JP3192793B2 - Method for producing thermoplastic resin embossed sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic resin embossed sheet having embosses having substantially the same surface roughness on both sides.

[0002]

2. Description of the Related Art A laminated glass in which an interlayer film composed of a thermoplastic resin such as a polyvinyl acetal resin and a plasticizer is bonded between transparent glass plates is widely used for window glasses of automobiles, aircrafts, buildings and the like. I have.

[0003] In this type of laminated glass, an interlayer is sandwiched between transparent glass plates, and this is passed through a pressing roll or placed in a rubber bag and suctioned under reduced pressure to deaerate air between the glass plate and the interlayer. It is manufactured by preliminarily bonding while heating and pressing in an autoclave to finally bond.

[0004] The intermediate film is required to have good degassing properties in the preliminary bonding step in order to eliminate entrapment of air bubbles. In addition, it is also required that the interlayer films do not block during storage. In order to satisfy such requirements, fine embosses (irregularities) are usually formed on both surfaces of the intermediate film.

The fine emboss formed on the intermediate film must have the same roughness on both surfaces. If the roughness of the emboss is uneven on both surfaces of the interlayer, the adhesive force between the glass plate and the interlayer becomes uneven, and the penetration resistance and the glass scattering prevention of the laminated glass deteriorate. In some cases, the thermoplastic resin sheet used for applications other than the intermediate film is required to have the same emboss roughness on both surfaces.

Conventionally, in order to form fine embossments on both surfaces of a thermoplastic resin sheet used for an intermediate film or other purposes, a plasticizer and other additives are mixed with the thermoplastic resin as necessary, A method in which the mixture is formed into a sheet by an extruder or a calender roll, the sheet is kept at a constant temperature, and is passed between a pair of upper and lower emboss rollers having the same roughness on both sides and adjusted to the same temperature. Widely adopted.

In this case, the sheet is maintained at a constant temperature, and the surface of the embossing roller has the same roughness on both sides and is adjusted to the same temperature. Emboss is formed.

The cause is that the embossed sheet passing between the pair of embossing rollers is heated and softened and becomes tacky, and when the embossing sheet is peeled off from the embossing roller at the exit immediately after passing through the embossing roller, it is inevitable that both of the embossing sheets are removed. This is because the film is not uniformly peeled off from the embossing roller but is peeled off while being partially adhered to one of the embossing rollers. As a result, the transfer rate of roughness from the embossing roller to the sheet changes.

[0009] Such a phenomenon is remarkable when the line speed is increased. In addition, although it is conspicuous in a sheet having a large adhesiveness such as an intermediate film, even a thermoplastic resin sheet other than the intermediate film is softened by heating during embossing, so that it is more or less generated.

[0010]

Therefore, the present inventor has proposed that the embossed sheet be peeled off from the other (upper) embossing roller at the exit of the embossing roller, and then from the other (lower) embossing roller. , A guide roller for an embossed sheet is disposed, and the temperature of one (lower) emboss roller is further reduced to the other (upper).
The embossing roller temperature was lowered or the temperature of one surface (lower side) of the sheet was similarly lowered to adjust the emboss transfer rate.

In this case, in order to form a good emboss having approximately the same roughness on both sides of the sheet, the temperature of one (lower) emboss roller is set to about 10 ° C. with respect to the temperature of the other (upper) emboss roller. It turns out that it is necessary to lower it. However, when the temperature is considerably reduced, the distortion of the sheet increases, and the thickness of the obtained embossed sheet varies greatly, and the heat shrinkage rate also increases.

The present invention solves the above-mentioned problem, and an object of the present invention is to provide a method of forming a sheet having substantially the same roughness on both surfaces without increasing the thickness variation and heat shrinkage due to sheet distortion. It is an object of the present invention to provide a method for producing a thermoplastic resin embossed sheet on which a special emboss is formed.

[0013]

According to the present invention, there is provided a method for producing an embossed sheet having embosses formed on both sides by passing a thermoplastic resin sheet between a pair of embossing rollers. The surface roughness of the other embossing roller is set to 1.2 Rz to 1.6 Rz with respect to the surface roughness Rz of one embossing roller, and the embossed sheet is peeled off from the other embossing roller at the exit of the embossing roller. By transferring the sheet so as to be peeled off from the one embossing roller, embosses having substantially the same surface roughness are formed on both sides.

Here, the surface roughness Rz is a commonly used surface roughness, and means a 10-point average roughness measured according to ISO / R468.

The thermoplastic resin sheet used in the present invention includes a thermoplastic resin used for an intermediate film, for example,
Polyvinyl acetal resin, vinyl chloride-glycidyl (meth) acrylate copolymer, vinyl chloride-ethylene-
Glycidyl (meth) acrylate copolymer, ethylene-vinyl acetate resin, linear polyurethane resin, or these resins, if necessary, including a plasticizer, an adhesion regulator,
A sheet made of a resin containing known additives such as a heat stabilizer, a lubricant, an ultraviolet absorber, an antioxidant, and a colorant is suitable, but not limited thereto.

