WO2023188602A1

WO2023188602A1 - External skin preparation

Info

Publication number: WO2023188602A1
Application number: PCT/JP2022/046781
Authority: WO
Inventors: 寛人佐々木
Original assignee: 大王製紙株式会社
Priority date: 2022-03-31
Filing date: 2022-12-20
Publication date: 2023-10-05
Also published as: JP2023149514A; JP7412472B2

Abstract

[Problem] To provide: a lightweight cellulose powder that has favorable dispersibility in oil-based liquids and is formed from particles that do not readily clump; and a cellulose powder dispersion. [Solution] The present invention provides an external skin preparation that is characterized by including petroleum jelly and a cellulose powder that is formed from clumps of microfibrous cellulose that has an average fiber diameter of 1–1000 nm, the cellulose powder having an average particle diameter of 1–500 μm, a loose bulk density of 0.1–300 mg/cm³, and a B-type viscosity of 50000–200000 mPa·s as measured at 35°C and a rotational speed of 3 rpm.

Description

Skin external preparations

The present invention relates to a skin external preparation.

Traditionally, external skin preparations that are solid (paste-like) at room temperature, especially Vaseline, lip balm, lipstick, etc., contain high viscosity hydrocarbons, so they have a so-called emollient effect (moisturizing effect), which makes them feel close to the skin. It has excellent durability. On the other hand, these external skin preparations tend to become sticky when applied to the skin. Various studies have been conducted to reduce stickiness, including mixing petrolatum with water-based moisturizing ingredients (emulsification), mixing petrolatum with liquid oil, and adding inorganic ultrafine particle powder to petrolatum. I can give an example.

The following documents can be cited as examples of techniques related to external skin preparations containing petrolatum. Patent Document 1 proposes a topical skin preparation that emulsifies petrolatum, an example of petrolatum, using polycondensation polymer particles or closed endoplasmic reticulum. It is disclosed that stickiness can be suppressed. Patent Document 2 proposes blending powdered hydrophobized modified alkylcellulose with white petrolatum to reduce the sticky feeling. Patent Document 3 proposes an external skin preparation that combines petrolatum, ultrafine particles of metal oxide as an ultraviolet scattering agent, and a volatile oil (volatile silicone oil), and this external skin preparation suppresses spread and stickiness. It is said that it can be done.

International publication WO2019/021801 Japanese Patent Application Publication No. 2014-141424 Japanese Patent Application Publication No. 2015-229643

As described above, Patent Documents 1 to 3 aim to suppress stickiness, but on the other hand, they result in a decrease in viscosity, impairing the high viscosity characteristic of petrolatum. Furthermore, in the case of external preparations for skin, the inventors of the present invention believe that in addition to stickiness, shine is also an important property, but this point is not considered in the above-mentioned patent documents.

Therefore, the present invention has been studied in view of the above circumstances, and an object of the present invention is to provide a skin preparation for external use that reduces not only stickiness but also shine when applied to the skin.

The above problem is solved by the following aspect.
(First aspect)
Contains petrolatum and cellulose powder,
The cellulose powder is made by agglomerating fine fibrous cellulose with an average fiber diameter of 1 to 1000 nm, has an average particle diameter of 1 to 500 μm, and has a loose bulk density of 0.1 to 300 mg/cm ³ ,
Type B viscosity is 50,000 to 200,000 mPa·s under measurement conditions of 35°C and rotation speed of 3 rpm.
A skin external preparation characterized by:

Patent Document 1 attempts to reduce stickiness by adding polycondensation polymer particles or closed vesicles as an emulsifier. Similarly, Patent Document 2 attempts to reduce stickiness by adding hydrophobically modified alkylcellulose, and Patent Document 3 attempts to reduce stickiness by adding a volatile oil agent and ultrafine particles of hydrophobically treated metal oxide. On the other hand, in this embodiment, the skin external preparation contains vaseline and cellulose powder to reduce stickiness. Cellulose powder increases the viscosity of the medium when added to the medium by itself. Although the exact mechanism for this has not been clarified, it is presumed that it is probably due to the influence of hydrogen bonds between hydroxyl groups and hydrogen groups in cellulose. It is thought that cellulose forms a static and three-dimensional network structure with each other through hydrogen bonding, resulting in high viscosity. The inventors' measurements have shown that cellulose powder has thixotropic properties, and its viscosity is relatively high in a static state and becomes low in a moving state. Since the skin external preparation of this embodiment contains cellulose powder, the B-type viscosity is high at low rotational speeds as in the above embodiment, but as the rotational speed increases, the B-type viscosity decreases. When applying a topical skin preparation with thixotropic properties to the skin, the viscosity decreases due to the application of external force, such as by hands, and the product spreads better, so the user can freely stretch the product while applying it. be able to. Note that the measurement condition of 35° C. for type B viscosity assumes a temperature close to body temperature.

The cellulose powder of this form is made by aggregating fine fibrous cellulose and has the above-mentioned average particle diameter and bulk density, so it has relatively excellent porosity and is lightweight. It is presumed that this porosity causes diffuse reflection, resulting in less shine.

In this embodiment, the cellulose powder is made by aggregating fine fibrous cellulose with an average fiber diameter of 1 to 1000 nm, has an average particle diameter of 1 to 500 μm, and has a loose bulk density of 300 mg/cm ³ or less. The loose bulk density is small compared to the average particle size, so although it is bulky, it is soft, and when applying the topical preparation to the skin, it is difficult to feel a lumpy sensation (feeling like a foreign body). There is.

Vaseline feels sticky when applied to the skin, but the inventors have found that when cellulose powder is included along with petrolatum, the stickiness is reduced. This is probably due to the thixotropic properties of cellulose powder. The action of touching the external skin preparation applied to the skin applies a dynamic external force to the cellulose powder, reducing its viscosity and making it feel slippery.

In addition to the above embodiments, the following embodiments are also preferred.
(Second aspect)
The solidifying temperature is 36°C or less,
The skin external preparation according to the first aspect.

(Third form)
the petrolatum is white petrolatum;
The skin external preparation according to the first aspect.

(Fourth form)
The cellulose powder is contained in an amount of 0.1 to 10% by mass.
The skin external preparation according to the first aspect.

(Fifth form)
The moisture content of the cellulose powder is 0.1 to 30%,
The skin external preparation according to the first aspect.

(Sixth form)
The cellulose powder has a specific surface area of 0.1 to 1000 m ² /g,
The skin external preparation according to the first aspect.

(Seventh form)
The cellulose powder is one in which inorganic fine particles are supported.
The skin external preparation according to the first aspect.

(Eighth form)
the cellulose powder is white or pale yellow;
The skin external preparation according to the first aspect.

(Ninth form)
Contains additives
the additive is a water-retaining polymer or a polyhydric alcohol;
The skin external preparation according to the first aspect.

(10th form)
the cellulose powder is porous;
The skin external preparation according to the first aspect.

According to the present invention, by containing cellulose powder, an external preparation for skin can be obtained which has a relatively high viscosity but does not have a relatively worsened stickiness or shine, or is hard to feel that it has improved.

It is an explanatory view of a spray-type freezing granulation device. This is a SEM image of cellulose powder. This is a SEM image of cellulose powder. This is a SEM image of cellulose powder. This is a SEM image of cellulose powder. 2 is a sectional view taken along the Z-Z line in FIG. 1. FIG. This is a SEM image of cellulose powder manufactured by hot drying. FIG. 6 is a side view of another embodiment of the dryer. FIG. 9 is a view of the dryer in FIG. 8 viewed in the Y direction. FIG. 3 is a diagram showing the results of a skin application test.

A mode for carrying out the present invention will be described below. Note that this embodiment is an example of the present invention. The scope of the present invention is not limited to the scope of this embodiment.

The skin external preparation according to the present embodiment contains petrolatum and cellulose powder, and the cellulose powder is made by agglomerating fine fibrous cellulose with an average fiber diameter of 1 to 1000 nm, has an average particle diameter of 1 to 500 μm, and has a loose bulk. It is characterized by having a density of 100 g/cm ³ or less, and a type B viscosity of 50,000 to 200,000 mPa·s under measurement conditions of 35° C. and 3 rpm. Before explaining the skin external preparation, the fine fibrous cellulose that is the raw material for cellulose powder will be explained.

Stickiness is a sensation felt by humans, and for example, based on the stickiness of Vaseline, cases in which the stickiness of the skin external preparation according to the present embodiment is felt to be equivalent to or improved from the stickiness of Vaseline are compared to cases in which the stickiness is relatively worsened. It can be said that there is no improvement or it is difficult to feel that it has improved. In addition, shine is a feeling that humans feel, and for example, based on the shine of Vaseline, the shine of the external skin preparation according to the present embodiment is equivalent to or improved upon the shine of Vaseline, and the shine is relatively It can be said that it is difficult to feel that it has not worsened or has improved.

