JP5530965B2 - Laminated body - Google Patents

Description

  The present invention relates to a laminate comprising a polyester resin layer / adhesive layer / polypropylene layer obtained by coextrusion molding.

  Polyester resins have a high melting point, high rigidity, excellent gas barrier properties and aroma retention, and are therefore used as packaging bodies and containers in a wide range of fields such as food, medicine and IT. However, since the polyester resin has a high melting point, it is difficult to perform heat fusion, and heat fusion at a high temperature is necessary to obtain sufficient heat fusion strength.

  Currently, polyester resin packaging bags and containers on the market are made of polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer, etc. so that sufficient heat-sealing strength can be obtained even at low temperatures. Lamination with an ethylene copolymer or the like is performed. However, in applications where processing at a high temperature such as 121 ° C. is performed as a package or container such as heat treatment (retort treatment) or sterilization treatment, a laminate of ethylene resin is not suitable. Since the ethylene resin has poor heat resistance, deformation such as wrinkles may occur during the heat treatment, and the ethylene resin layer may melt during the heat treatment and affect the contents. . Therefore, in applications where heat treatment at a temperature equal to or higher than the melting point of the ethylene resin is used, instead of the ethylene resin, a polypropylene homopolymer, a propylene-ethylene random copolymer, a propylene-ethylene-butadiene copolymer, etc. A propylene terpolymer is used.

  A laminate of a polyester resin and an ethylene-based resin is obtained by coextrusion molding, lamination, or the like, and an adhesive layer and an adhesion process having sufficient adhesion with the polyester resin have been developed (for example, Patent Document 1: Patent No. 3539304). issue). According to Patent Document 1, a resin composition containing a polyethylene resin (A) and a specific epoxy group-containing ethylene copolymer (B) for laminating a heat seal layer on a substrate adherend such as PET is provided. It is described that it is suitable for extrusion lamination.

  On the other hand, a laminate of polyester resin and polypropylene is rarely obtained by coextrusion molding, and is mainly a laminate. However, since the laminate has problems such as toxicity of the residual solvent and complicated processes, co-extrusion without using a solvent and a simple process is preferable from the viewpoint of environmental consideration and cost. That is, it is desired to develop an adhesive layer that has high adhesive strength that enables co-extrusion molding of polyester resin and polypropylene and that maintains sufficient adhesive strength even after heat treatment.

  Patent Document 2: According to Japanese Patent No. 4588980, when a carboxyl-modified polyolefin and a modified polyethylene are each used alone as a material constituting a layer for adhering an aliphatic polyester resin layer and a polypropylene layer, the adhesive force that can be co-extruded is However, it is described that the adhesive strength is greatly reduced by the heat treatment, and the present inventors have confirmed the fact (see Comparative Example 1 of the present invention). Therefore, in Patent Document 2, a mixture of a carboxyl-modified polyolefin and an epoxidized polyolefin is proposed as an adhesive layer that can co-extrusion an aliphatic polyester resin and polypropylene and maintains adhesive strength even after heat treatment. However, since the blend composition of the mixture has two types of functional groups in a single layer, the functional groups react with each other in the adhesive layer, and there is a possibility of gelation, and there is a high possibility that foreign matter is generated. Appearance is impaired.

Japanese Patent No. 3539004 (Japanese Patent Laid-Open No. 9-111062) Japanese Patent No. 4588980 (Japanese Patent Laid-Open No. 2004-237543)

  Adhesive layer with high adhesive strength that enables co-extrusion molding of polyester resin and polypropylene, maintains high adhesive strength that causes cohesive peeling even after heat treatment, and has excellent appearance with no gel formation I found it. An object of the present invention is to provide a laminate by coextrusion molding of a polyester resin and polypropylene using the adhesive layer.

  The present inventors can use co-extrusion molding by using a propylene-ethylene block copolymer of 10 to 40% by weight and epoxidized polyethylene of 60 to 90% by weight as an adhesive layer, and after heat treatment Also found to maintain a high degree of adhesive strength.

  That is, the gist of the present invention is a laminate obtained by coextrusion molding, in which a polyester resin layer and a polypropylene layer are interposed via an adhesive layer, and the adhesive layer is a propylene-ethylene block copolymer 10-40. In the peel test after heat treatment at 121 ° C., the polyester resin layer and the polypropylene layer cause cohesive peel, and the adhesive strength in the peel test is 1000 gf. It exists in the laminated body characterized by being / 10 mm or more.

  Another gist of the present invention is a first polymerization step in which the propylene-ethylene block copolymer produces a propylene homopolymer or an ethylene-propylene random copolymer having an ethylene content of 0.5 to 6% by weight. And the laminate obtained in the second polymerization step in which propylene and ethylene are copolymerized in the presence of the product obtained in the first polymerization step.

  Moreover, the other summary of this invention exists in the said laminated body whose product obtained at the 1st polymerization process is 50 to 95 weight% with respect to a propylene-ethylene block copolymer.

  Moreover, the other summary of this invention exists in the said laminated body whose epoxy group content rate of epoxidized polyethylene is 1 to 30 weight% as a monomer containing an epoxy group.

