JPH0455447A - Polyethylene resin composition and laminate utilizing the same - Google Patents

Abstract

PURPOSE:To prove the subject composition having excellent adhesivity, providing laminates by the co-extrusion of the composition and any other thermoplastic resin and suitable for preparing materials for wrapping foods, etc., by compounding a specific amount of an ethylenic copolymer containing units originated from a radical polymerizable acid anhydride. CONSTITUTION:The subject composition comprises (A) 3-80 wt.% of an ethylenic copolymer containing 0.1-20 wt.% of a radically polymerizable acid anhydride (e.g. maleic anhydride) and (B) 90-20 wt.% of a polyethylene resin having a MFR of 0.01-1000 g/10 min and comprising a high pressure ethylenic (co)polymer having a density of >=0.9 g/cc and prepared by (co)polymerizing ethylene alone, a mixture of the ethylene with a alpha-olefin or a mixture of the ethylene with <=10% of a radically polymerizing monomer. The composition is laminated to a thermoplastic resin by a co-extrusion method.

Description

Detailed Description of the Invention [Industrial Field of Application J The present invention is directed to a polyethylene resin containing an ethylene copolymer containing units derived from a radically polymerizable acid anhydride and having no odor and excellent adhesive properties. The present invention relates to a composition and a multilayer laminate using the composition.

[Prior Art] Polyolefin resins are used in various packaging materials and structural materials from the viewpoints of mechanical strength, hygiene, cost, moldability, etc. However, as is known from the past, polyolefin resins have oil resistance, gas barrier properties, adhesive properties,
It has poor printability and is unsuitable for use alone in materials required in the fields of highly functional packaging materials and structural materials.

In order to improve these drawbacks of polyolefin resin,
Although various proposals have been made in the past, satisfactory results have not been obtained due to constraints such as complicated manufacturing processes, increased costs, and limited application designs.

One solution to this problem is to use polyester, polyamide,
Saponified products of ethylene-vinyl acetate copolymer, metals such as aluminum, glass or metals, vapor deposition of inorganic materials, lamination with cloth, non-woven fabric, paper, etc., and composites are carried out, but polyolefins are originally made of polyolefins based on their chemical structure. Therefore, it has poor affinity with the above-mentioned resins, etc., and is difficult to stack.

As a solution to this problem, there has been a proposal to provide a separate layer for adhesion between these layers, but this requires a new process of applying an adhesive, which has the disadvantage of complicating the manufacturing process.

In addition, it is well known that polyolefin resins graft-modified with unsaturated carboxylic acids or acid anhydrides are used as adhesive resins for lamination, but their performance is limited by the crosslinking and decomposition reactions that occur during graft modification. The appearance is often unfavorable due to coloration due to side reactions.

In order to suppress this side reaction, it may be considered to reduce the amount of grafting for modification, but as a result, sufficient adhesion cannot be obtained and delamination between the layers of the laminate is often observed.

Furthermore, since a modification step is required in addition to the polymerization step, there is a problem in that the manufacturing cost increases.

[Problems to be Solved by the Invention] An object of the present invention is to provide a resin composition having the advantage of low cost in the fields of packaging materials for food and industrial materials, automobile parts materials, etc. It provides a laminate that is firmly bonded without adhesive by coextrusion method.

[Means for Solving the Problems] In order to solve the above problems, the inventors conducted extensive research and found that at least (1) the copolymerization ratio of the radically polymerizable acid anhydride is 0.1 to 20% by weight. Ethylene copolymer 3
to 80% by weight and MFR (190°C) of 0.1 to 10
The present invention provides a polyethylene resin composition containing 97 to 20% by weight of a polyethylene resin of 0.00, and (
2) Copolymerization ratio of radically polymerizable acid anhydride is 0.1 to 2
3 to 80% by weight of ethylene-based copolymer which is 0% by weight
The object of the present invention is to provide a laminate in which a polyethylene resin composition containing 97 to 20% by weight of a polyethylene resin having an MFR (190° C.) of 0.1 to 1000 is laminated with a thermoplastic resin by a coextrusion method.

