Chemical polymerization initiator, adhesive composition, and kit for preparing adhesive composition

Abstract

To provide an adhesive composition that comprises a chemical polymerization initiator blended in a radical-polymerizable monomer comprising (g) a polymerizable monomer with an acidic group and (h) a polymerizable monomer without an acidic group, wherein the adhesive composition exhibits superior adhesion and superior coating thickness even when used in systems containing high levels of water and oxidative components, particularly in the case of dentin.SOLUTION: A chemical polymerization initiator comprises (a) a thiourea compound, (b) peroxyester, (c) a bivalent copper compound and (d) powder, comprising one or more ascorbates selected from 2-phospho-L-ascorbic acid trisodium salt, calcium ascorbate and sodium isoascorbate, with an average particle size of 0.1-20 μm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a chemical polymerization initiator, an adhesive composition, and a kit for preparing an adhesive composition. [Background technology]

[0002] In the dental field, radical polymerization curable compositions, which are composed of radically polymerizable monomers such as (meth)acrylates and polymerization initiators, are used in various materials such as bonding agents, resin cements, resin-reinforced glass ionomers, and composite resins. When these materials are used in applications where they cannot be exposed to light or heat, chemical polymerization initiators are often used as polymerization initiators.

[0003] Among dental materials, adhesive compositions such as bonding agents and resin cements often use a mixture of non-acidic monomers and acidic monomers to enhance adhesion. Therefore, there has been a demand for chemical polymerization initiators that exhibit high polymerization activity in the presence of acid (acidic monomers). Chemical polymerization initiators that exhibit high polymerization activity in the presence of acid are known to consist of a combination of an oxidizing agent, which is a highly thermally stable organic peroxide such as hydroperoxides, ketone peroxides, peroxyesters, and diacyl peroxides, and a reducing agent, which is a combination of amines, sulfinic acid compounds, thiourea compounds, oxime compounds, and transition metal compounds (these may function as reducing agents individually or in combination, and are sometimes collectively called polymerization accelerators) (see Patent Documents 1 and 2).

[0004] Among these, chemical polymerization initiators combining hydroperoxides and thiourea compounds are particularly suitable for use as dental chemical polymerization initiators due to their high storage stability and high activity in the presence of acid. By selecting a specific compound as the thiourea compound, or by combining it with polymerization accelerators other than thiourea compounds, such as copper compounds, various characteristics can be achieved.

[0005] Incidentally, since a radical polymerization reaction is initiated immediately when an oxidizing agent and a reducing agent come into contact in the presence of a radically polymerizable monomer, when storing adhesive radical polymerization curable compositions (adhesive compositions) containing these chemical polymerization initiators, as well as acidic monomers and non-acidic monomers, it is necessary to prevent the oxidizing agent and reducing agent from coexisting. For this reason, it is common practice to prepare these compositions as combinations of two or more compositions (hereinafter sometimes referred to as "partial compositions"), which are mixtures of each component, such as the divided polymerizable monomer components, and each component, the divided chemical polymerization initiator, and to store these partial compositions separately (in individual packages). Then, immediately before use, two or more partial compositions stored in individual packages are mixed to prepare a curable composition containing all the chemical polymerization initiator components. As a result, the chemical polymerization initiator functions simultaneously with the mixing, causing the curable composition to polymerize and harden.

[0006] In the partially packaged compositions described above, it is important that each partially packaged component has high storage stability, and adhesive compositions that can achieve both high curability and high storage stability are known. For example, Patent Document 3 describes how, when using a highly active "(a) thiourea compound, (b) peroxyester, (c) divalent copper compound, and (d) arylborate compound, and substantially free of hydroperoxide" (hereinafter also simply referred to as "peroxyester-based chemical polymerization initiator") as a chemical polymerization initiator, and preparing the partial compositions by dividing the components constituting the peroxyester-based chemical polymerization initiator into two compositions in which each component is kept in a state where they cannot chemically come into contact with each other, the storage stability of either partial composition can be increased if a first partial composition mainly contains (a) thiourea compound and (d) arylborate compound and substantially free of organic peroxide, and a second partial composition mainly contains (b) peroxyester, (c) divalent copper compound, and an acidic group-containing polymerizable monomer and substantially free of (b) hydroperoxide is packaged separately and made into a kit, and mixed at the time of use. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2017-088637 [Patent Document 2] International Open Brochure WO2017 / 098724 [Patent Document 3] International Open Brochure WO2019 / 131094 [Patent Document 4] Japanese Patent Publication No. 2020-111513 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, while the adhesive composition prepared using the kit disclosed in Patent Document 3 exhibits high adhesive performance when used in the absence of water, it tends to have insufficient adhesive strength when applied to dentin, which contains a large amount of water, as a dental cement (see Patent Document 4). Adhesive compositions that improve adhesive strength in the presence of water are also known, by using a peroxyester-based chemical polymerization initiator combined with an inorganic peroxide as a chemical polymerization initiator that improves these points to some extent (see Patent Document 4). However, regarding the adhesion of this adhesive composition to dentin, the adhesiveness is not always sufficient, and there is room for further improvement, probably because dentin contains a large amount of oxygen, and the oxidizing components produced by it consume the reducing agent.

[0009] Therefore, the present invention aims to provide an adhesive radical polymerization curable composition, comprising an acidic monomer and a non-acidic monomer, that exhibits curability and high storage stability equivalent to or better than that of a peroxyester-based chemical polymerization initiator, and that can exhibit excellent adhesion even when used on systems containing a large amount of water and oxidizing components, particularly dentin. [Means for solving the problem]

[0010] The present invention solves the above problems. The first form of the present invention is: (a) The general formula (1) below is shown a thiourea compound, (b) a peroxyester, (c) a divalent copper compound, (d) The general formula (2) below is shown an aryl borate compound, and (e) an ascorbate, and is a chemical polymerization initiator substantially free of hydroperoxide, wherein the (e) ascorbate is included as a powder composed of at least one selected from the group consisting of trisodium 2-phospho-L-ascorbate, calcium ascorbate, and sodium isoascorbate, and the average particle diameter measured by a laser diffraction / scattering particle size distribution analyzer for the powder is 0.1 to 20 μm. It is a chemical polymerization initiator characterized by this.

Chemical formula

Chemical formula

[0011] In the chemical polymerization initiator of the above form (hereinafter, also referred to as "the chemical polymerization initiator of the present invention"), the ratio (%) of the number of particles having a particle diameter exceeding 20 μm in the total number of particles, obtained from the particle size distribution measured by a laser diffraction / scattering particle size distribution analyzer, is the particle content ratio of more than 20 μm: R 20When this is done, the R of the powder constituting (e) ascorbate 20 It is preferable that the amount be 20% or less, and particularly preferable that it be 10% or less.

[0012] A second embodiment of the present invention is a dental adhesive composition (hereinafter also referred to as "the adhesive composition of the present invention") characterized by comprising (g) an acidic group-containing polymerizable monomer component and (h) an acidic group-free polymerizable monomer, (i) a filler consisting of powder having an average particle size of 0.1 to 20 μm as measured by a laser diffraction scattering particle size distribution analyzer, and a chemical polymerization initiator as described in claim 1, and substantially free of hydroperoxide.

