JP2649619B2 - High gloss multilayer hollow container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high gloss multi-layer hollow container, and more particularly to a high gloss multi-layer hollow container having excellent surface gloss and good moldability.

[0002]

2. Description of the Related Art Polypropylene resins are widely used in blow-molded hollow containers because they have many excellent properties such as rigidity, impact resistance, heat resistance, hygiene, water vapor permeability and moldability. However, on the other hand, it has the drawback of poor gas barrier properties such as oxygen, nitrogen, and carbon dioxide gas.For food containers such as soft drinks, seasonings, and edible oils, the inner and outer layers are made of polyolefin resin, and the intermediate layer is made of gas barrier properties. A large number of hollow containers having a multilayer structure using a good resin, for example, an ethylene-vinyl alcohol copolymer or a polyamide resin, are used. However, the gloss of a multilayer container having a conventional polypropylene resin as a surface layer has not yet sufficiently satisfied the demands of the market where good appearance significantly increases the commercial value, and significant improvement of the surface gloss has been a very important issue. As a solution to such a problem, for example, as described in JP-A-2-215529, it is known that the surface gloss can be improved by using an ethylene-propylene binary random copolymer as the outermost surface layer of a multilayer container. However, in the case of an ethylene-propylene binary random copolymer, as the ethylene content increases, the degree of random bonding of ethylene to the propylene main chain decreases, and the degree of block bonding increases. There is a problem that the degree of improvement in gloss reaches a peak, and for example, a container having a large thickness or a container having a large basis weight has insufficient improvement effect.

[0003]

DISCLOSURE OF THE INVENTION The present invention greatly improves the surface gloss, which is a drawback of conventional polypropylene, and has an appearance which greatly enhances the commercial value, while taking advantage of the excellent properties of polypropylene. An object of the present invention is to provide a hollow container that can be directly blown.

[0004]

The present inventors have conducted various studies to eliminate the drawbacks of the conventional methods and to obtain a hollow container having an excellent surface gloss. The present inventors have found that a directly blown hollow container has extremely excellent gloss, and completed the present invention.

That is, the present invention provides the following “Basic Configuration 1”
And "Improved Configuration 1" to "Improved Configuration 8". [Basic Configuration 1] In a multilayer hollow container composed of a surface layer and an inner layer, a crystal melting point is 110 to 145 ° C, an ethylene content is 3 to 10% by weight, and an α-olefin having 4 or more carbon atoms is 0.5 to 10%.
Weight%, 230 ° C melt flow rate is 2 to 20 g / 1
A high-gloss multilayer hollow container obtained by a direct blow molding method, wherein a multi-component propylene random copolymer (A) having 0 minutes is used for a surface layer. [Improved Configuration 1] In a multilayer hollow container including a surface layer and an inner layer, the multicomponent propylene random copolymer (A) according to Basic Configuration 1 is described.
Crystalline propylene homopolymer 1 to 100 parts by weight
The melt flow rate at 230 ° C containing 30 parts by weight or 1 to 30 parts by weight of a propylene ethylene random copolymer having an ethylene content of 4% by weight or less is 2 to 20 g / 10
A high-gloss multilayer hollow container obtained by a direct blow molding method, wherein the propylene polymer composition (B) is used for the surface layer . [Improved Configuration 2] In a multilayer hollow container comprising a surface layer and an inner layer, the multicomponent propylene random copolymer (A) described in Basic Configuration 1
Alternatively, based on 100 parts by weight of the propylene polymer composition (B) described in Improved Configuration 1, 15 to 0.01 parts by weight of a linear low density polyethylene and 4 to 0.0 parts by weight of a low density polyethylene
230 ° C. melt flow rate of 2 to 20 g containing 1 part by weight or 4 to 0.01 parts by weight of high density polyethylene
/ 10 min propylene polymer composition (C) of the surface layer
A high-gloss multilayer hollow container obtained by a direct blow molding method, which is used for: [Improved Configuration 3] In a multilayer hollow container including a surface layer and an inner layer, a multicomponent propylene random copolymer (A) described in Basic Configuration 1, a propylene polymer composition (B) described in Improved Configuration 1 or an improved Nucleating agent (E) 0.05 per 100 parts by weight of propylene polymer composition (C) according to constitution 2
A propylene polymer composition (D) having a melt flow rate of 2 to 20 g / 10 minutes containing 230 parts by weight of a propylene polymer composition (D) is used for a surface layer, and a high flow rate obtained by a direct blow molding method. Luster multilayer hollow container . [Improved Configuration 4] The high gloss multilayer hollow container according to Improved Configuration 3, wherein the nucleating agent (E) is a benzylidene sorbitol nucleating agent.