(Fine fibrous cellulose)
Fine fibrous cellulose can be obtained by defibrating (refining) raw material pulp, and can be produced by known processing methods such as chemical processing and mechanical processing.

Raw material pulp for fine fibrous cellulose includes, for example, wood pulp made from hardwoods, coniferous trees, etc., non-wood pulp made from straw, bagasse, cotton, hemp, bark fibers, etc., used tea paper, used envelope paper, and magazines. Select and use one or more types of waste paper pulp (DIP) made from waste paper, used leaflet paper, used cardboard, white paper, imitation waste paper, refinished waste paper, recovered waste paper, waste paper, etc. be able to. Note that the above various raw materials may be in the form of, for example, pulverized products. In recent years, there has been an increasing demand for products containing organic ingredients that reduce environmental impact, so wood pulp made from plant-derived hardwoods and conifers other than waste paper is particularly suitable.

As the wood pulp, for example, one of chemical pulps such as hardwood kraft pulp (LKP), softwood kraft pulp (NKP), sulfite pulp (SP), dissolving pulp (DP), and mechanical pulp (TMP) or Two or more types can be selected and used. In particular, chemical pulps such as hardwood kraft pulp (LKP) and softwood kraft pulp (NKP), which are wood pulps with increased cellulose content, are preferred, and bleached pulp (BKP) is preferred.

Mechanical pulps include, for example, stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), chemical ground pulp (CGP), thermoground pulp (TGP), ground pulp (GP), One or more types can be selected and used from thermomechanical pulp (TMP), chemi-thermomechanical pulp (CTMP), refiner mechanical pulp (RMP), bleached thermomechanical pulp (BTMP), and the like.

From the viewpoint of producing fine fibrous cellulose with a relatively small average fiber diameter, it is preferable to use kraft pulp that is easy to defibrate and has high dispersibility. In particular, when applied to white or pale yellow products (e.g. external preparations for skin), it is convenient for the fine fibrous cellulose itself to be white, and from the viewpoint of improving whiteness, LBKP and NBKP are used. It is more preferable to use

The fine fibrous cellulose may be pretreated before being defibrated. For example, as a pretreatment, the raw material pulp may be prebeated mechanically or the raw material pulp may be chemically modified. The preliminary beating method is not particularly limited, and any known method can be used.

Pretreatment of raw material pulp by chemical methods includes, for example, hydrolysis of polysaccharides with acids (e.g., sulfuric acid, etc.) (acid treatment), hydrolysis of polysaccharides with enzymes (enzyme treatment), swelling of polysaccharides with alkali (alkaline treatment), etc. ), oxidation of polysaccharides (oxidation treatment) with oxidizing agents (e.g. ozone, etc.), reduction of polysaccharides with reducing agents (reduction treatment), oxidation (oxidation treatment) with TEMPO catalyst, anionization by phosphoric acid esterification, carbamate formation, etc. (anion treatment), cationization (cation treatment), etc.

Examples of the alkali used in the alkali treatment include sodium hydroxide, lithium hydroxide, potassium hydroxide, ammonia aqueous solution, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, etc. Examples include organic alkalis. From the viewpoint of manufacturing costs, it is preferable to use sodium hydroxide.

If enzyme treatment, acid treatment, or oxidation treatment is performed, the water retention degree of fine fibrous cellulose can be lowered, the degree of crystallinity can be increased, and the homogeneity can be increased. If the water retention level of fine fibrous cellulose is low, it will be easier to dehydrate and dry, so it is preferable to promote the aggregation of fine fibrous cellulose in producing cellulose powder by freezing and drying under reduced pressure.

When raw pulp is treated with enzymes, acid, or oxidation, the hemicellulose and amorphous regions of cellulose in the pulp are decomposed, and as a result, the energy required for micronization processing can be reduced, and the uniformity and dispersibility of cellulose fibers can be improved. can be improved. The dispersibility of cellulose fibers contributes to, for example, improving the homogeneity of the average particle diameter of cellulose powder. However, since pretreatment reduces the axial ratio of the fine fibrous cellulose, it is preferable to avoid excessive pretreatment.

Fine fibrous cellulose modified by introducing anionic functional groups through anionization includes fine fibrous cellulose esterified with phosphorus oxoacid, fine fibrous cellulose carbamate-formed, and hydroxyl groups of pyranose rings directly forming carboxyl groups. Examples include fine fibrous cellulose oxidized to a base.

Fine fibrous cellulose modified by introducing anionic functional groups has relatively high dispersibility. This is presumed to be because the anionic functional group causes a local charge imbalance, and the anionic functional group easily forms a hydrogen bond with water or an organic solvent in the dispersion.

When cellulose fibers are subjected to esterification with phosphorus oxoacid, which is an example of anionization, the fiber raw material can be made finer, and the produced fine fibrous cellulose has a large axial ratio, excellent strength, and high light transmittance and viscosity. Become something. Esterification with phosphorus oxo acid can be performed by the method described in JP 2019-199671 A. For example, there may be mentioned modified fine fibrous cellulose in which phosphorous acid ester groups are introduced by modifying the hydroxyl groups of cellulose fibers.

Defibration of cellulose fibers can be performed using the defibration apparatus and method shown below. The defibration may be carried out using one or more types of homogenizers such as a high-pressure homogenizer, a high-pressure homogenizer, a grinder, a millstone friction machine such as a grinder, a refiner such as a conical refiner or a disc refiner, various types of bacteria, etc. This can be done using selected means. However, the fibrillation of cellulose fibers is preferably carried out using an apparatus and method that uses a water stream, particularly a high-pressure water stream, to make the fibers fine. According to this apparatus and method, the resulting fine fibrous cellulose has extremely high dimensional uniformity and dispersion uniformity. On the other hand, for example, if a grinder is used that grinds the cellulose fibers between rotating grindstones, it is difficult to uniformly refine the cellulose fibers, and in some cases, there is a risk that undisintegrated fiber lumps may remain in some parts.

Examples of the grinder used to defibrate cellulose fibers include Mascolloider manufactured by Masuko Sangyo Co., Ltd. Furthermore, examples of devices for micronization using a high-pressure water stream include Starburst (registered trademark) manufactured by Sugino Machine Co., Ltd. and Nanovater (registered trademark) manufactured by Yoshida Kikai Kogyo Co., Ltd., and the like. Further, as a high-speed rotary homogenizer used for defibrating cellulose fibers, there may be mentioned Clearmix-11S manufactured by M Techniques.

The present inventors defibrated cellulose fibers by grinding between rotating grindstones and by using high-pressure water jets, and observed the resulting fibers under a microscope. It has been found that fibers obtained by a method of making the fibers finer have a more uniform fiber width.

Defibration by high-pressure water flow is performed by pressurizing the dispersion of cellulose fibers with a pressure intensifier to, for example, 30 MPa or more, preferably 100 MPa or more, more preferably 150 MPa or more, particularly preferably 220 MPa or more (high pressure condition), and the pore diameter is 50 μm or more. It is preferable to eject from a nozzle and reduce the pressure so that the pressure difference becomes, for example, 30 MPa or more, preferably 80 MPa or more, more preferably 90 MPa or more (reduced pressure condition). The pulp fibers are defibrated by the cleavage phenomenon caused by this pressure difference. If the pressure in the high pressure condition is low, or if the pressure difference from the high pressure condition to the reduced pressure condition is small, the fibrillation efficiency will decrease and it will be necessary to repeatedly fibrillate (spray from the nozzle) to obtain the desired fiber width. .

It is preferable to use a high-pressure homogenizer as the device for defibrating with a high-pressure water stream. The high-pressure homogenizer refers to a homogenizer that has the ability to eject cellulose fiber slurry at a pressure of, for example, 10 MPa or higher, preferably 100 MPa or higher. When cellulose fibers are treated with a high-pressure homogenizer, collisions between the cellulose fibers, pressure differences, microcavitation, etc. act, and the cellulose fibers are effectively defibrated. Therefore, the number of times of defibration processing can be reduced, and the production efficiency of fine fibrous cellulose can be increased.

As the high-pressure homogenizer, it is preferable to use one that allows the slurry of cellulose fibers to collide in opposite directions in a straight line. Specifically, for example, a counter-impingement type high-pressure homogenizer (microfluidizer/MICROFLUIDIZER (registered trademark), wet jet mill) is used. In this device, two upstream channels are formed so that pressurized slurry of cellulose fibers collide with each other in opposite directions at the confluence section. Further, the cellulose fiber slurry collides at the confluence section, and the collided cellulose fiber slurry flows out from the downstream channel. The downstream flow path is provided perpendicularly to the upstream flow path, and the upstream flow path and the downstream flow path form a T-shaped flow path. When such a high-pressure homogenizer of opposing collision type is used, the energy given from the high-pressure homogenizer is converted into collision energy to the maximum extent, so that cellulose fibers can be defibrated more efficiently.

