JPH08283352A - Modified linear low-density polyethylene - Google Patents

Abstract

PURPOSE: To obtain a modified linear low-density polyethylene excellent in melt moldability, especially laminate moldability, blow moldability, and extrusion moldability into films, sheets, etc. CONSTITUTION: A modified linear low-density polyethylene resin prepared by grafting 0.01-5wt.% unsaturated fatty acid ester having at least two unsaturations in only within the molecular chain onto a linear low-density polyethylene.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modified linear low-density polyethylene which is excellent in melt-molding, particularly in laminate, film, blow, sheet and the like and has excellent extrusion moldability.

[0002]

2. Description of the Related Art Linear low density polyethylene (hereinafter referred to as LL
DPE) is widely used because it has excellent properties such as rigidity, impact resistance, breaking strength, scratch resistance, heat sealability, moisture resistance, and water resistance, and is inexpensive. For example, it is widely used as a film for agriculture and general packaging. It is also used for release paper, printing paper, thermal transfer paper, process paper for manufacturing artificial leather, etc. by lamination with paper by extrusion lamination molding. Further, it is used as a packaging material for food packaging by laminating it with a biaxially oriented polypropylene film, a polyester film, a polyamide film, an aluminum foil and the like. Further, it is also used in blow-molded hollow containers such as bag-in-boxes. LLDPE having such characteristics
Is a film that generally has low viscosity or tension when melted,
There is a drawback that it does not have sufficient suitability for extrusion molding such as lamination and blow.

For example, in the case of laminate molding, it is generally 270 to 30 in order to have adhesiveness with paper or a film of polypropylene, polyester, polyamide or the like.
Molding needs to be performed at a high temperature of about 0 ° C. But,
Since the melt tension of LLDPE is small, the melt film becomes unstable at such a temperature, and fluctuations in width and thickness are likely to occur, and extrusion lamination molding was extremely difficult with LLDPE alone. Various methods have been proposed to solve this problem. For example, there is a method of blending a low density polyethylene produced by a high pressure method and having a wide molecular weight distribution. According to this method, the melt film is stable, and extrusion laminate molding can be stably performed in a wide range of molding conditions.
However, this method has a problem in that the high breaking strength and the decrease in rigidity, which are the characteristics of LLDPE, are caused. Moreover, the drawbacks that the high-speed moldability is not yet sufficient and the neck-in is significantly larger than that of low-density polyethylene cannot be solved.

On the other hand, even in blow molding, since the melt tension is small, the parison is unstable and it is difficult to obtain a large molded product. LLD with low fluidity to improve this
Although PE is used, the fact is that the moldability is not fundamentally improved due to the drawbacks such as increased uneven thickness of the molded product.

[0005]

As mentioned above, the LLD is used.
PE has excellent properties such as rigidity, impact resistance, rupture strength, scratch resistance, heat sealability, moisture resistance, and water resistance, while it has a low melt viscosity or melt tension, so it is used for film molding and laminate molding. However, there is a drawback that extrusion moldability such as blow molding is not sufficient. In view of such circumstances, it is an object of the present invention to provide a modified low density polyethylene excellent in extrusion moldability without impairing the excellent characteristics of LLDPE.

[0006]

As a result of intensive studies, the present inventors have found that the above object can be achieved by grafting a specific unsaturated compound on LLDPE, and based on this finding, The invention was completed.

That is, the present invention is characterized in that a linear low density polyethylene is grafted with 0.01 to 5% by weight of an unsaturated fatty acid ester having at least two unsaturated bonds only inside the molecular chain. A modified linear low density polyethylene is provided.

The LLDPE used in the present invention is a random copolymer of ethylene and another α-olefin. Specific examples of the other α-olefin here include propylene, 1-butene, 1-pentene, 1-hexene, 4-
Methyl-1-pentene, 1-octene, 1-decene, 1
-Tetradecene, 1-octadecene and the like. These α-olefins can be used alone or in combination of two or more.

The density of LLDPE is generally 0.90-0.
It is 94 g / cm ³ . If the density is less than 0.90 g / cm ³ , the rigidity is low, and if it exceeds 0.94 g / cm ³ , the heat seal strength is low, which is not preferable.

Melt flow rate of LLDPE (JIS
According to K6758, hereinafter referred to as MFR) is generally 0.
01 to 50 g / 10 minutes and 0.05 to 20 g / 10
Minutes are preferred. If the MFR is less than 0.01 g / 10 minutes,
Poor flowability and no improvement in extrusion moldability. Further, when the MFR exceeds 50 g / 10 minutes, the melt tension becomes small, the extrusion moldability is not improved, and the physical strength of the product is weak, which is not preferable.

These LLDPEs can be used alone or in combination of two or more.

The unsaturated fatty acid ester having at least two unsaturated bonds only in the molecular chain in the present invention (hereinafter, simply referred to as unsaturated fatty acid ester) is an ester of a higher fatty acid and a monohydric or polyhydric alcohol. Is.

The carbon number of the higher fatty acid is not particularly limited, but is preferably 6 to 200. When the carbon number exceeds 200, the graft reaction is unlikely to occur. Specific examples of higher fatty acids include linoleic acid, linolenic acid, eleostearic acid, parinaric acid, and arachidonic acid.

