JP2000334705A - Method for curing process with electron rays - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an efficient curing process with electron rays which shows remarkable effects for upgrading the surface hardness and heat resistance by using a treating agent containing a chemical compound represented by formula and at the same time, irradiating a material to be treated with a specific accelerating voltage and a specific dosage of electron rays. SOLUTION: First a material to be treated is impregnated and/or coated with a treating agent containing a chemical compound represented by formula, and is irradiated with 10-1,000 kGy dosage of electron rays at 50-500 kV accelerating voltage. In the formula, R1 is a hydrogen atom, a 1-18C alkyl group, a 3-10C cycloalkyl group, a 3-10C aryl group, a 1-8C hydroxyalkyl group or the like; R5 is a hydrogen atom, a 1-12C alkyl group, a 3-10C cycloalkyl group, a 3-10C aryl group, a 1-12C hydroxyalkyl group or a 2-8C oxirane group. Further, R6 is a hydrogen atom or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electron beam curing for modifying woody veneers, decorative paper, laminated plywood, wood chips, cellulosic materials such as cellulosic fibers, plastics, metals, glass and ceramics. Regarding the processing method.

[0002]

2. Description of the Related Art In household furniture, office furniture, and building interior materials, wood veneer (push) is used to give a high-grade appearance to the surface of a base material made of wood plywood, metal plate, glass plate, or the like. And decorative paper are laminated on the surface of the base material. Then, in order to increase the surface hardness of this surface decorative material (wood veneer, decorative paper, etc.), and to increase the moisture resistance, water resistance, heat resistance, etc., a treatment agent is infiltrated into the surface decorative material and applied to the base material. After overlapping, the treatment agent is cured, or the treatment agent is allowed to penetrate the surface decorative material, and the treatment agent is cured as it is.

[0003] In the field of particleboard and fiberboard used as building materials and the like, the moisture resistance of wood chips and cellulosic fibers, which are the constituent materials, is also high.
In order to enhance water resistance, heat resistance, and the like, the above-mentioned treating agent is penetrated and hardened into wood chips and cellulose fibers. As the treatment agent, those containing an unsaturated polyester resin, a vinyl ester resin, a urethane acrylate resin, a urea resin, and a melamine resin are typically used. In the treatment method using the treatment agent, The treatment agent was thermally cured by passing the treatment material through a heating furnace. Therefore, productivity was very low.

[0004] Therefore, there has been a demand for a processing method which has high productivity and efficiently reforms.

[0005]

In particular, electron beam curing is known as a curing method applicable to radical polymerization. In this curing method, since irradiation with very high energy is possible, curing is completed in a short time. On the other hand, in the case of modifying a cellulosic substrate represented by wood, it is preferable to have a hydrophilic functional group, and HEMA (2-hydroxyethyl methacrylate) is used as a material which can be cured by the electron beam. ) And HEA (2-hydroxyethyl acrylate), but HEMA has a high surface hardness improving effect, but does not have sufficient electron beam curability.
On the other hand, HEA has high electron beam curability, but is inferior in surface hardness improving effect and heat resistance improving effect.

Accordingly, an object of the present invention is to provide a treatment method which is excellent in the effect of improving the surface hardness, the effect of improving the heat resistance, etc., and which efficiently performs the electron beam curing treatment.

[0007]

Means for Solving the Problems The present inventor has conducted various studies to solve the above-mentioned problems, and as a result, the following general formula (1)
It has been found that it is good to use the treating agent containing the compound represented by the formula (1) and to specify the conditions of electron beam irradiation, and have completed the present invention.

[0008]

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That is, the electron beam curing treatment method according to the present invention comprises the steps of impregnating and / or applying a treatment agent containing a compound represented by the above general formula (1) to a material to be treated; And / or an applied voltage of 50 to 500 kV and a dose of 10 to 1000 kGy
Irradiating with an electron beam. The compound represented by the general formula (1) has good permeability to a cellulosic material. Moreover, the electron beam curability is high.

