Resin composition and optical element

Abstract

Provided is a resin composition that suppresses the occurrence of molding defects such as wire drawing and enables the formation of an optical element having high transparency and low birefringence. The resin composition of the present invention contains an alicyclic structure-containing polymer and strontium carbonate powder, and the proportion of the above-mentioned strontium carbonate powder in the resin composition is 0.2 mass% or more and 1.0 mass% or less.

Description

Technical Field

[0001] This invention relates to resin compositions and optical elements. Background Technology

[0002] Optical components require optical properties such as transparency and birefringence, as well as excellent weather resistance such as moisture resistance and heat resistance. Materials used for such optical components include, for example, alicyclic polymers such as cyclic olefin polymers, polycarbonate, polyethylene terephthalate, and polyacrylate.

[0003] In recent years, various materials have been proposed to obtain optical components with superior optical properties. For example, Patent Document 1 proposes using an optical resin containing alkaline earth metal carbonate micropowder in order to adjust the birefringence of optical components such as films used in a bent state. According to Patent Document 1, alkaline earth metal carbonate micropowder is a birefringent powder, thus enabling control of the birefringence of optical components.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent document 1: Japanese Patent Application Publication No. 2021-47402. Summary of the Invention

[0007] The problem the invention aims to solve

[0008] Here, it is required that the resin composition used to form optical elements, such as lenses, exhibit high transparency and low birefringence when molded into optical elements.

[0009] Furthermore, it is required that when optical elements such as lenses can be formed by, for example, injection molding of a resin composition, such a resin composition can suppress the occurrence of molding defects such as stringing.

[0010] Therefore, the object of the present invention is to provide a resin composition that suppresses the occurrence of molding defects such as wire drawing and is capable of forming an optical element with high transparency and low birefringence, and an optical element formed by molding the resin composition.

[0011] Solution for solving the problem

[0012] The inventors conducted in-depth research with the aim of solving the above-mentioned problems. Then, the inventors made a new discovery that as long as the resin composition contains a polymer with an alicyclic structure and strontium carbonate powder in a certain proportion, the occurrence of molding defects such as fiber drawing can be suppressed, and optical elements with high transparency and low birefringence can be formed, thus completing the present invention.

[0013] The purpose of this invention is to solve the above problems. [1] The resin composition of this invention contains an alicyclic polymer and strontium carbonate powder, wherein the content of the strontium carbonate powder in the resin composition is 0.2% by mass or more and 1.0% by mass or less.

[0014] Such a resin composition suppresses molding defects such as fiber drawing and can form optical elements with high transparency and low birefringence.

[0015] [2] In the resin composition described in [1] above, the strontium carbonate powder preferably contains strontium carbonate nanoparticles and a surfactant attached to the surface of the strontium carbonate nanoparticles.

[0016] If it is strontium carbonate powder of this type, it can improve the dispersibility of strontium carbonate powder in the resin composition.

[0017] [3] The resin composition described in [1] or [2] above preferably has a melt flow rate of 40 g / 10 min or more, as determined by JIS K6719 at a temperature of 280 °C and a load of 21.18 N.

[0018] If the resin composition has a melt flow rate of 1 or higher than the aforementioned lower limit, the birefringence of the resulting optical element can be further reduced. Furthermore, if the resin composition has a melt flow rate of 1 or higher than the aforementioned lower limit, the generation of molding defects such as weld lines can be suppressed.

[0019] [4] In any of the resin compositions described in [1] to [3] above, the aspect ratio (ratio of average major diameter to average minor diameter) of the strontium carbonate powder is preferably 1.1 or more.

[0020] If the aspect ratio of the strontium carbonate powder is above the lower limit mentioned above, the birefringence of the resulting optical element can be effectively suppressed.

[0021] In addition, in this specification, the average major and minor axes of the strontium carbonate powder were determined by an automated image processing method using scanning electron microscope images of the strontium carbonate powder.

[0022] [5] In any of the resin compositions described in [1] to [4] above, the average diameter of the strontium carbonate powder is preferably 10 nm or more and 100 nm or less.

[0023] If the average diameter of the strontium carbonate powder is above the aforementioned lower limit, the reduction in the transparency of the obtained optical element can be controlled. On the other hand, if the average diameter of the strontium carbonate powder is below the aforementioned upper limit, the surface of the obtained optical element can be kept smooth.

[0024] [6] The optical element of the present invention is formed by molding the resin composition described in any one of [1] to [5] above.

[0025] Invention Effects

[0026] According to the present invention, a resin composition is provided that suppresses the occurrence of molding defects such as wire drawing and is capable of forming an optical element with high transparency and low birefringence, as well as an optical element formed by molding the resin composition. Attached Figure Description

[0027] Figure 1 This is a schematic diagram illustrating the optical lens fabricated in the embodiment. Detailed Implementation

[0028] The embodiments of the present invention will now be described in detail.

[0029] (Resin Composition)

[0030] The resin composition of the present invention comprises an alicyclic polymer and strontium carbonate powder, and optionally further comprises other complexing agents.

[0031] <Polylicyclic polymers>

[0032] In this specification, an alicyclic polymer refers to a polymer and / or its hydride obtained by polymerizing one or more alicyclic monomers. When polymerizing alicyclic monomers to obtain an alicyclic polymer, the alicyclic monomers may be polymerized alone, or the alicyclic monomers may be copolymerized with monomers other than alicyclic monomers. That is, in this specification, an alicyclic polymer contains structural units from alicyclic monomers and may arbitrarily contain structural units from monomers other than alicyclic monomers.

[0033] Specific examples of alicyclic monomers are not particularly limited, but can include: monocyclic, dicyclic, tricyclic, tetracyclic, and pentacyclic monomers, as well as derivatives of these monomers with substituents on the ring.

[0034] As a monocyclic (single-ring) alicyclic monomer, there are no particular limitations, but examples include: cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclopentadiene, 1,3-cyclohexadiene, etc. Monocyclic alicyclic monomers can also be combined in combinations of two or more of these alicyclic monomers.

