JPS6118268B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a videotape reel that is easy to manufacture and reliable. A video tape reel, like a reel used in a conventional movie projector, is composed of an inner tube that serves as a winding core and is connected to a rotating shaft, a side plate for supporting the tape, and the like. Conventionally, tape reels were made of metal or some kind of synthetic resin, but in the case of video, the equipment itself is extremely sophisticated compared to conventional equipment such as tape recorders, and the tape reels used for this are also much more sophisticated than conventional equipment such as tape recorders. Remarkably high performance and high reliability are required. Moreover, since it is consumed in large quantities, it is also an essential condition that it can be easily mass-produced. A synthetic resin reel is most suitable for the latter requirement, but as described below, conventional synthetic resin reels do not have sufficient performance. In other words, tape reels require high dimensional accuracy, stability, durability, and friction characteristics.
Conventional synthetic resin reels cannot satisfy this requirement. As a synthetic resin reel, there is a polyacetal reel, which is most suitable as a tape reel among synthetic resin reels, but is still not sufficient in terms of dimensional accuracy and frictional characteristics. A reel made of polyacetal containing additives is considered as a reel with improved these properties. Regarding additives, it is effective to reduce the orientation and deformation during molding in order to improve the dimensional accuracy of tape reels, and therefore, for this purpose, highly effective additives such as metal soap are effective. Addition of lubricant is effective. Such a lubricant is also effective in reducing deformation during mold release. However, the addition of such a lubricant also increases the slippage within the molding machine, and has the disadvantage that even a small change in the amount of the lubricant results in a large change in effectiveness. As a result, dimensional variations increase, and as a result, dimensional accuracy does not improve. It is possible to improve fluidity by adding polyethylene glycol, etc., but the effect is small. Furthermore, various additives such as mineral oil are known to improve frictional properties, but these have the disadvantage of reducing dimensional accuracy, similar to the aforementioned lubricants. In this way, it is extremely difficult to improve a plurality of properties in a well-balanced manner using additives, and so far no satisfactory reel has been obtained by this method. As a result of various studies on improving the characteristics of reels, the present inventors discovered that the addition of a certain type of surfactant is extremely effective, leading to the present invention. The tape reel of the present invention contains 0.2 to 2% by weight of one or more surfactants selected from aliphatic amine surfactants and aliphatic amide surfactants.
This is a videotape reel having an inner cylinder and a side plate made of polyacetal resin. The tape reel of the present invention has the advantage that due to the appropriate lubricant properties of the additive, there is little deformation during molding and mold release, and there is also little variation in accuracy due to fluctuations in conditions. Additionally, the additives seeping out onto the surface have the advantage of significantly improving the frictional properties with the tape. More preferably, there is an advantage that there is little dirt on the surface of the mold, which occurs during normal long-term molding, and a good surface condition can be maintained stably for a long time. In particular, a tape reel to which an amine surfactant is added has excellent antistatic properties, and has the advantage of reducing problems caused by static electricity. As described above, according to the present invention, it is possible to provide a tape reel with excellent balance and performance that cannot be expected with conventional synthetic resin reels or additive-containing synthetic resin reels. The polyacetal resin referred to in the present invention means an acetal homopolymer, an acetal copolymer, or a modified product thereof, and a fluid grade (for example, "Dyuracon M270" manufactured by Polyplastics Co., Ltd.) is particularly preferable, and it is resistant to a decrease in thermal stability due to additives. Acetal copolymers and terminally etherified homopolymers are preferred in terms of the number of polymers. When using a stabilizer, a normal stabilizer for acetal is used, but in particular, as an antioxidant, molecular weight phenol having a t-butyl group at the ortho position (for example, "Irganox" manufactured by Ciba Geigy) is used.
1010” and “Irganox 259”) are preferred. Examples of amine surfactants used in the present invention include similar compounds derived from lauryl and stearyl grade aliphatic amines and ethylene oxide, similar compounds derived from olefins of grade aliphatic grade, and amide surfactants. Examples of the agent include those derived from aliphatic amides. Among these useful surfactants, preferred examples of aliphatic amine surfactants include lauryl diethanolamine, such as "Electrostripper EA" manufactured by Kao Soap Co., Ltd., and "TB-123" manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd. ” etc. Examples of aliphatic amide surfactants include lauryl diethanolamide and the like. The amount of these added is preferably 0.2 to 2% by weight, particularly 0.3 to 1.5% by weight. In the present invention, it is also possible to use a mixture of multiple types of activators. In particular, it is preferable to use a nonionic surfactant in combination with the aliphatic amine surfactant and aliphatic amide surfactant used in the present invention from the viewpoint of improving thermal stability during molding. Preferred nonionic surfactants include adducts of higher alcohols and ethylene oxide, esters of higher alcohols and fatty acids, esters of polyhydric alcohols and higher fatty acids, and polyethers mainly composed of polyethylene glycol and polypropylene glycol. Similarly, hydrophilic substances such as glycerin and diethylene glycol, and lipophilic substances such as paraffin can be used in combination with the surfactant of the present invention. As described above, the tape reel of the present invention is most suitable for video use, but in a type that has side plates on both the upper and lower sides, requirements for mechanical properties and precision are relatively low, and only the upper plate, which requires transparency, is used. It is also preferable to make it from a transparent resin such as styrene. Examples 1 to 3, Comparative Example 1 Acetal copolymer (polyplastic
A lauryl diethanolamine surfactant (Electro Stripper EA, manufactured by Kao Soap Co., Ltd.) was mixed with Diyuracon M270 (manufactured by Kao Soap Co., Ltd.) in the proportions shown in Table 1 below, and a 40 mm twin-screw extruder was used. The mixture was kneaded and extruded into pellets. Then, after pre-drying at 80℃,
Injection molded videotape reel (reel diameter
90 mm) was prepared, and a test piece cut from the side plate of the prepared reel was left to stand under predetermined conditions, and then the charging property was measured. To determine the charging property, the test piece was left at 20°C and 65RH% for 48 hours, and then the half-life of the charging voltage was measured using an Honest meter (manufactured by Shishido Shokai). The results are shown in Table-1.

