JP5160028B2 - Resin composition for polypropylene heat-shrinkable film, polypropylene heat-shrinkable film using the same, and use thereof - Google Patents

Description

  The present invention relates to a resin composition for polypropylene-based heat-shrinkable films, a polypropylene-based heat-shrinkable film using the same, and uses thereof. More specifically, the present invention relates to a polypropylene-based heat-shrinkable film resin composition having an improved heat shrinkage rate, particularly a low-temperature shrinkage rate, a shrink label film using the same, and an application utilizing the characteristics thereof.

In recent years, heat-shrinkable films have been used as exteriors to prevent the contents from fouling, falsification, and display, or for the integrated packaging of products for improved transportation efficiency and sales promotion, and the contents of packaging items. It is widely used for packaging for avoiding direct impact of goods, tight packaging, and label packaging that also serves to protect glass bottles or plastic bottles and display products.
These heat-shrinkable shrink films differ in required quality depending on the application, but are often used as exteriors, and those having excellent transparency and gloss are preferred. In addition, the higher the shrinkage rate, the more preferable it is because the packaging can be in close contact with various forms.

Among these, the label for PET bottles is used for the purpose of protecting bottles, improving design properties, various displays related to products, etc., and its use is expanding.
In this application, most PET bottles have no heat resistance, so it is necessary to shrink at low temperatures. Also, various bottle shapes are supported, and a beautiful finish that adheres not only to the trunk but also to the neck is obtained. Therefore, a high shrinkage rate is preferred, and it is required to be excellent in transparency and gloss in order to improve the appearance of the product.

Therefore, a label made of polyvinyl chloride, which is excellent in transparency and gloss and has high shrinkage properties, has been used for these applications. However, polyvinyl chloride has recently been replaced with other resins due to the concern that chlorine gas may be generated during incineration.
The most widely used label is a label made of polystyrene or polyethylene terephthalate having shrinkage characteristics close to that of polyvinyl chloride and excellent appearance.
However, with the recent promotion of recycling, problems with these labels have become apparent. That is, the PET bottle is separated and collected and recycled to various products, but the label is printed, so that it needs to be separated from the bottle. If the label is mixed, the quality at the time of reproduction will be reduced, so it is necessary to remove the label from the bottle and recycle it. The collector needs to remove it one by one. This is because polystyrene and polyethylene terephthalate have a small difference in specific gravity with PET bottles, so that floating separation is difficult. Specific gravity separation is industrially very easy. Especially, PET bottles have a specific gravity of about 1.3 or more, while specific gravity of 1.0 or less can be separated by water. However, since the separation can be performed extremely efficiently, the burden at the time of collection can be greatly reduced.

In such a situation, polypropylene has a specific gravity as low as about 0.9 and can be floated and separated from water by PET, so that its use is expected, but it has a problem that low-temperature shrinkage is insufficient. It was.
Various proposals have been made so far for the purpose of improving the low temperature shrinkability. For example, a method of adding a petroleum resin and / or terpene resin and a copolymer of ethylene and an α-olefin having 4 or more carbon atoms to an ethylene / propylene random copolymer has been proposed (Patent Document 1). The performance is still inadequate, and a large amount of petroleum resin and / or terpene resin needs to be added to improve the shrinkage characteristics, which increases the specific gravity and makes floating separation difficult. there were.
On the other hand, the present inventors have proposed a method of adding a specific alicyclic hydrocarbon resin to a specific propylene / α-olefin random copolymer for the purpose of improving low temperature shrinkage and specific gravity (Patent Document 2). Although it has been proposed so far, there is a strong demand from the market for further improvement in heat shrinkage characteristics, and further improvement in heat shrinkage characteristics has been demanded.

JP 63-304032 (Claims and lower right column on page 1) JP 2002-60566 A (summary)

  The heat-shrinkable film requires transparency, gloss, and excellent shrinkage, and the heat-shrinkable film for PET bottles, which has recently been in great demand, is particularly required to have low-temperature shrinkage. Under these circumstances, the alicyclic carbonization is reduced to improve the shrinkage characteristics by improving the polypropylene resin as the base, and to reduce the specific gravity for collecting and using the PET bottle. Realizing a resin composition for polypropylene heat-shrinkable film with improved heat shrinkage rate, especially low-temperature shrinkage rate for hydrogen resin, and using this resin composition provides a heat-shrinkable shrink film with excellent shrinkage properties. In particular, it is intended to exhibit excellent features in labeling PET bottles.

  The inventors of the present invention have previously had solid component viscoelastic characteristics, elution characteristics in temperature-elevated elution fractionation, etc., with specific component composition, molecular weight distribution, composition distribution, etc., by multistage polymerization using a metallocene catalyst. A series of research and development on a propylene-ethylene block copolymer is also carried out, and an application has been filed as a previous invention (Japanese Patent Application No. 2003-371458 and others), but the above-mentioned polypropylene-based heat-shrinkable film is the subject of the present invention. In addition, in order to effectively use the propylene ethylene block copolymer, which is a block type reactor TPO, as a film material, the prior invention is used as a propylene- Using ethylene block copolymer as a raw material, excellent film appearance such as transparency and gloss The low-temperature shrinkage required as a shrink film for PET bottles has been improved, and the low-temperature shrinkage rate has been improved in fewer alicyclic hydrocarbon resins in order to reduce the specific gravity for PET bottle recovery and utilization. Aiming at the realization of polypropylene resin, we decided to seek a new method.

  In order to find such a technique, the present inventors use a metallocene catalyst, and in the first step, more propylene-ethylene random copolymer component containing propylene alone or a small amount of ethylene in the second step than in the first step. In the propylene-ethylene block copolymer obtained by sequentially polymerizing propylene-ethylene random copolymer components containing ethylene, the component composition of each copolymer, ethylene content, crystallinity distribution and molecular weight distribution, Various considerations are made regarding solid viscoelastic properties or adoption as a composition component with other resins, and the above-described problems of the present invention are solved in the process of conducting various trials under these conditions. The possible requirements can be newly recognized and the present invention has been created.

  Those basic requirements recognized as described above include, in the second step, a propylene-ethylene random copolymer component containing propylene alone or a small amount of ethylene in the first step using a metallocene catalyst. In the propylene-ethylene block copolymer obtained by sequentially polymerizing a propylene-ethylene random copolymer component containing more ethylene than in the first step, the component composition and ethylene content of each copolymer are specified, combined The tan δ curve is characterized as the melt flow rate and solid viscoelastic properties of the propylene-ethylene block copolymer, and the specific propylene-ethylene block copolymer component (A) and the specific alicyclic hydrocarbon are further characterized. By using a resin composition comprising the resin component (B), the heat shrinkage rate, particularly the low temperature shrinkage, is improved. The polypropylene heat-shrinkable shrink film using this composition is found to be superior in shrinking properties compared to conventional ones and can be compatible with both shrinking properties and low specific gravity. I was able to find out.

Specifically, in the first step, propylene alone or propylene-ethylene random copolymer component (A1) having an ethylene content of 7 wt% or less is 30 to 95 wt%, and in the second step, 3 to 20 wt% more than component (A1). 70 to 5 wt% of the propylene-ethylene random copolymer component (A2) containing ethylene in a block copolymer, and in the block copolymer, the melt flow rate (MFR) is in the range of 0.1 to 30 g / 10 min. In the temperature-loss tangent (tan δ) curve obtained by solid viscoelasticity measurement (DMA) for improving the transparency of the film, the tan δ curve has a single peak below 0 ° C., and As another resin component, an alicyclic hydrocarbon resin having a specified softening point is used.
Such numerical definition is based on experimental verification and the like, and can be confirmed also by the comparison of Examples and Comparative Examples described later.

  The polypropylene-based heat-shrinkable film of the present invention is also used in the form of a multilayer film, and incidentally, the molecular weight obtained by gel permeation chromatography (GPC) measurement, other resin components, and the like are also defined.

  In the above, the background of the creation of the present invention and the configuration and characteristics of the invention have been described in general. If the overall configuration of the present invention is viewed here, the present invention comprises the following invention unit groups. Note that the invention described in [1] is a basic invention, and [2] the following invention adds an additional requirement to the basic invention or shows an embodiment.

[1] A resin composition containing 50 to 95 wt% of a propylene-ethylene block copolymer component (A) and 50 to 5 wt% of an alicyclic hydrocarbon resin component (B), wherein the component (A) is: A resin composition for a polypropylene-based heat-shrinkable film, which satisfies the conditions (Ai) to (A-iii) and the component (B) satisfies the following condition (Bi).
(Ai) 30 to 95 wt% of propylene-ethylene random copolymer component (A1) having propylene alone or ethylene content of 7 wt% or less in the first step using the metallocene catalyst, and component (A1) in the second step It is a propylene-ethylene block copolymer obtained by successively polymerizing 70 to 5 wt% of a propylene-ethylene random copolymer component (A2) containing 3 to 20 wt% more ethylene than (A-ii) ) Melt flow rate (MFR; 2.16 kg 230 ° C.) is in the range of 0.1-30 g / 10 min (A-iii) Temperature-loss tangent (tan δ) curve obtained by solid viscoelasticity measurement (DMA) The tan δ curve has a single peak at 0 ° C. or lower (Bi) the softening point temperature is from 110 ° C. to 160 ° C. [2] (A) is characterized by satisfying the following conditions (A-iv), polypropylene heat-shrinkable shrink film resin composition described in [1].
(A-iv) A component amount W (Mw ≦ 5,000) of 5,000 or less in the molecular weight of the block copolymer obtained by gel permeation chromatography (GPC) measurement is 0. [3] Polypropylene by the propylene-ethylene block copolymer described in [1] or [2], wherein the component (B) satisfies the following condition (B-ii): Resin composition for heat-shrinkable film.
(B-ii) One or more alicyclic hydrocarbon resins selected from petroleum resins, terpene resins, rosin resins, coumarone indene resins, and hydrogenated derivatives thereof [4] [1] to [3] A polypropylene heat-shrinkable film formed by a propylene-ethylene block copolymer described in any one of the above, and a polypropylene heat-shrinkable film stretched at least in a uniaxial direction.
[5] Polypropylene multilayer heat shrinkage comprising at least one layer made of the resin composition for polypropylene heat shrinkable films described in any one of [1] to [3] and stretched at least in a uniaxial direction. Sex shrink film.
[6] In the multilayer film described in [5], a layer made of the cyclic olefin-based resin composition component (C) satisfying the following characteristics (Ci) is laminated on one or both surfaces, A polypropylene-based multilayer heat-shrinkable shrink film formed by stretching at least in a uniaxial direction.
(Ci) Cyclic olefin compounds and / or cyclic olefin compounds comprising a cyclic olefin compound and / or ethylene having a glass transition temperature of 40 to 100 ° C. and an MFR (2.16 kg 260 ° C.) of 10 to 50 g / 10 min. A cyclic olefin-based resin selected from a polymer obtained by ring-opening polymerization of a cyclic olefin-based resin mainly containing a hydrogenated product thereof, a density of 0.88-0.93 g / cm ³ , MFR 0 to 50 wt% linear low density polyethylene polymerized with a metallocene catalyst (2.16 kg 190 ° C.) of 1.0 to 10 g / 10 min
[7] The polypropylene-based (multilayer) heat-shrinkable film described in any one of [4] to [6] is 1.0 to 1.5 times in the longitudinal direction by the tenter-type sequential biaxial stretching method, and the transverse direction. A polypropylene heat-shrinkable shrink film obtained by being stretched and molded by 3.0 to 10.0 times.
[8] A film for shrink labels, wherein the polypropylene (multilayer) heat-shrinkable film described in any of [4] to [7] is used for shrink label applications.

