JPS5950493B2 - Laminate manufacturing method and coextrusion die used therein - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a laminate and a coextrusion die used therein.

The present invention particularly relates to a coextruded molten resin web of multiple layers of thermoplastic resins such as polyolefin resins, ethylene copolymers, polyesters, and nylon. This article relates to a method for producing a laminate by extrusion coating on a material and an apparatus for carrying out the method, and more specifically, the citrus oil layer on the base material side of the web has good adhesion, and at the same time, There is little oxidation and decomposition of the surface of the coating resin film on the side that does not contact the base material.Therefore, the laminate has excellent heat sealability, little change in heat sealability over time, and low resin oxidation and decomposition odors. It relates to a manufacturing method and an apparatus for carrying out the method. Conventionally, as a method for manufacturing laminates for packaging, release paper, etc., resins such as polyolefin resin, ethylene copolymer, polyester, and nylon are used. After being melted and kneaded in an extruder, it is extruded through an extrusion die to create a molten resin web, which is then subjected to appropriate pretreatments such as anchor coating, corona discharge treatment, and flame treatment to improve adhesion. film,
The so-called extrusion coating method is widely used, in which materials are pressure-bonded to a base material such as paper or aluminum foil, and cooled at the same time.

In this case, the main reasons for coating the base material with a resin film such as polyolefin resin, ethylene copolymer, polyester, or nylon are to provide the base material with heat-sealing properties, moisture-proofing properties, grease-proofing properties, impact resistance, releasability, protective effects, etc. The goal is to give the characteristics of In the conventional extrusion coating process for polyolefin resins and other materials, in order to bond the polyolefin resins and other materials to the substrate with sufficient strength, the temperature of the resin in the extruder and die is usually set at 300°C or higher. It needs to be very hot. The reason for this is that in order to adhere to the base material, the melt viscosity of the resin is lowered to improve wetting to the base material, and at the same time, polyolefin resins such as polyethylene and polypropylene have the necessary polarity to adhere well to the base material. This is because the molten polyolefin is oxidized by air while the molten resin web passes through a distance called an air gap from the die exit to the crimping point between the cooling roll and the nip roll. be. For example, in the extrusion coating process of low-density polyethylene, high temperature conditions such as a resin temperature of 320 to 330°C at the adapter part and a molten resin web temperature of 300 to 315°C at the die exit are used to moderate the molten polyethylene. It is oxidized to In this way, in extrusion coating of thermoplastic resins such as polyolefin resins,
Web temperature, which affects the oxidation state of the molten resin web, has become an important factor that affects the adhesion between the web and the base material.
As mentioned above, in the known extrusion coating method, it is usually necessary to raise the resin temperature to over 300°C in order to generate sufficient adhesive strength between the web and the substrate. Laminates made by extrusion coating other substrates have several drawbacks, particularly when used as packaging materials.

That is, in a laminate of a polyolefin resin or other material and a base material by a known method, since the polyolefin resin or other material is heated to a high temperature during extrusion, thermal deterioration of the resin, that is, oxidation, decomposition, crosslinking, etc., often occurs.
As a result, there is a problem in that the heat sealing properties of the coated resin layer deteriorate, and this deterioration becomes more severe as time passes.

For example, in the inventor's test, a laminate manufactured by extrusion coating low-density polyethylene to a thickness of 40 μm on a cellophane base material at a resin temperature (adapter part) of 320°C was coated at an environmental temperature of 50°C. It has been found that when left for 20 days, the heat seal strength decreases to about 50% of the value measured 3 days after processing. Another disadvantage of laminates of polyolefin resins or other thermoplastic resins and base materials produced by known extrusion coating processing methods is that polyolefin resins and other materials are processed at high temperatures, which can cause oxidation and decomposition of the resin. ,
One example of this is that a unique odor, so-called "litter odor", is generated in the coating layer.

When this laminate is used as a packaging material, because the coating layer is located inside the package than the base material, this odor is easily transferred to the contents, often causing problems with the odor and odor of the contents. ing. Furthermore, laminates of polyolefin resins or other thermoplastic resins obtained by known methods also have the disadvantage that their physical and chemical properties deteriorate due to thermal deterioration of the resin.

