JPH10287720A - Graft polymerization process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a graft polymn. process whereby the surface of a substrate can be controlled with a high degree of freedom; the polymn. can be carried out even in the case of a water-incompatible monomer; and the formation of a homopolymer can be inhibited. SOLUTION: Droplets of an aq. soln. contg. a graft polymn. initiator and suspended or emulsified in an org. solvent are reacted with the surface of a substrate, i.e., an object of graft polymn., to form polymn. initiation sites on the surface, and a polymerizable unsatd. compd. is grafted onto the initiation sites. Then, if necessary, the second graft polymn. is conducted wherein a polymerizable unsatd. compd. other than the aforementioned is grafted onto the parts of the surface where the former unsatd. compd. has not been grafted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel method for graft-polymerizing a polymerizable unsaturated compound onto a substrate surface.

[0002]

2. Description of the Related Art Various graft polymerization methods are known as effective means for modifying a material or a material surface. By way of example, radiation or redox initiators, utilizing the reaction between the ionic initiator and the material or the chain transfer of the radical initiator, to generate active sites in the material or on the material surface,
Thus, a method of polymerizing a polymerizable unsaturated compound (hereinafter sometimes referred to as “polymerizable monomer”) (Adv.
Polym. Sci. Vol. 4, p111, 1965
), A method of introducing a polymerizable unsaturated bond into a material and using this to polymerize a polymerizable monomer (J. Pol
ymer Sci. , Part-A, 3, p1031,
1965, described in JP-B-5-5845, etc.),
A method of introducing a structure as an initiator into a material and polymerizing a polymerizable monomer using the structure (Tappi, Marc)
h, 56, p97, 1973, JP-A-6-28724.
No. 3 publication). Among these methods, the method is preferably used, and in particular, a system using an initiator is widely used.

As a graft polymerization initiator (hereinafter sometimes simply referred to as “initiator”), a redox-based one is industrially used, and ceric ammonium nitrate,
Fenton's reagent (H ₂ O ₂ / Fe system and the like), manganese system and the like are known. In the graft polymerization using these initiators, polymerization is generally performed in water or a water-mixed solvent system. These graft polymerization techniques are described as examples of graft polymerization to a hydrophilic polymer, such as "Fusayoshi Masuda: Superabsorbent Polymer: New Polymer One Material-4: Edited by The Society of Polymer Science" and "J. Appl. Polymer Sc.
i. , 19, p1257, 1975 "and the like. In the conventional graft polymerization, the amount of the graft polymer formed on the target material or the substrate surface for graft polymerization (generally referred to as graft ratio) is determined by the type or structure of the initiator or the starting point, the concentration of the initiator, It is controlled by the selection of the monomer concentration and the solvent.

[0004]

However, in a conventional graft polymerization method, particularly in a system using a redox-based initiator, it is difficult to control the molecular weight and the graft ratio of the graft polymer, and it is difficult to form the polymer on a substrate. It was difficult to control the higher order structure such as the morphology and area density of the graft polymer. That is, the number of molecules of the polymerizable monomer that becomes a graft polymer bonded per unit area on the substrate surface can be changed depending on the initiator concentration or the like, but the bonding density is not uniform on the surface. It was difficult to obtain a surface structure composed of a portion (domain) composed of a bonding portion of a graft polymer and a domain of a non-graft portion. On the other hand, there is an attempt to obtain the above-mentioned higher-order structure by partially masking the substrate surface and graft-polymerizing only the non-masked portion (Japanese Patent Publication No. 62-7931), but there are limitations such as complicated processes. It is not practical and cannot be applied to polyhedral substrates such as fibers and particles. Modification of the higher-order structure of the substrate surface as described above is useful in various applications as a means of modifying surface physical properties such as three-dimensional space, electric potential, and free energy. The degree of freedom is low and not enough. In addition, conventionally, having a plurality of functions on the surface of the base,
In order to obtain a so-called functional surface, a graft polymer itself to be grafted onto a substrate has been used as a copolymer, but in this case, surface physical property modification in a micro unit,
The function that can be expressed only by a certain amount of macro-assembly of the graft polymer cannot be obtained by such surface property modification.

[0005] In the conventional graft polymerization method, when the graft polymerization is carried out in an aqueous solvent, a large amount of a polymer product (hereinafter, referred to as "homopolymer") that is not grafted to a target material is formed, and the reaction efficiency is reduced. In addition, there is a problem that purification of the product requires a great deal of labor. As a method of suppressing the formation of this homopolymer,
A technique in which an initiator is reacted with a material or a substrate in an aqueous solvent in advance, and then the solvent is replaced with a non-aqueous solvent to perform graft polymerization (ACS, Symp. Ser., No. 1).
87, p45, 1982), but it is troublesome and industrially unsuitable, for example, the solvent must be replaced under an inert gas.

