JP7133165B2 - Method for producing modified particles for material modification - Google Patents

Description

The present invention relates to a method for producing modified particles for material modification.

Olefin polymers are industrially manufactured by various methods due to their high industrial utility value, and the annual production is said to exceed 100 million tons. Since olefin polymers are mainly composed of carbon and hydrogen, they are characterized by being stable and inexpensive materials. On the other hand, the structure having no functional group in the olefin polymer has poor affinity with polar materials, and also has properties such as colorability and adhesiveness that are difficult to modify.

As a method of modifying olefin polymers (method of introducing functional groups), a method of grafting maleic anhydride using a radical generator is known. , there is a limit to the amount of introduction.
As a solution to this problem, there is an example of a denaturation method using a solid-phase reaction (see, for example, Patent Document 1).

WO2015/166939

However, it seems that the current situation is that the problem such as the decrease in the molecular weight of the olefin polymer cannot be sufficiently solved. A decrease in molecular weight may lead to various negative factors such as a decrease in strength as a material.

On the other hand, depending on the application of the olefin polymer, there are cases in which only the surface of particles or moldings made of the olefin polymer may be modified. For example, there are adhesives, paints, base materials for bonding, base materials for coating, and slidability-improving particles used in automotive materials such as wipers and weather strips. The present inventors have found that if the surface or a specific site of the olefin polymer particles can be modified, the material modification effect can be enhanced when the particles are added to various materials while suppressing the decrease in the strength of the particles. I thought it would be possible.

Accordingly, an object of the present invention is to provide a method for producing modified particles for material modification by modifying olefin polymer particles efficiently mainly at the surface or at specific sites.

As a result of the research conducted by the present inventors in order to achieve the above objects, it has become possible to modify mainly the surface or a specific portion of the olefin polymer particles by the means shown below, and a new material has been developed. It has become possible to provide modifying olefin polymer particles. That is, the present invention is as follows.

[1] In one molecule, an atom (α) of an element selected from Group 15 elements and Group 16 elements and an atom (β) of a Group 17 element are added in an atomic number ratio of atom (α): atom (β) = A method for producing modified particles for material modification, comprising step 1 of irradiating radicals contained in a ratio of 1:1 to 4:1 with light, by modifying olefin polymer particles having an average particle size of 1 to 200 μm.
[2] The material according to [1], wherein the step 1 is a step of modifying the olefin polymer particles by irradiating the radicals with light in an environment where the olefin polymer particles and the radicals coexist. A method for producing modified particles for modification.
[3] The method for producing modified particles for material modification according to [2], wherein the step 1 is a step of irradiating the olefin polymer particles and the radicals with light.
[4] The method for producing modified particles for material modification according to any one of [1] to [3], wherein the olefin polymer particles have an average particle size of 1 to 60 μm.
[5] The method for producing modified particles for material modification according to any one of [1] to [4], wherein the radical is a chlorine dioxide radical.
[6] The method for producing a modified material according to any one of [1] to [5], wherein the material modifying modified particles are paint modifying modified particles.

According to the production method of the present invention, it is expected that it will be possible to modify mainly the surface or specific sites of the olefin polymer particles. Therefore, it is thought that it is possible to suppress the decrease in the molecular weight of the olefin polymer, which is the base material, and to provide olefin polymer particles that are excellent in material modification properties while making the best use of the inherent properties of the particles.

FIG. 1 is a schematic diagram of modifying olefin polymer particles in Examples. FIG. 2 is a photograph of hydrophilicity evaluation in Examples and Reference Examples.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the invention is not limited by the following description.
<<Method for producing modified particles for material modification>>
The method for producing modified particles for material modification according to the present invention (hereinafter also referred to as "this method") comprises:
Atoms (α) of elements selected from Group 15 and Group 16 elements and atoms (β) of Group 17 elements are contained in one molecule in an atomic number ratio of atoms (α): atoms (β) = 1:1. Including step 1 of irradiating light to the radicals contained in a ratio of ~4: 1,
A method for producing modified particles for material modification, which is obtained by modifying olefin polymer particles having an average particle size of 1 to 200 μm.

The step 1 is preferably a step of modifying the olefin polymer particles by irradiating the radicals with light in an environment where the olefin polymer particles and the radicals coexist.

