JP2001124912A - Optical reflecting member made of thermoplastic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical reflective member made of a thermoplastic resin having an optical reflective surface of superior specular reflection. SOLUTION: This optical reflecting member 10, made of a thermoplastic resin, has a rectangular planar optical reflecting surface 13 surrounded by a projecting part 12, a hollow part 14 is formed in the part of an optical reflecting member 11 constituting the entire region of the optical reflective surface 13, by introducing a pressurized fluid and a hollow part 14A extended from the part of the optical reflecting member constituting the entire region of the optical reflective surface is formed in a part of the part of the optical reflecting member constituting the projecting part 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical reflecting member made of a thermoplastic resin and having a rectangular flat optical reflecting surface with extremely excellent mirror finish.

[0002]

2. Description of the Related Art Optical reflecting members such as optical scanning reflectors used in digital equipment such as copiers and laser beam printers have conventionally been manufactured using glass. From the viewpoint of the degree of freedom of the shape due to the improvement of the required functionality, the transition to a thermoplastic resin is progressing.

[0003] Generally, as a method of manufacturing a molded article made of a thermoplastic resin, a mold having a cavity is used.
An injection molding method has been used in which a molten thermoplastic resin is injected and filled into a cavity of a mold maintained at a constant temperature, and the thermoplastic resin in the cavity is cooled and solidified. However, such as an optical reflection member, (1) a thick molded product, (2) a molded product having an uneven thickness portion, or (3)
In the case of molding a long molded product, (1) and (2) correspond to the portion between the thick portion and the thin portion of the molded product, and (3) corresponds to the center portion and the end portion. As a result, there is a difference in the cooling rate of the molten thermoplastic resin in the cavity, and as a result, distortion tends to occur in the molded product. Therefore,
There is a problem that it is difficult to transfer the mold surface of the cavity having high mirror finish to the molded product with high accuracy, that is, it is difficult to enhance the mirror transfer accuracy.

[0004] In order to improve the mirror surface transfer accuracy in this type of molded article molding method, for example, the following measures have been conventionally adopted.

Injection compression molding method After injecting and filling a molten thermoplastic resin into a cavity of a mold heated to a glass transition temperature T _g or more of the thermoplastic resin, a gate portion is sealed, and the temperature is reduced to a temperature equal to or lower than a thermal deformation temperature. A molding method in which the thermoplastic resin in the cavity is gradually cooled and the molded product is taken out when the resin pressure in the cavity becomes 0 Pa (0 kg / cm ² -G) (see Japanese Patent Application Laid-Open No. 64-38421). the resin matrix was before processing into a final shape, again heated above the glass transition temperature T _g of the matrix resin in a separate mold, slow cooling molding method to heat deformation temperature or less (JP-a-4-1631
No. 19) The material and surface roughness of two opposing mold surfaces provided in the cavity are changed, and the cavity is filled with the molten thermoplastic resin immediately before the cavity is completely filled with the molten thermoplastic resin. After the injection of the mold is completed, the thermoplastic resin in the cavity is cooled and solidified without applying pressure, thereby improving the adhesion of the mold surface on which the optical reflecting surface of the optical reflecting member is to be formed to the thermoplastic resin. A method of making the surface higher than the other mold surface (Japanese Patent Publication No. Hei 6-98642,
While the mold surface of the cavity in which the optical reflecting surface of the optical reflecting member is to be formed is maintained at a temperature equal to or higher than the thermal deformation temperature of the thermoplastic resin, the other mold surfaces are cooled to obtain a thermoplastic resin. Molding method for generating resin sink marks intensively on other mold surfaces (refer to the Journal of the Japan Society for Molding Engineering '94, P237-P240)

[0006]

However, in the above method, it is difficult to obtain sufficient mirror-like transfer accuracy depending on the size of the shape of the optical reflecting member and the distribution of uneven thickness. In the methods (1) and (2), since the cooling is performed, the molding cycle is lengthened, and the productivity is reduced. In addition, in order to improve productivity, there are economical problems such as separate processes in which each of filling, slow cooling, and unloading processes can be continuously performed, and a need for a plurality of molds with high mirror surface accuracy. . In the method of (1), the adhesive force is reversed depending on the material of the mold portion constituting each mold surface (transfer surface and rough surface) of the cavity or the thermoplastic resin used, and the optical reflection surface of the optical reflection member is changed. Sinks occur in the portion of the thermoplastic resin that is in contact with the mold surface on which is to be formed. Further, when the timing of stopping the filling of the molten thermoplastic resin is shifted, the relationship between the adhesiveness between the molten thermoplastic resin and the mold surface is reversed, and the mold surface on which the optical reflecting surface of the optical reflecting member is to be formed. Sinking occurs in the portion of the thermoplastic resin that is in contact, or the amount of the molten thermoplastic resin to be filled in the cavity becomes insufficient. In the method of
There is a problem of stability such that the optical reflection member is warped due to a mold temperature difference.

Accordingly, an object of the present invention is to provide an optical reflecting member made of a thermoplastic resin having a rectangular flat optical reflecting surface which is very excellent in mirror finish.

[0008]

An optical reflecting member according to the present invention for achieving the above object has a rectangular planar optical reflecting surface, and the rectangular planar optical reflecting surface has a projection. A hollow portion is formed by introducing a pressurized fluid into a portion of the optical reflecting member made of a thermoplastic resin surrounded by In addition, a hollow portion extending from a hollow portion formed in a portion of the optical reflecting member forming the entire area of the optical reflecting surface is formed in a part of the optical reflecting member forming the protrusion. It is characterized by the following.