  Moreover, the other summary of this invention exists in the said laminated body whose polypropylene layer is a propylene-ethylene random copolymer.

  Hereafter, the effect which this invention show | plays is demonstrated including an assumption with the action mechanism. The estimation includes parts that are not theoretically proved, but the present invention is included in the technical scope of the present invention without departing from the gist of the claims.

  Epoxidized polyethylene, which is one of the materials constituting the adhesive layer, exhibits adhesiveness with the polyester resin layer. The functional group on the polyester side (carboxyl group, hydroxyl group, etc.) such as the terminal functional group of the polyester resin reacts with the epoxy group of the epoxidized polyethylene to form a polyester-polyethylene copolymer, between the polyester resin layer and the epoxidized polyethylene. It is speculated that a strong chemical bond occurs.

  However, epoxidized polyethylene alone is insufficient in adhesion to the polypropylene layer. This is because epoxidized polyethylene and polypropylene are incompatible. Before heat treatment, the anchor effect due to the flexibility of the epoxidized polyethylene penetrates into the irregularities of the polypropylene layer and expresses sufficient adhesive strength, but the surface state is reconstructed by melting and crystallization of the epoxidized polyethylene during the heat treatment Therefore, it is assumed that the initial anchor effect is lost and the adhesive strength is greatly reduced (see Comparative Example 1 of the present invention).

  In order to maintain high adhesive strength even after heat treatment, it is necessary to connect between the epoxidized polyethylene and the polypropylene layer. Polypropylene that is compatible with the polypropylene layer is preferably used as the material to be connected, but propylene-ethylene random copolymers and propylene homopolymers have weak affinity with epoxidized polyethylene and do not exhibit good adhesive strength (this (See Comparative Examples 2 to 4 of the invention).

  Therefore, in order to increase the affinity between epoxidized polyethylene and polypropylene, the use of a propylene-ethylene block copolymer having a higher ethylene content in the propylene-based copolymer can provide a bridge between the epoxidized polyethylene and the polypropylene layer. It plays a role and provides high adhesive strength.

  Since the present invention is firmly adhered to both the polyester resin layer and the polypropylene layer even after heat treatment, in the peeling test of the polyester resin layer and the polypropylene layer, peeling does not occur at the bonding interface between the two, and instead of cohesive peeling. Show. This occurs because the adhesive strength to each layer is larger than the strength of the adhesive layer itself, and means that a high adhesive force is expressed. When the adhesive strength is low, interfacial peeling occurs where peeling occurs at the interface of either layer, which is not preferable as a laminate because the adhesive strength is insufficient.

  In the present invention, the epoxy resin is bonded to the polyester resin layer with the epoxidized polyethylene, and the epoxidized polyethylene and the polypropylene layer are connected with the propylene-ethylene block copolymer. Even a high degree of adhesive strength can be maintained. In addition, by using only an epoxy group as the functional group used for the adhesive layer, reaction within the adhesive layer was prevented, and no gel was generated, so that an adhesive layer having an excellent appearance could be found.

  In addition, since the heat treatment in the retort processing step and the sterilization treatment step of foods is usually performed at a high temperature of about 90 to 120 ° C., sufficient adhesion is achieved even after the heat treatment at 121 ° C. in the present invention. The criterion is that strength is maintained. In the peeling test, the polyester resin layer and the polypropylene layer cause cohesive peeling, and the adhesive strength in the peeling test can be 1000 gf / 10 mm or more, preferably 1500 gf / 10 mm or more.

<Polyester resin layer>
The polyester resin used in the polyester resin layer in the present invention can be used without particular limitation as long as it is a conventionally known polyester resin, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), PET. Aromatic polyester resins such as copolymer products (PETG) and aliphatics such as polyglycolic acid (including PGA and polyglycolide), polylactic acid (PLA), polytrimethylene carbonate (PTMC), polycaprolactone (PCL) A polyester resin is mentioned.

<Polypropylene layer>
If the polypropylene used for the polypropylene layer in this invention is a well-known thing used conventionally, it can be used without being specifically limited. Examples thereof include a propylene-ethylene random copolymer, a propylene homopolymer, a propylene-ethylene block copolymer, a propylene-α-olefin copolymer, and a propylene-ethylene-butene random copolymer. Examples of commercially available products include “NOVATEC PP” and “WINTEC” manufactured by Nippon Polypro.

<Adhesive layer>
(Propylene-ethylene block copolymer)
The propylene-ethylene block copolymer, which is one of the materials constituting the adhesive layer in the present invention, can be used without particular limitation as long as it is a conventionally known one. Examples of commercially available products include “NOVATEC PP” manufactured by Nippon Polypro Co., Ltd. and “ZELAS” manufactured by Mitsubishi Chemical Corporation.

  As a general method for producing a propylene-ethylene block copolymer, a first polymerization step (previous step) for producing a propylene polymer component (PP), followed by the presence of a product and a catalyst in the previous step, propylene-ethylene It is comprised from the 2nd superposition | polymerization process (following process) which manufactures a copolymer component (EP). In each step, a polymerization method such as a bulk polymerization method, a gas phase polymerization method, or a slurry polymerization method can be employed. In the present invention, a two-stage polymerization usually comprising a front stage and a rear stage is carried out, but in some cases, each stage can be further divided.

