JP2000218744A - Foamed polyolefin sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated, foamed polyolefin sheet in which a skin layer is formed at least on one side, and a method for producing the sheet. SOLUTION: In a foamed polyolefin sheet 11, the first foamed polyolefin sheet layer 32 and the second foamed polyolefin sheet layer 33 are laminated, and skin layers 19 are formed on both sides, The sheet 11 is produced by a method in which an expandable raw sheet 22 moving in contact with a belt 18 is heat-treated from the belt 18 side to expand the sheet 22, and before, during, or immediately after the foaming of the sheet, a foamed sheet 31 with a skin layer 19 formed on one side is laminated on the sheet 22 before or after the foaming so that the back of the skin layer 19 is adhered to the sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin foam sheet and a method for producing the same, and is used for producing, for example, armrests and headrests of automobiles, decorative plywood for building interiors, wallpaper, sports equipment life jackets, protectors, and the like. it can.

[0002]

BACKGROUND ART Polyolefin-based foam sheets have characteristics such as weather resistance and pollution-free properties and are widely used as building materials for sundries, flooring materials, wallpaper, and the like. Conventionally, it has been common practice to heat and foam a polyolefin-based foamable raw sheet by heating the sheet from both sides using a hot oven. But,
Since nothing is in contact with the both sides of the foamable raw sheet, the cells at the time of foaming affect the surface, and irregularities are likely to be generated on the surface. In addition, it is necessary to attach cloth or paper to the sheet so that the sheet does not expand and contract during heating. In this case, the irregularities on the surface are improved, but a step of peeling the cloth or paper is required later.

For example, according to Japanese Patent Application Laid-Open No. 56-137937, an olefin resin as a main material to which a crosslinking agent, a foaming agent and the like are added is formed into a sheet by an extruder and a calender roll. A method for producing a foamed sheet in which a foamed sheet is foamed while being sandwiched between two endless belts is disclosed. In this manufacturing method, since the upper and lower belts are pressed by the heating roll between the two main shafts around which the belt is wound, there is a possibility that the foam cannot be sufficiently foamed, or even if foamed, the foam is crushed.

According to Japanese Patent Application Laid-Open No. 9-290430, a foamable sheet is placed on a transporting material having a plurality of air holes and having excellent peelability from the foamable sheet, and is placed in a heating oven. A method for producing a polyolefin-based resin open-cell foam in which a foamable sheet is heated and foamed while being transported by the transport material is disclosed. According to this manufacturing method, partial swelling is slightly improved, but unevenness is generated on the front side of the foamable raw sheet at the time of heating and foaming, and transfer of air holes to the back surface of the sheet is inevitable.

Accordingly, an object of the present invention is to provide a polyolefin foam sheet having a laminated structure in which a skin layer is formed on at least one surface, and a method for producing the same.

[0006]

The polyolefin foam sheet according to the first invention of the present invention has a laminated structure of a first polyolefin foam sheet layer and a second polyolefin foam sheet layer, and at least one of them has a laminated structure. Is characterized in that a skin layer is formed on the surface side. According to the present invention,
Since the polyolefin foam sheet is constituted by the two-layer structure of the first foam sheet layer and the second foam sheet layer, it is easy to produce even a thick foam sheet having a thickness of, for example, 1 mm or more. Become. When the skin layers are formed on both surfaces, a foamed sheet having a good appearance on any surface can be obtained. In addition, the sheet includes a case where the thickness of the film is relatively thinner than that of the sheet.

The method for producing a polyolefin foam sheet according to the second invention of the present invention is characterized in that a heat treatment is applied to the polyolefin foam sheet, which moves in close contact with the adhesive medium, from the adhesive medium side. Foam the anti sheet,
Before, during, or immediately after foaming of the foamable raw sheet, a polyolefin foam sheet is laminated on the foamable raw sheet or foamed sheet. It is optional whether the time when the polyolefin foam sheet is laminated on the foamable raw sheet or the foamed sheet is any time before, during or after the foaming of the foamable raw sheet.

