JPH11217469A - Method for improving performance of polyethylene resin and method for processing polyethylene resin thereby - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for improving the performance of a polyethylene resin, whereby the melt tension necessary when a polyethylene resin is molded can be markedly increased, and the molding cycle in molding a polyethylene resin can be improved, and the obtained molding has improved rigidity and transparency and to provide a process for processing a polyethylene resin thereby. SOLUTION: A polyethylene resin is mixed with a polypropylene resin in a weight ratio of the polyethylene resin to the polypropylene resin of 99.9/0.1 to 95/5, and melt-kneaded at a temperature equal to or higher than the melting points of the polyethylene resin and the polypropylene resin, and the obtained mixture is re-molten at a temperature ranging from the melting point of the polyethylene resin to the melting point of the polypropylene resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for improving the performance of a polyethylene resin and a processing method using the same. More specifically, while significantly increasing the melt tension of the melt required for molding and processing the polyethylene resin, improving the molding cycle property when molding the polyethylene resin, and further improving the rigidity of the obtained molded product The present invention also relates to a method for improving the performance of a polyethylene resin capable of improving transparency and a processing method using the same.

[0002]

2. Description of the Related Art High-density polyethylene (HDPE) and low-density polyethylene (LDP) obtained by a high-pressure radical polymerization method
E), polyethylene-based such as linear low-density polyethylene (LLDPE) obtained by copolymerization of ethylene and α-olefin and ethylene / vinyl acetate copolymer (EVA) obtained by copolymerization of ethylene and vinyl acetate Resins are formed into films, sheets, various containers, and the like, and are used very widely. However, the characteristics of polyethylene resins vary greatly depending on the molecular structure.

For example, regarding high-density polyethylene,
Since the molecular structure has a high regularity, the obtained molded body has a high crystal ratio and is a material having high rigidity. Further, the crystallization rate in the cooling process during the forming process is high, and the forming cycle property is good. However, on the other hand, the transparency is extremely poor, and the melt tension of the melt is small due to the linear molecular structure. In many molding processes for polyethylene-based resins, for example, blow molding, sheet molding, calender molding and vacuum, air pressure molding, generally a large melt tension is required for the resin, and in that sense, the processing characteristics of high-density polyethylene are remarkable. Will be lower. In general, for high-density polyethylene, to increase the melt tension of the melt, to increase the molecular weight, broaden the molecular weight distribution, or blend low-density polyethylene obtained by high-pressure radical polymerization method, Further, a technique such as crosslinking of molecular chains by irradiation with a peroxide or an electron beam is employed. However, these methods have the drawbacks, although the intended increase in melt tension is possible. For example, if an attempt is made to increase the melt tension by increasing the molecular weight, the fluidity will deteriorate, and the load on the molding machine will increase during molding, and the productivity will decrease. Further, if the melt tension is increased by widening the molecular weight distribution, the production process becomes complicated and disadvantageous in cost. Furthermore, the method of adding low-density polyethylene lowers the density of the obtained molded product, and impairs the high-rigidity polyethylene characteristic of high rigidity. Further, in the method using peroxide or electron beam irradiation, it is difficult to control the method, which may cause fisheye or the like.

On the other hand, low-density polyethylene and ethylene / vinyl acetate copolymer obtained by high-pressure radical polymerization have a high melt tension due to the presence of long-chain branches in the molecular chain. However, low rigidity due to low density,
Also, impact strength and tear strength are small.

Further, linear low-density polyethylene obtained by copolymerization of ethylene and an α-olefin has a higher impact and tear strength than the above-mentioned low-density polyethylene obtained by a high-pressure radical polymerization method. The rigidity is also low because of the low density, and the melt tension of the melt is low because it has a linear molecular structure like the high-density polyethylene.

