JPS5839452B2 - Foam manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a flexible and hydrophilic foam.

Currently, various foams (sponges) are widely used as cosmetic puff materials.

For example, a sponge made from polyvinyl alcohol (P
VA sponge) is used as a pub for water-based cosmetics.

Although this PVA sponge has an extremely smooth feel in a wet state and is a desirable material, it has the disadvantage that it is hard in a dry state and cannot be used as a sponge for non-aqueous cosmetics.

For this reason, sponges derived from natural rubber, nitrile butadiene rubber (NBR), etc., which are flexible in a dry state, are used as pubs for non-aqueous cosmetics.

However, these rubber sponges have drawbacks such as poor slippage and roughness due to their rubbery properties on women's skin, which not only cause discomfort when used, but also sometimes damage the skin.

Furthermore, since rubber sponges are hydrophobic materials, it is difficult to use them for water-based cosmetics.

In view of the above-mentioned problems, the present inventors continued intensive research into foams that have both flexibility and hydrophilicity when dry, and found that natural rubber, NBR, or styrene-butadiene rubber (
The present invention was completed by discovering a method of adding fibroin powder to 5BR).

An object of the present invention is to provide a method for industrially and easily manufacturing a foam that is smooth and soft to the skin, has a certain degree of hydrophilicity, and is flexible even when dry.

Other objects and advantages of the invention will become apparent from the description below.

The above object of the present invention is achieved by adding and mixing fibroin powder to an aqueous dispersion of natural rubber, SBR or NBR, foaming and solidifying in the presence of a surfactant, followed by crosslinking.

Examples of the fibroin powder used in the present invention include the following.

(1) Fibroin powder obtained by pulverizing refined silk thread as it is or after treating it with acid or alkali to make it slightly brittle.

(2) Fibroin obtained by dissolving silk raw materials such as cocoon, raw silk, bis, boulet, etc. in a solvent such as a calcium chloride aqueous solution, calcium nitrate aqueous solution, or lithium bromide aqueous solution, or by further desalting the solvent solution of the silk raw material by dialysis. A fibroin powder obtained by regenerating and coagulating an aqueous solution by adding a coagulating salt, high-speed stirring, adding a water-miscible solvent, etc., and then pulverizing it.

The degree of crystallinity of this fibroin powder is preferably 25% or more in order to improve the dispersibility in the foam and to improve the smoothness of the foam.

Here, crystallinity refers to the crystallinity of 0%, assuming that the powder obtained by spray-drying a fibroin aqueous solution at 110°C is amorphous.
It is calculated from the intensity area ratio of X-ray diffraction when

Further, the particle size of the fibroin powder is preferably in the range of 1 to 100 μm in consideration of dispersibility, smoothness of the foam, etc.

NBR and SBR that can be applied to the present invention are copolymers obtained by polymerizing acrylonitrile and butadiene and styrene and butadiene according to a conventional method, and are in the form of an aqueous emulsion, and natural rubber is in the form of a water dispersion (latex). (In this specification, an aqueous emulsion and a latex are collectively referred to as an aqueous dispersion), natural rubber, NBR, etc.
and SBR can be used not only individually but also in combination.

The foam according to the present invention contains the fibroin powder of 0.5 to
10% by weight or preferably 2% to 6% by weight per 1% to 8% by weight, and the natural rubber, NBR or SB
It contains R in an amount of 90 to 99.5% by weight, preferably 92 to 99% by weight, particularly preferably 94 to 98% by weight.

Fibroin powder is less than 0.5 weight and rubber solids are 9
If the weight exceeds 95%, it is difficult for fibroin to exert its effects, and it tends to have poor slippage on the skin, giving a rough feel, and lacks hydrophilicity. becomes difficult to apply.

The foam of the present invention usually has a bulk density of 0.05 to 0.5 g/d, preferably 0.07 to 0.2517 M for cosmetic use, or 0.1 to 0.2 g/d. This is particularly suitable.

The foam of the present invention is obtained by mixing fibroin powder with an aqueous dispersion or emulsion solution of natural rubber, NBR or SBR, foaming in the presence of a surfactant, and then solidifying and dehydrating. A surfactant is added to an aqueous dispersion or an aqueous emulsion solution of SBR, and after foaming with strong stirring, fibroin powder is added and mixed.

Examples of surfactants include aliphatic alkaline soaps, higher alcohol sulfate ester salts, alkyl sulfonates,
Examples include quaternary ammonium salts, but aliphatic alkaline soaps are particularly preferred.

The amount of surfactant added is usually 0 to the rubber aqueous dispersion.
．． 3 to 5 weight class.

The solid content concentration of the aqueous dispersion of natural rubber, NBR or SBR is adjusted to 30 to 75% by weight, preferably 50 to 70% by weight.

Additionally, additives such as thickeners such as polyvinyl alcohol, colorants such as dyes and pigments, and anti-aging agents may be mixed as appropriate.

Fibroin powder is added to an aqueous dispersion of foamed natural rubber, NBR or SBH, and the mixture is stirred and mixed evenly.

Although the fibroin powder may be added in a dry state, it is preferable to add it in the form of a paste dispersed in water to facilitate uniform mixing.

