JP5642849B2 - Method for preparing room temperature curable polyorganosiloxane composition - Google Patents

Description

  The present invention relates to a method for preparing a room temperature curable polyorganosiloxane composition useful as an elastic adhesive or a sealing material.

  Polyorganosiloxane compositions (room temperature curable polyorganosiloxane compositions) that cure at room temperature upon contact with moisture in the air to produce rubbery elastic bodies (room temperature curable polyorganosiloxane compositions) have excellent adhesive properties, such as electrical and electronic industries. It is widely used as an elastic adhesive and coating material, and as a sealing material for construction. Recently, it is also being considered for use as a sealing material for concrete joints such as expressways, airport runways, and viaducts, and for sealing parts of automobile airbags.

  In particular, when used as a sealing material for concrete joints as described above or as an elastic adhesive for airbags, it has fluidity at room temperature, and the cured product has low modulus, high elongation, high strength and good adhesion. However, a room temperature curable polyorganosiloxane composition that sufficiently satisfies such requirements has not yet been obtained.

  That is, conventionally, as a sealing material having high fluidity and low modulus, a non-reactive plasticizer such as polydimethylsiloxane whose end is blocked with a trimethylsiloxy group, or a silicone-based plasticizer containing no hydroxyl group is high. Polyorganosiloxane compositions formulated in proportions are used.

  However, in such a composition, there was a problem that the plasticizer oozes out and easily contaminates the periphery of the construction site. Moreover, since the modulus of the seal portion (cured product) from which the plasticizer has exuded increases, the stress in the adhesion boundary phase increases, and as a result, there is a problem in that the adhesiveness decreases. Furthermore, when a plasticizer is blended at a high ratio, there is a problem that not only the curability is lowered, but the risk of surface cracks particularly during the curing is increased, and the strength after curing is lowered.

  Further, in order to obtain a cured product having a low modulus and a high elongation, a room temperature-curable polyorganosiloxane composition using phenyl-substituted tris-functional ketoxime silanes as a crosslinking agent has been proposed (see, for example, Patent Document 1). ).

  However, even the room temperature curable polyorganosiloxane composition described in Patent Document 1 has a sufficient fluidity at room temperature, and it is difficult to obtain a cured product having a low modulus and excellent extensibility.

  Furthermore, in order to improve the mechanical strength after curing, a polyorganosiloxane composition containing calcium carbonate as a filler is known. However, when calcium carbonate is highly charged, the viscosity increases and the viscosity decreases. It was difficult.

  Further, since moisture is adsorbed on the surface of calcium carbonate, when used in a one-component room temperature curable polyorganosiloxane composition that cures with moisture in the air, surface activity such as an alkali metal salt of a fatty acid is used. The surface treatment of calcium carbonate is performed with an agent to stabilize the composition, but in the composition containing calcium carbonate that has been subjected to the surface treatment, the thixotropy is improved, but the fluidity is reduced. After that, it was difficult to cure smoothly in a state where it was left to stand. Therefore, it is unsuitable for applications such as coating materials, potting materials, or sealing materials.

Japanese Patent No. 30428246

  The present invention has been made to solve these problems, has fluidity at room temperature, has a cured product with low modulus, high elongation, high strength, good adhesiveness, and does not contaminate the peripheral portion. It is an object to provide a room temperature curable polyorganosiloxane composition.