As described above, the characteristics of polyethylene resins vary greatly depending on the molecular structure, and at present, each resin is being marketed in accordance with the characteristics of each resin. However, even with these polyethylene-based resins, as their fields of use have expanded, higher performance has been required from the market, and improvements have been made in various ways to meet these demands. I have. In particular, for polyethylene-based resins, the major high-density polyethylene and linear low-density polyethylene excluding low-density polyethylene and ethylene / vinyl acetate copolymer obtained by high-pressure radical polymerization are all linear. It is desired to increase the melt tension of the melt for various molding processes. Furthermore, these high-density polyethylenes and relatively high-density linear low-density polyethylenes have disadvantages such as poor transparency of molded products, and general linear low-density polyethylenes have poor molding cycle properties. There is a need for improvements.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances surrounding polyethylene-based materials.
The problem to be solved by the invention is polyethylene resin,
In particular, it is possible to increase the melt tension of a melt of a polyethylene resin having a linear molecular structure, and in addition, to improve the cycleability at the time of molding and the rigidity and transparency of the obtained molded article. An object of the present invention is to provide a method for improving the performance of a polyethylene resin and a processing method using the same.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, blended a small amount of a polypropylene-based resin with a polyethylene-based resin, and once melted the melting points of both components. By melting and kneading at the above temperature, the cooled product is re-melted at a temperature equal to or lower than the melting point of the polypropylene resin, thereby increasing the melt tension of the melt of the polyethylene resin, and in addition, the molding cycle property at the time of molding. The inventors have found that the crystallization temperature can be increased, which leads to the improvement, and that the rigidity and transparency of the obtained molded product can be improved, and the present invention has been completed.

That is, in the present invention, a polyethylene-based resin (hereinafter, referred to as [A]) and a polypropylene-based resin (hereinafter, referred to as [B]) are expressed by weight fraction [A]: [B] = 9.
9.9: 0.1 to 95: 5, [A]
And after kneading at a temperature equal to or higher than the melting point of [B], [A]
The present invention relates to a method for improving the performance of a polyethylene resin characterized by being remelted at a melting point of not less than the melting point of [B] and a processing method using the same.

Hereinafter, the present invention will be described in detail.

The type of the polyethylene resin [A] used in the present invention is not particularly limited. For example,
Ethylene homopolymer or ethylene and at least one other α
-A copolymer of olefin or diene, or a copolymer of ethylene and a compound having a vinyl group such as vinyl acetate, acrylic acid, and styrene may be used. Further, a low-density polyethylene having a long-chain branch obtained by a high-pressure radical polymerization method may be used. Here, α- to be copolymerized with ethylene
Examples of olefins include propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene,
Examples thereof include 1-olefins having 3 or more carbon atoms such as methyl-1-pentene, 1-octene and 1-decene.
Examples of the diene include 1,3-butadiene, 1,4-hexadiene, and cyclopentadiene.

The method for producing the polyethylene resin [A] is not particularly limited. Conventionally known production techniques, for example, using a Ziegler catalyst, slurry polymerization, high-pressure polymerization, gas phase polymerization, those obtained by solution polymerization and the like, using a metallocene catalyst, such as those obtained by the above polymerization method, Any of them may be used.

On the other hand, as the polypropylene resin [B] in the present invention, those generally used can be used. For example, a propylene homopolymer, a propylene / ethylene random copolymer having an ethylene content of 0.5 to 12% by weight, an ethylene content of 0.5 to 12% by weight,
A propylene / ethylene / α-olefin terpolymer having an α-olefin content of 0.5 to 20% by weight, such as butene, and an impact polypropylene having an ethylene content of 1 to 60% by weight; Resins are used, and one or more of these are used. Among them, propylene homopolymer is preferable.

The melt flow rate (MFR) of the polypropylene resin (B) in the present invention is not particularly limited. However, for [A] having an MFR of 4 g / 10 minutes or less measured at 190 ° C. under a load of 2160 g,
To increase the melt tension of the melt, the MFR of [B]
Is 230 g and a value measured under a load of 2160 g is 8 g /
It is desirable that the time be 10 minutes or less.

The polypropylene resin [B] in the present invention can be obtained, for example, by a conventionally known method using a Ziegler catalyst or a metallocene catalyst.

