JPH037694B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides crosslinked rubber particles containing micro water droplets,
The present invention relates to aqueous dispersions thereof and methods for producing them.

Since ancient times, oil-in-water type dispersions have been used, in which oil components such as oil substances, fats and polymers, etc., are dispersed in the form of minute particles in water, and conversely, water-in-oil type dispersions, in which water is dispersed in the form of minute particles in oil components. A variety of dispersions have been made and used in a wide variety of fields.

The present inventor previously proposed an oil-in-water dispersion (O/W-type dispersion) or a water-in-oil dispersion (W/O-type dispersion) in which the oil component is liquid rubber, and particularly the latter. It has been discovered that a water-in-oil dispersion (W/O dispersion) is useful for cold insulation materials, heat insulation materials, or cushioning materials. Thereafter, various studies were conducted regarding this water-in-oil dispersion, focusing on its structure and function, and as a result, they discovered crosslinked rubber particles with distinctive functions, an aqueous dispersion thereof, and a method for producing them, and completed the present invention. I reached it.

That is, one aspect of the present invention resides in crosslinked rubber particles containing minute water droplets, that is, crosslinked rubber particles consisting of crosslinked particles of liquid rubber and minute water droplets encapsulated in the particles. The particles can be easily mixed and dispersed in synthetic resins such as epoxy resins, phenolic resins, and unsaturated polyester resins in which it is difficult to directly disperse water.
Helps provide flame-retardant synthetic resins. In addition, since the particles gradually release water, they can be used as a humidity control material.
It is also useful as a water supply material in reactions where water must be added little by little.

Another aspect of the present invention is an aqueous dispersion containing crosslinked rubber particles containing minute water droplets. That is, it is a so-called W/O/W type dispersion containing double-structured crosslinked rubber particles consisting of liquid rubber crosslinked particles and minute water droplets encapsulated in the particles. The aqueous dispersion provides a poultice that can be applied to the human body when the minute water droplets contain a medicinal ingredient for a poultice such as menthol, camphor, thymol, salicylic acid or methyl salicylate. To provide an aromatic agent that can be applied to a suitable object and gradually release a fragrance when a fragrance is dispersed in water droplets, and furthermore, when a highly reactive chemical substance is contained in the minute water droplets. provide a trapping material that captures certain chemicals.

Note that the minute water droplets do not need to be simply composed of water, and may be an aqueous solution or an aqueous emulsion of various water-soluble chemical substances, as described above. Further, it may be a water-swellable body held in a super absorbent resin.

Furthermore, one aspect of the present invention is to disperse a water component (a water-containing component such as water, an aqueous solution, an aqueous emulsion, or a water-swelled product) in the form of fine particles in a matrix of an oil component containing liquid rubber. A water droplet type dispersion is formed, the dispersion is further dispersed in the form of particles in an aqueous medium, and then the liquid rubber contained in the oil component is crosslinked, and then crosslinked rubber particles are extracted from the aqueous medium. A method for producing crosslinked rubber particles containing minute water droplets, the method comprising separating the particles. What is important here is that the liquid rubber contained as a main component in the oil component must be crosslinked. If the liquid rubber is not crosslinked or the proportion of the liquid rubber used is small, the fluidity of the oil component is high, so depending on the environment in which the water-in-oil dispersion is placed, the dispersion itself may may be destroyed or agglomerated, making it impossible for the present invention to exhibit its intended and unique function. Of course, if the hydraulic component cannot cause crosslinking, it will be impossible to obtain individual crosslinked rubber particles by removing only water from an aqueous dispersion in which a water-in-oil type is dispersed in an aqueous medium. According to the production method of the present invention, the oil component has lost its fluidity due to crosslinking, so
The water-in-oil particle structure is difficult to break even with slight changes in the environment, and the particles can not only be easily removed, but also form a stable aqueous dispersion of rubber particles.

In the present invention, the oil component is one whose main component is liquid rubber. However, plasticizers such as process oil, machine oil, liquid paraffin, and liquid polybutene may be included within the range that does not impair the gist of the present invention. Furthermore, a solid rubber such as natural rubber, polyisoprene rubber, polybutadiene rubber, or styrene-butadiene block copolymer may be included as long as it does not interfere with the dispersion of the water component into the oil component.

