JP2003311773A - Optical part and its molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly accurate optical part, which is obtained by injection molding and has at least one effective curved surface. <P>SOLUTION: In the optical part, which is obtained by injection molding and has at least one effective curved surface, the part is mainly made of a cyclic olefin based copolymer and does not have a non-transfer region having a size larger than 10 μm on the effective curved surface. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical component. It also relates to a method of molding the optical component.

[0002]

2. Description of the Related Art Conventionally, transparent plastic materials such as poly (methyl methacrylate) and cyclic olefin polymers, which are lightweight and have excellent moldability, have been used for optical parts. In particular, a cyclic olefin polymer is a resin having a small birefringence and a low water absorption rate, and has recently attracted attention as a material for high precision optical parts such as lenses.

For example, the toric lens introduced in Japanese Patent Laid-Open No. 2001-074915 has a resin containing 2 to 20 carbon atoms.
An α-olefin / cyclic olefin random copolymer derived from 20 α-olefins and a cyclic olefin having a specific structure is said to be preferable.

On the other hand, an optical component having a highly accurate curved surface is required in order to achieve high definition in a laser printer image forming system and to improve storage density in an optical disc pickup optical system. However, conventionally, when a cyclic olefin-based copolymer of this kind is used, the transfer of a curved surface tends to become poor.

In order to improve the transfer, there are known methods of raising the temperature of the resin and lowering the melt viscosity of the resin itself to lower the molecular weight. In this case, however, these methods are not effective. This has been an obstacle to obtaining high-precision optical components.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly accurate optical component obtained by injection molding and having at least one effective curved surface.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the problems, and as a result, an optical component having at least one effective curved surface obtained by injection molding has a cyclic olefin copolymer as a main component. Consists of, and
By not having a non-transfer area having a size of 10 μm or more on the effective curved surface, and more preferably, the molding conditions during the injection molding satisfy specific molding conditions,
The inventors have found that the problem can be solved and completed the present invention.

That is, the present invention comprises the following 1 to 4. 1. An optical component having at least one effective curved surface obtained by injection molding is composed of a cyclic olefin-based copolymer as a main component and has no non-transfer region having a size of 10 μm or more on the effective curved surface. Optical components to do. 21. The optical component according to item 1, wherein the cyclic olefin-based copolymer according to item 1 is an ethylene / tetracyclododecene random copolymer. 3 The molding conditions for injection molding are as follows: [1] to [3]; 4.5 ≤ logTW ≤ 6.5 [1] T + 90 ≤ t ¹ ≤ T + 180 [2] T-50 ≤ t ² ≤ T [ 3] (However, in the formula, TW is the apparent shear stress [Pa] of the resin at the narrowest part in the resin flow path, and t ¹ is the actual temperature of the resin during the injection operation [° C]
And t ² satisfy the actual temperature [° C.] of the mold during the mold opening operation, and T the Tg [° C.] of the resin composition as the raw material). Method for molding optical components. 43. The optical component according to item 1 or 2, which is obtained by the molding method according to item 43.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The optical component of the present invention and the method for manufacturing the same will be specifically described below. (Optical component) The optical component in the present invention is a component characterized by transmitting light of one or more specific wavelengths and / or continuous wavelengths. Various effects can be given to the optical component by the surface shape and treatment.

(Effective Curved Surface) The optical component of the present invention has at least one curved surface. Therefore, this component alone or in combination with other components is provided with a function of converging or diffusing light rays. I am planning.
Therefore, it is required that the region that transmits light in the actual use state and that is involved in the expression of the function has particularly high precision. This area is called an effective curved surface.

(Non-Transfer Area) The optical component of the present invention is an optical component characterized in that it has no non-transfer region having a size of 10 μm or more on the effective curved surface. The non-transfer region is a recessed region on the surface of the injection-molded product, which does not transfer the mold shape caused by the resin surface solidifying without touching the mold. The following (1) to ( 3) is not included. (1) Inconsistency with the mold shape due to the resin being released from the mold during cooling in the mold. (2) Scratches that are caused by removal from the mold or movement of the movable part of the mold. (3) Bubbles and the like left inside the molded product along with the flow of the resin. Further, in the present invention, the size of the non-transfer area indicates the diameter when the size of each area is approximated to a circle, and this means that general equipment such as a non-contact surface shape measuring device and a stereoscopic microscope is used. It is possible to measure it by observing the surface shape using it.

