JP4708268B2 - Surface modification of polyolefin moldings - Google Patents

Description

  The present invention relates to a method for modifying the surface of a polyolefin molded body, more specifically, a method for coating the surface of a molded body with a halogen atom, and a surface-modified polyolefin molded body obtained by the method.

  Polyolefins are widely used as various molded articles including films, sheets, containers and the like because of their excellent properties such as processability, chemical resistance, mechanical strength and transparency. However, since polyolefin is inherently hydrophobic, there is a problem that it cannot be dealt with as it is depending on applications such as the need to coat the surface of a molded product.

  In order to improve the surface properties of such polyolefin molded products, various surface treatments such as heat treatment, wave energy or particle beam treatment, plasma treatment, corona treatment have been tried, and each has achieved a certain result. . Corona treatment is also used to increase the hydrophilicity of polyolefin molded products, but in the case of thermally decomposable polyolefins such as polypropylene, there is a tendency for hydrophilicity to decrease over time after corona treatment, which is fundamental. It is in a situation that cannot be said to be a proper solution. The reason for this decrease in hydrophilicity in pyrolytic polyolefin is thought to be that in pyrolytic polyolefin, the low molecular weight polymer produced during molding bleeds out to the surface over time, which covers the corona-treated surface. It is done.

On the other hand, in Japanese Patent Application Laid-Open No. 2004-131620 by the present applicants, a polar group in a polyolefin obtained by copolymerization of an olefin and a polar group-containing monomer is converted into an atom transfer radical polymerization initiation terminal having a halogen atom. A method of grafting a polar group-containing monomer such as an acrylate ester by atom transfer radical polymerization is disclosed. According to this method, a side-reaction such as crosslinking and decomposition is suppressed, and a polyolefin-polar polymer graft polymer can be obtained in which a low molecular weight polymer component, a non-grafted polar polymer, and the like are not present as much as possible. In a molded product obtained from a polyolefin-based material obtained by this method, it is expected that problems such as surface bleed out will be improved as compared with various surface treatment methods as described above. However, since the polar polymer segment exists in both the inside and the surface of the polyolefin, the molded body not only hardly exhibits the effect of sufficiently modifying the surface properties of the polyolefin molded body, but also has a different polymer inside. Since it is dispersed, the inherent physical properties of polyolefin are impaired.
JP 2004-131620 A

  In such a situation, the problems to be solved by the present inventors are a technique for modifying the surface of a polyolefin molded article by an industrially advantageous method without impairing the original properties of polyolefin as much as possible, and this modification technique. It is to provide a surface-modified polyolefin molded body obtained by the above.

The present invention has been proposed in order to solve the above-mentioned problems, and provides a molded body having a modified polyolefin surface by a new technique that has not been conventionally used. In other words, according to the present invention, a halogen atom is effectively introduced on the surface of the polyolefin molded body, and a polyolefin molded body having a halogen atom introduced on the surface of the molded body is obtained. The halogen atom introduction site has a function as an atom transfer radical polymerization initiation terminal, and provides, for example, a polyolefin molded body whose surface is modified with a non-olefin polymer by atom transfer radical polymerization of a non-olefin monomer.

  Specifically, the present invention provides a halogenated polyolefin molded article in which halogen atoms are introduced on the surface of the molded article obtained by allowing a halogenated agent to act on the polyolefin molded article, and an industrially effective production method thereof.

  According to the present invention, it is possible to obtain a polyolefin molded article into which a halogen atom having an atom transfer radical polymerization ability of a vinyl monomer capable of radical polymerization on the surface is introduced by a low-cost and simple process. The technology of the present invention makes it possible to obtain a polyolefin molded product having a wide variety of polymer segments introduced at a low cost and a completely new method, and the amount and type of polymer introduced on the surface of the molded product. Depending on the printability, paintability, heat resistance, impact resistance, hydrophilicity, hydrophobicity, biocompatibility, stimulus responsiveness, strength / hardness, wear resistance, conductivity, gas barrier property, biocompatibility Alternatively, it is possible to provide a polyolefin-based molded article that exhibits excellent performance in adhesion performance with metals, plastics, papers, and the like.

  Hereinafter, the halogenated polyolefin molded product in which halogen atoms are introduced into the surface of the molded product by allowing a halogenating agent to act on the polyolefin molded product, and the production method thereof will be specifically described.

  First, a halogenated polyolefin molded product obtained by allowing a halogen atom to act on the polyolefin molded product according to the present invention and having a halogen atom introduced into the surface of the molded product will be described.

