Patent Application
20080039609
The present invention relates to a thermoplastic resin, more specifically, to a thermoplastic resin which enables to obtain highly heat-resistant molded product which is small in property changes caused by water absorption and has an excellent optical properties.
In recent years, there has been investigated to employ a transparent plastic injection molding lens instead of conventional glass grinding lenses so as to improve productivity and to produce light-weighted products in the optical lenses such as pick-lenses for optical disc optical system, collimator lenses or various lenses for capturing small image. In addition, there has been investigated to employ transparent plastic films instead of a conventional glass substrate so as to improve resistance to breakage, to give light-weighted and thinner film in the field of a flat panel display such as a liquid crystal display element or organic EL display element.
However, plastic generally has an optical anisotropy caused by distortion during molding so that the optical property may be readily deteriorated. As a result, it is necessary to reduce the optical anisotropy. In addition, the optical properties of the plastic change when affected by water absorption. As a result, low water absorption is required. In addition, it is required to have heat resistance so as to guarantee an operation under the condition that the environment using the plastic has high temperature and to make the plastic suitable for plasticity of an oriented film or sealing material and connection process of a driving circuit, and chemical resistance to various kinds of chemicals used in producing process.
As for such a various kinds of requirements, various kinds of resins have been invented. However, these resins have both advantages and disadvantages. It is considered that it is difficult to develop a resin satisfying all the requirements. Therefore, the resin which is deteriorated in several points but excellent in several points is practically selected and used.
As for the resin having an excellent balance between heat resistance and light transmittance, for example, Patent Document 1 discloses that a resin composition having a total light transmittance of 88% or more, an absolute value of a photoelasticity coefficient of 1.0×10−11Pa−1 or less, a glass transition temperature of 120 to 200° C. and a saturated water absorption ratio of 0.05 to 1 mass %, and comprising a phosphorus antioxidant of 0.01 to 1 parts by mass, based on 100 parts by mass of a thermoplastic amorphous resin having a moisture content of less than 0.05 mass % is suitable for an optical application. However, in the examples, there is only described a product name Aton G6810 manufactured by JSR Corporation as a thermoplastic amorphous resin having a saturated water absorption ratio of 0.4 mass % and the preferred water absorption ratio is 0.1% or more. In Patent Document 2, there is published a resin having various structures as a transparent resin having high heat resistance in Table 1. However, the preferred saturated water absorption ratio is also 0.1 mass % or less and examples of a transparent resin having an excellent optical property and heat resistance are not described. In addition, it is hard to say that the resin described above has a sufficiently low photoelasticity coefficient, and the birefringence becomes a problem when the molded product is used for optical applications.
Further, as for the resin having an excellent balance between low water absorption property and light transmittance, for example, Patent Document 3 discloses a resin B having a water absorption ratio of 0.01% as a resin having the same structure in the reference example 2. However, since the resin B has a low heat transition temperature of 123° C. which is an index for heat resistance, and a photoelasticity coefficient of −4.0×1013 cm2/dyne, it is not sufficient in low birefringence.
Further, as for the resin having an excellent balance between low water absorption property and light transmittance, for example, Non Patent Document 1 discloses methyl polymethacrylate but this resin has also a low heat deformation temperature of 65 to 100° C. and a high water absorption ratio as mentioned above.
[Patent Document 1] Japanese Unexamined Patent Publication No. 2002-088260
[Patent Document 2] Japanese Unexamined Patent Publication No. H01-240517
[Patent Document 3] Japanese Unexamined Patent Publication No. H09-326512 [Non Patent Document 1] Functional materials Vol. 7, March (1987), p. 21 to 29
It has been required a thermoplastic resin that has a low optical anisotropy caused by a distortion during molding so as not to cause the deterioration in optical properties, that is, the plastic having a low optical anisotropy, and having excellent properties of low water absorption ratio, heat resistance, and chemical resistance.
The present invention includes a thermoplastic resin having a glass transition temperature of 130° C. or more, a saturated water absorption ratio of 0.1 mass % or less, and a stress-optical coefficient CR satisfying |CR|≦3×10−10Pa−1.
There is provided a resin that has a low optical anisotropy caused by distortion during molding so as not to cause the deterioration in optical properties, that is, the plastic having a low optical anisotropy, and having excellent properties of low water absorption ratio, heat resistance, and chemical resistance.
