JPH05310241A - Hollow molded body - Google Patents

Abstract

PURPOSE:To provide a hollow molded container made of a polyethylene resin with an excellent surface luster, the quality capability of which is not spoiled, and which has an easily recycling suitability (reclaiming property), and which can take the place of a conventional hollow molded container made of a poly (vinyl chloride) resin, etc. CONSTITUTION:The present hollow molded body is a hollow molded container made of a polyethylene resin, of which an ethylene polymer resin compound with a melt flow rate of 1.0-10g/10min, consisting of a mixture of an ethylene homopolymer of which the melt flow rate is 0.1-3.0g/10min, the density of which is 0.940g/cm<3> or higher, the Q value (Mw/Mn) of which is 5-20, or 95-20wt.% of an ethylene-alpha-olefin copolymer, and 5-80wt.% of an ethylene-alpha-olefin copolymer of which the melt flow rate is 3.0-50g/10min, the density of which is 0.935g/cm<3> or less, is used at least as a raw material for the outer surface layer of the hollow molded container made of polyethylene resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene resin hollow molded container having excellent surface gloss. For more details,
The present invention relates to a polyethylene resin hollow molded container having excellent surface gloss without impairing the basic quality performance of the polyethylene resin hollow molded container.

[0002]

2. Description of the Related Art A blow molding method can be mentioned as one of the main molding methods of polyethylene resin. The polyethylene resin molded by such a hollow molding method is used in large quantities as a material for various bottle containers used in the fields of food, cosmetics, medicine and the like. However, such a polyethylene resin has a relatively high crystallization rate, and the pressure is released at the stage of being extruded from the die as a parison from the molten state under pressure in hollow molding. Since the applied pressure is also a relatively low pressure, the resulting hollow molded article tends to have poor surface smoothness. Therefore, the obtained bottle container has insufficient surface gloss, and there is a problem in that its use may be restricted. On the other hand, in recent years, since environmental problems of plastic products have been attracting attention, in the field of application such as the hollow molding container, conventionally, polyvinyl chloride resin (PV
It has been studied to replace C) and other resins that have been used with hollow molded containers made of polyethylene resin, which have excellent recyclability (suitability for recycling) and do not generate chlorine-containing gas. With the increasing environmental problems of plastic products, such demands are increasing.

[0003]

However, when substituting a hollow molding container made of polyethylene resin for a hollow molding container which has been using a conventional polyvinyl chloride resin or other resin having a gloss, in that case, Corresponding surface gloss appearance is also required for the surface of hollow molded containers made of alternative polyethylene resin. Therefore, as a method of improving the surface of such a polyethylene resin hollow molded container, first, a method of forming another resin having an excellent surface gloss in the outermost layer to form a coated multilayer structure can be considered. Such a device for forming a molded article having a multi-layer structure leads to cost increase due to complication of equipment, etc., and materials other than the polyethylene resin used as the material are mixed as foreign matter, so the above recycling When doing
It is not an effective method because the separation means etc. must be taken into consideration. Further, as a modification of the molding apparatus, a method of coating a fluororesin on a die part of the molding machine may be adopted, but not only the effect is insufficient, but there is a problem in terms of durability and the like.

Further, as a method of improving the resin itself used as a raw material, a method of kneading a fluorine resin, a method of blending a polypropylene resin with a specific polyethylene resin (see Japanese Patent Publication No. 62-59646), and By mixing a linear low-density polyethylene resin having a melt flow rate (MFR) of 3.0 g / 10 minutes or less, which has a relatively excellent surface gloss, with the density polyethylene resin, the surface gloss and the surface friction coefficient of the hollow container are reduced. A method (see Japanese Patent Laid-Open No. 3-115341) has been proposed. However, the method of improving the resin itself, although it is possible to recognize the effect of improvement to some extent, there is a problem in the thermal stability at the time of molding, or the strength of the pinch-off portion is apt to decrease, and the resulting molded article also has its use. It is still an incomplete technology because it is restricted by. The method of mixing the linear low-density polyethylene resin has a melt flow rate of 3.0 g /
Since the linear low-density polyethylene resin of 10 minutes or less is used by making the best use of it, although some improvement effect is certainly recognized, the melt flow rate of the mixed linear low-density polyethylene resin is 3 or less. If the amount is less than 0.0 g / 10 minutes, it does not contribute much to the improvement of the surface gloss and the sufficient effect is not obtained at present.

