JPH10151676A - Cutting method of photocured crosslinked resin sheet - Google Patents

Abstract

(57) [Problem] To provide a method for quickly cutting a crosslinked resin sheet obtained by curing an actinic ray-curable composition without causing cracks, chipping or the like. SOLUTION: A cross-linked resin sheet is cut by irradiating a laser beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for cutting a crosslinked resin sheet obtained by polymerizing an actinic ray-curable composition. This crosslinked resin sheet is used for touch panels of various electronic devices.

[0002]

2. Description of the Related Art Resin sheets are widely used in various fields, but most of them are formed by molding a thermoplastic resin such as polyethylene, polypropylene or polyethylene terephthalate into a sheet. However, for special applications such as touch panels for electronic devices, it is difficult to satisfy the required performance with a sheet formed of such a thermoplastic resin, and a crosslinked resin sheet obtained by polymerizing an actinic ray-curable composition is used. That is being considered. When a touch panel or the like is manufactured, it is necessary to cut a large-sized resin sheet into a desired shape and size. In order to cut the resin sheet into a desired shape, sharp blades such as scissors and cutters are exclusively used for thin resin sheets. In the case of a thick resin sheet, a method of cutting with a saw, or a method of rotating a tape or a disc with an abrasive attached thereto at a high speed to cut the sheet is used.

[0003]

However, the crosslinked resin sheet obtained by polymerizing the actinic ray-curable composition, when cut by the above-described cutting method, may be broken during the cutting or may be cracked. As a result, it was found that the product yield was reduced. This decrease in product yield tends to be more pronounced as the resin sheet becomes thinner. Although the cause of the breakage of the resin sheet during this cutting is not clear,
It is presumed to be based on the chemical structure of the resin. That is, the thermoplastic resin sheet is basically composed of a chain polymer, but the crosslinked resin sheet obtained by polymerizing the actinic ray-curable composition is different from this, and has a three-dimensionally crosslinked structure. . Therefore, it is considered to be high in hardness and brittle. The present invention provides a method for cutting such a crosslinked resin sheet without breaking it.

[0004]

According to the present invention, a crosslinked resin sheet obtained by polymerizing an actinic ray-curable composition is irradiated with a laser beam and cut to break the crosslinked resin sheet. Can be cut without.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The resin sheet of the present invention is obtained by polymerizing an actinic ray-curable composition into a sheet. As the actinic ray-curable composition, one which is cured by ultraviolet rays in the presence of a radical polymerization initiator is usually used. As the polymerizable component, various known compounds having an ethylenic double bond can be used. Usually, an actinic ray-curable composition comprising a polymerizable component mainly having a crosslinking ability, that is, one having two or more ethylenic double bonds in one molecule is used. Preferably, bis (meth) acrylate is used as the polymerizable component. For example, an actinic ray-curable composition in which the polymerizable component mainly comprises a bis (meth) acrylate selected from the following formulas (6) and (7) is preferably used.

[0006]

Embedded image

(Where R¹And R^TwoAre independent
Represents a hydrogen or methyl group. R^ThreeIs ethereal oxygen or
Is C which may contain thioetheric sulfur₁~ C₆of
A hydrocarbon group, preferably C_Two~ C_FourRepresents an alkylene group of
You. R^FourContains etheric oxygen or thioetheric sulfur.
C₁~ C₆A hydrocarbon group, preferably C
₁~ C_ThreeRepresents an alkylene group. X is a halogen atom or
C₁~ C₆Represents an alkyl group or an alkoxy group.
n shows 0 or the integer of 1-4. Where n is an integer of 2 or more
A plurality of Xs may be different from each other)

[0008]

Embedded image

(Wherein, R ⁵ and R ⁶ each independently represent hydrogen or a methyl group; p represents 1 or 2, q represents 0 or 1) Some of the compounds represented by the formula (6) An example is as follows. p-bis (β-methacryloyloxyethylthiomethyl) benzene, p-bis (β-acryloyloxyethylthiomethyl) benzene, m-bis (β-
Methacryloyloxyethylthiomethyl) benzene, m
-Bis (β-acryloyloxyethylthiomethyl) benzene, p-bis (β-methacryloyloxyethyloxyethylthiomethyl) benzene, p-bis (β-methacryloyloxyethylthiomethyl) tetrabromobenzene, m-bis (β -Methacryloyloxyethylthiomethyl) tetrachlorobenzene. These compounds can be synthesized, for example, by the method disclosed in JP-A-62-195357.