Examples of the radically polymerizable acid anhydride used in the present invention include maleic anhydride, itaconic anhydride, endic anhydride, citraconic anhydride, and alkenyl succinic anhydride with a terminal double bond having at most I8 carbon atoms. Acids, alkagenyl succinic anhydride having a double bond at the end and having at most 18 carbon atoms can be mentioned.

The ethylene copolymer of the present invention needs to contain a radically polymerizable acid anhydride in a copolymerization ratio of 0.1 to 20% by weight.

If the copolymerization ratio of the acid anhydride is less than 0.1, the laminate, which is the object of the present invention, cannot be effectively produced, and Φ peeling between the laminates occurs. Moreover, if it exceeds 20% by weight, properties such as flexibility and moisture stability that polyethylene resin originally possesses, which are expected from ethylene copolymers, will be impaired.

The copolymer of ethylene and radically polymerizable acid anhydride is bulky,
It is produced by processes such as solution, suspension, or emulsion, but the most common method is bulk copolymerization.
It is produced by radical polymerization at a temperature range of 100 to 300°C under a pressure of 00 to 3000 atm. Among them, the preferable pressure and temperature range is 1000 to 2500.
Atmospheric pressure, average temperature in the reactor is 150-270℃6
If the pressure is below 700 atm, the molecular weight of the polymer cannot be sufficiently increased, resulting in poor moldability and resin properties of the composition. Pressures exceeding 3,000 atmospheres hardly improve the physical properties or productivity of the product, are essentially meaningless, and only increase production costs.

If the average polymerization temperature is below 100°C, the polymerization reaction will not be stable,
The conversion rate to the copolymer decreases, causing economic problems.

Furthermore, if the temperature exceeds 300°C, the molecular weight of the copolymer cannot be increased and there is a risk that the reaction will run out of control.

As can be seen from the above, when producing an ethylene copolymer, it is basically possible to use ordinary high-pressure process low-density polyethylene production equipment and technology. As the type of reactor, an autoclave type or tubular type with a stirrer can be used.

Furthermore, if necessary, multiple reactors can be connected in series or in parallel to perform multistage polymerization. Furthermore, in the case of an autoclave type reactor, by partitioning the inside of the reactor into multiple zones, it is possible to create a temperature distribution and to perform more precise temperature control.

When using an autoclave type reactor, L/D is 1
It is preferable to use an autoclave type reactor with a temperature of ~30. In particular, since radically polymerizable acid anhydrides have poor polymerization stability, a high degree of uniformity within the reactor is required. When the L/D of the reactor is larger than 30, the circulation flow within the reactor becomes weak, making it difficult to achieve uniform dispersion within the reactor, and making runaway reactions more likely to occur.

Under the above conditions, the copolymer used in the present invention is
It is carried out in the presence of a free radical initiator of some kind. Examples of the free radical initiator include oxygen, dialkyl peroxide, dialkyl peroxide such as t-butylcumyl peroxide, dicumyl peroxide, acetyl peroxide, i-butyl peroxide, octanoyl peroxide, etc. Peroxydicarbonates such as diacyl peroxide, di-i-propyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, peroxy esters such as t-butyl peroxyvivalate, t-butyl peroxylaurate, Ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide, peroxyketals such as 1.1-bis t-butyl peroxycyclohexane and 2.2-bis t-butyl peroxyoctane, t-butyl hydroperoxide, and cumene. Examples include hydroperoxides such as hydroperoxide, and azo compounds such as 2,2-azo-1-butyronitrile.

Furthermore, various chain transfer agents can be used as molecular weight regulators during polymerization.

Examples of chain transfer agents include olefins such as propylene, butene, and hexene, paraffins such as ethane, propane, and butane, carbonyl compounds such as acetone, methyl ethyl ketone, and methyl acetate, and aromatic hydrocarbons such as toluene, xylene, and ethylbenzene. There are many examples of this.

The copolymer obtained by polymerization by the method described above is discharged from the reactor together with unreacted monomers, and passes through a high-pressure separator, optionally a medium-pressure separator, and a low-pressure separator to separate the polymer and monomer or low-pressure separator. After separating the monomer from the molecular weight polymer, it is pelletized through an extruder, and the unreacted monomer is recycled and reused after removing the low molecular weight polymer with a filter. When pelletizing, various additives as described later can be added.

