JP2012025874A - Sponge subjected to hydrophilic softening treatment and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sponge subjected to hydrophilic softening treatment which has moist feeling on both in drying and wetting, has strong hydrophilicity, and further has excellent productivity and operability.SOLUTION: A sponge is soaked into a treatment liquid, made of an aqueous solution comprising polymerizable monomers and having a cloud point of ≥20°C, in a condition where the temperature state of the treatment liquid lies in the cloud point or below, the treatment liquid is heated up to a temperature of the cloud point or above and also to less than 80°C, the polymerizable monomers are precipitated at the surface and at the inside of the sponge to be polymerized. Alternatively, the cloud point of the treatment liquid comprising the polymerizable monomers is 20 to 75°C, and also, the treatment temperature is 25 to 80°C.

Description

  The present invention relates to a sponge having flexible rubber elasticity, and in particular, has a large impact resilience, has a soft touch and is hydrophilic, and is used as a cosmetic puff made of rubber or polyurethane, a washing tool, or a cushion. The present invention relates to a sponge that is directly touched to the skin and has been subjected to a hydrophilic softening treatment and a method for producing the same.

  Sponges for directly touching the skin, especially cosmetic sponge puffs, require a moist and good texture per skin. In addition to the method of applying cosmetic foundation to the sponge puff and applying it (use without water), the sponge puff is moistened with water by squeezing the sponge puff with water. There is a method (use with water) of applying a cosmetic foundation after applying it. By moistening the sponge puff with water, a cool refreshing feeling and a softer and softer skin feel are preferred, and by moistening the sponge puff with water, the foundation is stretched and the makeup effect is good It will be excellent. This is because the resin surface of the sponge puff is wet with water, and the hydrophobic particles of the foundation float on the surface, so that the transfer to the skin becomes good. In order to exhibit such characteristics, foundations specifically for use with water are on the market. Many foundations are manufactured as a dual-use type with and without water.

  As such a sponge puff for use with water, a rubber elastic sponge such as NBR can be used. For the purpose of improving the effect, a sponge made hydrophilic by graft polymerizing the resin surface of the sponge with a hydrophilic monomer. Has been proposed. By making the resin surface of the sponge hydrophilic, water is strong on the surface during use, and it is uniformly held, and the elongation of the foundation is excellent.

  As such, as shown in Patent Document 1, in a hydrophilic puff production method comprising immersing a puff material in an aqueous solution of polyethylene glycol dimethacrylate, heating and causing graft polymerization, water is used as the polymerization initiator. In some cases, a reactive azo initiator is added in advance to the aqueous polyethylene glycol dimethacrylate solution.

Moreover, as shown in Patent Document 2, there is a technique in which a graft monomer is graft-polymerized on the surface of a cosmetic applicator by irradiating ultraviolet rays.
Japanese Patent Application Laid-Open No. 64-81834 JP 2001-95621 A

  However, in the one described in Patent Document 1, when the sponge is moist, it feels moist, but when it is dried, it becomes crisp and hard and the original flexibility of the sponge is reduced. Therefore, it cannot be used in a dual-use type foundation or shared with a waterless type foundation. Further, not all monomers in the aqueous solution are graft-polymerized on the sponge surface, and most of them become a homopolymer in the solution. This homopolymer is sticky, and it adheres to the sponge, giving an unpleasant feeling of stickiness, or attaching to the product as an undesired patchy stain.

  Further, most of the homopolymers and unreacted monomers in the solution are not taken into the sponge and are discharged as drainage, which increases costs. In addition, the waste liquid containing the homopolymer and the unreacted monomer is not allowed to be discharged into the river as it is, and wastewater treatment is required, which also causes an increase in cost.

  Moreover, in what was described in the said patent document 2, in order to photopolymerize polyalkylene glycol methacrylate, the apparatus which performs light irradiation is needed separately. In addition, polymerization does not occur inside the sponge where light does not reach by this light irradiation, and a uniform product cannot be obtained. Furthermore, since this method is processed after the form of the final product, productivity and workability are poor. Furthermore, since photopolymerization has an oxygen hindrance and cannot be produced by light irradiation in the air, it is necessary to perform a nitrogen purge, which requires a special apparatus for this purpose.

  The present invention has been made in view of these points, and has a moist feel when dried and wet, has a strong hydrophilicity, and has a hydrophilization softening treatment having excellent productivity and workability. A sponge and a method for producing the same are provided to solve the above problems.

