JP2009138111A - Injection molded product for optical use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molded product for optical use suitable for a fine optical lens having a small thickness. <P>SOLUTION: The thin optical molded product is produced by injection molding a polymer composition which contains a hydrogenated norbornene-based polymer having been prepared by ring-opening polymerizing a norbornene-based monomer composition, followed by hydrogenating, and a natural and/or synthetic wax, as molding materials. Fischer Tropsch Wax preferred as the wax. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical injection molded article having a very small thickness, such as a precision optical lens.

For exposure devices for semiconductors, endoscopes, recording / reproducing devices, display elements, etc., precision optical lenses that require precision processing are mounted. For image sensors that require miniaturization, the lens unit can be made smaller. A spherical lens or an aspherical lens having a very small thickness (ultra thin wall) is used. Due to the ease of precision processing, many resins are used for these lenses.
In particular, a precision optical lens that is required to be ultra-thin is required to have higher fluidity in order to improve moldability. For example, a norbornene monomer having an alkenyl group having a carbon-carbon double bond at a terminal thereof is 0.2 to 5 mol, and a norbornene monomer 100 having no alkenyl group having a carbon-carbon double bond at a terminal is used. It is known that when a norbornene-based polymer hydrogenated product obtained by ring-opening polymerization of a norbornene-based monomer composition containing a mole and then hydrogenating is used, even a thin Fresnel lens can ensure strength. (Patent Document 1).
In addition, with respect to lenses, for the purpose of improving transferability, a method using a polymer having a specific structure (Patent Documents 2 and 3); a method for adjusting a melt flow rate of a polymer (Patent Document 4), etc. are known. It has been.
In addition, as a method for increasing the fluidity by blending the third component with the polymer, blending a hydrocarbon resin having a weight average molecular weight of 2 × 10 ⁴ or less and solid at room temperature has been proposed (Patent Document 5). ing.
According to Patent Document 5, the hydrocarbon-based resin has a polystyrene-equivalent weight average molecular weight of 2 × 10 ⁴ or less, preferably 2 × 10 ^{4 to} 100, and is solid at room temperature. Examples, C ₅ resins, C ₉ resins, C ₅ based / C ₉ based mixed resin, cyclopentadiene resin, polymer-based resin of a vinyl-substituted aromatic compound, olefin / vinyl substituted aromatic compound Examples of the resin include a copolymer resin, a cyclopentadiene compound / vinyl-substituted aromatic compound copolymer resin, or a hydrogenated product of the resin. When a composition containing a copolymer resin of a pentadiene compound and a vinyl-substituted aromatic compound (softening point 100 ° C.) is press-molded and stretched in an oil bath, it has low birefringence and relatively high light transmittance. It has been shown that a 0.5 mm thick plate can be obtained.

JP 2007-262170 A JP-A-5-047034 JP 2000-075108 A JP 2000-219725 A JP-A-9-221577

  However, in order to obtain a spherical lens having a small thickness, the present inventors performed injection molding using the polymer described in the related art and the composition thereof. As a result, the polymer as in Patent Document 1 was used. Even in this case, it was found that even when the resin exemplified in Patent Document 5 was blended, the mold surface was not accurately transferred to the injection molded product (surface accuracy was low). Moreover, when the melt flow rate of a polymer was controlled like patent document 4, since the molecular weight of the polymer fell, it turned out that the intensity | strength of a molded object falls.

  Under such prior art, the present inventors have conducted extensive studies to obtain a molding material that is excellent in fluidity and can give a molding having high strength and excellent surface accuracy. It was found that when a norbornene-based polymer hydrogenated product obtained by ring-opening polymerization of a norbornene-based monomer composition and then hydrogenated is blended with a wax, these requirements are satisfied, and the present invention is completed. It was.

