JP2013256621A - Boron nitride-coated polymeric resin and method for production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To coat the whole surface of a polymeric resin having a curved surface with boron nitride.SOLUTION: The whole surface of a polymeric resin having a curved surface can be coated by heating the mixture including an ionic liquid, ammonia borane and the above polymeric resin under certain conditions.

Description

  The present invention relates to a polymer resin in which boron nitride is entirely coated, and a method for producing the same. The manufacturing method uses an ionic liquid.

  Boron nitride is a chemically stable substance and excellent in thermal conductivity and electrical insulation, and thus is used in a wide range of fields as a heat dissipation material. Boron nitride can be produced by various methods. For example, a boron nitride film can be manufactured by metal organic chemical vapor deposition (MOCVD) using trimethyl borate as a raw material (Non-patent Document 1). Moreover, a boron nitride film can also be manufactured by heat-processing the to-be-coated base material which apply | coated the boric acid ethanolethanol condensate (patent document 1).

  Boron nitride can also be used as a cosmetic material. For example, by blending composite particles in which the surface of the mother particle is directly coated with boron nitride powder into cosmetics, cosmetics excellent in touch, adhesion, elongation, etc. can be produced (Patent Document 2).

  An ionic liquid is generally a salt that exists as a liquid at room temperature, and is excellent in non-volatility and high heat resistance. Therefore, it is not limited to use as a reaction solvent, but can be used in various applications such as lithium ion batteries and lubricating oils. Application is expected. An ionic liquid is also used for embedding particles in a carrier (Patent Document 3). It is also known that the ionic liquid has an effect of promoting the dehydrogenation reaction of ammonia borane (Non-patent Document 2).

Japanese Patent Laid-Open No. 9-87071 JP-A-8-113514 Special table 2010-529231 gazette

Ishikawa Prefectural Industrial Experiment Station 2007 Research Report Vol. 57 "Boron nitride (BN) film fabrication technology and its characteristics" Inorg. Chem. , 48 (20), 9883-9 (2009)

  It is conceivable to improve the heat dissipation of the polymer resin by utilizing the excellent thermal conductivity of boron nitride. However, high heat dissipation cannot be obtained by simply mixing the polymer resin and boron nitride. Here, by using boron nitride excessively, the heat dissipation of the polymer resin can be enhanced, but on the other hand, there is a problem that the characteristics as the resin are lost.

  Therefore, by forming a boron nitride film on the surface of the polymer resin using a vapor deposition method or a sputtering method, high heat dissipation can be provided even with a small amount of boron nitride. However, in the vapor deposition method or the sputtering method, boron nitride moves linearly with respect to the coating target. Therefore, this method is effective for a flat coating target, but is not suitable for a curved coating target. In particular, it is difficult to coat boron nitride on the entire surface of a spherical object to be coated such as particles by this method.

  Therefore, an object of the present invention is to coat boron nitride on the entire surface of a polymer resin having a curved surface.

  As a result of intensive studies by the present inventors, by heating a mixture containing an ionic liquid, ammonia borane, and a polymer resin having a curved surface under a certain condition, the entire surface has a curved surface coated with boron nitride. It has been found that a polymer resin can be produced.

That is, the present invention includes the following.
[1] A first heating step of heating a mixture containing an ionic liquid, ammonia borane, and a polymer resin having a curved surface at 80 to 120 ° C .;
A second heating step of heating the mixture heated in the first heating step at a temperature exceeding the heating temperature in the first heating step;
A method for producing a polymer resin having a curved surface coated with boron nitride.
[2] The ionic liquid comprises 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) amide, and 1-butyl-3-methylimidazolium hexafluorophos. The production method according to [1], which is selected from the group consisting of folate.
[3] The manufacturing method according to [1] or [2], wherein the first heating step is performed for 1 hour or longer, and the second heating step is performed at 200 to 300 ° C. for 24 to 48 hours.
[4] A temperature raising step of continuously raising the temperature of a mixture containing an ionic liquid, ammonia borane, and a polymer resin having a curved surface to 80 ° C. to 120 ° C .;
A method for producing a polymer resin having a curved surface coated with boron nitride.
[5] A polymer resin having a curved surface coated with boron nitride, produced by the method according to any one of [1] to [4].