(Structure of Cyclic Olefin Copolymer) The optical component of the present invention is an optical component characterized by comprising a cyclic olefin copolymer as a main component. The cyclic olefin-based copolymer means the following formula (1);

[0013]

[Chemical 1]

(Wherein R ¹ is one or more divalent groups selected from a hydrocarbon group having 2 to 20 carbon atoms, and R ² is
One or more monovalent groups selected from the group consisting of hydrogen and hydrocarbon groups having 1 to 5 carbon atoms, x and y represent a copolymerization ratio, x / y is 5/95 or more, 95 / It is a real number that is 5 or less. ) Shows the copolymer represented by.

In the above formula (1), R ¹ is preferably one or more divalent groups selected from a hydrocarbon group having 2 to 12 carbon atoms, and more preferably
Formula (2) below;

[0016]

[Chemical 2] (In the formula, p is an integer of 0 to 2.) A divalent group represented by the formula, and most preferably p in the formula (2).
Is a divalent group in which 1 is 1. Further, in the above formula (1), R ² is preferably hydrogen and / or —CH ₃ , and most preferably hydrogen.

Further, the type of copolymerization is not limited in the present invention, and various known copolymerization types such as random copolymers, block copolymers and alternating copolymerization can be applied, but random copolymerization is preferable. It is a copolymer. Specifically, ethylene / tetracyclododecene random copolymer and ethylene / norbornene random copolymer are preferred copolymers.

(Other structures that can be used as a part of the main chain) The cyclic olefin copolymer used in the present invention is, if necessary, within a range that does not impair the good physical properties of the optical component of the present invention. And may have a repeating structural unit derived from another copolymerizable monomer. The copolymerization ratio is not limited, but is preferably 20 mol% or less, more preferably 10 mol% or less, and when copolymerization is further performed, the optical properties may be impaired and a highly accurate optical component may not be obtained. is there. The type of copolymerization is not limited, but a random copolymer is preferable.

(Molecular Weight of Cyclic Olefin Copolymer) The molecular weight of the cyclic olefin copolymer used in the optical component of the present invention is not limited, but preferably 13
The intrinsic viscosity [η] measured in decalin at 5 ° C is 0.
03 to 10 dl / g, more preferably 0.05 to 5 d
1 / g, and most preferably 0.10 to 2 dl / g. If the molecular weight is higher than this range, it becomes difficult to obtain a highly accurate optical component with poor moldability, and if the molecular weight is lower than this range, the molded product becomes brittle,
It is difficult to use as an optical component.

(Copolymerization Ratio and Glass Transition Temperature of Cyclic Olefin Copolymer) The copolymerization ratio of the cyclic olefin copolymer used in the optical component of the present invention is x / y in the above general chemical formula (1). It is within the range of real numbers that are from 5/95 to 95/5. The range of x / y is preferably 10/90 or more,
90/10 or less. Even if x / y is higher than this range or lower than this range, the homogeneity of the molded product is deteriorated and the crystallinity is exhibited, so that the transparency is deteriorated, and realization of a highly accurate optical component cannot be expected.

The glass transition temperature (hereinafter referred to as Tg) is changed by changing the copolymerization ratio of the cyclic olefin copolymer. Therefore, the copolymerization ratio is more preferably
To make Tg suitable for molding, post-treatment and use of optical parts,
It should be determined depending on the main chain structure and the use. Tg is preferably 70 ° C. or higher, more preferably 7
0 to 250 ° C, most preferably 100 to 200 ° C
Is.

When a copolymerization ratio having a Tg higher than this range is selected, moldability becomes poor and it becomes difficult to obtain a highly accurate optical component, and a copolymerization ratio having a Tg lower than this range is selected. In this case, the molded product becomes vulnerable to heat and is difficult to use as an optical component. The Tg can be measured by a generally known method such as DSC and viscoelasticity measurement. The copolymerization ratio can be measured by a known method by NMR.

(Production Method of Cyclic Olefin Copolymer)
The method for producing the cyclic olefin-based copolymer used in the optical component of the present invention is not limited and can be produced by a known method. For example, there may be mentioned a method in which this copolymerization is carried out in a hydrocarbon solvent and a catalyst formed from a vanadium compound and an organoaluminum compound soluble in the hydrocarbon solvent is used as the catalyst.