If the molecular weight of the liquid rubber used in the present invention is too large, it will not be easy to emulsify and disperse water, making it impossible to obtain a stable water-in-oil dispersion.
Crosslinked rubber particles containing minute water droplets and their aqueous dispersion cannot be obtained. Further, even if a water-in-oil dispersion is obtained, it will not be uniform, and it will not be possible to obtain a dispersion having the desired function in the present invention. On the other hand, if the molecular weight is too low, although the emulsification process itself becomes easier, when crosslinking liquid rubber particles containing minute water droplets, the crosslinking efficiency between the rubbers decreases significantly, causing them to flow easily and retain their shape. As a result, crosslinked rubber particles containing microscopic water droplets, which are desired in the present invention, cannot be obtained, and their unique functions are lost. Therefore, the viscosity average molecular weight of liquid rubber is 500.
A range of 100000 to 100000, particularly 10000 to 80000, is preferred.

In addition, when the glass transition temperature of liquid rubber is high, in crosslinked rubber particles containing minute water droplets or their aqueous dispersion, if the minute water droplets contain medicinal ingredients or fragrances, they may be absorbed through the oil phase. The rate of diffusion of the components slows down, and conversely, when a chemical substance is introduced from the outside of the crosslinked rubber particles into micro water droplets, the rate of diffusion and penetration of the chemical substance into the oil phase slows down. Otherwise, it becomes impossible to obtain an aqueous dispersion thereof, which is not preferable. Therefore, the glass transition temperature of liquid rubber is below 35℃, especially
It is desirable that the temperature is below 10℃.

Examples of liquid rubbers that can be used include liquid diene polymers such as liquid polybutadiene, liquid polyisoprene, liquid polypentadiene, and liquid polychloroprene, liquid butadiene-isoprene copolymers, liquid styrene-butadiene copolymers, and liquid styrene-butadiene copolymers. Isoprene copolymer, liquid acrylonitrile
Liquid diene copolymers such as butadiene copolymers, liquid acrylonitrile-isoprene copolymers, liquid isobutene-isoprene copolymers, liquid ethylene-propylene copolymers, and the like are included.

Among these, liquid polybutadiene, liquid polyisoprene, and liquid butadiene-isoprene copolymer, which are rich in 1,4 bonds, have extremely low glass transition temperatures, so even if their molecular weight is high, their viscosity is relatively low, making them difficult to work with. It is most preferably used because of its excellent properties.

Note that modified liquid rubbers in which the molecular chains of the liquid rubbers contain functional groups such as carboxyl groups, acid anhydride groups, hydroxyl groups, halogen groups, and epoxy groups can also be used, but among them, maleic anhydride-added liquid rubbers can also be used. Tempered liquid rubber is preferably used.

These liquid rubbers may be used alone or in combination of two or more.

In addition to the liquid rubber, the oil component may contain various plasticizers and solid rubbers as described above. Additionally, crosslinking agents, surfactant fillers, surfactants, or other rubber compounding chemicals may be included, as described below.

Next, the method for producing the crosslinked rubber particles containing minute water droplets and the aqueous dispersion thereof according to the present invention will be explained below.

First, a water component, that is, an aqueous solution or emulsion containing chemical substances such as water, medicinal ingredients of a poultice, and fragrances in a matrix of oil components containing liquid rubber, and a water-swollen product made of a super absorbent resin that has absorbed water. A water-in-oil type dispersion having minute water droplets is produced by dispersing a water component such as oil in the form of fine particles. Next, the water-in-oil type dispersion is dispersed in the form of particles in an aqueous medium to produce an aqueous dispersion of oil component particles made of liquid rubber containing minute water droplets. By crosslinking the liquid rubber in the particles of the aqueous dispersion thus obtained using energy rays such as radiation or electron beams, or by using a crosslinking agent pre-contained in the liquid rubber. An aqueous dispersion of crosslinked rubber particles containing minute water droplets is obtained. Crosslinked rubber particles containing minute water droplets are
It can be obtained by separating the aqueous dispersion into an aqueous medium and crosslinked rubber particles using a conventional method such as filtration.
In this way, crosslinked rubber particles containing minute water droplets and an aqueous dispersion containing the crosslinked rubber particles are obtained.

