Method for producing polymeric silane coupling agent having isocyanate group

Abstract

To synthesize a polymeric silane coupling agent having an isocyanate group.SOLUTION: A method for producing a polymeric silane coupling agent includes: step [i] reacting a compound bearing both a radically polymerizable group and a silicon alkoxide group in its chemical structure with a polymerization initiator to provide a polymer bearing a pendant silicon alkoxide group; step [ii] polymerizing a compound bearing both a radically polymerizable group and a protected isocyanate group in its chemical structure with the polymer derived from step [i]; and step [iii] subjecting the polymer derived from step [ii] to thermal deprotection of the isocyanate group.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing an AB block type polymer silane coupling agent having a polyethylene main chain as a basic skeleton and at least one or more protected isocyanate groups and silicon alkoxide groups in side chains, which is used in a novel medical and dental curable composition used in the medical and dental fields. More specifically, the present invention relates to a method for producing an AB block type polymer silane coupling agent having at least one or more protected isocyanate groups and silicon alkoxide groups in side chains, which is synthesized by atom transfer radical polymerization (ATRP).

Background Art

[0002] In the medical and dental fields, metal prostheses, synthetic resin moldings, etc. are used to repair bone and tooth defects. Adhesives containing adhesive polymerizable monomers are frequently used for adhesion to these living hard tissues. In the medical and dental fields, a medical and dental curable composition called composite resin is used clinically every day. This is obtained by filling a defect site such as a tooth with an uncured body (before radical polymerization) paste and then applying external energy such as light irradiation to obtain a radical polymerization cured body.

[0003] Generally, these adhesives and composite resins use (meth)acrylic acid derivative monomers such as methyl methacrylate, triethylene glycol dimethacrylate, and urethane dimethacrylate. In the free radical polymerization of vinyl monomers such as these (meth)acrylic acid derivative monomers (hereinafter referred to as radical polymerization), a polymer is formed and cured by the cleavage of the carbon-carbon double bond to form a single bond. In this composite resin, not only vinyl monomers but also inorganic fillers are added for the purpose of improving mechanical strength. Generally, these inorganic fillers are surface-treated with a silane coupling agent having a polymerizable group to improve wettability and mechanical strength. Particularly in the dental field, γ-methacryloxypropyltrimethoxysilane (®KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) has been widely used as a silane coupling agent. When particles surface-treated with this compound are used, a radical polymerizable group is introduced at the terminal, the surface of the inorganic filler is hydrophobized, and radical copolymerization with (meth)acrylic acid derivative monomers such as methyl methacrylate, triethylene glycol dimethacrylate, and urethane dimethacrylate is expected. However, what is expected from such a silane coupling agent is, of course, only radical polymerization. Therefore, there has been a demand for the stable introduction of an isocyanate group, which is expected to have a more diverse bonding method, onto the surface of an inorganic filler. That is, prior to the present invention, in order to improve the durability and filling rate of materials, methods of using a silane coupling agent having a long alkyl chain (Patent Documents 1, 2, 3), a silane coupling agent having a fluoroalkylene group (Patent Document 4), and a silane coupling agent having a large number of polymerizable groups (Patent Document 5) have been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

[0005] The present invention can introduce an isocyanate group protected on the surface of an inorganic filler, and if necessary, generate an isocyanate group by heating and deprotecting them. As a result, when used in a curable composition for medical and dental applications, a novel silane coupling agent that provides high mechanical strength and durability, an inorganic filler surface-treated with the novel silane coupling agent, and a novel curable composition for medical and dental applications are provided. It is an object of the present invention to provide a method for synthesizing and producing a completely novel polymer silane coupling agent.

[0006] Silane coupling agents used in general industrial fields including the medical and dental fields are generally compounds with a low molecular weight of about 10 to 20 carbon atoms. These low molecular weight silane coupling agents are highly rigid, so they are relatively brittle and provide a material that is high in strength but inferior in flexibility. In order to solve these various problems, the inventors have developed a polymer silane coupling agent. However, the synthesis of a polymer silane coupling agent having a highly reactive isocyanate group has been difficult in the prior art because an undesirable reaction between the isocyanate group and free radicals proceeds. That is, the object and problem of the present invention is to provide a production method by atom transfer radical polymerization of a blocked polymer silane coupling agent having a protected isocyanate group used in a curable composition for medical and dental applications, which has high toughness and has no elution of low molecular monomers or has biohard tissue adhesiveness suppressed as much as possible and excellent operability. [Means for Solving the Problems]

[0007] In order to solve the above-described problems, as a result of intensive studies by the inventors, a method for producing a polymer silane coupling agent having an isocyanate group has been found.