[0008] The contact medium may be an endless belt, a roll, or the like. The foamable raw sheet,
It may be moved in close contact with the moving contact medium, or may be moved in a state where only the foamable raw sheet is in close contact with the fixed contact medium. The heating of the foamable raw sheet can be performed by, for example, a heating roll disposed on the back side of the endless belt, a heating unit incorporated in the roll, or the like.

As the foamable raw sheet, a foamable raw sheet directly supplied from a calendering machine can be used in addition to a preformed foam and wound on a roll. Also, using the melt web from the extruder,
It is also possible to supply directly to the contact medium and perform thermocompression bonding.
The raw material of the polyolefin foam sheet may be an olefin polymer, and may be a homopolymer or a copolymer of two or more types. Further, a mixture of two or more of them may be used.

The above-mentioned homopolymer is polyethylene, polypropylene, polyisoprene, polybutadiene and the like, and the above-mentioned copolymer is ethylene-α olefin copolymer, propylene-α olefin copolymer and the like. Further, a filler such as an elastomer such as ethylene-propylene rubber (EPR) or calcium carbonate may be appropriately added to the raw material. As the foaming agent contained in the foamable raw sheet, any one can be used as long as it thermally decomposes at a predetermined temperature. For example, azodicarbonamide (ADCA),
And sodium bicarbonate.

The foaming temperature refers to a temperature higher than the decomposition temperature of the foaming agent contained in the foamable raw sheet. However, it is possible to lower the decomposition temperature of the foaming agent itself by adding the foaming aid to the foamable raw sheet. ADVANTAGE OF THE INVENTION According to this invention, since the other foam sheet can be heat-laminated with respect to one foam sheet, the polyolefin foam sheet of a laminated structure in which both sheets were reliably integrated can be obtained.

[0012] The method for producing a polyolefin foam sheet according to the third invention of the present invention is the method according to the second invention, wherein the foamable raw sheet is formed at any time before, during, or immediately after foaming of the foamable raw sheet. A polyolefin foam sheet having a skin layer formed on one side is laminated on the anti-sheet or foam sheet so that the back side of the skin layer is adhered. According to the present invention, a foamed sheet having a two-layer structure in which skin layers are formed on both surfaces is obtained.

The method for producing a polyolefin foam sheet according to the fourth invention of the present invention is the method according to the second or third invention, wherein the endless belt is wound around a plurality of rolls including the first and second heating rolls. The heat treatment is performed from the endless belt side to the polyolefin foamable raw sheet that moves in close contact with the endless belt, using the apparatus described above, and the foamable raw sheet is foamed.

As the material of the endless belt, a material having good heat conductivity, for example, stainless steel, nickel spring steel, glass fiber reinforced fluororesin, or the like can be used. The surface of the belt may be thinly coated with a material having good releasability (such as polyimide). The foamable raw sheet can be foamed using an apparatus having the endless belt.

According to a fifth aspect of the present invention, in the method for producing a polyolefin foam sheet according to the fourth aspect, the foamable raw sheet is provided with the first foam via the endless belt.
A heat roll, and the foamable raw sheet is heated at a temperature lower than the foaming start temperature by heating the foamable raw sheet to a temperature at which the thermocompression bonding to the endless belt is possible. Thermocompression bonding, and subsequently, the foamable raw sheet is brought into contact with the second heating roll via the endless belt, and the foamable raw sheet is heated at a temperature equal to or higher than a foaming start temperature to foam. It is characterized by making it. According to the present invention, since the heating-side surface is heated and foamed with respect to this foamable raw sheet in a state in which the heating-side surface is in close contact with the endless belt, there is almost no expansion due to foaming in the plane direction of the foamable raw sheet. Since the expansion is performed exclusively in the thickness direction, a thick foamed sheet can be obtained.

In the method for producing a polyolefin foam sheet according to the sixth invention of the present invention, the apparatus according to the second or third invention uses an apparatus provided with a roll having first and second heating portions on a part of its surface. A heat treatment is applied from the roll side to the polyolefin foamable raw sheet that moves in close contact with the roll to foam the foamable raw sheet.