  The polypropylene-based heat-shrinkable shrink film of the present invention is excellent in film appearance such as transparency and glossiness, and particularly has improved low-temperature shrinkage required as a shrink film for PET bottles. In order to reduce the specific gravity, the low-temperature shrinkage rate is improved in fewer alicyclic hydrocarbon resins.

  The present invention is a polypropylene heat-shrinkable film resin composition comprising a propylene-ethylene block copolymer (A) satisfying specific conditions and an alicyclic hydrocarbon resin component (B) satisfying specific conditions, and The present invention relates to a polypropylene-based heat-shrinkable shrink film imparted with heat-shrinkability by stretching in at least one direction using the resin composition and its use.

1. Basic composition of resin composition for polypropylene-based heat-shrinkable film The resin composition for polypropylene-based heat-shrinkable film of the present invention has a propylene-ethylene block copolymer (A) of 50 to 95 wt% satisfying specific conditions and specific conditions. It consists of 50 to 5 wt% of the alicyclic hydrocarbon resin component (B) that satisfies the above.
The propylene-ethylene block copolymer component (A) is a propylene-ethylene random copolymer component (A1) of 30 to 95 wt% with propylene alone or ethylene content of 7 wt% or less in the first step using a metallocene catalyst. Propylene-ethylene block copolymer obtained by sequential polymerization of propylene-ethylene random copolymer component (A2) containing 3 to 20 wt% more ethylene than component (A1) in the second step. In the temperature-loss tangent (tan δ) curve obtained by solid viscoelasticity measurement (DMA), the tan δ curve is single below 0 ° C. And has excellent transparency and improved shrinkage characteristics.
The alicyclic hydrocarbon resin component (B) has a softening point temperature of 110 ° C. or higher and 160 ° C. or lower, and is a component for improving low temperature shrinkage characteristics.
Each component needs to have the following requirements in order to satisfy the object of the present invention.

2. Configuration of Propylene-Ethylene Block Copolymer (A) (1) Basic Rules The propylene-ethylene block copolymer (A) used in the polypropylene heat-shrinkable film in the present invention is a first metallocene catalyst. 30 to 95 wt% of propylene-ethylene random copolymer component (A1) having propylene alone or ethylene content of 7 wt% or less in the step, and propylene-ethylene random containing 3 to 20 wt% more ethylene than the first step in the second step It can be obtained by successively polymerizing 70 to 5 wt% of the copolymer component (A2).
Such a propylene-ethylene block copolymer is commonly called a so-called block copolymer, but is in a blended state of component (A1) and component (A2), and both are bonded by polymerization. It is not what you have.

(2) Component (A1) (2-1) Ethylene content E in component (A1) E (A1)
Component (A1) produced in the first step has a relatively high melting point, that is, a relatively thick lamellar thickness, a crystalline propylene homopolymer, or a propylene-ethylene random copolymer having an ethylene content of 7 wt% or less. Must be a polymer. When the ethylene content exceeds 7 wt%, the melting point becomes too low and the shrinkage characteristics deteriorate, and the heat resistance is lowered. Therefore, the ethylene content is 7 wt% or less, preferably 6 wt% or less.
In addition, although component (A1) changes also with the quantity of a component (A2) or a component (B), shrinkage | contraction rate may improve, so that a lamella thickness is thick, On the other hand, it is difficult to extend | stretch uniformly. Therefore, a higher melting point is not necessarily better for improving the shrinkage rate. As a result, in the case of a propylene homopolymer having a high melting point, it is preferable that the amount of component (A2) or component (B) for improving stretchability is large, and a propylene-ethylene random copolymer having a low melting point is obtained. The melting point of the component (A1) itself is lowered, so that the stretchability is improved and the amount of the component (A2) or the component (B) can be reduced.
These balances can be dealt with by changing the composition and quantity ratio of each component according to the required performance.

(2-2) Ratio of component (A1) in component (A) If the ratio of component (A1) in the block copolymer (A) is too large, the stretchability is lowered, while component (A1). Since the shrinkage ratio is reduced when the ratio is too small, the ratio of the component (A1) needs to be in the range of 30 to 95 wt%, and preferably in the range of 50 to 90 wt%.

(3) About component (A2) (3-1) Ethylene content E (A2) in component (A2)
The propylene-ethylene random copolymer component (A2) produced in the second step needs to be a component that does not deteriorate the transparency while improving the stretching characteristics of the block copolymer (A).
Here, the component (A2) needs to have an ethylene content in a specific range in order to sufficiently exhibit the above effect. That is, in the block copolymer (A) of the present invention, the lower the crystallinity of the component (A2) relative to the component (A1), the greater the effect of improving the stretching properties, and the crystallinity is propylene-ethylene random copolymer. Since the ethylene content E (A2) in the component (A2) is 3 wt% or more higher than the ethylene content E (A1) in the component (A1), the effect cannot be exhibited. , Preferably 6 wt% or more, more preferably 8 wt% or more, and more ethylene than component (A1).
Here, when the difference in ethylene content between the component (A1) and the component (A2) is defined as E (gap) (= E (A2) −E (A1)), E (gap) is 3 wt% or more, preferably 6 wt% % Or more, more preferably 8 wt% or more.
On the other hand, if the ethylene content is excessively increased to lower the crystallinity of the component (A2), the difference E (gap) between the ethylene content of the component (A1) and the component (A2) increases, and the phase is divided into a matrix and a domain. A separation structure is taken, and transparency is lowered. This is because polypropylene originally has low compatibility with polyethylene, and even in a propylene-ethylene random copolymer, the compatibility between those having different ethylene contents decreases as the difference in ethylene content increases. The upper limit of E (gap) may be in a range in which the peak of tan δ is single according to the solid viscoelasticity measurement described later in paragraph 0025. For that purpose, E (gap) is in a range of less than 16 wt%. .

(3-2) Ratio of component (A2) in component (A) As shown in the ratio of component (A1), if the amount of component (A2) is too small, the stretchability is lowered, whereas component (A2) Since the shrinkage ratio is reduced when the ratio is too large, the ratio of the component (A2) needs to be in the range of 70 to 5 wt%, and preferably in the range of 50 to 10 wt%.
In addition, the component (A2) is a component also responsible for imparting impact resistance and flexibility, and as a result, can contribute to prevention of film breakage. The quality of the polypropylene heat-shrinkable film can be further improved by setting the composition and ratio of the component (A2) within the above range according to the required performance.

(4) Melt flow rate (MFR) of component (A)
The MFR of the propylene-ethylene random copolymer used for the polypropylene film of the present invention needs to be in the range of 0.1 to 30 g / 10 min. That is, in the present invention, if the MFR is too low, surface roughness called shark skin or melt fracture melt fracture occurs on the surface of the film, which not only significantly impairs transparency and appearance but also makes stretch molding difficult. On the other hand, if the MFR is too high, the shrinkage rate decreases, which is not preferable.
Therefore, in the present invention, the MFR of the component (A) must be in the range of 0.1 to 30 g / 10 min, and the range of 0.5 to 10 g / 10 min is from the viewpoint of balance between molding stability, film appearance, and physical properties. To preferred.
The melt flow rate (MFR) in the present invention is measured under the conditions of test temperature: 230 ° C. nominal load: 2.16 kg, die shape: 2.095 mm in diameter, and 8.00 mm in length according to JIS K7210 A method condition M. It is.

(5) Solid viscoelasticity measurement (5-1) Specification based on peak of tan δ curve In the propylene-ethylene random copolymer used for the polypropylene film of the present invention, temperature-loss obtained by solid viscoelasticity measurement (DMA) In the tangent (tan δ) curve, it is necessary that the tan δ curve has a single peak below 0 ° C.
When the component (A) has a phase separation structure, the glass transition temperature of the amorphous part contained in the component (A1) and the glass transition temperature of the amorphous part contained in the component (A2) are different from each other. Multiple. In this case, there is a problem that the transparency is remarkably deteriorated, and the component (B) is concentrated on the amorphous part and the improvement of the stretching characteristics is not sufficient.
Whether or not the phase separation structure is taken can be discriminated in the tan δ curve in the measurement of solid viscoelasticity. Is brought about by having.
The propylene-ethylene block copolymer of the present invention needs to have a single peak in the tan δ curve in the measurement of solid viscoelasticity in order to exhibit the effect of improving transparency and stretching properties.
In addition, the example of the peak of a tan-delta curve is shown in FIG.2 and FIG.3 as an example in superposition | polymerization manufacture example-1 and the superposition | polymerization manufacture example-3 in the case where it does not have a single peak.

(5-2) Measurement method Specifically, solid viscoelasticity measurement is performed by applying a sinusoidal strain of a specific frequency to a strip-shaped sample piece and detecting the generated stress. Here, the frequency is 1 Hz, and the measurement temperature is raised stepwise from −60 ° C. until the sample is melted and cannot be measured. Further, it is recommended that the magnitude of distortion is about 0.1 to 0.5%. From the obtained stress, the storage elastic modulus and the loss elastic modulus are obtained by a known method, and the loss tangent (= loss elastic modulus G ″ / storage elastic modulus G ′) defined by the ratio is plotted against the temperature. Then, a sharp peak is shown in a temperature range of 0 ° C. or lower. Generally, the peak of the tan δ curve at 0 ° C. or lower is for observing the glass transition of the amorphous part, and here, this peak temperature is defined as the glass transition temperature Tg (° C.).

(6) Specific components (A1) and (A2) of ethylene content E (A1) and E (A2) of each component of components (A1) and (A2), and each component amount W (A1) and W (A2) Each ethylene content and component amount can be specified by the material balance at the time of polymerization (material balance), but in order to specify these more accurately, the following analysis (fractionation method) should be used. Is desirable.

(6-1) Identification of component amounts W (A1) and W (A2) by temperature-temperature elution fractionation (TREF) 6-1-1. Temperature Elevated Elution Fractionation Method A technique for evaluating the crystalline distribution of propylene-ethylene random copolymer by temperature elevated elution fractionation method (TREF) is well known to those skilled in the art. Detailed measurement methods are shown.
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).
The propylene-ethylene block copolymer in the present invention is greatly different in the crystallinity of each of the components (A1) and (A2), and each crystallinity distribution is narrow by being produced using a metallocene catalyst. Therefore, there are very few intermediate components between the two, and both can be accurately separated by TREF.