The optical reflection member of the present invention uses, for example, an injection molding die provided with a cavity having a die surface for forming an optical reflection surface, and (a) a molten thermoplastic resin. And (b) introducing a pressurized fluid into the molten thermoplastic resin in the cavity,
A hollow portion is formed in the portion of the optical reflecting member that forms the entire area of the optical reflecting surface, and an optical part that forms the entire area of the optical reflecting surface in a part of the portion of the optical reflecting member that forms the protrusion. Forming a hollow portion extending from the exposed hollow portion of the reflecting member; and (c) adjusting the pressure in the hollow portion to a desired pressure range until the thermoplastic resin in the cavity is solidified and cooled. And (d) after removing the pressurized fluid in the hollow portion, opening the mold, and taking out the optical reflecting member. In addition, such a manufacturing method for manufacturing the optical reflecting member of the present invention may be hereinafter referred to as an optical reflecting member manufacturing method for convenience.

[0010] In the optical reflecting member made of the thermoplastic resin of the present invention (hereinafter, sometimes simply referred to as the optical reflecting member of the present invention), the rectangular planar optical reflecting surface is surrounded by the projection. In addition, a part of the optical reflection member constituting the projection (which may be referred to as a projection component) may be partially provided with an optical reflection member constituting the entire area of the optical reflection surface (the optical reflection surface component). , Which may be referred to as).
It is possible to reliably prevent the specularity of the optical reflecting surface in the optical reflecting surface constituting portion near the projection from deteriorating, and to maintain the side surface of the projecting portion facing the optical reflecting surface constituting portion with high surface accuracy. it can. If the projection is not provided, a hollow portion can be formed only in a part of the optical reflection surface constituting portion, and the optical reflection surface cannot be protected by the projection. Further, in the optical reflecting member of the present invention,
Since the hollow portion is formed in the portion of the optical reflecting surface component member, that is, when molding the optical reflecting member, the contraction of the thermoplastic resin in the optical reflecting surface component portion is formed by introducing a pressurized fluid. Since the hollow portion is suppressed, it is possible to obtain an optical reflecting member having extremely excellent mirror finish over the entire optical reflecting surface.

In the optical reflecting member according to the present invention, when the optical reflecting member is cut along a virtual plane including the optical reflecting surface, the outer shape of the optical reflecting member is rectangular, and the rectangular planar optical reflection member is formed. The width of the portion of the optical reflection member constituting the projection along the direction parallel to the short side of the surface is W ₁ , and the optical reflection constituting the projection along the direction parallel to the short side of the optical reflection surface The length of the hollow formed in a part of the member
_When it is set to ₂ , it is desirable to satisfy 0.01 ≦ W ₂ / W ₁ ≦ 0.8, preferably 0.01 ≦ W ₂ / W ₁ ≦ 0.5. When the value of W ₂ / W ₁ satisfies the lower limit of the above range, it is possible to more surely prevent the occurrence of sink marks on the optical reflecting surface in the optical reflecting surface constituting portion near the protrusion. By satisfying the upper limit of the range
The strength of the projection can be maintained. Furthermore, assuming that the width of the optical reflecting member along a direction parallel to the short side of the rectangular planar optical reflecting surface is W ₀ , 0.1 ≦ W ₁ / W ₀ ≦
0.3, preferably 0.1 ≦ W ₁ / W ₀ ≦ 0.25, and more preferably 0.1 ≦ W ₁ / W ₀ ≦ 0.2. When the value of W ₁ / W ₀ satisfies the lower limit of the above range, it is possible to more reliably prevent sinks from occurring on the optical reflection surface in the optical reflection surface constituting portion near the protrusion. If the value of W ₁ / W ₀ does not satisfy the upper limit of the above range, the ratio of the optical reflecting surface occupying the optical reflecting member becomes too small, which is not practical. When the thickness of the portion of the optical reflecting member constituting the entire area of the optical reflecting surface is t ₀ , 1 ≦ t ₀ / W ₁ ≦ 10, preferably 2 ≦ t ₀ /
It is desirable to satisfy W ₁ ≦ 5, more preferably 2 ≦ t ₀ / W ₁ ≦ 4.

In the optical reflecting member of the present invention, the rectangular
The length of the long side of the planar optical reflecting surface is L₁, Short side length
To L_TwoAnd L₁/ L_TwoThe value of is essentially arbitrary
However, in practice, the characteristics of the optical reflecting member of the present invention
From the viewpoint of taking advantage of ₁/ L_Two≧ 2, preferably
L₁/ L_Two≧ 3, more preferably L₁/ L_TwoSatisfies ≧ 4
It is desirable.