In step 1, the olefin polymer particles and the radicals are preferably irradiated with light. The phrase "the olefin polymer particles and the radicals are irradiated with light" does not mean that the olefin polymer particles and the radicals are irradiated with light independently, for example, from one light source. means that the olefin polymer particles and the radicals are irradiated with the light of . Moreover, it is preferable that the olefin polymer particles and the radicals are irradiated with light at the same time.

As the production method of the present invention, there is also an embodiment in which the radical-containing system is irradiated with light, and then the system is brought into contact with the olefin polymer particles to modify the olefin polymer particles.

Hereinafter, the modified particles for material modification obtained by this method may be simply referred to as "modified particles of the present invention" or "modifier particles of the present invention".
According to this method, mainly the surface or specific sites of the olefin polymer particles can be efficiently modified. According to this method, it is possible to modify mainly the surface or a specific site of the olefin polymer particles, so it can be said that the sites requiring modification can be efficiently modified. It is possible to enhance the modification effect while suppressing the decrease in the molecular weight of the olefin polymer.

According to this method, the olefin polymer particles can be efficiently modified (e.g., oxidized treatment) by a very simple method of only irradiating the radicals with light, and even under extremely mild conditions such as normal temperature and normal pressure. )can do. Furthermore, according to the present method, the olefin polymer particles are efficiently modified (eg, oxidized reaction) without using radical generators such as peroxides and azo compounds, which may be unstable at handling temperatures. be able to.

<Step 1>
In step 1, an atom (α) of an element selected from group 15 elements and group 16 elements and an atom (β) of a group 17 element are added to one molecule in an atomic number ratio of atom (α): atom (β )=1:1 to 4:1 in the step of irradiating the radicals with light.

In step 1, at least the radicals are irradiated with light, and the olefin polymer particles may or may not be irradiated with light.
In the present invention, irradiating the olefin polymer particles with light may not directly involve the modification reaction of the olefin polymer particles. However, considering the general lifetime of radicals and the case of modifying a specific site of the olefin polymer particles, it is a preferable method to substantially irradiate the olefin polymer particles with light.

The step 1 may be a liquid phase method in which the particles are immersed in or brought into contact with an aqueous phase and/or organic phase containing the radicals, and the aqueous phase and/or organic phase containing the radicals and the particles are A gas phase method without contact may be used, or a gas phase method may be performed in a gas phase containing the radicals and the particles. For example, in applications where the influence of residual water or solvent is strictly limited, reaction in the gas phase is preferred.

The radical contains atoms (α) of elements selected from group 15 and group 16 elements and atoms (β) of group 17 elements in a specific composition ratio in one molecule.
The radical may contain two or more Group 15 element atoms, may contain two or more Group 16 element atoms, and may contain one or more Group 15 element and Group 16 element atoms. It may contain two or more Group 17 element atoms. However, in these cases, the atomic number ratio is the ratio between the total number of atoms of group 15 and group 16 elements and the total number of atoms of group 17 elements.

Atom (α) is preferably nitrogen, oxygen or sulfur, with oxygen being particularly preferred.
The atom (β) is preferably chlorine, bromine or iodine, more preferably chlorine or bromine. Among these, chlorine is more preferable because chlorine-containing radicals are readily available or easily generated. When radicals containing chlorine are used, light containing ultraviolet rays is preferable as irradiation light, and when radicals containing bromine or iodine are used, it is considered that light with a longer wavelength than ultraviolet rays can also be used. Therefore, bromine and iodine are preferable depending on the degree of freedom of light selection and the possibility of photodegradation of the raw material polymer.

The atomic number ratio (atom (α):atom (β)) in the radical is preferably 1:1 to 2:1, more preferably 2:1.
A chlorine dioxide radical is preferable as the radical. For example, it is considered that chlorine radicals (Cl.) and oxygen molecules (O ₂ ) are generated by irradiating chlorine dioxide radicals with light.

In the production method of the present invention, for example, known olefin polymer particles can be used without limitation as raw materials. Specific examples of the olefin polymer constituting the olefin polymer particles include ethylene, propylene, butene, 4-methyl-1-pentene, hexene, octene, and the like, which are obtained singly or in combination of two or more olefins. A copolymer can be exemplified.