(Modification of Cyclic Olefin Copolymer) This cyclic olefin copolymer is modified by various known methods such as graft modification within a range that does not impair the good physical properties of the optical component of the present invention. Can be used. In order to obtain a graft modified product from a cyclic olefin copolymer (raw material resin), conventionally known polymer modification methods can be widely applied. For example, a method of adding a modifier to a raw material resin in a molten state to carry out a graft polymerization (reaction), a method of adding a modifier to a solvent solution of the raw material resin and carrying out a graft reaction, and the like. Such a graft reaction is usually performed at a temperature of 60 to 350 ° C. The graft reaction can be carried out in the presence of a radical initiator such as an organic peroxide and an azo compound.

Examples of the modifier used here include unsaturated carboxylic acids, and specifically, (meth) acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid. , Isocrotonic acid, endocis bicyclo [2.2.1] hept-5-ene-2,3
-Unsaturated carboxylic acids such as dicarboxylic acids (Nadic acid TM), and derivatives of these unsaturated carboxylic acids such as unsaturated carboxylic acid anhydrides, unsaturated carboxylic acid halides, unsaturated carboxylic acid amides, unsaturated carboxylic acid imides, Examples thereof include saturated carboxylic acid ester compounds. Specific examples of the unsaturated carboxylic acid derivative include maleic anhydride, citraconic anhydride, maleyl chloride, maleimide, monomethyl maleate, dimethyl maleate, and glycidyl maleate. Among these, α, β-unsaturated dicarboxylic acids and α, β-unsaturated dicarboxylic acid anhydrides such as maleic acid, nadic acid and anhydrides of these acids are preferably used. These modifiers can be used alone or in combination of two or more.

The graft modified product obtained by these methods can be used as it is, but a modified product having a high modification ratio is prepared in advance, and then this modified product and the unmodified raw material resin are adjusted to a desired modification ratio. It can also be efficiently produced by mixing the above components.

(Cyclic Olefin Copolymer as Main Component) The main component of the optical component of the present invention is a cyclic olefin copolymer. The main component is not limited as long as the composition ratio does not impair the good physical properties of the optical component of the present invention, but 70% or more of a cyclic olefin-based copolymer is preferable. More preferably
It is 80% or more, and most preferably 90% or more. It is difficult to obtain an optical component having sufficient optical characteristics by using a small amount of a cyclic olefin-based copolymer that is out of this range. The substance used as a raw material other than the main component is not limited, but examples thereof include other resins and additives.

(Resin Composition) In the present invention, a resin composition obtained by further adding another resin to the above cyclic olefin copolymer may be used. Other resins are added within a range that does not impair the object of the present invention.

For example, the following (1) to (17). (1) A polymer derived from a hydrocarbon having one or two unsaturated bonds. Specifically, for example, polyethylene,
Polyolefins such as polypropylene, polymethylbutene-1, poly-4-methylpentene-1, polybutene-1 and polystyrene are mentioned. Note that these polyolefins may have a crosslinked structure. (2) A halogen-containing vinyl polymer. Specific examples thereof include polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polychloroprene, and chlorinated rubber. (3) Polymers derived from α, β-unsaturated acids and their derivatives. Specifically, polyacrylates, polymethacrylates, polyacrylamides, polyacrylonitriles, or copolymers with monomers constituting the above polymers, such as acrylonitrile / butadiene / styrene copolymers, acrylonitrile / styrene copolymers, acrylonitrile / Examples thereof include styrene / acrylic acid ester copolymers. (4) Polymers derived from unsaturated alcohols and amines, or acyl derivatives or acetals of unsaturated alcohols. Specifically, polyvinyl alcohol, polyvinyl acetate, polyvinyl thraphosphate, vinyl polybenzoate,
Examples thereof include vinyl polymaleate, polyvinyl butyral, polyallyl phthalate, polyallyl melamine, and copolymers with the monomers constituting the polymer, for example, ethylene / vinyl acetate copolymer. (5) Polymers derived from epoxides. Specific examples include polymers derived from polyethylene oxide or bisglycidyl ether. (6) Polyacetal. Specifically, polyoxymethylene,
Examples thereof include polyoxyethylene and polyoxymethylene containing ethylene oxide as a comonomer. (7) Polyphenylene oxide. (8) Polycarbonate. (9) Polysulfone. (10) Polyurethane and urea resins.

