Laminate

Abstract

To provide a laminate which prevents draw resonance even when molding speed is increased and a sheet is thinned while being given functionality by a functional layer.SOLUTION: A laminate includes a base material layer, and an extrusion laminate layer provided on at least one surface of the base material layer, wherein the extrusion laminate layer contains at least two layers of a support layer and a functional layer, and the support layer has a strain hardening index of 0.05-0.4 measured under the conditions of 230°C and strain speed of 1 sec-1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminate.

Background Art

[0002] As a method of forming a resin into a sheet shape, an extrusion molding method is known. The extrusion molding method is a method of forming by extruding a resin from a die (die) at the tip of an extruder. It includes not only a method of extruding one type of resin but also a co-extrusion molding method of simultaneously extruding a plurality of resins, and an extrusion lamination method of laminating while extruding a resin onto a base material. In such an extrusion molding method, the resin extruded from the die is taken in between rolls and formed into a sheet shape.

[0003] Here, from the viewpoints of recent environmental problem countermeasures and cost reduction, an increase in the molding speed and a thinning of the sheet are required. When trying to thin the sheet, the extrusion speed of the resin from the die must be reduced. Also, when increasing the molding speed, the take-up speed of the resin extruded from the die increases. At this time, if the extrusion speed is small and the take-up speed is large, a large load is applied to the extruded resin, and unevenness such that the resin before take-up after extrusion undulates, so-called draw resonance (surge), may occur.

[0004] Although draw resonance can be suppressed by reducing the molding speed while balancing the extrusion speed and the take-up speed, productivity decreases. For this reason, methods of improving on the material side have been attempted. For example, improving the fluidity of the resin or adding low-density polyethylene or long-chain branched polypropylene, etc. (Patent Documents 1 and 2) are known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Furthermore, when attempting to provide a layer with functions such as heat sealing on the surface of the laminate, the difficulty of improving draw resonance in the formation of such a layer increases. For example, in in-mold labels, since a resin with a narrow molecular weight distribution is used for the heat-sealing layer, molding defects such as draw resonance are likely to occur. If the fluidity of the resin is too high, molding defects are likely to occur during heat sealing, and in the technologies described in Patent Documents 1 and 2, there is a risk that the performance of the functional layer in the laminate, such as a decrease in adhesion, may deteriorate.

[0007] An object of the present invention is to provide a laminate that is less likely to generate draw resonance while imparting functionality by a functional layer, even when the molding speed is increased and the sheet is made thinner.

Means for Solving the Problems

[0008] As a result of intensive studies by the present inventors to solve the above problems, it has been found that draw resonance can be suppressed without inhibiting the performance of the functional layer by co-extruding a support layer with adjusted strain hardening degree together with the functional layer, and the present invention has been completed. That is, the present invention is as follows.

[0009] [1] A laminate comprising a base material layer and an extrusion laminate layer provided on at least one surface of the base material layer, The extrusion laminate layer includes at least two layers of a support layer and a functional layer, The support layer has a strain hardening degree of 0.05 to 0.4 measured under the conditions of 230 ° C. and a strain rate of 1 sec -1 Laminate. [2] The laminate according to [1], wherein the extrusion laminate layer is a co-extrusion laminate layer. [3] The support layer has a complex viscosity of 3η, which is three times the complex viscosity measured under the conditions of 230 ° C., a swing angle of 1%, and an angular frequency of 1 s -1 Value +The laminate according to [1] or [2], wherein [the value] is from 2000 to 15000. [4] The laminate according to any one of [1] to [3], wherein the support layer contains a polyolefin resin. [5] The laminate according to any one of [1] to [4], wherein the support layer contains a branched-chain polypropylene resin. [6] The laminate according to any one of [1] to [5], wherein the extrusion laminate layer is a stretched layer. [7] The laminate according to any one of [1] to [6], wherein the support layer contains a filler. [8] The laminate according to any one of [1] to [7], wherein the functional layer is a printing receptive layer. [9] The laminate according to any one of [1] to [8], wherein the functional layer is a heat seal layer. [Advantages of the Invention]

[0010] According to the present invention, there can be provided a laminate having a functional layer, which is less likely to generate draw resonance without inhibiting the performance of the functional layer even when the molding speed is increased and the sheet is made thinner. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

Figure 3

[0012] Hereinafter, the laminate of the present invention will be described in detail. The following is an example (representative example) of the present invention, and the present invention is not limited thereto.

[0013] [Laminate] The laminate of the present invention includes a base material layer and an extrusion laminate layer provided on at least one surface of the base material layer. The extrusion laminate layer includes at least two layers of a support layer and a functional layer. The support layer has a strain curing degree of 0.05 to 0.4 measured under the conditions of 230°C and a strain rate of 1 sec -1 -1. By having the strain curing degree of the support layer within the above specific range, a laminate in which draw resonance hardly occurs without inhibiting the performance of the functional layer can be obtained. When the extrusion laminate layer is provided on both surfaces of the base material layer, a laminate in which draw resonance hardly occurs without inhibiting the performance of the functional layers on both sides can be obtained, and the same or different functions can be imparted to the laminate.

