KR100440224B1 - Preparation method of polydimethyl siloxane containing both terminal hydroxyl groups using octamethyl cyclosiloxane, potassium siloxane oleate and low molecular weight siloxane having hydroxyl group - Google Patents

Abstract

PURPOSE: A method for preparing polydimethyl siloxane containing both terminal hydroxyl groups which is excellent in storage stability, is free from offensive odor, has a uniform molecular weight and is used as the base polymer of a silicone sealant. CONSTITUTION: The method comprises the steps of polymerizing a cyclic siloxane monomer in the presence of a basic catalyst and a polymerization controller at a temperature of 100-200 deg.C under anhydrous condition; and adding a neutralizer to the polymerization reaction solution to neutralize it under reduced pressure, wherein the basic catalyst is potassium siloxane oleate represented by the formula I, the polymerization controller is a low molecular weight siloxane containing a hydroxyl group represented by the formula II, and the cyclic siloxane monomer is octamethyl cyclosiloxane. In the formula I, n is 1,000-5,000; and in the formula II, n is 5-2,000.

Description

Method for producing polydimethyl siloxane containing sock end hydroxyl group

The present invention relates to a method for preparing polydimethyl siloxane containing a sock end hydroxyl group, and more particularly, to prepare a potassium siloxane oleate catalyst and to use octamethylcyclotetrasiloxane and a siloxane containing hydroxyl group as a polymerization regulator. The present invention relates to a method for producing a polydimethyl siloxane containing a hydroxyl group in a sock end used as a base polymer of a silicone sealant.

In general, the silicone sealant is composed of a base polymer, a crosslinking agent, a coupling agent, a catalyst, a plasticizer, and a filler. In the self-reaction and curing process of the silicone sealant, the base polymer in the composition and the crosslinking agent react first, and then the curing is performed by moisture in the air to give a rubber-like elastomer.

As the base polymer used in the silicone sealant, polydimethyl siloxane (hereinafter referred to as hydroxyl group-containing siloxane) containing a hydroxyl group is generally used at the end of the polymer having a viscosity of 10,000 to 100,000 cs.

Synthesis of hydroxyl-containing siloxanes is generally carried out by cationic or anionic polymerization and condensation processes using catalysts of acid or basic reagents and monomers such as octamethylcyclotetrasiloxane, hexamethylcyclotetrasiloxane or dichlorodimethylsilane. In this case, water is used as a polymerization regulator.

Looking at the synthesis method of the hydroxyl group-containing siloxane (US Patent Nos. 4,652,662, 2,469,888, 4,157,337) reported to date there is a report using an ammonium compound as a catalyst used in the synthesis. In this case, when the ammonium compound is used as the basic reagent, the ammonia odor may be generated in the product when the catalyst is not completely neutralized after the synthesis of the hydroxyl group-containing siloxane.

In addition, a synthesis method using concentrated sulfuric acid as an acidic reagent as a catalyst for synthesis is known, in which case there is a disadvantage that the siloxane backbone by the strong acid can be decomposed during polymerization.

In addition, there has been a report of synthesizing hydroxyl group-containing siloxane using potassium hydroxide, which is a basic reagent, dissolved in cyclic ether as a catalyst, in which case potassium hydroxide dissolved in cyclic ether may be hydrated upon contact with water. The process can also adversely affect the storage stability of the catalyst.

When water is used as the polymerization regulator, water is distilled in the reaction vessel at a synthesis temperature of 100 ° C. or higher, and thus it is difficult to obtain a polymer having a constant molecular weight during the termination reaction with the polymer, thereby causing a problem in reproducibility.

Therefore, the present inventors synthesized potassium siloxane as a catalyst by first reacting potassium hydroxide with octamethylcyclotetrasiloxane in the synthesis of the hydroxyl group-containing siloxane, and the octamethylcyclotetrasiloxane and a polymerization regulator of siloxane instead of water. This invention was completed by synthesize | combining the hydroxyl group containing siloxane which is a base polymer of silicone sealant using the low molecular weight hydroxyl group containing siloxane whose repeating unit is about 50-500.

