Thickener comprising pullulan derivative, and cosmetic comprising the same

Abstract

To provide a novel thickener primarily derived from renewable sources, exhibiting superior thickening effects and shear-thinning properties.SOLUTION: The present invention provides a thickener comprising a pullulan derivative that has an acidic functional group represented by a following formula (a1) and / or a salt thereof. (In the formula (a1), A1 represents an optionally substituted, saturated or unsaturated alkylene group, and * represents a binding site to pullulan).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a thickening agent, and more particularly to a thickening agent containing a pullulan derivative. [Background technology]

[0002] Thickeners are essential cosmetic ingredients for cosmetics of all viscous forms, such as lotions, gels, creams, emulsions, and liquids. Thickeners dissolve in various solvents that make up cosmetics, such as water, alcohol, or a mixture of water and alcohol, and exhibit a thickening effect that increases the viscosity. They also impart shear-thinning properties, which reversibly reduce the viscosity when stress is applied, thereby imparting excellent usability and feel to cosmetics. Shear-thinning properties are an element that affects the feel when the formulation is pushed out of a tube-shaped container or when the formulation is spread on the skin, and are particularly important for thickeners for cosmetics.

[0003] The thickener currently most widely used as a cosmetic raw material is carboxyvinyl polymer (cosmetic label name: carbomer). Carboxyvinyl polymers are commercially available under trade names such as Hiviswako (registered trademark) (Fujifilm Wako Pure Chemical Industries, Ltd.) and Carbopol (registered trademark) (Lubrizol Corporation), and are incorporated into various cosmetics due to their excellent thickening and shear-thinning properties. However, carboxyvinyl polymers have issues with salt resistance, and there is an issue that the viscosity drops rapidly when mixed with salt or ionic raw materials (e.g., Patent Documents 1 and 2).

[0004] In recent years, in all industrial fields, there has been a demand to reduce the dependence on fossil resources derived from petroleum and to switch from fossil resources to renewable resources such as organic resources derived from living organisms. This is also true for cosmetic raw materials, and there is a strong demand for renewable cosmetic raw materials. As mentioned above, the most commonly used thickening agent at present is carboxyvinyl polymer, but at the current technological level, carboxyvinyl polymer is an artificial synthetic polymer made from petroleum resources, and it must be said that it is difficult to obtain it from natural resources in a renewable manner.

[0005] On the other hand, known thickeners based on natural polymers that do not depend on fossil resources include xanthan gum, guar gum, locust bean gum, etc. Although these natural polymer thickeners exhibit shear-thinning properties, they have a problem in that they have a relatively low viscosity and must be blended in large amounts to obtain a sufficiently high viscosity (e.g., Non-Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-68023 A [Patent Document 2] Patent No. 6805316 [Non-patent literature]

[0007] [Non-Patent Document 1] Satis Pharmaceutical Co., Ltd., "Development technology for water-soluble viscous cosmetics using natural polymers", Satis Pharmaceutical Co., Ltd. website, [Retrieved August 14, 2023], Internet,<URL:https: / / www.saticine-md.co.jp / rd / gel> Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above-mentioned conventional techniques, and an object of the present invention is to provide a new thickener that exhibits excellent thickening effect and shear-thinning properties and is obtained primarily from renewable raw materials. [Means for solving the problem]

[0009] In the course of intensive research efforts to solve the above problems, the inventors prepared a pullulan derivative having acidic functional groups by condensing pullulan, a type of water-soluble polysaccharide produced by microorganisms, with a dicarboxylic acid having a specific structure. They then surprisingly found that the pullulan derivative having acidic functional groups exhibited a thickening property far superior to that of pullulan itself, and that an aqueous solution of this pullulan derivative had a shear-thinning property that was not observed in an aqueous solution of pullulan itself.

[0010] That is, in one aspect, the present invention solves the above-mentioned problems by providing a thickener containing a pullulan derivative having an acidic functional group represented by the following formula (a1) and / or a salt thereof.

[0011] [ka]

[0012] In the above formula (a1), A1 represents an optionally substituted saturated or unsaturated alkylene group, and * represents a bond to pullulan. The bond to pullulan represented by * is typically a bond to a group obtained by removing a hydrogen atom from a hydroxyl group of pullulan.

[0013] In a preferred embodiment, the acidic functional group contained in the pullulan derivative may be a group represented by the following formula (a4) derived from succinic acid and / or a succinic acid derivative, and more preferably a group represented by the following formula (a6) derived from succinic acid and / or a succinic acid derivative.

[0014] [ka]

[0015] [ka]

[0016] In the above formulas (a4) and (a6), R 1 R each independently represents a hydrogen atom or an optionally substituted saturated or unsaturated alkyl group, and * represents a bond to pullulan. The saturated or unsaturated alkyl group may be an alkyl group, an alkenyl group, and / or an alkynyl group. 1 The number of carbon atoms in the saturated or unsaturated alkyl group represented by the formula (I) is not particularly limited, and the number of carbon atoms may be, for example, 1 to 20, preferably 2 to 16, more preferably 3 to 14, even more preferably 4 to 12, still more preferably 6 to 10, and most preferably 8.

[0017] Furthermore, in the course of further intensive research efforts, the inventors have surprisingly found that pullulan derivatives obtained by condensing pullulan with octenylsuccinic acid, which is a type of succinic acid derivative represented by the above formulas (a4) and (a6), exhibit a particularly excellent thickening effect when used as a salt with a divalent or higher metal ion.

[0018] That is, in a preferred embodiment, the present invention solves the above-mentioned problem by providing a thickener containing a pullulan derivative and / or a salt thereof having a group represented by the following formula (a19) derived from octenylsuccinic acid.

[0019] [ka]

[0020] In the above formula (a19), * represents the bond with pullulan.

[0021] As described above, according to the findings of the present inventors, the above pullulan derivatives, particularly those having a group represented by the above formula (a19) derived from octenylsuccinic acid, can exhibit a particularly excellent thickening effect when used as a salt with a divalent or higher metal ion. That is, in a preferred embodiment, the thickener according to one aspect of the present invention can be a thickener containing a salt of the above pullulan derivative, particularly those having a group represented by the above formula (a19) derived from octenylsuccinic acid, and a divalent or higher metal ion. In order to obtain an excellent thickening effect, it is considered that the above pullulan derivative and a divalent or higher metal ion should coexist at the time of use. Therefore, in order to obtain an excellent thickening effect, not only the above pullulan derivative can be made into a salt form in advance and used as a thickening agent, but also the above pullulan derivative can be used in a formulation containing a divalent or higher metal ion so that the above pullulan derivative and a salt of the divalent or higher metal ion are formed at the time of use. That is, in another aspect, the present invention also provides a thickening method characterized by coexisting the above pullulan derivative, particularly the pullulan derivative having a group represented by the above formula (a19) derived from octenylsuccinic acid, with a divalent or higher metal ion. The thickening method can be suitably used to thicken not only cosmetics but also various products such as quasi-drugs, pharmaceuticals, and food and beverage products.

[0022] Although there is no particular limitation on the type of divalent or higher metal ion that forms a salt with the pullulan derivative, calcium ion, magnesium ion, or aluminum ion is preferred, and aluminum ion is particularly preferred. That is, in a preferred embodiment, the thickener according to one aspect of the present invention may be a thickener containing a calcium salt, magnesium salt, or aluminum salt of the pullulan derivative, and particularly preferably a thickener containing an aluminum salt of the pullulan derivative.

[0023] Furthermore, in the course of further intensive research efforts, the inventors prepared an ambidextrous pullulan derivative in which a predetermined ratio of diethylaminoethyl groups were introduced as basic functional groups into a pullulan derivative having a group derived from succinic acid as an acidic functional group, and upon investigating the viscosity and shear thinning properties of an aqueous solution of this ambidextrous pullulan derivative, they surprisingly found that it exhibited a significantly superior thickening effect exceeding that of pullulan, and a shear thinning property not observed in pullulan.