[Table] *% by weight based on total composition
As can be seen from Table 1, by adding the above-mentioned aliphatic amine surfactant to insulating polyacetal, the half-life of the charging voltage is significantly reduced, and it becomes possible to have an antistatic effect. Example 4, Comparative Examples 2 and 3 A mixture of 0.8 parts by weight of lauryldiethanolamine and 0.2 parts by weight of glycerin was mixed with 99 parts by weight of polyacetal copolymer (Dyuracon M90 manufactured by Polyplastics Co., Ltd.) in the same manner as in Example 1, and pellets were prepared. After pre-drying at 80℃, test piece (inner diameter
A cylindrical sample (20.0 mm in diameter, 25.6 mm in outer diameter, and 5.0 mm in height) (Sample 1) was made by injection molding. This test piece was tested using a thrust type Suzuki abrasion tester under the conditions of a load of 10 kg/cm ² and a linear sliding velocity of 4.5 cm/sec.
The specific wear amount of this test piece with respect to stainless steel and steel (S55c) as counterpart materials was measured. As a comparative example, a similar test was conducted on a polyacetal resin and an ABS resin to which no surfactant was added, and the measurement results are shown in Table 2.

[Table] As can be seen from Table 2, the composition of the present invention has a smaller specific wear amount and superior wear resistance compared to polyacetal resins to which no surfactant is added and ABS resins, which are other resins. There is. Example 5, Comparative Example 4 A polyacetal copolymer containing 1% by weight of lauryl diethanolamine prepared in the same manner as in Example 2 (Dyuracon manufactured by Polyplastics Co., Ltd.)
M90) was used to mold a videotape reel (reel diameter 90 mm). The relationship between the surface runout of the side plate of the tape reel and the molding cycle was evaluated in comparison with a polyacetal copolymer that does not contain lauryl diethanolamine. The molding conditions are cylinder temperature 190℃ and holding pressure 1000℃.
Kg/cm ² , injection speed 0.8m/min, mold temperature on moving side
46-49℃, fixed side 50-52℃. The molding cycle (total of holding pressure and cooling time) was measured by changing the cooling time with a constant holding pressure time (10 seconds). The surface runout of the side plate was measured using a Mitoyo coordinate measuring machine A-11, and the deformation value indicates the difference between the highest and lowest portions of upward and downward deformation of the side plate. The results are shown in Table-3.

[Table] As shown in Table 3, the R values of the examples of the present invention are:
The R value is smaller than that of the comparative example, and the variation value is also smaller.
As can be seen, the tape reel of the present invention has excellent dimensional accuracy and is not easily affected by molding cycles.
Stable moldability. Examples 6-7 and Comparative Examples 5-6 Acetal copolymer (polyplastics)
After mixing lauryl diethanolamide with Diyuracon 270 (manufactured by Co., Ltd.) in the proportions shown in Table 4 below and pelletizing it in the same manner as in Example 1, a videotape reel made from this sample was prepared using the method described above. The half-life of the charging voltage, specific wear amount, and surface runout of the side plate were measured in the same manner as in the example. For comparison, similar tests were conducted on samples without additives and samples with zinc stearate added. The results are shown in Table 4.

[Table] Examples 8 and 9 Lauryl diethanolamine and polyethylene glycol or stearyl monoglyceride were mixed with polyacetal copolymer (Dyurancon M90 manufactured by Polyplastics Co., Ltd.) in the proportions shown in Table 5 below. After pelletizing in the same manner as above, the half-life of the charged voltage was measured for a videotape reel prepared from this sample by the method described in Example 1. The results are shown in Table-5.

[Table] As can be seen from Table 5, when a nonionic surfactant is used in combination with an amine surfactant, a remarkable antistatic effect can be achieved even if the amount of the amine surfactant added is small. Example 10 and Comparative Examples 7 to 8 In Examples 1 to 3 and Comparative Example 1, the half-life of charging voltage was measured when the amount of lauryl diethanolamine added was further changed, and the results are shown in Table 6 below. I got it.

[Table] Table 6 shows that if the amount of surfactant added is less than the lower limit specified in the present invention, the antistatic effect will be insufficient, and if it is more than the upper limit, the antistatic property will be improved, but polyacetal resin becomes easier to thermally decompose,
It can be seen that the moldability becomes poor.

Claims (1)

[Claims] 1. A videotape having an inner cylinder and side plate made of a polyacetal resin containing 0.2 to 2% by weight of one or more surfactants selected from aliphatic amine surfactants and aliphatic amide surfactants. reel.