The fine fibrous cellulose obtained by defibration can be dispersed in an aqueous medium and stored as a dispersion until used as a raw material for cellulose powder. It is particularly preferable that the aqueous medium consists entirely of water (aqueous dispersion). However, the aqueous medium may be another liquid that is partially compatible with water. As other liquids, for example, lower alcohols having 3 or less carbon atoms can be used.

The fine fibrous cellulose forming the cellulose powder of this embodiment may consist only of unmodified fine fibrous cellulose, only modified fine fibrous cellulose, or It may contain fine fibrous cellulose and unmodified fine fibrous cellulose. Examples of modified fine fibrous cellulose include those that have been oxidized with TEMPO, those that have been converted to phosphite esters, and those that have been converted to carbamate.

When the cellulose powder is formed from modified fine fibrous cellulose, a dispersion liquid in which the cellulose powder is dispersed in a dispersion medium exhibits a transparent color. On the other hand, when the cellulose powder is formed from unmodified fine fibrous cellulose, a dispersion liquid in which the cellulose powder is dispersed in a dispersion medium exhibits a white color. By adjusting the ratio of modified fine fibrous cellulose and unmodified fine fibrous cellulose in the fine fibrous cellulose forming the cellulose powder, a dispersion liquid having an intermediate color between white and transparent can be produced.

Cellulose powder is white or pale yellow regardless of whether the raw material is modified or unmodified fine fibrous cellulose. Modified fine fibrous cellulose has a smaller average fiber diameter than unmodified fine fibrous cellulose, so when comparing cellulose powders of the same mass, cellulose powder formed from fine fibrous cellulose containing modified fine fibrous cellulose has a smaller average fiber diameter than unmodified fine fibrous cellulose. However, the specific surface area tends to be larger than that of cellulose powder formed only from unmodified fine fibrous cellulose.

It is preferable to defibrate the raw material pulp so that the physical properties of the resulting fine fibrous cellulose reach desired values or evaluations as shown below.

<Average fiber diameter>
The upper limit of the average fiber diameter (average fiber width; average diameter of single fibers) of the fine fibrous cellulose is 1000 nm, preferably 500 nm or less, more preferably 100 nm or less, particularly preferably 50 nm or less. When the average fiber diameter of the fine fibrous cellulose exceeds 1000 nm, the formed cellulose powder will have a relatively small specific surface area, that is, it will have a poor porous shape. The lower limit of the average fiber diameter of the fine fibrous cellulose is 1 nm, preferably 2 nm or more, more preferably 3 nm or more. If the average fiber diameter of the fine fibrous cellulose is less than 1 nm, the dispersion will have a high viscosity, which may make it difficult to produce cellulose powder.

The average fiber diameter of the fine fibrous cellulose can be adjusted, for example, by selecting the raw material pulp, pretreatment, fibrillation, etc.

The method for measuring the average fiber diameter of fine fibrous cellulose is as follows.
First, 100 ml of an aqueous dispersion of fine fibrous cellulose with a solid content concentration of 0.01 to 0.1% by mass was filtered through a Teflon (registered trademark) membrane filter, once with 100 ml of ethanol, and 3 times with 20 ml of t-butanol. Replace the solvent. Next, it is freeze-dried, coated with osmium, and used as a sample. This sample is observed using an electron microscope SEM image at a magnification of 3,000 times to 30,000 times depending on the width of the constituent fibers. Specifically, two diagonal lines are drawn on the observed image, and three straight lines passing through the intersections of the diagonals are arbitrarily drawn. Furthermore, the widths of a total of 100 fibers that intersect with these three straight lines are visually measured. Then, the median diameter of the measured value is taken as the average fiber diameter.

<Average fiber length>
The average fiber length (average length of single fibers) of the fine fibrous cellulose is, for example, preferably 0.01 to 1000 μm, more preferably 0.03 to 500 μm. When the average fiber length exceeds 1000 μm, the fibers tend to become entangled with each other when the fine fibrous cellulose is dried, and become difficult to unravel when dispersed in an oil-based dispersion medium. In addition, other substances are easily supported on the fine fibrous cellulose, resulting in a cellulose powder that has the functionality of the other substances. If the average fiber length is less than 0.01 μm, the resulting cellulose powder will have poor entanglement.

The average fiber length can be arbitrarily adjusted, for example, by selecting the raw material pulp, pretreatment, fibrillation, etc.

The average fiber length of the fine fibrous cellulose is measured by visually measuring the length of each fiber in the same manner as the average fiber diameter. The median length of the measured value is taken as the average fiber length.

<Axle ratio>
The axial ratio of the fine fibrous cellulose is preferably 10 to 1,000,000, more preferably 30 to 5,000,000. When the axial ratio is less than 10, although the cellulose powder contained in vaseline is easily dispersed, the short axial ratio makes it difficult to form a network, making it difficult to suppress shine. On the other hand, if the axial ratio exceeds 1,000,000, the cellulose powder will have an extremely large average particle size, and there is a possibility that a rumbling sensation (foreign body sensation) may be felt when applying the external skin preparation to the skin.

<Crystallinity>
The lower limit of the crystallinity of the fine fibrous cellulose is preferably 50 or more, more preferably 60 or more, particularly preferably 70 or more, and the upper limit is preferably 100 or less, more preferably 95 or less, particularly preferably is 90 or less. If the crystallinity is less than 50, the entanglement of fibers becomes weak due to the influence of temperature changes during drying, the ability to hold other substances becomes weak, and it is difficult to form cellulose powder with a desired particle size.

The crystallinity is a value measured by an X-ray diffraction method in accordance with the "General rules for X-ray diffraction analysis" of JIS-K0131 (1996). Note that the fine fibrous cellulose has an amorphous portion and a crystalline portion, and the degree of crystallinity means the ratio of the crystalline portion in the entire fine fibrous cellulose.

<Pseudo particle size distribution>
The peak value in the pseudo particle size distribution curve of the fine fibrous cellulose is preferably one peak. If there is one peak, the fiber length and fiber diameter of the fine fibrous cellulose are highly uniform, and the fine fibrous cellulose easily becomes entangled with each other when producing cellulose powder, so the cellulose powder will not unravel in petrolatum. It becomes difficult. In addition, the cellulose powder has small statistical variations in particle size. If it is in the form of cellulose powder supporting inorganic fine particles, the cellulose powder will be sufficiently dispersed in petrolatum and will diffusely reflect incident light, so the skin to which the external skin preparation is applied will have less shine.

The peak value in the pseudo particle size distribution curve of fine fibrous cellulose is measured in accordance with ISO-13320 (2009). More specifically, the volume-based particle size distribution in the aqueous dispersion of fine fibrous cellulose is examined using a particle size distribution measuring device (laser diffraction/scattering type particle size distribution measuring device manufactured by Seishin Enterprise Co., Ltd.). Then, the most frequent diameter of the fine fibrous cellulose is measured from this distribution. This most frequent diameter is taken as the peak value. The fine fibrous cellulose preferably has a single peak in a pseudo particle size distribution curve measured by laser diffraction in a water-dispersed state. As described above, the fine fibrous cellulose having one peak is preferable because it has been sufficiently refined and can exhibit good physical properties as a fine fibrous cellulose. In addition, the peak value of the pseudo particle size distribution of the particle size of the fine fibrous cellulose that becomes the single peak is preferably 300 μm or less, more preferably 200 μm or less, and particularly 100 μm or less. preferable. When the peak value exceeds 300 μm, there are many relatively large fibers, the particle size of the cellulose powder tends to vary widely, and the shape of the cellulose powder tends to become non-uniform.

The peak value and median diameter in the pseudo particle size distribution curve of fine fibrous cellulose can be adjusted, for example, by selecting the raw material pulp, pretreatment, fibrillation, etc.

<Water retention>
The water retention degree of fine fibrous cellulose is not particularly limited, but for example, if it is unmodified fine fibrous cellulose, it is 500% or less, more preferably 100 to 500%. If the water retention degree exceeds 500%, the fine fibrous cellulose itself has a high water retention capacity and poor dehydration properties, so even if it is produced through a drying process, the drying time will be long and productivity will be poor. The lower limit of the water retention degree of the fine fibrous cellulose is not particularly limited, but if it is 100% or more, the binding force between the fine fibrous cellulose works and the shape of the cellulose powder is easily maintained.