  The propylene polymer component (PP) is produced in the preceding polymerization step. In the presence of a metallocene catalyst or Ziegler catalyst, propylene homopolymerization or propylene / α-olefin copolymerization is carried out. That is, a propylene homopolymer or a copolymer of propylene and an α-olefin is formed in a single stage or multiple stages in an amount of 30 to 95% by weight, preferably 40 to 90% by weight, based on the total polymerization amount (the whole propylene-ethylene block copolymer). It is the process of forming so that it may correspond to. In addition, in this invention, alpha olefin is a general term for alpha olefins other than propylene including ethylene. PP is preferably a homopolymer of propylene or an ethylene-propylene copolymer having an ethylene content of 0.5 to 6% by weight, particularly 3% by weight or less. It is speculated that a specific ethylene / propylene copolymer is preferable from the relation of compatibility with epoxidized polyethylene described later.

(Epoxidized polyethylene)
Epoxidized polyethylene includes graft method epoxidized polyethylene and copolymer method epoxidized polyethylene, both of which are used in the present invention. Grafted epoxidized polyethylene is polyethylene in which an epoxy group is introduced by graft-modifying a polyethylene resin with a monomer having both an ethylenically unsaturated double bond and an epoxy group in one molecule. As such a grafting monomer, glycidyl acrylate, glycidyl methacrylate, or the like is used. The polyethylene resin used as a base is not limited to an ethylene homopolymer, and an ethylene-α-olefin copolymer can also be used.

The copolymerized epoxidized polyethylene is a copolymer obtained by directly copolymerizing the grafting monomer with a vinyl monomer such as ethylene or propylene.
The epoxy group content in the copolymer is 1 to 30% by weight, preferably 3 to 20% by weight, as a monomer containing an epoxy group. Similarly, the ethylene content in the copolymer is 50 to 95% by weight, preferably 60 to 90% by weight.

<Combination ratio of adhesive layer constituting resin>
In the present invention, a mixture of 10 to 40% by weight of a propylene-ethylene block copolymer and 60 to 90% by weight of epoxidized polyethylene is used. When the propylene-ethylene block copolymer is less than 10% by weight or when the epoxidized polyethylene is more than 90% by weight, the adhesive strength with the polypropylene layer after the heat treatment is lowered, which is not preferable. Moreover, when there are more propylene-ethylene block copolymers than 40 weight%, or when epoxidized polyethylene is less than 60 weight%, the adhesive force with the polyester resin layer after heat processing will fall. The propylene-ethylene block copolymer is preferably 35% by weight or less and the epoxidized polyethylene is 65% by weight or more, and more preferably, the propylene-ethylene block copolymer is 30% by weight or less, and the epoxidized polyethylene is 70% by weight or more.

<Method for mixing adhesive layer constituting resin>
The method of blending the adhesive layer constituting resin in the present invention is not particularly limited as long as it is a known mixing method. Examples include a melt kneading method and a dry blend method using a single screw or twin screw extruder.

<Method for producing laminate>
The laminate of the present invention includes a configuration in which a polyester resin layer, an adhesive layer, and a polypropylene layer are laminated in this order, and layers may be added as necessary. Each layer is obtained by melt extrusion through a respective extruder and coextrusion through a flat die or an annular die.

<Use of laminate>
If the laminated body of this invention is a film with comparatively thin thickness, it will be used as a film for packaging materials, such as a foodstuff, medical care, IT, miscellaneous goods, an industrial part, or it will be used for a packaging bag by making a bag shape. If the laminated body of this invention is a sheet | seat with comparatively thick thickness, it will be used as secondary processed goods, such as a tray and a cup. Examples of the hollow molded product include bottles of food, medicine, detergents, cosmetics, agricultural chemicals and the like.

[Example]
EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated further in detail, this invention is not limited to a following example, unless the summary is exceeded.

<Use resin>
Table 1 summarizes general names of polymers, trade names, physical properties / compositions of polymers, and the like for each resin used to constitute the polyester resin layer, the polypropylene layer, and the adhesive layer. Only the propylene-ethylene block copolymer (PEB) was not a commercial product, but an in-house polymerized product detailed in the following production examples was used.

<Method for evaluating laminate>
(Heat treatment)
The laminate is cut into a size of about 200 mm × 200 mm, placed in a high-temperature and high-pressure cooking sterilization tester (manufactured by Hisaka Seisakusho, RCS-40RTGN type), pressurized, and the ambient temperature is increased to 121 ° C. The temperature was held for 30 minutes. Then, it cooled to about 40 degreeC, this sample bag was taken out from the testing machine, and it conditioned for 24 hours in 23 degreeC / 50% RH atmosphere.