[0035] As a bicyclic monomer containing an alicyclic structure, there are no particular limitations, but examples include: bicyclic [2.2.1]hept-2-ene (common name: norbornene, sometimes abbreviated as "NB"), 5-methyl-bicyclic [2.2.1]hept-2-ene, 5,5-dimethyl-bicyclic [2.2.1]hept-2-ene, 5-ethyl-bicyclic [2.2.1]hept-2-ene, 5-butyl-bicyclic [2.2.1]hept-2-ene, 5-Ethylene-bicyclo[2.2.1]hept-2-ene, 5-hexylene-bicyclo[2.2.1]hept-2-ene, 5-octylene-bicyclo[2.2.1]hept-2-ene, 5-octadecylene-bicyclo[2.2.1]hept-2-ene, 5-methylene-bicyclo[2.2.1]hept-2-ene, 5-vinylene-bicyclo[2.2.1]hept-2-ene, 5-propenylene-bicyclo[2.2.1]hept-2-ene, etc. Bicyclic alicyclic monomers can also be combined in combinations of two or more of these alicyclic monomers. Among these, norbornene is preferred among the bicyclic alicyclic monomers.

[0036] As a tricyclic monomer containing an alicyclic structure, there are no particular limitations; examples include: tricyclic [5.2.1.0] 2,6 ] Dec-3,8-diene (common name: dicyclopentadiene, sometimes abbreviated as "DCP" below)., tricyclic [5.2.1.0 2,6 ] Dec-3-ene, tricyclic [6.2.1.0 2,7 Undecyl-3,9-diene, tricyclic [6.2.1.0] 2,7 Undecyl-4,9-diene, tricyclic [6.2.1.0] 2,7 Examples include undecyl-9-ene, 5-cyclopentyl-bicyclo[2.2.1]hept-2-ene, 5-cyclohexyl-bicyclo[2.2.1]hept-2-ene, 5-cyclohexenylbicyclo[2.2.1]hept-2-ene, and 5-phenyl-bicyclo[2.2.1]hept-2-ene. Tricyclic alicyclic monomers can also be combined in combinations of two or more of these alicyclic monomers.

[0037] As a tetracyclic monomer containing an alicyclic structure, there are no particular limitations; examples include: tetracyclic [6.2.1.1] 3,6 .0 2,7 Dodecyl-4-ene (also simply called "tetracyclododecene", sometimes abbreviated as "TCD"), 9-methyltetracyclo[6.2.1.1] 3 ,6 .0 2,7 [6.2.1.1] Dodecyl-4-ene, 9-ethyltetracyclo[6.2.1.1] 3,6 .0 2,7 Dodecyl-4-ene (hereinafter sometimes abbreviated as "ETD"), 9-methylenetetracyclo[6.2.1.1] 3,6 .02.7 [6.2.1.1 Dodecyl-4-ene, 9-ethylidene tetracyclo[6.2.1.1] 3,6 .0 2.7 [6.2.1.1] Dodecyl-4-ene, 9-vinyltetracyclo[6.2.1.1] 3,6 .0 2.7 [6.2.1.1] Dodecyl-4-ene, 9-propenyl-tetracyclo[6.2.1.1] 3,6 .0 2.7 [Dodecyl-4-ene, tetracyclo[9.2.1.0]] 2,10 .0 3,8 [Tetradecano-3,5,7,12-tetraene (also known as 1,4-methylbridged-1,4,4a,9a-tetrahydrofluorene, sometimes abbreviated as "MTF"), tetracyclic [10.2.1.0] 2,11 .0 4,9 [15-C-4,6,8,13-Tetraene (also known as 1,4-methylbridged-1,4,4a,9,9a,10-hexahydroanthracene), etc. Tetracyclic alicyclic monomers can also be combined in combination with two or more of these alicyclic monomers. Among these, the tetracyclic alicyclic monomers are preferably selected from at least one or more monomers selected from tetracyclic dodecene and 1,4-methylbridged-1,4,4a,9a-tetrahydrofluorene.]

[0038] As a monomer with an alicyclic structure of five or more rings, there are no particular limitations; examples include: (E)9-cyclopentyl-tetracyclic [6.2.1.1] 3,6 .0 2,7 [6.2.1.1] Dodecyl-4-ene, 9-cyclohexyl-tetracyclo[6.2.1.1] 3,6 .0 2,7 [6.2.1.1] Dodecyl-4-ene, 9-cyclohexenyl-tetracyclo[6.2.1.1] 3,6 .0 2,7 [Dodecyl-4-ene, pentacyclic [6.6.1.1]] 3,6 .0 2,7 .0 9,14 ]-4-Hexadecene, Pentane [6.5.1.1 3,6 .0 2,7 .0 9,13 ]-4-Pentadecene, Pentane [7.4.0.0] 2,7 .1 3,6 .1 10,13 ]-4-pentadecanene, 9-phenyl-cyclopentyl-tetracyclo[6.2.1.1] 3,6 .0 2,7 [Dodecyl-4-ene, heptacyclic [8.7.0.1]] 2,9 .1 4,7 .1 11,17 .0 3,8 .0 12,16]-5-Eicosene, heptacyclic [8.7.0.1 2,9 .0 3,8 .1 4,7 .0 12,17 .1 13,16 ]-14-eicosene, etc. Monomers with alicyclic structures of five rings or more can also be combined in combination with two or more of these alicyclic structures.

[0039] The substituents on the ring of the above-mentioned derivatives are not particularly limited, and examples include alkyl, alkylene, vinyl, alkoxycarbonyl, alkylidene, etc.

[0040] As for monomers other than those containing alicyclic structures, there are no particular limitations as long as they can copolymerize with the aforementioned alicyclic monomers. Examples include α-olefins with 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-pentene, and 1-hexene, and their derivatives; and non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, and 1,7-octadiene. Among these, α-olefins are preferred, and ethylene is particularly preferred.