[0013] A third embodiment of the present invention is a kit for preparing a dental adhesive composition of the present invention, comprising a combination of a first partial composition and a second partial composition packaged in a manner that prevents physical contact between them, wherein the first partial composition contains (b) a thiourea compound, (d) an aryl borate compound, and (e) an ascorbate, and substantially does not contain (c) a divalent copper compound, (g) an acidic group-containing polymerizable monomer, and a peroxide; the second partial composition contains (a) a peroxyester, (c) a divalent copper compound, and (g) an acidic group-containing polymerizable monomer, and substantially does not contain (a) a thiourea compound, (d) an aryl borate compound, and (e) an ascorbate; and the (h) an acidic group-free polymerizable monomer and (i) a filler are each included in at least one composition selected from the first partial composition and the second partial composition, respectively, and is a kit for preparing a dental adhesive composition (hereinafter also referred to as "the kit of the present invention"). [Effects of the Invention]

[0014] The chemical polymerization initiator of the present invention exhibits high activity even in the presence of an acid (acidic monomer), similar to conventional peroxyester-based chemical polymerization initiators that do not contain (e) ascorbate. When blended with acidic monomers and non-acidic monomers to form the adhesive composition of the present invention (adhesive radical polymerization curable composition), the adhesive composition of the present invention can be made highly curable and can be packaged and stored stably for a long period of time.

[0015] Furthermore, because the adhesive composition of the present invention uses the chemical polymerization initiator of the present invention, it can achieve high adhesion even when used in systems containing a large amount of water or oxidizing components, especially when used on dentin, compared to conventional adhesive radical polymerization curable compositions containing peroxyester-based chemical polymerization initiators. Moreover, it is possible to reduce the thickness of the film formed in this case. [Modes for carrying out the invention]

[0016] The present inventors have discovered and proposed that a chemical polymerization initiator comprising (a) a thiourea compound, (b) a peroxyester, (c) a divalent copper compound, (d) an aryl borate compound, and (e) an ascorbate, and substantially free of hydroperoxide, exhibits higher adhesion to dentin than a peroxyester-based chemical polymerization initiator containing an inorganic peroxide (disclosed in Patent Document 4), even without the inclusion of an inorganic peroxide (Japanese Patent Application No. 2021-017441).

[0017] However, when the present inventors investigated the properties of dental adhesive compositions containing the above-mentioned chemical polymerization initiator, they confirmed that the film thickness sometimes increased when sodium ascorbate was added as an ascorbate (see Comparative Example 2 below). When bonding a prosthesis to a tooth base using a dental adhesive composition, a thinner film thickness (cured body) formed by the dental adhesive composition is preferable from the viewpoint of fit. Therefore, the cause of the thickening of the film thickness in the above system and a solution were further investigated. As a result, it was found that the film thickness increased because the sodium ascorbate used as a component of the chemical polymerization initiator contained many coarse particles, that when sodium ascorbate was finely ground, the desired activity could not be obtained due to moisture absorption (deliquescent) (see Comparative Example 3 below), that when L(+)-disodium ascorbate sulfate was used, the effect of improving adhesion to dentin could not be obtained (see Comparative Examples 4 and 5 below), and that when a specific ascorbate was used, the film thickness could be reduced without causing the above-mentioned decrease in activity even when finely ground. This invention was developed under these circumstances.

[0018] Furthermore, the reason why (e) the addition of ascorbate improves adhesion in environments with relatively high concentrations of water and oxidizing components while maintaining the characteristics of conventional peroxyester-based chemical polymerization initiators is not entirely clear, and the present invention is not bound by any logic. However, the inventors presume that the reason is as follows.

[0019] In other words, when used in the absence of water or oxidizing components, or in environments where the amount of water or oxidizing components is extremely small, the thiourea compound, similar to conventional peroxyester-based chemical polymerization initiators, comes into contact with the divalent copper compound, coordinating to the divalent copper atoms constituting the divalent copper compound and simultaneously reducing the divalent copper atoms to monovalent. Next, the copper complex obtained by this reduction reaction comes into contact with the peroxyester to form a highly active (radical-generating) active complex, which acts together with the aryl borate compound having a curing-accelerating function to carry out the curing reaction. At this time, the monovalent copper atoms are oxidized again to divalent through a redox reaction accompanied by radical generation, and are reused (catalytically without being deactivated or consumed) in the formation of the active complex. This cyclical process is repeated, and it is believed that high polymerization activity can be obtained.

[0020] On the other hand, in the absence of water or oxidizing components, or in environments where the amount of water or oxidizing components present is extremely small, (e) when ascorbate is not included (when conventional peroxyester-based chemical polymerization initiators are used), the hydrophilicity of each chemical polymerization initiator component is insufficient, and they are easily inhibited by oxidizing components. As a result, the above mechanism is difficult to operate (the catalytic cycle is difficult to complete), and polymerization activity decreases. In contrast, by incorporating ascorbate, which has very high hydrophilicity and is less susceptible to inhibition by oxidizing components, the catalytic cycle is able to operate smoothly, and adhesion is improved.

[0021] The chemical polymerization initiator, adhesive composition, and kit of the present invention are no different from those described in Patent Document 3, except that they contain a specific ascorbate salt. However, the present invention will be described below, including these points.

[0022] In this specification, unless otherwise specified, the notation "x~y" using numerical values ​​x and y means "greater than or equal to x and less than or equal to y". If a unit is attached only to the numerical value y in such notation, that unit shall also apply to the numerical value x. Furthermore, in this specification, the term "(meth)acrylic" means both "acrylic" and "methacrylic". Similarly, the term "(meth)acrylate" means both "acrylate" and "methacrylate", and the term "(meth)acryloyl" means both "acryloyl" and "methacryloyl".

[0023] 1. Chemical polymerization initiator of the present invention The chemical polymerization initiator of the present invention comprises (a) a peroxyester, (b) a thiourea compound, (c) a divalent copper compound, (d) an aryl borate compound, and (e) an ascorbate, and is substantially free of hydroperoxide. The (e) ascorbate is a powder consisting of at least one selected from the group consisting of 2-phospho-L-ascorbate trisodium, calcium ascorbate, and isoascorbate sodium, and is characterized in that the average particle size of the powder measured by a laser diffraction scattering particle size distribution analyzer (specifically, the particle size value corresponding to 50% of the particle size distribution) is 0.1 to 20 μm.

[0024] Here, "substantially free of hydroperoxide" means either (1) that it does not contain hydroperoxide (hydroperoxide content is 0% by mass), or (2) (b) when expressed as the molar ratio of peroxyester (PE) to hydroperoxide (HP): HP / PE, HP / PE is in a range greater than 0 and 2 / 100 or less, preferably greater than 0 and 1 / 300 or less. If the chemical polymerization initiator of the present invention does not satisfy the condition of "substantially free of hydroperoxide," it becomes difficult to achieve high storage stability when the adhesive composition containing (g) an acidic group-containing polymerizable monomer component and (h) an acidic group-free polymerizable monomer, and the chemical polymerization initiator, is packaged into multiple partial compositions and made into a kit.

