JP2000006346A - Multilayered polyester sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered polyester sheet developing excellent slip properties without losing transparency or appearance and capable of being processed by a conventional processing machine such as a cutter, a bending rule forming machine or a punching machine for a PVC sheet. SOLUTION: This sheet is constituted by forming a surface coating layer made of a polyester resin compsn. prepared by compounding 0.05-0.5 pts.wt. of inert particles having a average particle size of 3-12 μm and containing 5 wt.% or less of particles with a particle size of 15 μm or more on both surfaces of a transparent polyester resin substate sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multilayer polyester sheet. More specifically, it is suitable for cutting into a predetermined shape to form a folding ruled line and bending to make a case-like product, or for forming blisters and various containers by thermoforming such as vacuum forming method, etc. It relates to a polyester sheet.

[0002]

2. Description of the Related Art Conventionally, cosmetics, clothing, dolls, foods,
Transparent cases suitable for storing desktop slide calendars, video tapes, etc., and transparent blister cases for storing various small items are made from rigid polyvinyl chloride sheets from the viewpoint of cost and productivity. There were many things. However, recently, polyvinyl chloride (hereinafter referred to as “P
A transparent case made of a sheet made of “VC” may be used as a raw material. For this reason, production of a transparent case made of a PVC sheet has been voluntarily suppressed.

[0003] On the other hand, a transparent case that allows the stored articles to be visually observed from the outside is highly regarded by consumers and has a high utility value. Therefore, it is a transparent substitute for a PVC sheet and is suitable for molding a PVC sheet. There has been a need for a transparent case made of a sheet that can be used as it is without modifying a device for forming a folded crease, which has been used. Polystyrene, polycarbonate, polypropylene, polyester, and the like are known as resins having excellent transparency. The biaxially stretched polystyrene sheet has a drawback that it is easily broken when it is formed by forming a folding ruled line, and the polycarbonate sheet has a drawback that the raw material cost is high,
Further, the polypropylene sheet has a disadvantage that the transparency is slightly inferior. In contrast, polyester sheets are preferred because they do not have these disadvantages.

[0004]

When processing into a transparent case or the like, usually, about 200 to 300 transparent sheets are stacked and cut into a predetermined size by a cutting machine, and then a printing machine and a folding ruled line are used. It is supplied to a processing machine such as a forming machine or a punching machine to be processed. However, since the amorphous polyester sheet has poor slipperiness, it is easy to block,
Troubles such as cracking when cutting with a cutting machine, poor bite of the blade, etc., and blocking may occur when feeding continuously to the processing machine, so that it may not be supplied continuously There is a problem that occurs.

[0005] In order to solve the above-mentioned drawbacks, the present inventors first formed a layer containing an antistatic agent and inert particles on both surfaces of a polyester sheet to improve the slipperiness of the sheet surface. Proposed polyester sheet
609924). However, as a result of further investigation, the slipperiness, cutting property, continuous supply to a processing machine, and the like of the polyester sheet surface were improved, but the transparency and appearance of the sheet were sometimes insufficient depending on conditions.

The present invention has been made in view of the above circumstances, and as a result of diligent studies to provide a multilayer polyester sheet exhibiting excellent slipperiness without impairing transparency and appearance, the present invention has been completed. . The objects of the present invention are as follows. 1. Provided is a multilayer polyester sheet that exhibits excellent slipperiness without impairing transparency and appearance. 2. To provide a multilayer polyester sheet that can be easily processed by a conventional processing machine such as a cutting machine for PVC sheets, a folding crease forming machine, and a punching machine.