[0006] Multi-component propylene run used in the present invention
The dam copolymer (A) is obtained by randomly copolymerizing propylene as a main component and ethylene and an α-olefin having 4 or more carbon atoms, and has a crystal melting point (hereinafter sometimes abbreviated as Tm).
Is in the range of 110 to 145 ° C, the ethylene content is in the range of 3 to 10% by weight, and the α-olefin having 4 or more carbon atoms is in the range of 0.5 to 10% by weight. If the ethylene content is less than 3% or the α-olefin having 4 or more carbon atoms is less than 0.5%, the degree of improvement in gloss is small and the object of the present invention is not satisfied. Those having an ethylene content or a content of α-olefins having 4 or more carbon atoms exceeding 10% also have a small gloss improvement degree and do not satisfy the object of the present invention. This many
The α-olefin having 4 or more carbon atoms used in the propylene random copolymer (A) is an α-olefin having 4 or more carbon atoms such as butene-1, 4-methylpentene-1 or hexene-1.
-Means olefin. Multi-component propylene lander of the present invention
The content of ethylene and α-olefin having 4 or more carbon atoms in the copolymer (A) can be measured by infrared analysis or NMR. The melt flow rate at 230 ° C. of the multicomponent propylene / random copolymer A) is preferably 2 to 20 g / 10 minutes.

The multicomponent propylene random copolymer of the present invention
The isomer (A) is prepared by subjecting propylene as a main component, ethylene as a comonomer and an α-olefin having 4 or more carbon atoms to a known polymerization method using, for example, a Ziegler-Natta catalyst or a known highly active catalyst such as a reduced or supported catalyst. , By slurry polymerization, solution polymerization, or gas phase polymerization. The production itself of the multi-component propylene random copolymer used in the present invention is not novel, for example, the method described in JP-B-3-10648, titanium trichloride, using a catalyst containing an organic aluminum compound, n-hexane, hydrogen Concentration (0.2-10 mol%), ethylene (0.1-4 mol%), phthalene-1
(1 to 30 mol%), Fluorene is continuously fed to the polymerization vessel at a temperature of 40
-80 ° C, pressure 5-20 kg / cm ² G, reaction for 1-10 hours, ethylene content 3-10 wt%, butene content 0.5-20 wt%, crystal melting point 110-145 ° C and A multicomponent propylene random copolymer having a melt index of 2 to 20 g / 10 minutes can be produced. The melt flow rate can be adjusted by a known amount of hydrogen added.

The crystal melting point (Tm) is an endothermic curve accompanying melting of a crystal obtained by heating a 10 mg sample at a rate of 20 ° C./min in a nitrogen atmosphere using a scanning differential calorimeter. Shows the peak temperature. Those having a crystal melting point of more than 145 ° C are not suitable for the high gloss multilayer hollow container of the present invention because of insufficient gloss. If the crystal melting point is lower than 110 ° C., the molded product is difficult to release from the mold during molding, which increases the rejection rate and lowers the productivity. Generally, a propylene random copolymer has a reduced crystal melting point when the content of a comonomer component such as ethylene increases, and for example, varies slightly depending on the randomness of the copolymer, but the ethylene component in the copolymer is approximately If it exceeds 4% by weight, the crystal melting point will be 140 ° C. or less.

Specific examples of the multi-component propylene random copolymer used in the present invention include a crystalline melting point Tm of 120 to 1
A propylene terpolymer having an ethylene content of 3 to 10% by weight and a butene-1 or hexene-1 content of 3 to 6% by weight at 35 ° C. is exemplified. Above all, melting point Tm is 120-135 ° C
And those having a 230 ° C. melt flow rate of 3 to 18 g / 10 minutes are particularly preferred.