[0005]

[Means for Solving the Problems]

[Summary of the Invention] In view of the above situation, the present inventors have made it possible to recycle a polyethylene resin hollow molding container that does not impair the basic quality performance as a polyethylene resin hollow molding container and is excellent in surface gloss. As a result of earnest studies for the purpose of obtaining a container, generally, when a resin composition having a high melt flow rate is used as a polyethylene resin material used for blow molding, the melt tension at the time of blow molding Since it is expected that this will cause deterioration of drawdown properties and drawdown properties, it is necessary to set conditions of relatively low temperature and high speed on the molding surface, and at the same time, to improve the surface gloss of the resin material surface without impairing the melt properties of these materials. I had to improve it. Therefore, polyethylene resins having a MFR of 1.0 g / 10 min or less are usually used for blow molding. However, surprisingly, an ethylene homopolymer or an ethylene / α-olefin copolymer (A) having a Q value within the range of 5 to 20 is used as one component of the resin composition,
Moreover, the inventors have found that the above object can be achieved by using an ethylene polymer resin composition blended in a specific ratio as a material for the outer surface of a hollow container, and have completed the present invention.

That is, the polyethylene resin hollow molded container of the present invention has a component (A): melt flow rate of 0.1.
To 3.0 g / 10 minutes, density of 0.940 g / cm ³ or more, and Q value (Mw / Mn) of 5 to 20 ethylene homopolymer or ethylene / α-olefin copolymer 95 to 2
0% by weight and component (B): melt flow rate of 3.0 to
The melt flow rate is 1.0 to 10 g / 1, which is a mixture of 50 g / 10 minutes and 5 to 80% by weight of an ethylene / α-olefin copolymer having a density of 0.935 g / cm ³ or less.
The ethylene-based polymer resin composition for 0 minutes is used as a material for at least the outer surface layer of a polyethylene resin hollow molding container.

[Detailed Description of the Invention] [I] Polyethylene Resin Hollow Molded Container (1) Raw Material (a) Constituent Resin Material (Inner Layer) As the resin material constituting the polyethylene resin hollow molded container of the present invention, Basically, the main component is polyethylene resin, except that a specific ethylene-based polymer resin composition described below is used as a material for the outer surface layer of the polyethylene resin hollow molding container. The polyethylene resin is not particularly limited and may be a known polyethylene resin such as ethylene homopolymer or ethylene / α-olefin copolymer. Such a polyethylene resin is generally produced by using ethylene as a raw material and polymerizing alone, or by copolymerizing the ethylene with a comonomer shown below.

<Materials> As a raw material for producing the above-mentioned polyethylene resin, ethylene or a comonomer copolymerizable with the ethylene, specifically, α-olefin can be mentioned. In the case of polymerizing using only ethylene, an ethylene homopolymer, or ethylene and α-
When copolymerizing with an olefin, an ethylene / α-olefin copolymer is obtained. The α-olefin used in the case of producing the ethylene / α-olefin copolymer is represented by the general formula, R-CH = CH ₂ , wherein R in the formula has 1 to 9 carbon atoms. Individual alkyl groups), specifically, propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1,
4-methylhexene-1,4,4-dimethylpentene-
1, heptene-1, octene-1, nonene-1, decene-1 and the like. Among these α-olefins having 3 to 12 carbon atoms, butene-1, hexene-1,
It is preferable to use 4-methylpentene-1 and octene-1. In addition, the α-olefin in this case is not limited to the use of only one type, and may be a multi-component copolymer using two or more types such as a terpolymer. The content of the α-olefin in the ethylene / α-olefin copolymer is generally 0.1 to 20% by weight, preferably 0.1 to 1%.
It is within the range of 0% by weight.

<Polymerization (copolymerization) of ethylene> As a catalyst used in the above catalyst polymerization (copolymerization),
For example, using a compound such as titanium and vanadium as a transition metal component, a Ziegler type catalyst combined with an organoaluminum compound, a Phillips type catalyst using a compound such as chromium, a Kaminsky type catalyst using a compound such as zirconium and hafnium. And can be used by selecting from these catalyst systems. Manufacturing Process The manufacturing process in which the above-mentioned polymerization (copolymerization) is carried out is not particularly limited, and a known gas phase method, solution method, slurry method, or a high temperature of 200 kg / cm ² or higher and 150 ° C. or higher A high temperature / high pressure bulk polymerization method in which polymerization is performed under high pressure can be employed.

(B) Resin Material Constituting Outer Surface (Resin Composition) As the resin material constituting the outer surface layer of the polyethylene resin hollow molding container of the present invention, an ethylene homopolymer of the following component (A) or An ethylene-based polymer resin composition comprising a mixture of an ethylene / α-olefin copolymer and an ethylene / α-olefin copolymer of component (B).