[0007]

In order to solve the above problems, in the present invention, a transparent polyester resin base sheet is provided on both surfaces with 100 parts by weight of a polyester resin.
The average particle size is 3 to 12 μm and the particle size is 15
A surface coating layer made of a polyester-based resin composition containing 0.05 to 0.5 parts by weight of inert particles having a content of particles of 5 μm or less of 5 μm or less is formed. To provide a multilayer polyester sheet.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, the polyester-based resin forming the base sheet refers to a resin obtained by polycondensing a dicarboxylic acid component and a diol component in equimolar amounts. A typical dicarboxylic acid component is terephthalic acid, but a part of terephthalic acid may be replaced with another dicarboxylic acid component. Other dicarboxylic acid components include oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, neopentylic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, p-oxybenzoic acid, p-oxyethoxy Benzoic acid, benzoic acid, benzoyl benzoic acid, and the like. These other dicarboxylic acid components may be one kind or a mixture of two or more kinds.

A typical diol component is ethylene glycol, but a part of the ethylene glycol may be replaced by another diol component. Other diol components include propylene glycol, trimethylene glycol,
Tetramethylene glycol, hexamethylene glycol, diethylene glycol, neopentyl glycol,
Examples thereof include polyalkylene glycol, 1,4-cyclohexanedimethanol, glycerin, pentaerythritol, trimethylol, and methoxypolyalkylene glycol. These diol components may be one kind or a mixture of two or more kinds.

[0010] Among the above-mentioned polyester resins forming the base sheet, polyethylene terephthalate obtained by condensation polymerization of terephthalic acid and ethylene glycol is particularly preferred, but a dicarboxylic acid component other than terephthalic acid and a dicarboxylic acid component other than ethylene glycol are preferable. May be a copolymerized polyester containing the diol component of (1). Copolyesters suitable for forming the base sheet include terephthalic acid in which at least 60 mol% of the dicarboxylic acid component is replaced by another dicarboxylic acid component, and at least 60 mol% of the diol component is ethylene. Copolymerized polyesters obtained by condensation polymerization with the remainder being replaced by another diol component with glycol. Among the copolyesters, a copolyester resin in which 90 mol% or more of the dicarboxylic acid component is terephthalic acid and 90 mol% or more of the diol component is ethylene glycol is preferable. The polyester resin forming the base sheet may be a mixture of polyethylene terephthalate and the above-mentioned copolymerized polyester.

The polyester resin forming the base sheet preferably has an intrinsic viscosity of 0.5 or more. If the intrinsic viscosity is less than 0.5, the strength of the base sheet is undesirably reduced. Among these, the intrinsic viscosity is preferably 0.6
That is all.

The above-mentioned base sheet made of a polyester resin must be a single-layer unstretched sheet in a substantially non-crystallized state. In the case of a stretched sheet, cracks occur when a folded ruled line is formed in a bent portion, and in the case of a multilayer sheet, the cost increases, and both are not preferred. An unstretched sheet made of a polyester resin can be manufactured by an extrusion molding method. Here, the non-stretched sheet means a sheet that is not actively stretched for the purpose of increasing the strength of the sheet, and a sheet that is stretched less than twice by a stretching roll during extrusion molding is included in the non-stretched sheet.

The base sheet made of a polyester resin is J
3% haze value measured according to IS K7105
The following are preferred. Among them, those having a haze value of 2% or less are particularly preferable. It is preferable that no lubricant or antistatic agent which impairs the transparency of the sheet is added to the polyester resin constituting the base sheet at all, or when added, the amount is minimal. The thickness of the polyester resin base sheet can be selected in the range of 60 to 500 μm. When manufacturing the base sheet, a pulverized product obtained by trimming the end portion of the multilayer polyester sheet or the like can be added as long as the transparency of the base sheet is not impaired.

The multilayer polyester sheet according to the present invention comprises:
A surface coating layer made of a polyester resin composition containing a small amount of inert particles is formed on both surfaces of the polyester resin base sheet. As the resin to which the inert particles are blended, various polyester resins including those of the same kind as the polyester resin constituting the base sheet can be used. As a sheet for bending,
It is particularly preferable to use an amorphous copolyester in consideration of solvent adhesion.

When a case is manufactured by bending a multi-layer polyester sheet, the bent end may be bonded using a solvent such as tetrahydrofuran, cyclohexanone, ethyl acetate, or methyl ethyl ketone. However, when the above-mentioned base sheet comes into contact with these solvents, it may crystallize and whiten. However, when a coating layer made of amorphous copolymerized polyester is formed on the surface of the base sheet, these solvents can be prevented from contacting the base sheet, and whitening of the base sheet can be prevented.