Preferred examples of the olefin polymer include ethylene-based polymers, propylene-based polymers, butene-based polymers, and 4-methyl-1-pentene-based polymers. Among them, ethylene-based polymers and propylene is a preferred example.

As the olefin polymer particles, ethylene-based polymer particles are particularly preferable, and among them, ultra-high-molecular-weight ethylene-based polymer particles are preferable because they exhibit excellent effects such as improvement of slidability. The ultra-high molecular weight ethylene-based polymer preferably has an intrinsic viscosity [η] measured in decalin at 135°C of 4 to 35 dl/g, more preferably 5 to 25 dl/g, and still more preferably 5 to 20 dl/g. , particularly preferably in the range from 5 to 18 dl/g.

The average particle size of the olefin polymer particles used in the present invention is 1-200 μm, preferably 1-60 μm. Smaller particle sizes tend to be preferable as modifiers for paints and the like, which will be described later. Olefin polymers that serve as such base materials are commercially available from Mitsui Chemicals under trade names such as HI-ZEX (registered trademark), HI-ZEX MILLION (registered trademark), and MIPELON (registered trademark) as ethylene-based polymers. ing. In particular, Miperon is a product characterized by its small particle size (average particle size of 60 μm or less).

The average particle size of the olefin polymer particles in the present invention is determined by a conventional method.
Specifically, for the average particle size, in the particle size range of 60 μm or more, the particle size distribution is determined using multistage sieves with different opening sizes, and the median value (d50) is taken. For example, the method is as follows. 5 g of olefin polymer particles mixed with a very small amount of carbon black as an antistatic agent are classified using 7 kinds of sieves with an opening diameter of 45 μm to 850 μm to determine the particle size distribution, and the median value (d50) is taken as the average particle size. and

On the other hand, when the average particle size is in the particle size range of 60 μm or less, the Coulter counter method is preferably used. Specifically, it is determined by a conventional method using a multisizer model 3 manufactured by Beckman. (It goes without saying that the measurement results of another model may be used as long as it is confirmed that the results are similar to those of the above model.)
There are many reports on means for obtaining such olefin polymer particles, and these can be employed without restriction. For example, methods for providing ethylene polymer particles with a high molecular weight are disclosed in WO2008/013144, WO2016/136540, and the like.

In this method, for example, aromatic vinyl compounds such as styrene, (meth)acrylic acid and its esters, and the like may be used as the olefin in the raw material of the olefin polymer particles.

Olefin polymers are usually produced by a low-pressure polymerization method using a catalyst containing a transition metal, but a high-pressure radical method is also an effective method for obtaining such copolymers. be.

The olefin polymer particles may contain other polymers, antioxidants, heat stabilizers, light stabilizers, weather stabilizers and other stabilizers, antistatic agents, hydrophilic agents, repellents, etc., as long as the objects of the present invention are not compromised. Additives such as liquid agents, nucleating agents, slip agents, anti-blocking agents, anti-fogging agents, lubricants, dyes, pigments, natural oils, synthetic oils, antibacterial agents and flame retardants may be included.

The light (wavelength) used for the light irradiation may be appropriately selected according to the radicals to be used. Specifically, it is possible to select a wide range from the infrared region to the ultraviolet region, and it is, for example, 200 nm or more and, for example, 800 nm or less. Although the light irradiation time is not particularly limited, it is, for example, 1 minute or more and, for example, 1000 hours or less.

The light source for the light irradiation is not particularly limited, but natural light such as sunlight can be used from the viewpoint of convenience. Further, for example, instead of or in addition to the natural light, a light source such as a xenon lamp, a halogen lamp, a fluorescent lamp, or a mercury lamp may be appropriately used. Furthermore, if necessary, a filter that cuts wavelengths other than the required wavelength may be used as appropriate.

The temperature, pressure, and atmosphere in performing Step 1 are not particularly limited, but the reaction temperature is, for example, 0° C. or higher and, for example, 100° C. or lower, and the pressure is, for example, 0.1 MPa or higher and 100 MPa or lower. The atmosphere includes, for example, an air atmosphere and an inert gas atmosphere.