Accordingly, an object of the present invention is to provide a high degree of freedom in controlling the amount, density and the like of the graft polymer formed on the surface of the substrate on which the graft polymerization is to be carried out. To provide a graft polymerization method capable of freely controlling a higher-order structure such as a sea-island-like (mottle-like) structure between a domain consisting of a group of graft polymer-binding portions and a non-graft portion. It is in. Another object of the present invention is to provide a graft polymerization method that can easily perform graft polymerization even with a non-aqueous polymerizable monomer that cannot be polymerized by a conventional method in an aqueous solvent. . It is a further object of the present invention to provide a graft polymerization method capable of easily suppressing the formation of a homopolymer during polymerization.

[0007]

The above object is achieved by the present invention described below. That is, the present invention is to react a droplet of the aqueous solution in a suspension or emulsion comprising an aqueous solution containing a graft polymerization initiator and an organic solvent with a substrate surface to be subjected to graft polymerization, A graft polymerization method comprising forming a polymerization initiation point on the surface of a substrate and then graft-polymerizing a polymerizable unsaturated compound on a portion of the substrate surface where the polymerization initiation point is formed. Further, the present invention provides, as the first graft polymerization, a droplet of the aqueous solution in a suspension or an emulsion containing an aqueous solution containing a graft polymerization initiator and an organic solvent, and a substrate to be subjected to graft polymerization. Reacting with the partial surface, graft-polymerizing the polymerizable unsaturated compound only on the partial surface of the substrate where the polymerization initiation point is formed, and further as the second graft polymerization, the first graft polymerization of the substrate is not formed. A graft polymerization method comprising graft-polymerizing a polymerizable unsaturated compound different from the polymerizable unsaturated compound on a partial surface.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
According to the graft polymerization method of the present invention, an aqueous solution containing a graft polymerization initiator (hereinafter, sometimes referred to as “initiator solution”) is suspended in an organic solvent (suspension state).
Alternatively, by dispersing it in an emulsified state (emulsion state) and reacting it with a substrate, a polymerization initiation point can be selectively generated on the reaction surface. Therefore, by selectively graft-polymerizing the polymerizable monomer in the domain where the polymerization initiation point is formed, a graft polymer can be formed in a sea-island manner. That is, it is possible to form a graft polymer while leaving the non-grafted surface.

FIG. 1 is a schematic diagram showing the process of graft polymerization according to the method of the present invention. In FIG.
When a droplet of the initiator solution in the suspension or emulsion comes into contact with the substrate (a), the initiator reacts with the substrate to form a polymerization initiation point (b), and a polymerizable monomer is formed at the polymerization initiation point. Grafting forms a graft polymer (c).

The size, density, shape, etc. of the domains formed by the aggregate of the graft polymer bonded to the substrate surface are as follows:
The size of the droplet formed by the initiator solution in the suspension or the emulsion, the ratio of the substrate and the initiator solution (for example, the ratio of the surface area of the droplet to the substrate), and the stirring conditions of the suspension or the emulsion And so on. For example, if the size of the droplet of the initiator solution is increased, the size of the domain formed on the substrate is also increased, and if the mixing ratio of the initiator solution to the substrate is increased, the density of the domain is increased. By increasing the mixing ratio of the agent solution, a graft polymer can be formed on the entire surface of the substrate. Also,
When a liquid flow is generated by stirring, shearing, or the like the suspension or emulsion during the reaction, a domain shape corresponding to the liquid flow is obtained.

The specific conditions are as follows. Droplet size (droplet diameter) of suspension or emulsion formed by dispersing initiator solution in organic solvent
Is in the range of 0.001 μm to 1 mm, preferably 0.0
In the range of 01 to 100 μm, more preferably 0.01 to 1
It is selected from the range of 0 μm. Such a suspension or emulsion is obtained by mixing the above-mentioned initiator solution and an organic solvent, and then a roll mixer, a homogenizer, an ultrasonic disperser,
V type mixer, ribbon type mixer, paddle type mixer, screw type mixer, kneader, pressure type kneader, can be prepared by stirring or dispersing with a stirrer or disperser such as a double bowl type kneader, The droplet diameter of the initiator solution in the suspension or emulsion can be adjusted by the intensity of stirring, time, temperature, type of organic solvent, other additives (for example, surfactant), and the like.

