JPH02225558A - Production of polycarbonate sheet - Google Patents

Abstract

PURPOSE:To obtain a sheet having a smooth surface, good appearance, and low distortion of transmitted light and suitable for a window panel of an automobiles, vehicle, a building or the like by mixing a polycarbonate with a specified polyalcohol partial ester and melt-extruding the mixture into a sheet. CONSTITUTION:100 pts.wt. polycarbonate (of a viscosity-average MW of usually 10000-100000, desirably 15000-45000) is mixed with 0.01-1.0, desirably 0.05-0.5 pt.wt. partial ester of a 2-10C polyalcohol with a 10-30C aliphatic monobasic carboxylic acid (e.g. glycerol monostearate), and the obtained composition is melt-extruded into a polycarbonate sheet of low distortion of transmitted light.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a polycarbonate sheet, and more particularly to a method for producing a polycarbonate sheet having an extremely good surface condition and low perspective distortion.

<Conventional technology> Polycarbonate sheets have traditionally had transparency, heat resistance,
Due to its excellent mechanical strength, it is used in window materials for buildings, automobiles, vehicles, etc.

Polycarbonate sheets are generally produced by extruding a polycarbonate melt through a die using an extruder, then sandwiching and pressing the melt between a plurality of mirror-finished cooling rolls, and then taking it off with a take-off row. For this reason, the resulting polycarbonate sheet may have die lines or
Gear marks, transfer marks, adhesive marks on cooling rolls,
Warping, etc. will occur. Such a sheet has a large perspective distortion, that is, a distortion of the image seen through the sheet, and cannot be used as a window material, especially an automobile window material, from the viewpoint of safety during driving.

Conventionally, as a method for improving the surface condition of polycarbonate sheets, there has been a method of adjusting the cooling conditions during sheet production, for example, a method of sandwiching and pressing with rolls with a surface temperature of 155 to 190°C and then cooling (Japanese Patent Publication No. 51-25450). (No. Publication), one side of the clamping roll was heated to 30 to 90°C, and the other was heated to 10°C.
Method of maintaining the temperature between 0 and 140°C (Japanese Patent Application Laid-Open No. 62-48523
Publication No.) etc. have been proposed. However, these methods cannot sufficiently reduce perspective distortion.

<Object of the Invention> An object of the present invention is to provide a polycarbonate sheet that has sufficiently small perspective distortion and is suitable for window materials, particularly automobile window materials.

The inventors of the present invention have made extensive studies to achieve the above object, and have found that in order to suppress perspective distortion to a sufficiently low level, it is necessary to make the surface of the polycarbonate sheet extremely smooth. The surface of the mirror roll used to manufacture the sheet must be uniformly coated with an oily substance of about a monomolecular film, and furthermore, a monomolecular film of an oily substance is formed on the surface of the mirror roll, so that the sheet can be removed from the roll. It has been found that it is preferable for the monomolecular film to adhere to the sheet and separate from the roll when it is separated.

Based on this knowledge, many mold release agents and lubricants used in polycarbonate were investigated. However, with wire-type mold release agents, paraffins have the disadvantage of making the roll sticky and cloudy, and higher fatty acids have the disadvantage of making the roll sticky and cloudy.
High temperatures above 00°C have the disadvantage of decomposing polycarbonate, higher alcohols have insufficient mold release effects, and esters of higher fatty acids and higher alcohols have insufficient polycarbonate decomposition suppressing effects and mold release effects. , higher fatty acid amides caused decomposition of polycarbonate, and both were unsatisfactory. However, the inventors have found that only partial esters of specific polyhydric alcohols can sufficiently smooth the sheet surface and make it possible to manufacture polycarbonate sheets with low perspective distortion, and have thus arrived at the present invention.

<Structure of the Invention> The present invention provides 100 parts by weight of polycarbonate with 0.01 to 1.0 parts of a partial ester of a polyhydric alcohol having 2 to 10 carbon atoms and an aliphatic monocarboxylic acid having 10 to 30 carbon atoms.
This is a method for producing a polycarbonate sheet, which is characterized by melt-extruding a composition containing ai into a sheet shape.

The polycarbonate used in the present invention is produced by reacting dihydric phenol and a carbonate precursor by a solution method or a melt method.

A typical example of 21phenol is 2,2-bis(
4-Hydroxyphenyl)propane [bisphenol A
I, 1,1-bis(4-hydroxyphenyl)ethane,
1.1-bis(4-hydroxyphenyl cyclohexane, 2.2-bis<4-hydroxyl 35-dimethylphenyl)propane, 2.2-bis(4-hydroxy-
3,5-dibromophenyl)propane, 2,2-bis(
4-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)sulfide, bis(4-
Hydroxyphenyl) sulfonate, etc. Preferred dihydric phenol is bis(4-hydroxyphenyl)
The main raw material is alkanes, especially bisphenol A. Examples of carbonate precursors include carbonyl halides, carbonyl esters, heroformates, and specific examples include phosgene, diphenyl carbonate, dihaloformates of dihydric phenols, and mixtures thereof.

In producing polycarbonate, the above dihydric phenols can be used alone or in combination of two or more.

Polycarbonate viscosity average molecule f11 usually 10,00
0~100,000. Good mashikuha 15,000~45
,000. When producing such a polycarbonate, a molecular field regulator, a branching agent, a catalyst, etc. can be used as necessary.