  The invention of claim 1 is a treatment liquid comprising an aqueous solution containing a polymerizable monomer and having a cloud point of 20 ° C. or higher, wherein a sponge is immersed in the treatment liquid in a temperature state below the cloud point, and the treatment liquid is The temperature was raised to a temperature not lower than the cloud point and not higher than 80 ° C., and the polymerizable monomer was precipitated on the surface and inside of the sponge to obtain a polymerized hydrophilized and softened sponge.

  The invention according to claim 2 is characterized in that the treatment liquid containing the polymerizable monomer has a cloud point of 20 ° C. to 75 ° C. and a treatment temperature of 25 ° C. to 80 ° C. A treated sponge was obtained.

  A third aspect of the present invention is the sponge subjected to the hydrophilization / softening treatment according to the first or second aspect, wherein the polymerizable monomer is polyethylene glycol acrylate or polyethylene glycol methacrylate.

  The invention according to claim 4 is the sponge subjected to hydrophilization softening treatment according to any one of claims 1, 2, or 3, wherein a surfactant is added to the aqueous solution of the polymerizable monomer.

  The invention of claim 5 is a treatment liquid having a cloud point of 20 ° C. or higher, comprising an aqueous solution containing a polymerizable monomer, wherein a sponge is immersed in the treatment liquid in a temperature state below the cloud point, and the treatment liquid is The temperature was raised to a temperature not lower than the cloud point and not higher than 80 ° C., and the polymerizable monomer was precipitated on the surface and inside of the sponge, thereby producing a polymerized hydrophilically softened sponge.

  According to each of the first and fifth aspects of the present invention, the sponge is poured and immersed in the treatment liquid at a temperature below the cloud point and the polymerizable monomer is dissolved or solubilized in the treatment liquid. And the air in the sponge bubbles are sufficiently replaced, and the treatment liquid can be spread to the back of the sponge. Thereafter, the temperature is raised and the polymerizable monomer is precipitated and polymerized on the surface and inside of the sponge, so that uniform open cells (pores) can be formed in the sponge. As a result, it is possible to obtain a hydrophilized and softened sponge that is flexible when dry and wet, has a moist feel, has strong hydrophilicity, and has excellent productivity and workability. It was.

  Further, according to the invention of claim 2, since the cloud point of the treatment liquid containing the polymerizable monomer is 20 ° C. to 75 ° C. and the treatment temperature is 25 ° C. to 80 ° C., the use of the polymerizable monomer The efficiency is greatly improved as compared with the conventional one, and according to the experiment by the present applicant, it is about twice as large.

  According to the invention of claim 3, since the structure of the polymerizable monomer is polyethylene glycol acrylate or polyethylene glycol methacrylate, it has a moist feel when dry and wet than the sponge of claim 1 above. It was possible to obtain a hydrophilized and softened sponge having strong hydrophilicity, excellent productivity and workability.

  According to the invention of claim 4, since the surfactant is added to the aqueous solution of the polymerizable monomer, the cloud point temperature of the treatment liquid can be increased, and thus the monomer that is difficult to dissolve at a low temperature can be obtained. As a result, it became possible to use it, and the range of monomer selection was widened, so that an optimum sponge suitable for the purpose was obtained.

First, materials for forming the sponge of the present invention will be described.
As the sponge of the present invention, various sponges such as natural rubber, synthetic rubber and polyurethane can be used, but a resin having a double bond on the molecular structure of natural rubber or synthetic rubber is more preferable. An open cell structure is suitable. As the bubble diameter of the sponge, a sponge with a moist skin can be obtained by performing graft polymerization of the present invention on a sponge having an average bubble diameter of 50 μm or more and 300 μm or less.

Next, an aqueous solution of a polymerizable monomer in which the sponge is immersed will be described.
The polymerizable monomer used here is a monomer that makes the sponge hydrophilic by graft polymerization on the sponge, and is a monomer having a hydrophilic group in the molecular structure of the monomer. As the hydrophilic group, polyethylene oxide, sulfonyl group, carboxyl group, sulfate ester, phosphate ester, hydroxyl group, quaternary ammonium salt, pyrrolidone, polyamide and the like can be used.

