JPS5845936B2 - Thermoplastic resin matte sheet manufacturing method and its manufacturing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a matte thermoplastic resin sheet and an apparatus for producing the same, and an object of the present invention is to provide a matte sheet that exhibits little matte matting.

There are various methods for producing a matte sheet of thermoplastic resin, but it is generally carried out by using a pressure roll that has been subjected to a matte finish on a sheet immediately after melt extrusion.

There are two methods of matting the pressure roll: (1) etching using chemicals (acid or alkali);
) A method of physically roughening the surface by sandblasting.

(3) Method of performing matte plating.

Alternatively, there was a method of using these methods in combination.

Matte processed sheets are generally used to give the sheet a soft feel by diffusely reflecting light rays.
In some cases, it is used after secondary processing such as compression molding,
In the latter case, especially during the heating step, the molten sheet extruded from the extrusion die loses its luster, which is a so-called deglossing problem.

In that case, it is sufficient as long as the melt-extruded sheet itself has lost its luster.From this point of view, thermoplastic resins filled with inorganic fillers have been used, but this is still insufficient, and in the past, fillers have been used. In the case of thermoplastic resins that are not coated, the matting effect is severe.

As mentioned above, the reason why it was not possible to obtain a sheet with the desired low matteness using conventional methods is that although it is possible to obtain a roughness within a certain range, it is impossible to obtain a larger roughness. This is because it is technically difficult to create roughness that is not only close to , but is also thought to be effective in adding even smaller irregularities to irregularities that have a certain level of roughness microscopically.

As a result of intensive studies, the present inventors found that adding smaller irregularities to the irregularities themselves of a certain roughness not only has a very great matting effect but also reduces matting.This is a novel method that is not available in the prior art. This discovery led to the present invention.

The present invention can be further extended by using a thermally sprayed matte roll.

Thermal spraying is a process in which materials such as metals and ceramics are melted and sprayed from a nozzle using an oxygen-acetylene (or hydrogen) flame or plasma flame to coat the material onto the target substrate.

By making a matte roll by thermal spraying, it is easy to obtain a very rough surface.It is a porous surface with a complex shape, which has microscopically smaller irregularities than the rough surface. can be made.

By using the matte roll produced by this thermal spraying method, it became possible to obtain a thermoplastic resin sheet with a very large matte effect.

The use of a matte roll, which has a complex porous surface through thermal spraying, produces a great matting effect because it not only faithfully forms rough irregularities on the melt-extruded sheet, but also allows microscopic irregularities to be formed as well. This is thought to be because it can be attached well.

That is, the sheet immediately after melt extrusion is introduced between a plurality of pressure rolls, where rough irregularities are formed by one matte roll that has been thermally sprayed.

When the sheet is cooled and contracts, and when it is separated from the matting roll, the surface of the semi-molten sheet is sheared and scratched by the microscopic irregularities of the roll, so it becomes matted. It is thought that the effect will be stronger.

Therefore, even if a roll with rough roughness is used, the matting effect is very small, and as with this thermal spray roll, the rough roughness itself has a porous monolithic surface with even smaller roughness. This is very important.

Table 1 shows experimental results of how rough the surface of the matting roll is required from the viewpoint of the matting effect.

A 40φ single-screw extruder was used as the experimental equipment, and polypropylene CMPR melt flow lay immediately after extrusion.
Geo: 1.0) Commercially available sandpaper (-#-) on the sheet
40 to +1500) laminated between three polishing rolls.

The sandpaper was later removed from the polypropylene sheet laminated with sandpaper, and the surface was visually evaluated.

Further, this 1.5 mm thick sheet was vacuum formed and the deglossing was observed.

From the results in Table 1, it was found that sandpaper equivalent to Φ600 was good in terms of basic roughness.

Anything rougher than +100 is not possible because it will be completely bonded due to the physical anchoring effect.

On the other hand, fine -1500 has a large degree of matting after vacuum forming, which is not desirable.

Therefore, from the above results, it can be inferred that a matte roll having a roughness equivalent to 4P600 is preferable.

Note that the matte state depends on the resin temperature immediately after extrusion, the roll temperature, and the degree of roll pressure bonding, but in particular, if the resin temperature or roll temperature is extremely high, the sandpaper will stick to the resin, which is unfavorable.

On the other hand, if the resin temperature is low, the rubber elasticity will work and the matte state will worsen, and if the roll temperature is low, not only will the warp in the extrusion direction of the sheet increase, but the matte state will also deteriorate.

In the present invention, a rough matte roll with a large matte effect is produced by thermal spraying, and the effect (d) is very large compared to the use of matte rolls made by other manufacturing methods. .

Examples will be given to further clarify the effects of the present invention.

Example 1 Polypropylene (
"MFR: 1.0)" sheet was melt-extruded at a die temperature of 230°C.

This sheet was sequentially introduced into three fixed rolls.

Among the three rolls, the middle roll is a matte roll that has been matted by thermal spraying, and the other two are normal gloss rolls.

The matte roll uses a molybdenum-nickel-aluminum mixed powder material (II-447 manufactured by Daiichi Metco Co., Ltd.) with oxygen.
It is obtained by melting it with acetylene gas and spraying it onto the roll surface from a nozzle, and the surface roughness is equivalent to +600 of commercially available sandpaper.

A matte sheet was produced using this matte roll at a roll temperature of 80°C.

The matte state of this sheet itself is as shown in Table 2.

Also shown is the state of deglossing when this 1.5 mm thick sheet was vacuum formed.

Reference Example 1 The same material as Example 1 except that the roll surface was sandblasted with 180 degrees of sandblasting, etched and then matt plated as a matte roll.*The results of a matte sheet produced under the same conditions are as follows. It is shown in Table 2.

The roughness of the matte roll after etching was equivalent to +600.

Example 2 A matte roll was produced by spraying an alumina titania powder material (manufactured by Daiichi Metco Co., Ltd. = H31) onto the roll surface.

It corresponds to sandpaper with surface roughness i, 1=100.

Using this matte roll, a matte sheet was produced using the same materials and under the same conditions as in Example 1.

The results are shown in Table 2. Example 2 Table 2 shows the results of a matte sheet produced using the same materials and under the same conditions as in Example 1, except that the roll surface was etched to #600 and sandblasted as a matte roll.

Example 3 Table 2 shows the results of a matte sheet produced under the same conditions as Example 1 except that human BS resin was used as the material.

Example 1 Table 2 shows the results of a matte sheet produced under the same conditions as Example 1 except that polyethylene was used as the material.

Matte sheets using matte rolls produced by thermal spraying have the following advantages over matte sheets using conventional matte rolls that have been etched, sandblasted, matte plated, etc.

(1) Great matte effect.

In particular, the roughness equivalent to +600 is good.

(2) The sheet loses its luster during heating during vacuum forming and the like.

(3) A matte roll can be produced extremely quickly in only one step.

The thermal spraying process can also be applied to matting of rolls with crests, and matting of molds for vacuum forming, compression molding, injection molding, blow molding, and the like.

Claims (1)

[Scope of Claims] 1. A method for producing a matte thermoplastic resin sheet, which comprises sequentially pressing a molten thermoplastic resin sheet onto a matte roll on which a finely uneven metal coating has been formed by thermal spraying. 2. The method for producing a thermoplastic resin matte sheet according to claim 1, wherein the matte roll has a surface roughness of +100-41000 and corresponds to sandpaper. 3 Production of a thermoplastic resin matte sheet by arranging three rolls in front of the T-die of an extruder to introduce the sheet immediately after extrusion, and forming a fine uneven metal coating on the middle roll of the three rolls by thermal spraying. Device.