JP2011182875A - Resin structure for mirror frame - Google Patents

Abstract

Disclosed is a lens frame resin structure that is excellent in roundness and mechanical strength and has a low environmental load.
A resin structure for a lens frame according to the present invention is formed by molding a composite resin composition containing cellulose nanofibers having an aspect ratio of 10 to 1000000 and an average diameter of 1 to 800 nm in a resin. It is characterized by becoming. The lens frame resin structure is preferably for a camera. The lens frame resin structure preferably has a difference in mold shrinkage between the vertical and horizontal directions of 0.5% or less.
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Description

  The present invention relates to a resin structure for a lens frame.

  Conventionally, in a resin structure for a lens frame, a resin containing glass fiber or carbon fiber is used in order to maintain mechanical strength.

  However, resin structures such as a digital camera frame, a liquid crystal projector frame, a projection TV frame, a telescope frame, and a video camera frame have excellent roundness as well as mechanical strength. It is requested. Since these products have been made thinner, the above-mentioned requirements could not be satisfied using conventional resins.

  In order to solve such problems, (A) 50 to 90% by mass of a thermoplastic resin, (B) 5 to 40% by mass of a round glass fiber (fiber B) having a certain length, and (C) a certain length. The average fiber length of the fibers B in the obtained pellets is 0.16 to 0.40 mm and the average fiber length of the fibers C is obtained by melt-kneading 5 to 40% by mass of flat glass fibers (fibers C). A thermoplastic resin composition in which the thickness is controlled to 0.20 to 0.45 mm has been proposed (see Patent Document 1).

JP 2009-275172 A

The injection-molded body for a lens barrel obtained from the thermoplastic resin composition described in Patent Document 1 is composed of a thermoplastic resin composition reinforced with glass fibers, which has an excellent balance of moldability, elastic modulus and mechanical strength. Excellent roundness, appearance, and mechanical strength.
However, a molded body made of a resin containing glass fiber has poor recyclability and has a residue at the time of waste incineration, which is difficult in terms of high environmental load.

  On the other hand, the conventional molded body made of a resin containing cellulose fiber is good in that the cellulose fiber uses sustainable raw materials, has good recyclability, and has few residues during incineration. However, the strength itself was low, and it could not be used for a lens frame resin structure.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the resin structure for lens frames which is excellent in roundness and mechanical strength, and has a low environmental load.

(1) The resin structure for a lens frame of the present invention is formed by molding a composite resin composition containing cellulose nanofibers having an aspect ratio of 10 to 1000000 and an average diameter of 1 to 800 nm in the resin. It is characterized by.
(2) The resin structure for a lens frame of the present invention is preferably for a camera.
(3) In the lens frame resin structure of the present invention, the difference in mold shrinkage between the vertical direction and the horizontal direction is preferably 0.5% or less.
(4) In the resin structure for a lens frame of the present invention, it is preferable that the cellulose nanofiber has a hydroxyl group chemically modified with a modifying group and has an Iβ type crystal peak in an X-ray diffraction pattern.
(5) The resin structure for a lens frame of the present invention has an X-ray diffraction pattern in which the cellulose nanofiber has a θ range of 0 to 30 and one or two peaks at 14 ≦ θ ≦ 18, and 21 It is preferable to have one peak at ≦ θ ≦ 24 and no other peaks.
(6) It is preferable that the saturated absorption rate in the organic solvent of SP value 8-13 of the said cellulose nanofiber is 300-5000 mass% for the resin structure for lens frames of this invention.
(7) In the resin structure for a lens frame of the present invention, the organic solvent is preferably a water-insoluble solvent.
(8) In the lens frame resin structure of the present invention, 0.01% to 50% of the total hydroxyl groups of the cellulose nanofibers are preferably chemically modified.
(9) In the lens frame resin structure of the present invention, the resin is preferably polycarbonate.
(10) In the resin structure for a lens frame of the present invention, the mass content of the cellulose nanofiber is preferably 10% by mass to 90% by mass.

  According to the lens frame resin structure of the present invention, since it is excellent in roundness and mechanical strength, it is optimally used especially for a camera lens frame, and is easily recyclable because it is easily oiled or repelletized. Is excellent.

It is an X-ray diffraction analysis result of a cellulose nanofiber.

  The lens frame resin structure of the present invention is formed by molding a composite resin composition containing cellulose nanofibers having an aspect ratio of 10 to 1,000,000 and an average diameter of 1 to 800 nm in a resin.

