JPH0457828A - Preparation of room temperature-curable resin - Google Patents

Abstract

PURPOSE:To prepare the title resin excellent in easiness in application, weather resistance after being cured, and rubber elasticity by allowing a polyether having terminal allyl groups and a specific silane compd. to undergo addition reaction. CONSTITUTION:One mol of a polyoxylalkylene polyoxyalkylene polyol (e.g. a polyoxypropylene glycol) is made to react with one mol or higher of a pentaerithritol deriv. of formula I (wherein R1 is H or 1-4C alkyl) in the presence of an acidic catalyst at 50-180 deg.C for 3-4 hr to give a polyether which has a number-average mol. wt. of 5000-20000 and in which 60-95 mol% of the molecular terminals are allyl and the rest are hydroxyl. One mol of the polyether is allowed to undergo the addition reaction with 1.5-2.2 mol of an org. silane compd. of formula II (wherein R is H, 1-12C alkyl, or aryl; X is a hydrolyzable group; and (n) is 0-2) in the presence of a platinum catalyst at 50-100 deg.C to give the title resin.

Description

Detailed Description of the Invention (a) Purpose of the Invention [Field of Industrial Application] The present invention relates to a method for producing a polyether having an allyl group at the end, and a method for producing a room temperature curable resin using the polyether as a raw material. It is related to.

The room temperature curable resin obtained by the present invention provides a cured product having elasticity and is suitably used as a base polymer for elastic sealants, elastic adhesives, and the like.

[Prior art and its problems]

The properties required of a room-temperature-curing resin used as a main component of a room-temperature-curing sealant or adhesive are basically rubber elasticity that can follow distortion, and secondly, high weather resistance. Conventionally, various resins such as modified thiocol-based, urethane-based, silicone-based, and modified silicone-based resins are known as resins used for such purposes, but each of these resins has the following problems. .

That is, the modified thiokol type has a problem that the curing rate is very slow, it can practically only be used in a high temperature and humid environment, and the bad odor caused by the mercaptan type compound remains for a long time.

As a urethane type, polyurethane which has isocyanate groups at both ends of the molecule and has an average molecular weight of about 8,000 or more, which is obtained by the reaction of polyester polyol or polyether polyol with a polyvalent isocyanate compound, is common. Molecules attract each other due to hydrogen bonds based on urethane bonds, resulting in high viscosity and poor workability.

Next, as a typical silicone resin, polysiloxane having a silicon atom having a hydrolyzable group such as an acetoxy group at the end of the molecule is known. This polysiloxane cures quickly with moisture in the atmosphere and exhibits good adhesion to surfaces such as glass and ceramics without the use of a brimer, offering excellent performance, but is expensive. In some respects, there were practical limitations.

Modified silicone resins are inexpensive resins that have some of the characteristics of the silicone resins mentioned above, and representative examples include polyethers with high molecular weights, that is, polyether polyols with a molecular weight of 2,000 to 5,000. A resin is known in which a polyether skeleton having a molecular weight of 8,000 or more is obtained by further increasing the molecular weight of a polyester polyol, and a silicon atom having a hydrolyzable group is introduced at the end of the polyether skeleton.

The reason why a polyether or polyester with a high molecular weight is used as the skeleton of the modified silicone resin is that if the molecular weight thereof is small, the resin after curing will not have good rubber elasticity.

As methods for synthesizing modified silicone resins, for example, the following methods are known.

That is, in JP-A No. 51-230024, the terminal hydroxyl group of a polyol as a starting material is alkoxidized with an alkali metal, then a polyvalent halogen compound is reacted with it to link the polyols, and then ethylenic dihydrogen A method is to introduce a double bond at the end of a high-molecular-weight polyether using allyl chloride, etc., which has a heavy bond and a halogen atom, and then introduce a hydrolyzable silyl group based on the double bond. It has been proposed, and in Japanese Patent Publication No. 46-30711,
The raw material polyol and the diisocyanate compound are reacted to increase the molecular weight, and an isocyanate group is introduced at the end of the molecule, and then an organosilicon compound such as T-aminopropyltrimethoxysilane having a functional group reactive with the isocyanate group is reacted. A method has been proposed.

