JP2006523784A - Polyethylene made using metallocene with fiber applications - Google Patents

Abstract

According to the present invention there is provided a raffia made using unwoven or woven monofilaments or stretched tapes with long carbon chain branches made with metallocene.

Description

  The present invention relates to the field of monofilaments and stretch tapes made using polyethylene made with metallocene.

  Monofilaments are wire-like polymer strands with a circular cross section oriented in one direction. Monofilaments are made by a melt spinning process and have a diameter in the range of 0.1 to 2.5 mm depending on the end use. Polyethylene, polypropylene, nylon and polyester are usually used as raw materials for producing monofilaments.

  Stretch tape is made from a primary film produced by either a blown process or a cast film process. The film can be cut and oriented as a tape, or conversely oriented and cut into a tape. Orientation is accomplished by stretching the film or tape while passing it in an air oven or over a hot plate at a temperature below its melting point. Stretching is done by passing the film or tape over two sets of rollers operated at different speeds, which are placed in front of and after the air furnace / hot plate, respectively. In this case, the speed of the second set of rollers is faster than the speed of the first set of rollers.

  A polymer that is suitably used in the market for this application is high density polyethylene (HDPE) made with Ziegler-Natta catalysts. This HDPE has a MI2 of less than 1 g / 10 min. For example, Solvay Eltex's A4009MFN1325 resin, or Basel Hostalen's GF7740 F1, GF7740 F2, GF7740 M3 resin, or a polyethylene resin described in Patent Document 1. is there. The molecular weight distribution MWD of these resins is very wide, which means that these resins may contain very long and very short polymer chains.

  As described in Patent Documents 2 to 4, semicrystalline polyethylene (PE) and polypropylene (PP) are also used as raw materials for monofilaments, stretched tapes and raffia. Throughout this specification raffia is defined as woven monofilament or woven stretched tape. Stretch tapes and monofilaments made using polyethylene exhibit greater elongation at break, greater flexibility, and lower fibrillation tendencies than those made using polypropylene. These properties are advantageous, for example, when making woven tape fabrics. However, products made from polyethylene have the disadvantage that they are much less strong than products made from polypropylene. Strength increases as a function of molecular weight, density, degree of polymer chain / microcrystal orientation, and increases with narrowing molecular weight distribution. Impact strength increases with decreasing density, increasing molecular weight, and decreasing molecular weight distribution.

Accordingly, there is a need for monofilaments or stretched tapes that are unwoven or woven into raffia with a better balance of properties.
GB-0023662. FR-A-2814761 specification. JP-20013422209 specification. JP-2001220405 specification.

  The object of the present invention is to produce monofilament or stretched tape products with high strength.

  Another object of the invention is to produce a monofilament or stretch tape product with high impact strength.

  Another object of the present invention is to produce monofilament or stretched tape products with high elongation at break.

  Yet another object of the present invention is to produce a monofilament or stretch tape product with a soft tactile feel.

  Yet another object of the invention is to produce a highly flexible monofilament or stretch tape product.

  Thus, according to the present invention there is provided a non-woven or woven raffia monofilament or stretch tape made from polyethylene (mPE) with long carbon chain branch made using metallocene. .

Suitable metallocene catalyst components are based on a tetrahydroindenyl component or a component with a constrained geometry, particularly preferably based on a tetrahydroindenyl component. Also according to the present invention, in a method for producing raffia or stretched tape using polyethylene made using metallocene,
(A) preparing a medium density polyethylene resin with long carbon chain branches made of metallocene;
(B) making a film from the polyethylene resin of step (a),
(C) orienting the film obtained from step (b) by stretching,
(D) A method is provided comprising the step of cutting the stretched film of step (c) into strips.

  Alternatively, the primary film can be first cut into strips and then oriented by stretching.