  The aqueous solution of a polymerizable monomer refers to an aqueous solution in which a monomer having these groups is dissolved in water, or a liquid solubilized in combination with a surfactant described later. Moreover, it means what can be used as a treatment liquid in the impregnation step after being dissolved or solubilized in water at a temperature of 0 to 80 ° C. at a concentration of 1% to 10%.

  Furthermore, the polymerizable monomer of the present invention is a monomer having a cloud point. In the present invention, graft polymerization is efficiently performed on the sponge by utilizing the cloud point of the monomer. The polymerizable monomer having a cloud point is a monomer having a polyether group or a polyamide group of polyethylene oxide in the monomer molecule. As such a monomer, polyethylene glycol (meth) acrylate can be used, and preferably polyethylene glycol polypropylene glycol (meth) acrylate can be used.

The (meth) acrylate is an acrylic ester, a methacrylic ester or a mixture thereof.
The clouding point of the polymerizable monomer is preferably 20 ° C. or higher because the hydrophilicity of the sponge can be increased. Further, a cloud point of 75 ° C. or lower is preferable because the temperature in the impregnation step can be kept low, whereby the polymerization initiator can be prevented from being decomposed and the production of a single polymer can be prevented.

The number of moles of ethylene glycol added to polyethylene glycol is 2 moles or more, preferably 6 moles or more. Although there is no upper limit in particular, the effect of strengthening hydrophilicity is saturated even if it is 18 mol or more.
The number of moles of propylene oxide added to polypropylene glycol is 6 mol or less, preferably 3 mol or less, and the hydrophilicity can be strengthened. By using such a monomer, the cloud point of the treatment liquid can be set to 20 ° C to 75 ° C.

  Still further, as the polymerizable monomer of the present invention, alkyl polyethylene glycol polypropylene glycol (meth) acrylate having an alkyl group or alkenyl group, or alkenyl polyethylene glycol polypropylene glycol (meth) acrylate can be used.

  As the alkyl group or alkenyl group, those having 8 or more carbon atoms are preferable because the cloud point is lowered. Examples of the alkyl group or alkenyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, octyl, ethylhexyl, decyl, dodecyl, propenyl, butenyl, octenyl and the like. By using such a monomer, the cloud point of the treatment liquid can be set to 20 ° C to 75 ° C.

  In the present invention, a diacrylate sheet or a dimethacrylate monomer can be used in combination with the above monomer. As the diacrylate and dimethacrylate monomers, polyethylene glycol diacrylate sheet and polyethylene glycol dimethacrylate can be used. By using these, the hydrophilicity can be adjusted, the feel can be adjusted, and the durability of the product can be improved.

By using a surfactant in combination with the above monomer, even a monomer that does not dissolve at 0 ° C. to 25 ° C. can be solubilized and used as an aqueous solution of the polymerizable monomer of the present invention. Can do. Solubilization can be achieved by dissolving at the molecular level and making the solution transparent, as well as being dispersed in ultrafine particles and colored blue. In addition, by using a surfactant, it is possible to increase the cloud point of the treatment liquid even for a monomer that dissolves at 25 ° C. or higher, and it is possible to adjust the dissolution temperature and the treatment temperature described later. Efficiency is improved.
Moreover, the hydrophilicity of a product sponge can be improved by using an anionic surfactant for the surfactant used in combination with the monomer. Furthermore, by using a polymerizable anionic surfactant as the surfactant used in combination with the monomer, the hydrophilicity of the product sponge can be increased and the durability can be improved.
The amount of the surfactant used can be 10 to 100 parts by weight with respect to 100 parts by weight of the monomer.
Various surfactants can be used as such surfactants, and various sulfates and sulfonates can be particularly preferably used. Examples of this include higher alcohol sulfate sodium salt, alkyl sulfate sodium salt, alkylbenzene sulfonic acid sodium salt, higher alcohol maleic acid or succinic acid diester sulfonic acid sodium salt, acrylic acid or methacrylic acid ester sulfonic acid sodium salt, And ammonium salts and potassium salts thereof.

  In this invention, a polyfunctional monomer can be used in combination with the aforementioned monomer. As a polyfunctional monomer that can be used in the present invention, an ester of acrylic acid and a polyhydric alcohol can be used. As the polyhydric alcohol that is a raw material of the polyfunctional monomer, alkanediol, polyethylene glycol, polypropylene glycol, pentaerythritol and the like can be used. A monomer having a functional number of the polyfunctional monomer (the number of reactive double bonds in one molecule) of 2 or more can be used. By using a polyfunctional monomer in combination, hydrophilic durability can be enhanced.

