JP3305708B2 - Functionalization method of ionizing radiation cured surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for imparting various functionalities to the surface of a plastic film or the like, and more particularly, to a method for reliably and stably imparting functionality to a surface layer cured by ionizing radiation.

[0002]

2. Description of the Related Art Plastic materials are widely used in daily necessities and various mechanical parts because of their properties such as workability and flexibility. Also, plastic materials having excellent toughness have been developed, and are being used as engineering plastics as substitutes for inorganic materials such as metal materials and glass. However, since the surface is inferior in hardness and abrasion resistance, it is necessary to provide a surface protective layer. Therefore, the plastic surface is hardened.

In order to harden a plastic surface, a method of applying a thermosetting resin such as an organosiloxane type or a melamine type to a plastic surface by dipping or spraying, and then curing the resin is mainly performed. However, there is a problem that the plastic substrate may be thermally deformed, and the time required for heating is long.

Therefore, recently, a method using an ionizing radiation-curable resin has become popular, and a plastic substrate is coated with an ultraviolet-curable resin or an electron beam-curable resin.
Hardening of the surface has been performed.

Recently, plastic films have been widely used for protecting surfaces of various plastic products, metal products, wood products, and the like. Depending on the product to be protected, it is necessary to impart various functions such as slipperiness, scratch resistance, and abrasion resistance to the plastic film, perform antistatic treatment, and further improve the tactile sensation. Examples of a method for imparting such a function to a plastic film include a method of coating an ink mixed with an additive exhibiting a desired function on the surface of the plastic film, a method of directly coating the surface of the plastic film as a base material, or another coating method There is a method of applying an additive through a layer by spraying or the like to perform surface treatment.

However, for example, an additive for surface functionalization is added to an ink composed of an ionizing radiation-curable resin, the resultant is applied to a plastic film substrate, and a cured surface is simply obtained by irradiating with ionizing radiation. In the conventional method, in many cases, the additive does not sufficiently ooze to the surface of the plastic film, and as a result, sufficient surface functionalization cannot be obtained.

In the case of performing a surface treatment in which an additive is directly applied to a cured surface of a plastic film, the surface energy of the cured surface is often small, and a sufficient and stable effect of the surface treatment with the additive cannot be expected. .

Accordingly, an object of the present invention is to provide a method for reliably imparting a desired surface function to an ionizing radiation cured film.

[0009]

[Means for Solving the Problems]

In light of the above objects, as a result of intensive research, the present inventors have coated a substrate with an ionizing radiation curing ink to which an additive for expressing desired functionality is added, and irradiating the substrate with ionizing radiation from the functionalized surface side. First, the ionizing radiation curing ink is semi-cured, and then, the ink is completely cured by irradiating it with ionizing radiation from the surface to be functionalized again, so that the additives can be localized on the surface to be functionalized. It has been discovered that the desired surface functionalization can be surely performed, and the present invention has been completed.

That is, the method for functionalizing an ionizing radiation-cured surface of the present invention uses a silicone, wax, silicon, powder, surfactant, fluorine compound, antistatic agent, ultraviolet absorber as an additive for surface functionalization, After coating a substrate with an ionizing radiation curing ink containing 0.01 to 50% by weight of a total of one or more of an antioxidant and a stabilizer, the ink is irradiated with ionizing radiation from the functionalized surface side, The ink is semi-cured so that the gel fraction becomes 90% or less, and then the ink is completely cured by irradiating ionizing radiation again from the functionalized surface side.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

First, the ionizing radiation curing ink that can be used in the present invention is an ink mainly composed of an ionizing radiation curable resin that is cured by ionizing radiation such as ultraviolet rays or electron beams.
As the main ionizing radiation-curable resin, a prepolymer or oligomer having an ethylenically unsaturated bond in the molecule, for example, unsaturated polyesters, polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polyol acrylate, Various acrylates such as melamine acrylate, polyester methacrylate, polyether methacrylate, polyol methacrylate, one or more such as various methacrylates such as melamine methacrylate, a monomer having an ethylenically unsaturated bond in the molecule as needed, for example, Styrene monomers such as styrene, α-methylstyrene, methyl acrylate, 2-ethylhexyl acrylate, methoxyethyl acrylate, Acrylates such as butoxyethyl acrylate, butyl acrylate, methoxybutyl acrylate, and phenyl acrylateMethyl methacrylate, ethyl methacrylate, propyl methacrylate, methoxyethyl methacrylate, ethoxymethyl methacrylate, ethoxymethyl methacrylate, phenyl methacrylate, methacrylic Methacrylic acid esters such as lauryl acid, unsaturated carboxylic acid amides such as acrylamide and methacrylamide, acrylic acid-2- (N, N
-Diethylamino) ethyl, methacrylic acid-2- (N, N
-Dimethylamino) ethyl, acrylic acid-2- (N, N-
Substituted amino alcohol esters of unsaturated acids such as dibenzylamino) ethyl, (N, N-dimethylamino) methyl methacrylate, 2- (N, N-diethylamino) propyl acrylate, ethylene glycol diacrylate,
Propylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, diethylene glycol dimethacrylate, etc. And / or polythiol compounds having two or more thiol groups in the molecule, such as trimethylolpropane trithioglycolate, trimethylolpropane trithiopropylate, pentaerythritol tetrathioglycolate, etc. It is a mixture.