Here, the amorphous copolymerized polyester is
A copolymerized polyester or a mixture containing the copolymerized polyester is subjected to a differential scanning calorimeter (Perkin Elmer,
According to DSC-7), the heat of crystallization (ΔHc) when the temperature is lowered at a rate of 10 ° C./min from the molten state is 5 cal / g or less.

Amorphous copolyesters include those contained in the polyester resins mentioned above for producing the base sheet, but those containing mainly a relatively large amount of copolymer components. it can. Specifically, a dicarboxylic acid component mainly composed of terephthalic acid,
A copolymerized polyester resin containing 20 to 60 mol% of 1,4-cyclohexanedimethanol and the remainder being ethylene glycol, and a copolymerized polyester resin obtained by condensation polymerization of 20 to 60 mol% of an isophthalic acid component. Copolyesters obtained by condensation polymerization of a dicarboxylic acid component containing terephthalic acid and a diol component mainly composed of ethylene glycol, and the like can be used. These amorphous copolymerized polyesters may contain a small amount of a dicarboxylic acid such as phthalic acid, adipic acid or sebacic acid, or a diol component such as propylene glycol, triethylene glycol or diethylene glycol.

The amorphous copolymer polyester forming the surface coating layer of the base sheet preferably has an intrinsic viscosity of 0.5 or more as in the polyester resin forming the base sheet. . When the intrinsic viscosity is less than 0.5, the strength of the surface coating layer becomes low, and the inert particles cannot be held firmly, which is not preferable.
Among them, a preferable intrinsic viscosity is 0.6 or more.

The inert particles added to the resin forming the surface coating layer have a function of causing unevenness on the surface of the multilayer polyester sheet and exhibiting excellent slipperiness when a large number of multilayer polyester sheets are stacked. Fulfill. Examples of the inert particles include inorganic particles such as silica, silicate, titanium oxide, calcium carbonate, iron oxide, aluminum oxide, aluminum borate, calcium oxide, and magnesium oxide, or a mixture of two or more thereof. And various kinds of inert particles such as inorganic compounds such as talc and clay; and organic compounds such as a high melting point organic compound and a crosslinked polymer.

Further, in order to improve the transparency of the multilayer sheet, as inert particles to be added, a difference between the refractive index of the surface-layer polyester resin sheet and the refractive index of the surface layer polyester resin sheet is within ± 0.09. Preferably, active particles are selected and blended. When the difference between the refractive index of the polyester resin sheet forming the surface coating layer and the refractive index of the inert particles exceeds 0.09, the transparency of the sheet is reduced depending on the amount of the inert particles added. Absent. Examples of those having a refractive index satisfying the above requirements include silicates such as aluminosilicate, sodium calcium aluminosilicate and magnesium silicate, as well as aluminum borate.

Here, the refractive index of the inert particles means the refractive index of a mixture of the inert particles and the liquid when the inert particles are immersed in a liquid having a known refractive index. Since the refractive index depends on the ratio of the inert particles and the liquid, the refractive index of the liquid impregnated with the inert particles is measured with an Abbe refractometer,
A method of calculating the refractive index from the ratio between the inert particles and the liquid was used. The refractive index of the polyester-based resin sheet is determined by using sodium D line and nα, nβ, nγ
Is measured, and the average value (n) of these measured values is calculated by the following equation: n =
{(Nα + nβ + nγ) / 3}.

The inert particles have an average particle size of 3 to 12
μm, and the content of particles having a particle size of 15 μm or more needs to be 5% by weight or less. Average particle size is 3
If it is less than μm, unevenness formed on the sheet surface is small and the effect of improving slippage is not remarkable. If the average particle diameter exceeds 12 μm, the transparency and appearance of the multilayer sheet deteriorate, and both are not preferred. Further, the content of particles of 15 μm or more is 5
If the content is more than the weight percentage, the particles are visually observed, and the surface irregularities become too large, which deteriorates the appearance of the multilayer polyester sheet. Particularly preferred as inert particles are those having an average particle diameter of 5 to 10 μm and
The content of particles having a size of 5 μm or more is 2% by weight or less. Here, the average particle size of the inert particles means the particle size when the cumulative weight fraction becomes 60% as measured using a call counter (manufactured by Nippon Chemical Machinery Co., Ltd.).

