KR100264540B1 - The method of producing polyester sheet which is not expanded - Google Patents

Abstract

The present invention relates to a method for producing an unstretched polyester sheet, not only does not cause sheet physical property degradation caused by various additives, but also has excellent transparency, antistatic properties, and activity, and improves blocking resistance and formability, thereby greatly improving productivity. It is an object of the present invention to provide a method for producing an unstretched polyester sheet which can be improved, and the present invention for achieving the above object consists of ethylene terephthalate of at least 60% by weight of the main repeating unit and an intrinsic viscosity of 0.6 to 1.0 A single or a mixture of a polyester resin having a dl / g and a glass transition temperature of 70 to 85 ° C. and a sulfonic acid metal salt derivative compound of Formula 1 or Formula 2 having an acid value of 1.0 mgKOH / g or less and an average grain of 0.01 to 0.1 μm After melting and extruding in the state where phosphorus fine particles were added and forming into a sheet, the sheet surface having an average particle diameter of 10 to 50 µm Lead of the method for applying the powder provides a process for the preparation of the new esters replicon sheets.

[Formula 1]

[Formula 2]

In Formula 1 or Formula 2, R ₁ is an alkyl group having 1 to 10 carbon atoms, R ₂ is an alkyl group having 8 to 25 carbon atoms, and M is an alkaline earth metal element or an alkali metal element including Li, Na, or Mg.

Description

Manufacturing method of unstretched polyester sheet

The present invention relates to a method for producing an unstretched polyester sheet. More specifically, an unstretched polyester having improved transparency and activity by surface treatment after molding by mixing an oil and an inorganic compound having an appropriate particle diameter with a polyester resin. It relates to a method for producing a sheet.

In recent years, as the society becomes more modern, the market demand for general-purpose plastic sheets that can be applied to various items such as convenience containers and long-term contents storage, stationery, office supplies, electrical appliances, tools, toys, etc. is increasing. In particular, according to the market demand for luxury, the demand for plastic products with excellent transparency, which can be seen at any time by differentiating from existing products, is increasing rapidly.

Examples of the plastics that can be used for this purpose include polystyrene, polyvinyl chloride, polypropylene, polyethylene terephthalate, and the like. Among them, polyvinyl chloride has the advantage of being easy to process and does not require special technology or equipment. However, due to the generation of chlorine gas, which pollutes the environment during combustion, legal regulations have recently been intensified. In the case of polystyrene, transparency and Its mechanical properties are good, but it may cause environmental problems such as odor and black smoke, ash, and dust generated during incineration. Especially, it is brittle when it is moved or used during winter season. The resin has the advantage of being harmless and inexpensive, but it is not easy to increase the transparency than the existing product with the current technology level, and in spite of many advantages due to the problem derived from post-processing such as printability and bendability. It is not widely used yet.

In this respect, there is an increasing demand for polyesters having better processability and transparency than the above-mentioned plastics. In particular, polyethylene terephthalate of such polyester resins has a wide temperature from low temperature to high temperature. Excellent stability of physical properties, excellent chemical resistance, good mechanical strength, surface characteristics and uniformity of thickness, and excellent adaptability to various applications and process conditions. Industrial, medical, magnetic tape, condenser, packaging, In addition to being widely used for photographic films and labels, the recycling rate is also high in the field of environmental pollution.

However, in spite of the advantages mentioned above, polyester has a problem to be solved, such as turbidity or deformation in the process of manufacturing a non-stretched sheet requiring high temperature and pressure during molding. There are disadvantages that exist, and due to the insulation characteristics, there is a problem of generating static electricity due to running friction between the rotating body and the sheet, and as a result of coating defects caused by dust attached to the sheet surface due to such static electricity, It is caused by impact and blocking of sheets.

In particular, all high-transparent plastic sheets, including polyester, have a low surface crystallinity or a small crystal size to improve transparency, so that blocking phenomenon occurs more severely and poorly active when stacked or stacked for a long time. Is the biggest obstacle to demand.

In order to solve the defects caused by the electrostatic phenomenon of the polyester sheet, a lot of research has been conducted, and typically, a method of improving the charging characteristics by applying an antistatic agent to the surface of the sheet or incorporating it into the sheet has been mainly used.