The ratio of the surface area of the substrate to the initiator solution is:
It is selected from the range of 1:10 ⁶ to 10 ⁸ : 1. The mixing ratio of the substrate and the initiator solution is 1: 1 to 100 by volume.
It is selected from the range of 00: 1. The concentration of the initiator contained in the aqueous solution is preferably in the range of 0.1% by weight to 80% by weight. The ratio of the aqueous solution containing the initiator dispersed in the organic solvent is preferably in the range of 0.01% by weight to 10% by weight. Examples of a method of applying a liquid flow to a suspension or an emulsion during a reaction include a method using a rotating blade, a method of ejecting a liquid from a nozzle, and a method of ejecting an initiator solution in a gas to react with a substrate. Can be

FIG. 2 is a schematic view showing an example of a higher-order structure of the substrate surface formed by the graft polymerization method of the present invention. (A) shows the domain structure of the graft polymer formed on the substrate surface when an initiator solution having a uniform droplet diameter is used. (B) shows the domain structure of the graft polymer formed on the substrate surface when an initiator solution having a distribution of droplet diameters is used. (C)
Shows the domain structure of the graft polymer formed on the surface of the substrate when the mixing ratio of the initiator solution to the substrate is increased. (D) shows a state in which the blending ratio of the initiator solution to the substrate is further increased, and the graft polymer is formed on the entire surface of the substrate.
(E) shows the domain structure of the graft polymer formed on the surface of the substrate when a shear by high-speed stirring is applied in the reaction process between the droplet of the initiator solution and the substrate.

Further, in the present invention, it is possible to form different domains of different types of graft polymers on a substrate. Specifically, as shown in FIG. 3, first, as a first graft polymerization, a droplet of an initiator solution in a suspension or an emulsion of an initiator solution and an organic solvent is reacted with a partial surface of a substrate. The polymerization starting point is partially formed, and the polymerizable monomer is grafted only on the partial surface of the substrate where the polymerization starting point is formed to form a graft polymer A (a), and then the second grafting is performed. As the polymerization, another graft polymer B is formed on the partial surface of the substrate surface where the first graft polymerization is not formed (b).

At this time, if the second graft polymerization is carried out by the method of the present invention, a surface state having two AB polymer domains can be obtained as shown in FIG. In this case, the unreacted portion where neither of the two AB graft polymers is formed is further subjected to the third and fourth portions.
... n-th and n-th graft polymerizations of the present invention can be performed, and domains composed of n kinds of graft polymers can be provided on the surface of the substrate. On the other hand, in the case where the second graft polymerization is carried out in a conventional aqueous solvent, or in the case of the method of the present invention, when the concentration of the initiator solution relative to the substrate is sufficiently increased, FIG. As shown in (1), a surface state in which a graft polymer A is formed and a domain where the graft polymer B is formed except for the domain can be obtained.

Next, the materials used in the method of the present invention will be described. As the initiator, a water-soluble redox radical polymerization initiator is preferably used, and a cerium salt-based compound such as ceric ammonium nitrate, H ₂ O
It is possible to use a ₂ / Fe-based Fenton's reagent, a manganese salt-based compound, a vanadium salt-based compound, a cobalt complex and the like, and various compounds such as an acid may be added in combination therewith. As the aqueous solvent for dissolving the initiator, water, a mixture of water and alcohol, a mixture of water and ether, a mixture of water and ketone, and the like can be used. As the organic solvent for dispersing the aqueous solution containing the initiator, various solvents such as aromatic, aliphatic, ester, ether, and halogen solvents can be used.Examples include toluene, benzene, xylene, hexane, and cyclohexane. ,
Examples thereof include ethyl acetate, butyl acetate, methylene chloride and the like and a mixed solvent thereof. Further, it is preferable that the organic solvent does not dissolve the base material during the graft polymerization.

As a substrate for graft polymerization, an organic compound such as a polymer or an inorganic compound can be used. To be more specific, a polymer material having a reducing group such as a hydroxy group, an aldehyde group or an amino group, or a polymerizable group such as an unsaturated double bond in the molecule or on the surface of a substrate, or a similar material on the surface of an inorganic material Materials obtained by introducing a group by a reaction or the like are included. In particular, in a system using a redox polymerization initiator, a material having a reducing group such as a hydroxy group, an aldehyde group, or an amino group is preferable. Further, a material having high hydrophilicity is preferable from the viewpoint of affinity with the droplet of the aqueous solution containing the polymerization initiator which is a feature of the present invention. If these are exemplified, cellulose derivatives such as cellulose and methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, sulfonated methylcellulose, starch and substituted derivatives similar to the above cellulose, algose derived from seaweed, carrageenan and alginic acid, crustaceans Derived chitin and chitosan and derivatives thereof, plant-derived pectin and konjac mannan, microorganism-derived juran gum, xanthan gum and curdlan, polysaccharides such as hyaluronic acid and polyvinyl alcohol and derivatives thereof, poly (meth) acrylic acid and derivatives thereof, Synthetic polymers such as vinyl alcohol- (meth) acrylic acid copolymer, polyallylamine, natural proteins, poly (γ-glutamic acid), poly (ε -Lysine) and the like. Further, these polymers may be a three-dimensional crosslinked structure or a so-called polymer gel. Further, it is preferable that the base material does not dissolve in the organic solvent during the graft polymerization. The substrate may be composed of a plurality of materials. For example, a specific material, for example, a resin such as polyester, polyamide, polystyrene, poly (meth) acrylate, polyethylene, polypropylene, polyacetal, or polyether and the above-described reducing group may be used. And a blend with a polymer material. As the form of the base material, various materials such as blocks, films, tubes, fibers, particles, microcapsules, and those coated on a substrate can be used.