As described above, laminates of thermoplastic resins such as polyolefin resins and base materials produced by known extrusion coating processing methods have several drawbacks as packaging materials, as described above, due to thermal deterioration of the resins. It has become a thing. In addition, when manufacturing laminates made of polyolefin resin, polyester, nylon, etc. and paper or cloth for uses other than packaging materials, such as release paper and process paper, by extrusion coating,
In order to generate sufficient adhesion between the extruded coating layer and the substrate, the temperature of the molten resin usually needs to be higher than 300°C, but the coating resin surface of the laminate thus obtained is susceptible to oxidation due to heat. Because of this, the peeling performance is reduced. In this known extrusion coating process, it is necessary to raise the resin temperature to a very high temperature in order to adhere to the base material, but laminates processed under these conditions have poor physical properties due to oxidation of the resin surface. There is a great contradiction in that it has several drawbacks.

As a method to overcome the drawbacks of such known methods, in recent years some use of coextrusion has been considered.

This method uses two extruders as shown in Fig. 2, and one extruder is used to generate the air oxidation necessary for adhesion on the surface of resin A, which is on the base material side of the molten web, while passing through an air gap. The resin B is kneaded at a temperature of 300°C or higher, and the other extruder is used to extrude and coat the resin B on the opposite side of the base material, and the resin is kneaded at a relatively low temperature so as to prevent oxidation as much as possible while passing through the air gap. This leads to T-die. However, in this method, even if there is a large difference in the temperature of the two resins introduced into the T-die,
Heat exchange takes place between the die and the resin while passing through the T-die, and in reality the temperature difference between the hot and cold resin at the die exit is usually reduced to 10-20°C. Therefore, it is inevitable that not only the high-temperature side layer α1 but also the low-temperature side layer β1 of the molten web undergoes considerable oxidation while passing through the air gap.
As a result, the entire web becomes odorous due to oxidation products. The present inventors have conducted intensive studies aimed at eliminating all of the above-mentioned drawbacks in extrusion coating processing of thermoplastic resins including conventionally known polyolefin resins, and as a result, they have arrived at the present invention.

That is, an object of the present invention is to heat the resin layer on the base material side of a coextruded molten web consisting of multiple layers of thermoplastic resin and to be extrusion coated on the base material to a sufficiently high temperature, and to heat the resin layer on the opposite side of the base material to a sufficiently high temperature. An object of the present invention is to provide an improved method for manufacturing a laminate that makes it possible to maintain the laminate at a sufficiently low temperature, and a die used therein.

Another object of the present invention is that the resin layer on the side in contact with the base material of the coextruded molten web exhibits good adhesion to the base material, and that oxidation and decomposition of the resin layer on the side not in contact with the base material is suppressed. , Therefore, a method and apparatus for producing a laminate that makes it possible to produce a laminate that has excellent delamination resistance and heat-sealing properties, little deterioration of heat-sealing over time, and good flavor retention of the resin layer. is to provide.

According to the present invention, in a method for producing a laminate by coextruding a plurality of layers of thermoplastic resin into a molten web through a coextrusion die and coating the web on a substrate, the resin on the side in contact with the substrate is coated on the substrate. The resin is maintained at a higher temperature than the resin on the side that is not in contact with the die and introduced into the die, and the flow path in the die for the resin on the side that is in contact with the base material is set to a high temperature, and the flow path in the die for the resin on the side that is not in contact with the base material is set to a low temperature. setting, providing a heat insulating space between the plurality of resin flow paths in the die, and flowing gas into the space,
There is provided a method for producing a laminate, characterized in that coextrusion is performed with a temperature difference between the plurality of resin layers.

According to the present invention, the present invention further includes two die bodies and at least one partition member located between them, and a plurality of resin flow channels between each die body and the partition member or between each partition member. In a coextrusion die in which a plurality of resin flow channels merge at the tip of a partition member and form one die land at the bottom thereof, a heat insulating space that becomes a gas flow path is provided inside the partition member. A gas inlet is provided at one end of the space, a gas outlet is provided at the other end of the space, and a separate temperature control mechanism is provided in each die portion divided by the gas flow path. A laminating coextrusion die featuring features is provided.