The amount of the inert particles to be added to the resin forming the surface coating layer is selected from the range of 0.05 to 0.5 parts by weight based on 100 parts by weight of the resin for forming the surface coating layer. . If the amount is less than 0.05 part by weight, the effect of improving the slipperiness is not remarkable, and if it exceeds 0.5 part by weight, the transparency and appearance of the multilayer polyester sheet deteriorate, and both are not preferred. A particularly preferred amount of the inert particles is 0.1 to
The range is 0.3 parts by weight.

The thickness of the surface coating layer formed on both surfaces of the base sheet is selected on the one side in consideration of the balance between surface slipperiness and transparency, and is usually selected in the range of 5 to 50 μm. The thickness of the surface coating layer (total on both sides) is set to about 13 to 30% of the total thickness of the multilayer polyester sheet. When used as a sheet for folding, if the thickness of one side of the surface coating layer is set to 15 μm or more, the solvent contained in the adhesive used in the bonding process will penetrate the base sheet layer and whiten. It is preferable because it can be prevented.

The surface roughness of the multilayer polyester sheet is generally determined from the viewpoint of balance between slipperiness and other properties.
The 10-point average roughness (Rz) specified in IS B0601 is 0.2 to 2 μm, and the roughness (Rz) can be adjusted by the amount of inert particles added, the inert average particle diameter, and the like.

The polyester resin forming the surface coating layer includes, in addition to the above-mentioned inert particles, the slipperiness of the surface coating layer,
Antistatic agent, stabilizer,
Other thermoplastic resins and the like can be added in addition to lubricants, ultraviolet absorbers, various pigment additives, and the like. Furthermore, a lubricant such as an antistatic agent or silicone or wax can be applied to the surface of the surface coating layer as long as the slipperiness and transparency of the surface coating layer of the multilayer sheet are not impaired.

In order to produce the multilayer polyester sheet of the present invention, (1) a method in which each layer is formed in advance and then bonded by heat or an adhesive, and (2) a preformed surface coating layer is formed by extruding a base sheet. A method of heat bonding immediately after being extruded from a die of a molding machine, (3) a method of melt-extruding a base sheet and a surface coating layer with separate extruders, and sandwiching and melting and bonding with a nip roll, (4) a resin for a base sheet,
Melt the resin for forming the surface coating layer with separate extruders,
It is preferable to employ a method in which the material is melt-laminated in a die with a feed block or a multi-manifold die and extruded as a laminated sheet.

The multilayer polyester sheet according to the present invention comprises:
Excellent in transparency, appearance, and surface slipperiness. Cosmetics, clothing, dolls, foods, desktops, etc., by processing machines such as conventional PVC sheet cutting machines, folding crease forming machines, and punching machines. It can be easily processed into a transparent case suitable for storing slide calendars, video tapes, etc., or a transparent case such as a blister container for storing various small items. In addition, a transparent case with high commercial value can be obtained without whitening during bonding with a solvent.

[0029]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the examples described below unless departing from the gist thereof.

In the examples described below, the following resin (a) and resin (b) were used as the resin for forming the surface coating layer. Various physical properties are shown in Table 1. (a) Resin: a copolymerized polyester in which the dicarboxylic acid component is terephthalic acid and the diol component is a mixture of 67 mol% of ethylene glycol and 33 mol% of 1,4-cyclohexanedimethanol (intrinsic viscosity = 0.8, ΔHc = 0cal /
g, sacrificial rate = 1.567) (b) Resin: polyethylene terephthalate obtained by condensation polymerization of terephthalic acid and ethylene glycol (intrinsic viscosity = 0.
75, ΔHc = 42 cal / g, refractive index = 1.572)