[0025] The following describes in detail the (a) thiourea compounds, (b) peroxyesters, (c) divalent copper compounds, (d) aryl borate compounds, and (e) ascorbic acid salts used as chemical polymerization initiators in the present invention.

[0026] <(a) Thiourea compounds> blood Urea compounds refer to compounds that have the structure =NC(=S)-N=. In the chemical polymerization initiator of the present invention, Use the thiourea compound shown in the following general formula (1). 。

[0027] [ka]

[0028] Here, in general formula (1), R 1 , R 2 and R 3 Each of these is a hydrogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted acyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted alkenyl group, R 2 R 1 and R3 It may bond to any of the groups selected from to form a ring.

[0029] Among the thiourea compounds represented by general formula (1), R 1 , R 2 and R 3 Preferably, at least two of the groups are hydrogen atoms and the remaining group is a substituent. For example, R 2 and R 3 and are hydrogen atoms, R 1 Thiourea compounds in which the group is an acyl group are most preferred.

[0030] Suitable thiourea compounds include thiourea, methylthiourea, ethylthiourea, n-propylthiourea, isopropylthiourea, cyclohexylthiourea, benzylthiourea, phenylthiourea, acetylthiourea, benzoylthiourea, adamantylthiourea, 1-(2-pyridyl)-2-thiourea, 1-(2-tetrahydrofurfuryl)-2-thiourea, N,N'-dimethylthiourea, N,N'-diethylthiourea, N,N'-di-n-propylthiourea, N, Examples of thiourea compounds include N'-diisopropylthiourea, N,N'-dicyclohexylthiourea, N,N'-diphenylthiourea, trimethylthiourea, triethylthiourea, tri-n-propylthiourea, triisopropylthiourea, tricyclohexylthiourea, tetramethylthiourea, tetraethylthiourea, tetra-n-propylthiourea, tetraisopropylthiourea, tetracyclohexylthiourea, ethylenethiourea, and 4,4'-dimethylethylenethiourea. The most preferred thiourea compounds are acetylthiourea or benzoylthiourea.

[0031] Furthermore, one type of thiourea compound may be used, or two or more types may be used in combination. When two or more thiourea compounds are used, the reference mass is the total mass of those thiourea compounds.

[0032] In the chemical polymerization initiator of the present invention, the amount of (a) thiourea compound is not particularly limited, but it is preferably 4 to 4800 parts by mass per 100 parts by mass of (b) peroxyester. By satisfying this range, high polymerization activity and high storage stability can be achieved. To achieve even higher polymerization activity and higher storage stability, it is more preferable to use 13 to 875 parts by mass, and even more preferable to use 27 to 600 parts by mass, per 100 parts by mass of peroxyester.

[0033] (b) Peroxyester (b) A peroxyester is a compound having a structure represented by RC(=O)-OO-R' (where R and R' are any organic groups) or ROC(=O)-OO-R' (where R and R' are any organic groups). In the chemical polymerization initiator of the present invention, peroxyesters having such structures can be used without particular limitation. Specific examples of peroxyesters that can be suitably used include cumyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxydecanoate, t-hexyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexyl peroxy-2-ethylhexanoate, t-butyl peroxy Examples include t-oxy-2-ethylhexanoate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-di(benzoylperoxy)hexane, t-butylperoxyacetate, t-butylperoxy-3-methylbenzoate, and t-butylperoxybenzoate. Among these, peroxyesters with a 10-hour half-life temperature of 80°C or higher are preferred from the viewpoint of polymerization activity and storage stability, and t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxy-2-ethylhexylmonocarbonate, t-butylperoxyacetate, and t-butylperoxybenzoate are particularly preferred.

[0034] The aforementioned (b) peroxyester may be used by one type only, or by a combination of two or more types. When two or more types of (b) peroxyesters are used, the reference mass is the total mass of those (b) peroxyesters.

[0035] <(c) Divalent copper compounds> The chemical polymerization initiator of the present invention uses a divalent copper compound as the copper compound. In addition, the chemical polymerization initiator of the present invention may also use a monovalent copper compound in combination with the divalent copper compound. However, since monovalent copper compounds act as reducing agents for peroxyesters and tend to reduce storage stability, it is preferable to keep the content of monovalent copper compounds to a trace amount that does not adversely affect the product, or to omit them altogether. Here, "omitted" means that while unavoidable inclusion as an impurity in the divalent copper compound is acceptable, it should not be actively incorporated.

[0036] (c) The divalent copper compound may be in hydrate or anhydrous form. Examples of divalent copper compounds that can be suitably used include copper(II) chloride, copper(II) sulfate pentahydrate, copper(II) nitrate, copper(II) trifluoromethane sulfate, copper(II) acetate monohydrate, copper(II) acetylacetone, copper(II) naphthenate, copper(II) salicylate, copper(II) benzoate, copper(II) methacrylate, copper(II) butyl phthalate, copper(II) gluconate, copper(II) dichloro(1,10-phenanthroline)copper(II), disodium ethylenediaminetetraacetate copper(II) tetrahydrate, copper(II) dimethyldithiocarbamate, copper(II) diethylthiocarbamate, copper(II) hexafluoroacetylacetonate, bis(1,3-propanediamine)copper(II) dichloride, bis(8-quinolinolato)copper(II), and the like. These divalent copper compounds may be used individually or in combination of two or more.

[0037] Among these divalent copper compounds, it is preferable that the ligand that coordinates to the divalent copper atom constituting the divalent copper compound is (i) a halogen atom, (ii) an atomic group containing an oxygen atom, or (iii) an atomic group containing a nitrogen atom, due to its high storage stability and high activity with (b) thiourea compounds. In particular, it is more preferable that the ligand is (ii) an atomic group containing an oxygen atom, and examples of divalent copper compounds having such ligands include copper(II) sulfate, copper(II) acetate monohydrate, and copper(II) acetylacetone. When (ii) the ligand is an atomic group containing an oxygen atom, the atomic group containing the oxygen atom coordinates to the divalent copper atom via the oxygen atom, and when (iii) the ligand is an atomic group containing a nitrogen atom, the atomic group containing the nitrogen atom coordinates to the divalent copper atom via the nitrogen atom.

[0038] In the chemical polymerization initiator of the present invention, the amount of (c) divalent copper compound (total amount if two or more compounds are included) is not particularly limited, but it is preferably 0.002 parts by mass to 250 parts by mass per 100 parts by mass of (b) peroxyester. By satisfying this range, high polymerization activity and high storage stability can be achieved. To achieve even higher polymerization activity and higher storage stability, it is more preferable to use 0.008 parts by mass to 20 parts by mass, and even more preferable to use 0.03 parts by mass to 8 parts by mass, per 100 parts by mass of peroxyester.

[0039] <(d) Arylborate compounds> Arylborate compounds are compounds that have at least one boron-aryl bond in their molecule. the law of nature , In the chemical polymerization initiator of the present invention, Using the compound represented by the following general formula (2) ru .