In the TREF elution curve obtained as a plot of elution amount (dWt% / dT) against temperature by the temperature rising elution fractionation method (TREF) in the temperature range of −15 ° C. to 140 ° C. using o-dichlorobenzene solvent, (A1) and (A2) show their elution peaks at the respective temperatures T (A1) and T (A2) due to the difference in crystallinity, and since the difference is sufficiently large, the intermediate temperature T (A3) (= {T Separation is almost possible at (A1) + T (A2)} / 2).
In addition, the lower limit of the TREF measurement temperature is −15 ° C. in the apparatus used for this measurement, but in the case where the crystallinity of the component (A2) is very low or an amorphous component, There may be no peak within the range (at this time, the concentration of the component (A2) dissolved in the solvent is detected at the lower limit of the measurement temperature (ie, −15 ° C.)). In this case, T (A2) is considered to exist below the lower limit of the measurement temperature, but the value cannot be measured. In such a case, T (A2) is the lower limit of the measurement temperature − It is defined as 15 ° C.
Here, if the integrated amount of the component eluted before T (A3) is defined as W (A2) wt%, and the integrated amount of the component eluted at T (A3) or higher is defined as W (A1) wt%, W (A2) Almost corresponds to the amount of the low-crystalline or amorphous component (A2), and the integrated amount W (A1) of the component eluted at T (A3) or higher is the component (A1) having a relatively high crystallinity. Almost corresponds to the amount of. In addition, the example of a TREF elution curve is illustrated by FIG. 1 as an example in superposition | polymerization manufacture example A-1.

6-1-2. TREF Measurement Method In the present invention, specifically, 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.

(6-2) Determination of ethylene content E (A1) and E (A2) in each component 6-2-1. Separation of components (A1) and (A2) Based on T (A3) determined by the previous TREF measurement, a component of soluble components in T (A3) (by a temperature rising column fractionation method using a preparative fractionator ( A2) and the insoluble component (A1) in T (A3) are fractionated, and the ethylene content of each component is determined by NMR.
The temperature rising column fractionation method is a measurement method disclosed in, for example, Macromolecules 21 314-319 (1988). Specifically, the following method was used in the present invention.

6-2-2. Fractionation conditions A cylindrical column having a diameter of 50 mm and a height of 500 mm is filled 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 (A3) 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 (A3), 800 ml of o-dichlorobenzene of T (A3) is allowed to flow at a flow rate of 20 ml / min, whereby components soluble in T (A3) present in the column are obtained. Elute and collect.
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. , T (A3) is eluted and recovered.
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.

6-2-3. ¹³ C-NMR by measuring the fractionated by components obtained ethylene content and (A1) (A2) an ethylene content of each was measured according to the following conditions by complete proton decoupling ^method, a 13 C-NMR spectrum Obtained by analysis.
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 number: 5,000 times or more The attribution of the spectrum may be performed with reference to Macromolecules 17 1950 (1984), for example. The spectral attributions measured under the above conditions are shown in Table 1. In the table, symbols such as S _αα follow the notation of Carman et al. (Macromolecules 10 536 (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 Macromolecules 15 1150 (1982) and the like, 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 (T _ββ ) (1)
[PPE] = k × I (T _βδ ) (2)
[EPE] = k × I (T _δδ ) (3)
[PEP] = k × I (S _ββ ) (4)
[PEE] = k × I (S _βδ ) (5)
[EEE] = k × {I (S _δδ ) / 2 + I (S _γδ ) / 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 (T _ββ ) means the intensity of the peak at 28.7 ppm attributed to T _ββ .
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 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 2.

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 where X is the ethylene content in mol%.
The ethylene content E (W) of the entire block copolymer is calculated from the ethylene contents E (A1), E (A2) and TREF of the components (A1) and (A2) measured above. The weight ratio W (A1) and W (A2) wt% is calculated by the following formula.
E (W) = {E (A1) × W (A1) + E (A2) × W (A2)} / 100 (wt%)

(6-3) Additional requirement of crystallinity distribution by TREF elution curve By using the TREF elution curve used for specifying the amount of each component, the propylene-ethylene block copolymer of the present invention has a crystallinity distribution. Additional features can be found in
6-3-1. Elution peak temperature T (A1)
The higher the elution peak temperature T (A1) of the component (A1) in the TREF elution curve, the higher the crystallinity of the component (A1). At this time, when the crystallinity of the component (A1) increases, the block copolymer ( Since the shrinkage properties tend to deteriorate with the decrease in stretchability of A), the component (A2) necessary for improving the shrinkage properties must be increased.
On the other hand, if the proportion of the component (A2) is too large, the shrinkage rate is reduced. Therefore, in order to improve the balance between stretchability and shrinkage rate, T (A1) should not be too high. Here, in the present invention, component (A1) is propylene alone or a random copolymer of ethylene of 7 wt% or less, but T (A1) can be lowered by an increase in ethylene content.
From this point of view, if the peak temperature T (A1) is less than 55 ° C., the temperature at which the component (A1) crystals melt is too low, and the block copolymer is unlikely to exhibit sufficient shrinkage characteristics. In the present invention, the peak temperature T (A1) is preferably 55 ° C. or higher, and more preferably 60 ° C. or higher.

6-3-2. Elution end temperature T (A4)
Even if T (A1) is low, when the crystallinity distribution is on the high crystal side, there is a problem that the shrinkage property is deteriorated due to the decrease in stretchability. The cause of this is not clear, but it is presumed that the higher-order structure of the crystal becomes coarse if there is a crystalline distribution on the high crystal side.
Therefore, it is preferable that the crystallinity spread to the high temperature side is suppressed in the TREF elution curve. The spread of crystallinity toward the high crystal side can be evaluated by TREF measurement, and the elution end temperature T (A4) of the entire component propylene-ethylene block copolymer with respect to the peak temperature T (A1) (however, TREF measurement Since it is difficult to define the temperature at which all elution occurs, it is preferable that the temperature at which 99 wt% of the elution is defined as the elution end temperature T (A4) is not high in the present invention. If there is an elution component on the side, the crystallinity of the component increases. Therefore, as a preferable requirement of the present invention, T (A4) is 98 ° C. or less, preferably 90 ° C. or less.
Furthermore, the temperature difference ΔT (T (A4) −T (A1)) from the elution peak to the end is preferably 5 ° C. or less, more preferably 4 ° C. or less, and even more preferably 3 ° C. or less.

6-3-3. Elution peak temperature T (A2)
If the crystallinity of the component (A2) is not sufficiently lowered, the effect of improving the stretchability of the block copolymer component (A) is insufficient, and the shrinkage property is not sufficiently improved. Therefore, T (A2) is preferably 45 ° C. Below, more preferably 40 ° C. or less.

(7) Regarding molecular weight (7-1) Regulation of molecular weight The propylene-ethylene block copolymer component (A) in the present invention is additionally characterized by a low amount of low molecular weight components.
It is considered that a low molecular weight component, particularly a component whose molecular weight is less than the molecular weight between the entanglement points, bleeds out to the surface of the molded body and deteriorates stickiness and transparency.
The molecular weight between the entanglement points of polypropylene is about 5,000, as described in Journal of Polymer Science: Part B: Polymer Physics; 37 1023-1103 (1999).
Therefore, the block copolymer in the present invention has a low molecular weight component and the amount of the component having a weight average molecular weight of 5,000 or less is 0.8 wt% or less, preferably 0.5 wt% or less.

(7-2) Molecular weight measurement In this invention, a weight average molecular weight (Mw) and a number average molecular weight (Mn) say what was measured by the gel permeation chromatography (GPC) method.
Conversion from the retention volume to the molecular weight is performed using a calibration curve prepared in advance with standard polystyrene.
Standard polystyrenes used are the following brands manufactured by Tosoh Corporation. F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000
A calibration curve is prepared by injecting 0.2 ml of a solution dissolved in o-dichlorobenzene (containing 0.5 mg / ml BHT) so that each is 0.5 mg / ml. The calibration curve uses a cubic equation obtained by approximation by the least square method. The following numerical value is used for [η] = K × M ^α in the viscosity formula used for conversion to molecular weight.
PS: K = 1.38 × 10 ⁻⁴ α = 0.7
PE: K = 3.92 × 10 ⁻⁴ α = 0.733
PP: K = 1.03 × 10 ⁻⁴ α = 0.78
The measurement conditions for GPC are as follows.
Apparatus: GPC (ALC / GPC 150C) manufactured by WATERS
Detector: MIRAN 1A IR detector manufactured by FO × BORO (measurement wavelength: 3.42 μm)
Column: AD806M / S (3 pieces) manufactured by Showa Denko KK
Mobile phase solvent: o-dichlorobenzene Measurement temperature: 140 ° C.
Flow rate: 1.0 ml / min
Injection volume: 0.2ml
Sample Preparation Prepare a 1 mg / ml solution using o-dichlorobenzene (containing 0.5 mg / ml BHT) and dissolve it at 140 ° C. for about 1 hour.
The amount of the component having a molecular weight of 5,000 or less can also be determined from a plot of the elution ratio against the molecular weight obtained by GPC measurement.

3. Propylene-ethylene block polymer production method (1) Metallocene catalyst The method for producing the propylene-ethylene block copolymer (A) of the present invention requires the use of a metallocene catalyst.
It is well known to those skilled in the art that stickiness and bleedout deteriorate when the molecular weight and crystallinity distribution are wide in the propylene-ethylene block copolymer, but also in the propylene-ethylene block copolymer used in the present invention, In order to suppress stickiness and bleed out, and to exhibit sufficient transparency and heat shrinkability in a heat shrinkable film, it is necessary to polymerize using a metallocene catalyst that can narrow the molecular weight and crystallinity distribution. It is apparent from the comparison of the examples and comparative examples described later that the Ziegler-Natta catalyst does not yield the excellent propylene-ethylene block copolymer of the present invention.

The type of the metallocene-based catalyst is not particularly limited as long as it can produce a copolymer having the performance of the present invention. It is preferable to use a metallocene catalyst comprising a) and (b) and, if necessary, the component (c) used.
Component (a): At least one metallocene transition metal compound selected from the transition metal compounds represented by the general formula (1) Component (b): At least one selected from the following (b-1) to (b-4) (B-1) an ionic compound capable of reacting with the component (A) to convert the component (A) into a cation, or (B-3) Solid acid fine particles (b-4) Ion exchange layered silicate component (c): Organoaluminum compound.