For example, as shown in the examples below, this method is carried out in the atmosphere at normal temperature (eg, 5 to 35° C.) and normal pressure (atmospheric pressure) without any heating, pressurization, pressure reduction, etc. is also possible.
The light irradiation is performed, for example, on the radicals present in an aqueous phase, an organic phase and/or a gas phase. When emphasis is placed on reducing the load on the environment and the effects on the human body, it is preferable to perform the treatment on radicals present in the water phase or the gas phase. Step 1, in one embodiment, may be in an environment in which two or more phases of aqueous, organic and gaseous phases are present. Further, for example, when the radicals exist in the liquid phase, the olefin polymer particles to be modified may also exist in the liquid phase, but may exist in other phases such as the gas phase. may

In one embodiment, the concentration of radicals containing atoms (α) and atoms (β) in the aqueous phase and/or organic phase is not particularly limited, but is, for example, 0.0001 mol/L or more, such as 1 mol/L. It is below.

In step 1, in one embodiment, the liquid phase (aqueous phase and/or organic phase) containing the olefin polymer particles and the radicals may be irradiated with light. The concentration of the raw material (substrate) olefin polymer particles in the liquid phase is not particularly limited, but may be, for example, 1 g/L or more and 10 g/L or less.

The aqueous phase is not particularly limited as long as it contains water.
The organic phase is not particularly limited as long as it contains an organic solvent.
Although the organic solvent is not particularly limited, examples thereof include hydrocarbon solvents and halogenated solvents.

One kind of the organic solvent may be used, or two or more kinds thereof may be used.
Examples of the hydrocarbon solvent include, but are not limited to, n-hexane, cyclohexane, benzene, toluene, o-xylene, m-xylene, and p-xylene.

Examples of the halogenated solvent include, but are not limited to, methylene chloride, chloroform, carbon tetrachloride, carbon tetrabromide, and fluorous solvents.
The fluorous solvent refers to a solvent in which all or most of the hydrogen atoms of a hydrocarbon are substituted with fluorine atoms. The fluorous solvent may be, for example, a solvent in which 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more of the hydrogen atoms in the hydrocarbon are substituted with fluorine atoms.

Examples of the fluorous solvent include CF ₃ —(CF ₂ ) _n —CF ₃ (n is 4 to 7), N—((CF ₂ ) _n CF ₃ ) ₃ (n is 1 or 4), hexafluorobenzene , 1-(trifluoromethyl)undecafluorocyclohexane, 1-(trifluoromethyl)pentafluorobenzene, octadecafluorodecahydronaphthalene, among which CF ₃ (CF ₂ ) ₄ CF ₃ is preferred. .

A fluorous solvent has the advantage of suppressing or preventing side reactions, for example, because the solvent itself has low reactivity. Examples of the side reaction include oxidation reaction of the solvent, hydrogen abstraction reaction and chlorination reaction of the solvent by radicals, and reaction between radicals derived from the raw material (substrate) and the solvent.

The aqueous phase and/or the organic phase may contain components other than the radicals. Other components may be dispersed or precipitated in the aqueous phase and/or organic phase.

Examples of the other component include, but are not particularly limited to, the radical generating source, Bronsted acid, Lewis acid, and oxygen (O ₂ ).
Each of these may be used alone or in combination of two or more.

Said other ingredients may be dissolved in the aqueous phase and/or the organic phase, but they do not have to be dissolved.
In addition, one substance may serve as both the Lewis acid and the Bronsted acid. The term "Lewis acid" refers to a substance that acts as a Lewis acid against the above radical generation source.

The source of the radical is not particularly limited, but when the radical is a chlorine dioxide radical, for example, chlorous acid (HClO ₂ ) or a salt thereof may be used. Salts of chlorous acid are not particularly limited, and examples thereof include metal salts. Examples of the metal salt include alkali metal salts, alkaline earth metal salts and rare earth salts.

More specifically, the chlorine dioxide radical generation source is, for example, sodium chlorite (NaClO ₂ ), lithium chlorite (LiClO ₂ ), potassium chlorite (KClO ₂ ), magnesium chlorite (Mg (ClO ₂ ) ₂ ) and calcium chlorite (Ca(ClO ₂ ) ₂ ). Among these, sodium chlorite is preferable from the viewpoint of cost, ease of handling, and the like.