The plasticizer used for the intermediate film includes triethylene glycol di-2-ethylhexoate, triethylene glycol dicaprylate, triethylene glycol di-n-heptate, and triethylene glycol di-2-ethyl. Butyrate, tetraethylene glycol di-n-heptoate and the like are preferably used. Such a plasticizer is generally used in an amount of 20 to 100 parts by weight of the resin.
60 parts by weight, preferably 30 to 55 parts by weight, are mixed.

Examples of the adhesion regulator for the intermediate film include metal salts of carboxylic acids, for example, potassium salts and sodium salts of octylic acid, hexyl acid, butyric acid, acetic acid, formic acid and the like. In general, 0.01 to 0.5 part by weight, preferably 0.02 to 0.2 part by weight, of such an adhesive force adjuster is mixed with 100 parts by weight of the resin.

Hereinafter, the production of a plasticized polyvinyl acetal resin embossed sheet used for an intermediate film will be described with reference to the drawings.

FIG. 1 is a side view showing an embodiment of the present invention. In FIG. 1, a mixture obtained by mixing a plasticizer and other additives with a polyvinyl acetal resin is melt-kneaded by an extruder and extruded into a sheet shape from an extrusion die 10. The sheet can be formed by a calender roll. The thickness of the sheet is generally 0.3 to 1.6 mm
It is said.

The extruded sheet 20 thus obtained is passed through the surfaces of temperature control rollers 30 and 31 to be adjusted to a constant temperature. Then, the sheet 2 adjusted to a certain temperature
0 is passed between the pair of emboss rollers 40 and 41. The embossing rollers 40 and 41 have the same configuration as the conventional embossing roller except for the surface roughness.

The sheet 20 has temperature control rollers 30, 3
1, generally 90-150 ° C. on both sides, preferably 11
It is adjusted to the same temperature on both sides from 0 to 130 ° C. If the heating temperature of the sheet is too low, the distortion in the embossing process increases, and the thickness balance and shrinkage of the sheet increase. On the contrary, if the heating temperature of the sheet is too high, it may cause poor biting into the embossing roller or winding. .

The surface roughness of the embossing rollers 40 and 41 is such that the surface roughness Rz of one (eg, lower) embossing roller 41 is 1.2 Rz or less. 1.6 Rz. Although the shape of the emboss is not particularly limited, it is usually formed in a satin-patterned unevenness.

For example, both surfaces have a surface roughness Rz of 30 to 40.
To produce a μm sheet (interlayer), one side (lower)
Surface roughness Rz of embossing roller 41 of 30-40 μm
On the other hand, the surface roughness of the other (upper) emboss roller 40 is set higher (rougher) by 6 to 18 μm.

Then, a pair of emboss rollers 40, 4
The embossed sheet 21 passing through the gap 1 is transferred while being guided in the direction of one (lower) embossed roller 41 by the guide rollers 50 and 51 also serving as cooling.
The guide rollers 50 and 51 are disposed at such positions that the embossed sheet 21 is peeled off from the other (upper) embossing roller at the exit of the embossing roller, and then is peeled off from one (lower) embossing roller. .

In order for the sheet 20 to be peeled off from the other (upper) embossing roller at the exit of the embossing roller and then from one (lower) embossing roller, the above-mentioned guide roller is used. In addition, an appropriate release means such as an air knife is employed.
Also, the temperature of one (lower) emboss roller 41 is
A method of slightly setting the temperature of the other (upper) emboss roller 40 to be higher is also adopted. In this case, the temperature of the one (lower) emboss roller 41 is suppressed to as high as about 5 ° C. so that the sheet is not distorted and the variation in the sheet thickness is not increased.

The embossed sheet 21 is used for the guide roller 5
It is cooled by passing through 0 and 51, is taken up by a pair of take-up rolls 60 and 61, and is taken up. The linear speed of the take-off roll is adjusted so that the embossed sheet 2 'does not slack. Thus, an embossed sheet (intermediate film) is manufactured.

[0027]

When the embossed sheet passing between a pair of embossing rollers is transported so as to be peeled off from the other (upper) embossing roller at the exit of the embossing roller and then from one (lower) embossing roller. Since the embossed sheet led out from the pair of embossing rollers is always transferred in a state of being peeled off from one (lower) embossing roller, the embossing formed by one (lower) embossing roller is the other. The transfer rate is higher than that of the emboss formed by the (upper) embossing roller, and the surface is always rough. However, since it is not necessary to lower the temperature of one side of the sheet, the sheet is less likely to be distorted in the embossing step.

Then, the emboss is formed in such a constant state, and one side (lower side) is formed.
The surface roughness of the other (upper) embossing roller is 1.2 Rz to 1.
Assuming 6Rz, the emboss roughness of both surfaces is adjusted to almost the same level.