  In this invention, an initiator can be used to perform polymerization of the above-mentioned monomer. Examples of the initiator include sodium persulfate, potassium persulfate, ammonium persulfate, azobis compounds, azobisamidinopropane dihydrochloride, and the like. The initiator can be used by dissolving in an aqueous monomer solution. By using this initiator, the polymerization temperature can be kept low, and the heat treatment temperature described later can be kept low.

  Furthermore, in this invention, an antifoaming agent can be added and used for the above-mentioned monomer aqueous solution. By using this antifoaming agent, excessive foaming during the impregnation treatment can be suppressed, and interruption of work can be prevented.

Then, the manufacturing method of the sponge of this invention is demonstrated.
In the production method of the present invention, the aforementioned chemicals such as monomers are dissolved in water, impregnated with a product to be treated in this liquid, a predetermined amount is adhered and adsorbed, and polymerized and fixed by heating.

Drugs such as monomers dissolve at temperatures below the cloud point of the monomers. As a solution temperature, it is preferable to melt | dissolve at 30 degrees C or less, More preferably, it is 25 degrees C or less. Water at this temperature can be easily prepared. The lower limit of the liquid temperature is 0 ° C., but there is no particular limitation as long as the temperature allows the monomer to dissolve. Moreover, it can melt | dissolve and solubilize at the temperature more than the cloud point of a monomer by using surfactant. The monomer concentration of the treatment liquid to be dissolved can be 1 to 10%, preferably 2 to 7%.
The amount of the treatment liquid used is preferably an amount that allows the sponge to be sufficiently immersed. In the case of an open-cell sponge, if the apparent volume of the sponge is 1 L, the same amount or more is preferable. The weight is 5 to 10 parts by weight per 1 part by weight of sponge.

In the impregnation treatment, a sponge is added in a state where the monomer is dissolved or solubilized in a treatment liquid having a liquid temperature of 0 ° C. to 75 ° C., and the treatment liquid and the air in the sponge bubbles are sufficiently replaced to the back of the sponge. Spread the processing solution. Next, the temperature of the treatment liquid is raised to a cloud point or higher. By spreading the treatment liquid on the sponge in advance at a temperature below the cloud point, the product has uniform open cells (pores). The specific temperature of the cloud point can be 25 ° C. or higher, preferably 30 ° C. or higher, more preferably 35 ° C. or higher. Moreover, it is preferable to perform this temperature at the temperature which does not exceed 80 degreeC. When the temperature exceeds 80 ° C., the polymerization initiator starts to be decomposed and a monomer polymerization reaction occurs in the impregnation treatment liquid, which may cause spots or stickiness in the product.
In addition, it is preferable that the heating does not suddenly exceed the cloud point, but it exceeds the cloud point while raising the temperature slowly, as a uniform product.
In addition, it is preferable to apply compression to the sponge repeatedly at this time so as to spread the liquid to the inside of the sponge because a uniform product is obtained.

By treating at such a temperature, the monomer is precipitated at a temperature exceeding the cloud point, and the monomer is adsorbed on the surface and inside of the sponge to be treated, thereby improving the utilization efficiency of the monomer.
As a result, the monomer concentration of the treated liquid after treatment is lower than the initial concentration. Thereby, the monomer discarded wastefully can be decreased.

  As the impregnation device, a washing machine, a rotating drum, a compression device, a roller, or the like can be used. By replacing the air inside the sponge with the chemical solution, the inside of the sponge can be made uniform.

  The reason why the use efficiency of the monomer is increased by performing the impregnation at the above temperature is that, as the temperature of water molecules that hydrogen bond to the ether group of the hydrophilic group increases in the molecular structure of the monomer, the hydrogen bond is removed and the hydrophilicity decreases. Finally, it reaches the cloud point and precipitates. The precipitated monomer in the molecular state comes into uniform contact with the resin forming the sponge and the entire sponge. At this time, it is considered that the monomer having an ester group is adsorbed to a sponge resin having a high affinity with the ester group and high utilization efficiency is exhibited.

  The sponge impregnated with the monomer has a constant impregnation rate in the drawing step. For the squeezing, a centrifugal dehydrator, a roller squeezer or the like can be used. The temperature of the drawing process is preferably performed at a temperature equal to or higher than the cloud point similarly to the impregnation temperature.