The partial ester of polyhydric alcohol used in the present invention is a partial ester of a polyhydric alcohol having 2 to 10 carbon atoms and an aliphatic monocarboxylic acid having 10 to 30 carbon atoms, such as ethylene glycol monopalmitate, glycerin monopalmitate, etc. Examples include stearate, pentaerythritol monopalmitate, turgortan monostearate, propylene glycol monooleate, glycerin distearate, etc., and these may be used alone or in a mixture of two or more. In particular, glycerin monostearate and mixtures mainly containing this are preferred because they have an excellent sheet surface improvement effect.

The content m of the partial ester of the polyhydric alcohol is 0.01 to 1.0 parts by weight, preferably 0.5 parts by weight of O,OS, per 100 parts by weight of the polycarbonate resin. 0.
If the amount is less than 0.01 part by weight, no effect of improving the surface of the sheet can be obtained, and if it exceeds 1.0 parts by weight, the surface of the mirror roll will become sticky and the surface of the sheet will deteriorate.

In addition, the composition containing the partial ester of the polyhydric alcohol may contain other components as necessary, such as heat stabilizers such as phosphorous esters, phosphoric esters, and phosphonic esters (
UV absorbers (0.1 to 0.7 parts by weight) such as benztriazole type, acetophenone type, salicylic acid ester type, tetrabrome bisphenol A, tetrabrome bisphenol A, etc. Flame retardants such as low molecular weight polycarbonate and decabromodiphenyl ether (3 to 15 auxiliary components such as antistatic agents, colorants, and brighteners may be added between the suspended parts).

The polycarbonate sheet of the present invention is prepared by mixing polycarbonate powder or pellets with a predetermined amount of the partial ester of the polyhydric alcohol, and further adding other additives as necessary, using an arbitrary method such as a tumbler-1V blender, a super mixer, etc. It is produced by uniformly mixing the composition using a mixing means, and then melt-extruding the resulting composition as it is or after pelletizing it. Further, the above composition may be prepared by adding and mixing the partial ester of the polyhydric alcohol, etc. to a polycarbonate solution, and then removing the solvent.

Furthermore, polycarbonate powder or pellets and a predetermined amount of the partial ester of the polyhydric alcohol may be continuously fed to the extruder. During melt extrusion, there is no need to adopt special conditions, and the usual conditions for producing polycarbonate sheets can be arbitrarily adopted.

<Effects of the Invention> The polycarbonate sheet obtained by the method of the present invention has a highly smooth surface, an extremely good appearance, and has low perspective distortion, making it suitable for applications such as window glasses and nameplates for automobiles, vehicles, buildings, etc. suitable for

<Example> Examples will be given below for further explanation. Note that parts in the examples mean parts by weight. In addition, the surface temperature of the sheet and mirror roll was measured using a non-contact infrared tllrJ4Q6 meter [r-T
600 (*-Enssha'lJ) NiJ:')a
The method for evaluating the properties of the sheet is as follows.

(1) Surface roughness Ra (μ) stylus type surface roughness meter ((
It is shown as a measured value by Tokyo Johimisaku Co., Ltd.). Cutoff 0.
h+m, measurement length 4. ram(1) value.

(n) Perspective distortion Automotive safety glass test method JIS-R-3212. Specifically, an apparatus shown in FIG. 1 is used. In the figure, 1 is a projector, 2 is a screen, 3 is a sheet, the distance between points A and B is 4±0.2 m, and the distance between points 3 and C is 4 m. The circular shape of the bright part projected onto the screen by the projector was adjusted in advance to 8 Φ, and the sheet was placed in the direction of the projector.
It was installed at an angle of 5°, and the amount of deformation in test area 1 and the angle at which the amount of deformation was 2° to 3 am were determined.

The smaller the amount of deformation at the 35° angle and the angle at which the amount of deformation is 2° to 3 mm above, the smaller the perspective distortion.

(b) Appearance The surface was evaluated by visually observing the hue, burning, and presence or absence of warping.

Examples 1 to 3 and Comparative Examples 1 to 6 Sheets were manufactured using an extruder equipped with the apparatus shown in FIG. In the figure, 4 is a T-die with a width of 1200111, 5 is a sheet,
6, 7 and 8 are mirror rolls with a diameter of 300fffffi,
9 is a take-up roll.

100 parts of polycarbonate powder with a viscosity average molecular m of 27.700 manufactured from bisphenol △ and phosgene was mixed with the compound listed in Table 1 by adding the ω listed in the table, and then discharged from a T-die (t) into a sheet at 250 ka/hr. It was extruded, held between mirror rolls, and taken off to obtain a sheet with a thickness of 5 cm.The mirror rolls were 6.7° and 120.1 cm thick each time.
30. 115℃, surface speed of mirror roll is 0.5/m
, the take-up speed was set to 0.55/school. The measurement results of the characteristic values of the obtained sheet are shown in Table 1.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an apparatus used for measuring perspective distortion, and FIG. 2 is a model diagram showing an example of a sheet manufacturing apparatus suitable for carrying out the present invention. In FIG. 1, 1 is a projector, 2 is a screen, 3 is a sheet, and in FIG. 2, 4 is a T-die, 5 is a sheet, 6, 7 . and 8
9 is a mirror roll, and 9 is a take-off roll.

Claims (1)

[Claims] A composition in which 100 parts by weight of polycarbonate is blended with 0.01 to 1.0 parts by weight of a polyhydric alcohol having 2 to 10 carbon atoms and a partial ester of an aliphatic monocarboxylic acid having 10 to 30 carbon atoms is melted into a sheet. A method for producing a polycarbonate sheet, characterized by extrusion.