Here, the effect of improving the performance of the polyethylene resin, which is the object of the present invention, is that the polypropylene resin [B] is added to the polyethylene resin [A] and the weight fraction [A]: [B] = It can be obtained by blending so as to be 99.9: 0.1 to 95: 5. When the content of [B] is less than 0.1% by weight, the desired effect of improving the performance of the polyethylene resin of [A] is not sufficient. On the other hand, when the content exceeds 5% by weight, the desired improvement is obtained. Although part of the effect is achieved, the weight fraction of [B] is 5% by weight.
There is no difference from the effect obtained in the following cases, and further, there is a case where the transparency is worse than that when [B] is not added, or a by-problem such as a deterioration in surface smoothness occurs, which is preferable. Absent.

Further, in the method for improving the performance of the polyethylene resin of the present invention and the processing method using the same, the [A] and [B] are once melt-kneaded at a temperature higher than their melting points, and then the [A] Must be re-melted at a temperature equal to or higher than the melting point and equal to or lower than the melting point of [B]. Once [A] and [B]
Is required to finely disperse a small amount of [B] in [A], and then the melt-kneaded product is melted at a temperature equal to or higher than the melting point of [A] and [B]. The object of the present invention is achieved by re-melting below. Here, if the melt-kneaded material is re-melted at a temperature equal to or higher than the melting point of [B], the effect of improving the performance intended by the present invention is not exhibited.

In the present invention, the polypropylene resin [B] may be used in a differential scanning calorimeter (DSC) to measure
The peak temperature (Tc (PP)) of the peak located at the highest temperature among the exothermic crystallization peaks obtained when the sample is kept at 00 ° C. for 5 minutes and then cooled at a constant rate of 10 ° C./min is 1
When the temperature is 25 ° C. or more, when the above melt-kneaded and cooled product is remelted, even if the melting temperature is equal to or higher than the melting point of [B],
It is preferable because the object of the present invention is achieved to some extent. The upper limit of Tc (PP) is not particularly limited, and basically, the higher the Tc (PP), the more preferable. However,
Tc (PP) obtained by the above method is generally 13
5 ° C. is the upper limit. Here, the polypropylene-based resin having Tc (PP) of 125 ° C. or higher can be obtained by, for example, improving the isotactic stereoregularity. Also, a polypropylene resin composition can be obtained by adding a known crystal nucleating agent represented by a metal benzoate and a commercially available clarifying agent represented by a sorbitol compound to the polypropylene resin.

In the performance improving method of the present invention and the processing method using the same, the polyethylene resin of [A] to be improved is, if necessary, a phenolic resin or a phenolic resin.
Various antioxidants such as phosphites and thioethers, metal salts of fatty acids, metal salts of hydroxy fatty acids, metal salts of alkyl lactic acid, neutralizing agents such as hydrotalcite, benzophenones, benzotriazoles, salicylates, etc. UV absorbers, hindered amine light stabilizers, lubricants, antiblocking agents, antistatic agents, dispersants, face amounts, and the like can be added.

Further, another polyethylene resin or another resin such as polyamide or polyester may be blended with the polyethylene resin [A]. Alternatively, polyethylene which has been cross-linked by addition of a peroxide or electron beam irradiation may be used.

In the process for improving processability and performance of the present invention, the polypropylene resin (B) may be added by any method. However, for ease of handling and improvement in dispersibility, rolls and plastmills are used. Preferred is a method in which [A] and [B] are heated and kneaded at a temperature equal to or higher than their melting points using a suitable kneader such as a single-screw or twin-screw extruder, a kneader, or a Banbury mixer.

The composition comprising the polyethylene resin and the polypropylene resin obtained in this manner can be prepared by a known molding method, for example, injection molding, extrusion molding, compression molding, blow molding, injection blow molding, inflation molding and casting. It is used as a resin molding material applied to molding methods such as molding. The composition of the present invention can also obtain the desired improvement effect by a method in which a highly filled resin is prepared in advance and added at the time of molding or re-kneading, that is, by adding in a so-called master batch. However, the resin temperature during molding must not exceed the melting point of the component [B] unless [B] satisfies claim 2.