In the method for manufacturing an optical reflecting member, the desired pressure range in the step (c) is a gauge pressure of 1 × 1.
0 ⁵ Pa (1 kgf / cm ² -G) or more and 5 × 10 ⁶ Pa
(5 × 10 kgf / cm ² -G) or less, more preferably, 1.2 × 10 ⁵ Pa (1.2 kgf /
cm ² -G) or more and 4 × 10 ⁶ Pa (4 × 10 kgf / cm)
^2- G) or less, more preferably, 2.0 × at gauge pressure.
10 ⁵ Pa (2.0 kgf / cm ² -G) or more 2.5 × 1
^{0 6 Pa (2.5 × 10kgf /} cm 2 -G) is preferably set to less. When a hollow portion is formed in a part of the optical reflecting surface component and the projection component, the contraction of the thermoplastic resin in the optical reflecting surface component and the projection component is caused by the introduction of the pressurized fluid. It is sufficient to maintain the inside of the hollow portion at a pressure sufficient to bear on the side of the hollow portion. Therefore, the pressure in the hollow portion may be maintained within a desired pressure range of such a relatively low pressure. The desired pressure range (hereinafter,
If the gauge pressure is 1 × 10 ⁵ Pa or more, a hollow portion can be reliably formed in a part of the optical reflecting surface constituting portion and the projecting portion constituting portion. On the other hand, by setting the desired pressure range to 5 × 10 ⁶ Pa or less, the pressure for pressing the molten thermoplastic resin in the cavity from the hollow portion against the mold surface for forming the optical reflection surface becomes thermoplastic. It is unlikely that an excessive pressure exceeding the pressure responsible for the contraction of the resin will occur, a residual stress will not easily occur in the optical reflecting member, and there is little problem in releasing the optical reflecting member from the mold. As a result, the specularity of the optical reflection surface of the optical reflection member is less likely to be impaired.

In the method for manufacturing an optical reflecting member, the desired pressure range in the step (c) is adjusted by (A) the pressure of the pressurized fluid for pressurizing the hollow portion until the thermoplastic resin in the cavity is solidified and cooled. May be controlled by
(B) It may be controlled by the volume of the pressurized fluid introduced in the step (b), or (C) the mold may further include a movable core, and may be controlled by position control of the movable core.
In the method (C), specifically, the volume of the optical reflecting member and further the volume of the hollow portion are increased by the movement of the movable core.

In the optical reflecting member of the present invention, an injection molding die provided with a cavity having a die surface for forming an optical reflecting surface is used, and the optical molding formed in the cavity is performed. It is preferable that there is only a gap of 1 μm or less per 10 mm ² of the optical reflection surface between the optical reflection surface of the reflection member and a mold surface for forming the optical reflection surface.

In the optical reflection member of the present invention, the volume occupied by the portion of the optical reflection member constituting the projection (the volume of the projection component, and the volume of the hollow portion formed in a part of the projection component) Is the volume of the optical reflecting member (the volume of the optical reflecting surface constituent part, the volume of the hollow part formed in such part, the volume of the protruding part constituent part, and the hollow formed in a part of such part. 1) of 1)
It is desirably 30%, preferably 1 to 15%.

In the optical reflecting member of the present invention, the warping ratio W of the optical reflecting surface is 1 × 10 ⁻³ or less (0.1% or less).
It is preferred that The warpage ratio W of the optical reflecting surface is assumed to be a line segment (length L) connecting any two points on the edge of the optical reflecting surface, and the optical reflection from the line segment is performed along the line segment. measuring the distance to the surface (D), the maximum value of the distance D _{MA X}
Can be represented by the following equation. When the warp ratio W (L) is 1 × 10 ⁻³ or less for an arbitrary line segment, “the warp ratio of the optical reflecting surface is 1 × 10 ⁻³ or less”
And

[Equation 1] W (L) = D _MAX / L

In the mold used in the method for manufacturing an optical reflecting member, a resin injection portion (so-called gate portion) for injecting the molten thermoplastic resin into the cavity is provided for forming an optical reflecting surface. If it is a part of the mold other than the mold surface,
In particular, it can be provided without any positional restrictions. In addition, depending on the structure of the mold, for example, when manufacturing a rectangular optical reflection member, the molten thermoplastic resin injected into the cavity,
It is desirable to dispose the resin injection part in the mold so that the resin flows from the short side to the long side of the optical reflection surface.

In the mold used in the method for manufacturing the optical reflecting member, the pressurized fluid introducing portion is also particularly positioned if it is a part of the mold other than the mold surface for forming the optical reflecting surface. It can be provided without any restrictions. Specifically, the pressurized fluid introduction unit may be arranged near the resin injection unit, may be arranged separately from the resin injection unit, or may be arranged inside the resin injection unit. In addition, the number of pressurized fluid introduction sections is not limited.

The pressurized fluid used is a gaseous substance at normal temperature and normal pressure, and it is desirable that the fluid does not react with or mix with the thermoplastic resin used. Specifically, nitrogen gas, air, carbon dioxide gas, helium and the like can be mentioned, but from the viewpoint of safety and economy, nitrogen gas and helium gas are preferable. The timing of starting the introduction of the pressurized fluid into the molten thermoplastic resin in the cavity is preferably 0.1 second to 25 seconds from the start of the injection of the molten thermoplastic resin into the cavity. The lower limit of the introduction start time of the pressurized fluid is that when the pressurized fluid is introduced into the molten thermoplastic resin in the cavity while the molten thermoplastic resin is being injected into the cavity, the introduced pressurized fluid is The time may be set so that the molten thermoplastic resin is not blown off. On the other hand, if the introduction start time of the pressurized fluid exceeds 25 seconds, a desired hollow portion cannot be formed due to solidification of the molten thermoplastic resin in the cavity, and sinks occur on the optical reflection surface, and the mirror surface of the optical reflection surface May impair the performance. The timing of starting the introduction of the pressurized fluid into the molten thermoplastic resin in the cavity may be during injection of the molten thermoplastic resin into the cavity, simultaneously with the completion of the injection, or after the completion of the injection.