[0040] [ka]

[0041] In general formula (2), R 10 , R20 and R 30 Each of these is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted alkenyl group, R 40 , and R 50 Each of these is independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group, L + These are metal cations, quaternary ammonium ions, quaternary pyridinium ions, quaternary quinolinium ions, or phosphonium ions.

[0042] Here, (i) as metal cations, (ia) alkali metal cations such as sodium ions, lithium ions, and potassium ions, or (ib) alkaline earth metal cations such as magnesium ions are preferred; (ii) as quaternary ammonium ions, tetrabutylammonium ions, tetramethylammonium ions, and tetraethylammonium ions are preferred; (iii) as quaternary pyridinium ions, methylpyridinium ions, and ethylpyridinium ions are preferred; (iv) as quaternary quinolinium ions, methylquinolinium ions, ethylquinolinium ions, and butylquinolium ions are preferred; and (v) as phosphonium ions, quaternary phosphonium ions such as tetrabutylphosphonium ions and methyltriphenylphosphonium ions are preferred.

[0043] Suitable examples of arylborate compounds represented by general formula (2) include sodium salt, lithium salt, potassium salt, triethanolammonium salt, and tetrabutylammonium salt of tetraphenylborate. Among these, sodium salt of tetraphenylborate is particularly preferred because it has high water solubility and therefore exhibits high curing activity in areas with high water content.

[0044] In the chemical polymerization initiator of the present invention, the amount of (e) aryl borate compound is not particularly limited, but it is preferably 10 to 2000 parts by mass, and particularly 30 to 1000 parts by mass, per 100 parts by mass of (b) peroxyester. By using an amount within this range, high curability and / or adhesion can be obtained when the chemical polymerization initiator of the present invention is used in an adhesive composition or an adhesive composition kit.

[0045] <(e) Ascorbate> The chemical polymerization initiator of the present invention uses a powder made of at least one ascorbate selected from the group consisting of 2-phospho-L-ascorbate trisodium, calcium ascorbate, and isoascorbate sodium (hereinafter also referred to as "specific ascorbate"), and the average particle size (specifically, the particle size value corresponding to 50% of the particle size distribution) obtained from the volume-based particle size distribution determined by laser diffraction scattering is 0.1 to 20 μm (hereinafter also referred to as "specific ascorbate powder"). Here, powder means an aggregate of particles, and in the chemical polymerization initiator of the present invention or in a (adhesive) polymerizable composition using it, the particles are dispersed among other components. Measurement using a laser diffraction scattering particle size distribution analyzer (for example, Beckman Coulter's "LS13-320") can be performed using a sample in which a predetermined amount of specific ascorbate powder is dispersed in a dispersion medium that does not dissolve the specific ascorbate powder. Sample preparation can be performed by using ethanol as the dispersion medium, adding an amount of specific ascorbate powder such that the PIDS (Polarization Intensity Differential Scattering) concentration is 45-55% by mass, and dispersing it by ultrasonic treatment. In this invention, ultrasonic treatment is performed, for example, using an AS ONE "Ultrasonic Cleaner VS-150" to treat a sample at 150W output for 5 minutes. The refractive index of ethanol is set to 1.33 and the refractive index of ascorbate to 1.6, and the particle size corresponding to 50% of the particle size distribution in the volume-based particle size distribution obtained by measurement is defined as the average particle size.

[0046] If ascorbic acid salts other than the three compounds (specific ascorbic acid salts) described above are used, the effects of the present invention cannot be obtained. That is, not only is it difficult to maintain the powder state with the above average particle size, but the activity of the chemical polymerization initiator decreases due to moisture absorption, or even if the powder state with the above average particle size can be maintained, the activity will be low. The inventors have confirmed, for example, that when sodium ascorbate is made into small particles by mechanical grinding, freeze-drying, reprecipitation, etc., it deliquesces and does not show sufficient activity as an initiator (see Comparative Example 3 below), and that when disodium ascorbate sulfate is used, high activity cannot be obtained (see Comparative Examples 4 and 5 below). Furthermore, if the upper limit of the above range is exceeded, the composition will contain a large number of particles that are significantly larger than the particle size of inorganic fillers commonly used in dental adhesive compositions such as dental cement, for example. Therefore, when incorporated as a chemical polymerization catalyst component in a dental adhesive composition, the thickness of the cured film cannot be reduced, and the fit when bonding a prosthesis to a tooth base, etc., will decrease. Furthermore, it is difficult and time-consuming to produce powder that falls below the lower limit of the above range.

[0047] From the viewpoint of the above-mentioned suitability and ease of preparation, the average particle size of the powder is preferably 0.1 to 20 μm, and particularly preferably 0.1 to 10 μm. Furthermore, the percentage (%) of particles with a particle size exceeding 20 μm in the total number of particles, determined from the particle size distribution measured by a laser diffraction scattering particle size analyzer, is defined as the 20 μm particle content: R 20 When this is done, the R of the powder 20 The content of the monomer is preferably 20% or less, and particularly preferably 10% or less. Methods for obtaining such a powder include mechanical grinding using a mortar and pestle or ball mill, freeze-drying, reprecipitation, and grinding by kneading with polymerizable monomers, and it is preferable to sift the powder after grinding. When employing these methods, it is preferable to investigate the relationship between the grinding conditions and the average particle size in advance and to adopt conditions that yield a powder with a predetermined average particle size to reduce the particle size.

[0048] In the chemical polymerization initiator of the present invention, the amount of (e) specific ascorbate powder blended is preferably 7 to 21,000 parts by mass, particularly 17 to 3,300 parts by mass, and most preferably 55 to 1,320 parts by mass, per 100 parts by mass of (b) peroxyester, for the reason that it can exhibit high polymerization activity and high adhesive strength.

[0049] <Inorganic peroxide> As described above, the chemical polymerization initiator of the present invention achieves the effects described above even without the use of inorganic peroxides. For this reason, the chemical polymerization initiator of the present invention may contain or substantially contain inorganic peroxides, and from the viewpoint of reducing the number of constituent components, it is preferable that it does not contain inorganic peroxides. On the other hand, if a synergistic effect is expected, it is preferable to further incorporate inorganic peroxides.

[0050] As inorganic peroxides, known inorganic peroxides such as lithium peroxide, potassium peroxide, magnesium peroxide, calcium peroxide, barium peroxide, zinc peroxide, peroxodisulfate, and peroxodiphosphate can be used without particular limitation. From the viewpoint of polymerization activity, it is preferable to use peroxodisulfates such as sodium peroxodisulfate, potassium peroxodisulfate, and ammonium peroxodisulfate, and it is particularly preferable to use potassium peroxodisulfate and sodium peroxodisulfate.

[0051] When an inorganic peroxide is actively incorporated into the chemical polymerization initiator of the present invention, the amount incorporated is preferably 7 to 21,000 parts by mass, particularly 17 to 3,300 parts by mass, and most preferably 55 to 1,320 parts by mass, per 100 parts by mass of (b) peroxyester, for the reason that it can exhibit high polymerization activity and high adhesive strength.

[0052] <Other polymerization accelerators> The chemical polymerization initiator of the present invention may include polymerization accelerators in addition to the components (a) to (e) and inorganic peroxides described above. These will be described below.