In the lens frame resin structure of the present invention, the cellulose nanofibers contained in the composite resin composition are not particularly limited as long as they have the above-described configuration, and known ones can be used.
Since the cellulose nanofibers are made from plants, the resin that was wasted at the time of injection molding can be oiled, repelletized and reused. On the other hand, in the resin containing glass fiber or carbon fiber, the performance deteriorates and it is difficult to reuse it, and the remaining treatment becomes a problem as a residue at the time of oiling.
Thus, using the lens frame resin structure of the present invention made of the resin containing the cellulose fiber leads to reduction of carbon dioxide emission and is environmentally friendly.

The aspect ratio of the cellulose nanofabric contained in the resin constituting the lens frame resin structure of the present invention is 10 to 1000000 from the viewpoint of the reinforcing effect. More preferably, it is 50-2000. In the present specification and claims, the “aspect ratio” means the ratio of average fiber length to average diameter (average fiber length / average diameter) in cellulose nanofibers.
Since the aspect ratio is within the above range, the cellulose nanofiber has strong entanglement between molecules and a network structure, and imparts mechanical strength to the resin structure for a lens frame.

  The average diameter of the cellulose nanofiber is 1 to 800 nm. The average diameter is more preferably 1 to 300 nm, and further preferably 50 to 200 nm. When the average diameter is 1 nm or more, the production cost does not increase, and when the average diameter is 800 nm or less, the aspect ratio does not decrease and a sufficient reinforcing effect is obtained.

  In the resin structure for a lens frame of the present invention, the difference in mold shrinkage between the vertical direction and the horizontal direction is preferably 0.5% or less. The smaller the difference in shrinkage rate, the more the lens frame resin structure tends to be more round.

  In the lens frame resin structure of the present invention, since the cellulose nanofibers used are uniformly dispersed in the resin at the nano level, there is little anisotropy and excellent roundness. In addition, there is little anisotropy of mechanical properties. Therefore, the lens frame resin structure of the present invention is suitably used for a camera frame.

  Cellulose type I is a composite crystal of Iα type crystal and Iβ type crystal. Cellulose derived from higher plants such as cotton has many Iβ components, but bacterial cellulose has many Iα components. Any of the cellulose fibers used in the present invention may be used, but it is preferable to use the Iβ type as a main component because the reinforcing effect on the resin is high. For this reason, an X-ray diffraction pattern in which the range of θ is 0 to 30 as shown in FIG. 1 in which the type Iα is not confirmed has one or two peaks at 14 ≦ θ ≦ 18, and 21 ≦ θ ≦ 24. Particularly preferred is one having one peak and no other peaks.

The cellulose nanofibers used in the lens frame resin structure of the present invention may be chemically modified in order to enhance functionality. In order to use cellulose nanofiber for the composite material, it is preferable to chemically modify the hydroxyl group on the surface of the cellulose nanofiber with a modifying group to reduce the hydroxyl group. By preventing strong adhesion due to hydrogen bonding between cellulose nanofibers, it can be easily dispersed in a polymer material to form a good interface bond.
The proportion of the total hydroxyl groups in the cellulose nanofiber that is chemically modified by the modifying group is preferably 0.01% to 50%, more preferably 0.1% to 20%. It is further more preferable that it is% -20%. If the modification rate is too high, hydrogen bonds between cellulose nanofibers are lost and the reinforcing effect on the resin is reduced. On the other hand, if the modification rate is too low, the dispersibility of the cellulose nanofibers in the resin is lowered and the reinforcing effect is lowered.

The chemical modification is not particularly limited as long as it reacts with a hydroxyl group. However, cellulose nanofibers etherified and esterified by chemical modification are preferable because they can be easily and efficiently modified.
As the etherifying agent, alkyl halides such as methyl chloride and ethyl chloride; dialkyl carbonates such as dimethyl carbonate and diethyl carbonate; dialkyl sulfates such as dimethyl sulfate and diethyl sulfate; alkylene oxides such as ethylene oxide and propylene oxide are also preferable. Moreover, it is not limited to alkyl etherification, Etherification by benzyl bromide etc., silyl etherification, etc. are preferable. For example, silyl etherification includes alkoxysilane, more specifically n-butoxytrimethylsilane, tert-butoxytrimethylsilane, sec-butoxytrimethylsilane, isobutoxytrimethylsilane, ethoxytriethylsilane, octyldimethylethoxysilane or Examples include alkoxysilanes such as cyclohexyloxytrimethylsilane, alkoxysiloxanes such as butoxypolydimethylsiloxane, and silazanes such as hexamethyldisilazane, tetramethyldisilazane, and diphenyltetramethyldisilazane. Further, silyl halides such as trimethylsilyl chloride, diphenylbutyl chloride, and silyl trifluoromethanesulfonates such as t-butyldimethylsilyl trifluoromethanesulfonate can also be used.
Examples of esterifying agents include carboxylic acids, carboxylic acid anhydrides, and carboxylic acid halides that may contain heteroatoms. Acetic acid, propionic acid, butyric acid, acrylic acid, methacrylic acid, and derivatives thereof are preferred, and acetic acid, anhydrous Acetic acid and butyric anhydride are more preferable.
Among etherification and esterification, alkyl etherification, alkylsilylation, and alkylesterification are preferable in order to improve the dispersibility in the resin.