  The polyolefin molded body used to obtain the halogenated polyolefin molded body of the present invention is a molded body in which a polyolefin resin is essential, and injection molding, extrusion molding, extrusion lamination molding, inflation processing, hollow molding, compression molding, If the shape is maintained after applying desired shape using a mold by applying heat and pressure to the polyolefin resin simultaneously or separately, such as cast molding or secondary processing of them, etc. For example, it can be used as a raw material for the halogenated polyolefin molded article according to the present invention.

  The polyolefin molded body used in the present invention is a molded body in which the polyolefin resin is exposed on a part of the surface or the entire surface in order to be halogenated. It may be a part of a composite processed product with the material.

The main component polyolefin resin constituting the polyolefin molded body is a (co) polymer having ethylene or α-olefin as a main component monomer. Preferred polyolefin resins include high-density polyethylene, medium-density polyethylene, and ethylene-based elastomer. , Propylene-based elastomer, isotactic polypolypropylene, syndiotactic polypropylene, high-pressure low-density polyethylene and its acrylic acid, acrylate ester, copolymer with vinyl acetate, polyolefin ionomer, 4-methylpentene-1 polymer, ethylene -A cyclic olefin copolymer etc. are mentioned. In addition, a resin obtained by modifying the above polyolefin resin by any method such as a polyolefin resin graft-modified with an acrylate ester or maleic anhydride in the presence of a peroxide, or a resin crosslinked with a crosslinking agent is also present. It can be used as a polyolefin resin constituting the polyolefin molded body according to the invention.
These may be used alone or in combination of two or more.

Any non-polyolefin resin, modifier, compatibilizing agent, inorganic filler component, or additive may be blended in the polyolefin molded body as necessary as long as the halogenation reaction of the present invention is not inhibited. . Examples of additives include softeners, stabilizers, fillers, antioxidants, crystal nucleating agents, waxes, thickeners, mechanical stability imparting agents, leveling agents, wetting agents, film-forming aids, crosslinking agents, Examples include antiseptics, rust inhibitors, pigments, fillers, dispersants, antifreezing agents, antifoaming agents, and the like. These may be added alone or in combination of two or more.

As the halogen atom introduced into the surface of the polyolefin molded body, chlorine, bromine and iodine are preferable, and a bromine atom is particularly preferable from the viewpoint of stability of molecular structure and ease of atom transfer radical polymerization.
Introduction of halogen atoms to the surface of the polyolefin molded body can be achieved by controlling reaction conditions using a halogenating agent.

  The halogenating agent used in the present invention is not particularly limited as long as it can produce a halogenated polyolefin molded body by halogenating a polyolefin molded body. Specifically, chlorine, bromine, iodine, phosphorus trichloride are used. Phosphorus tribromide, phosphorus triiodide, phosphorus pentachloride, phosphorus pentabromide, phosphorus pentaiodide, thionyl chloride, sulfuryl chloride, thionyl bromide, N-chlorosuccinimide, N-bromosuccinimide, N-bromocaprolactam, N-bromophthalimide, 1,3-dibromo-5,5-dimethylhydantoin, N-chloroglutarimide, N-bromoglutarimide, N, N′-dibromoisocyanuric acid, N-bromoacetamide, N-bromocarbamic acid ester , Dioxane dibromide, phenyltrimethylammonium tribromide, pyridini Muhydrobromide perbromide, pyrrolidone hydrotribromide, t-butyl hypochlorite, t-butyl hypobromite, copper (II) chloride, copper (II) bromide, iron (III) chloride, oxalyl chloride, IBr In particular, bromine and N-bromosuccinimide, which can be halogenated under mild conditions, are preferable.

  In the present invention, the method for introducing halogen atoms into the polyolefin molded body is not particularly limited, but the ease of introduction of halogen atoms into the polyolefin molded body, the type of polyolefin molded body, and the reaction conditions are mild. The optimal method is selected from the viewpoint of whether or not.

For example, for bromination, a photobromine that brominates alkenes by reacting bromine under light irradiation, as disclosed in GA Russel et al., J. Am. Chem. Soc., 77, 4025 (1955). Angew. Chem. Int. Ed. Engl., 37, 1895, by PR Schneiner et al.
(1998), a method of brominating cyclic alkyl by heating to reflux in a solvent in the presence of 50% aqueous NaOH and carbon tetrabromide, as described in MC Ford et al., J. Chem.
Soc., 2240 (1952) discloses a method in which N-bromosuccinimide is brominated at the alkyl terminal by a radical reaction using a radical initiator such as azobisisobutyronitrile.