In addition, propylene copolymerized in a block
The melting point Tm of the ethylene block copolymer is such that the main peak is 15
There is a small minor peak above 0 ° C and in the range of 110-130 ° C. In the case of such a block copolymer having a melting point of more than 140 ° C., the gloss of the multilayer hollow container is extremely reduced, which is not suitable for the purpose of the present invention.

The linear low-density polyethylene blended in the present invention.
Down is, those skilled in the art (Linear Low density Polyethylene (LLD
PE) is a polyethylene copolymer containing ethylene as a main component and copolymerizing an α-olefin such as butene-1 and hexene-1 using a Ziegler-Natta catalyst or the like, among which a density of 0.915 to 0.935 Those having a 190 ° C. melt flow rate of 0.5 to 50 g / 10 minutes at g / cm ³ are particularly preferred. The amount of linear low-density polyethylene is multi-component
Pyrene random copolymer (A) 100 parts by weight, 0.0
The range is 1 to 15 parts by weight, preferably 0.05 to 10 parts by weight, and more preferably 0.1 to 3 parts by weight. 0.01
If the amount is less than 15 parts by weight, the effect of improving gloss is insufficient. If the amount is more than 15 parts by weight, the opaque feeling of the linear low-density polyethylene increases, and the appearance is impaired.

The low-density polyethylene used in the present invention
Emissions are produced by high-pressure density 0.915~0.935g / cm
³ is preferred, and especially 190 ° C melt flow rate is 0.1.
Particularly preferably, the density is 5 to 30 g / 10 min and the density is 0.915 to 0.925 g / cm ³ . High-density polyethylene used in the present invention, the density in those produced in the intermediate and low pressure using a high activity catalyst such as a Ziegler-Natta catalyst or a known reducing system or supported is 0.945~0.970g / cm ³ as Those having a 190 ° C melt flow rate of 0.5 to 30 g / 10 minutes are particularly preferred. The blending amount of low-density polyethylene or high- density polyethylene depends on the multicomponent propylene random copolymer (A).
0 parts by weight, 0.01 to 4 parts by weight, preferably 0.3
When it is less than 0.01 part by weight, the gloss improving effect is insufficient, and when it exceeds 4 parts by weight, the cloudiness of low-density polyethylene and high-density polyethylene increases, the appearance is impaired, and it is preferable as a high-gloss multilayer container. Absent.

The composition used for the surface layer of the high-gloss multilayer hollow container of the present invention includes, in addition to the above-mentioned components, a nucleating agent, an organic nucleating agent and an inorganic nucleating agent such as known talc. A compounding agent can be compounded within a range that does not impair the purpose of the present invention. It can be seen that the effect of improving the gloss is even greater than in this case. However, nucleating agents generally have a peculiar odor,
You may use it in the range which can be used as a hollow container.
The surface layer of the high gloss multilayer hollow container of the present invention, including the inner layer, in addition to the above-described components, antioxidants, weathering agents, ultraviolet absorbers, antistatic agents, various compounding agents of colorants, the purpose of the present invention It can be blended within a range that does not impair. Further, a known thermoplastic resin such as a hydrogenated petroleum resin and an elastomer can be blended in the high gloss multilayer hollow container of the present invention as long as the object of the present invention is not impaired. Furthermore, isotactic polypropylene or a crystalline propylene ethylene copolymer having an ethylene content of 4% by weight or less is used in combination as a base polymer, and two types of linear low-density polyethylene, low-density polyethylene or high-density polyethylene are used. The above can be used in combination without impairing the object of the present invention.

The composition of the surface layer and the inner layer of the present invention can be obtained by mixing the above components. To mix these components,
For example, a conventional mixer such as a tumbler, a Henschel mixer (trade name), a super mixer (trade name), and a high-speed mixer, a ribbon blender, and a tumbler mixer may be used. When melt-kneading is required, an ordinary single-screw extruder or twin-screw extruder is used. The melting and kneading temperature is generally from 160 to 300 ° C, preferably from 230 to 270 ° C. 230 of this composition of the surface layer
C. Melt flow rate is 2-20 g / 10 min. If the melt flow rate is less than 2 g / 10 minutes, the degree of improvement in gloss is insufficient and the object of the present invention is not satisfied. If the melt flow rate exceeds 20 g / 10 minutes, uniform extrusion is difficult and moldability is impaired.