[0008] According to the present invention, the following production method is provided. Step [i]: A step of reacting a compound having both a radically polymerizable group and a silicon alkoxide group in its chemical structure with a polymerization initiator to obtain a polymer having a silicon alkoxide group pendent. Step [ii]: To the polymer obtained in step [i], A step of polymerizing a compound having both a radically polymerizable group and a protected isocyanate group in its chemical structure. Step [iii]: A step of deprotecting the isocyanate group by heat treatment of the polymer obtained in step [ii]. A method for producing a polymer silane coupling agent including the above steps.

[0009] Also, according to the present invention, the following production method is provided. Step [i]: A step of reacting a compound having both a radically polymerizable group and a protected isocyanate group in its chemical structure with a polymerization initiator to obtain a polymer having a protected isocyanate group pendent. Step [ii]: To the polymer obtained in step [i], A step of polymerizing a compound having both a radically polymerizable group and a silicon alkoxide group in its chemical structure. Step [iii]: A step of deprotecting the isocyanate group by heat treatment of the polymer obtained in step [ii]. A method for producing a polymer silane coupling agent including the above steps.

[0010] The present invention also provides the following polymer silane coupling agent.

[0011]

Chemical formula

[0012] In the formula, A represents a chemical structure having a silicon alkoxide group pendant, and B represents a chemical structure having an isocyanate group pendant. Further, Z represents a structure derived from a polymerization initiator. In the formula, a and b represent the number of repetitions, both of which are in the range of 1 to 1000. The B terminal may have a halogen derived from a polymerization initiator. A and B may be reversed. It is desirable to have a molar mass distribution Mw / Mn of 1.0 to 1.8.

Effect of the Invention

[0013] The AB-block type polymer silane coupling agent having at least one or more isocyanate groups and silicon alkoxide groups protected with a polyethylene main chain as a basic skeleton according to the present invention can be synthesized very efficiently. That is, compounds having an isocyanate group at the terminal include 2-isocyanatoethyl methacrylate, etc. However, when these are radically polymerized with a peroxide such as benzoyl peroxide, a sufficient polymer cannot be obtained. This is because the isocyanate group forms dimers such as uretdione groups in an environment where free radicals coexist, so efficient radical polymerization cannot be carried out and a polymer with the desired degree of polymerization cannot be obtained. That is, in the prior art, it was difficult to synthesize an AB-block type polymer silane coupling agent having a polyethylene main chain with a high degree of polymerization as a basic skeleton and at least one or more isocyanate groups and silicon alkoxide groups in the side chain. However, since the (meth)acrylate ester having a protected isocyanate group at the terminal according to the present invention is stable to radicals, an AB-block type polymer silane coupling agent having a polyethylene main chain with the desired molecular weight as a basic skeleton and at least one or more isocyanate groups and silicon alkoxide groups in the side chain can be synthesized. That is, after block polymerizing a (meth)acrylate ester monomer having a protected isocyanate group at the terminal and a monomer having a silicon alkoxide group at the terminal by atom transfer radical polymerization to obtain a polymer silane coupling agent, by heating, the isocyanate group can be generated by deprotecting the isocyanate group protecting group. Since the generated isocyanate group is very highly active, it easily reacts with a hydroxy group, a silanol group, an amide group, a primary amine, a secondary amine, amines, an epoxy ring, a carboxylic acid, a carboxylic anhydride, and thiols. In particular, in the reaction with water, it is possible to generate a primary amine via carbamic acid. That is, it is possible to synthesize an AB-block type polymer silane coupling agent having a polyethylene main chain as a basic skeleton and at least one or more primary amino groups and silicon alkoxide groups in the side chain.More specifically, in the atom transfer radical polymerization method, polymerization of 2-aminoethyl methacrylate or the like is difficult due to the influence of its active hydrogen. Therefore, the synthesis and production method of the present invention is a very useful invention for the synthesis of an AB block type polymer silane coupling agent having a polyethylene main chain as a basic skeleton and at least one or more primary amino groups and silicon alkoxide groups in the side chain.