The method for preparing the room temperature curable polyorganosiloxane composition of the present invention comprises (A) a molecule having an average of two or more silanol groups and / or ketoximato groups bonded to silicon atoms as silicon functional groups at 23 ° C. (B) silicon having one silanol group or ketoximato group bonded to a silicon atom in the molecule with respect to 100 parts by weight of a silicon-functional polyorganosiloxane having a viscosity of 20,000 to 1,000,000 mPa · s 5 to 100 parts by weight of a functional polyorganosiloxane, (C) 20 to 200 parts by weight of calcium carbonate having an average particle diameter of 0.5 to 10 μm, and (D) a silane compound having a hydrolyzable group as a crosslinking agent 0 Hydrolysis which contains 5 to 25 parts by weight and (E) 0.01 to 10 parts by weight of a curing catalyst and is the component (D) Silane compounds having a group, the hydrolysis with (D1) includes a hydrolyzable group-containing silane compound having a mercapto group, and a hydrolyzable group-containing silane compound having no mercapto group, and wherein (D1) a mercapto group A room temperature-curable polyorganosiloxane composition containing a functional group-containing silane compound in a proportion of 0.05 to 5.0 parts by weight with respect to 100 parts by weight of the silicon-functional polyorganosiloxane as the component (A). (D1) The hydrolyzable group-containing silane compound having a mercapto group is added to the hydrolyzable group-containing silane compound having no mercapto group among the components (D) before ( It is added to a mixture of the component (A), the component (B) and the component (C).

  The room temperature curable polyorganosiloxane obtained by the present invention has low viscosity and fluidity at room temperature, and can obtain a cured product having low modulus, high elongation and high strength. Further, it has good curability, shows good adhesion to various substrates such as metal, glass, and resin, and has little contamination to the periphery. Furthermore, the storage (preservation) stability is good, and it has the same characteristics as the initial stage after storage.

  Embodiments of the present invention will be described below. The room temperature-curable polyorganosiloxane composition of the embodiment has (A) molecules having an average of two or more silanol groups and / or ketoximinosilyl groups that are ketoximato groups bonded to silicon atoms as silicon functional groups. And a silicon-functional polyorganosiloxane having a viscosity at 23 ° C. of 20,000 to 1,000,000 mPa · s, and (B) one silanol group or ketoximato group bonded to a silicon atom in the molecule (ketoximi (Si) -functional polyorganosiloxane having (nosilyl group), (C) calcium carbonate having an average particle size of 0.5 to 10 μm, (D) a silane compound having a hydrolyzable group as a crosslinking agent, and (E ) Each contains a curing catalyst. And the silane compound which has a hydrolyzable group which is (D) component contains the hydrolyzable group containing silane compound which has (D1) mercapto group. Hereinafter, each component of the room temperature curable polyorganosiloxane composition of the embodiment will be described.

  The silicon-functional polyorganosiloxane as component (A) is a base polymer of the room temperature curable polyorganosiloxane composition of the embodiment. The component (A) has an average of two or more silanol groups and / or ketoximato groups bonded to silicon atoms as silicon functional groups in the molecule, and is a crosslinking agent that is component (D) by the catalytic action of component (E) Reacts with and cures. The reaction is a hydrolysis reaction followed by a condensation reaction and proceeds in the presence of moisture in the air. (A) The viscosity (23 degreeC) of the silicon functional polyorganosiloxane which is a component is 20,000-1,000,000 mPa * s.

で示される実質的に直鎖状のポリオルガノシロキサンである。 The (A) silicon-functional polyorganosiloxane used in the embodiment is typically represented by the general formula:

Is a substantially linear polyorganosiloxane.

In the formula, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different from each other, and R ² represents a hydroxyl group or —ZSiR ³ _3-p X _p . Here, Z represents a divalent oxygen group and / or a divalent hydrocarbon group, R ³ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different from each other, and X represents a hydroxyl group Or the ketoximato group which is a hydrolysable group is represented, and p represents the number of 1-3. Moreover, n is a number which makes the viscosity at 23 ° C. of the component (A) 20,000 to 1,000,000 mPa · s. Thus, the component (A) has a hydroxyl group (silanol group) bonded to at least one silicon atom or a ketoximato group (ketoximinosilyl group) bonded to a silicon atom at both ends of the molecule.

On the other hand, when imparting heat resistance, radiation resistance, cold resistance or transparency, a necessary amount of phenyl group as a part of R ¹ , and when imparting oil resistance and solvent resistance, ^one of R ¹ When a 3,3,3-trifluoropropyl group or 3-cyanopropyl group is given as a part, and a surface having paintability is imparted, a long chain alkyl group or an aralkyl group is a methyl group as a part of R ^1. Can be arbitrarily selected depending on the purpose.