(1-1) Component (a)
As the component (a), at least one metallocene transition metal compound selected from transition metal compounds represented by the following general formula (1) can be used.
_{Q (C 5 H 4 -aR 1} ) (C 5 H 4 -bR 2) MeXY (1)

[Wherein Q represents a divalent linking group that bridges two conjugated five-membered ring ligands, Me represents a metal atom selected from titanium, zirconium, and hafnium, and X and Y represent hydrogen atoms. Atom, halogen atom, hydrocarbon group, alkoxy group, amino group, nitrogen-containing hydrocarbon group, phosphorus-containing hydrocarbon group or silicon-containing hydrocarbon group, X and Y are each independently, ie, the same or different. Also good. R ₁ and R _{2 each} represent hydrogen, a hydrocarbon group, a halogenated hydrocarbon group, a silicon-containing hydrocarbon group, a nitrogen-containing hydrocarbon group, an oxygen-containing hydrocarbon group, a boron-containing hydrocarbon group, or a phosphorus-containing hydrocarbon group. . a and b are the number of substituents. ]

Specifically, Q represents a divalent linking group that bridges two conjugated five-membered ring ligands, and has, for example, a divalent hydrocarbon group, a silylene group or an oligosilylene group, or a hydrocarbon group as a substituent. Examples include a silylene group, an oligosilylene group, or a germylene group having a hydrocarbon group as a substituent. Among these, preferred is a silylene group having a divalent hydrocarbon group and a hydrocarbon group as a substituent.
X and Y represent a hydrogen atom, a halogen atom, a hydrocarbon group, an alkoxy group, an amino group, a nitrogen-containing hydrocarbon group, a phosphorus-containing hydrocarbon group, or a silicon-containing hydrocarbon group. Among these, hydrogen is preferable , Chlorine, methyl, isobutyl, phenyl, dimethylamide, diethylamide group and the like. X and Y may be independent, that is, may be the same or different.
R ₁ and R ₂ represent hydrogen, a hydrocarbon group, a halogenated hydrocarbon group, a silicon-containing hydrocarbon group, a nitrogen-containing hydrocarbon group, an oxygen-containing hydrocarbon group, a boron-containing hydrocarbon group, or a phosphorus-containing hydrocarbon group. . Specific examples of the hydrocarbon group include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a phenyl group, a naphthyl group, a butenyl group, and a butadienyl group. In addition, halogenated hydrocarbon group, silicon-containing hydrocarbon group, nitrogen-containing hydrocarbon group, oxygen-containing hydrocarbon group, boron-containing hydrocarbon group or phosphorus-containing hydrocarbon group include methoxy group, ethoxy group, phenoxy group, trimethylsilyl group. Typical examples include a group, a diethylamino group, a diphenylamino group, a pyrazolyl group, an indolyl group, a dimethylphosphino group, a diphenylphosphino group, a diphenylboron group, and a dimethoxyboron group. In these, it is preferable that it is a C1-C20 hydrocarbon group, and it is especially preferable that they are a methyl group, an ethyl group, a propyl group, and a butyl group. By the way, adjacent R ₁ and R ₂ may combine to form a ring, on which a hydrocarbon group, halogenated hydrocarbon group, silicon-containing hydrocarbon group, nitrogen-containing hydrocarbon group, oxygen-containing You may have a substituent which consists of a hydrocarbon group, a boron containing hydrocarbon group, or a phosphorus containing hydrocarbon group.
Me is a metal atom selected from titanium, zirconium and hafnium, preferably zirconium and hafnium.

  Among the components (a) described above, preferred for the production of the propylene polymer of the present invention is a substituted cyclopentadienyl group crosslinked with a silylene group, a germylene group or an alkylene group having a hydrocarbon substituent. A transition metal compound comprising a ligand having a substituted indenyl group, a substituted fluorenyl group, or a substituted azulenyl group, particularly preferably a 2,4-position crosslinked by a silylene group having a hydrocarbon substituent or a germylene group It is a transition metal compound comprising a ligand having a substituted indenyl group and a 2,4-position substituted azulenyl group.

Non-limiting specific examples include dimethylsilylene bis (2-methyl-4-phenylindenyl) zirconium dichloride, diphenylsilylene bis (2-methyl-4-phenylindenyl) zirconium dichloride, dimethylsilylene bis (2-methyl). Benzoindenyl) zirconium dichloride, dimethylsilylenebis {2-isopropyl-4- (3,5-diisopropylphenyl) indenyl} zirconium dichloride, dimethylsilylenebis (2-propyl-4-phenanthrylindenyl) zirconium dichloride, dimethyl Silylene bis (2-methyl-4-phenylazurenyl) zirconium dichloride, dimethylsilylene bis {2-methyl-4- (4-chlorophenyl) azurenyl} zirconium dichloride, dimethylsilylene bi (2-Ethyl-4-phenylazurenyl) zirconium dichloride, dimethylsilylenebis (2-isopropyl-4-phenylazurenyl) zirconium dichloride, dimethylsilylenebis {2-ethyl-4- (2-fluorobiphenyl) azurenyl} zirconium Examples thereof include dichloride and dimethylsilylenebis [2-ethyl-4- (4-t-butyl-3-chlorophenyl) azurenyl} zirconium dichloride.
A compound in which the silylene group of these specific examples is replaced with a germylene group and zirconium is replaced with hafnium is also exemplified as a suitable compound.
In addition, since the catalyst component is not an important element of the present invention, it avoids complicated listing and is limited to a representative example, but it is obvious that the effective range of the present invention is not limited thereby. It is.

(1-2) Component (b)
As the component (b), at least one solid component selected from the components (b-1) to (b-4) described above is used. Each of these components is a known component, and can be appropriately selected from known technologies and used. Specific examples and manufacturing methods thereof are described in detail in JP-A No. 2002-284808, JP-A No. 2002-53609, JP-A No. 2002-69116, JP-A No. 2003-105015, and the like.
Here, as the particulate carrier used for the component (b-1) and the component (b-2), inorganic oxides such as silica, alumina, magnesia, silica alumina, silica magnesia, magnesium chloride, magnesium oxychloride, chloride Examples thereof include inorganic halides such as aluminum and lanthanum chloride, and porous organic carriers such as polypropylene, polyethylene, polystyrene, styrene divinyl benzene copolymer, and acrylic acid copolymer.

Further, as a non-limiting specific example of the component (B), a particulate carrier on which methylalumoxane, isobutylalumoxane, methylisobutylalumoxane, aluminum butylboronate tetraisobutyl, etc. are supported as the component (b-1). As component (b-2), triphenylborane, tris (3,5-difluorophenyl) borane, tris (pentafluorophenyl) borane, triphenylcarbonium tetrakis (pentafluorophenyl) borate, N, N-dimethyl Particulate carrier carrying anilinium tetrakis (pentafluorophenyl) borate, etc., component (b-3), alumina, silica alumina, magnesium chloride, etc., component (b-4), montmorillonite, zakonite, beidellite , Nontronic , Saponite, hectorite, stevensite, bentonite, smectite group such as taeniolite, vermiculite, and the like mica group. These may form a mixed layer.
Particularly preferred among the above components (b) is the ion-exchange layered silicate of component (b-4), and more preferred are chemical treatments such as acid treatment, alkali treatment, salt treatment, and organic matter treatment. It is an ion exchange layered silicate applied.

(1-3) Component (c)
Examples of organoaluminum compounds used as component (c) as needed are:
General formula AIR _a X _3-a
(Wherein R is a hydrocarbon group having 1 to 20 carbon atoms, X is hydrogen, halogen, alkoxy group, a is a number of 0 <a ≦ 3), trimethylaluminum, triethylaluminum, tripropylaluminum, Trialkylaluminum such as triisobutylaluminum or halogen- or alkoxy-containing alkylaluminum such as diethylaluminum monochloride, diethylaluminum monomethoxide. In addition, aluminoxanes such as methylaluminoxane can also be used. Of these, trialkylaluminum is particularly preferred.

(1-4) Formation of catalyst Component (a), component (b) and, if necessary, component (c) are brought into contact to form a catalyst. The contact method is not particularly limited, but the contact can be made in the following order. Moreover, this contact may be performed not only at the time of catalyst preparation but also at the time of prepolymerization with olefin or at the time of polymerization of olefin.
1) Contact component (a) and component (b) 2) Add component (c) after contacting component (a) and component (b) 3) Contact component (a) and component (c) 4) Add component (b) after contact 4) Add component (a) after contacting component (b) and component (c) 5) Contact three components simultaneously

(1-5) Component Amounts The amounts of components (a), (b) and (c) used in the present invention are arbitrary. For example, the amount of component (a) used relative to component (b) is preferably in the range of 0.1 μmol to 1,000 μmol, particularly preferably 0.5 μmol to 500 μmol, relative to 1 g of component (b). The amount of component (c) used relative to component (b) is preferably such that the amount of transition metal is 0.001 to 100 μmol, particularly preferably 0.005 to 50 μmol, relative to 1 g of component (b). Therefore, the amount of the component (c) to the component (a) is preferably in the range of 10 ⁻⁵ to 50, particularly preferably 10 ^{−4 to} 5 in terms of the molar ratio of the transition metal.

(1-6) Prepolymerization It is preferable that the catalyst of the present invention is subjected to a prepolymerization treatment in which a small amount of the olefin is brought into contact with the catalyst in advance. The olefin to be used is not particularly limited, but ethylene, propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-butene, vinylcycloalkane, styrene, and the like can be used. It is possible to use, and it is particularly preferable to use propylene. The olefin can be supplied by any method such as a supply method for maintaining the olefin at a constant speed or in a constant pressure state, a combination thereof, or a stepwise change. The prepolymerization temperature and time are not particularly limited, but are preferably in the range of −20 ° C. to 100 ° C. and 5 minutes to 24 hours, respectively. The amount of prepolymerization is preferably 0.01 to 100, more preferably 0.1 to 50 with respect to the component (b). After completion of the prepolymerization, the catalyst can be used as it is, depending on the usage form of the catalyst, but may be dried if necessary.
Furthermore, a polymer such as polyethylene, polypropylene, or polystyrene, or an inorganic oxide solid such as silica or titania can be allowed to coexist during or after the contact of the above components.

(2) Production method (2-1) Sequential polymerization In producing the propylene-ethylene block polymer (A) of the present invention, the crystalline propylene-ethylene random copolymer component (A1) and low crystalline or non-crystalline The crystalline propylene-ethylene random copolymer component (A2) needs to be sequentially polymerized for the reason described above.
When performing sequential polymerization, either a batch method or a continuous method can be used, but it is generally desirable to use a continuous method from the viewpoint of productivity.
In the case of a batch method, it is possible to polymerize component (A1) and component (A2) separately using a single reactor by changing the polymerization conditions with time. As long as the effects of the present invention are not impaired, a plurality of reactors may be connected in parallel.
In the case of the continuous method, it is necessary to use a production facility in which two or more reactors are connected in series because it is necessary to individually polymerize the component (A1) and the component (A2), but as long as the effect of the present invention is not impaired. A plurality of reactors may be connected in series and / or in parallel for each of component (A1) and component (A2).

(2-2) Polymerization process As the polymerization process (polymerization method), an arbitrary polymerization method such as a slurry method, a bulk method, or a gas phase method can be used. Although supercritical conditions can be used as intermediate conditions between the bulk method and the gas phase method, they are substantially the same as the gas phase method, and are therefore included in the gas phase method without particular distinction.
Since the low crystalline or amorphous propylene-ethylene random copolymer component (A2) is easily soluble in organic solvents such as hydrocarbons and liquefied propylene, it is desirable to use a gas phase method for the production of the component (A2).
There is no particular problem in using any process for the production of the crystalline propylene-ethylene random copolymer component (A1). In order to avoid this problem, it is desirable to use a vapor phase method.
Therefore, the crystalline propylene-ethylene random copolymer component (A1) is first polymerized by a bulk method or a gas phase method using a continuous method, followed by a low crystalline or amorphous propylene-ethylene random copolymer elastomer. It is most desirable to polymerize component (A2) by a gas phase method.