The carbon number of the monohydric or polyhydric alcohol is not particularly limited, but is preferably 6 to 200. 2 carbon atoms
If it exceeds 00, the graft reaction is unlikely to occur. Specific examples of monohydric or polyhydric alcohols include methanol,
Ethanol, propanol, butanol, ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, glycerin, 1,3-dihydroxypropane, 2,2-dimethyl-1,3 -Dihydroxypropane.

The unsaturated fatty acid ester in the present invention is
It is a fatty acid ester in which the carbon at the terminal of the molecular chain has a single bond and has at least two unsaturated bonds between the carbons inside the molecular chain. Such unsaturated fatty acid ester, linoleic acid ethyl ester, linoleic acid octyl ester, linolenic acid butyl ester, diester of linolenic acid and ethylene glycol, triester of linoleic acid and glycerin, triester of linolenic acid and glycerin Examples thereof include simple substances or mixtures thereof, vegetable oils and the like. Here, the vegetable oil is a drying oil and / or a semi-drying oil containing triglyceride of linoleic acid and linolenic acid as a main component, and specific examples thereof include flaxseed oil, tung oil,
Examples include soybean oil, sesame oil, rapeseed oil, cottonseed oil and the like.

During the production of the modified linear low-density polyethylene of the present invention, a small amount of unsaturated compound can be added within the range not impairing the object of the present invention. Examples of such compounds include diethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, 1,4-pentadiene, Compounds having two or more unsaturated groups only at the molecular chain terminals such as 1,5-hexadiene,
Examples thereof include, but are not limited to, a single substance and / or a mixture of compounds having an unsaturated bond inside and at the end of the molecular chain such as 1,3-hexadiene and crotonic acid allyl ester.

The modification of LLDPE by the method of the present invention comprises:
By causing LLDPE and unsaturated fatty acid ester to react with each other, long-chain branching is imparted to a polypropylene resin having almost no long-chain branching. Therefore, it is presumed that this reaction is mainly a radical reaction.
Therefore, in order to accelerate this reaction, a radical generator such as an organic peroxide can be added. There is no particular limitation on the organic peroxide. Specific examples thereof include dialkyl peroxides such as di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide, i-
Diacyl peroxides such as butyl peroxide, di i
-Peroxydicarbonates such as propylperoxydicarbonate, peroxyesters such as t-butylperoxypivalate, ketone peroxides such as methyl ethyl ketone peroxide, 1,1-bis-t-butylperoxycyclohexane Examples thereof include peroxyketals, etc., and hydroperoxides such as t-butyl hydroperoxide, etc., but are not limited thereto.

In order to obtain the modified linear low-density polyethylene of the present invention, LLDPE and the above unsaturated fatty acid ester may be added with an organic peroxide, if necessary, and dry-blended in advance, followed by melt-kneading, or LLDPE. Is dissolved in a solvent, and an unsaturated fatty acid ester and, if necessary, an organic peroxide are added and reacted. In the case of melt kneading, a method of kneading using an open roll, a Banbury mixer, a kneader, an extruder or the like may be appropriately used. The kneading temperature is usually 120 to 300.
C., preferably 140 to 260.degree.

The modified linear low-density polyethylene of the present invention may optionally contain conventional additives such as plasticizers, lubricants, various stabilizers, antiblocking agents, antistatic agents, dyes, pigments and various fillers. You may add.

The amount of the unsaturated fatty acid ester grafted to LLDPE is generally 0.01 to 5% by weight, and
1-2% by weight is preferred. When the graft amount of the unsaturated fatty acid ester is less than 0.01% by weight, the melt tension does not increase so much, and therefore the extrusion moldability is not improved, which is not preferable. Further, if it exceeds 5% by weight, odor or the like is generated, which is not preferable.

The grafting ratio of unsaturated fatty acid ester to LLDPE is measured by the absorbance of 1740 Kaiser (absorption of ester of unsaturated fatty acid ester) with reference to the absorbance of 4250 Kaiser (methylene group of LLDPE) in infrared absorption spectrum. You can As a specific method, a sample in which an unsaturated fatty acid ester is graft-reacted with LLDPE is stirred and dissolved in xylene at 150 ° C. for 1 hour, and then re-precipitated with methanol at room temperature, filtered, and unreacted without graft reaction The unsaturated fatty acid ester of is removed. After the methanol was dried and removed, the precipitate was hot-pressed at 180 ° C. to form a film, and the infrared absorption spectrum was measured.
The graft ratio can be determined from the ratio of the absorbance of 250 Kaiser (methylene group of LLDPE) and the absorbance of 1740 Kaiser (absorption of ester of unsaturated fatty acid ester).

[0022]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. The types of various LLDPE used in the examples and comparative examples used below are shown below.

