JP4931342B2 - Denture base coating material - Google Patents

Description

  The present invention relates to a coating material that imparts appropriate moisture retention to a denture base used by xerostomia patients.

  Xerostomia, also known as dry mouth, is a type of xerosis with chief complaints in the mouth and thirst, and is one of the modern diseases in which patients are increasing with dry eye, which is xerosis that appears in the eyes. Xerostomia, in mild cases, is caused by symptoms such as stickiness in the mouth, cavities, increased plaque and tongue banding, and associated bad breath. There are cases where the so-called “lingual pain” causes eating disorders that cannot be eaten, and pronunciation problems such as difficulty in speaking during conversation.

  The cause of xerostomia is said to be due to stress, living environment, aging and side effects caused by drugs. On the other hand, in general, denture users are often elderly, and the frequency of taking drugs derived from adult diseases is high. Therefore, the number of patients with xerostomia among denture users is increasing.

  When a denture user suffers from xerostomia, the denture is poorly retained and easily dislodged, and the oral mucosa dries so that friction with the denture increases and you feel pain, This is one of the causes of the loss of quality of life for denture users.

  A fundamental cure for xerostomia has not yet been found, and there is currently only a coping method such as a mouthwash with high moisturizing power, a moisturizing gel, or spraying with a spray. However, the above countermeasure has a drawback that the effective time is as short as several hours, and it is necessary to deal with it many times a day. In particular, in the case of a denture user who needs care, it is difficult for the denture user himself to perform treatment on the denture and the oral cavity, and a coping method that maintains the effect has been eagerly desired.

  On the other hand, as a copolymer of a hydrophilic monomer and a hydrophobic monomer used as a coating material for medical-related materials, a copolymer obtained by random copolymerization of 2-methacryloyloxyethyl phosphorylcholine (hereinafter MPC) and butyl methacrylate. Coalescence is known (see, for example, Patent Document 1). By coating the copolymer on the resin base material, it is excellent in biocompatibility and resistant to contamination by proteins and the like, and thus, for example, a medical material such as a catheter having a coating layer excellent in antithrombotic properties can be provided.

  The coating layer using the copolymer has moisture retention based on a hydrophilic monomer, and is considered useful as a coating material for dentures as described above.

JP-A-9-3132

  However, the coating layer using the copolymer does not have sufficient durability as a denture base coating agent, and there is still room for improvement. That is, under relatively mild conditions such as blood flow as in a catheter, the coating layer using the copolymer exhibits a certain degree of durability against peeling. However, when a coating using the copolymer is to be applied to the denture base, the denture has a shearing force between the coating layer and the oral mucosa every time it is chewed. There existed a problem that it peeled and lose | disappeared and durability was insufficient. Furthermore, in the case of dentures, it is often washed with a denture cleaner for cleaning, and when the dentures that have been coated with a commercially available denture cleaner are washed, the effect of coating is easily lost. there were.

  Accordingly, there is a need to provide a material that is compatible with moisture retention that can be used as a denture coating material for dry mouth patients and durability, that is, good adhesion to a denture.

  As a result of diligent investigations to solve the above problems, the present inventors considered that it is difficult to achieve both adhesion to denture and water retention by simply using a random polymer, and further studies were made. As a result of the progress, a hydrophilic polymer segment having a constant chain length, such as a polymer of MPC, and a hydrophobic polymer having a constant chain length having a structure close to polymethyl methacrylate (hereinafter referred to as PMMA) as a denture material If it is a polymer having segments and the polymer satisfies the condition that it is water-insoluble, it has sufficient moisture retention when coated on a denture, and also improves adhesion to the denture As a result, it was found that a coating layer having durability was obtained, and the present invention was completed.

（但し、Ｒ _１ 、Ｒ _２ は各々独立に水素原子またはメチル基を示し、ｎは１〜１０の整数） That is, the present invention relates to a polymer block and a hydrophobic monomer based on a hydrophilic monomer in which the hydrophilic monomer is a phosphorylcholine group-containing (meth) acrylic acid ester monomer represented by the following formula (1). A non-crosslinked copolymer volatile organic solvent solution that is both insoluble in water and is a diblock copolymer comprising a hydrophilic segment-hydrophobic segment. Polymer, or hydrophilic segment-hydrophobic segment-triblock copolymer consisting of hydrophilic segment or hydrophobic segment-hydrophilic segment-hydrophobic segment, or a hydrophobic segment as a backbone polymer and a hydrophilic segment as a branched polymer Graft copolymer or hydrophilic segment as the backbone polymer and hydrophobic segment as the branch polymer A denture coating material is a raft copolymer.