Some examples of the compound represented by the formula (7) are as follows. Bis (oxymethyl) tricyclo [5.2.1.0 ^2.6 ] decane = diacrylate, bis (oxymethyl) tricyclo [5.2.1.0
^2.6 ] decane = dimethacrylate, bis (oxymethyl) tricyclo [5.2.1.0 ^2.6 ] decane = acrylate methacrylate, bis (oxymethyl) pentacyclo [6.5.1.1 ^3.6 . 0 ^2.7 . 0 ^9.13 ] pentadecane diacrylate, bis (oxymethyl) pentacyclo [6.5.1.1 ^3.6 . 0 ^2.7 . ^09.13 ] pentadecane dimethacrylate, bis (oxymethyl) pentacyclo [6.5.1.1 ^3.6 . 0 ^2.7. 0 ^9.13 ] pentadecane acrylate methacrylate. These compounds can be synthesized, for example, by the method disclosed in JP-A-62-225508.

The actinic ray-curable composition contains, in addition to the bis (meth) acrylate selected from the above formulas (6) and (7), other polymer which is compatible with and copolymerizable with the bis (meth) acrylate. Sexual compounds may be used in combination. Examples of such a compound include methyl (meth) acrylate, phenyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, methacryloyloxymethyltetracyclododecane, methacryloyloxymethyltetracyclododecene, and ethylene glycol di (meth) acrylate. ) Acrylate, diethylene glycol di (meth) acrylate,
1,6-hexanediol di (meth) acrylate,
2,2-bis [4- (β-methacryloyloxyethoxy) phenyl] propane, 2,2′-bis [4- (β-
(Methacryloyloxyethoxy) cyclohexyl] propane, (meth) acrylate compounds such as 1,4-bis (methacryloyloxymethyl) cyclohexane, trimethylolpropane tri (meth) acrylate, styrene, chlorostyrene, divinylbenzene, α-methylstyrene, etc. Styrene which may have a substituent in a nucleus or a side chain is exemplified. Of these, methacryloyloxymethylcyclododecane, 2,2-bis [4- (β
-Methacryloyloxyethoxy) phenyl] propane, 2,2-bis [4- (β-methacryloyloxyethoxy) cyclohexyl] propane, 1,4-bis (methacryloyloxymethyl) cyclohexane, and mixtures thereof are particularly preferred. These compounds are preferably used in an amount of 10% by weight or less based on the bis (meth) acrylate of the formulas (6) and (7).

The actinic ray-curable composition preferably further contains a mercapto compound in addition to the bis (meth) acrylates of the formulas (6) and (7). Since the mercapto compound acts as a chain transfer agent, polymerization proceeds uniformly and gently, and a resin sheet having a small retardation value is generated. As the mercapto compound, a compound having two or more mercapto groups is preferably used. When such a mercapto compound is used, a resin sheet having a small retardation value and appropriate toughness can be obtained without significantly impairing heat resistance. The mercapto compound is used in an amount of usually 25% by weight or less, preferably 1 to 10% by weight, based on the polymerizable component having an ethylenically unsaturated bond. When the ratio of the mercapto compound is too large, the heat resistance of the obtained resin sheet is reduced. As the mercapto compound contained in the actinic ray-curable composition, those represented by the following formulas (8) to (10) are preferable.

[0013]

Embedded image

In the formula, a plurality of R ⁷ may be different from each other and each represents a methylene group or an ethylene group. R ⁸ represents a C ₂ -C ₁₅ , preferably C ₂ -C ₆ hydrocarbon residue which may contain etheric oxygen and / or thioetheric sulfur. a shows the integer of 2-6. That is, the compound represented by the formula (8) is a diester to hexaester of thioglycolic acid or thiopropionic acid and a polyol. Some examples are pentaerythritol tetrakis (β-thiopropionate), pentaerythritol tetrakis (thioglycolate), trimethylolpropane tris (β-thiopropionate), and trimethylolpropane tris (thioglycolate). , Diethylene glycol bis (β-thiopropionate), diethylene glycol bis (thioglycolate), triethylene glycol bis (β-thiopropionate), triethylene glycol bis (thioglycolate), dipentaerythritol hexakis (β -Thiopropionate), dipentaerythritol hexakis (thioglycolate) and the like.