According to the present invention, as described above, a heat insulating space is provided in the partition member in the coextrusion die, gas is actively flowed into this space, and each die portion divided by the heat insulating space has a temperature control mechanism. By providing this, it becomes possible to perform coextrusion with a predetermined temperature difference between the resin layer on the base material side of the melt coextruded web and the resin layer on the opposite side, and as a result,
Sufficiently increases the interlayer adhesion between the resin layer on the base side of the coextruded web and the base material, and prevents oxidation and deterioration of the resin layer on the opposite side of the base material, improving low-temperature heat sealability. It is possible to prevent deterioration of strength over time and to produce a laminate with an odor-free heat-sealing surface.

In a preferred embodiment of the present invention, the exhaust gas from the above-mentioned heat insulating space is blown onto one or both sides of the molten coextruded web.

In this way, by blowing the gas that communicates with the heat insulating space onto the web, in addition to the above-mentioned advantages, low molecular weight substances and decomposition products of the resin generated from the high temperature resin web are blown away, and the laminate is Odor-causing substances are effectively removed, and as a result, flavor retention when the laminate is used as a packaging material can be dramatically improved. Moreover, if an inert gas is sprayed on the side of the molten web opposite to the base material, oxidative deterioration of the resin layer on this side can be more effectively prevented, and ozone, oxygen, etc. When sprayed, the resin layer on this side oxidizes and adheres to the base material. The additional advantage of further improved performance is also achieved. The invention will be explained in more detail below on the basis of examples shown in the accompanying drawings.

Figure 1 shows a typical known extrusion coating. The resin X melted and kneaded in the extruder at a temperature of at least 300°C is transferred to the die body 1 of the extrusion coating die heated by heaters 5 and 6. It passes through the opened resin passage 2 and is guided to the manifold 3.

The molten resin spread in the width direction of the die within the manifold 3 is pushed out of the die through the die outlet 4 formed by two die lips whose position is adjusted by adjustment bolts, becomes a molten resin web, and is passed through the air gap. While passing through A, its surface is oxidized by air, and as soon as it touches the base material 7, it is pressed onto the base material 7 by a nip roll 9 whose surface is coated with rubber and a metal cooling roll 8. In this case, it is desirable that the surface α on the base material side of the molten resin web is oxidized as much as possible in order to firmly adhere to the base material 7, while the surface β that does not contact the base material 7 has good heat sealability and odor. From these points of view, it is desirable to avoid oxidation as much as possible, but in this conventionally known method, the α and β faces of the molten resin web
It is impossible to change the oxidation degree of each surface separately, and as a result, a narrow oxidation degree range is set as a compromise between the oxidation degree required for the α-face and the oxidation degree required for the β-face.
Processing conditions such as resin temperature, air gap, and take-off speed are adjusted to match this. Therefore, if the laminating conditions change for some reason, the oxidation state of the molten resin web will change, and if the oxidation degree exceeds the narrow appropriate range as a compromise, it will cause poor adhesion, poor heat sealing, etc. This defective phenomenon appears and often becomes a problem in the actual processing of extrusion coatings. As one solution to this problem, a method using a two-layer coextrusion die has been used in some cases.

FIG. 2 shows the two-layer coextrusion die and laminating section (cooling roll and nip roll) used in this method. Resin A melted and kneaded at a resin temperature of, for example, 320°C in the first extruder is guided to the manifold 13 through a resin passage 23 opened in the die body 10, which is heated to, for example, 320°C by a heater 21. After spreading over the entire width, it passes through the resin flow path 15 formed between the die body 10 and the partition plate 12 and heads for the confluence 17 at the tip of the partition plate 12. Meanwhile, in the second extruder, for example, 270°C
The melted and kneaded resin B passes through a resin passage 24 opened in the die body 11 which is heated to, for example, 270°C by a heater 22, is guided to the manifold 14, spreads over the entire width of the die, and then passes through the die body 11. The resin passes through a resin flow path 16 formed between the resin flow path 11 and the partition plate 12 to the merging portion 17 . Here, the temperature of the partition plate 12 is between the temperature of 320°C of the die body 10 and the temperature of 270°C of the die body 11, so the temperature of the resin A flowing inside the die is lower than the 320°C when it flows into the die. The temperature of the resin B flowing therein becomes higher than 270° C. at the time of inflow, and the resin B merges at the merging portion 17. Therefore, the temperature difference at the die exit 18 between the high temperature resin A and the low temperature resin B coextruded from the die exit 18 is considerably smaller than the temperature difference when they enter the die. As a result of the temperature of the high-temperature side layer α of the molten web becoming lower than the appropriate temperature, sufficient adhesion with the base material 7 is difficult to occur, and at the same time, the temperature of the low-temperature side layer β of the molten web also becomes higher than the target temperature. Together with the high-temperature side layer α, it undergoes considerable oxidation during passage through the air gap, resulting in the creation of an odor-bearing laminate as a whole.
There still remains a problem regarding changes in heat sealability over time. FIG. 3 shows a two-layer coextrusion die and laminate section according to the present invention.