[0012] The above compounds can be arbitrarily mixed to form an ink, but in order to have appropriate coating suitability, the prepolymer or oligomer is added in an amount of 5% by weight or more,
95 of the monomer and / or polythiol compound
% By weight or less. A polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, and benzoquinone may be added to the ink as a stabilizer in order to prevent the above compound from being cured before being irradiated with ultraviolet rays or electron beams.

When the ink is of an ultraviolet curing type, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxyester, tetramethylthiuram monosulfide, thioxanthone, and the like are used as photopolymerization initiators therein. N-butylamine as a sensitizer,
Triethylamine, tri-n-butylphosphine, or the like is used as a mixture.

Next, surface-functionalizing additives that can be used in the present invention include silicone, wax, silicon, powder, surfactant, fluorine compound antistatic agent, ultraviolet absorber, antioxidant, There are stabilizers and the like. These additives are used alone or in combination of two or more so as to obtain a desired functionalization. The addition amount is set so that the total amount of the additives is in the range of 0.01 to 50% by weight in the ionizing radiation curing ink. When the amount of the additive is less than 0.01% by weight, the function by the additive is not remarkably exhibited, while
If the amount exceeds the above range, the ionizing radiation curing ink is not sufficiently cured, or the adhesion between the substrate and the cured ink layer is undesirably reduced.

[0015] Silicone acts as a tactile enhancer. It also acts to improve chemical resistance. As the silicone actually used,
Amino-modified silicone, ether-modified silicone, mercapto-modified silicone, OH-containing silicone, UV or EB
There is a curable silicone. The preferred addition amount of silicone is 0.01 to 10% by weight.

[0016] Wax works to improve slipperiness and tactile sensation. Examples of the wax include polyethylene glycol and polytetramethylene glycol. The preferred amount of wax added is 0.1 to 10% by weight.

Silicon is added for improving resin modification, thermal stability and the like. Specifically, allyltrimethylsilane, 3-aminopropyltriethoxysilane, 1,3-bis (3-aminopropyl) -1,1,3,3-tetradimethylsiloxane, N, O
-Bis (trimethylsilyl) acetamide and the like.
The preferable addition amount of silicon is 0.01 to 10% by weight.

As for the powder, various functions can be obtained by selecting the powder. For example, by adding SiO ₂ , Al ₂ O ₃ , TiO _2, etc., the surface can be made a non-glare layer, and the scratch resistance and wear resistance can be improved. If carbon is added, the antistatic property can be improved, and coloring can be achieved. Further, the use of a wax powder or the like can improve the slipperiness.
Other examples include silicon powder and Teflon powder. The tactile sensation can also be improved by adding powder. The preferable addition amount of the powder is 1 to 50% by weight.

The surfactant and the fluorine compound function as a tactile sensation improver or an antistatic agent, and also contribute to improving the adhesion to the plastic substrate. Further, it imparts antifogging property (hydrophilicity). Specifically, there are a fatty acid salt, an alkylbenzene sulfonate and the like as the anionic surfactant, and an alkylamine salt and a pyridine derivative as the cationic surfactant. Examples of the non-ionic one include polyoxyethylene alkyl ether and sorbitan fatty acid ester. Further, examples of the fluorine compound include a fluorine-based surfactant such as a perfluoroalkyl carboxylate and a perfluoroalkyl ethylene oxide adduct. UV or EB curable fluorine compounds can also be used as the fluorine compound. Preferred amounts of the surfactant and the fluorine compound are 0.01 to 30% by weight and 0.01 to 30% by weight, respectively.
~ 10% by weight.

