WO2002032984A1

WO2002032984A1 - Antifogging polyolefin sheet, process for producing antifogging polyolefin sheet, molded object obtained from the sheet, sheet for food packaging, and molded object for food packaging

Info

Publication number: WO2002032984A1
Application number: PCT/JP2001/009028
Authority: WO
Inventors: Masahiro Kubo; Akira Funaki
Original assignee: Idemitsu Petrochemical Co., Ltd.
Priority date: 2000-10-16
Filing date: 2001-10-15
Publication date: 2002-04-25
Also published as: JP2010180407A; JP5227986B2; JPWO2002032984A1

Abstract

An antifogging polyolefin sheet having a coating layer which contains an antifogging agent and has a high film strength. It can have a high antifogging effect even when the amount of the antifogging agent is small. The sheet (1) comprises a polyolefin resin sheet (11) and formed on at least one side thereof a coating layer (12) comprising an antifogging agent and a binder resin comprising an acrylic adhesive.

Description

Description Anti-fog polyolefin-based sheet, method for producing anti-fog polyolefin-based sheet, molded article using the sheet, food packaging sheet, molded product for food packaging

The present invention relates to an antifogging polyolefin-based sheet, a method for producing the antifogging polyolefin-based sheet, and a molded article, a food packaging sheet, and a food packaging molded article using the sheet. Background art

In recent years, transparent polypropylene has been actively developed as an alternative resin in the field where OPS resin (stretched polystyrene resin) is used.

Compared to OPS resins, polypropylene without polar groups provides anti-fogging properties, an essential property in this field.Coatings with only anti-fog agents have low film strength and maintain their effects even after thermoforming. To do so, it is necessary to apply a large amount of antifogging agent.

However, when a large amount of antifogging agent is used, there is a problem that only a sheet having extremely poor handling properties can be obtained because the sheet surface is sticky.

In order to solve such problems, sheets containing an antifogging agent have been developed, but the bleed-out amount of the antifogging agent is affected by the storage environment of the sheet, and the antifogging effect is not sufficient There is a problem that it tends to be stable.

An object of the present invention is to provide an antifogging polyolefin-based sheet which can exhibit a high antifogging effect without using a large amount of an antifogging agent, in which the layer containing the antifogging agent has high coating strength. An object of the present invention is to provide a method for producing a olefin-based sheet, and a molded article, a sheet for food packaging, and a molded article for food packaging using the sheet. Disclosure of the invention

The anti-fog polyolefin sheet according to the present invention is a polyolefin resin sheet. Is characterized by having a coating layer containing a binder resin composed of an antifogging agent and an acrylic adhesive on at least one surface of the substrate.

Here, as the polyolefin-based resin constituting the polyolefin-based resin sheet, homopolymers and copolymers of various olefins, and mixtures thereof can be used.

As the monomer constituting the homopolymer, ethylene, propylene, 1-butene, isoprene, butadiene and the like can be used. In addition, as the copolymer, an ethylene-polyolefin copolymer, a propylene-polyolefin copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylate copolymer, or the like can be used. . Among them, it is preferable to use polypropylene in consideration of transparency, strength and the like.

The polyolefin resin sheet of the present invention may have either a single-layer structure or a multilayer structure. When the polyolefin-based resin sheet has a multilayer structure, it is ideal to employ polypropylene for at least the surface layer.

The antifogging agent is not particularly limited, but may be sucrose fatty acid ester, glycerin fatty acid ester, fatty acid tertiary amide, higher alcohol fatty acid ester, propylene glycol fatty acid ester, etc., alone or in combination of two or more. Can be used in combination.

On the other hand, the acrylic adhesive is not particularly limited, but a copolymer such as polyacrylic ester can be used.

Here, as the acrylate constituting the polyacrylate, methyl acrylate, ethyl butyl, butyl acrylate, octy / restenol, 2-ethylhexyl, and the like can be used.

A polymer obtained by copolymerizing these ester acrylates with ester methacrylate, styrene, acrylonitrile, vinyl chloride, vinyl acetate and the like can be used. Further, a polymer obtained by copolymerizing the above acrylate with various functional monomers such as acrylic acid, acrylamide, methylol acrylamide, and hydroxydialkyl methacrylate can also be used.

