JPH0760924A - Multilayer polyester sheet - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain an amorphous polyester resin sheet having good antistatic properties and excellent transparency. [Structure] On both surfaces of the transparent polyester resin base layer,
A surface layer made of a composition containing 0.05 to 2 parts by weight of glycerin fatty acid ester is formed with respect to 100 parts by weight of a polyester resin to form a multilayer sheet. This sheet can be obtained as a non-stretched or low-stretched sheet. [Effect] By containing a glycerin fatty acid ester, which is highly effective as an antistatic agent, in the surface layer, excellent antistatic properties can be obtained without impairing transparency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer polyester for use in applications such as cutting into a predetermined shape and bending to obtain a case-like body, or obtaining a blister or container by thermoforming such as vacuum forming. Regarding the seat.

[0002]

2. Description of the Related Art A polyethylene terephthalate (PET) sheet in an unstretched or amorphous state has excellent transparency as compared with a polyvinyl chloride resin sheet or an unstretched polypropylene sheet, and is easy to treat after use. So it is suitable as a transparent case for cosmetics and dolls.

In order to manufacture such a case, the sheet is cut into a predetermined shape, bent along a folding ruled line, and then an adhesive is applied to the adhesive margin portion, or the adhesive margin portion and the inner surface of the case are joined together. A small amount of solvent is sandwiched between them to perform adhesion, and the desired case shape is finished.

[0004]

However, the amorphous PET sheet is easily charged with static electricity, dust is attached to the surface of the sheet to generate whiskers at the time of printing, and dust is attached to the case after assembly to increase the commercial value. There is a problem of lowering it. The adhesion of dust also poses a problem in thermoforming applications and the like. To improve the antistatic property of a PET sheet, a method of kneading an antistatic agent having good heat resistance such as an alkali metal salt of alkylsulfonic acid or an alkali metal salt of alkylbenzenesulfonic acid is generally adopted. If the addition amount is within the range where the transparency can be maintained, the antistatic effect is insufficient, and if the addition amount is increased, the transparency is lowered and it cannot be practically used as a transparent sheet.

Other polyalkylene glycols have been investigated, but their heat resistance is insufficient, and the mechanical strength of the sheet is lowered and the sheets are colored due to oxidative decomposition or thermal decomposition, which is not preferable. Further, although a cationic antistatic agent has a great antistatic effect, it has a problem in food hygiene and cannot be used. Also, a method of applying an antistatic agent to the surface of the sheet may be considered, and although the antistatic property is certainly improved, it often causes problems in terms of durability of effect, printing, and adhesive properties, making it difficult to practically use. Is.

[0006] Another problem is that the amorphous PET sheet has poor slippage, so that there is a problem such as a supply trouble when the sheet is supplied to the printing machine during case processing. In addition, there is also a problem in that the assembled cases are badly slipped and the surface of the cases is easily scratched.

[0007]

The present invention provides a multilayer polyester sheet having an excellent antistatic property without impairing the transparency of the sheet, and particularly, by utilizing the excellent transparency, It is a sheet suitable as a folding sheet used for forming a ruled line and bending it to obtain a transparent case. That is, the gist of the present invention is to provide a polyester resin 10 on both surfaces of a transparent polyester resin base layer.
0 to 0 parts by weight of glycerin fatty acid ester 0.05 ~
A multilayer polyester sheet having a surface layer formed of a composition containing 2 parts by weight.

The present invention will be described in detail below. The sheet of the present invention has a multi-layer structure in which a transparent polyester resin substrate layer is formed on both surfaces with surface layers made of a glycerin fatty acid ester-containing polyester resin. The base layer is made of a transparent polyester resin, particularly an ethylene terephthalate polyester resin. This layer is preferably not highly oriented and is substantially not crystallized (amorphous state) for secondary processing such as bending and thermoforming.

As the polyester resin of this base layer,
A homopolymer of ethylene terephthalate or a copolymer in which 60 mol% or more, preferably 90 mol% or more of the dicarboxylic acid component is terephthalic acid and 60 mol% or more, preferably 90 mol% or more of the diol component is ethylene glycol. , Or a mixture of these polyester resins.