The water retention degree of fine fibrous cellulose can be adjusted arbitrarily, for example, by selecting the raw material pulp, pretreatment, fibrillation, etc.

The water retention degree of fine fibrous cellulose is JAPAN TAPPI No. 26 (2000).

<Pulp viscosity>
The pulp viscosity of the defibrated fine fibrous cellulose is 1 to 10 mPa·s, more preferably 2 to 9 mPa·s, particularly preferably 3 to 8 mPa·s. Pulp viscosity is the viscosity of a solution after dissolving cellulose in a copper ethylene diamine solution, and the higher the pulp viscosity, the higher the degree of polymerization of cellulose, and it also affects the strength of the fiber itself.

<Additives>
In addition to the effect of preventing skin dryness caused by petrolatum (emollient effect), additives can be added for the purpose of improving the dispersibility of cellulose powder produced through the drying process in petrolatum. This is because cellulose powder has a smaller bulk specific gravity than petrolatum, so it may be unevenly distributed in the upper part of petrolatum. Adding additives to cellulose powder masks the polarity of cellulose molecules in cellulose powder, making it easier to disperse cellulose powder in petrolatum. In addition, since the cellulose powder of this form is hydrophilic, adding the additive, which is a hydrophilic material, to the skin external preparation improves the dispersibility of the cellulose powder, prevents stickiness from worsening, and suppresses shine. The effect is maintained. As the additive, one or more selected from the group consisting of polyhydric alcohols, polysaccharides, and water-retentive polymers can be used. The blending ratio of additives (=additive: fine fibrous cellulose) is preferably 1:99 to 50:50, preferably 50:50, based on solid content. If the blending ratio of additives to fine fibrous cellulose is high, the dry product (cellulose powder) will be sticky, the cellulose powder of the present invention will lose its lightweight feel, and its handling properties will deteriorate. On the other hand, if the blending ratio is too low, the above-mentioned dispersion effect may deteriorate.

Examples of polyhydric alcohols used as additives include polyhydric alcohols having 2 to 6 carbon atoms and 2 to 3 oxygen atoms. Specifically, glycerin, propylene glycol, butylene glycol, pentanediol, dipropylene glycol, hexanediol, heptanediol, ethylene glycol, diethylene glycol, 1,3-propanediol, 3-methyl-1,3-butanediol, etc. However, the present invention is not limited to these. Glycerin is particularly preferred from the viewpoint of thickening properties and dispersibility of composite particles.

As the polysaccharide, quince seed, vegum, xanthan gum, hyaluronate, etc. can be used, but the polysaccharide is not limited to these. In particular, hyaluronate and the like are preferred from the viewpoint of thickening properties and dispersibility of cellulose powder.

Water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, carboxyvinyl polymer, polyethylene glycol, homopolymers or copolymers whose constituent monomers are monomers having a phosphorylcholine group, and homopolymers or copolymers whose constituent monomers are monomers having sugar residues. , homopolymers or copolymers whose constituent monomers are monomers having amino acid residues. Specifically, copolymers consisting of alkyl (meth)acrylates and polymethacryloyloxyethylphosphorylcholine, copolymers consisting of alkyl (meth)acrylates and methacryloyloxyethyl glucoside, alkyl (meth)acrylates and methacryloyl-L-lysine. Examples include copolymers consisting of, but are not limited to. Particularly preferred is polyvinylpyrrolidone from the viewpoint of thickening properties and dispersibility of cellulose powder.

Note that the additive also has the effect of moisturizing the skin.

<Inorganic fine particles>
The cellulose powder may contain inorganic fine particles. Inorganic fine particles can impart various functions to cellulose powder. For example, by adding metal-based inorganic fine particles, an effect of diffusing and reflecting incident light can be expected. External skin preparations containing cellulose powder containing inorganic fine particles diffusely reflect incident light, thereby suppressing shine on the applied area.

The content of inorganic fine particles in the cellulose powder may have an upper limit of 50% by mass, preferably 45% by mass or less, and a lower limit of 0% by mass, preferably 5% by mass or more. When the content exceeds 50% by mass, the specific gravity of the cellulose powder increases due to the inorganic fine particles contained therein, and there is a risk that the dispersibility in the external skin preparation may be impaired. On the other hand, if the content is 5% by mass or more, the effect of diffuse reflection of incident light will be sufficiently exhibited.

The upper limit of the primary particle diameter of the inorganic fine particles is preferably 10 μm, preferably 5 μm or less, and more preferably 1 μm or less. When the primary particle diameter of the inorganic fine particles exceeds 10 μm, it becomes difficult for the inorganic fine particles to be supported by the fine fibrous cellulose. Moreover, the surface area as a cellulose powder is not large enough. The lower limit of the inorganic fine particles is not particularly limited, but may be 1 nm, preferably 2 nm or more, and more preferably 3 nm or more. If the primary particle diameter of the inorganic fine particles is 1 nm or more, when the inorganic fine particles are mixed into a raw material slurry for producing cellulose powder, the inorganic fine particles tend to disperse and stick to the fine fibrous cellulose.

The primary particle diameter of the inorganic fine particles can be measured by electron microscopic observation, and the average value of the obtained particle diameters is taken as the measured value.

The inorganic fine particles can of course be used as they are, but it is preferable to hydrophilize them because they become more compatible with the raw material slurry for producing cellulose powder. The surface treatment agent used in the hydrophilic treatment has the effect of suppressing the surface activity of the inorganic fine particles, improving the dispersibility of the inorganic fine particles, and improving transparency and squeaking. The surface treatment agent for inorganic fine particles is not particularly limited as long as it can be dispersed in the raw material slurry, but those containing anhydrous silicic acid and hydrated silicic acid are preferred.

The inorganic fine particles are not particularly limited and any known inorganic fine particles can be used, but examples include barium titanate, lead zirconate titanate, silicon carbide, silicon nitride, aluminum nitride, alumina, zirconia, zircon, titanium oxide, and titanium oxide. Zinc, iron oxide, cerium oxide, etc. can be mentioned. A cellulose powder containing these powders and fine fibrous cellulose is preferable because it has excellent redispersibility in a liquid. From the viewpoint of suppressing the transmission of sunlight, for example, one type or a combination of two or more types selected from the group consisting of titanium oxide, zinc oxide, iron oxide, and cerium oxide can be used. In particular, when the inorganic fine particles are titanium oxide, the rutile type is preferable because it improves the suppression of sunlight transmission in the skin external preparation.

The shape of the inorganic fine particles that can be included in the cellulose powder is not particularly limited, but can be, for example, spherical, rod-like, needle-like, spindle-like, plate-like, polygonal, etc.

The inorganic fine particles may be attached to the surface of the fine fibrous cellulose in the cellulose powder, or may be encapsulated in the fine fibrous cellulose. It is preferable that the inorganic fine particles are encapsulated in the fine fibrous cellulose because the inorganic fine particles can be carried not only on the surface of the cellulose powder but also inside the cellulose powder, and even if incident light is irradiated from various angles, it will be diffusely reflected. Here, inclusion refers to the state in which part of the surface of an inorganic fine particle is covered with fine fibrous cellulose, or the state in which the inorganic fine particle is covered with fine fibrous cellulose when observing cellulose powder from the outside. It can be said that it is not possible.

Inorganic fine particles can be added to fine fibrous cellulose before drying, and should be mixed until uniform.

(cellulose powder)
The cellulose powder of this embodiment is formed by drying fine fibrous cellulose, but when viewed microscopically, the fine fibrous cellulose dries as a single substance and aggregates (for example, in one piece). Some are formed by the intertwining of book threads within the threads, while others are formed by agglomeration of multiple fine fibrous celluloses during drying. Fine fibrous cellulose is manufactured from raw material pulp, and when dried, the fibers wrinkle and shrink, so the cellulose powder that is formed has an uneven shape, although it is difficult to describe.For example, dried fine fibrous cellulose It has a shape that looks like an agglomeration of paper, a shape that looks like confetti, or a shape that looks like one or more sheets of paper, such as hanshi paper, that have been crumpled and rolled up. Furthermore, the cellulose powder is white, pale yellow, cream colored, pale orange, or a mixture of these colors. In particular, white or pale yellow cellulose powder is preferred because it is inconspicuous even when mixed with vaseline.