[0041] In one embodiment, when an alicyclic polymer is obtained by polymerizing an alicyclic monomer and other monomers other than the alicyclic monomer, from the viewpoint of transparency and birefringence, the mass ratio of the amount of other monomers used to the amount of alicyclic monomers used (other monomers / alicyclic monomers) is preferably 30 / 70 or less, more preferably 20 / 80 or less, even more preferably 10 / 90 or less, and particularly preferably 1 / 99 or less.

[0042] The alicyclic polymer is a polymer containing alicyclic monomers, meaning that the mass ratio of the amount of other monomers used to the amount of alicyclic monomers used (other monomers / licyclic monomers) is preferably 0 / 100.

[0043] In another embodiment, when polymerizing an alicyclic monomer and other monomers other than the alicyclic monomer to obtain an alicyclic polymer, the mass ratio of the amount of other monomers used to the amount of alicyclic monomers used (other monomers / alicyclic monomers) is preferably 1 / 99 or more, more preferably 3 / 97 or more, even more preferably 5 / 95 or more, preferably 70 / 30 or less, more preferably 50 / 50 or less, and even more preferably 40 / 60 or less.

[0044] The alicyclic polymer can be, for example, a polymer obtained by addition polymerization of alicyclic monomers (alicyclic addition polymer) or a polymer obtained by ring-opening polymerization of alicyclic monomers (alicyclic ring-opening polymer). Among these, alicyclic ring-opening polymers are preferred due to their excellent mechanical strength.

[0045] In addition, open-ring polymers containing alicyclic structures can be obtained by polymerizing one or more monomers with bicyclic or higher alicyclic structures.

[0046] The aforementioned ring-opening polymers containing alicyclic structures can be manufactured, for example, by a method using a ruthenium carbene complex catalyst or other translocation reaction catalyst (ring-opening polymerization catalyst) as described in International Publication No. 2010 / 110323, and by a method using a tungsten tetrachloride (phenylimide)-tetrahydrofuran complex or other ring-opening polymerization catalyst as described in Japanese Patent Application Publication No. 2015-54885.

[0047] The aforementioned alicyclic addition polymers can be manufactured using existing known polymerization methods, such as by using a catalyst system that combines addition polymerization catalysts such as titanium compounds, zirconium compounds, and vanadium compounds with co-catalysts such as organoaluminum compounds.

[0048] The alicyclic polymer can be any of an alicyclic addition polymer, an alicyclic ring-opening polymer, or their hydrides, but due to its excellent mechanical strength, the hydride is preferred (hereinafter, the hydrides of alicyclic addition polymers and hydrides of alicyclic ring-opening polymers are sometimes referred to together as "alicyclic polymer hydrides"). The alicyclic polymer is particularly preferred as an alicyclic ring-opening polymer hydride obtained by hydrogenating an alicyclic ring-opening polymer.

[0049] As a method for producing alicyclic ring-opening polymer hydrides by hydrogenating alicyclic ring-opening polymer, examples include the method using a hydrogenation catalyst described in International Publication No. 2010 / 110323. Furthermore, for example, the aforementioned ruthenium carbene complex catalyst can be used as a ring-opening polymerization catalyst. After producing the alicyclic polymer, the ruthenium carbene complex catalyst can also be used directly as a hydrogenation catalyst to hydrogenate the alicyclic ring-opening polymer to produce alicyclic ring-opening polymer hydrides.

[0050] The hydrogenation rate of the alicyclic polymer hydride is preferably 90% or more, more preferably 95% or more, and even more preferably 99% or more.

[0051] If the hydrogenation rate of the alicyclic polymer hydride is above the aforementioned lower limit, its weather resistance and heat resistance can be improved. The hydrogenation rate of the alicyclic polymer hydride can be adjusted, for example, by changing the conditions of the hydrogenation reaction.

[0052] Furthermore, in this specification, the hydrogenation rate of the alicyclic polymer hydride can be determined by... 1 It was determined by H-NMR measurements.

[0053] The glass transition temperature (hereinafter sometimes abbreviated as "Tg") of alicyclic polymers varies depending on the type of polymer, preferably 70°C or higher, more preferably 100°C or higher, even more preferably 130°C or higher, preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower.

[0054] If the heat resistance (Tg) of the alicyclic polymer is above the lower limit mentioned above, an optical element with high heat resistance can be obtained. On the other hand, if the heat resistance (Tg) of the alicyclic polymer is below the upper limit mentioned above, it is possible to prevent the molding temperature of the resin composition from becoming too high and to prevent resin scorching of the resin composition.

[0055] Furthermore, in this specification, Tg is measured using a differential scanning calorimeter according to JIS K7121 at a heating rate of 10°C / min. The differential scanning calorimeter can be the DSC6220 manufactured by Seiko Nanotechnology Co., Ltd.

[0056] The weight-average molecular weight (hereinafter sometimes abbreviated as "Mw") of the alicyclic polymer is preferably 5,000 or more, more preferably 8,000 or more, even more preferably 10,000 or more, preferably 40,000 or less, more preferably 35,000 or less, and even more preferably 30,000 or less.

[0057] If the Mw of the alicyclic polymer is above the lower limit mentioned above, the viscosity of the resin composition reaches a good level, which improves the moldability of the resin composition. On the other hand, if the Mw of the alicyclic polymer is below the upper limit mentioned above, the viscosity of the resin composition reaches a good low level, which reduces the residual stress of the obtained optical element, resulting in a further reduction in the birefringence of the optical element. In addition, the generation of molding defects such as weld lines can be suppressed. In addition, in this specification, a weld line refers to a fine line generated on the fused portion of the molten resin in the mold during resin molding.

[0058] Additionally, in this specification, the Mw of alicyclic polymers is a converted value of polyisoprene (or polystyrene in the case of tetrahydrofuran solution) determined by gel permeation chromatography using a cyclohexane solution (or a tetrahydrofuran solution if the alicyclic polymer is insoluble).

[0059] The proportion of the alicyclic polymer in the resin composition is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, even more preferably 99.0% by mass or more, even more preferably 99.2% by mass or more, particularly preferably 99.35% by mass or more, preferably 99.8% by mass or less, more preferably 99.7% by mass or less, and even more preferably 99.6% by mass or less.