(Measurement of adhesive strength after heat treatment)
After a heat treatment, the polyester resin layer side of the laminate after the heat treatment was applied with a Pioneer cloth adhesive tape, and after the polyester resin layer was reinforced, a cutter was put in the adhesive layer, and the polyester resin layer and the polypropylene layer were peeled off by about 50 mm. . Then, it cut out in the strip | belt shape of a width of 10 mm, 50 mm peeled beforehand was set to the holding tool, the T-shaped peeling test was implemented, and the adhesive strength measurement was performed. A universal testing machine (Tensilon universal testing machine, manufactured by Orientec Co., Ltd.) was used as a measuring instrument, and the peeling rate was 500 mm / min. It can be judged that the adhesive strength is 1000 gf / 10 mm or more, and that the peel form is cohesive peel, it has a sufficiently strong adhesive force.

(Appearance judgment)
Those in which gel is generated at the time of molding have a poor appearance, and those having no gel are in good appearance. It was judged whether or not gel was generated visually.

[Production Example of Propylene-Ethylene Block Copolymer (PEB)]
(1) Preparation of prepolymerization catalyst (1-1) Chemical treatment of silicate Into a glass separable flask equipped with a 10-liter stirring blade, 3.75 liters of distilled water, followed by concentrated sulfuric acid (96%) 5 kg was added slowly. At 50 ° C., 1 kg of montmorillonite (Menzawa Chemical Co., Ltd. Benclay SL; average particle size = 25 μm, particle size distribution = 10-60 μm) was dispersed, heated to 90 ° C., and maintained at that temperature for 6.5 hours. After cooling to 50 ° C., the slurry was filtered under reduced pressure to recover the cake. 7 liters of distilled water was added to this cake to reslurry it, and then filtered. This washing operation was performed until the pH of the washing solution (filtrate) exceeded 3.5. The collected cake was dried at 110 ° C. overnight under a nitrogen atmosphere. The weight after drying was 707 g.

(1-2) Drying of silicate The silicate chemically processed previously was dried with a kiln dryer. Specifications and drying conditions are as follows.
Rotating cylinder: Cylindrical, inner diameter 50 mm, heating zone 550 mm (electric furnace)
Number of revolutions with lifting blade: 2 rpm, tilt angle: 20/520
Silicate supply rate: 2.5 g / min, gas flow rate: nitrogen 96 liters / hour Countercurrent drying temperature: 200 ° C. (powder temperature)

(1-3) Preparation of catalyst An autoclave having an internal volume of 16 liters having a stirring blade and a temperature control device was sufficiently substituted with nitrogen. 200 g of dry silicate was introduced, 1160 ml of mixed heptane and 840 ml of a heptane solution of triethylaluminum (0.60 M) were added, and the mixture was stirred at room temperature. After 1 hour, the mixture was washed with mixed heptane to prepare 2,000 ml of silicate slurry. Next, 9.6 ml of a heptane solution of triisobutylaluminum (0.71 M / L) was added to the silicate slurry prepared above and reacted at 25 ° C. for 1 hour. In parallel, 187 ml of (r) -dichloro [1,1′-dimethylsilylenebis {2-methyl-4- (4-chlorophenyl) -4H-azurenyl}] zirconium and 2,180 mg (0.3 mM) of mixed heptane Then, 33.1 ml of a heptane solution of triisobutylaluminum (0.71 M) was added and the mixture reacted at room temperature for 1 hour was added to the silicate slurry. After stirring for 1 hour, 5,000 ml was added with mixed heptane. Prepared.

(1-4) Preliminary polymerization / washing Subsequently, the temperature in the tank was raised to 40 ° C., and when the temperature was stabilized, propylene was supplied at a rate of 100 g / hour to maintain the temperature. After 4 hours, the supply of propylene was stopped and maintained for another 2 hours.
After completion of the prepolymerization, the remaining monomer was purged, the stirring was stopped and the mixture was allowed to stand for about 10 minutes, and then the supernatant was decanted to 2,400 ml. Subsequently, 9.5 ml of a heptane solution of triisobutylaluminum (0.71 M / L) and 5,600 ml of mixed heptane were further added, stirred for 30 minutes at 40 ° C., allowed to stand for 10 minutes, and then 5,600 ml of the supernatant was removed. It was. This operation was further repeated 3 times. When the component analysis of the final supernatant was performed, the concentration of the organoaluminum component was 1.23 mmol / L and the Zr concentration was 8.6 × 10 ⁻⁶ g / L, and the abundance in the supernatant with respect to the amount charged. Was 0.016%. Subsequently, 170 ml of a heptane solution of triisobutylaluminum (0.71 M / L) was added, followed by drying at 45 ° C. under reduced pressure. A prepolymerized catalyst containing 2.0 g of polypropylene per 1 g of catalyst was obtained.