Component (A): LLDPE A-1: MFR 10 g / 10 minutes, density 0.923 g
/ Cm ³ ethylene and 1-butene random copolymer A-2: MFR 40 g / 10 minutes, density 0.910 g
/ Cm ³ random copolymer of ethylene and 1-octene A-3: MFR 1 g / 10 min, density 0.930 g /
cm ³ random copolymer of ethylene and 1-hexene (B) component: unsaturated fatty acid ester (B-1, B-2)
Or an unsaturated compound (B-
3) B-1: linolenic acid glycerin triester B-2: flaxseed oil B-3: ethylene glycol dimethacrylate (C) component: low-density polyethylene C-1: MFR 7 g / 10 minutes, density 0.917 g / c
Dicumyl peroxide (DCP) was used as the low-density polyethylene organic peroxide having m ³ .

Example 1 10 kg of A-1 and 40 g of B-1 (charge of 0.4% by weight) were mixed in a Henschel mixer, and then the screw diameter was 3
220 using the same direction twin-screw extruder with 0 mmφ vent
Kneading and grafting reaction were carried out at ℃. Wash the pellet after reaction for measurement of infrared absorption spectrum with xylene,
Unreacted B-1 component was removed. Graft ratio is 0.33
% By weight. Using a pellet molding machine having a 40 mmφ extruder using the pellets, a biaxially stretched polyamide 6 film preliminarily laminated with a high-pressure polyethylene was used as a base material, and a high-pressure polyethylene layer of the film had a temperature of 280. Laminate molding was performed at a temperature of 110 ° C. and an air gap of 110 mm. Drawdown property is 30 rpm of extruder
The take-up speed was increased by rpm to evaluate the speed at which film breakage occurred, and the neck-in was measured using a sample molded at a film thickness of 20 μ and a take-up speed of 200 m / min. It was as good as 65 mm. Also, the laminated film is good in appearance without gel fish eyes, and has a heat seal strength at 150 ° C. (150 ° C., pressure 2 kg / cm ² , seal time 1 second, seal width 5 mm, sample width 15 mm). A good value of 4.8 kg / 15 mm was shown.

Examples 2 to 6 LL whose types and blending amounts (prepared amounts) are shown in Table 1
The DPE component, unsaturated fatty acid ester and organic peroxide were mixed for 5 minutes using a Henschel mixer, and then melt-kneaded at a temperature of 220 ° C. by an extruder with a vent to form pellets. The obtained pellets were washed with xylene in the same manner as in Example 1 and subjected to infrared absorption spectrum measurement and molding to obtain a sample. The drawdown property, neck-in and heat seal strength were measured in the same manner as in Example 1. The results are shown in Table 1.

Example 7 Pellets were obtained in the same manner as in Example 1 except that A-3 was used as the component (A). The graft ratio was 0.34% by weight. Blow molding was performed using this. In blow molding, the extrusion temperature is 230 ° C and the mold temperature is 4
A hollow molded article was obtained at 0 ° C. It was possible to perform stable molding, and the obtained hollow molded product had a good appearance.

Example 8 Film formation was carried out using the pellets obtained in Example 6. A film forming machine having a T-die having a width of 200 mm was used for forming, and a film having a thickness of 50 μm was prepared at a resin temperature of 255 ° C. and a take-up speed of 3 m / min. The molding could be carried out without any problems. The obtained film had no gel and had a good appearance.

Comparative Example 1 In Example 6, the same evaluation as in Example 1 was carried out for the sample which did not use B-2 and was not grafted.
Could not be molded.

Comparative Example 2 In order to improve moldability, A-1 was blended with 50% by weight of low density polyethylene and the same evaluation as in Example 1 was carried out, but the neck-in was large and the heat seal strength was small.

Comparative Example 3 An unsaturated compound having an unsaturated bond at the molecular chain end was used in place of the unsaturated fatty acid ester, and the same evaluation as in Example 5 was carried out. Many were observed and the appearance was poor.

Comparative Example 4 The same operation as in Example 1 was carried out except that 0.001% by weight of B-1 was used, but molding could not be performed.

Comparative Example 5 Blow molding was carried out using only A-2. However, the parison was poor in stability and only a hollow molded product having a nonuniform thickness was obtained.

[0033]

[Table 1]

[0034]

The modified linear low-density polyethylene of the present invention has excellent extrusion moldability such as laminate, blow, film and sheet without impairing the advantages of the linear low-density polyethylene. The productivity in extrusion molding can be improved.

Continued front page (72) Inventor Takaya Tahira, 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Akira Kawasaki Plastic Research Laboratory (72) Inventor Satoshi Maruyama 3-2, Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa No. Awakawa Electric Co., Ltd. Kawasaki Resin Research Laboratory

Claims (3)

[Claims] 1. A modified linear chain characterized by grafting 0.01 to 5% by weight of an unsaturated fatty acid ester having at least two unsaturated bonds only inside the molecular chain onto a linear low density polyethylene. Low density polyethylene. 2. The modified linear low-density polyethylene according to claim 1, wherein the unsaturated fatty acid ester having at least two unsaturated bonds only inside the molecular chain is a vegetable oil. 3. The linear low density polyethylene has a density of 0.
90 to 0.94 g / cm ³ , melt flow rate 0.0
The modified linear low-density polyethylene according to claim 1 or 2, which is a linear low-density polyethylene having an amount of 1 to 50 g / 10 minutes.