Resin A melt-kneaded at, for example, 320°C in the first extruder
is guided to the manifold 31 through a resin passage 29 opened in the die body 25, which is heated to, for example, 320° C. and whose temperature is controlled by a heater 41 and a thermocouple 43, and spreads over the entire width of the die. The resin passes through a resin flow path 33 formed between the base material-side block 27 of the partition plate and heads toward the merging portion 35 . Here, the base material side block 27 of the partition plate is heated to, for example, 320°C and temperature controlled by a heater 39 and a thermocouple 45, and furthermore, this block 27 is
Air, nitrogen, and other gases are introduced from the gas inlet 37 made in the partition plate through a gas flow path (
By introducing the heat insulating space into the heat insulating space 38 and discharging it from both ends of the sink die, it is possible to
8 and is insulated. Therefore, the resin A passes through the manifold 31 from the resin passage 29, passes through the resin flow passage 33, and reaches the confluence point 3.
It is possible to maintain the resin temperature at the time of introduction into the die, for example, 320° C., until the temperature reaches 5.5. On the other hand, resin B melt-kneaded at 270°C in the second extruder, for example,
The resin passes through a resin passage 30 opened in the die body 26 which is heated to, for example, 270° C. by a heater 42 and a thermocouple 44 and whose temperature is controlled, and is guided to the manifold 32 and spread over the entire width of the die. and the block 28 on the opposite side of the partition plate base material.
Head to the confluence section 35 through the intersection. Here, the temperature of the block 28 on the opposite side of the partition plate from the base material is heated to, for example, 270° C. by a heater 40 and a thermocouple 46, and as described above, this block 28 has a hole in the partition plate. By introducing air, nitrogen, or other gas from the gas inlet 37 formed in the die into the gas flow path 38 formed over the entire width of the die, and discharging it from both ends of the die, the base material side of the partition plate is It is insulated from block 27. Therefore, the resin B passes through the manifold 32 from the resin passage 30, passes through the resin flow path 34, and until it reaches the confluence point 35, it is possible to maintain the resin temperature at, for example, 270° C. when it is introduced into the die.
The resin flows that merge and become laminated at the confluence point 35 are extruded from the die outlet 36 to become a molten web. The high-temperature layer α2 on the base material side of this molten web is at a high enough temperature to create strong adhesive force with the base material 7, and the layer β2 on the opposite side of the molten web from the base material can be subjected to extrusion coating processing. The molten web consisting of these two layers can be pressed onto the base material 7 between the cooling hole 8 and the nip roll 9. By cooling at the same time, the adhesion with the base material 7 is sufficiently strong, and there is very little oxidation on the heat-sealing surface, so it has excellent low-temperature sealing properties, there is no deterioration of heat-sealing properties over time, and the resin It becomes possible to produce a laminate with less odor due to oxidation and decomposition. In this way, in conventional coextrusion dies, the temperature is controlled by heating the die jaws on both sides to the desired temperature from the outside using heaters and thermocouples. There was no other choice but to reach an equilibrium state while holding it and settle down to a temperature between the set temperatures of the die jaws on both sides, so the high temperature resin A is cooled on the surface that contacts the partition plate in the manifold and resin flow path, while the low temperature Resin B is heated at the surface that contacts the partition plate in the manifold and resin flow path, and as a result, the temperature difference between the high temperature resin A and the low temperature resin B at the confluence point of both resins is as low as 100% before they flow into the die. However, in the present invention, a gas flow path is provided in the center of the partition plate over the entire width of the die, and the partition plate is connected to the substrate side and the opposite side of the substrate. The blocks are separated into blocks, and the blocks are insulated by flowing gas through the gas flow path, and each block is equipped with a heater and thermocouple to adjust the temperature of these blocks to the set temperature of the die jaw on each side. By heating and controlling the temperature, high-temperature resin A can also be heated to low-temperature resin B.
It becomes possible for resin to flow through the die and flow through a channel whose wall surface temperature is equal to the temperature of each resin until it reaches the confluence point, and as a result, the high temperature resin A and the low temperature resin B at the confluence point This makes it possible to maintain the temperature difference equal to the temperature difference immediately before flowing into the die.