[0015]

Embedded image

Wherein Y may be different from each other and
(CH_Two)_b-(CO)-(OCH _Two-CH_Two)_c−
(CH_Two)_dIndicates-. Where b is an integer of 1 to 4 and c is 1
And an integer of 0 to 4, d represents an integer of 0 to 2, respectively. Sand
The compound of the formula (4) is a triisocyanurate containing an ω-SH group.
It is. Some examples are Tris [2-
(Β-thiopropionyloxy) ethyl] isocyanurate
, Tris (2-thioglyconyloxyethyl) iso
Cyanurate, tris [2- (β-thiopropionylo
[Xyethoxy) ethyl] isocyanurate, tris (2
-Thioglyconyloxyethoxyethyl) isocyanurate
, Tris [3- (β-thiopropionyloxy) propyl
Ropyl] isocyanurate, tris (3-thioglyconi
Loxypropyl) isocyanurate and the like.
You.

[0017]

Embedded image

In the formula, R ⁹ and R ¹⁰ may be different from each other and represent a C ₁ -C ₃ hydrocarbon group. e and f each represent 0 or 1. g represents 1 or 2. That is, the compound of the formula (10) is an α, ω-SH group-containing compound.
Some examples are benzenedimercaptan,
Xylylene dimercaptan, 4,4'-dimercaptodiphenyl sulfide, and the like. The actinic ray-curable composition may further contain an amorphous thermoplastic resin dissolved in a polymerizable component.

The amorphous thermoplastic resin has a crystallinity of not more than 5% by an X-ray diffraction method, and specifically includes polystyrene, styrene-acrylonitrile copolymer, polycarbonate, polymethyl methacrylate, and polymethyl methacrylate. Ether sulfone, polyarylate, amorphous polyolefin,
Examples thereof include polyphenylene oxide, polyvinyl chloride, polycyclohexyl methacrylate, and fluorene copolymerized polyester. Of these, amorphous polyolefin is preferable because it is difficult to generate birefringence and gives a resin sheet with low hygroscopicity, so that it can be used widely. Examples of the amorphous polyolefin include those having the following cyclic structures.

(1) Cyclopentadiene or its induction
Addition of conductor to norbornadiene or its derivative
Substance or dicyclopentadiene or its derivative
Co-polymerization of an adduct with Tylene and a compound having a vinyl group
Combination or hydrogenated product thereof Examples of these adducts include bicyclo [2.2.1]
Hept-2-ene, tetracyclo [4.4.0.
1^2.5. 1^7.10] -3-dodecene, hexacyclo [6.
6.1.1^3.6. 1^10.13. 0^2.7. 0^9.14-4-F
Ptadecene, octacyclo [8.8.0.1^2.9. 1
^4.7. 1^11.18. 1^13.16. 0^3.8. 0^12.17] -5
Dococene, pentacyclo [6.6.1.1^3.6.
0^2.7. 0^9.14-4-Hexadecene, heptacyclo
[8.8.0.1^2.9. 1^4.7. 1^11.18. 0^3.8. 0
^12.17] -5-eicosene, pentacyclo [6.5.
1.1^3.6. 0^2.7. 0^9.13-4-pentadecene, pe
Nantacyclo [6.5.1.1^3.6. 0^2.7] -4,10
-Pentadecadiene, tricyclo [4.3.0.
1^2.5] -3-decene, tricyclo [4.4.0.1
^2.5] -3-undecene, pentacyclo [7.4.0.
1^2.5. 1^9.12. 0^8.13-3-pentadecene, hepta
Cyclo [8.7.0.1^3.6. 1^10.17. 1^12.15. 0
^2.7. 0^11.16-4-Eicosene, pentacyclo
[8.4.0.1^2.5. 1^9.12. 0^8.13-3-hexa
Decene, heptacyclo [8.8.0.1^4.7.
1^11.18. 1^13.16. 0^3.8. 0^12.17-5-Henue
Icocene, nonacyclo [10.9.1.1^4.7. 1
^13.20. 1^15.18. 0 ^2.10. 0^3.8. 0^12.21. 0
^14.19-5-pentacocene, nonacyclo [10.1
0.1.1^5.8. 1^14.21. 1^16.19. 0^2.11.
0^4.9. 0^13.22. 0^15.20-5-hexacocene, etc.
And chlorine, bromine, fluorine, methyl,
Tyl, propyl, phenyl, naphthyl, butyl
Group, cyclohexyl group, ethylidene group, propylidene
Group, a substituent such as a benzyl group is bonded.
You.