Although the concentration of the radical generation source in the aqueous phase and/or organic phase is not particularly limited, it is, for example, 0.0001 mol/L or more and 1 mol/L or less.
The Lewis acid is not particularly limited, and may be, for example, an organic substance or an inorganic substance.

Examples of the organic substances include ammonium ions and organic acids (eg, carboxylic acids).
The inorganic substance may contain one or both of metal ions and non-metal ions. The metal ions may contain one or both of typical metal ions and transition metal ions.

The inorganic substance includes, for example, alkaline earth metal ions (e.g. Ca ²⁺ etc.), rare earth ions, Mg ²⁺ , Sc ³⁺ , Li ⁺ , Fe ²⁺ , Fe ³⁺ , Al ³⁺ , silicate ions and It may be at least one selected from the group consisting of borate ions.

The alkaline earth metal ions include, for example, calcium, strontium, barium or radium ions, more specifically Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Ra ²⁺ .

The "rare earth" is a general term for a total of 17 elements, including two elements of scandium and yttrium and 15 elements (lanthanides) from lanthanum to lutetium. Examples of rare earth ions include trivalent cations.

Further, when the Lewis acid is an ion, the Lewis acid may be a substance having a counter ion of the ion, and the counter ion is, for example, trifluoromethanesulfonate ion (CF ₃ SO ₃ ⁻ ). , trifluoroacetate ion (CF ₃ COO ⁻ ), acetate ion, fluoride ion, chloride ion, bromide ion, iodide ion, sulfate ion, hydrogen sulfate ion, sulfite ion, nitrate ion, nitrite ion, phosphate ion , phosphite ion.

Also, the Lewis acid may be at least one selected from the group consisting of AlCl ₃ , AlMeCl ₂ , AlMe ₂ Cl, BF ₃ , BPh ₃ , BMe ₃ , TiCl ₄ , SiF ₄ and SiCl ₄ . In addition, among these, "Ph" represents a phenyl group, and "Me" represents a methyl group.

The Lewis acidity of the Lewis acid is, for example, 0.4 eV or more, but is not limited thereto. Although the upper limit of the Lewis acidity is not particularly limited, it is, for example, 20 eV or less. The Lewis acidity is described, for example, in Ohkubo, K.; Fukuzumi, S. Chem. Eur. J., 2000, 6, 4532, J. AM. CHEM. SOC. Org. Chem. 2003, 68, 4720-4726.

The Bronsted acid is not particularly limited, and examples thereof include inorganic acids and organic acids. Specific examples include trifluoromethanesulfonic acid, trifluoroacetic acid, acetic acid, hydrofluoric acid, hydrochloric acid, bromo Hydrochloric acid, hydroiodic acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, phosphoric acid, phosphorous acid.

The acid dissociation constant pK _a of the Bronsted acid is, for example, 10 or less. Although the lower limit of the pK _a is not particularly limited, it is -10 or more, for example.
The concentration of at least one of the Lewis acid and Bronsted acid in the aqueous phase and/or the organic phase is not particularly limited and can be set as appropriate. is.

For example, oxygen (O ₂ ) can be dissolved in the aqueous and/or organic phase by blowing air or oxygen gas through the aqueous and/or organic phase. At this point, for example, the aqueous phase and/or the organic phase may be saturated with oxygen (O ₂ ). When the aqueous phase and/or the organic phase contain oxygen (O ₂ ), for example, the modification (oxidation reaction) of the olefin polymer particles can be promoted.

<Radical generation step>
The method may include a step of generating the radicals (radical generation step), and specifically includes a step of generating the radicals from the radical generation source.

Although the radical generation step is not particularly limited, for example, the water phase may contain the radical generation source, and the radicals may be generated from the radical generation source. Specifically, the radical-generating source (eg, chlorous acid or a salt thereof) is dissolved in water and allowed to stand, so that the radicals are spontaneously generated from the radical-generating source. At this time, for example, the presence of at least one of the Lewis acid and the Bronsted acid in the water can promote the generation of the radicals. Further, for example, the radicals can be generated by irradiating an aqueous phase in which the radical generating source is dissolved in water with light. This light irradiation may be the light irradiation in step 1, that is, the light irradiation may be performed on the radicals while generating the radicals.

For example, a mechanism (mechanism) for generating chlorine dioxide radicals from chlorite ions is presumed as shown in Scheme 1 below. However, Scheme 1 below is an example of a presumed mechanism and does not limit the present invention in any way.