[0060] <Strontium carbonate powder>

[0061] Strontium carbonate powder contains strontium carbonate. In addition to strontium carbonate, strontium carbonate powder may also contain auxiliary components such as surfactants. The proportion of strontium carbonate in the strontium carbonate powder is, for example, 30% by mass or more, preferably 35% by mass or more.

[0062] In one embodiment, the strontium carbonate powder comprises nanoparticles formed from strontium carbonate (hereinafter also referred to as "strontium carbonate nanoparticles").

[0063] In the resin composition of the present invention, the content of strontium carbonate powder in the resin composition is 0.2% by mass or more and 1.0% by mass or less. Such a resin composition suppresses molding defects such as fiber drawing and enables the formation of optical elements with high transparency and low birefringence. The reasons for this are as described below.

[0064] When molding an optical element from a resin composition, it is desirable to use a higher molding temperature to reduce residual stress and thus birefringence. However, increasing the molding temperature reduces the viscosity of the resin composition, sometimes causing stringing during optical element molding. If the strontium carbonate powder content in the resin composition is 0.2% by mass or more, stringing can be suppressed even at high molding temperatures, enabling the formation of an optical element with low birefringence. Furthermore, since the molding temperature can be increased, weld lines can be suppressed when molding the resin composition to obtain the optical element.

[0065] On the other hand, if the content of strontium carbonate powder in the resin composition is 1.0% by mass or less, the resin composition can suppress light scattering caused by the powder, and can form an optical element with high transparency. Furthermore, although strontium carbonate powder has the effect of suppressing birefringence, surprisingly, when the content of strontium carbonate powder in the resin composition is 1.0% by mass or less, an optical element with low birefringence can be formed. The reason for this may not be clear, but based on the examples and comparative examples described below, it is clear that when the content of strontium carbonate powder is 1.0% by mass or less, an optical element with low birefringence can be formed.

[0066] The content of strontium carbonate powder in the resin composition is preferably 0.3% by mass or more, more preferably 0.4% by mass or more, preferably 0.8% by mass or less, and more preferably 0.65% by mass or less.

[0067] The aspect ratio (ratio of average major diameter to average minor diameter) of the strontium carbonate powder is preferably 1.1 or more, more preferably 1.2 or more, even more preferably 1.3 or more, preferably 5.0 or less, and more preferably 4.0 or less.

[0068] If the aspect ratio of the strontium carbonate powder is above the lower limit and below the upper limit, the birefringence of the resulting optical element can be effectively suppressed.

[0069] The average diameter of the strontium carbonate powder is preferably 10 nm or more, more preferably 15 nm or more, more preferably 100 nm or less, and more preferably 75 nm or less.

[0070] If the average diameter of the strontium carbonate powder is above the lower limit mentioned above, particle aggregation can be suppressed, and the reduction in the transparency of the obtained optical element can be controlled. On the other hand, if the average diameter of the strontium carbonate powder is below the upper limit mentioned above, the surface of the obtained optical element can be kept smooth.

[0071] The average major and minor axes of the strontium carbonate powder were determined by automatic image processing of scanning electron microscopy (SEM) images of the strontium carbonate powder. The major axis of the strontium carbonate powder was measured as the length (length of the long side) when the strontium carbonate powder was considered as a rectangle. Similarly, the minor axis of the strontium carbonate powder was measured as the length (length of the short side) when the strontium carbonate powder was considered as a rectangle. Specifically, the rectangle with the smallest area circumscribed to the strontium carbonate powder in the image was calculated, and the major and minor axes were determined based on the lengths of its long and short sides. Furthermore, "average" refers to the average value obtained by measuring the major and minor axes of a statistically reliable number (N) of strontium carbonate powder samples, typically 100 or more, preferably 300 or more, and more preferably 500 or more.

[0072] The strontium carbonate powder preferably comprises strontium carbonate nanoparticles and a surfactant attached to the surface of the strontium carbonate nanoparticles. Such a strontium carbonate powder can improve the dispersibility of the strontium carbonate powder in the resin composition.

[0073] Surfactants can be compounds having hydrophilic and hydrophobic groups, and further having groups that form anions in water. Preferably, the hydrophilic group is a polyoxyalkylene group, with a hydrophobic group bonded to one end of the polyoxyalkylene group and a group that forms anion in water bonded to the other end. The hydrophobic group is preferably alkyl or aryl, more preferably phenyl. The group that forms anion in water is preferably a carboxylic acid group, a sulfate group, or a phosphate group.

[0074] The surfactant is preferably a phosphate ester whose anionic group is a phosphate group. Since phosphate esters have higher heat resistance compared to carboxylic acid esters and sulfate esters, resin compositions containing strontium carbonate nanoparticles surface-treated with phosphate esters are less prone to discoloration due to the thermal decomposition of the surfactant. Examples of phosphate esters include, for example, polyoxyethylene styrene phenyl ether phosphate and polyoxyethylene alkyl ether phosphate.

[0075] The surfactant content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, more preferably 40 parts by mass or less, and more preferably 30 parts by mass or less, relative to 100 parts by mass of strontium carbonate nanoparticles.

[0076] If the surfactant content is above the lower limit mentioned above, the dispersibility of strontium carbonate powder in the resin composition can be further improved. On the other hand, if the surfactant content is below the upper limit mentioned above, the surfactant can be prevented from becoming an impurity during the manufacture of the resin composition, thereby further improving the transparency of the obtained optical element.

[0077] In addition, in this specification, the surfactant content of the strontium carbonate powder is determined by, for example, a thermogravimetric differential thermal analysis (TG-DTA) apparatus.

[0078] As a method for manufacturing strontium carbonate powder, one can cite, for example, the method described in Japanese Patent Application Publication No. 2021-47402.