An object of the present invention is to provide a method for producing a hydroxyl group-containing siloxane which is excellent in storage stability, has no odor and has a uniform molecular weight.

Hereinafter, the present invention will be described in detail.

The present invention provides a method for producing a polydimethyl siloxane containing a hydroxy group by using a catalyst, a polymerization regulator and a cyclic monomer, wherein the catalyst is potassium siloxane oleate represented by the following structural formula (I), and a cyclic monomer Is octamethylcyclosiloxane, and the polymerization regulator is characterized by reacting with a low molecular weight hydroxyl group-containing siloxane represented by the following structural formula (II).

Wherein n is 1,000 to 5,000

Wherein n is from 5 to 2,000

The present invention will be described in more detail as follows.

The present invention relates to a method for preparing a polydimethyl siloxane containing a sock end hydroxyl group by synthesizing a catalyst and adding a polymerization regulator and a cyclic monomer prepared using the same. Methyl siloxane uses potassium siloxane oleate represented by the above formula (I) and a polymerization regulator represented by the above formula (II) as a catalyst.

Here, the method for synthesizing potassium siloxane oleate, which is the catalyst represented by Structural Formula (I), is 100-200 ° C., 3-48 in a reaction vessel in which a cyclic monomer including a catalyst of an acid or basic reagent and silicon is well dried. It can be obtained by reacting with time.

In this case, acidic reagents that may be used as catalysts include hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, or acidic clay, more preferably sulfuric acid or acidic clay, and basic reagents include sodium hydroxide, lithium hydroxide, potassium hydroxide, Cesium hydroxide or rubidium hydroxide, and the like, more preferably potassium hydroxide.

The reason is that since the synthesis of potassium siloxane is carried out at a temperature of 100 to 200 ° C., lithium hydroxide and sodium hydroxide are not dissolved in the cyclic monomer containing silicon at this synthesis temperature and thus cannot participate in the initiation reaction. . In addition, cesium hydroxide has a disadvantage in that the reactivity is too fast in the synthesis of potassium siloxane oleate, and lithium hydroxide is too slow.

Generally, the rate of polymerization by the catalyst is controlled according to the basic strength and weakness of the catalyst. When using a basic metal hydroxide catalyst, the reactivity by polymerization of cyclic monomers including silicon is determined by cesium hydroxide> rubidium hydroxide> potassium hydroxide> sodium hydroxide> lithium hydroxide. It is lowered in order. This order of reactivity is the order of cation size, and also the order of the ability of the oxygen in the siloxane backbone to act as electron donor.

In addition, cyclic monomers containing silicon which may be used in the synthesis of potassium siloxane oleate include hexamethylcyclosiloxane or octamethylcyclosiloxane.

The amount of a suitable catalyst used for the cyclic monomer containing silicon is 0.2 to 2.0%. When the amount of the catalyst exceeds 2.0%, the synthesis of colorless transparent potassium siloxane in the single phase (Homogeneous phase) cannot be synthesized, and when the amount of the catalyst is less than 0.2%, a large amount of high molecular weight hydroxyl group-containing siloxane can be synthesized. There is a disadvantage in that an amount of potassium siloxane oleate must be used.

In the synthesis of potassium siloxane, the cyclic monomer including silicon undergoes a cationic ring-opening polymerization reaction with the catalyst of the basic reagent, and in this process, the molecular weight increases through condensation of hydroxyl groups present in the siloxane backbone. At this time, water is generated as a by-product during condensation. Water generated as a by-product must be treated with a Dean-Stark trap installed in the reaction vessel.

If the by-product water is not treated separately as a trap in the reaction vessel, it is not possible to synthesize single phase colorless transparent potassium siloxane after synthesis, and it is difficult to obtain reproducible results every time.

