JPH10305441A - Molding method of silicone resin material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mold a strain-free optical lens by a method wherein a thermosetting silicone resin material containing an organopolysiloxane having a specified cold viscosity and a specified composition is poured in a molding metal mold until the overflowing of the material occurs so as to harden a molded article part after the gate parts on a bung hole side and on an overflowing part side are sealed by hardening. SOLUTION: A thermosetting silicone resin material containing an organopolysiloxane, the viscosity at normal temperature of which is 20-300 poise and an average compositional formula of which is: Rn(C6 H5 )mSiO(4-n-m) /2, in which R is the same kind or different kinds, substituent or non-substituent, aliphatic or clicyclid monovalent hydrocarbon group and 0.1-50 mol.% of R is aliphatic unsaturated hydrocarbon group, and (n) and (m) are positive numbers, which satisfy inequalities: 1<=n+m<2 and 0.02<=m/(n+m)<=0.8, is used. The above-mentioned molding material 5 is poured in a molding metal mold, the temperature of which is controlled to be a predetermined one. The pouring is stopped at the instant that the overflowing of the material starts. A nozzle 11 is left as being connected and, after the gate parts 7 and 7' are hardened, is disconnected. Thus, a ultra low pressure molding becomes possible, resulting in allowing to produce a molded article highly efficiently without molding strain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a molded product using a silicone resin material without molding distortion, and particularly to a camera optical system, a finder system, a video camera, a video projector, binoculars, a loupe, and a copying machine optical system. For optical lenses used in various OA equipment such as optical systems of printers and optical related equipment, it is possible to perform ultra-low pressure molding, so molding distortion hardly occurs, thereby lowering optical characteristics due to molding distortion. The present invention relates to a method for molding a silicone resin material, which can suppress the occurrence of the resin as much as possible and can cope with high-cycle molding.

[0002]

2. Description of the Related Art As materials for molded articles such as optical lenses used in the above-mentioned various OA equipment and optical-related equipment, there are:
Clean, abrasion resistance, low absorption, focusing on basic optical properties such as excellent transparency, high refraction, low dispersion, low birefringence, etc.
General characteristics such as heat resistance, high strength, weather resistance, and high dimensional accuracy are required. Conventionally, as such a material, an optical lens made of an inorganic glass material has been used,
These almost satisfied the above-mentioned characteristics.

[0003] In recent years, the market for various OA equipment and optical-related equipment described above has been expanded for individual users, and the size, weight, cost, and fashion of various OA equipment and optical-related equipment are extremely high. It has become strongly desired. In order to respond to these demands, for example, in the case of an optical lens, in addition to the above-mentioned characteristics, furthermore, a workability for easily obtaining an optical lens having a complicated shape such as an aspherical lens, more impact resistance, etc. It has become necessary to satisfy the above characteristics. In contrast, conventional optical lenses made of an inorganic glass material have a disadvantage that they have a large specific gravity, are inferior in impact resistance, and have poor workability, so that it is difficult to cope with a complicated shape such as an aspherical lens. In many cases, it has not been possible to fully satisfy the requirements of the above.

Therefore, optical resin materials such as PMMA, PC, PS, diethylene glycol bisallyl carbonate (CR-39),
Optical lenses using materials such as polycyclohexyl methacrylate (PCHMA), poly-4-methylpentene, amorphous alicyclic polyolefin, and polycyclic norbornene-based polymers have been developed and used. Optical lenses using these resin materials also have a lower specific gravity than inorganic glass materials for optics, and can be used to mold lenses of complex shapes such as aspherical lenses. When forming the optical system, it is possible to make the configuration simpler than the optical lens made of an inorganic glass material, and thus it is possible to reduce the size of various OA devices and optical-related devices.

[0005]

When a molded article such as an optical lens is molded from an optical resin material, various optical characteristics such as a refractive index, a light transmittance and a birefringence, and the warpage of the molded article. Molding conditions must be set to maintain good dimensional accuracy including torsion. Molding of an optical lens using the above-mentioned optical resin material as a raw material is generally performed by a molding method such as injection molding, injection compression molding, or molding by casting. However, the optical lens having good optical characteristics and dimensional accuracy is used. In order to obtain a molded product, it is necessary to form a molded product with minimum molding distortion.

However, when a thermoplastic resin is used among the above-mentioned optical resin materials, the mold must be filled with the material at a high pressure in order to prevent sinking of a molded product. This is a factor that causes molding distortion, and causes a problem that optical characteristics are deteriorated. Also, in order to reduce molding distortion as much as possible, it is necessary to take sufficient molding time including pressurizing time and cooling time during molding,
For this reason, there also arises a problem that high cycle production cannot be performed. On the other hand, even when a thermosetting resin is used, if a molding method by casting is used, molding can be performed with a relatively small molding pressure, so that a molded product without molding distortion can be obtained. However, there is a problem that a high cycle production cannot be performed due to a long molding time.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and it is possible to easily obtain a molded article which can be formed by ultra-low pressure and has no molding distortion, can be produced by a simple apparatus, and has a high cycle cycle. An object of the present invention is to provide a method of molding a silicone resin material which can be produced and which can easily mold an optical lens used for OA equipment and optical-related equipment having particularly excellent optical basic performance.