The first (upper) reaction formula in Scheme 1 below shows the disproportionation reaction of chlorite ion (ClO ₂ ⁻ ), and at least one of Lewis acid and Bronsted acid is present in this reaction system. , the equilibrium tends to shift to the right.

The second (middle) reaction formula in Scheme 1 below shows a dimerization reaction, in which hypochlorite ions (ClO ⁻ ) generated in the disproportionation reaction react with chlorite ions to form dioxide. Chlorine (Cl ₂ O ₂ ) is produced. This reaction is thought to proceed more easily as the amount of protons H ⁺ in the water increases, that is, as the water becomes more acidic.

The third (lower) reaction scheme in Scheme 1 below represents radical generation. In this reaction, dichlorine dioxide produced in the dimerization reaction reacts with chlorite ions to produce chlorine dioxide radicals.

A two-phase reaction system including an organic phase and an aqueous phase will be described below as an example of the reaction system used in the radical generation step, but the present method is not limited to this system. First, prior to performing step 1, the two phases of the aqueous phase and the organic phase are brought into contact. At this time, the aqueous phase and the organic phase may be mixed to form an emulsion or the like, and the reaction may be carried out while stirring or the like. Alternatively, the two layers of the aqueous layer (the aqueous phase) and the organic layer (the organic phase) may simply be separated and in contact with each other only at the interface.

Here, an embodiment of two-layer separation consisting of an aqueous layer containing chlorite ions (ClO ₂ ⁻ ) and acid and an organic layer containing olefin polymer particles is described, but the method is limited to this embodiment. Do not mean. In the reaction vessel, the reaction system is divided into two layers, an aqueous layer (the aqueous phase) and an organic layer (the organic phase), which are in contact with each other only at the interface. One layer is the aqueous layer (said aqueous phase) and the other layer is the organic layer (said organic phase). Chlorite ions (ClO ₂ ⁻ ) in the aqueous layer (aqueous phase) react with acid to generate chlorine dioxide radicals (ClO ₂ .). Chlorine dioxide radicals (ClO ₂ ·) are sparingly soluble in water and dissolve in the organic layer.

Next, by irradiating at least the organic layer containing chlorine dioxide radicals (ClO ₂ ·) with light, the chlorine dioxide radicals (ClO ₂ ·) in the organic layer are decomposed into chlorine radicals (Cl ·) and oxygen molecules (O ₂ ) occurs. This oxidizes the substrate (olefin polymer particles) in the organic layer (organic phase).

However, the above process is an example of a presumed mechanism and does not limit the present invention.
In step 1, when a one-phase reaction system containing only an organic phase is used, for example, the chlorine dioxide radicals are generated in an aqueous phase containing a chlorine dioxide radical generation source, and the generated chlorine dioxide radicals are After extraction into the organic phase, the aqueous phase may be removed, and the organic phase containing the chlorine dioxide radical may be subjected to the step 1 as the one-phase reaction system. In this embodiment, olefin polymer particles (substrate) may be added into the organic phase prior to the extraction of the chlorine dioxide radicals, into the organic phase simultaneously with or after the extraction of the chlorine dioxide radicals. may be added. Thereafter, the aqueous phase and the organic phase are separated (the organic phase alone), and, for example, in a state in which the organic phase contains the olefin polymer particles and the chlorine dioxide radicals, light irradiation is performed as described above. do

For the sake of convenience, the presumed mechanism (mechanism) by which ethanol is produced is considered as follows, taking the oxidation reaction of ethane as an example. First, chlorine dioxide radicals are decomposed by light irradiation to generate chlorine radicals (Cl.) and oxygen molecules (O ₂ ). The chlorine radical acts as a hydrogen abstracting agent for ethane to generate an ethyl radical _{( CH3CH2} .). The oxygen molecules then oxidize the ethyl radicals to produce ethanol. However, this is an example of a presumed mechanism and does not limit the present invention.

