JPH0618893B2 - Dulled polyolefin-based stretched molded product and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a dulled polyolefin-based stretch molding containing a propylene-ethylene block copolymer as a main component, and the surface of the copolymer is a dense rough surface with irregularities. The present invention relates to a product and a manufacturing method thereof.

[Conventional technology]

In general, polypropylene or polyolefin-based uniaxially or biaxially stretched molded products, such as sheets, films, filaments, yarns, hollow containers, etc., having a rough surface, are provided with useful applications, and particularly sheets are used. ， Film is multicolor printing paper ， Tracing paper ，
It is widely used as release paper, information paper (fax paper, thermal paper, overhead paper, etc.), general packaging paper, etc.

Conventionally, as a method for roughening a polyolefin-based stretched molded product, (a) a method of adding a large amount of an inorganic filler such as calcium carbonate, silica, magnesium silicate, or (b) a molded product as a solvent or There were methods such as treating with chemicals to make it dull, and (c) coating a matte coating film. In the method (a), since a large amount of the inorganic filler is added, the fluidity at the time of extrusion is significantly reduced, the screen pack is clogged, the dispersion failure due to the moisture absorption of the inorganic filler, and the stretch molded product. However, there are drawbacks such that foaming is likely to occur inside, and a dense roughened product cannot be obtained.
In both methods (b) and (c), it is necessary to additionally perform post-treatment after manufacturing a stretch-molded product. And (b)
The method requires a process of removing solvents and chemicals,
The coating method of (c) is disadvantageous in terms of cost because it requires equipment investment such as equipment, and has a drawback in that scratches due to abrasion of the coating film occur during use of the product.

In addition, as a method for modifying the surface of a stretched molded product, a film obtained from a composition obtained by blending polypropylene with high density polyethylene or low density polyethylene is laminated, or a film obtained from a propylene-ethylene block copolymer is laminated. Although the film (Japanese Patent Publication No. 57-32954) is known, all of them have drawbacks such that the surface of the molded product is largely roughened and dense irregularities cannot be obtained.

[Problems to be Solved by the Invention]

The present invention solves the above-mentioned drawbacks of the prior art and, without post-processing, has a matte-like stretch drawing with a low gloss due to the dense rough surface of the stretched product itself and having a high gloss. The challenge is to get things.

[Means for Solving the Problems]

As a result of various studies by the present inventors, a propylene-ethylene block copolymer, an ethylene polymer and an amorphous ethylene-propylene polymer, or a composition in which an engraving agent is further blended is melt-extruded and stretched. The inventors obtained the present invention by discovering that the polyolefin-based stretched molded product obtained as described above has an extremely fine and rough surface in a concavo-convex state and is excellent in dull tone aesthetics.

That is, the dulled polyolefin-based stretch-molded product according to the present invention comprises 100 parts by weight of a propylene-ethylene block copolymer and 6 to 30 parts by weight of each polymer and 3 to 20 parts by weight of each polymer. It is characterized in that it is composed of a polymer and an amorphous ethylene-propylene copolymer and is stretched in at least one direction. An engraving agent may be mixed in the molded product.

The method for producing a dulled polyolefin-based stretched molded product according to the present invention comprises 100 parts by weight of a propylene-ethylene block copolymer, a total of 6 to 30 parts by weight, and 3 to 20 parts by weight of each polymer. After the composition prepared by blending the ethylene polymer and the amorphous ethylene-propylene copolymer is molded by a melt extrusion method to prepare a raw sheet,
The sheet is characterized by being stretched at least twice in at least one direction.

In some cases, the above composition may be further blended with an engraving agent and used as a raw material for melt extrusion.

The present invention will be described in more detail below.

The propylene-ethylene block copolymer used in the present invention is not particularly limited with respect to the copolymerization ratio of propylene and ethylene, but the ethylene component concentration is preferably 2 to 20% by weight, and infrared spectroscopy absorbance ratio between 720 cm ^-1 and 731cm ^-1 due to spectrophotometry (A720 / a 730) by the indicated by block index (by later measurement method) is 0.6 or more in the resin melt flow rate (according to later measurement method) is
It is a propylene-ethylene block copolymer of 0.1 to 20 g / 10 min.