[0023]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

The densities, melt flow rates (MFR) and melting points of the polyethylene and polypropylene resins used in Examples and Comparative Examples were measured by the following methods.

Density: JIS K6760 (1981)
The sample was immersed in hot water at 100 ° C. for 1 hour and then allowed to cool to 40 ° C. or less in an atmosphere of 23 ° C. as it was, and a water / isopropyl alcohol mixed system kept at 23 ° C. Was measured using a density gradient tube.

Melt flow rate (MFR): JIS
According to K7210 (1976), in the case of the component [A] and the polyethylene resin used in the comparative example, 1
The measurement was performed at 90 ° C. under a load of 2160 g, and in the case of the polypropylene resin of the component [B], at 230 ° C. under a load of 2160 g.

Melting point: The melting point is measured by a differential scanning calorimeter (DSC).
-7, manufactured by PerkinElmer Co., Ltd.).
Approximately 5 mg in weight from a sheet-shaped sample obtained by compression molding of pellets
Was cut out and packed in a pan for DSC measurement to obtain a sample for measurement. The measurement was performed at 30 ° C to 80 ° C / min.
Brought to 0 ° C. and held at that temperature for 5 minutes before 10 ° C.
The temperature of the endothermic peak located at the highest temperature obtained in the process of cooling to 30 ° C./min, holding at 30 ° C. for 5 minutes, and then raising the temperature to 180 ° C. at 10 ° C./min was defined as the melting point.

Example 1 In Example 1, an ethylene / butene-1 copolymer [A1] was used as the polyethylene resin of the component [A].
[A1] is high density polyethylene, Nipolon hard, grade 4010 manufactured by Tosoh Corporation. This is because the density measured by the above method is 0.963 g / cm ³ and the MFR is
Is 5.5 g / 10 min and the melting point is 136 ° C. A propylene homopolymer [B1] was used as the polypropylene resin of the component [B]. [B1] is Polypropylene, Chisso Polypro, grade K1008 manufactured by Chisso Corporation. This is the MF measured by the above method.
R is 11.0 g / 10 minutes and melting point is 162 ° C. The mixed composition of the two components is as follows: [A1]: [B1] is 9 by weight.
9: 1. Using a single screw extruder with a screw diameter of 25 mm manufactured by Toyo Seiki Co., Ltd., the above mixture of both components was melt-kneaded at a cylinder temperature of 180 ° C., which is a temperature higher than the melting point of both components, at a screw rotation speed of 50 rpm, and extruded. The obtained rod-shaped melt was cut with water to produce pellets. The effect of improving the workability and performance of [A1] by adding [B1] includes the melt tension (MS) of the pellet, the crystallization temperature (Tc) measured by a differential scanning calorimeter (DSC), and the compression of the pellet. Evaluation was made by measuring the tensile modulus (E) and haze of the molded sheet. T
c is an index of the molding cycle property, and by adding [B], Tc caused by the component [A] is higher than that of [A] alone.
If this rises, it corresponds to the improvement of the molding cycle property. The method for each measurement item is described below.

Measurement of Melt Tension (MS) MS was measured using a Capillograph manufactured by Toyo Seiki Co., Ltd. The die used had a capillary diameter of 2.095 mm,
The capillary length is 8 mm. The measurement was performed with a piston descending speed of 10 mm / min and a take-up speed of 10 m / mi.
n. Here, the extrusion-melted and kneaded pellets were measured at 150 ° C., which is lower than the melting point of the component [B].

Measurement of crystallization temperature (Tc) Tc was measured by using DSC-7 manufactured by Perkin Elmer Co., Ltd. A compression molded sheet having a thickness of about 0.2 mm was prepared from the extruded melt-kneaded pellets, and a compression molded sheet having a thickness of about 0.2 mm was formed therefrom.
A small piece of mg was cut out and used as a sample for DSC measurement.
The sheet was compressed at 150 ° C. for 12 minutes at 0.4 MPa, then quickly transferred to a 30 ° C. compression molding machine, where
It was produced by compressing at 4 MPa for 5 minutes. Note that D
The SC measurement was performed at 150 ° C., which is below the melting point of the component [B].
The temperature was maintained for 10 minutes and then cooled at a constant rate of 10 ° C./min. Here, the peak temperature of the peak located at the highest temperature among the endothermic peaks of the component [A] obtained at that time was defined as the crystallization temperature (Tc).