The surface material of the roll preferably has good thermal conductivity and low adhesion to the foamable raw sheet, and the metal roll coated with a polyimide resin on its surface is optimal. The foamable raw sheet can also be foamed using an apparatus provided with the roll.

According to a seventh aspect of the present invention, in the method for manufacturing a polyolefin foam sheet according to the sixth aspect, the foamable raw sheet is brought into contact with the first heating portion, and the foamable raw sheet is contacted therewith. The sheet is heated at a temperature equal to or higher than the temperature at which thermocompression bonding to the roll is possible and lower than the foaming start temperature to bring the foamable raw sheet into close contact with the roll, and subsequently, the foamable raw sheet is subjected to the second heating. The foamable raw sheet is foamed by heating the foamable raw sheet at a temperature equal to or higher than the foaming start temperature.

According to the present invention, since the foamable raw sheet is heated and foamed in a state where the heating side surface is in close contact with the roll, expansion due to foaming of the foamable raw sheet in the plane direction is prevented. Since there is almost no expansion only in the thickness direction, a thick foamed sheet can be obtained.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A polyolefin foam sheet according to a first embodiment of the present invention and a method for producing the same will be described with reference to FIGS. First, the configuration of a device for producing the polyolefin foam sheet 11 used in the production method of the present embodiment will be described.

As shown in FIG. 1, the manufacturing apparatus includes three rolls 12 arranged at respective corners of a triangle.
, A first supply roll 15 for supplying a polyolefin-based foamable raw sheet 22
A second supply roll 16 for supplying a polyolefin foam sheet 31 having a skin layer 19 formed on one side, and a winding roll 17 for winding the obtained two-layered polyolefin foam sheet 11. It is configured. First roll 12 and second roll in the first endless belt 18
Reference numeral 13 denotes a heating roll having a built-in heating means such as a heater, and a third roll 14 is a cooling roll having a built-in cooling means such as a water-cooled type.

At least one of the first to third rolls 12 to 14 is connected to a rotary driving means such as a motor. This endless belt 18 is made of metal such as stainless steel or resin such as glass fiber reinforced fluororesin,
A polyimide resin is coated on the surface to which the sheet adheres. In the vicinity of the first roll 12, a first guide roll 23 for pressing the foamable raw sheet 22 unwound from the first supply roll 15 against the endless belt 18 is provided.

On the other hand, the running endless belt
At a position immediately before the 18 is wound around the second roll 13,
A second guide roll 24 for pressing the foam sheet 31 having the skin layer 19 fed from the second supply roll 16 against the endless belt 18 is provided. In the vicinity of the third roll 17, the produced polyolefin foam sheet 11 is peeled off from the endless belt 18 and wound up.
A third guide roll 25 for guiding to 17 is provided. Each of the guide rolls 23 to 25 has a surface coated with a polyimide resin.

Using this manufacturing apparatus, a polyolefin foam sheet 11 is manufactured as follows. First, the foamable raw sheet 22 supplied from the first supply roll 15 is brought into contact with the endless belt 18 at the position of the first roll 12 by the first guide roll 23, and is heated by the roll 12. The one side 22A of the foamed raw sheet 22 is
In close contact. The heating temperature here is the foamable raw sheet
The temperature is equal to or higher than the temperature at which thermocompression bonding of the belt 22 to the belt 18 is possible and lower than the foaming start temperature.

Subsequently, the foamable raw sheet 22 adhered to the endless belt 18 is rotated by the rotation of the belt 18 to form a second sheet.
, And one surface 22A of the foamable raw sheet 22 is brought into contact with the second roll 13 via the belt 18. At this time, the back surface side of the skin layer 19 is bonded to the polyolefin foam sheet 31 having the skin layer 19 formed on one side supplied from the second supply roll 16 to the pre-foamable raw sheet immediately before foaming. (Fig. 2
reference). Then, with the one surface 22A of the foamable raw sheet 22 in close contact with the belt 18, the heated second roll 13
The foamed raw sheet 22 is heated and foamed at a temperature equal to or higher than the foaming start temperature, and at the same time, the skin layer 19 is formed.
reference).