(2-3) Other Polymerization Conditions The polymerization temperature can be used without any particular problem as long as it is within a commonly used temperature range. Specifically, a range of 0 ° C. to 200 ° C., more preferably 40 ° C. to 100 ° C. can be used.
Although the polymerization pressure varies depending on the process to be selected, it can be used without any problem as long as it is in a pressure range usually used. Specifically, a range of greater than 0 to 200 MPa, more preferably 0.1 MPa to 50 MPa can be used. At this time, an inert gas such as nitrogen can be coexisted.
In the case where the sequential polymerization of the component (A1) in the first step and the component (A2) in the second step is performed, it is desirable to add a polymerization inhibitor into the system in the second step. In the case of producing a propylene-ethylene block copolymer, if a polymerization inhibitor is added to a reactor that performs ethylene-propylene random copolymerization in the second step, the particle properties (fluidity, etc.) of the resulting powder, gel, etc. Product quality can be improved. Various technical studies have been made on this technique, and examples thereof include Japanese Patent Publication Nos. 63-54296, 7-25960, and 2003-2939. It is desirable to apply the method to the present invention.

4). Method for Controlling Components of Propylene-Ethylene Block Copolymer Each component of the propylene-ethylene block copolymer (A) used in the polypropylene film of the present invention is controlled as follows, and the propylene-ethylene block of the present invention is controlled. It can manufacture so that the structural requirements required for a copolymer (A) may be satisfy | filled.

(1) About component (A1) About crystalline propylene-ethylene random copolymer component (A1), it is necessary to control ethylene content E (A1) and T (A1).
In the present invention, in order to control E (A1) within a predetermined range, the amount ratio of propylene and ethylene supplied to the polymerization tank in the first step may be appropriately adjusted. The relationship between the supply ratio and the ethylene content in the resulting propylene-ethylene random copolymer varies depending on the type of metallocene catalyst used, but the component (A1) having the ethylene content E (A1) required by adjusting the supply ratio is added. Can be manufactured. For example, when E (A1) is controlled to 0 to 7 wt%, the supply weight ratio of ethylene to propylene may be in the range of 0 to 0.3, preferably in the range of 0 to 0.2. At this time, the component (A1) has a narrow crystallinity distribution, and T (A1) decreases as E (A1) increases.
Therefore, in order for T (A1) to satisfy the scope of the present invention, E (A1) and the relationship between these are grasped and adjusted to take the target range.

(2) Component (A2) Regarding the low crystalline or amorphous propylene-ethylene random copolymer component (A2), it is necessary to control the ethylene contents E (A2) and T (A2).
In the present invention, in order to control E (A2) within a predetermined range, the ratio of ethylene supply to propylene in the second step may be controlled in the same manner as E (A1). For example, when E (A2) is controlled to 5 to 20 wt%, the supply weight ratio of ethylene to propylene may be in the range of 0.01 to 5, preferably in the range of 0.05 to 2. At this time, although the crystallinity distribution of the component (A2) is slightly increased as the ethylene content is increased, T (A2) is decreased as E (A2) is increased as in the case of the component (A1).
Therefore, in order for T (A2) to satisfy the scope of the present invention, the relationship between E (A2) and T (A2) is grasped, and E (A2) is controlled to be within a predetermined range. Good.

(3) About W (A1) and W (A2) The amount W (A1) of component (A1) and the amount W (A2) of component (A2) are the production amounts of the first step for producing component (A1). It can be controlled by changing the ratio of the production amount of the component (A2). For example, in order to increase W (A1) and decrease W (A2), the production amount of the second step may be reduced while maintaining the production amount of the first step, which shortens the residence time of the second step. It can be easily controlled by reducing the polymerization pressure or polymerization temperature or increasing the amount of the polymerization inhibitor. The reverse is also true.
When actually setting the conditions, it is necessary to consider the activity decay. That is, in the range of the ethylene content E (A1) and E (A2) carried out in the present invention, generally, the polymerization activity increases when the ratio of ethylene supply to propylene is increased in order to increase the ethylene content. The activity decay tends to increase. Therefore, in order to maintain the activity of the second step, it is necessary to suppress the polymerization activity of the first step. Specifically, the production amount W (A1) is lowered in the first step, and the polymerization is performed as necessary. Lower the temperature and / or shorten the polymerization time (residence time), or increase the ethylene content E (A2) in the second step, increase the production W (A2), and raise the polymerization temperature as necessary And / or conditions may be set in such a way as to increase the polymerization time (residence time).

(4) Glass transition temperature Tg In the propylene-ethylene block copolymer used in the present invention, the glass transition temperature Tg described in paragraph 0025 needs to have a single peak. In order for Tg to have a single peak, the difference [E] gap or E (A2) between the ethylene content E (A1) in component (A1) and the ethylene content E (A2) in component (A2) ) -E (A1) may be 20 wt% or less, preferably 18 wt%, more preferably 16 wt% or less, and E (gap) may be reduced to a range where Tg becomes a single peak in actual measurement.
Depending on the ethylene content E (A1) of the crystalline copolymer component (A1), the ethylene content E (A2) of the low crystalline or non-crystalline copolymer component (A2) is within an appropriate range. By setting the supply weight ratio of ethylene to propylene during the polymerization of component (A2), it is possible to obtain a polymer having a predetermined [E] gap.
The Tg of the block copolymer that does not take a phase separation structure as in the present invention is the ethylene content E (A1) in the component (A1), the ethylene content E (A2) in the component (A2), and It is affected by the ratio of both components. In the present invention, the amount of the component (A2) is 5 to 70 wt%, but in this range, Tg is more strongly affected by the ethylene content E (A2) in the component (A2).
That is, Tg reflects the glass transition of the amorphous part, whereas in the block copolymer component (A) of the present invention, the component (A1) has crystallinity and relatively few amorphous parts, This is because the component (A2) is low crystalline or amorphous and most of it is an amorphous part.
Therefore, the value of Tg is controlled approximately by E (A2), and the control method for E (A2) is as described above in paragraph 0060.

(5) Melt flow rate (MFR) In the propylene-ethylene block copolymer (A) of the present invention, a crystalline copolymer component (A1) and a low crystalline or amorphous material are used to maintain transparency. Since it is essential that the copolymer elastomer component (A2) is compatible, the viscosity [η] A1 of the component (A1), the viscosity [η] A2 of the component (A2), propylene-ethylene block copolymer An apparent viscosity mixing rule is generally established between the total viscosity [η] W of the combined (A). That is,
Log [η] W = {W (A1) × Log [η] A1 + W (A2) × Log [η] A2} / 100
Is generally established. In general, there is a certain correlation between MFR and [η], so from the viewpoint of flexibility and heat resistance, [η] A2, W (A1), and W (A2) are set first. The MFR can be freely controlled by changing [η] A1 according to the above equation.

(6) About T (A4) T (A4) is an index indicating the crystallinity distribution, and the narrower the crystallinity distribution of the component (A1) is, the closer T (A4) is to T (A1) (lower). ), Controlling T (A4) to be low is nothing other than controlling the crystallinity distribution of component (A1) and component (A2) narrowly.
In general, by using a metallocene catalyst, a polymer having a narrower crystallinity distribution can be obtained than when using a Ziegler-Natta catalyst. It is not necessary and sufficient to use a metallocene catalyst in order to narrow the sex distribution.
In order to adjust the final propylene-ethylene block copolymer to those having desirable physical properties, the component (A1) and the component (A2) need to have different specific polymer compositions. That is, in the first step and the second step, it is necessary to keep the polymerization conditions corresponding to the respective polymer compositions, particularly the monomer gas composition, at different specific values. Therefore, when the crystallinity distribution of the component (A2) is wide in the adopted process, the transfer step is adjusted so that the specific monomer gas mixture corresponding to the first step is not brought into the second step from the first step. It is necessary to devise such as. Specifically, the crystallinity distribution of the component (A2) can be narrowed by increasing the purge amount in the transfer step, or by diluting or substituting with an inert gas such as nitrogen. That is, T (A4) can be controlled to be low by adjusting the transfer process.

(7) About W (Mw ≦ 5,000) In general, a polymer having a narrower molecular weight distribution than that of a Ziegler-Natta catalyst can be obtained by using a metallocene catalyst. However, in a system that performs sequential polymerization as in the present invention, it is not always sufficient to use a metallocene catalyst in order to narrow the molecular weight distribution. In particular, in order to prevent the formation of low molecular weight components, the time for transferring from the first step to the second step can be shortened, or the monomer gas mixture corresponding to the first step in the transfer step can be replaced with an inert gas such as nitrogen. By completely substituting, W (Mw ≦ 5,000) can be controlled to be small independently of the polymerization conditions.

5. Structure of Alicyclic Hydrocarbon Resin Component (B) (1) Basic Rules The alicyclic hydrocarbon resin component (B) used in the present invention has a low temperature shrinkage property of the resin composition for polypropylene heat-shrinkable film. It is a component necessary for improvement, and is an alicyclic hydrocarbon resin component having a softening point temperature of 110 ° C. or higher and 160 ° C. or lower, preferably 120 ° C. or higher and 145 ° C. or lower.
When the softening point is less than 110 ° C., the heat shrinkage rate tends to be small, and stickiness or whitening is likely to occur over time. Moreover, when the softening point temperature exceeds 160 ° C., the transparency of the stretched film tends to deteriorate.
The addition amount is 5 to 50 wt%, preferably 10 to 30 wt%. If it is less than 5 wt%, the heat shrinkage properties deteriorate, and if it is greater than 50 wt%, the specific gravity tends to be high, and stickiness tends to occur during film formation.
Here, the density is preferably about 0.94 cm ³ or less in order to separate the specific gravity by water from other resins such as PET bottles.

(2) Preferred examples of alicyclic hydrocarbon resin component (B) Among alicyclic hydrocarbon resins having a softening point of 110 ° C to 160 ° C, particularly preferred examples of the present invention include petroleum resins and terpenes. Examples thereof include resins, rosin resins, coumarone indene resins, and hydrogenated derivatives thereof. Among these, resins having no polar group or resins having a hydrogenation rate of 95% or more by adding hydrogen are preferable. A more preferable resin is petroleum resin or a hydrogenated derivative of petroleum resin, and examples of the petroleum resin include commercially available products such as Alcon manufactured by Arakawa Chemical Industries, Ltd. or Opera manufactured by ExxonMobil Co., Ltd. .

6). Additional component The resin composition for a polypropylene heat-shrinkable film of the present invention may be blended with an ethylene / α-olefin copolymer component for the purpose of improving heat shrinkability and improving the fracture resistance of the stretched film. The standard of the blending amount is approximately 0 to 10 wt%, and if it exceeds 10 wt%, the rigidity tends to decrease and the transparency tends to deteriorate.

