1. A mulch sheet characterized in that this comprises a tissue layer laminated with an opaque laminating adhesive to a second layer made of another biodegradable sheet.
2. A mulch sheet according to claim 1, characterized in that said second layer is a tissue layer.
3. A mulch sheet according to one of claims 1 or 2, characterized in that said layers have a weight within the range of 10 to 50 gm2, in particular, between 15 and 35 gm2.
4. A sheet according to one of claims 1 to 3, characterized in that said layers have different weights.
5. A sheet according to one of claims 1 to 4, characterized in that this has a weight of no more than 100 gm2.
6. A sheet according to one of claims 1 to 5, characterized in that said layers have a stretch at breaking point of 20 to 30% in the running direction of the paper-making machine, as measured in accordance with the international standard ISO 1924207-1995 (paragraph 10.5).
7. A sheet according to one of claims 1 to 6, characterized in that said layers are colored, in particular, colored brown.
8. A sheet according to one of claims 1 to 7, characterized in that said lamination adhesive comprises:
5 to 25% of an opacifying agent, in particular carbon black, in dry-weight, with respect to the total weight of the adhesive;
15 to 85% of a polymer binder, as a stabilized aqueous dispersion, in particular chosen from amongst styrene-butadiene, carboxylated styrene-butadiene and styrene-acrylic copolymers, or acrylic polymers;
0 to 25% of another organic binder, in particular chosen from amongst starch, polyvinyl alcohol, casein, alginates, cellulose derivatives and gelatin;
0 to 70% of other fillers, in particular, mineral fillers chosen from amongst calcium, kaolin and talc; and
0 to 25% of a thickener,
these percentages being dry-weight percentages with respect to the overall dry-weight of the adhesive, and the sum of these percentages being 100.
9. A sheet according to one of claims 1 to 8, characterized in that the lamination adhesive is applied at a rate of 4 to 40 gm2, in dry-weight, preferably 5 to 20 gm2.
10. A method of manufacturing the mulch sheet according to one of claims 1 to 9, characterized in that:
a first tissue layer is unwound;
this first tissue layer is coated with said lamination adhesive; and then,
said second layer is applied on the adhesive; and then,
the mulch sheet obtained in this manner is dried.
11. A method of manufacturing the mulch sheet according to one of claims 1 to 9, characterized in that:
a first tissue layer is unwound;
said layer is coated with said lamination adhesive; and then,
the layer coated in this manner is fed through a drying tunnel;
said second layer is applied on the hot adhesive so as to form the mulch sheet.
12. A method of manufacturing the mulch sheet according to one of claims 1 to 9, characterized in that:
a first tissue layer is unwound;
said layer is coated with said lamination adhesive, then dried; and then,
the cooled, coated layer is rolled;
the coated layer is unwound and fed through a heating cylinder; and
said second layer is applied on the hot adhesive so as to form the mulch sheet.
13. A method of manufacturing a mulch sheet according to one of claims 10 to 12, characterized in that said lamination adhesive is applied by means of silkscreen.
14. A method of manufacturing a mulch sheet according to claim 13, characterized in that the silkscreen apparatus comprises at least two rotating screens.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A production method of a synthetic resin sheet comprising the steps of:
obtaining a preprocessed sheet by introducing into and pressing molten resin between a first metallic endless belt that is disposed around a first cooling roller and a second cooling roller with the outer circumferential surface thereof coated with an elastic material so that the belt can circulate and a third cooling roller that faces the second cooling roller through the first metallic endless belt, at least either one the outer circumferential surfaces of which is a mirror surface, and holding and moving the introduced molten resin between the first metallic endless belt and the third cooling roller for quenching the sheet; and
heat treating the preprocessed sheet by pressing the sheet on either one of the outer circumferential surfaces of the heated roller and the metallic heating endless belt to thermally stick the sheet thereon, moving the thermally stuck sheet between the outer circumferential surfaces of the roller and the heating endless belt, and peeling off this sheet from the outer circumferential surface of the roller and then from the outer circumferential surface of the heating endless belt.
2. A production method of a synthetic resin sheet comprising the steps of:
obtaining a preprocessed sheet by introducing molten resin extruded from a T die to between a first metallic endless belt that is disposed around a first cooling roller and a second cooling roller with the outer circumferential surface thereof coated with an elastic material so that the belt can circulate and a second metallic endless belt that is disposed around a third cooling roller and a fourth cooling roller so that the belt can circulate in the direction reverse to that in which the first metallic endless belt circulates and is provided with the outer circumferential surface thereof facing the outer circumferential surface of the first metallic endless belt, at least either one of the outer circumferential surfaces of which is a mirror surface, holding and moving the introduced molten resin between the first metallic endless belt and the second metallic endless belt while pressed together with the first metallic endless belt and the second metallic endless belt between the second cooling roller and the third cooling roller for quenching the sheet; and
heat treating the preprocessed sheet by pressing the sheet on either one of the outer circumferential surfaces of the heated roller and the metallic heating endless belt to thermally stick the sheet thereon, moving the thermally stuck sheet between the outer circumferential surfaces of the roller and the heating endless belt, peeling off this sheet from the outer circumferential surface of the roller and then from the outer circumferential surface of the heating endless belt.
