JPH08142293A - Polyester sheet of excellent lubricity - Google Patents

Abstract

PURPOSE: To obtain a polyester sheet in which lubricity and cutting properties are improved without impairing working characteristics of transparency, printing properties, etc., by a method wherein a specified ester product is blended in a polyester polymer of a specified composition by jointly using inert particles having a specified secondary particle series. CONSTITUTION: Dicarboxylic acid constituent having terephthalic acid as main constituent, and glycol constituent of 90-10mol% of ethylene glycol and 10-90mol% of 1.4-cyclohexanedimethanol by ratio are condensation polymerized. A skin layer is provided wherein 0.01-5wt.% of an ester product of 10-10000ppm of inert particle of 1-10μm in mean particle size of secondary particle, 0-2000ppm of 10-30μm inert particle, polyhydric alcohol having at least 3 hydroxyl groups, and at least 12C aliphatic monocarboxylic acid is blended in polyester polymer of 0.4-1.1 intrinsic viscosity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester sheet having improved slipperiness, blocking property and cutting property without impairing processing properties such as transparency, printability and adhesiveness.

[0002]

2. Description of the Related Art Saturated polyesters, particularly crystalline polyester resins typified by polyethylene terephthalate (hereinafter abbreviated as PET) are widely used as polymers for sheets and films including fibers, but have excellent chemical resistance. It has come to be applied to carbonated drinks, juices, bottles for beverages such as beer, cosmetics containers, food trays, etc., by taking advantage of its low gas permeability.

Among them, the amorphous polyester sheet called A-PET has attracted attention for its excellent recyclability, low pollution and food safety, and its use amount has rapidly increased in recent years as a packaging material replacing vinyl chloride and polystyrene. ing. This polyester sheet is used as a blister bag for food and medicine containers and miscellaneous goods by thermoforming,
Utilizing its excellent transparency, it is used as a clear case in which cosmetics, electric devices, etc. are put.

Conventionally, when such saturated polyester sheets are stacked, it is difficult to take out the sheets one by one during transportation, because the inherent stickiness of the polyester resin causes blocking between the sheets. In addition, the cutting property when the sheets are bundled is extremely poor, and it cannot be used as a sheet-shaped product such as used for vinyl chloride, and improvement has been desired.

Many proposals have hitherto been made on methods for improving the slipperiness of polyester. For example, JP-A-50-
As described in JP-A-45885, JP-A-4-136063 and JP-A-4-180957, inert particles such as silicon oxide, calcium carbonate, talc, kaolin and wollastonite are added at the time of polymerization or a sheet. There is a method of adding during film formation (inert particle addition method). In these methods, as described in JP-A-52-1279667, weak stretching in a range that does not impair thermoformability causes the fine particles contained therein to cause unevenness on the surface of the sheet, thus giving slipperiness. However, the substantially non-stretched sheet has insufficient sliding properties. Therefore, in order to provide sufficient slipperiness, it is necessary to increase the amount of particles to be blended, which causes deterioration of the transparency and mechanical properties of the sheet, which is a problem.

Further, as described in JP-A No. 53-14753, a method in which a part or all of a catalyst, a coloring preventing agent and the like used in polyester polymerization are precipitated in the course of the reaction and exist as fine particles (internal particle forming method). Alternatively, JP-A-49-117550 and JP-A-57-1475.
The method of blending a resin with a high melting point or a resin with a high Tg (resin blending method) as described in JP-A No. 43-11055 and JP-A No. 1-110555 has almost no effect in improving slipperiness in an unstretched state.

Further, as described in JP-B-44-8759 and JP-A-60-61259, there is a method of spraying fine powder on the surface of the sheet or coating or printing a coating film having slipperiness. These methods tend to impair the appearance and physical properties because it is difficult to apply and apply evenly. Further, a method of coating silicon on the surface is also widely used, but it causes a decrease in heat sealability, printability, and adhesiveness, and its use is extremely limited.