[0014] In extrusion molding, it is advantageous from the viewpoint of suppressing draw resonance that the distance (air gap) from the die until it is laminated to the base material layer is small. On the other hand, when laminating the extrusion laminate layer to the base material layer, it is necessary to match the width of the extrusion laminate layer to the width of the base material layer, and changing the air gap is considered as a method. However, due to the neck-in phenomenon in which the film thickness at both side edges increases before the extruded resin reaches the base material layer as the air gap is changed, the width of the extrusion laminate layer may change. Therefore, it is difficult to change the air gap for the purpose of suppressing draw resonance. Therefore, by including a support layer having the above specific strain curing degree in the extrusion laminate layer, an approach to suppressing draw resonance is made from the material aspect of the extrusion laminate layer itself.

[0015] <Extrusion laminate layer> The extrusion laminate layer includes at least two layers of a support layer and a functional layer. By having a support layer separately from the functional layer, draw resonance and neck-in during lamination of the functional layer can be suppressed, and the moldability can be maintained well. The arrangement of the support layer and the functional layer is not particularly limited, and the support layer and the functional layer may be provided in this order on the base material layer, or the functional layer and the support layer may be provided in this order on the base material layer. Further, the extrusion laminate layer is provided on at least one surface of the base material layer, and may be provided on both surfaces of the base material layer.

[0016] FIGS. 1 and 2 are cross-sectional views of the laminate 1 in which the extrusion laminate layer 20 is provided on one surface of the base material layer 10. Furthermore, in the laminate 1 of FIG. 1, the support layer 21 and the functional layer 22 are provided in this order on one surface of the base material layer 10, and in the laminate 1 of FIG. 2, the functional layer 22 and the support layer 21 are provided in this order on one surface of the base material layer 10. FIG. 3 is a cross-sectional view of the laminate 1 in which the extrusion laminate layers 20A and 20B are provided on both surfaces of the base material layer 10. Furthermore, in the laminate 1 of FIG. 3, the support layer 21A and the functional layer 22A are provided in this order on one surface of the base material layer 10, and the support layer 21B and the functional layer 22B are provided in this order on the other surface.

[0017] The extrusion laminate layer is preferably a co-extrusion laminate layer. By co-extruding the functional layer and the support layer, even when a resin that is likely to cause molding defects such as draw resonance is used for the functional layer, the moldability can be improved without inhibiting the performance of the functional layer.

[0018] When the extrusion laminate layer is a co-extrusion laminate layer, by reducing the viscosity difference between the support layer resin and the functional layer resin, the generation of turbulent flow during lamination inside the die can be suppressed, and the performance of the functional layer can be prevented from being inhibited. The melt flow rate (M S : 230°C, 2.16 kg load) of the functional layer resin with respect to the melt flow rate (M F : 230°C, 2.16 kg load) of the support layer resin, the ratio (M F / M S ) is preferably from 0.1 to 10, more preferably from 0.2 to 5, still more preferably from 0.4 to 3, and particularly preferably from 0.5 to 2 from the above viewpoints.

[0019] From the perspective of enabling the addition of various functions, the extrusion laminate layer is preferably a stretched layer. The number of stretching axes is preferably 1 or more, and the extrusion laminate layer is preferably a uniaxially stretched layer or a biaxially stretched layer.

[0020] The thickness of the extrusion laminate layer is preferably 5 μm or more, more preferably 8 μm or more. Also, from the perspective of enabling the addition of various functions while making the entire laminate thinner, it is preferably 400 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less. When the extrusion laminate layer is a stretched layer, the thickness of the extrusion laminate layer is preferably within the range obtained by dividing the above thickness by the stretching ratio.

[0021] The extrusion laminate layer is preferably a stretched layer. By stretching, it is easy to obtain a thickness dimension and stiffness that are excellent in various printing suitability as printing paper. Also, the variation in the total thickness dimension of the printing paper is alleviated, and it is easy to obtain a uniform thickness. Furthermore, it is easy to obtain a flat surface. When not containing a filler, the transparency of the sheet is also improved. Additionally, when the strain curing degree of the support layer is within the above specific range, the viscosity of the thin film part increases during stretching, and a sheet with a more uniform thickness can be obtained. Also, the stretching may be performed in at least one direction. On the other hand, from the perspective of preventing surface breakage, the extrusion laminate layer is preferably an unstretched layer.

[0022] <Support layer> The support layer is provided to suppress draw resonance and neck-in during lamination of the functional layer and to maintain good formability.

[0023] The support layer has a strain curing degree of 0.05 to 0.4 measured under the conditions of 230°C and a strain rate of 1 sec -1 -1. The strain hardening degree is an index representing the strength during melting and stretching. When the strain hardening degree is large, the viscosity improves near the take-up roll, and as a result, draw resonance during extrusion molding can be suppressed. Also, when the strain hardening degree is large, the melt tension improves, and as a result, neck-in during extrusion molding can be suppressed. On the other hand, by controlling the strain hardening degree to be small, the non-uniformity of stress dispersion between the air gaps (the space from the die outlet to the take-up roll) due to excessive tension increase near the take-up roll can be eliminated, and the deterioration of draw resonance and breakage during molding can be suppressed. From this perspective, the strain hardening degree is 0.05 or more, preferably 0.08 or more, and more preferably 0.15 or more. Also, the strain hardening degree is 0.4 or less, preferably 0.37 or less, and more preferably 0.34 or less.