  Thereafter, heat treatment is performed to polymerize the monomer. It is preferable that the heat treatment temperature is higher than the decomposition temperature of the initiator used in terms of work efficiency. Specifically, it is about 30 minutes at 80 ° C. to 120 ° C. As a heating method, methods such as hot air, steam, microwave heating, dielectric heating and the like can be used. If the treatment temperature is too low, the initiator does not decompose and it takes a long time, resulting in poor working efficiency. Moreover, if it is high, processing for a short time is possible, but it is not preferable because the sponge is burnt or discolored. Thereafter, washing with water and drying are performed as necessary to obtain the sponge of the present invention.

In a stainless steel container, as a polymerizable monomer, NK Economer (trademark, the same shall apply hereinafter) MLR-140 (cloud point 41 ° C., liquid) 160 g and initiator V-50 1.6 g were dissolved in water 7.84 Kg at 20 ° C. A treatment solution was prepared. This treatment liquid was transparent, and both the monomer and the initiator were in a dissolved state. When 10 ml of this treatment solution was taken into a test tube and slowly heated in a hot water bath, it became cloudy at 41 ° C. The cloud point was 41 ° C.
As a raw material sponge, NBR sponge YUKIRON (trademark, the same shall apply hereinafter) CX piece product (diameter 60 mm, thickness 8 mm disk shape, about 350 pieces) 1.0 kg is put in a washing net and immersed in the treatment solution at 20 ° C. Pressing was repeated to replace the air in the bubbles with the treatment liquid. Next, the container was immersed in a hot water tank, and the temperature of the treatment liquid was increased to 43 ° C. and maintained for 10 minutes. At this time, the treatment liquid was in a slightly cloudy state, but the turbidity that was observed at the time of cloud point measurement was not generated. This is presumably because the treatment liquid temperature is higher than the cloud point and the precipitated monomer is adsorbed on the sponge. Thereafter, the treatment liquid was squeezed with a centrifugal dehydrator similarly at 43 ° C. In this state, the weight of the sponge after impregnation was 1.5 kg.
Thereafter, heating with hot air was performed in a rotary drum dryer, and the temperature was maintained at 100 ° C. for 30 minutes. The sponge was dried by evaporation of moisture. The weight after cooling was 1.02 kg.
Thereafter, washing with water and drying were performed to remove unreacted monomers and the like. The sponge weight was 1.012 kg.

Then, from the following calculation formula, the treatment liquid impregnation rate was 50%, the monomer adhesion rate was 2%, the graft polymer adhesion rate was 1.2%, and the grafting rate was 60%.
This indicates that among the monomers used, the amount of the monomer actually produced is 12 g, and the monomer utilization rate is 7.5%.

The above treatment liquid impregnation rate = (sponge weight after impregnation ÷ raw sponge weight) −1
Adhesion rate of the above monomers, etc. = (Weight of sponge after heat treatment / weight of raw material sponge) -1
Graft polymer adhesion rate = (weight of sponge after washing and drying ÷ weight of raw material sponge) −1
Grafting rate = Graft polymer adhesion rate / Monomer adhesion rate Above monomer utilization rate = (Product weight-Raw material sponge weight) / Raw material monomer weight

The resulting sponge had improved elasticity in the dry state, and had a soft and moist feel. When the sponge hardness was measured, the raw material sponge was 55 degrees, but it was 43 degrees and was softened.
It was hydrophilic and soaked as soon as it contained water. When this was squeezed, the whole was moist and moist.
After the sponge was soaked with water, it was pressed firmly by hand to squeeze the water. When this sponge was placed on the surface of the water, the sponge absorbed the water, and after 2 seconds the whole died under the surface of the water. On the other hand, when the above raw material sponge is performed in the same manner, the pressure can be repeatedly infiltrated with water several times. It only submerged below the surface of the water, and the whole thing never submerged below the surface.

The end face of the sponge produced in Example 1 was processed into a round shape to obtain a cosmetic puff. This puff was moistened with water, and a commercially available foundation for water was used to conduct a monitor test for actual makeup. It was an evaluation result that the riding of the foundation was well stretched and could be applied uniformly.
Moreover, it was flexible even in a dry state, and was excellent in use without water.