3. The production method of a synthetic resin sheet according to claim 1 or claim 2, wherein the step of obtaining the preprocessed sheet and the heat treatment step are carried out successively.
4. The production method of a synthetic resin sheet according to claim 1 or claim 2, wherein the preprocessed sheet obtained in the step of obtaining the preprocessed sheet is wound up, and then the wound-up preprocessed sheet is wound off and heat treated.
5. The production method of a synthetic resin sheet according to any of claims 1 through 4, wherein the internal haze of the preprocesses sheet is 20% or below and the surface roughness Rmax on at least one of the surfaces is 0.5 \u03bcm or below.
6. The production method of a synthetic resin sheet according to any of claims 1 through 5, wherein the preprocessed sheet is preheated and then pressed on either one of the outer circumferential surfaces of the heated roller or the heating endless belt to be thermally stuck thereon.
7. The production method of a synthetic resin sheet according to any of claims 1 through 6, wherein the resin is polypropylene-based resin.
8. A synthetic resin sheet obtained by the production method as described in any of claims 1 through 7.
9. A production device for a synthetic resin sheet comprising:
a preprocessed sheet production device for molding a preprocessed sheet including: a T-die extrusion device; a pressure section having a first cooling roller, a second cooling roller with the outer circumferential surface coated with an elastic material, a first metallic endless belt disposed around the first cooling roller and the second cooling roller, and a third cooling roller provided so that molten resin can be introduced to between the outer circumferential surface thereof and the outer circumferential surface of the first metallic endless belt, at least either one of the outer circumferential surfaces of which is a mirror surface, the pressure section pressing the introduced molten resin together with the first metallic endless belt between the second cooling roller and the third cooling roller; and a section for holding and moving the resin between the first metallic endless belt and the third cooling roller; and
a heat-treating device including a heated roller, and a metallic heating endless belt heated and provided with the outer circumferential surface thereof to face the outer circumferential surface of the roller so that the belt can circulate, the heat-treating device being adapted to thermally stick the preprocessed sheet produced by the preprocessed sheet production device on either one of the outer circumferential surfaces of the roller and the heating endless belt, moving the sheet between the outer circumferential surfaces of the roller and the heating endless belt, and peeling off the sheet from the outer circumferential surface of the roller and then from the outer circumferential surface of the heating endless belt.
10. A production device for a synthetic resin sheet comprising:
a preprocessed sheet production device for molding a preprocessed sheet including: a T-die extrusion device; a pressure section having a first cooling roller, a second cooling roller with the outer circumferential surface coated with an elastic material, a first metallic endless belt disposed around the first cooling roller and the second cooling roller, a third cooling roller, a fourth cooling roller, and a second metallic endless belt disposed around the third cooling roller and the fourth cooling roller with the outer circumferential surface facing the outer circumferential surface of the first metallic endless belt so that the belt can circulate in the direction reverse to that in which the first metallic endless belt circulates, and the molten resin can be introduced between the outer circumferential surface thereof and the outer circumferential surfaces of the first metallic endless belt, at least either one of the outer circumferential surfaces of which is a mirror surface, the pressure section pressing the resin together with the first metallic endless belt and the second metallic endless belt; and a pressurizing section for applying pressure in the direction in which the first metallic endless belt and the second metallic endless belt move closer to each other in a zone where the first metallic endless belt and the second metallic endless belt move in parallel to each other; and
a heat-treating device including a heated roller, and a metallic heating endless belt heated and provided with the outer circumferential surface thereof to face the outer circumferential surface of the roller so that the belt can circulate, the heat-treating device being adapted to thermally stick the preprocessed sheet produced by the preprocessed sheet production device on either one of the outer circumferential surfaces of the roller and the heating endless belt, moving the sheet between the outer circumferential surfaces of the roller and the heating endless belt, and peeling off the sheet from the outer circumferential surface of the roller and then from the outer circumferential surface of the heating endless belt.
11. The production device for a synthetic resin sheet according to claim 9 or claim 10, further comprising a preheating device provided between the preprocessed sheet production device and the heat-treating device so as to preheat the preprocessed sheet molded by the preprocessed sheet production device before the sheet is stuck on either one of the outer circumferential surfaces of the roller and the heating endless belt in the heat-treating device.
12. The production device for a synthetic resin sheet according to any of claims 9 to 11, wherein the heat-treating device comprising an elastic roller for temporally welding and thermally sticking the preprocessed sheet on either one of the outer circumferential surfaces of the roller and the heating endless belt to thermally stick the sheet thereon.