According to the present invention, an antifogging agent and / or Since it has a coating layer containing a pinda resin, the coating film strength can be increased and the stickiness of the coating layer surface can be suppressed as compared with a coating layer containing only an antifogging agent. . Moreover, since an acrylic adhesive is used as the binder resin, stickiness on the surface of the coat layer can be further reduced, and a molded article obtained by thermoforming the anti-fog polyolefin-based sheet can be obtained. However, the anti-fogging property can be exhibited effectively.

In the above, the coating layer, it is preferable that the polyolefin-based resin sheet to the anti-fogging agent, respectively 4~40 Om gZm ² applied to your Yopi binder resin as a solid content, is a layer formed by drying.

Here, if the weight per unit area of the binder resin on the sheet surface is less than 4 mg / m ² , the strength of the coat layer may be reduced. On the other hand, if it exceeds 4 O Omg / m ² , the antifogging effect may be reduced.

The weight per unit area of the anti-fogging agent of the sheet surface is less than 4m gZm ^2, there is a possibility that no sufficient anti-fogging effect. On the other hand, if it exceeds 40 Omg / m ² , the strength of the coat layer may decrease and stickiness may occur.

Further, polyolefin-based resin sheet has an average spherulite radius is 4 / zm or less, the average spherulite number of sheet cross-section is 600 ZMM ² or less, the solid density is 0. 890 g / cm ³ or less, differential scanning calorimetry ( (DSC) Polypropylene layer with a melting enthalpy of the maximum endothermic peak ΔΗ of less than 95 J / g and a heating layer of 1 j / g or more on the low temperature side of the maximum endothermic peak and a thickness of 50 μπι or more It is preferred that

Here, if the average spherulite radius is larger than 4 μπι, the internal haze may increase (transparency may decrease). More preferably, the average spherulite radius is 3 / im or less. Further, when the average number of spherulites in the cross section of the sheet is more than 600 / mm ² , the softening point temperature of the sheet may increase. More preferably, the average number of spherulites is 400 or less and Zmm ² or less.

Further, when the solid density is greater than 0.890 g / cm ³ , the density is too high, that is, the crystallinity is too high, which may affect the softening point temperature. If the thickness of the sheet is less than 5 μμπι, a molded article having rigidity after thermoforming (volume May be difficult to build.

The anti-fog polyolefin-based sheet having a polypropylene layer having such properties has a low heating softening point temperature, can be subjected to low-temperature thermoforming, and has good internal haze (transparency).

In addition, since the heating softening temperature is low, it is not necessary to use a special molding device, so that manufacturing costs can be reduced. Moreover, by thermoforming such a sheet, it is possible to obtain a thermoformed article having anti-fogging properties and high transparency. Furthermore, the melting enthalpy ΔΗ is relatively small, less than 95 jZg, and heat generation of 1 J / g or more is observed at the low temperature side.Therefore, the amount of heat that must be supplied from the outside to soften the sheet is small, and Since the heating temperature during softening is relatively low, low-temperature thermoforming becomes easier.

As the polyolefin-based resin sheet, the thickness of this layer in case that the t mm, the internal haze ^{is, (330 t 2 - 1 50} t + 20)% or less it is not preferable.

^{Here, (330 t 2 - 1 50} t + 20) measures the relationship between the internal haze and the sheet thickness, an equation obtained by the least squares method.

If the internal haze value is larger than the value obtained from the above relational expression, the transparency of the thermoformed article obtained by thermoforming the antifogging polyolefin-based sheet may deteriorate. That is, by setting the internal haze of the sheet to the above range, the internal haze of the thermoformed body is (330 s ² — 150 S + 25)% or less (s: the thickness of the thermoformed body (mm) ), And a thermoformed article having excellent transparency can be obtained.

Further, the tensile modulus of the polyolefin-based resin sheet is preferably 1500 MPa or less.