As in Example 1, NK Economer MLR-140 and Initiator V-50 (trademark, the same applies hereinafter) were dissolved at 20 ° C. as the polymerizable monomer. The raw material sponge was immersed in the treatment liquid at 20 ° C. and repeated pressing to replace the bubble air with the treatment liquid.
Next, the container was immersed in a hot water tank, and the temperature of the treatment liquid was raised to 80 ° C., much higher than the cloud point, and maintained for 10 minutes. Thereafter, the treatment liquid was squeezed with a centrifugal dehydrator at 80 ° C. In this state, the weight of the sponge after impregnation was 1.5 kg.
Thereafter, heating with hot air was performed in a rotary drum dryer, and the temperature was maintained at 100 ° C. for 30 minutes. The sponge was dried by evaporation of moisture. The weight after cooling was 1.021 kg.
Thereafter, washing with water and drying were performed to remove unreacted monomers and monopolymer. The sponge weight was 1.013 Kg.

From the above calculation formula, the treatment liquid impregnation rate was 50%, the monomer adhesion rate was 2.1%, the graft polymer adhesion rate was 1.3%, and the grafting rate was 61.9%.
Of the used monomers, the actual product was 13 g, and the monomer utilization rate was 8.1%.

  Similar to Example 1, but NK Economer MID-112 having a cloud point of 26 ° C. was used as the polymerizable monomer. The cloud point of the treatment liquid was 26 ° C. After dissolving the drug at 20 ° C. and impregnating the raw material sponge with the above processing solution at 20 ° C., the temperature of the processing solution is raised and maintained at 28 ° C., 2 ° C. higher than the cloud point, for 10 minutes, and then centrifuged at the same temperature Squeezed with a dehydrator. Thereafter, similarly to Example 1, after heating at 100 ° C. for 30 minutes, washing with water and drying were performed. Finally, the monomer utilization was 7.5%.

  As in Example 3, NK Economer MID-112 having a cloud point of 26 ° C. was used as the polymerizable monomer, and 40 g of sodium lauryl sulfate was used as the surfactant. The cloud point of the monomer alone was 26 ° C., but the cloud point of the treatment liquid was 32 ° C. After dissolving the drug at 28 ° C. and impregnating the raw material sponge with the above processing solution at 28 ° C., the temperature of the processing solution is raised and maintained at 34 ° C., which is 6 ° C. higher than the cloud point, for 10 minutes. Squeezed with a dehydrator. Thereafter, the sample was heated at 100 ° C. for 30 minutes in the same manner as in Examples 1 and 3, and then washed with water and dried. Finally, the monomer utilization was 7.5%.

  As in Example 1, NK Economer MID-082 having a cloud point of 14 ° C. was used as the polymerizable monomer, and 40 g of sodium lauryl sulfate was used as the surfactant. The cloud point of the monomer alone was 14 ° C., but the cloud point of the treatment liquid was 20 ° C. The drug dissolved at 15 ° C. The treatment liquid was bluish and transparent. Since a surfactant is used, it is a transparent solution despite being above the cloud point of the monomer. After impregnating the raw material sponge with the above treatment liquid at 15 ° C., the treatment liquid was heated and maintained at 25 ° C. for 10 minutes. Then, it squeezed with the centrifugal dehydrator at the same temperature. Thereafter, similarly to Example 1, after heating at 100 ° C. for 30 minutes, washing with water and drying were performed. Finally, the monomer utilization was 7.5%.

  As in Example 1, NK Economer MLR-140 was used as the polymerizable monomer, but 40 g of sodium lauryl sulfate was used as the surfactant. The cloud point of the monomer was 41 ° C., and the cloud point of the treatment liquid was 50 ° C. The chemical | medical agent melt | dissolved at 20 degreeC, the raw material sponge was impregnated with the said process liquid of 20 degreeC, and the process liquid was heated up and it maintained at 60 degreeC for 10 minutes. Then, it squeezed with the centrifugal dehydrator at the same temperature. Thereafter, similarly to Example 1, after heating at 100 ° C. for 30 minutes, washing with water and drying were performed. Finally, the monomer utilization was 7.5%.

  These are summarized in Table 1.