Further, when dispersing in water, a small amount of a water-miscible solvent can be added to improve dispersibility.

Next, sulfur is usually used as a crosslinking agent, but at the same time zinc oxide, zinc diethyldithiocarbamate, etc. can be added to promote crosslinking.

Sulfur as a crosslinking agent is usually used in natural rubber NBR or SBR.
It is sufficient to use an amount that is 1 to 10% more O6 by weight than the solid content.

After foaming, these mixed liquids are transferred to a solidification step.

As a solidification method, any conventionally known method can be adopted, but in particular, it is preferable to use sulfur hexafluorosilicate because it maintains uniform air bubbles, facilitates molding, and simplifies equipment. It is preferable.

The solidified foam is then crosslinked.

When sulfur is used as a crosslinking agent, this can usually be achieved by heating under saturated steam.

The temperature may be 50 to 1.30°C, preferably 90 to 120°C for 10 to 60 minutes.

A flexible foam can be obtained by washing with water and drying after crosslinking treatment.

Drying is usually 50-130℃, preferably 60-100℃
'C under normal pressure or reduced pressure.

The obtained foam is subjected to post-processing as appropriate depending on the use, and then cut into products according to the purpose.The foam of the present invention has flexibility and has good sliding properties on the skin. Since it has a soft feel and a certain degree of hydrophilicity, it has great effects, such as being able to be used not only for oil-based or emulsion-based cosmetics, but also for water-based cosmetics.

In addition, the addition of fibroin significantly improves oil resistance, which has been a drawback of conventional natural rubber, and this not only improves the service life of oil-based cosmetics but also improves oil-based ink. It can also be applied to fields that require oil resistance, such as roller materials.

The present invention will be specifically explained below with reference to Examples.

Example 1 Boulet IKy was immersed in a 0.5 weight aqueous solution of Marcel soap 30, treated at 80°C for 1 hour to substantially completely remove residual sericin and oil, thoroughly washed with water, and then heated to 70°C.
It was dried.

0.2 Ky of the refined Boletus was put into a kneader containing 1.5 Kp of a mixed solution of 45 parts by weight of calcium nitrate, 27 parts by weight of water and 28 parts by weight of ethyl alcohol, and heated at 80 to 85°C. The mixture was stirred and dissolved for 1 hour.

The resulting viscous solution was diluted with 0.8 Ky of water and then dialyzed using a cellulose membrane to remove calcium nitrate.

Fibroin aqueous solution 3 from which impurities were then removed by filtration
．． To 1 Kp, 0.4 to 2 parts of methyl alcohol was added with stirring.

After about 30 minutes, the whole gelatinized product was dehydrated by centrifugation in a cloth bag, and then dried with hot air at 60° C. for 10 hours.

Next, the particle size is reduced to 1 to 4 by grinding with a jet mill.
A fibroin powder of 0.14 KP with a diameter of 0 μm and a nearly spherical shape was obtained.

The crystallinity of the powder was 37%.

Commercially available NBR emulsion (N1pol manufactured by Nippon Zeon Co., Ltd.
Lx 531 ) 100 P (NBR concentration 6, lead 211, zinc mercaptobenzothiazole 0.7 f, zinc diethyldithiocarbamate 0.71) dispersed in 52 parts of water were added.

Since this NBR emulsion already contained a large amount of potassium oleate as a surfactant, it was not added at the time of foaming.

Next, the above-mentioned fibroin powder was made into an aqueous dispersion of 30 weight φ, and the mixture was added in the proportions shown in Table 1 and thoroughly mixed.
The volume was adjusted to about 70 ocrtt.

After the bubbles were sufficiently homogenized, 25 weight of sodium hexafluorosilicate aqueous dispersion 51 was added and mixed.

Next, it was poured into an aluminum cylindrical container with an inner diameter of 9 CrrL, and left at room temperature.

After 3 to 4 minutes, the gelled foam was treated under saturated steam at 110°C for 30 minutes and taken out from the container.

After thorough washing with water, heat at 70°C under reduced pressure (1 vmHg
) and dried for 8 hours.

The obtained NBR-fibroin mixed foam was cut into appropriate sizes and its physical properties were evaluated.

Regarding the feeling of using cosmetics, women aged 19 to 302
0 people were selected and each sample was scored and evaluated based on the following criteria.

Each person scored the preferred level for each sample on a scale of 5 points, and a total score of 85 points or more is ◎ (very good), and 70 or more.
84 points ○ (good) 55 to 69 points △ (slightly poor), 54
A score below a point was rated as × (defective).

As in experiment number 1-1.1-2, the amount of fibroin was 0.
If the weight is less than 5 φ, it is flexible, but tends to have a strong friction with the facial skin, and lacks hydrophilicity, so it has poor affinity with water-based cosmetics, and is not suitable for use as a pub for water-based cosmetics. When using it, the adhesive, spreadability, etc. performance was not good enough.

- All of the foams obtained by the method of the invention were flexible and had excellent smoothness and hydrophilicity, and had a favorable feel when used in both water-based and oil-based cosmetics.