Here, if the tensile modulus of the polyolefin-based resin sheet is 150 OMPa or more, the degree of crystallinity is high, so that the softening point temperature becomes high, and molding may be difficult.

Further, by setting the tensile modulus of the polyolefin resin sheet within the above range, crystallization is promoted by heating during thermoforming, and the tensile elastic modulus of the thermoformed body is maintained at 170 OMPa while maintaining transparency. The molded body having sufficient strength Can be obtained.

In addition, the tensile modulus in the present invention refers to a value measured in the moving direction (MD direction) at the time of sheet production by a method based on JIS K7113.

The polyolefin-based resin sheet of the present invention preferably has a surface subjected to a corona treatment.

The anti-fogging polyolefin-based sheet described above has a high anti-fogging effect and is excellent in transparency, so that it can be suitably used as an OPS alternative field, for example, as a food packaging sheet.

Further, a molded article obtained by thermoforming the anti-fogging polyolefin-based sheet of the present invention is also excellent in anti-fogging property and transparency, so that it is suitably used for a molded article for food packaging, for example, a food tray. be able to.

The method for producing an anti-fog polyolefin-based sheet according to the present invention comprises the steps of: introducing a molten polyolefin-based resin between an endless belt wound around a plurality of cooling ports and a mirror-surface cooling roll; A sheet forming step in which the molten polyolefin resin is pressed into contact with a belt and a mirror cooling roll to form a sheet, and quenched to form a polyolefin resin sheet; and a polyolefin resin obtained by the sheet forming step. Coating a mixed aqueous solution of an anti-fogging agent and a binder resin on at least one surface of the resin sheet, and then drying to form a coat layer.

Here, the temperature at which the sheet is rapidly cooled is not particularly limited. More preferred.

The endless belt is not particularly limited, and a mirror stainless steel belt, a belt coated with a polyimide resin, a fluorine resin, or the like on the surface of a metal belt, or the like can be used.

The polyolefin resin sheet, antifogging agent, and binder resin are the same as described above.

According to the present invention, there is provided a sheet forming step in which the molten polyolefin resin is brought into pressure contact with the endless belt and the mirror surface cooling port and quenched. did Thus, a polyolefin resin sheet having high transparency and low crystallinity can be obtained, and as a result, the transparency and thermoformability of the anti-fog polyolefin resin sheet can be improved.

In addition, since a coating layer forming step of coating a mixed aqueous solution of an antifogging agent and a binder resin is provided, the coating strength of the coating layer can be increased and the stickiness of the surface can be suppressed. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a partial cross-sectional view showing an antifogging polyolefin-based sheet according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing an apparatus for producing a polyolefin-based resin sheet in the embodiment of FIG. '' Best mode for carrying out the invention

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[1] Anti-fog 1 "raw polyolefin sheet

FIG. 1 shows an antifogging polyolefin-based sheet 1 according to a first embodiment of the present invention.

The anti-fog polyolefin-based sheet 1 comprises a polypropylene layer 11 as a polyolefin-based luster sheet, and a coat layer 12 formed by coating a mixed aqueous solution containing an anti-fog agent and an acrylic adhesive. It is provided with.

Here, the polypropylene layer 11 constituting the anti-fog polyolefin-based sheet 1 has an average spherulite radius of 4 μπι or less, an average number of spherulites in the sheet cross section of 600 / mm ² or less, and a solid density of 0.8. 90 g / cm ³ or less, Tensile modulus 150 OMPa or less, Melting enthalpy ΔΗ at the maximum endothermic peak of the DSC curve is less than 95 j / g, and 1 J / g or more at the low temperature side of the maximum endothermic peak The exothermic peak has a thickness of 50 μπι or more.

When the thickness of the polypropylene layer 11 is tmm, the internal haze is (330 t2-150 t + 20)% or less. [2] Apparatus and method for producing polyolefin resin sheet (polyolefin sheet) constituting antifogging polyolefin sheet

First, with reference to FIG. 2, a production apparatus used for producing a polypropylene sheet (polypropylene layer) 11 constituting the anti-fog polyolefin sheet 1 of the present invention will be described.