The propylene-ethylene block copolymer can be produced by a multi-stage polymerization method, that is, a propylene mixture, for example, ethylene in an amount of 5% by weight or less is used in the first stage polymerization.
In the second stage, a polymerization method is generally used in which the polymerization of ethylene is carried out to complete the polymerization, or the continuous polymerization is repeated, but the polymerization method is not particularly limited. For example, any known method such as JP-A-58-69215, JP-A-55-116716, JP-A-58-29811, and JP-A-57-195718 may be used.

If only a propylene-ethylene block copolymer is used, a dull feeling is insufficient, and a matte-like stretched polyolefin molded article having a low gloss and a high haze, which is a subject of the present invention, cannot be obtained. Therefore, in the present invention, the propylene-ethylene block copolymer is further blended with an ethylene polymer and an amorphous ethylene-propylene copolymer for use.

The ethylene polymer used in the present invention has a density of 0.915 to 0.930.
A commercially available product having a melt flow rate in the range of 1 to 10 g / 10 min may be used. When the melt flow rate is less than 1 g / 10 min, the compatibility with the propylene-ethylene block copolymer is poor and exceeds 10 g / 10 min. And it lacks dull feeling and is not desirable.

The amorphous ethylene-propylene copolymer used in the present invention preferably has a propylene component content of 20 to 23% and a melt flow rate of 0.3 to 5 g / 10 minutes. Outside of this range, the object of the present invention cannot be achieved even in combination with a propylene-ethylene block copolymer or an ethylene polymer.

A dulled polyolefin-based stretched molded product according to the present invention,
Therefore, the composition used in the production is 100 parts by weight of the propylene-ethylene block copolymer, 6 to 30 parts by weight in total, and 3 to 20 parts by weight of each of the ethylene polymer and the amorphous ethylene. A propylene copolymer. If the total amount of the ethylene polymer and the amorphous ethylene-propylene copolymer is less than 6 parts by weight, the effect of imparting dulling is insufficient, and if it exceeds 30 parts by weight, extrusion unevenness and stretch rupture are likely to occur at the time of molding, resulting in stretched molded products. The quality is poor and the productivity is extremely reduced, which is not preferable. The mixing ratio between the ethylene polymer and the amorphous ethylene-propylene copolymer is 3: 7 to 7: 3, which is because a stretch-molded product sufficiently dull is obtained and the productivity is excellent. Particularly preferred.

In the present invention, the compounding of the engraved product is effective in order to obtain a polyolefin-based stretched molded product which is more dense in the uneven state of the molded product surface and is excellent in dulling.

Conventionally, the addition of a nucleating agent to a plastic is generally performed for the purpose of improving the transparency and glossiness of a molded product,
As in the present invention, it has not been compounded in order to make the surface of the molded article have a finely uneven surface.

The nucleating agent used in the present invention may be a known nucleating agent.

For example, sodium benzoate, aluminum benzoate,
Sodium adipate, dibenzylidene sorbetle,
Although there are bisamide compounds and the like, metal salts of cyclic aromatic compounds represented by the following general formula are preferable.

(In the formula, R represents a direct bond or an alkylidene group, and R ₁
And R ₂ each represent a hydrogen atom, an alkyl group or a cycloalkyl group, and M represents a monovalent metal atom.) The amount of the metal salt of the cyclic aromatic phosphorus compound added is propylene-ethylene block copolymer and ethylene. Total of polymer and amorphous ethylene-propylene copolymer (these may be collectively referred to as three types of polymers below) 10
It is 0.005 to 0.15 parts by weight relative to 0 parts by weight, and if the lower limit of this range is not reached, the effect of making the surface of the molded article finely rugged is insufficient, and if the upper limit of this range is exceeded, dispersion in the polymer will occur. When the film is extremely deteriorated, a large number of voids (voids) having this compound as a nucleus are generated due to stretching, which undesirably deteriorates the appearance of the film. 0.01 to 0.05 even in the above addition range
Parts by weight are preferred.

As the nucleating agent, a powdery form containing few impurities and having a uniform particle size and shape and free from aggregation is preferable.

The most preferable nucleating agent is R ₁ , R ₂ in the above general formula.
Are -tC ₄ H ₉ , R is> CH ₂ , and M is Na, and are composed of methylenebis (2,4-di-t-butylphenol) acitrated phosphate Na salt, the average particle size of which is 10 μm or less. It is pulverized, and is effective in the present invention to make the surface of the stretch-molded product finer and finer.