[0008]

DISCLOSURE OF THE INVENTION As a result of intensive studies made by the present inventors in order to solve such conventional problems, a polyester-based polymer having a specific composition and an inactive material having a specific secondary particle system is obtained. By using particles in combination at a specific ratio, and further blending an ester product of a specific polyhydric alcohol and an aliphatic monocarboxylic acid, the transparency of A-PET even in a substantially amorphous non-oriented polyester sheet, It was found that excellent slipperiness can be imparted without impairing the heat-sealing property, and the present invention has been completed.

[0009]

That is, the present invention provides (A) a dicarboxylic acid component containing terephthalic acid as a main component, 90 to 10 mol% of ethylene glycol, 1.4-cyclohexanedimethanol (hereinafter 1.4-CHDM). 10)
Polycondensation of a glycol component in a proportion of ˜90 mol%,
In addition, the polyester-based polymer having an intrinsic viscosity of 0.4 to 1.1, the secondary particles having an average particle diameter of 0.1 to 10 μm, the inert particles of 10 to 10000 ppm, and the inert particles of 10 to 30 μm are used. A skin layer containing 0.01 to 5% by weight of an ester product of a polyhydric alcohol having 2000 ppm and 3 or more hydroxyl groups and an aliphatic monocarboxylic acid having 12 or more carbon atoms, (B) terephthalic acid and ethylene Glycol is polycondensed and has an intrinsic viscosity of 0.4-1.
1. A polyester laminate comprising a core layer made of a polyester of 1, wherein the (A) layer is laminated on at least one side, and the (A) layer is 1 to 30% of the total thickness of the sheet. It is a substantially amorphous non-oriented polyester sheet in the range of 1) and a packaging container obtained by punching, bending, and assembling the sheet.

The copolymerized polyester (A) to be laminated on the surface used in the present invention is a dicarboxylic acid component containing terephthalic acid as a main component and ethylene glycol 90 to 10 mol%, 1.4-CHDM 10 to 90 mol%. It is obtained by polycondensing the glycol component of.

The amount of 1.4-CHDM copolymerized is preferably 15 to 85 mol%. When it is less than 10 mol% or more than 90 mol%, the compatibility of the polyhydric alcohol compounded as the organic lubricant with the ester composed of fatty acid is deteriorated, and not only the transparency of the sheet is deteriorated, but also It is not preferable because the adhesive strength of a solvent-based adhesive containing methyl ethyl ketone, tetrahydrofuran or the like as a main component, which is generally used for adhesion of a clear case, decreases. The ratio of cis and trans of 1.4-CHDM to be used is not particularly limited, but 4: 6 to 0:10 is preferable in terms of impact strength.

The polyester (B) used in the core layer of the present invention is not limited to PET, but a part of the terephthalic acid component is isophthalic acid, adipic acid, diphenylcarboxylic acid,
Substituting one or more other dicarboxylic acid components such as diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, sebacic acid, naphthalene dicarboxylic acid, etc., and part of the ethylene glycol component is diethylene glycol, hexamethylene glycol, trimethylene glycol, propylene glycol, Included are copolyesters substituted with one or more of the other above glycol components such as cyclohexanedimethanol, neopentyl glycol, styrene glycol and the like.

The total proportion of the copolymerization components in the polyester (B) is preferably 40 mol% or less based on the total acid components. Further, a compound having three or more functional groups or a monofunctional compound may be contained within the range considered to be substantially linear.
Further, a heat stabilizer, a fluidity improver, an ultraviolet absorber, an antistatic agent, an antifogging agent and the like can be added to the polyester within a range that does not reduce the transparency. Further, when matting is required, a coloring agent such as titanium dioxide, calcium carbonate, iron oxide or carbon black may be contained.

The intrinsic viscosity of the polyester used in (B) in the present invention is 60/40 in weight ratio of phenol / phenol at 20 ° C.
When measured in a mixed solvent of tetrachloroethane, the intrinsic viscosity is required to be 0.4 to 1.1, and particularly preferably 0.6 or more. If it is less than 0.4, the mechanical strength of the final product is not sufficient, and especially the impact strength at low temperature and the ductility during clear case bending are insufficient. On the other hand, the intrinsic viscosity is 1.
When it exceeds 1, not only the economical efficiency is deteriorated but also the melt moldability during the film formation becomes difficult.