The manufacturing equipment consists of an extruder T die 22, a first cooling roll 23, a second cooling roll 26, a third cooling roll 24 and a fourth cooling roll 25, and a metal endless belt 27. , A cooling water spray nozzle 28, a water tank 29, a water absorbing roll 30, and a peeling roll 31.

The fourth cooling port rule 25, the second cooling port rule 26, and the third cooling port rule 24 are metal rolls. Cooling means (not shown) is built-in.

Here, the surface of the first cooling roll 23 is coated with an elastic material 32 made of nitrile-butadiene rubber (NBR). The elastic material 32 has a hardness (measured by a method based on JIS K 6301A) of 60 degrees or less and a thickness of 10 mm.

In addition, at least one of the first, fourth, and third cooling rolls 23, 25, and 24 has its rotating shaft connected to a rotation drive unit (not shown). '' The second cooling roll 26 is a metal roll (mirror cooling roll) having a mirror surface of Rmax = 1.0 m, and a cooling means such as a water-cooling type to enable surface temperature control (Not shown) is built-in. Here, if Rmax = l.0 / m (Rmax is based on JIS B0601 “Definition and Display of Surface Roughness”), the resulting polypropylene sheet (polypropylene layer) 11 has low gloss. And a polypropylene sheet 11 with low transparency.

The second cooling roll 26 is disposed so as to sandwich the polypropylene sheet 11 between the first cooling roll 23 and the metal endless belt 27.

The endless belt 27 is made of stainless steel or the like, and has a mirror surface of Rmax = 1.0 μm or less. The endless belt 27 is rotatably wound around the first, third, and fourth cooling rolls 23 to 25 described above.

The cooling water spray nozzle 28 is provided on the lower surface side of the second cooling port ruler 26, As a result, the cooling water is sprayed on the back surface of the endless belt 27. By spraying the cooling water in this manner, the endless belt 27 is rapidly cooled, and the polypropylene 11 immediately after being pressed by the first and second cooling rolls 23 and 26 is also rapidly cooled. I have.

Further, the water tank 29 is formed in a box shape having an open upper surface, and is provided so as to cover the entire lower surface of the second cooling roll 26. The water tank 29 collects the sprayed cooling water and discharges the collected water from an outlet 29 A formed on the lower surface of the water tank 29.

The water-absorbing roll 30 is installed on the side surface of the second cooling roll 26 on the side of the third cooling roll 24 so as to be in contact with the endless belt 27, and excess cooling adhered to the back surface of the endless belt 27. It acts to remove water.

The peeling roll 31 is arranged so as to guide the polypropylene sheet 11 to the endless belt 27 and the third cooling roll 24, and the endless belt for the polypropylene sheet 11 after cooling is completed. Separated from 27. · In this embodiment, the peeling roll 31 does not press the polypropylene sheet 11 against the third cooling roll 24, but may press it. However, it is preferable not to make pressure contact as in the present embodiment.

A method of manufacturing the polypropylene sheet 11 using the manufacturing apparatus configured as described above will be described (sheet forming step).

First, the endless belt 27 and the second cooling roll 26 which come into direct contact with the polypropylene sheet 11 and cool it are kept in advance at each cooling port so that the surface temperature is maintained at the dew point or higher and 30 ° C or lower. Control the temperature of rules 24, 25 and 26.

Here, if the surface temperature of the second cooling roll 26 and the endless belt 27 is lower than the dew point, dew condensation may occur on the surface, making it difficult to form a uniform film. On the other hand, if the surface temperature is higher than 30 ° C., the transparency of the obtained polypropylene sheet 11 will decrease, and the number of crystals will increase, which may make it difficult to heat-mold. Therefore, in the present embodiment, the surface temperature is set to 14 ° C.

Next, the polypropylene sheet 11 extruded from the T die 22 of the extruder is sandwiched between the endless belt 27 and the second cooling roll 26 on the first cooling roll 23. Put in. In this state, the polypropylene sheet 11 is pressed against the first and second cooling rolls 23 and 26 and rapidly cooled at 14 ° C.