In order to solve the above problems, the present inventors have made extensive studies and found that the problems can be solved by a thermoplastic resin having a glass transition temperature of 130° C. or more, a saturated water absorption ratio of 0.1 mass % or less, and a stress-optical coefficient CR satisfying |CR|≦3×10−10Pa−1. As a result, the inventors have achieved the present invention.
That is, the present invention includes a thermoplastic resin having a glass transition temperature of 130° C. or more, a saturated water absorption ratio of 0.1 mass % or less, and a stress-optical coefficient CR satisfying |CR|≦3×10−10Pa−1, more preferably |CR|≦2×10−10 Pa−1.
A preferred aspect of the thermoplastic resin of the present invention preferably includes an alicyclic structure in a part of or all of a repeating structure unit.
Further, a preferred aspect of the thermoplastic resin includes one kind or two or more kinds of structure represented by a general formula (1);
(wherein, x and y each represents a copolymerization ratio and are real numbers satisfying 0/100≦y/x≦65/35, n is a number of a substituent Q and is an integer satisfying 0≦n≦2. R1 is one kind or two or more kinds of 2+n valent group of selected from hydrocarbon groups having 2 to 20 carbon atoms, R2 is a hydrogen atom, or one kind or two kinds or more kinds of monovalent group selected from groups having a structure composed of 1 to 10 carbon atom(s) and hydrogen atom(s), R3 is one kind or two or more kinds of tetravalent group selected from hydrocarbon groups having 2 to 20 carbon atoms, and Q is a monovalent group of one kind or two kinds or more selected from structures represented by COOR4 (R4 is a hydrogen atom, or one kind or two kinds or more kinds of monovalent group selected from groups having a structure composed of 1 to 10 carbon atom(s) and hydrogen atom(s).).)
In the general formula (1), R1 group preferably includes at least one ring structure in the structure. In the general formula (1), y/x is preferably a real number satisfying 20/80≦y/x≦65/35. In the present invention, a resin composition comprising a resin in the amount of 90% mass or more is preferably used and used for various types of molded products. The molded product is preferably used for optic applications.
(Glass Transition Temperature)
The thermoplastic resin used in the present invention has a glass transition temperature of 130° C. or more, preferably in a range of 130° C. or more to 240° C. or less, more preferably in a range of 140° C. or more to 220° C. or less. Among them, the thermoplastic resin in a range of 150° C. or more to 220° C. or less is most preferable.
When the glass transition temperature is below the range, it is not possible to guarantee an operation under the condition that the using environment is high temperature and it is not suitable for plasticity of oriented film or sealing agent and the connecting process of a driving circuit. When the glass transition temperature is above the range, melt molding may become impossible.
(Measuring Method)
For the measuring method of the thermoplastic resin used in the present invention, a known method can be employed. The measuring apparatuses are not limited. When a glass transition temperature of a thermoplastic amorphous resin is measured by using a differential scanning calorimeter (DSC), for example, it is generally measured by a differential scanning calorimeter DSC-20 manufactured by Seiko Electronic KK at the condition of temperature elevation rate of 10° C./min.
(Saturated Water Absorption Ratio)
A thermoplastic resin of the present invention has a saturated water absorption ratio of 0.1 mass % or less, preferably 0.05 mass % or less. There is no lower limit of a saturated water absorption ratio for the resin, a resin composition having a saturated water absorption ratio of 0.02 mass % or more is particularly preferable when considering characteristics of adhesion and treatment. When the ratio is below this range, the characteristics of the adhesion and the treatment may be deteriorated. When the ratio is above this range, the resin is affected by the absorption so that the optical property changes.
(Measuring Method)
For the measuring method of the saturated water absorption ratio, a known method can be used. The measuring apparatuses are not limited.
For example, on the basis of ASTM D570, the saturated water absorption ratio is obtained by immersing said molded sheet in distilled water for 1 week at 23° C., and measuring difference between weight before the immersion and weight after the immersion.
(Stress-Optical Coefficient CR)
A stress-optical coefficient is a known constant number disclosed in Collected Papers on Polymers, Vol. 53, No. 10. on pages 603 to 613 (1996), and is a concept on the basis of modified stress-optical regulations (MSOR) describing a relation between the birefringence and the stress in the vicinity of a glass transition region. According to this concept, the stress-optical coefficient can be divided into R component and G component.