[0053] The chemical polymerization initiator of the present invention may also contain aromatic sulfinic acid compounds and barbituric acid compounds as other polymerization accelerators.

[0054] Examples of aromatic sulfinate compounds that can be suitably used include sodium p-toluenesulfinate, sodium benzenesulfinate, 2,4,6-trimethylbenzenesulfinic acid, 2,6-dimethylbenzenesulfinic acid, 2,6-diisopropylbenzenesulfinic acid, sodium salts of 2,4,6-trimethylbenzenesulfinic acid and 2,4,6-triisopropylbenzenesulfinic acid, triethanolammonium salt, and tetraethylammonium salt. Among these aromatic sulfinates, benzenesulfinates and p-toluenesulfinates are preferred due to their high reactivity and high solubility in polymerizable monomers.

[0055] Examples of barbituric acid compounds that can be suitably used include 5-butylbarbituric acid, 1,3,5-trimethylbarbituric acid, 1-cyclohexyl-5-ethylbarbituric acid, and the sodium and calcium salts of these barbituric acids.

[0056] When these are blended, the amount blended is preferably 10 to 2000 parts by mass, particularly 30 to 1000 parts by mass, per 100 parts by mass of (b) peroxyester.

[0057] 2. Adhesive composition of the present invention The adhesive composition of the present invention is characterized by comprising a radical polymerizable monomer component consisting of (g) an acidic group-containing polymerizable monomer and (h) an acidic group-free polymerizable monomer, and the chemical polymerization initiator of the present invention, and substantially free of hydroperoxide. Here, "substantially free of hydroperoxide" means (1) that hydroperoxide is not contained (hydroperoxide content is 0% by mass), or (2) that the molar ratio of (b) peroxyester (PE) to hydroperoxide (HP) contained in the adhesive composition of the present invention: HP / PE is greater than 0 and about 2 / 100 or less, preferably greater than 0 and about 1 / 300 or less.

[0058] The blending ratio of (g) acidic monomer and (h) non-acidic monomer in the radical polymerizable monomer component of the adhesive composition of the present invention is preferably such that the blending ratio of (g) acidic group-containing polymerizable monomer and (h) acidic group-free polymerizable monomer in the radical polymerizable monomer component is such that the (g) acidic group-containing polymerizable monomer is 0.1 to 50 parts by mass and the remainder is the (h) acidic group-free polymerizable monomer per 100 parts by mass of the radical polymerizable monomer component, and more preferably such that the (g) acidic group-containing polymerizable monomer is 1 to 30 parts by mass and the remainder is the (h) acidic group-free polymerizable monomer. Furthermore, the content of the chemical polymerization initiator of the present invention is preferably such that the (b) peroxyester is 0.005 to 5 parts by mass, and particularly preferably 0.05 to 2.5 parts by mass, per 100 parts by mass of the radical polymerizable monomer component.

[0059] The adhesive composition of the present invention may further optionally contain (i) a filler, a solvent, a polymerization inhibitor, a pigment, an ultraviolet absorber, etc. The adhesive composition of the present invention can be suitably used as a dental material, and among dental materials, it can be particularly suitably used as a dental cement or a dental adhesive. When used as a dental cement, it is preferable that (i) a filler is included, and when used as a dental adhesive, it is preferable that a solvent is included.

[0060] The radical polymerizable monomers used in the adhesive composition of the present invention, specifically (g) acid group-containing polymerizable monomers (acid monomers), (h) acid group-free polymerizable monomers (non-acid monomers), and (i) fillers, will be described below.

[0061] <(g) Acidic group-containing polymerizable monomer (acidic monomer)> As the acidic monomer, known polymerizable monomers having at least one acidic group and at least one radical polymerizable unsaturated group can be used. Here, the acidic group is one in which an aqueous solution or aqueous suspension of the radical polymerizable monomer having this group exhibits acidity. Typical examples include those having a hydroxyl group such as a carboxyl group (-COOH), a sulfo group (-SO3H), a phosphinico group {=P(=O)OH}, or a phosphono group {-P(=O)(OH)2}. In addition to such hydroxyl group-containing acidic groups, other examples include acid anhydride groups with a structure formed by the dehydration condensation of two hydroxyl group-containing acidic groups, and acid halide groups in which the hydroxyl group of a hydroxyl group-containing acidic group is substituted with a halogen. Furthermore, the radical polymerizable unsaturated group is not particularly limited and may be any known group. Examples include (meth)acryloyl groups such as (meth)acryloyl groups, (meth)acryloyloxy groups, (meth)acryloylamino groups, and (meth)acryloylthio groups, as well as vinyl groups, allyl groups, and styryl groups.

[0062] From the viewpoint of polymerizability, (meth)acrylic acid ester-based polymerizable monomers containing acidic groups are preferably used as acidic monomers. These (meth)acrylic acid ester-based polymerizable monomers containing acidic groups are particularly suitable for use in dental materials from the viewpoint of biosafety. One type of acidic monomer may be used, or two or more types may be used in combination.

[0063] Suitable acidic monomers include 2-(meth)acryloyloxyethyl dihydrogen phosphate, bis[2-(meth)acryloyloxyethyl]hydrogen phosphate, 2-(meth)acryloyloxyethyl phenylhydrogen phosphate, 6-(meth)acryloyloxyhexyl dihydrogen phosphate, 6-(meth)acryloyloxyhexyl phenylhydrogen phosphate, 10-(meth)acryloyloxydecyl dihydrogen phosphate, 1,3-di(meth)acryloylpropane-2-dihydrogen phosphate, 1,3-di(meth)acryloylpropane-2-phenylhydrogen phosphate, and bis[5-{2-(meth)acryloyloxyethoxycarbonyl}heptyl]hydrogen phosphate.

[0064] <(h) Polymerizable monomers that do not contain acidic groups (non-acidic monomers)> The non-acidic monomer is not particularly limited as long as it has at least one radically polymerizable unsaturated group in its molecule and does not have an acidic group. From the viewpoint of polymerizability and safety for living organisms, (meth)acrylic acid ester-based polymerizable monomers that do not contain acidic groups are preferably used. One type of non-acidic monomer may be used, or two or more types may be used in combination. Examples of preferably usable non-acidic monomers include methyl (meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 2,2-bis[4-(3-methacryloyloxy)-2-hydroxypropoxyphenyl]propane, 2,2-bis(methacryloyloxypolyethoxyphenyl)propane, 2-hydroxyethyl methacrylate, 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate, 1,10-decanediol di(meth)acrylate, and the like.

[0065] Furthermore, when the adhesive composition of the present invention is used as a dental material, for example, superior mechanical strength may be required for the cured product of the adhesive composition. In this case, it is preferable to use a di-, tri-, or tetra-functional radical polymerizable monomer having multiple radical polymerizable groups as the non-acidic monomer.

[0066] Next, we will describe compounding agents that can be suitably incorporated into the adhesive composition of the present invention.

[0067] <(i) Filler> As fillers that can be used in the adhesive composition of the present invention, conventional powdered inorganic fillers, organic fillers, and organic-inorganic composite fillers used in dental materials can be used. From the viewpoint of the mechanical strength of the cured product, it is preferable to use inorganic fillers or organic-inorganic composite fillers.