[0031]

[Table 1]

In the examples described below, the characteristics of the multilayer polyester sheet were evaluated by the methods described below. (1) Coefficient of friction: Measured according to JIS K7215. The smaller the numerical value of both μs and μd, the more preferable. (2) Slipperiness: In a state where 200 multilayer sheets are stacked,
A method of checking whether it can be continuously supplied to a printing machine and a folding crease forming machine after cutting to a predetermined size by a commercially used cutting machine. When the multilayer sheet could be continuously supplied, ○ was given, and when a trouble occurred during continuous supply, × was given. (3) Haze (%): Measured according to JIS K7105. The smaller the numerical value (%), the smaller the haze and the better the transparency.

(4) Surface appearance: The following items were evaluated by visual observation. The “roughness” was evaluated by evaluating the degree of surface roughness of the surface of the multilayer sheet. ◎: surface roughness was not observed at all, ○: surface roughness was not observed, ○: surface roughness was observed. Indicated as x. "Flicker"
When the added inert particles were not seen at all by visual observation, it was indicated as 、, when the inert particles were not seen as ○, when the inert particles were clearly seen as ×, and between intermediate ○ and ×, as Δ. The surface roughness of the multilayer sheet and visual observation of the added inert particles by visual observation are harmful to use and are not preferred.

(5) Solvent adhesiveness: A multi-layer polyester resin sheet is formed with a folding ruled line by a folding ruled line forming machine.
A method in which methyl ethyl ketone is applied to the bent narrow portion and adhered to the end of the opposing wide portion and visually observed for the presence or absence of whitening of the bonded portion. And those with whitening were indicated as x. (6) Refractive index: a value measured and calculated by the above-described method for both the polyester resin sheet and the inert particles.

[Examples 1 to 8, Comparative Examples 1 to 6] Polyethylene terephthalate having an intrinsic viscosity of 0.75 was used as a raw material for forming a base sheet (center layer), and the above resin (a) or (b) was used. A resin composition for forming a surface coating layer obtained by adding inert particles shown in Table 1 to a polyester resin of a resin is used as a raw material, and each is melted by an extruder and melt-laminated in a multi-manifold of a co-extrusion T-die. And extruded as a three-layer sheet from a T-die at 285 ° C., and cast on a cooling drum at 40 ° C.
A three-layer sheet having a thickness of 25 μm and a thickness of both surface coating layers of 25 μm was produced. The obtained three-layer sheet was evaluated for the coefficient of friction, the slipperiness, the haze, the transparency, the surface appearance, the solvent adhesion, and the like by the methods described above. The evaluation results are collectively shown in Table-2.

[0036]

[Table 2]

From Table 2, the following becomes clear. (1) Although the multilayer sheets of Examples 1 to 8 had 0.05 to 0.5 parts by weight of AE inert particles added to the surface coating layer, the transparency of the multilayer sheets was -There is little deterioration in appearance and slipperiness is improved. (2) Furthermore, in the multilayer sheets of Examples 3 to 5, the difference between the refractive index of the inert particles mixed in the surface coating resin layer and the refractive index of the surface coating polyester resin sheet was ± 0.
Since the inert particles C to E in the composition No. 09 are blended, the haze value of the multilayer sheet is small, and the multilayer sheet according to Example 1 is transparent.
-Superior to Example 2.

(3) In Examples 1 to 7, since the amorphous polyester resin (a) was used as the surface coating resin, (b) was used as the surface layer resin in terms of solvent adhesion. ) Is superior to that of Example 8 using Therefore, the conventional bonding line used for the PVC sheet can be used, and no new equipment is required. On the other hand, in Example 7, a case excellent in transparency and the like can be obtained by using another bonding method instead of the solvent bonding, for example, using a hot melt adhesive. (4) On the other hand, in the multilayer sheet of Comparative Example 2, the amount of inert particles E was small, and the slip property of the multilayer sheet was insufficient. Although the addition amount is large, there is an effect of improving the slipperiness, but the addition amount is too large and the transparency of the sheet is inferior.

