JPH0741524A - Polyethylene/amino acrylate film and production thereof - Google Patents

Abstract

PURPOSE:To obtain a film which is satisfactory in film strength and heat sealability and has high transparency. CONSTITUTION:The film is made from a polyethylene/amino acrylate graft copolymer obtained by grafting 0.1-20 pts.wt. aminoalkyl acrylate represented by the formula (wherein R1 is hydrogen or methyl; R2 and R3 each is hydrogen or a 1-4C alkyl; and n is an integer of 1-4) onto 80.0-99.9 pts.wt. high-density polyethylene having a density of 0.935g/cm<3> or higher. The film has a haze lower than 20%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene-aminoacrylate graft copolymer film having high strength, excellent transparency and good heat sealability, and a method for producing the same.

[0002]

2. Description of the Related Art Hitherto, as a high density polyethylene film having transparency, there has been a high density polyethylene film having a relatively low molecular weight and a narrow molecular weight distribution. This film was produced by inflation-molding polyethylene and then rapidly cooling it, but it had a problem of poor strength.

To address this problem, the present inventors have
In Japanese Patent Application No. 60-262672, the density is 0.935 g.
/ Cm ³ or more of high-density polyethylene, inflation-molded raw film having a blow ratio of 3 or more is passed between three or more heating rolls under a predetermined temperature condition to be heat-treated at a draw ratio of 5 times or less, and then A high density polyethylene film having a haze value of less than 10% obtained by cooling was proposed.
However, although this film has excellent gas barrier properties, high strength, and excellent transparency, it has poor heat-sealing properties, and there is a complaint that it takes a long time at a high temperature for heat-sealing. Further, although this film is excellent in strength, there was a complaint that the impact strength could not be sufficiently improved.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to obtain a film having good film strength and heat sealability and high transparency.

[0005]

[Means for Solving the Problems] The above problem is 0.935.
High-density polyethylene 8 with a density of g / cm ³ or more
General formula in 0.0 to 99.9 parts by weight

[Chemical 3] (Wherein R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are hydrogen or an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 4). A polyethylene-amino acrylate graft copolymer film formed by grafting 1 to 20 parts by weight and having a haze value of less than 20% is solved by a polyethylene-amino acrylate graft copolymer film. Hereinafter, the present invention will be described in detail.

As the high-density polyethylene (hereinafter abbreviated as high-density PE) used in the present invention, various kinds can be used as long as they contain ethylene as a unit and have a density of 0.935 g / cm ³ or more. it can. Specifically, homopolymers of ethylene, ethylene and other monomers (eg, propylene, butene-1, hexene-1)
Etc.) or a copolymer composed of ethylene and a prepolymer composed of two or more kinds of monomers.

This high density PE has a density of 0.935 g /
It must be at least cm ³ . Density is 0.935
If it is less than g / cm ³ , the resulting film will have poor properties as a high-density polyethylene film, such as waist strength (Young's modulus) and gas barrier property (moisture resistance).

The polyethylene-aminoacrylate graft copolymer according to the present invention has a high density PE of 80.0 to 99.
9 parts by weight of aminoalkyl acrylate compound 0.1
˜20 parts by weight is grafted. When the amount of the high-density PE is less than 80.0 parts by weight, the tensile strength of the film is low, and when it exceeds 99.9 parts by weight, the heat sealing property and the impact strength are poor.

It is desirable that the high-density PE has a melt index of 1.0 g / 10 minutes or less, preferably 0.5 g / 10 minutes or less, and more preferably 0.1 g / 10 minutes or less. As the melt index increases, the strength of the film tends to decrease.

The aminoalkyl acrylate compound used in the present invention has the general formula