_{(Wherein, R 1,} R ₂ each independently represents a hydrogen atom or a methyl radical, n is an integer of from 1 to 10)

  By coating the denture base coating material of the present invention on the mucosal surface of the denture base of a dry mouth patient, a suitable moisturizing property can be obtained, and a coating material that can maintain the effect for at least one week can be provided. .

  The coating material used in the present invention has both a polymer block based on a hydrophilic monomer and a polymer block based on a hydrophobic monomer, and is a non-crosslinked copolymer that is insoluble in water ( Hereinafter, it may be simply referred to as a copolymer in the present invention) and a volatile organic solvent as essential components.

  On the other hand, even when a copolymer having both a portion based on a hydrophilic monomer and a portion based on a hydrophobic monomer is used as a polymerization unit, a random copolymer in which these do not form a polymer block or With the alternating copolymer, moisture retention can be obtained, but sufficient durability cannot be obtained. Further, when a polymer that dissolves in water is used, such a polymer is dissolved in saliva, drinking water, etc., and the required durability cannot be obtained. Here, the copolymer is insoluble in water means that the copolymer is dispersed in 100 times the amount of water at 37 ° C., and then the dry weight after filtration is 95% or more based on the initial weight. It means that.

  Moreover, when it is a crosslinked polymer, a solution cannot be adjusted and a denture cannot be coated.

  The copolymer used in the present invention includes both a polymer block based on a hydrophilic monomer (hereinafter also referred to as a hydrophilic segment) and a polymer block based on a hydrophobic monomer (hereinafter also referred to as a hydrophobic segment). If you have. Here, the polymer block means that the number of repeating polymer units based on a hydrophilic monomer or a hydrophobic monomer is 10 or more.

  In such a copolymer, the hydrophobic segment exhibits sufficient adhesion by being entangled with a resin matrix (in many cases, an acrylic resin such as polymethylmethacrylate) that forms a denture base, while it is hydrophilic. The sex segment is thought to play a role in moisture retention.

Examples of such a copolymer include, for example, a block copolymer in which a hydrophilic segment and a hydrophobic segment are bonded without branching, a trunk polymer composed of either a hydrophilic segment or a hydrophobic segment, and the other segment. A block copolymer in which is bonded as a branch polymer can be used in the present invention .

  The copolymer in the present invention only needs to have one each of the hydrophilic segment and the hydrophobic segment. For example, alternating portions of the hydrophilic monomer and the hydrophobic monomer are not included. Alternatively, it may have a polymer chain produced by random copolymerization, or a polymer chain having a repeating number of 9 or less based on only one of a hydrophilic monomer and a hydrophobic monomer. However, in order to obtain better moisture retention and durability, 50% or more of all repeating units (that is, 50 mol% or more of all monomers involved in polymerization) are hydrophilic segments or hydrophobic. A copolymer forming a segment is preferable, more preferably 70% or more, and particularly preferably 90% or more.

  For the same reason, it is not classified as a hydrophilic segment or a hydrophobic segment, but it has a segment part (repetition number is 2 to 9) based only on either the hydrophilic monomer or the hydrophobic monomer. A copolymer having an average repeating unit of 10 or more including both such a segment and a hydrophilic segment or a hydrophobic segment is preferred. Furthermore, when the copolymer is a block copolymer in which the other segment is bonded as a branch polymer to a trunk polymer composed of either a hydrophilic segment or a hydrophobic segment, the branch polymer in the trunk polymer The average of repeating units is preferably 10 or more.

  In the copolymer used in the present invention, the ratio between the hydrophilic segment and the hydrophobic segment is not particularly limited, but both good moisture retention and durability can be easily obtained, and further, a water-insoluble copolymer can be obtained. From the viewpoint of easily forming a polymer, the total ratio of each repeating unit is preferably in the range of 1: 5 to 5: 1, and more preferably in the range of 1: 3 to 3: 1.