The polymerizable monomers usable for the graft polymerization include (meth) acrylate compounds, (meth) acrylic acid, vinyl sulfonate, (meth) acrylamide and derivatives thereof, vinyl acetate, vinylpyrrolidone, styrene and halogens thereof. Alkyl, heteroatom-substituted compound, ethylene, butadiene, isoprene, propylene,
Unsaturated compounds such as (meth) acrylonitrile, vinyl chloride and vinylidene chloride; divinyl compounds such as divinylbenzene; di (meth) acrylate compounds such as ethylene glycol di (meth) acrylate; tri (meth) acrylate compounds; tetra (meth) One or a mixture of crosslinkable monomers such as acrylate compounds and di (meth) acrylamide compounds such as methylenebis (meth) acrylamide.

In the combination of a substrate and a graft polymer formed thereon, when cellulose, chitin, chitosan, or the like (film, fiber, etc.) is used as the substrate, poly (meth) acrylic acid, polymaleic acid, poly (vinyl sulfonate) is added thereto. The product obtained by grafting, or a salt thereof, a copolymer or a crosslinked product thereof, can be used as a medical material, a water-absorbing material, a fiber for clothing, a water-absorbing fiber, an adsorbent, and the like.
When cellulose particles or fibers are used as the substrate, an amino group-containing polymer, a polymer containing a carboxyl group or a sulfonic acid group or a crosslinked product thereof are grafted with an ink additive, a thickener, a flocculant, It can be used as an adsorbent. In the case of using microcapsules having shells made of polymer particles or polyurea such as polyester particles or styrenic resins contained in coloring materials or inks as base materials, poly (meth) acrylates or atom-containing poly (meth) acrylic Those grafted with acid esters, poly (meth) acrylic acid, and copolymers and crosslinked products thereof can be used for electrophotographic toners, ink jet recording inks, and the like. When a gel such as starch, chemically modified cellulose or agarose or a particle thereof is used as a base, poly (meth) acrylic acid, polymaleic acid, poly (vinyl sulfonate) or a salt thereof, and a copolymer or cross-linked product thereof are used. The grafted product can be used as a superabsorbent resin. The combination and use of the substrate and the graft polymer are not limited to those described above.

In particular, the method of forming a sea-island structure on the surface of a substrate by the method of the present invention includes, for example, charge control of an electrophotographic material such as toner and carrier, medical material having high compatibility with blood,
It is applicable to column materials such as affinity chromatography. Further, if two or more types of graft polymers are formed on the substrate surface by the method of the present invention, a substrate surface having a plurality of functions derived from each graft polymer can be obtained. Medical material applications,
It can be applied to chromatography applications and the like.

Next, the graft polymerization method of the present invention will be described in more detail. When an aqueous solution containing an initiator is dispersed in an organic solvent to form a suspension or an emulsion, the aqueous solution containing the initiator is previously stirred in a predetermined amount of an organic solvent by a shaking or rotary stirring device or ultrasonic irradiation. Even if the suspension or emulsion is dispersed by stirring such as by applying ultrasonic waves to the reaction system, and then added to the reaction system, the dispersion is performed in the same manner after adding the aqueous solution containing the polymerization initiator in the reaction system. It does not matter. In this dispersion process, it is preferable to add a surfactant, and in particular, a low H.O. L. Those having a B value (hydrophilic-hydrophobic balance) are preferable, and examples thereof include sorbitol esters and ethylene oxides. The preferable addition amount of the surfactant is in the range of 0.01% by weight to 10% by weight based on the organic solvent.

The substrate and the droplets of the aqueous solution containing the above-mentioned initiator are brought into contact with and reacted in an organic solvent by stirring with a shaking or rotary stirring device or applying ultrasonic waves with an ultrasonic irradiation device. Radicals are generated on the surface,
This serves as the polymerization starting point. The polymerizable monomer may be added to the reaction system in advance, or may be added after the polymerization starting point is formed on the substrate. A preferable operation in the above step is to mix a substrate and an organic solvent, add a polymerizable monomer thereto, and further add a suspension or emulsion obtained by forming a suspension or emulsion of an aqueous solution containing an initiator in another step. Or a substrate and an organic solvent are mixed, and a suspension or emulsion of an aqueous solution containing an initiator in a suspension or emulsion is added thereto, and after stirring, a polymerizable monomer is added. Polymerizes.