  In addition, in order to provide the composition before curing with low viscosity and high fluidity, and to give excellent mechanical properties to the cured product, n of the component (A) is the viscosity of the component (A) at 23 ° C. Is selected to be 20,000 to 1,000,000 mPa · s, preferably 40,000 to 500,000 mPa · s. When the viscosity of the component (A) is less than 20,000 mPa · s, the extensibility of the cured product is not sufficient. On the other hand, when the viscosity exceeds 1,000,000 mPa · s, it is difficult to produce a uniform composition, and it is difficult to obtain a uniform composition. A particularly preferred viscosity is in the range of 40,000 to 200,000 mPa · s from the viewpoint of balancing the properties required for the composition before and after curing.

で示される実質的に直鎖状のポリオルガノシロキサンが挙げられる。式中、Ｒ^１は、互いに同一でも異なっていてもよい置換または非置換の１価の炭化水素基を表し、（Ａ）成分のケイ素原子に直接結合した有機基Ｒ^１と同様な基を例示することができる。入手のしやすさと、優れた架橋反応速度が得られることから、メチル基またはビニル基が好ましい。 In an embodiment, examples of the silicon-functional polyorganosiloxane having a silanol group or a ketoximato group bonded to a silicon atom in the molecule as the component (B) include, for example, the general formula:

The substantially linear polyorganosiloxane shown by these is mentioned. In the formula, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same as or different from each other, and exemplifies the same group as the organic group R ¹ directly bonded to the silicon atom of the component (A). can do. A methyl group or a vinyl group is preferred because it is easily available and an excellent crosslinking reaction rate can be obtained.

R ² represents a hydroxyl group or —ZSiR ³ _3-p X _p . Here, Z, R ³ and p all represent the same group and number as Z, R ³ and p in the formula representing the component (A). Furthermore, m is a number which makes the viscosity of the component (B) at 23 ° C. 100 to 200,000 mPa · s. Thus, as the component (B), one having one hydroxyl group (silanol group) bonded to a silicon atom or one ketoximato group (ketoximinosilyl group) bonded to a silicon atom at one end of the molecule can be mentioned. . In the component (B), the position of one silanol group or ketoximato group bonded to a silicon atom present in the molecule may be the middle part instead of the terminal of the molecule.

  In embodiment, the compounding quantity of the silicon functional polyorganosiloxane which is (B) component is 5-100 weight part with respect to 100 weight part of said (A) component, More preferably, it is the range of 5-50 weight part. . If it is less than 5 parts by weight, the fluidity of the composition before curing and the extensibility of the cured product become insufficient, which is not preferable. When the amount exceeds 100 parts by weight, the mechanical strength of the cured product becomes insufficient, which is not preferable.

  In the embodiment, the calcium carbonate as the component (C) is blended for the purpose of imparting high fluidity to the composition before curing and imparting high mechanical strength to the cured product. A thing with a diameter of 0.5-10 micrometers is used. When the average particle diameter of calcium carbonate exceeds 10 μm, not only the mechanical properties of the cured product are deteriorated, but also the extensibility of the cured product is not sufficient. Moreover, when the average particle diameter is less than 0.5 μm, the viscosity of the composition before curing is increased and the fluidity is lowered, which is not preferable.

  The calcium carbonate which is (C) component can use what processed the surface by the fatty acid, the resin acid, the ester compound, the silicic acid type compound, etc. besides the surface which has not been processed yet.

In the embodiment, the silane compound having a hydrolyzable group as the component (D) functions as a crosslinking agent for the silicon-functional polyorganosiloxane as the component (A). As part of this (D) silane compound, (D1) a hydrolyzable group-containing silane compound having a mercapto group is used. The hydrolyzable group-containing silane compound having a mercapto group as component (D1) has, for example, the general formula: R ⁴ _4-q SiY _q (wherein R ⁴ have a mercapto group which may be the same or different from each other). Represents a monovalent hydrocarbon group, Y represents a hydrolyzable group, and q is an average of more than 2 and 4 or less.