Materials used Yukiron CX Yukigaya Chemical Industry Puff NBR Sponge Apparent density 140kg / m3 8mm thickness 60mmφ Sponge hardness 55 degrees Average bubble diameter 200μm
NK Economer MLR-140 New Nakamura Chemical Co., Ltd. Alkyl polyethylene glycol polypropylene glycol methacrylate Average molecular weight 820 Cloud point 41 ° C Liquid at room temperature NK Economer MID-112 Shin Nakamura Chemical Co., Ltd. Alkyl polyethylene glycol polypropylene glycol methacrylate Average molecular weight 720 Cloud point 26 ℃ Liquid at room temperature NK Economer MID-082 Shin-Nakamura Chemical Co., Ltd. Alkyl polyethylene glycol polypropylene glycol methacrylate Average molecular weight 690 Cloud point 14 ° C Liquid at room temperature V-50 Wako Pure Chemical Industries water-soluble azo compound initiator

Comparative Example 1
As in Example 1, NK Economer MLR-140 was used as the polymerizable monomer. The chemical was dissolved at 20 ° C. and impregnated with 1 kg of sponge at the same temperature, but maintained for 10 minutes without increasing the temperature. Then, it squeezed with the centrifugal dehydrator at the same temperature. In this state, the weight of the sponge after impregnation was 1.5 kg.
Thereafter, in the same manner as in Example 1, heating with hot air was performed with a rotary drum dryer, and the temperature was maintained at 100 ° C. for 30 minutes. The sponge was dried by evaporation of moisture. The weight after cooling was 1.01 kg.
Thereafter, washing with water and drying were performed to remove unreacted monomers and monopolymer. The sponge weight was 1.006 kg.

From the above calculation formula, the treatment liquid impregnation rate was 50%, the monomer adhesion rate was 1%, the graft polymer adhesion rate was 0.6%, and the grafting rate was 60%.
This is 6 g of the actually used monomer among the used monomers, and the monomer utilization rate is 3.8%.

  The resulting sponge was hydrophilic, but it took a while before it soaked in water. Further, the elasticity, softness, and moist feel of the sponge were improved as compared with the raw material sponge, but were not changed as much as in Example 1. A submergence test was performed in the same manner as in Example 1. The time required for the sponge to submerge was 50 seconds.

Comparative Example 2
As in Examples 1 and 2, NK Economer MLR-140 was used as the polymerizable monomer. The chemical was dissolved at 20 ° C., impregnated with sponge at the same temperature, then heated to 85 ° C., which was higher than that in Example 2, and maintained for 10 minutes. Generation of a white resinous material was observed in the treatment liquid. This is considered that the polymerization reaction started during the impregnation treatment and a single polymer was produced. After this, when squeezed with a centrifugal dehydrator at the same temperature, sticky dirt adhered to the sponge. After that, after heating at 100 ° C. for 30 minutes in the same manner as in Examples 1 and 2, washing with water and drying were performed. Even after heating, sticky stains were observed, but also after washing and drying. The completed sponge was highly hydrophilic and absorbed water as soon as water was contained in the sponge. Finally, the monomer utilization was 12.5%. It is thought that the homopolymer produced | generated in the solution is contained.

Comparative Example 3
As in Example 3, NK Economer MID-112 was used as the polymerizable monomer. The chemical was dissolved at 20 ° C., and the sponge was impregnated in the dissolved state at the same temperature, and maintained for 10 minutes without heating. This temperature is 6 ° C. lower than the cloud point of 26 ° C. of the treatment liquid. Then, it squeezed with the centrifugal dehydrator at the same temperature. Thereafter, similarly to Example 3, after heating at 100 ° C. for 30 minutes, washing with water and drying were performed. Finally, the monomer utilization was 3.8%.

Comparative Example 4
As in Example 5, NK Economer MID-082 was used as the polymerizable monomer. The chemicals were dissolved at 20 ° C., which is higher than the cloud point of 14 ° C. of the polymerizable monomer. The monomer did not dissolve, and when the stirring of the treatment liquid was stopped, the monomer settled as droplets on the bottom of the container. The sponge was impregnated at the same temperature, and maintained for 10 minutes without increasing the temperature. Then, it squeezed with the centrifugal dehydrator at the same temperature. Thereafter, similarly to Example 5, after heating at 100 ° C. for 30 minutes, washing with water and drying were performed. Finally, the monomer utilization was 5.6%.
The finished sponge was uneven in appearance and swollen in some places. Differences in elasticity and feel were observed among the sponges. When the dried sponge was soaked with water, a part that was soaked in part was seen.