Further, the molecular weight of the copolymer used in the present invention is not particularly limited, but from the viewpoint of durability and ease of handling when used as a solution, the number average molecular weight is 5 × 10 ³ to 1 × 10 ^6. Copolymers in the range are preferred. The higher the molecular weight, the better the durability, but if the molecular weight is too high, the viscosity when dissolved in the solution will be too high, and the coating operability will be inferior, and in extreme cases the solution may not be prepared. To do.

  The copolymer as described above is obtained according to a known block copolymer or graft copolymer production method using a hydrophilic monomer and a hydrophobic monomer as raw materials.

In the present invention, the hydrophilic monomer has a number average molecular weight in terms of standard polystyrene of 2 × 10 ⁴ and a molecular weight distribution (weight average molecular weight / number average molecular weight) within a range of 1 to 2. This refers to a polymerizable monomer in which the homopolymer is completely dissolved when 1 g of the homopolymer is added to 100 g of water at 37 ° C.

  Specific examples of suitable hydrophilic monomers include N-vinylpyrrolidone; 4-vinyl-N-methylpyridinium chloride, 4-vinyl-N-ethylpyridinium chloride, 4-vinyl-N-methylpyridinium bromide, 4 -Quaternized vinyl pyridines such as vinyl-N-ethylpyridinium bromide; Alkali metal salts of (meth) acrylic acid such as sodium (meth) acrylate and potassium (meth) acrylate; 2-hydroxyethyl (meth) acrylate (Meth) acrylic acid esters such as 2-hydroxypropyl (meth) acrylate; (meth) acrylamides such as N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-diisopropylacrylamide; ethylene oxide, Examples include propylene oxide.

  Furthermore, in the present invention, the following formula (1),

(However, R ₁ and R ₂ each independently represents a hydrogen atom or a methyl group, and n is an integer of 1 to 10) and a (meth) acrylic acid ester-containing monomer represented by .

  Specific examples of the phosphorylcholine group-containing (meth) acrylic acid ester monomer represented by the above formula (1) include 2- (meth) acryloyloxyethyl-2 ′-(trimethylammonio) ethyl phosphate, 2- (Meth) acryloyloxypropyl-2 '-(trimethylammonio) ethyl phosphate, 2- (meth) acryloyloxyethoxyethyl-2'-(trimethylammonio) ethyl phosphate, 2- (meth) acryloyloxydi 2- (meth) acryloyloxyethyl phosphorylcholines such as ethoxyethyl-2 ′-(trimethylammonio) ethyl phosphate, 2- (meth) acryloyloxytriethoxyethyl-2 ′-(trimethylammonio) ethyl phosphate, etc. Is mentioned.

Among them, a compound in which R ₂ is a hydrogen atom and n is 1 in the above formula (1), that is, 2- (meth) acryloyloxyethyl-2 ′-(trimethylammonio) ethyl phosphate (MPC) is particularly preferable. is there. In this MPC, for example, 2-bromoethyl phosphoryl dichloride and 2-hydroxyethyl methacrylate are reacted to obtain 2-methacryloyloxyethyl-2′-bromoethyl phosphate (MBP), and the MBP is dissolved in a methanol solution of trimethylamine. It can be synthesized by reaction.

  The copolymer in the present invention may be one using a plurality of different polymerizable monomers as the hydrophilic monomer. That is, the hydrophilic segment is not necessarily a homopolymer block based on a single type of hydrophilic monomer, and may be a copolymer block based on two or more types of hydrophilic monomers, or a block copolymer. If the graft copolymer has two or more hydrophilic segments, they may be based on different hydrophilic monomers.

In the present invention, the hydrophobic monomer means a single weight having a number average molecular weight of 2 × 10 ⁴ in terms of standard polystyrene and a molecular weight distribution (weight average molecular weight / number average molecular weight) within a range of 1 to 2. This refers to a polymerizable monomer in which 1 g of the combined product is dispersed in 100 g of water at 37 ° C. and then filtered and the dry weight becomes 95% or more based on the initial weight.

  Specific examples of suitable hydrophobic monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, ethylhexyl (meth) acrylate, and the like. Alkyl (meth) acrylates, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, alkyl ether (meth) acrylates such as butoxyethyl (meth) acrylate, acetyloxyethyl (meth) acrylate, propionoxyethyl ( Examples include meth) acrylate, butanoneoxyethyl (meth) acrylate, acetoacetoxyethyl (meth) acrylate, and the like.

