TWI523139B - Protective sheet and method for conveying substrate - Google Patents

Description

Protective sheet and substrate conveying method

The present invention relates to a protective sheet used for a substrate used for a laminated color filter or the like and a method of transporting the substrate.

In recent years, as the size of the liquid crystal display device has increased, the glass substrate for manufacturing the color filter has also been used in a large size (for example, 1 m or more on one side). The glass substrate as described above has a property of being thin (for example, 1 mm or less) and being easily bendable. Therefore, most of the glass substrates are housed in a dedicated tray one by one.

Fig. 2 is a perspective view showing a conventional glass substrate transport carriage, and Fig. 3 is a perspective view showing a state in which a glass substrate transport carriage shown in Fig. 2 is laminated.

The glass substrate transport tray 101 is used for accommodating the glass substrate 102 during transportation, such as a bracket-shaped metal frame 103, a buffer member 104 for mounting the glass substrate 102, and a horizontal plug 105 for supporting the cushion member. Composition.

One glass substrate 102 is accommodated in the glass substrate transfer tray 101. At this time, in order to completely absorb the glass substrate 102 in the glass substrate transport tray 101, the depth of the glass substrate transport tray 101 is designed to be sufficiently larger than the thickness of the glass substrate 102.

As shown in FIG. 3, the plurality of glass substrate transport trays 101 in which the glass substrate 102 is housed are transported in a state of being superposed on each other. At this time, since the glass substrate 102 is accommodated inside the glass substrate conveyance bracket 101, the glass substrate 102 is prevented from coming into contact with the conveyance bracket 101 superposed on the upper stage.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-59116

However, when one glass substrate transport tray 101 is used for each glass substrate 102, the height of the loading space is limited in the truck or the container system, so the number of glass substrates 102 that can be transported at one time is limited, which may result in The problem of increased transportation costs.

Accordingly, an object of the present invention is to provide a protective sheet and a method for transporting a substrate which can efficiently transport substrates while preventing scratches and breakage due to contact between substrates.

The present invention relates to a protective sheet sandwiched between respective substrates when a plurality of substrates are laminated. The protective sheet is characterized by being composed of a non-woven fabric.

Further, the present invention relates to a method of transporting a substrate represented by a color filter. In the transport method, a laminate in which a protective sheet and a substrate composed of a non-woven fabric are alternately stacked is formed inside a pallet.

If the protective sheet of the present invention is used, the substrates can be laminated without being in contact with each other. Thereby, it is possible to prevent scratches and breakage of the substrate. Further, since the height of the substrate laminate can be reduced, efficient transportation can be performed.

Fig. 1 is a cross-sectional view showing a method of transporting a substrate using a protective sheet according to an embodiment of the present invention. More specifically, (a) shows a substrate stacking process diagram, (b) shows a state diagram after the substrate is laminated, and (c) shows a state diagram of the stacked substrate.

The protective sheet 1 according to the embodiment of the present invention is used as a protective material when the substrate 2 is laminated. Specifically, as shown in FIG. 1( a ), the protective sheet 1 is sandwiched between the laminated substrates 2 . This protective sheet 1 is composed of a non-woven fabric. The nonwoven fabric is preferably made of, for example, a vinyl polymer, but is not particularly limited thereto. Here, the ethylene-based polymer means a polymer composed of a small amount of an olefin having 3 to 20 carbon atoms as a comonomer with respect to ethylene. Polyethylene (PE) is mentioned as a vinyl type polymer. The PE system has the best processability and is easily formed into a non-woven fabric. Further, the PE-based general-purpose resin is the softest, and it is not necessary to add an additive for softening. From these, the manufacturing cost of the nonwoven fabric can be suppressed as compared with the case of using other materials. In the present specification, the substrate 2 includes a glass substrate which is a material for manufacturing a color filter, a color filter substrate of a finished product, and a substrate of an intermediate product (a substrate having at least one layer formed on the glass substrate) The general term.

Here, when the nonwoven fabric constituting the protective sheet 1 is composed of a vinyl polymer, the number average molecular weight (Mw) of the vinyl polymer is 17,000 or more, and the weight average molecular weight is divided by the number average molecular weight (Mw/Mn). The value obtained is preferably 5 or less. If Mw is less than 17,000 or Mw/Mn exceeds 5, the low molecular weight component will be eluted from the nonwoven fabric, causing contamination of the substrate 2.

The component having a molecular weight of 1,000 or less in the ethylene-based polymer constituting the nonwoven fabric preferably has a weight fraction of 1.0% by weight or less. If the weight fraction exceeds 1.0% by weight, the low molecular weight component is eluted from the nonwoven fabric to cause contamination of the substrate 2.