Since cellulose, which is a constituent unit of fine fibrous cellulose, has hydroxy groups (OH groups) and hydrogen groups (H groups), cellulose powder containing fine fibrous cellulose also has hydroxy groups and hydrogen groups. Hydroxy groups and hydrogen groups form hydrogen bonds with other hydroxy groups and hydrogen groups, thereby hydrogen bonding the fine fibrous cellulose within the cellulose or with each other, forming a three-dimensional network structure of cellulose powder. When cellulose powder is mixed with an aqueous medium, hydrogen bonds are loosened by hydrolysis, etc., and the aggregation of cellulose is weakened, causing the cellulose powder and the loosened fine fibrous cellulose to be dispersed in the aqueous medium. On the other hand, if cellulose powder is mixed with an oil-based medium instead of an aqueous medium, the following will occur. Since the oil-based medium is hydrophobic, the cellulose powder does not unravel as easily as under an aqueous medium. The cellulose powder is dispersed in an oil-based medium while maintaining its shape. In this case, the cellulose powder is difficult to settle and maintains a dispersed state.

The cellulose powder according to the present embodiment preferably contains fine fibrous cellulose in an amount of 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, with an upper limit of 100% by mass. It's fine. When the mass percentage of fine fibrous cellulose in the cellulose powder is less than 50 mass%, there is a possibility that the desired bulk density and specific surface area of the cellulose powder of the present invention cannot be obtained.

<Average particle diameter>
The cellulose powder according to this embodiment preferably has an average particle size in the range of 0.1 to 1000 μm, more preferably in the range of 0.1 to 700 μm, and still more preferably in the range of 0.1 to 500 μm. This is the range of Although the effects of the present invention can be exerted even if the average particle diameter is less than the above range, from the viewpoint of ease of handling, it is desirable that the average particle diameter is at least the lower limit of the above range. On the other hand, if the average particle diameter exceeds the above range, when the cellulose powder is filled or dispersed in a dispersion medium, the voids formed between the particles become large, making it difficult to adjust the concentration to the desired concentration.

The standard deviation of the particle diameter of the cellulose powder is preferably 1 to 400 μm, more preferably 1 to 300 μm, particularly preferably 2 to 200 μm.

The cellulose powder of this form is characterized by having particle sizes of various sizes. Specifically, the dispersion coefficient of particle diameter is statistically large. Note that the cellulose powder does not have excellent sphericity, and has individual irregularities, a porous shape, and different shapes.

The cellulose powder of this form has a porous shape as seen in FIG. The individual pores constituting the porous shape have, for example, a pore diameter of 0.001 to 5 μm. When cellulose powder supports inorganic fine particles, the inorganic fine particles may be stuck in the pores or may be attached to the surface of the cellulose powder. Therefore, the inorganic fine particles can be supported on the cellulose powder regardless of the size of the pores. Note that not only inorganic fine particles but also vaseline, surfactants, and additives can be supported on the cellulose powder.

Furthermore, since cellulose powder has a porous shape, incident light from the outside is reflected at various angles by the pores. Therefore, the skin external preparation containing the cellulose powder has the effect of suppressing shine.

Furthermore, although not shown, the cellulose powder of this embodiment can be manufactured by drying, for example, so that multiple dried and wrinkled fine fibrous celluloses are entangled to form porous pores. Sometimes. Since fine fibrous cellulose dries in various ways, the cellulose powder that is formed does not consist of particles of a single shape, but of particles of various shapes.

The average particle diameter, median diameter, cumulative 10% diameter, and cumulative 90% of cellulose powder are measured using a measuring device compliant with ISO-13320 (2009), specifically a laser diffraction/scattering particle size distribution measuring device (particle size distribution ) The values were measured using a dry method using "LA-960V2" without removing the moisture attached to the cellulose powder.

<Specific surface area>
The specific surface area of the cellulose powder is preferably 0.1 m ² /g or more, more preferably 1 m ² /g or more, even more preferably 10 m ² /g or more, and the upper limit of the specific surface area is not particularly limited, but it is 1000 m ² /g. Good to have. When the specific surface area is less than 0.1 m ² /g, it becomes difficult to obtain porous particles without unevenness on the particle surface, which is important in terms of suppressing stickiness and shine. On the other hand, those having a specific surface area of more than 1000 m ² /g are preferable in terms of particle weight reduction and redispersibility, but are extremely difficult to manufacture.

The specific surface area of the cellulose powder was measured by the BET method. Specifically, NOVA4200e manufactured by Quantachrome Instruments was used as a measuring device, and the measurement was carried out by an adsorption method using nitrogen gas. The compliant test method is JIS Z8830:2013.

<Moisture percentage>
The moisture content of the cellulose powder is preferably 30% or less, more preferably 20%, even more preferably 10% or less. Cellulose powder with a moisture content of more than 30% contains a large amount of water, and when the external skin preparation is left for a long time, there is a risk that it will separate into a cellulose powder phase and a vaseline phase.

<Bulk density>
The cellulose powder according to the present embodiment preferably has a consolidated bulk density of 0.1 to 400 mg/cm ³ , more preferably a consolidated bulk density of 0.1 to 380 mg/cm ³ , and still more preferably a consolidated bulk density of 0.1. ~350 mg/cm ³ . Cellulose powder with a solidified bulk density of more than 400 mg/cm ³ is an aggregate in which fibers are tightly intertwined with each other and has poor dispersibility. Moreover, even if it is dispersed in a dispersion medium, a portion of it may gradually start to settle due to its own weight, and it cannot be said that it has excellent dispersibility. Cellulose powders with a solidified bulk density of less than 0.1 mg/cm ³ tend to disintegrate in the air and have poor handling properties.

The cellulose powder according to the present embodiment preferably has a loose bulk density of 0.1 to 300 mg/cm ³ , more preferably a loose bulk density of 0.1 to 280 mg/cm ³ , and still more preferably a loose bulk density of 0.1. ~250 mg/cm ³ . Similar to the aforementioned bulk density, cellulose powder with a loose bulk density of more than 300 mg/cm ³ is an aggregate in which the fibers are tightly intertwined, and on the other hand, the loose bulk density is 0.1 mg/cm ³ Cellulose powder of less than 100% is easily disintegrated in the air and has poor handling properties.

The following relational expression [Equation 1] holds true between the loose bulk density, hardened bulk density, and degree of compaction of the cellulose powder according to the present embodiment.
[Number 1]
(Compaction degree (%)) = ((Hardened bulk density) - (Loosened bulk density)) / (Hardened bulk density) x 100

The hardened bulk density and the loosened bulk density are one of the items used to calculate Carr's fluidity index, and were measured in accordance with ASTM D6393-99 compressibility measuring method. The measurement was carried out using a "multi-functional powder physical property measuring device Multitester MT-02" (manufactured by Seishin Enterprise Co., Ltd.).

<Compression degree>
Regarding the degree of compression of the cellulose powder, the degree of compression is preferably 50% or less, more preferably 40% or less, and still more preferably 30%. In the process of performing the compression operation to measure the compacted bulk density after measuring the loose bulk density, the voids formed between the cellulose powders are eliminated (i.e., the voids formed between the cellulose powders are eliminated, causing the inside of the container to cellulose powders are tightly packed together), and some particles may collapse. In this respect, in the cellulose powder of this embodiment, the voids are only eliminated during the compression operation process, and the change in the density of the cellulose powder itself is small, making it difficult for particles to collapse. The cellulose powder of this form is not a spherical shape with excellent sphericity, but (although it is difficult to express) it is a granular material with irregularities and porous material, so when it is poured into a container and filled, it will have a shape of various sizes. Many shaped voids occur. If the degree of compaction exceeds 50%, the particles may lose their light weight feel, since it is suggested that the cellulose powder will collapse in addition to filling the voids between the particles. In addition, cellulose powder manufactured by the hot dry drying method shown in Figure 7 is a solid particle formed by tightly agglomerating the fibers, so the compression operation in measuring the degree of compaction , the cellulose powder only fills the voids between particles, and there is little collapse of the particles themselves. Note that the voids formed between cellulose powders can be conceptually understood by imagining voids formed between atoms filled in a unit cell. On the other hand, the lower limit of the degree of compaction of the cellulose powder is not particularly limited (ie, 0%), but may be, for example, 1% or more, considering that the above-mentioned voids are slightly generated.

When the cellulose powder according to the present embodiment is a cellulose powder produced by freeze-drying (also referred to as "freeze-dried powder"), the average particle size is preferably in the range of 1 to 1000 μm, more preferably 1 to 1000 μm. The average particle diameter is in the range of 800 μm, more preferably in the range of 1 to 500 μm. The loosened bulk density of the freeze-dried powder is preferably 0.01 to 100 mg/cm ³ , more preferably 0.01 to 50 mg/cm ³ . The specific surface area of the freeze-dried powder is preferably 10 to 1000 m ² /g, more preferably 20 to 1000 m ² /g.

When the cellulose powder according to the present embodiment is a cellulose powder produced by heat drying treatment (also referred to as "heat dry powder"), the average particle size is preferably in the range of 50 to 500 μm, more preferably 50 to 500 μm. The average particle diameter is in the range of 400 μm, more preferably in the range of 50 to 300 μm. The loose bulk density of the heat-dried powder is preferably 50 to 1000 mg/cm ³ , more preferably 100 to 800 mg/cm ³ . The specific surface area of the heat-dried powder is preferably 0.1 to 5 m ² /g, more preferably 0.2 to 5 m ² /g.