As the copolymerization component, dicarboxylic acids such as isophthalic acid, phthalic acid, adipic acid, sebacic acid and neopentylic acid, and diol components such as diethylene glycol, polyalkylene glycol, neopentyl glycol and 1,4-cyclohexanedimethanol are used. Can be mentioned.

The ethylene terephthalate polyester resin is relatively inexpensive, can be easily formed into a sheet, and has excellent strength, rigidity, transparency and bending workability. In most cases, the most readily available polyethylene terephthalate (homopolymer) is sufficient for the base layer,
It is also preferable in terms of characteristics.

The polyester resin base layer preferably has a haze of 3% or less, particularly 2% or less. This can be easily obtained by adding a lubricant or an antistatic agent which impairs transparency to the polyester resin of the base layer, or by adding a trace amount thereof, and by adopting sheet molding conditions in which crystallization is not promoted.

The polyester resin layer serving as the surface layer of the sheet of the present invention is formed by adding glycerin fatty acid ester as an antistatic agent to the polyester resin. As the polyester resin for the surface layer, various polyester resins including those similar to the polyester resin used for the base layer can be used, but as the folding sheet, in consideration of solvent adhesiveness, a non-described It is preferable to use a crystalline copolyester.

As the glycerin fatty acid ester, there are monoglyceride, acetylated monoglyceride and the like, which is 250 to 300 which is the molding temperature of the polyester resin.
It is desirable that thermal decomposition or oxidative decomposition does not occur at ℃,
In this respect, monoglyceride is particularly preferable. Examples of monoglycerides include glycerin monopalmitate, glycerin monostearate, glycerin monobehenate, and glycerin monocaprylate, and those modified in various ways to improve thermal stability can also be used.

The amount of glycerin fatty acid ester added varies slightly depending on the type, but in order to prevent dust from adhering, the surface resistivity of the sheet (JIS K691
1) is preferably 1 × 10 ¹⁶ Ω or less, particularly 1 × 10 ¹⁵ Ω or less, and the general addition amount therefor is 0.05 parts by weight or more based on 100 parts by weight of the polyester resin.
If it is less than 0.05 part by weight, the antistatic property is low. On the other hand, 2
When the amount is more than the weight part, the transparency is lowered and the adhesiveness and the printability are impaired. Therefore, the preferable range is 0.05 to 2% by weight, and the particularly preferable range is 0.3 to 0.5 part by weight.

When the sheet of the present invention is used as a sheet for folding, it is preferable to use an amorphous copolyester resin as the polyester resin of the surface layer. When a case is manufactured by a folding process, a folded end of a sheet may be adhered with a solvent, but a crystalline polyester resin is crystallized and whitened by coming into contact with the solvent. Therefore, by constituting the surface layer with an amorphous polyester resin, good adhesion can be achieved without causing whitening with a general-purpose solvent such as tetrahydrofuran, cyclohexanone, ethyl acetate, 1,1,2-trichloroethane.

The term "amorphous" as used herein means that a polyester resin or a polyester resin mixture is measured by a differential scanning calorimeter (DSC-7 type manufactured by Perkin Elmer Co., Ltd.) from a molten state.
It means that the heat of crystallization (ΔHc) when the temperature is lowered at a rate of ° C / min is 5 cal / g or less.

Examples of the amorphous copolymerized polyester resin include those containing a relatively large amount of the copolymerized component as described for the polyester resin used for the base layer. Specifically, isophthalic acid 20 to 4
An amorphous copolyester resin comprising a residue of a dicarboxylic acid containing 0 mol% and the remainder being terephthalic acid and a residue of a diol mainly containing ethylene glycol can be mentioned. This resin has an advantage that it can be obtained at a relatively low cost as an amorphous polyester resin.

An amorphous copolymer composed of a residue of a dicarboxylic acid mainly containing terephthalic acid and a residue of a diol containing 20 to 60 mol% of 1,4-cyclohexanedimethanol and the balance being ethylene glycol. Polyester resin can also be used suitably.