Thereafter, the produced polyolefin foam sheet 11 having a two-layer structure is moved to the third roll 14 side, where the polyolefin foam sheet 11 is cooled.
Roll up the foam sheet 11 through the guide roll 25
Rewind to 27. As shown in FIG. 3, the polyolefin foam sheet 11 is formed by foaming a first polyolefin foam sheet layer 32 which is a polyolefin foam sheet 31 on which a skin layer 19 has been formed in advance and a foamable raw fabric sheet 22. 2 with the formed second polyolefin foam sheet layer 33
It has a layer structure and has skin layers 19 formed on both sides.

In this embodiment, the polyolefin foam sheet 31 having the skin layer 19 on one side is laminated on the foamable raw sheet 22 before foaming.
As shown by a two-dot chain line, a polyolefin foam sheet 31 may be laminated on the foamable raw sheet 22 being foamed via a fourth guide roll 28. In addition, the fifth
The polyolefin foam sheet 31 may be laminated on the foam sheet immediately after the foamable raw sheet 22 has foamed via the guide roll 29. In the present embodiment, as a sheet to be laminated on the foamable raw sheet 22, a skin layer is formed on one side.
Although the polyolefin foam sheet 31 formed with 19 was used, a polyolefin foam sheet without a skin layer may be used. In this case, the skin layer 19 is formed only on one side.
Is obtained, the foamed sheet 11 having a two-layer structure is formed.

Second Embodiment A polyolefin foam sheet 11 according to a second embodiment of the present invention and a method for producing the same will be described with reference to FIG. First, a configuration of a manufacturing apparatus of the polyolefin foam sheet 11 used in the present embodiment will be described. As shown in FIG. 4, this manufacturing apparatus supplies a roll 44 having first and second heating portions 41 and 42 and a cooling portion 43 on the surface in this order, and a polyolefin foamable raw sheet 22. A first supply roll 46, a second supply roll 47 for supplying a polyolefin foam sheet 31 having a skin layer 19 formed on one surface, and a winding for winding the resulting two-layered polyolefin foam sheet 11. Take roll 52
It is comprised including. The ratio of each of the portions 41, 42, and 43 to the total surface area is approximately 1/6 for the first heating portion 41, approximately 1/3 for the second heating portion 42, and approximately 1/2 for the cooling portion 43.

The first and second heating portions 41 and 42 of the roll 44 incorporate heating means such as a heater, and the cooling portion 43 incorporates cooling means such as a water-cooling type. The roll 44 is installed in a fixed state. In the vicinity of the first heating portion 41 of the roll 44, a first supply roll is provided.
A first guide roll 48 is provided for pressing the foamable raw sheet 22 fed from the roll 46 against the roll 44.

On the other hand, at an intermediate position of the second heating portion 42,
A second guide roll 49 is provided for pressing the polyolefin-based foam sheet 31 having the skin layer 19 fed from the second supply roll 47 against the roll 44. In the vicinity of the cooling portion 43, a third guide roll 51 for peeling the cooled polyolefin-based foamed sheet 11 from the roll 44 and guiding it to the winding roll 52 is provided.
Each of the guide rolls 48, 49, 51 has a surface coated with a polyimide resin.

Using this manufacturing apparatus, a polyolefin foam sheet 11 is manufactured as follows. First, the foamable raw sheet 22 supplied from the first supply roll 46 is brought into contact with the first heating portion 41 of the roll 44 by the first guide roll 48, and the heating portion 41 One surface 22A of the sheet 22 is preheated. The heating temperature here is equal to or higher than the temperature at which the foamable raw sheet 22 can be thermocompression-bonded to the roll 44 and lower than the foaming start temperature.