[0016] The inner layer of the high-gloss multilayer hollow container of the present invention comprises 1
This layer is made of a thermoplastic resin such as a polyolefin resin, a polyolefin elastomer, or a gas barrier resin. Known adhesives and adhesive resins can be used between the layers including the surface layer as long as the object of the present invention is not impaired. Of course, the thickness of each layer and the overall thickness are not limited as long as the object of the present invention is not impaired.

The method for obtaining the high-gloss multilayer hollow container of the present invention is a direct blow molding method. As a direct blow molding method, a multilayer parison is melt-extruded using an extruder, and the parison is brought into a blow molding die kept at 50 ° C. or less, and air at a pressure of 5 to 10 kg / cm ^{2 is} blown from an air blowing port, A molding method in which air pressure is applied until the shape is fixed can be exemplified. The multilayer hollow container obtained by these methods is excellent in glossiness and can be used for various uses such as for food, medicine, and general industry.

[0018]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited by these specific examples. The following methods were used to evaluate the characteristics used in the following Examples and Comparative Examples. (1) The crystal melting point (abbreviation Tm in the text) was obtained by using a scanning differential calorimeter (abbreviation: DSC) at room temperature (23 ° C.) at a rate of 20 ° C./min. It is measured and expressed as the peak temperature (unit: ° C) of the endothermic curve accompanying the melting of the crystal. (2) 230 ° C melt flow rate (abbreviated MFR-) is JISK72
The measurement was performed based on Test Condition 14 (230 ° C. 2.16 kgf) of 10 (1976). (Unit: g / 10 min) (3) 190 ° C melt flow rate (abbreviated MFR-) is JISK72
The measurement was performed based on 10 (1976) test condition 14 (190 ° C. 2.16 kgf). (Unit: g / 10 min) (4) The density was measured based on the D method (density gradient tube method) under the test conditions of JIS K7112 (1980). (Unit: g / cm ³ ) (5) The glossiness was measured based on JIS K7105 (1981) test conditions (60-degree specular glossiness). (unit%)

(Examples 1 to 7 Comparative Examples 1 and 2) 0.1 parts by weight of BHT as an antioxidant per 100 parts by weight of various crystalline propylene random copolymer powders having the properties shown in Table 1 as a surface layer material , 0.1 parts by weight of calcium stearate, blended using a Henschel mixer, melt-kneaded with an extruder, and the resulting pelletized composition was supplied to an extruder for a surface layer. MFR-) 1.5 g / 10 min, ethylene-propylene random copolymer having an ethylene content of 3.5 mol% was supplied to an inner layer extruder, and a two-layer molten parison was extruded at an extrusion temperature of 190 ° C. Blow molding was performed in a blow mold at a mold temperature of 30 ° C. to obtain a bottle having a body thickness of 700 μm and an internal volume of 500 cc. The thickness of each layer of this bottle was 100 μm for the surface layer and 600 μm for the inner layer. Table 1 shows the properties of the multilayer hollow container. As is clear from this table, Examples 1 to 7 of the high gloss multilayer hollow container of the present invention are Comparative Examples 1 to 2 (crystalline propylene.
It can be seen that it has a higher glossiness than that of the ethylene binary random copolymer). (Examples 8 to 17 Reference Example 1) Ethylene content 5.0% by weight, butene-1 content 4.5% by weight, Tm 125 ° C, MFR-
Is 4.3 g / 10 min of crystalline propylene random copolymer (PP
-A) 100 parts by weight of powder, and a blending material of polyethylene and a nucleating agent of the type shown in Table 2 and an antioxidant BHT 0.1
Parts by weight, 0.1 part by weight of calcium stearate,
The mixture was blended using a Henschel mixer and melt-kneaded by an extruder to obtain a pellet-shaped composition. The melt flow rate at 230 ° C. was measured, and the results are shown in Table 2. This composition was supplied to a surface layer extruder, and MFR- was 1.5 g / 1 as an inner layer.
0 minutes, an ethylene / propylene random copolymer having an ethylene content of 3.5% by weight was supplied to the inner layer extruder, and the extrusion temperature was increased.
A two-layer molten parison was extruded at 190 ° C., and the parison was blow molded in a blow mold at a mold temperature of 30 ° C. to form a multilayer hollow container having an average body thickness of 700 μm and an internal volume of 500 ml. The thickness of each layer of this container is 100μ for the surface layer and 600μ for the inner layer.
μ. Table 2 shows the characteristics of the multilayer hollow container.
As can be seen from the table, Examples 8 to 17 of the multilayer hollow container according to the present invention have high gloss. Example 17 is obtained by adding 0.2 parts by weight of a nucleating agent dibenzylidene sorbitol which can provide excellent transparency and gloss to various injection-molded articles to the composition of Example 8, and thus further adding a nucleating agent. It can be seen that the effect of improving the glossiness is further improved. However, the nucleating agent generally has a peculiar odor, and its use as a hollow container is sometimes limited. Reference Example 1
Has a large number of linear low-density polyethylenes, so that it becomes cloudy and has insufficient gloss.