[0079] <Other compounding agents>

[0080] The resin composition of the present invention may include other known compounding agents as needed, without impairing the effects of the invention. Examples of other known compounding agents include: lubricants, release agents, dispersants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, infrared absorbers, antistatic agents, dispersants, dechlorinating agents, flame retardants, nucleating agents, antifogging agents, pigments, organic fillers, neutralizers, decomposing agents, metal passivators, antifouling materials, antibacterial agents, thermoplastic elastomers, etc.

[0081] <Physical Properties of Resin Compositions>

[0082] The melt flow rate (hereinafter sometimes abbreviated as "MFR") of the resin composition of the present invention, measured according to JIS K6719 at a temperature of 280°C and a load of 21.18 N, is preferably 40 g / 10 min or more, more preferably 45 g / 10 min or more, further preferably 50 g / 10 min or more, preferably 80 g / 10 min or less, and more preferably 60 g / 10 min or less.

[0083] If the resin composition has a MFR (Mean Refractive Index) of 5% or higher than the lower limit, the birefringence of the resulting optical element can be further reduced, and molding defects such as weld lines can be suppressed. On the other hand, if the MFR is below the upper limit, the moldability of the resin composition can be improved.

[0084] The MFR of the resin composition can be adjusted according to the MFR of the alicyclic polymer and the proportion of the alicyclic polymer.

[0085] <Uses of Resin Compositions>

[0086] Because the resin composition of the present invention suppresses molding defects such as fiber drawing and can form optical elements with high transparency and low birefringence, it is particularly preferred for use in optical elements obtained by injection molding. That is, the resin composition of the present invention is particularly preferred for use in optical elements. Examples of such optical elements include optical lenses, diffraction gratings, filters, prisms, etc.

[0087] (Methods and procedures for manufacturing the resin composition)

[0088] The method for manufacturing the resin composition of the present invention is not particularly limited. For example, the resin composition of the present invention can be manufactured by mixing a polymer containing an alicyclic structure and strontium carbonate powder. The resin composition can be obtained, for example, in the form of resin particles. The mixing temperature is not particularly limited, but is, for example, 180°C or higher, preferably 190°C or higher, more preferably 200°C or higher, for example, 300°C or lower, preferably 290°C or lower, more preferably 280°C or lower.

[0089] The resin composition of the present invention can also be manufactured by mixing strontium carbonate powder and appropriate compounding agents in a high concentration in an alicyclic polymer, then mastering the mixture, and then mixing the masterbatch and the alicyclic polymer in a desired ratio, followed by melt mixing.

[0090] The concentration of strontium carbonate powder and various compounding agents in the masterbatch is not particularly limited, but is preferably more than 2 times and less than 30 times the mass concentration in the final product, and more preferably more than 4 times and less than 25 times.

[0091] The mixing of alicyclic polymers, strontium carbonate powder, and appropriate compounding agents is not particularly limited and can be performed using mixers such as Henschel mixers, V-type mixers, belt mixers, drum mixers, and conical mixers. Furthermore, after this mixing, without particular limitation, the resin composition can be obtained by melt-kneading using a single-screw extruder, twin-screw extruder, kneader, etc.

[0092] The shape of the resin composition is not particularly limited, but for easy molding of optical elements, it is preferred to be granulated, crushed, or in particulate form.

[0093] (Optical components)

[0094] The optical element of the present invention is formed by molding the resin composition of the present invention. Since the optical element of the present invention is formed by molding the resin composition of the present invention, it has high transparency and low birefringence. Furthermore, since the resin composition of the present invention can suppress molding defects such as fiber drawing, the optical element of the present invention is preferably injection molded from the resin composition. Examples of optical elements include optical lenses, diffraction gratings, filters, and prisms.

[0095] The melting temperature during molding varies depending on the alicyclic polymer and resin composition used, and is preferably 200°C or higher, more preferably 250°C or higher, even more preferably 300°C or higher, preferably 400°C or lower, and more preferably 350°C or lower.

[0096] If the melting temperature during molding is above the aforementioned lower limit, an optical element with lower birefringence can be obtained because the residual stress of the optical element can be reduced. Furthermore, the formation of molding defects such as weld lines can be suppressed.

[0097] On the other hand, if the melting temperature during molding is below the aforementioned upper limit, resin scorching in the resin composition can be reduced, resulting in optical elements with superior transparency. Furthermore, molding defects such as stringing can be further suppressed.

[0098] In addition, in the injection molding described in this specification, the melting temperature during molding refers to the temperature of the resin composition in the molten state.

[0099] When using a mold, when the glass transition temperature of the polymer containing an alicyclic structure is denoted as Tg (unit: °C), the temperature of the mold is preferably (Tg-30 °C) or higher, more preferably (Tg-20 °C) or higher, even more preferably (Tg-10 °C) or higher, preferably (Tg+15 °C) or lower, more preferably (Tg+10 °C) or lower, and even more preferably (Tg+5 °C) or lower.

[0100] Example

[0101] The present invention will be further described in detail below with examples and comparative examples. However, the present invention is not limited to these examples.

[0102] In the following examples and comparative examples, various physical properties were measured according to the methods described below.

[0103] <Weight-average molecular weight>

[0104] The weight-average molecular weight (Mw) of alicyclic polymers was determined by gel permeation chromatography (GPC) using cyclohexane as the eluent, and calculated as a standard polyisoprene equivalent.

[0105] As standard polyisoprene, standard polyisoprene manufactured by Tosoh Corporation (Mw = 602, 1390, 3920, 8050, 13800, 22700, 58800, 71300, 109000, 280000) is used.

[0106] During the assay, three chromatographic columns (manufactured by Tosoh Corporation, TSKgel G5000HXL, TSKgel G4000HXL and TSKgel G2000HXL) were connected in series and used under the conditions of a flow rate of 1.0 mL / min, a sample injection volume of 100 μL and a column temperature of 40 °C.

[0107] Glass transition temperature

[0108] The glass transition temperature (Tg) of the alicyclic polymers was determined using a differential scanning calorimeter (manufactured by Seiko Electronics Nanotechnology Co., Ltd., "DSC6220") according to JIS K7121 at a heating rate of 10°C / min.