The above-mentioned radical polymerization operation and reaction are preferably carried out in an inert gas atmosphere of nitrogen, argon, helium or the like as in the prior art. The molecular weight of the formed graft polymer can be controlled by the initiator concentration and the polymerizable monomer concentration in the same manner as in the prior art. Generally, when the initiator concentration is reduced or the polymerizable monomer concentration is increased, the molecular weight of the graft polymer is increased. Get higher.

In the graft polymerization method of the present invention, an aqueous solution containing a polymerization initiator is formed into a suspension or emulsion, and is reacted with a substrate to form a reactive surface and a non-reactive surface, thereby polymerizing the substrate surface into a domain. One of the features is that a higher order structure such as a sea-island surface structure can be controlled by generating a starting point and selectively graft-polymerizing the starting point. That is, in modification of the substrate surface by graft polymerization, the higher-order structure and morphology of the surface can be controlled more precisely and more precisely. When the size and concentration of the droplet of the initiator solution contained in the suspension or the emulsion are changed, the size and density of the domain of the polymerization initiation point formed on the substrate are changed accordingly. When the domain is small, it becomes a small domain, on which a graft polymer is formed, and since the density of the domain of the graft polymer on the substrate surface changes according to the concentration of the droplet, the domain is formed on the substrate surface. The structure and density of the graft polymer can be arbitrarily controlled. In addition, the shape of the graft polymer domain formed on the substrate can be controlled by contacting the droplet of the initiator solution with the substrate and applying agitation, rotational force, and the like during the reaction process.

Since the graft polymerization is based on the reaction principle between the substrate and the initiator as described above, the surface structure of the substrate can be controlled not only by using a planar body but also by using a polyhedron such as fibers or particles. is there. In addition, the method of the present invention is an organic solvent-based polymerization reaction system except for around the polymerization initiation point, so that chain transfer and the like of radicals into the solvent are suppressed, and therefore, the production of homopolymer is suppressed and the graft efficiency is high. Can be polymerized. Furthermore, since the method of the present invention is an organic solvent-based polymerization reaction system, a water-insoluble monomer can be used as the polymerizable monomer for graft polymerization.

[0026]

【Example】

Example 1 A cellophane film piece (about 25 μm in thickness, 1 cm × 1 cm in size, specific gravity about 1.2,
Volume: about 8.33 cm ³ , surface area: about 6666 cm ² ) 10
g was placed in a reaction vessel equipped with a stirrer, and 35 ml of an organic solvent, toluene, was added thereto. The inside of the reaction vessel was replaced with nitrogen, and the subsequent steps were performed under nitrogen. 0.135 g of ceric ammonium nitrate as a polymerization initiator, 2N-
0.6 ml of a nitric acid aqueous solution (about 0.7
2 ml) was mixed under nitrogen with 5 ml of a toluene solution in which 0.04 g of Sorgen 50 (sorbitan monostearate: manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was dissolved as a surfactant, and stirred to obtain a suspension solution (a solution of the initiator solution). Drop size: about 8 μm)
This was added into a reaction vessel, stirred, and reacted with a cellophane film piece by stirring for 2 minutes [substrate: droplet of initiator solution = 1: 1 (surface area ratio), 12: 1 (volume ratio)]. .
Thereafter, the reaction vessel was placed in a constant temperature bath set at 25 ° C. 10 g of styrene as a water-insoluble monomer was added as a polymerizable monomer, and graft polymerization was performed for 5 hours. After completion of the polymerization, the sample was washed with distilled water and dried.

The weight of the sample was about 12.5 g, and from the increase in weight, the graft ratio was 25% [） (12.5-10)
/ 10 ° × 100]. The weight of the polymer component extracted into the washing solution was measured. As a result, the weight was about 0.1 g, and it was confirmed that almost no homopolymer was generated. As a result of an IR surface analysis of this sample, it was found that polystyrene was uniformly graft-polymerized on the entire surface of the substrate.

Example 2 A cellophane film piece (about 25 μm thick, 1 cm × 1 cm, specific gravity about 1.2, volume about 8.33 cm ³ , surface area about 6666 as a substrate sample)
cm ² ) was placed in a reaction vessel equipped with a stirrer, and 35 ml of an organic solvent, toluene, was added thereto. The inside of the reaction vessel was replaced with nitrogen, and the subsequent steps were performed under nitrogen. Ceric ammonium nitrate 0.135 as a polymerization initiator
g of a 2N-nitric acid aqueous solution (about 0.72 ml as an initiator solution) and Sorgen 50 as a surfactant.
(Sorbitan monostearate: manufactured by Daiichi Kogyo Seiyaku) 0.
The solution was mixed under nitrogen with 5 ml of a toluene solution in which 04 g was dissolved, and stirred to form a suspension solution (droplet diameter of the initiator solution: about 8 μm).
m) was added to a reaction vessel, stirred, and reacted with a cellophane film piece by stirring for 2 minutes [substrate: initiator solution droplet = 1: 1 (surface area ratio), 12: 1
(Volume ratio)]. Thereafter, the reaction vessel was placed in a constant temperature bath set at 25 ° C. Acrylic acid 10 as a polymerizable monomer
g was added and graft polymerization was performed for 5 hours. After polymerization,
The sample was washed with distilled water and dried.