When producing the oil component, rubber compounding chemicals such as a crosslinking agent, a crosslinking aid, a filler, and an antioxidant may be added to the liquid rubber or a mixture of the liquid rubber, a plasticizer, and a solid rubber. . Examples of the crosslinking agent include rubber vulcanizing agents such as sulfur, peroxide compounds, and quinone dioxime, and when the liquid rubber has a functional group, a compound that can react with the functional group. For example, when the functional group is a carboxyl group, metal compounds, epoxy compounds, polyamine compounds,
Further, in the case of a hydroxyl group, an isocyanate compound may be mentioned. As a filler, carbon black,
Examples include calcium carbonate, silica, and clay.

When preparing a water-in-oil dispersion and an aqueous dispersion of oil component particles containing minute water droplets, it is preferable to use a surfactant in order to improve the dispersion stability. The surfactants used here include polyoxyethylene oleyl ether,
Examples include polyoxyethylene lauryl ether, polyoxyethylene stearate, sodium alkylbenzene sulfonate, sodium alkylmethyl taurate, rosinate salt, and oleate salt. To obtain a water-in-oil dispersion, the HLB value must be between 2 and 2.
In order to obtain an aqueous dispersion of oil component particles containing minute water droplets using the surfactant No. 12, it is preferable to use a surfactant with an HLB value of 8 or more, particularly 10 or more. In addition, the surfactant H.
It is preferable to use a surfactant whose LB value is smaller than that of the surfactant used to obtain the water-in-oil dispersion. These surfactants contain oil components,
It is added at the time of dispersion of the water component or aqueous medium, but it may be included in these components in advance.

In addition, when obtaining a water-in-oil dispersion, water, an aqueous solution or emulsion of a chemical substance capable of imparting various functions such as a medicinal ingredient to a poultice or a fragrance, and further water are added to the oil component containing the liquid rubber. The water-swellable body made of the super absorbent resin is dispersed. The medicinal ingredients of the poultice include menthol, camphor,
Examples include thymol, salicylic acid, methyl salicylate, and the like. As the fragrance, osmanthus,
Examples include single floral scents such as rose, citrus scents, mint scents, and bouquet scents. Other chemical substances that provide various functions include water-soluble polymers such as polyvinyl alcohol and methyl cellulose, and chelating agents that absorb ions. The superabsorbent resin has a water absorption capacity of distilled water of 1000 times or less, particularly 10 to 500 times its own weight,
A crosslinked product of a saponified copolymer of vinyl ester and acrylic ester (as a commercially available product, Sumitomo Chemical Co., Ltd.
There is a product name ``Sumikagel'' manufactured by Co., Ltd. ), a crosslinked product of starch-unsaturated carboxylic acid graft copolymer (commercially available product is Sanyo Chemical Co., Ltd. under the trade name "Sunwet")
There is. ), crosslinked carboxymethyl cellulose (commercially available products include the trade name "Aqualon" manufactured by Hercules), self-crosslinking polymers consisting of alkali metal salts of acrylic acid, and crosslinked products of alkali neutralized acrylic acid polymers. , a crosslinked product of an alkali-neutralized copolymer of a vinyl compound such as methyl vinyl, styrene, ethylene, or isobutylene and maleic anhydride.

Dispersion of a water component into an oil component to obtain a water-in-oil dispersion, and dispersion of the water-in-oil dispersion into an aqueous medium to obtain oil component particles containing microscopic water droplets. is carried out by using a conventional stirrer. In particular, when obtaining a water-in-oil dispersion, a stirrer capable of high-speed stirring such as a propeller type stirrer, homomixer, homogenizer, etc. is used. In addition, when using a water-swollen body in which water is absorbed by a superabsorbent resin as the water component that forms minute water droplets, the water-swelled body can be stably dispersed in the oil component even at an extremely low stirring speed. Furthermore, when dispersing a water-in-oil dispersion containing microscopic water droplets into an aqueous medium, high-speed stirring is not necessarily necessary; rather, if the stirring is too vigorous, the oil component containing liquid rubber may Moderate agitation is appropriate as it breaks up the microscopic water droplets in the particles.

If the content of the water component in the water-in-oil dispersion is too small, the desired functions of the present invention cannot be obtained, and if it is too large, the water-in-oil dispersion becomes unstable. Furthermore, when the water-in-oil dispersion is dispersed in water, the minute water droplets are easily broken, so it is preferably 5 to 60% by weight, particularly 10 to 50% by weight of the water-in-oil dispersion.
Note that the above ratio of the water-in-oil dispersion is also the ratio of crosslinked rubber particles.