(11) Diamine and dicarboxylic acid and /
Or polyamides and copolyamides derived from aminocarboxylic acids, or the corresponding lactams. Specifically, nylon 6, nylon 66, nylon 11, nylon 1
2 and the like. (12) Polyesters derived from dicarboxylic acids and dialcohols and / or oxycarboxylic acids, or the corresponding lactones. Specific examples include polyethylene terephthalate, polybutylene terephthalate, poly 1,4-dimethylol cyclohexane terephthalate and the like. (13) A polymer having a crosslinked structure derived from aldehyde and phenol, urea or melamine. Specific examples include phenol / formaldehyde resin, urea / formaldehyde resin, melamine / formaldehyde resin and the like. (14) Alkyd resin. Specific examples include glycerin and phthalic acid resins. (15) An unsaturated polyester resin derived from a copolyester of a saturated or unsaturated dicarboxylic acid and a polyhydric alcohol and obtained by using a vinyl compound as a crosslinking agent, and a halogen-containing modified resin. (16) Natural polymer. Specifically, cellulose, rubber, protein, or derivatives thereof such as cellulose acetate,
Examples include cellulose propionate and cellulose ether. (17) Soft polymer. For example, a soft polymer containing a cyclic olefin component, an α-olefin copolymer, an α-olefin
Diene copolymer, aromatic vinyl hydrocarbon / conjugated diene soft copolymer, isobutylene or isobutylene
Examples thereof include soft polymers or copolymers of conjugated dienes.

(Additive) In addition to the above-mentioned components, the cyclic olefin-based copolymer used in the present invention further contains known weather stabilizers and heat-resistant stabilizers as long as the good characteristics of the optical component of the present invention are not impaired. Stabilizers, antistatic agents, flame retardants, slip agents, antiblocking agents, antifog agents, lubricants, dyes, pigments, natural oils, synthetic oils, waxes, organic or inorganic fillers and the like may be added.

For example, as an ultraviolet absorber of a weathering stabilizer to be added as an optional component, a benzophenone compound, a benzotriazole compound, a nickel compound,
There are hindered amine compounds, specifically, 2,2 ',
4,4'-Tetrahydroxybenzophenone, 2- (2'-hydroxy-3'-t-butyl-5'-butylphenyl) -5-chlorobenzotriazole and 2- (2'-hydroxy-3'-t- Butyl-5'-butylphenyl) benzotriazole, nickel salt of bis (3,5-di-t-butyl-4-hydroxybenzoylphosphoric acid ethyl ester, bis (2,2 ', 6,6'-tetra Methyl-4-piperidine) sebacate and the like.

Further, as a heat resistance stabilizer to be added as an optional component, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane,
β- (3,5-di-t-butyl-4-hydroxyphenyl) propionic acid alkyl ester, 2,2'-oxamide bis [ethyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) Phenolic antioxidants such as propionate, fatty acid metal salts such as zinc stearate, calcium stearate, calcium 1,2-hydroxystearate, glycerin monostearate, glycerin distearate, pentaerythritol monostearate, pentaerythritol distearate , Polyerythral alcohol fatty acid esters such as pentaerythritol tristearate, etc., and also distearyl pentaerythritol diphosphite, phenyl-4,4'-isopropylidene diphenol-pentaerythritol diphosphite, bis
A phosphorus-based stabilizer such as (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite or tris (2,4-di-t-butylphenyl) phosphite may be used. These may be blended alone or in combination. For example, tetrakis [methylene-3- (3.5-
Di-t-butyl-4-hydroxyphenyl) propionate]
Examples thereof include a combination of methane, zinc stearate and glycerin monostearate. These stabilizers can be used alone or in combination of two or more.

The method of mixing the cyclic olefin polymer used in the present invention with other resin components and additives is not limited, and known methods can be applied. For example, there is a method of mixing the respective components at the same time.

(Molding Method) The optical component of the present invention is obtained by injection molding. As the injection molding method, a known method can be applied, but preferably, the molding conditions at the time of injection molding are
This is a method that satisfies Expression [1] to Expression [3]. 4.5 ≤ logTW ≤ 6.5 [1] T + 90 ≤ t ¹ ≤ T + 180 [2] T-50 ≤ t ² ≤ T [3] (Each symbol in the formula is as described above) In formula [1], TW Shows the apparent shear stress [Pa] of the resin at the narrowest part in the resin flow path. The resin flow path refers to a resin flow path inside the mold, and the narrowing portion is usually a gate portion.