In the polyolefin-based stretch-molded article according to the present invention, and accordingly in the composition for melt extrusion used for its production, various known additives such as a processing stabilizer, an antioxidant, a slip agent, and an anti-oxidant may be added if necessary. A blocking agent, an antistatic agent, etc. may be added.

In order to produce the dulled polyolefin stretch-formed product according to the present invention, first, the composition to be melt-extruded is blended. This composition should be blended in a conventional blender, mixer, etc.
Although it can be easily obtained in a powder form by mixing the raw materials mainly containing the above-mentioned polymers, it is particularly preferable to melt-mix using a extruder, a Banbury mixer or the like to use as a pellet-shaped composition.

The composition thus obtained is formed into a raw sheet by a melt extrusion method, and then uniaxially stretched or biaxially stretched by a known method to obtain a dulled molded article for the purpose of the present invention. The thing is obtained.

This stretching method may be any of known uniaxial stretching methods such as roll stretching, oven stretching and hot plate stretching, or known methods such as simultaneous or sequential biaxial stretching such as tubular stretching and tenter stretching. The temperature condition at that time is not particularly limited.

The original sheet is stretched at least in one direction at least 2 times to obtain a stretch-molded product, which is the object of the present invention.
Simultaneous or sequential biaxial stretching in which high-strength stretching of about 10 to 60 times is performed is particularly preferable.

Thus, the stretch-formed product obtained in the present invention has a gloss of 20% or less and a haze value of 60% or more (each measuring method will be described later). 20% gloss
If the haze value is more than 60% and haze value is less than 60%, there is a feeling of shiny
A stretch-molded product having a dull tone cannot be obtained. Among the stretch-molded products obtained by the present invention, the stretch-molded products having a glossiness of 10% or less and a haze value of 70% or more are particularly preferable because they have a dense rough surface with unevenness and are excellent in dull tone.

The dulled polyolefin-based stretched molded product according to the present invention may be subjected to a surface treatment such as corona treatment or plasma treatment in an atmosphere of air, oxygen, nitrogen or the like, if necessary.

[Examples and comparative examples]

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The method of evaluating the characteristic values used in the following examples and comparative examples was as follows.

(1) Haze: According to ASTM D 1003.

(2) Gloss: According to ASTM D523. (Angle: 20) (3) Melt flow rate (MFR): JIS K7210-1776 (Unit:
g / 10 minutes). However, the propylene-ethylene block copolymer and the amorphous ethylene-propylene copolymer are
230 ° C, 2.16kgf.

For ethylene polymer, the conditions are 190 ° C and 2.16kgf.

(4) Ethylene component concentration and block index: The ethylene component concentration was determined by a calibration curve method from the absorbance at 731 cm ^-1 based on the infrared absorption spectrum measured by a Perkin-Elmer 783 infrared spectrophotometer, and the block index was calculated. Is 72
0 cm ^-1 seeking and absorbance A730 absorbance A720 and 730 cm ^-1, and that the ratio of (A720 / A730) and block index.

(5) Density: According to ASTM D 1505-67.

Examples 1 and 2 Propylene-ethylene block copolymer having MFR of 1.5, ethylene component concentration of 8%, and block index of 0.8 (first
In the table, in the polypropylene polymer column, designated as A), 100 parts by weight of powder are added with 0.1 parts by weight of phenolic antioxidant BHT and 0.1 parts by weight of calcium stearate as general additives. Amorphous ethylene
Propylene copolymer (ethylene concentration 22% by weight, MF
R = 0.7) and ethylene polymer (MFR = 1.6, density 0.91)
8, melting point 108 ° C) was added in the prescribed amount shown in Table 1, mixed with a Henschel mixer, melted and mixed at a temperature of 250 ° C through an extruder, cooled and cut to obtain a pellet-shaped composition. It was

The obtained composition was melt-extruded at a temperature of 250 ° C. using an extruder having a diameter of 40 mm and a T-die having a width of 30 cm, and was rapidly cooled by a mirror surface cooling roll kept at 45 ° C. to be a 0.6 mm-thick unstretched raw fabric sheet. Got

Next, this raw sheet is cut into squares, preheated at a temperature of 151 ° C. for 60 seconds using a Pandagraph type biaxial stretching machine, and then stretched 5 times in both the longitudinal and transverse simultaneous directions at the same temperature. ,
Heat treatment was conducted under tension at the same temperature for 10 seconds to obtain two kinds of biaxially stretched films (Examples 1 and 2) having a thickness of about 24 μm.