The sheet thickness is not particularly limited, but is usually 50-
It is 1500 μm, preferably 150 to 800 μm.

The inert particles used in the present invention are talc, silica, calcium carbonate, alumina, wollastonite, kaolin, zinc oxide, barium sulfate, calcium phosphate, aluminum hydroxide, Ca, Ba, Zn, M.
Examples thereof include terephthalate salts such as n and crosslinked polymers, and particles having a refractive index close to that of amorphous polyester are advantageous in terms of transparency.

These may be used alone or in combination, or may be added as a slurry at the time of polymerization in order to disperse them uniformly in the sheet, or within a range not deteriorating the transparency of the sheet, an olefin wax, a fatty acid or a metal salt of a fatty acid. The surface treatment of the particles may be carried out by, for example, In order to prevent the occurrence of scratches due to the friction of the sheet, inert particles having a Mohs hardness of 5 or less, such as polystyrene (hereinafter referred to as PS)
It is effective to use crosslinked particles such as polymethylmethacrylate.

The inert particles have secondary particles having an average particle size of 0.
Fine particles of 1 to 10 μm 10 to 10,000 ppm, preferably fine particles of 3 to 10 μm 100 to 20
00 ppm and particles having an average particle size of secondary particles of 10 to 30 μm 0 to 2000 ppm, preferably 10 to 25 μm
10 to 1000 ppm of particles are required.

The former fine particles having an average particle diameter of 0.1 to 10 μm alone can sufficiently provide slipperiness, but the latter particles having a rather large particle diameter are used in combination to produce a synergistic effect. Sliding property can be imparted by mixing a small amount of inert particles.

When the average particle size of the inert particles is less than 0.1 μm or the compounding amount is less than 10 ppm, the unevenness per unit area of the sheet is insufficient, or the height of the unevenness is low, so that the slipperiness is insufficient and the sheet is Blocking occurs when overlapping. In addition, the average particle size of the inert particles exceeds 30 μm, or the compounding amount is 12000 pp.
If it exceeds m, the transparency of the sheet is deteriorated and scratches occur during sheet conveyance, which is not preferable.

The ester product used in the present invention must be composed of a polyhydric alcohol having 3 or more hydroxyl groups and an aliphatic monocarboxylic acid having 12 or more carbon atoms.
An ester composed of an alcohol having less than 3 hydroxyl groups of a polyhydric alcohol has a good compatibility with the above polyester, and therefore the amount of bleed-out on the surface of the sheet is small and sufficient slipperiness cannot be provided. Examples of such polyhydric alcohols having three or more hydroxyl groups include glycerin, pentaerythritol, sorbitol, xylitol, mannitol and the like.

When the aliphatic monocarboxylic acid used to obtain the ester product has less than 12 carbon atoms, the heat resistance of the ester product is insufficient, and when it is compounded in PET or the like, it is formed into a sheet. Not only the sliding effect is very low due to hydrolysis caused by heating during film formation, but also the mechanical properties of the sheet itself are extremely low.

Examples of such an aliphatic monocarboxylic acid having 12 or more carbon atoms include tridecyl acid, myristic acid, pentadesilyl acid, palmitic acid, margaric acid, stearic acid, nonadesilyl acid, arachidic acid, heneisancoic acid,
Examples thereof include behenic acid, tricosanoic acid, lignoceric acid, pentacosanoic acid, cerotic acid, heptacosanoic acid, montanic acid, nonacosanoic acid, and melissic acid.

The amount of the ester product required to impart good slipperiness to the sheet is 0.01 to 5% by weight, preferably 0.05 to 2% by weight. If the blending amount is less than 0.01% by weight, sufficient slipperiness cannot be provided. Further, when the compounding amount exceeds 5% by weight, the bleed-out amount on the surface of the sheet is too large, and thus the printability,
Workability such as adhesiveness is significantly reduced and transparency is impaired.

Among the esters produced from the polyhydric alcohol and the aliphatic monocarboxylic acid, compounds containing two or more ester bonds are preferable in terms of heat resistance.