Comparative Example 5
As in Examples 1 and 2, NK Economer MLR-140 was used as the polymerizable monomer. The chemical was dissolved at 45 ° C., which is higher than the cloud point of 41 ° C. of the polymerizable monomer. The monomer did not dissolve, and when the stirring of the treatment liquid was stopped, the monomer settled as droplets on the bottom of the container. The sponge was impregnated at the same temperature, and maintained for 10 minutes without increasing the temperature. Then, it squeezed with the centrifugal dehydrator at the same temperature. After that, after heating at 100 ° C. for 30 minutes in the same manner as in Examples 1 and 2, washing with water and drying were performed. Finally, the monomer utilization was 5.6%.
The finished sponge was uneven in appearance and swollen in some places. Differences in elasticity and feel were observed among the sponges. When the dried sponge was soaked with water, a part that was soaked in part was seen.

Comparative Example 6
As in Example 5, NK Economer MID-082 was used as the polymerizable monomer, but no surfactant was used in combination. The chemical was dissolved at 10 ° C. to be transparent. After impregnating the raw material sponge at the same temperature, the temperature of the treatment liquid was increased and maintained at 16 ° C. for 10 minutes. Then, it squeezed with the centrifugal dehydrator at the same temperature. Thereafter, similarly to Example 5, after heating at 100 ° C. for 30 minutes, washing with water and drying were performed. Finally, the monomer utilization was 7.5%.

As a result of comparing these examples with comparative examples, the following effects were obtained in the examples compared to those in the comparative examples.
1. Excellent hydrophilicity and excellent for use with water.
2. Soft and good per skin.
3. High utilization efficiency of raw material monomers.
4. A uniform product with few defects can be made.

Evaluation Method For hydrophilicity and submergence tests, water is once contained in the sponge and pressed to squeeze the water inside the sponge. This was placed gently on the surface of the water, and the time for the whole to sink under the surface of the water was measured. Excellent for 3 seconds or less, good for 30 seconds or less, acceptable for more than 30 seconds, and improper for 3 minutes.
The texture was judged by an in-house tester to actually use it for makeup.
Regarding the cloud point, the cloud point of the treatment liquid is determined as follows. If the treatment liquid is almost transparent, it is in a dissolved or solubilized state. If the treatment liquid is cloudy, it is already above the cloud point, so it is cooled to be almost transparent. From this state, the mixture is heated while slowly stirring, and the liquid temperature is slowly increased. When the cloud point is reached, the entire liquid becomes cloudy, and this temperature is taken as the cloud point. The cloud point of the monomer is measured in the same manner as above by preparing a 1% aqueous solution of the monomer.
The sponge hardness was measured with an Asker Durometer F type manufactured by Kobunshi Keiki.
As for the average bubble diameter, a micrograph of the cut surface of the sponge was taken, and the bubble cross section that appeared here was circularly approximated to obtain the average diameter.

Claims (5)

A treatment liquid comprising an aqueous solution containing a polymerizable monomer and having a cloud point of 20 ° C. or higher, wherein a sponge is immersed in the treatment liquid at a temperature state below the cloud point, and the treatment liquid is at or above the cloud point and A sponge that has been hydrophilized and softened, characterized in that the temperature is raised to 80 ° C. or less, and the polymerizable monomer is precipitated and polymerized on the surface and inside of the sponge. The hydrophilization softening treatment according to claim 1, wherein the clouding point of the treatment liquid containing the polymerizable monomer is 20 ° C. to 75 ° C., and the treatment temperature is 25 ° C. to 80 ° C. Sponge. 3. The hydrophilized and softened sponge according to claim 1, wherein the polymerizable monomer is polyethylene glycol acrylate or polyethylene glycol methacrylate. 4. The hydrophilized and softened sponge according to claim 1, wherein a surfactant is added to the aqueous solution of the polymerizable monomer. A treatment liquid comprising an aqueous solution containing a polymerizable monomer and having a cloud point of 20 ° C. or higher, wherein a sponge is immersed in the treatment liquid at a temperature state below the cloud point, and the treatment liquid is at or above the cloud point and A method for producing a hydrophilized and softened sponge, characterized in that the temperature is raised to 80 ° C. or lower, and the polymerizable monomer is precipitated and polymerized on the surface and inside of the sponge.