  According to the present invention, it is possible to provide a polymer resin having a curved surface in which boron nitride is coated on the entire surface.

A cross section of polystyrene particles coated with boron nitride is schematically shown. 2 shows a photograph of polystyrene particles coated with boron nitride produced in the examples. The photograph of the cross section of the polystyrene particle | grains coat | covered with the boron nitride manufactured in the Example is shown. 2 shows a photograph of polystyrene particles coated with boron nitride produced in the examples.

Hereinafter, the present invention will be described in detail.
The present invention relates to a polymer resin having a curved surface coated with boron nitride (hereinafter, simply referred to as a heating step) in which a mixture containing an ionic liquid, ammonia borane, and a polymer resin having a curved surface is heated under certain conditions. It is related with the manufacturing method of "it may be called" coating resin. "

When ammonia borane is heated in an ionic liquid, a dehydrogenation reaction occurs, boron nitride is synthesized and deposited, and the surface of the polymer resin is coated. Conversion from ammonia borane to boron nitride is represented by the following formula.
NH ₃ BH ₃ → BN + 3H ₂

  Since the polymer resin exists in the ionic liquid, boron nitride generated in the ionic liquid can contact the polymer resin from all directions. Thereby, not only a part of the surface of the polymer resin but also the entire surface can be continuously coated with boron nitride.

  The ionic liquid used in the present invention is not particularly limited, and generally known ionic liquids can be used. For example, the cation constituting the ionic liquid has the following structure:

［式中、Ｒ_１〜Ｒ_７は、それぞれ独立して、炭素数１〜１０のアルキル（例えば、メチル、エチル、ブチル、ペンチル、ヘキシル）、エトキシメチル、又はアリルである］
を有するカチオン等を挙げることができる。
一方、イオン液体を構成するアニオンとしては、以下の構造：

[Wherein, R _{1 to} R ₇ are each independently alkyl having 1 to 10 carbon atoms (for example, methyl, ethyl, butyl, pentyl, hexyl), ethoxymethyl, or allyl.]
And cations and the like.
On the other hand, the anion constituting the ionic liquid has the following structure:

を有するアニオンやクロライドアニオン（Ｃｌ⁻）等を挙げることができる。

And anions having chlorides and chloride anions (Cl ⁻ ).

Specific ionic liquids include 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmin] [BF ₄ ]), 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) amide ([Bmin] [TFSA]), and 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmin] [PF ₆ ]), 1-butyl-3-methylimidazolium chloride ([Bmin] [Cl]), N , N-diethyl-N-methyl-N- (methoxyethyl) ammonium tetrafluoroborate ([DEME] [BF ₄ ]) and the like. In particular, it is preferable to use [Bmin] [BF ₄ ], [Bmin] [TFSA], [Bmin] [PF ₆ ]. These ionic liquids may be used alone or in combination of two or more. By using an ionic liquid, boron nitride can be synthesized at a lower temperature than vapor deposition or sputtering. Therefore, it becomes possible to coat boron nitride on a polymer resin that is easily thermally decomposed.

  The polymer resin used in the present invention is not particularly limited as long as it has a curved surface structure. Examples thereof include a polymer resin having only a curved surface structure, a polymer resin having both a curved surface and a planar surface structure, and the like. In particular, it is preferable to use polymer resin particles. By using polymer resin particles, particles having a core-shell structure (polymer resin core and boron nitride shell) can be formed.

  Although the kind of polymer resin is not specifically limited, What has electrical insulation is preferable. For example, monomers having no polar functional group such as styrene, α-methylstyrene, vinyl toluene, vinyl biphenyl, vinyl naphthalene, vinyl acetate, vinyl propionate, acrylic acid, methacrylic acid, 2-hydroxyethyl methacrylate, methacryl Of one or more monomers selected from monomers having polar functional groups such as 2-dimethylaminoethyl acid, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, i-butyl methacrylate, acrylonitrile, benzyl methacrylate Homopolymers and copolymers can be mentioned.