At this time, the elastic material 32 is compressed and elastically deformed by the pressing force between the first cooling roll 23 and the second cooling roll 26. The portion where the elastic member 32 is elastically deformed, that is, the arc portion corresponding to the central angle 01 of the first cooling roll 23, the polypropylene sheet 11 is surfaced by the cooling rolls 23, 26. It has been pressed. The surface pressure at this time is 0. 220 MPa.

The polypropylene sheet 11 pressed as described above and sandwiched between the second cooling roll 26 and the endless velvet 27 subsequently has an arc portion corresponding to a substantially lower half circumference of the second cooling roll 26, While being pressed between the endless belt 27 and the second cooling roll 26 in planar contact, the cooling water spray nozzle 28 sprays cooling water on the back side of the endless belt 27 to further cool rapidly. You. The surface pressure at this time is 0.1 to 0.5 MPa, and the temperature of the cooling water is 8 ° C.

The sprayed cooling water is collected in the water tank 29, and the collected water is discharged from the drain 29A.

After being pressed and cooled by the second cooling roll 26 in this manner, the polypropylene sheet 11 in close contact with the endless belt 27 is moved onto the third cooling roll 24 with the rotation of the endless belt 27. Moved to Here, the polypropylene sheet 11 guided by the peeling roll 31 is again cooled at a temperature of 30 ° C. or less in an arc portion corresponding to a substantially upper half circumference of the third cooling roll 24. .

The water adhering to the back surface of the endless belt 27 is removed by the water absorbing roll 30 provided on the way from the second cooling roll 26 to the third cooling roll 24.

The polypropylene sheet 11 cooled on the third cooling roll 24 is peeled off from the endless belt 17 by the peeling roll 31 and wound up at a predetermined speed by a winding roll (not shown).

[3] Method for producing anti-fog polyolefin-based sheet (coat layer forming step)

Next, a method of forming the coat layers 12 on both surfaces of the polypropylene layer (polypropylene sheet) 11 obtained by the method described in the above [2] will be described. First, a corona treatment is applied to both sides of the polypropylene layer 11. Polypropylene layer 1 1 of the surface was subjected to corona treatment of an aqueous solution of a mixture of Akuriru system adhesives as anti-fogging agent Contact Yopi binder resin, respectively. 4 to 4 0 0 mg Roh m ² as solid content by gravure coater Then, the coated layer is dried to form a coat layer 12, and an anti-fogging polyolefin sheet 1 is obtained.

The anti-fogging polyolefin-based sheet 1 thus obtained has a high anti-fogging effect and is excellent in transparency, so that it can be suitably used as an OPS substitute field, for example, as a food packaging sheet. .

Further, a molded article obtained by thermoforming an antifogging polyolefin-based sheet is also excellent in antifogging property and transparency, so that it can be suitably used for a molded article for food packaging, for example, a food tray. .

These points are the same in the following second embodiment.

According to the above-described embodiment, the following effects can be obtained.

(1) Since the surface of the polypropylene layer 11 has a coating layer 12 containing an anti-fogging agent and a pinda resin, the coating film strength can be increased as compared with a coating layer containing only an anti-fogging agent. As well as reducing stickiness on the surface.

(2) Since an acryl-based adhesive is used as the binder resin, the tackiness of the surface of the coating layer 12 can be further reduced, and the anti-fog polyolefin-based sheet 1 is thermoformed. The anti-fogging property can be effectively exhibited also in the molded article obtained by the above method.

(3) Anti-fog having a polypropylene layer 11 having a characteristic that the average spherulite radius is 4 μπι or less, the average number of spherulites is 600 Zmm ² or less, and the solid density is 0.895 g Zcm ³ or less. Polyolefin-based sheet 1. Therefore, it is possible to obtain the sheet 1 having a low heating softening point temperature, capable of performing low-temperature thermoforming, and having good internal haze (transparency). In addition, since the heating softening temperature is low, it is not necessary to use a special molding device, so that manufacturing costs can be reduced. Moreover, by thermoforming such a sheet 1, a thermoformed product having anti-fogging properties and high transparency can be obtained.