[0008]

Means for Solving the Problems In order to solve the above problems, the present inventors have conducted intensive studies and as a result, a molding material injection port is provided at the lower part of the mold, and the injected molding material is provided at the upper part of the mold. A method of molding a silicone resin material using a molding die in which an overflow portion of a material is provided, and a gate portion on the molding material injection port side and a gate portion on the overflow portion side are formed by drawing to be thinner than the thickness of the molded product. Then, a thermosetting silicone resin material containing an organopolysiloxane represented by the following average composition formula (1) having a viscosity at room temperature of 20 to 300 poise is injected from a molding material injection port of the molding die. Injecting the molding material until the molding material comes out to the overflow portion of the molding die, and then curing the molding material injection port side and the gate portion on the overflow portion side,
By curing the molded part after sealing, molded parts such as optical lenses with free shapes and no molding distortion can be obtained, including aspherical surfaces, and molded using conventional optical resin materials. In comparison with the case, even if molding is performed at a high cycle, molding distortion can be suppressed as much as possible, and it has been found that molded products such as optical lenses having good optical characteristics can be obtained with high efficiency, and the present invention has been completed. Was. R _n (C ₆ H ₅ ) _m SiO _{(4-nm) / 2} (1) wherein R is the same or different, substituted or unsubstituted aliphatic or alicyclic monovalent hydrocarbon group, 0.1 to 50 mol% is an aliphatic unsaturated hydrocarbon group, and n and m are 1 ≦ n
It is a positive number satisfying + m <2 and 0.05 ≦ m / (n + m) ≦ 0.8. ]

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic explanatory view showing a method for molding a silicone resin material of the present invention. As shown in this figure, the molding apparatus used in the present invention mainly includes a molding die, a molding material supply unit, a molding temperature control device, a molding die opening / closing device, and the like.

As shown in FIG. 1, the molding die 1 is provided with a molding material injection port 3 in a lower mold portion 2 and an overflow portion 6 of the injected molding material 5 in an upper mold portion 4. On the molding material injection port 3 side and the overflow portion 6 side of the injection material 5, there are provided gate portions 7 and 7 'formed by drawing to be thinner than the thickness of the obtained molded product. The dimensions of the gate portions 7, 7 'have a trade-off with the thickness of the molded product to be obtained, but are within a range of 1/2 to 1/5 of the thickness of the molded product in contact with the gate portion. And the shape of the gate portion is preferably a pinpoint shape. However, even in the case of a film gate shape or a fan gate shape, the gate thickness is １ ／ to 1 times the thickness of the molded product.
/ 5. If the dimensional ratio of the gate portion is larger than 1/2, it takes time to cure and seal the gate portion, which is a feature of the present invention, and there is a disadvantage that the molding time is lengthened. If it is smaller than 5, the material injection resistance into the mold becomes large, so that the material injection pressure must be increased, which causes distortion during molding, which is not preferable. Although not shown in this figure, plugs are provided in the middle of the pipe between the material injection nozzle 11 and the molding material supply unit 8 and at the tip of the overflow unit 6 so that the material is injected into the mold. Before the gate is cured,
By closing both stoppers, pressure inside the mold may be applied.

The molding material supply section 8 is for supplying the molding material 5 to the molding material injection port 3 in the molding die 1, for example, a supply method using compressed air, a supply method using a tube pump or the like, or A general method for supplying a liquid material, such as a supply method using a servo screw feed mechanism using the servo motor 9 shown in FIG. 1, can be adopted. The molding material supply unit 8 may control the temperature as needed in order to keep the viscosity of the material constant.

Since the molding material used in the present invention is a thermosetting resin material containing organopolysiloxane, the molding die 1 is provided with a temperature controller. As this temperature control device, various temperature control mechanisms such as a rod-shaped or plate-shaped electric heater, or an oil circulation system can be used, but in molding that requires precise temperature control such as molding of an optical lens, In particular, it is desirable to use an oil temperature control mechanism 10 as shown in FIG.

The opening / closing device for the molding die is not particularly limited as long as it is a mold-clamping opening mechanism used in an ordinary injection molding machine. The mold clamping force is 10kg / c because there is no need to inject the material
m ² or more is sufficient. This mold clamping force is 10kg / cm ²
If it is smaller, before the molding material is injected and cured, a phenomenon occurs in which the material viscosity temporarily decreases in the mold, and resin leakage occurs from the parting line of the mold, so that a good product cannot be obtained. Absent. In view of the above, not only a hydraulic mechanism but also a drive mechanism using an air cylinder can sufficiently cope with the drive for opening the mold clamping mold.