A solvent may or may not be used for introducing a halogen atom into the surface of the polyolefin molded article of the present invention, that is, halogenation. When a solvent is used, any solvent that does not inhibit the halogenation reaction and does not dissolve the polyolefin molded article can be used. Specific examples include aromatic hydrocarbon solvents such as benzene, toluene and xylene, aliphatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane and decane, and fats such as cyclohexane, methylcyclohexane and decahydronaphthalene. Cyclic hydrocarbon solvents, chlorinated hydrocarbon solvents such as chlorobenzene, dichlorobenzene, trichlorobenzene, methylene chloride, chloroform, carbon tetrachloride and tetrachloroethylene, methanol, ethanol, n-propanol, iso-propanol, n- Alcohol solvents such as butanol, sec-butanol and tert-butanol, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and dimethyl phthalate, dimethyl ether, die Ether, di -n- amyl ether, and ether solvents such as tetrahydrofuran and dioxy anisole and the like. Water can also be used as a solvent. These solvents may be used alone or in combination of two or more.

  The reaction temperature is not particularly limited as long as it is a temperature at which the polyolefin molded body does not melt or swell and the halogenation reaction proceeds, but it is usually -50 ° C to 150 ° C. The reaction is preferably 0 ° C to 80 ° C, more preferably a reaction under mild conditions such as 0 ° C to 50 ° C. In some cases, the reaction can be performed under reduced pressure, normal pressure, or increased pressure.

In the examples described in the specification of the present application, a room temperature bromination method using bromine vapor in the absence of a solvent is adopted, but this is one of the recommended methods from the viewpoint of simplicity and bromination efficiency.
Introduction of halogen atoms to the surface of the polyolefin molded body can be confirmed by a spectroscopic method such as X-ray photoelectron spectroscopy, electron beam microanalyzer, or nuclear magnetic resonance spectrum.

  In addition, according to the production method of the present invention, it is possible to introduce halogen atoms at a higher concentration on the surface than inside the polyolefin molded body, and as a result, the physical properties of the polyolefin resin are reduced, that is, the melting point is lowered and coloring during molding is minimized. It becomes possible to suppress.

  In the present invention, a desirable halogenated polyolefin molded body is a surface layer of the molded body, that is, a surface layer portion usually having a depth of 0 to 500 μm from the surface of the molded body, preferably a surface layer portion having a depth of 0 to 200 μm, Preferably, the molded body has a halogenated concentration of a surface layer portion having a depth of 0 to 100 μm, which is relatively high compared to the inside thereof.

The halogenated polyolefin molded article according to the present invention obtained as described above is characterized in that the halogen atom introduced on the surface has a function as an atom transfer radical polymerization initiating group accompanied by dissociation between covalent bonds with the carbon atom. It is.
Atom transfer radical polymerization (ATRP) is described in Science, (1996), 272,866, Chem. Rev., 101, 2921 (2001), WO96 / 30421, WO97 / 18247, WO98 / 01480, WO98 / 40415. No., WO00 / 156795, or Sawamoto et al., Chem. Rev., 101, 3689 (2001), JP-A-8-41117, JP-A-9-208616, JP-A-2000-264914, As disclosed in JP 2001-316410, JP 2002-80523, and JP 2004-307872, a metal having an organic halide or a sulfonyl halide as an initiator and a transition metal as a central metal In this method, a radical polymerizable monomer is radically polymerized using a complex as a catalyst, and the halogen atom introduced into the surface according to the present invention functions as a polymerization initiating group accompanied by dissociation between covalent bonds with the carbon atom.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.
The X-ray photoelectron spectroscopic analysis of the surface of the molded body shown in this example uses an SSX-100 type X-ray photoelectron spectrometer manufactured by SSI, and the bromine atom distribution state is an EPMA-1600 type manufactured by Shimadzu Corporation. An electron beam microanalyzer was used. In addition, ATR / IR analysis was performed using an FTS-6000 type infrared spectrophotometer manufactured by Biorad.