The weight of the sample was about 15.5 g, and the graft ratio was 55% based on the weight increase. The weight of the polymer component extracted into the washing solution was measured. As a result, the weight was about 0.2 g, and it was confirmed that a homopolymer was hardly generated. The graft polymer portion (polyacrylic acid) of this sample was dyed with a cationic dye and observed under a microscope. As a result, it was found that the polymer was uniformly graft-polymerized on the substrate surface.

Example 3 Cellophane film pieces (thickness: about 25 μm, size: 1 cm × 1 cm, specific gravity: about 1.2, volume: about 8.33 cm ³ , surface area: about 6666) as a substrate sample
cm ² ) was placed in a reaction vessel equipped with a stirrer, and 35 ml of an organic solvent, toluene, was added thereto. The inside of the reaction vessel was replaced with nitrogen, and the subsequent steps were performed under nitrogen. Cerium ammonium nitrate 0.045 as a polymerization initiator
g, 2 ml of a 2N-nitric acid aqueous solution (about 0.24 ml as an initiator solution), and Solgen 50 as a surfactant.
(Sorbitan monostearate: manufactured by Daiichi Kogyo Seiyaku) 0.
The solution was mixed with 5 ml of a toluene solution in which 02 g was dissolved under nitrogen, and stirred to obtain a suspension solution (droplet diameter of the initiator solution: about 8 μm).
m) was prepared, added to a reaction vessel, stirred, and reacted with a cellophane film piece by stirring for 2 minutes [substrate: initiator solution droplets = 3: 1 (surface area ratio), 35: 1
(Volume ratio)]. Thereafter, the reaction vessel was placed in a constant temperature bath set at 25 ° C. Acrylic acid 10 as a polymerizable monomer
g was added and graft polymerization was performed for 5 hours. After polymerization,
The sample was washed with distilled water and dried.

The weight of the sample was about 14.5 g, and the graft ratio was 45% from the weight increase. The weight of the polymer component extracted into the washing solution was measured. As a result, the weight was about 0.2 g, and it was confirmed that a homopolymer was hardly generated. The graft polymer part (polyacrylic acid) of this sample was stained with a cationic dye, and observed under a microscope. As a result, the sea-island structure of the stained part and the unstained part was observed, indicating that the sample had an uneven surface structure. Was. The size of the domain of the stained portion was centered in the range of about 20 to 50 μm.

Example 4 Cellophane film pieces (thickness: about 25 μm, size: 1 cm × 1 cm, specific gravity: about 1.2, volume: about 8.33 cm ³ , surface area: about 6666)
cm ² ) was placed in a reaction vessel equipped with a stirrer, and 35 ml of an organic solvent, toluene, was added thereto. The inside of the reaction vessel was replaced with nitrogen, and the subsequent steps were performed under nitrogen. Cerium ammonium nitrate 0.045 as a polymerization initiator
g, 2 ml of a 2N-nitric acid aqueous solution (about 0.24 ml as an initiator solution), and Solgen 50 as a surfactant.
(Sorbitan monostearate: manufactured by Daiichi Kogyo Seiyaku) 0.
2 g was dissolved in 5 ml of a toluene solution dissolved under nitrogen,
Stirring was performed to prepare an emulsified solution (droplet diameter of the initiator solution: about 1 μm), which was added to the reaction vessel, stirred, and reacted with a cellophane film piece by stirring for 2 minutes [substrate: initiator Solution droplet = 1: 2 (surface area ratio), 35: 1 (volume ratio)]. Thereafter, the reaction vessel was placed in a constant temperature bath set at 25 ° C. 10 g of acrylic acid was added as a polymerizable monomer, and graft polymerization was performed at a temperature of 25 ° C. for 5 hours. After completion of the polymerization, the sample was washed with distilled water and dried.

The weight of the sample was about 15.5 g, and the graft ratio was 55% from the increase in weight. The weight of the polymer component extracted into the washing solution was measured. As a result, the weight was about 0.5 g, and it was confirmed that a homopolymer was hardly generated. The graft polymer part (polyacrylic acid) of this sample was stained with a cationic dye, and as a result of optical microscopic observation, fine sea-island structures were observed in the stained part and non-stained part, and the sample had an uneven surface structure. As can be seen, the size of the domain of the stained portion was as fine as about 5 μm or less. As a result of observing the surface of the sample treated with osnimic acid for the purpose of observing the surface structure in more detail with an electron microscope, it was found that a sea-island structure having fine domains of about 1 μm was formed.