Subsequently, the preheated foamable raw sheet 22 is caused to travel to the position of the second heating portion 42, and the second supply roll 47 is applied to the foamable raw sheet 22 being foamed. The polyolefin-based foam sheet 31 provided with the skin layer 19 on one side is laminated so that the back side of the skin layer 19 is adhered (see FIG. 2). Then, in a state where one surface 22A of the foamable raw sheet 22 is in close contact with the roll 44, the foamable raw sheet 22 is heated and foamed at a temperature equal to or higher than the foaming start temperature by the heated second heating portion 42. At the same time, a skin layer 19 is formed (see FIG. 3).

Thereafter, the produced polyolefin foam sheet 11 having a two-layer structure is moved to the cooling portion 43 side, where the polyolefin foam sheet 11 is cooled. 11 is wound up on a winding roll 52. In the present embodiment, the polyolefin foam sheet 31 having the skin layer 19 on one side is laminated on the foamable raw sheet 22 being foamed. System foam sheet
31 may be laminated or foamed raw sheet
The polyolefin foam sheet 31 may be laminated on the foam sheet immediately after the foam 22 has been foamed.

[0034]

EXAMPLES [Example 1] In the first embodiment, a polyolefin foam sheet 11 was manufactured under specific conditions as follows. First, the following sheet materials were kneaded at 180 ° C. using a mixing roll, and charged into a calendering device via a warming roll. This calendering apparatus was a four-roll type, and the set temperature of the first roll was 140 ° C. The final thickness of this molding machine is 0.5
The foamed raw fabric sheet 22 having a width of 1020 mm and a width of 1020 mm was finished.

<Sheet raw material> Polyolefin foam resin: L-LD manufactured by Idemitsu Petrochemical Co., Ltd.
PE (linear low-density polyethylene) Moretech 0134 (trade name), MRF: 1.2 g / 10 min, 80 kg. Ethylene propylene rubber (EPR): P0680 (trade name) manufactured by Mitsui Petrochemical Co., Ltd., MRF: 0.7 g / 10 minutes (230 ° C),
20kg. Blowing agent: Azodicarbonamide (ADC) manufactured by Eiwa Chemical Co., Ltd.
A) VINHALL AC♯3 (trade name), decomposition temperature: 208 ℃, 3k
g. Foaming aid: Metal soap (Zinc aliphatic monocarboxylate) SP-100Z (trade name), manufactured by Eishin Kasei Co., Ltd., 1 kg.

Next, using the foamable raw sheet 22,
The conditions such as the temperature of the roll in the manufacturing apparatus were as follows. On the other hand, as the polyolefin-based foam sheet 31 having the skin layer 19 formed on one side, the above-described embodiment in which only the foamable raw sheet 22 was foamed without lamination was used. The temperature of the first roll 12: 140 ° C. The temperature of the second roll 13: 200 ° C. The temperature of the third roll 14 ... 30 ° C. Expansion ratio: 5 times. Heating time between the second heating roll 13 and the cooling roll 14: 35 seconds. The resulting two-layer polyolefin foam sheet (thickness
(0.5 mm) 11 had the skin layers 19 formed on both sides, was glossy, and had a good appearance.

[Comparative Example 1] The polyolefin foam sheet according to this comparative example is obtained by foaming only the foamable raw sheet 22 without laminating in the above embodiment. The manufacturing conditions are the same as in the first embodiment. The obtained polyolefin foam sheet had some irregularities on the surface opposite to the heated surface.

[0038]

According to the present invention, a polyolefin foam sheet having a laminated structure having a skin layer formed on at least one surface can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus used in a method for producing a polyolefin foam sheet according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a sheet and an endless belt showing a manufacturing method according to the embodiment.

FIG. 3 is a cross-sectional view of a polyolefin foam sheet having a two-layer structure obtained by the same embodiment.

FIG. 4 is a schematic view of an apparatus used in a method for producing a polyolefin foam sheet according to a second embodiment of the present invention.