[0109] <Hydrogenation rate (carbon-carbon double bond residue)>

[0110] The hydrogenation rate of polymers containing alicyclic structures is determined by... 1 It was determined by H-NMR measurements.

[0111] Melt flow rate

[0112] The melt flow rate (MFR) of the resin composition was determined according to JIS K6719 at a temperature of 280°C and a load of 21.18 N (2.16 kgf).

[0113] <Haze>

[0114] Particles of a resin composition containing a polymer with an alicyclic structure are fed into an injection molding machine (manufactured by FANUC, product name "ROBOSHOT S2000i100A") and injection molded at a resin temperature of 270°C, a mold temperature of (Tg-20)°C, and an injection pressure of 80MPa to produce a resin plate with a length of 65mm, a width of 65mm, and a thickness of 3mm.

[0115] Next, the resin plate was used as a test piece, and the haze in the 3mm thickness direction of the test piece was measured using a turbidimeter (NDH7000SPII, manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with the method of JIS K7105.

[0116] <Silk-drawing>

[0117] Particles of a resin composition containing an alicyclic polymer were fed into an injection molding machine (FANUC, product name "ROBOSHOT αS-50iA"). Injection molding was performed using a mold at a resin temperature of 310°C, a mold temperature of (Tg-5)°C, an injection pressure of 50 MPa, and a mold opening distance of 150 mm to produce an optical lens with a convex radius of curvature of 5.73 mm, a concave radius of curvature of 3.01 mm, a diameter of 4.5 mm, a lens portion (optical effective surface) diameter of 3 mm, and a center thickness of 0.02 mm. Figure 1 Additionally, in Figure 1 In the diagram, A represents the gate direction and B represents the backgate direction.

[0118] The length of the string produced between the nozzle and the sprue section of the molding machine when the lens is removed from the mold is measured.

[0119] <Fusion line>

[0120] The surface of the lens obtained above was observed using an optical microscope (Olympus Corporation, "BX60"), and the length of the weld line generated in the direction of the back gate was measured.

[0121] Birefringence

[0122] The birefringence of the central portion of the lens obtained above was measured using a resin-molded lens inspection system (manufactured by Photonic Lattice Co., Ltd., "WPA-100"). The birefringence value was obtained as a normalized value at the measurement wavelength (543 nm). The smaller the value, the lower the birefringence.

[0123] In the following examples and comparative examples, polymers (A) to (D) containing alicyclic structures and strontium carbonate powder were used as polymers and strontium carbonate powder manufactured by the following methods.

[0124] (Manufacturing of alicyclic polymer (A))

[0125] A mixture of monomers consisting of 70% by mass of methyl-bridged tetrahydrofluorene (MTF), 23% by mass of tetracyclododecene (TCD), and 7% by mass of norbornene (NB) was added to a dry, nitrogen-replaced polymerization reactor. The mixture also included 1600 parts by mass of dehydrated cyclohexane, 0.55 parts by mass of 1-hexene, 1.3 parts by mass of diisopropyl ether, 0.33 parts by mass of isobutanol, 0.84 parts by mass of triisobutylaluminum, and 30 parts by mass of 0.66% by mass of tungsten hexachloride cyclohexane solution. The mixture was stirred at 55°C for 10 minutes.

[0126] Next, the reaction system was maintained at 55°C, and while stirring, 693 parts by mass of the above monomer mixture and 72 parts by mass of a 0.77% by mass cyclohexane solution of tungsten hexachloride were continuously added dropwise to the polymerization reactor over 150 minutes. After the addition was stopped, the mixture was stirred for 30 minutes, and 1.0 part by mass of isopropanol was added to terminate the ring-opening polymerization reaction. The polymerization reaction solution was analyzed by gas chromatography, and the result showed that the conversion rate of monomer to polymer was 100%.

[0127] Next, 300 parts by mass of the polymerization reaction solution containing the above polymer were transferred to an autoclave equipped with a stirrer, and 100 parts by mass of cyclohexane and 2.0 parts by mass of diatomaceous earth-supported nickel catalyst (manufactured by Nichih Chemical Co., Ltd.; "T8400RL", nickel loading rate 58% by mass) were added. After purging the autoclave with hydrogen, the reaction was carried out at 180°C and a hydrogen pressure of 4.5 MPa for 6 hours.

[0128] After the hydrogenation reaction was terminated, diatomaceous earth (manufactured by Showa Chemical Industry Co., Ltd., “RADIOLITE (registered trademark) ♯500”) was used as a filter bed, and a pressure filter (manufactured by IHI Corporation; “FUNDA Filter”) was used to filter the polymerization reaction solution after the hydrogenation reaction was completed at a pressure of 0.25 MPa, resulting in a colorless and transparent solution.

[0129] Next, 0.25 parts by weight of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (manufactured by Ciba Specialty Chemicals; "Irganox 1010") relative to 100 parts by weight of the above-mentioned hydride were added to the obtained solution as an antioxidant and dissolved.

[0130] The solution was filtered using a filter (CUNO FILTER Co., Ltd.; "Zeta Plus (registered trademark) 30H", pore size 0.5~1μm), and then the filtrate was filtered using a metal fiber filter (NICHIDAI Co., Ltd., pore size 0.4μm) to remove impurities.

[0131] Next, using a cylindrical concentrator (manufactured by Hitachi, Ltd.), at a temperature of 260°C and a pressure of 1 kPa or less, cyclohexane and other volatile components, which serve as solvents, are removed from the filtrate (solution) obtained above. The remaining material is extruded in a molten state into strands through a die directly connected to the concentrator. After water cooling, the strands are cut using a granulator (manufactured by Nagata, Ltd.; "OSP-2") to obtain particles of the alicyclic polymer (A).

[0132] The alicyclic polymer (A) has a molecular weight (Mw) of 25,000, an Mw / Mn ratio of 1.6, a hydrogenation rate of 99.9%, and a temperature gradient (Tg) of 141°C. Mn represents the number-average molecular weight.