When the cellulose powder according to the present embodiment is a cellulose powder produced by spray drying (also referred to as "spray dried powder"), the average particle size is preferably in the range of 0.1 to 30 μm, more preferably The average particle diameter is in the range of 0.1 to 25 μm, more preferably in the range of 0.1 to 20 μm. The loose bulk density of the spray-dried powder is preferably 50 to 1000 mg/cm ³ , more preferably 100 to 800 mg/cm ³ . The specific surface area of the heat-dried powder is preferably 0.5 to 10 m ² /g, more preferably 1 to 10 m ² /g.

(Manufacturing)
Cellulose powder can be dried as a raw material for cellulose nanofibers by freeze-drying, vacuum drying, heat-drying (for example, hot dry drying), spray-drying, or other methods of drying the cellulose powder of this embodiment. It can be produced by spray freezing/vacuum drying, but it is particularly preferable to use spray freezing/vacuum drying as it allows the production of porous cellulose powder. If the cellulose powder is porous, it is possible to support another substance in the large number of pores formed in the cellulose powder, or to utilize a large surface area. By doing so, properties not found in cellulose can be imparted to cellulose powder.

Although the cellulose powder according to the present invention can be produced by freeze-drying, it is preferable to use the spray-type freeze granulation apparatus 1 shown in FIG. 1, for example, because particles with relatively small specific gravity can be produced. The spray-type freeze granulation device 1 includes a freeze granulation tank 8, a spray mechanism section 7 that sprays raw material M onto the upper part of the freeze granulation tank 8, and a spray mechanism section 7 provided below the freeze granulation tank 8 to spray frozen cellulose powder. and a drying section 6 for drying. The raw material M sprayed into the freeze granulation tank 8 is instantaneously frozen in the freeze granulation tank 8 and becomes a frozen body P. The frozen body P naturally falls into the drying section 6 and is stored therein. The drying section 6 is separably connected to the freeze granulation tank 8, and is separated from the freeze granulation tank 8 when the frozen body P is stored, and is sealed to dry the frozen body P to obtain cellulose powder. It is possible.

As the raw material M, a slurry or dispersion of fine fibrous cellulose can be exemplified. The fine fibrous cellulose used as the raw material M may be a fine fibrous cellulose from one group, or may be a combination of fine fibrous cellulose from two groups. In the case of a combination of two groups of fine fibrous cellulose, the fine fibrous cellulose group C1 has an average particle diameter R of more than 10 nm to 1000 nm or less, and the fine fibers have an average particle diameter R of 1 nm or more to 10 nm or less. The cellulose group C2 may be mixed at a mixing ratio of 1:99 to 99:1.

The spraying mechanism section 7 has a raw material flow path to which the raw material M is supplied, a compressed gas flow path to which the compressed gas A is supplied, and a freezing granulation tank for a mixed fluid in which the supplied raw material M and compressed gas A are mixed. 8 has a nozzle 5 (also referred to as a two-fluid nozzle) that sprays water into the air. Examples of the form of the nozzle 5 include a three-fluid type, a four-fluid type, a pressurized type, an ultrasonic type, and a centrifugal spray type.

The raw material flow path has a mechanism in which the base end is connected to a raw material tank that stores the raw material M, and the raw material M flows from the raw material tank to the nozzle 5 by a pump provided in the raw material flow path. The compressed gas flow path has a mechanism in which the base end is connected to a compressed gas supply device such as a compressor or a cylinder, and the compressed gas flows into the nozzle 5 by activating the compressed gas supply device. Examples of the compressed gas include air, nitrogen, and rare gases.

In addition to fine fibrous cellulose, the raw material M may contain additives and inorganic fine particles, and may also contain a plasticizer. Examples of plasticizers include phthalic acid esters and citric acid esters.

The freeze granulation tank 8 is composed of three tanks, and specifically includes three cylinders with different diameters, which are arranged in concentric circles with the same axis, with the axis extending in the vertical direction. These three cylinders become the inner tank wall 2, the middle tank wall 3, and the outer tank wall 4 in order from the inside, and the inner tank surrounded by the inner tank wall 2 becomes the freezing tank 12 for freezing the raw material M, the inner tank wall 2, and the inner tank wall 2. A cooling medium filling tank 13 in which a bottomed middle layer surrounded by a tank wall 3 is filled with a cooling medium, and a bottomed outer tank surrounded by an outer tank wall 4 and an inner tank wall 3 keep the temperature inside the tank constant. It serves as a vacuum insulation tank 14 for holding. The freezing tank 12 is preferably configured such that the lower end of the inner tank wall 2 is removably connected to a flange portion 4a formed at the upper end of the drying section 6.

The freezing tank 12 forms a frozen body P by freezing the raw material M sprayed from the nozzle 5 provided near the top surface. The freezing tank 12 preferably has a temperature of -10°C to -200°C by the cooling medium supplied from the cooling medium filling tank 13.

The cooling medium filling tank 13 is filled with a cooling medium for cooling the freezing tank 12. As the cooling medium, for example, liquid nitrogen, liquid argon, liquid helium, dry ice, etc. can be used.

The vacuum insulation tank 14 is surrounded by an inner tank wall 3 and an outer tank wall 4, the upper end of the inner tank wall 3 and the upper end of the outer tank wall 4 are closed, and the lower end of the inner tank wall 3 and the lower end of the outer tank wall 4 are closed. is closed and has a structure that prevents fluid from flowing into the vacuum insulation tank 14 from the outside, so that it is maintained in a vacuum state and heat transfer between the cooling medium filled in the cooling medium filling tank 13 and the outside air is difficult to occur. It has become.

The cooling medium filling tank 13 has a cooling medium supply pipe 15 extending from the outside into the cooling medium filling tank, and is configured so that the cooling medium N is supplied into the cooling medium filling tank 13. It has a cooling medium introduction pipe 16 that introduces the cooling medium gas obtained by vaporizing the cooling medium N in the tank 13 into the freezing tank 12, and is configured so that the cooling medium gas is introduced into the freezing tank 12.

The frozen body P formed in the freeze granulation tank 8 is stored in a drying section 6 that is detachably provided with respect to the freeze granulation tank 8. After a predetermined amount of frozen material P is stored in the drying section 6, the drying section 6 is separated from the freeze granulation tank 8, sealed, and freeze-dried to obtain cellulose powder. The configuration of the dryer 100 according to this embodiment will be described below.

The dryer 100 has a drying section 6 and a vacuum mechanism. The drying section 6 may have a cylindrical wall whose axis is in the vertical direction and a bottom continuous with the wall. The cylindrical wall can be provided with an exhaust part (not shown) that can be opened and closed, and the gas in the drying part 6 can be exhausted as exhaust gas D from the exhaust part. The upper end edge of the cylindrical wall is a flange portion 4a, which is detachably connected to the lower end edge of the freezing granulation tank 8. After the frozen body P generated in the freeze granulation tank 8 falls into the drying section 6, the drying section 6 is removed from the freeze granulation tank 8, and the flange section 4a is covered with an upper lid and hermetically sealed to freeze-dry the frozen body P.

The drying process of the frozen body P can be performed as follows. The drying section 6 is configured to be able to connect the base end of a gas pipe 21 for evacuation, and the gas sucked into the gas pipe 21 is guided to a cooling trap 22 connected to the tip of the gas pipe 21. A portion of the gas is concentrated and separated as a concentrated liquid or solid, and the remaining gas is sucked by a vacuum pump 24 provided at the other end of the gas pipe 23 connected to the cooling trap 22. When the vacuum pump 24 is started with the drying section 6 sealed, the air pressure inside the drying section 6 decreases, and the sublimable or vaporizable substances contained in the frozen body P (for example, the raw material M is mixed with water and fine fibers). In the case of a dispersion made of cellulose, the water sublimes or vaporizes and is sucked into the vacuum pump 24, and the remainder becomes cellulose powder. In the process of performing the drying process, it is preferable to rock or vibrate the drying section 6 so that the frozen bodies P do not aggregate with each other and in order to dry each frozen body P evenly. The drying section 6 may be vibrated or rocked manually, or may be vibrated or rocked by a vibrating mechanism or a rocking mechanism. When vibrating, for example, the flange portion formed in a substantially circular shape may be gripped at both ends of the diameter (

portions

4a and 4a in FIG. 1) and shaken from side to side. For example, a method may be adopted in which the diameter is used as a rotation axis and the rotation is repeated alternately clockwise and counterclockwise. The pivot angle to the clockwise or counterclockwise direction is not particularly limited, but it is preferable to set it to 30° to 100° because the frozen body P in the drying section 6 is shaken. In the drying process, it is not essential to rock or vibrate, and the frozen body P may be vacuum-dried in a stationary state. Although it cannot be said in general, the bulk density of the cellulose powder produced may be relatively higher if the drying process is rocked or vibrated.