It has been proposed by the present applicant to add this compound to an amino resin in order to solve the problems when an amino resin is used as a high boiling point resin (Japanese Patent Application Laid-Open No. H10-158471). Gazette). Further, methyl-, which is one kind of the compound represented by the general formula (1),
α- (Hydroxymethyl) acrylate has been proposed as a polymerizable component having good permeability to cellulosic materials (see JP-A-11-114914). However, all of these treating agents are for heat curing and are not effective for electron beam curing.

When hardening with an electron beam, HEMA or H
That EA has the above-mentioned disadvantages,
On the other hand, it has not been known that the compound represented by the general formula (1) has excellent electron beam curability and can improve both surface hardness and heat resistance.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the electron beam curing treatment method according to the present invention, a material to be treated described below is irradiated with an electron beam as described below using the following treating agent, thereby improving the material to be treated. Try to be quality. [Treatment agent] The treatment agent used in the method of the present invention is characterized by containing the compound represented by the general formula (1).

Since the compound represented by the general formula (1) has radical polymerizability, it has high electron beam curability. However, when the amount of the compound represented by the general formula (1) is small, it is preferable to add another radically polymerizable component. In order to enhance the electron beam curability, 80% by weight or more of the high boiling point resin, preferably 10% by weight or more contained in the treating agent, including the compound represented by the general formula (1), is subjected to high boiling point radical polymerization. It is preferable to occupy the components. In other words, in a preferred embodiment, 20% by weight or less of the high boiling point resin may be a non-radical polymerizable component. The compound represented by the general formula (1) preferably accounts for 5% by weight or more of the high boiling point radically polymerizable component.

Hereinafter, the constituents of these treating agents will be described in detail. The high boiling point resin preferably contained in the treating agent of the present invention is a polymer containing at least one kind of a high boiling point unsaturated polymer (including the concept of oligomer or macromonomer) or a high boiling point polymerizable monomer. Refers to components. Here, the high boiling point preferably means that the boiling point is 12 at normal pressure.
It means 0 ° C. or higher, more preferably 150 ° C. or higher, but those having no volatility at room temperature may be called high boiling point.

It is essential that the treating agent of the present invention contains a compound represented by the following general formula (1), and preferably contains at least 5% by weight of the high boiling radically polymerizable component.
More preferably, it contains 0% by weight or more, even more preferably 40% by weight or more, and most preferably 60% by weight or more.

[0016]

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In the general formula (1), when R ₆ is a hydrogen atom, specific examples include methyl-α-hydroxymethyl acrylate, ethyl-α-hydroxymethyl acrylate, n-butyl-α-hydroxymethyl Acrylate, 2-ethylhexyl-α-hydroxymethyl acrylate, methyl-α- (1-hydroxyethyl) acrylate, ethyl-α- (1-hydroxyethyl) acrylate, 2-ethylhexyl-α- (1-hydroxyethyl) acrylate, etc. Alkyl-α-hydroxyalkyl acrylates. Among these compounds, methyl-α-hydroxymethyl acrylate, ethyl-α-hydroxymethyl acrylate,
n-butyl-α-hydroxymethyl acrylate, 2-
Ethylhexyl-α-hydroxymethyl acrylate is particularly preferable in that the effects of the present invention can be further exhibited.

In the general formula (1), when R ₆ is represented by the following general formula (2), the compound is not particularly limited, but is represented by —CH ₂ (CHR ₇ ) _n O—. The repeating structure of the oxyalkylene group has the following structure. That is, the substituent represented by R ₇ may be independently composed of a hydrogen atom or an organic residue for each oxyalkylene group, and these oxyalkylene groups may be bonded in blocks or randomly. Is also good. R ₇ is preferably a hydrogen atom, a methyl group, or an ethyl group. The substituent represented by R ₁ is preferably an alkyl group having 1 to 18 carbon atoms, and the substituent represented by R ₅ is preferably a hydrogen atom.

[0019]

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In the general formula (1), when R ₆ is represented by the following general formula (3), the compound is not particularly limited, but preferably the substituent represented by R ₁ is An alkyl group having 1 to 8 carbon atoms, wherein R ₅ , R ₈ , R
_The substituent represented by ₉ is a hydrogen atom, and n is 4.