[0024] The specific measurement method of the strain hardening degree will be described in the examples.

[0025] The support layer has a complex viscosity measured under the conditions of 230°C, vibration angle 1%, and angular frequency 1 s -1 multiplied by 3 to obtain a value 3η + preferably in the range of 2000 to 15000. The complex viscosity is an index representing the viscosity ratio. In general resins, the higher the complex viscosity, the lower the fluidity tends to be. When 3η + is equal to or greater than the above lower limit value, molding defects such as sharkskin due to the generation of turbulent flow during extrusion can be suppressed. When 3η + is equal to or less than the above upper limit value, the increase in resin pressure during extrusion and the opening of the lip of the die outlet due to this can be suppressed, and there is a tendency to suppress draw resonance. From this perspective, 3η + is preferably 2000 or more, more preferably 4000 or more, and particularly preferably 5000 or more. Also, 3η + is 15000 or less, preferably 14000 or less, and more preferably 13000 or less.

[0026] The complex viscosity is obtained by measuring using a viscoelasticity measuring device under the conditions of 230°C, vibration angle 1%, and angular frequency 1 s -1 ​Note that since the complex viscosity is measured at 230°C as described above, the resin is in a molten state at such a temperature. Therefore, the complex viscosities of the resin composition for forming the support layer and the support layer are the same value.

[0027] The support layer is obtained by molding the resin composition. The resin used for the support layer is preferably a thermoplastic resin, and is not particularly limited, but from the viewpoint of mechanical strength, a polyolefin resin is preferred, and a polypropylene resin or a polyethylene resin is particularly preferred. In addition, in order to make the strain curing degree of the support layer within the above-specified range, the resin composition preferably contains a resin having strain curability. Strain curability means the property that the viscosity increases due to strain. Specific examples of the resin having strain curability include resins having branched chains and ultra-high molecular weight resins.

[0028] Examples of the polyolefin resin having a branched chain include long-chain branched polypropylene resins, low-density polyethylene resins (density 0.910 to 0.930 g / cm 3 ), low-molecular-weight polyethylene ionomer resins, and the like. Whether it is long-chain branched can be confirmed by calculating the branching index g'. The branching index g' can be calculated from the following formula. When the branching index g' is a value smaller than 1, it can be determined that it has a long-chain branched structure. The long-chain branched structure is distinguished from the short-chain branched structure formed by copolymerization with an α-olefin such as 1-butene. Branching index g' = Vbr / Vlin Vbr represents the intrinsic viscosity of the resin having a long-chain branched structure, and Vlin represents the intrinsic viscosity of a linear resin having the same molecular weight as the resin having a long-chain branched structure. Examples of the ultra-high molecular weight polyolefin resin include ultra-high molecular weight polyethylene resins. Particularly, long-chain branched polypropylene-based resins are preferable from the viewpoint of heat resistance, and polypropylene produced by macromer copolymerization using a combination of metallocene catalysts is particularly preferable. Such polypropylene may be synthesized or commercially available products may be used, and Waymax MFX3, Waymax MFX6, Waymax MFX8, etc. manufactured by Japan Polypropylene Corporation are preferably used. Resins having strain hardening properties can also be used as a mixture of two or more kinds.

[0029] The content of the resin having strain hardening properties in the support layer is preferably 1 to 30% by mass, more preferably 3 to 25% by mass, and still more preferably 5 to 20% by mass. By being in such a range, the strain hardening degree of the resin composition becomes a sufficient range, the moldability becomes good, and the melt tension does not become too high, and there is a tendency to reduce the deterioration of draw resonance and breakage during molding.

[0030] In addition to the strain-curable resin, the support layer may further contain other resins. Examples of the other resins include linear polyolefin resins such as high-density polyethylene, medium-density polyethylene, linear low-density polyethylene resins, linear polypropylene resins, and polymethyl-1-pentene; polyamide resins such as nylon-6, nylon-6,6, nylon-6,10, and nylon-6,12; thermoplastic polyester resins such as polyethylene naphthalate and aliphatic polyesters; and thermoplastic resins such as polycarbonate, atactic polystyrene, syndiotactic polystyrene, and polyphenylene sulfide. It is preferable that the above other resins include linear polyolefin resins, and more preferably include linear polypropylene resins. These can also be used as a mixture of two or more. In order to make the strain curing degree of the support layer within a predetermined range, the content of the above other resins is preferably 50 parts by mass or more, more preferably 100 parts by mass or more, and even more preferably 200 parts by mass or more with respect to 100 parts by mass of the strain-curable resin. Also, the content of the above other resins is preferably 2000 parts by mass or less, more preferably 1000 parts by mass or less, and even more preferably 500 parts by mass or less with respect to 100 parts by mass of the strain-curable resin. Also, when the extrusion laminate layer is a stretched layer, the support layer preferably further contains a high-density polyethylene resin. The high-density polyethylene resin is a polyethylene resin having a density of 0.940 to 0.960 g / cm 3 . By the support layer further containing a high-density polyethylene resin, the ductility can be improved, and breakage and uneven thickness during stretching can be suppressed. The content of the high-density polyethylene resin in the support layer is preferably 10 parts by mass or more, more preferably 20 parts by mass or more with respect to 100 parts by mass of the strain-curable resin. Also, the content of the high-density polyethylene resin in the support layer is preferably 500 parts by mass or less, more preferably 300 parts by mass or less, and even more preferably 100 parts by mass or less in order to make the strain curing degree of the support layer within a predetermined range.