Example 2 A foam was manufactured using the fibroin powder obtained in Example 1 and the natural rubber aqueous dispersion.

Potassium oleate as a surfactant was added in an amount of 1.5 weight to 60 weight φ of natural rubber aqueous dispersion 1001, and stirred.\ Colloidal sulfur 1.2P, zinc oxide 21
, zinc mercaptobenzothiazole 0.7P, zinc diethyldithiocarbamate 0.71 to 51? were dispersed in water and mixed.

Next is 2.5L? of fibroin powder was added and mixed as an aqueous dispersion of 30 weight φ, and the volume of the foam was 200 to 1.
The mixture was foamed until the volume reached 500 ml, and then 25 parts by weight of an aqueous dispersion 52 of sodium hexafluorosilicate was added and mixed.

This foam was poured into an aluminum container and gelled, then treated under saturated steam at 110° C. for 30 minutes, washed with water and dried to obtain foams having various bulk densities.

The usability was evaluated by scoring by 20 women in the same manner as in Example 1.

When the bulk density increased as in Experiment No. 2-5, it became very hard and was practically unsuitable for use as a cosmetic puff.

- All of the foams obtained by the method of the invention had flexibility and smoothness, and had excellent performance for both water-based and oil-based cosmetics.

Example 3 Fibroin powder obtained in Example 1 and NBR (Zeon Corporation N1pol Lx 531B solid content concentration 66% by weight)
) Aqueous dispersions of SBR (Nippon Zeon Co., Ltd. N1pol 4850 solid content concentration 63% by weight) and natural rubber (solid content concentration 60% by weight) were used as raw materials.

The foam was manufactured using the same procedure as in Example 1 or 2, i.e., in the case of natural rubber, potassium oleate was added as a surfactant to the aqueous dispersion in a range of 1.5% by weight, and in the case of NBR and SBR, it was Since an activator is added, it is left as is.
The mixture was stirred and foamed.

The crosslinking agent composition and gelling agent composition were the same as in Example 1 or 2 in the same amounts.

The obtained foam has a major axis of 10 CrrL1 a minor axis of 6, and a thickness of 1
．． It was cut to the size of a 2cIrL ellipsoid and compared with a commercially available cosmetic pub.

Sliding friction coefficient is vertical 4crIL1 horizontal 2G1'/L, thickness 1
Cut each foam into crrL, load 20 y/crf
1 was applied to the entire surface of the foam and calculated from the maximum stress when sliding it on synthetic leather.

The toluene immersion volumetric swelling rate was calculated from the volumetric expansion rate after immersing the foam in toluene for 10 minutes.

The same evaluation method as in Example 1 was used for the feeling of use.

The foams obtained by the method of the present invention not only have excellent smoothness and feel when used in cosmetics compared to conventional products, but also have significantly improved oil resistance by adding fibroin. It was something.

Example 4 Raw silk I Ky was immersed in a multi-Marcel soap aqueous solution 40 and treated at 98°C for 1 hour to remove sericin, then immersed in a 0.5N sodium hydroxide aqueous solution 25 and heated at 60°C. After treatment for 3 hours, the sample was thoroughly washed with water and dried.

Next, the treated raw silk is pulverized with a jet mill to a length of 3 to i
ooμ, short fibroin powder with a radius of about 1μ 0
．． Obtained 58 K9.

The crystallinity was 47. 100? NBR aqueous emulsion (Zeon Corporation N1pol Lx 531)
While stirring, add 1.5 f of colloidal sulfur, 22 g of zinc oxide,
0.7 f of zinc mercaptobenzothiazole and 0.71 f of zinc diethyldithiocarbamate were dispersed in 51 g of water and added.

Next, the fibrous fibroin powder described above was added in the proportions shown in Table 4, thoroughly mixed, the volume was adjusted to about 700 μm, and 25 parts by weight of an aqueous dispersion of sodium hexafluorosilicate 51 was added and mixed. .

After gelation in an aluminum container, the mixture was heated under saturated steam at 110° C. for 30 minutes to effect crosslinking.

As shown in Table 4, the foams obtained by washing with water and drying were all flexible and had appropriate hydrophilicity, so they could be applied to both oil-based and water-based cosmetics.

The usability was evaluated in the same manner as in Example 1.

Claims (1)

[Claims] 1. Fibroin powder is added to and mixed with an aqueous dispersion of natural rubber, nitrile butadiene rubber, or styrene butadiene rubber, foamed and solidified in the presence of a surfactant, and then crosslinked. A method for producing a foam. 2. The manufacturing method according to claim 1, wherein the fibroin powder is obtained by regenerating and coagulating an aqueous fibroin solution and then pulverizing the fibroin powder. 3. The manufacturing method according to claim 1, wherein the fibroin powder is powdered silk thread. 4. The manufacturing method according to claim 1, wherein the fibroin powder has a particle size of 1 to 100 μm. 5. The manufacturing method according to claim 1, wherein the fibroin powder has a crystallinity of 20φ or more. 6 Fibroin powder is added to the rubber solid content at a ratio of 0.5 to 1
The manufacturing method according to claim 1, in which 0 weight amount is added.