<Component (A)> The ethylene homopolymer or ethylene / α-olefin copolymer of the component (A) constituting the ethylene polymer resin composition has a melt flow rate (MFR) of 0.1. To 3.0 g / 10 minutes, preferably 0.1 to 2.0 g / 10 minutes, and a density of 0.940 g / cm ³ or more, preferably 0.945.
~ 0.970 g / cm ³ and further GPC
Weight average molecular weight (Mw) and number average molecular weight (M
It is important to use a material having a Q value, which is the ratio (Mw / Mn) of n), in the range of 5 to 20, preferably 5.5 to 15. If the MFR is less than the above range, the melt viscosity of the ethylene-based polymer resin composition may be increased, and the skin may be easily roughened, and sufficient surface gloss may not be obtained. Further, if the MFR exceeds the above range, the drawdown property deteriorates too much. When the density is less than the above range, the rigidity is deteriorated, buckling is likely to occur, and the use thereof is limited, which is not desirable. Further, if the Q value (Mw / Mn) is less than the above range, it is expected that the melt tension and drawdown property of the ethylene-based polymer resin composition will be lowered, and the critical shear stress will also be low, resulting in high speed. It is also disadvantageous in terms of moldability. On the other hand, when the Q value (Mw / Mn) exceeds the above range, the effect of improving the surface gloss is decreased, and the physical properties of the strength of the container are also decreased, which is not preferable.

<Component (B)> The ethylene / α-olefin copolymer as the component (B) constituting the above ethylene polymer resin composition has a melt flow rate of 3.0 to 50 g / 10.
Min, preferably in the range of 3.0~30g / 10 min, also density of 0.935 g / cm ³ or less, preferably important to use what is in 0.900~0.930g / cm ³ Is. If the melt flow rate is less than the above range, the effect of improving the surface gloss becomes insufficient,
The extrusion load at the time of molding also increases, and it is easy for rough skin to occur. In addition, when the melt flow rate exceeds the above range, the drawdown of the ethylene-based polymer resin composition becomes large, and the strength of the container in terms of physical properties such as wall thickness uniformity and ESCR (environmental stress crack resistance) is also high. May be reduced. If the density exceeds the above range, the effect of improving the surface gloss becomes poor.

<Mixing> Mixing method An ethylene homopolymer or ethylene / α-olefin copolymer as the component (A), which is a resin material constituting the outer surface layer of the polyethylene resin hollow molding container of the present invention, The mixture of the component (B) with the ethylene / α-olefin copolymer gives an ethylene-based polymer resin composition by mixing both components. The mixing method used when producing the present ethylene-based polymer resin composition is not particularly limited, and a known method can be adopted. That is, the above components (A) and (B) are blended in a predetermined amount, mixed with a commonly used mixer such as a Henschel mixer or a super mixer, and then directly subjected to molding, or,
It may be subjected to molding after kneading by a continuous melt kneading method using a single-screw kneader, a twin-screw kneader such as FMC or CIM, or a batch-type melt kneading method such as roll or Banbury. Mixing ratio The mixing ratio of the component (A) and the component (B) constituting the above ethylene-based polymer resin composition is the component (A) (ethylene homopolymer or ethylene / α-olefin copolymer): component
(B) (Ethylene / α-olefin copolymer) = 95% by weight: 5% by weight to 20: 80% by weight, preferably 80: 2
It is 0% to 30: 70% by weight. If the mixing ratio is out of the above range, the effect of improving the surface gloss may be poor, or even if the effect of improving the surface gloss is obtained, the moldability is lowered and the rigidity (buckling) is reduced.
It causes problems such as deterioration.

<Ethylene polymer resin composition> The above components
The ethylene polymer resin composition obtained by mixing the component (A) and the component (B) has a melt flow rate of 1.0 to 10 as the whole ethylene polymer resin composition.
It is important that it is in g / 10 minutes, preferably 2.0-6.0 g / 10 minutes. If the melt flow rate of the ethylene-based polymer resin composition is out of the above range, the effect of improving the surface gloss may be poor, or even if the improving effect is obtained, the moldability and rigidity (buckling) may decrease. It causes trouble.

[II] Hollow Molding <Hollow Molding> A hollow molding method for molding a hollow molding container using the above ethylene polymer resin composition as a raw material is carried out by using a known hollow molding method or a hollow molding apparatus. Can be done. Specifically, it is usually carried out by heating and melting with an extruder type blow molding machine, extruding as a molten parison from a die, then sandwiching this parison with a mold, and blowing air into the parison. ..
However, from the viewpoint of reducing the drawdown, it is desirable to set the conditions at relatively low temperature and high speed.