These amorphous copolyester resins may contain a small amount of dicarboxylic acids such as phthalic acid, adipic acid and sebacic acid, or components such as propylene glycol, triethylene glycol and diethylene glycol.

Particularly preferred is the latter, that is, an amorphous copolyester resin comprising a residue of a dicarboxylic acid mainly containing terephthalic acid and a residue of a diol containing 20 to 60 mol% of 1,4-cyclohexanedimethanol. Is. An unstretched amorphous polyester sheet made of PET or a copolyester resin has a problem that the impact strength characteristics of the sheet deteriorate and become brittle after a few months after the sheet is manufactured. The resin did not decrease in strength with time, and by using this resin as the surface layer, it was possible to improve the strength decrease and brittleness of the entire sheet. This amorphous resin was also superior to other amorphous copolyester resins in that it did not cause whitening during solvent adhesion.

The intrinsic viscosity of the polyester resin of the base layer and the surface layer of the sheet of the present invention is preferably 0.5 or more, particularly 0.6 or more. When it is lower than 0.5, the strength of the sheet becomes low, which is preferable. Absent.

The thickness of the sheet of the present invention is not particularly limited and may be appropriately set depending on the application, but is usually about 60 to 500 μm, and particularly about 200 to 400 μm. this house,
The thickness of the polyester resin base layer can be appropriately set depending on the application, but is generally 50 to 400 μm, for example, 150 μm or more for a sheet for bending, and preferably 200 to
In the thickness range of 400 μm, it is preferable that the haze has a transparency of 3% or less, particularly 2% or less as described above.

The thickness of the surface layer is generally 5 to 50 μm on one side because of the balance between functionality such as antistatic property and transparency.
The degree. Usually, the objective can be achieved when the surface layer thickness (total of both sides) of the total sheet thickness is about 15 to 30%. Especially when it is used as a sheet for folding, if the surface layer has a thickness of 15 μm or more, preferably 20 μm or more, it is possible to prevent the solvent from penetrating into the base layer and whitening.

Various additives such as stabilizers, lubricants, ultraviolet absorbers, pigments and other thermoplastic resins can be added to the sheet of the present invention within the range of not impairing transparency. Since the surface layer of the sheet of the present invention is generally thin, it is possible to improve the slipperiness without significantly impairing the transparency of the sheet by adding a lubricant which tends to impair the transparency, to the surface layer.

As described above, in order to improve the slipperiness of the sheet, it is preferable to add inert particles to the surface layer. The inert particles include silica, titanium oxide, calcium carbonate, iron oxide and aluminum oxide. Various inorganic particles such as inorganic particles of calcium oxide, magnesium oxide or the like or a mixture thereof; inorganic compounds such as talc and clay; organic compounds such as high melting point organic compounds and cross-linked polymers can be used. It is desirable that the particles have high affinity with the polyester resin in order not to reduce the transparency, and silica particles are particularly preferable from this viewpoint. It is also effective to use an organic lubricant such as fatty acid amide or various waxes in combination with these inert particles.

The above particles preferably have an average particle size of 2 to 10 μm. When the particle size is less than 2 μm, the unevenness formed on the surface of the sheet is small and the slip improving effect is small. It has a negative effect on sex. In particular, those in the range of 3 to 6 μm are suitable. Here, the average particle diameter of the particles was measured by using a Coulter Counter (manufactured by Nippon Kagaku Kikai Co., Ltd.) and the particle diameter when the cumulative weight fraction was 50% was defined as the average particle diameter.

The amount of particles added is preferably 0.05 to 0.5 parts by weight, particularly 0.1 to 0.3 parts by weight, based on 100 parts by weight of the polyester resin in the surface layer, and less than 0.05 parts by weight. The slip improving effect is small, and if it exceeds 0.5 parts by weight, the transparency and adhesiveness of the sheet are deteriorated.

From the viewpoint of the balance between slipperiness and other characteristics, a generally preferred sheet surface roughness is 0.2 to 2 μm in terms of 10-point average surface roughness (Rz) defined by JIS B0601, and the addition of particles. The surface roughness can be adjusted by the amount and the particle size.