The molding material used in the present invention has an average compositional formula (1) having a viscosity at room temperature of 20 to 300 poise.
A thermosetting silicone resin material containing an organopolysiloxane represented by the following formula is used. _{R n (C 6 H 5)} m SiO (4-nm) / 2 (1) wherein, R represents preferably 1 to 20 carbon atoms, particularly preferably unsubstituted or substituted the same or different 1 to 10 carbon atoms An aliphatic or alicyclic monovalent hydrocarbon group such as a methyl group, an ethyl group, an alkyl group such as a propyl group, a saturated hydrocarbon group such as a cycloalkyl group, a vinyl group, an allyl group. And unsaturated hydrocarbon groups such as propenyl group and butenyl group, halogen atom-substituted hydrocarbon groups such as 3,3,3-trifluoropropyl group, and cyano group-substituted hydrocarbon groups. And R of 0.1 to 5
It is necessary that 0 mol% is an unsaturated hydrocarbon group, preferably 1 to 20 mol% is an aliphatic unsaturated hydrocarbon group, more preferably an alkenyl group. If the content of the unsaturated hydrocarbon group is less than 0.1 mol%, the required hardness of the cured silicone resin cannot be obtained in this case. On the other hand, if the unsaturated hydrocarbon group content exceeds 50 mol%, the number of crosslinking points becomes too large, so that the cured silicone resin becomes brittle, and the strength required as an optical lens cannot be maintained. N and m are 1 ≦ n + m <2, and the content of the phenyl group is 5 to 80 mol% of all organic groups [0.05 ≦ m / (n + m)
m) ≦ 0.8], and particularly preferably 5 to 50%. When the phenyl group is within this range, the characteristics as an optical lens can be sufficiently satisfied.

If the viscosity of this organopolysiloxane at room temperature (20 to 25 ° C.) is less than 20 poise, resin leakage from the parting line is likely to occur, and the mold clamping force must be increased to prevent this. The disadvantage is that the characteristics of the present invention cannot be utilized. Conversely, if it is larger than 300 poise, the injection pressure must be increased because the pressure loss during injection becomes large. Since it has a disadvantage that it does not conform to the gist of the ultra-low pressure molding of the present invention, the viscosity is 20 to 30.
It is preferably within the range of 0 poise. Further, the silicone resin material used in the present invention may contain a catalyst such as organohydrogenpolysiloxane, chloroplatinic acid, or other additives in addition to the above-mentioned organopolysiloxane. Examples of such a silicone resin material include, for example, Japanese Patent Application No. 8-31588 previously proposed by the applicant.
No. 8, the silicone resin material described in the specification may be used.

Next, a method for molding a molded article using the molding apparatus and the molding material described above will be described. First 100
10kg / c of mold for temperature controlled within the range of ~ 180 ° C
Clamp with a clamping force of m ² or more. At this time, the mold temperature is 1
If the temperature is lower than 00 ° C., the time required for curing becomes extremely long, so that the productivity is poor. On the other hand, if the temperature is higher than 180 ° C., the components of the molding material volatilize and foaming occurs inside the molded product, which is not preferable. Next, the material injection nozzle 11 connected to the material supply unit 8 is connected to the molding material injection port 3 provided in the lower part 2 of the mold, and the molding material 5 is injected. Next, when the injected molding material 5 comes out into the overflow portion 6 provided in the mold upper part 4, the injection is stopped, and the nozzle 11 is left for a while while being connected to the molding material injection port 3. When the gates 7, 7 'on the upper mold side 2 and lower gate 4 side are hardened, the nozzle 11 is separated from the injection port 3 of the molding die 1. The molding part 12 in the molding die 1 is left for a predetermined time for hardening, and then the molding die 1 is opened by the die opening / closing device, and the molded product is taken out. For this removal, a removal device that matches the shape of the molded article may be used.

The material injection nozzle 11 used here is
The shape may be adapted to the material injection port 3 provided in the lower portion 2 of the molding die so as to prevent leakage of the molding material and air entrapment during the injection. In addition, it is necessary to connect to the molding material injection port of the molding die whose temperature is controlled to the temperature required for curing until the gate portion is cured after molding material injection. Cooling water 13
It is desirable to provide a cooling mechanism such as a structure capable of flowing air. Furthermore, a device such as a shut-off nozzle may be employed so that the supply of the molding material can be stopped immediately after the injection of the molding material is completed. In the present invention, an optical lens has been mainly described in particular. However, the present invention is not limited to this optical lens alone, and may be applied to a molded article molded of a silicone resin material.