(4) Since the melting enthalpy ΔH is relatively small, less than 95 JZ g, and heat generation of 1 JZ g or more is observed on the low temperature side, it must be supplied from outside to soften the sheet 1. Since the amount of heat required is small and the heating temperature during softening is relatively low, low-temperature thermoforming becomes easier.

(5) Since the tensile modulus of the polypropylene layer 11 is 150 OMPa or less, the crystallinity and softening point temperature are low, and thermoforming can be easily performed. Further, the crystallization is promoted by heating during thermoforming, and the tensile elastic modulus of the thermoformed body of the anti-fog polyolefin-based sheet 1 can be set to 170 OMPa or more while maintaining the transparency. Strength can be obtained.

(6) the thickness of the polypropylene layer 1 1 in case of a t mm, the internal haze ^{is, (3 3 0 t 2 -} 1 5 0 t + 2 0)% because it will antifogging polyolefin based sheet 1 Of the thermoformed article obtained by thermoforming the polymer. That is, by setting the internal haze of the polypropylene layer 11 within the above range, the internal haze of the thermoformed body is not more than (330 s ² — 150 S + 25)% (s: thickness of the thermoformed body). (Mm)).

(7) The endless belt 27 and the second cooling roll 26, which is a mirror-surface cooling roll, press the molten polypropylene sheet 11 in contact with the sheet, and have a sheet forming process for rapid cooling. Thus, a low-crystalline polypropylene sheet (polypropylene layer) 11 can be obtained, and as a result, the transparency and thermoformability of the anti-fog polyolefin-based sheet 1 can be improved.

(8) Since a coating layer forming step of coating a mixed aqueous solution of an anti-fogging agent and a binder resin is provided, the coating strength of the coating layer 12 can be increased and the stickiness of the surface can be suppressed. .

(9) Since the polypropylene sheet 11 is cooled while being pressed against the surface of the polypropylene sheet 11 with the elastic deformation of the elastic material 32, the mirror transfer efficiency and cooling efficiency are increased, and the transparent polyester sheet is highly transparent. 1 1 can be manufactured at high speed.

(10) Since the Rmax of the second cooling roll 26 and the endless belt 27 are not more than 1.0 ^ m, it is necessary to obtain a highly transparent polypropylene sheet 11 with a high surface gloss. Can be.

(11) Since the surface temperature of the second cooling roll 26 and the endless belt 27 is maintained at the dew point or higher and 30 ° C or lower, a polypropylene sheet 11 uniformly formed is obtained. be able to.

(12) Since the cooling water is sprayed by the cooling water spray nozzle 28 for further cooling, the quenching effect of the polypropylene sheet 11 can be further improved, and the crystallization of the polypropylene sheet 11 can be suppressed. It should be noted that the present invention is not limited to the above embodiment, and modifications and improvements as long as the object of the present invention can be achieved are included in the present invention. For example, in the above-described embodiment, the polypropylene layer 11 is employed as the polyolefin-based resin sheet. However, the present invention is not limited to this, and a layer made of various polyolefin-based resins, for example, a polyethylene layer or the like may be used.

In the above-described embodiment, the endless belt 27 is a force wound around three rolls. The present invention is not limited to this. In short, if the device can rotate and cool the endless belt, the number of cooling rolls around which the endless belt is wound can be set arbitrarily.

In the above embodiment, the mirrorless stainless steel belt is used as the endless belt 27, but the present invention is not limited to this. That is, there is no particular limitation as long as the endless belt is Rmax = 1.O / zm or less.For example, a belt in which a surface of a metal endless belt is coated with a polyimide resin, a fluororesin such as polytetrafluoroethylene, or the like. May be adopted.

Further, as the elastic member 32, an elastic member made of NBR has been adopted, but it is not limited to this. In short, any material may be used as long as it has a predetermined hardness and thickness and is elastically deformed when the polypropylene sheet is pressed. For example, an elastic material made of silicone or the like can be used.

In the above embodiment, the surface temperature of the second cooling port ruler 26 and the endless belt 27 was set to 14 ° C., but is not limited thereto, and is not less than the dew point and not more than 50 ° C., preferably the dew point. As described above, any temperature of 30 ° C. or less can be adopted.