[0031] The support layer preferably further contains a filler. Thereby, the proportion of the plastic can be relatively reduced. In addition, since fine pores with the filler as the core are formed inside the support layer to form a porous layer, the stiffness, whiteness or opacity of the laminate can be adjusted, and the texture of paper can be imparted to the laminate. On the other hand, when the support layer contains a filler, molding defects are more likely to occur than when it does not contain a filler. Therefore, the support layer may not contain a filler. However, in the laminate according to the present embodiment, the laminate can be manufactured without causing molding defects even when the support layer contains a filler. Examples of fillers that can be used include inorganic fillers or organic fillers, etc., and these can be used alone or in combination.

[0032] Examples of inorganic fillers include inorganic fine powders such as calcium carbonate, calcined clay, talc, titanium oxide, barium sulfate, zinc oxide, magnesium oxide, diatomaceous earth, silicon oxide, composite inorganic fine powders having aluminum oxide or hydroxide around the core of the inorganic fine powder, hollow glass beads, etc. Among them, calcium carbonate, calcined clay or diatomaceous earth is preferable because they are inexpensive and can form many pores by stretching. Note that examples of calcium carbonate include heavy calcium carbonate and light calcium carbonate.

[0033] As the organic filler, a resin having a melting point or glass transition point higher than that of the resin used in the support layer and being incompatible with the resin used in the support layer is preferable from the viewpoint of pore formation. Specific examples of the organic filler include, for example, polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate, polyethylene naphthalate, polystyrene, a homopolymer or copolymer of (meth)acrylic acid ester, melamine resin, polyethylene sulfite, polyimide, polyethyl ether ketone, polyphenylene sulfide, a homopolymer of cyclic olefin, a copolymer (COC) of cyclic olefin and ethylene, etc. When using a crystalline polyolefin resin as the resin for the support layer, as the organic filler, in particular, polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate, polyethylene naphthalate, polystyrene, a homopolymer of cyclic olefin and a copolymer (COC) of cyclic olefin and ethylene, etc. are preferably used.

[0034] The average particle size of the filler is preferably 0.01 μm or more, more preferably 0.1 μm or more, still more preferably 1 μm or more, and preferably 25 μm or less, more preferably 15 μm or less, still more preferably 10 μm or less, even more preferably 5 μm or less, and particularly preferably 3 μm or less. When the average particle size is 0.01 μm or more, the filler does not aggregate in the resin and is uniformly dispersed, so the draw resonance tends to be good. Also, when it is 25 μm or less, the entanglement of the molecular chains of the resin is not inhibited, and in addition to the good draw resonance, it tends to be able to suppress the appearance defect due to surface breakage when stretched.

[0035] Also, when the support layer contains a filler, from the viewpoint of suppressing the inhibition of the effect by the strain-curable resin, the aspect ratio of the filler is preferably 1 to 5, more preferably 1 to 3, and still more preferably 1 to 2. Examples of such filler shapes include spherical and irregular shapes.

[0036] The content of the filler in the support layer (the total amount when using an inorganic filler and an organic filler in combination) is preferably 3% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, since it is easy to impart opacity etc. to the film. Also, from the viewpoint of improving the draw resonance by resin formulation and maintaining the dispersion state of the filler, it is preferably 60% by mass or less, more preferably 55% by mass or less, still more preferably 50% by mass or less.

[0037] <Other components> The support layer can optionally contain known additives as required. Examples of the additives include known auxiliaries such as dispersants, antioxidants, light stabilizers, ultraviolet absorbers, crystal nucleating agents, antiblocking agents, plasticizers, slip agents such as fatty acid amides, dyes, pigments, mold release agents, and flame retardants.

[0038] The dispersant is an optional component compounded from the viewpoint of enhancing the uniformity of the dispersion of the inorganic filler powder. The dispersant may be present as a surface treatment agent for the inorganic filler. Examples of the dispersant include silane coupling agents, higher fatty acids such as oleic acid and stearic acid, metal soaps, polyacrylic acid, polymethacrylic acid, or salts thereof. Among these, especially when the support layer is a stretched layer, higher fatty acids or metal soaps are preferred from the viewpoint of suppressing appearance defects due to aggregation of the inorganic filler or surface breakage caused by foreign matter, and at least one compound selected from the group consisting of an acid having a hydrocarbon group with 8 to 20 carbon atoms, an ester of the acid, and a salt thereof is more preferred. The content of the dispersant in the support layer is preferably 0.01% by mass or more, more preferably 1% by mass or more, because sufficient dispersibility can be easily obtained. Also, the content of the dispersant is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, because aggregation of the inorganic filler powder can be easily avoided.

