JP2012031889A - Linear motion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing device which improves lubricity, while preventing vacuum/clean environment deterioration due to a linear motion apparatus.SOLUTION: The linear motion apparatus includes a pair of relative movement members and the sealing device which seals a gap between itself and the other member in one member, wherein since the sealing member is composed of a polyolefin system synthetic resin containing an ionic liquid of 10 mass% or more and 80 mass% or less, it is possible to prevent the evaporation of a sealing composition under a low pressure environment, both vacuum/clean environment deterioration can be and dust scattering can be prevented. The ionic liquid contained in the polyolefin system synthetic resin permeates to the synthetic resin surface gradually and covers the surface, so that the lubricity can be improved.

Description

  The present invention relates to a linear motion device suitable for a transfer device used in a semiconductor manufacturing apparatus or the like.

  Conventionally, a linear guide device is known as a linear motion device as a typical device used in a transfer device used in a semiconductor manufacturing apparatus. For example, as shown in FIG. 2, the linear guide device includes a guide rail 1 having a rolling element rolling groove 3 on the outer surface and extending in the axial direction, and a slider 2 assembled across the guide rail 1. Are known. The slider 2 includes a slider body 2A and end caps 2B attached to both ends thereof. The slider body 2A is a rolling body (not shown) facing the rolling element rolling grooves 3 of the guide rail 1 on the inner side surfaces of both sleeve portions 4. It has a rolling groove and a rolling element return path (not shown) that penetrates the thick part of the sleeve portion in the axial direction. On the other hand, the end cap 2B has a curved path (not shown) that connects the rolling element rolling groove of the slider body 2A and the rolling element return path parallel to the rolling element rolling groove, and the rolling element rolling groove and the rolling element return. A circulation circuit of the rolling elements is formed by the road and the curved paths at both ends. A large number of rolling elements made of, for example, steel balls are loaded in the circulation circuit of the rolling elements.

  The slider 2 assembled to the guide rail 1 smoothly moves along the guide rail through the rolling of the rolling elements in the opposing rolling element rolling grooves. During the movement, the rolling elements circulate in the rolling elements in the slider. Circulate while rolling on the road. Lubrication of the rolling elements that roll is performed by grease preliminarily applied to the inner surface of the slider 2.

  As shown in FIG. 3, a side seal 5 is attached to the end face of each end cap 2B, and an under seal 6 is attached to the bottom face of the slider 2 as a sealing device that seals the opening between the guide rail 1 and the outside. Intrusion of foreign matter from the inside and diffusion of the internal lubricant to the outside is prevented. Generally, rubber seals such as NBR (acrylonitrile butadiene rubber) are used for these conventional seals.

  By the way, in the linear motion apparatus used for such a semiconductor manufacturing apparatus, in order to prevent the semiconductor from being contaminated by dust, the operation in a clean environment is required in a vacuum environment. When a linear motion device equipped with an NBR seal device used in a moving device is used in a vacuum environment, volatile components in NBR, such as DOP [di- (2-ethylhexyl) phthalate] used as a plasticizer, etc. Since the volatile components of the product evaporate and scatter and adhere to the semiconductor, there is a risk of contaminating the clean environment.

  Therefore, in order to prevent deterioration of the clean environment by evaporating and scattering the lubricating component even in such a vacuum environment, for example, in Patent Document 1, as in the linear motion device shown in FIG. By attaching a polyolefin synthetic resin containing vacuum pump oil or fluorine oil, which is difficult to evaporate, to the end of the slider 2 in the linear motion direction, that is, to the end cap 2B as a seal device 10, a vacuum / clean environment is maintained. Yes.

JP-A-9-208757

  However, in the device of Patent Document 1, the amount of evaporation of hydrocarbon oil such as vacuum pump oil contained in the seal device 10 increases due to the temperature rise due to heat generation accompanying the increase in the speed of the linear motion device, and adheres to semiconductors and the like. Because of contamination, there was room for improvement to prevent dust generation. Although fluorine oil can prevent vacuum and clean environment deterioration due to evaporation of the seal device components, the lubricity between the seal device 10 and the guide rail 1 may be deteriorated due to the fluorine oil components and the operability may be deteriorated. There was room for improvement to reduce the frictional resistance of the device.

  The present invention has been made to eliminate such inconveniences, and even in a vacuum environment, the lubricity of the linear motion device is improved while preventing deterioration of the clean environment due to evaporation of the seal device of the linear motion device. It aims at providing the sealing device which improves.