The volume of the molten thermoplastic resin to be injected into the cavity may be any volume that can mold a desired optical reflecting member, and depends on the volume occupied by the hollow portion in the optical reflecting member. That is, the volume of the molten thermoplastic resin to be injected into the cavity may be a volume that completely fills the cavity or a volume that does not completely fill the cavity. If desired, an overflow portion into which excess molten thermoplastic resin flows from the cavity may be provided in the mold in communication with the cavity, and the entire optical reflection surface may be formed as a hollow portion.

The thermoplastic resin constituting the optical reflecting member of the present invention may be any thermoplastic resin, such as a polycarbonate resin; an olefin resin such as a polyethylene resin and a polypropylene resin; a polystyrene resin, an AS resin, and an ABS resin. Styrene resin such as AES resin; PM
Methacrylic resin such as MA resin; polyoxymethylene (polyacetal) resin; polyamide 6, polyamide 6
6, polyamide resins such as polyamide MXD; modified polyphenylene ether (PPE) resin; polyphenylene sulfide resin; polyethylene terephthalate (PE
T) Resins, polyester resins such as polybutylene terephthalate (PBT) resins, etc .; thermoplastic resins such as liquid crystal polymers; or polymer alloys comprising at least two or more of these thermoplastic resins. Among them, it is preferable to use a thermoplastic resin selected from the group consisting of a polycarbonate resin, a polyamide resin, a polyphenylene ether resin, a polyester resin, and a polymer alloy resin composition of a polycarbonate resin / polyester resin.

As the polycarbonate resin, it is desirable to use an aromatic polycarbonate. In particular,
2,2 bis (4-hydroxyphenyl) -propane, 2,
A polymer obtained by a known method from one or more divalent phenolic compounds exemplified by 2-bis (3,5-dibromo-4-hydroxyphenyl) propane and a carbonate precursor exemplified by phosgene Can be exemplified. Particularly, in the optical reflecting member of the present invention, in addition to high rigidity and transparency, heat resistance and impact resistance are required.
An aromatic polycarbonate resin having a viscosity average molecular weight of 15,000 to 30,000 calculated from the melt viscosity of methylene chloride at 5 ° C. is preferable.

The thermoplastic resin constituting the optical reflection member of the present invention may be mixed with a dye in order to give an arbitrary color tone. For example, azo dyes, cyanine dyes,
It can be selected from those usually used for coloring thermoplastic resins, such as quinoline dyes and perylene dyes. The compounding amount may be appropriately selected, for example, within a range that does not impair transparency. Further, within a range that does not impair the object of the present invention, for example, an effective expression amount of a stabilizer, a release agent, and an ultraviolet absorber may be blended in the thermoplastic resin.

In the optical reflecting member of the present invention, an optical reflecting film may be provided on the surface of the optical reflecting surface. In the method for manufacturing an optical reflecting member, after the step (d), an optical reflecting film may be formed on the surface of the optical reflecting surface. The thickness of the optical reflection film may be any thickness that can effectively reflect light, and is at least 50 nm, preferably 50 nm to 500 nm, and more preferably 100 n.
m to 300 nm is desirable. If the thickness is less than 50 nm, the reflectance may not be sufficient.
If it exceeds 500 nm, the surface smoothness of the optical reflection surface is reduced, and a problem may occur in the mirror surface.

As materials constituting the optical reflection film, for example, gold, platinum, silver, chromium, nickel, phosphorus nickel,
Examples thereof include metals such as aluminum, copper, beryllium, beryllium copper, and zinc, and metal compounds and alloys thereof. As the film forming method, (a) various kinds of vacuum evaporation methods such as an electron beam heating method, a resistance heating method, and flash evaporation; (b) a plasma evaporation method; (c) a bipolar sputtering method, a DC sputtering method, a DC magnetron sputtering method, and a high-frequency sputtering method Methods, magnetron sputtering method, ion beam sputtering method, bias sputtering method, etc. (d) DC (direct current) method, RF method, multi-cathode method, activation reaction method, electric field evaporation method, high frequency ion plating method PVD (Physical Vapor Depositio), such as various ion plating methods such as reactive ion plating
n) Method can be mentioned. In terms of reflectivity and cost,
Most preferably, the optically reflective film is formed from an aluminum vapor-deposited film obtained by vacuum-depositing aluminum.

The optical reflecting member of the present invention thus obtained is required to have high specularity, dimensional accuracy, light weight, safety, durability, and economy, and is required for electric and electronic parts, automobile parts, medical use, and security. It is an optical reflecting member suitable for many uses, such as for building, building materials, and household goods. As an embodiment of the optical reflection member of the present invention, a mirror can be given. More specifically, a roof mirror for a camera, an optical system mirror for a copying machine,
An optical system mirror such as a polygon mirror for a laser beam printer can be exemplified.