  This film can be either a blown film or a cast film. Films are made easier when processed materials with high melt strength, such as polyethylene with long carbon chain branches and / or linear polyethylene with very long chain lengths are used. Metallocene catalyst systems based on tetrahydroindenyl components or components with a constrained geometric structure are particularly useful for the production of polyethylene resins having long carbon chain branches.

  In the manufacture of blown films, resins made with tetrahydroindenyl catalyst components produce very stable film bubbles, thus obtaining films with uniform thickness and little or no defects. When the film is cut into tape and stretched, the uneven thickness and wrinkles become weak spots.

  In the production of cast films, the resin made with the tetrahydroindenyl catalyst component has a very stable elongational viscosity, and therefore a stable and regular thickness film is obtained.

In addition, resins with long branching can provide traction resistance and tenacity.
It has been observed that mechanical properties such as (strength) are better retained at lower densities than linear resins with comparable mechanical properties. The ability to work with low density has the advantage that a material with improved flexibility, low melting temperature and good processing stability can be obtained.

  Orientation of the primary film or cut tape is accomplished by stretching while maintaining the temperature below the melting point while passing through an air oven or over a hot plate. The elongation of the primary film or cut tape is the film or tape on two sets of rollers (godet roller) operated at different speeds placed before and after the air furnace / hot plate, respectively. It is done by passing through. The stretch ratio S2 / S1 is defined by the speed S2 of the roller 2 versus the speed S1 of the roller 1. In this case, S2 is larger than S1.

  When stretching is performed at such a high temperature, polymer chain / crystal orientation occurs, and at the same time, the crystallinity increases. These structural changes increase tensile strength and at the same time decrease elongation. Tensile strength increases with increasing elongation ratio and elongation temperature. The elongation temperature is as close to the melting point as possible, but is preferably lower than the melting point. For high density polyethylene, typical values for the stretch ratio are 5.0 to 7.0. The typical elongation temperature depends on the melting point of the polyethylene resin. The elongation temperature is below the melting point but should be as close to the melting point as possible. Typically, the elongation temperature is 5 to 70 ° C. below the melting point of the resin, preferably 10 to 50 ° C. below the melting point of the resin.

  Preferably, the stretched tape is annealed immediately after the stretching operation to minimize shrinkage that may result from residual stress in the oriented tape. Annealing is performed by heating the tape while carrying the stretched tape from the second godet roller to a third godet roller having a speed S3 that is slower than the speed S2 of roller 2. Preferably, speed S3 is about 95% of speed S2. The annealing ratio AR is defined by (S2-S3) / S2 at a temperature slightly below the elongation temperature. Typically, the annealing temperature is 5-10 ° C. below the elongation temperature.

  Polymers that do not contain either very long linear polymer chains or molecules with long carbon chain branches have good extensibility. For example, low density polyethylene (LDPE) with long carbon chain branching cannot extend beyond a certain extent. On the other hand, pure linear polyethylene usually obtained using a Ziegler-Natta catalyst has a high degree of extensibility.

Metallocenes used to produce high density polyethylene are of the general formula
R ″ (lnd) ₂ MQ ₂ (I)
The bisindenyl represented by or the formula
R ″ (Cp) ₂ MQ ₂ (II)
A bis-cyclopentadienyl represented by
R ″ (Cp) (NR ′) MQ ₂ (III)
Can be a component having a constrained geometric structure represented by where (Ind) is an indenyl or hydrogenated indenyl with or without substituents, and Cp has a substituent or A free cyclopentadienyl ring, R ′ is hydrogen or a hydrocarbyl having 1 to 20 carbon atoms, R ″ is a structural bridge between two indenyl groups to give steric rigidity and C _{1 to} C ₄ -alkylene group, dialkyl germanium or silicon or siloxane, or alkylphosphine or amine group, the bridge may or may not be substituted; Q is 1 to 20 carbon atoms A hydrocarbyl group or halogen, and M is a transition metal or vanadium of group IVb of the periodic table.