A first invention for solving the above problems is a linear motion device including a set of relative movement members and a sealing device that seals a gap between one member and the other member.
The sealing device is made of a polyolefin-based synthetic resin containing 10% by mass or more and 80% by mass or less of an ionic liquid.

  According to the present invention, since the seal device of the linear motion device is made of a polyolefin-based synthetic resin containing an ionic liquid, it becomes possible to prevent evaporation of the seal composition under a low pressure environment and prevent deterioration of the vacuum / clean environment. can do. In addition, the ionic liquid contained in the polyolefin-based synthetic resin gradually oozes out on the surface of the synthetic resin, and the lubricating performance can be improved by covering the surface.

It is a figure which shows the linear motion apparatus provided with the sealing apparatus which concerns on this invention and a prior art example. It is a figure which shows the linear motion apparatus provided with the sealing device which concerns on a prior art example. It is a figure which shows the linear motion apparatus lower surface of FIG. It is a figure which shows the linear motion apparatus provided with the sealing device which concerns on another prior art example.

Embodiments of the present invention will be described below.
A seal device 100 for a linear motion device according to the present invention shown in FIG. 1 contains a lubricant in advance and has a self-lubricating property that itself has a lubricant supply function. First, the component composition will be described.
(Ionic liquid)
In the present invention, the ionic liquid contained in the lubricating oil is a liquid salt composed of positive and negative ions, and since the positive and negative ions are strongly bound by ionic bonds, it is nonflammable, non-volatile, and has excellent thermal stability. ing. The ionic liquid is classified into the following aliphatic amines (Chemical Formula 1), alicyclic amines (Chemical Formula 2), imidazoliums (Chemical Formula 3), pyridines (Chemical Formula 4), and phosphoniums based on the type of cation. (Chemical formula 5).
Examples of the anion (X ⁻ ) include BF ⁴⁻ , PF ⁶⁻ , [(CF ₃ SO ₂ ) ₂ N] ⁻ , Cl ⁻ , Br ^{− and the} like.

In the formula, R ₁ , R ₂ , R ₃ and R ₄ represent an alkyl group or an alkoxy group. The greater the carbon number of the alkyl group and the greater the molecular weight, the greater the kinematic viscosity. A kinematic viscosity at 40 ° C. is known to be approximately 12 mm ² / s to 260 mm ² / s, and a base oil having an appropriate viscosity can be obtained by using ionic liquids alone or in combination. These ionic liquids can be used alone or in combination of two or more. The content of the ionic liquid is 1% by mass or more, preferably 10% by mass or more, and most preferably 100% by mass with respect to the total amount of the base oil. Here, the base oil is preferably a fluorine oil having a small amount of evaporation even in a vacuum or a high molecular weight hydrocarbon-based lubricating oil.

Polyethylene, polypropylene, polymethylpentene and the like are suitable as the polyolefin-based synthetic resin that can be used in the seal device of the linear motion device according to the present invention. As the polyethylene, those having a low to medium molecular weight having a number average molecular weight of 10,000 to less than 1,000,000 and those having an ultrahigh molecular weight having a number average molecular weight of 1,000 to 6,000,000 are used alone or mixed as necessary. Of these, ultra-high molecular weight polyethylene has poor fluidity when dissolved, and is premised on being molded by injection molding. In that case, 10 mass% or less is appropriate in the total composition, and if it is added 5 mass% or more, sufficient mechanical strength can be obtained if necessary.
Polypropylene having a number average molecular weight of 100,000 to 400,000 can be used. However, when the oil content is high as in the composition of the present invention, the mechanical strength becomes too low by itself, so that the purpose is to improve it. High molecular weight polyethylene may be added. Further, thermoplastic resins such as polyamide, polycarbonate, polybutylene terephthalate, polyphenylene sulfide, polyethersulfone, polyetheretherketone, polyamideimide, polystyrene, and ABS resin can be used. Alternatively, thermosetting resins such as unsaturated polyester resins, urea resins, melamine resins, phenol resins, polyimide resins, and epoxy resins can be used.

  The seal device of the linear motion device of the present invention having the above component composition is composed of an ionic liquid having a low vapor pressure even in vacuum and a polyolefin-based synthetic resin. However, the evaporation component is taken into the ionic liquid, and no volatilization of oil or the like occurs from the seal itself. Therefore, the function as a seal can be maintained for a long time without degrading the degree of vacuum of the use atmosphere. In addition, the ionic liquid held inside the seal gradually oozes out to form an oil film on the contact surface with the guide rail which is a lubricated member of the linear motion device, thereby expressing the self-lubricating property of the seal device itself. At the same time, it also functions as a lubricant supply device that supplies oil to the rolling elements via the guide rail. Therefore, stable lubrication is performed over a long period of time for a linear motion device used in a vacuum atmosphere.