When the antistatic agent is applied to the sheet surface among the above methods, the antistatic agent is free to be selected, the thermal stability and compatibility of the polymer are not considered, and the amount of the antistatic agent is required so that the properties of the moldings are not affected. Although there is an advantage that a relatively high level of antistatic property can be obtained, the antistatic agent layer formed by the above method exists thinly on the surface layer of the sheet, so that the precautions of workability for the presence of uncoated parts during application and the multi-step post-processing When used under repeated use or harsh conditions of the consumer, the surface may be damaged and the chargeability may be lost, so care must be taken in terms of durability, and the manufacturing cost is high economically. There is a possibility of severe occurrence, and the surface friction of the sheet, washing, the passage of time There are drawbacks, such as lack of permanence that the effect of preventing degradation.

Therefore, as a method for improving the antistatic property of a polyester sheet, a research into a technique for incorporating an antistatic agent into the interior is being actively conducted, unlike the method by the above application. In 12910, polyethylene glycol and sulfonic acid metal salt derivatives were added to impart antistatic properties. In US Pat. No. 59-15148, a polyester composition in which styrene oligomers and alkali sulfonates were blended was disclosed.

However, the styrene oligomer among the additives greatly lowers the heat resistance, degrades the film transparency, and may result in poor printability when the polyethylene glycol is excessively used.

In addition, since the transfer rate of the antistatic agent transferred to the surface is also limited by other additives, there is a fear that the effect of the antistatic agent is reduced. In addition, when the antistatic agent having an aromatic derivative is applied to the polyester, the surface transfer speed is remarkably decreased, which increases the amount of addition or requires a high temperature treatment, thereby deteriorating the sheet properties.

The present invention is to solve the problems of the prior art described above, molded into a sheet by mixing a sulfonic acid metal salt derivative having a suitable acid value and inorganic fine particles of an appropriate size to a polyester resin having a range of extreme viscosity and glass transition temperature. After the surface treatment with the coating liquid containing starch as a main component, the sheet properties are not degraded by the additives, and the transparency, the antistatic property and the releasing activity are very excellent, the blocking resistance and the moldability are improved, and the productivity is greatly increased. It is an object of the present invention to provide a method for producing an unstretched polyester sheet which can be improved.

The present invention for achieving the above object is a polyester resin having at least 60% by weight of the main repeating unit is made of ethylene terephthalate and has an ultimate viscosity of 0.6 to 1.Odl / g and a glass transition temperature of 70 to 85 ℃ After forming a sheet by melting and extruding in the state of adding a single or a mixture of the sulfonic acid metal salt derivative compounds of Formula 1 or Formula 2 having an acid value of less than .OmgKOH / g and fine particles having an average particle diameter of 0.01 to 0.1 µm, Provided is a method for producing an unstretched polyester sheet characterized by coating starch powder having an average particle diameter of 10 to 50 µm on the surface of the sheet.

In Formula 1 or Formula 2, R ₁ is an alkyl group having 1 to 10 carbon atoms, R ₂ is an alkyl group having 8 to 25 carbon atoms, and M is an alkaline earth metal element or an alkali metal element including Li, Na, or Mg.

The polyester of the present invention has an intrinsic viscosity of 0.6 to 1.Odl / g, measured at a concentration of 0.3 grams per 25 milliliters of orthochlorophenol at 35 ° C, but more preferably in the range of 0.7 to 0.9 da / g.

If the intrinsic viscosity is less than 0.6d1 / g, the polyester sheet of the present invention is not preferable due to the severe degradation of the productivity due to severe white turbidity during molding, as well as mechanical properties such as mechanical strength in the final product.

In addition, when the intrinsic viscosity exceeds 1.Odl / g, the melt viscosity is very high, so productivity in the post process is greatly reduced due to difficulties in the manufacturing process, such as extrusion instability.

In this invention, polyester polycondenses the acid component which has aromatic dicarboxylic acid as a main component, and the glycol component which has alkylene glycol as a main component.

Specific examples of such aromatic dicarboxylic acid include dimethyl terephthalate, terephthalate acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, anstagencarboxylic α, β-bis (2-chlorofe). Oxy-4,4'- dicarboxylic acid, etc. are mentioned, Among these, dimethyl terephthalate and terephthalic acid are especially preferable.