The present invention further provides parts designed to blow exhaust gas onto one or both sides of the molten web to the gas exhaust ports at both ends of the coextrusion die having the above structure, and air to the gas flow path of the partition plate. It also includes a method of manufacturing a laminate by flowing an inert gas such as ozone or nitrogen and simultaneously blowing the exhaust gas onto one or both sides of a molten web.

The details will be explained below with reference to the attached drawings. Fourth
The figure shows surface α on the high temperature side of the molten web.

FIG. 5 shows a side view of a flat die according to the present invention with a part for blowing exhaust gas attached thereto, and FIG. 5 shows a front view of the die. Further, FIG. 6 shows a cross section taken along line AA' in FIG. 4. The following description will be made mainly using FIG. 6 and with reference to FIG. 4.

A gas selected from air, ozone, nitrogen and other inert gases is introduced into the die through the gas inlet 37 made in the partition plate 28 of the coextrusion die in FIG. Gas outlet 5 opened at both ends of
Gas is discharged from 1 and 53 to the outside of the die. Parts 52 and 54 for spraying the exhaust gas onto the molten web are attached to the exhaust ports 51 and 53 at both ends of the die, respectively, and the die exhaust gas is sent to the molten web from the air outlet 55 formed in the spraying parts. It will be sprayed on. When the gas used is air, ozone, or a mixture thereof, the gas is blown onto the surface α2 on the base material side of the molten web, and when nitrogen or other inert gas is used, the gas is blown onto the surface α2 on the side of the molten web opposite to the base material. Surface β. This involves spraying gas onto the area. When air is used, it is also possible to spray both sides of the molten web. In these cases, by introducing and flowing a gas flow into the gas flow path in the partition plate of the coextrusion die according to the present invention, the space between the partition plate procs on both sides of the gas flow path is insulated, and as a result, the die The high-temperature resin A and the low-temperature resin B introduced into the machine are laminated together at the same temperature as when they were introduced, extruded from the die exit, and this molten web is pressure-bonded to the base material, so that the adhesive strength is strong. This not only makes it possible to produce laminates with excellent heat-sealability and low odor, but also eliminates low-molecular-weight and decomposed resin products generated from the high-temperature molten web by blowing the exhaust gas from the die onto the molten web. Removes odor-causing substances from laminates by blowing away the
This makes it possible to dramatically reduce odor. When air is used for heat insulation of the die partition plate block and for spraying onto the molten web, the air may be sprayed only on the side of the base material of the molten web, or may be sprayed on both sides. In either case, it is effective in removing low molecular weight substances and decomposed substances of resin generated from the molten web, which are the cause of odor in laminates. Further, when ozone or a mixed gas of ozone and air is used instead of the air, it is sprayed onto the side surface of the base material of the molten web. This makes it possible to remove odor-causing substances and at the same time promote oxidation of the side surface of the molten web base material, thereby further improving the adhesive strength with the base material. Further, when nitrogen or other inert gas is used instead of the air, it is sprayed onto the side of the molten web opposite to the substrate. This makes it possible to remove odor-causing substances and at the same time further suppress oxidation on the side of the molten web opposite to the base material, more effectively reducing the odor of the laminate, and at the same time improving low-temperature sealing properties. This makes it possible to effectively prevent heat sealability from deteriorating over time. Naturally, the present invention is not limited to the two-layer coextrusion described above, but can also be used for three or more layer coextrusion.