Measurement of Tensile Modulus (E) As in the case of the Tc measurement sample, an ASTM1822 type test piece was punched out of the compression-molded sheet produced at 150 ° C. to obtain a measurement sample. The measurement was performed using a tensile tester manufactured by Orientec Co., Ltd., Tensilon, under the conditions of a distance between chucks of 28 mm and a tensile speed of 20 mm / min. The tensile modulus was determined from the initial gradient of the stress-strain curve obtained at that time.

Measurement of Haze As with the sample for which Tc and E were measured, the sample was melted at 150 ° C., and the produced compression molded sheet was used as a sample for measurement.
The measurement conforms to JIS K7105 (1981),
The measurement was performed using a haze meter manufactured by Nippon Denshoku Industries Co., Ltd.

Table 1 shows the M of Example 1 obtained by the above method.
S, Tc, E, and haze are shown.

Comparative Example 1 Comparative Example 1 is a comparative example of Example 1 and uses [A
1] It is a simple substance. Same as Example 1 except that [B1] was not added. Table 1 shows MS, T of Comparative Example 1.
c, E and haze are shown. This indicates that the addition of [B1] has the desired improvement effect on [A1].

Comparative Example 2 Comparative Example 2 is also a comparative example of Example 1. Except that the melting temperature when measuring MS and Tc was from 150 ° C. to 180 ° C., and the melting temperature when preparing a compression-molded sheet used for measuring E and haze was from 150 ° C. to 180 ° C. This is the same as the first embodiment. The melting temperature of 180 ° C. in this comparative example is higher than the melting point (162 ° C.) of [B1], and is outside the scope of the present invention. Table 1 shows MS, Tc, E, and haze of Comparative Example 2. Here, the results of re-melting of [A1] alone not containing [B1] at 180 ° C. are also shown. From this, when the melt-kneaded product (pellet) of both components is re-melted at a temperature equal to or higher than the melting point of component [B], even if component [B] is blended with component [A], the desired improvement effect is obtained. It turns out that it cannot be obtained.

Comparative Example 3 Comparative Example 3 is also a comparative example of Example 1, and the component [A] contains [A
1] was used. Here, instead of component [B], low-density polyethylene [C1] obtained by a high-pressure radical polymerization method
Was added to [A1]. [C1] is a low-density polyethylene, Petrocene, grade 190 manufactured by Tosoh Corporation. The density measured by the above method is 0.921 g / cm ³ ,
With an MFR of 4.0 g / 10 min, the MFR is almost equivalent to that of [A1]. The mixed composition of [A1] and [C1] was such that [A1]: [C1] was 80:20 by weight.
Example 1 is the same as Example 1 except that 20% by weight of [C1] was added instead of 1% by weight of [B1]. Table 1
Shows MS, Tc, E, and haze of Comparative Example 3. Although MS is almost the same as that of Example 1, the haze is larger than that of Example 1 (poor in transparency). [A
1] It is almost the same as the simple substance, and E is [A] of Comparative Example 1.
1] It is smaller than a simple substance.

Example 2 In Example 2, an ethylene / butene-1 copolymer [A2] was used as the polyethylene resin of the component [A].
[A2] is high density polyethylene, Nipolon hard, grade 2500 manufactured by Tosoh Corporation. This has a density of 0.961 g / cm ³ , an MFR of 8.0 g / 10 min, a melting point of 134 ° C., and a higher MFR (lower molecular weight) than [A1] used in Example 1 as measured by the above method. . The same [B1] as in Example 1 was used as the component [B].
It is the same as Example 1 except that [A1] is changed to [A2]. Table 1 shows MS, Tc, E, and haze of Example 2.