  When core particles made of a polymer resin having a polar functional group are used, the boron nitride shell can be formed thick and uniform. Therefore, as a polymer resin, a homopolymer or copolymer of one or more monomer components having a polar functional group, or one or more monomer components having a polar functional group, and 1 having no polar functional group It is preferred to use a copolymer with more than one monomer component. When copolymerizing, it is preferable to use the monomer component having a polar functional group in a proportion of 80% by weight or less based on the total amount of the monomer component.

  The core particles may be purchased and used commercially, or may be prepared in the previous stage of the shell formation reaction. Preferably, the monomer component and the polymerization reaction initiator are added to the solvent, and the core particles are generated by allowing the polymerization reaction (core formation reaction) to proceed. Next, ammonia borane and a reaction initiator for initiating the reaction from ammonia borane to boron nitride are added to advance the shell formation reaction.

  The solvent used for the core formation reaction is not particularly limited, and examples thereof include ionic liquid, water, ethanol, methanol, propanol, acetone, petroleum ether, hexane, and ethyl acetate. In order to reduce the number of steps, it is preferable to use the same solvent for the core formation reaction and the shell formation reaction. Therefore, it is preferable to use an ionic liquid in the core formation reaction.

  The polymerization reaction initiator can be appropriately selected according to the monomer used. For example, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (V-70), 2,2′-azobis (isobutyronitrile) (AIBN), 2,2′-azobis [ 2- (2-imidazolin-2-yl) propane] (VA-061), 2,2′-azobis (2,4-dimethylvaleronitrile) (V-65), 1,1′-azobis (cyclohexane-1) Use azo compounds such as (carbonyl) (V-40), peroxides such as benzoyl peroxide, potassium persulfate, ammonium persulfate, cumene hydroxy peroxide, or redox initiators such as benzoyl peroxide-dimethylaniline. Can do.

  In order to disperse the core particles produced by polymerization, it is preferable to add a dispersion stabilizer in the solvent. Examples of the dispersion stabilizer include polyvinyl pyrrolidone (PVP), partially saponified polyvinyl alcohol, polyacrylic acid, polyethylene glycol, and low molecular surfactants such as sodium dodecyl sulfate.

  When polymer resin particles are used as the polymer resin having a curved surface, the average particle diameter of the polymer resin particles is preferably, for example, 50 to 2000 nm, and more preferably 100 to 1000 nm.

  The mixture containing the ionic liquid, ammonia borane, and the polymer resin having a curved surface is preferably heated in two stages. Specifically, after heating the mixture at a constant temperature (first heating step), it is preferable to further heat the mixture at a temperature exceeding the heating temperature in the first heating step (second heating step). Thus, by heating in two steps, a stronger boron nitride film can be formed on the surface of the polymer resin. Further, it is possible to prevent ammonia borane from remaining.

  The heating temperature in the first heating step is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, and still more preferably 80 ° C. or higher. As an upper limit of heating temperature, 150 degreeC, 140 degreeC, 130 degreeC, 120 degreeC etc. can be mentioned, for example.

  The heating time in the first heating step is preferably 0.5 hours or more, more preferably 1 hour or more. Examples of the upper limit of the heating time include 48 hours, 36 hours, and 24 hours.

  The heating temperature in the second heating step is preferably 160 ° C. or higher, more preferably 180 ° C. or higher. In particular, it is preferable to heat at 200 ° C. or higher in order to completely convert ammonia borane into boron nitride. Examples of the upper limit of the heating temperature include 350 ° C., 320 ° C., and 300 ° C., but if the heating temperature is too high, the boron nitride may be modified. It is particularly preferable that

  If the heating time is too short in the second heating step, ammonia borane may remain. Therefore, the heating time in the second heating step is preferably 16 hours or more, more preferably 20 hours or more, and further preferably 24 hours or more. Examples of the upper limit of the heating time include 72 hours, 60 hours, 48 hours, etc. However, if the heating time is too long, the boron nitride may be modified, so the upper limit of the heating time is 48 hours. It is particularly preferable that

  Instead of heating a mixture containing an ionic liquid, ammonia borane, and a polymer resin having a curved surface in two stages, it is also preferable to raise the temperature continuously. By continuously raising the temperature, non-uniform precipitation of boron nitride and fusion between polymer resins can be suppressed. As a result, a coating resin having a smooth boron nitride film and less aggregation / fusion can be produced.