Thus, according to the present invention, a polymer composition comprising a norbornene-based polymer hydrogenated product obtained by ring-opening polymerization of a norbornene-based monomer composition and then hydrogenating, and a natural wax and / or a synthetic wax. An optical injection-molded body made of an article is provided.
The natural wax and / or synthetic wax is preferably a compound having a melting point of 25 to 100 ° C.
In addition, the compound having a melting point of 25 to 100 ° C. is preferably a synthetic wax, and in particular, the synthetic wax is preferably a hydrocarbon wax, and is a Fischer-Tropsch wax among hydrocarbon waxes. It is preferable.

  The optical injection molded article of the present invention contains a norbornene-based polymer hydrogenated product obtained by subjecting a norbornene-based monomer composition to ring-opening polymerization and then hydrogenation, and a natural wax and / or a synthetic wax. It can be obtained by injection molding a polymer composition.

  In the present invention, a norbornene polymer hydrogenated product obtained by ring-opening polymerization of a norbornene monomer composition and then hydrogenating (hereinafter simply referred to as a norbornene polymer hydrogenated product) contains a norbornene skeleton. A condensed ring compound is obtained by ring-opening polymerization and then hydrogenated.

Examples of norbornene monomers used in the present invention include bicyclo [2.2.1] hept-2-ene (common name: norbornene) and its derivatives (having a substituent in the ring), and tricyclo [4.3. 0 ^1,6 . 1 ^2,5 ] deca-3,7-diene (common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name: methano) Tetrahydrofluorene: 1,4-methano-1,4,4a, 9a-tetrahydrofluorene), tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene (common name: tetracyclododecene), 8-methoxycarbonyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-methyl-8-methoxycarbonyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-ethylidene-tetracyclo [4.4.0.1 ^2,5 . ^{17, 10} ] dodec-3-ene, 5-vinyl-bicyclo [2.2.1] hept-2-ene, 5-allyl-bicyclo [2.2.1] hept-2-ene, 5-vinyl Oxycarbonyl-bicyclo [2.2.1] hept-2-ene, 8-vinyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-allyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-vinyloxycarbonyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene and the like. These norbornene monomers can be used alone or in combination of two or more.

  In the present invention, in addition to these monomers, other monomers copolymerizable with these monomers include, for example, monocyclic cyclic olefin monomers such as cyclohexene, cycloheptene, and cyclooctene. Can be used in combination. The other monomers are used in a proportion of generally 10 mol% or less, preferably 5 mol% or less, more preferably 1 mol% or less in all polymerizable monomers.

These monomers become ring-opening polymers by polymerizing in an arbitrary solvent such as toluene or cyclohexane in the presence of a known ring-opening polymerization catalyst. Examples of the ring-opening polymerization catalyst include a catalyst comprising a metal halide such as ruthenium or osmium, a nitrate or an acetylacetone compound, and a reducing agent, or a metal halide or acetylacetone such as titanium, zirconium, tungsten, or molybdenum. A catalyst comprising a compound and an organoaluminum compound can be used.
According to a conventional method, a known hydrogenation catalyst containing a transition metal such as nickel or palladium is added to this ring-opening polymer polymerization solution, and the carbon-carbon unsaturated bond is hydrogenated under a hydrogen atmosphere. A norbornene-based polymer used in the invention can be obtained.
The resulting hydrogenated product preferably has a high hydrogenation rate, usually 90% or more, more preferably 95% or more, and particularly preferably 99% or more. Here, the hydrogenation rate is a value calculated based on the number of moles of the aliphatic carbon-carbon double bond.
There are no particular restrictions on the conditions such as temperature and time of the ring-opening polymerization reaction and hydrogenation reaction, and general reaction conditions for producing a ring-opening polymer of norbornene monomer and its hydrogenated product Should be adopted.

The weight average molecular weight of the norbornene-based polymer used in the present invention is usually 20000 to 45000, preferably 25000 to 35000.
The norbornene-based polymer has a melt flow rate at 280 ° C. and a load of 2.16 Kgf of usually 5 g / 10 min or more, preferably 10 g / 10 min to 150 g / 10 min, more preferably 20 g / 10 min to 140 g / 10 min. is there. The melt flow rate is measured according to JIS K 6719.