<Hollow Molded Container> In the polyethylene resin hollow molded container of the present invention, it is important that at least the outer surface of the hollow molded container is formed of the ethylene polymer resin composition. Therefore, the portion other than the outer surface layer of the polyethylene resin hollow molding container may be a hollow molding container having a two-layer structure formed by a normal polyethylene resin layer, or the ethylene / vinyl oxide copolymer may be formed between these layers. Compound, polyamide resin, polyester resin and other multi-layered hollow molding container formed with a resin layer, or a single layer structure in which the entire hollow molding container is formed of a resin consisting of the ethylene polymer resin composition only It may be a hollow molded container. However, from the viewpoint of easy recyclability, it can be said that a hollow molded container having a single-layer structure or a multi-layer structure composed of layers of polyethylene resin is more preferable.

<Composite> Giving Surface Glossiness In order to further enhance the surface glossiness of the polyethylene resin hollow molding container of the present invention, a mica (mica) pearl pigment is prepared by a method such as a masterbatch. It is effective to mix and color to give a pearly feeling. In particular, in the case of a polyethylene resin hollow molded container having a multilayer structure, it is preferable that the outermost surface layer portion formed from the ethylene-based polymer resin composition is not colored and only the inner layer portion is colored with a pearl pigment. is there. Compounding agent In the polyethylene resin constituting the polyethylene resin hollow molded container of the present invention, other than the above components, depending on the purpose of use and application, various additives and compounding agent components that have been conventionally used in this type of field, For example, antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, crosslinking agents, neutralizing agents, antistatic agents, flow improvers, nucleating agents, additives such as optical brighteners, or other organic pigments, A compounding agent such as a colorant such as an inorganic pigment may be added directly or in the form of a masterbatch diluted with a resin or the like and mixed.

Examples of such additives and compounding ingredients include
In particular, a phosphite-based antioxidant, a lubricant such as a higher fatty acid metal salt, or a benzylidene sorbitol-based crystallization nucleating agent can be preferably used together as an additive for the polyethylene resin in the polyethylene resin hollow molding container of the present invention. It is mentioned as a thing. However, in the case of coloring with the mica-made pearl pigment, the mica may be treated with titanium or the like, which may easily cause yellowing after coloring. As an antioxidant, for example, in a phenol system,
3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy}-
1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, tris (3,5)
-Di-t-butyl-4-hydroxybenzyl) isocyanurate, tris (4-t-butyl-2,6-di-methyl-3-hydroxybenzyl) isocyanurate, tetrakis [methylene-3- (3,5-) Di-t-butyl-4
-Hydroxyphenyl) propionate] methane is preferred, especially 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl]-. 2, 4, 8, 1
0-Tetraoxaspiro [5.5] undecane is preferred. In the phosphite system, bis (2,6-di-
t-butyl-4-methylphenyl) pentaerythritol-di-phosphite, 2,2-methylenebis (4,4)
6-di-t-butylphenyl) octyl phosphite,
Tris (2,4-di-t-butylphenyl) phosphite, bis (2,4-di-t-butylphenyl) pentaerythritol-di-phosphite, tetrakis (2,4-di-t-butylphenyl) -4,4'-Vienylene phosphonite, distearyl pentaerythritol diphosphite and the like are preferable, and particularly bis (2,2
6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octylphosphite, tris (2,4-di-) t-butylphenyl)
Phosphite and bis (2,4-di-t-butylphenyl) pentaerythritol-di-phosphite can be mentioned as preferable ones.

[0019]

EXAMPLES In order to describe the coating of the hollow molded container of the present invention in more detail, the examples and comparative examples will be specifically described below. However, the present invention is not limited to these examples. The evaluations in the following examples and comparative examples are measured by the evaluation methods shown below. [I] Evaluation method (1) Melt flow rate (MFR) conforming to JIS-K6760 (190 ° C) (2) Density JIS-K6760 (density gradient piping method) (3) Q value 140 in orthodichlorobenzene solution The Q value was defined as the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) obtained by GPC (gel permeation chromatography) measurement at ° C. (4) Melt tension (MT) Using a Toyo Seiki Capillograph, cylinder temperature 1
The sample was extruded at 90 ° C. at a speed of 10 mm / min, and the extruded sample was guided to a winding roll at a speed of 3.9 m / min, and the take-up tension at that time was measured and used as a measure of drawdown property. .. (5) Surface gloss IHI Corporation "IPB-10A" (screw diameter 40 mm ^phi, the die lip width 1.5 mm) using a 2
Flat hollow bottle with a molding temperature of 00 ° C (internal volume 700c
c, wall thickness 0.5 mmt), and the flat side surface of this flat hollow bottle is cut out to obtain surface gloss at an incident angle of 60 degrees with a Nippon Denshoku Industries Glossmeter according to JIS-Z8741. It was measured. (6) Stiffness Using a 2 mm thick sheet obtained by compression molding at a temperature of 160 ° C., the flexural modulus according to ASTM-D747 was measured and used as a measure of rigidity (buckling).

