Microcapsules with porous or hollow cores and pH-sensitive shells and uses thereof

Abstract

The present invention relates to microcapsules comprising a hollow or porous core composed of a polymeric material and containing components of a redox initiator system, and a shell composed of a pH-sensitive material, which can be used to formulate dental materials.

Description

[Technical Field]

[0001] The present invention relates to pH-sensitive microcapsules, paste / paste systems containing such microcapsules, and their use for preparing hardenable compositions comprising redox initiator systems. [Background technology]

[0002] The use of microcapsules to store components of redox initiator systems is generally known.

[0003] U.S. Patent No. 5,154,762 (Mitra et al.) describes in Example 11 the microencapsulation of ascorbic acid in cellulose acetate butyrate. While the use of a water-insoluble encapsulant may initially seem inappropriate for water-based cements, it has been found that vigorous mechanical mixing is generally sufficient to rupture the capsule walls, allowing for adequate release of the encapsulated reducing or oxidizing agent and subsequent hardening of the cement. This technique is particularly useful for preparing powder compositions.

[0004] However, compared to paste / paste-based powder compositions, they are easier to prepare and stabilize due to the physical separation of the mixed powder components.

[0005] In contrast, paste-like compositions are typically produced by a kneading process in which high shear forces are applied onto the microcapsules.

[0006] Microcapsules described in the prior art, particularly those proposed for storing components of redox initiator systems, are typically not stable enough to survive such high shear forces.

[0007] On the other hand, when mixing paste / paste compositions, the mixing forces applied are often not strong enough to rupture the microcapsules to allow release of the active agent.

[0008] Therefore, techniques used to produce powder compositions generally cannot be used for paste / paste compositions. Other references describing the use and production of microcapsules are:

[0009] U.S. Patent No. 9,422,411 (B2) (Sahouani et al.) relates to porous polymer particles that can be hydrophilic or hydrophobic. The porous polymer particles can be used for storing and delivering various active agents or for moisture management. Also provided are a reaction mixture for forming the porous polymer particles, a method for making the porous polymer particles, and an article containing the porous polymer particles.

[0010] U.S. Patent Application Publication No. 2016 / 088836(A1) (Sahouani et al.) describes polymer composite particles that can be used to store and deliver various biologically active agents. The polymer composite particles contain a porous polymer core and a coating layer surrounding the porous polymer core. The porous polymer composite particles typically further contain a biologically active agent that is disposed within the porous polymer core but is not covalently bound to the porous polymer core. The biologically active agent can be released from the polymer composite particles by diffusing from the porous polymer core through the coating layer.

[0011] WO 2016 / 053830 A1 (3M IPC) describes an article comprising a fibrous substrate and porous polymer particles. At least 50% of the porous polymer particles are bonded to the fibrous substrate. A method for manufacturing the article is provided, comprising providing porous polymer particles, providing a fibrous substrate, and bonding the porous polymer particles to the fibrous substrate. The article can be used for fluid management.

[0012] U.S. Patent No. 6,391,288 (B1) (Miyazawa et al.) describes the preparation of microcapsules containing an inner oil phase, an aqueous phase, and an outer oil phase. Ascorbic acid (in the aqueous phase) is encapsulated. The microcapsules have a density of 10 to 500 g / cm. 2, or 500 to 2,000 g / cm 2 , or 2,000 to 5,000 g / cm 2 The o / w emulsion is used to produce microcapsules. The release of the active ingredient, such as ascorbic acid, can be triggered by the appropriate burst strength. Summary of the Invention

[0013] Therefore, there is a need for storage-stable, redox-curable microcapsules that can be used to prepare paste-like compositions.

[0014] Furthermore, it should be possible to ensure proper release of the ingredients stored within the microcapsules on demand.

[0015] This objective is addressed by the microcapsules and related processes claimed and described herein.

[0016] In one embodiment, the invention features microcapsules as claimed and described herein.

[0017] In another embodiment, the present invention relates to a kit of parts comprising a catalyst paste and a base paste comprising the pH-sensitive microcapsules as claimed and described herein.

[0018] Further embodiments of the present invention relate to processes for producing such pH-sensitive microcapsules as claimed and described herein.

[0019] The present invention also relates to a process for curing a curable composition containing the microcapsules claimed and described herein.

[0020] The invention further features the use of microcapsules to prepare curable compositions containing the redox initiator systems claimed and described herein.

[0021] Microcapsules consist essentially of a mechanically stable hollow or porous core filled with an active agent and covered with a pH-sensitive shell that swells or dissolves in acidic or basic environments.

[0022] The microcapsules are sufficiently stable to survive the mixing processes, including the kneading processes typically applied in the preparation of paste-like compositions. [Brief explanation of the drawings]

[0023] [Figure 1] 1A-1C show SEM images of microcapsules described herein that contain a dye and are coated with an acid-sensitive material. [Figure 2] 2A-2C show SEM images of microcapsules described herein that contain a reducing agent and are coated with an acid-sensitive material.

[0024] Unless otherwise defined, as used herein, the following terms have the meanings set forth below.

[0025] "Hollow core" refers to a polymer particle having a polymeric outer shell surrounding a non-polymeric inner region or cavity.

[0026] "Porous core" refers to a polymer particle having a polymer structure that contains voids or pores.

[0027] As used herein, "(meth)acryl" is a contraction for "acryl" and / or "methacryl." For example, a "(meth)acryloxy" group is a contraction for either an acryloxy group (i.e., CH=CH-C(O)-O-) and / or a methacryloxy group (i.e., CH=C(CH)-C(O)-O-).

[0028] An "initiator" is a substance capable of initiating a chemical reaction, preferably by a free radical reaction. The initiator may be a single compound or may contain two or more components, such as a combination of a sensitizer and a reducing agent. Depending on the reaction conditions selected (e.g., pH values ​​> 7 or pH values ​​< 7), different initiators may be preferred.

[0029] A "redox initiator system" is defined as the combination of a reducing agent and an oxidizing agent located on the application portion of an application device. If present, a transition metal component is also considered a component of the redox initiator system.

[0030] As used herein, "hardening" or "curing" of a composition are used interchangeably and refer to polymerization and / or crosslinking reactions, including, for example, photopolymerization reactions and chemical polymerization techniques (e.g., ionic or chemical reactions that form radicals effective to polymerize ethylenically unsaturated compounds), involving one or more materials included in the composition.

[0031] A "dental composition" or "composition for use in dentistry" or "composition to be used in the dental field" is any composition that can be used in the dental field. In this regard, the composition should not be harmful to the patient's health and, therefore, should be free of harmful and toxic components that may leak from the composition. Examples of dental compositions include permanent and temporary crown and bridge materials, artificial crowns, anterior or posterior fillings, adhesives, mill blanks, lab materials, luting materials, and orthodontic appliances. Dental compositions are typically hardenable compositions that can be hardened at ambient conditions, including temperatures ranging from 15 to 50°C, or 20 to 40°C, within a 30-minute, 20-minute, or 10-minute time frame. Higher temperatures are not recommended because they may cause pain to the patient and may be harmful to the patient's health. Dental compositions are typically provided to the practitioner in similarly small volumes, i.e., in the range of 0.1 to 100 mL, 0.5 to 50 mL, or 1 to 30 mL. Thus, the storage capacity of a useful packaging device is within these ranges.

[0032] The term "compound" or "component" refers to a chemical substance having a particular molecular identity or made from a mixture of such substances, for example, polymeric substances.

[0033] A "polymerizable component" is any component that can be cured or solidified, for example, by heating to cause polymerization or chemical crosslinking, or for example, by radiation-induced polymerization or crosslinking, or for example, using a redox initiator, or by any other radical-forming process. A radically polymerizable component may contain only one, two, three, or more radically polymerizable groups. Typical examples of radically polymerizable groups include unsaturated carbon groups, such as vinyl groups present in (methyl)acrylate groups.

[0034] A "monomer" is any chemical substance that can be characterized by a chemical formula having a radically polymerizable unsaturated group (including a (meth)acrylate group) that can be polymerized to form an oligomer or polymer to increase molecular weight. Typically, the molecular weight of a monomer can be simply calculated based on the given chemical formula.

[0035] "Polymer" or "polymeric material" are used interchangeably to refer to homopolymers, copolymers, terpolymers, and the like.

[0036] A "derivative" or "structurally analogous compound" is a chemical compound that exhibits a chemical structure closely related to a corresponding reference compound and contains all structural elements characterized by the corresponding reference compound, but has minor modifications compared to the corresponding reference compound, such as further possessing additional chemical groups, e.g., alkyl moieties, Br, Cl, or F, or lacking chemical groups, e.g., alkyl moieties. That is, a derivative is a structurally analogous compound of the reference compound. A derivative of a chemical compound is a compound that contains the chemical structure of said chemical compound.

[0037] An ingredient containing an "ascorbic acid moiety" is an ingredient that contains the following structural element: [ka] In the formula, the symbol " * " denotes a connection to another chemical moiety or atom.

[0038] "Ambient conditions" refers to the conditions to which the compositions of the present invention are normally exposed during storage and handling. Ambient conditions may be, for example, a pressure of 900-1100 mbar, a temperature of -10-60°C, and a relative humidity of 10-100%. In laboratories, ambient conditions are adjusted to 23°C and 1013 mbar. In the dental and orthodontic fields, ambient conditions are reasonably understood to be a pressure of 950-1050 mbar, a temperature of 15-40°C, and a relative humidity of 20-80%.

[0039] As used herein, "a," "an," "the," "at least one," and "one or more" are used interchangeably. The terms "comprise" or "contain" and variations thereof do not have a limiting meaning where these terms appear in the specification and claims. The term "comprising" also includes the more limiting terms "consisting essentially of" and "consisting of."

[0040] Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0041] The terms "comprise" or "contain" and variations thereof do not have a limiting meaning where these terms appear in the specification and claims. The term "comprise" is intended to encompass the terms "consist essentially of" and "consist of."