[0068] Examples of suitable inorganic fillers include various silicas; complex oxides containing silicon as a constituent element, such as silica-titania and silica-zirconia; clay minerals or silicates containing silicon as a constituent element, such as talc, montmorillonite, zeolite, and calcium silicate (hereinafter referred to as silica-based fillers); ytterbium fluoride, yttrium fluoride, silicate glass, fluoroaluminosilicate glass, lanthanum glass, barium glass, strontium glass, etc. These inorganic fillers may also be surface-treated with surface treatment agents such as silane coupling agents to improve compatibility with polymerizable monomers and enhance the mechanical strength and water resistance of the resulting hardened product. The silica-based fillers have excellent chemical stability and are easy to surface-treat with silane coupling agents, etc. Furthermore, suitable organic fillers include polymethyl methacrylate, polyethyl methacrylate, methyl methacrylate-ethyl methacrylate copolymer, crosslinked polymethyl methacrylate, crosslinked polyethyl methacrylate, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, acrylonitrile-styrene copolymer, and acrylonitrile-styrene-butadiene copolymer. In addition, suitable organic-inorganic composite fillers include those obtained by compounding an inorganic filler with a polymerizable monomer that can be used as (e) an acidic monomer or (f) a non-acidic monomer. The compounding method is not particularly limited, and the composite may be solid or have pores. From the viewpoint of the mechanical strength of the cured product, it is preferable to use an organic-inorganic composite filler in which the surface of inorganic aggregated particles is coated with an organic polymer and has pores, as described in the International Publication No. 2013 / 039169 pamphlet. These fillers may be used individually or in combination of two or more types.

[0069] Since the average particle size of these fillers is usually 20 μm or less, it does not adversely affect the thickness of the cured coating. However, when using fillers containing coarse particles, (e) the average particle size and R are similar to those of specific ascorbate powders. 20 It needs to be used as a powder containing [specific properties].

[0070] (i) The total amount of filler should be determined appropriately according to the intended use. In particular, when used in dental materials, especially dental cement, it is preferable to blend 65 parts by mass or more and 1000 parts by mass or less per 100 parts by mass of polymerizable monomer components contained in dental cement. From the viewpoint of mixability and mechanical strength of the hardened product, it is more preferable to blend 150 parts by mass or more and 400 parts by mass or less per 100 parts by mass of polymerizable monomer components contained in dental cement. When the adhesive composition of the present invention is used as dental cement, the composition of the radical polymerizable monomer components is such that, based on the total mass of the radical polymerizable monomer components, 0.1% by mass or more and 50% by mass or less is (g) acidic monomer and the remainder is (h) non-acidic monomer, and preferably 1% by mass or more and 30% by mass or less is (g) acidic monomer and the remainder is (h) non-acidic monomer. Dental cements employing such polymerizable monomer component compositions can achieve stronger adhesion to tooth structure and further improve the adhesive durability to tooth structure and prosthetics made of various materials.

[0071] 3. The present invention kit The kit of the present invention having the above features consists of a combination of a first partial composition and a second partial composition packaged in a manner that prevents them from physically coming into contact with each other, and the adhesive composition of the present invention is prepared by mixing the two partial compositions at the time of use. The first partial composition contains (a) a thiourea compound, (d) an aryl borate compound, and (e) a specific ascorbate powder, but substantially does not contain (c) a divalent copper compound, (g) an acidic group-containing polymerizable monomer, and peroxides; the second partial composition contains (b) a peroxyester, (c) a divalent copper compound, and (g) an acidic group-containing polymerizable monomer, but substantially does not contain (a) a thiourea compound, (d) an aryl borate compound, and (e) a specific ascorbate powder; and (h) an acidic group-free polymerizable monomer and (i) a filler are each contained in at least one composition selected from the first partial composition and the second partial composition.

[0072] The kit of the present invention, having the above-described features, exhibits high storage stability for the individually packaged first and second partial compositions, allowing for stable storage (preservation) for extended periods in their packaged state. This makes it useful not only as a storage solution but also as a product that can be distributed to the market.

[0073] Furthermore, "packaged in a state where physical contact is impossible" means a state in which one composition and another are separated and packaged by an inhibitory member (packaging member) that inhibits molecular diffusion between them. Generally, solid materials such as resins, glass, metals, and ceramics, which are suitably used as materials for containers and bags, are used as inhibitory members (packaging members). A typical example of a "state where physical contact is impossible" is a state in which one type of composition is stored in a sealed state in a container that blocks outside air and external light. Specific packaging forms include forms in which the compositions are filled into containers such as bottles, tubes, and syringes. For example, the adhesive composition of the present invention can be prepared by i) applying appropriate amounts of the first agent and the second agent onto mixing paper and mixing them with a spatula; ii) when the first agent and the second agent are in paste form, simultaneously extruding the first agent and the second agent from a syringe with a mixing tip attached to the end; or iii) when the first agent and the second agent are in liquid form, collecting the first agent and the second agent in the same mixing dish.

[0074] Furthermore, in the first and second partial compositions, "substantially absent" means (1) when the target compound or component is not present (content is 0% by mass), or (2) when it is present in trace amounts to the extent that no significant difference in storage stability is observed compared to when the target compound or component is not present. Here, in the case shown in (2) above, the content in each partial composition is usually 1% by mass or less, preferably 0.02% by mass or less, and particularly preferably 0.01% by mass or less.

[0075] For example, when the kit of the present invention is used as a dental cement kit, it is preferable to adopt an embodiment in which the first partial composition consists only of (a) a thiourea compound, (d) an aryl borate compound, (e) a specific ascorbate powder, (h) a polymerizable monomer that does not contain an acid group, and (i) a filler, and the second partial composition consists only of (b) a peroxyester, (c) a divalent copper compound, (g) a polymerizable monomer that contains an acid group, (h) a polymerizable monomer that does not contain an acid group, and (i) a filler.

[0076] The compositions of the first partial composition (Part 1) and the second partial composition (Part 2) are basically determined such that when they are mixed in equal amounts {when the mixing ratio of Part 1 to Part 2 (amount of Part 1 / amount of Part 2): 1 / 1, or when the mixing ratio of Part 1 to Part 2 (100 × amount of Part 1 / amount of Part 2): 100%}, the composition of the adhesive composition of the present invention is obtained. Then, Part 1 and Part 2 can be easily prepared by weighing and mixing each component according to the composition determined in this way. Note that the above "equal amounts" usually means equal amounts by mass, but when the composition is liquid, it may be equal amounts by volume.

[0077] However, in actual use, that is, when mixing the first partial composition (first agent) and the second partial composition (second agent) to prepare the adhesive composition of the present invention, it may not be possible to strictly maintain the mixing ratio at 1 / 1. In this case, it is preferable to ensure that the adhesive composition of the present invention having the desired composition is obtained when mixed at a mixing ratio other than 1 / 1 (hereinafter also referred to as the "specified mixing ratio"). The specified mixing ratio (this value expressed as a percentage is also referred to as the "specified mixing ratio") can be appropriately determined within a range that does not significantly impair polymerization activity and operability. However, from practical viewpoints such as ease of handling and ease of product packaging, the specified mixing ratio (rate) is preferably within the range of 1 / 5 to 5 / 1 (mixing ratio: 20% to 500%) on a mass basis (or volume basis) for the mixing ratio (first agent / second agent), and more preferably within the range of 1 / 3 to 3 / 1 (mixing ratio: 33% to 300%).