[0133] (Manufacturing of alicyclic polymer (B))

[0134] The amount of 1-hexene used was adjusted to 0.5 parts by mass. Otherwise, the alicyclic polymer (B) was manufactured in the same manner as the alicyclic polymer (A).

[0135] The alicyclic polymer (B) has a Mw of 26,500, an Mw / Mn ratio of 1.7, a hydrogenation rate of 99.9%, and a Tg of 142℃.

[0136] (Manufacturing of alicyclic polymers (C))

[0137] Norbornene, a hydrocarbon solvent (polymerization solvent), ethylene, and hydrogen are supplied to the continuous polymerization unit at a rate of 52 kg / h, 23 kg / h, 4.0 kg / h, and 0.67 g / h, respectively. Simultaneously, a catalyst system consisting of diphenylmethylene-cyclopentadienylfluorenylzirconium dichloride as the catalyst (polymerization catalyst) and methylaluminoxane (10% by mass toluene solution) as the co-catalyst is supplied to the continuous polymerization unit. The temperature of the continuous polymerization unit is maintained at 70°C to obtain the addition polymer. In the stirred tank of the next process, 0.2% by mass of pentaerythritol-tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (manufactured by Ciba Specialty Chemicals; "Irganox (registered trademark) 1010") is added as an antioxidant to the addition polymer. In the subsequent desolventizing process, the solvent is removed under high temperature and reduced pressure. The molten copolymer is extruded into strands and cut using a granulator (manufactured by Nagata Manufacturing Co., Ltd.; "OSP-2") to obtain particles of the alicyclic polymer (C).

[0138] The Tg of the alicyclic polymer (C) is 137℃.

[0139] (Manufacturing of alicyclic polymers (D))

[0140] Norbornene, a hydrocarbon solvent (polymerization solvent), ethylene, and hydrogen are supplied to the continuous polymerization unit at a rate of 36 kg / h, 22 kg / h, 3.0 kg / h, and 0.45 g / h, respectively. Simultaneously, a catalyst system consisting of diphenylmethylene-cyclopentadienylindenylzirconium dichloride as the catalyst and methylaluminoxane (10% by mass toluene solution) as the co-catalyst is supplied to the continuous polymerization unit. The temperature of the continuous polymerization unit is maintained at 70°C to obtain the addition polymer. In the stirred tank of the next process, 0.2% by mass of pentaerythritol-tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (manufactured by Ciba Specialty Chemicals; "Irganox (registered trademark) 1010") is added as an antioxidant to the addition polymer. In the subsequent desolventizing process, the solvent is removed under high temperature and reduced pressure. The molten copolymer is extruded into strands and cut using a granulator (manufactured by Nagata Manufacturing Co., Ltd.; "OSP-2") to obtain particles of alicyclic polymer (D).

[0141] The Tg of the alicyclic polymer (D) is 139℃.

[0142] (Manufacturing of strontium carbonate powder)

[0143] <Reaction Process>

[0144] 366g of strontium hydroxide octahydrate (premium grade reagent, purity: ≥96% by mass) was added to 3L of pure water at 10°C and mixed to prepare a 5.6% by mass aqueous suspension of strontium hydroxide. DL-tartaric acid (premium grade reagent, purity: ≥99%) was added to this aqueous suspension and stirred until dissolved. Then, while maintaining the temperature of the aqueous suspension at 10°C, carbon dioxide gas was continuously blown into the suspension at a flow rate of 0.5L / min (3mL / min relative to 1g of strontium hydroxide) until the pH of the aqueous suspension reached 7, forming strontium carbonate. Stirring was then continued for another 30 minutes to obtain an aqueous suspension of strontium carbonate.

[0145] <Cooking Process>

[0146] The obtained aqueous suspension of strontium carbonate was placed in a stainless steel tank and heated at 80°C for 24 hours to grow strontium carbonate into needle-like structures. It was then cooled to room temperature to produce an aqueous slurry of strontium carbonate nanoparticles.

[0147] <Surface treatment and drying processes>

[0148] 3500 g of an aqueous slurry of strontium carbonate nanoparticles (concentration: 5.8% by mass) was added to a homogenizer (PRIMIX Co., Ltd., TKHOMO MIXER MARKII). While the homogenizer's stirring blades were rotating at a circumferential speed of 7.85 m / s, 56.8 g (28 parts by mass relative to 100 parts by mass of strontium carbonate nanoparticles) of polyoxyethylene styrene phenyl ether phosphate was added to the aqueous slurry and dissolved. Stirring was then continued for 1 hour. The mixed aqueous slurry was dried to obtain surface-treated strontium carbonate powder. Electron microscopy confirmed that the strontium carbonate powder was needle-shaped (average major diameter: 60 nm).

[0149] (Example 1)

[0150] 0.2 parts by weight of strontium carbonate powder were mixed with 99.8 parts by weight of alicyclic polymer (A) particles. The mixture was compounded using a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., product name "TEM35B") at a resin temperature of 245°C and a screw speed of 180 rpm, extruded into strands, water-cooled, and then cut using a granulator to produce resin composition particles with a length of 4 mm.

[0151] Various determinations were performed using resin composition particles. The results are shown in Table 1.

[0152] (Example 2)

[0153] Resin composition particles were prepared in the same manner as in Example 1, with 0.5 parts by weight of strontium carbonate powder mixed with 99.5 parts by weight of alicyclic polymer (A) particles, and various measurements were performed. The results are shown in Table 1.

[0154] (Example 3)

[0155] Resin composition particles were prepared in the same manner as in Example 1, with 0.75 parts by weight of strontium carbonate powder mixed with 99.25 parts by weight of alicyclic polymer (A) particles, and various measurements were performed. The results are shown in Table 1.

[0156] (Example 4)

[0157] Resin composition particles were prepared in the same manner as in Example 1, with 1 part by weight of strontium carbonate powder mixed with 99 parts by weight of alicyclic polymer (A) particles, and various measurements were performed. The results are shown in Table 1.