[0042] Adding "(s)" to a term means that the term is inclusive of the singular and the plural. For example, the term "additive(s)" means one additive and multiple (e.g., two, three, four, etc.) additives.

[0043] Unless otherwise indicated, all numbers expressing quantities of ingredients, measurements of physical properties, for example, as described below and used in the specification and claims, are to be understood as such numbers and as modified by the term "about."

[0044] "And / or" means either one or both. For example, the phrase component A and / or component B refers to component A only, component B only, or both component A and component B. DETAILED DESCRIPTION OF THE INVENTION

[0045] The microcapsules and uses thereof described herein are advantageous for several reasons.

[0046] Microcapsules contain a porous or hollow core suitable for absorbing or storing active agents.

[0047] The microcapsules further contain a shell or coating that prevents migration of the active agent from the porous or hollow core during storage, thus avoiding reaction between the encapsulated ingredient and ingredients surrounding the microcapsule.

[0048] The microcapsules are sufficiently mechanically stable to survive shear forces that typically occur during manufacturing processes involving kneading steps, for example, when preparing a paste-like composition.

[0049] The pH-sensitive shell allows the active agent to be released from the porous or hollow core on demand, for example, by contacting the microcapsules with an acidic component.

[0050] This can be advantageous, for example, for redox initiator systems contained in dental two-part paste / paste compositions that contain acidic components.

[0051] Thus, the microcapsules described herein help overcome challenges associated with, for example, producing redox-curable paste / paste compositions.

[0052] The pH-sensitive core-shell microcapsules described herein comprise a porous or hollow core.

[0053] The porous or hollow core is composed of a polymeric material, a cross-linked matrix, which has been found to have sufficient mechanical stability to withstand the shear forces encountered during the mixing process.

[0054] Microcapsules typically have the following characteristics: a) Shape: spherical; b) diameter: 1 to 200 μm, or 1 to 100 μm, or 5 to 100 μm, or 5 to 50 μm, or 5 to 25 μm; c) the pore size of the porous core material: 10 to 200 nm, or 20 to 200 nm, or 50 to 200 nm; d) Mechanical stability The present invention can be characterized by any of the following alone or in combination:

[0055] Combinations of features a) and b), or a) and c), or b) and c), or a), b) and c), or a), b), c) and d) may sometimes be preferred.

[0056] The shape, diameter and pore size can be assessed by microscopy, particularly scanning electron microscopy (SEM).

[0057] The microcapsules are mechanically stable, if so, able to survive the high shear forces typically encountered during paste preparation in a kneader. Suitable tests are described in the Examples section.

[0058] For example, mechanical stability can be achieved when cross-linked polymeric materials, especially highly cross-linked polymeric materials, are used.

[0059] The polymeric material of the porous or hollow core is typically a (meth)acrylate, ie, the polymerization product of polymerizable monomers containing a (meth)acrylate moiety.

[0060] Suitable (meth)acrylates that may be present in the polymeric material include: [ka] where p is an integer at least equal to 1 and R 1 is hydrogen or alkyl), CH2=CR 1 -(CO)-OYR 2 (2) (In the formula, R 1 is hydrogen or methyl, Y is a single bond, alkylene, oxyalkylene, or poly(oxyalkylene), and R 2 is a carbocyclic or heterocyclic group), and mixtures thereof.

[0061] The term "alkylene" refers to a divalent group that is a radical of an alkane, and includes groups that are straight-chained, branched, cyclic, bicyclic, or combinations thereof. Suitable alkylene groups are C1-C 20 , or C1~C 16 , or C1~C 12 , or C1~C 10 , or C1 to C8, or C1 to C6, or C1 to C4 moieties.

[0062] Porous or hollow core materials are typically obtained by emulsion polymerization of suitable monomers, including those described above.

[0063] According to one embodiment, the porous or hollow core polymeric material is obtained by polymerizing components according to formulas (1) and (2), optionally in the presence of other components.

[0064] Other components include a nonionic surfactant and / or a component of formula (3) HO[-CH2-CH(OH)-CH2-O] n -H (3) (wherein n is an integer at least equal to 1).

[0065] The polymerization is typically initiated by an initiator for free radical polymerization.

[0066] According to a further embodiment, the porous or hollow core polymeric material is a polymerization product of a reaction mixture comprising: a) a first phase, i) a compound of formula (3), ii) a nonionic surfactant; and b) a second phase dispersed in the first phase, iii) a monomer composition comprising a monomer of formula (1); iv) polypropylene glycol, preferably having a Mw of at least 500 g / mol; i) optionally a second phase comprising a further monomer of formula (2).

[0067] Suitable processes for producing microcapsules having porous or hollow cores are described, for example, in U.S. Pat. No. 9,422,411 (B2) (Sahouani et al.) or U.S. Patent Application Publication No. 2016 / 008836 (A1) (Sahouani et al.). The contents of these references are incorporated herein by reference. The porous or hollow core contains one component of a redox initiator system. The redox initiator system typically includes an oxidizing agent and a reducing agent. According to one embodiment, the porous or hollow core contains an oxidizing agent.

[0068] The nature and structure of the oxidizing agent are not particularly limited, provided the desired result is not unachievable.

[0069] Suitable oxidizing agents include organic and inorganic peroxides, persulfate components, and mixtures thereof.

[0070] In general, all peroxides, ie inorganic and organic peroxides, that can be incorporated or absorbed by microcapsules can be used.

[0071] Oxidizing agents are typically solids at ambient conditions (23°C, 1013 hPa). In contrast to inorganic peroxides, organic peroxides do not contain metals or metal ions. Thus, organic peroxides typically contain only C, O, H, and optionally halogens (e.g., F, Cl, Br).

[0072] Organic peroxides that can be used include hydroperoxides, ketone peroxides, diacyl peroxides, dialkyl peroxides, peroxyketals, peroxyesters, and peroxydicarbonates.

[0073] Diperoxides that can be used include those in which R1 and R3 are H, alkyl (e.g., C1-C6), branched alkyl (e.g., C1-C6), cycloalkyl (e.g., C5-C 10 ), alkylaryl (e.g., C7-C 12), or aryl (e.g., C6-C 10 ), and R2 is selected from alkyl (e.g., C1-C6), or branched alkyl (e.g., C1-C6).

[0074] Examples of ketone peroxides include methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, methyl cyclohexanone peroxide, and cyclohexanone peroxide.

[0075] Examples of peroxyesters include cumyl peroxyneodecanoate, t-butyl peroxypivalate, t-butyl peroxyneodecanoate, 2,2,4-trimethylpentylperoxy-2-ethylhexanoate, t-amyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, di-t-butyl-peroxyisophthalate, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-3,3,5-trimethylhexanoate, t-butyl peroxyacetate, t-butyl peroxybenzoate, and t-butyl peroxymaleate.

[0076] Examples of peroxydicarbonates include di-3-methoxyperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, diisopropyl-1-peroxydicarbonate, di-n-propylperoxydicarbonate, di-2-ethoxyethyl-peroxydicarbonate, and diallylperoxydicarbonate.

[0077] Examples of diacyl peroxides include acetyl peroxide, benzoyl peroxide, decanoyl peroxide, 3,3,5-trimethylhexanoyl peroxide, 2,4-dichlorobenzoyl peroxide, and lauroyl peroxide.

[0078] Examples of dialkyl peroxides include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,3-bis(t-butylperoxyisopropyl)benzene, and 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexane.

[0079] Examples of peroxyketals include 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexanoate, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, and 4,4-bis(t-butylperoxy)valeric acid-n-butyl ester.

[0080] According to one embodiment, the organic peroxide is a hydroperoxide, in particular an organic peroxide in which R is (e.g., C1-C 20 ) alkyl, (e.g., C3-C 20 ) branched alkyl, (e.g., C6-C 12 ) cycloalkyl, (e.g., C7-C 20 ) alkylaryl, or (e.g., C6-C 12 ) aryl, is a hydroperoxide containing the structural moiety ROOH.

[0081] Examples of suitable organic hydroperoxides include t-butyl hydroperoxide, t-amyl hydroperoxide, p-diisopropylbenzene hydroperoxide, cumene hydroperoxide, pinane hydroperoxide, p-methane hydroperoxide, and 1,1,3,3-tetramethylbutyl hydroperoxide.

[0082] Suitable peroxodisulfate and / or peroxodiphosphate components and / or mixtures thereof that can be used include organic and / or inorganic components.

[0083] Suitable examples include ammonium, sodium, and potassium peroxodisulfate and / or peroxodiphosphate components. Sodium peroxodisulfate may be preferred. Alternatively, the hollow or porous core contains a reducing agent.

[0084] The nature and structure of the reducing agent are not particularly limited, provided the desired result is not unachievable.

[0085] Suitable reducing agents include organic and inorganic components, and mixtures thereof. Reducing agents are typically solids at ambient conditions (23° C., 1013 hPa).

[0086] Reducing agents that can be contained in the porous or hollow core include ascorbic acid moieties, tertiary amine moieties, sulfinate moieties, sulfite moieties, borane moieties, (thio)urea moieties, and (thio)barbituric acid moieties, saccharin, and metal salts thereof.

[0087] Ingredients containing an ascorbic acid moiety, such as salts and esters of ascorbic acid, ethers, ketals, or acetals, may be preferred.

[0088] Suitable salts include alkali metal and alkaline earth metal salts such as Na, K, Ca, and mixtures thereof.

[0089] Esters of ascorbic acid include those in which one or more of the hydroxyl functional groups of ascorbic acid is substituted with a carboxylic acid, particularly C2-C6 30 Examples include those formed by reacting with a carboxylic acid.

[0090] C2~C 30Suitable examples of carboxylic acids include fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linoleelaidic acid, α-linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, and docosahexaenoic acid.

[0091] Particularly preferred are components containing ascorbic acid moieties that can be readily dissolved or mixed into the remaining resin matrix containing the polymerizable component.