Specific examples of the alkylene glycol include ethylene glycol, trimethylene glycol tetramethylene glycol, pentamethylene glycol hexamethylene glycol, hexylene glycol, and the like, and among these, ethylene glycol is particularly preferable.

The polyester of the present invention is a homopolyester of 60% by weight or more of polyethylene terephthalate and may be copolymerized within 40% by weight. Specific examples of the copolymerization components include diol compounds such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylene glycol, 1,4-cyclohexanedimethol, 5-sodium sulforezocin, adipic acid, Dicarboxylic acid components, such as 5-sodium sulfoisophthalic acid, Polyfunctional dicarboxylic acid components, such as trimeryl acid and a pyromellitic acid, etc. are mentioned.

Unlike film, polyester resins used in the manufacture of sheets need to improve the glass transition temperature in the range of 70 to 85 ° C in order to prevent whitening during post-processing such as cases and tray containers, and the crystallization temperature of the resin is simply Although it is possible to increase the molecular weight, it is preferable to copolymerize with low molecular weight substances such as isophthalic acid, dimethylisophthalic acid and cyclohexanedimethanol.

The amount of the compound of Formula 1 or Formula 2 is 0.01 to 1.0% by weight, but preferably 0.05 to 0.8% by weight. When it exceeds 1.0% by weight, fine fish-eye is formed on the surface of the sheet, so that the physical properties of the sheet are not greatly reduced, and it does not help the antistatic properties. Can't be reached.

Specific examples of the compound of Formula 1 include sodium 3,5-dicarbo-methoxybenzenesulfonate, sodium 3,5-dicarbo-ethoxybenzenesulfonate, sodium 3,5-dicarbo-pentoxybenzenesulfonate , Lithium 3,5-dicarbo-methoxybenzenesulfonate, potassium 3,5-dicarbo-pentoxybenzenesulfonate, and the like, but are not necessarily limited thereto, and the compound of formula 2 is potassium octylbenzenesulfonate Sulfonic acid metal salt derivatives such as potassium nonylbenzenesulfonate and potassium undecylbenzenesulfonate, but are not necessarily limited thereto.

The sulfonic acid metal salt derivative is excellent in heat resistance and the applied sheet has excellent antistatic properties, and improves printability by increasing surface tension and having excellent adhesion to ink and coating solution.

In the present invention, the antistatic agent is preferably used at the same time as the formula (1) and formula (2), at least one may be selected according to the processing conditions and the use conditions of the sheet.

The fine particles used together with the sulfonic acid metal salt derivatives to improve the formability of the sheet and to improve the activity thereof preferably have a particle diameter of 0.01 to 0.1 μm. When the particle size is less than 0.1 μm, the effect of the present invention can be obtained. If the thickness is more than 0.1㎛, the sheet transparency is difficult to use.

The amount of the fine particles added is 0.1 to 1% by weight is suitable, if less than 0.1% by weight can not achieve the desired effect, if more than 1% by weight also falls in transparency. Representative examples that can be used as the inorganic fine particles include silica and alumina. Any particles may be used as long as the particles are spherical and do not impair transparency.

As the input method of the additive used in the present invention, both of the following methods are possible.

Firstly, each additive is slurried with ethylene glycol to the required concentration of the final sheet and directly added during esterification, transesterification, or polycondensation reaction. The second method is advantageous for mass production. After the polyester polycondensate is added into the process, the additive is added in the extrusion molding process or a part of the additive is mixed with the polyester polycondensate in high concentration. In this way, the contamination of the polymerization reactor can be reduced, and the concentration of additives can be easily controlled according to the degree of dilution of the master batch chip, which is suitable for the small variety of sheets.

As mentioned above, the transparency of polyester sheet, and this activity, which is also described as slip resistance or blocking resistance, are in opposite relationship, so simple molding conditions alone cannot satisfy both requirements.

Therefore, the sheet having improved transparency by the process conditions mentioned in the present invention is used in the present invention to reduce the contact surface or lower the surface energy in order to improve the slip resistance and blocking resistance and improve the activity between sheets. It is applied to the surface.

The coating method of the starch used in the present invention can be any method as long as it can be evenly sprayed on the surface of the sheet.