[0078] The specified mixing ratio (rate) can be displayed on a medium for displaying mixing ratio (rate) information. Examples of such mediums for displaying mixing ratio (rate) information include: i) product packaging consisting of a cardboard box, etc.; ii) product instruction manuals provided in paper and / or electronic format; iii) containers (bottles, syringes, packaging bags, etc.) for storing the first and second components in a sealed state; iv) product catalogs provided in paper and / or electronic format; and v) communications sent to product users separately from the product via email or postal mail. The specified mixing ratio may also be provided to product users in a manner that allows them to recognize it, other than those shown in i) to v) above.

[0079] When using the kit of the present invention, the mixed composition (adhesive composition of the present invention) obtained by mixing the first partial composition (first agent) and the second partial composition (second agent) contains all types of chemical polymerization initiator components and polymerizable monomer components, and therefore polymerizes and cures quickly or within a predetermined operating time. A cured body can then be obtained. Known methods can be used to polymerize and cure the mixed composition. For example, the mixed composition can be applied to the area to be cured and left to stand. In this case, the mixed composition can be sufficiently cured by maintaining the applied mixed composition in a temperature range of 10 to 37°C. [Examples]

[0080] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[0081] 1. Abbreviations of the substances used First, the abbreviations for the chemical polymerization initiators and the substances used in the compositions containing them in each example and comparative example are described below.

[0082] <(a) Thiourea compounds> AcTU; Acetylthiourea BzTU; Benzoylthiourea PyTU; pyridylthiourea.

[0083] (b) Peroxyester BPT; t-butylperoxy-3,5,5-trimethylhexanoate BPB; t-butylperoxybenzoate BPE; t-Butylperoxy-2-ethylhexyl monocarbonate BPL; t-butyl peroxylaurate.

[0084] <(c) Divalent copper compounds> CuA; copper(II) acetate monohydrate CuAA; Acetylacetone copper(II).

[0085] <(d) Arylborate compounds> PhBNa; Sodium salt of tetraphenylboron PhBTEOA; ammonium triethanolate of tetraphenylboron.

[0086] <(e) Specific ascorbic acid salts> AANA phosphate; trisodium 2-phospho-L-ascorbic acid salt AACa;L(+)-Calcium Ascorbate IsoAANa; L-Isoascorbate sodium.

[0087] <Other ascorbic acid salts> AANa;L(+)-Sodium Ascorbate AANO sulfate; L(+)-disodium ascorbic acid sulfate.

[0088] <(f) Polymerizable monomers containing acidic groups (acidic monomers)> MDP; 10-methacrylate oxydecyl dihydrogen phosphate.

[0089] <(g) Polymerizable monomers that do not contain acidic groups (non-acidic monomers)> BisGMA; 2,2-Bis[4-(3-methacryloyloxy)-2-hydroxypropoxyphenyl]propane D-2.6E; 2,2-Bis(methacryloyloxypolyethoxyphenyl)propane 3G; Triethylene glycol dimethacrylate HEMA; 2-hydroxyethyl methacrylate.

[0090] <(h) Filler> F1; Silica-zirconia filler with an average particle size of 3.4 μm. F2; Silica-zirconia filler with an average particle size of 0.2 μm. The average particle diameter of the filler material mentioned above refers to the average particle diameter of aggregated particles measured using a laser diffraction scattering particle size distribution analyzer.

[0091] 2. Ascorbate particle size reduction and evaluation of particle size and deliquescence Ascorbate particle size reduction was performed by taking a predetermined amount from unground ascorbate, grinding it in a mortar for 5 minutes, and collecting the ground ascorbate that passed through a stainless steel sieve with a mesh size of 20 μm. Next, 0.1 g of the obtained ground ascorbate was taken, 10 mL of ethanol was added to it, and it was shaken to form a suspension. This suspension was ultrasonically treated for 5 minutes at 150 W output using an AS ONE "Ultrasonic Cleaner VS-150," and then the particle size distribution was analyzed using a Beckman Coulter LS13-320 particle size analyzer, applying the optical model "Fraunhofer" (refractive index: dispersion medium; 1.333, sample; 1.6) to obtain the average particle size (the particle size value corresponding to 50% of the particle size distribution) and R 20 (The percentage of particles with a particle size exceeding 20 μm out of the total number of particles was determined.) Separately, a sample prepared in the same manner using 0.1 g of unground ascorbate was used to determine the average particle size and R in the same manner. 20 The following was determined. In addition, the deliquescence before and after the grinding process was evaluated by leaving the samples undisturbed for one day in an atmospheric environment with 80% humidity and 25°C. Samples that partially liquefied were marked with ×, and those that did not liquefy were marked with ○. These results are shown in Table 1.

[0092] [Table 1]

[0093] 3. Examples 1-14 and Comparative Examples 1-6 (1) Preparation of the first and second drugs The first and second components were prepared by the following methods. Specifically, the first component was prepared by mixing 50 parts by mass of polymerizable monomer components for the first component consisting of (g)BisGMA:30 parts by mass and (g)3G:20 parts by mass, 116.5 parts by mass of filler consisting of F1:46.5 parts by mass and F2:70 parts by mass, and each additive shown in Table 2 in the amounts (parts by mass) shown in Table 2. The second component was prepared by mixing 50 parts by mass of polymerizable monomer components for the second component consisting of (f)MDP:12.5 parts by mass, (g)HEMA:5 parts by mass, (g)D-2.6E:20 parts by mass and (g)3G:12.5 parts by mass, 116.5 parts by mass of filler consisting of F1:46.5 parts by mass and F2:70 parts by mass, and each additive shown in Table 2 in the amounts (parts by mass) shown in Table 2.

[0094] Note that the parts by mass (number in parentheses) for each component shown in Table 2 represent parts by mass relative to 50 parts by mass of the polymerizable monomer component for the first agent for the first agent additive, and parts by mass relative to 50 parts by mass of the polymerizable monomer component for the second agent additive for the second agent additive. In other words, the components other than the additives for the first agent and the second agent additive are common to each example and comparative example. The common components of the first agent in each example and comparative example consist of a base composition for the first agent having the composition shown below, and the common components of the second agent consist of a base composition for the second agent having the composition shown below. Also, "↑" in Table 2 means the same as above.

[0095] <First component base composition> ·(g)BisGMA: 30 parts by mass ·(g)3G: 20 parts by mass ·(h)F1:46.5 parts by mass ·(h)F2:70 parts by mass <Second Agent Base Composition> ·(f)MDP: 12.5 parts by mass ·(g)HEMA: 5 parts by mass ·(g)D-2.6E: 20 parts by mass ·(g)3G: 12.5 parts by mass ·(h)F1:46.5 parts by mass ·(h)F2: 70 parts by mass.