  Among the hydrophobic monomers, a lower alkyl ester of (meth) acrylic acid is preferable in terms of high compatibility with PMMA which is a general night guard material, and methyl (meth) acrylate can be most preferably used. .

  The copolymer in the present invention is the same as the hydrophilic monomer in that a plurality of different polymerizable monomers may be used as the hydrophobic monomer.

  Examples of the method for producing a block copolymer using the hydrophilic monomer and the hydrophobic monomer as described above include, for example, benzyl-N, N-diethyldithiocarbamate and xylylene bis (N, N-diethyl). Applying the technique of living radical polymerization using iniferters such as dithiocarbamate), a method of sequential polymerization of a hydrophobic monomer and a hydrophilic monomer, and a terminal polymerized in the presence of 2-mercaptoethanol A polymer of a hydrophobic monomer having a hydroxyl group is reacted with a hydrophilic monomer and a polymer initiator obtained by reacting azoisobutyronitrile or 4,4′-azobis (4-cyanopentanoic acid chloride). A living monomer anionic polymerization under light irradiation using a tetraphenylporphyrinatomethylaluminum complex, and a hydrophobic monomer and a hydrophilic monomer And the like method of manufacturing by sequential performing polymerization of.

The block copolymer obtained by such a method includes a diblock copolymer comprising a hydrophilic segment-hydrophobic segment, a hydrophilic segment-hydrophobic segment-hydrophilic segment, or a hydrophobic segment-hydrophilic segment-hydrophobic. triblock copolymer of sexual segment Ru mentioned.

  Examples of methods for producing graft copolymers include radicals having a polymer group such as 2,2′-azobis (2-methacryloyloxyethylbenzene), methacryloyloxyethyl-tert-butylperoxycarbonate, and the like. A method of synthesizing a branched polymer from a polymerization initiator and a hydrophilic monomer, and then copolymerizing the hydrophobic monomer and the branched polymer, radical polymerization of the hydrophilic monomer in the presence of thioglycolic acid And then synthesizing a branched polymer having a carboxyl group at the end, and subsequently reacting with glycidyl methacrylate to chemically bond the polymerized group, followed by radical polymerization with a hydrophobic monomer and the like. It is done.

  By such a method, a copolymer having a hydrophobic segment as a trunk polymer and a hydrophilic segment as a branch polymer and a copolymer having a hydrophilic segment as a trunk polymer and a hydrophobic segment as a branch polymer can be obtained. However, a copolymer having a hydrophobic segment as a backbone polymer is more preferable in that the effects of the present invention can be easily obtained.

  The second component in the coating material of the present invention is a volatile organic solvent. The organic solvent is not particularly limited as long as it dissolves the copolymer and volatilizes in a temperature range from room temperature to 100 ° C. Specific examples of solvents that can be used include alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, cyclic ethers such as oxirane, tetrahydrofuran and 1,4-dioxane, Examples include ketones such as acetone and methyl ethyl ketone, chlorinated hydrocarbons such as methylene chloride and chloroform, acetonitrile, and dimethylformamide. The said volatile organic solvent may be used independently, and multiple types may be mixed and used for it.

  In the coating material of the present invention, the blending ratio of the copolymer and the volatile organic solvent is not particularly limited, and may be appropriately set depending on the type and molecular weight of the copolymer used, the type of the volatile organic solvent, and the like. Good. In general, a solution having a copolymer concentration in the range of 0.1 to 50% by mass is preferable. When the amount of the copolymer is too small, it may be necessary to repeatedly apply the coating many times in order to obtain sufficient moisture retention. On the other hand, when the blending amount is too large, the viscosity of the solution becomes high and it becomes difficult to perform operations such as application of the solution. More preferably, it is in the range of 1 to 20% by mass.

  The coating material of the present invention only needs to contain the above-described copolymer and volatile organic solvent in the present invention, but other components are blended as necessary unless the effects of the present invention are impaired. May be.