[0024] That is, in one aspect, the present invention also provides a thickener containing an amphoteric pullulan derivative having an acidic functional group and a basic functional group, which is any one of the above-mentioned pullulan derivatives. The basic functional group may be a basic functional group represented by the following formula (b1).

[0025] [ka]

[0026] In the above formula (b1), R 2 are each independently a hydrogen atom or an optionally substituted saturated or unsaturated alkyl group, and n is 2 or 3. 2 may be the same or different. r represents the valence of the nitrogen atom and is 0 or 1. R 3 is an optionally substituted saturated or unsaturated alkylene group. * represents a bond with pullulan, typically a bond with a group obtained by removing a hydrogen atom from a hydroxyl group of pullulan. In a preferred embodiment, the basic functional group represented by the above formula (b1) may be a diethylaminoethyl group as shown in the experimental example described below. According to the findings of the present inventors, a bipolar pullulan derivative having a group derived from succinic acid as an acidic functional group and a diethylaminoethyl group as a basic functional group in a predetermined ratio can exhibit a particularly excellent thickening effect. Effect of the Invention

[0027] According to the present invention, a new thickening agent is provided which has excellent thickening and shear-thinning properties in aqueous solvents and is obtained primarily from renewable raw materials. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 shows a synthesis scheme of pullulan having a group derived from octenylsuccinic acid as an acidic functional group (OSA pullulan). [Diagram 2] FIG. 1 shows the results of 1H NMR analysis of OSA pullulan aluminum salt. [Diagram 3] FIG. 1 shows the viscosity measurement results of aqueous solutions of OSA pullulan sodium salt, calcium salt, and aluminum salt in comparison with the viscosity measurement result of an aqueous pullulan solution. [Figure 4] FIG. 2 is a graph showing the results of viscosity measurement of an aqueous solution of OSA pullulan aluminum salt in comparison with the results of viscosity measurement of an aqueous solution of a carboxyvinyl polymer. [Diagram 5] FIG. 1 is a diagram showing a synthesis scheme of pullulan having a group derived from succinic acid as an acidic functional group and a diethylaminoethyl group as a basic functional group (DEAE / SA pullulan). [Figure 6] FIG. 1 shows the results of 1H NMR analysis of DEAE / SA pullulan 1. [Figure 7] FIG. 1 shows the results of 1H NMR analysis of DEAE / SA pullulan 2. [Figure 8] FIG. 1 shows the viscosity measurement results of aqueous solutions of DEAE / SA pullulan 1 and DEAE / SA pullulan 2 in comparison with the viscosity measurement results of an aqueous pullulan solution. [Figure 9] FIG. 1 shows a synthesis scheme of pullulan having a group derived from succinic acid as an acidic functional group (SA pullulan). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] A thickener according to one aspect of the present invention is a thickener containing a pullulan derivative and / or a salt thereof.

[0030] <Pullulan> Pullulan is a water-soluble polysaccharide whose basic unit is a maltotriose structure in which three glucose molecules are linked together via α-1,4 bonds, as represented by the following formula (1), and this basic unit is linked together via α-1,6 bonds.

[0031] [ka]

[0032] Pullulan is typically produced by culturing a microorganism capable of producing pullulan in a medium containing a carbon source including sucrose, glucose, maltose, etc., and isolating and purifying pullulan from the resulting culture. For example, Aureobasidium pullulans, a type of filamentous fungus, is known as a microorganism capable of producing pullulan, and a method for producing pullulan using Aureobasidium pullulans is described, for example, in International Publication No. WO2011 / 158936. Pullulan used as a raw material for pullulan derivatives in this way can be produced based on biological resources.

[0033] There is no particular limitation on the origin or manufacturing method of pullulan used as a raw material for the pullulan derivative contained in the thickener according to one aspect of the present invention, but from the viewpoints of availability and quality, commercially available pullulan can be preferably used. As commercially available pullulan, for example, food additive grade pullulan (product name "Pullulan (Food Additive)"), cosmetic grade pullulan (product name "Cosmetic Pullulan"), pharmaceutical grade pullulan (product name "Japanese Pharmacopoeia Pullulan"), etc., manufactured and sold by Hayashibara Co., Ltd., can be preferably used, but are not limited to these.

[0034] There are no particular limitations on the molecular weight or molecular weight distribution of pullulan used as a raw material for the pullulan derivative contained in the thickener according to one aspect of the present invention, and an appropriate molecular weight can be adopted depending on the target viscosity, etc., and the molecular weight can be, for example, 5,000 Da or more, preferably 10,000 Da or more and 1,000,000 Da or less, and more preferably 50,000 Da or more and 500,000 Da or less.

[0035] In one aspect of the present invention, the above-mentioned pullulan can be used as a thickener by appropriately derivatizing it. In this specification, the pullulan derivative means a modified pullulan obtained by introducing an acidic functional group and / or a basic functional group, which will be described below, into the pullulan molecule.

[0036] <Acidic functional group> The pullulan derivative contained in the thickener according to one aspect of the present invention is a pullulan derivative having an acidic functional group. In this specification, the acidic functional group means a functional group that has a dissociable hydrogen atom and can react with a basic substance or a basic functional group, such as a carboxylic acid group, a sulfonic acid group, or a phosphoric acid group. In this specification, the term "having an acidic functional group" includes both a case in which only an acidic functional group is present as a substituent, and a case in which other substituents are also present, such as a basic functional group described below.

[0037] In a preferred embodiment, the pullulan derivative contained in the thickener according to one aspect of the present invention preferably has a carboxylic acid group as an acidic functional group, and more preferably has an acidic functional group represented by the following formula (a1).

[0038] [ka]

[0039] In the above formula (a1), A1 represents an optionally substituted saturated or unsaturated alkylene group, and * represents the bond to pullulan.

[0040] An alkylene group is a divalent substituent formed by removing two hydrogen atoms from a straight-chain alkane, and has the general formula (-(CH2) n -), and specific examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. The number of carbon atoms in the alkylene group is not particularly limited, and may be, for example, 1 to 20, preferably 1 to 10, more preferably 2 to 5, even more preferably 2 to 3, and even more preferably 2.

[0041] In the above formula (a1), the saturated or unsaturated alkylene group represented by A1 may be substituted. "May be substituted" includes both cases where the substitutable hydrogen atoms constituting the group are not substituted and cases where they are substituted. When the substitutable hydrogen atoms are not substituted, it means that all the substitutable hydrogen atoms are hydrogen atoms. On the other hand, when the substitutable hydrogen atoms are substituted, it means that the substitutable hydrogen atoms are substituted with a substituent other than a hydrogen atom. Examples of the substituent include, but are not limited to, halogen, hydroxyl group, alkyl group, alkenyl group, alkynyl group, acetyl group, cycloalkyl group, halogenated alkyl group, haloalkyl group, hydroxyalkyl group, alkoxy group, haloalkoxy group, amino group, nitro group, cyano group, carboxyl group, etc. The number of the substituents may be multiple, and when there are multiple substituents, the multiple substituents may be the same or different.

[0042] On the other hand, the bond with pullulan represented by "*" can typically be a bond with a group obtained by removing a hydrogen atom from a hydroxyl group of pullulan. In other words, the above-mentioned acidic functional group is typically bonded to pullulan via an ester bond formed by condensation of a hydroxyl group and a carboxyl group of pullulan.

[0043] Those skilled in the art can introduce the acidic functional group represented by the above formula (a1) into pullulan by a suitable method. The simplest method is, for example, to subject pullulan to dehydration condensation with a dicarboxylic acid represented by the following formula (a2), as shown in the experimental example described later.