  The norbornene polymer is not limited by its glass transition temperature, but considering the moldability of the molded product, the lower limit is usually 80 ° C., preferably 100 ° C., more preferably 110 ° C., and the upper limit is usually 250 ° C. Preferably it is 200 degreeC.

The natural wax or synthetic wax (hereinafter simply referred to as wax) used in the present invention has an oily substance having a high melting point indicating an ester of a higher fatty acid and a monohydric or dihydric higher alcohol, or a property similar to this. These are neutral fats, higher fatty acids, hydrocarbons and the like. Usually, it is a soft and smooth solid at room temperature, its melting point is usually 25 to 120 ° C., and the gas burns well. Specifically, waxes obtained from animals, plants, and minerals, petroleum waxes (paraffin wax, microcrystalline wax, solid hydrocarbons at room temperature, mainly composed of hydrocarbons extracted during the distillation of crude oil) Or petrolatum), hydrocarbon wax synthesized by Fischer-Tropsch method (Fischer-Tropsch wax), and polyalkylene wax. Among these, hydrocarbon waxes represented by C _n H _{2n + 2} , such as petroleum waxes, Fischer-Tropsch waxes, and polyalkylene waxes, are more preferable because of the high transparency of the obtained molded products. Is Fischer-Tropsch wax. The hydrocarbon wax contains 95% by weight or more of a linear or branched saturated hydrocarbon.

  The mixing ratio of the norbornene polymer hydrogenated product and the wax is such that the wax is usually 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight based on 100 parts by weight of the norbornene polymer hydrogenated product. Preferably it is 1-10 weight part. If the ratio of the wax is too large, the transparency of the resulting molded product is lowered and the strength of the molded product is lowered, which is not preferable. When the ratio of the wax is too small, the thin moldability is lowered, and the precision of the surface of the mold and the molded body tends to be different, which is not preferable.

  In the present invention, an antioxidant, a colorant, an optical brightener, a dispersant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, a lubricant, a solvent, etc. are added to the polymerizable composition. An agent can be appropriately blended.

The optical injection-molded article of the present invention is injection-molded using a polymer composition comprising the above-mentioned wax and a norbornene-based polymer hydrogenated product with additives as necessary.
In the injection molding method, the molding material is usually put into a hopper of an injection molding machine, sent to a cylinder with a screw set at a rotation speed so that the molding material is uniformly mixed, and then injected into a mold. It is a method to do. The temperature of the cylinder is appropriately selected in the range of usually 150 to 400 ° C, preferably 200 to 350 ° C, more preferably 230 to 330 ° C. If the cylinder temperature is too low, fluidity will deteriorate, causing shrinkage and distortion in the molded product, and if the cylinder temperature is excessively high, silver streaks will occur due to thermal decomposition of the resin, or the molded product will turn yellow. Defects may occur.
When the injection speed from the cylinder to the mold is usually 1 to 500 mm / second, it is excellent in appearance and suitable.
The injection pressure from the cylinder to the mold is usually in the range of 50 to 5000 kgf / cm ² . The injection pressure at this time may be appropriately selected and set in consideration of conditions such as mold design and fluidity of the molding material used.

The holding pressure is a pressure applied for a certain period of time until the molten resin at the gate portion of the mold is completely cooled and solidified after the mold is substantially filled with the injection pressure. The upper limit of the holding pressure is generally set within the range of the clamping pressure of the mold, but is usually set within a range of 2000 kgf / cm ² or less, preferably 1700 kgf / cm ² or less, more preferably 1500 kgf / cm ² or less. The By setting the upper limit value of the holding pressure in such a range, there is no possibility that molding defects such as distortion occur in the molded body. The lower limit of the holding pressure is set in a range of at least 50 kgf / cm ² or more, preferably 100 kgf / cm ² or more, more preferably 150 kgf / cm ² or more. By setting the lower limit value of the holding pressure in such a range, the occurrence of sink marks in the molded body can be prevented, the molding shrinkage rate can be reduced, and a product with excellent dimensional accuracy can be obtained.