However, the room temperature curable resin obtained by the method described in JP-A-59-230024 has a cured product with poor weather resistance, as is clear from the comparative examples mentioned below.
In addition, in the method described in Japanese Patent Publication No. 46-30711, since the polyols are connected by urethane bonds, there is a problem of high viscosity due to the effect of hydrogen bonds as described above.

[Problems to be Solved by the Invention] An object of the present invention is to easily produce a room-temperature curable resin and its raw material that is easy to apply and provides a resin with excellent weather resistance and good rubber elasticity after curing. The purpose is to provide a manufacturing method.

(B) Structure of the Invention [Means for Solving the Problems] In order to solve the above problems, the inventors of the present invention have conducted intensive studies and have completed the present invention.

That is, the first invention of the present invention provides (a) a polyoxyalkylene polyol and (b) a pentaerythritol derivative represented by the following general formula in a molar ratio (b)/(a
) is a method for producing a polyether having an allyl group at the end of the molecule, characterized by carrying out a condensation reaction at a ratio of more than 1, and the general formula: CHz"CH-C-R+ CR+-C-CH=
CHz (In the formula, R1 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) Furthermore, the second invention provides a polyether having an allyl group at the end of the molecule obtained by the above method, which has the general formula ;HS
i (R)n(X)3-n (wherein R is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group,
is a hydrolyzable group, and n is an integer of 0 to 2. ) is a method for producing a room temperature curable resin, which is characterized by subjecting an organic silane compound represented by the following formula to an addition reaction.

The present invention will be explained in more detail below.

Examples of the polyoxyalkylene polyol (hereinafter sometimes simply referred to as polyol) used in the first invention include polyoxyethylene glycol, polyoxypropylene glycol, and polyoxybutylene glycol, and these glycols have multiple oxyalkylene units. Various types of copolymerized polyoxyalkylene glycols can also be used. Furthermore, a small amount of polyol having three or more hydroxyl groups in one molecule can also be used in combination.

In the first aspect of the invention, polyoxypropylene glycol is preferred because it has an excellent balance between elongation properties and tensile strength of the cured product obtained from the room temperature curable resin of the second aspect.

A polyol in which polyoxyethylene glycol is added to both ends of polyoxypropylene glycol is more preferable, and specific examples include, for example, Excenol 530 manufactured by Asahi Olin ■.

The polyol preferably has a molecular weight of 400 or more, more preferably 2,000 to 5,000 in terms of polystyrene-equivalent number average molecular weight measured by gel permeation chromatography (hereinafter referred to as GPC). When the molecular weight is less than 400, in the polyether formed from the polyol and the pentaerythritol derivative, the proportion of linking parts derived from the pentaerythritol derivative increases, and flexibility and elongation are impaired.

As described above, the pentaerythritol derivative reacted with the polyoxyalkylene polyol is a compound represented by the following general formula.

General formula; % formula %) (In the formula, R1 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) In the above general formula, a compound in which R1 is a hydrogen atom,
Diarylidene pentaerythritol is commercially available and can also be synthesized by reacting pentaerythritol with excess acrolein in the presence of an acid catalyst (Angeiy, Chem.
, j42L Nα5. 113 pages, 1950)
.

Pentaerythritol derivatives other than diarylidene pentaerythritol, that is, compounds in which R1 in the above general formula is a methyl group, ethyl group, propyl group, or butyl group, include pen erylidene pentaerythritol, methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, or butyl. It can be synthesized by reacting vinyl ketones.

Next, the reaction between a polyol and a pentaerythritol derivative will be explained.