R ⁴ represents a monovalent hydrocarbon group having a mercapto group, and examples of the monovalent hydrocarbon group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, An alkyl group such as a dodecyl group can be exemplified. Examples of the hydrolyzable group Y include alkoxy groups such as a methoxy group and an ethoxy group. Examples of mercapto group-containing silane compounds as component (D) include 3-mercaptopropyltrimethoxysilane.

  This (D1) hydrolyzable group-containing silane compound having a mercapto group not only serves as a crosslinking agent for the silicon-functional polyorganosiloxane (A) component, but also includes (C) the calcium carbonate component. It also functions as a surface treatment agent, imparts fluidity to the composition before curing, and imparts good mechanical properties and extensibility to the cured product. Furthermore, it has the effect of improving the adhesion to a member that is difficult to adhere, such as mortar. Therefore, the hydrolyzable group-containing silane compound having a mercapto group as the component (D1) is preferably added before blending with the other (D) silane compounds described later. That is, the hydrolyzable group-containing silane compound having a mercapto group as the component (D1) is first added to the mixture in which the calcium carbonate as the component (C) is blended with the component (A) and the component (B). After mixing, it is preferable to add another (D) hydrolyzable group-containing silane compound. However, even if (D1) a hydrolyzable group-containing silane compound having a mercapto group and another (D) silane compound are added at the same time, the surface treatment characteristics of the component (D1) are not significantly reduced, and are sufficiently effective. Can be raised.

(D1) As a crosslinking agent that is a component (D) other than the hydrolyzable group-containing silane compound having a mercapto group, a silane compound represented by the general formula: R ⁵ _4-r SiW _r can be used. Here, R ⁵ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same as or different from each other, and exemplifies the same group as the organic group R ¹ directly bonded to the silicon atom of the component (A). be able to. A methyl group or a vinyl group is preferred because it is easily available and an excellent crosslinking reaction rate can be obtained. W represents a hydrolyzable group, and examples thereof include a ketoximato group exemplified as X present at the terminal of the component (A). r is a number exceeding 2 on average and 4 or less.

  Considering that it is easy to synthesize, does not impair the storage stability of the composition, and gives a large crosslinking reaction rate (curing rate), among these crosslinking agents, methyltris (methylethylketoxime) silane, vinyltris (methylethylketoxime) ) Silane, phenyltris (methylethylketoxime) silane and their partial hydrolysis condensates are preferably used.

  In the embodiment, in addition to such a ketoximato group-containing silane, a silane having a substituted hydrocarbon group may be used in combination as a crosslinking agent.

  The composition of the embodiment can be obtained by mixing all of the above components and, if necessary, various additives in a state where moisture is blocked. The obtained composition can be used as a so-called one-pack type (one-pack type) room temperature curable composition that is stored as it is in a sealed container and cured only by exposure to moisture in the air during use. . In addition, the composition of the present invention is prepared as a composition in which, for example, a crosslinking agent and a curing catalyst are separated, and is stored in two or three separate containers as appropriate, and these are mixed at the time of use. It can also be used as a room temperature curable composition.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to a following example. In the examples, “parts” means “parts by weight” and “%” means “% by weight”. All physical property values such as viscosity are measured values at 23 ° C. and relative humidity (RH) 50%.

Example 1
100 parts of α, ω-dihydroxypolydimethylsiloxane having a viscosity of 80,000 mPa · s as component (A), 10 parts of hydroxypolydimethylsiloxane having one-sided terminal having a viscosity of 2,000 mPa · s as component (B), and (C ) 80 parts of heavy calcium carbonate (average particle size 1.1 μm) treated with resin acid as a component, and 40 parts of polydimethylsiloxane blocked at both ends with a viscosity of 100 mPa · s with trimethylsiloxy groups, Kneaded uniformly.