[0044] [ka]

[0045] In the above formula (a2), A1 is an optionally substituted saturated or unsaturated alkylene group, as described above for formula (a1).

[0046] In addition, when the acidic functional group represented by the above formula (a1) is introduced into pullulan, the acidic functional group may be introduced into pullulan by reacting the acid anhydride of the dicarboxylic acid represented by the above formula (a2) with pullulan. The acid anhydride of the dicarboxylic acid represented by the above formula (a2) can be represented, for example, by the following formula (a3).

[0047] [ka]

[0048] Specific examples of such dicarboxylic acids or anhydrides thereof may include, but are not limited to, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, malic acid, octenylsuccinic acid, and acid anhydrides thereof.

[0049] In a preferred embodiment, A1 in the formula (a1) may be an optionally substituted ethylene group. More preferably, the acidic functional group represented by the formula (a1) may be a group derived from succinic acid and / or a succinic acid derivative. The group derived from succinic acid and / or a succinic acid derivative may be represented by the following formula (a4).

[0050] [ka]

[0051] In the above formula (a4), R 1 are each independently a hydrogen atom or an optionally substituted saturated or unsaturated alkyl group, and * represents a bond to pullulan. The bond to pullulan represented by * can typically be a bond to a group obtained by removing a hydrogen atom from a hydroxyl group of pullulan. In this specification, when multiple substituents are "independently", this means that the substituents may all be the same, may be different from each other, or may all be different.

[0052] In the above formula (a4), R 1 More specifically, the saturated or unsaturated alkyl group that can be represented by the formula (C n H 2n+1 )-). Examples of alkyl groups include, but are not limited to, methyl, ethyl, and propyl groups. An alkenyl group is a monovalent group formed by removing one hydrogen atom from a carbon atom that constitutes an alkene, and can be represented by the general formula ((C n H 2n-1 )-). Examples of alkenyl groups include, but are not limited to, vinyl and allyl groups. An alkynyl group is a monovalent group formed by removing one hydrogen atom from a carbon atom constituting an alkyne, and can be represented by the general formula ((C n H 2n-3 )-). Examples of alkynyl groups include, but are not limited to, ethynyl and propargyl groups. The alkyl, alkenyl, or alkynyl groups may be linear or branched, but are preferably linear.

[0053] Also, R 1The number of carbon atoms in the saturated or unsaturated alkyl group that can be represented by the formula (I) is not particularly limited, and may be, for example, 1 to 20, preferably 2 to 18, more preferably 3 to 16, even more preferably 4 to 14, still more preferably 6 to 12, and most preferably 8.

[0054] Those skilled in the art can introduce the acidic functional group represented by the above formula (a4) into pullulan by a suitable method. The simplest method is, for example, to condense pullulan with succinic anhydride or anhydride of a succinic acid derivative represented by the following formula (a5), as shown in the experimental example described below. It goes without saying that succinic acid or a succinic acid derivative not in the form of an acid anhydride may be condensed with pullulan.

[0055] [ka]

[0056] In the above formula (a5), R 1 each independently represents a hydrogen atom or an optionally substituted saturated or unsaturated alkyl group, as described above for formula (a4).

[0057] In a preferred embodiment, the acidic functional group derived from succinic acid and / or a succinic acid derivative may be a group represented by the following formula (a6) derived from succinic acid and / or a succinic acid derivative:

[0058] [ka]

[0059] In the above formula (a6), R 1 is a hydrogen atom or an optionally substituted saturated or unsaturated alkyl group. * represents a bond to pullulan, and typically may be a bond to a group obtained by removing a hydrogen atom from a hydroxyl group of pullulan.

[0060] Those skilled in the art can introduce the acidic functional group represented by the above formula (a6) into pullulan by a suitable method. The simplest method is, for example, to condense pullulan with succinic anhydride or anhydride of a succinic acid derivative represented by the following formula (a7), as shown in the experimental example described below. As mentioned above, succinic acid or a succinic acid derivative not in the form of an acid anhydride may be condensed with pullulan.

[0061] [ka]

[0062] In the above formula (a7), R 1 represents a hydrogen atom or an optionally substituted saturated or unsaturated alkyl group, as described above for formula (a6).

[0063] Specific examples of the compound represented by the formula (a7) include succinic anhydride represented by the following formula (a8) (CAS number: 108-30-5), methylsuccinic anhydride represented by the following formula (a9) (CAS number: 4100-80-5), allylsuccinic anhydride represented by the following formula (a10) (CAS number: 7539-12-0), n-butylsuccinic anhydride represented by the following formula (a11) (CAS number: 2035-76-9), 2-buten-1-ylsuccinic anhydride represented by the following formula (a12) (CAS number: 7538-42-3), 2- Examples of the acid anhydride include, but are not limited to, hexen-1-yl succinic anhydride (CAS number: 10500-34-2), n-octyl succinic anhydride (CAS number: 4200-92-4) represented by the following formula (a14), 2-octen-1-yl succinic anhydride (CAS number: 42482-06-4) represented by the following formula (a15), n-dodecyl succinic anhydride (CAS number: 2561-85-5) represented by the following formula (a16), and 2-dodecen-1-yl succinic anhydride (CAS number: 19780-11-1) represented by the following formula (a17). These acid anhydrides may be prepared by oneself or may be commercially available.

[0064] [ka]

[0065] In a preferred embodiment, in the above formula (a6), R 1 may be a hydrogen atom. That is, in a preferred embodiment, the pullulan derivative contained in the thickener according to one aspect of the present invention may be a pullulan derivative having an acidic functional group represented by the following formula (a18). According to the findings of the present inventors, a pullulan derivative having an acidic functional group represented by the following formula (a18) exhibits an excellent thickening effect, and its aqueous solution exhibits shear-thinning properties, and therefore may be particularly preferably used as an active ingredient of a thickener. In the following formula (a18), * represents a bond with pullulan, as in the other acidic functional groups.

[0066] [ka]

[0067] On the other hand, in a preferred embodiment, in the above formula (a6), R 1 The group represented by R may be a saturated or unsaturated alkyl group. 1 The number of carbon atoms in the saturated or unsaturated alkyl group that can be represented by the formula (I) is not particularly limited, and may be, for example, 1 to 20. However, according to the findings of the present inventors, the number of carbon atoms is preferably 2 to 18, more preferably 3 to 15, even more preferably 4 to 12, still more preferably 6 to 10, and most preferably 8.

[0068] The saturated or unsaturated alkyl group having 8 carbon atoms may be, for example, an octyl group, an octenyl group, or an octynyl group, but is particularly preferably an octenyl group. That is, in a preferred embodiment, the group derived from succinic acid and / or a succinic acid derivative may be a group represented by the following formula (a19) derived from octenylsuccinic acid. The group represented by the following formula (a18) derived from octenylsuccinic acid can be produced, for example, by condensing 2-octen-1-ylsuccinic anhydride represented by the above formula (a15) with pullulan, as shown in the experimental example described later.

[0069] [ka]

[0070] In the above formula (a19), * represents a bond to pullulan, and typically may be a bond to a group obtained by removing a hydrogen atom from a hydroxyl group of pullulan.

[0071] According to the findings of the present inventors, the pullulan derivatives having the acidic functional groups described above, particularly the pullulan derivatives having a group represented by the above formula (a19) derived from octenylsuccinic acid, can exhibit a particularly excellent thickening effect when in the form of a salt with a divalent or higher metal ion. That is, in a preferred embodiment, the thickener according to one aspect of the present invention can be a thickener containing the pullulan derivative in the form of a salt, and the salt can be preferably a salt of the pullulan derivative and a divalent or higher metal ion.