[Explanation of symbols]

 11 Polyolefin foam sheet 12-14 Roll 15 First supply roll 16 Second supply roll 18 Endless belt 19 Skin layer 22 Polyolefin foam raw sheet 22A One side 31 Polyolefin foam sheet 32 First polyolefin foam Foam sheet layer 33 Second polyolefin foam sheet layer 41 First heating section 42 Second heating section 43 Cooling section 44 Roll 46 First supply roll 47 Second supply roll

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) B29K 105: 04 B29L 9:00 F term (Reference) 4F100 AH02H AH03H AH08H AK03A AK03B AK63 AK64 AL05 AN02 BA02 BA43 CA01 DJ01A DJ01B EA021 EA022 EH012 EJ021 EJ023 EJ421 EJ423 EK03 GB08 GB33 GB87 JK15 JL02 4F204 AA03 AA08K AA09K AA45K AB02 AC03 AD05 AD08 AD17 AE06 AE07 AG01 AG03 AG20 A26AH26 AH27 FH23 AH48 AH27 FH23 AH48 AH27 AB02 AG20 AH26 AH27 AH48 AH59 AR06 AR11 UA09 UB02 UB22 UB30 UG02 UG05 UJ11 UN09 UN13

Claims (7)

[Claims] 1. A polyolefin foam having a laminated structure of a first polyolefin foam sheet layer and a second polyolefin foam sheet layer, wherein a skin layer is formed on at least one surface side. Foam sheet. 2. A foamable raw sheet, which is moved in close contact with an adhesive medium, is subjected to a heat treatment from the adhesive medium side to foam the expandable raw sheet. A method for producing a polyolefin foam sheet, comprising laminating a polyolefin foam sheet on the foamable raw sheet or foam sheet at any point during or immediately after foaming. 3. The method for producing a polyolefin foam sheet according to claim 2, wherein the foamable raw sheet or foam sheet is formed at any time before, during or immediately after foaming of the foamable raw sheet. Then, a polyolefin foam sheet having a skin layer formed on one side is laminated so that the back side of the skin layer is adhered to the polyolefin foam sheet. 4. The method for producing a polyolefin foam sheet according to claim 2, wherein an apparatus having an endless belt wound between a plurality of rolls including a first and a second heating roll is used. A method for producing a polyolefin-based foamed sheet, comprising subjecting a heat-treated polyolefin-based foamed sheet that is in close contact with the endless belt to heat treatment from the endless belt side to foam the foamable sheet. 5. The method for producing a polyolefin-based foam sheet according to claim 4, wherein the foamable raw sheet is brought into contact with the first heating roll via the endless belt, and the foamable raw sheet is formed therein. The anti-sheet is heated at a temperature higher than the temperature at which thermocompression bonding to the endless belt is possible and lower than the foaming start temperature to thermocompression-bond the foamable raw sheet to the endless belt. A method for producing a polyolefin foam sheet, comprising bringing the foamable raw sheet into foam by heating the foamable raw sheet at a temperature equal to or higher than a foaming start temperature, by bringing the foamable raw sheet into contact with the second heating roll via an endless belt. 6. The method for producing a polyolefin foam sheet according to claim 2, wherein an apparatus having a roll having first and second heating portions on a part of its surface is used, and the roll is closely attached to the roll. A method for producing a polyolefin-based foamed sheet, comprising: applying heat treatment to the moving polyolefin-based foamable sheet from the roll side to foam the foamable sheet. 7. The method for producing a polyolefin-based foam sheet according to claim 6, wherein the foamable raw sheet is brought into contact with the first heating portion, and the foamable raw sheet is transferred to the roll. Is heated at a temperature not lower than the temperature at which thermocompression bonding can be performed and lower than the foaming start temperature to bring the foamable raw sheet into close contact with the roll. Subsequently, the foamable raw sheet is brought into contact with the second heated portion. Here, a method for producing a polyolefin foam sheet, wherein the foamable raw sheet is foamed by heating at a temperature equal to or higher than a foaming start temperature.