In order to further improve the slipperiness of the sheet,
It is also possible to stretch a sheet in which inert particles are added to the surface layer at a low magnification. Since the inactive particles are projected on the surface of the sheet by stretching, the slipperiness can be improved by adding a relatively small amount of particles. When it is stretched, it is stretched 1.05 to 2 times in at least one direction. If the draw ratio is less than 1.05 times, there is no improvement effect on the slipperiness by drawing, and if it exceeds 2 times, the slipperiness is not so improved, but the secondary workability such as transparency, bending workability and thermoformability is not improved. Will be adversely affected. The preferred draw ratio is 1.1 to 1.6 times.

The stretching method is to obtain a non-oriented multilayer sheet,
Stretching is performed in the longitudinal direction with a speed difference between the rolls, and if necessary, stretching is also performed in the width direction using a tenter. In terms of manufacturing cost, it is desirable to stretch only in the longitudinal direction. Unlike ordinary stretching for increasing the strength of the sheet, this stretching is for forming projections of particles on the surface, so that it is preferable to carry out at a relatively high temperature condition, and usually 90
Perform at ~ 100 ° C.

In order to obtain the sheet of the present invention, it is possible to form each layer in advance and then laminate and bond them by heat or an adhesive. However, in practice, a die with a feed block, a multi-manifold die, etc. are used. It may be obtained by extruding the molten multilayer sheet onto a cooling drum by a coextrusion method and quenching. The resulting sheet is substantially non-oriented and is in a substantially amorphous state. When stretched at a low ratio, the sheet is in a low orientation and is substantially in an amorphous state.

[0033]

EXAMPLES In the following examples, the properties of the sheets were evaluated by the following methods.

1) Haze JIS K7105 2) Friction coefficient JIS K7215 3) Surface specific resistance JIS K6911 4) Impact strength High speed impact tester (Shimadzu Corporation,
It was measured with a Hydroshot impact tester HTM-1) at a test speed of 3 m / sec.

(Example 1) Copolymerized polyester having an diol component of 67 mol% of ethylene glycol and 33 mol% of 1,4-cyclohexanedimethanol and a dicarboxylic acid of terephthalic acid (intrinsic viscosity 0.8) was used as a surface layer and an ultimate limit. A three-layer sheet having a base layer (center layer) of polyethylene terephthalate having a viscosity of 0.65 was produced from a T-die by a co-extrusion method.
It was extruded at 85 ° C and cast on a cooling drum at 40 ° C so that both surface layers were 25 μm each and the substrate layer was 200 μm.
A layered sheet was created.

The following (A), (B) or (C) as an antistatic agent was added to the surface layer in an amount shown in Table 1.
The evaluation results of the sheet are shown in Table 1.

(A) Glycerin monobehenate (B) Glycerin monostearate modified product (C) Sodium alkyl sulfonate

[Table 1]

Antistatic agents (A) and (B) are added in an amount of 0.05 to 2
The sheet of the present invention added in the range of 10 parts by weight has a surface resistivity of 10 ¹⁶ Ω or less while maintaining good transparency, and particularly when the addition amount of the antistatic agent is in the range of 0.3 to 0.5 parts by weight. The best results were shown. Further, even if the amount exceeds 2.0 parts by weight (No. 12), the transparency does not decrease significantly, but stickiness due to a large amount of bleeding of the antistatic agent on the sheet surface causes problems such as poor printability and blocking. It occurs and cannot be used practically. Further, the sheet to which the antistatic agent (C) was added showed a large antistatic effect even if added in a small amount, but was inferior in that the transparency was greatly reduced.

Example 2 The substrate layer was the same polyethylene terephthalate as in Example 1, and the surface layer was the following (a),
As polyester resins (b) and (c), 0.3 part by weight of glycerin monostearate modified product and silica fine particles having an average particle diameter of 2.5 μm were added to the surface layer in the amounts shown in Table 2. Then, in the same manner as in Example 1, a non-oriented three-layer sheet was prepared.