The polymerization regulator represented by Structural Formula (II) is used in a pressurized reactor to which a mechanical stirrer is attached using a cyclic monomer including potassium siloxane oleate represented by Structural Formula (I), water, and silicon. It can obtain by reacting at 100-200 degreeC for 1 to 18 hours.

In this case, the reason for the polymerization in the pressurized reactor is that the water used for the terminating reaction is not distilled at high temperature, and participates in the terminating reaction with all the amount of physical potassium siloxane oleate added in the reaction, thereby reducing the molecular weight of the polymerization regulator. This is to obtain reproducible results in the synthesis.

The molecular weight of the polymerization regulator is adjusted according to the amount of water used. At this time, the amount of water used is suitably between 1 and 10% based on the amount of cyclic monomers including silicon, and when less than 1% is used, a high molecular weight polymerization regulator is obtained. It is accompanied by difficulty. In addition, if the amount is more than 10%, the polymerization is not performed.

As described above, the molecular weight of the polymerization regulator synthesized in the high pressure reactor is preferably n = 50 to 500 in Structural Formula (II).

In addition, since the moisture is present in the synthesized polymerization regulator, the moisture must be removed using a drying agent. At this time, if the moisture in the polymerization regulator is not completely removed, reproducible results cannot be obtained in the synthesis of the hydroxyl group-containing siloxane.

Desiccants that can be used to remove moisture include magnesium sulfate, sodium sulfate, or molecular sieves.

Synthesis of hydroxyl-containing siloxanes used in the base polymer of the final product silicone sealant can be synthesized using the cyclic monomers including potassium siloxane oleate, polymerization regulators and silicones.

At this time, the reaction vessel is a pressurized reactor equipped with a mechanical stirrer, and a suitable reaction time and reaction temperature are 4 to 24 hours and 100 to 200 ° C, respectively.

In a pressurized reactor equipped with a mechanical stirrer, a molecular stirrer is used because the molecular weight and viscosity are rapidly increased, and a pressurized reactor is used to shorten the equilibrium arrival time. Potassium siloxane oleate to be used can control the polymerization rate, the amount used is not constant.

When an excessive amount of the polymerization regulator used for molecular weight control is used, a low molecular weight hydroxyl group-containing siloxane can be obtained, and when a small amount is used, a high molecular weight hydroxyl group-containing siloxane can be obtained. Therefore, the amount of polymerization regulator to be used may vary depending on the desired molecular weight.

And octamethylcyclo siloxane is added as a cyclic monomer.

Upon completion of the polymerization of the hydroxyl group containing siloxane, the catalyst of the basic reagent present in the polymer should be neutralized with an acidic reagent. At this time, a weak acid phosphoric acid is suitable as an acidic reagent. The use of strong acids, such as hydrochloric acid or sulfuric acid, can break down the main chain of hydroxyl-containing siloxanes.

After the neutralization process of the hydroxyl group-containing siloxane by the acidic reagent, there is a small amount of water generated by the condensation reaction during the polymerization process and the cyclic monomer containing silicon which is not involved in the product. To remove them. 50-150 degreeC, 0.1-1.0 torr, and 30-120 minutes are suitable for pressure reduction conditions.

The hydroxyl group-containing siloxane thus prepared has excellent storage stability, uniform molecular weight and is colorless and transparent.

Hereinafter, the present invention will be described in detail with reference to the following Examples, but the present invention is not limited by the Examples.

Preparation Example 1

Hydroxide completely removed under a nitrogen atmosphere after installing a Dean-Stark trap to collect water distilled from the thermometer, nitrogen input system, condenser and reaction vessel in a 250 ml three-necked flask equipped with a mechanical stirrer. 135 g of octamethylcyclosiloxane was added as a cyclic monomer containing 0.7 g of potassium and silicon, and the reaction temperature was raised to 130 ° C. while stirring with a mechanical stirrer. And n = 2,340 to give a colorless transparent homogeneous phase potassium siloxane oleate.