The polyethylene resin used in the present invention refers to a wide range of polyethylene resins, including high-pressure low-density polyethylene that is an ethylene homopolymer, high-density and medium-density polyethylene, and ethylene-based resins with a density exceeding 0.90 g/cc. -Olefin copolymers (including linear low density polyethylene) [e.g. ethylene and propylene, 1-butene, l-hexene, 4-methylpentene-1 or l
- refers to a copolymer with octene, etc.] or with ethylene and 1
High-pressure ethylene copolymers copolymerized with various radically polymerizable monomers in an amount not exceeding 0% by weight, such as ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer Includes polymers, etc.

MFR of the polyethylene resin [JIS K7210
(Thermoplastic plastic flow test) Condition 4 in Table 1 (
The test was conducted at a temperature of 190°C and a test load of 2° (16 kgf). ] is preferably 0.01-1000. If the MFR value is less than 0.01, it will not only be difficult to form a composition with the ethylene copolymer of the present invention for boat fishing, but also difficult to mold the laminate of the present invention. Also, M
When the FR value exceeds 1000, it becomes difficult to mix the resins, and when the amount of the polyethylene resin increases, the strength of the resulting composition becomes extremely low.

In addition, in order for the unit derived from the radically polymerizable acid anhydride in the ethylene copolymer to function in accordance with the purpose of the present invention, magnesium and aluminum remaining in the polyethylene resin used in the present invention are required. , the amount of transition metal is at most 11000PP, preferably at most 300PPM
It is necessary that In particular, it is preferable that the amount of transition metals is large (both 1100PP and the total of magnesium and aluminum is at most 200PPM).

This is because units derived from the acid anhydride in the ethylene copolymer react with the metal compound and form a pseudo-crosslinked state, causing problems in moldability and deterioration in adhesion. That will happen.

Therefore, it is preferable that the polyethylene resin used in the present invention does not contain a large amount of the metal compound.

The polyethylene resin composition of the present invention is obtained from 3% to 80% by weight of the above-mentioned ethylene copolymer and 97% to 20% by weight of the above polyethylene resin.

In order to effectively produce a laminate, which is the object of the present invention, the polyethylene resin composition must contain 0.05% to 10% by weight of units derived from radically polymerizable acid anhydrides.
It is preferable to take into consideration the amount of the ethylene copolymer in the composition and the amount of units derived from the radically polymerizable acid anhydride in the copolymer so that the following results are obtained.

In particular, when the amount of units derived from radically polymerizable acid anhydride in the polyethylene resin composition is less than 0.05% by weight, the glabella adhesiveness of the laminate of the present invention will be insufficient. In addition, it is not necessary that the unit derived from the radically polymerizable acid anhydride is substantially 10% by weight or more, and furthermore, the above-mentioned amount is sufficient to achieve the practical performance of the laminate of the present invention, taking economic efficiency into consideration. is lower than expected, ranging from 0.05 to 3% by weight. Furthermore, if limited, 0.1 to 0.
It exhibits performance at 5% by weight.

In particular, by forming a composition with a polyethylene resin using an ethylene copolymer containing at least 1% by weight of units derived from a radically polymerizable acid anhydride, it is possible to solve this problem by forming a composition with a polyethylene resin. It has been found that even if the amount of units derived from a substance is smaller than expected, or in other words, even if a large amount of dilution is performed, sufficient adhesive performance is exhibited.

This is because the polyethylene resin that is not copolymerized with a radically polymerizable acid anhydride has the main effect on the mechanical properties and moldability of the polyethylene composition of the present invention, and the adhesiveness required for the laminate is the same as the ethylene resin. This is thought to be because it depends on the polymer.

Through this study, we found that when trying to create a self-composition, if the amount of radically polymerizable acid anhydride is the same, it is not necessary to create a composition; It has been found that the adhesion is higher when the laminate is simply combined than when the laminate is obtained by coextrusion molding. This suggests that the concentration of the ethylene copolymer is effectively increased at the glabellar adhesive interface of the laminate through the molding process.

Various commonly known resin mixing methods can be used to produce the polyethylene resin composition. Examples of specific methods include a method in which the ethylene copolymer and polyethylene resin are dissolved in a good solvent for each component such as high-temperature toluene and reprecipitated, a method in which both components are mixed in a molten state; This can be carried out using a pressurized Nigu, a Banbury mixer, a static mixer, a screw extruder, etc., which are commonly used. It is also possible to mix the resins of each component in the form of powder or pellets when manufacturing the laminate, and to melt and mix them using the manufacturing stage of the laminate.