In addition, the temperature of the water sprayed by the cooling water spray nozzle 28 was set to 8 ° C, but is not limited to this, and may be arbitrarily set to a value lower than the surface temperature of the second cooling roll 26 and the endless belt 27. Can be set. In addition, specific structures, shapes, and the like when carrying out the present invention are described below with reference to examples and comparative examples, as well as other structures within a range that can achieve the object of the present invention. Will be described.

[Example 1]

[1] Manufacture of polyolefin resin sheet (sheet forming process)

In the above embodiment, the specific conditions of the production apparatus and the production method were set as follows, and the polypropylene layer 11 was obtained.

Extruder diameter: 9 Omm

T die 22 width: 800 mm

Polypropylene: Idemitsu Polypropylene E—304GP (made by Idemitsu Petrochemical Co., Ltd.) Sheet 11 Pick-up speed: 1 OmZmin

Surface temperature of second cooling roll 26 and endless belt 27: 14 ° C Cooling water temperature: 8 ° C

Cooling water spray amount: 200 liters Zm i n

[2] Formation of coat layer (coat layer formation step)

Corona treatment is applied to both sides of the polypropylene layer 11 obtained in the above sheet forming process, and the treated antifogging agent is dried on both sides by 7 Omg per unit area, and the acrylic adhesive is dried. This was applied so as to be 50 mg in weight per unit area, and dried to form a coat layer 12, and an antifogging polyolefin sheet 1 was obtained.

Riquemar A (manufactured by Riken Vitamin Co., Ltd.) was used as the antifogging agent, and Julimer FC-80 (manufactured by Nippon Pure Chemical Co., Ltd.) was used as the acryloline adhesive. The thickness of the coating before drying was measured with an infrared moisture meter (manufactured by Kurashiki Spinning Co., Ltd.).

[Example 2]

An antifogging polyolefin sheet was prepared in the same manner as in Example 1, except that the weight of the antifogging agent was 300 mg per unit area after drying and the weight of the ataryl adhesive was 250 mg per unit area after drying. Got one.

[Example 3]

10 mg by weight per unit area after drying of antifogging agent, after drying of ataryl adhesive The antifogging polyolefin-based sheet 1 was obtained in the same manner as in Example 1, except that the weight per unit area was 10 mg.

[Example 4]

An antifogging polyolefin sheet 1 was obtained in the same manner as in Example 1 except that a transparent nucleating agent (dibenzylidene sorbitol derivative) was used as a sheet manufacturing method and a general tattyrol molding was employed.

[Example 5]

An antifogging polyolefin was prepared in the same manner as in Example 1, except that the weight of the antifogging agent was 500 mg per unit area after drying and the weight of the ataryl adhesive was 4 OOmg per unit area after drying. System sheet 1 was obtained.

[Example 6]

An antifogging poly was prepared in the same manner as in Example 1 except that the antifogging agent was 2 mg in weight per unit area after drying and the acrylic adhesive was 1 mg in weight per unit area after drying. An olefinic sheet 1 was obtained.

[Comparative Example 1]

An antifogging polyolefin sheet was obtained in the same manner as in Example 1 except that no acrylic adhesive was used.

The anti-fogging polyolefin-based sheets obtained in the above Examples and Comparative Examples were evaluated for the appearance of the sheet after winding and the anti-fogging property (high temperature Z low temperature) of the wound sheet. It was shown to.

Further, the anti-fogging polyolefin-based sheet obtained in each of the above Examples and Comparative Examples was molded into a container having a diameter of 100 mm and a depth of 1 Omm using a general vacuum pressure air molding machine. The same evaluation was performed for, and also shown in Table 1. table 1

Here, the appearance of the sheet after winding and the appearance of the molded body were visually evaluated. The antifogging property was evaluated by the following method.

[1] High temperature anti-fog properties

Pour a certain amount of hot water at 90 ° C into a container of fixed volume and seal with a molding lid. Leave at room temperature The subsequent change over time was visually evaluated (evaluation 5: good, evaluation 1: bad).