[0039] From the viewpoint of moldability, the thickness of the support layer is preferably 2 μm or more, more preferably 4 μm or more. Also, from the viewpoint of enabling the addition of various functions while making the entire laminate thinner, the thickness is preferably 380 μm or less, more preferably 180 μm or less, and even more preferably 90 μm or less. When the support layer is a stretched layer, the thickness of the support layer is preferably within the range obtained by dividing the above thickness by the stretching ratio.

[0040] Also, from the viewpoint of moldability, the thickness of the support layer is preferably 30% or more, more preferably 40% or more, based on the thickness of the entire extrusion laminate layer.

[0041] <Functional layer> The functional layer is a layer provided to impart various functions to the laminate, and examples thereof include a printing layer, a print-receiving layer, a heat-sealing layer, a gas barrier layer, an adhesive layer for in-mold forming, and the like.

[0042] The printing layer is a layer composed of characters, images, etc. formed with printing ink or toner, and as printing methods, various printing methods such as offset printing, inkjet method, electrophotography (laser) method, thermal recording method, thermal transfer method, etc. can be used. Conventionally known printing layers can be used by known methods.

[0043] The print-receiving layer is a layer that functions as an ink or toner receiving layer when providing the printing layer. Depending on the properties of the print-receiving layer, various characteristics such as the abrasion resistance, antistatic property, printability, water resistance, storage stability, etc. of the printing layer can be adjusted. Conventionally known print-receiving layers can be used by known methods.

[0044] The heat-sealing layer is a layer mainly composed of a thermoplastic resin and has the function of an adhesive for joining the base material layer and other resins. The heat-sealing layer contains a thermoplastic resin having a melting point lower than that of the thermoplastic resin contained in the base material layer. The melting point of the thermoplastic resin contained in the heat-sealing layer is preferably 10°C or more lower than that of the thermoplastic resin contained in the base material layer, more preferably 20°C or more lower, and even more preferably 30°C or more lower. Also, the melting point of the thermoplastic resin contained in the heat-sealing layer is preferably lower than that of the thermoplastic resin contained in the support layer.

[0045] Suitable thermoplastic resins for the heat-sealing layer include resins such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid alkyl ester copolymer (the alkyl group has 1 to 8 carbon atoms), and metal salts of ethylene-(meth)acrylic acid copolymer (such as salts with metals selected from Zn, Al, Li, K, Na). Further, as the thermoplastic resin, there may be mentioned random copolymers or block copolymers of α-olefins obtained by copolymerizing at least two or more comonomers selected from α-olefins having 2 to 20 carbon atoms in the molecule. Among these, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-based copolymers copolymerized using a metallocene catalyst are preferred. The thermoplastic resin used for the heat-sealing layer may be used alone or in combination of two or more.

[0046] The resin used for the functional layer is not particularly limited, but from the viewpoint of enhancing the interlayer strength with the support layer, polyolefin-based resins are preferred. Further, the functional layer may contain a filler.

[0047] From the viewpoint of function manifestation, the thickness of the functional layer is preferably 1 μm or more, more preferably 3 μm or more. Also, from the viewpoint of enabling the addition of various functions while making the entire laminate thin, it is preferably 250 μm or less, more preferably 120 μm or less, and even more preferably 60 μm or less. When the functional layer is a stretched layer, the thickness of the functional layer is preferably within the range obtained by dividing the above thickness by the stretching ratio.

[0048] <Base material layer> The base material layer is provided as a support of the laminate. As the resin constituting the base material layer, from the viewpoint of mechanical strength, polyolefin-based resins are preferred, and from the viewpoint of film-forming properties, polypropylene-based resins or polyethylene-based resins are preferred.

[0049] The base material layer may contain a filler. Examples of the filler that can be used include the inorganic filler or organic filler, etc. used for the above-described support layer.

[0050] The base material layer can further contain a heat stabilizer (antioxidant), a light stabilizer, a dispersant, a lubricant, or a nucleating agent, etc., as necessary.

[0051] The base material layer may have a single-layer structure or a multilayer structure of two or more layers. By multi-layerization, it becomes possible to impart various functions such as mechanical properties, writing properties, abrasion resistance, or suitability for secondary processing to the base material layer.

[0052] From the viewpoints of mechanical strength and transportability during printing, the thickness of the base material layer is preferably 10 μm or more, more preferably 15 μm or more, and is preferably 800 μm or less, more preferably 400 μm or less, and particularly preferably 150 μm or less.

[0053] The base material layer is preferably a stretched layer. By stretching, it is easy to obtain a thickness dimension and stiffness that are excellent in various printing suitability as printing paper, and the variation (uneven thickness) in the total thickness dimension of the printing paper is alleviated and a uniform thickness is easily obtained, and furthermore, a flat surface is easily obtained. Also, the stretching may be in at least one direction.

[0054] In the laminate of the present invention having the above configuration, the occurrence of draw resonance in extrusion molding is suppressed. In extrusion molding, the larger the ratio of the take-up speed to the extrusion speed (take-up speed / extrusion speed = draft ratio), the easier it is for draw resonance to occur, and if the molding speed is reduced in an attempt to suppress this draw resonance, the productivity decreases.