[0072] There is no particular limitation on the type of divalent or higher metal ion, but calcium ion, magnesium ion, or aluminum ion is preferred, calcium ion or aluminum ion is more preferred, and aluminum ion is even more preferred. In other words, in a preferred embodiment, the thickener according to one aspect of the present invention is preferably a calcium salt, magnesium salt, or aluminum salt of the pullulan derivative, more preferably a calcium salt or aluminum salt, and particularly preferably an aluminum salt. The effect of the pullulan derivative, which can exert a remarkable thickening effect as a salt, particularly a salt with a divalent or higher metal ion, in other words, can exert a remarkable thickening effect in an environment where a divalent or higher metal ion may be generated, is extremely advantageous and distinguishes it from carboxyvinyl polymers, which have been widely used as thickeners for cosmetics and have been problematic in terms of salt resistance.

[0073] The degree of substitution of the acidic functional group in the pullulan derivative used in the thickener according to one aspect of the present invention is not particularly limited, but may be, for example, 0.001 to 1, preferably 0.001 to 0.50, more preferably 0.001 to 0.10, even more preferably 0.005 to 0.050, and even more preferably 0.010 to 0.045. The degree of substitution of the acidic functional group refers to the number of acidic functional groups substituted per glucose residue constituting the pullulan derivative. The degree of substitution can be measured by a known method such as colloid titration or NMR.

[0074] <Basic functional group> In a preferred embodiment, the pullulan derivative contained in the thickener according to one aspect of the present invention may further have a basic functional group. That is, in a preferred embodiment, the pullulan derivative contained in the thickener according to one aspect of the present invention may be an amphoteric pullulan derivative having both an acidic functional group and a basic functional group in one molecule. In this specification, a basic functional group means a functional group, such as an amino group, that can accept a hydrogen atom and react with an acidic substance or an acidic functional group.

[0075] In a preferred embodiment, the basic functional group contained in the pullulan derivative contained in the thickener according to one aspect of the present invention may be an optionally substituted aminoalkyl group, monoalkylaminoalkyl group, dialkylaminoalkyl group, or trialkylaminoalkyl group. In other words, the basic functional group may be a basic functional group represented by the following formula (b1):

[0076] [ka]

[0077] In the above formula (b1), R 2 are each independently a hydrogen atom or an optionally substituted saturated or unsaturated alkyl group, and n is 2 or 3. 3 is an optionally substituted alkylene group. * represents a bond to pullulan, and typically may be a bond to a group obtained by removing a hydrogen atom from a hydroxyl group of pullulan.

[0078] On the other hand, in the above formula (b1), r represents the valence of the nitrogen atom and is 0 or 1. More specifically, in the above formula (b1), when n is 2, the valence r of the nitrogen atom is 0, and when n is 3, the valence r of the nitrogen atom is 1. In other words, the basic functional group represented by the above formula (b1) includes aminoalkyl groups, monoalkylaminoalkyl groups, dialkylaminoalkyl groups, and trialkylaminoalkyl groups represented by the following formulae (b2) to (b5).

[0079] [ka]

[0080] In the above formulas (b2) to (b5), R 2 are each independently an optionally substituted saturated or unsaturated alkyl group; R 3 is an optionally substituted alkylene group. * represents a bond to pullulan, and typically may be a bond to a group obtained by removing a hydrogen atom from a hydroxyl group of pullulan.

[0081] In the above formula (b1) and the above formulas (b2) to (b5), R 2 The number of carbon atoms in the alkyl group represented by the formula (I) is not particularly limited, but may be, for example, 1 to 6, preferably 1 to 4, more preferably 1 to 3, and particularly preferably 2. 3 The number of carbon atoms in the alkylene group represented by the following formula (I) is not particularly limited, and may be, for example, 1 to 6, preferably 1 to 4, more preferably 1 to 3, and particularly preferably 2.

[0082] More specific examples of the basic functional group represented by the above formula (b1) or the above formulae (b2) to (b5) include, but are not limited to, aminoalkyl groups such as an aminoethyl group, an aminopropyl group, and an aminobutyl group; dialkylaminoalkyl groups such as a dimethylaminoethyl group, a diethylaminoethyl group, a diisopropylaminoethyl group, a dimethylaminopropyl group, a diethylaminopropyl group, and a diisopropylaminopropyl group; and trialkylaminoalkyl groups such as a trimethylaminoethyl group, a triethylaminoethyl group, a trimethylaminopropyl group, and a triethylaminopropyl group.

[0083] On the other hand, according to the findings of the present inventors, in a preferred embodiment, the basic functional group of the pullulan derivative according to one aspect of the present invention is particularly preferably a diethylaminoethyl group represented by the following formula (b6): As shown in the experimental examples described later, for example, an amphoteric pullulan derivative having a diethylaminoethyl group represented by the following formula (b6) as the basic functional group and a group represented by the above formula (a18) derived from succinic acid as the acidic functional group can exhibit particularly excellent thickening effect and shear thinning properties.

[0084] [ka]

[0085] In the above formula (b6), * represents a bond to pullulan, and typically may be a bond to a group obtained by removing a hydrogen atom from a hydroxyl group of pullulan.

[0086] Those skilled in the art can introduce the basic functional group represented by the above formula (b6) into pullulan by a suitable method. For example, as shown in the experimental example described later, a compound represented by the following formula (b7) having a halogenated alkyl group may be reacted with pullulan in the presence of a strong alkali.

[0087] [ka]

[0088] In the above formula (b7), X represents a halogen atom and can be, for example, Cl, Br, or I.

[0089] The degree of substitution of the basic functional group in the pullulan derivative used in the thickener according to one aspect of the present invention is not particularly limited, but may be, for example, 0.001 to 1, preferably 0.001 to 0.50, more preferably 0.001 to 0.10, even more preferably 0.001 to 0.050, and even more preferably 0.001 to 0.020. The degree of substitution of the basic functional group refers to the number of basic functional groups substituted per glucose residue constituting the pullulan derivative. The degree of substitution can be measured by a known method such as colloid titration or NMR.

[0090] In addition, when the pullulan derivative used in the thickener according to one aspect of the present invention is a bipolar pullulan derivative having a basic functional group in addition to an acidic functional group, there is no particular limitation on the ratio of the degree of substitution of the basic functional group to the degree of substitution of the acidic functional group, but the degree of substitution of the basic functional group is preferably equal to or less than the degree of substitution of the acidic functional group, and more preferably less than the degree of substitution of the acidic functional group. In terms of the ratio of the degree of substitution of the basic functional group to the degree of substitution of the acidic functional group, the ratio can be, for example, within the range of 1:0.01 to 1:0.99, with the degree of substitution of the acidic functional group being 1, but from the viewpoint of obtaining an excellent thickening effect, it is more preferable that it is within the range of 1:0.10 to 1:0.40, even more preferable that it is within the range of 1:0.15 to 1:0.40, and even more preferable that it is within the range of 1:0.20 to 1:0.40. According to the findings of the present inventors, an amphiphilic, ambichargeable pullulan derivative having a ratio of the degree of substitution of the basic functional group to the degree of substitution of the acidic functional group within the above range can exhibit a particularly excellent thickening effect.

[0091] The above-described bipolar pullulan derivative having both a basic functional group and an acidic functional group has excellent solubility in aqueous solvents such as water, exerts a high thickening effect, and its aqueous solution exhibits shear-thinning properties, as shown in the experimental examples described below, and therefore can be particularly suitably used as a thickener for cosmetics in which aqueous solvents are used.

[0092] <Cosmetics> In another aspect, the present invention provides a cosmetic product containing the above-described pullulan derivative and / or thickener.

[0093] There is no particular limitation on the form of the cosmetic product according to one aspect of the present invention. The cosmetic product according to one aspect of the present invention may be in the form of, for example, a cream, a gel, a milky lotion, or a liquid, but is not limited thereto.