The size of water droplets in a water-in-oil dispersion is
Although not particularly specified, the size is preferably such that the final crosslinked rubber particles containing micro water droplets include several to several hundreds of micro water droplets.

Considering the stability of the dispersion, the content of the oil component particles containing minute water droplets and their crosslinked product, that is, the crosslinked rubber particles containing minute water droplets, in the aqueous dispersion is 15 to 75% by weight, especially 30-65
Weight percent is preferred.

The size of the oil component particles and crosslinked rubber particles containing minute water droplets is preferably 5 mm or less in particle size. In the case of particles containing microscopic water droplets containing the medicinal ingredient or fragrance of a poultice, a particle size of 2 mm or less is more preferable in consideration of the diffusion efficiency or absorption efficiency of the chemical substance.

The oil component particles containing minute water droplets obtained in this way are considered to be crosslinked rubber particles, but the crosslinking methods include a crosslinking method using energy rays such as radiation and electron beams, and a method in which the particles are pre-incorporated into liquid rubber. There are crosslinking (vulcanization) methods using sulfur, peroxide compounds, quinone dioxime, etc., and further crosslinking methods using metal compounds, epoxy compounds, polyamine compounds, isocyanate compounds, etc. that are pre-contained in modified liquid rubber containing functional groups. Can be mentioned. The crosslinking agent may be mixed into the oil component in advance, or may be mixed during the preparation of the water-in-oil dispersion. Furthermore, it may be added to the aqueous medium when the water-in-oil dispersion is dispersed in the aqueous medium.

The crosslinking reaction when using a crosslinking agent can be carried out at room temperature, but it is preferably carried out under heating at 40 to 100°C in order to accelerate the crosslinking reaction.

In this way, an aqueous dispersion containing crosslinked rubber particles containing minute water droplets is obtained, but a conventional method such as filtration is used to separate the crosslinked rubber particles from the aqueous dispersion. be done.

The crosslinked rubber particles containing minute water droplets and their aqueous dispersion of the present invention can be used as humidity conditioners, fragrances, poultices, It is useful in a wide range of applications, such as chemical substance capture agents, oral removal agents, wastewater treatment agents, water-containing adhesives, water-containing sealants, and plastic flame retardants.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. In addition, "parts" in the examples mean "parts by weight" unless otherwise specified.

Example 1 To 100 parts of liquid polybutadiene rubber with a 1,4 bond content of 83% and a viscosity average molecular weight of 20,000 obtained by polymerizing butadiene using a lithium catalyst, 2 parts of sulfur and 2 parts of zinc stearate were added. types of vulcanization accelerators (zinc dimethyldithiocarbamate,
Zinc ethyl phenyl dithiocarbanate) 2 parts each,
and 12 parts of a surfactant (polyoxyethylene nonyl phenyl ether) with an HLB value of 7.8,
Mixed in a turbine type stirrer maintained at 50°C. Next, while vigorously stirring the mixture thus obtained, 30 parts of a medicinal agent aqueous solution (an aqueous solution containing 1 part of methyl salicylate and 2 parts of ethyl salicylate) for a cataplasm was gradually added, followed by 2.5 parts of bentonite. A water-in-oil dispersion (W/O dispersion) was obtained. The dispersion was stable.

Next, the above dispersion was added to 100 parts of a 3% aqueous solution of a surfactant (polyoxyethylene sorbitan laurate) with an HLB value of 17 while stirring to obtain a dispersion in which oil component particles containing minute water droplets were dispersed in water. (W/O/W type dispersion) was obtained. The dispersion had oil component particles with an average particle size of about 0.5 mm and was highly stable. When the dispersion was left at room temperature for one week, it was observed that the liquid rubber in the oil component was crosslinked. Therefore, the stability of the dispersion was further improved.

Immediately after preparing the aqueous dispersion (W/O/W type dispersion) of oil component particles obtained in this way,
The liquid polybutadiene rubber was vulcanized with sulfur by heating for a certain period of time. In this way, an aqueous dispersion of crosslinked rubber particles containing minute water droplets was obtained. The average particle diameter of the crosslinked rubber particles is 0.5
It was warm in mm.