The cellulose nanofibers chemically modified as described above preferably have a saturated absorption rate in an organic solvent having a solubility parameter (hereinafter referred to as SP value) of 8 to 13 of 300 to 5000% by mass. Cellulose nanofibers dispersed in the organic solvent having the SP value have a high affinity with the resin and a high reinforcing effect.
Organic solvents having an SP value of 8 to 13 include acetic acid, ethyl acetate, butyl acetate, isobutyl acetate, isopropyl acetate, methyl propyl ketone, methyl isopropyl ketone, xylene, toluene, benzene, ethyl benzene, dibutyl phthalate, acetone, isopropanol, acetonitrile Dimethylformamide, ethanol, tetrahydrofuran, methyl ethyl ketone, cyclohexane, carbon tetrachloride, chloroform, methylene chloride, carbon disulfide, pyridine, n-hexanol, cyclohexanol, n-butanol, nitromethane and the like.

  The organic solvent is preferably a water-insoluble solvent (a solvent that does not mix with water at 25 ° C. in any proportion), and includes xylene, toluene, benzene, ethylbenzene, methylene chloride, cyclohexane, methylene chloride, ethyl acetate, Examples thereof include carbon chloride, carbon disulfide, cyclohexanol, nitromethane and the like. Among these, methylene chloride in which polycarbonate is dissolved is particularly good.

  The composite resin composition used for the lens frame resin structure of the present invention contains the cellulose nanofibers in the resin. Therefore, the resin structure for a lens frame of the present invention is excellent in strength and heat resistance due to the excellent reinforcing effect of the cellulose nanofiber.

  The type of resin in the composite resin composition may be a thermoplastic resin or a thermosetting resin. Plant-derived resins, resins made from carbon dioxide, ABS resins, alkylene resins such as polyethylene and polypropylene, styrene resins, vinyl resins, acrylic resins, amide resins, acetal resins, carbonate resins, urethane resins, epoxy resins, imide resins And urea resin, silicone resin, phenol resin, melamine resin, ester resin, acrylic resin, amide resin, fluororesin, styrene resin, engineering plastic, and the like. Engineering plastics include polyamide, polybutylene terephthalate, polycarbonate, polyacetal, modified polyphenylene oxide, modified polyphenylene ether, polyphenylene sulfide, polyether ether ketone, polyether sulfone, polysulfone, polyamideimide, polyetherimide, polyimide, polyarylate. Polyallyl ether nitrile and the like are preferably used. Two or more of these resins may be mixed. Among these, polycarbonate is particularly good because of its high impact strength, and a lens frame resin structure having excellent mechanical strength can be obtained by using the polycarbonate composite resin composition containing the cellulose nanofibers.

  As the polycarbonate, those usually used can be used. For example, an aromatic polycarbonate produced by a reaction between an aromatic dihydroxy compound and a carbonate precursor can be preferably used.

  Examples of the aromatic dihydroxy compound include 2,2-bis (4-hydroxyphenyl) propane (“bisphenol A”), bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 4,4′-dihydroxydiphenyl, bis (4-hydroxyphenyl) cycloalkane, bis (4-hydroxyphenyl) sulfide, bis (4- Hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ketone.

  Examples of the carbonate precursor include carbonyl halide, carbonyl ester, and haloformate. Specific examples include phosgene, dihaloformate of dihydric phenol, diphenyl carbonate, dimethyl carbonate, and diethyl carbonate.