The inventors have found that effects of birefringence at the using environment of the molded product apart from the glass transition region are slightly suppressed by selecting the resin having R component of the stress-optical coefficient in a range of |CR|≦3×10−10Pa−1, when the glass transition temperature is 130° C. or more and the saturated water absorption ration is 0.1 mass % or less. The stress-optical coefficient of the thermoplastic resin of present invention is preferably in a range of |CR|≦2×10−10Pa−1. When the constant number is not in such a range, the obtained molded product has a large optical anisotropy, thereby deteriorating the optical property of the product.
(Measuring Method)
As for a measuring method of said stress-optical coefficient, a known method can be used. The measuring apparatuses are not limited. For example, a method may be exemplified in which the stress-optical coefficient CR is obtained by simultaneously measuring a complex elastic modulus (ER) and a distorted optics ratio (OR) at Tg+10° C. to Tg+30° C. using a press sheet having a thickness of 0.5 mm formed by heat press molding a resin at Tg+100° C. with a viscoelasticity measuring apparatus in combination with the birefringence measuring apparatus and then calculating by the following calculation (I).
CR=OR/ER (I)
(Total Light Transmittance and Spectral Light Transmittance)
A total light transmittance and a spectral light transmittance are not particularly limited. However, in case of using the thermoplastic resin or the resin composition of the present invention for optical applications, it is necessary to transmit light beam. Therefore, it is preferable to have light transmittance to some degree. The light transmittance is defined by a total light transmittance or a spectral light transmittance according to the applications.
In case of using the resin in total light or a plurality of wavelength region, it is necessary to have good total light transmittance and the total light transmittance is preferably 85% or more, more preferably 88% or more. When the total light transmittance is below this range, a required amount of light can not be obtained. As a measuring method, a known method can be used. The measuring apparatuses are not limited. On the basis of ASTM D1003, total light transmittance is obtained by molding the thermoplastic resin into the form of a sheet having a thickness of 3 mm and measuring the molded sheet using a haze meter.
In case of an optical system (for example, laser optical system) using only a specific wavelength, even when the total light transmittance is not relatively high, it can be still used as long as the spectral light transmittance in the wavelength is good. In this case, the spectral light transmittance in the using light wavelength is preferably 85% or more, more preferably 88% or more. When the spectral light transmittance is below this range, the required amount of light can not be obtained. As a measuring method, a known method can be used. The measuring apparatuses are not limited.
(Thermoplastic Resin)
When the thermoplastic resin of the present invention has the glass transition temperature of 130° C. or more, and the saturated water absorption ratio of 0.1 mass % or less, the thermoplastic resin is not particularly limited as long as the thermoplastic resin preferably has a R component of the stress optical constant number of |CR≦3×10−10 Pa−1, more preferably |CR|≦2×10−10 Pa−1. Further, an aspect of the thermoplastic resin suitable for the present invention preferably includes an alicyclic structure in a part of or all of a repeating structural unit. Here, structures (a), (b), and (c) mentioned below are exemplified as a preferred structures of the alicyclic structure. More preferably, the thermoplastic resin includes one kind or two or more kinds of structure represented by said general formula (1). Even further preferably, following conditions are given for symbols in said general formula (1), and these conditions are used in combination if necessary.
[1] R1 group includes at least one part of ring structure in structures.
[2] R3 group is exemplified by structures (a), (b), and (c) as an example of the structural unit including this R3 group (in case that n equals to 0).
(where, R1 in the formula is mentioned above.)
[3] n is 0.
[4] y/x is a real number satisfying 20/80≦y/x≦65/35.
[5] R2 is a hydrogen atom and/or —CH3.
[6] Q is —COOH or —COOCH3 group.
Here, most preferably, symbols in the general formula (1) have following conditions and these conditions are used in combination with each other if necessary.
[1] R1 group is a divalent group represented by a general formula (2):
(where, p is a integral number from 0 to 2.)
More preferably, the R1 group is the divalent group in which p is 1 in the formula (2).
[2] R3 group is an example of a structural unit (in case n equals 0) including this group and is the exemplified structure (a). In the embodiment of combination of these conditions, the most preferred thermoplastic resin is a polymer obtained by a random additional polymerization of ethylene and tetracyclo[4.4.0.12,5.17,10]-3-dodecene. When the thermoplastic resin does not have such a condition in structures, the thermoplastic resin may not has low optical anisotropy which is the excellent property of the resin, caused by distortion during molding, thereby being deteriorated the optical property. That is, when the thermoplastic resin does not have such a condition in structures, the thermoplastic resin may not be the plastic having a small optical anisotropy and the thermoplastic resin may not obtain excellent properties in low absorption ratio, heat resistance, and chemical resistance.