[0094] Specific examples of the cosmetic product according to one aspect of the present invention include skin lotion, lotion, milky lotion, beauty essence, hand cream, face cream, cleansing cream, massage cream, emollient cream, pack, foundation, sunscreen, shampoo, rinse, hair conditioner, rinse-in-shampoo, treatment lotion, hair cream, hair styling agent in foam or gel form, etc. However, these specific examples are merely illustrative of possible forms of the cosmetic product according to one aspect of the present invention, and the scope of the present invention is not limited to these.

[0095] When the thickener or pullulan derivative according to one aspect of the present invention is blended in a cosmetic product, there is no particular limitation on the blending method, and it may be blended at an appropriate stage in the manufacturing process depending on the type of the cosmetic product to be manufactured. There is also no particular limitation on the pH of the cosmetic product to be blended, but it may be, for example, 4.0 to 6.0, preferably 4.0 to 5.5.

[0096] Furthermore, when the thickener or pullulan derivative according to one aspect of the present invention is blended in a cosmetic product, there is no particular limitation on the blending amount, which may be appropriately adjusted depending on the intended use, usability, dosage form, etc. of the cosmetic product. For example, the blending amount of the pullulan derivative relative to the total mass of the cosmetic product may be, for example, 0.1 to 30 mass%, preferably 0.2 to 25 mass%, more preferably 0.3 to 20 mass%, and even more preferably 0.5 to 15 mass%.

[0097] The cosmetic containing the thickener according to one aspect of the present invention may further contain various components generally blended in cosmetics in addition to the thickener or pullulan derivative according to one aspect of the present invention. Needless to say, such optional components include, for example, excipients, solvents, surfactants, chelating agents, moisturizers, pH adjusters, antioxidants, preservatives, fragrances, etc., but are not limited thereto.

[0098] Needless to say, the thickener or pullulan derivative according to one aspect of the present invention may be used as a thickener for various products such as quasi-drugs, pharmaceuticals, foods and drinks, in addition to cosmetics. Since the suitable blending amount and the like in that case are basically the same as those described for cosmetics, the description is omitted.

[0099] Hereinafter, the present invention will be described in more detail with reference to experimental examples. However, the present invention is not limited by these experimental examples.

[0100] <Experiment 1: Pullulan derivative having a group derived from octenyl succinic acid as an acidic functional group> A pullulan derivative having a group derived from octenyl succinic acid (OSA) as an acidic functional group (hereinafter sometimes referred to as "OSA pullulan") was prepared, and the viscosity and thixotropy of its aqueous solution were evaluated.

[0101] <Preparation of OSA pullulan / Na salt> The sodium salt of OSA pullulan (OSA pullulan / Na salt) was prepared according to the synthesis scheme shown in FIG. 1. That is, 10.0 g of pullulan (trade name "Pullulan (food additive)", manufactured by Hayashibara Co., Ltd.) was dissolved in 21.0 g of water, and 0.6 g of octenyl succinic acid was added thereto. After adjusting the pH to 7.5 using a 3 mass% sodium hydroxide solution, the mixture was stirred at 40 ° C. for 6 hours. The stirred solution was freeze-dried to obtain 5.2 g of the sodium salt of OSA pullulan.

[0102] <Preparation of OSA pullulan / Ca salt> The calcium salt of OSA pullulan (OSA pullulan / Ca salt) was prepared according to the following procedure. That is, 5.0 g of the sodium salt of OSA pullulan separately prepared by the above-mentioned procedure was dissolved in 45.0 g of water. 96 μL of a 50% by mass aqueous calcium chloride solution was added to this aqueous solution, and the mixture was stirred for 30 minutes. The solution after stirring was freeze-dried to obtain 4.8 g of the calcium salt of OSA pullulan.

[0103] <Preparation of OSA pullulan / Al salt> The aluminum salt of OSA pullulan was prepared according to the following procedure. That is, 5.0 g of the sodium salt of OSA pullulan separately prepared by the above-mentioned procedure was dissolved in 45.0 g of water. 1.8 mL of a 30% by mass aqueous aluminum sulfate solution was added to this aqueous solution, and the mixture was stirred for 30 minutes. The solution after stirring was freeze-dried to obtain 4.4 g of the aluminum salt of OSA pullulan.

[0104] <Composition analysis> The composition of OSA pullulan was analyzed by 1H NMR according to a conventional method using the aluminum salt of OSA pullulan. 1 For NMR measurement, Varian 400 MR was used, and DMSO-d6 was used as the solvent. The obtained NMR spectrum is shown in Figure 2. Based on the ratio of the proton derived from the methyl group derived from octenyl succinic acid (peak g in Figure 2) to the anomeric proton derived from pullulan (peaks a and a' in Figure 2), the degree of substitution of octenyl succinic acid (the number of groups derived from octenyl succinic acid per glucose residue constituting pullulan) was calculated to be 0.024.

[0105] <Viscosity evaluation> Aqueous solutions containing the sodium salt, calcium salt, and aluminum salt of OSA pullulan obtained by the above procedure at a predetermined concentration were prepared, and the viscosity and shear thinning property of the obtained aqueous solution were measured according to a conventional method. That is, a rotational rheometer (model: MCR302, Anton Paar) was used together with a Cone Plate 50 to measure the viscosity change of the aqueous solution according to the shear rate at 30°C and in the shear rate range of 0.01 to 1,000 / s. On the other hand, the shear thinning property was evaluated as having shear thinning property (in the table shown below, shear thinning property is indicated as "◯") when the viscosity at a shear rate of 1,000 / s measured using the rotational rheometer was 1 / 10 or less of the viscosity at a shear rate of 0.01 / s, and otherwise was evaluated as not having shear thinning property (in the table shown below, shear thinning property is indicated as "X"). As a comparative control, an aqueous solution containing pullulan (product name "Pullulan (food additive)", manufactured by Hayashibara Co., Ltd.) at a predetermined concentration was prepared, and the viscosity and shear-thinning property of the obtained aqueous solution were measured in the same manner.

[0106] For each aqueous solution, the viscosity measured at rest at a shear rate of 0.01 / s is shown in Table 1. In the rest of this specification, unless otherwise specified, the viscosity measured at a shear rate of 0.01 / s is shown as the viscosity of each aqueous solution.

[0107] [Table 1]

[0108] As shown in Table 1, the viscosity of a 1 mass% pullulan aqueous solution was 1.7 mPa·s, and the viscosity of a 10 mass% pullulan aqueous solution was 240 mPa·s. In contrast, although the viscosity of an aqueous solution containing 5 mass% of the sodium salt of OSA pullulan remained at 119 mPa·s, the viscosity of an aqueous solution containing 10 mass% of the calcium salt of OSA pullulan was 2,107 mPa·s, showing a viscosity approximately nine times higher than that of an aqueous solution containing unmodified pullulan at the same concentration. And, surprisingly, the viscosity of an aqueous solution containing 10 mass% of the aluminum salt of OSA pullulan was 926,000 mPa·s, showing a viscosity approximately 3,860 times higher than that of an aqueous solution containing unmodified pullulan at the same concentration.

[0109] On the other hand, Fig. 3 shows the viscosity changes of each aqueous solution when the shear rate was changed in the range of 0.01 - 1,000 / s. As shown in Fig. 3, in an aqueous solution containing 10 mass% of pullulan and an aqueous solution containing 10 mass% of the sodium salt of OSA pullulan, a decrease in viscosity with an increase in shear rate was not observed, whereas in an aqueous solution containing 10 mass% of the calcium salt of OSA pullulan and an aqueous solution containing 10 mass% of the aluminum salt of OSA pullulan, a decrease in viscosity with an increase in shear rate, that is, thixotropy, was observed.

[0110] As described above, OSA pullulan, particularly the calcium salt and aluminum salt of OSA pullulan, show a significantly superior thickening effect compared to pullulan and also show thixotropy, so they can be used extremely advantageously as thickeners.