[0092] That is, it may sometimes be preferable to use an ascorbic acid moiety-containing component that also has a hydrophobic moiety. Suitable hydrophobic moieties include saturated and unsaturated aliphatic residues (e.g., C2-C6). 30 or C 12 ~C 30 These ascorbic acid derivatives may also function as surfactants (so-called "head / tail" substances). Ascorbyl palmitate, ascorbyl stearate, mixtures thereof, and salts thereof may be particularly preferred.

[0093] When an oxidizing agent is contacted with a reducing agent, a redox reaction typically begins. Such a redox reaction is suitable for initiating the curing of the hardenable component and for resulting in crosslinking of the hardenable component.

[0094] Other components of the redox initiator system that may be present and contained in the porous or hollow core include a transition metal component.

[0095] Suitable transition metal components include organic and / or inorganic salts selected from titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and / or zinc, with copper and iron sometimes being preferred.

[0096] Useful salts include acetates, chlorides, sulfates, benzoates, acetylacetonates, naphthenates, carboxylates, bis(1-phenylpentane-1,3-dione) complexes, salicylates, complexes of any of the transition metals with ethylenediaminetetraacetic acid, and mixtures thereof.

[0097] According to one embodiment, the transition metal component is in an oxidation state that allows the component to be reduced. Useful oxidation states include +2, +3, +4, +5, +6, and +7, as appropriate.

[0098] Copper components are sometimes preferred, with the oxidation state of the copper in the copper component preferably being +1 or +2.

[0099] Typical examples of copper components that can be used include copper salts and complexes, including copper acetate, copper chloride, copper benzoate, copper acetylacetonate, copper naphthenate, copper carboxylate, copper bis(1-phenylpentane-1,3-dione) complex (copper procetonate), copper salicylate, copper thiourea complex, ethylenediaminetetraacetic acid, and / or mixtures thereof. The copper compound may be used in hydrate form or may be water-free. Particularly preferred is copper acetate.

[0100] If desired, the porous or hollow polymer particles can also be filled with other active ingredients, such as dyes, or crosslinking agents, fluoride-releasing agents. Suitable dyes and fluoride-releasing agents are described in the specification below.

[0101] The pH-sensitive core-shell microcapsules described herein also comprise a shell, which surrounds the porous or hollow core of the microcapsule.

[0102] Shells typically have the following characteristics: a) Thickness: 0.1 to 5 μm, or 0.5 to 4 μm, or 1 to 3 μm; b) coverage: covering at least 85%, or at least 90%, or at least 95%, or at least 99% of the surface of the porous or hollow core; c) Sensitive: sensitive to, soluble in, or swellable in acidic or basic components The present invention can be characterized by any of the following alone or in combination:

[0103] The following combinations of features may be preferred: a) and b), a) and c), b) and c), a), b) and c).

[0104] If desired, the shell thickness can be determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), or secondary ion mass spectroscopy (SIMS).

[0105] If desired, the coverage of the shell can be determined by scanning electron microscopy (SEM).The shell is composed of a pH-sensitive material.

[0106] A pH sensitive material is a material that dissolves, swells, or weakens when contacted with another substance that is either basic or acidic in nature.

[0107] According to one embodiment, the pH sensitive material is an acid sensitive material.

[0108] Acid-sensitive materials typically have the following characteristics: a) dissolving in a composition having a pH in the range of 1 to 6, or 1 to 4; b) be stable in compositions having a pH in the range of 14 to 7; c) being polymeric, for example having a molecular weight of 10,000 to 1,000,000 g / mol, or 20,000 to 500,000 g / mol, or 50,000 to 300,000 g / mol; d) The glass temperature is less than 200 degrees, or less than 180 degrees, or less than 150 degrees, or less than 100 degrees. The present invention can be characterized by any of the following alone or in combination:

[0109] Examples of acid-sensitive materials include copolymers of methyl (meth)acrylate and diethylaminoethyl (meth)acrylate (such as those sold under the trade name Kollicoat™ Smartseal), copolymers of methyl (meth)acrylate, butyl methacrylate and dimethylaminoethyl (meth)acrylate (such as those sold under the trade name Eudragit™ E), poly(2-(dimethylamino)ethyl methacrylate), cellulose acetate phthalate, sodium carboxymethylcellulose, hydroxypropylmethylcellulose phthalate, poly(vinyl acetate phthalate), poly(4-vinylpyridine), chitosan, and mixtures thereof.

[0110] According to another embodiment, the pH sensitive material is a base sensitive material.

[0111] Base-sensitive materials typically have the following characteristics: a) dissolving in a composition having a pH in the range of 14 to <7, or 12 to 8; b) being stable in compositions having a pH in the range of 1 to 7, or in the range of 1 to 5; c) being polymeric, for example having a molecular weight of 10,000 to 1,000,000 g / mol, or 20,000 to 500,000 g / mol, or 50,000 to 300,000 g / mol; d) Glass temperature T g : Less than 200°C, or less than 180°C, or less than 150°C, or less than 100°C It is characterized by any one or combination of the following:

[0112] Examples of base-sensitive materials include copolymers of methacrylic acid and methyl (meth)acrylate (e.g., those sold under the trade names Eudragit® L, S), copolymers of methacrylic acid and alkyl (e.g., C 1―6 ) (meth)acrylate copolymers, methacrylic acid, methyl (meth)acrylate and methyl acrylate copolymers (such as those sold under the trade name Eudragit™ FS 30D), poly(acrylic acid), poly(sulfonic acid), poly(styrene sulfonic acid), poly(2-hydroxyethyl methacrylate) phosphate, hyaluronic acid, and mixtures thereof.

[0113] The pH-sensitive microcapsules described herein can be prepared as follows.

[0114] Porous or hollow particles as described herein and the components of a redox initiator system are provided.

[0115] The porous or hollow particles are treated with the components of the redox initiator system to allow the porous particles to absorb the components of the redox initiator system.

[0116] If the components of the redox initiator system are in a solid or highly viscous state, the components are typically first dissolved in a solvent.

[0117] After treatment, the solvent is typically evaporated, for example, by drying the treated microcapsules.

[0118] Suitable solvents include water and low boiling point solvents, which typically have a boiling point below 80° C. at atmospheric pressure.

[0119] Suitable solvents include water, methylene chloride, low boiling ethers (eg, tetrahydrofuran, methyl tert.butyl ether), alcohols (eg, methanol, ethanol, iso- and n-propanol), and mixtures thereof.

[0120] After treatment, the components of the redox initiator system are located within or absorbed by the pores of the porous particles.

[0121] Optionally, the treatment process has the following characteristics: a) Duration: 5-60 minutes; b) Temperature: 20~60℃; c) Pressure: atmospheric pressure d) Stirring the mixture The present invention can be characterized by any of the following alone or in combination:

[0122] The following combinations of features may be preferred: a) and b), a), b) and c), or a), b), c) and d).

[0123] The porous or hollow particles having components of the redox initiator system contained within their pores are then treated with a pH-sensitive coating.

[0124] Examples of pH-sensitive coatings include those mentioned above.

[0125] Such coating processes have the following characteristics: a) The coating process is carried out by spray drying; b) Duration: 0.1 to 10 hours, or 0.2 to 5 hours; c) Temperature: 20 to 90°C, or 30 to 80°C, or 40 to 70°C; d) Pressure: Atmospheric pressure (e.g., 900 to 1,030 hPa) The present invention can be characterized by any of the following alone or in combination:

[0126] The following combinations of features may be preferred: b) and c), or a), b) and c), or a), b), c) and d).

[0127] Spray drying is typically used to g It is carried out at a temperature near the glass temperature.

[0128] This temperature has often been found to be adequate to ensure proper encapsulation and to obtain a smooth and uniform surface.

[0129] Therefore, typical coatings have a glass transition temperature (T) below 200°C. g ) and a molecular weight (Mw) in the range of 20,000 to 500,000 g / mol.

[0130] Spray drying is typically used to g This can help achieve a smooth and uniform surface seal and successful manufacturing.

[0131] The present invention also relates to a kit of parts, which includes a catalyst paste and a base paste.

[0132] The catalyst paste includes the pH-sensitive core-shell microcapsules described herein, and the catalyst paste includes a first component of a redox initiator system.

[0133] The base paste includes an acidic or basic component and a second component of a redox initiator system.

[0134] The first and second components of the redox initiator system together form an initiator system suitable for initiating the curing of the catalyst paste or the base paste or the curable components present in the catalyst paste and base paste.

[0135] According to one embodiment, the first component of the redox initiator system contained in the pH-sensitive microcapsules is a reducing agent and the second component of the redox initiator system is an oxidizing agent.

[0136] According to another embodiment, the first component of the redox initiator system contained in the pH-sensitive microcapsules is an oxidizing agent and the second component of the redox initiator system is a reducing agent.

[0137] The oxidizing agent and reducing agent include those described above.

[0138] According to one embodiment, the kit of parts comprises two types of microcapsules: microcapsules containing a reducing agent and microcapsules containing an oxidizing agent.

[0139] The shell of these microcapsules is composed of either an acid-sensitive or a base-sensitive material, preferably an acid-sensitive material. According to one embodiment, the base paste contains an acidic component.

[0140] The acid component included in the base paste is a component suitable for interacting with the pH-sensitive shell of the microcapsules such that the pH-sensitive shell is weakened (e.g., dissolved) and allows the first component of the redox initiator system to migrate out of the pores of the porous core.

[0141] The nature and structure of these components are not particularly limited, provided that the intended purpose is not rendered unachievable. Inorganic and organic acidic components can be used as desired.

[0142] Inorganic acidic components that can be used include hydrochloric acid, sulfuric acid, phosphoric acid, mixtures thereof, and acid salts thereof.