(2) Production of Propylene-Ethylene Block Copolymer (PEB) Using the prepolymerized catalyst prepared as described above, PEB was produced according to the following procedure.
(2-1) First polymerization step A horizontal reactor (L / D = 6, internal volume 100 liters) having a stirring blade was sufficiently dried, and the inside was sufficiently replaced with nitrogen gas. While stirring at a rotation speed of 30 rpm in the presence of a polypropylene powder bed, 0.568 g / hr of the prepolymerized catalyst adjusted by the above method (as the amount of solid catalyst excluding the prepolymerized powder) in the upstream part of the reactor, Triisobutylaluminum was continuously fed at 15.0 mmol / hr. The monomer mixed gas is continuously reacted so that the reactor temperature is maintained at 65 ° C., the pressure is maintained at 2.1 MPaG, the ethylene / propylene molar ratio in the reactor gas phase is 0.07, and the hydrogen concentration is 100 ppm. It was made to distribute | circulate in a container and vapor phase polymerization was performed. The polymer powder produced by the reaction was continuously extracted from the downstream portion of the reactor so that the amount of the powder bed in the reactor was constant. At this time, the amount of the polymer extracted when the steady state was reached was 10.0 kg / hr.
When the propylene-ethylene random copolymer obtained in the first polymerization step was analyzed, the MFR was 6.0 g / 10 min and the ethylene content was 2.2% by weight.

(2-2) Second polymerization step The propylene-ethylene random copolymer extracted from the first polymerization step was continuously supplied to a horizontal reactor (L / D = 6, internal volume 100 liters) having a stirring blade. . While stirring at a rotational speed of 25 rpm, the temperature of the reactor is maintained at 70 ° C., the pressure is maintained at 2.0 MPaG, the ethylene / propylene molar ratio in the gas phase portion in the reactor is 0.453, and the hydrogen concentration is 330 ppm. A monomer mixed gas was continuously passed through the reactor to carry out gas phase polymerization. The polymer powder produced by the reaction was continuously extracted from the downstream portion of the reactor so that the amount of the powder bed in the reactor was constant. At this time, oxygen was supplied as an activity inhibitor so that the amount of polymer extracted was 17.9 kg / hr, and the polymerization reaction amount in the second polymerization step was controlled. The activity was 31.4 kg / g-catalyst.
Various analysis results of PEB (propylene-ethylene block copolymer) thus obtained are as follows.
Ethylene content in the first polymerization step = 2.2% by weight
Propylene-ethylene random copolymer amount obtained in the first polymerization step = 56% by weight
Ethylene content in the second polymerization step = 11% by weight
Propylene-ethylene random copolymer amount obtained in the second polymerization step = 44% by weight
Melting peak temperature (Tm) = 130 ° C.
Glass transition temperature = −8.6 ° C.
MFR = 6.0g / 10min

The above various analysis results are based on the following analysis methods.

(Tm: melting peak temperature)
The melting peak temperature is a value obtained with a differential scanning calorimeter (DSC manufactured by Seiko Co., Ltd.). Specifically, a sample amount of 5.0 mg is taken, held at 200 ° C. for 5 minutes, and then 10 ° C./40° C. It is a value obtained as a melting peak temperature when crystallization is performed at a temperature lowering speed of 1 minute and further melting is performed at a temperature increasing speed of 10 ° C./minute.

(Amount of propylene-ethylene random copolymer obtained in the first polymerization step and the second polymerization step)
This is a value obtained by temperature rising elution fractionation (TREF). Techniques for evaluating the crystallinity distribution of propylene-ethylene random copolymers and the like by temperature-temperature elution fractionation (TREF) are well known to those skilled in the art. For example, detailed measurement methods are shown in the following documents.
G. Glockner, J. et al. Appl. Polym. Sci. : Appl. Polym. Symp. 45, 1-24 (1990)
L. Wild, Adv. Polym. Sci. 98, 1-47 (1990)
J. et al. B. P. Soares, A .; E. Hamielec, Polymer; 36, 8, 1639-1654 (1995)
Specifically, in the present invention, the measurement is performed as follows.
A sample is dissolved in o-dichlorobenzene (containing 0.5 mg / ml BHT) at 140 ° C. to obtain a solution. This is introduced into a 140 ° C. TREF column, cooled to 100 ° C. at a rate of 8 ° C./min, subsequently cooled to −15 ° C. at a rate of 4 ° C./min, and held for 60 minutes. Then, a component of -15 ° C o-dichlorobenzene (containing 0.5 mg / ml BHT), which is a solvent, flows through the column at a flow rate of 1 ml / min, and is dissolved in -15 ° C o-dichlorobenzene in the TREF column. Is eluted for 10 minutes, and then the column is linearly heated to 140 ° C. at a heating rate of 100 ° C./hour to obtain an elution curve.
In the obtained elution curve, the first polymerization process component and the second polymerization process component show their elution peaks at the respective temperatures T (first polymerization process component) and T (second polymerization process component) due to the difference in crystallinity. Since the difference is sufficiently large, separation is possible at an intermediate temperature T (= {T (first polymerization step component) + T (second polymerization step component)} / 2).
Here, the integrated amount of the components eluting up to T is defined as the second polymerization step component amount (wt%), and the integrated amount of the portion eluting at T or more is defined as the first polymerization step component amount (wt%).