The mold temperature t ₀ ° C at this time is usually room temperature <t ₀ <(t ₁ +15) ° C., preferably (t ₁ −30) <t ₀ <(, assuming that the glass transition temperature of the resin is t ₁ ° C. It is performed at t ₁ +10) ° C., more preferably at (t ₁ −20) <t ₀ <(t ₁ +5) ° C. _(However, (t 1 -30) <room temperature, or _(t 1 -20) ℃ <If it is room temperature, and room temperature _{<t 0} ℃.) Resin temperature during molding, the mold temperature is within this range And it is excellent in mold release property and can suppress the distortion of a molded object low.

  In addition, for the purpose of reducing the color tone deterioration of the molded body and the generation of oxides and voids as much as possible, preliminary drying of the molding material is performed, or nitrogen or the like is flowed from the hopper portion of the injection molding machine to replace with air. preferable. The method of preliminary drying is not limited, and for example, it is performed by vacuum drying at a temperature 5 to 50 ° C. lower than the glass transition temperature for 4 to 12 hours.

  The optical injection molded article of the present invention is a precision optical lens such as a thin optical lens composed of, for example, a spherical lens or an aspheric lens, or an optical lens having fine irregularities such as a Fresnel lens, a lenticular lens, a prism sheet, or a lens array And is particularly suitable for a spherical lens. In particular, a remarkable effect can be obtained in the case of a thin molded lens having a thickness of the thinnest part of less than 400 μm, particularly 150 to 300 μm.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following, parts and% are based on weight unless otherwise specified.

(1) Weight average molecular weight (Mw), number average molecular weight (Mn)
Mw and Mn were measured at 40 ° C. as standard polyisoprene conversion values by gel permeation chromatography (GPC) using cyclohexane as an eluent.
As a measuring apparatus, HLC8120GPC manufactured by Tosoh Corporation was used.
As the standard polyisoprene, ten standard polyisoprenes manufactured by Tosoh Corporation, Mw = 602, 1390, 3920, 8050, 13800, 22700, 58800, 71300, 109000 and 280000 were used.
The sample was prepared by heating and dissolving the measurement sample in cyclohexane at 40 ° C. so that the sample concentration was 4 mg / ml.
The measurement was performed using three TSKgel G5000HXL, TSKgel G4000HXL, and TSKgel G2000HXL columns connected in series as columns, using a flow rate of 1.0 ml / min, a sample injection amount of 100 μml, and a column temperature of 40 ° C.
(2) Glass transition temperature (Tg)
It measured based on JISK6911 using the differential scanning calorimeter.
(3) Hydrogenation rate It measured by < ¹ > H-NMR spectrum using the mixed solution (1/1 weight ratio) of deuterated chloroform / carbon tetrachloride as a solvent.
(4) Melting point It measured with the differential scanning calorimeter with the heating rate of 20 degree-C / min, and took the maximum value of the melting curve.
(5) Softening point Measured based on JIS K 5903.
(6) Thin-wall formability Thin-wall formability includes a convex curvature radius of 5.73 mm, a concave curvature radius of 3.01 mm, a size of 4.5 mm, a lens portion diameter of 3 mm, and a lens center thickness of 0. Using a mold that forms a 2 mm lens, create a molded product by injection molding, and center the resulting molded product with a non-contact three-dimensional measuring instrument (manufactured by Mitaka Koki Co., Ltd .; product name “NH-3SP”) In the range of 2 mm in diameter, the surface shape of the convex and concave surfaces was measured, and the radius of curvature of the molded product was measured. The PV value (μm) was determined from the curvature radius of the molded product and the curvature radius of the mold design value. The smaller the PV value, the better the mold transferability.
(7) Transparency Haze was measured using a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) by molding a molded product having a thickness of 1 mm and a length and width of 65 mm by injection molding. It shows that transparency is so favorable that haze (%) is small.