[0143] Organic acidic components that can be used include monocarboxylic acids such as formic acid, acetic acid, and benzoic acid and derivatives of these acids, or dicarboxylic acids selected from oxalic acid, malonic acid, succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, sorbic acid, phthalic acid, and terephthalic acid and derivatives of these acids, or tricarboxylic acids selected from hemimelanic acid, trimellitic acid, trimesic acid, agric acid, citric acid, and 1,2,3-propanetricarboxylic acid and derivatives of these acids, or multicarboxylic acids selected from the group consisting of pyromellitic acid and mellitic acid and derivatives of these acids, or polycarboxylic acids selected from polyacrylic acid and polymethacrylic acid and derivatives of these acids, and mixtures thereof.

[0144] Such acidic ingredients have the following characteristics: a) pKs value: 5 or less, 4 or less, or 3.5 or less, or 3 or less, or 2 or less; b) containing an acidic moiety selected from a sulfonic acid, sulfinic acid, phosphoric acid, phosphonic acid, phosphinic acid, or carboxylic acid moiety; The present invention can be characterized by any of the following alone or in combination:

[0145] Optionally, the acidic component may include one or more polymerizable moieties, such as (meth)acrylate moieties. Optionally, there may be one or more polymerizable components having acidic moieties.

[0146] Polymerizable components having an acid moiety can typically be represented by the formula: A n B.C. m wherein A is an ethylenically unsaturated group such as a (meth)acrylic moiety; B is (i) a straight or branched C-C alkyl group optionally substituted with other functional groups (e.g., halides (including Cl, Br, I), OH, or mixtures thereof); 12 (ii) C-C optionally substituted with other functional groups (e.g., halide, OH, or mixtures thereof) 12aryl; (iii) organic groups having 4 to 20 carbon atoms bonded to each other by one or more ether, thioether, ester, thioester, thiocarboyl, amide, urethane, carbonyl, and / or sulfonyl bonds; C is an acidic group or a precursor of an acidic group, such as an acid anhydride; m, n are independently selected from 1, 2, 3, 4, 5, or 6; Acidic groups include one or more carboxylic acid residues such as -COOH or -CO-O-CO-, phosphoric acid residues such as -OP(O)(OH)OH, phosphonic acid residues such as -CP(O)(OH)(OH), sulfonic acid residues such as -SOH, or sulfinic acid residues such as -SOH.

[0147] Examples of polymerizable components having an acid moiety include glycerol phosphate mono(meth)acrylate, glycerol phosphate di(meth)acrylate, hydroxyethyl (meth)acrylate (e.g., HEMA) phosphate, bis((meth)-acryloxyethyl)phosphate, (meth)acryloxy-propyl phosphate, bis((meth)-acryloxypropyl)phosphate, bis((meth)acryloxy)-propyloxyphosphate, (meth)acryloxyhexyl phosphate, bis((meth)acryloxyhexyl)phosphate, (meth)-acryloxyoctyl phosphate. Examples of suitable solidifying components include, but are not limited to, bis((meth)acryloxyoctyl)phosphate, (meth)acryloxydecylphosphate, bis((meth)acryloxydecyl)phosphate, caprolactone methacrylate phosphate, citric acid di- or tri-methacrylate, poly(meth)acrylated oligomaleic acid, poly(meth)acrylated polymaleic acid, poly(meth)acrylated poly(meth)acrylic acid, poly(meth)acrylated polycarboxyl-polyphosphonic acid, poly(meth)acrylated polychlorophosphate, poly(meth)acrylated polysulfonate, poly(meth)acrylated polyboric acid, and the like. Derivatives of these solidifying components having acid moieties that can readily react, for example with water, to form the above specific examples, such as acid halides or anhydrides, are also contemplated.

[0148] Monomers, oligomers, and polymers of unsaturated carboxylic acids, such as (meth)acrylic acid, aromatic (meth)acrylated acids (e.g., methacrylated trimellitic acid), and anhydrides thereof, can also be used.

[0149] Optionally, an acidic component is present, typically in the following amounts: Lower limit amount: at least 2, or at least 3, or at least 4 wt. %; Upper limit: maximum 50, or maximum 40, or maximum 30% by weight; Range: 2-50, or 3-40, or 4-30 wt.%; The weight percentages are relative to the weight of the composition obtained by mixing the catalyst paste and the base paste of the kit of parts. According to another embodiment, the base paste contains a basic component.

[0150] The basic component included in the base paste is a component suitable for interacting with the pH-sensitive shell of the microcapsules such that the pH-sensitive shell is weakened (e.g., dissolved) and allows the first component of the redox initiator system to migrate out of the pores of the porous core.

[0151] The nature and structure of these components are not particularly limited as long as the intended purpose is not rendered unachievable. Inorganic and organic basic components can be used as desired.

[0152] Inorganic basic components that can be used include salts of hydroxides, carbonates, phosphates (including sodium, potassium, calcium, and ammonium salts) and aqueous solutions thereof, as well as inorganic alkaline glasses such as fluoroaluminosilicate glasses (acid-reactive glasses).

[0153] Organic basic components include primary, secondary, and tertiary aliphatic (eg, C2-C6 alkyl) amines, and mixtures thereof.

[0154] If a basic component is present, it is typically present in the following amounts: Lower limit amount: at least 1, or at least 3, or at least 5% by weight; Upper limit: up to 70, or up to 60, or up to 50% by weight; Range: 1-70, or 3-60, or 5-50 wt.%; The weight percentages are based on the weight of the composition obtained by mixing the catalyst paste and base paste of the kit of parts.

[0155] The hardenable components typically contained in the paste of the kit of parts are components that can be polymerized in the presence of a redox initiator system. According to one embodiment, the hardenable components do not contain acidic moieties.

[0156] Optionally, one or more polymerizable components that do not have acidic moieties may be present.

[0157] The nature and structure of these constituents are not particularly limited, as long as the intended purpose is not rendered unachievable.

[0158] The polymerizable component without acidic moieties is typically a free-radically polymerizable material that includes an ethylenically unsaturated monomer, monomer, or oligomer or polymer.

[0159] Suitable polymerizable components without acidic moieties have the following formula: A n BA m wherein A is an ethylenically unsaturated group such as a (meth)acrylic moiety; B is (i) a straight or branched C-C alkyl group optionally substituted with other functional groups (e.g., halides (including Cl, Br, I), OH, or mixtures thereof). 12 (ii) C-C optionally substituted with other functional groups (e.g., halide, OH, or mixtures thereof) 12 aryl, or (iii) organic groups having 4 to 20 carbon atoms bonded to each other by one or more ether, thioether, ester, thioester, thiocarboyl, amide, urethane, carbonyl, and / or sulfonyl bonds; m, n are independently selected from 0, 1, 2, 3, 4, 5, or 6, provided that n+m is greater than 0, i.e., at least one A group is present. can be characterized by

[0160] Such polymerizable materials include methyl acrylate, methyl methacrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-hexyl (meth)acrylate, stearyl (meth)acrylate, allyl (meth)acrylate, glycerol di(meth)acrylate, and diurethane dimethacrylate called UDMA (a mixture of isomers, e.g., Rohm), which is the reaction product of 2-hydroxyethyl methacrylate (HEMA) and 2,2,4-trimethyl-hexa-methylene diisocyanate (TMDI). Plex6661-0), glycerol tri(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, trimethylolpropane tri(meth)acrylate, 1,2,4-butanetriol tri(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, sorbitol hexa(meth)acrylate, bis[1-(2-(meth)acryloxy)]-p-ethoxy-phenyldimethylmethane, bis[1-(3-methacryloxy-2-hydroxybenzoyl)methyl]methyl] Mono-, di-, or poly-acrylates and methacrylates such as bis[1-(3-acryloxy-2-hydroxy)]-p-propoxy-phenyl-dimethyl-methane (BisGMA), bis[1-(3-acryloxy-2-hydroxy)]-p-propoxy-phenyl-dimethyl-methane, and trishydroxyethyl-isocyanurate trimethacrylate; bis-acrylates and bis-methacrylates of polyethylene glycols having molecular weights of 200 to 500, copolymerizable mixtures of acrylated monomers (see U.S. Pat. No. 4,652,274), and acrylated oligomers (see U.S. Pat. No. 4,642,126); and vinyl compounds such as styrene, diallyl phthalate, divinyl succinate, divinyl adipate, and divinyl phthalate; and polyfunctional (meth)acrylates containing urethane, urea, or amide groups.Mixtures of two or more of these free radically polymerizable materials can be used if desired.

[0161] Further polymerizable components that may be present include di(meth)acrylates of ethoxylated bis-phenol A, such as 2,2'-bis(4-(meth)acryloxytetraethoxyphenyl)propane, urethane (meth)acrylates, and (meth)acrylamides. The monomers used may also be esters of [α]-cyanoacrylic acid, crotonic acid, cinnamic acid, and sorbic acid.

[0162] Methacrylic esters as described in EP 0235826, such as bis[3[4]-methacryl-oxymethyl-8(9)-tricyclo[5.2.1.0 2,6 ]decylmethyl triglycolate can also be used. 2,2-bis-4(3-methacryloxy-2-hydroxypropoxy)phenylpropane (bis-GMA), 2,2-bis-4(3-methacryloxy-propoxy)phenylpropane, 7,7,9-trimethyl-4,13-dioxo-3,14-dioxa-5,12-diaza-hexadecane-1,16-dioxydimethacrylate (UDMA), urethane (meth)acrylate, and bishydroxymethyltricyclo-(5.2.1.0 2,6 The di(meth)acrylate of decane is also suitable.

[0163] These ethylenically unsaturated monomers can be used alone or in combination with other ethylenically unsaturated monomers in dental compositions. Other hardenable components that can be added in addition to or in addition to these components include oligomeric or polymeric compounds such as polyester (meth)acrylates, polyether (meth)acrylates, polycarbonate (meth)acrylates, and polyurethane (meth)acrylates. The molecular weight of these compounds is typically less than 20,000 g / mol, particularly less than 15,000 g / mol, and especially less than 10,000 g / mol.