Examples 18 to 21 Comparative Examples 3 to 6 A linear low-density polyethylene and BHT as an antioxidant were added to 100 parts by weight of the propylene random copolymer shown in Table 3.
0.1 part by weight of calcium stearate and 0.1 part by weight were blended by using a Henschel mixer, melt-kneaded by an extruder, and cooled and cut to obtain a pellet-shaped composition. Using this composition as a raw material for the surface layer, Table 3 shows the characteristic values of the hollow container obtained by the same multilayer hollow molding method using the same material for the inner layer as in Example 1. As can be seen from Table 3, the claimed embodiments of the present invention each have significantly improved gloss. On the other hand, a crystalline propylene / ethylene binary random copolymer (Comparative Examples 3 to 6) having an ethylene content of 6.7% by weight, a Tm of 131 ° C., and an MFR of 4.5 g / 10 minutes, which is out of the claims, or In the case of a compounded material obtained by adding a linear low-density polyethylene to the above, the effect of improving gloss is inferior, and the object of the present invention is not achieved.

Examples 22 to 27 Reference Examples 2 to 3 The crystalline propylene random copolymer (PP-A), which is the base polymer shown in Example 8, had an MFR- of 4.3 g / 10 min.
950 g / cm ³ of density polyethylene (PE-1) 0.1,1.0,3.
0 ° C and 5 parts by weight of each material or base polymer, 190 ° C melt flow rate (MFR-
) Is 2.0 g / 10 min, a material obtained by blending 0.1, 1.0, 3.0 and 10.0 parts by weight of low density polyethylene (PE-2) having a density of 0.922 g / cm ³ , respectively. Table 4 shows the characteristic values of the hollow container obtained by using the composition as the material for the surface layer and using the same material for the inner layer as in Example 1 and by the same multilayer blow molding method. As a result, Examples 22 to 24 were obtained.
As shown in the above, when the amount of the high-density polyethylene is 0.1 to 3.0 parts by weight, the gloss is clearly improved with respect to the blank. In Reference Example 2, a feeling of white turbidity peculiar to high-density polyethylene is observed. Similarly, in Examples 25 to 27 in which low-density polyethylene is blended, a hollow container having high gloss can be obtained if the addition amount is 0.1 to 3 parts by weight. At 10 parts by weight of Reference Example 3, clouding progressed.