The starch to be applied can be used raw starch or soluble starch and the particle size of the starch is about 10 to 50㎛, especially 20 to 50㎛ even better. If the particle size of the starch is larger than 50 mu m, the white powder remains on the surface and the appearance is not good. If the particle size is smaller than 10 mu m, the effect of the present invention cannot be obtained.

The concentration of starch powder sprayed on the sheet surface is most appropriate in the range of 0.01 to 0.1 g / m², and when it is 0.1 g / m 2 or more, the remaining amount in the sheet is not good appearance and the powder is scattered during post-processing. If it is g / m <2> or less, the effect of this invention cannot be expected.

In order for the starch powder to be uniformly applied to the sheet surface, the static electricity adhering to the sheet surface moving at high speed must be removed. For this purpose, the static electricity can be removed using a thin wire. It is better to choose according to the method used.

After coating the surface using starch powder, a dust collector may be used to remove the remaining amount on the surface of the sheet. If you can get a better effect.

Starch powder to be used may be used as it is, but in order to prevent coagulation and to be uniformly distributed, the surface treatment is preferably 0.001 to 0.01 mg / g based on the weight of the starch powder. If the surface treatment is less than 0.001mg / g, the surface color of the starch is changed, the appearance is not good. Rapid treatment of starch is generally available in both known dry and wet methods, but the present invention uses starch treated by the dry method.

In order to manufacture a sheet that satisfies the properties of the present invention, all existing molding machines can be used. In particular, the use of a “△” name belt type sheet molding machine can further improve transparency, and in order to improve transparency, high gloss on the surface of the sheet can be obtained. Since paint is one of the most important factors, it is necessary to make the surface of the roll or belt contacting the sheet, as well as close enough, so that sufficient transfer and crystallization to the sheet surface can be suppressed. It is necessary to set the process conditions for forming the sheet while inducing the phenomenon.

The polyester is discharged at 250 to 300 kg per hour under an extrusion temperature of 250 to 300 ° C. and 100 to 150 screw rpm, cooled by a cooling roll at 15 to 40 ° C., and rotated at a speed of 10 to 30 m / min. Attached and molded into sheets of constant thickness.

Process temperature and residence time are the major factors that determine the transparency of the sheet, so must be produced in the temperature range of the present invention. If the extrusion temperature is too high, the cooling time is delayed and the transparency is lowered. This defect results in poor surface gloss and transparency.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

Example 1

Dimethyl terephthalate is mixed with ethylene glycol and cyclohexanedimethanol in an equivalent ratio of 1: 1.1, and a transesterification catalyst is added to produce a polyethylene terephthalate monomer (bis-2-hydroxyethylterephthalate). After preparing a polyester resin having an ultimate viscosity of 0.780 dl / g and a glass transition temperature of 79 ° C., some potassium chips were added with octylbenzenesulfonate and silica by compounding method. Manufactured.

After mixing the two chips in the master chip and the general chip in an appropriate ratio, the octylbenzene sulfonate is adjusted to 0.05% of silica and 0.3% by weight of the final sheet, and is discharged at a screw rpm of 120 and 270kg per hour under the cylinder extrusion temperature of 270 ° C. The sheet was molded into a belt rotating at a speed of 15 m / min by pressure-cooling between a 30 degreeC cooling roll and a 120 degreeC belt.

The sheet mirror surface was treated with a nozzle spray method to apply starch powder having a particle diameter of 35 μm with a copper metal surface treatment of 0.006 mg / g to a concentration of 0.05 g / m ₂ , and the light transmittance, The haze, coefficient of friction, surface resistance, moldability and blocking resistance were tested and the results are shown in Table 1 below.

Experimental Example

Haze, light transmittance

The haze meter (model name: SEP-P) of Nippon Semichu Kogaku Co., Ltd., Japan, was used to measure transmitted light and scattered light using a C-light source, and the haze was calculated by substituting the following equation (1).

[Equation 1]

Friction coefficient

Using a surface tester (model name: 2227001) manufactured by Seisaku-Sho, Japan, the measurement was carried out under a condition of 1.Okg load and a speed of 150 mm / min.