Moreover, as a polycarbonate used for this invention, the polycarbonate which does not contain an aromatic may be sufficient. Examples of the polycarbonate not containing aromatics include alicyclic polycarbonates and aliphatic polycarbonates. The polycarbonate resin may be linear or branched. Moreover, the copolymer of the polymer obtained by superposing | polymerizing the said aromatic dihydroxy compound and a carbonate precursor, and another polymer may be sufficient.
The polycarbonate resin can be produced by a conventionally known method. Examples thereof include various methods such as an interfacial polymerization method, a melt transesterification method, and a pyridine method.

The composite resin composition used in the lens frame resin structure of the present invention is additionally provided with additives such as fillers, flame retardant aids, flame retardants, antioxidants, mold release agents, colorants, and dispersants. Also good.
Examples of the filler include carbon fiber, glass fiber, cellulose fiber, clay, titanium oxide, silica, talc, calcium carbonate, potassium titanate, mica, montmorillonite, barium sulfate, balloon filler, bead filler, and carbon nanotube.
As the flame retardant, halogen flame retardant, nitrogen flame retardant, metal hydroxide, phosphorus flame retardant, organic alkali metal salt, organic alkaline earth metal salt, silicone flame retardant, expansive graphite and the like can be used.
As the flame retardant aid, polyfluoroolefin, antimony oxide or the like can be used.
As antioxidant, phosphorus antioxidant, phenolic antioxidant, etc. can be used.
Examples of the release agent include higher alcohols, carboxylic acid esters, polyolefin waxes, and polyalkylene glycols.
As the colorant, any colorant such as carbon black or phthalocyanine blue can be used.
The dispersant is not particularly limited as long as cellulose nanofibers can be dispersed in the resin, and examples thereof include anionic, cationic, nonionic and amphoteric surfactants, polymer-type dispersants, and combinations thereof.

In the lens frame resin structure of the present invention, the mass content of the cellulose nanofibers in the resin is preferably 10% by mass to 90% by mass, and more preferably 10% by mass to 60% by mass.
When the amount is less than 10% by mass, the mechanical strength of the resin decreases, and when the amount exceeds 90% by mass, the fluidity often decreases.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to a following example.

Example 1
2 g of a filter paper cut into 3 mm squares with scissors was placed in a 200 ml flask beaker, and 50 ml of N, N-dimethylacetamide and 60 g of ionic liquid 1-butyl-3-methylimidazolium chloride were added and stirred. Next, this was filtered to obtain cellulose nanofibers, which were further acetylated with acetic anhydride. The modification rate of the acetylated cellulose nanofiber obtained at this time was 10%. Next, the polycarbonate previously dissolved in methylene chloride and this acetylated cellulose nanofiber were mixed in dichloromethane and dried to obtain a polycarbonate composite resin composition containing cellulose nanofibers uniformly dispersed therein.

(Example 2)
A polycarbonate composite resin composition containing cellulose nanofibers uniformly dispersed was obtained in the same procedure as in Example 2 except that acetic anhydride was used in an amount twice that of Example 1. The modification rate of the cellulose nanofiber obtained at this time was 18%.

(Example 3)
A polycarbonate composite resin composition containing cellulose nanofibers uniformly dispersed was obtained in the same procedure as in Example 2 except that hexamethyldisilazane was added as a silylating agent instead of acetic anhydride. The modification rate of the cellulose nanofiber obtained at this time was 15%.

(Comparative Example 1)
As a polycarbonate composite resin composition, Panlite G-3120PH (glass fiber content 20 mass%) manufactured by Teijin Ltd. was used.

(Comparative Example 2)
As a polycarbonate composite resin composition, Panlite EN-8515N (carbon fiber content 15 mass%) manufactured by Teijin Ltd. was used.

The molded products of each Example and each Comparative Example were measured by the following test methods, and the results are shown in Table 1.
(1) Aspect ratio, average diameter The number average fiber diameter and number average length of Examples 1 to 3 were evaluated by SEM analysis.
Specifically, various fiber dispersions are cast on a wafer and observed with an SEM, and fiber diameters and length values are read for 20 or more fibers per obtained image, and at least three overlaps are read. An image of the unexposed region was performed, and information on a minimum of 30 fiber diameters and lengths was obtained.
The number average fiber diameter and length can be calculated from the fiber diameter and length data obtained as described above, and the aspect ratio was calculated from the ratio between the average fiber length and the fiber diameter.

(2) Crystal structure analysis (XRD)
The crystal structures of Examples 1 to 3 were analyzed using a powder X-ray diffractometer Rigaku Ultima IV. The X-ray diffraction pattern has one or two peaks at 14 ≦ θ ≦ 18 and one peak at 21 ≦ θ ≦ 24. If there is no other peak, ○, otherwise Was judged as Δ.