Compounds having a vinyl group include α
-Olefin, 1,3-conjugated diene, styrene and styrene derivatives are used. As the α-olefin, ethylene, propylene, butylene and the like,
Butadiene, isoprene, pentadiene and the like as 1,3-conjugated dienes, and o-
Methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, o-chlorostyrene, m-
Chlorostyrene, p-chlorostyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, p-
Examples include methoxystyrene, p-chloroethylstyrene, p-methyl-α-methylstyrene, and the like.

(2) Ring-opened polymer of tetracyclo-3-dodecene or a derivative thereof and / or bicyclohept-2-ene or a derivative thereof Tetracyclo-3-dodecene is represented by the following formula (11), and bicyclohept-2-ene is represented by the following formula: (12) A compound represented by the formula:

[0023]

Embedded image

These skeletons include a polar group such as a carboxyl group, an acetoxy group, a cyano group, a halogen, a methyl group, an ethyl group, a propyl group, a phenyl group, a naphthyl group,
A hydrocarbon group such as a butyl group, a cyclohexyl group, an ethylidene group, a propylidene group and a benzyl group may be substituted.

(3) Copolymer of tetracyclo-3-dodecene or a derivative thereof and / or bicyclohept-2-ene or a derivative thereof with an olefin or a hydrogenated product thereof As the olefin, a cycloolefin is usually used. Cycloolefins include cyclopentene, cyclooctene, 1,5-cyclooctadiene, 1,5,9-
Monocyclic olefins such as cyclododecatriene, polycyclics such as bicyclohept-2-ene, tricyclo-3-decene, tricyclo-9-undecene, tetracyclo-3-dodecene, pentacyclo-4-pentadecene, and pentacyclo-4-hexadecene Cycloolefin.

Preferred as the amorphous polyolefin are tetracyclo-3-dodecene and / or bicyclohept-2 having a polar group in the above (2) or (3).
-Derived from ene. The proportion of the amorphous thermoplastic resin in the actinic ray-curable composition is usually 50% by weight.
Hereinafter, it is particularly 2 to 50% by weight.

The actinic ray-curable composition usually contains a polymerization initiator which generates radicals by actinic radiation such as ultraviolet rays. Examples of commonly used polymerization initiators include, for example, benzophenone, benzoin methyl ether, benzoin isopropyl ether, diethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,6-dimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenyl Phosphine oxide and the like. Preferably,
2,4,6-trimethylbenzoyldiphenylphosphine oxide or benzophenone is used. These polymerization initiators may be used alone or in combination of two or more. The polymerization initiator, for the polymerizable component,
Usually 0.01 to 1% by weight, preferably 0.02 to 0.3%
It is used so as to be% by weight. If the amount of the polymerization initiator is too large, the polymerization proceeds rapidly, and often gives a resin sheet having a large retardation value.

The active light-curable composition may further contain conventional additives such as antioxidants, ultraviolet absorbers, dyes and pigments, and fillers. Preparation of the resin sheet from the actinic ray-curable composition can be performed according to a conventional method. Usually, the actinic ray-curable composition is injected into a mold having a flat cavity formed by facing two flat plates, at least one surface of which can transmit active energy rays, and the active energy rays are irradiated to polymerize the composition. It should be done. The depth of the cavity may be equal to the thickness required for the resin sheet. Usually 150 to 3000 μm, especially 200 to 20
00 μm. The mold is preferably made of polished glass which has sufficient permeability to active energy rays, is hardly thermally deformed, and gives a resin sheet having good surface properties, but is preferably made of an acrylic plate, etc. You can also.
It is also preferable that the mold is subjected to a process of applying a release agent or depositing a release layer to facilitate the removal of the formed resin sheet from the mold.