The weight fraction of chlorine atoms contained in the ethylene-based polymer constituting the nonwoven fabric is preferably 5 ppm by weight or less. When the weight fraction containing chlorine atoms exceeds 5 ppm by weight, the chlorine atoms themselves are eluted from the nonwoven fabric to cause contamination of the substrate 2. Alternatively, in the presence of a chlorine atom, the thermal stability of the ethylene polymer is lowered, whereby the low molecular weight component is eluted from the nonwoven fabric, and the substrate 2 is contaminated. Among them, Mw and Mw/Mn, a weight fraction of a component having a molecular weight of 1,000 or less, and a weight fraction containing a chlorine atom are more preferably at the same time satisfying the above range.

In order to convey the substrate 2, first, a robot or the like (not shown) for transporting the substrate 2 is used, and as shown in (a), the protective sheet 1 and the substrate 2 are sequentially housed in the pallet 3. Next, as shown in (b), the laminated body 10 is formed inside the pallet 3 by alternately stacking a predetermined number of the protective sheets 1 and the substrate 2.

Next, as shown in (c), the pallet 3 in which the laminated body 10 is accommodated is conveyed to a truck or a container by, for example, a fork lift.

As shown above, the protective sheets 1 are provided in such a manner as to be sandwiched between the substrates 2, thereby preventing the substrates 2 from coming into contact with each other. Further, since the protective sheet 1 is formed by a non-woven fabric, there is no possibility that the substrate 2 is scratched by the protective sheet 1 itself. By these, it is possible to prevent the occurrence of scratches and breakage of the laminated substrate 2.

Further, when the same number of substrates 2 are laminated, as shown in the prior art, the height of the laminated body 10 becomes lower than in the case of using one bracket for accommodating a glass substrate (Fig. 3). . Thereby, the number of pieces that can be transported in a certain transport space is increased, and the substrate 2 can be efficiently accommodated and transported, so that the transport cost of one average substrate is reduced.

Among them, in the above embodiment, a protective sheet larger than the substrate is used. However, if it is possible to prevent the substrates from coming into contact with each other, the size thereof is not particularly limited. It is also possible to use, for example, the same size as the substrate.

Further, in the above embodiment, the substrate is laminated on the pallet, but the type of the pallet is not particularly limited thereto. For example, a person who can accommodate a larger number of substrates can also be used.

[Examples]

The embodiments of the present invention will be described below.

[Example 1]

In the protective sheet of Example 1, a non-woven fabric (weight per unit area = 30 g/m ² ) composed of polyethylene (PE) was used. The PE has a weight average molecular weight (Mw) of 37,000, a weight average molecular weight divided by a number average molecular weight (Mw/Mn) of 3.0, a molecular weight of 1000 or less, a polymer content of 1% or less, and chlorine contained therein. The atom is 5 ppm or less.

[Embodiment 2]

The protective sheet of the second embodiment differs from the protective sheet of the first embodiment in the type of PE. Specifically, a polyethylene having a Mw of 18,000, a Mw/Mn of 3.2, a molecular weight of 1,000 or less, a polymer content of 1% or less, and a chlorine atom of 5 ppm or less is used.

[Example 3]

The protective sheet of Example 3 differs from the protective sheet of Example 1 in the type of PE. Specifically, a polymer having a Mw of 47,000, a Mw/Mn of 4.0, a molecular weight of 1,000 or less, a polymer content of 1% or less, and a chlorine atom of 5% or less is used.

[Comparative Example 1]

In the protective sheet of Comparative Example 1, a PE film (manufactured by Asahi Kasei Chemicals Co., Ltd., thickness: 35 μm, weight per unit area: 30 g/m ² ) was used. In the PE system, the Mw is 45,000, the Mw/Mn is 2.5, the polymer content of the molecular weight of 1,000 or less is 1% or less, and the chlorine atom contained is 5% or less.

[Comparative Example 2]

The protective sheet of Comparative Example 2 differed from the protective sheet of Example 1 in the type of PE. Specifically, a polymer having a Mw of 50,000, a Mw/Mn of 6.0, a molecular weight of 1,000 or less, a polymer content of more than 1%, and a chlorine atom of more than 5% is used. Among them, the PE of Comparative Example 2 was synthesized using a Ziegler-Natta catalyst.

[Comparative Example 3]

The protective sheet of Comparative Example 3 differed from the protective sheet of Example 1 in the type of PE. Specifically, a polymer having a Mw of 10,000, a Mw/Mn of 3.5, a molecular weight of 1,000 or less, a polymer content of 1% or less, and a chlorine atom of 5% or less is used.

Using the protective sheets (750 mm × 940 mm) of Examples 1 to 3 and Comparative Examples 1 to 3, the glass substrates (730 mm × 920 mm × thickness 0.7 mm) used for the color filters were alternately stacked, and the inside of the dedicated pallet was overlapped. There is a laminated body of 300 glass substrates. Next, the dedicated pallet is loaded on the truck for transportation. Next, the evaluation test shown in the following items was performed about the glass substrate after conveyance. Table 1 is the result of the evaluation of the test results.