Production of halogenated polypropylene molded body with bromine atoms introduced on the surface. Commercially available polypropylene (PP) powder (F102WP, manufactured by Mitsui Chemicals) is pressed at 180 ° C. and 10 MPa using a press molding machine, and is about 1 mm thick sheet. A polypropylene (PP) molded body (hereinafter referred to as PP sheet) was prepared. The produced PP sheet was cut into a size of 1 cm × 2 cm and set in a 200 ml glass container at 25 ° C. Gently insert a glass microtube containing 0.5 ml of bromine into this container so that the contents do not spill, close the mouth of the eggplant flask with a stopper, and fill the flask with bromine vapor. And left at 25 ° C. for 1 hour. Thereafter, the PP sheet in the flask was taken out using tweezers, and the taken out PP sheet was washed successively in 100 ml of methanol and 100 ml of acetone. The washed PP sheet was dried under reduced pressure at 80 ° C. for 10 hours. The dried PP sheet had the same shape as that immediately after molding (before bromine treatment) and was not colored.

  When the surface of the obtained PP sheet was analyzed by X-ray photoelectron spectroscopy (XPS, ESCA), 0.2 atom% of bromine element was detected. In addition, when the distribution state of bromine atoms in the depth direction of the sheet was analyzed with an electron beam microanalyzer (EPMA), bromine atoms were detected in the region from the sheet surface to about 70 μm, and the detected amount increased from the surface to the inside. The distribution state of decreasing was confirmed. In this way, a polypropylene molded body having bromine introduced on the surface was obtained.

Confirmation of the function as an atom transfer radical polymerization initiating group on the surface of the sheet-shaped halogenated polypropylene molded body In a 50 ml glass reactor sufficiently substituted with nitrogen, a stirrer chip and the sheet-shaped halogenated polypropylene molded body obtained as described above were used. One piece was set at 25 ° C., 24.5 ml of commercially available acetone degassed under a nitrogen atmosphere and 4.5 ml of methyl methacrylate monomer (MMA) were added, stoppered and gently stirred with a stirrer. After 20 minutes, 65 mg of cuprous bromide (CuBr) and N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine (PMDETA) 0.17 ml acetone 2 ml prepared in a separate container The solution was added to the reactor and properly plugged, and then gently stirred at 25 ° C. for 30 minutes. Thereafter, stirring with a stirrer was stopped, and the reaction solution charged with the PP sheet was allowed to stand at 25 ° C. under a nitrogen atmosphere. Three days later, the inner sheet was taken out with tweezers and washed well in 100 ml of methanol and 100 ml of acetone, respectively. The washed sheet-like molded body was placed in a glass petri dish and allowed to air dry for 24 hours. When ATR / IR analysis was performed on the dried sheet surface, characteristic peaks of polymethacrylate were observed at 1730 cm-1, 1270 cm-1, 1242 cm-1, 1193 cm-1, 1149 cm-1, and The presence of polymethyl methacrylate was confirmed.

[Comparative Example 1]
Similarly, atom transfer radical polymerization of MMA was attempted for the sheet-like polypropylene (PP) molded body before the treatment with bromine described in Example 1. When the surface of the obtained sheet-like molded body was analyzed by ATR / IR analysis, the absorption pattern was not changed from the absorption pattern on the sheet surface before polymerization, and the production of MMA polymer was not confirmed.

The brominated mapping result by EPMA of the halogenated polypropylene molded body obtained in Example 1 is shown (image processing is performed in the specified plane based on the analysis data, and the bromine concentration is shown by the shade of the color tone. In the figure, the white portion indicates that the bromine concentration is high, and it was found that more bromine was present near the surface of the molded body (the left-right direction of the drawing corresponds to the depth direction of the molded body). 2 shows characteristic X-ray spectrum data of bromine by EPMA of the halogenated polypropylene molded product obtained in Example 1 (the horizontal direction in the drawing corresponds to the depth direction of the molded product, and the vertical direction in the drawing indicates the spectral intensity. The intensity increases as it goes upward, indicating that the characteristic X-ray spectrum intensity of bromine is large near the surface of the molded body).

Claims (1)

It is obtained by allowing a halogenated agent to act at 0 to 80 ° C. in the absence of a solvent on a polyolefin molded body containing a polyolefin having a thickness of more than 100 μm as a main component, and halogen atoms are directly bonded to the main chain of the polyolefin. On the surface of the molded body
Including a step of atom transfer radical polymerization of a non-olefin monomer using the halogen atom as an atom transfer radical polymerization initiation group,
A method for producing a polyolefin molded body surface-modified with a non-olefin polymer,
In the molded product in which halogen atoms are directly bonded to the polyolefin main chain, the halogen concentration in the surface layer portion up to 100 μm from the surface is higher than the internal halogen concentration in the surface layer portion.