[0111] <Further study on the aluminum salt of OSA pullulan> In the above experiments, the aluminum salt of OSA pullulan showed a particularly excellent thickening effect. Therefore, the viscosity of the aqueous solution was examined when the concentration of the aluminum salt of OSA pullulan in the aqueous solution was changed. Specifically, aqueous solutions containing 1 mass%, 5 mass%, and 10 mass% of the aluminum salt of OSA pullulan were prepared, and the viscosity and thixotropy of the obtained aqueous solutions were evaluated by the same procedure as described above. The results obtained are shown in Table 2.

[0112] [Table 2]

[0113] As shown in Table 2, the viscosity of a 10% by mass aqueous solution of pullulan was 240 mPa s. In contrast, an aqueous solution of the aluminum salt of OSA pullulan showed a high viscosity of 39,700 mPa s at a concentration of 1% by mass, which is only one-tenth of the concentration, and when the concentration of the aluminum salt of OSA pullulan in the aqueous solution was increased to 5% by mass and 10% by mass, the viscosity increased to 109,000 mPa s and 926,000 mPa s. In this way, the aluminum salt of OSA pullulan can exhibit a significantly superior thickening effect compared to pullulan itself.

[0114] Furthermore, the shear thinning properties of an aqueous solution containing an aluminum salt of OSA pullulan at a concentration of 1% by mass were evaluated and compared with those of an aqueous solution containing a commercially available carboxyvinyl polymer (product name: Hiviswako 104, Fujifilm Wako Pure Chemical Industries, Ltd.) at the same concentration, as shown in Figure 4. As shown in Figure 4, the aqueous solution containing the aluminum salt of OSA pullulan showed the same level of shear thinning properties as an aqueous solution containing the same amount of carboxyvinyl polymer.

[0115] As described above, OSA pullulan, especially its aluminum salt, exhibits an excellent thickening effect, and its aqueous solution exhibits thixotropic properties. Therefore, it can be extremely advantageously used as a thickener for various products using an aqueous solvent. This thickening action and thixotropic property are comparable to those of carboxyvinyl polymer, which has been widely used as a thickener, indicating the usefulness of OSA pullulan, especially its aluminum salt, as a thickener. Moreover, since OSA pullulan exhibited an excellent thickening effect particularly in the presence of salts that impair the thickening effect of carboxyvinyl polymer, it can not only replace carboxyvinyl polymer derived from petroleum resources, but also provide a new thickener that can be used even in the presence of salts where the use of carboxyvinyl polymer has been restricted.

[0116] <Experiment 2: Pullulan Derivative Having Both Acidic and Basic Functional Groups> A pullulan derivative having a group derived from succinic acid (SA) as an acidic functional group and a diethylaminoethyl (DEAE) group as a basic functional group (hereinafter sometimes referred to as "DEAE / SA pullulan") was prepared, and the viscosity and thixotropic property of its aqueous solution were evaluated.

[0117] <Preparation of DEAE / SA Pullulan - Part 1> DEAE / SA pullulan was synthesized according to the scheme shown in Fig. 5. 24.0 g of pullulan (trade name "Pullulan (food additive)", Hayashibara Co., Ltd.) was dissolved in 180.0 mL of an aqueous sodium hydroxide solution with a concentration of 2.47 mol / L. While stirring the obtained aqueous solution at 40 °C, 60.0 mL of an aqueous solution of 2-(diethylamino)ethyl chloride (DEAE-Cl) hydrochloride with a concentration of 2.47 mol / L was added dropwise thereto over 30 minutes. Acetic acid was added to adjust the pH of the mixture to 6.8, and it was cooled to 25 °C. This solution was added dropwise to 2-propanol to obtain a precipitate. The obtained precipitate was separated by filtration according to a conventional method, washed with acetone, and then dried under reduced pressure at 60 °C for 24 hours to obtain 15.2 g of a pullulan derivative having a diethylaminoethyl group as a basic functional group (hereinafter sometimes referred to as "DEAE pullulan"). 5.6 g of the obtained DEAE pullulan was dissolved in 73.3 mL of DMSO. While stirring the obtained solution at 60 °C, 50.0 mL of a solution in which succinic acid was dissolved in DMSO at a concentration of 1.492 mol / L was added dropwise thereto, and then it was stirred at 60 °C for 4 hours. The obtained reaction solution was added dropwise into 2-propanol to obtain a precipitate. The obtained precipitate was separated by filtration according to a conventional method, washed with acetone, and then dried under reduced pressure at 60 °C for 24 hours to obtain 3.6 g of a pullulan derivative having a diethylaminoethyl group as a basic functional group and a group derived from succinic acid as an acidic functional group (hereinafter sometimes referred to as "DEAE / SA pullulan 1"). The composition of DEAE / SA pullulan 1 was 1 The results of analysis by 1H NMR are shown in Fig. 6. Based on the ratio of the protons derived from the diethylaminoethyl group (peak j in Fig. 6) and the protons derived from the group derived from succinic acid (peaks k and l in Fig. 6), when the ratio of the diethylaminoethyl group introduced into pullulan and the group derived from succinic acid was calculated, the ratio was 0.0034:1 (= diethylaminoethyl group: group derived from succinic acid).

[0118] <Preparation of DEAE / SA Pullulan - Part 2> 24.0 g of pullulan (trade name "Pullulan (food additive)", manufactured by Hayashibara Co., Ltd.) was dissolved in 180.0 mL of a 2.47 mol / L aqueous solution of sodium hydroxide. While stirring the resulting aqueous solution at 40°C, 60.0 mL of a 1.24 mol / L aqueous solution of 2-(diethylamino)ethyl chloride (DEAE-Cl) hydrochloride was added dropwise over 30 minutes. The pH of the mixture was adjusted to 6.8 by adding acetic acid, and the mixture was cooled to 25°C. This solution was added dropwise to 2-propanol to obtain a precipitate. The resulting precipitate was filtered and washed with acetone in a conventional manner, and then dried under reduced pressure at 60°C for 24 hours to obtain 19.8 g of a pullulan derivative having a diethylaminoethyl group as a basic functional group (hereinafter, sometimes referred to as "DEAE pullulan"). 10.0 g of the obtained DEAE pullulan was dissolved in 157.0 mL of DMSO, and while stirring the obtained solution at 60°C, 33.0 mL of a solution in which succinic acid was dissolved in DMSO at a concentration of 1.492 mol / L was added dropwise thereto, and then the mixture was stirred at 60°C for 4 hours. The obtained reaction solution was dropped into 2-propanol to obtain a precipitate. The obtained precipitate was filtered and washed with acetone in a conventional manner, and then dried under reduced pressure at 60°C for 24 hours to obtain 4.1 g of a pullulan derivative having a diethylaminoethyl group as a basic functional group and a group derived from succinic acid as an acidic functional group (hereinafter, sometimes referred to as "DEAE / SA pullulan 2"). The composition of DEAE / SA pullulan 2 was as follows: 1 The results of the H NMR analysis are shown in Figure 7. Based on the ratio of the protons derived from the diethylaminoethyl group (peak j in Figure 7) and the protons derived from the groups derived from succinic acid (peaks k and l in Figure 7), the ratio of the diethylaminoethyl group introduced into pullulan to the groups derived from succinic acid was calculated to be 0.32:1 (=diethylaminoethyl group:groups derived from succinic acid).

[0119] <Viscosity measurement> Aqueous solutions containing 1 mass%, 5 mass%, or 10 mass% of the DEAE / SA pullulan 1 obtained by the above procedure and an aqueous solution containing 10 mass% of DEAE / SA pullulan 2 were prepared, and their aqueous viscosity and shear-thinning properties were evaluated by the same procedure as in Experiment 1. The results obtained for the above aqueous solutions containing DEAE / SA pullulan 1 or 2 are shown in Table 3, together with the results obtained for the aqueous solution containing 10 mass% pullulan.