This reaction is a reaction in which the hydroxyl group of the polyol is added to the allyl group of the pentaerythritol derivative, and the polyol is made to have a high molecular weight by linking multiple polyols through the residues of the pentaerythritol derivative.
As explained below, as a result of using the pentaerythritol derivative in excess of the polyol, an allyl group is introduced at the end of the resulting high-molecular-weight polyether.

The reason why the addition reaction of a hydroxyl group to an allyl group occurs quantitatively and easily without side reactions is because there are two carbon atoms at the 3rd position of the allyl group in the pentaerythritol derivative used in the present invention. It is presumed that this is due to the structural specificity of the bonding of oxygen atoms.

As mentioned above, the reaction ratio of the (a) polyol and (b) pentaerythritol derivative is such that the molar ratio (b)/(a) is greater than 1, preferably the molar ratio (b)/(
This is the ratio at which a) has a value of 1.1 to 2.0. By reacting at such a molar ratio, the number average molecular weight is 5000.
~20000 preferably 8000~20000,
A polyether can be obtained in which about 60 to 95 mol% of the molecular terminals are converted to allyl groups, and the remaining terminal groups are hydroxyl groups.

When the value of the molar ratio (b)/(a) is 1 or less, the conversion rate to the terminal allyl group in the high molecular weight polyether is low, and in the second invention, this is reacted with an organic silane compound. However, a room temperature curable resin having practically satisfactory physical properties cannot be obtained. On the other hand, when the value of (b)/(a) exceeds 2, the pentaerythritol derivative tends to remain unreacted, and the elongation of the cured product made of the room temperature curable resin is likely to be insufficient.

In the above reaction, it is preferable to use an acidic catalyst, and examples of the catalyst include organic acids such as p-toluenesulfonic acid, diethylsulfonic acid, n-diethylsulfuric acid, ethylsulfonic acid, n-dibutylsulfonic acid, oxalic acid, and caffeinesulfonic acid. ,
Examples include Lewis acids such as anhydrous aluminum chloride, and a more preferred catalyst is para-toluenesulfonic acid. The preferred amount of catalyst used is 0.1 to 5.0 parts by weight per 100 parts by weight of raw material polyol.

The reaction can be carried out either solvent-free or in a solvent system. When a solvent system is used, a solvent without active hydrogen such as ether, aliphatic hydrocarbon, aromatic hydrocarbon, or halogenated hydrocarbon is used. Good to use.

The reaction temperature is suitably 50'C to 180°C, more preferably 80 to 110°C in terms of coloration and suppression of side reactions.
It is. Further, the reaction time may be usually about 3 to 4 hours.

In the polyether obtained by the above reaction, the raw material polyol is bonded by cyclic acetal units that have excellent weather resistance, so compared to the high molecular weight polyether used as the skeleton in conventional modified silicone resins, It provides extremely excellent weather resistance to the cured resin produced.

Next, in order to produce a room temperature curable resin in the second invention, the organic silane compound reacted with the polyether has the general formula HSi (R)n(X)3- (wherein R is a hydrogen atom). , an alkyl group or aryl group having 1 to 12 carbon atoms, X is a hydrolyzable group, and n is an integer of 0 to 2), specifically trichlorosilane. , halogenated silanes such as methyldichlorosilane and dimethylchlorosilane; alkoxysilanes such as trimethoxysilane, triethoxysilane, methyldimethoxysilane and methyldimethoxysilane; alkoxysilanes such as methyldiacetoxysilane and phenyldiacetoxysilane; Siloxysilanes include bis(dimethylketoximate)methylsilane and bis(cyclohexylketoximate silane).

Among the above-mentioned compounds, alkoxysilanes are more preferable because the compounds produced during curing of the obtained resin are volatilized with low molecular weight alcohol and do not have any adverse effect on the cured resin.

In the reaction between polyether and the above-mentioned organosilane compound (hereinafter referred to as silylation reaction), it is preferable to use approximately the same mole of the organosilane compound as the allyl group introduced into the polyether, and usually 1 mole of the polyether is used. A ratio of 1.5 to 2.2 mol of organosilane compound per mol is preferred.