The ethylene-α-olefin copolymer is a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms, and preferably has an ethylene content of 95 to 60 wt%. When the ethylene content exceeds 95 wt%, the effects of improving heat shrinkability and rupture resistance are not easily observed, and when the ethylene content is less than 60 wt%, the rigidity tends to decrease.
Moreover, it is preferable that the density of this ethylene-alpha-olefin copolymer is 0.870-0.920 g / cm < ³ >. When the density is less than 0.870 g / cm ³ , stickiness is likely to occur, and the blocking resistance is deteriorated. When the density is more than 0.920 g / cm ³ , the effects of improving heat shrinkability and rupture resistance are not easily observed.

In addition, for example, an amorphous cyclic olefin resin may be added to the polypropylene heat-shrinkable film resin composition of the present invention for the purpose of improving heat shrinkability.
Examples of the amorphous cyclic olefin-based resin include polymers such as cyclopentadiene and tetracyclododecene, and copolymers mainly composed thereof. Etc. can be illustrated.
The standard of a compounding quantity is about 0-20 weight part with respect to 100 weight part of resin compositions of this invention. If it exceeds 20 parts by weight, the polypropylene-based heat-shrinkable shrink label film made of the resin composition of the present invention becomes fragile or the transparency tends to deteriorate.
Amorphous cyclic olefin-based resins having a glass transition temperature of 50 ° C. or higher and 120 ° C. or lower are preferable from the viewpoint of improving heat shrinkage and ensuring transparency.

  In the resin composition for polypropylene-based heat-shrinkable film of the present invention, a nucleating agent, an antioxidant, a neutralizing agent, a light stabilizer used as a known compounding agent for polyolefin resin as long as the effects of the present invention are not impaired. Various additives such as an ultraviolet absorber, an antiblocking agent, a lubricant, an antistatic agent, a metal deactivator, a peroxide, a filler, an antibacterial and antifungal agent, and a fluorescent brightening agent can be added. The amount of these additives is generally 0.0001 to 3% by weight, preferably 0.001 to 1% by weight.

7). Polypropylene-based heat-shrinkable shrink film (1) Production method of film The polypropylene-based heat-shrinkable film of the present invention is obtained by stretching an unstretched sheet containing at least one layer of the resin composition in at least a uniaxial direction, and preferably aging subsequently. Thus, it can be obtained by controlling the shrinkage with time.
(1-1) Production of unstretched sheet For production of an unstretched sheet, a known film or sheet forming method can be used. As a specific example, a casting method in which a raw material is plasticized by an extruder, and a resin melt-extruded from a T-die is cooled and solidified using an air knife and a cooling roll, and niped by two or more cooling rolls and then cooled and solidified. Examples thereof include sheet molding and inflation molding in which a resin melt-extruded from an annular die is cooled and solidified by air cooling or water cooling.

(1-2) Stretching method As the stretching method, a known method can be used. For example, a tubular method, a tenter-type stretching method, a roll stretching method using a speed difference between rolls, a pantograph batch stretching method, and the like. Can be mentioned.
As an example of the stretching method, a sheet obtained by the T-die method is roll-stretched about 1.0 to 5.0 times, preferably about 1.0 to 1.5 times, and then 2.0 to 10.0 by the tenter method. An example is a method of stretching about twice, preferably about 3.0 to 10.0 times.
For the purpose of improving the shrinkage rate, the stretching is preferably performed at a low temperature as much as possible within a range that does not cause stretching cracks and poor appearance. Especially when there is a step of preheating the unstretched sheet, the preheating temperature is formed From the viewpoint of improving the shrinkage rate, it is preferable to make it as low as possible within the possible range.
At this time, by using the resin composition of the present invention, it is possible to lower the stretching temperature without causing stretching cracks, and for example, it is higher than the melting peak temperature Tm (° C.) obtained by DSC measurement of the component (A). It is preferable to carry out at a temperature lower by 60 ° C. or more because the shrinkage rate at a low temperature is extremely improved.

(1-3) Aging If the shrinkage with time is large after stretching, there are cases where blocking occurs or the paper tube is destroyed when the film is wound around a paper tube and stored. Therefore, it is preferable to perform a known heat treatment such as so-called aging in order to suppress the shrinkage over time. Conditions for heat treatment such as aging can be appropriately set in view of the balance between shrinkage with time and heat shrinkage.

(1-4) Laminated film The polypropylene heat-shrinkable film of the present invention can be used in multiple layers in order to satisfy various requirements other than shrinkage characteristics. Examples of lamination are those in which a known sealant resin is laminated on the surface layer in order to improve heat sealability or reduce blocking, or in which a known barrier material such as PVDC or EVOH is laminated in order to impart barrier properties. Or something.
Further, for the purpose of further improving the heat shrinkage rate and imparting a sealing property with a solvent, the glass transition temperature is preferably 40 to 100 ° C., more preferably 50 to 90 ° C., and the MFR (260 ° C., 2.16 kg load) is 10 to 50 g. / 10 minutes, more preferably 15 to 35 g / 10 minutes cyclic olefin compound and / or a cyclic olefin polymer comprising ethylene, a polymer obtained by ring-opening polymerization of a cyclic olefin compound or a hydrogenated product thereof. The cyclic olefin resin selected from the cyclic olefin resin is preferably 50 to 100 wt%, more preferably 60 to 90 wt%, and the specific gravity is 0.88 to 0.93, more preferably 0.90 to 0.92, MFR (190 ° C. , 2.16 kg load) is 1.0 to 10 g / 10 min, more preferably 1.5 to 5.0 g / 10 min. More preferably the linear low density polyethylene 0～50Wt% which is also mentioned laminating a resin composition comprising 10 to 40 wt%.
At that time, a cyclic olefin polymer composed of the cyclic olefin compound and / or ethylene, a polymer obtained by ring-opening polymerization of the cyclic olefin compound, or a cyclic olefin resin mainly composed of a hydrogenated product thereof. By laminating olefin-based resins, the film tends to be fragile, and on the other hand, blending the linear low density polyethylene tends to deteriorate transparency, so that heat shrinkability, solvent sealability, transparency It is preferable to adjust the blending amount of the linear low density polyethylene in consideration of the balance.

A cyclic olefin resin selected from a cyclic olefin polymer comprising the cyclic olefin compound and / or ethylene, a polymer obtained by ring-opening polymerization of a cyclic olefin compound, or a hydrogenated product thereof. Examples thereof include polymers such as cyclopentadiene and tetracyclododecene, and copolymers mainly composed thereof, and examples of commercially available products include Apel manufactured by Mitsui Chemicals, ZEONOR manufactured by Nippon Zeon Co., Ltd., and the like.
Examples of the method for laminating these multilayer films include a multilayer coextrusion method and an in-line laminating method, but the multilayer coextrusion method is preferable from the viewpoint of simplifying the production equipment.
In addition, known additives such as antiblocking agents, slip agents, and antistatic agents can be appropriately added to the surface layer of the laminated film for the purpose of controlling the surface properties.

8). Applications The resin composition and heat shrinkable shrink film using the resin composition of the present invention are excellent in heat shrink characteristics at low temperatures, light in specific gravity, transparent and excellent in gloss, and can be widely used in fields where conventional shrink films are used. is there.
Among these, it is particularly suitable for shrink label applications typified by plastic bottle packaging taking advantage of these features.

In the following, in order to describe the present invention more specifically and clearly, the present invention will be described in contrast to Examples and Comparative Examples, and the rationality and significance of the requirements of the constitution of the present invention will be demonstrated.
The evaluation methods and resins used in the examples and comparative examples are as follows.

[Method for measuring physical properties of propylene-ethylene block copolymer (A)]
1) Melt flow rate (MFR)
According to JIS K7210 A method condition M, it measured on condition of the following.
Test temperature: 230 ° C
Nominal weight: 2.16kg
Die shape: Diameter 2.095mm Length 8.00mm

2) TREF
A sample is dissolved in o-dichlorobenzene (containing 0.5 mg / ml BHT) at 140 ° C. to prepare 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. Thereafter, o-dichlorobenzene (containing 0.5 mg / ml BHT) as a solvent is caused to flow through the column at a flow rate of 1 ml / min, and components dissolved in o-dichlorobenzene at −15 ° C. in the TREF column. Elution is performed 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.
〔apparatus〕
(TREF part)
TREF column: 4.3 mmφ × 150 mm stainless steel column Column packing material: 100 μm surface inactive treated glass beads Heating method: Aluminum heat block Cooling method: Peltier element (Peltier element is cooled by water)
Temperature distribution: ± 0.5 ° C
Temperature controller: Chino Corporation Digital Program Controller KP1000 (Valve Oven)
Heating method: Air bath oven Measurement temperature: 140 ° C
Temperature distribution: ± 1 ° C
Valve: 6-way valve 4-way valve (sample injection part)
Injection method: Loop injection method Injection volume: Loop size 0.1ml
Inlet heating method: Aluminum heat block measurement temperature: 140 ° C
(Detection unit)
Detector: Fixed wavelength infrared detector FOXBORO MIRAN 1A
Detection wavelength: 3.42 μm
High-temperature flow cell: Micro flow cell for LC-IR Optical path length: 1.5 mm Window shape: 2φ x 4 mm long circle Synthetic sapphire window measurement temperature: 140 ° C
(Pump part)
Liquid feed pump: SSC-3461 pump manufactured by Senshu Kagaku Co. [Measurement conditions]
Solvent: o-dichlorobenzene (containing 0.5 mg / ml BHT)
Sample concentration: 5 mg / ml
Sample injection volume: 0.1 ml
Solvent flow rate: 1 ml / min

3) Measurement of solid viscoelasticity A sample 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 was used. 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: TU-15 injection molding machine manufactured by Toyo Machine Metal Co., Ltd. Setting 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)
Injection pressure: 800 kgf / cm ²
Holding pressure: 800 kgf / cm ²
Holding time: 40 seconds Mold shape: Flat plate (thickness 2 mm, width 30 mm, length 90 mm)

4) DSC
Using a Seiko DSC, take 5.0 mg of sample, hold at 200 ° C. for 5 minutes, crystallize to 40 ° C. at a rate of temperature decrease of 10 ° C./min, and further melt at a rate of temperature increase of 10 ° C./min. The melting peak temperature was Tm (unit: ° C.). DHm was determined from the area of the endothermic curve at the time of temperature increase.

5) GPC
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography (GPC).
Conversion from the retention volume to the molecular weight is performed using a calibration curve prepared in advance with standard polystyrene. The measurement method is the method detailed in paragraph 0041.

6) Calculation of ethylene content According to the method described in detail in paragraphs 0032 to 0036.