[0164] The hardening component without acidic moieties is typically present in the following amounts: Lower limit amount: at least 5, or at least 10, or at least 20% by weight; Upper limit: maximum 65, or maximum 55, or maximum 45% by weight; Range: 5-65, or 10-55, or 20-45 wt.%; The weight percentages are based on the weight of the composition obtained by mixing the catalyst paste and base paste of the kit of parts.

[0165] The catalyst paste and / or base paste may contain further components including fillers, photoinitiators, and additives including fluoride releasers, stabilizers, and colorants.

[0166] The amount and type of each ingredient in the composition should be adjusted to provide the desired physical and handling properties before and after polymerization.

[0167] If desired, one or more fillers may be present, the nature and structure of which are not particularly limited, provided that the intended purpose is not rendered unachievable.

[0168] The addition of fillers can be beneficial for adjusting rheological properties such as viscosity, for example. The filler content also typically affects the physical properties of the composition after solidification, such as hardness or flexural strength.

[0169] The size of the filler particles should be such that a homogeneous mixture with the solidifying components forming the resin matrix can be obtained. The average particle size of the filler may range from 5 nm to 100 μm.

[0170] If desired, particle size measurements of the filler particles can be performed by TEM (transmission electron microscopy) techniques, which analyze the population and provide an average particle size.

[0171] A preferred method for measuring particle size can be described as follows: A sample approximately 80 nm thick is placed on a 200-mesh copper grid with a carbon-stabilized Formvar substrate (SPI Supplies, a division of Structure Probe, Inc., West Chester, PA). Transmission electron microscope (TEM) photographs are obtained using a JEOL™ 200CX (sold by JEOL, Ltd. of Akishima, Japan, and JEOL USA, Inc.) at 200 Kv. A collection of approximately 50-100 particles can be sized to determine the average diameter.

[0172] The filler typically comprises a non-acid-reactive filler, which is a filler that does not undergo an acid / base reaction with an acid.

[0173] Useful non-acid-reactive fillers include fumed silica and fillers based on non-acid-reactive fluoroaluminosilicate glasses, quartz, powdered glass, water-insoluble fluorides such as CaF2, silica gels and granules such as silicic acids, especially pyrogenic silicic acids, cristobalite, calcium silicate, zirconium silicate, and zeolites, including molecular sieves.

[0174] Suitable fumed silicas include, for example, products sold under the tradenames Aerosil™ series OX-50, -130, -150, and -200, Aerosil™ R8200, -R805 available from Degussa AG (Hanau, Germany), CAB-O-SIL™ M5 available from Cabot Corp (Tuscola, Ill.), and HDK types available from Wacker, such as HDK™-H2000, HDK™ H15, HDK™ H18, HDK™ H20, and HDK™ H30.

[0175] Fillers that can be used to provide radiopacity to the dental materials described herein include heavy metal oxides and fluorides. As used herein, "radiopacity" refers to the ability of a hardened dental material to be distinguished from tooth structures using standard dental X-ray equipment in a conventional manner. Radiopacity in dental materials is advantageous in certain cases when X-rays are used to diagnose dental conditions. For example, radiopaque materials allow the detection of secondary caries that may have formed in the dental tissue surrounding the filling.

[0176] Oxides or fluorides of heavy metals having atomic numbers greater than about 28 may be preferred. The heavy metal oxide or fluoride should be selected so as not to impart undesirable color or shade to the hardened resin in which the filler is dispersed. For example, iron and cobalt are not preferred because they impart dark colors and contrasting colors to the neutral tooth color of the dental material. More preferably, the heavy metal oxide or fluoride is an oxide or fluoride of a metal having an atomic number greater than 30. Suitable metal oxides are oxides of yttrium, strontium, barium, zirconium, hafnium, niobium, tantalum, tungsten, bismuth, molybdenum, tin, zinc, lanthanides (i.e., elements with atomic numbers ranging from 57 to 71), cerium, and combinations thereof. Suitable metal fluorides include, for example, yttrium trifluoride and ytterbium trifluoride. More preferably, the material of the present invention optionally includes an oxide or fluoride of a heavy metal having an atomic number greater than 30 and less than 72. Particularly preferred metal oxides that impart radiopacity include lanthanum oxide, zirconium oxide, yttrium oxide, ytterbium oxide, barium oxide, strontium oxide, cerium oxide, and combinations thereof. The heavy metal oxide particles may be agglomerated. In this case, the average diameter of the agglomerated particles is preferably less than 200 nm, more preferably less than 90 nm.

[0177] Other suitable fillers that increase radiopacity are barium and strontium salts, particularly strontium sulfate and barium sulfate.

[0178] Fillers that can be used also include nano-sized fillers such as nano-sized silica.

[0179] Suitable nano-sized particles typically have an average particle size in the range of 5 to 80 nm.

[0180] Preferred nano-sized silica particles include those commercially available under the product name NALCO™ COLLOIDAL SILICAS from Nalco Chemical Co. (Naperville, Ill.) (e.g., NALCO™ products 1040, 1042, 1050, 1060, 2327, and 2329), those available from Nissan Chemical America Company, Houston, Texas (e.g., SNOWTEX-ZL, -OL, -O, -N, -C, -20L, -40, and -50), those available from Admatechs Co., Ltd., Japan (e.g., SX009-MIE, SX009-MIF, SC1050-MJM, and SC1050-MLV), and those available from Grace Chemicals Co., Ltd., Japan (e.g., SX009-MIF, SC1050-MJM, and SC1050-MLV). GmbH & Co. KG, Worms, Germany (e.g., those available under the LUDOX™ product name, such as P-W50, P-W30, P-X30, P-T40, and P-T40AS), those available from Akzo Nobel Chemicals GmbH, Leverkusen, Germany (e.g., those available under the LEVASIL™ product name, such as 50 / 50%, 100 / 45%, 200 / 30%, 200A / 30%, 200 / 40%, 200A / 40%, 300 / 30%, and 500 / 15%), and those available from Bayer Material Science AG, Leverkusen, Germany (e.g., those available under the DISPERCOLL™ S product name, such as 5005, 4510, 4020, and 3030).

[0181] Surface-treating the nano-sized silica particles prior to placement in the dental material can improve dispersion stability in the resin. Preferably, the surface treatment stabilizes the nano-sized particles so that they are well dispersed in the hardening resin, resulting in a substantially homogeneous composition. Furthermore, it is preferred that at least a portion of the silica surface be modified with a surface treatment agent, so that the stabilized particles can copolymerize or otherwise react with the hardening resin during hardening.

[0182] Thus, silica particles and other suitable non-acid-reactive fillers may be treated with a resin compatibilizing surface treatment.

[0183] If fillers are present, they are typically present in the following amounts: Lower limit amount: at least 1, or at least 5, or at least 10% by weight; Upper limit: up to 80, or up to 70, or up to 60% by weight; Range: 1-80, or 5-70, or 10-60 wt.%; The weight percentages are based on the weight of the composition obtained by mixing the catalyst paste and base paste of the kit of parts.

[0184] The kit of parts may also include a photoinitiator.

[0185] The nature and structure of the photoinitiator are not particularly limited, as long as the intended purpose is not adversely affected. Photoinitiators suitable for free radical polymerization are generally known to those skilled in the art of working with dental materials.

[0186] The photoinitiator is preferably one that can polymerize polymerizable monomers by the action of visible light having a wavelength of 350 nm to 500 nm.

[0187] Suitable photoinitiators often contain an alpha-diketo moiety, an anthraquinone moiety, a thioxanthone moiety, or a benzoin moiety.

[0188] Examples of photoinitiators include camphorquinone, 1-phenylpropane-1,2-dione, benzil, diacetyl, benzil dimethyl ketal, benzil diethyl ketal, benzil di(2-methoxyethyl) ketal, 4,4'-dimethylbenzyl dimethyl ketal, anthraquinone, 1-chloroanthraquinone, 2-chloro-anthraquinone, 1,2-benz-anthraquinone, 1-hydroxy-anthraquinone, 1-methyl-anthraquinone, 2-ethyl-anthraquinone, 1-bromoanthraquinone, thioxanthone, and 2-isopropylthioxanthone. , 2-nitrothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2-chloro-7-trifluoromethylthioxanthone, thioxanthone-10,10-dioxide, thioxanthone-10-oxide, benzoin methyl ether, benzoin ethyl ether, isopropyl ether, benzoin isobutyl ether, benzophenone, bis(4-dimethyl-amino-phenyl) ketone, 4,4'-bisdiethylaminobenzophenone.

[0189] The use of acylphosphine oxides has also proven useful.

[0190] Suitable acylphosphine oxides are those of the general formula: (R 9 )2-P(=O)-C(=O)-R 10 (In the formula, each R 9 may individually be hydrocarbyl groups such as alkyl, cycloalkyl, aryl, and aralkyl, any of which may be substituted with halo-, alkyl-, or alkoxy groups, or two R 9 groups can be attached to form a ring with the phosphorus atom, R 10 is a hydrocarbyl group, an S-, O-, or N-containing 5- or 6-membered heterocyclic group, or -ZC(=O)-P(=O)-(R 9 )2 groups, where Z represents a divalent hydrocarbyl group such as alkylene or phenylene having 2 to 6 carbon atoms. can be characterized by

[0191] Suitable systems are also described, for example, in US Pat. No. 4,737,593 (Ellrich et al.), the contents of which are incorporated herein by reference.

[0192] Preferred acylphosphine oxides are those represented by R 9 and R 10 The group is phenyl, or lower alkyl- or lower alkoxy-substituted phenyl. "Lower alkyl" and "lower alkoxy" refer to such groups having 1 to 4 carbon atoms. In particular, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin™ TPO, BASF) has been found to be useful.