Next, this sheet was left unoriented and the sheet was stretched in the lengthwise direction at a temperature of 90 ° C. at a magnification shown in Table 2 by a roll type longitudinal stretching machine. The sheet thickness was finally set to 250 μm (both surface layers each 25 μm, base layer 200 μm).

(A) Polyethylene terephthalate (intrinsic viscosity 0.65, ΔHc = 42 cal / g) (b) The diol is ethylene glycol 67 mol% and 1,
Amorphous copolymer polyester in which 4-cyclohexanedimethanol is 33 mol% and dicarboxylic acid is terephthalic acid (intrinsic viscosity 0.8, ΔHc = 0 cal / g) (c) Dicarboxylic acid is 78 mol% terephthalic acid and isophthalic acid 22 Amorphous copolyester with mol% and ethylene glycol as the diol (intrinsic viscosity 0.7, Δ
Hc = 0 cal / g) Table 2 shows the evaluation results.

[0042]

[Table 2]

From these results, it can be seen that the slipperiness of the sheet is significantly improved by adding silica.
When the sheet is stretched, the transparency is slightly lowered, but the slipperiness is further improved. These sheets were punched out as shown in FIG. 1 and provided with folding ruled lines, and then a small amount of ethyl acetate was applied to the adhesive margin portion and solvent bonding was performed to assemble them into a case, and polyester (b), (c) The sheet using as a surface layer was able to perform firm adhesion without whitening. However, the sheet using the polyester (a) as the surface layer was whitened and was not suitable for use in solvent adhesion. The surface resistivity of each sheet was 10 ¹⁴ order, and the antistatic property was good.

(Embodiment 3) No. 3 showing good results in Embodiment 2 With respect to 16, 19, 21 and 27, the impact strength immediately after the sheet production and after standing at 50 ° C. for 2 days was measured. The results are shown in Table 3.

[0045]

[Table 3]

As a result, the above polyester (b) was used as the polyester resin for the surface layer (No. 19,
21) showed the best results in the initial strength and the strength after aging.

[0047]

INDUSTRIAL APPLICABILITY The sheet of the present invention contains a glycerin fatty acid ester as an antistatic agent in a thin surface layer and thus has an excellent antistatic property without impairing the transparency of the sheet, and can be used for various bending processes. Can be suitably used for

Claims (5)

[Claims] 1. A multi-layer polyester sheet comprising a transparent polyester resin substrate layer and a surface layer formed on both surfaces of the polyester resin substrate layer, the surface layer comprising a composition containing 0.05 to 2 parts by weight of glycerin fatty acid ester per 100 parts by weight of the polyester resin. . 2. The polyester resin on both surfaces has a residue of a dicarboxylic acid mainly composed of terephthalic acid and a residue of a diol in which 20 to 60 mol% of 1,4-cyclohexanedimethanol is contained and the balance is ethylene glycol. Amorphous copolyester resin consisting of or isophthalic acid 2
2. An amorphous copolyester resin comprising, as a main component, a residue of a dicarboxylic acid containing 0 to 40 mol% and the balance being terephthalic acid and a residue of a diol mainly containing ethylene glycol. Multi-layer polyester sheet. 3. The surface layer contains 0.0% of inert particles having an average particle diameter of 2 to 10 μm per 100 parts by weight of a polyester resin.
The multilayer polyester sheet according to claim 1 or 2, which comprises 5 to 0.5 parts by weight. 4. The multilayer polyester sheet according to claim 1, 2 or 3, wherein both surface layers each have a thickness of 5 to 50 μm. 5. On both surfaces of the transparent polyester resin base layer, 0.05 to 2 parts by weight of glycerin fatty acid ester is added to 100 parts by weight of the polyester resin, and the average particle diameter is 2 to 2.
A substantially non-oriented multilayer polyester sheet formed by forming a surface layer made of a composition containing 0.05 to 0.5 parts by weight of 10 μm inert particles in at least one direction of 1.0
A multilayer polyester sheet formed by stretching 5 to 2 times.