As the active energy rays to be irradiated, ultraviolet rays, particularly, ultraviolet rays of 200 to 400 nm are used. The irradiation amount may be appropriately adjusted according to the type of the polymerizable component in the curable composition and the type and amount of the polymerization initiator. Further, thermal polymerization may be used in combination to quickly complete the curing. In this case, the curable composition is heated to 30 to 300 ° C. simultaneously with the irradiation of the actinic ray. Further, a thermal polymerization initiator such as benzoyl peroxide, diisopropyl peroxy carbonate, t-butyl peroxy (2-ethylhexanoate) may be added to the actinic ray-curable composition. The amount is 1% by weight based on the polymerization component
The following is preferable, and when the amount of use is too large, the retardation value of the generated resin sheet increases.

Further, the resin sheet generated by the irradiation of the active energy ray can be heated to complete the polymerization reaction and reduce internal strain generated during the polymerization. The heating temperature is appropriately selected depending on the composition of the curable composition and the glass transition temperature of the formed resin sheet, but is usually preferably around the glass transition temperature or lower. In the present invention, when the crosslinked resin sheet obtained by polymerizing the liquid actinic ray-curable composition in the form of a sheet into a sheet as described above and cutting the sheet into a desired shape, a machine such as scissors, a cutter such as a cutter or a saw is used. Instead of cutting, it is cut by irradiating a laser beam. As the laser, a gas laser, particularly a carbon dioxide gas laser, is usually used. The laser light is focused at a high density by a condensing lens and irradiated by a conventional method. It is preferable that the laser light is continuously oscillated. When pulse oscillation occurs, the cut portion may be roughened. In addition, an inert gas is blown to the irradiation point simultaneously with the irradiation of the laser beam, so that the danger that sublimates generated at the time of cutting adhere to the resin sheet or the resin sheet is damaged by heat can be reduced. The output of the laser may be appropriately selected in consideration of the thickness of the resin sheet, a desired cutting speed, thermal damage of the cut portion, and the like. Also, JP-A-6-1708
A protective film may be formed on a resin sheet as disclosed in JP-A-22.

[0031]

The present invention will be described more specifically with reference to the following examples. In addition, whether cracks occurred in the cut part,
Also, whether or not chipping occurred at the time of cutting was visually determined.

Production of resin sheet (A): A pair of polished glass plates (310 × 410 × 5 mm) were sandwiched by a width of 5 m.
m, a silicone rubber having a thickness of 1 mm was sandwiched therebetween, and an adhesive tape was wrapped therearound to form a sealing mold.
Bis (oxymethyl) tricyclo [5.2.1.
0 ^2.6 ] decane dimethacrylate 94 parts by weight, pentaerythritol tetrakis (β-thiopropionate) 6
Parts by weight, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF: Luciline TPO)
0.06 parts by weight of benzophenone and 0.04 parts by weight of benzophenone were mixed, stirred to obtain a uniform composition, and then defoamed to prepare a photopolymerizable composition. This photopolymerizable composition was poured into the above mold. A metal halide lamp with an output of 80 w / cm is placed above and below the mold at a distance of 400 mm from the glass surface,
The photopolymerizable composition was cured by irradiating with ultraviolet rays for 30 minutes. The size of the obtained resin sheet (A) is 300 × 4
It was 00 × 1.0 mm.

Production of the resin sheet (B): The resin sheet (B) was produced in exactly the same manner as the production of the resin sheet (A) except that silicone rubber having a width of 5 mm and a thickness of 0.3 mm was used for forming the mold. ) (300 × 400 × 0.3 mm).

Example 1 Using a carbon dioxide laser (RF-excited carbon dioxide laser manufactured by Thinrad, USA, output 25 W), a resin sheet (A) was linearly cut at an output of 25 W and a cutting speed of 200 mm / sec so that the cutting distance became 200 mm. Cut into pieces. No cracking or chipping occurred in the resin sheet.