The resins used in the present invention include polyolefin resins such as low density, medium density, and high density polyethylene, polypropylene, polybutene, poly-4-methylbenzene-1, and copolymers of ethylene and propylene, ethylene or propylene and butene-1, and copolymers of ethylene and propylene, ethylene or propylene and butene-1. , copolymers with α-olefins such as benzene-1, copolymers of ethylene and acrylic acid or methacrylic acid, or partially ionic crosslinked products thereof (ionomers), and ethylene and acrylic esters or methacrylic acid. Copolymers of esters, copolymers of ethylene and carboxylic acid vinyl esters such as vinyl acetate and vinyl propionate, and polyesters such as polyethylene terephthalate and polytetramethylene terephthalate, and 6-nylon, 6-6 nylon,
Polyamide resins such as copolymerized nylon can be used, but the material is not limited thereto, and any resin that can be formed by extrusion coating may be used. In addition, blends of two or more of the above resins, and slip agents, anti-blocking agents, antistatic agents, antifogging agents, antioxidants, ultraviolet absorbers, and flame retardants for the above resins or blends thereof. A resin composition to which , an adhesive, a filler, etc. are added can be used in the present invention. The plurality of resin layers in the coextruded web may be composed of the same or the same type of resin, or may be composed of different types of resin.

For example, even when a coextruded resin web is composed of two resin layers of the same or the same type, the interlayer adhesion can be improved by melt-extruding one layer located on the base material side at a high temperature and the other at a low temperature. As already mentioned above, a desirable combination with heat sealability can be obtained. In addition, the resin layer on the base material side of the coextruded web is made of ethylene copolymer or nylon, which is more desirable in terms of adhesiveness with the base material, and the resin layer on the opposite side to the base material is made of olefin resin, which is more desirable in terms of heat sealability. A person skilled in the art will readily understand that it can be a layer. In addition, the substrates used in the present invention include papers such as kraft paper, kurupata, bag-making paper, paperboard, aluminum foil, woven and non-woven fabrics of natural or synthetic fibers, cellophane, stretched and unstretched polypropylene films, stretched and unstretched polypropylene films, etc. It includes nylon film, stretched polyester vinyl film, and other resin films and sheets such as vinylon, polycarbonate, polyvinyl chloride, and polystyrene.

The base materials used in the present invention, such as paper, paperboard, aluminum foil, woven fabric, and non-woven fabric, may be coated with the molten resin web by extrusion as they are, but are more preferably preheated using a hot roll or an infrared heater. It is better to perform pre-treatment to improve adhesion, such as flame treatment, corona discharge treatment, etc. Furthermore, the various plastic films used in the present invention, such as cellophane, stretched polypropylene film, and stretched nylon film, need to be subjected to an anchor coating treatment to improve adhesion, which is used in ordinary extrusion coating processing. In some cases. Examples of anchor coating agents that can be used include alkyl titanate, polyethyleneimine, isocyanate, and other anchor coating agents. The temperature difference between the plurality of resin layers is determined in consideration of the type of resin so as to achieve the above-mentioned object of the present invention.

In many cases, within the range from the melting temperature to the decomposition temperature of the resin, the temperature difference between the two resin layers is at least 20°C or more, especially 40°C.
It is advantageous to set the temperature to be at least ℃. The invention is illustrated by the following example.

Example 1 Polyethylene A having an M of 14 g/10 minutes and a density of 0.923 g/Cnf was melt-kneaded in a first extruder, and the resin temperature was 325°C.
Then, it was fed into the base material side manifold 31 of the coextrusion T-die of the present invention shown in FIG.

At this time, the die body 1 25 and the base material side block 27 of the partition plate
The temperature was set at 325°C. On the other hand, Ml7g/10min,
Polyethylene B with a density of 0.920 g/CIll3 was melt-kneaded in a second extruder and fed into the manifold 32 on the opposite side from the base material of the main T-die at a resin temperature of 260° C. At this time, the base material of the die body 26 and the partition plate Block 28 on the opposite side
The temperature was set at 260°C. After the resin flows A and B from the two manifolds are combined at the confluence point 35, they are extruded from the die lip 36, and at the same time, they are extruded from the gas inlet 37 in the partition plate.
Air is introduced at a flow rate of 20Ncnf/Hr from the gas flow path 38, and is discharged from the outlets 51 and 53 at both ends of the die, via the conduits 52 and 54, and from the outlet 55 on the base material side of the molten web. While spraying onto the surface, this molten web was extrusion coated onto unbleached kraft paper which had been previously subjected to corona discharge treatment under conditions of a processing speed of 150 m/min, an air gap of 140 mm, and a total coating thickness of 20 μm.