[0120] [Table 3]

[0121] As shown in Table 3, the viscosity of a 10% by mass aqueous solution of pullulan was 240 mPa·s, whereas the viscosity of an aqueous solution containing the same amount of DEAE / SA pullulan 1, which has a ratio of diethylaminoethyl (DEAE) groups and succinic acid (SA) groups of 0.0034:1 (=DEAE:SA), was 4,235 mPa·s, approximately 17 times higher than that of the aqueous solution containing pullulan. On the other hand, when DEAE / SA pullulan 2, which has a higher ratio of diethylaminoethyl (DEAE) groups and a ratio of diethylaminoethyl (DEAE) groups and succinic acid (SA) groups of 0.32:1 (=DEAE:SA), was used, a high viscosity of 10,149 mPa·s was shown at a concentration of 1% by mass, which is only one-tenth the concentration. This viscosity was more than 40 times higher than that of a 10% by mass aqueous solution of pullulan. Furthermore, the viscosity of an aqueous solution of DEAE / SA pullulan 2 increased to 159,999 mPa s at a concentration of 5% by mass, and reached 2,240,000 mPa s at a concentration of 10% by mass, which was approximately 10,000 times higher than that of an aqueous solution of unmodified pullulan at the same concentration. These results suggest that, although DEAE / SA pullulan basically exhibits an excellent thickening effect regardless of the introduction ratio of diethylaminoethyl groups and groups derived from succinic acid, from the viewpoint of increasing the viscosity of an aqueous solution, a ratio of diethylaminoethyl groups and groups derived from succinic acid of approximately 0.32:1 is preferable.

[0122] On the one hand, as shown in Fig. 8, when a shear stress was applied to the aqueous solutions of DEAE / SA pullulan 1 and DEAE / SA pullulan 2, a decrease in viscosity with an increase in shear rate was observed. From this result, it was shown that the aqueous solutions of DEAE / SA pullulan have thixotropic properties regardless of the introduction ratio of the diethylaminoethyl group and the group derived from succinic acid.

[0123] As shown above, since DEAE / SA pullulan exhibits a remarkably excellent thickening effect and its aqueous solution shows thixotropic properties, it can be extremely advantageously used as a thickener for various products in which an aqueous solvent is used.

[0124] <Experiment 3: Pullulan Derivative Having a Group Derived from Succinic Acid as an Acidic Functional Group> A pullulan derivative having a group derived from succinic acid (SA) as an acidic functional group (hereinafter sometimes referred to as "SA pullulan") was prepared, and the viscosity and thixotropic properties of its aqueous solution were evaluated.

[0125] <Preparation of SA Pullulan - Part 1> SA pullulan was prepared according to the synthetic scheme shown in Fig. 9. That is, 15.0 g of pullulan (trade name "Pullulan (Food Additive)", manufactured by Hayashibara Co., Ltd.) was dissolved in 200.0 mL of dimethyl sulfoxide (DMSO), and 40.0 mL of a solution in which dimethylaminopyridine (DMAP) was dissolved in DMSO at a concentration of 0.77 mol / L was added thereto. While stirring at 60 °C, 50.0 mL of a solution in which succinic acid was dissolved in DMSO at a concentration of 1.492 mol / L was added dropwise to this mixed solution. After the dropwise addition, the mixture was further stirred at 60 °C for 4 hours. The obtained reaction solution was dropped into 2-propanol at 28 °C to obtain a precipitate. The obtained precipitate was filtered off according to a conventional method, washed with acetone, and then dried under reduced pressure at 60 °C for 24 hours to obtain 9.9 g of a pullulan derivative having a group derived from succinic acid as an acidic functional group (hereinafter sometimes referred to as "SA pullulan 1").

[0126] <Preparation of SA Pullulan - Part 2> In addition, as a comparative control, a pullulan derivative with a small amount of acidic functional groups derived from succinic acid (hereinafter, sometimes referred to as "SA pullulan 2") was prepared according to the synthesis scheme shown in FIG. 9, except that DMAP was not used as a catalyst. That is, 10.0 g of pullulan (trade name "Pullulan (food additive)", manufactured by Hayashibara Co., Ltd.) was dissolved in 19.0 g of dimethyl sulfoxide (DMSO), and 2.5 g of 11.4 mass% succinic acid aqueous solution was dropped into this mixed solution while stirring at 40°C. After dropping, the pH of the mixed solution was adjusted to 5.0 using a 3 mass% sodium hydroxide aqueous solution, and then stirred at 40°C for another 6 hours. The obtained reaction solution was dropped into 2-propanol at 28°C to obtain a precipitate. The obtained precipitate was filtered and washed with acetone according to a conventional method, and then dried under reduced pressure at 60°C for 24 hours, to obtain 11.9 g of a pullulan derivative (hereinafter, sometimes referred to as "SA pullulan 2") having a group derived from succinic acid as an acidic functional group. In the synthesis process of SA Pullulan 2, the catalyst DMAP is not used, and the amount of succinic acid solution used is less than that of SA Pullulan 1. Therefore, as described above, it is considered that SA Pullulan 2 is a pullulan derivative with a smaller amount of acidic functional groups derived from succinic acid than SA Pullulan 1.

[0127] <Viscosity measurement> An aqueous solution containing 3% by mass of the SA pullulan 1 or its sodium salt obtained by the above procedure and an aqueous solution containing 10% by mass of SA pullulan 2 were prepared, and their water-soluble viscosity and shear-thinning properties were evaluated by the same procedure as in Experiment 1. The results obtained for the above aqueous solutions containing SA pullulan are shown in Table 4, along with the results obtained for the aqueous solution containing 10% by mass of pullulan. The sodium salt of SA pullulan 1 was basically prepared in the same manner as the calcium salt of OSA pullulan shown in Experiment 1, except that SA pullulan 1 was used as the pullulan derivative and sodium hydroxide was used as the base.

[0128] [Table 4]

[0129] As shown in Table 4, the viscosity of a 10% by mass aqueous solution of pullulan was 240 mPa·s, whereas the viscosity of an aqueous solution of SA Pullulan 1 at a lower concentration of 3% by mass was 351,000 mPa·s, which was more than 1000 times higher than that of a 10% by mass aqueous solution of pullulan. When shear stress was applied to the aqueous solution of SA Pullulan 1, a decrease in viscosity was observed with an increase in shear rate, indicating that the aqueous solution of SA Pullulan 1 has shear-thinning properties. Thus, SA Pullulan 1, which has a group derived from succinic acid as an acidic functional group, exhibits a remarkably excellent thickening effect, and its aqueous solution exhibits shear-thinning properties, and therefore can be used extremely advantageously as a thickener for various products in which aqueous solvents are used.

[0130] On the other hand, in SA pullulan 2, which has a smaller amount of acidic functional groups derived from succinic acid than SA pullulan 1, almost no increase in the viscosity of the aqueous solution was observed, and no shear thinning was observed. This result shows that in order for a pullulan derivative having a group derived from succinic acid as an acidic functional group to function as an excellent thickening agent, it is not preferable to introduce too few groups derived from succinic acid, and it is preferable to introduce more groups derived from succinic acid than SA pullulan 2, about the same amount as SA pullulan 1. As mentioned above, the amount of groups derived from succinic acid introduced in a pullulan derivative can be easily measured by a person skilled in the art using colloid titration.