As the antistatic agent, conductive powder, various anionic, cationic, zwitterionic or nonionic surfactants, inorganic salts, and the like can be used. The preferable addition amount of the antistatic agent is 1 to 50% by weight.

As the ultraviolet absorber, benzotriazole-based, benzophenone-based, oxalic acid anilide-based ones and the like usually used as ultraviolet absorbers can be used. The preferable addition amount of the ultraviolet absorber is 0.1 to 10% by weight.

As the antioxidant, phenolic and hindered phenolic antioxidants can be used. The preferable addition amount of the antioxidant is 0.1 to 10% by weight.

Further, hindered amine-based stabilizers can be used. In particular, the light stabilizer is a hindered amine-based compound such as bis- (1,2,2- (3,5-di-t-butyl-4-hydroxybenzyl) -2'-n-butylmalonate).
2,6-pentamethyl-4-piperidyl), bis- (1,2,
2,6,6-pentamethyl-4-piperidyl) sebacate,
And tetrakis- (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate. The preferred amount of the stabilizer is 0.1 to 10% by weight. In addition, remarkable improvement in weather resistance can be obtained by using an ultraviolet absorber and a light stabilizer together.

Next, the surface functionalization method of the present invention will be described. First, an ink is prepared by using the ionizing radiation-curable resin described above and a desired additive without using a solvent or adding a solvent as needed. Examples of usable solvents include alcohols such as methanol, ethanol, isopropanol, methyl cellosolve and ethyl cellosolve, ethers such as tetrahydrofuran, ketones such as methyl ethyl ketone, acetone and methyl isobutyl kent, ethyl acetate and butyl acetate. There are esters, aromatic hydrocarbons such as toluene and xylene, and the like, or a mixed solvent thereof.

Next, the above-described ink is applied to the surface of the base material. It is preferable to use a plastic film such as polyester as the substrate. Application methods include blade coating, gravure coating, rod coating,
Knife coding, reverse roll coating, offset gravure coating and the like can be used.

After the application of the ink containing the additive, the film is irradiated with ionizing radiation. Before that, a film such as polyester is preferably laminated on the surface to which the ink is applied. The lamination of the film facilitates the shaping operation such as making the ionizing radiation curing ink layer uneven. In addition, the handling of the plastic film base material is also facilitated.For example, in the case of curing by ionizing radiation described below, after the first ionizing radiation irradiation is performed and the ink is partially cured, the base material is once wound up, stored, and used. In some cases, the surface can be completely cured by irradiating ionizing radiation again to be used.

Further, it is preferable that the film to be laminated is subjected to a surface treatment with the same additives as those previously added to the ink. As the surface treatment of the film with the additive, there is a method in which the additive is previously coated on the film, but a film produced from a composition in which the additive is kneaded may be used. By laminating such a film on the ink-coated surface of the plastic substrate, the additive component is more likely to be unevenly distributed on the surface in the subsequent step of ionizing radiation irradiation, and the surface functionality is further improved.

Next, ionizing radiation irradiation is performed. The ionizing radiation used is preferably an electron beam. In the case of electron beam irradiation, 50 emitted from various electron beam accelerators such as Cockloft-Walton type, Bande graph type, Resonant transformer type, Insulated core transformer type, Linear type, Dynamitron type, High frequency type electron curtain type etc. An electron beam having an energy in the range of 10001000 KeV, preferably 100-300 KeV can be used. The irradiation amount of the electron beam is generally 1 to 20 Mrad.

The irradiation with ionizing radiation is performed in two stages. First, as the first irradiation, ionizing radiation is applied from the surface to be functionalized. When the ink for ionizing radiation curing is completely cured by this first irradiation, the bleeding of the additive to the surface becomes worse, the additive cannot be unevenly distributed on the surface, and the functionalization of the surface becomes insufficient. . Therefore, in the first irradiation with ionizing radiation, the ionizing radiation curing ink is not completely cured, but is cured only to such an extent that the gel fraction of the ink after irradiation is 90% or less. When the ionizing radiation curing ink is semi-cured by the first irradiation of the ionizing radiation, the additive present in the ink is easily unevenly distributed on the surface of the ink by a so-called bleeding action. The gel fraction in the present invention is obtained by the difference between the weight after immersing the target semi-cured ink in tetrahydrofuran (THF) for 24 hours and drying, and the weight before immersion. Is determined by Gel fraction = [(W ₁ −W ₂ ) / W ₁ ] × 100 (where W ₁ is the weight of the ink before immersion, and W ₂ is 2
It is the weight after immersion and drying for 4 hours. )

Next, as a second irradiation, ionizing radiation is irradiated from the surface to be functionalized again to completely cure the ionizing radiation curing ink. Note that the second irradiation may be performed in a plurality of times as necessary. In the present invention, the ionizing radiation in the first and second irradiations is performed from the surface side that functions together. Therefore, since the ionizing radiation does not substantially pass through the plastic substrate, it has the advantage of hardly damaging the plastic substrate. The additive can be unevenly distributed on the surface of the ionizing radiation cured layer by the method described above, and the obtained plastic surface is stabilized,
Great functionality is provided.