The types of copolymerization are not limited in the present invention. Various types of known copolymers such as a random copolymer, a block copolymer and an alternate copolymer can be employed, but the random copolymer is preferable.
(Other Structures Used in a Part of Main Chain)
The polymer used in the present invention may have a repeating structural unit derived from other copolymerizable monomers in a scope of not causing deterioration of properties of products obtained by the formation method of the present invention if necessary. The ratio of copolymerization is not limited but it is preferable less than 20 mol % or less, more preferably 10 mol % or less. In case that the ratio of copolymerization is above the range, the optical property is deteriorated so that the optical products having high prescience may not be obtained. In addition, the kinds of the copolymerization are not limited but the random copolymer is preferable.
(Molecular Weight of Polymers)
A molecular weight of the polymer used for the optical product of the present invention is not limited but a limiting viscosity [η] measured in decalin of 135° C. is preferably in a rage of 0.03 to 10 dl/g, more preferably 0.05 to 5 dl/g, most preferably 0.10 to 2 dl/g. The moldability of thermoplastic resin deteriorates when the molecular weight is above the range. The molded product is brittle when the molecular weight is below the range.
(Resin Composition)
In the present invention, a resin composition prepared by blending other resins can be used for the polymer if necessary. Other resins can be added within the scope of not disturbing the object of the present invention.
(Additives)
In the polymers used in the present invention, in addition to the constituents mentioned above, a known weathering agent, heat-resistant stabilizer, antistatic agent, fire retardant, slip agent, anti-blocking agent, antifog agent, lubricant, natural oil, synthetic oil, wax, organic or inorganic filler or the like may be blended within the scope of not disturbing the preferred properties of the optical component of the present invention.
For example, specific examples of the weathering agent blended as an arbitrary component include ultraviolet absorbers such as a benzophenone-based compound, a benzotriazole-based compound, a nickel-based compound, and a hindered amine-based compound are given as a light-resistant stabilizer other than a known hindered amine-based additive. The hindered amine-based light-resistant stabilizer is a compound which has 3,5-di-t-butyl-4-hydroxyphenyl group or 2,2,6,6-tetramethylpiperidine group or 1,2,2,6,6-pentamethyl-4-piperidyl group in a structure in general and the specific examples thereof include 1-[2-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy)ethyl]-4-(3,3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidine (for example, Sanol LS-2626 manufactured by Sankyo Co., Ltd.), 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate-bis-(1,2,2,6,6-pentamethyl-4-piperidyl)(for example, Tinuvin 144 manufactured by Chiba-Geigy Japan Ltd.) and the like. Specific examples of the benzotriazole-based ultraviolet absorbers include 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2,2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl, 2-(2′-hydroxy-5′-methylphenyl)benzotriazole, 2-(2′-hydroxy-3′,5′-di-t-butylphenyl)benzotriazole, 2-(2′-hydroxy-3′-t-butyl-5′-methyl-phenyl)-5-chlorobenzotriazole, 2-(2′-hydroxy-3′,5′-di-t-butyl-phenyl)-5-chlorobenzotriazole, 2-(2′-hydroxy-4′-n-octoxyphenyl)benzotriazole, benzotriazole derivatives such as Tinuvin 328 and Tinuvin PS (both manufactured by Chiba-Geigy Japan Ltd.), or SEESORB709 (2-2′-hydroxy-5′-t-octylphenyl)benzotriazole, manufactured by Shiraishi Calcium Kaisha, LTD), which are commercially available. Specific examples of benzophenone-based ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxy-5-sulfobenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2-hydroxy-4-n-octoxy benzophenone, 2-hydroxy-4-octadecyloxy benzophenone, 2-hydroxy-4-n-dodecyloxy benzophenone, 2-hydroxy-4D-benzyloxybenzophenone, 2,2′,4,4′-tetrahydroxy benzophenone, 2-hydroxy-4-dodecyloxy benzophenone, 2-hydroxy-4-(2-hydroxy-3-methacryloxy)propoxybenzophenone, or Uvinul 490 (a mixture of 2,2′-dihydroxy-4,4′-dimethoxy benzophenone and other tetrasubstituted benzophenone, manufactured by GAF Corporation), PermylB-100 (benzophenone compound, manufactured by Ferro Corporation).