The sheet can be obtained by melt-extruding using a conventional extruder for polyester such as a single-screw extruder or a twin-screw vent extruder, and cooling the molten resin with a cooling drum. It is preferable to cool the sheet as rapidly as possible in order to prevent a decrease in transparency due to crystallization, and the crystallinity measured by the density method is 1
0% by weight or less (density 1.348 g / cm ³ or less) and sheet haze are preferably 5% or less.

As a film forming method, there are a method of sandwiching and cooling between metal rolls (touch roll method), an electrostatic application method, an air knife method and the like, but the touch roll method is used in view of glossiness and thickness uniformity of the sheet. preferable. A known method can be applied to the method of adding the inert particles to be mixed with the polyester or the ester formed from the polyhydric alcohol and the aliphatic monocarboxylic acid, and there is no particular limitation. For example, the components are preliminarily uniformly blended with a tumbler or a blender, and the mixture is fed to an extruder, or the components to be added to the polyester are preliminarily pelletized as a masterbatch and fed at the time of extrusion, polymerization. There is a method to add it sometimes.

When a multilayer sheet having two or more layers is formed, it can be produced by known techniques such as melt lamination, coextrusion and dry lamination, but the coextrusion method is preferable from the quality of the sheet. The ratio of the skin layer of the sheet to the total thickness of the sheet is 1 to 30%, but 3 to 20% is preferable from the viewpoint of economy and stability of quality. When the proportion of the skin layer is less than 1%, it becomes difficult to uniformly form the skin layer containing the inert particles and the ester of the polyhydric alcohol and the monocarboxylic acid at a high concentration, and slipperiness and the like are deteriorated. Be stable. On the other hand, the skin layer is 30%
Even if it is increased, the slipperiness is not further improved, and the transparency of the sheet tends to be lowered, which is not preferable.

The product of the present invention maintains the excellent recyclability originally possessed by A-PET, and the ears of the sheet generated during film formation of the sheet or the skeleton generated during the punching process are crushed and the sheet is re-sheeted. It can be used as a raw material. These recycled raw materials can be returned to both the skin layer and the core layer of the product of the present invention. However, when returning to the core layer, the concentration of the inert particles and the fatty acid ester contained in the core layer needs to be 50% or less of the amount blended in the skin layer. When the concentration of the inert particles and the fatty acid ester contained by returning the recycled raw material exceeds 50% of the skin layer, the transparency of the sheet is significantly lowered, which is not preferable.

The slipperiness and antiblocking property of the sheet are related to the performance of the surface portion of the sheet. Compared to the core layer, the skin layer contains a high concentration of inert particles and an ester of a polyol and a monocarboxylic acid. A multilayer structure is desirable. The core layer can maintain the transparency and mechanical properties of the sheet because the amount of the inert particles and the ester of the polyhydric alcohol and the monocarboxylic acid is smaller than that of the skin layer.

[0031]

INDUSTRIAL APPLICABILITY The present invention is excellent in slipperiness, blocking resistance, solvent adhesiveness and cuttability without impairing processing characteristics such as transparency, printability and adhesiveness, and is cut into individual sheets. Ideal for making a sheet. Particularly, it is most suitable as a substitute material for vinyl chloride and rolled PP sheet, which are generally used as materials for clear cases. The method of punching, bending and assembling the sheet to obtain a packaging container may be any method used for vinyl chloride or polyolefin sheet.

The product of the present invention can be used as a container or a blister by thermoforming as in the conventional A-PET without any problem. The thermoforming method to be used may be vacuum forming, pressure forming, hot plate forming, plug assist forming, reverse draw forming, air slip forming, or the like, or a combination of these methods. Can also be used.

[0033]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
Each characteristic value was measured according to the following method.

(1) Sheet haze Using a haze meter NDH-20D manufactured by Nippon Denshoku Co., Ltd., the haze (haze value) of the sheet was measured by a method according to JIS-K-7105.

(2) Static friction coefficient Using a friction measuring machine TR type manufactured by Toyo Seiki, ASTM-18
The static friction coefficient of the sheet was measured by the method according to 94.