Preparation Example 2

According to Preparation Example 1, after installing a thermometer in a decompression facility equipped with a mechanical stirrer and a 1,000 ml reaction vessel, 300 g of octamethylcyclosiloxane, 15 g of water, and water were completely removed as a cyclic monomer containing silicon under a nitrogen atmosphere. After inserting 12 g of the prepared potassium siloxane oleate, the reaction temperature was raised to 150 ° C. while stirring with a mechanical stirrer, and the reaction was carried out for 12 hours. The polymerization was carried out at low molecular weight, where n = 215, represented by Structural Formula (II). Regulators were prepared.

Example 1

Under the same experimental apparatus as Preparation Example 2, 207 g of octamethylcyclosiloxane as the cyclic monomer containing silicon, 38 g of the low molecular weight polymerization regulator prepared according to Preparation Example 2 and potassium siloxane oleate prepared according to Preparation Example 1 After inserting 1.88 g, the reaction was carried out at 170 ° C. for 14 hours.

In order to neutralize the potassium hydroxide in the hydroxy group-containing siloxane, 0.019 g (0.16 mmol) of phosphoric acid (80%) was inserted into the reaction vessel, reacted at 80 ° C for 3 hours, and octamethylcyclosiloxane remaining in the hydroxy group-containing siloxane polymerized. The reaction was terminated after depressurizing (0.6 torr, 60 minutes, 100 ° C.) to remove excess moisture. At this time, the amount of recovered octamethylcyclosiloxane was 35 g (17%), represented by the formula (II), n = 1,580 (MW: 117,200, MWD: 1.7), and contains a hydroxyl group having a viscosity of 77,000 cs (brookfield viscometer) The siloxane was obtained in 83% yield.

Example 2

Except that 202 g of octamethylcyclosiloxane, 47 g of low molecular weight polymerization regulator prepared according to Preparation Example 2 and 1.84 g of potassium siloxane oleate prepared according to Preparation Example 1 were inserted as a cyclic monomer containing silicone. Was carried out in the same manner as in Example 1.

At this time, the amount of recovered octamethylcyclosiloxane was 32 g (16%), represented by the formula (II), n = 1,445 (MW: 107,000, MWD: 2.2), the viscosity of the hydroxyl group containing 68,000 cs (brookfield viscometer) The siloxane was obtained in 84% yield.

Example 3

Except that 205 g of octamethylcyclosiloxane, 54 g of low molecular weight polymerization regulator prepared according to Preparation Example 2 and 1.86 g of potassium siloxane oleate prepared according to Preparation Example 1 were inserted as a cyclic monomer containing silicone. Was carried out in the same manner as in Example 1.

At this time, the amount of recovered octamethylcyclosiloxane was 33 g (16%), represented by the structural formula (II), n = 1,350 (MW: 100,200, MWD: 2.0) and the hydroxyl group-containing siloxane having a viscosity of 48,000 cs (brookfield viscometer) Was obtained in 84% yield.

Example 4

As a cyclic monomer containing silicon, 215 g of octamethylcyclosiloxane, 60 g of a low molecular weight polymerization regulator prepared according to Preparation Example 2 and 1.95 g of potassium siloxane oleate prepared according to Preparation Example 1 were inserted and phosphoric acid (85 %) The same process as in Example 1 was carried out except that 0.020 g (0.017 mmol) was used.

At this time, the amount of recovered octamethylcyclosiloxane was 34 g (16%), represented by the structural formula (II), n = 1,120 (MW: 83,200, MWD: 2.0), the viscosity contains a hydroxyl group of 22,000 cs (brookfield viscometer) The siloxane was obtained in 84% yield.

Example 5

Except that 218 g of octamethylcyclosiloxane, 67 g of a low molecular weight polymerization regulator prepared according to Preparation Example 2 and 1.98 g of potassium siloxane oleate prepared according to Preparation Example 1 were inserted as a cyclic monomer containing silicone. Was carried out in the same manner as in Example 1.