[Scars on the surface of the glass substrate]

The surface of the glass substrate after the conveyance was visually observed under a projector light source. Further, the surface of the substrate is inspected in an automatic inspection of the color filter manufacturing line. These results were evaluated by "○: no scars occurred, ×: scars occurred".

[Contamination of the surface of the glass substrate]

The surface of the glass substrate after the conveyance was visually observed under a projector light source. Further, the surface of the glass substrate before and after the deposition was extracted by ethanol, and the ion detection amount was measured by ion chromatography, and the values of the two were compared. The results were evaluated by "○: no visually-obtained contamination, and there was no difference in the amount of ion detection before and after the transport, x: there was visual contamination, or the ion-detection amount before and after the transport was poor".

Even when any of the protective sheets of Examples 1 to 3 was used, no scratches and contamination were observed in the glass substrate after the conveyance. Therefore, by using the laminated body which comprises a glass substrate and the protective sheet which consists of a nonwoven fabric, even if it is using any protective sheet, the glass substrate can be conveyed efficiently.

On the other hand, no scar was observed in the glass substrate conveyed by using the protective sheet of Comparative Example 1. This is because the protective sheet of Comparative Example 1 is composed of a film. That is, although the contact of the glass substrates with each other is prevented, the film itself causes scratches on the glass substrate. This confirmed the effectiveness of using a non-woven fabric on the protective sheet.

Further, no contamination was observed in the glass substrate conveyed by using the protective sheet of Comparative Example 2. This is because the ratio of the Mw/Mn of the protective sheet of Comparative Example 2 is large, and the ratio of the polymer having a molecular weight of 1,000 or less is high, and the ratio of chlorine atoms contained therein is large. That is, for the first reason, the low molecular weight PE content ratio is high. Since the low molecular weight component of PE is weakly related to other PE components, if the protective sheet contacts the surface of the glass substrate, the low molecular weight PE easily moves to the surface of the glass substrate. Further, for the second reason, a large amount of chlorine atoms are listed.

Due to the presence of chlorine atoms, the thermal stability of the polymer is lowered, and low molecular weight PE occurs due to molecular chain decomposition, and the low molecular weight PE easily migrates to the surface of the glass substrate.

Further, no contamination was observed in the glass substrate conveyed by the protective sheet of Comparative Example 3. In this case, the Mw of the PE constituting the protective sheet of Comparative Example 3 was relatively small. Regarding these, it is also cited that the low molecular weight PE content ratio is high.

From the results of Comparative Examples 2 and 3, it was found that adjusting the Mw, Mw/Mn of the PE constituting the nonwoven fabric, the PE content ratio of the molecular weight of 1,000 or less, and the chlorine atom content ratio were extremely effective in preventing contamination of the glass substrate.

[Industry use possibility]

In the present invention, a protective sheet for transferring a substrate used for a color filter or the like and a method of transporting the substrate can be used.

1. . . Protective sheet

2. . . Substrate

3. . . Pallet

10. . . Laminated body

101. . . Glass substrate transport bracket

102. . . glass substrate

103. . . Metal frame

104. . . Cushion member

105. . . Cross bolt

Fig. 1 (a) to (c) are cross-sectional views showing a method of transporting a substrate using a protective sheet according to an embodiment of the present invention.

Fig. 2 is a perspective view of a conventional glass substrate storage tray.

Fig. 3 is a perspective view showing a state in which the storage tray shown in Fig. 2 is laminated.

1. . . Protective sheet

2. . . Substrate

3. . . Pallet

10. . . Laminated body

Claims (8)

A protective sheet which is a protective sheet sandwiched between the respective substrates when a plurality of substrates are laminated, and is characterized in that it is composed of a nonwoven fabric having a basis weight of 0.003 g/cm ² . The protective sheet of claim 1, wherein the nonwoven fabric is composed of a vinyl polymer. The protective sheet according to claim 1, wherein the nonwoven fabric is composed of a vinyl polymer, the weight average molecular weight of the vinyl polymer is 17,000 or more, and the weight average molecular weight is divided by the number average molecular weight. the following. The protective sheet according to claim 1, wherein the nonwoven fabric is composed of a vinyl polymer, and the component having a molecular weight of 1000 or less in the ethylene polymer has a weight fraction of 1.0% by weight or less. The protective sheet according to claim 1, wherein the nonwoven fabric is composed of a vinyl polymer, and the ethylene polymer has a chlorine atom content of 5 ppm by weight or less. The protective sheet of claim 1, wherein the substrate is a color filter substrate. A substrate laminate which is formed by alternately stacking a protective sheet and a substrate according to any one of claims 1 to 6. A substrate transporting method is characterized in that a substrate laminate in which a protective sheet and a substrate are alternately stacked as in any one of claims 1 to 6 is formed inside the pallet to transport the substrate.