  In the temperature raising step, it is preferable to continuously raise the temperature of the mixture containing the ionic liquid, ammonia borane, and the curved polymer resin from 60 ° C. to 350 ° C., and continuously from 70 ° C. to 300 ° C. It is more preferable to raise the temperature, it is more preferable to continuously raise the temperature from 80 ° C to 220 ° C, and it is particularly preferable to continuously raise the temperature from 80 ° C to 120 ° C.

  When the temperature is raised rapidly in the temperature raising step, non-uniform precipitation of boron nitride and fusion between polymer resins may occur. Therefore, it is preferable to heat up over 0.5 to 24 hours, and it is more preferable to heat up over 1 to 12 hours.

  The present invention also relates to a polymer resin having a curved surface coated with boron nitride, which is produced by the above production method. The coating resin according to the present invention has high heat dissipation because boron nitride having excellent thermal conductivity is continuously coated on the entire surface. The coating resin according to the present invention can be used for electronic parts and the like, for example.

〔Example〕
EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, a reference example, and a comparative example, the technical scope of this invention is not limited to this.

<Selection of ionic liquid>
In an ionic liquid shown in Table 1, ammonia borane was heated at 100 ° C. for 24 hours to confirm the precipitation state of boron nitride.

  As shown in Reference Examples 1 and 2, boron nitride was not precipitated in certain ionic liquids, but it is estimated that boron nitride can be precipitated by adjusting the heating conditions and the like.

<First heating step>
The ammonia borane in [Bmin] [BF ₄ ] was heated at the heating temperature and heating time shown in Table 2, and the precipitation state of boron nitride was confirmed.

  Since boron nitride precipitated in the first heating step was dissolved in methanol, it is suggested that bonds between boron nitride molecules are not sufficiently formed.

<Second heating step>
The ammonia borane in [Bmin] [BF ₄ ] was heated at 120 ° C. for 24 hours and then further heated at the heating temperature and heating time shown in Table 3 to confirm the remaining impurities (ammonia borane).

  Boron nitride that had undergone the second heating step did not dissolve in methanol. Therefore, it is suggested that the bonds between the boron nitride molecules are sufficiently formed.

  When the heating temperature in the second heating step is lower than 200 ° C., impurities remain, and when it is higher than 300 ° C., the boron nitride tends to be modified. Further, when the heating time in the second step is shorter than 24 hours, impurities remain, and when it is longer than 48 hours, the boron nitride tends to be modified.

<Manufacture of coated particles>
The raw materials shown in Table 4 were heated at 120 ° C. for 1 hour, and further heated at 300 ° C. for 24 hours. A photograph of the obtained sample by a scanning electron microscope (SEM) is shown in FIG. When the cross section of the sample was observed with a transmission electron microscope (TEM), particles having a core-shell structure were confirmed (FIG. 3). Moreover, the peaks of polystyrene and boron nitride were confirmed by a Fourier transform infrared spectrophotometer (FT-IR).

  Instead of performing the heating process in two steps, the temperature was continuously raised from 80 ° C. to 220 ° C. over 1 hour, and maintained at 220 ° C. for 24 hours to obtain polystyrene particles having a smoother boron nitride film. (FIG. 4).

Claims (5)

A first heating step of heating a mixture containing an ionic liquid, ammonia borane, and a polymer resin having a curved surface at 80 to 120 ° C .;
A second heating step of heating the mixture heated in the first heating step at a temperature exceeding the heating temperature in the first heating step;
A method for producing a polymer resin having a curved surface coated with boron nitride.   The ionic liquid is from 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) amide, and 1-butyl-3-methylimidazolium hexafluorophosphorate The manufacturing method of Claim 1 selected from the group which consists of.   The manufacturing method of Claim 1 or 2 which performs a 1st heating process for 1 hour or more and performs a 2nd heating process at 200-300 degreeC for 24 to 48 hours. A temperature raising step of continuously raising the temperature of a mixture containing an ionic liquid, ammonia borane, and a polymer resin having a curved surface from 80 ° C. to 120 ° C .;
A method for producing a polymer resin having a curved surface coated with boron nitride.   A polymer resin having a curved surface coated with boron nitride, produced by the method according to claim 1.

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