Example 2 A resin sheet was cut in exactly the same manner as in Example 1 except that the resin sheet (B) was used instead of the resin sheet (A). No cracking or chipping occurred in the resin sheet. Example 3 A resin sheet (A) was linearly formed with a carbon dioxide laser (RF-excited carbon dioxide laser manufactured by Mitsubishi Electric Corporation, output 3 kW) at an output of 1000 W and a cutting speed of 200 mm / sec so that the cutting distance became 200 mm. Cut. No cracking or chipping occurred in the resin sheet.

Example 4 A resin sheet (A) was produced using a carbon dioxide impact laser (IMPACT L500, manufactured by Sumitomo Heavy Industries, Ltd.) at an output of 75 W and a frequency of 1 so that the cutting distance was 200 mm.
Cutting was performed linearly at 50 Hz and a cutting speed of 400 mm / min. No cracking or chipping occurred in the resin sheet.

Comparative Example 1 The resin sheet (A) was cut using an NT cutter with a cutting length of 100.
mm, cracks occurred in the resin sheet. Comparative Example 2 When the resin sheet (A) was cut at a cutting length of 100 mm using scissors, cracks occurred in the resin sheet.

Comparative Example 3 The resin sheet (A) was cut with a cutting length of 100 mm using a dicing apparatus used for cutting a silicon wafer or the like. No cracking or chipping occurred in the resin sheet,
Cutting required 10 minutes.

Claims (6)

[Claims] 1. A method of cutting a crosslinked resin sheet obtained by irradiating a laser beam onto a crosslinked resin sheet obtained by polymerizing a liquid actinic ray-curable composition mainly composed of a crosslinkable component into a sheet and polymerizing the same. A method for cutting a crosslinked resin sheet. 2. The method for cutting a crosslinkable resin sheet according to claim 1, wherein the polymerizable component mainly comprises bis (meth) acrylate. 3. The method for cutting a crosslinkable resin sheet according to claim 1, wherein the main component of the polymerizable component is bis (meth) acrylate selected from the formulas (1) and (2). Embedded image (Wherein, R ¹ and R ² each independently represent hydrogen or a methyl group. R ³ and R ⁴ each independently represent
C _{1 to} C ₆ hydrocarbon groups which may contain etheric oxygen or thioetheric sulfur. X represents a halogen atom or a C ₁ -C ₆ alkyl group or an alkoxy group. n shows 0 or the integer of 1-4. However, when n is an integer of 2 or more, a plurality of Xs may be different from each other. (In the formula, R ⁵ and R ⁶ each independently represent hydrogen or a methyl group. P represents 1 or 2, and q represents 0 or 1.) 4. The actinic ray-curable composition is represented by the formula (1):
Polymerization of bis (meth) acrylate selected from formula (2)
25% by weight or less based on the polymerizable component
Mel selected from the following formulas (3), (4) and (5)
4. The composition according to claim 3, further comprising a capto compound.
The method for cutting a crosslinkable resin sheet according to the above. Embedded image(Wherein multiple R⁷May be different from each other
Shows a methylene group or an ethylene group. R⁸Is an etheric acid
C which may contain sulfur and / or thioetheric sulfur
_Two~ C_FifteenRepresents a hydrocarbon group. a represents an integer of 2 to 6
)(Wherein Y may be different from each other and HS- (CH_Two)
_b-(CO)-(OCH _Two-CH_Two)_c− (CH_Two)_d
Indicates-. Here, b is an integer of 1 to 4, and c is an integer of 1 to 4.
And d represents an integer of 0 to 2).(Where R⁹And R^TenAre each independently C₁~ C_Threeof
Shows a hydrocarbon group. e and f are each independently 0 or
1 is shown. g represents 1 or 2) 5. The actinic ray-curable composition comprises 50 to 98% by weight of a polymerizable bis (meth) acrylate and 2 to 50% by weight of a soluble amorphous thermoplastic resin. The method for cutting a crosslinked resin sheet according to any one of claims 1 to 4. 6. The method for cutting a crosslinked resin sheet according to claim 1, wherein the laser is a carbon dioxide gas laser.