(3) Blocking property The blocking property of the sheets was evaluated by a method according to ASTM-1893.

(4) Heat-sealing property The sheets were adhered to each other at 180 ° C. for 2 seconds under a pressure of 2 kg / cm ² and the heat-sealing strength was measured by the method according to JIS-K-6772. Seal strength exceeding 500 g / 15 mm is ○,
Those with 200 to 500 g / 15 mm were evaluated as Δ, and those less than 200 g / 15 mm were evaluated as x.

(5) Solvent Adhesiveness A sheet is adhered using methyl ethyl ketone to JIS-K.
The peel strength was measured by a method according to -6772. Peel strength 2000g / 15mm
◯, those of 2000 to 500 g / 15 mm were evaluated as Δ, and those of less than 500 g / 15 mm were evaluated as ×.

(6) Average particle size MULTI made by Coulter Electronics Limited
The diameter (particle diameter) with an integrated volume fraction of 50% in the equivalent spherical distribution measured by the SIZER device was taken as the average particle diameter.

(7) Evaluation of surface irregularities The surface irregularities of the sheet were measured using a SURFCOM surface roughness meter manufactured by Tokyo Seimitsu Co., Ltd. according to JIS-B-0601.

(8) Impact strength of sheet Using a surface impact tester (Hydroshot) manufactured by Shimadzu Corporation, cracking at 25 ° C. under conditions of a punching speed of 5 m / sec, a punching punch diameter of 13 mm and a die diameter of 76 mm. The generated energy was measured.

Examples 1 to 6 and Comparative Examples 1 to 11 When measured at 20 ° C. in a phenol / tetrachloroethane mixed solvent having a weight ratio of 60/40, the intrinsic viscosity was 0.70.
Copolymerized PET (30 mol%, 1,4-CHDM) was dried to a water content of 200 ppm or less, and the inert particles having the particle size shown in the examples at 270 ° C. were mixed with a biaxial kneader.
It was melt-kneaded with ET resin to prepare a 2 wt% master. Similarly, a 10 wt% master of the ester product of the polyol and the aliphatic monocarboxylic acid shown in the examples was prepared.
When the melt extrusion is performed from the T-die using a twin-screw vent extruder under the conditions of 285 ° C. and the degree of vacuum of the vent portion is 5 mmHg, when the film is formed by the touch roll method, the master of these inert particles and ester Was blended with the polyester resin described in the example, and a sheet having a composition of the 250 μm-thick three-layer structure shown in the example was produced and evaluated.

[0043]

[Table 1]

[0044]

[Table 2]

Claims (4)

[Claims] 1. A dicarboxylic acid component containing (A) terephthalic acid as a main component, ethylene glycol 90 to 10 mol%, and 1.4-cyclohexanedimethanol 10 to 90.
Polyester polymer having an intrinsic viscosity of 0.4 to 1.1, which is obtained by polycondensing a glycol component in a mol% ratio, and inert particles having an average secondary particle size of 0.1 to 10 μm. 0.01 to 5 wt% of an ester product of a polyhydric alcohol having an inert particle size of 10000 ppm and 10 to 30 μm of 0 to 2000 ppm and a hydroxyl group of 3 or more and an aliphatic monocarboxylic acid having a carbon number of 12 or more. A polyester laminate comprising: a blended skin layer; and (B) a core layer made of polyester that is polycondensed with terephthalic acid and ethylene glycol and has an intrinsic viscosity of 0.4 to 1.1. A substantially amorphous non-oriented polyester sheet in which the layer (A) is laminated on at least one side, and the layer (A) is in the range of 1 to 30% of the total thickness of the sheet. 2. The sheet according to claim 1, wherein the concentration of the particles of the core layer (B) and the fatty acid ester is 50% or less of the concentration of the particles of the skin layer (A) and the fatty acid ester. Polyester sheet. 3. A polyester single-wafer product obtained by cutting the sheet according to claim 1 or 2. 4. A polyester packaging container obtained by punching, bending, and assembling the sheet according to claim 1, 2, or 3.