  Next, 0.8 part of 3-mercaptopropyltrimethoxysilane was added to the mixture and kneaded again. Next, 8 parts of methyltris (methylethylketoxime) silane, 2 parts of vinyltris (methylethylketoxime) silane, and 0.8 part of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane were added. Further, 0.5 part of N-propyl orthosilicate and 0.2 part of dibutyltin dilaurate as component (E) were added in a state where moisture was blocked, and mixed uniformly to form a one-component room temperature curable polyorganosiloxane composition. I got a thing.

Example 2
As component (D), instead of blending 8 parts methyltris (methylethylketoxime) silane and 2 parts vinyltris (methylethylketoxime) silane, 10 parts phenyltris (methylethylketoxime) silane was blended. Other than that was carried out similarly to Example 1, and obtained the room temperature-curable polyorganosiloxane composition.

Examples 3-10
Each component shown in Table 1 was blended in the composition shown in the same table and mixed in the same procedure as in Example 1 to obtain a room temperature curable polyorganosiloxane composition.

Comparative Example 1
Heavy calcium carbonate (average particle size 1.1 μm) 100 treated with resin acid (C) is added to 100 parts of (A) component α, ω-dihydroxypolydimethylsiloxane having a viscosity of 80,000 mPa · s. Part and 87.5 parts of polydimethylsiloxane blocked at both ends with a viscosity of 100 mPa · s with trimethylsiloxy groups were added and kneaded uniformly. (B) The one-side terminal hydroxypolydimethylsiloxane which is a component was not mix | blended.

  Next, 10 parts of methyltris (methylethylketoxime) silane, which is component (D), and vinyltris (methylethylketoxime) silane, each of which is component (D), without blending the mixture with 3-mercaptopropyltrimethoxysilane which is component (D1). 5 parts, 1.0 part of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 0.6 part of N-propyl orthosilicate and 0.3 part of dibutyltin dilaurate as component (E) were added. Each was added in a state where moisture was blocked and mixed uniformly to obtain a room temperature-curable polyorganosiloxane composition.

Comparative Example 2
A room temperature-curable polyorganosiloxane composition was obtained in the same manner as in Example 1 except that 3-mercaptopropyltrimethoxysilane as component (D1) was not blended.
Comparative Examples 3-9

  Each component shown in Table 2 was blended in the composition shown in the same table and mixed in the same procedure as in Example 1 to obtain a room temperature curable polyorganosiloxane composition.

  Next, with respect to the polyorganosiloxane compositions obtained in Examples 1 to 10 and Comparative Examples 1 to 9, tack free time, viscosity, physical properties (hardness, tensile strength, elongation, and tensile at 100% elongation) Strength), adhesion, contamination (mortar) and storage stability (characteristics after accelerated heat deterioration) were measured and evaluated by the following methods. These measurement results are shown in Tables 3 and 4.

(A) Tack-free time After the composition was extruded in an atmosphere of 23 ° C. and 50% RH, the time to contact the surface with a finger and confirm that it was in a dry state was measured.

(B) Viscosity After pouring the composition into a 50 cc polystyrene cup in an atmosphere of 23 ° C. and 50% RH, the viscosity was measured using a rotational viscometer.

(C) Physical properties The composition was extruded into a sheet having a thickness of 2 mm, and the obtained sheet was left at 23 ° C. and 50% RH for 7 days to be cured by moisture in the air. Then, the hardness, tensile strength, elongation, and tensile strength (modulus) at 100% elongation of the cured product were measured according to JIS K6301.

(D) Adhesiveness After the composition was applied to aluminum, glass, acrylic resin, polycarbonate, silicone rubber-coated nylon base fabric, and mortar, respectively, it was left at 23 ° C. and 50% RH for 7 days due to moisture in the air. It hardened and it was set as the test body and the cohesive failure rate was measured as adhesiveness with respect to each to-be-adhered body of hardened | cured material.

(E) Contamination (mortar)
After the composition was applied to mortar (JIS standard product), it was left to stand at 23 ° C. and 50% RH for 7 days to be cured by moisture in the air to obtain a test specimen. The specimen was exposed outdoors for 3 months, and the presence or absence of contamination (dirt) on the surrounding mortar was visually confirmed.