[Production Example 1]
<Synthesis of ring-opening polymer hydrogenated product>
To a reactor substituted with nitrogen, 7 parts of methanotetrafluorene (hereinafter referred to as “MTF”) (1% by weight based on the total amount of monomers used for polymerization), 1070 parts of cyclohexane and 530 parts of toluene were added, and tri-i- 0.55 part of butylaluminum and 0.21 part of isobutyl alcohol, 0.84 part of diisopropyl ether as a reaction regulator, and 4.86 parts of 1-hexene as a molecular weight regulator were added. To this, 24.1 parts of a 0.65% tungsten hexachloride solution dissolved in cyclohexane was added and stirred at 55 ° C. for 10 minutes. Next, 693 parts of MTF and 48.9 parts of a 0.65% tungsten hexachloride solution dissolved in cyclohexane were continuously added dropwise to the system over 150 minutes while maintaining the reaction system at 55 ° C. Thereafter, the reaction was continued for 30 minutes to complete the polymerization.
The obtained ring-opening polymerization reaction liquid was transferred to a pressure resistant hydrogenation reactor, and 56 parts of diatomaceous earth-supported nickel catalyst (manufactured by JGC Chemicals, product name “T8400RL”, nickel support rate 57%) and 167 parts of cyclohexane were added. In addition, the reaction was carried out at 180 ° C. and a hydrogen pressure of 4.6 MPa for 8 hours. The reaction solution was filtered under pressure with Radiolite # 500 as a filter bed at a pressure of 0.25 MPa (Ishikawajima-Harima Heavy Industries Co., Ltd., product name “Funda filter”) to remove the hydrogenation catalyst, and a colorless transparent solution was obtained. Obtained. Subsequently, 0.5 parts of antioxidant per 100 parts of the hydrogenated product: pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (manufactured by Ciba Specialty Chemicals, The product name “Irganox 1010”) was added to the resulting solution and dissolved. Next, it is sequentially filtered through a Zeta Plus filter 30H (Cuneau filter, pore size 0.5 to 1 μm), and further filtered through another metal fiber filter (pore size 0.4 μm, manufactured by Nichidai Corp.). Minutes removed. The hydrogen conversion rate of the ring-opening polymer hydrogenated product was 99.9%.
Next, using a cylindrical concentrator / dryer (manufactured by Hitachi, Ltd.), at a temperature of 270 ° C. and a pressure of 1 kPa or less, cyclohexane and other volatile components as solvents are removed from the solution and directly connected to a concentrator. The resulting die was extruded into a strand shape in a molten state, and pellets A were obtained after cooling. Tg was 158 ° C. The pellet A thus obtained had a weight average molecular weight (Mw) of 28,200 and a molecular weight distribution (Mw / Mn) of 2.12.
The polymerization conversion during the synthesis of the ring-opening polymer was 100%, and the hydrogen conversion was 99.9%, which was a high level.

[Example 1]
5 parts of Fischer-Tropsch wax “FNP0115” (product name; manufactured by Nippon Seiwa Co., Ltd .; melting point: 114 ° C.) were added to 100 parts of the ring-opened polymer hydrogenated product of Production Example 1, and a twin-screw extruder (Toshiba Machine Co., Ltd.). Manufactured; product name “TEM-35B”, screw diameter 37 mm, L / D = 32, screw rotation speed 250 rpm, resin temperature 270 ° C., feed rate 10 kg / hour), kneaded and extruded to form pellets.
This pellet is used to form a concave meniscus lens having a convex curvature radius of 5.73 mm, a concave curvature radius of 3.01 mm, a size of 4.5 mm, a lens portion diameter of 3 mm, and a lens center thickness of 0.2 mm. using a mold to a cylinder temperature of 290 ° C., mold temperature 125 ° C., injection speed 10 mm / sec, the holding pressure 300 kgf / cm ^2, and injection molded under the conditions of a back pressure 50 kgf / cm ^2, to obtain a lens. The thin-wall formability of the obtained lens and the transparency of the obtained resin were evaluated. The results are shown in Table 1.