[0158] (Example 5)

[0159] Instead of alicyclic polymer (A), alicyclic polymer (B) was used. 0.5 parts by weight of strontium carbonate powder were mixed with 99.5 parts by weight of particles of alicyclic polymer (B). Otherwise, resin composition particles were prepared in the same manner as in Example 1, and various measurements were performed. The results are shown in Table 1.

[0160] (Comparative Example 1)

[0161] No strontium carbonate powder containing alicyclic polymer (A) was mixed with the particles; otherwise, various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0162] (Comparative Example 2)

[0163] Resin composition particles were prepared in the same manner as in Example 1, with 0.1 parts by weight of strontium carbonate powder mixed with 99.9 parts by weight of alicyclic polymer (A) particles, and various measurements were performed. The results are shown in Table 1.

[0164] (Comparative Example 3)

[0165] Resin composition particles were prepared in the same manner as in Example 1, with 1.5 parts by weight of strontium carbonate powder mixed with 98.5 parts by weight of alicyclic polymer (A) particles, and various measurements were performed. The results are shown in Table 1.

[0166] (Example 6)

[0167] 0.2 parts by weight of strontium carbonate powder were mixed with 99.8 parts by weight of alicyclic polymer (C) particles. The mixture was compounded using a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., product name "TEM35B") at a resin temperature of 240°C and a screw speed of 160 rpm, extruded into strands, water-cooled, and then cut using a granulator to produce resin composition particles with a length of 4 mm.

[0168] Resin composition particles were prepared using resin composition granules, and various determinations were performed. The results are shown in Table 2.

[0169] (Example 7)

[0170] Resin composition particles were prepared in the same manner as in Example 6, with 0.5 parts by weight of strontium carbonate powder mixed with 99.5 parts by weight of alicyclic polymer (C) particles, and various measurements were performed. The results are shown in Table 2.

[0171] (Example 8)

[0172] Resin composition particles were prepared in the same manner as in Example 6, with 0.75 parts by weight of strontium carbonate powder mixed with 99.25 parts by weight of alicyclic polymer (C) particles, and various measurements were performed. The results are shown in Table 2.

[0173] (Example 9)

[0174] Resin composition particles were prepared in the same manner as in Example 6, with 1 part by weight of strontium carbonate powder mixed with 99 parts by weight of alicyclic polymer (C) particles, and various measurements were performed. The results are shown in Table 2.

[0175] (Example 10)

[0176] 0.5 parts by weight of strontium carbonate powder were mixed with 99.5 parts by weight of alicyclic polymer (D) particles. The mixture was compounded using a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., product name "TEM35B") at a resin temperature of 245°C and a screw speed of 160 rpm, extruded into strands, water-cooled, and then cut using a granulator to produce resin composition particles with a length of 4 mm.

[0177] Resin composition particles were prepared using resin composition granules, and various determinations were performed. The results are shown in Table 2.

[0178] (Comparative Example 4)

[0179] No strontium carbonate powder containing alicyclic polymer (C) was mixed with the particles; otherwise, the evaluations were performed in the same manner as in Example 6. The results are shown in Table 2.

[0180] (Comparative Example 5)

[0181] Resin composition particles were prepared in the same manner as in Example 6, with 0.1 parts by weight of strontium carbonate powder mixed with 99.9 parts by weight of alicyclic polymer (C) particles, and various measurements were performed. The results are shown in Table 2.

[0182] (Comparative Example 6)

[0183] Resin composition particles were prepared in the same manner as in Example 6, with 1.5 parts by weight of strontium carbonate powder mixed with 98.5 parts by weight of alicyclic polymer (C) particles, and various measurements were performed. The results are shown in Table 2.

[0184] [Table 1]

[0185]

[0186] [Table 2]

[0187]

[0188] As can be seen from Tables 1 and 2, Examples 1 to 10 are resin compositions that suppress the formation of filaments and are capable of forming optical elements with high transparency and low birefringence.

[0189] Industrial availability

[0190] According to the present invention, a resin composition is provided that suppresses the occurrence of molding defects such as wire drawing and is capable of forming an optical element with high transparency and low birefringence, as well as an optical element formed by molding the resin composition.

[0191] Explanation of reference numerals in the attached figures

[0192] A: Gate direction;

[0193] B: Back gate direction.

Claims

1. A resin composition comprising an alicyclic polymer and strontium carbonate powder, The strontium carbonate powder in the resin composition is present in an amount of 0.2% by mass or more and 0.4% by mass or less, or in an amount of 0.65% by mass or more and 0.8% by mass or less. The alicyclic polymer is a polymer and / or its hydride obtained by polymerizing alicyclic monomers. The alicyclic monomer is selected from one or more alicyclic monomers with monocyclic, bicyclic, tricyclic, tetracyclic, and pentacyclic structures, and derivatives of the alicyclic monomer having substituents on the ring. The substituents on the ring of the derivative are alkyl, alkylene, vinyl, alkoxycarbonyl, or alkylidene groups. The strontium carbonate powder comprises strontium carbonate nanoparticles and a surfactant attached to the surface of the strontium carbonate nanoparticles. The content of the surfactant is more than 1 part by weight and less than 40 parts by weight relative to 100 parts by weight of the strontium carbonate nanoparticles. The alicyclic polymer comprises structural units derived from the alicyclic monomer, and optionally includes structural units derived from monomers other than the alicyclic monomer. The mass ratio of the amount of other monomers used relative to the amount of alicyclic monomers used, i.e., the ratio of other monomers to alicyclic monomers, is less than 30 / 70.

2. The resin composition according to claim 1, wherein, According to JIS K6719, the melt flow rate, measured at 280°C and 21.18 N, is above 40 g / 10 min.

3. The resin composition according to claim 1 or 2, wherein, The aspect ratio of the strontium carbonate powder is 1.1 or higher.

4. The resin composition according to claim 1 or 2, wherein, The strontium carbonate powder in the resin composition is present in an amount of 0.2% by mass or 0.75% by mass.

5. An optical element formed from the resin composition of claim 1 or 2.

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