Example 5 10 g of a cellophane film piece (thickness: about 25 μm, size: 1 cm × 1 cm) obtained by graft polymerization of acrylic acid prepared in Example 3 as a substrate sample
Was placed in a reaction vessel equipped with a stirrer, and 35 ml of an organic solvent, toluene, was added thereto. Replace the inside of the reaction vessel with nitrogen,
Subsequent steps were performed under nitrogen. 0.045 g of ceric ammonium nitrate as a polymerization initiator and 0.2 ml of a 2N aqueous solution of nitric acid were used as surfactants and Sorgen 50 as a surfactant.
(Sorbitan monostearate: manufactured by Daiichi Kogyo Seiyaku) 0.
The solution was mixed with 5 ml of a toluene solution in which 02 g was dissolved under nitrogen, and stirred to obtain a suspension solution (droplet diameter of the initiator solution: about 8 μm).
m) was prepared, added to a reaction vessel, stirred, and reacted with a cellophane film piece by stirring for 2 minutes. Thereafter, the reaction vessel was placed in a constant temperature bath set at 25 ° C.
10 g of methyl acrylate is added as a polymerizable monomer,
Graft polymerization was performed for 5 hours. After completion of the polymerization, the sample was washed with distilled water and dried.

The weight of the sample was about 13.5 g, and the graft ratio was 35% based on the weight increase. The weight of the polymer component extracted into the washing solution was measured. As a result, the weight was about 0.1 g, and it was confirmed that almost no homopolymer was generated. This shows that a graft polymer of poly (methyl acrylate) was formed together with poly (acrylic acid) on the cellulose film. In addition, observation of the surface structure similar to that in Example 3 confirmed that the surface structure had an uneven surface structure.

Comparative Example 1 Examples 1 to 5 were used as substrate samples.
10 g of the same cellophane film piece (about 25 μm in thickness, 1 cm × 1 cm) was placed in a reaction vessel equipped with a stirrer, and 35 ml of water was added thereto. The inside of the reaction vessel was replaced with nitrogen, and the subsequent steps were performed under nitrogen. 0.135 g of ceric ammonium nitrate as a polymerization initiator, 2N-
A nitric acid aqueous solution (0.6 ml) and water (5 ml) were mixed under nitrogen, added to the reaction vessel, stirred, and reacted with a cellophane film piece for 2 minutes. Then the reaction vessel is 2
It was installed in a constant temperature bath set at 5 ° C. Graft polymerization was performed by adding 10 g of styrene, a water-insoluble monomer as a polymerizable monomer, but the graft polymerization did not proceed because styrene did not dissolve in water, and a graft polymer could not be formed on the substrate. Was.

(Comparative Example 2) A cellophane film piece (thickness: about 25 μm, size 1c) similar to that of the example was used as a substrate sample.
10 g of m × 1 cm) was placed in a reaction vessel equipped with a stirrer, and 40 ml of toluene was added thereto. The inside of the reaction vessel was replaced with nitrogen, and the subsequent steps were performed under nitrogen. 0.135 g of ceric ammonium nitrate as a polymerization initiator, 2N-
A nitric acid aqueous solution (0.6 ml) was mixed under nitrogen, added to the reaction vessel, stirred, and reacted with a cellophane film piece by stirring for 2 minutes, but the aqueous solution containing the initiator was added to a part of the cellophane film piece. Only adhesion and reaction occurred. As it was, the reaction vessel was placed in a constant temperature bath set at 25 ° C. 10 g of styrene as a water-insoluble monomer was added as a polymerizable monomer, and graft polymerization was performed for 5 hours. After completion of the polymerization, the sample was washed with distilled water and dried.

The weight of the sample was about 10.3 g, and from the increase in weight, the graft ratio was about 3%. The solution contained a large amount of unreacted polymerizable monomers. When this sample was observed in detail, it was found that only a small portion of the cellophane film was formed, and the graft polymer was not formed on most of the cellophane film.

Comparative Example 3 A cellophane film piece (thickness: about 25 μm, size: 1 c) similar to that of the example was used as a substrate sample.
10 g of m × 1 cm) was placed in a reaction vessel equipped with a stirrer, and 35 ml of water was added thereto. The inside of the reaction vessel was replaced with nitrogen, and the subsequent steps were performed under nitrogen. As a polymerization initiator, 0.045 g of ceric ammonium nitrate, 0.2 ml of a 2N aqueous solution of nitric acid, and 5 ml of water were mixed under nitrogen, and the mixture was added to a reaction vessel, stirred, and mixed with a piece of cellophane film.
The reaction was allowed to stir for minutes. Thereafter, the reaction vessel was placed in a constant temperature bath set at 25 ° C. 10 g of acrylic acid was added as a polymerizable monomer, and graft polymerization was performed for 5 hours.
After completion of the polymerization, the sample was washed with distilled water and dried.