[Example 2]
A lens was molded in the same manner as in Example 1 except that the amount of the Fischer-Tropsch wax “FNP0115” was changed to 10 parts and the mold temperature was changed to 110 ° C., and the thin-wall forming property and the transparency of the obtained resin were evaluated. The results are shown in Table 1.

[Example 3]
The lens was molded in the same manner as in Example 1 except that “Paraflint H1-N4” (product name; manufactured by Sazol Wax; melting point: 94 ° C.) was changed to 5 parts as the Fischer-Tropsch wax. And the transparency of the obtained resin was evaluated. The results are shown in Table 1.

[Comparative Example 1]
According to the method described in Example 1 of JP-A-2007-262170, pellets containing a norbornene polymer hydrogenated product (Mw 16,600, Mw / Mn = 2.2) and an antioxidant were obtained. A lens was molded in the same manner as in Example 1 except that this pellet was used, and the thin-wall formability and the transparency of the obtained resin were evaluated. The results are shown in Table 1.
[Comparative Example 2]
Instead of Fischer-Tropsch wax, petroleum resin “Imabe P-100” (product name; manufactured by Idemitsu Petrochemical Co., Ltd .; complete hydrogenation of dicyclopentadiene-styrene (50:50) random copolymer; average molecular weight 650, softening A lens was molded in the same manner as in Example 1 except that the point 100 ° C. was used, and the thin-wall formability and the transparency of the obtained resin were evaluated. The results are shown in Table 1.
[Comparative Example 3]
Instead of Fischer-Tropsch wax, petroleum resin “Imabe P-90” (product name; manufactured by Idemitsu Petrochemical Co., Ltd .; complete hydrogenation of dicyclopentadiene-styrene (50:50) random copolymer; average molecular weight 590, softening) A lens was molded in the same manner as in Example 1 except that the point 90 ° C. was used, and thin-wall formability and transparency of the obtained resin were evaluated. The results are shown in Table 1.
[Comparative Example 4]
Instead of Fischer-Tropsch wax, petroleum resin "Arkon P140" except for using (product name; manufactured by Arakawa Chemical Industries, Ltd. C ₉ based hydrogenated petroleum resin, softening point 140 ° C.), the lens in the same manner as in Example 1 Molding was conducted to evaluate the thin-wall formability and the transparency of the obtained resin. The results are shown in Table 1.

  From this result, it can be seen that when the wax is not used (Comparative Example 1), or when the hydrogenated petroleum resin is used instead of the wax (Comparative Examples 2 to 4), the thin-wall formability is reduced. Further, even when the same wax is used, it can be seen that as the amount of wax increases, haze tends to increase (transparency decreases).

Claims (5)

Optical injection molding comprising a polymer composition containing a norbornene polymer hydrogenated product obtained by ring-opening polymerization of a norbornene monomer composition and then hydrogenated, and a natural wax and / or a synthetic wax. body. The optical injection-molded article according to claim 1, wherein the natural wax and / or the synthetic wax is a compound having a melting point of 25 to 120 ° C. The optical injection-molded article according to claim 2, wherein the compound having a melting point of 25 to 120 ° C is a hydrocarbon wax. The optical injection molded article according to claim 3, wherein the hydrocarbon wax is petroleum wax or Fischer-Tropsch wax. The optical injection-molded article according to claim 4, wherein the hydrocarbon wax is a compound represented by C _n H _{2n + 2} .