(5) The multilayer sheets of Comparative Examples 4 and 5 are:
Although the sliding property and the transparency are good, the surface appearance of the multilayer sheet is inferior because the added inert particles contain many coarse particles exceeding 15 μm. (6) The multilayer sheet of Comparative Example 1 is inferior in slipperiness because no inert particles are blended in the surface coating resin, and the multilayer sheet of Comparative Example 6 is blended with inert particles in the surface coating resin. However, since the average particle diameter is small, the sliding property is poor.

Example 9 In the example described in Example 5, in addition to the inert particles E, 0.15 parts by weight of a montanic acid ester (lubricant) and glycerin monostearate (an antistatic agent) ) 0.3 parts by weight were blended, and a three-layer sheet having the same thickness as the sheet of the same example was prepared in the same procedure as in the same example. Various evaluation tests were performed on the obtained multilayer sheet in the same procedure as in the same example. Table 3 shows the results.

[Examples 10 to 11] In the example described in Example 5, the thickness of the surface coating resin was changed to 15 μm (Example 10) and 40 μm (Example 11). The total thickness of the multilayer sheet is 2
A three-layer sheet of 50 μm was prepared. Various evaluation tests were performed on the obtained three-layer sheet in the same procedure as in the same example. Table 3 shows the results.

[0042]

[Table 3]

From Table 3, the following becomes clear.
(1) Since the multi-layer sheet of Example 9 contains an organic lubricant and an antistatic agent in addition to the inert particles E in the surface coating resin, the slip property is improved as compared with Example 5, and the friction is improved. The coefficient has decreased. (2) The multilayer sheets of Examples 10 and 11 are excellent in slipperiness, transparency, appearance, and the like.

[0044]

The present invention has been described in detail above, and has the following particularly advantageous effects, and its industrial value is extremely large. 1. The multilayer polyester sheet according to the present invention is obtained by blending a small amount of inactive particles having an average particle diameter of 3 to 12 μm and a particle diameter of 15 μm or more and 5% by weight or less with the surface coating resin. Therefore, it has excellent transparency, appearance, and surface slipperiness. 2. When the surface coating layer of the multilayer polyester sheet according to the present invention is mainly composed of amorphous copolymerized polyester, the base sheet is not whitened by the solvent-type adhesive, and a transparent case with excellent appearance is obtained. . 3. Since the multilayer polyester sheet according to the present invention has excellent surface slipperiness, it can be processed by a conventional processing machine such as a cutting machine for PVC sheets, a folding crease forming machine, and a punching machine.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F100 AA20H AA33H AK41A AK41B AK41C AK41K AL01B AL01C BA03 BA06 BA10B BA10C BA16 CA23 CA23B CA23C DE01B DE01C DE01H EH20 GB16 GB48 GB71 GB84 GB90 JA12JJNJJNJJNJJNJJNJJN YY00H 4F208 AA24 AB15 AB17 AD08 AD20 AE10 AF16 AG07 AH42 AH56 MA01 MB01 MG04 MG22 4F209 AA24 AB15 AB17 AD08 AD20 AE10 AF16 AG07 AH42 AH56 NA02 NA13 NG02 NG05 NL10

Claims (3)

[Claims] 1. The method according to claim 1, wherein both surfaces of the transparent polyester resin base sheet have an average particle diameter of 3 to 12 μm and a particle diameter of 15 μm with respect to 100 parts by weight of the polyester resin.
m, wherein a surface coating layer made of a polyester resin composition containing 0.05 to 0.5 parts by weight of inert particles having a content of particles of 5% by weight or less is formed. A multi-layer polyester sheet. 2. The multilayer polyester sheet according to claim 1, wherein the polyester resin forming the surface coating layer is mainly composed of an amorphous copolymerized polyester. 3. The difference between the refractive index of the inert particles and the refractive index of the polyester resin sheet forming the surface coating layer is ± 0.
The multilayer polyester sheet according to claim 1, wherein the thickness of the multilayer polyester sheet falls within the range of 09.