(Ethylene content of the propylene-ethylene random copolymer component obtained in the first polymerization step and the second polymerization step)
This is a value determined by NMR. The ethylene content of the first polymerization step component and the ethylene content of the second polymerization step component are separated from each other component by a temperature rising column separation method using a preparative separation apparatus, and the ethylene content of each component is determined by NMR. .
The temperature rising column fractionation method refers to a measurement method as disclosed in, for example, Macromolecules; 21, 314-319 (1988).

Specifically, the following method was used in the present invention.
<Temperature rising column separation>
A cylindrical column having a diameter of 50 mm and a height of 500 mm is packed with a glass bead carrier (80 to 100 mesh) and maintained at 140 ° C. Next, 200 ml of a sample o-dichlorobenzene solution (10 mg / ml) dissolved at 140 ° C. is introduced into the column. Thereafter, the temperature of the column is cooled to 0 ° C. at a rate of temperature decrease of 10 ° C./hour. After holding at 0 ° C. for 1 hour, the column temperature is heated to T (obtained for TREF measurement) at a heating rate of 10 ° C./hour and held for 1 hour. Note that the temperature control accuracy of the column through a series of operations is ± 1 ° C.
Next, while maintaining the column temperature at T, 800 ml of o-dichlorobenzene at the temperature T is allowed to flow at a flow rate of 20 ml / min to elute and recover components soluble at the temperature T existing in the column.
Next, the column temperature is increased to 140 ° C. at a rate of temperature increase of 10 ° C./min, left at 140 ° C. for 1 hour, and then 800 ml of o-dichlorobenzene as a solvent at 140 ° C. is flowed at a flow rate of 20 ml / min. Insoluble components at temperature T are eluted and collected.
The polymer-containing solution obtained by fractionation is concentrated to 20 ml using an evaporator and then precipitated in 5 times the amount of methanol. The precipitated polymer is collected by filtration and dried overnight in a vacuum dryer.

Measurement of ethylene content by ¹³ C-NMR The ethylene content of each of the first and second polymerization step components obtained by the above fractionation was measured by a proton complete decoupling method according to the following conditions. ¹³ C-NMR spectrum It is obtained by analyzing.
Model: GSX-400 manufactured by JEOL Ltd. or equivalent device (carbon nuclear resonance frequency of 100 MHz or more)
Solvent: o-dichlorobenzene / heavy benzene = 4/1 (volume ratio)
Concentration: 100 mg / ml
Temperature: 130 ° C
Pulse angle: 90 °
Pulse interval: 15 seconds Integration count: 5,000 times or more

  The spectrum may be assigned with reference to, for example, Macromolecules; 17, 1950 (1984). The spectral assignments measured under the above conditions are shown in Table 2. Symbols such as Sαα in the table are C.I. J. et al. According to the notation of Carman, Macromolecules; 10, 536-544 (1977), P represents a methyl carbon, S represents a methylene carbon, and T represents a methine carbon.

Hereinafter, when “P” is a propylene unit in a copolymer chain and “E” is an ethylene unit, six types of triads of PPP, PPE, EPE, PEP, PEE and EEE may exist in the chain. As described in Masahiro Kakugo, Macromolecules; 15, 1150-1152 (1982), the concentration of these triads and the peak intensity of the spectrum are linked by the following relational expressions (1) to (6).
[PPP] = k × I (Tββ) (1)
[PPE] = k × I (Tβδ) (2)
[EPE] = k × I (Tδδ) (3)
[PEP] = k × I (Sββ) (4)
[PEE] = k × I (Sβδ) (5)
[EEE] = k × {I (Sδδ) / 2 + I (Sγδ) / 4} (6)
Here, [] indicates the fraction of triads, for example, [PPP] is the fraction of PPP triads in all triads.
Therefore,
[PPP] + [PPE] + [EPE] + [PEP] + [PEE] + [EEE] = 1 (7)
It is. Further, k is a constant, I indicates the spectral intensity, and for example, I (Tββ) means the intensity of the 28.7 ppm peak attributed to Tββ.
By using the relational expressions (1) to (7) above, the fraction of each triad is obtained, and the ethylene content is obtained from the following expression.
Ethylene content (mol%) = ([PEP] + [PEE] + [EEE]) × 100
In addition, the propylene-ethylene random copolymer of the present invention contains a small amount of a propylene hetero bond (2,1-bond and / or 1,3-bond), thereby producing a minute peak shown in Table 3. .

In order to obtain an accurate ethylene content, it is necessary to include these peaks derived from heterogeneous bonds in the calculation, but it is difficult to completely separate and identify the peaks derived from heterogeneous bonds, and the amount of heterogeneous bonds is small. Therefore, the ethylene content of the present invention is obtained by using the relational expressions (1) to (7) as in the analysis of the copolymer produced with a Ziegler-Natta catalyst that does not substantially contain a heterogeneous bond. I will do it.
Conversion from mol% to wt% of ethylene content is performed using the following formula.
Ethylene content (% by weight)
= (28 * X / 100) / {28 * X / 100 + 42 * (1-X / 100)} * 100
(Here, X is the ethylene content in mol%.)