At this time, the extrusion rates of the two extruders were adjusted so that the proportion of polyethylene A and polyethylene B in the total coating thickness of 20 μm was 50% and 50%, respectively. The measurement results of the physical properties of the obtained laminate are shown in Table 1 together with Comparative Example 1, which was subjected to extrusion coating using a conventionally known method.
It is recognized that the laminate obtained in this example has significantly less odor and has excellent heat seal strength. It was calculated from the following formula.

Adhesiveness [%] = B/A x 100 Note 2) Heat seal strength measurement conditions Seal pressure 3kg/Cm2 Seal time 1 second Peeling speed 300mm/min Peeling angle 90° Note 3) Odor comparison test A sensory test was conducted to determine the odor from polyethylene surfaces. It was found to be good with less odor. Shows the number of people.

Comparative Example 1 Polyethylene with an MI of 4 g/10 minutes and a density of 0.923 g/Cm3 was melt-kneaded using an extruder at a resin temperature of 325°C.
It is fed into a known T-die shown in Fig. 1 whose temperature is controlled at 5°C, extruded from the die exit as a molten web, and processed at a processing speed of 1 for unbleached kraft paper that has been previously subjected to corona discharge treatment.
50m/min, air gap 140mm, coat thickness 20
Extrusion coating was performed under μ conditions.

Table 1 shows the measurement results of the physical properties of the obtained laminate.
vinegar. Example 2 Polypropylene with an MFI of 20 g/10 minutes and a density of 0.91 was melt-kneaded in the first extruder at a resin temperature of 300°C, and the third
The base material side manifold of the coextrusion T-die of the present invention shown in the figure. - I sent it to Ludo 31.

At this time, the temperatures of the die body 25 and the substrate side block 27 of the partition plate were set at 300°C. On the other hand, the same polypropylene was used in a second extruder at a resin temperature of 260
The mixture was melted and kneaded at ℃ and fed into the manifold 32 on the opposite side of the T-die from the base material. In addition, at this time, Daibody 126
and the temperature of block 28 on the opposite side of the partition plate from the base material to 26
The temperature was set at 0°C. After the resin flows from the two manifolds are combined at a confluence point 35, they are extruded from a die lip 36,
At the same time, 20Nm3 of air is introduced from the gas inlet 37 in the partition plate.
/Hr, flows through the gas flow path 38, is discharged from the outlets 51 and 53 at both ends of the die, and passes through the conduits 52 and 54 from the outlet 55 to the surface of the base material side of the molten web. After spraying, this molten web was extruded and coated onto a biaxially stretched polypropylene film substrate having a thickness of 20 μm under conditions of a processing speed of 120 m/min, an air gap of 90 mm, and a total coating thickness of 20 μm.

At this time, the extrusion rates of the two extruders were adjusted so that the ratio of the high temperature polypropylene layer to the total coating thickness of 20 μm was 50% and the ratio of the low temperature layer was 50%. The measurement results of the physical properties of the obtained laminate are shown in Tables 2 and 3 together with Comparative Example 2, which was subjected to extrusion coating using a conventionally known method. It is recognized that the laminate obtained in this example is superior to products produced by conventional methods in both heat-sealability and hot-sealability. Note 1) Hot sealing property measurement method When heat sealing two laminates, attach a 45 g weight to one end of each, and after heat sealing, as soon as the seal bar is separated, the load is The peeling force was applied at an angle of 23°, and the peeling distance of the sealed portion was measured.

For heat sealing, the sealing pressure is 3. kg/Cnl2 sealing time was 0.5 seconds.

A smaller peel distance means better hot sealing properties.

Comparative Example 2 The same polypropylene used in Example 2 was melt-kneaded in an extruder at a resin temperature of 300°C, fed into a known T-die shown in Figure 1 whose temperature was controlled at 300°C, and melted from the die outlet. It is extruded as a web and processed at a processing speed of 12 on a biaxially stretched polypropylene film base material with a thickness of 20μ.
Extrusion coating was performed under processing conditions of 0 m/min, air gap of 90 m, and coating thickness of 20 μm.