COMPARATIVE EXAMPLE 4 Comparative Example 4 is a comparative example of Example 2 and uses [A
2] It is a simple substance. Same as Example 2 except that [B1] was not added. Table 2 shows MS and T of Comparative Example 4.
c, E, and haze are shown, but [B1] is also used for [A2].
It can be seen that the desired improvement effect is exhibited by the addition of.

Comparative Example 5 Comparative Example 5 is also a comparative example of Example 2, in which the melting temperature when measuring MS and Tc was changed from 150 ° C. to 180 ° C.
Example 2 is the same as Example 2 except that the melting temperature at the time of producing a compression molded sheet used for measuring haze was changed from 150 ° C to 180 ° C. Melting temperature 18 in this comparative example
0 ° C. is a temperature higher than the melting point of [B1] (162 ° C.), and is outside the scope of the present invention. Table 1 shows Comparative Example 5
MS, Tc, E, and haze are shown here, but here [B1]
The results of remelting of [A2] alone at 180 ° C., which does not contain the same, are also shown. From this, when the melt-kneaded product (pellet) of both components is re-melted at a temperature equal to or higher than the melting point of component [B], even if component [B] is blended with component [A], the desired improvement effect is obtained. It turns out that it cannot be obtained.

Comparative Example 6 Comparative Example 6 is also a comparative example of Example 2, and [A2] was used as the component [A]. Here, instead of the component [B], a low-density polyethylene [C] obtained by a high-pressure radical polymerization method is used.
2] was added to [A2]. [C2] is Tosoh Corporation
Low-density polyethylene, petrocene, grade 203
And the density measured by the above method is 0.919 g / cm
^3. MFR is 8.0 g / 10 min, MFR is almost equivalent to that of [A2]. The mixed composition of [A2] and [C2] was such that [A2]: [C2] was 70:30 by weight fraction. Instead of blending 1% by weight of [B1], 3 parts of [C2]
The same as Example 2 except that 0% by weight was blended. Table 2
Shows the MS, Tc, E, and haze of Comparative Example 4. Although MS is almost the same as that of Example 2, the haze is larger than that of Example 2 (poor in transparency), and Tc is that of Comparative Example 4. Is almost the same as [A2] alone, and E is smaller than [A2] alone in Comparative Example 4.

Example 3 In Example 3, an ethylene / butene-1 copolymer [A3] was used as the polyethylene resin of the component [A].
[A3] is high density polyethylene, Nipolon hard, grade 5110 manufactured by Tosoh Corporation. This has a density measured by the above method of 0.960 g / cm ³ , an MFR of 0.9 g / 10 min, a melting point of 137 ° C., and a lower MFR (higher molecular weight) than [A1] used in Example 1. . As the component [B], the same [B1] as in Example 1 was used. It is the same as Example 1 except that [A1] is changed to [A3]. Table 1 shows MS, Tc, E, and haze of Example 3.

Comparative Example 7 Comparative Example 7 is a comparative example of Example 3 and uses [A
3] It is a simple substance. Same as Example 3 except that [B1] was not added. Table 1 shows MS, T of Comparative Example 7.
c, E, and haze, but the addition of [B1]
3] also shows that the intended improvement effect is obtained.

Comparative Example 8 Comparative Example 8 is a comparative example of Example 3, in which the melting temperature when measuring MS and Tc was from 150 ° C. to 180 ° C.
Example 3 is the same as Example 3 except that the melting temperature when producing a compression-molded sheet used for measuring E and haze was changed from 150 ° C to 180 ° C. Melting temperature 1 in this comparative example
80 ° C. is a temperature higher than the melting point of [B1] (162 ° C.), and is outside the scope of the present invention. Table 1 shows MS, Tc, E, and haze of Comparative Example 8. Here, [B
[1] also shows the result of re-melting of [A3] alone at 180 ° C. From this, when the melt-kneaded product (pellet) of both components is re-melted at a temperature equal to or higher than the melting point of component [B], even if component [B] is blended with component [A], the desired improvement effect is obtained. It turns out that it cannot be obtained.