[0029]

EXAMPLES Examples and comparative examples of the present invention will be described below. Example 1 To 100 parts by weight of a polyvinyl butyral resin having an average degree of polymerization of 1700 and a degree of butyralization of 65 mol%, triethylene glycol-di-2-ethyl butyrate 40 was used as a plasticizer.
Parts by weight, and magnesium acetate 0.2 as an adhesion regulator
Parts by weight, the mixture is melt-kneaded by an extruder, extruded into a sheet form from an extrusion die 10,
The temperature of the sheet 10 is set to 11 on both upper and lower sides through 0 and 31.
The temperature was maintained at 4 ° C. The thickness of the sheet at the entrance of the embossing roller was adjusted to an average thickness of 1.25 mm by adjusting the extrusion amount.

The sheet is passed between a pair of upper and lower embossing rollers 40 and 41 to form an emboss on both sides, and is peeled off from the upper embossing roller 40 at the exit of the embossing roller. Was transported so that it could be peeled off.

The linear speed of the pair of emboss rollers is 10 m
/ Min. The surface roughness Rz of the upper embossing roller 40 is 39 μm, and the lower embossing roller 41 has a roughness Rz of 39 μm.
The surface roughness Rz is 32 μm. The temperature of the upper emboss roller 40 was adjusted to 130 ° C., and the temperature of the lower emboss roller 41 was adjusted to 135 ° C. Subsequently, the embossed sheet 21 was cooled after passing through the guide rollers 50 and 51, and was taken out by a pair of take-up rolls 60 and 61.

The roughness Rz on the upper surface of the embossed sheet thus obtained was 31 μm, and the roughness Rz on the lower surface was 31 μm. The average thickness of the embossed sheet is 770 μm
, Thickness drop (difference between maximum and minimum values of thickness in the length direction)
Was 7 μm, and the heat shrinkage (shrinkage in the length direction at 50 ° C. for 10 minutes in warm water) was 2.5%. The results are summarized in Table 1.

Example 2 In Example 1, the linear velocity of the pair of embossing rollers was changed to 12 m / min, and the surface roughness Rz of the upper embossing roller was changed to 42 μm. Other than that, it carried out similarly to Example 1. The results are summarized in Table 1.

Example 3 In Example 1, the linear speed of the pair of embossing rollers was changed to 14 m / min, and the surface roughness Rz of the upper embossing roller was changed to 45 μm. Other than that, it carried out similarly to Example 1. The results are summarized in Table 1.

Comparative Example 1 In Example 1, the surface roughness Rz of each of the upper and lower embossing rollers was changed to 33 μm, and the temperature of both the upper and lower embossing rollers was adjusted to 130 ° C. Other than that, it carried out similarly to Example 1. The results are summarized in Table 1.

Comparative Example 2 In Comparative Example 1, the temperature of the upper emboss roller was set to 1
Adjust the temperature of the lower embossing roller to 11 ° C.
The temperature was adjusted to 0 ° C. Other than that, it carried out similarly to the comparative example 1.
The results are summarized in Table 1.

Comparative Example 3 In Comparative Example 1, the temperature on the upper side of the sheet extruded into a sheet from the mold was adjusted to 115 ° C., and the temperature on the lower side of the sheet was adjusted to 105 ° C. Other than that, it carried out similarly to the comparative example 1. The results are summarized in Table 1.

[0038]

[Table 1]

[0039]

As described above, according to the method for producing a thermoplastic resin embossed sheet of the present invention, the distortion of the sheet in the embossing step is reduced, and the variation in the thickness of the obtained embossed sheet and the heat shrinkage are suppressed to a small level. In addition, it is possible to form fine embossments having approximately the same roughness on both sides of the sheet.

Therefore, when the sheet obtained according to the present invention is used, for example, as an interlayer film of laminated glass, the deaeration in the pre-adhesion step with the glass plate is good, and the workability and quality are good. In addition, since the interlayer films do not block each other during storage, the storage properties are improved.

[Brief description of the drawings]

FIG. 1 is a side view illustrating an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Extrusion die 20 Extrusion sheet 21 Emboss sheet 30 Temperature control roller 31 Temperature control roller 40 The other (upper) emboss roller 41 One (lower) emboss roller 50 Cooling guide roller 51 Cooling guide roller 60 Take-off roller 61 Take-off roller

Claims (1)

(57) [Claims] 1. A method for manufacturing an embossed sheet having an embossed surface on both sides by passing a thermoplastic resin sheet between a pair of embossed rollers, wherein the surface roughness Rz of one embossed roller is reduced by the other embossed roller. By transferring the surface roughness of the roller to 1.2 Rz to 1.6 Rz, the embossed sheet is peeled off from the other embossed roller at the exit of the embossed roller, and then peeled off from the one embossed roller. A method for producing an embossed sheet, comprising forming embossments having substantially the same surface roughness on both sides.