[0029]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Next, the present invention will be described. In Examples and Comparative Examples
The optical reflection member made of thermoplastic resin to be manufactured is
An optical reflection mirror for a beam printer was used. As a rule
The optical reflecting member has a rectangular planar optical reflecting surface.
The rectangular planar optical reflecting surface is surrounded by protrusions.
ing. Here, the optical plane is a virtual plane including the optical reflection surface.
The outer shape of the optical reflection member when the reflection member is cut is
It is rectangular and parallel to the short side of the rectangular planar optical reflection surface.
Part of the optical reflection member that constitutes the protrusion along the direction
Width W₁Was set to 2 mm. In addition, rectangular planar optical reflection
Length L of the long side of the surface₁Is 233 mm and the length of the short side is L_Two10
mm. Further, regarding the outer dimensions of the optical reflecting member,
In the direction parallel to the short side of the rectangular planar optical reflection surface.
The width W of the optical reflector along ₀Is 14 mm
Optical along a direction parallel to the long side of the planar optical reflecting surface
The length of the reflecting member was 290 mm. W₁/ W₀= 0.1
4. In addition, the thickness t of the optical reflection surface constituting portion₀6
mm. Note that the measurement of the planar accuracy of the optical reflecting surface is performed by 1
Evaluation of interference fringes using 0 mm diameter optical flat
Done by valuing. The measurement site is
Centered. The evaluation results show that the number of observed interference fringes is 5 or less.
The lower case is marked with “◎” and the number of interference fringes is 6 or more and 10 or less.
Indicates the case where the interference fringes are 11 or more and 20 or less.
"△" mark, when there are 21 or more interference fringes, "x" mark
Was.

FIG. 1A is a schematic side view of the optical reflecting member 10 in the long side direction.
FIG. 1B is a schematic cross-sectional view of the optical reflecting member 10 cut along a vertical plane including the bisector of the short side of FIG.
FIG. 1 is a schematic cross-sectional view of the optical reflecting member 10 in a short side direction (FIG. 1).
(A) is a schematic cross-sectional view taken along the line CC of FIG.

The optical reflecting member 10 has one (one) optical reflecting surface 12 in the form of a rectangular plane, and constitutes the entire optical reflecting surface of the optical reflecting member 10. (Optical reflection surface constituting portion) 11 is formed with a hollow portion 14 by introducing a pressurized fluid. The rectangular planar optical reflection surface 12 is surrounded by the projection 13. Further, a hollow portion 14 formed in the optical reflection surface constituting portion 11 is provided in a portion 13A of the portion of the optical reflecting member (projecting portion constituting portion) constituting the projecting portion 13.
And a hollow portion 15 extending from the hole. On the other hand, on the right-hand side of the protrusion 13 on the right-hand side of the optical reflection surface constituting portion 11 of the optical reflection member 10, marks (marks of the resin injection portion) 16 where the molten thermoplastic resin is injected, and pressure A trace 17 where the fluid is introduced (a trace of the pressurized fluid introduction part) remains.

(Example 1) In Example 1, an injection molding machine provided with an injection molding die 20 whose schematic sectional view is shown in FIG. 2 was used. Except for the heating cylinder 26, the components of the injection molding machine are not shown. Mold 20
Is composed of a fixed mold portion 21 having a cavity 24 and having a nest 23 forming a mold surface for forming the optical reflection surface 12, and a movable mold portion 22. When the fixed mold part 21 and the movable mold part 22 are clamped, a cavity 24 is formed. The mold 20 has a cavity 24
A resin injection section 25 is provided, which is open to the outside. The resin injection section 25 communicates with a heating cylinder 26. Further, a pressurized fluid introduction unit 27 is provided in the resin injection unit 25, and one end of the pressurized fluid introduction unit 27 is opened in the resin injection unit 25. On the other hand, the other end of the pressurized fluid introducing section 27 is connected to a pressurized fluid source 28. A check valve (not shown) is provided between the other end of the pressurized fluid introduction unit 27 and the pressurized fluid source 28 so that the pressurized fluid in the hollow portion faces the pressurized fluid source 28. And does not flow backward. The resin injection section 25 is a part of the optical reflecting surface component 1 of the optical reflecting member 10.
The mold is arranged such that the molten thermoplastic resin is injected into a cavity for forming a portion of the optical reflection member other than 1. That is, the resin injection section (gate section) 25
The optical reflection surface is not formed depending on the mold surface near. Nest 23, fixed mold part 21, and movable mold part 22
Was made from a stainless steel based material. Nesting 2
The surface roughness _Ry of the mold surface of No. 3 was set to 0.01 μm. still,
Surface measurement of roughness R _y are analogous JISB0601.

In Example 1, an SH-100 injection molding machine manufactured by Sumitomo Heavy Industries, Ltd. was used as the injection molding machine, and the heating cylinder 26 was heated to 280 ° C.
20 ° C. As the thermoplastic resin, a polycarbonate resin having a viscosity average molecular weight of 21500 (trade name: Iupilon S-3000R, manufactured by Mitsubishi Engineering-Plastics Corporation), which is a thermoplastic resin for injection molding, was used. Nitrogen gas was used as the pressurized fluid.