7) Heat resistance Using the test piece used for the measurement of solid viscoelasticity, the heat resistance of the block copolymer (A) was evaluated under the following conditions.
Standard number: JIS K7206 (Conforms to the 50 method except that the load is 250 g)
Measuring machine: Fully automatic HDT measuring machine (manufactured by Toyo Seiki)
Specimen shape: 2mm thickness 25mm x 25mm 2 sheets of flat plate Preparation method: Injection molded flat plate is punched into the above shape Adjustment of room temperature: 23 ° C, humidity controlled at 50% humidity for 24 hours Leave as it is (no annealing)
Test weight: 250g
Temperature increase rate: 50 ° C./hour Number of test pieces: 3

[Evaluation of film properties]
1) Heat shrinkage rate (unit:%): Cut into a 10 cm × 10 cm square shape so that one side thereof is parallel to the film flow direction, and this is cut at a predetermined temperature (80 ° C., 90 ° C., 100 ° C.). It was immersed in a water bath heated to 10 seconds. Immediately after the elapse of 10 seconds, the film was immersed in a separately prepared 25 ° C. water bath for 20 seconds, and the length in the direction perpendicular to the film flow direction was measured.
2) Haze (unit:%): The transparency of the obtained stretched film was evaluated by haze measurement. The measuring method was based on JIS K7136-2000.
3) Density: Based on JIS K-7112: 1999, the density of the obtained stretched film was measured by the density gradient tube method.

[Production Example PP-1]
[Polymerization Production Example A-1]
Preparation of prepolymerization catalyst (chemical treatment of ion-exchange layered silicate) In a glass separable flask equipped with a 10-liter stirring blade, 3.75 liters of distilled water, followed by 2.5 kg of concentrated sulfuric acid (96%) Slowly added. 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, 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.
(Drying of ion-exchanged layered silicate) The silicate previously chemically treated was dried by a kiln dryer. Specifications and drying conditions are as follows.
Rotating cylinder: Cylindrical inner diameter 50 mm Heating zone 550 mm (Electric furnace) Speed with rotating blade: 2 rpm Tilt angle: 20/520 Silicate feed rate: 2.5 g / min Gas flow rate: Nitrogen 96 liters / hour Countercurrent drying Temperature: 200 ° C (powder temperature)
(Preparation of catalyst) An autoclave having an internal volume of 16 liters having a stirring and temperature control device was sufficiently replaced with nitrogen. To this, 200 g of the silicate was introduced, 1160 ml of mixed heptane and 840 ml of a heptane solution of triethylaluminum (0.60 M) were added and stirred at room temperature. After 1 hour, the mixture was washed with mixed heptane to prepare a silicate slurry to 2000 ml. 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, 870 ml of (r) -dichloro [1,1′-dimethylsilylenebis {2-methyl-4- (4-chlorophenyl) -4H-azurenyl}] zirconium and 2180 mg (0.3 mM) of zirconium were mixed with 870 ml of triheptane. A mixture obtained by adding 33.1 ml of a heptane solution of isobutylaluminum (0.71 M) and reacting at room temperature for 1 hour was added to the silicate slurry, and after stirring for 1 hour, mixed heptane was added to prepare 5000 ml.
(Preliminary polymerization / washing) Subsequently, the temperature in the tank was raised by 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 by 2400 ml. Subsequently, 9.5 ml of a heptane solution of triisobutylaluminum (0.71 M / L) and 5600 ml of mixed heptane were further added, stirred for 30 minutes at 40 ° C., allowed to stand for 10 minutes, and then 5600 ml of the supernatant was removed. 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 / liter and the Zr concentration was 8.6 × 10 −6 g / L. It 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.
Using this prepolymerized catalyst, a propylene-ethylene block copolymer was produced according to the following procedure.

First Step In the first step, propylene-ethylene random copolymerization was carried out using a liquid phase polymerization tank with a stirrer having an internal volume of 0.4 m ³ . Liquefied propylene, liquefied ethylene, and triisobutylaluminum were continuously fed at 90 kg / hour, 4.2 kg / hour, and 21.2 g / hour, respectively. The hydrogen supply amount was adjusted so that the MFR in the first step became a target value.
Further, the above prepolymerized catalyst was supplied as a catalyst (excluding the weight of the prepolymerized polymer) so as to be 6.9 g / hour. The polymerization tank was cooled so that the polymerization temperature was 45 ° C.
Analysis of the propylene-ethylene random copolymer obtained in the first step revealed that the BD (bulk density) was 0.46 g / cc, the MFR was 2.0 g / 10 min, and the ethylene content was 3.7 wt%. .

Second Step In the second step, propylene-ethylene random copolymerization was performed using a stirred gas phase polymerization tank having an internal volume of 0.5 m ³ . The slurry containing polymer particles was continuously withdrawn from the liquid phase polymerization tank in the first step, flushed with liquefied propylene, and then pressurized with nitrogen and continuously supplied to the gas phase polymerization tank.
The polymerization tank was controlled so that the temperature was 80 ° C. and the total partial pressure of propylene, ethylene, and hydrogen was 1.5 MPa. At that time, the concentration of propylene, ethylene and hydrogen in the total partial pressure of propylene, ethylene and hydrogen was controlled to be 66.97 vol%, 32.99 vol% and 420 volppm, respectively.
Furthermore, ethanol was supplied to the gas phase polymerization tank as an activity inhibitor. The supply amount of ethanol was set to 0.3 mol / mol with respect to aluminum in TIBA supplied along with the polymer particles supplied to the gas phase polymerization tank.
When the obtained propylene-ethylene block copolymer was analyzed, the activity was 8.7 kg / g-catalyst, BD was 0.41 g / cc, MFR was 2.0 g / 10 min, and the ethylene content was 8.7 wt%. Met.

(Granulation)
The following antioxidant and neutralizer were added to the blender to the block copolymer powder obtained in Polymerization Production Example A-1, and the mixture was sufficiently stirred and mixed.
Antioxidant: Tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane (manufactured by Ciba Specialty Chemicals, Inc., Irganox 1010) 0.05 Parts by weight, tris (2,4-di-t-butylphenyl) phosphite (manufactured by Ciba Specialty Chemicals Co., Ltd. Irgafos 168) 0.10 parts by weight neutralizing agent: calcium stearate (manufactured by Nippon Oil & Fats Co., Ltd.) Stearate G) 0.05 part by weight Antiblocking agent: Synthetic silica (Silicia 430 manufactured by Fuji Silysia Co., Ltd.) 0.40 part by weight Lubricant: Oleic acid amide (Neontron manufactured by Nippon Seika Co., Ltd.) 0.30 weight Part

  The copolymer powder to which the additive was added was mixed at 750 rpm with a Henschel mixer at room temperature for 1 minute at room temperature, and then a PCM twin screw extruder manufactured by Ikegai Seisakusho with a screw diameter of 30 mm, screw rotation speed 200 rpm, discharge rate 10 kg / hr, The melted resin is melt kneaded at an extruder temperature of 190 ° C., the molten resin extruded from the strand die is taken out while being cooled and solidified in a cooling water tank, and the strand is cut into a length of about 3 mm and a diameter of about 2 mm using a strand cutter. -The raw material pellet (PP-1) of the ethylene block copolymer (A) was obtained.

(analysis)
Using the obtained PP-1 pellets, TREF, ethylene content, DSC, GPC, solid viscoelasticity, and heat resistance were measured.
Table 4 shows each data obtained by the measurement.
From the measurement results obtained, it can be said that PP-1 satisfies all the requirements as component (A).
Here, in order to show the position of each parameter in the TREF measurement result, an elution curve is illustrated in FIG. In order to show the position of each parameter in the solid viscoelasticity measurement results, FIG. 2 illustrates changes in storage elastic modulus G ′, loss elastic modulus G ″ and loss tangent tan δ with respect to temperature.

[Production Examples PP-2 to 3]
[Polymerization Production Examples A-2 to 3]
In the same manner as in Polymerization Production Example A-1, the polymerization conditions were changed to produce a propylene-ethylene block copolymer. The polymerization conditions and polymerization results are shown in Table 3.
Using the obtained polymer powder, PP-2 to 3 were obtained by the same additive formulation and granulation conditions as in Production Example PP-1. Various analysis results are shown in Table 4.

[Production Example PP-4]
[Polymerization Production Example A-4]
In Polymerization Production Example A-1, polymerization was carried out in the same manner as in Polymerization Production Example A-1, except that only the first step was carried out without carrying out the second step, to produce a propylene-ethylene random copolymer. went. The polymerization conditions and polymerization results are shown in Table 3.
Using the obtained polymer powder, PP-4 was obtained by the same additive formulation and granulation conditions as in Production Example PP-1. Various analysis results are shown in Table 4.

[Production Example PP-5]
[Polymerization Production Example A-5]
(Preparation of solid catalyst component)
2,000 milliliters of dehydrated and deoxygenated n-heptane was introduced into a flask thoroughly purged with nitrogen, and then 2.6 mol of MgCl ₂ and 5.2 mol of Ti (On-C ₄ H ₉ ) ₄ were introduced. The mixture was introduced and reacted at 95 ° C. for 2 hours. After completion of the reaction, the temperature was lowered to 40 ° C., and then 320 ml of methylhydropolysiloxane (20 centistokes) was introduced and reacted for 3 hours. The resulting solid component was washed with n-heptane.
Next, 4,000 milliliters of n-heptane purified in the same manner as described above was introduced into a sufficiently nitrogen-substituted flask, and 1.46 mol of the solid component synthesized above was introduced in terms of Mg atoms. Next, 25 ml of n-heptane was mixed with 2.62 mol of SiCl ₄ , introduced into the flask at 30 ° C. for 30 minutes, and reacted at 70 ° C. for 3 hours. After completion of the reaction, washing with n-heptane was performed. Next, 0.15 mol of phthalic acid chloride was mixed with 25 ml of n-heptane, introduced into the flask at 70 ° C. for 30 minutes, and reacted at 90 ° C. for 1 hour. After completion of the reaction, washing with n-heptane was performed. Next, 11.4 mol of TiCl ₄ was introduced and reacted at 110 ° C. for 3 hours. After completion of the reaction, the solid component (A1) was obtained by washing with n-heptane. The titanium content of this solid component was 2.0 wt%.
Next, the autoclave having an internal volume of 16 liters having a stirring and temperature control device was sufficiently replaced with nitrogen, and 5,000 milliliters of n-heptane purified in the same manner as above was introduced into the solid component (A1 ) Was introduced, and 0.875 mol of SiCl ₄ was introduced and reacted at 90 ° C. for 2 hours. After completion of the reaction, further (CH ₂ ═CH) Si (CH ₃ ) ₃ 0.15 mol, (t-C ₄ H ₉ ) (CH ₃ ) Si (OCH ₃ ) ₂ 0.075 mol and Al (C ₂ H ₅ ) ₃ 0.4 mol was sequentially introduced and contacted at 30 ° C. for 2 hours. After completion of the contact, the solid catalyst component (A) mainly composed of magnesium chloride was obtained by thoroughly washing with n-heptane. The titanium content of this product was 1.8 wt%.
(Preliminary polymerization)
An autoclave with an internal volume of 16 liters equipped with a stirring and temperature control device was sufficiently replaced with nitrogen. Here, 100 g of the n-heptane slurry of the solid catalyst component (A) prepared above was introduced as the solid catalyst component (A), and n-heptane was further introduced to adjust the liquid level to 5000 ml. Next, the temperature in the tank was adjusted to 15 ° C., and 0.1 mol of triethylaluminum / n-heptane solution (10 wt%) was added as Al (C ₂ H ₅ ) ₃ . Thereafter, prepolymerization was performed by supplying propylene at a rate of 50 g / hour for 2 hours. After completion of the prepolymerization, the residual monomer was purged and the solid catalyst was thoroughly washed with n-heptane. After the washing, drying under reduced pressure was performed to obtain a prepolymerized catalyst. The prepolymerized catalyst contained 2.0 g of polypropylene per 1 g of the solid catalyst component.
Polymerization Production Example A-1 except that the prepolymerization catalyst thus obtained was used, and triethylaluminum was continuously fed at 10 g / hour instead of triisobutylaluminum, and the polymerization conditions shown in Table 3 were used. Propylene-ethylene block copolymer was produced in the same manner as described above. The polymerization results are shown in Table 3.
Using the obtained polymer powder, PP-5 was obtained by the same additive formulation and granulation conditions as in Production Example PP-1. Various analysis results are shown in Table 4.