Another embodiment of the dryer 200 will be described with reference to FIGS. 8 and 9. The difference from the dryer 100 of FIG. 1 described above is that it includes a shaft 30 for swinging the drying section 6. By providing the swinging mechanism on the axis 30, the drying section 6 can be rotated, for example, by 100 degrees clockwise or counterclockwise toward the paper surface of FIG. 9 about the axis 30.

Cellulose powders 11 and 11' produced by the above production method are shown in FIGS. 2 to 5. The cellulose powder 11 shown in FIGS. 2 and 3 was produced using a spray freeze granulation device 1 using a 2% by mass aqueous dispersion of unmodified fine fibrous cellulose (ELEX (registered trademark)-S) as a raw material. It is. A large number of pores 11a are confirmed in the cellulose powder 11, indicating that the cellulose powder 11 has a porous structure. The cellulose powder 11' shown in FIGS. 4 and 5 was produced using a spray freeze granulation device 1 using a 2% by mass aqueous dispersion of modified fine fibrous cellulose (ELLEX (registered trademark)-STAR) as a raw material. It is. A large number of pores 11'a were confirmed in the cellulose powder 11'. The drying process was performed by placing the sample in a vacuum dryer ("EYELA FDU-2110" manufactured by Tokyo Rikakikai Co., Ltd.) and vacuum drying it while standing still. The freeze granulation tank 8 can be exemplified by "Freeze Granulation Chamber CS30" manufactured by Priss Corporation, and the dryer 200 can be exemplified by the barrel freeze drying unit "TFD-10" manufactured by Priss Corporation.

Cellulose powder can be produced by the freeze-drying method described above, but it can also be produced by a heat-drying method or a spray-drying method. According to the method for manufacturing cellulose powder using the drum drying method among heat drying methods, even if the cellulose is in the form of fine fibers with relatively high concentration or poor fluidity, it is possible to produce a dried product that is difficult to aggregate and easily dispersed. Obtainable. An example of manufacturing cellulose powder using the drum dry method is as follows.

The fine fibrous cellulose can be supplied, for example, in the form of a slurry (aqueous dispersion) to a drum dryer that performs a drying process, but in this case, the content of the fine fibrous cellulose (absolutely dry mass %) is 1 mass %. The content is preferably 1.5% by mass, more preferably 2.0% by mass. Further, the content is 10% by mass or less, preferably 7% by mass, and more preferably 5% by mass. When the content exceeds 10% by mass, the viscosity of the slurry is too high and the handling properties are poor. On the other hand, if the content is less than 1% by mass, a lot of energy and time are consumed to remove water, which is not economical.

The drum dryer used in the drum drying method may be a known drum dryer. For example, "John Milder JM-T" manufactured by Johnson Boiler Company can be used. As the drum dryer, an internal rotary drum dryer can be suitably used. An internal rotary drum dryer performs a gentle drying process, resulting in a dried product with a relatively small specific surface area. The drying process can be performed under normal pressure.

Regarding the operating conditions of the drum dryer, the surface temperature of the inner surface of the drum is 80 to 200°C, preferably 90 to 190°C. At this surface temperature, a dried product with strong cohesive force can be obtained. When the surface temperature exceeds 200° C., there is a risk that some of the fibers of the fine fibrous cellulose will undergo thermal denaturation. On the other hand, if the surface temperature is less than 80° C., not only will it take a lot of time to remove moisture, but the particles will have a very high moisture content. Further, the rotational speed of the drum dryer can be, for example, 1 rpm or more and 2 rpm or less, although it depends on the inner diameter of the drum and the amount of slurry input. The time required for drying with a drum dryer is from 1 second to 60 seconds, depending on the amount of slurry input, for sufficient drying, and even if the drying time is longer than that, the moisture content of the dried product will not decrease any further.

As an example of the device used for the spray drying process, a spray drying device (“TR160” manufactured by Pris Co., Ltd.) can be exemplified. Spray-dried powder can be obtained by feeding a slurry of fine fibrous cellulose to a spray-drying device. The device was a two-fluid nozzle system and used two 90-type nozzles. The spray drying conditions are, for example, a slurry of fine fibrous cellulose (for example, a supply rate of 0.1 to 3.0% of fine fibrous cellulose): 20 kg/h, an inlet temperature of drying air of 200°C, and an outlet temperature of 200°C. The temperature can be 100° C. and the atomizing air pressure can be 0.6 MPa, but this is not the only option.

(Vaseline)
Examples of petrolatum include yellow petrolatum, white petrolatum, propeto, sun white, balms (e.g., moisturizing balm, cleansing balm), creams, especially lip balms, and white petrolatum is preferred, but not limited thereto.

Vaseline has a melting point of 36 to 60°C, preferably 40 to 55°C. If the melting point is less than 36°C, it may melt during storage at room temperature (for example, 15 to 30°C), and if it exceeds 60°C, it may remain hard and difficult to spread when applied.

(External skin preparation)
The content of cellulose powder in the external skin preparation of this form is not particularly limited as long as the type B viscosity of the external skin preparation is within a predetermined range, but if there is too much or not enough cellulose powder, it may be necessary to apply it to the skin. There is a possibility that you may feel discomfort or strong stickiness. Therefore, the skin external preparation preferably contains cellulose powder in an amount of 0.1 to 10% by mass, more preferably 0.2 to 9% by mass, and still more preferably 0.3 to 8% by mass.

The type B viscosity of the skin external preparation (measurement conditions are rotation speed: 3 rpm, 35° C.) is preferably 50,000 to 200,000 mPa·s, more preferably 555,000 to 190,000 mPa·s, and even more preferably 60,000 to 18,000 mPa·s. When the type B viscosity of the external skin preparation exceeds 200,000 mPa·s, it becomes difficult to apply and spread the external skin preparation of this embodiment on the skin. On the other hand, if the type B viscosity of the external skin preparation is less than 50,000 mPa·s, petrolatum and cellulose powder are likely to undergo phase separation, and a foreign body sensation may be felt when the external skin preparation is applied to the skin.

The skin external preparation of the present invention is characterized in that the hydrophilic cellulose powder can be maintained dispersed in the hydrophobic vaseline without adding a surfactant in principle. This is presumed to be based on the relatively low bulk density and large average particle diameter that are unique to the cellulose powder of this form. If the moisture content of the cellulose powder is within the above range, phase separation into an oil phase and an aqueous phase will be less likely to occur.

The solidification temperature of the external skin preparation of this form is preferably 35°C or lower, more preferably 34°C or lower. If the temperature at which the external skin preparation solidifies is 35° C. or higher, depending on the outside temperature (or indoor temperature), the external skin preparation may liquefy and become difficult to use. Furthermore, if the cellulose powder easily solidifies or liquefies depending on the outside temperature (or room temperature), the distribution of the cellulose powder in the skin external preparation may become uneven, depending on the storage state. The temperature at which the external skin preparation solidifies can be adjusted by adjusting the blending ratio of vaseline, the surfactant and additives described below.

The skin external preparation contains vaseline and cellulose powder, and may also contain surfactants (emulsifiers), additives, etc. to impart functionality. The percentage of vaseline contained in the skin external preparation is preferably 50 to 99% by weight, more preferably 60 to 95% by weight. If the percentage exceeds 99% by mass, the content of cellulose powder will be relatively low, and the shine-preventing effect of the external skin preparation will be poor. On the other hand, if the percentage is less than 50% by mass, the viscosity will be too low and there is a risk that the film will not feel as good on the skin.

(surfactant)
In principle, the skin external preparation of this embodiment does not need to contain a surfactant since the cellulose powder is well dispersed in petrolatum. However, if left for a long time, the cellulose powder may become unbalanced, so a surfactant can be added to the extent that the viscosity of the external skin preparation is not impaired to emulsify it. When emulsifying, it can be dispersed and emulsified using a known disperser (homogenizer, etc.). When external skin preparations contain surfactants, it is thought that the electrical repulsion between cellulose powder and petrolatum is reduced, and as a result, cellulose powder remains dispersed in petrolatum for a long period of time. . The percentage of the surfactant in the external skin preparation is preferably 0.1 to 5% by weight, preferably 0.2 to 4% by weight.

As the surfactant, for example, nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, phospholipids, etc. can be used, In particular, it is preferable to use ester type or ester/ether type nonionic surfactants, such as glycerin fatty acid ester, polyglycerin, fatty acid ester, propylene glycol fatty acid ester, sorbitan fatty acid ester, and sorbitol fatty acid ester, Also, examples thereof include alkylene glycol adducts, polyalkylene glycol fatty acid esters, sucrose fatty acid esters, polysorbate 20, polysorbate 60, polysorbate 80, polyoxyalkylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and the like.

Materials normally used in cosmetics other than surfactants can also be added to external skin preparations as long as they do not impair viscosity.

(Preparation of test examples and reference examples)
<Test Examples 1 and 2>
Examples are shown below. Test Examples 1 and 2 were manufactured as follows. A dispersion in which fine fibrous cellulose (product "ELLEX (registered trademark)-S" manufactured by Daio Paper Co., Ltd.) is dispersed in water to a concentration of 2% by mass is supplied as a raw material to a spray freeze granulation device. Cellulose powder A was obtained. The average fiber diameter of the fine fibrous cellulose is 50 nm. The raw material is sprayed into a spray-type freezing granulator and subjected to freezing treatment to obtain a frozen intermediate, which is then vacuum-dried to obtain cellulose powder A. After obtaining a frozen body using a freeze granulation chamber CS30, a barrel freeze-drying unit "TFD-10" manufactured by Priss Co., Ltd. was used until the frozen mass was completely dried. , the frozen body was dried with rocking.

Put liquefied white petrolatum at 90°C (Ken'ei Pharmaceutical Co., Ltd., Japanese Pharmacopoeia) into a 100 ml container, add cellulose powder A to it, and stir with a stirrer (IKA-T25) at 8000 rpm for 3 minutes to mix. Thereafter, it was cooled to 5° C. in a refrigerator to obtain Test Example 1 and Test Example 2.

<Test Example 3>
Test Example 3 used a cellulose powder obtained by heating and drying fine fibrous cellulose, and was produced as follows. An aqueous dispersion of fine fibrous cellulose (“ELLEX (registered trademark)-S” manufactured by Daio Paper Co., Ltd.) with a concentration of 2% by mass was dried in a double drum dryer (“John Milder JM-T” manufactured by Johnson Boiler Co., Ltd.). A dried body was obtained by drying at a rotation speed of 3 rpm and a drum surface temperature of 135° C., and the dried body was pulverized to obtain cellulose powder B. The average particle diameter of the cellulose powder was 238.8 μm.

Put liquefied white petrolatum at 90°C into a 100ml container, add cellulose powder B to it, and mix with a stirrer (IKA-T25) at 8000 rpm for 3 minutes, then cool to 5°C in a refrigerator and test. Example 3 was obtained.

<Test Example 4>
Test Example 4 was produced as follows. An aqueous dispersion of fine fibrous cellulose ("ELLEX (registered trademark)-S" manufactured by Daio Paper Co., Ltd.) with a concentration of 2% by mass was spray-dried using a spray dryer ("TR-160" by Pris Co., Ltd.). , cellulose powder C was obtained. The average particle diameter of cellulose powder C was 10.1 μm.

Put liquefied white petrolatum at 90°C (Kenei Pharmaceutical Co., Ltd., Japanese Pharmacopoeia) into a 100ml container, add cellulose powder C to it, and stir with a stirrer (IKA-T25) at 8000 rpm for 3 minutes to mix. Thereafter, it was cooled to 5° C. in a refrigerator to obtain Test Example 4.

Physical properties, degree of compaction, loose bulk density, hardened bulk density, specific surface area, moisture content, average particle diameter, median diameter, cumulative 10% diameter, and cumulative 90% diameter were measured for each cellulose powder. The measurement results are shown in Table 1.

Although each cellulose powder was manufactured using the same fine fibrous cellulose as a raw material, it had different physical properties in terms of bulk density, specific surface area, and average particle diameter.

<Reference example 1>
As a reference example, white petrolatum to which cellulose powder A was not added was prepared and designated as reference example 1.

(Test 1: Type B viscosity measurement)
The B-type viscosity was measured for each of the above-mentioned test examples and reference examples. Table 2 shows the mixing ratio of cellulose powder and white petrolatum and the measurement results of type B viscosity. The measurement conditions for type B viscosity were a rotational speed of 3 rpm and a temperature of 35°C.

Here, the B-type viscosity was measured in accordance with "Liquid viscosity measurement method" of JIS-Z8803 (2011). Type B viscosity is the resistance torque when stirring a liquid, and the higher the viscosity, the more energy is required for stirring.

(Test 2: Sensory test)
A sensory test was conducted using the prepared test examples and reference examples. The contents of the sensory test are as follows. The test subjects applied the test example and the reference example to their own skin, and evaluated each item at that time. Specifically, the foreign body feeling, stickiness, and shine were evaluated with either 1, 2, or 3 points. The usability was evaluated by ranking Test Examples 1 to 4 from 1st to 4th. The subjects were 13 men and 31 women.

Evaluation was performed as follows, and the average value was calculated for each item.
Regarding the foreign body sensation, 3 points were given if there was no difference from Reference Example 1, 2 points were given if it was a little bothersome, and 1 point was given if it was painful or bothersome.
Regarding stickiness, the students were given 3 points if it was less sticky than Reference Example 1, 2 points if it was the same as Reference Example, and 1 point if it was stickier or worse than Reference Example.
Regarding shine, the participants were given 3 points if it was less shiny than Reference Example 1, 2 points if it was the same as Reference Example, and 1 point if it was more shiny or worse than Reference Example.
Regarding the feel of use, Test Examples 1 to 4 were ranked 1st to 4th (with 1st place being the best in use feeling and 4th place being the worst in use feeling) and evaluated. 1st place gets 1 point, 2nd place gets 2 points, 3rd place gets 3 points, and 4th place gets 4 points.
The evaluation results are shown in Table 3. The scores shown in Table 3 are average scores obtained by averaging the evaluations of all subjects.

Regarding stickiness, Test Examples 1 to 4 gave results that seemed to be equivalent to or improved from Reference Example 1. Regarding shine, Test Examples 1 to 4 gave results that seemed to be equivalent to or improved from Reference Example 1.

(Test 3: Skin application test)
A skin application test was conducted on the test examples and reference examples. In the skin application test, one of Test Examples 1 to 4 and Reference Example 1 was applied to artificial skin (Beaulux product "Bio Skin Plate H077-002 296 mm x 213 mm x 5 mm" cut into 10 cm long and 5 cm wide). 1 g was taken and applied evenly to the same area, and observed after 5 minutes. The results are shown in FIG.

It was confirmed that test example 1 suppressed shine the most.

(others)
Unless otherwise specified, JIS, TAPPI, and other tests and measurement methods shown in the above specification are performed at room temperature, especially 25° C., and atmospheric pressure, especially 1 atm.

The present invention can be used for external preparations for the skin.

1 Spray type freeze granulation device 2 Inner tank wall 3 Inner tank wall 4 Outer tank wall 4a Flange part 5 Nozzle 6 Drying part 7 Spraying mechanism part 8 Freeze granulation tank 11 Cellulose powder 11a Cellulose powder hole 11' Cellulose powder 11' a Cellulose powder holes 12 Freezing tank 13 Cooling medium filling tank 14 Vacuum insulation tank 15 Cooling medium supply pipe 16 Cooling medium introduction pipe 21 Gas pipe 22 Cooling trap 23 Gas pipe 24 Vacuum pump 100 Dryer

Claims

Contains petrolatum and cellulose powder,
The cellulose powder is made by agglomerating fine fibrous cellulose with an average fiber diameter of 1 to 1000 nm, has an average particle diameter of 1 to 500 μm, and has a loose bulk density of 0.1 to 300 mg/cm 3 ,
Type B viscosity is 50,000 to 200,000 mPa·s under measurement conditions of 35°C and rotation speed of 3 rpm.
A skin external preparation characterized by:
The solidifying temperature is 36 to 60°C.
The skin external preparation according to claim 1.
the petrolatum is white petrolatum;
The skin external preparation according to claim 1.
The cellulose powder is contained in an amount of 0.1 to 10% by mass.
The skin external preparation according to claim 1.
The moisture content of the cellulose powder is 0.1 to 30%,
The skin external preparation according to claim 1.
The cellulose powder has a specific surface area of 0.1 to 1000 m 2 /g,
The skin external preparation according to claim 1.
The cellulose powder is one in which inorganic fine particles are supported.
The skin external preparation according to claim 1.
the cellulose powder is white or pale yellow;
The skin external preparation according to claim 1.
Contains additives
the additive is a water-retaining polymer or a polyhydric alcohol;
The skin external preparation according to claim 1.
the cellulose powder is porous;
The skin external preparation according to claim 1.