Next, using the aqueous dispersion containing crosslinked rubber particles, water was removed by a filtration method to obtain crosslinked rubber particles containing minute water droplets.

Example 2 Cis-1,4 bond amount 82%, viscosity average molecular weight
By reacting maleic anhydride with 29000 liquid cis-1,4-polyinprene rubber (manufactured by Clareisoprene Chemical Co., Ltd., trade name Kuraprene LIR-30), 2.5 parts of maleic anhydride was added to 100 parts of the liquid rubber. An added modified liquid rubber was obtained. 100 parts of the above modified liquid rubber and 100 parts of naphthenic process oil
1 part, 5 parts zinc oxide, and a surfactant (polyethylene glycol oleyl ether) with an HLB value of 6.
Then, 50 parts of a perfume aqueous dispersion (a liquid containing 2 parts of geraniol dispersed in it) was gradually added to the resulting mixture under vigorous stirring, and the perfume-containing dispersion (O/W/O type dispersion) was obtained. Subsequently, 100% of a surfactant aqueous solution (5% aqueous solution of potassium oleate) was added into the dispersion (O/W/O type dispersion).
was added under stirring to obtain a dispersion (W/O/W/O type dispersion) in which oil component particles encapsulating microdroplets of an aqueous perfume dispersion were dispersed in water. The mixture was then left at room temperature for 7 days to obtain an aqueous dispersion of rubber particles crosslinked with zinc oxide.

When the thus obtained aqueous dispersion of crosslinked rubber particles containing microdroplets of the aqueous perfume dispersion liquid was applied to a box, a fragrance was observed, indicating that it could be used as a fragrance.

Example 3 Liquid cis-1,4-polyisoprene rubber (manufactured by Clarei Soprene Chemical Co., Ltd., trade name: Kuraprene)
LIR-30) 100 parts, liquid paraffin 90 parts, masticated natural rubber 10 parts, sulfur 3 parts, zinc stearate 3 parts
1 part, 2 parts of zinc diethylcarbamate, 3 parts of zinc 2-methylthiazole, and 1 part of diorthotolylguanidine, and then 5 parts of a surfactant (polyethylene glycol oleyl ether) with an HLB value of 6 was added thereto to form a liquid. A rubber-containing mixture was obtained.

On the other hand, a partial sodium salt of isobutylene-maleic anhydride alternating copolymer (manufactured by Clareisoprene Chemical Co., Ltd., Isoban-10) having a molecular weight of about 160,000 was cross-linked with glycerin diglycidyl ether,
A super absorbent resin powder capable of absorbing distilled water 1500 times its own weight was prepared, and then 20 times the amount of water was added to the resin powder 1 to obtain a water-swollen body containing 20 times its own weight of water.

Next, the water-swollen material is added to the liquid rubber-containing mixture, and the water-swollen material is encapsulated in fine particles while being stirred. A dispersion was formed, and then the dispersion was added to 180 parts of an aqueous solution containing 2 parts of a surfactant (polyoxyethylene lauryl ether) with an HLB value of 16 under stirring to encapsulate water-swelled microparticles. An aqueous dispersion of oil component particles was obtained. Next, the dispersion was heated to 80° C. for 30 minutes to vulcanize the liquid rubber with sulfur to obtain an aqueous dispersion of crosslinked rubber particles containing water-swelled microparticles.

The thus obtained aqueous dispersion was applied to a towel cloth and then dried to obtain a towel cloth to which crosslinked rubber particles encapsulating water-swellable microparticles were attached. After cooling the towel in the freezer, I took it out and then wrapped it around my neck to examine its cooling effect.It was found that it was easily wrapped around the neck and did not make me feel like I was wearing a foreign object, and that it had a sufficient cooling effect. .

Claims (1)

[Claims] 1. Crosslinked rubber particles containing minute water droplets. 2. An aqueous dispersion containing crosslinked rubber particles containing minute water droplets. 3. A water-in-oil type aqueous dispersion is formed by dispersing a water component in the form of fine particles in a matrix of an oil component containing liquid rubber, and the dispersion is further dispersed in a particulate form in an aqueous medium. A method for producing crosslinked rubber particles containing minute water droplets, the method comprising: then crosslinking the liquid rubber contained in the oil component, and then separating the crosslinked rubber particles from the aqueous medium.