The specific examples of the heat-resistant stabilizer blended as an arbitrary component include phenolic antioxidants such as tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate alkyl ester, and 2,2′-oxamidebis[ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]; fatty acid metal salts such as zinc stearate, calcium stearate, and calcium 1,2-hydroxystearate; and polyalcohol fatty acid esters such as glycerin monostearate, glycerin distearate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate. Further, phosphorous stabilizers such as distearyl pentaerythritol diphosphite, phenyl-4,4′-isopropylidene diphenol-pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, and tris(2,4-di-t-butylphenyl)phosphite may be used. These stabilizers may be used in single or in combination with each other. For example, bending of tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, zinc stearate, and glycerin monostearate may be exemplified. Theses stabilizers may be used by blending one kind or two kinds or more.
(Molded Product, Application)
The molded product of the present invention can be molded by a molding method without a limit in particular such as extrusion molding, injection molding, and blow molding. Particularly, the molded product of the present invention is appropriately used for an optical application. For the optical application, optical lenses such as pickup lenses, a transparent seat, an optical disc, and optical fibers are exemplified. Particularly, as for the optical lenses, it is appropriately used for an application of a in-vehicle sensor which requires heat resistance. In addition, the injection molding is suitably used for the optical lens.
A blending method of the ringed olefin-based polymer and other resin components or additives used in the present invention is not limited and a known method can be employed. For example, the method includes simultaneously blending each component.
Next, the present invention is further described with reference to the following examples, but it should be construed that the invention is not limited to those examples. A measuring method of physical property is performed by following methods.
(1) Melt Flow Rate (MFR)
A melt flow rate was measured at 260° C. under a load of 2.16 Kg, in accordance with ASTM D1238.
(2) Glass Transition Temperature (Tg)
A glass transition temperature was measured by heating a sample under the condition of temperature elevation up to 250° C. at a rate of 10° C./min in nitrogen and then cooling quickly to measure the sample at the rate of 10° C./min by using DSC-20 (manufactured by Seiko Denshi Kogyo K.K)
(3) Saturated Water Absorption Ratio
In accordance with ASTM D570, a saturated water absorption ratio was obtained by immersing said molded sheet in distilled water of 23° C. for 1 week, and measuring difference between weight before the immersion and weight after the immersion.
(4) Stress-Optical Coefficient CR
The stress-optical constant was obtained by simultaneously measuring a complex elastic modulus (ER) and a distorted optics ratio (OR) at Tg+10° C. to Tg+30° C. using a press sheet having a thickness of 0.5 mm formed by heat press molding a resin at Tg+100° C. with a viscoelasticity measuring apparatus in combination with the birefringence measuring apparatus and then calculating by the following calculation (I).
CR=OR/ER (I)
(5) Light Beam Transmittance in 405 nm
By the injection molding, a rectangular board having a length of 65 mm, a width of 35 mm, and a thickness of 5 mm was obtained. A light beam transmittance was measured using this rectangular board with an ultraviolet-visible spectrophotometer.
(6) Retardation Value
A retardation value was obtained by measuring a retardation distribution data of the rectangular board in a range of +5 mm of width from the center and in a range of 60 mm of length except by 2.5 mm of both ends from the total length of 65 mm with a KOBRA-CCD/X typed birefringence distribution measuring apparatus manufactured by Oji Scientific Instruments at a wavelength of 590 nm and calculating the average value.
Ethylene-tetracyclo[4.4.0.12,5.17,10]-3-dodecene copolymer was obtained by polymerizing according to a known method using vanadium catalyst (VOCl3). The results of physical properties are shown in table 1.
According to a method disclosed in Japanese Unexamined Patent Publication No. 2002-332312, a complex having a structure of the following Formula (2-A) was obtained.
Ethylene-tetracyclo[4.4.0.12,5.17,10]-3-dodecene copolymer was obtained by polymerizing with this complex as a catalyst and methylaminoxan as an auxiliary catalyst. The results of evaluated physical properties are shown in Table 2.
Ethylene-norbornene copolymer was obtained by polymerizing according to a known method using vanadium catalyst (VOCl3). The results of evaluated physical properties are shown in table 3.
For the polymers obtained in Synthesis Examples 1 to 6, an appearance evaluation and a retardation measurement were performed. The physical properties are shown in table 4.
The present invention can be greatly suitably employed in resins, resin composition and molded products used for optical lenses such as pickup lenses for an optical disc, collimator lens or various lenses for capturing small image, or transparent plastic films for flat panel display having liquid crystal display elements and organic EL display elements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-203333 | Jul 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/11900 | 6/29/2005 | WO | 1/9/2007 |