  Each indenyl or hydrogenated indenyl compound in formula (I) is substituted in one or more positions in the cyclopentadienyl ring, cyclohexenyl ring and bridge in the same or different manner from one another. Can be.

In formula (I), the substituents on indenyl can be independently selected from the substituents of formula XR _V , where X is selected from Group IVA of the periodic table, oxygen and nitrogen, and each R is the same or phase Differently selected from hydrogen and C 1-20 hydrocarbyl, v + 1 is the valence of X. X is preferably C. If the cyclopentadienyl ring has a substituent, the substituent must be so bulky as to affect the coordination of the olefin monomer to the metal M. The substituent R on the cyclopentadienyl ring is preferably hydrogen or CH ₃ . More preferably, at least one and most preferably both cyclopentadienyl rings are unsubstituted.

  In one preferred embodiment, both indenyl groups are unsubstituted and the most preferred catalyst component is tetrahydroindenyl.

  In formula (II), each cyclopentadienyl ring can have a substituent in one or more positions in the cyclopentadienyl ring in the same or different manner.

In formula (II), the substituents on cyclopentadienyl can be independently selected from the substituents of formula XR ^* _V , where X is selected from group IVA of the periodic table, oxygen and nitrogen, and each R ^* Is the same or different and is selected from hydrogen and hydrocarbyl having 1 to 20 carbon atoms, and v + 1 is the valence of X. X is preferably C and the most preferred substituent is n-butyl.
R ″ is preferably a C ₁ -C ₄ -alkylene group (used herein to describe a bifunctional group, also referred to as an alkylidene group), most preferably an ethylene bridge (bifunctional in this specification). Used to describe a functional group, also referred to as an ethylidene group), which may or may not have a substituent.

  The metal M is preferably zirconium, hafnium or titanium, most preferably zirconium.

  Each Q is the same or different and can be a hydrocarbyl or hydrocarboxy having 1 to 20 carbon atoms, or a halogen. Suitable hydrocarbyls include aryl, alkyl, alkenyl, alkylaryl, or arylalkyl. Each Q is preferably a halogen.

  Among suitable metallocenes used in the present invention, there can be mentioned bis-tetrahydroindenyl compounds and bis-indenyl compounds, or bis (cyclopentadienyl) compounds as described in WO 96/35729. The most preferred metallocene catalyst is isopropylidene-bis (4,5,6,7-tetrahydro-1-indenyl) zirconium dichloride.

  The metallocene can be supported using any method known in the art. When supported, the support used in the present invention can be any organic or inorganic solid, in particular a porous support such as talc, an inorganic oxide, and a resinous support material such as a polyolefin. Preferably the support material is an inorganic oxide in the form of a fine powder. When a reagent that reacts with the carrier and has an ionization action is added to the carrier, an active site can be created.

  It is preferred to use alumoxane to ionize the catalyst during the polymerization process, and any alumoxane known in the art is suitable.

Preferred alumoxanes are those for linear oligomeric alumoxanes.
(IV) R- (Al (R) -O) _n -AIR ₂ ,
And for cyclic alumoxanes
(V) (-Al (R) -O-) _m
And an oligomeric linear and / or cyclic alkylalumoxane. Where n is 1-40, preferably 10 to 20, m is 3 to 40, preferably is R a 3~20 _C 1 ~C ₈ - alkyl group, preferably methyl. Preference is given to using methylalumoxane.

One or more aluminum alkyls can be used as a catalyst in the reactor. Aluminum alkyls represented by the formula AlR _X can be used, wherein each R is the same or different and is selected from a halide or an alkoxy or alkyl group having 1 to 12 carbon atoms, and x is 1 to 3. . A particularly suitable aluminum alkyl is trialkylaluminum, with triisobutylaluminum (TIBAL) being most preferred.

  Further, the catalyst can be prepolymerized before introducing the catalyst into the reaction zone and / or before the reaction conditions stabilize in the reactor.