[II] Experimental Examples Examples 1 to 5 and Comparative Examples 1 to 5 (1) Component (A) As the component (A), a melt flow rate (MFR) of 1.5.
g / 10 minutes, density 0.952 g / cm ³ , Q value (Mw /
Mn) 6.0 (Examples 1, 2, 4 and Comparative Example 1,
3, 4) and a melt flow rate of 0.35 g / 10 minutes,
Those having a density of 0.954 g / cm ³ , a Q value of 7.5 (Examples 3 and 5), and a melt flow rate (MFR) of 2.0.
A g / 10 min, a density of 0.960 g / cm ³ , and a Q value of 3.8 (Comparative Example 2) were used. (2) Component (B) As component (B), melt flow rate (MFR) 20g
/ 10 min, a density of 0.925 g / cm ³ (Examples 1, 2, 3, 4, 5 and Comparative Examples 2, 3, 5), and a melt flow rate of 2.0 g / 10 min, a density of 0. 923g
/ Cm ³ (Comparative Example 1) was used. (3) Mixing of Mica These resins were mixed at the mixing ratios shown in Table 1. In particular, in the case of Example 2, a white mica pearl pigment masterbatch (manufactured by Dainichiseika Co., Ltd.) It was blended so that the final concentration was 2.0% by weight. (4) Mixing The above components were mixed in the mixing ratios shown in Table 1, mixed for 3 minutes with a Henschel mixer, and then pelletized with a single-screw granulator. Then, the pellets were used for flattening hollow bottles (no volume 7) at a molding temperature of 200 ° C. using “IPB-10A” (screw diameter 40 mm ^φ , die lip width 1.5 mm) manufactured by Ishikawajima Harima Heavy Industries Ltd.
00 cc, wall thickness 0.5 mmt) was molded to produce a hollow molded container. The physical properties of this hollow molded container were evaluated according to the above evaluation methods. The results are shown in Table 1.

[0021]

[Table 1]

[0022]

EFFECT OF THE INVENTION The polyethylene resin hollow molded container of the present invention has excellent surface gloss even when ordinary hollow molding at a relatively low pressure is carried out, and has the basic quality performance as a polyethylene resin hollow molded container. Since it is not damaged, it is not restricted in its application. In addition, since the material resin of the container is mainly composed of polyethylene resin, it is excellent in easy recyclability (suitability for recycling) and also in environmental problems. Therefore, it can be used as a substitute for conventional hollow molded containers made of polyvinyl chloride resin (PVC) or other resins, and can be expected to be widely used as various hollow molded containers.

Front page continuation (72) Inventor Higashi Higashi 1 Toho-cho, Yokkaichi-shi, Mie Prefecture Yokkaichi Research Institute Ltd. (72) Inventor Sumio Takahashi 3-2-6 Oshima, Koto-ku, Tokyo Stock company Yoshino Industry

Claims (2)

[Claims] 1. Component (A): having a melt flow rate of 0.1.
3.0 g / 10 minutes, density of 0.940 g / cm ³ or more,
95-20% by weight of an ethylene homopolymer or ethylene / α-olefin copolymer having a Q value (Mw / Mn) of 5-20, and component (B): a melt flow rate of 3.0-50
Ethylene polymer having a melt flow rate of 1.0 to 10 g / 10 minutes, which is composed of a mixture of 5 to 80% by weight of an ethylene / α-olefin copolymer having a density of g / 10 minutes and a density of 0.935 g / cm ³ or less. A hollow molding container made of polyethylene resin, characterized in that the resin composition is used as a material for at least an outer surface layer of the hollow molding container made of polyethylene resin. 2. The polyethylene resin hollow molded container according to claim 1, wherein at least a part of the layer of the polyethylene resin hollow molded container is colored with a mica pearl pigment.