[Chemical 4] R ₁ is hydrogen or a methyl group, and R ₂ and R ₃ are hydrogen or methyl, ethyl, n-
It is an alkyl group having 1 to 4 carbon atoms such as propyl, isopropyl and tertiary butyl. In addition, n represents an integer of 1 to 4, and specific examples of C _n H _2n include methylene, ethylene, trimethylene, tetramethylene, dimethylmethylene, methylethylmethylene, dimethylethylene, methyltrimethylene and the like. Specific examples of the aminoalkyl acrylate compound represented by the above general formula include aminomethyl acrylate, aminoethyl acrylate, amino normal butyl acrylate, N-methylaminoethyl acrylate, N-ethylaminoethyl acrylate and N-isopropylaminoethyl acrylate. , N-tert-butyl ethyl acrylate, N
-N-butylaminoethyl acrylate, N, N-dimethylaminomethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoisopropyl acrylate, N, N-dimethylamino-n-butyl acrylate, N, N -Dimethylaminohexyl acrylate, N, N-diethylaminoethyl acrylate, N, N-di-n-propylaminoethyl acrylate, N, N-diisopropylaminoethyl acrylate, N, N-di-n-butylaminoethyl acrylate, N -Methyl-N-ethylaminoethyl acrylate, N-methyl-Nn-butylaminoethyl acrylate, acrylic acid esters such as N, N-di-n-propylaminopropyl acrylate, and corresponding methacrylic acid ester It can be and listed.
Among the methacrylic acid esters, N, N-diethylaminoethyl methacrylate and N, N-dimethylaminoethyl methacrylate are preferable.

The polyethylene-aminoacrylate graft copolymer film of the present invention is a film obtained by reacting the above high-density PE and aminoalkyl acrylate compound in the presence of an organic peroxide directly in an extruder installed in a film forming machine. It can be manufactured by performing molding at the same time, and this method is also excellent in economic efficiency. As another method, a polyethylene-aminoacrylate graft copolymer is produced by using a kneading machine such as an extruder or a Banbury mixer, a radiation irradiation device, or the like, and film-forming is performed using a normal film-forming machine. May be.

Examples of the organic peroxide include benzoyl peroxide, lauryl peroxide, azobisisobutyronitrile, dicumyl peroxide and t.
-Butyl hydroperoxide, α, α'-bis (t-
Butyl peroxydiisopropyl) benzene, di-t-
Butyl peroxide, 2,5- (t-butylperoxy) hexine and the like are preferably used.

The total amount of the high-density PE and the aminoalkyl acrylate compound is 100 parts by weight, and 0.005
It is used in an amount of up to 2.0 parts by weight, preferably 0.01 to 1 part by weight. If the amount of the organic peroxide added is less than 0.005 parts by weight, the modifying effect is not substantially exerted, and even if it is added in excess of 2.0 parts by weight, it is difficult to obtain further effects, and This may cause excessive decomposition or crosslinking reaction. The organic peroxide is decomposed by heating during the production of the polyethylene-aminoacrylate graft copolymer (hereinafter, sometimes simply referred to as a copolymer), and a part thereof is taken out of the copolymer and a part thereof is taken into the copolymer. It is considered difficult to accurately define the amount in the copolymer.

The grafting reaction and the film forming temperature for obtaining the above polyethylene-aminoacrylate graft copolymer are appropriately selected in consideration of the usual temperature conditions, that is, the deterioration of the resin, the decomposition temperature of the organic peroxide and the like. Generally, reaction temperatures in the range of 150 ° C to 250 ° C are used.

If necessary, stabilizers, antistatic agents, colorants such as pigments, and other additives are added to the polyethylene-aminoacrylate graft copolymer according to the present invention within a range not impairing the object of the present invention. can do. This addition may be made at the time of film formation or at the time of producing the polyethylene-aminoacrylate graft copolymer.

The polyethylene-aminoacrylate graft copolymer film of the present invention is formed by various known methods. For example, the air-cooled inflation method, the water-cooled inflation method, the T-die method and the like are suitable because the graft reaction is carried out in the extruder, and the air-cooled inflation method is particularly preferable.

The production of the air-cooled blown film can be carried out in an air-cooled blown film manufacturing apparatus, for example, high density PE, an aminoalkyl acrylate compound and an organic peroxide are mixed to obtain 150 to 250.
It is extruded through a circular die from an extruder at a temperature of ℃, brought into contact with the air blown out from an air-cooled air ring to be rapidly cooled, solidified and taken up by a pinch roll, and then wound on a frame. By this method, it is possible to simultaneously improve the transparency, strength and heat sealability of the air-cooled blown film, which has been difficult to solve at the same time.

Of course, in addition to the air-cooled inflation film, a water-cooled inflation film and a T-die method film can be produced, and a film having good transparency can be obtained.

The thickness of the polyethylene-aminoacrylate graft copolymer film of the present invention is 10 to 20 μm, more preferably 30 to 100 μm from the viewpoint of ease of use.
It is desirable that it is about m.