The polyethylene resin of the present invention has a density of 0.925 to 0.950 g / cm ³ , preferably 0.930 to 0.940 g / cm ³ , most preferably about 0.935 g / cm ³ . The melt index MI2 is in the range of 0.1 to 5 g / 10 minutes, preferably 0.2 to 1.5 g / 10 minutes.

  Density was measured at 23 ° C. by standard test method ASTM D 1505, and melt index MI2 was measured at 190 ° C. under a load of 2.16 kg according to standard test method ASTM D 1238.

  Polyethylenes made with metallocenes give very strong stretched tapes and raffia products due primarily to the narrow molecular weight distribution and long carbon chain branching. The final product has improved tensile and elongation properties while having improved flexibility and processing properties.

  Several resins were tested to make raffia products.

Resin R1 is a medium density polyethylene resin made with isopropylidene (tetrahydroindenyl) zirconium dichloride. This had a density of 0.934 g / cm ³ and a melt index MI2 of 0.9 g / min. Additives were added to this as follows.

94.5% by weight of resin R1;
-4% red masterbatch, Clariant PE 44930;
1% polymer processing aid, Schuman polymer processing aid, AMF 702;
-0.5% antiblocking masterbatch, Clariant B1981.

Resin R2 was a commercially available resin (GF7740 F1 from Hostalen) made with Ziegler-Natta catalyst system. This had a density of 0.946 g / cm ³ and a melt index MI2 of 0.5 g / 10 min.

These two resins were processed under the same conditions under the following blown film production conditions and stretching conditions.
-Melting die mold temperature: 220 ° C.
-Primary film thickness: 60 microns.
-Orientation temperature: It changes sequentially between 80-120 degreeC.
-Elongation ratio: 7: 1.

  The final product obtained from the resin R1 made with metallocene, whether unwoven or woven (net), has high strength, excellent elongation at break, and very high break strength I had. It had a soft feel and high flexibility.

  Resins R1 and R2 summarize the properties of the stretch tapes obtained from Table I.

伸長テープの破断時における伸び、強度およびテナシティーは標準試験法ＩＳＯ−２０６２（１９９３）に従って測定した。タイター（ｔｉｔｒｅ）はｔｅｘまたはｇ／ｋｍ単位で測定した。この値はフィラメントまたは繊維の直線的な重さの目安である。

The elongation, strength and tenacity at break of the stretched tape were measured according to standard test method ISO-2062 (1993). The titer was measured in tex or g / km. This value is a measure of the linear weight of the filament or fiber.

  The properties of the woven stretched tape, or raffia, are listed in Table II.

このように本発明に従ってつくられたラフィア製品は従来法の製品に比べ改善された性質をもっている。

Thus, raffia products made in accordance with the present invention have improved properties compared to products of the prior art.

  The elongation and strength at break of the raffia were measured according to standard test method ISO-5081 (1977).

Claims (8)

  A non-woven or woven raffia monofilament or stretch tape characterized in that it is made from polyethylene with long carbon chain branches made using metallocene.   2. The monofilament or stretched tape according to claim 1, wherein the metallocene component is tetrahydroindenyl. (A) preparing a medium density polyethylene resin with long carbon chain branches made of metallocene;
(B) making a film from the polyethylene resin of step (a),
(C) orienting the film obtained from step (b) by stretching,
(D) cutting the stretched film of step (c) into strips,
(E) A method for producing an elongated tape, comprising the step of annealing the elongated tape as needed.   4. The method of claim 3, wherein step (d) is performed before step (c).   The method according to claim 3 or 4, wherein the elongation temperature is 10 to 70 ° C lower than the melting temperature of the resin.   6. The method according to claim 5, wherein the elongation temperature is 15 to 50 [deg.] C. lower than the melting temperature of the resin.   The method according to any one of claims 3 to 6, wherein a speed ratio of the plurality of rollers is in a range of 5 to 7.   The method according to claim 3, wherein when annealing is performed, the annealing temperature is 5 to 10 ° C. lower than the elongation temperature.