At this time, the amount of recovered octamethylcyclosiloxane was 34 g (16%), represented by the formula (II), n = 920 (MW: 68,200, MWD: 2.0), the viscosity of 9,800 cs (brookfield viscometer) containing a hydroxyl group The siloxane was obtained in 84% yield.

Comparative Example 1

In a 500 ml three-necked flask equipped with a mechanical stirrer, a thermometer, a nitrogen input system, and a condenser were installed, followed by octamethylcyclosiloxane as a cyclic monomer containing 1.88 g of potassium hydroxide and silicon instead of the potassium siloxane oleate used in the above example under a nitrogen atmosphere. After inserting 207 g and stirring with a mechanical stirrer for 14 hours at 170 ° C., the reaction was terminated using 2 g of water instead of the polymerization regulator used in the above examples.

Then, to neutralize the potassium hydroxide in the polymerized hydroxyl group-containing siloxane, 3.80 g (0.033 mol) of phosphoric acid (85%) was inserted into the reaction vessel and reacted at 80 ° C for 3 hours, followed by octamethyl remaining in the polymerized hydroxyl group-containing siloxane. The reaction was terminated after decompression (0.6 torr, 60 min, 100 ° C.) to remove the cyclosiloxane and water.

At this time, the amount of recovered octamethylcyclosiloxane was 45 g (22%), represented by Structural Formula (II), and a translucent hydroxyl group having n = 3,600 (MW: 260,000, MWD: 1.2) and a viscosity of 172,000 cs (brookfield viscometer). Containing siloxane was obtained in 78% yield.

Comparative Example 2

The reaction was conducted in the same manner as in Comparative Example 1, except that 4 g was used instead of 2 g of water used in Comparative Example 1 as the polymerization regulator.

At this time, the amount of recovered octamethylcyclosiloxane was 42 g (20%), represented by Structural Formula (II), n = 3,850 (MW: 285,000, MWD: 1.1), and a translucent transparent particle having a viscosity of 179,000 cs (brookfield viscometer). The hydroxyl group containing siloxane was obtained in 80% yield.

Claims (6)

In the method for producing a polydimethyl siloxane containing a sock end hydroxyl group using a basic catalyst, a polymerization regulator and a cyclic siloxane monomer, Using potassium siloxane oleate represented by the following structural formula (I) as the basic catalyst, a low molecular weight hydroxyl group-containing siloxane represented by the following structural formula (II) as the polymerization regulator, and octamethylcyclosiloxane as the monomer, 100 After polymerization at an anhydrous condition at a temperature of ~ 200 ℃, Method for producing a polydimethyl siloxane containing a sock end hydroxyl group characterized in that the neutralizing agent is added to the polymerization reaction solution and neutralized under reduced pressure. Wherein n is 1,000 to 5,000, Wherein n is from 5 to 2,000. The potassium siloxane oleate represented by Structural Formula (I) used as the catalyst according to claim 1, wherein 0.2 to 2.0% of a base or an acidic reagent is added to a cyclic monomer containing silicon and then 3 to 48 hours at 100 to 200 ° C. Method for producing a polydimethyl siloxane containing a sock end hydroxyl group, characterized in that the reaction. The method of claim 2, wherein the basic reagent is sodium hydroxide, lithium hydroxide, potassium hydroxide, cesium hydroxide or rubidium hydroxide. The method of claim 2, wherein the acidic reagent is hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, or acidic clay. The low molecular weight hydroxyl group-containing siloxane represented by Structural Formula (II) used as the polymerization regulator is 1 to 10% of cyclic monomer and water containing silicon in potassium siloxane oleate represented by Structural Formula (I). The method for producing polydimethyl siloxane containing a sock end hydroxyl group, which is prepared by adding and reacting at 100 to 200 ° C. for 1 to 18 hours in a pressurized reactor, followed by drying with a desiccant. The method of claim 5, wherein the desiccant is magnesium sulfate, sodium sulfate or molecular sieve.