The measurement results of the physical properties of the obtained laminate are shown in Table-2 and Table-
Not shown in 3. Example 3 Polyethylene with M17g/10 minutes and density 0.917g/CTn3 was melt-kneaded in the first extruder, and the resin temperature was 320°C.
The base material side ma of the coextrusion T-die according to the present invention shown in FIG.
I sent it to Nifold 31.

At this time, the die body 1 25 and the base material side block 27 of the partition plate
The temperature was set at 320°C. On the other hand, an ionomer made of Zn ions of an ethylene-methacrylic acid copolymer with an MI of 5 g/10 min was melt-kneaded in a second extruder, and the resin temperature was 3.
At 00°C, the manifold 32 on the opposite side of the T-die base material
I sent it to. At this time, the temperature of the die body 26 and the block 28 on the side opposite to the base material of the partition plate was set at 300°C. After combining these two resin streams at the confluence point 35,
The molten web is extruded from the die lip 36, and at the same time, nitrogen is introduced at a flow rate of 10 Nm3/Hr from the gas inlet 37 in the partition plate, flows through the gas flow path 38, and is discharged from the outlets 51 and 53 at both ends of the die. While spraying the molten web onto the surface opposite to the base material of
For the Al surface of the base material with E/A1 configuration, the processing speed was 120
m/min, air gap 140mm, total coat thickness 23μ
Extrusion coating was performed under the following conditions (inner polyethylene 13μ, ionomer 10μ) so that the polyethylene was in contact with the Al foil. It was found that the obtained laminate had sufficient adhesive strength, almost no odor, and was excellent in various heat sealing properties. Table 4 shows the heat sealing strength of this laminate, and Table 5 shows the hot sealing properties.

[Brief explanation of drawings]

FIG. 1 schematically shows a conventional extrusion coating die and a laminating section. FIG. 2 schematically shows a known in-die adhesive type two-layer coextrusion die and a laminate section. FIG. 3 schematically shows a coextrusion die and a laminating section according to the present invention. FIG. 4 is a side view schematically showing a coextrusion die according to the present invention with a spraying part for spraying exhaust gas from the die onto a molten web, and FIG. 5 is a front view thereof. It is. Furthermore, FIG. 6 shows a cross section taken along the line A-A'' in FIG.
, 33 and 34 are resin flow paths, 36 is a die land, 38 is a gas flow path, 41 and 42 are heating mechanisms, and 43 and 44 are temperature detection mechanisms, respectively.

Claims (1)

[Scope of Claims] 1. In a method of manufacturing a laminate by coextruding multiple layers of thermoplastic resin into a molten web through a coextrusion die and coating this onto a base material, the resin on the side in contact with the base material is The resin is maintained at a higher temperature than the resin on the side not in contact with the base material and introduced into the die, the flow path in the die for the resin on the side in contact with the base material is set to a high temperature, and the flow path in the die for the resin on the side not in contact with the base material is set to a low temperature. A laminate characterized in that a heat insulating space is provided between the resin channels in the die, a gas is flowed into the space, and coextrusion is performed by creating a temperature difference between the plurality of resin layers. How things are manufactured. 2. The method according to claim 1, characterized in that the exhaust gas from the heat insulating space is blown onto one or both sides of the molten web extruded from a die. 3. The method according to claim 2, wherein the gas passed through the heat insulating space is air, ozone, or a mixture thereof, and the exhaust gas is sprayed onto the surface of the molten web on the base material side. 4. The method according to claim 2, wherein the gas passed through the heat insulating space is an inert gas, and the exhaust gas is blown onto the surface of the molten web opposite to the base material. 5 The gas passed through the heat insulating space is air, and the exhaust gas is blown onto both sides of the molten web.
The method described in section. 6 Consisting of two die bodies and at least one partition member located between them, a plurality of resin channels are formed between each die body and the partition member or further between the partition members, and at the tip of the partition member In a coextrusion die in which a plurality of resin flow paths merge to form one die land at the bottom thereof, a heat insulating space that becomes a gas flow path is provided inside the partition member, and one end of the space is provided. gas inlet,
A coextrusion die for lamination, characterized in that gas discharge ports are provided at the other end, and separate temperature control mechanisms are provided in die portions partitioned by the gas flow paths. 7. The die according to claim 6, wherein a gas blowing mechanism for blowing gas onto one or both sides of the molten resin web from the coextrusion die is connected to the gas outlet.