Example 4 In Example 4, the same [A3] as in Example 3 was used as the component [A]. Here, a propylene homopolymer [B2] was used as the polypropylene resin of the component [B].
[B2] is a polypropylene manufactured by Chisso Corporation, Nisso Polypro, grade K1011. This means that the MFR measured by the above method is 1.0 g / 10 min and the melting point is 16
2 ° C. Example 3 except that [B1] was changed to [B2]
Is the same as Table 1 shows MS, Tc, E, and
Although haze is shown, as apparent from comparison with Example 3,
For a component [A] having a low MFR (high molecular weight) such as [A3], the present invention is better if a component [B] having a low MFR (high molecular weight) such as [B2] is added. It can be seen that the intended improvement effect increases.

Comparative Example 9 Comparative Example 9 is a comparative example of Example 4, wherein the melting temperature when measuring MS and Tc was from 150 ° C. to 180 ° C.
Example 4 is the same as Example 4 except that the melting temperature when producing a compression-molded sheet used for measuring E and haze was changed from 150 ° C to 180 ° C. Melting temperature 1 in this comparative example
80 ° C. is a temperature higher than the melting point of [B2] (162 ° C.), and is outside the scope of the present invention. Table 1 shows MS, Tc, E, and haze of Comparative Example 9;
The results when [A3] alone not containing [2] was remelted at 180 ° C. are also shown. From this, when the melt-kneaded product (pellet) of both components is re-melted at a temperature equal to or higher than the melting point of component [B], even if component [B] is blended with component [A], the desired improvement effect is obtained. It turns out that it cannot be obtained.

Example 5 In Example 5, the component [A] was ethylene-hexene-
One copolymer [A4] was used. [A4] is a high-grade α-olefin-based linear low-density polyethylene, Nipolon-Z, grade ZF260-1 manufactured by Tosoh Corporation. The density measured by the above method is 0.935 g / cm ³ , and the MFR is 2 0.0 g / 10 min, melting point 126 ° C. here,
Since the MFR of [A4] is 4 g / 10 minutes or less,
Component [B] has the same low MFR [B2] as in Example 4.
Was used. Example 4 except that [A1] was changed to [A4].
Is the same as Table 2 shows the MS, Tc, E, and
Indicates haze.

Comparative Example 10 Comparative Example 10 is a comparative example of Example 5, and is a single [A4] used in Example 5. Same as Example 5 except that [B2] was not added. Table 2 shows M of Comparative Example 10.
It shows S, Tc, E, and haze. It can be seen that the desired improvement effect is obtained by adding [B2] to a polyethylene resin having a low density such as [A2].

Comparative Example 11 Comparative Example 11 is also a comparative example of Example 5, and is a compression molded sheet used for measuring MS and Tc from 150 ° C. to 180 ° C., and for measuring E and haze. Is the same as Example 5 except that the melting temperature at the time of manufacturing was changed from 150 ° C. to 180 ° C. The melting temperature of 180 ° C. in this comparative example is higher than the melting point (162 ° C.) of [B2], and is outside the scope of the present invention. Table 2 shows MS, Tc, E, and haze of Comparative Example 11, but here also shows the result of re-melting of [A4] alone without [B2] at 180 ° C. Thus, even in a polyethylene resin having a low density such as [A4], when the melt-kneaded product (pellet) of both components is re-melted at a melting point of the component [B] or higher, the component [B] is added to the component [A]. ], The intended improvement effect cannot be obtained.

Comparative Example 12 Comparative Example 12 is also a comparative example of Example 5, and the components [A] and [B]
Are the same [A4] and [B2] as in Example 5. This example is the same as Example 5 except that [A4]: [B2] is set to 94: 6. In this example, the mixing ratio of [A4] and [B2] is out of the claims. Table 2 shows MS, Tc, and
Although E and haze are shown, MS and E are larger than [A4] alone even when [B2] exceeds 5% by weight. However, compared with Example 5 ([A4]: [B2] = 99: 1), MS and E were not large, and the haze was large compared to Example 5 and the transparency was poor. And above all, what cooled [A4] below the melting point of [B2] was cooled (for example, a rod-shaped sample after MFR measurement).
Has a rough surface, which is not preferable as a molding material.