In the first embodiment, the thermoplastic resin is supplied into the heating cylinder 26,
After being kneaded and plasticized in 6 and melted, the molten thermoplastic resin 30 was injected into the cavity 24 of the mold 20 via the resin injection section 25. FIG. 3 schematically shows a state in which the molten thermoplastic resin 30 is being injected. The injection time is 1 second, and the volume of the injected molten thermoplastic resin is 8 times the volume of the cavity 24.
0%. And the cavity 24 of the molten thermoplastic resin.
Simultaneously with the completion of the injection into the inside, the pressurized fluid is introduced into the molten thermoplastic resin 30 in the cavity 24 from the pressurized fluid introduction portion 27, so that the optically reflective surface constituting portion 11 of the optically reflective member 10 is introduced. A hollow portion 14 was formed, and a hollow portion 15 extending from the hollow portion 14 formed in the optical reflection surface forming portion 11 was formed in a portion 13A of the protruding portion forming portion (see FIG. 4). The pressure of the pressurized fluid when introducing the pressurized fluid into the molten thermoplastic resin 30 in the cavity 24 is 3.7 × 10 ⁶ Pa (3.7 × 10 kgf / cm ² -G) in gauge pressure.
And

Thereafter, without performing the pressure-holding operation, until the thermoplastic resin in the cavity 24 is solidified and cooled (from the time when the injection of the molten thermoplastic resin into the cavity is completed, 4 hours).
During 0 seconds), the pressure in the hollow portions 14 and 15 is controlled by the volume of the pressurized fluid that pressurizes the hollow portions 14 and 15 via the pressurized fluid introduction portion 27, and is 2.0 × 10 ⁶ Pa (2.0
× 10 kgf / cm ² -G). After that, the pressurized fluid in the hollow portions 14 and 15 is released into the atmosphere through the pressurized fluid introduction portion 27, the mold is opened, and the optical reflection member 10 is opened.
Was taken out. In the optical reflection member 10 thus obtained, the volume of the hollow portion 14 is 20% of the volume of the optical reflection member 10, and the volume occupied by the projection component is 5% of the volume of the optical reflection member 10. there were. The length (length along the short side parallel to the direction of the rectangular planar optical reflecting surface 12) of the hollow portion 15 formed on a portion 13A of the projecting portion component W ₂ is a 0.2mm there were. That is, W ₁ =
Because of 2 mm, W ₂ / W ₁ = 0.1. Between the optical reflection surface 12 of the optical reflection member 10 molded in the cavity 24 and the mold surface of the nest 23 for forming the optical reflection surface 12, 1 μm per 10 mm ^{2 of the} optical reflection surface Only the following gaps existed.

The optical reflecting member 1 thus obtained
Table 1 below shows the plane accuracy of the optical reflecting surface 12 of 0.
Table 2 below shows the warpage ratio measured based on the line L ₀ connecting the “X ₁ ” point and the “X ₂ ” point in FIG. In the following Examples and Comparative Examples, the measurement of the warpage rate was the same.

On the optical reflecting surface 12 of the formed optical reflecting member 10, an aluminum vapor-deposited film is formed by a vacuum vapor deposition method.
A mirror was formed by depositing a film having a thickness of 20 nm. As a result, the optical reflection member 10 had excellent image clarity (specularity) equivalent to that of a normal glass mirror, and the subject was clearly displayed.

(Example 2) The hollow portion 1 is kept until the thermoplastic resin in the cavity 24 is solidified and cooled (for 40 seconds after the injection of the molten thermoplastic resin into the cavity is completed).
The pressure in each of the pressure chambers 4 and 15 is controlled by the volume of the pressurized fluid that pressurizes the hollow sections 14 and 15 through the pressurized fluid introduction unit 27, and is controlled to 4.8 × 10 ⁶ Pa (4.8 × 10 kgf / cm). ² −
An optical reflection member made of a thermoplastic resin was produced based on the same method as in Example 1 except that the optical member was held in G). The flatness of the optical reflecting surface of the optical reflecting member thus obtained is shown in Table 1 below, and the warpage ratio is shown in Table 2 below.

(Embodiment 3) The pressure in the hollow portions 14, 15 is maintained in a desired pressure range until the thermoplastic resin in the cavity 24 is solidified and cooled. Was controlled by the pressure of the pressurized fluid when the pressurized fluid was introduced into the molten thermoplastic resin in the cavity 24.

More specifically, in the third embodiment, the thermoplastic resin is supplied into the heating cylinder 26, kneaded and plasticized in the heating cylinder 26 and melted, and then injected into the cavity 24 of the mold 20. The molten thermoplastic resin 30 was injected through the part 25. The injection time is 1 second, and the volume of the injected molten thermoplastic resin is 80% of the volume of the cavity 24.
And Then, simultaneously with the completion of the injection of the molten thermoplastic resin into the cavity 24, a pressurized fluid is introduced into the molten thermoplastic resin 30 in the cavity 24 from the pressurized fluid introduction unit 27,
Thus, the optical reflection surface constituting portion 11 of the optical reflection member 10
A hollow portion 15 extending from the hollow portion 14 formed in the optical reflection surface constituting portion 11 was formed in a portion 13A of the projection component member. The pressure of the pressurized fluid when introducing the pressurized fluid into the molten thermoplastic resin 30 in the cavity 24 is 2.0 × 10 ⁶ Pa in gauge pressure.
(2.0 × 10 kgf / cm ² -G).