(Examples 28 to 32) As a base polymer, a crystalline propylene / α-olefin random having an ethylene content of 5.0% by weight, butene-1 of 4.5% by weight, a Tm of 125 ° C. and an MFR of 4.3 g / 10 minutes was used. 100 parts by weight of copolymer (PP-A) and M
FR-9.5g / 10min isotactic homopolypropylene (PP-E) or ethylene content 2.5% by weight, Tm147
℃, MFR-7.5 / 10 minutes crystalline propylene ethylene 2
1 part by weight of linear low-density polyethylene (LL-1) in a combined system of 19 parts by weight of the original random copolymer (PP-F), or an ethylene content of 5.0% by weight and butene-1 of 4.5% by weight %, Tm 125 ℃, MFR- 4.3g / 10min crystalline propylene / α-olefin ram copolymer (PP-A) powder 99 parts by weight low density polyethylene (PE-2) and high density polyethylene (PE- 1)
In each case, or a composition in which 0.5 parts by weight of a linear low-density polyethylene and 0.5 parts by weight of a high-density polyethylene are blended into pellets according to the method shown in Example 1. Table 5 shows the characteristic values of the hollow containers obtained by the same multilayer hollow molding method using the same inner layer material as in Example 1 as the raw material. As is clear from this table, the base polymer can be used in combination with the unclaimed polymer as long as the gloss of the present invention is not impaired. Alternatively, by using a combination of high-density polyethylene and linear low-density polyethylene or the like, it has extremely excellent gloss and is suitable as a high-gloss multilayer hollow container.

[0023]

EFFECT OF THE INVENTION Ethylene / propylene 2
A multilayer hollow container using a base random copolymer is inferior in the effect of improving the surface gloss, and a container having a large basis weight cannot satisfy the demand for good appearance in the market and cannot be said to be sufficient. The high-gloss multilayer hollow container of the present invention is extremely superior in glossiness as compared with the conventional polypropylene-based multilayer hollow container, and can achieve a glossiness exceeding 100%, and is desired to have good appearance and clean feeling. It is extremely useful for pharmaceutical containers, food containers, etc., and general industrial uses.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location // B29K 23:00 B29L 22:00

Claims (5)

(57) [Claims] 1. A multilayer hollow container comprising a surface layer and an inner layer, wherein the crystal melting point is 110 to 145 ° C., the ethylene content is 3 to 10% by weight, the α-olefin having 4 or more carbon atoms is 0.5 to 10%. Wt%, 230 ° C melt flow rate is 2
A high-gloss multilayer hollow container obtained by a direct blow molding method, wherein a multi-component propylene random copolymer (A) having a weight of up to 20 g / 10 minutes is used for a surface layer. 2. In a multilayer hollow container comprising a surface layer and an inner layer, 1 to 30 parts by weight of a crystalline propylene homopolymer with respect to 100 parts by weight of the multicomponent propylene random copolymer (A) according to claim 1. Or a propylene ethylene random copolymer having an ethylene content of 4% by weight or less
230 ° C melt flow rate of 2 to 2 parts by weight
Propylene polymer composition is 0 g / 10 min (B) Table
A high gloss multilayer hollow container obtained by a direct blow molding method characterized by being used for a face layer . 3. A multilayer hollow container comprising a surface layer and an inner layer, wherein the multicomponent propylene random copolymer (A) according to claim 1 or the propylene polymer composition (B) according to claim 2 is 100% by weight. Parts by weight, linear low-density polyethylene 15 to 0.01 parts by weight, low-density polyethylene 4 to
0.01 parts by weight or high density polyethylene 4 to 0.0
230 ° C. melt flow rate containing 1 part by weight is 2 to
The propylene polymer composition (C), which is 20 g / 10 minutes, is
A high gloss multilayer hollow container obtained by a direct blow molding method, which is used for a surface layer . 4. A multilayer hollow container comprising a surface layer and an inner layer, wherein the multicomponent propylene random copolymer (A) according to claim 1, the propylene polymer composition (B) according to claim 2, or Item 3. A nucleating agent (E) of 0.05 to 100 parts by weight of the propylene polymer composition (C) according to Item 3
A high gloss obtained by a direct blow molding method, wherein a propylene polymer composition (D) containing 0.4 parts by weight and having a melt flow rate of 230 ° C. of 2 to 20 g / 10 minutes is used for a surface layer. Multi-layer hollow container . 5. The high gloss multilayer hollow container according to claim 4, wherein the nucleating agent (E) is a benzylidene sorbitol nucleating agent.