Antistatic characteristics (antistatic, surface resistance measurement)

Surface resistance was measured using an insulation resistance measuring instrument of the US Hewlett. (23 ℃, RH: 60%, applied voltage: 500V, unit)

Formability

Moldability was evaluated to the extent that turbidity occurred in the process of manufacturing a container under the pressure of 70 degreeC and 5 kg using a sheet | seat.

○: does not occur at all

×: turbidity occurs

Blocking resistance evaluation

Blocking phenomenon occurs when 100 sheets (10cmx10cm) are stacked and adhered to a certain temperature and a certain pressure. This is called blocking, and the phenomenon is observed after leaving it for 24 hours under a temperature of 25 ° C, a humidity of 50RH% and a pressure of 1kgf / cm ₂ . Evaluated.

○: Good (no occurrence at all)

△: blocking less than 10% per total area

×: Blocking more than 10% per total area

[Examples 2 to 5]

It was carried out in the same manner as in Example 1 but changing the manufacturing conditions as shown in Table 1.

[Comparative Examples 1 to 7]

It was carried out in the same manner as in Example 1, but the manufacturing conditions were changed as shown in Table 1 below.

In Table 1, “sil” is silica, “al” is alumina, and “tan” is calcium carbonate.

As can be seen from the results shown in Table 1, in the case of the polyester sheet prepared from the embodiment of the present invention, the general physical properties showed very good results, whereas the comparative example showed the weak characteristics according to the test items. Particularly, Comparative Example 1, in which the intrinsic viscosity of the polyester resin used as the substrate was 0.520 dl / g and the glass conductivity was 65 ° C. or lower, was not only poor in moldability but also poor in light transmittance. It was poor and good results could not be obtained in blocking resistance.

In addition, in the case of Comparative Example 2 without the addition of sulfonic acid metal salt, the surface resistance was 10 ¹⁵ kPa, which was the highest, indicating that the antistatic property was very weak.

In the case of Comparative Example 3, the fine particles used to improve the activity was not added at all, and as a result, it was found that the moldability and the blocking resistance were poor, and the friction coefficient was also slightly higher as 0.6. Could know.

Comparative Example 6, which had no starch powder applied to the sheet surface, was the weakest blocking resistance, and Comparative Example 6, which did not apply starch powder at all, had the weakest blocking resistance and very high surface resistance and friction coefficient. The results were also bad for sex.

Unlike Comparative Example 6, in the case of Comparative Example 4, starch powder was applied to the sheet surface, but the metal ions were not adsorbed on the surface of the starch powder particles. there was.

As described above, the present invention is formed into a sheet by mixing a sulfonic acid metal salt derivative having a suitable acid value and an inorganic fine particle of an appropriate size to a polyester resin having a range of intrinsic viscosity and glass transition temperature, and then containing starch as a main component. By surface treatment with the coating liquid, sheet physical properties are not lowered by additives, as well as excellent transparency, antistatic property and activity, excellent blocking resistance and moldability, and thus, non-stretched poly which can greatly improve productivity. It is a useful invention to provide a process for preparing an ester sheet.

Claims (2)

At least 60% by weight of the main repeating unit is made of ethylene terephthalate and has a polyester resin having an intrinsic viscosity of 0.6 to 1.0 dl / g and a glass transition temperature of 70 to 85 ° C. and an acid value of 1.0 mgKOH / g or less. After melting or extruding in the state of adding a single or a mixture of the sulfonic acid metal salt derivative compounds of Formula 1 or Formula 2 and fine particles having an average particle diameter of 0.01 to 0.1 μm, and forming a sheet, starch powder having an average particle diameter of 10 to 50 μm is applied to the sheet surface. In the method for producing a non-stretched polyester sheet to apply, the starch powder is a method of producing a non-stretched polyester sheet, characterized in that the copper, silver or magnesium surface-treated at 0.001 to 0.1mg / g relative to the starch weight. [Formula 1] [Formula 2] In Formula 1 or Formula 2, R ₁ is an alkyl group having 1 to 10 carbon atoms, R ₂ is an alkyl group having 8 to 25 carbon atoms, and M is an alkaline earth metal element or an alkali metal element including Li, Na, or Mg. The method for producing an unstretched polyester sheet according to claim 1, wherein the polyester resin mixture is extruded at 15 to 40 캜 after extruding the polyester resin mixture while the extrusion temperature is maintained at 250 to 300 캜.