[0021]

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In the general formula (1), when R ₆ is represented by the following general formula (4), the compound is not particularly limited, but preferably, the substituent represented by R ₁ is An alkyl group having 1 to 8 carbon atoms, wherein the substituent represented by R ₅ is a hydrogen atom, the substituent represented by R ₁₀ is a hydrogen atom,
The substituent represented by R ₁₁ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0023]

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The above general formula (1) used in the present invention
The compound represented by is preferably a compound having a hydroxyl group, and more preferably a compound having a boiling point of 200 ° C. or more at normal pressure. Although it is essential that the treating agent of the present invention contains the compound represented by the above general formula (1), it may contain a high-boiling radical polymerizable component other than the compound.

The high-boiling radical polymerizable component includes:
It is composed of at least one kind of a high-boiling point polymer having an unsaturated group having radical polymerizability (including the concept of oligomer or macromonomer) and a high-boiling point radical polymerizable monomer. Specifically, for example, as the unsaturated group-containing polymer having radical polymerizability, vinyl ester resin, unsaturated polyester resin, polyester (meth) acrylate, poly (meth) acrylate having (meth) acrylate group, urethane ( (Meth) acrylates and other radically polymerizable macromonomers.
Examples of the high boiling point radical polymerizable monomer include vinyl monomers such as styrene, vinyltoluene, α-chlorostyrene, α-methylstyrene, 2-vinylpyridine and divinylbenzene; acrylic acid, 2-ethylhexyl acrylate, and n-stearyl acrylate , Lauryl /
Tridecyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-methoxyethyl acrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, polyester diacrylate, pentaerythritol triacrylate, trimethylol Propane triacrylate, tetramethylol methane tetraacrylate, dipentaerythritol hexaacrylate, a mixture of dipentaerythritol pentaacrylate, oligoester acrylate, pentaerythritol acrylate polyfunctional monomer, N-methylol acrylamide, N, N′-dimethylacrylamide, Acetone acrylamide, LA Uril methacrylate, tridecyl methacrylate, stearyl methacrylate, C ₁₂ ~
C ₁₃ alkyl methacrylates, C ₁₂ -C ₁₃ alkyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, 2-ethoxyethyl methacrylate,
Tetrahydrofurfuryl methacrylate, allyl methacrylate, glycidyl methacrylate, polyethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, tetramer mixture of dimethylaminoethyl methacrylate, dimethyl A tetramer mixture of aminoethyl methacrylate / methyl chloride, a tetramer mixture of dimethylaminoethyl methacrylate / dimethyl sulfate, allyl glycidyl ether, N-methylol methacrylamide, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane And other substituted ethylene compounds having radical polymerizability.

As described above, the treating agent of the present invention essentially contains the compound represented by the general formula (1), and may further contain, if necessary, a radical polymerizable component other than the compound. However, in addition to these components, a non-radical polymerizable component having a high boiling point may be contained. The non-radical polymerizable component having a high boiling point is not particularly limited, for example,
Examples thereof include polymethyl (meth) acrylate, polypropylene glycol, polyethylene glycol, melamine resin, and polyester.

The treating agent of the present invention may contain a radically polymerizable component having no high boiling point, if necessary. Examples of the radical polymerizable component having no high boiling point include, but are not limited to, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and the like. Further, the treating agent of the present invention may contain a solvent, if necessary. By containing the solvent, the workability when impregnating or applying the treating agent to the base material is easily improved, and the effect of the present invention when the impregnation and application are performed is also easily improved. Examples of the solvent include, but are not particularly limited to, glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether; and glycol ether acetates such as ethylene glycol monomethyl ether acetate and ethylene glycol monoethyl ether acetate. ,
There are aromatic hydrocarbons such as toluene and xylene, ketones such as methyl ethyl ketone and cyclohexanone, and acetates such as ethyl acetate and butyl acetate. These solvents are used alone or as a mixture. Further, the solvent includes N-methylformamide, N, N-dimethylformamide, N-methylformanilide, N-methylacetamide, N, N-dimethylacetamide, N-methylformamide.
Methylpyrrolidone, dimethyl sulfoxide, benzyl ethyl ether, dihexyl ether, acetonylacetone, isophorone, caproic acid, caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate, γ-butyrolactone One or more high-boiling solvents such as ethylene carbonate, propylene carbonate, and phenyl cellosolve acetate can also be added.