In the present invention, the raw material (substrate) in the above mechanism is olefin polymer particles, and the olefin polymer, like ethane, has a structure having a carbon-hydrogen single bond. It can be assumed that the reaction proceeds. Moreover, since the reaction used in the present invention proceeds via light, the reaction is expected to occur mainly at the sites exposed to light, that is, mainly at the surfaces of the olefin polymer particles. If this property is used, even if the olefin polymer molecule is cut or crosslinked by the modification reaction, it will remain near the particle surface, and the impact on the performance inside the particle, such as the strength of the olefin polymer particle, will be minimal. This is advantageous in terms of maintaining particle strength, etc.

In addition, if only one side of the particle is irradiated with light, it is possible to modify only half of the surface of the particle, or if a photomask is used, it is possible to modify only a specific particle. It is expected that it can also be controlled to

By using the production method of the present invention, the proportion of modified particles that can be obtained (controlled) is 100% (number basis or area basis) of all particles in a certain range, and the preferred lower limit is 1%. The order of 5%, 10%, 20%, 30% and 50% is preferred, and the preferred upper limit is 100%, more preferably 90%. The range of denatured particles and the denatured area in one particle can be determined, for example, by contacting the particles with a polar ink and then observing any number of points with an electron microscope. It can be evaluated by measuring the number of particles and the area of the particles to which the ink adheres.

It is considered that the modification progresses with radicals of the group 17 element generated when the radicals are exposed to light as a starting point. As a matter of course, it is considered that modification occurs at the portion where the radical comes into contact with the raw material olefin polymer particles.

<Recovery process>
Further, after step 1, the step of recovering the modified particles is performed as necessary. The recovery step is performed by a conventional method. That is, the modified particles are separated from other components, dispersion medium, etc. by filtration or centrifugation, washed several times with water or an organic solvent, and then dried to obtain the desired product. It is the preferred method to obtain

《Modified Particle》
In some cases, the modification introduces a functional group containing the atom (α) contained in the radical into the olefin polymer particles. sometimes At this time, the atoms (β) contained in the radicals may also be introduced into the olefin polymer particles. According to this method, it is thought that the atom (β) may also be introduced into the olefin polymer particles in this way. Therefore, the effect of the atom (β) may also be expected in the modified particles of the present invention. be.

As the functional group containing the atom (α), when the radical contains oxygen, for example, a hydroxy group, a carboxyl group, an aldehyde group, a carbonyl group, an ether bond, an ester bond, -C(=O)OOH, and - OO- is included.

If this method is used, it may be possible to simultaneously introduce not only a hydroxyl group, a carboxyl group, an aldehyde group, a carbonyl group, etc. but also a group 17 element, typically chlorine, into the substrate olefin polymer particles. Of course, by changing the type of radical used, it is possible to introduce not only chlorine but also bromine and iodine. It has been reported that the introduction of group 17 elements is suppressed when modifying low-molecular-weight hydrocarbon compounds such as alkanes using the radicals. In some cases, it can be introduced into the olefin polymer particles together with the element. This is thought to be due to the fact that the existence density of carbon-hydrogen bonds in olefin polymers tends to be higher than in the case of modifying low-molecular substances such as methane and ethane, and that radicals do not interact with polymers. The present inventors believe that one of the reasons for this is the possibility that having a battery will stably extend its life. However, this speculation does not limit the present invention.

When the atoms (β) are introduced into the olefin polymer particles, the total amount [Cα] of the atoms (α) introduced into the olefin polymer particles and the total amount [Cβ] of the atoms (β) The lower limit of the ratio ([Cα]/[Cβ]) is preferably greater than zero, more preferably 0.01, still more preferably 0.1, particularly preferably 0.5, and the upper limit is preferably is 5000, more preferably 100, even more preferably 20. The above [Cα] and [Cβ] values are values specified by the XPS method. The measurement is carried out by a conventional method using the product name AXIS-Nova (manufactured by KRATOS).

The surface refers to a region whose depth from the surface of the modified particle is 1/10 or less, more preferably 1/20 or less of the diameter. The depth of this denatured portion can be confirmed by, for example, the XPS method.

《Application》
The modified particles for material modification obtained by this method are expected to be preferably applied to various uses. The modified particles of the present invention are considered to be suitable as modifiers that mainly impart slidability and durability to paints such as urethane paints, acrylic paints and styrene paints. In addition, the modified particles of the present invention can be expected to exhibit suitable dispersibility even when used in water-based paints, which are considered to have a low environmental load, and can also be expected to improve the interfacial strength with other components. In addition, the molecular weight of the olefin polymer constituting the modified particles of the present invention is small, and improvement in terms of durability can be expected.