[0055] The thickness of the laminate is preferably 1000 μm or less, more preferably 800 μm or less, still more preferably 500 μm or less, and particularly preferably 200 μm or less, from the viewpoints of reducing manufacturing costs and reducing waste plastic. Also, from the viewpoints of high-speed formability and strength, it is preferably 25 μm or more. The thickness of the laminate is measured, for example, in accordance with JIS K7130:1999 "Plastics - Films and Sheets - Methods of Measuring Thickness".

[0056] [Manufacturing Method] The laminate of the present invention can be manufactured by known methods. Examples of the manufacturing method of the laminate include cast molding, calender molding, rolling molding, inflation molding, etc., in which a resin composition containing a resin and optional components is melted and extruded into a sheet shape by a T-die, I-die, etc. connected to a screw-type extruder.

[0057] As a manufacturing method of the laminate, after forming a base material layer and an extrusion laminate layer respectively, they may be laminated. Alternatively, using ordinary methods such as a multilayer die method using a feed block and a multi-manifold, or an extrusion lamination method using a plurality of dies, the forming and lamination of the base material layer and the extrusion laminate layer can be carried out in parallel. Furthermore, it is preferable that the extrusion laminate layer is laminated by co-extrusion of a support layer and a functional layer.

[0058] Each layer constituting the laminate may be an unstretched film or a stretched film stretched in one axial direction or two axial directions. From the viewpoints of the formability of pores and the improvement of mechanical strength when containing a filler, a stretched film is preferable.

[0059] For example, by stretching in one axial direction or two axial directions at a temperature lower than the melting point of the thermoplastic resin used for each layer constituting the laminate, a stretched film in which all layers are stretched in one axial direction or two axial directions can be obtained.

[0060] In addition, in the laminate, an extrusion laminate layer can be laminated on a base material layer stretched in the uniaxial direction, and by stretching uniaxially in the axial direction different from that of the base material layer, a uniaxial / biaxial stretched film can also be obtained. The base material layer and the extrusion laminate layer may be stretched and laminated individually, but it is simpler and the production cost can be reduced by stretching them together after laminating each layer, which is preferable.

[0061] Examples of the stretching method include stretching between rolls using the peripheral speed difference of a roll group, clip stretching using a tenter oven, etc. According to stretching between rolls, the stretching ratio can be arbitrarily adjusted, and it is easy to obtain the desired rigidity, opacity, smoothness, glossiness, etc., which is preferable.

[0062] The stretching temperature is usually 5 to 60°C lower than the melting point of the resin. When using two or more resins, the stretching temperature is preferably usually 5°C or more lower than the melting point of the resin with the largest blending amount.

Examples

[0063] The present invention will be described more specifically below with reference to examples and comparative examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the production examples and examples can be appropriately changed without departing from the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[0064] The materials used below are shown. <Polyolefin resin> Propylene homopolymer A: Manufactured by Nippon Polypropylene Corporation, trade name: Novatec PP FY6, MFR (230°C, 2.16 kg load): 2.5 g / 10 min Propylene homopolymer B: Manufactured by Nippon Polypropylene Corporation, trade name: Novatec PP MA3, MFR (230°C, 2.16 kg load): 11 g / 10 min Propylene homopolymer C: Manufactured by Nippon Polypropylene Corporation, trade name: Waymax MFX3, MFR (230°C, 2.16 kg load): 9.0 g / 10 min, branching index: 0.85 Propylene homopolymer D: Manufactured by Nippon Polypro Co., Ltd., trade name: Waymax MFX6, MFR (230 °C, 2.16 kg load): 2.5 g / 10 min, branching index: 0.88 High-density polyethylene: Manufactured by Nippon Polyethylene Co., Ltd., trade name: Novatech HD HJ381, MFR (190 °C, 2.16 kg load): 11 g / 10 min Metallocene polyethylene: Manufactured by The Dow Company, trade name: Engage 8401, MFR (ASTM D1238): 30 g / 10 min, density 0.885 g / cm 3 , melting point (JIS-K7121): 81 °C

[0065] <Filler> Calcium carbonate A: Manufactured by Bihoku Powder Chemical Industry Co., Ltd., trade name: Softon 1800, average particle diameter: 1.25 μm, aspect ratio: 1.78 Calcium carbonate B: Manufactured by Bihoku Powder Chemical Industry Co., Ltd., trade name: Softon 3200, average particle diameter: 0.7 μm Calcium carbonate C: Manufactured by Maruo Calcium Co., Ltd., trade name: YM30, average particle diameter: 0.3 μm, fatty acid surface treatment Calcium carbonate D: Manufactured by Bihoku Powder Chemical Industry Co., Ltd., trade name: BF200, average particle diameter: 5 μm

[0066] [Resin compositions 1-1 to 1-9, 2-1 to 2-2] Resin compositions 1-1 to 1-8 for the support layer of the extrusion laminate layer with the compositions shown in Table 1 were prepared. Resin composition 1-9 for the functional layer of the extrusion laminate layer with the compositions shown in Table 1 was prepared. Resin compositions 2-1 to 2-2 for the base material layer with the compositions shown in Table 1 were prepared.

[0067] <3η + > Using a viscoelasticity measuring device (MCR301 manufactured by Anton Paar), at 230 °C, oscillation angle 1%, angular frequency 1 s -1 Under the conditions of, the complex viscosity (Pa·s) of resin compositions 1-1 to 1-8 was measured and tripled to obtain 3η + was calculated.