Mode for Carrying Out the Invention

[0014] The molecular structure of the AB block type polymer silane coupling agent having a protected isocyanate group and at least one or more silicon alkoxide groups in the side chain with a polyethylene main chain produced by the present invention as a basic skeleton is the structure shown below. When using them in a curable composition for medical and dental use, they may be used alone or in a combination of two or more. Chemical structure examples of the AB block type polymer silane coupling agent having a protected isocyanate group and at least one or more silicon alkoxide groups in the side chain with a polyethylene main chain as a basic skeleton in the present invention are described below. Note that Z indicating the initiator and the polymerization terminal Br are the same even when in reverse positions. That is, it means that it is possible to synthesize an AB block type polymer silane coupling agent having the same properties with a polyethylene main chain as a basic skeleton, differing only in the order of the monomers to be polymerized.

[0015]

Chemical Formula

[0016]

Chemical Formula

[0017]

Chemical Formula

[0018]

Chem.

[0019]

Chem.

[0020]

Chem.

[0021] Also, by heating the above-mentioned polymer silane coupling agent, the protecting group can be removed as shown below, and the isocyanate group can be regenerated.

[0022]

Chem.

[0023]

Chem.

[0024]

Chem.

[0025] As the polymerization initiator in the atom transfer radical polymerization method used in the present invention, the following compounds can be preferably used. The halogen atom to be bonded may be any of Br, Cl, and I, and the halogen atom derived from the polymerization catalyst may be substituted with a halogen-free atom and functional group using a halogen remover such as allyltributyltin.

[0026]

Chem.

Examples

[0027] A method for producing an AB block type polymer silane coupling agent having at least one or more isocyanate groups and silicon alkoxide groups protected with a polyethylene main chain as a basic skeleton in the side chain will be described in detail, but the present invention is not limited to these descriptions at all.

[0028]

Table 1-1

[0029]

Table 1-2

[0030]

Table 2-1

[0031]

Table 2-2

[0032] Polymer Synthesis Examples 1 to 6 according to the present invention Into a 100 mL Schlenk polymerization tube with a three-way stopcock that had been baked, 134 mg (0.932 mmol) of Cu(I)Br was accurately weighed, and dehydrated and degassed anisole (30 mL), nonane (0.1 mL, internal standard for tracking the polymerization reaction), n-tributylamine (polymerization cocatalyst, 92.7 mg, 0.5 mmol), and 2,2'-bipyridine (146 mg, 1.56 mmol) were successively injected into the syringe under an argon stream. The Schlenk polymerization tube was heated to 70 °C under magnetic stirring to completely dissolve the catalyst ligand. Then, a radical polymerizable monomer having a silicon alkoxide group as described in Table 1-1 (50.0 mmol) was added, stirred well to homogenize, and then 181 mg (1.00 mmol) of methyl 2-bromo-2-methylpropanoate (polymerization initiator) was added to initiate the polymerization. Samples were withdrawn under an argon stream at regular intervals, and the monomer conversion rate was measured by gas chromatography. When the monomer conversion rate reached 95%, 12.1 g (50 mmol) of (E)-2-((((butan-2-ylideneamino)oxy)carbonyl)amino)ethyl methacrylate was added all at once, and again, samples were withdrawn under an argon stream at regular intervals, and the monomer conversion rate was measured by gas chromatography. When the monomer conversion rate reached 95%, the heating was stopped, a trace amount of oxygen was bubbled in to stop the polymerization reaction, and the remaining monomer / anisole was distilled off using an evaporator. In these reaction steps, an AB block-type polymer silicon coupling agent having an isocyanate group protected with a polyethylene main chain as the basic skeleton and a silicon alkoxide group in the side chain was obtained. As a result of GPC measurement, the molar mass distributions (Mw / Mn) of the obtained AB block copolymers were 1.03, 1.02, 1.05, 1.08, 1.04, and 1.05, respectively.