Other anticipated uses for the modified particles of the present invention include modifiers for wiper blade rubber, weatherstrip sponges, rubber products such as glass run channels, and brake pad materials. These materials often contain various components such as pigments and fillers in addition to the main rubber component. The modified particles of the present invention are expected to have excellent affinity with these components, as well as excellent dispersibility and interfacial strength.

In addition, since the modified particles obtained by the production method of the present invention are highly likely to have improved interaction between particles themselves, it is expected to be suitable as a raw material for filters such as sintered filters.

Examples of the present invention will be described below. However, the present invention is not limited to the following examples.
[Oxidation of polyethylene powder]
0.4 g of sodium chlorite (manufactured by Sigma-Aldrich) and 25 mL of ultrapure water were added to a 110 mL screw tube containing a stirrer bar to dissolve sodium chlorite in the ultrapure water. Then, 25 mL of perfluorohexane (manufactured by Oakwood Chemical) and 60 μL of 35-37% hydrochloric acid aqueous solution (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) were added. It was previously confirmed by the ESR method that chlorine dioxide radicals were generated under these conditions. 1 g of polyethylene powder (Mipelon (registered trademark), manufactured by Mitsui Chemicals, Inc.) was further added to this mixed solution, and the whole was stirred with a stirrer. The miperone used in this example had an average particle size of 25 μm as measured by the Coulter counter method, a temperature of 135° C., and an intrinsic viscosity [η] of 13 dl/g as measured in decalin. After stirring, as shown in FIG. 1, the liquid in the screw tube was separated into two layers, an aqueous layer and an organic layer. The solution containing the polyethylene powder was irradiated with light of a wavelength of 365 nm at 20 mW/cm ² for 5 minutes at Hololite Kaku manufactured by Pi Photonics Co., Ltd. from the side of the screw tube as shown in FIG. irradiated. Thereafter, the liquid containing the polyethylene powder was filtered through a funnel equipped with filter paper, and the polyethylene powder was washed with ultrapure water until the yellow colored by the mixed liquid and perfluorohexane separated from water disappeared visually. Then, the polyethylene powder was dried under reduced pressure to obtain the polyethylene oxide powder of Example 1.

[Electron beam irradiation of polyethylene powder]
By irradiating 100 g of polyethylene powder (Mipelon (registered trademark), manufactured by Mitsui Chemicals, Inc.) with an electron beam at an irradiation dose of 200 kGy, an electron beam-irradiated polyethylene powder (electron beam irradiated product) was obtained.

[Hydrophilic evaluation of polyethylene powder]
Untreated polyethylene powder (Reference Example 1), electron beam-irradiated polyethylene powder (Reference Example 2), and oxidized polyethylene powder (Example 1) were each placed in a screw tube containing water, and immediately after stirring. The state of dispersion of the polyethylene powder (see FIG. 2) was visually confirmed. Table 1 shows the results. In addition, the polyethylene powder used was the above-mentioned MIPELON.

Claims (5)

Atoms (α) of elements selected from Group 15 and Group 16 elements and atoms (β) of Group 17 elements are contained in one molecule in an atomic number ratio of atoms (α): atoms (β) = 1:1. comprising a step 1 of irradiating light to the radicals contained in a ratio of ~4:1;
the element selected from the group 15 elements and group 16 elements is oxygen,
The Group 17 element is chlorine, bromine or iodine,
The step 1 is
In an environment where olefin polymer particles having an average particle size of 1 to 200 μm and the radicals coexist,
a step of modifying the olefin polymer particles by irradiating the radicals with light;
A method for producing modified particles for material modification. 2. The method for producing modified particles for material modification according to claim 1 , wherein said step 1 is a step of irradiating said olefin polymer particles and said radicals with light. 3. The method for producing modified particles for material modification according to claim 1, wherein the olefin polymer particles have an average particle size of 1 to 60 μm. 4. The method for producing modified particles for material modification according to any one of claims 1 to 3 , wherein the radicals are chlorine dioxide radicals. The method for producing modified particles for material modification according to any one of claims 1 to 4 , wherein the modified particles for material modification are paint modification modified particles.

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