  For example, in order to improve adhesiveness, a hydrophobic polymer having excellent compatibility with the resin constituting the denture base can be added. Examples of such a hydrophobic polymer include polymethyl methacrylate, polyethyl methacrylate, polyisopropyl methacrylate homopolymers, and copolymers thereof.

  For the purpose of adjusting the viscosity, it is possible to add a hydrophilic polymer other than the copolymer in the present invention. However, since such a hydrophilic polymer tends to be lost as the denture is used, it is not preferable to add a large amount thereof. In the case of blending, the blending amount is 50 parts by mass or less, preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less with respect to 100 parts by mass of the copolymer in the present invention.

  Moreover, you may mix | blend a small amount of water for the purpose of adjusting the solubility etc. of the various polymers to mix | blend. In this case, since the copolymer in the present invention tends to be insoluble when blended in an excessively large amount, it is 50 parts by mass or less, preferably 30 parts by mass or less, particularly preferably 100 parts by mass of the volatile organic solvent. It may be 10 parts by mass or less.

  Furthermore, it is also possible to mix | blend components, such as a fragrance | flavor, a pigment | dye, a pigment, a refreshing agent, antiseptic | preservative, and an antibacterial agent, with the coating material of this invention.

  The method of using the coating material of the present invention is not particularly limited as long as it can coat the denture base, and application by brush or brush, dip coating, spin coating, spraying, or the like is suitably performed. In particular, application with a brush or a brush, which does not require a special device and requires a minimum amount of coating material solution, is suitable. The coating material applied to the denture base is appropriately dried before use. The drying method is not particularly limited, and heating may be performed at room temperature. Moreover, it can also blow and dry. By drying, the volatile organic solvent blended in the coating material is removed, and the copolymer in the present invention (and the nonvolatile component blended as necessary) remains, which forms a coating layer. To do.

  In addition, prior to the denture base coating in the present invention, a conventionally known coating pretreatment can also be performed. Examples thereof include a method of washing with water after applying a basic aqueous solution to the mucosal surface of the denture base, corona discharge treatment, plasma treatment, flame treatment and the like. The above-mentioned treatment is known as a treatment for imparting a polar group to the surface layer of the denture that is the adherend, and it is expected that the interaction with the hydrophilic segment of the copolymer in the present invention forming the coating layer will increase. The

  The coated denture base is used with its surface wetted with tap water or the like immediately before use by the patient. Pain caused by mucous membrane tension can be alleviated. Moreover, the effect is maintained for a certain period of time and can be reused even when the denture base is once removed from the oral cavity.

  Examples are provided to specifically describe the present invention, but the present invention is not limited to these examples.

(1) Classification of polymerizable monomer In order to determine whether the polymerizable monomer used corresponds to a hydrophilic monomer or a hydrophobic monomer, classification is performed using the following determination method. It was.

A glass polymerization tube was charged with 30 g of a polymerizable monomer, 0.95 g (8.0 mmol) of hexyl mercaptan, 0.16 g (1.0 mmol) of azobisisobutyronitrile (AIBN), and 50 ml of benzene. Was repeated and replaced with a nitrogen atmosphere. Heating was performed at 60 ° C., and a part of the contents was sampled from 3 hours after the start of heating, and the molecular weight of the polymer was traced using gel permeation chromatography (GPC: HLC-8020 manufactured by Tosoh Corporation). . When the number average molecular weight of the produced polymer reached 2.0 × 10 ⁴ , heating was stopped and the reaction was stopped. The obtained polymer was precipitated in a poor solvent according to the type of the polymer, and then dried under reduced pressure until a constant weight was obtained.

When methyl methacrylate (MMA) was used as the polymerizable monomer, the homopolymer was obtained by putting the polymer solution obtained as a result of solution polymerization into methanol, precipitating and drying. As a result of GPC analysis again, the number average molecular weight was 2.2 × 10 ⁴ and the molecular weight distribution was 1.9. After dispersing 1.0 g of the powdery MMA homopolymer thus obtained in 100 g of water at 37 ° C. and stirring for 15 h, the undissolved content was collected by filtration and dried under reduced pressure until a constant weight was obtained. As a result, the dry weight was 1.0 g, and it was confirmed that MMA is a hydrophobic monomer.