[0068] <Degree of Strain Hardening> Using an ARES-2000 manufactured by Rheometric Scientific, at 230 °C and a strain rate of 1 sec -1 The elongational viscosity (ηe + ) of resin compositions 1-1 to 1-8 was measured under the conditions of. When plotting the elongational viscosity against time, ηe was plotted within the range where the slope was constant among strain amounts of 1 to 4 + (ε1) was extracted at three or more points. Using the following relational expression, the non-linear parameter (λn) at each plot was calculated. λn = ηe + (ε1) / 3η + ηe + (ε1): Elongational viscosity at a strain rate of 1 (sec -1 ) 3η + : Three times the complex viscosity (Pa·s) calculated above Using the non-linear parameter (λn), the degree of strain hardening (SH) was calculated by the following formula. SH = dLn(λn) / dε

[0069] The evaluation results of resin compositions 1-1 to 1-8 are shown in Table 1.

[0070]

Table 1

[0071] [Example 1] The resin composition 2-1 for the base material layer shown in Table 1 was melt-kneaded using an extruder set at 250 °C, then extruded into a sheet shape, and cooled to about 60 °C to obtain an unstretched sheet. Next, this unstretched sheet was reheated using a hot roll so that the temperature of the sheet surface became 150 °C, and then longitudinally stretched 4.8 times using the peripheral speed difference of the roll group, and cooled using a cooling roll until the temperature of the sheet surface became about 60 °C to obtain a base material layer made of a longitudinally stretched resin sheet. Next, the resin composition 1-1 for the support layer and the resin composition 1-9 for the functional layer were each melt-kneaded with two extruders having a diameter of 40 mmφ set at 250°C, and then co-extruded in a sheet form at a speed of 2.5 m / min from a T-die set at 250°C while being laminated on one side of the base material layer, and this was taken up by a cooling roll at a speed of 30 m / min (air gap 60 mm) and cooled to about 60°C to obtain a laminated sheet having a three-layer structure of base material layer / support layer / functional layer. Next, after cooling this laminated sheet to 60°C, reheating it to 150°C, stretching it 9 times in the width direction of the sheet, and then annealing it at 165°C. Thereafter, it was cooled to 60°C, the ears were slit to obtain a laminate having a total thickness of 50 μm (base material layer / support layer / functional layer) with a three-layer structure (biaxially stretched / uniaxially stretched / uniaxially stretched).

[0072] [Example 2] A laminate was obtained in the same manner as in Example 1 except that the thicknesses of the support layer and the functional layer were as shown in Table 2.

[0073] [Example 3] A laminate was obtained in the same manner as in Example 1 except that the thicknesses of the support layer and the functional layer were as shown in Table 2.

[0074] [Example 4] A laminate having a total thickness of 162 μm (base material layer / support layer / functional layer) with a three-layer structure (biaxially stretched / unstretched / unstretched) was obtained in the same manner as in Example 1 except that the laminated sheet was reheated to 150°C and stretching in the width direction and annealing treatment were not performed.

[0075] [Example 5] A laminate was obtained in the same manner as in Example 1 except that the resin composition for the support layer was changed to 1-2.

[0076] [Example 6] A laminate was obtained in the same manner as in Example 5 except that the resin composition for the base material layer was changed to 2-2.

[0077] [Example 7] A laminate was obtained in the same manner as in Example 1 except that the resin composition for the support layer was changed to 1-3.

[0078] [Example 8] A laminate was obtained in the same manner as in Example 1, except that the resin composition for the support layer was changed to 1-4.

[0079] [Example 9] A laminate was obtained in the same manner as in Example 1, except that the resin composition for the support layer was changed to 1-5.

[0080] [Example 10] A laminate was obtained in the same manner as in Example 1, except that the resin composition for the support layer was changed to 1-8.

[0081] [Example 11] A laminate having a five-layer structure of functional layer / support layer / substrate layer / support layer / functional layer with a total thickness of 64 μm (substrate layer / support layer / functional layer) in a five-layer structure (uniaxial stretching / uniaxial stretching / biaxial stretching / uniaxial stretching / uniaxial stretching) was obtained in the same manner as in Example 1, except that the resin composition 1-1 for the support layer and the resin composition 1-9 for the functional layer were co-extruded and laminated in a sheet form on both sides of the substrate layer.

[0082] [Comparative Example 1] A laminate was obtained in the same manner as in Example 1, except that the resin composition for the support layer was changed to 1-6.

[0083] [Comparative Example 2] A laminate was obtained in the same manner as in Example 1, except that the resin composition for the support layer was changed to 1-7.

[0084] [Comparative Example 3] A laminate was obtained in the same manner as in Example 1, except that no support layer was provided and the thickness of the functional layer was as shown in Table 2.