[0193] Suitable bisacylphosphine oxides have the following general formula: [ka] [wherein n is 1 or 2, and R 4 , R 5 , R 6 and R 7 is H, C 1―4 Alkyl, C 1―4 alkoxyl, F, Cl, or Br; R 2 and R 3 are the same or different and are cyclohexyl, cyclopentyl, phenyl, naphthyl, or biphenylyl radicals, cyclopentyl, cyclohexyl, phenyl, naphthyl, or F, Cl, Br, I, C 1―4 Alkyl and / or C 1―4 represents an alkoxyl or biphenylyl radical substituted with an S- or N-containing 5- or 6-membered heterocycle, or R 2 and R 3 is a ring containing 4 to 10 carbon atoms, optionally containing 1 to 6 C 1―4 linked to form a ring substituted with an alkyl radical] It can be expressed as:

[0194] Further examples include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-ethoxy-phenyl-phosphine oxide, bis-(2,6-dichlorobenzoyl)-4-biphenylylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2-naphthyl- Phosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-chloro-phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,4-dimethoxyphenyl-phosphine oxide, bis-(2,6-dichlorobenzoyl)decylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-octylphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,5-dimethyl Phenylphosphine oxide, bis-(2,6-dimethoxy-benzoyl)-phenylphosphine oxide, bis-(2,4,6-trimethyl-benzoyl)-2,5-dimethyl-phenylphosphine oxide, bis-(2,6-dichloro-3,4,5-trimethoxy-benzoyl)-2,5-dimethylphenyl-phosphine oxide, bis-(2,6-dichloro-3,4,5-trimethoxybenzoyl)-4-ethoxyphenylphosphine oxide, bis-(2-methyl-1-naphthoyl)-2,5 -dimethyl-phenyl-phosphine oxide, bis-(2-methyl-1-naphthoyl)-phenylphosphine oxide, bis-(2-methyl-1-naphthoyl)-4-biphenylylphosphine oxide, bis-(2-methyl-1-naphthoyl)-4-ethoxyphenylphosphine oxide, bis-(2-methyl-1-naphthoyl)-2-naphthylphosphine oxide, bis-(2-methyl-1-naphthoyl)-4-propylphenylphosphine oxide, bis-(2-methyl-1-naphthoyl)-2,5-dimethyl-phosphine oxide, bis-(2-methoxy-1-naphthoyl)-4-ethoxyphenyl-phosphine oxide, bis-(2-methoxy-1-naphthoyl)-4-biphenylylphosphine oxide, bis-(2-methoxy-1-naphthoyl)-2-naphthyl-phosphine oxide and bis-(2-chloro-1-naphthoyl)-2,5-dimethylphenyl-phosphine oxide.

[0195] The acylphosphine oxide bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (formerly known as IRGACURE™ 819, Ciba Specialty Chemicals) is sometimes preferred.

[0196] If a photoinitiator is present, it is typically present in the following amounts: Lower limit amount: at least 0.1, or at least 0.2, or at least 0.3 wt.%; Upper limit: maximum 10, or maximum 8, or maximum 6% by weight; Range: 0.1-10, or 0.2-8, or 0.3-6 wt.%; The weight percentages are based on the weight of the composition obtained by mixing the catalyst paste and base paste of the kit of parts.

[0197] Examples of dyes or pigments that can be used include titanium dioxide or zinc sulfide (lithopone), red iron oxide 3395, Bayferrox 920 Z Yellow, Neazopon Blue 807 (a copper phthalocyanine dye) or Helio Fast Yellow ER. These additives can be used as individual colorants in the dental composition.

[0198] Examples of photobleachable colorants that may be present include rose bengal, methylene violet, methylene blue, fluorescein, eosin yellow, eosin Y, ethyl eosin, eosin blueish, eosin B, erythrosin B, erythrosin yellowish blend, toluidine blue, 4',5'-dibromofluorescein, and blends thereof. Further examples of photobleachable colorants can be found in U.S. Patent No. 6,444,725.

[0199] Examples of fluoride stripping agents that may be present include natural or synthetic fluoride minerals. These fluoride sources may optionally be treated with a surface treatment agent.

[0200] Further additives which may be added include stabilizers, in particular free radical scavengers, such as substituted and / or unsubstituted hydroxyaromatic compounds (e.g. butylated hydroxytoluene (BHT), hydroquinone, hydroquinone monomethyl ether (MEHQ), 3,5-di-tert-butyl-4-hydroxy-anisole (2,6-di-tert-butyl-4-ethoxyphenol), 2,6-di-tert-butyl-4-(dimethyl-amino)-methyl-phenol or 2,5-di-tert-butylhydroquinone, 2-(2'-hydroxybenzoyl)-2-methyl-4-methyl-2 ... 2-(2'-hydroxy-5'-methylphenyl)-2H-benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)-2H-benzotriazole, 2-hydroxy-4-methoxy-benzo-phenone (UV-9), 2-(2'-hydroxy-4',6'-di-tert-pentyl-phenyl)-2H-benzotriazole, 2-hydroxy-4-n-octoxy-benzo-phenone, 2-(2'-hydroxy-5'-methacryl-oxy-ethylphenyl)-2H-benzotriazole, and phenothiazine.

[0201] Further additives that can be added include inhibitors (e.g., 1,2-diphenylethylene), plasticizers (including polyethylene glycol derivatives, polypropylene glycol, low molecular weight polyesters, dibutyl, dioctyl, dinonyl and diphenyl phthalate, di(isononyl adipate), tricresyl phosphate, paraffin oil, glycerol triacetate, bisphenol A diacetate, ethoxylated bisphenol A diacetate, and silicone oil), flavorings.

[0202] These adjuvants or additives do not have to be present, and may be absent altogether, but when present they are typically present in amounts that are not deleterious for the intended purpose.

[0203] If additives are present, they are typically present in the amounts set forth below.

[0204] Lower limit amount: at least 0.01% by weight, or at least 0.05% by weight, or at least 0.1% by weight; Upper limit: maximum 15% by weight, or maximum 10% by weight, or maximum 5% by weight; Range: 0.01% to 15% by weight, or 0.05% to 10% by weight, or 0.1% to 5% by weight.

[0205] Amounts are given by weight of the total composition obtained when the catalyst paste and base paste are combined.

[0206] The catalyst paste and base paste of the kit of parts are typically stored in a packaging device during storage.

[0207] The catalyst paste and base paste of the kits of parts described herein may be contained in separate sealable containers (eg, made from plastic or glass).

[0208] For use, the physician can remove appropriate portions of the contained compositions from the containers and manually mix the portions on a mixing plate.

[0209] According to a preferred embodiment, the catalyst paste and the base paste are contained in separate compartments of a storage device.

[0210] The storage device typically includes two compartments for storing each part, each compartment equipped with a nozzle for delivering the respective part. Once the appropriate amounts have been delivered, the parts can then be mixed manually on a mixing plate.

[0211] According to another preferred embodiment, the storage device has an interface for receiving a static mixing tip. The mixing tip is used to mix the respective pastes. Static mixing tips are commercially available, for example, from the SulzerMixpac company. Suitable storage devices include cartridges, syringes, and tubes.

[0212] The reservoir typically comprises two housings or compartments, one at a front end having a nozzle, and one at a rear end, and at least one piston movable within the housing or compartment.

[0213] Cartridges that can be used are described, for example, in U.S. Patent Application Publication No. 2007 / 0090079 or U.S. Patent No. 5,918,772, the disclosures of which are incorporated by reference. Some usable cartridges are commercially available, for example, from Sulzer Mixpac AG (Switzerland). Static mixing tips that can be used are described, for example, in U.S. Patent Application Publication No. 2006 / 0187752 or U.S. Patent No. 5,944,419, the disclosures of which are incorporated by reference. Mixing tips that can be used are also commercially available from Sulzer Mixpac AG (Switzerland).

[0214] Other suitable storage devices are described, for example, in WO 2010 / 123800 (3M), WO 2005 / 016783 (3M), WO 2007 / 104037 (3M), WO 2009 / 061884 (3M) (in particular the device shown in Figure 14 of WO 2009 / 061884 (3M) or WO 2015 / 073246 (3M), or the device shown in Figure 1 of WO 2015 / 07346). These storage devices have the shape of a syringe. The contents of these references are likewise incorporated herein by reference.

[0215] Alternatively, although not preferred, the paste / paste compositions described herein can be dispensed in two individual syringes, and the individual pastes can be mixed by hand before use.

[0216] Accordingly, the present invention is also directed to a device for storing a kit of parts as described herein, comprising two compartments, compartment A and compartment B, compartment A containing a catalyst paste and compartment B containing a base paste, wherein the catalyst paste and base paste are as described herein, and both compartment A and compartment B comprising an interface for receiving an entrance orifice of a nozzle or static mixing tip.

[0217] The mixing ratio of the base paste and the catalyst base paste is typically 3:1 to 1:3 by volume, preferably 2:1 to 1:2, and more preferably 1:1.

[0218] The pH-sensitive microcapsules described herein are particularly useful in preparing hardenable compositions that include redox initiator systems.

[0219] According to one embodiment, the hardenable composition is a dental or orthodontic composition.

[0220] According to one embodiment, the hardenable composition is a dental or orthodontic cement, adhesive or filling material.

[0221] The pH-sensitive microcapsules described herein are particularly useful for producing curable compositions obtained by combining two pastes, a base paste and a catalyst paste, one of which contains the pH-sensitive microcapsules described herein and the other paste containing an acidic component.

[0222] When the two pastes are mixed, the paste containing the acidic component comes into contact with the pH-sensitive shell of the pH-sensitive microcapsules. Upon contact, the pH-sensitive shell dissolves, allowing the components of the redox initiator system to migrate from the porous core. Self-adhesive dental materials typically contain an acidic paste.

[0223] The acidity of this paste can be used as a trigger to remove the shell from the microcapsules when both pastes are mixed, thereby releasing the encapsulated components or agents, especially components of the redox initiator system.The present invention also relates to a process for curing the curable composition.