[0096] [Table 2]

[0097] (2) Evaluation of particle size of fillers in the first and second components To evaluate the particle size of the filler in the first and second components, the first and second component base compositions are prepared in the same manner as described above, except that the additives for the first and second components are not added separately, and the average particle size and R of the filler dispersed in the obtained compositions are evaluated. 20 Upon evaluation, the average particle size was found to be 3.0 μm, and R 20 The result was 0%. The evaluation was performed in the same manner as described in 2, using samples prepared in the same manner as described in 2, with 0.1 ml of each composition and 10 mL of ethanol.

[0098] (3) Preparation of dental adhesive compositions and evaluation of the obtained dental adhesive compositions Using the kit consisting of the first and second components prepared in (1), the first and second components constituting the kit were mixed in a volume ratio of 1:1 using mixing tip cement (manufactured by Tokuyama Dental Co., Ltd.) to prepare dental adhesive compositions for each example and comparative example. The adhesive strength and film thickness of the obtained dental adhesive compositions to dentin were then measured as follows. The evaluation results are shown in Table 3.

[0099] <Method for evaluating adhesive strength to dentin> Extracted bovine mandibular anterior teeth were polished with P600 waterproof abrasive paper under water irrigation to create a dentin plane parallel to the labial surface. After drying this dentin plane by blowing compressed air onto it, double-sided tape with 3 mm diameter holes was fixed to each tooth to define the bonding area. Next, each prepared adhesive composition was applied to an 8 mm diameter cylindrical metal attachment, and the coated surface of the adhesive composition was pressed against the dentin surface so that the holes in the double-sided tape and the surface of the metal attachment were concentric. After immersing this test sample in 37°C water for 24 hours, a universal testing machine (AG-I type, Shimadzu Corporation) was used to start loading at a crosshead speed of 2 mm / mm. Loading was applied to the test sample until it fractured, and the adhesive strength was determined from the maximum load using the following formula (2). • Formula (2) Adhesion strength (MPa) = Maximum load (N) / Adhesion area (mm) 2 ).

[0100] <Method for measuring coating thickness> First, two glass plates, each with a diameter of 16 mm and a thickness of approximately 6.0 mm, were prepared. The thickness of these two plates when stacked was measured using a micrometer to determine the blank value: d1. Next, 0.1 g of paste (the adhesive composition sample), mixed for 30 seconds, was placed in the center of one glass plate. Immediately afterward, the paste was sandwiched between the other glass plate, and a load of 15 kg was applied. The plate was left to stand for 10 minutes to allow the paste to harden. After releasing the load, the thickness d2 of the hardened adhesive composition film sandwiched between the two plates was measured, and the thickness of the hardened film was determined from d2-d1. The thicknesses d1 and d2 were calculated as the average of five points (center and four points on the outer circumference), and the film thickness was calculated as the average of five tests. A film thickness of 20 μm or less was considered a good film thickness.

[0101] [Table 3]

[0102] As shown in Table 3, the adhesive compositions of Examples 1 to 14 were confirmed to exhibit high adhesive strength to dentin and provide good film thickness.

[0103] On the other hand, when sodium ascorbate is used as the ascorbate, using unground ascorbate (Comparative Example 2) results in high adhesion to dentin but also a thicker coating. Using ascorbate that has been reduced in particle size (Comparative Example 3) results in a thinner coating but a reduced adhesion to dentin due to deliquescence. Furthermore, when L(+)-disodium ascorbate sulfate is used (see Comparative Examples 4 and 5 below), no improvement in adhesion to dentin is obtained, regardless of the average particle size, similar to the case without sodium ascorbate (Comparative Example 1). Moreover, even when using unground L-isoascorbate sodium, a specific ascorbate, when the average particle size exceeds 20 μm (Comparative Example 6), the adhesion to dentin is high but the coating is thick. Furthermore, in order to evaluate storage stability, the adhesive composition prepared using the first and second components, which constitute the adhesive composition immediately after preparation, were placed in separate containers and stored at 50°C for two weeks. The same evaluation was performed on the prepared adhesive composition, and it was confirmed that results were almost the same as those obtained immediately after preparation.

[0104] Comparative Example 7 In Comparative Example 1, the adhesive strength to dentin was evaluated in the same manner as in Comparative Example 1, except that 3.3 parts by mass of sodium peroxodisulfate was added as an inorganic peroxide to the second agent. The result was 5.2 MPa. Although this value is considerably higher than that of Comparative Example 1, it is inferior to the value obtained in the example.

Claims

1. (a) General formula (1) 【Chemistry 1】 (In the formula, R1, R2, and R3 are, respectively, a hydrogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted acyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted alkenyl group, and R2 may be bonded to any group selected from R1 and R3 to form a ring.) Thiourea compounds shown in (b) Peroxyester, (c) Divalent copper compounds, (d) General formula (2) below 【Chemistry 2】 (In the formula, R10, R20, and R30 are each a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted alkenyl group; R40 and R50 are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group; and L+ is a metal cation, a quaternary ammonium ion, a quaternary pyridinium ion, a quaternary quinolinium ion, or a phosphonium ion.) The arylborate compounds shown, and (e) A chemical polymerization initiator containing ascorbate and substantially free of hydroperoxide, The (e) ascorbate is included as a powder consisting of at least one selected from the group consisting of trisodium 2-phospho-L-ascorbate, calcium ascorbate, and sodium isoascorbate. The average particle size of the aforementioned powder, as measured by a laser diffraction scattering particle size distribution analyzer, is 0.1 to 20 μm. A chemical polymerization initiator characterized by the following features.

2. The percentage (%) of particles with a diameter exceeding 20 μm out of the total number of particles, determined from the particle size distribution measured by a laser diffraction scattering particle size analyzer, is called the 20 μm particle content: R ２０ When that happens, (e) R of the powder constituting the ascorbate ２０ The chemical polymerization initiator according to claim 1, wherein the amount is 20% or less.

3. A dental adhesive composition comprising (g) a polymerizable monomer containing an acidic group and (h) a polymerizable monomer not containing an acidic group, a filler comprising (i) a powder having an average particle size of 0.1 to 20 μm as measured by a laser diffraction scattering particle size distribution analyzer, and the chemical polymerization initiator described in claim 1, characterized in that it substantially does not contain hydroperoxide.

4. A kit for preparing the dental adhesive composition described in claim 3, It consists of a combination of a first subcomposition and a second subcomposition, which are packaged in a manner that prevents them from physically coming into contact with each other. The first partial composition comprises (a) a thiourea compound, (d) an aryl borate compound, and (e) an ascorbate, and substantially does not contain (c) a divalent copper compound, (g) an acidic group-containing polymerizable monomer, and a peroxide. The second partial composition comprises (b) peroxyester, (c) divalent copper compound, and (g) acidic group-containing polymerizable monomer, and substantially does not contain (a) thiourea compound, (d) aryl borate compound, and (e) ascorbate. The (h) acid group-free polymerizable monomer and the (i) filler are each included in at least one composition selected from the first partial composition and the second partial composition. A kit for preparing dental adhesive compositions, characterized by the following features.

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