In the silylation reaction, it is preferable to use a platinum-based catalyst such as chloroplatinic acid, platinum metal, and platinum olefin complex, and the reaction temperature is preferably 50°C to 100°C.

Further, the reaction can be carried out either without a solvent or in a solvent system.

The room temperature curable resin obtained by the above operation is three-dimensionally crosslinked by the action of atmospheric moisture to form a cured product having rubber-like elasticity. To accelerate the curing reaction, silanol condensation catalysts such as alkyl titanates, organosilicon titanates, tin octylate, dibutyltin laurate, dibutyltin phthalate, and dibutylamine-2-ethylhexoate may be used in combination. good.

Fillers such as calcium carbonate, magnesium carbonate, titanium oxide, talc, glass powder, power pump rack, and fumed silica can be added to the room temperature curable resin, and the preferred amount of filler added is 100 parts by weight of the room temperature curable resin. It is 10 to 200 parts by weight, more preferably 50 to 100 parts by weight.

Depending on the purpose, pigments, anti-aging agents, antioxidants,
Ultraviolet absorbers, plasticizers, tackifiers, surfactants, etc. can also be added.

[Examples and comparative examples]

EXAMPLES Below, the present invention will be explained in more detail by giving Examples. In each of the following, parts indicate parts by weight, % indicates weight %, and molecular weight indicates a number average molecular weight in terms of styrene determined by GPC.

Example 1 In a 500 d three-neck flask equipped with a stirrer, a thermometer, and a nitrogen gas inlet tube, 200 g of polypropylene glycol with a molecular weight of 3000, 21.2 g of diarylidene pentaerythritol, and paratoluenesulfonic acid (hereinafter referred to as PTSA) were placed. 2.2g of was prepared, and while stirring in a nitrogen stream,
A reaction was carried out at 100°C for 3.5 hours to obtain a polyether having a high molecular weight.

Next, an aqueous NaOH solution in an amount equal to that of the PTSA was added to the reaction solution to neutralize it. Methylene chloride was added to the solution thus obtained to dissolve the polyether in the methylene chloride layer, washed with water, and then separated. The methylene chloride layer was placed in an evaporator, and the solvent was evaporated to isolate the desired polyether.

The resulting polymer had a molecular weight of 17,500, with 80% of its terminal groups converted to allyl groups. Note that the remaining terminal groups were hydroxyl groups.

Next, 100 g of the above polyether was charged into a 200 m1 pressure-resistant glass reaction vessel equipped with a stirrer, and 0.0 g of chloroplatinic acid was added.
0.05 ml of a solution of 0.05 g dissolved in a mixed solvent of 1 ml of Improper Tool and 10 ml of tetrahydrofuran.
and 3.4g of methyldimethoxysilane, 70°
The reaction was carried out at C for 5 hours.

Through the above reaction, the terminal allyl group of the polyether was converted to a silyl-based reactive group, and the number average molecular weight was 8100.
A room temperature curable resin was obtained.

Add 5 g of dibutyltin dilaurate per 100 g of the above room temperature curable resin, mix thoroughly, and apply the resulting liquid resin on a Teflon sheet and leave it at room temperature for 2 days.
By leaving it at 0°C for 3 days and then at room temperature for 2 days,
A cured product sheet with a thickness of about 3 mm was obtained.

The physical properties of this sheet were measured using JIS-6301, and the results were as follows.

Job A Hardness: 10 Tensile strength: 4. Okgf/cm" Elongation: 340% In addition, an aging test was conducted using an ultraviolet moist forced aging tester, but no cracking or decomposition was observed up to 250 hours.

Example 2 Polypropylene glycol 20 with an average molecular weight of 10,000
By the same operation as in Example 1 using 0 parts of diarylidene pentaerythritol and 7.0 parts of diarylidene pentaerythritol, 90 parts of the terminal group
A polyether having a molecular weight of 18,000 and having an allyl group introduced therein was synthesized.