Next, examples of the sealing device of the present invention and a friction durability test procedure regarding lubricity will be described.
Example 1
This embodiment is an example applied to a sealing device of a linear guide device as a linear motion device. The sealing device 10 of the linear guide device was injection molded using a paste-like mixture obtained by mixing the following components (A), (B), and (C) as an injection molding material.
(A) Low / medium molecular weight polyethylene: PZ50U [Mitsubishi Yuka Co., Ltd.] 15% by mass
(B) Ultra high molecular weight polyethylene: Mipperon (registered trademark) XM220 [manufactured by Mitsui Petrochemical Co., Ltd.] 10% by mass
(C) N, N-dimethyl-N-methyl-N- (2-methyloxyl) ammonium ion (cation) and BF ⁴⁻ (anion) [manufactured by Kanto Chemical Co., Ltd.] 75% by mass
(Example 2)
N in (C) of Example 1, N-dimethyl -N- methyl -N- and (2 Mechiruokishiru) ammonium ion _{(cation), (CF 3 SO 2)} 2 N - ( anion) Kanto Chemical ( Co., Ltd.] 75% by mass
(Comparative Example 1)
In Example 1 (C), octadecyl diphenyl ether: Neobak SY (manufactured by Muramatsu Oil Research Co., Ltd.), 75% by mass
A running test of the linear guide device in a vacuum was performed using the sealing device having the composition of Example 1, Example 2, and Comparative Example 1 as a sample.
When the sealing devices 10 and 100 are mounted, as shown in FIGS. 1 and 4, a protector 15 that is a reinforcing metal plate is disposed on the outside, and a metal sleeve is provided in a mounting hole for an end cap 2B (not shown). The spacer was mounted as a spacer and screwed to the end cap end face of the slider 2 while preventing the seal devices 10 and 100 from being crushed by screw tightening.
(Test condition specifications)
Linear guide device: Slider width 20mm, length 27mm, height 10mm
Travel stroke length: 20mm
Feeding speed: 100 mm / second lubrication: only by lubricating oil supplied from the side seal.
Degree of vacuum: 10 ^-3 Torr
(Test results)
The results of the friction durability test are shown in Table 1.
According to Table 1, in both Examples 1 and 2, no abnormality was observed even after running for 1000 hours, and no problem occurred in lubricity. On the other hand, in Comparative Example 1, seizure occurred due to poor lubrication after running for 100 hours. Thereby, it turned out that the friction durability performance of the synthetic resin containing an ionic liquid is superior to the synthetic resin containing hydrocarbon oil.

Needless to say, the present invention can be variously modified without departing from the gist of the present invention.
For example, the seal device of the linear motion device of the present invention is not limited to the linear guide device, but is also a linear motion guide device that performs linear motion using balls or rollers, such as a linear ball spline device and a linear ball bushing device. It can be suitably applied to.
Also, the linear guide device is not limited to the type of the embodiment, and for example, the load rolling element rolling groove may be other than one on one side, and the rolling element may be a roller instead of a ball.
Furthermore, the seal device for the linear motion device of the present invention is not limited to the linear guide device of the embodiment, and can be suitably applied to other various types of ball screw devices.
In addition, fillers, silica particles, solid lubricants, fullerenes, carbon nanotubes, and the like may be added to the polyolefin-based synthetic resin used in the present invention. Furthermore, a structure that makes it easier to hold the lubricant and reduces friction between the sealing device and the mating member by forming fine grooves, protrusions, holes, etc. on the sliding surface of the mating member that contacts the sealing device It may be.

DESCRIPTION OF SYMBOLS 1 ... Guide rail 2 ... Slider 2A ... Slider main body 2B ... End cap 3 ... Rolling body rolling groove 4 ... Both sleeve parts 5 ... Side seal 6 ... Under seal 10, 100 ... Sealing device 15 ... Protector

Claims (1)

In a linear motion device including a set of relative movement members and a sealing device that seals a gap between one member and the other member,
The linear motion device, wherein the sealing device is made of a polyolefin-based synthetic resin containing 10% by mass or more and 80% by mass or less of an ionic liquid.

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