When MPC is used as the polymerizable monomer, the polymer solution obtained as a result of solution polymerization is poured into a hexane-diethyl ether (3: 2) mixed solution, precipitated, and dried to give the homopolymer. Got. As a result of re-analysis by GPC, the number average molecular weight was 2.1 × 10 ⁴ and the molecular weight distribution was 2.0. As a result of dispersing 1.0 g of the powdered MPC homopolymer thus obtained in 100 g of water at 37 ° C. and stirring, the polymer was quickly and completely dissolved in water. This confirmed that MPC is a hydrophilic polymer.

(2) Production Example 1 Synthesis of Block Copolymer of MPC and MMA Benzyl-N, N-diethylthiocarbamate (BDC) synthesized from benzyl chloride and N, N-diethyldithiocarbamate Na salt was distilled under reduced pressure. . The obtained purified BDC (0.19 g, 0.78 mmol), MMA (69 g, 0.69 mol) and benzene (100 ml) were placed in a glass polymerization tube, freeze-degas was repeated, and the tube was sealed under vacuum. Ultraviolet irradiation (irradiation from a distance of 10 cm using Toshiba SHL100 as a light source) was performed at 30 ° C. for 15 hours. The tube was opened, and the contents were precipitated in a large amount of methanol, followed by vacuum drying. The number of terminal N, N-dithiocarbamate of the obtained MMA polymer was determined from the number average molecular weight (Mn) calculated from the UV and viscosity of the polymer using UV of BDC (λmax: 282 nm, ε10500 in cyclohexane) as a standard. It was done. The polymerization rate was 30%, Mn = 6.4 × 10 ⁴ , and the number of terminal SC (S) NEt ₂ was 0.99.

The above-mentioned terminal SC (S) NEt _2- group-introduced PMMA 2.0 g, MPC 4.0 g, and THF 20 ml were charged into a sealed tube, and light irradiation was performed in the same manner as in MMA polymerization to carry out polymerization. The resulting content was added dropwise to a hexane-diethyl ether (3: 2) mixture to precipitate a block copolymer. The dry weight of the obtained precipitate was 3.6 g. ^From the result of ¹ H-NMR, the molar ratio of MMA: MPC in the copolymer was 1: 0.27.

(3) Production Example 2 Synthesis of graft copolymer of MPC and MMA MPC 30 g (0.10 mol), thioglycolic acid 1.8 g (20 mmol), AIBN 0.16 g (1.0 mmol) were placed in a glass polymerization tube. After repeated freeze degassing, the film was sealed under vacuum. After heating at 60 ° C. for 5 hours, the mixture was cooled, opened, and poured into a hexane-diethyl ether (3: 2) mixture to cause precipitation. Yield 50%. Mn = 4.0 × 10 ³ (titration of terminal carboxylic acid with 0.1 NKOH aqueous solution using phenolphthalein / ethanol indicator in THF).

  The terminal carboxylic acid-terminated prepolymer was placed in a flask equipped with a reflux condenser together with 1.5 times moles of glycidyl methacrylate, a small amount of hydroquinone and dimethyllaurylamine, and heated and refluxed overnight in THF under nitrogen. After confirming that no terminal carboxylic acid remained by titration, it was purified by precipitation into a hexane-diethyl ether (3: 2) mixture.

The above-mentioned macromonomer 1.6 g, MMA 2.2 g, AIBN 0.010 g and THF 10 ml were charged into a glass polymerization vessel, sealed after freeze degassing, and heated at 60 ° C. for 7 days. After cooling, the contents were precipitated in a hexane-diethyl ether (3: 2) mixture. The yield was 3.7 g (number average molecular weight 2.4 × 10 ⁴ : standard polystyrene conversion).

(4) Denture stabilizer immersion durability test 0.50 g of the copolymer was dissolved in 5.0 ml of THF-methylene chloride (1: 1) mixed solvent to prepare a coating solution. The coating solution was applied to a 20 × 20 × 1 mm PMMA plate whose weight was measured in advance, and then dried at room temperature. Thereafter, after drying under reduced pressure, the weight of the sample was measured, and the weight of the coating layer was determined by subtracting it from the weight of only the PMMA plate. Next, the sample was immersed in distilled water for 10 days, and the weight of the sample was measured. The initial water absorption rate of the coating layer (%) {= 100 × (weight after water absorption−weight before water absorption) / weight of coating layer) } Was requested.