The processing agent of the present invention may contain a photosensitive initiator, a sensitizer and the like in order to enhance the electron beam curability.
The treating agent of the present invention may further contain other additives as necessary, for example, pigments, dyes, antioxidants, ultraviolet absorbers, and the like. [Processed Material] The processed material targeted by the method of the present invention is not particularly limited, and may be a material other than a cellulosic material. plywood,
Examples include cellulosic materials such as wood chips and wood fibers, plastics, metals, glass, and ceramics. [Electron Beam Curing Treatment] In carrying out the method of the present invention, it is important to maintain the irradiation conditions of the electron beam within a certain range, that is, within a range of an acceleration voltage of 50 to 500 kV and a dose of 10 to 1000 kGy. The acceleration voltage is preferably in the range of 200 to 500 kV. Acceleration voltage is 50k
If it is less than V, the treatment agent permeated into the material to be treated cannot be sufficiently cured. When the voltage exceeds 500 kV, most of the electron beams pass through the material to be processed, and there is a problem that efficiency is poor. If the dose is less than 10 kGy, the treatment agent cannot be sufficiently cured, and
If it exceeds 00 kGy, there is a problem that the material to be processed is deteriorated.

In the case of the treatment agent having the above-mentioned constitution, other radiation (infrared ray, visible ray, ultraviolet ray, X-ray, α-ray, γ
Ray, β ray, etc.) can be cured by adding an initiator and a sensitizer suitable for each radiation as needed. Curing can also be performed by combining an electron beam with other radiation. The case where the material to be treated is a cellulosic material and is a surface decorative material for a substrate such as a wood plywood, a metal plate or a glass plate will be described in some detail below.

In this case, the surface decorative material impregnated and / or coated with the treating agent is superimposed on the substrate, and then the electron beam irradiation is performed, or after the surface decorative material is irradiated with the electron beam, Perform bonding. The amount to be impregnated or applied to the surface decorative material is not particularly limited depending on the material and thickness of the material to be treated.
g / scale ² to 20 g / scale ² (where 1 shaku ² = (0.30
3 × 0.303) m ² ).

The acceleration voltage of the electron beam is preferably adjusted according to the thickness of the material to be processed. For example, as a specific example of the relationship between the acceleration voltage and the penetration depth, when the surface decorative material is a wooden veneer, the electron beam irradiation condition is such that when the thickness of the wooden veneer is 0.1 mm, the acceleration voltage is 175 kV or more. When the thickness of the wooden veneer is 0.2 mm, the accelerating voltage is 22
It is preferably 5 kV or more, and when the thickness of the veneer veneer is 0.4 mm, the acceleration voltage is preferably set to 300 kV or more.

When a wood chip of a particle board or a cellulosic fiber of a fiber board is to be treated, the treating agent also serves as a modifier and a binder of the wood chip or the cellulosic fiber. In the case of simple surface coating, a treatment agent containing a polymerizable component having a high boiling point may be applied to the surface of the material to be treated and cured.

According to the method of the present invention, it is also possible to infiltrate a hardening treatment by infiltrating a processing agent into wood which is hardly processed.

[0034]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited by these examples. (Production Example 1: Synthesis example of alkyl-α-hydroxymethyl acrylate) 400 g (4 mol) of ethyl acrylate in a 1000 ml four-necked flask equipped with a thermometer, a gas injection tube, a cooling tube, a stirrer, and a water bath. , 35
86 g (1 mol) of a weight% formaldehyde aqueous solution, 98 g (0.5 mol) of a 30 weight% trimethylamine aqueous solution as a tertiary amine compound, and 0.4 g of p-methoxyphenol as a polymerization inhibitor were charged. The ratio of p-methoxyphenol to ethyl acrylate is 1
000 ppm. Thereafter, the reaction solution was reacted by stirring at 60 ° C. for 3 hours while blowing air into the reaction solution.