Example 3 Methylenebis (2,4-di-t-butylphenol) citrate phosphate N described above as a nucleating agent in the composition of Example 2
A stretched film was obtained in the same manner as in Example 2 except that 0.03 parts by weight of the salt a was used.

Example 4 MFR as a propylene-ethylene block copolymer
1.0, ethylene concentration 12%, block index 1.6 (shown as B in the column of polypropylene polymer in Table 1) except that the blending amount of the amorphous ethylene-propylene copolymer was changed. A stretched film was obtained in the same manner as in Example 1.

Comparative Examples 1 and 2 Only the same propylene-ethylene block copolymer (shown as A in Table 1) similar to that of Example 1 without blending the ethylene polymer and the amorphous ethylene-propylene polymer (Comparative Example 2). Alternatively, a stretched film was obtained in the same manner as in Example 1 except that only a propylene homopolymer having a MAR of 2.5 (shown as C in Table 1) (Comparative Example 1) was used.

Comparative Examples 3 and 4 Changing the blending amount of the amorphous ethylene-propylene copolymer without blending the ethylene polymer (Comparative Example 3), and blending amounts of the ethylene polymer and the amorphous ethylene-propylene polymer. Example 1 except that was changed to outside the scope of the present invention.
A stretched film was obtained in the same manner as in Comparative Example 3 except that
In Comparative Example 4, uniform stretching was impossible, and a film was not obtained.

Table 1 shows the compositions and film characteristics of the compositions of the above Examples and Comparative Examples.

As is clear from Table 1, the stretched films of Examples 1 to 4 have a haze value of 60% or more and a glossiness of 20% or less, and it is understood that the brightness is suppressed. Even by visual observation, all of these films were excellent films having a beautiful and unique dull feeling with no rough feeling due to the roughened surface of the films.

On the other hand, in the case of only the propylene homopolymer of Comparative Example 1, the propylene-ethylene block copolymer was used as in Comparative Examples 2 and 3, but the ethylene polymer and the amorphous ethylene-polymer were used.
In the case where only one of them is blended without adding the propylene copolymer, when the ethylene polymer and the amorphous ethylene-propylene polymer are blended as in Comparative Example 4, the blending amount thereof is outside the range of the present invention. In any of these cases, it can be seen that the object of the present invention cannot be achieved.

〔The invention's effect〕

The polyolefin-based stretched molded product obtained in the present invention has a propylene-ethylene block copolymer as a main component thereof, and an ethylene polymer and an amorphous ethylene-propylene copolymer in a specific ratio thereof, In addition, the surface of the film has a unique dense rough surface due to the inclusion of a nucleating agent, giving it an opaque appearance. For example, in the case of films and sheets, it has a beautiful dull tone. It is useful for a wide range of applications such as release paper, chemical wrapping paper, general wrapping, printing paper, tracing paper, packing material, etc.

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Claims (5)

[Claims] 1. A propylene-ethylene block copolymer of 100 parts by weight and a total of 6 to 30 parts by weight of each polymer and 3 to 20 parts by weight of an ethylene polymer and an amorphous ethylene polymer.
A dulled polyolefin-based stretched molded article, comprising a propylene copolymer and stretched in at least one direction. 2. The dulled polyolefin-based stretched molded product according to claim 1, wherein the molded product contains a nucleating agent. 3. The nucleating agent is a compound represented by the following general formula and the compounding amount thereof is 100 weight% in total of a propylene-ethylene block copolymer, an ethylene polymer and an amorphous ethylene-propylene copolymer. The dulled polyolefin-based stretched molded product according to claim 2, wherein the amount is 0.005 to 0.15 part by weight. (In the formula, R represents a direct bond or an alkylidene group,
₁ and R ₂ each represent a hydrogen atom, an alkyl group or a cycloalkyl group, and M represents a monovalent metal atom. ) 4. A propylene-ethylene block copolymer of 100 parts by weight and a total of 6 to 30 parts by weight of each polymer and 3 to 20 parts by weight of an ethylene polymer and an amorphous ethylene polymer.
A composition in which a propylene copolymer is blended is molded by a melt extrusion method to prepare a raw sheet, and then the sheet is stretched at least twice in at least one direction. Method for manufacturing molded article. 5. The method for producing a dulled polyolefin-based stretched molded article according to claim 4, wherein the composition is further blended with a nucleating agent.