[0224] Such a process typically involves the following steps:

[0225] A catalyst paste is prepared that includes the pH-sensitive microcapsules described herein and a base paste that includes an acidic or basic component.

[0226] Either the catalyst paste or the base paste, or the catalyst paste and the base paste, comprise a curable component and a further component of a redox initiator system.

[0227] The catalyst paste and the base paste are mixed.

[0228] The acidic component contained in the base paste dissolves or weakens the pH-sensitive shell of the microcapsules, resulting in the release of the redox initiator component contained therein.

[0229] When brought into contact with one another, the redox initiator components initiate curing of the curable components of the curable composition.

[0230] According to one embodiment, the kit of parts is characterized as follows: The catalyst paste pH-sensitive microcapsules as described herein comprising a reducing component, preferably a component comprising an ascorbic acid moiety; a curable non-acidic (meth)acrylate component; and a filler; Base paste B is an acidic component, preferably a polymerizable component comprising an acidic moiety; a curable (meth)acrylate component; and Filler and an oxidizing component, The reducing component and the oxidizing agent form a redox initiator system for curing the curable (meth)acrylate component.

[0231] According to another embodiment, the kit of parts is characterized as follows: The catalyst paste pH-sensitive microcapsules as described herein comprising an oxidizing component, preferably a component comprising a peroxide moiety; a curable non-acidic (meth)acrylate component; and a filler; Base paste B is an acidic component, preferably a polymerizable component comprising an acidic moiety; a curable (meth)acrylate component; and Filler and a reducing component, The reducing component and the oxidizing agent form a redox initiator system for curing the curable (meth)acrylate component.

[0232] The shell of a pH-sensitive microcapsule is typically an acid-sensitive material, including those listed above.

[0233] The following examples are intended to illustrate the invention. [Example]

[0234] Unless otherwise indicated, all parts and percentages are by weight, all water is deionized water, and all molecular weights are weight average molecular weight. Furthermore, unless otherwise indicated, all experiments were conducted at ambient conditions (23° C., 1013 mbar). material [Table 1]

[0235] method viscosity If desired, viscosity can be measured using a Physica MCR 301 Rheometer (Anton Paar, Graz, Austria) at 23°C under controlled shear rate using a cone / plate geometry CP25-1. The diameter is 25 mm, the cone angle is 1°, and the separation between the cone tip and the plate is 49 μm. The shear rate is 100 s -1 to 0.001 seconds -1 Logarithmically decrease the

[0236] Color value measurement (L * a * b * color coordinates) The device is calibrated using a white and black background as a reference. The sample is placed in front of the illumination. Then, L * a * b * The color coordinates and contrast ratio (opacity) are determined. * A positive b indicates yellow, while a negative b * The value indicates blue color.

[0237] Scanning Electron Microscopy (SEM) If desired, the microcapsule coating process can be further analyzed by SEM, for example using a device JSM 5400 (Hitachi).

[0238] mechanical stability If desired, the mechanical stability of the microcapsules can be determined as follows.

[0239] The microcapsules to be analyzed are filled with Sudan blue II (a blue dye) as described below. The filled microcapsules are then coated with a coating agent. A paste is then prepared, for example, using the following composition: 18 wt% TEGDMA, 20 wt% UDMA, 52.02 wt% glass filler, 8.0 wt% fumed silica, 0.1 wt% IC 819, and 0.46 wt% coated filled microcapsules.

[0240] The composition was then mixed using a commercially available speed mixer (e.g., SpeedMixer™ DAC150SP (Hauschild, Germany)) by applying the following conditions: 3 x 90 seconds, 2500 RPM and 3 x 20 seconds, 3500 RPM, and cooled to room temperature after each mixing step.

[0241] Light-cured discs are prepared from this composition: 700 mg of paste is loaded into a cylindrical mold (15 mm diameter, 1.5 mm height) placed between glass slides covered with transparent film. The sandwich is irradiated from both sides for 20 seconds (without a light guide) using an Elipar™ S10 light-curing device (3M Oral Care).

[0242] The sample is then removed from the mold and placed in a Visio™ Beta Vario light oven (3M Oral Care) equipped with vacuum for 7 minutes to fully light cure the sample.

[0243] Next, L * a * b * Determine the color coordinates. *If the value is positive, the blue color Sudan Blue II was apparently not released from the microcapsules during paste and disk preparation, which is an indication that the tested microcapsules are mechanically stable. * If the value is negative, the blue color Sudan Blue II was apparently released from the microcapsules during paste and disk preparation, which is an indication that the tested microcapsules are not mechanically stable.

[0244] A. Proof of Principle The blue dye Sudan II was used as a model substance because its release from the microcapsules can be easily followed visually or by colorimetry.

[0245] A1 Preparation of porous microcapsules Monomers SR339 (100 grams) and SR603OP (100 grams) obtained from Sartomer and sulfo-ethyl-methacrylate (10 grams) were mixed with Acclaim™ polyol PPG4200 (86 grams) and IRGACURE™ 819 (600 grams) obtained from Covestro. The mixture was vigorously stirred for 20 minutes. This mixture was then added to 1,200 grams of glycerol premixed with 36 g of surfactant APG325 obtained from Cognis Corporation. The mixture was sheared in a high shear mixer for 10 minutes. The mixture was then spread thinly between sheets of polyethylene terephthalate (PET) and heated at 5 mW / cm. 2The particles were cured with long-wave UVA at a light intensity of 1000 rpm for 15 minutes. The cured mixture was then dispersed in four bottles of isopropyl alcohol (300 mL) and centrifuged at 3,000 rpm. After removing the supernatant, the resulting particles were resuspended in four bottles containing 500 mL of isopropyl alcohol for a second rinse, followed by centrifugation. These particles were then suspended in four bottles containing 300 mL of isopropyl alcohol, shaken for 2 minutes, and centrifuged again. This extracted the PPG and left pores within the particles (Figures 1A and 2A). These microcapsules are designated MC1.

[0246] Filling of porous microcapsules with A2 Sudan II 4 g of Silquest™ A187 was mixed with 0.1 g of Sudan II. This liquid mixture was added to 20 g of porous microcapsules MC1 and rolled in a glass container for 2 hours. The microcapsules absorbed the active agent and retained it inside (Figure 1B). The resulting microcapsules are designated MC1-SD-C0.

[0247] A3 Coating of porous and filled microcapsules with pH-sensitive polymers The filled porous microcapsules MC1-SD-C0 were coated with a shell via spray drying. Spray drying was performed using a Buchi spray dryer, model B290, with an inlet temperature range of 55-60°C. The experiments were carried out using the following coating agents:

[0248] Microcapsules filled with Sudan II and coated with Kollicoat™ Smartseal 30D are designated MC1-SD-C1. Uncoated microcapsules filled with Sudan II are designated MC1-SD-C0.

[0249] Microcapsules containing a dye as the active agent and coated with a pH-sensitive shell are shown in Figure 1C.

[0250] B. Paste Composition Paste A1 and A2 Pastes A1 and A2 were prepared by weighing out the respective compounds. For better comparison, different weight percentages of MC1-SD-C0 and MC1-SD-C1 were weighed out to obtain the same amount of Sudan II in both pastes A1 and A2. The mixtures were mixed using a commercially available SpeedMixer™ DAC150SP (Hauschild, Germany) by applying 3 x 90 seconds at 2500 RPM and 3 x 20 seconds at 3500 RPM (cooling to room temperature after each mixing step). [Table 2]

[0251] Paste B Paste B1 was prepared by weighing each compound, and then the mixture was mixed using a commercially available SpeedMixer™ DAC150SP (Hauschild, Germany) by applying 3 x 90 seconds at 2500 RPM and 2 x 60 seconds at 3500 RPM (cooling to room temperature after each mixing step). [Table 3]

[0252] B1 Preparation of light-cured samples of pastes A1 and A2 700 mg of Paste Ax was loaded into a cylindrical mold (15 mm diameter, 1.5 mm height) placed between glass slides covered with transparent film. This sandwich structure was irradiated from both sides for 20 seconds (without a light guide) using an Elipar™ S10 light-curing device (3M Oral Care). The sample was then removed from the mold and placed in a Visio™ Beta Vario light oven (3M Oral Care) with vacuum for 7 minutes to fully light-cure the sample and remove the inhibitory layer.

[0253] The cured samples were further analyzed for their color values, and the results are shown below (Table 4). [Table 4]

[0254] Both pastes A1 and A2 contain the same amount of dye Sudan II, but their b * There are differences in value and appearance. Paste A1 has a b of 3.7. * Paste A2 had a b value of -3.2 and appeared slightly yellow. * value and appeared blue.

[0255] Clearly, the coating of the porous Sudan II-containing cores survives the rate mixing process, delivering uniformly encapsulated coated microcapsules as confirmed by SEM photographs (Figure 1C).

[0256] B2 Preparation of photocured samples of pastes A1-A2 and B1 420 mg of Paste Ax was mixed with 300 mg of Paste B1 by hand on a mixing pad for 30 seconds with the aid of a spatula (mixing ratio 1.4:1.0). The mixture was then loaded into a cylindrical mold (15 mm diameter, 1.5 mm height) placed between glass slides covered with transparent film. This sandwich-like structure was irradiated from both sides for 20 seconds (without a light guide) using an Elipar™ S10 light-curing device (3M Oral Care). The sample was then removed from the mold and placed in a Visio™ Beta Vario light oven (3M Oral Care) equipped with vacuum for 7 minutes to fully light-cure the sample and remove the inhibitory layer.

[0257] The samples of Examples 1 and 2 were prepared by mixing Pastes A1-A2 with Paste B1 and photocuring as described below. [Table 5]

[0258] When Pastes A1 and A2 were mixed with Paste B1, the b* values ​​of Examples 1 and 2 decreased. A color shift from yellow to blue was observed, demonstrating that the pH-sensitive polymer of MC-SD-C1 (in Paste A1) reacted with the acidic paste to release the blue dye Sudan II.