Thereafter, until the thermoplastic resin in the cavity 24 is solidified and cooled (for 40 seconds after the injection of the molten thermoplastic resin into the cavity is completed), the hollow portions 14 and 1 are formed.
The pressure in 5 was controlled by the pressure of the pressurized fluid introduced into the hollow portions 14 and 15. Hollow part 1 just before opening the mold
The pressure in 4, 15 is 2.0 × 10 ⁶ Pa in gauge pressure.
(2.0 × 10 kgf / cm ² -G). After that, the pressurized fluid in the hollow portions 14 and 15 was discharged into the atmosphere via the pressurized fluid introduction unit 27, the mold was opened, and the optical reflection member 10 was taken out. In the optical reflection member 10 thus obtained, the volume of the hollow portion 14 was 20% of the volume of the optical reflection member 10. The length (length along the short side parallel to the direction of the rectangular planar optical reflecting surface 12) of the hollow portion 15 formed on a portion 13A of the projecting portion component W ₂ is a 0.25mm there were. That is, W ₁ = 2 mm
Although it is therefore, it became a W ₂ / W ₁ = 0.125.

(Embodiment 4) The pressure in the hollow portions 14 and 15 is maintained within a desired pressure range until the thermoplastic resin in the cavity 24 is solidified and cooled. 20 has a movable core 29 instead of the nest 23.
The movable core 29 is further provided with a mold surface for forming an optical reflection surface, and the desired pressure range is controlled by controlling the position of the movable core 29.

More specifically, as shown in a schematic cross-sectional view of FIG. 5, a movable core 29 that can be moved by, for example, a hydraulic cylinder (not shown) may be provided in the fixed mold portion 21. . And in molding the optical reflection member,
At the time of mold clamping, the fixed mold part 21 and the movable mold part 22 are clamped so that the volume (V _C ) of the cavity 24 is smaller than the volume (V _M ) of the optical reflection member to be molded. In addition, the position of the movable core 29 in the cavity is controlled. Then, the molten thermoplastic resin is injected into the cavity (volume: V _C ) 24, and further, a pressurized fluid is introduced into the molten thermoplastic resin in the cavity 24, so that the optical reflecting surface of the optical reflecting member 10 is formed. A hollow portion 14 is formed in the component portion 11, and a hollow portion 15 extending from the hollow portion 14 formed in the optical reflection surface component portion 11 is formed in a portion 13A of the protrusion component portion. Thereafter, the movable core 29 is moved by the operation of a hydraulic cylinder (not shown), and the volume of the cavity 24 is increased stepwise, continuously, or all at once to the volume (V _M ) of the optical reflecting member to be molded. Let it. Thus, the pressure in the hollow portions 14 and 15 is maintained in a desired pressure range until the thermoplastic resin in the cavity 24 is solidified and cooled.

Comparative Example 1 In Comparative Example 1, an optical reflecting member having no hollow portion was formed without introducing a pressurized fluid. Specifically, the same injection molding machine, mold, and thermoplastic resin as those in Example 1 were used, and the thermoplastic resin was supplied into the heating cylinder 26, and kneaded and plasticized in the heating cylinder 26 to be melted. Thereafter, the molten thermoplastic resin was injected into the cavity 24 of the mold 20 via the resin injection section 25. The injection time was set to 1 second, and the volume of the injected molten thermoplastic resin was set to 100% of the volume of the cavity 24. After the injection of molten thermoplastic resin is completed, heating cylinder 2
From the 6 side, the holding pressure is 1 × 10 ⁸ Pa (1 × 10 ³ kgf /
cm ² -G) and a dwell operation for 40 seconds.
Next, the thermoplastic resin in the cavity 24 is applied for 20 seconds.
Cooled and solidified. Thereafter, the mold was opened, and the optical reflection member was taken out. The flatness of the optical reflecting surface of the optical reflecting member thus obtained is shown in Table 1 below, and the warpage ratio is shown in Table 2 below.

Comparative Example 2 Same as Comparative Example 1 except that after the injection of the molten thermoplastic resin was completed, the thermoplastic resin in the cavity 24 was cooled and solidified without performing the pressure-holding operation from the heating cylinder 26 side. The optical reflection member was produced by the method described in the above. The flatness of the optical reflecting surface of the optical reflecting member thus obtained is shown in Table 1 below, and the warpage ratio is shown in Table 2 below. Between the optical reflecting surface 12 of the optical reflecting member 10 molded in the cavity 24 and the mold surface of the nest 23 for forming the optical reflecting surface 12, a maximum of 10 mm ² per optical reflecting surface is provided. There was a 20 μm gap.

(Comparative Example 3) The volume of the molten thermoplastic resin injected into the cavity 24 was reduced to 9 times the volume of the cavity 24.
It was set to 0%, and a hollow portion was formed only in a part of the optical reflection surface constituting part and a part of the protruding part constituting part. That is, the hollow portion was formed up to the center of the optical reflection surface. Except for this point, an optical reflection member made of a thermoplastic resin was manufactured based on the same method as in Example 1. The flatness of the optical reflection surface of the optical reflection member obtained in this manner is shown in Table 1 below.
And the warpage ratio is shown in Table 2 below.

(Comparative Example 4) An optical reflecting member having no projection was formed. The external shape of the optical reflecting member is rectangular (length 2
90 mm, width 10 mm). The volume of the molten thermoplastic resin injected into the cavity 24 was set to 80% of the volume of the cavity 24, and a hollow portion was formed only in a part of the optical reflecting member. The size of the portion of the optical reflecting member constituting the optical reflecting surface is about 233 mm in length and about 10 mm in width.
Met. No hollow portion is formed in the outer peripheral portion of the optical reflecting member, and the outer peripheral portion of the optical reflecting member has a solid structure. An optical reflection member made of a thermoplastic resin was manufactured based on the same method as in Example 1 except for these points. The flatness of the optical reflecting surface of the optical reflecting member thus obtained is shown in Table 1 below, and the warpage ratio is shown in Table 2 below.