The resin composition obtained by the above method can be laminated on metal, glass, cloth, paper, plastic, etc. by conventionally known methods. That is, extrusion lamination method (including single method, tandem method, coextrusion method, and sandwich lamination method), adhesive lamination method (including dry lamination method, wet lamination method, solution coating method, hot melt method), coextrusion method, thermal bonding method, etc.

As a base material for imparting oil resistance and gas barrier properties to the laminate, it is necessary to select a thermoplastic resin suitable for the purpose. Specifically, the adjacent layer, that is, the base material laminated with the polyethylene resin composition of the present invention, includes polyethylene, polypropylene, polystyrene, nylon, polyester, ethylene-vinyl alcohol copolymer, polyvinyl Alcohol, polyvinylidene chloride, etc., and preferably thermoplastic resins such as polyethylene, nylon, ethylene-vinyl alcohol, polyvinyl alcohol, etc. can be mentioned.

The ethylene copolymer, the composition of the copolymer and a polyethylene resin, or the thermoplastic resin according to the present invention include:
Various additives and compounding agents can be used within the range that does not impair the characteristics of the polymer. Examples of additives and compounding agents include antioxidants (heat stabilizers), ultraviolet absorbers (
light stabilizers), antistatic agents, antifogging agents, flame retardants, lubricants (slip agents, antiblocking agents), inorganic and organic fillers, reinforcing materials, colorants (dyes, pigments), blowing agents, crosslinking agents, fragrances. etc.

The laminate obtained by the above method has strong interlayer adhesion (and has excellent appearance, odor, etc.), so it can be used for various purposes as various packaging materials and containers.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples and can take various forms.

[Example] (Example 1) A copolymer of ethylene and maleic anhydride was produced using high-pressure polyethylene production equipment having an autoclave type reactor. The obtained ethylene copolymer (A) is M
The FR (190° C.) was 8.6 g/10 min, and the unit derived from maleic anhydride was 2.2% by weight.

MFR [JIS
Condition 4 in Table 1 of K 7210 (Thermoplastic Flow Test) (Test temperature 190°C, Test load 2.1
6Kgf), ]7. Og/10 min, density 0.9
High pressure low density polyethylene (a) of 17 g/cc was mixed in a weight ratio of 20/80. For mixing, after tri-blending the two in a tumbler,
Using a 50 mmφ single-screw extruder, the mixture was melted and mixed at 170° C. and made into pellets.

VFR of the obtained polyethylene resin composition (190°C
) was 7.3 g/lo min, and the unit derived from maleic anhydride was 0.44% by weight. Note that the polymer composition was determined by infrared absorption spectrum.

The obtained resin composition had almost the same odor as ordinary high-density polyethylene.

A laminate of 3 types and 5 layers consisting of polyethylene layers as both outer layers, a 6-nylon layer in the middle, and the above-mentioned polyethylene resin composition between both layers was produced by coextrusion molding under the following conditions. For molding, a coextrusion multilayer film molding machine with three extruders with a die diameter of 65 mm and a T die with a width of 1300 mm was used.
Resin temperature in die 250℃, take-up speed 30m
/min to produce a laminate with a total thickness of 50 μm.

Molding was particularly problematic (it was carried out. The obtained laminate had good appearance and transparency, and a molded product with no pinholes was obtained.The obtained laminate was heated at 23°C and 50% relative humidity. After adjusting the condition for 24 hours, we cut it into strips of 15 mm width and measured the 180 degree peel strength between the layers at a speed of 300 mm/min. It was not possible to create a peeling edge for this purpose.Also, an attempt was made to remove the outermost layer by heat-sealing it, but the outermost layer of polyethylene only broke and the glabella could not be removed.As a result It was recognized that the laminate had sufficient lamination strength.

From the above results, the laminate obtained by the manufacturing method according to the present invention is
It can be seen that this is a good laminate that can be used for various purposes.