Embodiment 6 Embodiment 6 is an embodiment corresponding to claim 2. Components [A] and [B] have the same [A1] and [B1] as in Example 1.
Was used. However, here, [B1] previously blended with 3000 ppm of aluminum benzoate (hereinafter abbreviated as [B1] Al) is melt-kneaded with [A1] to form pellets. The crystallization temperature (Tc (P) of [B1] measured by the method according to claim 2 by adding 3000 ppm of aluminum benzoate to [B1].
P)) rises from 119 ° C to 128 ° C. [B1]
The Tc (PP) of Al satisfies the requirement of claim 2 that the Tc (PP) is 125 ° C. or higher, and the present embodiment is directed to a melt-kneaded product of both components [A] and [B]. This shows that the desired improvement effect is obtained even when the (pellet) is remelted at a temperature equal to or higher than the melting point of the component [B]. Specifically, the melting temperature when measuring MS and Tc,
And the melting temperature at the time of producing a compression molded sheet used when measuring E and haze is 180 ° C.,
This temperature is higher than the melting point of 164 ° C. of [B1] Al. In addition, here, what mix | blended [B1] which does not mix | blend aluminum benzoate salt with [A1] was 180 degreeC.
The re-melted material is a comparative example, which is the same as the comparative example 2. Table 3 shows M of Example 6 and Comparative Example 2.
S, Tc, E and haze are shown, but Tc (PP) is 125
It can be seen that by using the component [B] having a temperature of not less than 0 ° C., the desired effect can be obtained even if the melt-kneaded product (pellet) of both components is re-kneaded at a melting point of the component [B] or more.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

As described above, the process for improving the processability and performance of the polyethylene resin according to the present invention is intended to improve the melting point which is a disadvantage of the polyethylene resin, especially the polyethylene resin having a linear molecular structure. The melt tension can be remarkably increased, and in addition, the molding cycle property during molding can be improved, and the rigidity and transparency of the obtained molded body can be improved. Therefore, by applying the present improved method, the range of applicable molding methods and molding conditions can be widened, and the molding efficiency in molding the same can be increased. Further, the obtained molded product is also a polyethylene material having an unprecedented performance balance.

Claims (4)

[Claims] 1. A polyethylene-based resin and a polypropylene-based resin, wherein a polypropylene-based resin is blended with a polyethylene-based resin in a weight fraction of polyethylene-based resin: polypropylene-based resin = 99.9: 0.1 to 95: 5. Melt-kneading at a temperature not lower than the melting point of the polyethylene resin and then re-melting at a temperature not lower than the melting point of the polyethylene resin and not higher than the melting point of the polypropylene resin. 2. Among the exothermic crystallization peaks measured when the polypropylene resin is kept at 200 ° C. for 5 minutes using a differential scanning calorimeter and then cooled at a constant rate of 10 ° C./min. The peak temperature of the peak located at a high temperature is 125
The method for improving the performance of a polyethylene-based resin according to claim 1, wherein the method is a polypropylene-based resin having a temperature of not less than ° C. 3. A polyethylene-based resin obtained by mixing a polypropylene-based resin with a polyethylene-based resin in a weight ratio of polyethylene-based resin: polypropylene-based resin = 99.9: 0.1 to 95: 5. A method for processing a polyethylene resin, comprising: melting and kneading at a temperature not lower than the melting points of the resin and the polypropylene resin; re-melting at a temperature not lower than the melting point of the polyethylene resin and not higher than the melting point of the polypropylene resin; 4. A peak located at the highest temperature among exothermic crystallization peaks measured when the sample is held at 200 ° C. for 5 minutes using a differential scanning calorimeter and then cooled at a constant rate of 10 ° C./min. 4. The method for processing a polyethylene resin according to claim 3, wherein a polypropylene resin having a peak temperature of 125 ° C. or higher is used.