  An aqueous solution of a commercially available denture cleaning agent “Polydent” (manufactured by Kobayashi Pharmaceutical Co., Ltd.) was prepared by a method designated by the manufacturer, and the water absorption sample was immersed for 10 hours. Next, the denture cleaning agent-treated sample was immersed in distilled water for 14 hours. After such denture cleaning treatment-distilled water immersion was repeated seven times, the sample was washed with water and dried under reduced pressure, the weight of the sample was determined, and the ratio of the residual coating layer was determined.

  The sample after the denture stabilizer immersion durability test was again immersed in distilled water to determine the water absorption rate of the remaining coating layer.

Example 1
The block copolymer synthesized in Production Example 1 was used as a coating substrate. The block copolymer swelled in water but did not dissolve. Further, 1.0 g of the block copolymer was dispersed in 100 g of water and stirred for 15 hours, and then the undissolved content was collected by filtration and dried under reduced pressure until a constant weight was obtained. As a result, it was confirmed that the present block copolymer was essentially insoluble in water. A coating solution was prepared by dissolving 0.50 g of the block copolymer in 5.0 ml of THF-methylene chloride (1: 1). The test results of the coating samples are shown in Table 1. The initial water absorption rate of the coating layer was 67%, indicating good moisture retention. Further, the ratio of the remaining coating layer after the denture cleaning agent immersion test was 92%. Further, as a result of moisture absorption of the sample again, the water absorption was 65%, and it was found that the moisture retention was maintained.

Example 2
The same evaluation as in Example 1 was performed except that the graft copolymer synthesized in Production Example 2 was used as a coating substrate. The graft copolymer swelled in water but did not dissolve. Further, 1.0 g of the block copolymer was dispersed in 100 g of water and stirred for 15 hours, and then the undissolved content was collected by filtration and dried under reduced pressure until a constant weight was obtained. As a result, it was confirmed that the present block copolymer was essentially insoluble in water. The initial water absorption rate of the coating layer was 72%, indicating good moisture retention. Moreover, the ratio of the residual coating layer after the denture cleaning agent immersion test was 98%. As a result of moisture absorption of the sample again, the water absorption was 72%, and it was found that the moisture retention was maintained.

Comparative Example 1
Evaluation similar to Example 1 was performed except that a copolymer of MPC and MMA randomly copolymerized (MPC content in the copolymer: 40 mol%) was used as a coating substrate. The random copolymer was dissolved in water. Therefore, the initial water absorption rate of the coating layer could not be measured because the coating layer was peeled off while the coating sample was immersed in distilled water. Moreover, even if the sample after water immersion was dried under reduced pressure and the sample was again moisture-absorbed, it was found that the water absorption was 0.1% and the moisture retention was not maintained.

Comparative Example 2
Evaluation similar to Example 1 was performed, except that a copolymer of random copolymerized MPC and MMA (MPC content 20 mol% in the copolymer) was used as a coating substrate. The graft copolymer swelled in water but did not dissolve. The initial water absorption of the coating layer was 66%, indicating good moisture retention. However, the ratio of the remaining coating layer after the denture cleaning agent immersion test was about 4%, and it was found that the coating layer was almost lost. Even when the sample was again moisture-absorbed, the water absorption was 1%, indicating that the moisture retention was not maintained.

Claims (1)

A polymer block based on a hydrophilic monomer and a polymer block based on a hydrophobic monomer , wherein the hydrophilic monomer is a phosphorylcholine group-containing (meth) acrylic acid ester monomer represented by the following formula (1) : A diblock copolymer comprising a hydrophilic segment-hydrophobic segment, or a hydrophilic block, comprising a volatile organic solvent solution of a non-crosslinked copolymer that is both insoluble in water. Triblock copolymer consisting of hydrophilic segment-hydrophobic segment-hydrophilic segment-hydrophobic segment-hydrophilic segment-hydrophobic segment, or graft copolymer with hydrophobic segment as backbone polymer and hydrophilic segment as branch polymer Or a graft copolymer with a hydrophilic segment as the backbone polymer and a hydrophobic segment as the branch polymer. Denture coating material that.

_{(Wherein, R 1,} R ₂ each independently represents a hydrogen atom or a methyl radical, n is an integer of from 1 to 10)