A haze value of 2 is obtained by the above manufacturing method.
A polyethylene-amino acrylate graft copolymer film having an excellent transparency of less than 0% can be obtained. The haze value is measured according to ASTM D1003. Further, in the present invention, the haze value indicates a numerical value obtained by summing the external haze value and the internal haze value.

[0021]

The polyethylene-amino acrylate graft copolymer film of the present invention has a particle size (L = 100 to 110Å) of an aggregate of crystalline lamellas protruding in an irregular shape on the surface.
However, it has a feature that it is smaller than the particle size of high-density polyethylene (L = 50 to 60Å), and the film surface can be smoothed to reduce the external haze value of the film. Furthermore, the grain size of the microcrystals inside the film is simultaneously reduced, and the internal haze value of the film can be reduced. Further, such a reduction in crystal grain size and an increase in molecular mobility lowers the melting temperature and develops a low-temperature heat-sealing property. Also,
Since the high-density PE component is 80.0 to 99.9 parts by weight,
High strength, which is an excellent property of the high-density polyethylene film, is retained.

[0022]

[Examples] Examples 1 and 2, Comparative Examples 1 and 2 By the air-cooled inflation molding method, high-density PE and an aminoalkyl acrylate-based compound were reacted in the presence of an organic peroxide directly in an extruder to simultaneously form a film. Molded. As the organic peroxide, benzoyl peroxide was used in an amount of 0.1 part by weight based on 100 parts by weight of the total of the high-density PE and the aminoalkyl acrylate compound. The high-density PE used had a density of 0.950 g / cm ³ and a melt index of 0.04 g / 10 min, and aminoethyl acrylate was used as the aminoalkyl acrylate compound. The compounding ratio of high-density PE and aminoethyl acrylate was set to (95/5) in Example 1 and (90/10) in Example 2. Comparative Example 1 and Comparative Example 2
No aminoalkyl acrylate-based compound was used, and no organic peroxide was used in Comparative Example 1. The composition having the above blending ratio was formed into a film having a thickness of 30 μm by an air-cooled inflation molding machine. At that time, molding temperature 200
C., blow ratio was 3. The physical properties of the obtained film are shown in Table 1.

Each physical property was measured by the following methods. Haze value ・ ・ ・ Compliant with ASTM D1003 Yield strength ・ ・ ・ Compliant with JIS Z 1702 Young's modulus ・ ・ ・ Compliant with ASTM D882 Heat-sealing property ・ ・ ・ First, cut the film into a strip shape with a width of 15 mm and seal it. Pressure 2kg / cm
^2. Heat sealing is performed while changing the temperature under the condition that the sealing time is 1 second, and the test piece is peeled at a speed of 300 mm / min to examine the peel strength. As a result, the heat sealing property was represented by the sealing temperature of the test piece having a peel strength of 1 kg. Impact strength: Compliant with ASTM D781

From the results shown in Table 1, the film of the first invention has excellent impact strength, heat sealability, haze value,
It was confirmed that the material had well-balanced physical properties such as yield strength and Young's modulus.

[0025]

[Table 1]

[0026]

EFFECT OF THE INVENTION Since the polyethylene-aminoacrylate graft copolymer film described above has flexibility and an appropriate melting temperature, in addition to high strength, which is an excellent property of high-density polyethylene, It also has good impact strength, heat sealability and high transparency. Therefore, it can be easily heat-sealed at a low temperature, and is not easily broken even if it receives an impact. Further, according to the manufacturing method as described above, a film having high strength, easy heat sealability, high impact strength, and the like, and good transparency can be easily manufactured.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Onoda 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Akira Kawasaki Plastics Research Laboratory (72) Inventor Toshio Taka Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 3 No. 2 Showa Electric Co., Ltd. Kawasaki Resin Research Laboratory

Claims (2)

[Claims] 1. A high-density polyethylene having a density of 0.935 g / cm ³ or more in 80.0 to 99.9 parts by weight is represented by the general formula: (Wherein R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are hydrogen or an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 4). A polyethylene-aminoacrylate graft copolymer film comprising a polyethylene-aminoacrylate graft copolymer grafted with 1 to 20 parts by weight and having a haze value of less than 20%. 2. A high density polyethylene having a density of 0.935 g / cm ³ or more is represented by the general formula: (Wherein R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are hydrogen or an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 4). The method for producing a polyethylene-aminoacrylate graft copolymer film according to claim 1, wherein the graft copolymerization is carried out in a molding machine.