The weight of the sample was about 15.0 g, and the graft ratio was 50% based on the weight increase. Also, as a result of measuring the weight of the polymer component extracted into the washing solution, about 3
g, a large amount of homopolymer was formed, and the grafting efficiency was low. The graft polymer portion (polyacrylic acid) of this sample was observed with an optical microscope and an electron microscope in the same manner as in the example using a cationic dye. As a result, the graft polymer was uniformly formed on the surface. It was found that a higher-order structure such as was not obtained.

[0041]

According to the present invention, the degree of freedom in controlling the graft polymerization is high. In particular, the surface structure of the graft polymer on the surface of the substrate, for example, the domain consisting of a collection of graft polymer binding portions and the non-graft portion It is possible to freely control higher-order structures such as sea-island shapes. Further, according to the present invention, even a non-aqueous polymerizable monomer that cannot be polymerized by a conventional method in an aqueous solvent can be easily graft-polymerized. Furthermore, according to the present invention, the formation of a homopolymer during graft polymerization can be suppressed.

The graft polymerization method of the present invention can be widely applied to surface modification of various polymer materials and inorganic materials. For example, toners for electrophotography, ink additives, functional coloring materials, electronic materials, functional papers, medical materials, materials for immobilizing physiologically active materials such as enzymes, materials for immobilizing microorganisms, cell culture materials, environmental purification materials, aggregation It can be applied to the production of agents, adsorbents, water-absorbing materials, biodegradable materials and the like.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating the process of the graft polymerization method of the present invention.

FIG. 2 is a schematic view showing an example of a higher-order structure of a graft polymer formed on a substrate surface by the graft polymerization method of the present invention.

FIG. 3 is a schematic diagram illustrating a process of forming a plurality of types of graft polymers by the graft polymerization method of the present invention.

FIG. 4 is a schematic diagram showing an example of a higher-order structure of a plurality of types of graft polymers formed on a substrate surface by the graft polymerization method of the present invention.

Claims (14)

[Claims] An aqueous solution containing a graft polymerization initiator and droplets of the aqueous solution in a suspension or an emulsion comprising an organic solvent are reacted with the surface of a substrate to be subjected to graft polymerization. A graft polymerization method comprising forming a polymerization initiation point on a substrate surface, and then graft-polymerizing a polymerizable unsaturated compound on a portion of the substrate surface where the polymerization initiation point is formed. 2. The graft polymerization method according to claim 1, wherein a reaction between the droplet of the aqueous solution and the surface of the substrate is caused on the entire surface of the substrate to form a polymerization initiation point on the entire surface of the substrate. 3. A reaction between a droplet of the aqueous solution and the surface of the substrate is caused on a partial surface of the substrate to partially form a polymerization starting point, and only on the partial surface of the substrate where the polymerization starting point is formed. The graft polymerization method according to claim 1, wherein the graft polymerization is performed. 4. A first graft polymerization, wherein a droplet of the aqueous solution in a suspension or an emulsion comprising an aqueous solution containing a graft polymerization initiator and an organic solvent is mixed with a substrate to be subjected to graft polymerization. Reacting with the partial surface to partially form a polymerization starting point, and graft-polymerize the polymerizable unsaturated compound only on the partial surface of the substrate where the polymerization starting point is formed; further, as a second graft polymerization, A graft polymerization method, wherein a polymerizable unsaturated compound different from the polymerizable unsaturated compound is graft-polymerized on a partial surface of the substrate where the first graft polymerization is not formed. 5. The graft polymerization method according to claim 4, wherein the second graft polymerization is performed by the graft polymerization method according to claim 1. 6. The graft polymerization method according to claim 4, further comprising sequentially performing the second or more graft polymerizations by the graft polymerization method according to claim 1. 7. The graft polymerization method according to claim 1, wherein the concentration of the graft polymerization initiator is 0.1 to 80% by weight in the aqueous solution. 8. The proportion of the aqueous solution containing the graft polymerization initiator in the suspension or the emulsion is 0.01 to 10% by weight.
The graft polymerization method according to claim 1, wherein: 9. A substrate to be subjected to graft polymerization,
The graft polymerization method according to claim 1 or 4, wherein the mixing ratio with the aqueous solution containing the graft polymerization initiator is 1: 1 to 10,000: 1 by volume ratio. 10. The graft polymerization method according to claim 1, wherein the polymerizable unsaturated compound is selected from the group consisting of acrylic acid, acrylic acid ester, and styrene. 11. The graft polymerization method according to claim 1, wherein the organic solvent is a non-aqueous solvent. 12. The graft polymerization method according to claim 1, wherein the substrate on which the graft polymerization is performed is a polysaccharide compound. 13. The graft polymerization method according to claim 1, wherein the graft polymerization initiator is a water-soluble redox radical polymerization initiator. 14. The graft polymerization method according to claim 1, wherein a surfactant or surfactant is further contained in a suspension or emulsion comprising an aqueous solution containing a graft polymerization initiator and an organic solvent. .