A substrate is coated with an ionizing radiation curing ink containing an additive exhibiting a desired function, and the first ionizing radiation is irradiated from the functionalized surface side to semi-cure the ionizing radiation curing ink. . This irradiation causes the ink to have a gel fraction of 90.
%, So that the additive contained in the ink easily bleeds and is unevenly distributed on the surface. Then, in a state where the additive component is unevenly distributed or precipitated on the surface portion of the ink surface hardened layer, the ink is completely hardened by irradiating ionizing radiation from the surface side to be functionalized again,
A good functionalized surface layer is obtained.

In the present invention, since the irradiation of the first and second ionizing radiations is performed from the functionalized surface side, the ionizing radiation does not substantially pass through the substrate, and may not damage the substrate. rare.

In particular, a film which has been subjected to a surface treatment in advance with the same additive as that added to the ink is laminated on the ionizing radiation curing ink layer, and then the first and second ionizing radiation irradiations are performed. Is more effective. This is probably because the presence of the additive on the surface of the laminated film makes it easier for the additive component in the ink to move in the direction of the laminate film (the surface of the ink layer).

As described above, after the additive component is unevenly distributed on the surface layer portion of the ink layer by the first ionizing radiation irradiation, the second ionizing radiation irradiation is performed again in that state to completely cure the ink layer. Then, a stable functionalized surface can be obtained, and damage to the base material is reduced.

[0035]

【Example】

The present invention is described in more detail by the following examples.

Example 1 70 parts by weight of urethane acrylate (UV-7,700B, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 30 parts by weight of phenoxyethyl acrylate (PO-A, manufactured by Kyoeisha Yushi Kogyo KK), and silicone Acrylate (TUV-6000, manufactured by Toshiba Silicone Co., Ltd.) is mixed with 1 part by weight, heated to 40 ° C., and roll-coated to form a 100 μm-thick polyester film (Hp-7, manufactured by Teijin Limited). Coated. In addition, this polyester film has been subjected to an easy adhesion treatment in advance.

Next, a silicone-treated polyester film having a thickness of 50 μm (E7000, manufactured by Toyobo Co., Ltd.)
Was laminated. After lamination, the electron beam was irradiated with 1Mr from the polyester film (E7000) side which had been silicone-treated with 160 KV acceleration voltage as the first electron beam irradiation by an electron curtain type electron beam (EB) irradiation device (manufactured by ESI).
ad irradiation. After irradiation with the first ionizing radiation, the gel fraction of the semi-cured ink for curing ionizing radiation was measured in a manner described later, and was 65%.

Next, as a second electron beam irradiation, an electron beam was irradiated at 5 Mrad from the surface of the silicone-treated polyester film (E7000) at an accelerating voltage of 180 KV to completely cure the coating film.

After curing, the laminate film is removed, and the following (b)
The physical properties of the cured coating film were evaluated in the same manner as in (d).

(A) Gel Fraction After First Ionizing Radiation Irradiation The laminate film was cut into a size of 10 cm × 10 cm, and its weight (W ₁ ) was measured. This is of 100cm ³
It was immersed in THF for 24 hours and dried at 70 ° C. for 3 hours. The weight (W ₂ ) after drying was measured. Then, the gel fraction was determined by the following equation. Gel fraction = [(W ₁ −W ₂ ) / W ₁ ] × 100

(B) Nail Scratch Test The coating film is scratched with a forefinger's fingernail two to three times (scratch length is about 30 mm), and it is checked whether significant scratches, scratches that do not recover, or scratches that expose the fabric occur. Observed. ○: not damaged ×: damaged

(C) Slipperiness test A weight of 50 g was placed on the surface of the coating film, and the surface of the coating film was gradually angled to measure the angle at which the weight began to slide.