[0085] [Limiting draft ratio] In the co-extrusion molding of the above support layer and functional layer, the extrusion speed (m / min) was decreased, and the draw ratio (take-up speed / extrusion speed) was calculated from the extrusion speed at which draw resonance occurred, and this value was defined as the limiting draw ratio. The draw resonance was determined by visually observing the sway of the end of the sheet and measuring the thickness unevenness in the flow direction of the collected sheet. A sheet with a thickness deviation of 20 μm or more was regarded as having draw resonance. Limiting draw ratio (A to D are qualified) A: 14.5 or more B: 13 or more and less than 14.5 C: 11.5 or more and less than 13 D: 10 or more and less than 11.5 E: 8 or more and less than 10 F: less than 8

[0086] <Neck-in> In the co-extrusion molding of the above support layer and functional layer, the sheet width at an extrusion speed of 2.5 m / min was measured. The reduction amount from the die width of 230 mm was defined as the neck-in amount. Neck-in amount (A or B is qualified) A: less than 24 mm B: 24 mm or more and less than 32 mm C: 32 mm or more and less than 35 mm D: 35 mm or more

[0087] <Surface breakage> 1 m of the laminate 2 The number of foreign matters visually confirmable in it and the number of surface breakages caused by the foreign matters were measured. Number of surface breakages (○ or △ is qualified) ○: less than 2 △: 2 or more and less than 6 ×: 6 or more

[0088] <Thickness deviation> The thickness of the obtained extrusion-molded sheet was measured in accordance with JIS K7130:1999 "Plastics - Films and Sheets - Method for Measuring Thickness", and the difference between the maximum value and the minimum value was defined as the thickness deviation.

[0089] The evaluation results of Examples 1 to 11 and Comparative Examples 1 to 3 are shown in Table 2.

[0090]

Table 2

[0091] From the above results, the laminated bodies of Examples 1 to 11 in which Resin Compositions 1-1 to 1-5 and 1-8 with both the strain curing degree and 3η within predetermined ranges were respectively used for the support layer in the extrusion laminate layer all had a high limiting draft ratio, a small amount of neck-in, excellent moldability, and were capable of exhibiting heat sealability by the functional layer. + Also, in Examples 2 and 3, although the limiting draft ratio decreased compared to Example 1 with a high support layer A thickness ratio, both the limiting draft ratio and the amount of neck-in could be judged as qualified. Since the extrusion laminate layer of the laminated body of Example 4 was an unstretched layer, uneven thickness occurred, but both the limiting draft ratio and the amount of neck-in could be judged as qualified. In the laminated bodies of Examples 5, 6, 7, 8, and 10, resonance was inhibited by containing a filler in the support layer, and although the limiting draft ratio decreased compared to Example 1 without the filler, both the limiting draft ratio and the amount of neck-in could be judged as qualified. In Example 8, the dispersibility was improved by using a surface-treated filler, and the limiting draft ratio was good. Since the laminated body of Example 9 used Resin Composition 1-5 containing high-density polyethylene for the support layer in the extrusion laminate layer, the resonance decreased but it could be judged as qualified, the ductility was improved, the neck-in characteristics were good, and uneven thickness could also be suppressed. The laminated body of Example 11 was an example manufactured by changing the number of stretching axes of the extrusion laminate layer, but both the limiting draft ratio and the amount of neck-in could be judged as qualified.

[0092] ​On the other hand, the laminate of Comparative Example 1 using the resin composition 1-6 with a strain curing degree greater than a predetermined range for the support layer in the extrusion laminate layer had a low limiting draft ratio. Also, the laminate of Comparative Example 2 using the resin composition 1-7 with a strain curing degree of less than 0.01 for the support layer in the extrusion laminate layer, and the laminate of Comparative Example 3 having no support layer and a single-layer structure for the extrusion laminate layer had a low limiting draft ratio, a large amount of neck-in, and poor formability.

Explanation of Reference Numerals

[0093] 1... laminate, 10... base material layer, 20, 20A, 20B... extrusion laminate layer, 21, 21A, 21B... support layer, 22, 22A, 22B... functional layer

Claims

1. A laminate comprising a base material layer and an extrusion laminate layer provided on at least one surface of the base material layer, wherein the extrusion laminate layer includes at least two layers of a support layer and a functional layer. The support layer has a strain curing degree of 0.05 to 0.4 measured under the conditions of 230°C and a strain rate of 1 sec －１ The laminate is such that the strain curing degree is 0.05 to 0.4 measured under the conditions of 230°C and a strain rate of 1 sec

2. The laminate according to Claim 1, wherein the extrusion laminate layer is a co-extrusion laminate layer.

3. The support layer has a complex viscosity measured under the conditions of 230 °C, a swing angle of 1%, and an angular frequency of 1 s －１ multiplied by 3 to obtain a value 3η ＋ which is 2000 to 15000, and the laminate according to claim 1 or 2.

4. The laminate according to Claim 1 or 2, wherein the support layer contains a polyolefin resin.

5. The laminate according to Claim 1 or 2, wherein the support layer contains a polypropylene resin having a branched chain.

6. The laminate according to Claim 1 or 2, wherein the extrusion laminate layer is a stretched layer.

7. The laminate according to Claim 1 or 2, wherein the support layer contains a filler, and the average particle diameter of the filler is 0.01 to 25 μm.

8. The laminate according to Claim 1 or 2, wherein the functional layer is a printing receptive layer.

9. The laminate according to Claim 1 or 2, wherein the functional layer is a heat seal layer.

10. The laminate according to Claim 1 or 2, wherein the support layer contains high density polyethylene.

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