[0131] The present invention will be described in more detail below by way of examples, but the following examples are not intended to limit the scope of the present invention in any way. EXAMPLES

[0132] <Lotion> A lotion was prepared in the usual manner using each component according to the formulation shown below. The pH of the lotion was 4.0 to 5.5. Blend amount (w / w%) 1,3-Butylene glycol 6.0 Glycerin 4.0 Trehalose (Product name: Trehalose (for cosmetics) / Hayashibara Co., Ltd.) 1.0 PEG-75 1.0 Polysorbate 20 0.2 Aluminum salt of OSA pullulan prepared in experiment 1 0.5 Phenoxyethanol 0.8 Citric acid (appropriate amount) Sodium citrate (appropriate amount) water remainder Total amount 100.0 EXAMPLES

[0133] <Lotion> A lotion was prepared in the usual manner using each component according to the formulation shown below. The pH of the lotion was 4.0 to 5.5. Blend amount (w / w%) 1,3-Butylene glycol 3.0 Methylparaben 0.2 Glycerin 3.5 Glycosyl trehalose (product name: Tornare (registered trademark) / Hayashibara Co., Ltd.) 3.0 Sorbitol 2.0 Pullulan (Product name: Cosmetic pullulan / Hayashibara Co., Ltd.) 0.1 Aluminum salt of OSA pullulan prepared in experiment 1 0.5 Polysorbate 80 0.2 PEG-60 hydrogenated castor oil 0.2 PEG-75 0.3 Citric acid (appropriate amount) Sodium citrate (appropriate amount) water remainder Total amount 100.0 EXAMPLES

[0134] <Gel> A gel was prepared in the usual manner using each component according to the formulation shown below. The pH of the gel was 5.0 to 5.5. Blend amount (w / w%) DEAE / SA pullulan prepared in experiment 3 10.0 Carbomer 0.1 Sodium hydroxide (appropriate amount) 1,3-Butylene glycol 2.0 Glycerin 6.0 Glycosyl trehalose (product name: Tornare (registered trademark) / Hayashibara Co., Ltd.) 1.0 PEG-8 1.5 Pentylene glycol 3.0 water remainder Total amount 100.0 EXAMPLES

[0135] <Shampoo> A shampoo was prepared according to the usual method using each component according to the formulation shown below. The pH of the shampoo was 4.0 to 5.0. Blend amount (w / w%) Sodium lauroyl methylalanine 5.6 Sodium methyl cocoyl taurate 3.5 Lauramidopropyl Betaine 18.0 PPG-2 Cocamide 2.0 Glycerin 3.5 Glycol distearate 1.2 Aluminum salt of OSA pullulan prepared in experiment 1 5.0 Glycosyl trehalose (product name: Tornare (registered trademark) / Hayashibara Co., Ltd.) 5.0 Dimethicone 0.3 Citric acid (appropriate amount) Methylparaben 0.2 Sodium chloride (appropriate amount) water remainder Total amount 100.0 EXAMPLES

[0136] <Face cream> A face cream was prepared in a conventional manner using the ingredients according to the formulation shown below. The pH of the face cream was 5.0 to 5.5. Blend amount (w / w%) Polyglyceryl-10 Stearate 1.2 Polyglyceryl-10 Myristate 1.8 Stearyl alcohol 1.0 Behenyl Alcohol 3.0 Batyl alcohol 1.0 Cetyl palmitate 1.0 Glyceryl Stearate 2.0 Vaseline 2.0 Isopropyl palmitate 4.0 Squalane 5.0 Octyldodecyl myristate 5.0 Macadamia seed oil 0.5 Triethylhexanoin 2.0 Dimethicone 0.3 Stearic acid 0.5 1,3-Butylene glycol 5.5 Pentylene glycol 3.0 Glycerin 10.0 Pullulan (Product name: Cosmetic pullulan / Hayashibara Co., Ltd.) 1.0 Aluminum salt of OSA pullulan prepared in experiment 1 0.3 Citric acid (appropriate amount) Sodium citrate (appropriate amount) water remainder Total amount 100.0 EXAMPLES

[0137] <Body cream> A body cream was prepared in a conventional manner using the ingredients according to the formulation shown below. The pH of the body cream was 5.0 to 5.5. Blend amount (w / w%) Polysorbate 60 1.0 Sorbitan stearate 1.0 Glyceryl Stearate (SE) 3.0 Cetearyl Alcohol 2.0 Cetyl Palmitate 3.0 Triethylhexanoin 10.0 Grape seed oil 10.0 1,3-Butylene glycol 3.0 Trehalose (Product name: Trehalose (for cosmetics) / Hayashibara Co., Ltd.) 3.0 Aluminum salt of OSA pullulan prepared in experiment 1 1.0 Phenoxyethanol 0.9 water remainder Total amount 100.0 [Industrial Applicability]

[0138] Thickeners are used in various products around us, including cosmetics, quasi-drugs, medicines, and food and beverages. In recent years, in all industrial fields, including cosmetic raw materials, there is a demand for a shift from fossil resources to renewable resources. Carboxyvinyl polymers, which are widely used as thickeners for cosmetic raw materials, are synthetic polymers obtained from fossil resources, while no thickeners based on renewable resources that exhibit sufficient thickening and shear-thinning properties have been known. The present invention provides a new thickener that has excellent thickening and shear-thinning properties in aqueous solvents and is obtained mainly from renewable raw materials, which contributes to the shift to renewable resources in cosmetic raw materials and has great industrial applicability.

Claims

1. A thickener containing a pullulan derivative having an acidic functional group represented by the following formula (a1) and / or a salt thereof: 【Chemistry 1】 (In the above formula (a1), A1 represents an optionally substituted saturated or unsaturated alkylene group, and * represents the bond to pullulan).

2. The thickener according to claim 1, characterized in that the acidic functional group is a group represented by the following formula (a4) derived from succinic acid and / or a succinic acid derivative: 【Chemistry 2】 (In the above formula (a4), R １ each independently represents a hydrogen atom or an optionally substituted saturated or unsaturated alkyl group, and * represents the bond to pullulan.

3. The thickener according to claim 2, characterized in that the acidic functional group is a group represented by the following formula (a6) derived from succinic acid and / or a succinic acid derivative: 【Chemistry 3】 (In the above formula (a6), R １ represents a hydrogen atom or an optionally substituted saturated or unsaturated alkyl group, and * represents the bond to pullulan.

4. R １ The thickener according to claim 3, characterized in that the substituent represented by the formula (I) is an optionally substituted saturated or unsaturated alkyl group having 1 to 20 carbon atoms.

5. The thickener according to claim 4, characterized in that the acidic functional group is a group represented by the following formula (a19) derived from octenylsuccinic acid: 【Chemistry 4】 (In the above formula (a19), * represents the bond to pullulan.)

6. The thickening agent according to claim 5 , wherein the pullulan derivative is in the form of a salt of the pullulan derivative with a divalent or higher metal ion.

7. 7. The thickener according to claim 6, wherein the salt of the pullulan derivative with a divalent or higher metal ion is a calcium salt, a magnesium salt or an aluminum salt.

8. The thickener according to claim 1, wherein the pullulan derivative further has a basic functional group represented by the following formula (b1): 【Chemistry 5】 (In the above formula (b1), R ２ are each independently a hydrogen atom or an optionally substituted saturated or unsaturated alkyl group, and n is 2 or 3. r represents the valence of the nitrogen atom and is 0 or 1. ３ is an optionally substituted saturated or unsaturated alkylene group. * represents the bond to pullulan.

9. The thickener according to claim 8, characterized in that the basic functional group is a group represented by the following formula (b6): 【Chemistry 6】 (In the above formula (b6), * represents the bond with pullulan.)

10. The thickener according to claim 9, characterized in that the acidic functional group is a group represented by the following formula (a18) derived from succinic acid: 【Chemistry 7】 (In the above formula (a18), * represents a bond with pullulan.)

11. A cosmetic, a quasi-drug, a medicine, or a food or drink, comprising the thickener according to any one of claims 1 to 10.

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