[2] Low temperature anti-fog properties

— Pour a certain amount of water at 23 ° C into a container of constant volume and seal with a molding lid. Changes over time after standing in a refrigerator at 5 ° C were visually evaluated (evaluation 5: good, evaluation 1: bad). As shown in Table 1, the anti-fogging polyolefin-based sheets obtained in Examples 1 to 3 have extremely good sheet appearance, anti-fogging property, appearance of molded article, and anti-fogging property. You can see that.

In Example 5, since the antifogging agent and the acrylic binder were applied excessively, transfer unevenness occurred in some parts, and peeling of the coating film occurred in some parts due to elongation during thermoforming. It is not enough to be a problem.

In Example 6, it can be seen that the antifogging effect of the sheet and the antifogging effect of the molded article were slightly reduced because the antifogging agent and the acrylyl binder were small.

On the other hand, in Comparative Example 1, which did not contain the acrylic adhesive, it was found that stickiness of the surface and transfer to the opposite surface of the sheet occurred, resulting in uneven transfer.

In Example 4, the transparency of the sheet was high, but the thermoformability at low temperatures was slightly insufficient, and the transparency of the molded product was low. However, it is superior to Comparative Example 1. Industrial applicability

The present invention relates to an antifogging polyolefin-based sheet, a method for producing the antifogging polyolefin-based sheet, and a molded article, a food packaging sheet, and a food packaging molded article using the sheet, and is used for packaging food and the like. it can.

Claims

The scope of the claims

1. An anti-fogging polyolefin sheet comprising at least one surface of a polyolefin resin sheet having a coating layer containing a binder resin comprising an anti-fogging agent and an atalylic adhesive.

2. The anti-fog polyolefin sheet according to claim 1,

The coating layer, antifogging polyolefin system, characterized in that said anti-fogging agent and Vine da resin to the polyolefin-based resin sheet is a layer formed by 4~ 40 Omg / m ² respectively coated solid basis Sheet.

3. The anti-fog polyolefin-based sheet according to claim 1, wherein at least a surface layer of the polyolefin-based resin sheet is a polypropylene layer.

4. The antifogging polyolefin sheet according to any one of claims 1 to 3,

The polyolefin-based resin sheet has an average spherulite radius of 4 μπι or less, an average number of spherulites in the sheet cross section of 600 or less Zmm ² , a solid density of 0.890 g / cm ³ or less, and differential scanning calorimetry (DSC). The melting enthalpy ΔΗ of the maximum endothermic peak of the curve is less than 95 J / g, and the polypropylene layer has an exothermic peak of 1 J / g or more on the low temperature side of the maximum endothermic peak and has a thickness of 50 μπι or more. Characteristic anti-fog polyolefin sheet.

5. The anti-fog polyolefin sheet according to any one of claims 1 to 4,

The anti-fog polyolefin-based sheet, wherein the polyolefin-based resin sheet has an internal haze of (330 t ² _ 150 t + 20)% or less when the thickness of the sheet is t mm.

6. In the anti-fog polyolefin sheet according to any one of claims 1 to 5,

The anti-fog polyolefin-based sheet, wherein the tensile modulus of the polyolefin-based resin sheet is 1500 MPa or less.

7. After the molten polyolefin resin is introduced between the endless belt wound around the plurality of cooling openings and the mirror cooling opening, the molten polymer is introduced by the endless belt and the mirror cooling roll. A sheet forming step of forming a polyolefin resin sheet by quenching and forming a olefin resin sheet by pressing the refin resin into a sheet shape, and forming at least one surface of the polyolefin resin sheet obtained by the sheet forming step. A method for producing an anti-fogging polyolefin sheet, comprising: applying a mixed aqueous solution of an anti-fogging agent and a pinda resin, followed by drying to form a coat layer.

8. A molded article obtained by thermoforming the anti-fog polyolefin sheet according to any one of claims 1 to 6.

9. A food packaging sheet using the antifogging polyolefin-based sheet according to any one of claims 1 to 6.

10. A molded article for food packaging, characterized by using the molded article according to claim 8.