After completion of the reaction, the reaction solution was separated into an organic layer and an aqueous layer, and then the organic layer was subjected to fractional distillation.
° C / 5 mmHg as a colorless transparent liquid ethyl-
111 g of α-hydroxymethyl acrylate was obtained. Methyl-α-hydroxymethyl acrylate and n-butyl-α-hydroxymethyl acrylate were also synthesized in the same manner as described above. (Production Example 2: Synthesis example of epoxy acrylate) Thermometer,
Araldite GY-250 (manufactured by Ciba Geigy), an epoxy compound having an average epoxy equivalent of 185, was placed in a four-necked flask equipped with a stirrer, an air blowing tube, and a cooling tube.
860 parts, acrylic acid 1140 parts, hydroquinone 0.
4 parts and triethylamine 1 as an esterification catalyst
2.0 parts were charged and reacted at 115 ° C. for 8.0 hours in an air stream to obtain an epoxy acrylate having an acid value of 7.9 and a number average molecular weight of 515.

Examples 1 to 6 At the mixing ratios shown in Table 1, the components were uniformly mixed to prepare the treating agents (1) to (6) of the present invention. 0.3m thick
the natural wood decorative plywood stuck natural wood veneer of m, prepared treating agent (1) to (6), respectively 8 g / scale ² (although,
After application to be 1 shaku ^{2 = (0.303 × 0.303) m} 2), it was impregnated to stand 1 hour. Next, the natural wood decorative plywood impregnated with the treating agent was accelerated at an accelerating voltage of 300 kV and a dose of 20 using an area beam type electron beam irradiation apparatus.
Treated woods (1) to (6) were obtained by curing the treating agent by irradiating one bath electron beam under a nitrogen atmosphere at 0 kGy and a conveyor speed of 6 m / min. Each of the obtained treated woods (1) to (6) is 15c
The test pieces were cut into mx 15 cm test pieces.

The obtained test pieces were evaluated for heat resistance, surface hardness, and dryness to the touch. The results are shown in Table 1. In addition, evaluation about heat resistance, surface hardness, and dryness to the touch was performed by the following test methods. (Heat resistance) The obtained test pieces were left in a thermostat at 80 ° C. ± 3 ° C., and the occurrence of cracks on the test piece surfaces after 48 hours and 96 hours was visually evaluated according to the following criteria.

：: No crack was observed. Δ: Small cracks are observed. X: Generation of a large crack is observed. (Surface hardness) 8. of JIS K 5400 (1995).
According to the pencil scratch test specified in 4.1,
When the surface of the obtained test piece is scratched five times with a pencil lead with a load of 1 kg, the density symbol of the hardest pencil among the pencils in which scratches on the surface are recognized less than twice Was defined as the surface hardness. (Dry-to-touch property) The dryness of the surface of each test piece after electron beam irradiation was evaluated by finger touch according to the following criteria.

：: tack-free. Δ: Some tackiness is felt. ×: Tack is felt.

[0040]

[Table 1]

Comparative Examples 1 and 2 Comparative treatment agents (1) and (2) were adjusted at the mixing ratios shown in Table 1, and test pieces were prepared in the same manner as in Example 1. I did it. The results are shown in Table 1. As shown in Table 1, in the treatments (1) to (6) of Examples 1 to 6, good results were obtained in all the tests.

[0042]

According to the present invention, it is possible to provide a treatment method which is excellent in the effect of improving the surface hardness and the heat resistance of the material to be treated, and which efficiently performs the electron beam curing treatment.

Claims (3)

[Claims] 1. A step of impregnating and / or applying a treatment agent containing a compound represented by the general formula (1) to a material to be treated, and applying an accelerating voltage to the material to be impregnated and / or coated with the treatment agent. 50-500kV, dose 10-1000kGy
Irradiating with an electron beam. Embedded image 2. The material to be treated is a cellulosic material,
The electron beam curing method according to claim 1. 3. An accelerating voltage of the electron beam is 200 to 500 k.
The electron beam curing treatment method according to claim 1, wherein V is V. 4.