[Table 1] Pressurized fluid Gas holding pressure Molding machine holding pressure Planar accuracy Example 1 Yes 2.0MPa No ◎ Example 2 Yes 4.8MPa No ○ Comparative Example 1 No No 100MPa × Comparative Example 2 No No No △ Comparative Example 3 Yes 2.0MPa No × Comparative Example 4 Yes 2.0MPa No ×

[0049]

Although the present invention has been described based on the preferred embodiments, the present invention is not limited to these embodiments. The injection molding machine, the mold, and the used thermoplastic resin described in the embodiments are merely examples, and can be appropriately changed. The structure, shape, and dimensions of the optical reflecting member are also examples, and the design can be changed as appropriate.

[0051]

According to the present invention, a high-precision optical resin made of a thermoplastic resin having a rectangular optical reflecting surface (mirror surface) like a mirror or a reflector and having a projection formed thereon. The reflective member can be manufactured stably, with high quality, efficiently and economically, without requiring a separate process or a post-process.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an optical reflecting member formed in an example.

FIG. 2 is a schematic cross-sectional view of an injection molding machine and a mold used in Examples and Comparative Examples.

FIG. 3 is a schematic cross-sectional view of a mold and the like for explaining a method of manufacturing an optical reflection member of the present invention.

FIG. 4 is a schematic cross-sectional view of a mold and the like for explaining the method for manufacturing the optical reflection member of the present invention, following FIG. 3;

FIG. 5 is a schematic sectional view of a mold used in Example 4.

[Explanation of symbols]

10 optical reflection member, 11 optical reflection surface component, 12 optical reflection surface, 13 protrusion
13A: a part of the portion of the optical reflection member constituting the projection, 14, 15: a hollow part, 20: a mold for injection molding, 21 ... a fixed mold part, 22 ...・ Movable mold part, 23 ... nest, 24 ... cavity, 25 ・
..Resin injection section, 26... Heating cylinder, 27.
.Pressurized fluid introduction part, 28 ... Pressurized fluid source, 29 ...
Movable core, 30 ... molten thermoplastic resin

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshihiro Chino 5-6-2, Higashi-Yawata, Hiratsuka-shi, Kanagawa Prefecture Inside the Technology Center of Mitsubishi Engineering-Plastics Corporation (72) Inventor Kazuaki Ochiai 5 Higashi-Yawata, Hiratsuka-shi, Kanagawa Prefecture 6-2, Mitsubishi Engineering Plastics Co., Ltd. Technology Center (72) Inventor Yoichi Kotani 2-7-1, Yamazaki, Shimamoto-cho, Mishima-gun, Osaka Prefecture F-term in NARUX Co., Ltd. AG07 AG28 AH78 WA05 WA53 WA89 WB01 WC01 WK01

Claims (8)

[Claims] 1. An optical reflecting member having a rectangular planar optical reflecting surface, wherein said rectangular planar optical reflecting surface is a thermoplastic resin optical reflecting member surrounded by a projection. A hollow portion is formed by introducing a pressurized fluid in a portion of the optical reflecting member that forms the entire surface, and a part of the optical reflecting member that forms the projection portion includes:
An optical reflecting member, wherein a hollow portion extending from a hollow portion formed in a portion of the optical reflecting member constituting the entire area of the optical reflecting surface is formed. 2. An external shape of the optical reflecting member when the optical reflecting member is cut along a virtual plane including the optical reflecting surface is rectangular, and a direction parallel to a short side of the rectangular planar optical reflecting surface. The width of the portion of the optical reflection member that forms the protrusion along W ₁ is formed on a part of the portion of the optical reflection member that forms the protrusion along the direction parallel to the short side of the optical reflection surface. When the length of the hollow portion is W ₂ , 0.01 ≦ W ₂ / W ₁ ≦
2. The optical reflecting member according to claim 1, wherein 0.8 is satisfied. 3. When the width of the optical reflecting member along a direction parallel to the short side of the rectangular planar optical reflecting surface is W ₀ ,
3. The optical reflecting member according to claim 2, wherein 0.1 ≦ W ₁ / W ₀ ≦ 0.3 is satisfied. 4. When a length of a long side of a rectangular planar optical reflecting surface is L ₁ and a length of a short side is L ₂ , L ₁ / L ₂ ≧ 2 is satisfied. The optical reflection member according to claim 1. 5. The optical reflection member according to claim 1, wherein the volume occupied by the portion of the optical reflection member constituting the projection is 1 to 30% of the volume of the optical reflection member. 6. An optical reflection member of an optical reflection member molded in a cavity using an injection molding die provided with a cavity having a mold surface for forming an optical reflection surface. ^2. The optical reflecting member according to claim 1, wherein there is only a gap of 1 μm or less per 10 mm ^{2 of the} optical reflecting surface between the optical reflecting surface and a mold surface for forming the optical reflecting surface. 7. The optical reflecting member according to claim 1, wherein a warp rate of the optical reflecting surface is 1 × 10 ⁻³ or less. 8. The optical reflection member according to claim 1, wherein an optical reflection film is provided on a surface of the optical reflection surface.