[0033] Polymer Synthesis Examples 7 to 12 according to the present invention Into a 100 mL Schlenk polymerization tube with a three-way stopcock that had been baked, 134 mg (0.932 mmol) of Cu(I)Br was accurately weighed, and dehydrated and degassed anisole (30 mL), nonane (0.1 mL, internal standard for tracking the polymerization reaction), n-tributylamine (polymerization cocatalyst, 92.7 mg, 0.5 mmol), and 2,2'-bipyridine (146 mg, 1.56 mmol) were successively injected with a syringe under an argon stream. The Schlenk polymerization tube was heated to 70 °C under magnetic stirring to completely dissolve the catalyst ligand. Then, the radical polymerizable monomer having a silicon alkoxide group described in Table 1-1 (50.0 mmol) was added, stirred well for homogenization, and then 181 mg (1.00 mmol) of methyl 2-bromo-2-methylpropanoate (polymerization initiator) was added to initiate the polymerization. Samples were withdrawn under an argon stream at regular intervals, and the monomer conversion rate was measured by gas chromatography. When the monomer conversion rate reached 95%, 12.6 g (50 mmol) of 2-(3,5-dimethyl-1H-pyrazole-1-carboxamido)ethyl methacrylate was added all at once. Again, samples were withdrawn under an argon stream at regular intervals, and the monomer conversion rate was measured by gas chromatography. When the monomer conversion rate reached 95%, the heating was stopped, a trace amount of oxygen was bubbled in to stop the polymerization reaction, and the remaining monomer / anisole was distilled off with an evaporator. In these reaction steps, an AB block-type polymer silicon coupling agent having an isocyanate group protected with a polyethylene main chain as the basic skeleton and a silicon alkoxide group in the side chain was obtained. As a result of GPC measurement, the molar mass distributions (Mw / Mn) of the obtained AB block copolymers were 1.04, 1.01, 1.02, 1.05, 1.09, and 1.01, respectively.

[0034] Polymer Synthesis Examples 13 to 25 according to the present invention Weigh 1.00 g each of the AB-block type polymer silane coupling agents having an isocyanate group and a silicon alkoxide group protected with a polyethylene main chain as a basic skeleton synthesized in Synthesis Examples 1 to 12 into a 5.0 mL freezing vial. After that, add 10 mg of dibutyltin dilaurate and 3.0 mL of dehydrated anisole, and perform argon bubbling substitution to degas. Seal the ampule tube with an acetylene-oxygen gas burner. Heat them with a block heater heated to 150 °C for 3 hours. After the heating is completed, return the ampule tube to room temperature, and confirm the presence of 3,5-dimethyl-1H-pyrazole and (E)-butan-2-one oxime desorbed from the protected isocyanate group by gas chromatography. As a result, the desorption rate was 99% or more in each case, and the synthesis of the AB-block type polymer silane coupling agent having an isocyanate group and a silicon alkoxide group in the side chain with a polyethylene main chain as a basic skeleton was confirmed.

[0035] Polymer Comparative Synthesis Examples 1 to 6 Into a 100 mL Schlenk polymerization tube with a three-way stopcock that had been baked, 134 mg (0.932 mmol) of Cu(I)Br was accurately weighed, and dehydrated and degassed anisole (30 mL), nonane (0.1 mL, internal standard for tracking the polymerization reaction), n-tributylamine (polymerization cocatalyst, 92.7 mg, 0.5 mmol), and 2,2'-bipyridine (146 mg, 1.56 mmol) were injected successively with a syringe under an argon stream. The Schlenk polymerization tube was heated to 70 °C with magnetic stirring to completely dissolve the catalyst ligand. Then, a radical polymerizable monomer having a silicon alkoxide group as described in Table 2-1 (50.0 mmol) was added, and after thorough stirring and homogenization, 181 mg (1.00 mmol) of methyl 2-bromo-2-methylpropanoate (polymerization initiator) was added to initiate the polymerization. Samples were withdrawn under an argon stream at regular intervals, and the monomer conversion rate was measured by gas chromatography. When the monomer conversion rate reached 95%, 7.76 g (50 mmol) of 2-isocyanatoethyl methacrylate was added all at once, and again, samples were withdrawn under an argon stream at regular intervals, and the monomer conversion rate was measured by gas chromatography. However, the monomer conversion rate did not change or increase at all, and block polymerization could not be achieved. That is, the synthesis of the AB block type polymer silicon coupling agent having a protected isocyanate group and a silicon alkoxide group as side chains with a polyethylene main chain as the basic skeleton could not be accomplished.