The apparent shear stress [Pa] can be calculated by a known method, but in practice it is preferable to select a calculation method that can be easily calculated depending on the molding machine, molding conditions, mold shape and the like. For example, when the gate has a cylindrical shape with a radius R [cm] and a length L [cm], the apparent shear stress [Pa] is the resin pressure at the time of injection P [Pa]
Then, it is represented by the formula [4]; TW = P · R / 2 · L [4], and, for example, the apparent shear rate at the time of injection calculated from the mold shape and the injection speed is DW [sec ⁻¹ ], And if the apparent melt viscosity separately measured under the conditions is VI [Pa · sec], it is represented by the formula [5]; TW = DW · VI [5]. Further, in the above formulas [2] and [3], T represents Tg [° C.] of the resin composition as a raw material. Tg is a glass transition temperature and can be measured by various known methods. In the case of the present invention, for example, by DSC, after raising the temperature to 250 ° C. under a temperature raising condition of 10 ° C./min. In nitrogen, the sample is rapidly cooled, and then in a temperature raising condition of 10 ° C./min. In nitrogen. Can be measured. Further, in the above formula [2], t ¹ represents the actual temperature [° C] of the resin during the injection operation, which can be easily measured by means such as injecting the resin into a thermometer outside the mold during the injection operation. To be done. Further, in the above formula [3], t ² represents the actual temperature [° C.] of the mold during the mold opening operation, and this can measure the temperature of the corresponding portion with a surface thermometer or the like.

It is more preferable that the molding conditions at the time of injection molding satisfy the formulas [1] 'to [3]'. 5 ≤ logTW ≤ 6.5 [1] 'T + 100 ≤ t ¹ ≤ T + 160 [2]' T-40 ≤ t ² ≤ T [3] '(Each symbol in the formula is as described above) Outside these ranges Under the molding conditions, it is difficult to obtain high-precision optical parts.

[0038]

EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

The physical property measuring methods in the examples are as follows. (1) Melt flow index (MFR) 260 ° C, load 2.16kg according to ASTM D1238
Measured by. (2) Glass transition temperature (Tg) After heating up to 250 ° C. in nitrogen at a temperature rising rate of 10 ° C./min. Using DSC-20 manufactured by SEIKO Denshi Kogyo Co., Ltd., the sample was once rapidly cooled and then Measured at a heating rate of 10 ° C / min.

[0040]

Examples 1 to 6 and Comparative Examples 1 to 5 Ethylene / tetracyclododecene random copolymers obtained using a Ziegler catalyst (tetracyclododecene unit content: 37 mol%,
MFR: 30g / 10 minutes, Tg: 130 ° C), injection molding machine (named machine M-70B) is used, and 10 lenses each having two effective curved surfaces under the molding conditions shown in Table 1 Molded.
The calculated values of the shear stress and the number of non-defective products of the obtained molded products are also shown in Table 1. The number of non-defective products is 10
The number of products that do not have a non-transfer area of 10 μm or more on the effective curved surface among the individual molded products. The observation was carried out over the entire effective curved surface using a stereoscopic microscope. Molding condition

[0041]

[Table 1]

In the table, TW is the apparent shear stress [Pa] of the resin in the narrowest part of the resin flow path, and t ¹ is the actual temperature of the resin during the injection operation.
[° C], and t ² indicates the actual temperature of the mold [° C] during the mold opening operation. In addition, the * mark indicates that the data is out of the range of the above formulas [1] to [3].

[0043]

According to the present invention, a highly accurate optical component having at least one effective curved surface can be obtained by injection molding.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B29L 11:00 B29L 11:00 F term (reference) 4F202 AA12 AH73 AR06 CA11 CB01 CN27 4F206 AA12E AH73 AR064 JA07 JM04 JP17 JQ81 4J100 AA02P AR09Q CA04 FA09 JA33

Claims (4)

[Claims] 1. An optical component having at least one effective curved surface obtained by injection molding is composed of a cyclic olefin-based copolymer as a main component and has an effective curved surface of 10 μm.
An optical component characterized by not having a non-transfer area larger than m. 2. The optical component according to claim 1, wherein the cyclic olefin-based copolymer according to claim 1 is an ethylene / tetracyclododecene random copolymer. 3. The molding conditions at the time of injection molding are expressed by formula [1] to formula.
[3]; 4.5 ≤ logTW ≤ 6.5 [1] T + 90 ≤ t ¹ ≤ T + 180 [2] T-50 ≤ t ² ≤ T [3] (However, in the formula, TW is the narrowest in the resin flow path. The apparent shear stress [Pa] of the resin in the part, t ¹ is the actual temperature of the resin during the injection operation [° C]
And t ² satisfy the actual temperature [° C.] of the mold during the mold opening operation, and T represents the Tg [° C.] of the resin composition as the raw material). A method for molding an optical component as described above. 4. The optical component according to claim 1, which is obtained by the molding method according to claim 3.