(MFR: Melt flow rate)
According to JIS K7210 A method condition M, test temperature: 230 ° C. nominal load: 2.16 kg Die shape: diameter 2.095 mm, length 8.00 mm.

(Glass transition point)
The glass transition point is a value determined by solid viscoelasticity measurement (DMA).
The sample used was cut into a strip of 10 mm width × 18 mm length × 2 mm thickness from a 2 mm thick sheet injection molded under the following conditions. The apparatus used was ARES manufactured by Rheometric Scientific. The frequency is 1 Hz. The measurement temperature was raised stepwise from −60 ° C., and the measurement was performed until the sample melted and became impossible to measure. The strain was performed in the range of 0.1 to 0.5%.
[Preparation of specimen]
Standard number: JIS-7152 (ISO294-1)
Molding machine: EC-20 injection molding machine manufactured by Toshiba Machine Molding machine set temperature: 80, 80, 160, 200, 200, 200 ° C from below the hopper
Mold temperature: 40 ℃
Injection speed: 200 mm / sec (speed in the mold cavity)
Holding pressure: 20 MPa
Holding time: 40 seconds Mold shape: Flat plate (thickness 2 mm, width 40 mm, length 80 mm)

[Example 1]
Polyethylene terephthalate as polyester resin layer; “RT543” manufactured by Nippon Unipet Co., Ltd., propylene-ethylene random copolymer as polypropylene layer; “FG4” manufactured by Nippon Polypro Co., Ltd., epoxidized polyethylene as adhesive layer; manufactured by Sumitomo Chemical Co., Ltd. A dry blend of 75% by weight of “BONDFAST 7M” and 25% by weight of PEB (propylene propylene-ethylene block copolymer) was used.
The polyester resin layer is melt extruded at a temperature of 290 ° C with an extruder having a screw diameter of 20 mmΦ, the polypropylene layer is melt extruded at a temperature of 230 ° C with an extruder having a screw diameter of 35 mmΦ, and the adhesive resin layer is extruded with an extruder having a screw diameter of 20 mmΦ. Melt extrusion was performed at a temperature of 220 ° C., and co-extrusion molding was performed by a T-die method to obtain a laminate of polyester resin layer (50 μm) / adhesive resin layer (20 μm) / polypropylene layer (50 μm).

[Comparative Example 1]
A laminate was obtained in the same manner as in Example 1 except that 100% by weight of “BONDFAST 7M” manufactured by Sumitomo Chemical Co., Ltd. was used as the adhesive layer constituting resin.

[Comparative Example 2]
Example 1 except that 75% by weight of “BONDAST 7M” manufactured by Sumitomo Chemical Co., Ltd. and propylene-ethylene random copolymer; 25% by weight of “FG4” manufactured by Nippon Polypro Co., Ltd. were used as the adhesive layer constituting resin. A laminate was obtained in the same manner.

[Comparative Example 3]
A laminate was obtained in the same manner as in Example 1 except that 50% by weight of “BONDFAST 7M” manufactured by Sumitomo Chemical Co., Ltd. and 50% by weight of “FG4” manufactured by Nippon Polypro were used as the adhesive layer constituting resin. .

[Comparative Example 4]
A laminate was obtained in the same manner as in Example 1 except that 25% by weight of “BONDAST 7M” manufactured by Sumitomo Chemical Co., Ltd. and 75% by weight of “FG4” manufactured by Nippon Polypro Co., Ltd. were used as the adhesive layer constituting resin. .

[Comparative Example 5]
A laminate as in Example 1 except that 50% by weight of “BONDFAST 7M” manufactured by Sumitomo Chemical Co., Ltd. and 50% by weight of PEB (propylene-ethylene block copolymer) are dry blended as the adhesive layer constituting resin. Got.

[Comparative Example 6]
Example 1 except that 75% by weight of “BONDAST 7M” manufactured by Sumitomo Chemical Co., Ltd. and hydrogenated styrene / butadiene rubber; 25% by weight of “DYNARON 1320P” manufactured by JSR were used as the adhesive layer constituting resin. Thus, a laminate was obtained.

[Comparative Example 7]
A laminate was obtained in the same manner as in Example 1, except that 50% by weight of “BONDAST 7M” manufactured by Sumitomo Chemical Co., Ltd. and 50% by weight of “DYNARON 1320P” manufactured by JSR were used as the adhesive layer constituting resin. .

[Comparative Example 8]
Sumitomo Chemical Co., Ltd. “BONDAST 7M” 75% by weight as an adhesive layer constituting resin and ethylene-α-olefin random copolymer; Mitsui Chemicals Co., Ltd. “TAFMER”
A laminate was obtained in the same manner as in Example 1 except that a dry blend of 25 wt% of “P-0280” was used.

[Comparative Example 9]
A laminate as in Example 1 except that 50% by weight of “BONDAST 7M” manufactured by Sumitomo Chemical Co., Ltd. and 50% by weight of “TAFMER P-0280” manufactured by Mitsui Chemicals are used as the adhesive layer constituting resin. Got.