(3) Evaluation method of hydroxyl group modification rate A1 The modification rate of the hydroxyl group was calculated from the element ratios of carbon, hydrogen, and oxygen obtained by elemental analysis.

(4) Evaluation of Saturated Absorption Rate R Cellulose nanofibers with a weight (W1) are dispersed in dichloromethane (SP value 9.7) to prepare a 2 wt% dispersion, put into a centrifuge bottle, and then 30 for 4500G. After the partial treatment, the weight (W2) of the lower gel layer was measured after removing the upper transparent solvent layer, and the saturated absorption rate was calculated by the following formula.
R = W2 / W1 × 100%
Example 2 was evaluated using two solvents: ethyl acetate (SP value 9.1) and dichloromethane (SP value 9.7). At this time, ethyl acetate was 1200 mass% and dichloromethane was 1500 mass%.
When the saturated absorption rate was 300 or more and 5000% by mass or less, it was judged as ◯, and when it was not, it was judged as Δ.

(5) Mass content The mass content of the cellulose nanofiber of each Example was shown.

  As shown in Table 1, the examples have an aspect ratio of 10 or more and 1000000 or less, an average diameter of 1 to 300 nm, an Iβ type crystal type X-ray diffraction pattern, and a chemical modification rate of 10% to 20%. %Met.

The molded products of each Example and each Comparative Example were measured by the following test methods, and the results are shown in Table 2.
(1) Bending strength The bending strength of the molded bodies of Examples 1 to 3 was measured with a three-point bending tester. Catalog values were used for Comparative Examples 1 and 2.

(2) Difference in shrinkage rate
Resin was molded according to JISK7152-4, and the shrinkage rate parallel to the flow direction and the shrinkage rate perpendicular to the flow direction were measured, and the difference was calculated. When the difference was 0.5% or less, it was judged as “good”, and otherwise, it was judged as “poor”.

(3) Roundness With a CNC three-dimensional measuring instrument LEGEX manufactured by MITSUTOYO, roundness was measured on the inscribed surface of the cylindrical shaped body according to the measurement program. A value of 300 μm or less was evaluated as “◯”, and a value higher than that was determined as “X”.

(4) Environmental compatibility In each example and each comparative example, it was judged as ○ when a sustainable raw material was used, and × when it was not.

  As shown in Table 2, the molded products obtained in the examples have good shrinkage differences and roundness. Moreover, it is excellent in bending strength and has little mechanical property anisotropy. Furthermore, compared with the comparative example 1 and the comparative example 2, Examples 1-3 used the sustainable raw material called wood, and were excellent in environmental compatibility. From these results, the resin structure of the present invention is more suitable for a lens frame than a structure using glass fiber or carbon fiber.

Claims (10)

  A lens frame resin structure obtained by molding a composite resin composition containing cellulose nanofibers having an aspect ratio of 10 to 1,000,000 and an average diameter of 1 to 800 nm in a resin.   The resin structure for a lens frame according to claim 1, which is for a camera.   The resin structure for a lens frame according to claim 1 or 2, wherein a difference in mold shrinkage between the vertical direction and the horizontal direction is 0.5% or less.   The resin structure for a lens frame according to any one of claims 1 to 3, wherein the cellulose nanofiber has a hydroxyl group chemically modified with a modifying group and has an Iβ-type crystal peak in an X-ray diffraction pattern.   The cellulose nanofiber has an X-ray diffraction pattern in which the range of θ is 0 to 30 and has one or two peaks at 14 ≦ θ ≦ 18 and one peak at 21 ≦ θ ≦ 24. The resin structure for a lens frame according to claim 4, which has no peak.   6. The resin structure for a lens frame according to claim 4, wherein the cellulose nanofibers have a saturated absorptance in an organic solvent having an SP value of 8 to 13 of 300 to 5000 mass%.   The resin structure for a lens frame according to claim 6, wherein the organic solvent is a water-insoluble solvent.   The resin structure for a lens frame according to any one of claims 4 to 7, wherein 0.01% to 50% of the total hydroxyl groups of the cellulose nanofibers are chemically modified.   The resin structure for a lens frame according to any one of claims 1 to 8, wherein the resin is polycarbonate.   The resin structure for a lens frame according to any one of claims 1 to 9, wherein a mass content of the cellulose nanofiber in the resin is 10% by mass to 90% by mass.

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