilane. (n-propoxy)silane, methyltris(propenoxy)silane, vinyltris(propenoxy)silane, phenyltris(
1-methoxyl (2-methylpropenoxy) silane, and partially hydrolyzed products or mixtures thereof are preferably used.

These component (b) should be added in an amount of 0.5 to 20 parts by weight, especially 1 part by weight, per 100 parts by weight of the organopolysiloxane of component (a).
It is preferable to use it in a proportion of ~IO parts by weight.

If it is less than 0.5 part by weight, the composition will not be cured sufficiently, making it difficult to obtain an elastomeric cured product, and may also cause disadvantages such as deterioration of the mechanical properties of the cured product. . Furthermore, if more than 20 parts by weight is used, disadvantages such as excessively high hardness of the cured product may occur.

Charcoal Content (6) In the present invention, the organic fatty acid used as component (c) suppresses the crosslinking reaction and acts as a pot life regulator of the composition. As such organic fatty acids, various fatty acids such as lower fatty acids to higher fatty acids and unsaturated fatty acids can be used as long as the number of carbon atoms is 2 or more. Specific examples include acetic acid, butyric acid, succinic acid, jacic acid, phthalic acid, octylic acid, lauric acid, oleic acid, stearic acid, and maleic acid. Particularly preferably used in the present invention are:
It is a monocarboxylic acid having 6 to 30 carbon atoms.

For example, lower fatty acids such as acetic acid and butyric acid have a strong odor, and if they adhere to the skin, they cause rashes, discomfort, etc., so their use may be limited. Furthermore, if the number of carboxylic acid groups becomes too large or the molecular weight becomes too high, the solubility of component (a) in organopolysiloxane may decrease, and the effect of suppressing the crosslinking reaction may not be sufficiently achieved.

The above-mentioned component (c) is preferably used in an amount of 0.01 to 10 parts by weight, particularly 0.1 to 5 parts by weight, per 100 parts by weight of the organopolysiloxane of component (a). If the amount is less than 0.01 part by weight, the effect of suppressing the crosslinking reaction will not be sufficiently achieved, and the object of the present invention, which is to ensure a suitable pot life, may not be achieved. If more than 10 parts by weight is used, although the effect of suppressing the crosslinking reaction is sufficiently high, there may arise a problem that curing in the so-called deep part, which is not exposed to air, becomes too slow.

Carbon fractionation Component (d) used in the present invention is a curing catalyst used to promote curing by crosslinking reaction of components (a) and (b), and is generally a condensed silicone room temperature curable. The curing catalyst used in the composition is used. For example, metal salts of organic acids such as dibutyltin dilaurate, dibutyltin dibenzyl maleate, dibutyltin dioctoate, iron stearate, lead octylate, titanate esters such as tetraisopropyl titanate, and titanium chelate compounds such as titanium acetylacetonate. , and mixtures thereof are preferably used.

These curing catalysts are generally desirably used in a proportion of 0.01 to 10 parts by weight, particularly 0.1 to 5 parts by weight, per 100 parts by weight of the total amount of components (a) to (c).

If the amount is less than 0.01 parts by weight, the curing catalyst will not function sufficiently, the curing time will be prolonged, and curing deep within the rubber layer will tend to be insufficient. 10 more
If the amount is more than 1 part by weight, the storage stability of the composition will be poor, and the properties such as heat resistance of the cured product will tend to deteriorate.

In the present invention, in addition to the above-mentioned components (a) to (d), various additives may be added in order to improve the properties of the composition within a range that does not impair the purpose of the present invention. Can be blended. For example, fumed silica, precipitated silica, hydrophobized products thereof, carbon black, etc. can be blended as reinforcing fillers, anti-settling agents, or to impart electrical conductivity. Quartz powder, fused silica, spherical silica, diatomaceous earth, zeolite, calcium carbonate, titanium dioxide, iron oxide, alumina, spherical alumina, aluminum hydroxide, and nitride can also be used as semi-reinforcing fillers, extenders, and thermally conductive fillers. Aluminum, magnesium sulfate, etc. can be blended. Furthermore, lead compounds such as lead carbonate and lead hydroxide can be blended for radiation shielding, and colorants such as inorganic pigments and organic dyes, cerium oxide,
Heat resistance or flame retardancy improvers such as zinc carbonate, manganese carbonate, benzotriazole, and platinum compounds can also be blended. Further, the composition of the present invention is a condensation curing type, and in order to accelerate curing or to perform good curing in deep parts, water, methanol, ethanol, propatool, etc.
It is also optional to add alcohols such as methylcellosolve.

The room-temperature curable composition of the present invention can be easily prepared by uniformly mixing the above-mentioned components. It is also possible to use the liquid form by mixing them immediately before use.

When the composition of the present invention is left in the air, it is cured at room temperature by moisture in the air, forming a cured product of rubber elastic body.

(Example) In the following examples, "parts" indicate parts by weight, and viscosity is a value at 25°C.

1 to 9 Dimethylpolysiloxane (viscosity: 10,000 cP) with both ends capped with hydrosilyl groups 100 parts Dry silica with a specific surface area of 300 rI (20 parts hexamethyldisilazane 5 parts water)
Kneader 1 part
The mixture was mixed in a vacuum chamber and heated at 150°C for 4 hours, and then used as a silicone paste.

To 100 parts of this silicone base were added 3 parts of orthoethylsilicate, 1 part of dibutyltin dioctoate, and the types and amounts of organic fatty acids shown in Table 1 to prepare compositions (Examples 1 to 9). For comparison, a composition was prepared in the same manner as above without adding any organic fatty acid (Comparative Example 1).

Each composition was cast into an aluminum Petri dish with a diameter of 60 holes and a depth of 6 holes, and the pot life and hardness (JIS A) of the cured product after 1 day and 3 days of room temperature curing were measured. The measurement results are shown in Table 1.

(Effects of the Invention) According to the present invention, it has become possible to ensure a suitable pot life of the composition while stably maintaining mechanical properties such as hardness of the cured product.

Claims (2)

[Claims] (1) (a) Organopolysiloxane having at least two silanol groups in one molecule, (b) Organosilane or organosiloxane having at least three silicon-bonded hydrolyzable groups in one molecule, (c A room temperature curable organopolysiloxane composition comprising:) an organic fatty acid having 2 or more carbon atoms; and (d) a curing catalyst. (2) A cured product obtained by curing the composition according to claim (1).