[Comparative Example 10]
Sumitomo Chemical Co., Ltd. “BONDAST 7M” 75% by weight and propylene-ethylene random copolymer; Nippon Polypro Co., Ltd. “WINTECWFW4” 12.5% by weight as an adhesive layer constituting resin; and ethylene-α-olefin random copolymer; Japan A laminate was obtained in the same manner as in Example 1 except that a dry blend of 12.5% by weight of “KERNEL KS340T” manufactured by Polyethylene Co. was used.

[Comparative Example 11]
Other than using a dry blend of 50% by weight of “BONDAST 7M” manufactured by Sumitomo Chemical Co., Ltd., 25% by weight of “WINTEC WFW4” manufactured by Nippon Polypro, and 25% by weight of “KERNEL KS340T” manufactured by Nippon Polyethylene Co., Ltd. Obtained a laminate in the same manner as in Example 1.

  The laminates obtained in the above examples and comparative examples were subjected to heat treatment (retort treatment), and an adhesive strength measurement test was performed. The results are summarized in Table 4 and Table 5. The following matters can be understood from Tables 4 and 5.

  In Example 1, in the multi-layering of a general-purpose polyethylene terephthalate layer and a propylene-ethylene random copolymer layer, epoxidized polyethylene 75% by weight and in-house polymerized product “propylene-ethylene block copolymer” (PEB) 25% by weight are optimal. The adhesive layer is composed of the composition. Also in the peel test after the heat treatment, cohesive peeling was shown, and good adhesive strength exceeding 1600 gf / 10 mm was shown. Moreover, it did not generate | occur | produce a gel but was a favorable external appearance, and was a favorable performance as a laminated body.

  In Comparative Example 1, the adhesion to the polyester resin layer was sufficient, but the adhesive strength after the heat treatment was insufficient because the adhesive strength to the polypropylene layer was small, and the performance as a laminate was not satisfactory.

  In Comparative Example 2, the adhesive strength to the polyester resin layer is sufficient, but since a propylene-ethylene random copolymer having a low affinity with epoxidized polyethylene was used, the adhesive strength was weak and the adhesive strength after heat treatment was poor. It was sufficient and the performance was not satisfactory as a laminate.

  Since Comparative Examples 3-5, 9, and 11 had a small amount of epoxidized polyethylene, the adhesive strength to the polyester resin layer was weak, the adhesive strength after heat treatment was insufficient, and the performance was not satisfactory as a laminate. .

  Comparative Examples 6 and 7 were obtained when epoxidized polyethylene and hydrogenated styrene-butadiene rubber were used, and a large amount of gel was generated and could not be molded. It is presumed that a structural change occurred in the adhesive layer, and the epoxy groups of the epoxidized polyethylene reacted to generate a gel.

In Comparative Examples 8 and 10, the adhesive strength to the polyester resin layer is sufficient, but since the resin having low affinity with the epoxidized polyethylene was used, the adhesive strength was weak and the adhesive strength after the heat treatment was insufficient. The performance was not as satisfactory.
“TAFMER P-0280” (ethylene-α-olefin random copolymer) manufactured by Mitsui Chemicals, Ltd., “WINTEC WFW4” (propylene-ethylene random copolymer) manufactured by Nippon Polypro Co., Ltd., and “KERNEL KS340T” manufactured by Nippon Polyethylene The dry blend product of (ethylene / α-olefin random copolymer) was expected to have an action to connect the epoxidized polyethylene and the polypropylene layer and tried to improve the adhesive strength, but the effect was not seen. .

  Considering each of the above Examples and Comparative Examples in contrast, the laminate obtained from the combination satisfying the configuration of the present invention has sufficient adhesive strength even after heat treatment and is excellent in appearance. It is obvious.

The laminate obtained from the combination satisfying the configuration of the present invention is a laminate useful as a packaging bag or a container because it has sufficient adhesive strength even after heat treatment and has an excellent appearance.

Claims (5)

  A laminate obtained by co-extrusion molding, in which a polyester resin layer and a polypropylene layer are interposed via an adhesive layer, the adhesive layer comprising 10 to 40% by weight of a propylene-ethylene block copolymer and 60 to 60% of epoxidized polyethylene 90% by weight, in the peel test after heat treatment at 121 ° C., the polyester resin layer and the polypropylene layer cause cohesive peel, and the adhesive strength in the peel test is 1000 gf / 10 mm or more Laminated body.   A propylene-ethylene block copolymer is obtained in the first polymerization step to produce a propylene homopolymer or an ethylene-propylene random copolymer having an ethylene content of 0.5 to 6% by weight, and the first polymerization step. The laminate according to claim 1, wherein the laminate is obtained by a second polymerization step in which propylene and ethylene are copolymerized in the presence of a product and a catalyst.   The laminate according to claim 1 or 2, wherein the product obtained in the first polymerization step is 30 to 95% by weight based on the propylene-ethylene block copolymer.   The laminate according to any one of claims 1 to 3, wherein the epoxy group content of the epoxidized polyethylene is 1 to 30% by weight as a monomer containing an epoxy group.   The laminate according to any one of claims 1 to 4, wherein the polypropylene layer is a propylene-ethylene random copolymer.