The procedure was the same as in Example 1 except that 100 parts of the above polyether and 2.50 parts of trimethoxysilane were used, and the terminal was converted to a silyl-based reactive group.
A room temperature curable resin of 9000 was obtained.

The physical properties of the cured sheet obtained from the room temperature curable resin were measured and the results were as follows.

Shore A hardness; 4 Tensile strength: 2.5kgf/cm” Elongation: 480% In addition, the results of an aging test were also good.

Example 3 The same procedure as in Example 1 was carried out using 200 parts of ethylene glycol-terminated polypropylene glycol (Asahi Olin Excenol 530) having an average molecular weight of 3000 and 24.4 parts of diarylidene pentaerythritol. , synthesized polyether.

The procedure was the same as in Example 1, except that 2.43 parts of the above polyether 100 methyldimethoxysilane was used, and the terminal was converted to a silyl-based reactive group, and the molecular weight was 950.
A room temperature curable resin of No. 0 was obtained.

The physical properties of the cured sheet obtained from the room temperature curable resin were measured and the results were as follows.

Shore A hardness; 7 Tensile strength; 4. Okgf/cm” Elongation: 350% The results of an aging test were also good.

Comparative Example 1 Polypropylene glycol 150 with an average molecular weight of 3000
A 200 m, l pressure-resistant glass reaction vessel was charged with 200 m, 1 of the mixture, stirred at 100°C under reduced pressure for 30 minutes to remove moisture, and then 2.3 parts of metallic sodium was added and heated at 120°C under reduced pressure for 8 min.
Allowed time to react.

The temperature is then lowered to 60''C, 3.54 parts of methylene chloride is added, and the reaction is carried out at 80°C for 5 hours.

Then, 2.54 parts of allyl chloride was added and
The reaction was carried out for a period of time to allylate the terminal end of the polyether.

After the reaction is complete, take out the liquid reaction product into a beaker,
1000 parts of ethyl ether is added to dissolve the polyether formed, and the precipitated salt is filtered.

By evaporating the filtrate and distilling off the volatile components, 140 parts of polypropylene glycol having an average molecular weight of 8,300 and having allyl groups introduced at the terminals were obtained. was converted into a dimethoxysilyl group and had a molecular weight of 8,500. The physical properties of a cured sheet obtained from the curable resin were as follows.

Shore A hardness: 6 Tensile strength: 2.9 kgf/cm" Elongation: 300% However, when the same aging test as in Example 1 was conducted, 2
After 00 hours, the cured resin decomposed and became a liquid.

(C) Effects of the Invention According to the first aspect of the present invention, it is possible to simultaneously and easily increase the molecular weight of a polyoxyalkylene polyol and introduce an allyl group into a polyether having a high molecular weight. Moreover, the resulting polyether is bonded with cycloacecool units that have excellent weather resistance and heat resistance, so it has superior physical properties compared to polyether used as the backbone of conventional modified silicone resins. There is.

In addition, since the room-temperature-curable resin obtained by the second invention has a polyether skeleton having the above characteristics, it has excellent weather resistance and heat resistance like the polyether, and the cured product has sufficiently good properties. Since it has high rubber elasticity, it is suitable for use as an elastic sealant or adhesive side.

Claims (1)

[Claims] 1. (a) polyoxyalkylene polyol and (b)
) A method for producing a polyether having an allyl group at the end of the molecule, which is characterized by subjecting a pentaerythritol derivative represented by the following general formula to a condensation reaction at a molar ratio (b)/(a) of more than 1. . General formula; ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) 2. Produced by the method described in claim 1, The general formula HSi (
R)_n(X)_3_-_n (wherein R is a hydrogen atom, an alkyl group or aryl group having 1 to 12 carbon atoms,
X is a hydrolyzable group, and n is an integer of 0-2. )
A method for producing a room-temperature curable resin, which comprises carrying out an addition reaction with an organic silane compound represented by: