JP2022157453A - Natural rubber particle and method for producing the same, and cosmetic - Google Patents
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Landscapes
- Cosmetics (AREA)
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Abstract
Description
本発明は、高い弾性と良好な生分解性を持つ天然ゴム粒子、およびその製造方法に関する。 TECHNICAL FIELD The present invention relates to natural rubber particles having high elasticity and good biodegradability, and a method for producing the same.
現在、石油由来の合成高分子（プラスチック）は、さまざまな産業で利用されている。合成高分子は、長期安定性を求めて開発されることが多く、自然環境中で分解されない。そのため、様々な環境問題が起こっている。例えば、水環境に流出したプラスチック製品が長い期間蓄積され、海洋や湖沼の生態系が大きな影響を受けている。また、近年、長さが５ｍｍ以下からｎｍレベルまでのマイクロプラスチックが大きな問題となっている。マイクロプラスチックに該当するものとして、化粧用品等に含まれる微粒子、加工前のプラスチック樹脂の小さな塊、大きな製品が海中で浮遊するうちに微細化した物、等が挙げられている。 Currently, petroleum-derived synthetic polymers (plastics) are used in various industries. Synthetic polymers are often developed for long-term stability and do not degrade in the natural environment. As a result, various environmental problems have arisen. For example, plastic products that have flowed into the water environment have accumulated over a long period of time, greatly affecting marine and lake ecosystems. In recent years, microplastics with a length of 5 mm or less to nm level have become a big problem. Examples of microplastics include fine particles contained in cosmetic products, small lumps of plastic resin before processing, and substances that become finer as large products float in the sea.
プラスチック粒子は、真比重が軽いため下水処理場で除去し難く、河川、海洋、池沼等に流れ出易い。更に、プラスチック粒子は、殺虫剤等の化学物質を吸着し易いため、生物濃縮により人体に影響を与えるおそれがある。このことは国連環境計画等でも指摘されており、各国、各種業界団体が規制を検討している。例えば、化粧品の自然・オーガニック指数表示に関するガイドライン（ＩＳＯ１６１２８）が制定されている。このガイドラインによれば、製品中の原料を、自然原料、自然由来原料、非自然原料に分類し、各原料の含有量に基づいて指数が算出される。既に、商品にこの指数が表示されるようになっており、自然由来原料、更に、自然原料が要求されている。 Since plastic particles have a low true specific gravity, they are difficult to remove at sewage treatment plants and easily flow into rivers, oceans, ponds, and the like. Furthermore, plastic particles tend to adsorb chemical substances such as insecticides, which may affect the human body through bioaccumulation. This has been pointed out by the United Nations Environment Program, etc., and various countries and industry groups are considering regulations. For example, a guideline (ISO16128) has been enacted for the display of natural/organic indices for cosmetics. According to this guideline, raw materials in products are classified into natural raw materials, naturally derived raw materials, and non-natural raw materials, and an index is calculated based on the content of each raw material. This index is already being displayed on products, and there is a demand for naturally derived raw materials, and even more natural raw materials.
このような背景から、自然環境中で微生物等により水と二酸化炭素に分解され、自然界の炭素サイクルに組み込まれる生分解性プラスチックが注目されている。特に、植物由来の自然原料であるセルロース粒子は、環境に流出しても水に浮くことがなく、また、良好な生分解性を持つため、環境問題を引き起こす懸念が少ない。例えば、良好な生分解性を持つＩ型セルロースで形成された多孔質セルロース粒子が知られている（例えば、特許文献１を参照）。この粒子を化粧料に配合すると、良好な感触特性が得られる。また、生分解性、触感および親油性に優れたセルロースアセテートを含む粒子が知られている（例えば、特許文献２を参照）。さらに、アミロペクチンの含有量が９０重量％以上の生分解性に優れた澱粉粒子が知られている（例えば、特許文献３を参照）。 Against this background, biodegradable plastics, which are decomposed into water and carbon dioxide by microorganisms or the like in the natural environment and incorporated into the carbon cycle of the natural world, have attracted attention. In particular, cellulose particles, which are natural raw materials derived from plants, do not float on water even if they are discharged into the environment, and have good biodegradability, so there is little concern about causing environmental problems. For example, porous cellulose particles made of type I cellulose having good biodegradability are known (see, for example, Patent Document 1). When these particles are blended into cosmetics, good tactile properties can be obtained. Particles containing cellulose acetate, which are excellent in biodegradability, tactile feel and lipophilicity, are also known (see, for example, Patent Document 2). Furthermore, starch particles having an amylopectin content of 90% by weight or more and having excellent biodegradability are known (see, for example, Patent Document 3).
これらの特許文献に開示された粒子は、生分解に優れ、ＰＭＭＡやＮｙｌｏｎ等のプラスチックビーズと同様なソフトで滑らかな感触特性を具備している。しかし、素材そのものが比較的硬質であることから、高い弾性が得られず、シリコーンビーズやポリウレタンビーズの代替材料としては適さない。 The particles disclosed in these patents are highly biodegradable and have soft, smooth tactile properties similar to plastic beads such as PMMA and Nylon. However, since the material itself is relatively hard, high elasticity cannot be obtained, and it is not suitable as a substitute material for silicone beads or polyurethane beads.
そこで、本発明の目的は、高い弾性と良好な生分解性を持つ天然素材の粒子を実現することにある。 SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide particles of natural materials with high elasticity and good biodegradability.
本発明による天然ゴム粒子は、平均粒子径ｄ１が０．０１～２０μｍ、最大粒子径ｄ２は３０μｍ未満かつ、平均粒子径ｄ１の３．０倍以内であり、ＣＶ値が４０％未満、真球度が０．８０以上、硝子転移温度が－５３～１０℃である。 The natural rubber particles according to the present invention have an average particle diameter d1 of 0.01 to 20 μm, a maximum particle diameter d2 of less than 30 μm and within 3.0 times the average particle diameter d1, and a CV value of less than 40%. , a sphericity of 0.80 or more, and a glass transition temperature of -53 to 10°C.
本発明による天然ゴム粒子の製造方法は、未架橋の天然ゴムラテックスを含む溶液にアルカリ成分を加え、脂質を加水分解して精製天然ゴムの固体を得る精製工程と、精製天然ゴムに有機溶媒を加え、精製天然ゴムを溶解させて溶解液を得る工程と、溶解液と界面活性剤と水を混合して、乳化液滴を含む乳化液を調製する工程と、乳化液に電離放射線を照射して天然ゴム粒子を架橋させる架橋工程と、乳化液滴から有機溶媒を除去する有機溶媒除去工程と、架橋工程と有機溶媒除去工程を経て得られた水分散体を固液分離して天然ゴム粒子を固形物として得る固液分離工程と、を備えている。 The method for producing natural rubber particles according to the present invention comprises a purification step of adding an alkaline component to a solution containing uncrosslinked natural rubber latex to hydrolyze lipids to obtain a purified natural rubber solid, and adding an organic solvent to the purified natural rubber. In addition, a step of dissolving the purified natural rubber to obtain a solution, a step of mixing the solution, a surfactant and water to prepare an emulsion containing emulsified droplets, and a step of irradiating the emulsion with ionizing radiation. A cross-linking step of cross-linking the natural rubber particles by means of a squeegee, an organic solvent-removing step of removing the organic solvent from the emulsified droplets, and a solid-liquid separation of the aqueous dispersion obtained through the cross-linking step and the organic solvent-removing step to obtain natural rubber particles. and a solid-liquid separation step of obtaining as a solid.
また、乳化液から有機溶媒を除去した後に、架橋工程を行ってもよい。 Further, the cross-linking step may be performed after removing the organic solvent from the emulsion.
本発明は、天然ゴム成分を架橋させて形成した天然ゴム粒子に関し、平均粒子径ｄ１が０．０１～２０μｍ、最大粒子径ｄ２が３０μｍ未満、粒径比（ｄ２／ｄ１）が３．０以内、粒子変動係数が４０％未満、真球度が０．８０以上、硝子転移温度が－５３～１０℃である。このような粒子は、高い弾性と良好な生分解性を持っている。 The present invention relates to natural rubber particles formed by cross-linking a natural rubber component, having an average particle size d1 of 0.01 to 20 μm, a maximum particle size d2 of less than 30 μm, and a particle size ratio ( d2 / d1) of 3.0 or less, the particle variation coefficient is less than 40%, the sphericity is 0.80 or more, and the glass transition temperature is -53 to 10°C. Such particles have high elasticity and good biodegradability.
粒子の形状は粉体の感触特性に影響を与える。平均粒子径ｄ１が２０μｍより大きい粒子、あるいは、最大粒子径ｄ２が３０μｍ以上の粒子では、ざらつきが感じられ、ソフト感としっとり感が低下する。最大粒子径が平均粒子径の３．０倍を超えると、均一な延び広がり性が低下する。平均粒子径ｄ１が０．０１μｍ未満の粒子は、工業的に製造することが難しい。粒子（粉体）を感触改良材として用いる場合、平均粒子径ｄ１は１～２０μｍが好ましく、５～１５μｍが最適である。１μｍ未満では、転がり感、転がり感の持続性、均一な延び広がり性等の感触特性が低下する。平均粒子径ｄ１が０．０１～１μｍ未満の粒子は、光散乱効果が高いため、ソフトフォーカス材料として好適である。 The shape of the particles influences the tactile properties of the powder. Particles with an average particle diameter d1 of more than 20 μm or particles with a maximum particle diameter d2 of 30 μm or more give a rough feel, and the softness and moistness are reduced. When the maximum particle size exceeds 3.0 times the average particle size, the uniform spreadability is deteriorated. Particles having an average particle diameter d1 of less than 0.01 μm are difficult to industrially produce. When particles (powder) are used as a feel improving material, the average particle diameter d1 is preferably 1 to 20 μm, most preferably 5 to 15 μm. If the thickness is less than 1 μm, the tactile properties such as the rolling feel, the durability of the rolling feel, and the uniform spreadability are deteriorated. Particles having an average particle diameter d 1 of 0.01 to less than 1 μm have a high light scattering effect and are suitable as a soft focus material.
また、粒子変動係数（ＣＶ値）が４０％未満である。粒子変動係数が４０％以上だと、均一な転がり性が得られないおそれがある。粒子変動係数は、３０％以下が好ましい。なお、粒子変動係数は、小さいほど好適であるものの、狭小分布の粒子を得ることは工業的に困難である。概ね３％以上であれば、特に問題なく製造できる。 Also, the particle variation coefficient (CV value) is less than 40%. If the coefficient of variation of particles is 40% or more, there is a possibility that uniform rolling performance cannot be obtained. The particle variation coefficient is preferably 30% or less. Although the smaller the particle variation coefficient, the better, it is industrially difficult to obtain particles with a narrow distribution. If it is about 3% or more, it can be produced without any particular problem.
また、硝子転移温度は天然ゴムの架橋の程度に関係する。硝子転移温度が－５３℃より低い状態の天然ゴムは、架橋が十分進んでおらず、粘着性があるため、粉体（粒子）として取り出すことができない。架橋が進み１０℃以上になると弾性が低下すると共に、生分解性が低下してしまう。硝子転移温度は、－５０～０℃が好ましく、－４０～－１０℃が最適である。 Also, the glass transition temperature is related to the degree of cross-linking of natural rubber. Natural rubber having a glass transition temperature lower than −53° C. is not sufficiently crosslinked and is sticky, so that it cannot be taken out as powder (particles). When the cross-linking progresses and the temperature rises to 10°C or higher, the elasticity and biodegradability of the polymer are lowered. The glass transition temperature is preferably -50 to 0°C, most preferably -40 to -10°C.
真球度は０．８０以上である。真球度が高いほど粉体（粒子）の転がり感が向上する。真球度は０．９０以上が特に好ましい。 The sphericity is 0.80 or more. The higher the sphericity, the better the rolling feel of the powder (particles). A sphericity of 0.90 or more is particularly preferable.
さらに、タンパク質の含有量は１０ｐｐｍ未満が好ましい。タンパク質による即時型アレルギー（ラテックスアレルギー）を発症させる虞が少ない。さらに、リン脂質由来のリンの含有量は１００ｐｐｍ未満が好ましい。また、脂肪酸を含まないことが好ましい。臭気、菌の増殖、変質、腐敗を抑制することができる。天然ゴム粒子の赤外線吸収スペクトルにおいて、脂肪酸に特有な１７１０ｃｍ－１付近の吸収、および脂肪酸エステルに特有な１７４０ｃｍ－１付近の吸収が実質的に認められなければ、脂肪酸を含んでいないと判断できる。 Furthermore, the protein content is preferably less than 10 ppm. There is little risk of developing immediate-type allergy (latex allergy) due to protein. Furthermore, the content of phosphorus derived from phospholipids is preferably less than 100 ppm. Moreover, it is preferable not to contain a fatty acid. It can suppress odors, growth of bacteria, deterioration, and putrefaction. In the infrared absorption spectrum of natural rubber particles, if absorption around 1710 cm −1 specific to fatty acids and absorption around 1740 cm −1 specific to fatty acid esters are not substantially observed, it can be determined that the particles do not contain fatty acids.
分子構造がシス型の天然ゴムを成分として粒子を構成することにより、高い弾性が得られる。シス型の天然資源として、パラゴムノキ、グアユール、ロシアタンポポ等が例示できる。トランス型のアラビアゴムから得られる粒子では、高い弾性が得られないおそれがある。 High elasticity can be obtained by forming the particles with natural rubber having a cis-type molecular structure as a component. Examples of cis-type natural resources include Hevea brasiliensis, guayule, and Russian dandelion. Particles obtained from trans-type gum arabic may not provide high elasticity.
架橋した天然ゴムは、未架橋の天然ゴムに比べて生分解速度が遅い。しかし、本発明の天然ゴム粒子は、粒径が微細であり、比表面積が大きい。そのため、ＯＥＣＤ ＴＧ３０１Ｆ（易分解性）による生分解性試験で２８日間暴露すると、６０％以上が分解される。このような天然ゴム粒子は、欧州化学物質庁が提案するマイクロプラスチックスの定義案に該当しない。 Crosslinked natural rubber has a slower biodegradation rate than uncrosslinked natural rubber. However, the natural rubber particles of the present invention have a fine particle size and a large specific surface area. Therefore, 60% or more is degraded after 28 days of exposure in a biodegradability test according to OECD TG301F (readily degradable). Such natural rubber particles do not fall under the proposed definition of microplastics proposed by the European Chemicals Agency.
また、天然ゴムの比重は、水よりも軽く、水に浮きやすい。そのため、排水処理設備で除去できず、環境中にそのまま放出されることが懸念される。しかし、天然ゴムは光分解性を有しているので、自然界における物質循環のサイクルに組み込まれやすい。 Moreover, the specific gravity of natural rubber is lighter than that of water, and it easily floats on water. Therefore, it is feared that they cannot be removed by wastewater treatment facilities and are discharged into the environment as they are. However, since natural rubber is photodegradable, it is easily incorporated into the cycle of material circulation in the natural world.
また、天然ゴム粒子は疎水性であるが、表面処理を行って親水性とすることにより、水系の化粧料に配合することができる。表面処理方法は、天然ゴム粒子の表面を親水性に改質できる方法であればよく、例えば、ＨＬＢ値が８～１８のノニオン系またはアニオン系界面活性剤処理、アミノ酸やリポアミノ酸処理、アルギン酸やポリアクリル酸等の水溶性高分子処理などが挙げられる。 Although natural rubber particles are hydrophobic, they can be blended in water-based cosmetics by surface-treating them to make them hydrophilic. The surface treatment method may be any method as long as it can modify the surface of the natural rubber particles to be hydrophilic. Treatment with a water-soluble polymer such as polyacrylic acid may be mentioned.
＜天然ゴム粒子の製造方法＞
はじめに、未架橋の天然ゴムラテックス溶液にアルカリを加えて、脂質を加水分解し、水洗する。これに酸を加えて、ラテックスを凝固させた後、更に水洗して乾燥する（精製工程）。これにより、脂質が低減された精製天然ゴムの固体が得られる。次に、この天然ゴムの固体を有機溶媒に加えて、完全に透明になるまで溶解する（溶解工程）。これにより天然ゴムが有機溶媒に溶解した溶液が得られる。次に、この溶液と界面活性剤と水を混合して、乳化液滴を含む乳化液を調製する（乳化工程）。これにより、天然ゴムが有機溶媒に溶解した溶液が内層、水が外層からなる乳化液滴を含むＯ／Ｗ乳化液が得られる。この乳化液に電離放射線を照射して、天然ゴムを架橋させる（架橋工程）。これにより、天然ゴムの構成成分（鎖状ポリイソプレン）が架橋した三次元の網目構造体が得られる。続いて、Ｏ／Ｗ乳化液中の乳化液滴から有機溶媒を除去する（有機溶媒除去工程）。これにより架橋された天然ゴム粒子の水分散体が得られる。次に、この水分散体を固液分離し、更に水洗して、ケーキ状物質を取り出す（固液分離工程）。次に、このケーキ状物質を乾燥し、解砕して天然ゴム粒子の粉体が得られる（乾燥工程）。ここで、架橋工程と有機溶媒除去工程の順を入れ替えてもよい。すなわち、乳化工程で得られた乳化液から有機溶媒を除去した後に、電離放射線を照射してもよい。
<Method for producing natural rubber particles>
First, an alkali is added to an uncrosslinked natural rubber latex solution to hydrolyze the lipids, followed by washing with water. Acid is added to this to coagulate the latex, which is then washed with water and dried (refining step). This results in a refined natural rubber solid with reduced lipids. The natural rubber solid is then added to an organic solvent and dissolved until completely transparent (dissolution step). As a result, a solution of natural rubber dissolved in an organic solvent is obtained. Next, this solution, a surfactant, and water are mixed to prepare an emulsified liquid containing emulsified droplets (emulsification step). As a result, an O/W emulsion containing emulsified droplets having an inner layer of a solution of natural rubber dissolved in an organic solvent and an outer layer of water is obtained. The emulsified liquid is irradiated with ionizing radiation to crosslink the natural rubber (crosslinking step). As a result, a three-dimensional network structure in which natural rubber constituents (chain polyisoprene) are crosslinked is obtained. Subsequently, the organic solvent is removed from the emulsified droplets in the O/W emulsion (organic solvent removal step). An aqueous dispersion of crosslinked natural rubber particles is thereby obtained. Next, this aqueous dispersion is subjected to solid-liquid separation and further washed with water to take out a cake-like substance (solid-liquid separation step). Next, this cake-like substance is dried and pulverized to obtain a powder of natural rubber particles (drying step). Here, the order of the cross-linking step and the organic solvent removal step may be changed. That is, the ionizing radiation may be applied after removing the organic solvent from the emulsified liquid obtained in the emulsifying step.
以下、各工程を詳細に説明する。 Each step will be described in detail below.
［精製工程］
未架橋の天然ゴムラテックスにアルカリを加えて、室温～２００℃に加熱して脂質を加水分解する。天然ゴムラテックスは、ゴムノキ等の樹液に含まれるシス－ポリイソプレンを主成分としている。さらに、タンパク質、脂肪酸、リン脂質などの非ゴム成分を約６重量％含んでいる。脂質を低減することにより、以降の溶解工程で有機溶媒に不溶なゲル成分が少なくなり、収率が向上する。ここで用いるアルカリとして、アンモニア、水酸化ナトリウム、水酸化カリウムが例示できる。アルカリの濃度は高いほど効果的であり、５％以上が好ましい。
[Purification process]
Alkali is added to uncrosslinked natural rubber latex and heated to room temperature to 200° C. to hydrolyze lipids. Natural rubber latex is mainly composed of cis-polyisoprene contained in the sap of rubber trees and the like. Furthermore, it contains about 6% by weight of non-rubber components such as proteins, fatty acids and phospholipids. By reducing the lipid content, the amount of gel components insoluble in organic solvents is reduced in the subsequent dissolution step, and the yield is improved. Examples of the alkali used here include ammonia, sodium hydroxide, and potassium hydroxide. The higher the alkali concentration is, the more effective it is, and 5% or more is preferable.
加水分解後、限外濾過、遠心分離等によりゴム成分と脂質の分離を行う。次いで、鉱酸等の酸性成分を加えて、ゴム成分を固液分離して水洗する。その後、真空乾燥を行って天然ゴムの固形物を得る。 After hydrolysis, the rubber component and lipids are separated by ultrafiltration, centrifugation, or the like. Next, an acidic component such as a mineral acid is added, and the rubber component is solid-liquid separated and washed with water. After that, vacuum drying is performed to obtain a natural rubber solid.
また、市場には、天然ゴムラテックスにアンモニアを加えて、遠心分離等で６０％程度に濃縮した製品が流通しており、これを原料に用いてもよい。 In the market, a product obtained by adding ammonia to natural rubber latex and concentrating it to about 60% by centrifugation or the like is distributed, and this may be used as a raw material.
さらに、酵素を用いた酵素処理、変性剤を用いた変性処理、アセトン等での抽出により、タンパク質を低減することが望ましい。市場には、脱タンパク天然ゴムラテックス（例えば、酵素処理されたラテックス（住友ゴム工業社製セラテックス）、水酸化アルミニウム処理されたラテックス（泰国ＭＭＧポリマー製）等が流通しており、これを利用してもよい。残留タンパク質を１％未満に低減したものが好ましい。他方、固形ゴムとして流通しているシート状（視覚的格付けゴム）、ブロック状（技術的格付けゴム）のゴムは、非ゴム成分が多く含まれており、精製が困難である。 Furthermore, it is desirable to reduce proteins by enzymatic treatment using an enzyme, denaturation treatment using a denaturing agent, or extraction with acetone or the like. In the market, deproteinized natural rubber latex (e.g., enzyme-treated latex (Sumitomo Rubber Industries, Ltd., Ceratex), aluminum hydroxide-treated latex (manufactured by MMG Polymer, Thailand), etc. are distributed. It is preferable to reduce the residual protein to less than 1%.On the other hand, the sheet-like (visually graded rubber) and block-shaped (technically graded rubber) rubbers distributed as solid rubbers are non-rubber It contains many components and is difficult to purify.
［溶解工程］
次に、天然ゴムの固形物を有機溶媒中に加えて、室温から溶媒の沸点以下に加熱して溶解させる。有機溶媒のＳＰ値は、６～１０（天然ゴムのＳＰ値８に対して、おおよそ±２の範囲）が好ましい。シクロへサン等が好適である。ゲル成分は、オートクレーブ中で高温、高圧をかけても溶解しない。そのため、溶解液を限外濾過し、ゲルを分離する。これにより、透明な天然ゴム溶解液を得る。なお、タンパク質と脂質は水溶性なので、この限外濾過により低減できる。天然ゴム溶解液中の固形分は５０％以上が経済的である。
[Dissolving process]
Next, the natural rubber solid is added to an organic solvent and heated from room temperature to the boiling point of the solvent or below to dissolve. The SP value of the organic solvent is preferably 6 to 10 (with respect to the SP value of 8 for natural rubber, the range is approximately ±2). Cyclohexane and the like are preferred. The gel component does not dissolve at high temperatures and high pressures in an autoclave. Therefore, the lysate is ultrafiltered to separate the gel. Thereby, a transparent natural rubber solution is obtained. Since proteins and lipids are water-soluble, they can be reduced by this ultrafiltration. A solid content of 50% or more in the natural rubber solution is economical.
［乳化工程］
天然ゴム溶解液と水と界面活性剤を混合する。界面活性剤は、Ｏ／Ｗ型の乳化液滴を形成するために添加される。界面活性剤のＨＬＢ値は８～１８が適している。次に、この混合溶液を乳化装置により乳化させる。この時、平均径が、約０．０２～４０μｍの乳化液滴を含む乳化液が得られるように、乳化条件を設定する。乳化液滴中には天然ゴム溶解液が存在している。乳化装置には、一般的な高速せん断装置を用いることができる。その他にも、より微細なナノサイズの乳化液滴が得られる高圧乳化装置、より均一な乳化液滴が得られる膜乳化装置、マイクロチャネル乳化装置等の公知の装置を目的に応じて適用できる。
[Emulsification process]
A natural rubber solution, water and a surfactant are mixed. A surfactant is added to form O/W type emulsified droplets. A suitable HLB value for the surfactant is 8-18. Next, this mixed solution is emulsified by an emulsifier. At this time, the emulsification conditions are set so as to obtain an emulsified liquid containing emulsified droplets with an average diameter of about 0.02 to 40 μm. A natural rubber solution is present in the emulsified droplets. A common high-speed shearing device can be used for the emulsifying device. In addition, known devices such as a high-pressure emulsifier capable of obtaining finer nano-sized emulsified droplets, a membrane emulsifier capable of obtaining more uniform emulsified droplets, and a microchannel emulsifier can be applied depending on the purpose.
なお、乳化液滴の平均径は次のように測定した。乳化液をスライドガラスに滴下し、その上からカバーガラスを被せる。デジタルマイクロスコープ（キーエンス社製、ＶＨＸ－６００）により、カバーガラス越しに３０倍から２０００倍の倍率で撮影し、乳化液滴の写真投影図を得る。この写真投影図から、５０個の液滴を任意に選び、付属のソフトウェアにて円相当径を算出する。それら５０個の円相当径の平均値を平均径（平均液滴径）とした。 The average diameter of emulsified droplets was measured as follows. An emulsified liquid is dropped onto a slide glass, and a cover glass is placed thereon. Using a digital microscope (VHX-600, manufactured by Keyence Corporation), images are taken through a cover glass at a magnification of 30 to 2000 times to obtain a photographic projection of the emulsified droplets. 50 droplets are arbitrarily selected from this photographic projection, and the equivalent circle diameter is calculated by the attached software. The average value of these 50 equivalent circle diameters was taken as the average diameter (average droplet diameter).
［架橋工程］
この乳化液を金属製容器に入れ、電離放射線を照射する。未架橋の天然ゴムの硝子転移温度に対して、約１０℃上昇する程度に電離放射線を照射すると、粒子の粘着性が抑えられ、粉体として取り出せるようになる。また、電離放射線の照射により、残留している非ゴム成分が分解し、水層に移行する。そのため、天然ゴムの純度が高くなる。電離放射線は、ｘ線、γ線、電子線のいずれかを適用し、照射線量は、５０～５００ｋＧｙの範囲が好ましい。５０ｋＧｙ未満の場合、架橋が未発達なため、乳液を固液分離した際、ゴム粒子同士が粘着して固まりとなり、個別の粉体として取り出すことができない。また、５００ｋＧｙを超えると架橋密度が高すぎて、弾性が低下すると共に、生分解速度が低下する。
[Crosslinking step]
This emulsion is placed in a metal container and irradiated with ionizing radiation. When the ionizing radiation is irradiated to such an extent that the glass transition temperature of the uncrosslinked natural rubber is increased by about 10° C., the stickiness of the particles is suppressed and the particles can be taken out as powder. In addition, the remaining non-rubber components are decomposed by irradiation with ionizing radiation and migrate to the water layer. Therefore, the purity of natural rubber is increased. As the ionizing radiation, any one of x-rays, γ-rays, and electron beams is applied, and the irradiation dose is preferably in the range of 50 to 500 kGy. If the amount is less than 50 kGy, the cross-linking is underdeveloped, so when the emulsion is subjected to solid-liquid separation, the rubber particles adhere to each other to form lumps, which cannot be taken out as individual powders. On the other hand, when it exceeds 500 kGy, the cross-linking density is too high, and the elasticity is lowered and the biodegradation rate is lowered.
また、前述の乳化を希薄系にて行い、これに電離放射線を照射すると、より高い弾性の粒子が得られる。なお、この架橋工程で天然ゴム粒子の硝子転移温度を調整することができる。金属製容器は２００Ｌドラム缶がハンドリング上も好適である。 Further, if the emulsification described above is carried out in a dilute system and then irradiated with ionizing radiation, particles with higher elasticity can be obtained. In addition, the glass transition temperature of the natural rubber particles can be adjusted in this cross-linking step. A 200L drum can is suitable for handling as a metal container.
［有機溶媒除去工程］
架橋工程で得られた乳化液から有機溶媒を除去する。常圧または減圧下で加熱することにより、有機溶媒を蒸発させる。これにより、乳化液滴から有機溶媒が除去され、粒子径０．０２～４０μｍ程度の天然ゴム粒子を含む水分散体が得られる。
[Organic solvent removal step]
The organic solvent is removed from the emulsion obtained in the cross-linking step. The organic solvent is evaporated by heating under normal or reduced pressure. As a result, the organic solvent is removed from the emulsified droplets, and an aqueous dispersion containing natural rubber particles having a particle size of about 0.02 to 40 μm is obtained.
例えば、常圧下の加熱除去法では、冷却管を備えたセパラブルフラスコを加熱し、有機溶媒を取り除く。また、減圧下の加熱除去法では、ロータリーエバポレーターや蒸発缶等用いて減圧加熱し、有機溶媒を取り除く。 For example, in the heat removal method under normal pressure, a separable flask equipped with a cooling tube is heated to remove the organic solvent. In addition, in the heat removal method under reduced pressure, the organic solvent is removed by heating under reduced pressure using a rotary evaporator, an evaporator, or the like.
［固液分離工程］
次に、有機溶媒除去工程で得られた水分散体から、公知の濾過、遠心分離等の方法により固形分を分離する。これにより、天然ゴム粒子のケーキ状物質が得られる。得られたケーキ状物質を洗浄することにより、界面活性剤を低減できる。天然ゴム粒子を乳化物等の液体製剤に配合する場合、界面活性剤が長期安定性を阻害するおそれがある。そのため、天然ゴム粒子に含まれる界面活性剤の残留量は１００ｐｐｍ以下が好ましい。界面活性剤を低減するためには、有機溶媒を用いて洗浄すると良い。
[Solid-liquid separation step]
Next, solid content is separated from the aqueous dispersion obtained in the organic solvent removal step by a known method such as filtration or centrifugation. As a result, a cake-like material of natural rubber particles is obtained. Surfactants can be reduced by washing the obtained cake-like substance. When blending natural rubber particles into a liquid formulation such as an emulsion, the surfactant may impede long-term stability. Therefore, the residual amount of the surfactant contained in the natural rubber particles is preferably 100 ppm or less. In order to reduce the amount of surfactant, it is preferable to wash with an organic solvent.
［乾燥工程］
乾燥工程では、常圧または減圧下での加熱により、固液分離工程で得られたケーキ状物質に含まれる水分を蒸発させる。その後、ミキサー等で解砕することで、平均粒子径０．０１～２０μｍの天然ゴム粒子の粉体が得られる。
[Drying process]
In the drying step, the water contained in the cake-like substance obtained in the solid-liquid separation step is evaporated by heating under normal pressure or reduced pressure. Then, by pulverizing with a mixer or the like, a powder of natural rubber particles having an average particle size of 0.01 to 20 μm is obtained.
＜化粧料＞
上述の天然ゴム粒子と各種化粧料成分を配合して化粧料を調製できる。このような化粧料によれば、シリコーンビーズやポリウレタンビーズと同様な柔軟性が感じられる。同時に、天然ゴム粒子の粉体が持つ優れた感触特性（転がり感、転がり感の持続性、および均一な延び広がり性、ソフト感としっとり感）を得ることができる。すなわち、化粧料の感触改良材に求められる代表的な感触特性を満たすことができる。感触改良材としては、平均粒子径ｄ１が１～２０μｍの天然ゴム粒子が特に適している。
<Cosmetics>
Cosmetics can be prepared by blending the above natural rubber particles and various cosmetic ingredients. With such a cosmetic, the same softness as silicone beads or polyurethane beads can be felt. At the same time, it is possible to obtain the excellent tactile characteristics (rolling feeling, durability of rolling feeling, uniform spreadability, soft feeling and moist feeling) of the powder of natural rubber particles. That is, it is possible to satisfy the typical feel properties required for feel improvers for cosmetics. Natural rubber particles having an average particle size d1 of 1 to 20 μm are particularly suitable as feel improvers.
具体的な化粧料を表１に分類別に例示する。このような化粧料は、従来の一般的な方法で製造できる。化粧料は、粉末状、ケーキ状、ペンシル状、スティック状、クリーム状、ジェル状、ムース状、液状、クリーム状等の各種形態で使用される。 Specific cosmetics are exemplified in Table 1 by category. Such cosmetics can be produced by conventional general methods. Cosmetics are used in various forms such as powder, cake, pencil, stick, cream, gel, mousse, liquid and cream.
各種化粧料成分として代表的な分類や成分を表２に例示する。さらに、医薬部外品原料規格２００６（発行：株式会社薬事日報社、平成１８年６月１６日）や、International Cosmetic Ingredient Dictionary and Handbook（発行：The Cosmetic, Toiletry, and Fragrance Association、Eleventh Edition2006）等に収載されている化粧料成分を配合してもよい。 Table 2 shows representative classifications and components of various cosmetic ingredients. In addition, the Standards for Quasi-drug Ingredients 2006 (published by Yakuji Nippo Co., Ltd., June 16, 2006), International Cosmetic Ingredient Dictionary and Handbook (published by The Cosmetic, Toiletry, and Fragrance Association, Eleventh Edition 2006), etc. You may mix the cosmetic ingredients listed in.
以下、本発明の実施例を具体的に説明する。 Examples of the present invention will be specifically described below.
［実施例１］
天然ゴムラテックスとして脱タンパク天然ゴム（住友ゴム工業社製ＳＥＬＡＴＥＸ－１１０１）を用いた。これを純水で希釈してゴム濃度を３０重量％とし、これに水酸化ナトリウムを濃度が５％となるように加えた。得られた水分散液のｐＨは１３．５であった。この水分散液を４０℃に加温し、２４時間攪拌し、脂質を加水分解した。次いで、限外濾過膜を用いて、電気伝導度が１０ｍＳ／ｍ以下になるまで洗浄した。次に、ロータリーエバポレーターを用いて真空乾燥して、精製天然ゴムの固体を得た。
[Example 1]
Deproteinized natural rubber (SELATEX-1101 manufactured by Sumitomo Rubber Industries, Ltd.) was used as the natural rubber latex. This was diluted with pure water to give a rubber concentration of 30% by weight, and sodium hydroxide was added to give a concentration of 5%. The resulting aqueous dispersion had a pH of 13.5. The aqueous dispersion was heated to 40° C. and stirred for 24 hours to hydrolyze the lipids. Then, using an ultrafiltration membrane, it was washed until the electrical conductivity became 10 mS/m or less. Next, vacuum drying was performed using a rotary evaporator to obtain a purified natural rubber solid.
この固体にシクロヘキサンを加えて固形分５０重量％とした後、６０℃で２時間攪拌を行い、透明な天然ゴムの溶解液を得た。 Cyclohexane was added to this solid to adjust the solid content to 50% by weight, and the mixture was stirred at 60° C. for 2 hours to obtain a transparent solution of natural rubber.
この溶解液２００ｇに水３３４６ｇと界面活性剤（花王社製レオドールＴＷ－Ｏ１２０Ｖ）２５ｇの混合溶液に加えた。この混合溶液を、乳化分散機（プライミクス社製Ｔ．Ｋ．ロボミックス）を用いて１００００ｒｐｍで１０分間撹拌した。これにより乳化され、乳化液滴を含む乳化液が得られた。 To 200 g of this solution was added a mixed solution of 3346 g of water and 25 g of a surfactant (Rheodol TW-O120V manufactured by Kao Corporation). This mixed solution was stirred at 10000 rpm for 10 minutes using an emulsifying disperser (TK Robomix manufactured by Primix). This resulted in an emulsified liquid containing emulsified droplets.
この乳化液を４Ｌ金属角缶（アズワン社製）に詰めて、線量２７０ｋＧｙのγ線を照射し、乳化液滴中の天然ゴムを架橋した。 This emulsified liquid was packed in a 4 L metal square can (manufactured by AS ONE) and irradiated with γ rays at a dose of 270 kGy to crosslink the natural rubber in the emulsified droplets.
次に、この乳化液から、ロータリーエバポレーターを用いてシクロヘキンを蒸留して取り除いた。得られた水分散液を、ブフナー漏斗（関谷理化硝子器械社製３．２Ｌ）を用いて定量濾紙（アドバンテック東洋社製Ｎｏ．２）で濾過した。その後、電気伝導度が１ｍＳ／ｍになるまで水洗を行い、非ゴム成分を除去した。次いで、ヘプタン１Ｌを用いた洗浄を３回繰り返し、界面活性剤を除去した。このようにして得られたケーキ状物質を、６０℃で１２時間乾燥した。この乾燥粉体をジューサーミキサーで解砕し、２５０ｍｅｓｈ篩（ＪＩＳ試験用規格篩）でふるいにかけ、天然ゴム粒子を得た。 Cyclohexane was then distilled off from this emulsion using a rotary evaporator. The resulting aqueous dispersion was filtered through quantitative filter paper (No. 2, manufactured by Advantech Toyo Co., Ltd.) using a Buchner funnel (3.2 L, manufactured by Sekiya Rika Glass Instruments Co., Ltd.). Then, it was washed with water until the electric conductivity reached 1 mS/m to remove non-rubber components. Washing with 1 L of heptane was then repeated three times to remove the surfactant. The cake thus obtained was dried at 60° C. for 12 hours. This dry powder was pulverized with a juicer mixer and sieved with a 250 mesh sieve (JIS test standard sieve) to obtain natural rubber particles.
天然ゴム粒子の調製条件を表３にまとめた。また、天然ゴム粒子の粉体の物性を以下の方法で測定した。他の実施例や比較例についても同様に測定し、その結果を表４に示す。 Table 3 summarizes the preparation conditions of the natural rubber particles. In addition, the physical properties of the powder of natural rubber particles were measured by the following methods. Other examples and comparative examples were measured in the same manner, and the results are shown in Table 4.
（１）平均粒子径、最大粒子径、粒子変動係数
レーザー回折装置（堀場製作所製のＬＡ-９５０ｖ２）を用いて、天然ゴム粒子の粒度分布を測定した。この粒度分布からメジアン値を求め、平均粒子径ｄ１とした。また、粒度分布で検出される最も大きい粒子径を最大粒子径ｄ２とした。さらに、粒度分布（母集団）から標準偏差σと母平均μを求め、粒子変動係数（ＣＶ＝σ／μ）を得た。表４では百分率で表している。また、最大粒子径ｄ２を平均粒子径ｄ１で除して最大粒子径と平均粒子径の比（ｄ２／ｄ１）を求めた。
(1) Average Particle Size, Maximum Particle Size, and Particle Variation Coefficient The particle size distribution of natural rubber particles was measured using a laser diffractometer (LA-950v2 manufactured by Horiba, Ltd.). A median value was obtained from this particle size distribution and was defined as the average particle size d1. The largest particle size detected in the particle size distribution was defined as the maximum particle size d2. Further, the standard deviation σ and the population mean μ were obtained from the particle size distribution (population) to obtain the particle variation coefficient (CV=σ/μ). In Table 4, it is expressed as a percentage. Also, the ratio of the maximum particle size to the average particle size (d 2 /d 1 ) was obtained by dividing the maximum particle size d 2 by the average particle size d 1 .
（２）真球度
透過型電子顕微鏡（日立製作所製、Ｈ－８０００）により、２０００倍から２５万倍の倍率で撮影し、写真投影図を得る。この写真投影図から、任意の５０個の粒子を選び、それぞれの最大径ＤＬと、これに直交する短径ＤＳを測定し、比（ＤＳ／ＤＬ）を求めた。それらの平均値を真球度とした。
(2) Sphericality Using a transmission electron microscope (manufactured by Hitachi Ltd., H-8000), images are taken at a magnification of 2,000 to 250,000 times to obtain a photographic projection. Arbitrarily selected 50 particles from this photographic projection, the maximum diameter DL and the short diameter DS perpendicular thereto were measured to obtain the ratio (DS/DL). Their average value was taken as the degree of sphericity.
（３）タンパク質の含有量
ケルダール法にて測定した。具体的には、硫酸を用いて試料を加熱分解し、試料に含まれる窒素を硫酸アンモニウムとした。次に、この分解液をアルカリ性とし、遊離したアンモニアを蒸留し、そのＮ量を滴定により測定した。このＮ量に６．２５を乗じた値をタンパク質の含有量とした。本実施例では、Ｎを定量した結果、検出限界の１ｐｐｍ未満であった。そこで、タンパク質量は６ｐｐｍ未満と判断した。
(3) Protein content Measured by the Kjeldahl method. Specifically, the sample was thermally decomposed using sulfuric acid, and the nitrogen contained in the sample was converted to ammonium sulfate. Next, this decomposed liquid was made alkaline, liberated ammonia was distilled, and the amount of N was measured by titration. The value obtained by multiplying this N amount by 6.25 was taken as the protein content. In this example, as a result of quantifying N, it was less than the detection limit of 1 ppm. Therefore, the protein amount was determined to be less than 6 ppm.
（４）リンの定量
天然ゴム粒子の粉末約１ｇを白金皿に採取する。硝酸５ｍｌ、弗化水素酸１０ｍｌを加えて、サンドバス上で加熱する。乾固したら、少量の水と硝酸５０ｍｌを加えて溶解させて１００ｍｌのメスフラスコに入れ、水を加えて１００ｍｌとする。次に、この溶液から分液１０ｍｌを２０ｍｌメスフラスコに採取する操作を５回繰り返し、分液１０ｍｌを５個得る。そして、これを用いて、リンについてＩＣＰプラズマ発光分析装置（ＳＩＩ社製ＳＰＳ５５２０）にて標準添加法で測定を行った。
(4) Quantification of Phosphorus About 1 g of powder of natural rubber particles is collected in a platinum dish. Add 5 ml of nitric acid and 10 ml of hydrofluoric acid and heat on a sand bath. After drying, add a small amount of water and 50 ml of nitric acid to dissolve, put in a 100 ml volumetric flask, and add water to bring the volume to 100 ml. Next, the operation of collecting 10 ml of liquid separation from this solution into a 20 ml volumetric flask is repeated five times to obtain five 10 ml liquid separations. Using this, phosphorus was measured by the standard addition method with an ICP plasma emission spectrometer (SII SPS5520).
（５）脂肪酸、脂肪酸エステルの確認試験
赤外線吸収スペクトルにおいて、脂肪酸に特有なカルボニル基に帰属される１７１０ｃｍ－１付近の吸収、および脂肪酸エステルに特有なカルボニル基に帰属される１７４０ｃｍ－１付近の吸収の有無を確認した。
(5) Confirmation Test of Fatty Acids and Fatty Acid Esters In the infrared absorption spectrum, absorption near 1710 cm −1 attributed to carbonyl groups characteristic of fatty acids, and absorption near 1740 cm −1 attributed to carbonyl groups characteristic of fatty acid esters. I checked the presence or absence of
具体的には、天然ゴム粒子の粉末２０ｍｇを２０φのディスクに成型する。これを真空ラインに接続されたＩＲセルに設置して、７０oＣで１時間、真空排気処理を行って吸着水分を除去した。真空排気処理後、２５oＣに降温して、試料ディスクのＩＲスペクトルを赤外吸光分光計（日本分光社製 ＦＴ／ＩＲ－４６００）で測定した。 Specifically, 20 mg of powder of natural rubber particles is formed into a disk of 20φ. This was placed in an IR cell connected to a vacuum line, and vacuum exhaust treatment was performed at 70° C. for 1 hour to remove adsorbed moisture. After the evacuation process, the temperature was lowered to 25° C., and the IR spectrum of the sample disk was measured with an infrared absorption spectrometer (FT/IR-4600 manufactured by JASCO Corporation).
（６）硝子転移温度
示差走査熱量計（リガク社製 ＤＳＣ８２３０Ｌ）を用い、－８０℃から８０℃まで、１０℃／分で昇温させて測定した。
(6) Glass transition temperature A differential scanning calorimeter (DSC8230L manufactured by Rigaku Corporation) was used to measure the temperature from -80°C to 80°C at a rate of 10°C/min.
（７）生分解性
天然ゴム粒子の粉末をＯＥＣＤ ＴＧ３０１Ｆ（易分解性）に基づいて生分解性試験を行い、２８日間の暴露における分解率を測定した。本実施例では、この分解率は９０％であった。
(7) Biodegradability The powder of natural rubber particles was subjected to a biodegradability test based on OECD TG301F (easily degradable) to measure the decomposition rate after exposure for 28 days. In this example, the decomposition rate was 90%.
［実施例２］
乳化分散機の回転数を５０００ｒｐｍとした以外は、実施例１と同様に調製した。
[Example 2]
Preparation was carried out in the same manner as in Example 1, except that the rotation speed of the emulsifying disperser was 5000 rpm.
［実施例３］
乳化分散機の回転数を１３０００ｒｐｍとした以外は、実施例１と同様に調製した。
[Example 3]
Preparation was carried out in the same manner as in Example 1, except that the rotation speed of the emulsifying disperser was 13000 rpm.
［実施例４］
γ線照射量を１６０ｋＧｙとした以外は、実施例１と同様に調製した。
[Example 4]
It was prepared in the same manner as in Example 1, except that the γ-ray irradiation dose was 160 kGy.
［実施例５］
γ線照射量を４００ｋＧｙとした以外は、実施例１と同様に調製した。
[Example 5]
It was prepared in the same manner as in Example 1, except that the γ-ray irradiation dose was 400 kGy.
［実施例６］
天然ゴムラテックスとして、脱タンパク天然ゴム（住友ゴム工業社製ＳＥＬＡＴＥＸ ３８２１）を用いた以外は、実施例１と同様に調製した。
[Example 6]
It was prepared in the same manner as in Example 1, except that deproteinized natural rubber (SELATEX 3821 manufactured by Sumitomo Rubber Industries, Ltd.) was used as the natural rubber latex.
［実施例７］
乳化分散機の回転数を１６０００ｒｐｍで２０分間とした以外は、実施例１と同様に調製した。
[Example 7]
Preparation was carried out in the same manner as in Example 1, except that the rotation speed of the emulsifying disperser was 16000 rpm for 20 minutes.
［比較例１］
乳化分散機の回転数を２０００ｒｐｍとした以外は、実施例１と同様に調製した。
[Comparative Example 1]
Preparation was carried out in the same manner as in Example 1, except that the rotation speed of the emulsifying disperser was 2000 rpm.
［比較例２］
架橋工程を行わないこと以外は、実施例１と同様な操作を行ったところ、乾燥品はシート状となり、ジューサーミキサーで解砕できなかった。そのため、天然ゴム粒子が得られなかった。
[Comparative Example 2]
When the same operation as in Example 1 was performed except that the cross-linking step was not performed, the dried product became sheet-like and could not be crushed with a juicer-mixer. Therefore, natural rubber particles could not be obtained.
［比較例３］
γ線照射量を６００ｋＧｙとした以外は、実施例１と同様に調製した。
[Comparative Example 3]
It was prepared in the same manner as in Example 1, except that the γ-ray irradiation dose was 600 kGy.
［比較例４］
γ線照射量を４０ｋＧｙとした以外は、実施例１と同様な操作を行ったところ、乾燥品はシート状となり、ジューサーミキサーで解砕できなかった。そのため、天然ゴム粒子が得られなかった。
[Comparative Example 4]
When the same operation as in Example 1 was performed except that the γ-ray dose was changed to 40 kGy, the dried product became sheet-like and could not be crushed with a juicer-mixer. Therefore, natural rubber particles could not be obtained.
〈天然ゴム粒子の粉体の感触特性〉
次に、各実施例と比較例で得られた粉体の感触特性を評価した。各粉体について、２０名の専門パネラーによる官能テストを行い、さらさら感、しっとり感、転がり感、均一な延び広がり性、肌への付着性、転がり感の持続性、およびソフト感の７つの評価項目に関して聞き取り調査を行った。評価点基準（ａ）に基づく各人の評価点を合計し、評価基準（ｂ）に基づき感触特性を評価した。結果を表５に示す。
評価点基準（ａ）
５点：非常に優れている。
４点：優れている。
３点：普通。
２点：劣る。
１点：非常に劣る。
評価基準（ｂ）
◎：合計点が８０点以上
○：合計点が６０点以上８０点未満
△：合計点が４０点以上６０点未満
▲：合計点が２０点以上４０点未満
×：合計点が２０点未満
<Tactile Characteristics of Powder of Natural Rubber Particles>
Next, the tactile properties of the powders obtained in each example and comparative example were evaluated. Each powder was subjected to a sensory test by a panel of 20 specialists, and was evaluated in seven categories: smoothness, moistness, rollability, uniform spreadability, adhesion to skin, durability of rollability, and softness. An interview survey was conducted regarding the items. Each person's evaluation points based on the evaluation point criteria (a) were totaled, and the tactile characteristics were evaluated based on the evaluation criteria (b). Table 5 shows the results.
Evaluation point criteria (a)
5 points: Excellent.
4 points: Excellent.
3 points: Normal.
2 points: Inferior.
1 point: very poor.
Evaluation criteria (b)
◎: Total score is 80 or more ○: Total score is 60 or more and less than 80 △: Total score is 40 or more and less than 60 ▲: Total score is 20 or more and less than 40 ×: Total score is less than 20
〈リキッドファンデーションの使用感〉
天然ゴム粒子の粉体を用いて、表６に示す配合比率（重量％）となるようにＷ／Ｏ型リキッドファンデーションを作製した。すなわち、各例の粉体を成分（１０）として、成分（２）～（１４）と共にディスパーにて均一に分散させ、その後で、成分（１）と混合した。さらに、成分（１５）～（１９）を同様に均一混合した。これらを７０℃に加熱し成分を融解した後、ディスパーで乳化・冷却・脱泡し、Ｗ／Ｏ型リキッドファンデーションを得た。この様にして得られたリキッドファンデーションについて、２０名の専門パネラーによる官能テストを行った。肌への塗布中の均一な延び、しっとり感、滑らかさ、および、肌に塗布後の化粧膜の均一性、しっとり感、やわらかさの６つの評価項目に関して聞き取り調査を行った。前述の評価点基準（ａ）に基づく各人の評価点を合計し、前述の評価基準（ｂ）に基づきファンデーションの使用感を評価した。結果を表７に示す。実施例による化粧料は、塗布中でも塗布後でも、使用感が優れている。しかし、比較例の化粧料は、使用感がよくない。
<Usage of liquid foundation>
A W/O type liquid foundation was prepared using powder of natural rubber particles so as to have a compounding ratio (% by weight) shown in Table 6. That is, the powder of each example was used as component (10) and was uniformly dispersed with components (2) to (14) by a disper, and then mixed with component (1). Furthermore, components (15) to (19) were uniformly mixed in the same manner. After heating these to 70° C. to melt the ingredients, emulsification, cooling, and defoaming were performed using a disper to obtain a W/O type liquid foundation. The liquid foundation thus obtained was subjected to a sensory test by 20 expert panelists. Interviews were conducted on six evaluation items: uniform spread, moist feeling, and smoothness during application to the skin, and uniformity, moist feeling, and softness of the cosmetic film after application to the skin. Each person's evaluation points based on the evaluation point criteria (a) described above were totaled, and the feeling of use of the foundation was evaluated based on the evaluation criteria (b) described above. Table 7 shows the results. The cosmetics according to the examples have an excellent feel during use and after application. However, the cosmetics of the comparative examples do not give a good feeling when used.
Claims (8)
前記精製天然ゴムに有機溶媒を加え、前記精製天然ゴムを溶解させて溶解液を得る工程と、
前記溶解液と界面活性剤と水を混合して、乳化液滴を含む乳化液を調製する工程と、
前記乳化液に電離放射線を照射して前記乳化液滴中の天然ゴム成分を架橋させる架橋工程と、
前記乳化液滴から有機溶媒を除去する有機溶媒除去工程と、
前記架橋工程と前記有機溶媒除去工程を経て得られた水分散体を固液分離して、天然ゴム粒子を固形物として得る固液分離工程と、を備える天然ゴム粒子の製造方法。 a purification step of adding an alkaline component to a solution containing uncrosslinked natural rubber latex to hydrolyze the lipid to obtain a purified natural rubber solid;
adding an organic solvent to the purified natural rubber to dissolve the purified natural rubber to obtain a solution;
mixing the solution, a surfactant, and water to prepare an emulsified liquid containing emulsified droplets;
a cross-linking step of irradiating the emulsified liquid with ionizing radiation to cross-link the natural rubber component in the emulsified droplets;
an organic solvent removing step of removing the organic solvent from the emulsified droplets;
A method for producing natural rubber particles, comprising a solid-liquid separation step of solid-liquid separation of the aqueous dispersion obtained through the cross-linking step and the organic solvent removal step to obtain natural rubber particles as a solid matter.
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