[0018]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. (Example 1) 100 parts by weight of an organopolysiloxane represented by the following average composition formula (2), 10 parts by weight of an organohydrogenpolysiloxane represented by the following average composition formula (3), and a solution of chloroplatinic acid in isopropanol (containing platinum) (Amount: 0.20% by weight) and 1.2 parts by weight were mixed and degassed by vacuum stirring to prepare a silicone resin material. (CH ₃ ) _1.02 (C ₆ H ₅ ) _0.40 (CH ₂ = CH) _0.08 SiO _1.25 (2) (CH ₃ ) ₃ SiO-[(CH ₃ ) ₂ SiO] ₃ -[(CH ₃ ) HSiO] _3- [(C ₆ H ₅ ) ₂ SiO] ₄ —Si (CH ₃ ) ₃ (3) Molding of an optical lens with the silicone resin material clamped at a temperature of 150 ° C. and a pressure of 100 kg / cm ² through an injection nozzle. The injection was stopped when the molding material came out of an overflow section provided above the molding die. The injection nozzle was connected to a material injection port provided below the molding die until the gate was cured. Thereafter, the injection nozzle was released, and the mixture was cured by heating for 5 minutes, and then the mold was opened with a mold opening / closing device to obtain a lens molded product. Using this lens molded product, the characteristics of birefringence and light transmittance were measured by the following measurement methods. A resin pressure measurement sensor was embedded in the mold to measure the resin pressure. Table 1 shows the above results. [Birefringence] Measured using a digital refractometer. [Light transmittance] According to JIS K7105, SM-3
It was measured using a mold (manufactured by Suga Test Machine Co., Ltd.).

Example 2 A molded lens was obtained in the same manner as in Example 1, except that the clamping pressure of the molding die was changed to 10 kg / cm ² . Example 1 describes the measurement items and the measurement method for this lens molded product.
The measurement was performed in the same manner as described above, and the results are shown in Table 1.

Comparative Example 1 A lens molded product similar to that of Example 1 was molded by injection molding using PMMA resin for optics (Acrypet, manufactured by Mitsubishi Rayon Co., Ltd.). The clamping force of the molding die was about 590 kg / cm ² . The measurement items and the measurement method were the same as in Example 1, and the results are shown in Table 1.

(Comparative Example 2) A lens molded product similar to that of Example 1 was molded by an injection molding method using an optical PC resin (Iupilon, manufactured by Mitsubishi Gas Chemical Co., Ltd.). The clamping force of the molding die was about 590 kg / cm ² . The measurement items and the measurement method were the same as in Example 1, and the results are shown in Table 1.

Comparative Example 3 The same lens molded article as in Example 1 was molded by casting using diethylene glycol bisallyl carbonate (CR-39). The measurement items and the measurement method were the same as in Example 1, and the results are shown in Table 1.

[0023]

[Table 1]

[0024]

According to the method of the present invention, since ultra-low pressure molding is possible, there is no molding distortion, and molded products such as optical lenses having excellent optical basic characteristics can be produced with high efficiency by a simple manufacturing apparatus. Obtainable.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a method for molding a silicone resin material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Molding die 2 ... Mold lower part 3 ... Molding material inlet 4 ... Mold upper part 5 ... Molding material 6 ... Overflow part 7, 7 '... Gate part 8 ... Molding material supply part 9 ... Servo motor 10 ... Oil Temperature control mechanism 11 Material injection nozzle 12 Molded part 13 Cooling water

Continuation of front page (72) Inventor Tsutomu Nagasawa 1-406-1, Yoshino-cho, Omiya-shi, Saitama Shin-Etsu Polymer Co., Ltd. Tokyo factory

Claims (1)

[Claims] 1. A molding material injection port is provided at a lower part of a mold,
An overflow portion of the injected molding material is provided on the upper portion of the mold, and a molding die in which the gate portion on the molding material injection port side and the gate portion on the overflow portion side are formed by drawing to be thinner than the thickness of the molded product is used. A thermosetting silicone resin material containing an organopolysiloxane represented by the following average composition formula (1) having a viscosity at room temperature of 20 to 300 poise at room temperature. The molding material was injected from a molding material injection port, and the molding material was injected at least until the molding material appeared in the overflow portion of the molding die.Then, the molding material injection port side and the gate portion on the overflow portion side were cured and sealed. A method for molding a silicone resin material, wherein the molded article is cured later. R _n (C ₆ H ₅ ) _m SiO _{(4-nm) / 2} (1) wherein R is the same or different, substituted or unsubstituted aliphatic or alicyclic monovalent hydrocarbon group, 0.1 to 50 mol% is an aliphatic unsaturated hydrocarbon group, and n and m are 1 ≦ n
It is a positive number satisfying + m <2 and 0.05 ≦ m / (n + m) ≦ 0.8. ]