[Production of heat-shrinkable film]
(1) Forming method of unstretched sheet Using a three-layer three-layer T-die connected to an extruder for surface layer-1, an extruder for surface layer-2, and an extruder for intermediate layer-3, Extruder-2 has WFX4T (Propylene / ethylene random copolymer MFR7 melting peak temperature 125.2 ° C. by metallocene catalyst) manufactured by Nippon Polypro Co., Ltd. as the surface layer resin, and Extruder-3 has the intermediate layer resin composition The melt was extruded at 220 ° C., and cooled and solidified with a cooling roll at 15 ° C. to obtain an unstretched sheet having a thickness of 400 microns consisting of three layers. The thickness ratio of the three layers was 1/8/1.
(2) Forming method of stretched film The unstretched sheet is introduced into a tenter furnace, preheated for 30 seconds at the minimum temperature at which it can be stretched, and 30 seconds in the width direction under a temperature atmosphere equivalent to the preheating temperature. The film was stretched 5 times and subsequently annealed at 85 ° C. for 30 seconds while being relaxed by 7.5% in the width direction in the same tenter furnace. A heat-shrinkable film having a draw ratio of 6 times and a thickness of 60 μm was obtained. The obtained heat-shrinkable film was conditioned at 40 ° C. for 1 day to obtain a sample for evaluation.

[Example 1]
Antioxidant: Tetrakis [methylene-3- (3 ′, 5′-di-t-butyl) with respect to 100 parts by weight of a resin mixture composed of 75 wt% PP-1 pellets and 25 wt% Arakawa Chemical petroleum resin (Alcon P125) -4'-hydroxyphenyl) propionate] methane (manufactured by Ciba Specialty Chemicals Co., Ltd., Irganox 1010), 0.05 parts by weight of tris (2,4-di-t-butylphenyl) phosphite (Ciba・ After adding 0.05 parts by weight of Specialty Chemicals Co., Ltd., Irgaphos 168), high-speed mixing at 750 rpm for 1 minute at room temperature with a Henschel mixer, using a PCM twin screw extruder manufactured by Ikegai Seisakusho with a screw diameter of 30 mm , Melt kneading at a screw speed of 200 rpm, a discharge rate of 10 kg / hr, an extruder temperature of 190 ° C., The extruded molten resin from Torandodai, take-off while cooled and solidified in a cooling water bath, to obtain a resin composition by cutting a strand diameter of about 2 mm, a length of about 3mm with a strand cutter.
Using the obtained resin composition as a raw material for the intermediate layer, a three-layer polypropylene heat-shrinkable film was molded by the method described above. The minimum preheating temperature at which stretching was possible was 50 ° C. Table 5 shows the evaluation results of the obtained heat-shrinkable film.

[Example 2]
A three-layer polypropylene heat-shrinkable film was obtained in the same manner as in Example 1 except that PP-1 in Example 1 was replaced with PP-2. The minimum preheating temperature at which stretching was possible was 55 ° C. Table 5 shows the evaluation results of the obtained heat-shrinkable film.

[Comparative Example 1]
A three-layer polypropylene heat-shrinkable film was obtained in the same manner as in Example 1 except that PP-1 in Example 1 was replaced with PP-3. The minimum preheating temperature at which stretching was possible was 55 ° C. Table 4 shows the evaluation results of the obtained heat-shrinkable film.
Since PP-3 had a plurality of tan δ peaks, the transparency was poor. Moreover, the heat shrinkage rate was also inferior.

[Comparative Example 2]
A three-layer polypropylene heat-shrinkable film was obtained in the same manner as in Example 1 except that PP-1 in Example 1 was replaced with PP-4 pellets. The minimum preheating temperature that can be stretched was 60 ° C. Table 4 shows the evaluation results of the obtained heat-shrinkable film.
Since it was not a block copolymer but a random copolymer, the heat shrinkage rate was inferior to that of the examples.

[Comparative Example 3]
The same operation as in Example 1 was conducted except that PP-1 in Example 1 was replaced with PP-5 pellets to obtain a three-layer polypropylene heat-shrinkable film. The minimum preheating temperature that can be stretched was 60 ° C. Table 5 shows the evaluation results of the obtained heat-shrinkable film.
Since PP produced using a Ziegler-Natta catalyst was used, the heat shrinkage ratio was inferior to that of the Examples.

[Comparative Example 4]
Using PP-1 pellets as an intermediate layer raw material, a three-layer polypropylene heat-shrinkable film was formed by the method described above. The minimum preheating temperature at which stretching was possible was 100 ° C. Table 5 shows the evaluation results of the obtained heat-shrinkable film.
Since the alicyclic hydrocarbon resin was not added, the heat shrinkage rate was inferior to that of the example.

[Comparative Example 5]
Antioxidant: Tetrakis [methylene-3- (3 ′, 5′-di-t-butyl) per 100 parts by weight of a resin mixture composed of 40 wt% PP-1 pellets and 60 wt% Arakawa Chemical Petroleum Resin (Alcon P125) -4'-hydroxyphenyl) propionate] methane (manufactured by Ciba Specialty Chemicals Co., Ltd., Irganox 1010), 0.05 parts by weight of tris (2,4-di-t-butylphenyl) phosphite (Ciba・ After adding 0.05 parts by weight of Specialty Chemicals Co., Ltd. (Irgaphos 168) and mixing at 750 rpm for 1 minute at room temperature with a Henschel mixer, it was added to a Ikegai PCM twin screw extruder with a screw diameter of 30 mm. Melt kneading at a screw speed of 200 rpm, a discharge rate of 10 kg / hr, and an extruder temperature of 190 ° C. The molten resin extruded from a strand die, take-off while cooled and solidified in a cooling water bath, to obtain a resin composition by cutting a strand diameter of about 2 mm, a length of about 3mm with a strand cutter.
Using the obtained resin composition as a raw material for the intermediate layer, a three-layer polypropylene heat-shrinkable film was molded by the method described above. The minimum preheating temperature at which stretching was possible was 50 ° C. Table 5 shows the evaluation results of the obtained heat-shrinkable film.
Since the blending amount of the alicyclic hydrocarbon resin exceeded 50 w%, the density was higher than that of the example.

[Consideration by contrast between Example and Comparative Example]
Considering each of the above Examples and Comparative Examples in contrast, the provision of the present invention is achieved using the novel propylene-ethylene block copolymer composition of the present invention that satisfies the respective provisions of the constitution of the present invention. The heat-shrinkable film molded according to the molding conditions to be satisfied is very excellent in transparency and heat-shrinkability, and each provision of the constituent requirements of the present invention that expresses practically low specific gravity is reasonable and experimental data It is understood that this is confirmed.
In Comparative Example-1, since the tan δ peak of the block copolymer (A) is not single, the phase separation structure is taken and the transparency is deteriorated.
In comparative example-2, the case where the random copolymer by a metallocene catalyst was used instead of a block copolymer was shown. Since it is not a block copolymer, it became inferior to heat shrinkability.
In Comparative Example-3, since the block copolymer (A) was not polymerized with a metallocene catalyst, the heat shrinkability deteriorated.
In Comparative Example-4, since the alicyclic hydrocarbon resin was not added, the heat shrinkage rate was inferior to that of the example.
In Comparative Example-5, since the blending amount of the alicyclic hydrocarbon resin exceeded 50 w%, the density was higher than that of the example.
As described above, various properties such as transparency and heat shrinkability are excellent, and a practically sufficient low specific gravity is expressed. Compared to the heat shrinkable film made of the propylene-ethylene block copolymer of the present invention, each comparative example is inferior in quality. However, the characteristics of the polypropylene heat-shrinkable film of the present invention are highlighted.

It is a graph which shows the elution amount curve and elution amount integration of PP-1. It is a graph which shows the solid viscoelasticity measurement of PP-1. It is a graph which shows the solid viscoelasticity measurement of PP-3.

Claims (6)

Molded from a resin composition containing 50 to 95 wt% of a propylene-ethylene block copolymer component (A) and 50 to 5 wt% of an alicyclic hydrocarbon resin component (B), the component (A) is subjected to the following conditions (A A polypropylene-based heat-shrinkable film satisfying -i) to (A-iii), and the component (B) satisfies the following condition (B-i).
(Ai) 30 to 95 wt% of propylene-ethylene random copolymer component (A1) having propylene alone or ethylene content of 7 wt% or less in the first step using the metallocene catalyst, and component (A1) in the second step A propylene-ethylene block copolymer obtained by sequential polymerization of 70 to 5 wt% of a propylene-ethylene random copolymer component (A2) containing less than 3 to 16 wt% of ethylene (A- ii) Melt flow rate (MFR; 2.16 kg 230 ° C.) is in the range of 0.1-30 g / 10 min (A-iii) Temperature-loss tangent (tan δ) obtained by solid viscoelasticity measurement (DMA) In the curve, the tan δ curve has a single peak at 0 ° C. or lower (Bi) the softening point temperature is 110 ° C. or higher and 160 ° C. or lower. The component (A) satisfies the following condition (A-iv), and the polypropylene-based heat-shrinkable film according to claim 1.
(A-iv) A component amount W (Mw ≦ 5,000) of 5,000 or less in the molecular weight of the block copolymer obtained by gel permeation chromatography (GPC) measurement is 0. 8wt% or less The polypropylene-based heat-shrinkable film according to claim 1 or 2, wherein the component (B) satisfies the following condition (B-ii).
(B-ii) one or more alicyclic hydrocarbon resins selected from petroleum resins, terpene resins, rosin resins, coumarone indene resins, and hydrogenated derivatives thereof A polypropylene-based multilayer heat-shrinkable film comprising at least one layer comprising the resin composition for a polypropylene-based heat-shrinkable film according to any one of claims 1 to 3, and stretched at least in a uniaxial direction. The polypropylene-based (multilayer) heat-shrinkable film according to any one of claims 1 to 4 is 1.0 to 1.5 times in the longitudinal direction and 3.3 in the transverse direction by a tenter-type sequential biaxial stretching method. A polypropylene-based heat-shrinkable film obtained by being stretch-molded 0 to 10.0 times. The film for shrink labels, wherein the polypropylene (multilayer) heat-shrinkable film according to any one of claims 1 to 5 is used for shrink label applications.

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