[0036] Polymer Comparative Synthesis Examples 7 to 12 Into a 100 mL Schlenk polymerization tube with a three-way stopcock that had been baked, 134 mg (0.932 mmol) of Cu(I)Br was accurately weighed, and dehydrated and degassed anisole (30 mL), nonane (0.1 mL, internal standard for tracking the polymerization reaction), n-tributylamine (polymerization cocatalyst, 92.7 mg, 0.5 mmol), and 2,2'-bipyridine (146 mg, 1.56 mmol) were successively injected with a syringe under an argon stream. The Schlenk polymerization tube was heated to 70 °C under magnetic stirring to completely dissolve the catalyst ligand. Then, a radical polymerizable monomer (50.0 mmol) having a silicon alkoxide group described in Table 2-2 was added, and after sufficient stirring and homogenization, 181 mg (1.00 mmol) of methyl 2-bromo-2-methylpropanoate (polymerization initiator) was added to initiate the polymerization. Samples were withdrawn under an argon stream at regular intervals, and the monomer conversion rate was measured by gas chromatography. When the monomer conversion rate reached 95%, 7.06 g (50 mmol) of 2-isocyanatoethyl acrylate was added all at once, and again, samples were withdrawn under an argon stream at regular intervals, and the monomer conversion rate was measured by gas chromatography. However, the monomer conversion rate did not change or increase at all, and block polymerization could not be achieved. That is, the synthesis of the AB block type polymer silane coupling agent having a protected isocyanate group and a silicon alkoxide group on the side chain with the target polyethylene main chain as the basic skeleton could not be achieved.

Industrial Applicability

[0037] Silane coupling agents used in general industrial fields including the medical and dental fields are generally low molecular weight compounds having about 10 to 20 carbon atoms. Since these low molecular weight silane coupling agents are highly rigid, they are relatively brittle and provide a material that is high in strength but inferior in flexibility. In order to solve these various problems, the inventors have developed high molecular weight silane coupling agents. However, the synthesis of high molecular weight silane coupling agents having highly reactive isocyanate groups has been difficult in the prior art because an undesirable reaction between the isocyanate group and free radicals proceeds. However, by using a (meth)acrylate monomer having a protected isocyanate group at the terminal used in the present invention, it has become possible to synthesize a high molecular weight silane coupling agent having a highly reactive isocyanate group after deprotection. Since the isocyanate group is very highly active, it easily reacts with hydroxy groups, silanol groups, amide groups, primary amines, secondary amines, amines, epoxy rings, carboxylic acids, carboxylic anhydrides, thiols, and water, and thus can be used in various applications. Therefore, it can be said that the present invention has a very high potential for industrial use.

Claims

1. Step [i]: reacting a compound having both a radically polymerizable group and a silicon alkoxide group in its chemical structure with a polymerization initiator to obtain a polymer having a silicon alkoxide group pendent; Step [ii]: to the polymer obtained in Step [i], reacting a compound having both a radically polymerizable group and a protected isocyanate group in its chemical structure; Step [iii]: deprotecting the isocyanate group by heat treatment of the polymer obtained in Step [ii]; A method for producing a polymer silane coupling agent, comprising the above steps.

2. Step [i]: reacting a compound having both a radically polymerizable group and a protected isocyanate group in its chemical structure with a polymerization initiator to obtain a polymer having a protected isocyanate group pendent; Step [ii]: to the polymer obtained in Step [i], reacting a compound having both a radically polymerizable group and a silicon alkoxide group in its chemical structure; Step [iii]: deprotecting the isocyanate group by heat treatment of the polymer obtained in Step [ii]; A method for producing a polymer silane coupling agent, comprising the above steps.

3. The method for producing a polymer silane coupling agent according to Claim 1 or 2, wherein the polymerization methods in the above Step [i] and Step [ii] are Atom Transfer Radical Polymerization (ATRP).

4. The method for producing a polymer silane coupling agent according to Claim 1 or 2, wherein the compound having both a radically polymerizable group and a silicon alkoxide group in its chemical structure is selected from at least one of the following combinations. 【Chemical 1】

5. The production method according to Claim 1 or 2, wherein the chemical structure of the compound having both a radically polymerizable group and a protected isocyanate group in its chemical structure is selected from at least one of the following combinations. [Chemical 2]

6. A polymer silane coupling agent represented by the following chemical structural formula. [Chemical Formula 3] In the formula, A represents a chemical structure having a silicon alkoxide group pendent, and B represents a chemical structure having an isocyanate group pendent. Also, Z represents a structure derived from a polymerization initiator. In the formula, a and b represent the number of repetitions, both being in the range of 1 to 1000. The B terminal may have a halogen derived from a polymerization initiator. A and B may be reversed.

7. The polymeric silane coupling agent according to claim 6, which has a molar mass distribution Mw / Mn of 1.0 to 1.8.

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