(F) Storage stability (characteristic after accelerated heat deterioration)
The composition was put in a container where moisture was cut off and heated at 70 ° C. for 5 days to cause deterioration, and then tack free time, viscosity and physical properties were measured in the same manner as described above.

  As can be seen from Tables 3 and 4, the room temperature curable polyorganosiloxane compositions prepared in Examples 1 to 10 have lower viscosity and fluidity than the compositions obtained in Comparative Examples 1 to 9. It has a low modulus, high elongation and high strength cured product. In addition, the compositions of Examples 1 to 10 have good curability and show good adhesion to various base materials such as aluminum, glass, acrylic resin, polycarbonate, silicone rubber-coated nylon base fabric, and mortar. Also, there was little contamination with mortar. Furthermore, it was confirmed that the storage stability (preservation stability) was good because there was little decrease in characteristics after heat-promoted deterioration compared to the initial characteristics.

  The room temperature curable polyorganosiloxane of the present invention has a low viscosity and fluidity at room temperature, and can form a cured product having low modulus, high elongation, high strength and excellent adhesiveness. Therefore, it can be used as a sealing material for concrete joints such as expressways, airport runways, and viaducts, and as a structural elastic adhesive for buildings or an elastic adhesive for airbags.

Claims (6)

(A) Silicon having an average of two or more silanol groups and / or ketoximato groups bonded to silicon atoms as silicon functional groups in the molecule, and a viscosity at 23 ° C. of 20,000 to 1,000,000 mPa · s For 100 parts by weight of functional polyorganosiloxane,
(B) 5 to 100 parts by weight of a silicon functional polyorganosiloxane having one silanol group or ketoximato group bonded to a silicon atom in the molecule;
(C) 20 to 200 parts by weight of calcium carbonate having an average particle size of 0.5 to 10 μm;
(D) 0.5 to 25 parts by weight of a silane compound having a hydrolyzable group that is a crosslinking agent, and (E) 0.01 to 10 parts by weight of a curing catalyst,
The silane compound having a hydrolyzable group as the component (D) includes (D1) a hydrolyzable group-containing silane compound having a mercapto group and a hydrolyzable group-containing silane compound not having a mercapto group, And (D1) a hydrolyzable group-containing silane compound having a mercapto group in a proportion of 0.05 to 5.0 parts by weight with respect to 100 parts by weight of the silicon-functional polyorganosiloxane as the component (A). A method for preparing a room temperature curable polyorganosiloxane composition,
The (D1) hydrolyzable group-containing silane compound having a mercapto group is mixed with the hydrolyzable group-containing silane compound having no mercapto group among the components (D) and the component (A). A method for preparing a room temperature-curable polyorganosiloxane composition, which is added to a mixture of the component (B) and the component (C). After adding the (D1) hydrolyzable group-containing silane compound having a mercapto group to the mixture in which the component (C) is blended with the component (A) and the component (B), the mercapto The method for preparing a room temperature-curable polyorganosiloxane composition according to claim 1, wherein a hydrolyzable group-containing silane compound having no group is added. 3. The silane compound having a ketoximato group bonded to a silicon atom as at least a part of the hydrolyzable group-containing silane compound having no mercapto group in the component (D). Of preparing a room temperature curable polyorganosiloxane composition.   4. The room temperature curable resin according to claim 1, wherein the hydrolyzable group-containing silane compound having a (D1) mercapto group has a methoxy group or an ethoxy group as the hydrolyzable group. A method for preparing a polyorganosiloxane composition.   5. The silane compound having a substituted or unsubstituted hydrocarbon group bonded to a silicon atom as a part of the silane compound having a hydrolyzable group as the component (D). A method for preparing a room temperature-curable polyorganosiloxane composition according to any one of the above.   The (D1) hydrolyzable group-containing silane compound having a mercapto group is blended at a ratio of 0.1 to 4.0 parts by weight with respect to 100 parts by weight of the silicon-functional polyorganosiloxane as the component (A). A method for preparing a room temperature curable polyorganosiloxane composition according to any one of claims 1 to 5.