[0259] C. Porous microcapsules filled with ascorbic acid The general principle of the preparation of microcapsules containing a reducing agent (e.g., ascorbic acid or its derivatives) and coated with a shell of acid-sensitive material is illustrated in Figures 2jA-C. Microcapsules were prepared as described above. The resulting microcapsules are shown in Figure 2A.

[0260] Filling porous microcapsules with ascorbic acid 5 g of ascorbic acid was dissolved in 30 g of demineralized water. Loading was achieved by dropping the ascorbic acid-containing solution onto 30 g of porous polymer particles MC1. The particles absorbed the ascorbic acid-containing solution. The solvent was then removed by drying at room temperature. These microcapsules are designated MC1-AA-C0 and are shown in Figure 2B.

[0261] Microcapsule coating The filled porous microcapsules MC1-AA-C0 were coated with a coating agent by spray drying to form a shell on the microcapsules. The coating agent used was Eudragit™ EPO. Spray drying was performed using a laboratory-scale spray dryer, model B290, from Buchi, with an inlet temperature range of 55°C to 60°C. g The coating was carried out at a temperature around 1000 K. The microcapsules shown in Figure 2C were obtained. The coated microcapsules are designated MC1, AA, and C2, respectively.

[0262] Extraction of porous microcapsules (uncoated) 0.2 wt% of the loaded microcapsules, MC1-AA-C0, were dispersed in 0.2 M H3PO4 in water using a VORTEX™ mixer. The mixture was then subjected to ultrasonic treatment, centrifuged, and filtered to obtain a solution containing the extracted ascorbic acid derivatives. The sample solution was then injected into an HPLC system to determine the concentration of ascorbic acid.

[0263] Findings: The determined amount of ascorbic acid was very close to the theoretical amount, demonstrating that the microcapsules described herein can be reliably loaded with reactive ingredients. The present invention includes the following aspects. (1) a hollow or porous core composed of a polymeric material and containing components of a redox initiator system, and a shell composed of a pH-sensitive material; A microcapsule comprising: (2) The microcapsule according to item 1, wherein the polymeric material of the hollow or porous core comprises a (meth)acrylate. (3) The porous or hollow core has the following characteristics: having a spherical shape; having a diameter in the range of 1 to 200 μm; having a pore size of 10 to 200 nm; Mechanically stable 3. Microcapsules according to item 1 or 2, characterized by one or a combination of: (4) The shell has the following characteristics: Thickness: 0.1~5μm; covering more than 85% of the surface of said porous or hollow core; Soluble in acidic or basic components 4. The microcapsules according to any one of items 1 to 3, characterized by any one of the following, alone or in combination: (5) The microcapsules according to any one of items 1 to 4, wherein the pH-sensitive material is a polymer, in particular, a polymer comprising a copolymer of methyl (meth)acrylate and diethylaminoethyl (meth)acrylate, a copolymer of methyl (meth)acrylate, butyl methacrylate and dimethylaminoethyl (meth)acrylate, cellulose acetate phthalate, sodium carboxymethylcellulose, hydroxypropylmethylcellulose phthalate, polyvinyl acetate phthalate, a copolymer of methacrylic acid and methyl (meth)acrylate, a copolymer of methacrylic acid and alkyl (meth)acrylate, a copolymer of methacrylic acid, methyl (meth)acrylate and methyl acrylate, or a mixture thereof. (6) The microcapsules according to any one of items 1 to 5, wherein the component of the redox initiator system is selected from a reducing agent or an oxidizing agent. (7) The microcapsules according to item 6, wherein the component of the redox initiator system is a reducing agent selected from an ascorbic acid component, a tertiary amine component, a sulfinate component, a sulfite component, a borane component, a (thio)urea component, a (thio)barbituric acid component, saccharin, and metal salts thereof. (8) The microcapsules according to item 6, wherein the component of the redox initiator system is an oxidizing agent selected from organic and inorganic peroxides, preferably hydroperoxides, ketone peroxides, diacyl peroxides, dialkyl peroxides, peroxyketals, peroxyesters, and peroxydicarbonates, persulfate components, and mixtures thereof. (9) A kit of parts including a catalyst paste and a base paste, The catalyst paste 9. The microcapsules according to any one of items 1 to 8, which contain a first component of a redox initiator system, The base paste is an acidic or basic component; a second component of said redox initiator system. (10) The base paste containing an acidic component has the following characteristics: pKa value: less than 5; comprising an acidic moiety selected from a sulfonic acid, sulfinic acid, phosphoric acid, phosphonic acid, phosphinic acid, or carboxylic acid moiety; Containing one or more polymerizable moieties 10. The kit of parts according to item 9, characterized by any one or combination of the following: (11) The catalyst paste The microcapsules according to any one of items 1 to 7, which contain a reducing agent; a curable non-acidic (meth)acrylate component; and Filler and optionally a photoinitiator; The base paste B is An acidic component, a curable (meth)acrylate component; and Filler and an oxidizing agent; optionally a transition metal component; the reducing component and the oxidizing agent form a redox initiator system for curing the curable (meth)acrylate component. 11. The kit of parts according to item 9 or 10, characterized in that (12) A method for producing pH-sensitive core-shell microcapsules according to any one of items 1 to 8, comprising: providing particles having a hollow or porous core and components of a redox initiator system; imbibing the particles with the components of the redox initiator system; coating the particles containing the absorbed components of the redox initiator system with a pH-sensitive coating material. (13) The coating step preferably comprises spray drying the pH-sensitive coating material to a glass transition temperature T g Item 13. The method according to item 12, wherein the method is carried out in accordance with item 13. (14) A method for curing a curable composition, comprising: A step of preparing a catalyst paste containing the microcapsules according to any one of items 1 to 8 and a base paste containing an acidic or basic component, either the catalyst paste or the base paste, or the catalyst paste and the base paste, comprises a curable component; mixing the catalyst paste with the base paste. (15) Use of microcapsules according to any of items 1 to 8 for producing a hardenable composition comprising a redox initiator system, in particular a dental or orthodontic composition such as a dental or orthodontic cement, adhesive or filling material.

Claims

1. a hollow or porous core constructed from a polymeric material; a reducing agent or an oxidizing agent; a shell comprised of an acid-sensitive material; A microcapsule comprising: the acid-sensitive material is characterized by being ionic in a composition having a pH value of 1 to 4; the reducing agent or the oxidizing agent is encapsulated in the hollow or porous core; the shell at least partially covers a surface of the polymeric material; The microcapsules are characterized by a diameter of 1 to 200 μm.

2. The microcapsule of claim 1 , wherein the polymeric material comprises the polymerization product of a polymerizable monomer having a (meth)acrylate moiety.

3. The porous or hollow core has the following characteristics: having a spherical shape; Pore ​​diameter of 10 to 200 nm 2. The microcapsules of claim 1, characterized by:

4. The shell has the following characteristics: Thickness: 0.1-5 μm; covering more than 85% of the surface of said polymeric material; Soluble in acidic components 2. The microcapsules of claim 1, characterized by:

5. 2. The microcapsule of claim 1, wherein the acid-sensitive material is a polymer comprising a copolymer of methyl (meth)acrylate and diethylaminoethyl (meth)acrylate, a copolymer of methyl (meth)acrylate, butyl methacrylate and dimethylaminoethyl (meth)acrylate, or a combination thereof.

6. 2. The microcapsule of claim 1, wherein the reducing agent is selected from ascorbic acid moieties, tertiary amine moieties, sulfinate moieties, sulfite moieties, borane moieties, (thio)urea moieties, and (thio)barbituric acid moieties, saccharin, and metal salts thereof.

7. 2. The microcapsules of claim 1, wherein the oxidizing agent is selected from organic and inorganic peroxides, preferably hydroperoxides, ketone peroxides, diacyl peroxides, dialkyl peroxides, peroxyketals, peroxyesters, and peroxydicarbonates, persulfate components, and mixtures thereof.

8. A kit of parts including a catalyst paste and a base paste, The catalyst paste The microcapsules according to any one of claims 1 to 7 are contained therein, The base paste is an acidic or basic component; a reducing agent or an oxidizing agent.

9. The base paste containing an acidic component has the following characteristics: pKa value: less than 5; comprising an acidic moiety selected from a sulfonic acid, sulfinic acid, phosphoric acid, phosphonic acid, phosphinic acid, or carboxylic acid moiety; Containing one or more polymerizable moieties 9. The kit of parts of claim 8, characterized by the following, alone or in combination:

10. The catalyst paste the microcapsules having a reducing agent within the hollow or porous core; a curable non-acidic (meth)acrylate component; and Filler and optionally a photoinitiator; The base paste is An acidic component, a curable (meth)acrylate component; and Filler and an oxidizing agent; optionally a transition metal component; the reducing agent and the oxidizing agent form a redox initiator system for curing the curable (meth)acrylate component.

9. The kit of parts of claim 8, characterized by:

11. A method for producing the microcapsules according to any one of claims 1 to 7, Providing a polymeric material having a hollow or porous core; providing a reducing agent or an oxidizing agent; allowing the polymeric material to absorb the reducing agent or the oxidizing agent within the hollow or porous core; coating the polymeric material containing the reducing agent or the oxidizing agent within the hollow or porous core with an acid sensitive material.

12. 12. The method of claim 11, wherein the coating step is carried out by spray drying at the glass transition temperature, Tg, of the acid-sensitive coating material.

13. 1. A method for curing a curable composition, comprising: Preparing a catalyst paste containing the microcapsules according to any one of claims 1 to 7; providing a base paste including an acidic component and a reducing or oxidizing agent; mixing the catalyst paste with the base paste; wherein one or both of the catalyst paste and the base paste comprises a curable component.

14. Use of microcapsules according to any one of claims 1 to 7 for the preparation of a redox-curable composition.

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