(D) Lipstick test A lipstick was applied to the surface of the coating film, left at room temperature for 4 hours, wiped off with petroleum benzene, and observed whether the lipstick disappeared. ：: Lipstick disappears ×: Lipstick remains The results are shown in Table 1.

Comparative Example 1 As a comparative example, the same ionizing radiation curing ink as in Example 1 was applied to the same substrate as in Example 1, and a similar laminated film was applied. Next, as the first electron beam irradiation, an electron beam of 5 Mrad was irradiated from the siliconized laminated polyester film side at an acceleration voltage of 180 kV. After this first electron beam irradiation, the gel fraction of the cured ink was measured and found to be 98%.

Next, as the second electron beam irradiation, 5M from the siliconized laminated polyester film side at an accelerating voltage of 180 kV.
The ink was completely cured by irradiation with an electron beam of rad. Next, the above-mentioned tests (b) to (d) were performed on the obtained cured coating film in the same manner as in Example 1. The results are shown in Table 1.

[0046]

Example 2 50 parts by weight of urethane acrylate (UV-4200B, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and 25 parts by weight of 1,6-hexanediol diacrylate (HDDA, manufactured by Nippon Kayaku Kogyo Co., Ltd.) And 25 parts by weight of an acrylic acid dimer (M-5600, manufactured by Toagosei Kogyo Co., Ltd.) and octyltrimethylammonium chloride (Katiogen 08, Daiichi Pharmaceutical Co., Ltd.)
2 parts by weight), heated to 60 ° C., and roll-coated a 100 μm-thick polyester film (Hp
-7, Teijin Limited). In addition, this polyester film has been subjected to an easy adhesion treatment in advance.

Next, a 50 μm-thick antistatic treated polyester film (E7410, manufactured by Toyobo Co., Ltd.) was laminated on the coated surface. After lamination, an electron beam (EB) irradiation device (manufactured by ESI) irradiated 1 Mrad of the electron beam from the surface of the polyester film which had been subjected to the antistatic treatment at an acceleration voltage of 160 kV as the first electron beam irradiation.
Then, the gel fraction was measured in the same manner as in Example 1.

Next, as a second electron beam irradiation, an electron beam of 5 Mrad was irradiated from the polyester film surface at 180 kV to completely cure the coating film. After curing, the laminate film was removed and the surface resistance was measured. The results are shown in Table 2.

Comparative Example 2 As a comparative example, the irradiation dose of the first electron beam irradiation in Example 2 was set to 5 Mrad at 180 kV, and a polyester film (T
A cured surface layer was prepared in the same manner as in Example 2, except that -60, manufactured by Toray Industries, Inc.) was used. The gel fraction of the ionizing radiation curing ink after the first electron beam irradiation was 100
%, And the ink was completely cured by the irradiation of the first electron beam. Next, the surface resistance of the obtained cured coating film was measured in the same manner as in Example 2. The results are shown in Table 2.

[0051]

[0052]

【The invention's effect】

As described in detail above, the cured surface according to the present invention has a larger surface function than a cured surface obtained by only one irradiation of ionizing radiation from the side to which the ink for ionizing radiation curing is applied. According to the present invention, by appropriately selecting the additives to be used, slipperiness, scratch resistance,
A cured film having excellent abrasion resistance and the like can be obtained, and a plastic film excellent in antistatic properties and tactile sensation can be obtained.

Continuation of the front page (56) References JP-A-63-176135 (JP, A) JP-A-60-78667 (JP, A) JP-A-63-137778 (JP, A) JP-B-47-24655 (JP, A) , B1) (58) Fields surveyed (Int. Cl. ⁷ , DB name) B05D 1/00-7/26

Claims (4)

(57) [Claims] (1) a silicone as an additive for surface functionalization,
An ionizing radiation curing ink containing 0.01 to 50% by weight of a total of one or more of wax, silicon, powder, surfactant, fluorine compound, antistatic agent, ultraviolet absorber, antioxidant and stabilizer. After coating the substrate, the surface to be functionalized is irradiated with ionizing radiation, the ink is semi-cured so that the gel fraction of the ink is 90% or less,
A method for functionalizing a surface, wherein the ink is completely cured by irradiating the functionalized surface with ionizing radiation again. 2. The method for functionalizing a surface according to claim 1, wherein after coating the substrate with the ionizing radiation curing ink, the coated surface is further laminated with a film. 3. The method for functionalizing a surface according to claim 2, wherein said laminate film is surface-treated with said additive. 4. A surface functionalizing method according to claim 1, wherein said ionizing radiation is an electron beam.