(Examples 2 to 10, Comparative Examples 1 to 3) A polyethylene resin composition was produced using the following ethylene copolymer and polyethylene resin in the same manner as in Example 1, and further laminated with a thermoplastic resin. manufactured something. The layer structure, molding temperature, and performance are shown in Table 1.

<Note> LDPE: High-pressure low-density polyethylene LLD: Linear low-density polyethylene resin E: High-density polyethylene d, density (g/Cm') EVO)l: Ethylene-vinyl alcohol copolymer (
Ethylene content 32mo42%) Non-peelable near 00g/15mm or more (Example 11
) The peel strength of the polyethylene resin composition of the ethylene copolymer (A) obtained in Example 1 and the high-pressure low density polyethylene (a) was tested by changing the blending ratio.

High-pressure low density polyethylene was used for both outer layers, ethylene-vinyl alcohol copolymer was used for the middle layer, and the molding temperature was 220°C.

The results are shown in Table 2.

(The following is a blank space) Table 2 From the above examples, it is recognized that the multilayer laminate of the present invention using the resin composition of the present invention is excellent.

[Effects of the invention] Lamination of polyolefin resins with poor adhesiveness, gas barrier properties, printability, etc. and barrier resins such as ethylene-vinyl alcohol copolymers, nylon, polyester, vinylidene chloride, etc., or thermal adhesiveness and rigidity. Laminates between various synthetic resins have been developed to improve functionality, such as laminates of polyethylene, polypropylene, etc. and other thermoplastic resins for the purpose of imparting a There was no adhesive resin available. For this reason, dry lamination methods have been used, expensive adhesive resins such as modified polyolefins produced by craft polymerization of maleic anhydride have been used, or adhesives having insufficient peel strength have been produced.

The polyethylene resin composition of the present invention is made by blending an ethylene copolymer, which is a copolymer of a radically polymerizable acid anhydride and ethylene, with a polyethylene resin, so it is less expensive and gels better than a graft modified product. It has a low content, has an excellent appearance when commercialized, and has excellent moldability equivalent to ordinary low-density polyethylene, and can be used to obtain laminates with sufficiently high adhesive strength even by coextrusion, which is highly productive. We have developed a suitable polyethylene resin composition and a laminate using it.

The resin composition of the present invention has an odor comparable to that of ordinary high-density polyethylene (and its adhesive strength does not decrease even when diluted), and it is particularly effective in coextrusion molding with ethylene-vinyl alcohol copolymers, nylon, etc. It shows the performance that
The present invention provides a laminate that is cheaper and has superior peel strength than graft copolymers of polymerizable acid anhydrides currently on the market as adhesive resins.

The polyethylene resin composition and laminate obtained by the present invention exhibit the above-mentioned effects and can be used in a wide variety of fields.

Typical applications include materials for packaging containers such as blow tubes, films, and sheets that require oxygen barrier properties; containers that require oil permeation resistance such as gasoline tanks; paper packs that require water resistance; It can be used in a wide variety of applications, such as release paper for cross-linking and laminating silicone resin, and vapor-deposited paper.

Claims (4)

[Claims] (1) Copolymerization ratio of radically polymerizable acid anhydride is from 0.1 to
A polyethylene resin composition comprising 3 to 80% by weight of an ethylene copolymer (20% by weight) and 97 to 20% by weight of a polyethylene resin. (2) Polyethylene resin has a density of 0.90 g/cc
Ethylene alone or a copolymer of ethylene and α-olefin exceeding .01~1
The resin composition according to claim 1, which is a polyethylene resin having a weight of 000 g/10 min. (3) The resin composition according to claim 1, wherein the polyethylene resin composition contains 0.05 to 10% by weight of units derived from a radically polymerizable acid anhydride. (4) Copolymerization ratio of radically polymerizable acid anhydride is from 0.1 to
3 to 80% by weight of an ethylene copolymer with a density of 20% by weight and ethylene alone or a copolymer of ethylene with an α-olefin mainly composed of ethylene with a density exceeding 0.90g/cc, or a copolymer of ethylene with a density of less than 10% by weight. A laminate obtained by laminating a resin composition consisting of 97 to 20% by weight of a polyethylene resin made of a high-pressure ethylene copolymer copolymerized with a radically polymerizable monomer within a range of 20 to 20% by weight with a thermoplastic resin by coextrusion.