DE19639638C2 - Synthetic polyolefin pulp - Google Patents

Description

The present invention relates to a synthetic Polyolefin pulp. In particular, the invention relates to a synthetic polyolefin pulp used in the manufacture of heat-sealable papers and paper webs (sheets) e.g. B. is usable for tea bags.

Because of their good heat sealability and their excellent gas and water permeability heat sealable papers made of synthetic pulps in applied in many areas, e.g. B. as papers for Tea bags and desiccant bags.

There has been strong demand in recent years for heat-sealable papers that can be found at lower Heat seal temperatures to save energy and productivity in terms of Increase production speed. Synthetic pulps with a low density polyethylene resin (LLDPE) as Base material was used for heat-sealable papers  Heat sealability developed at low temperatures and came onto the market. Such synthetic Pulps are detailed in Kasenshi Kenkyukai, No. 20, Pages 17 to 20 (1981).

To further enlarge the scope of application, that would be Development of synthetic polyolefin pulps desirable which is an even more improved Heat sealability at low temperatures than have conventional synthetic LLDPE pulps. In particular there is a need for synthetic polyolefin pulps with which can be used to produce heat-sealable papers that at temperatures around the melting point of the polyolefin resins can be heat sealed and excellent Have strength properties of the heat seal.

The present invention aims at the above solve the problems of the prior art described, and an object of the present invention is Providing a synthetic polyolefin pulp which especially for the production of heat sealable Papers and films that can be used not only with a temperature in the range of the melting point of the as Starting material used polyethylene resin can be heat sealed, but also one have excellent heat seal strength.

The synthetic polyolefin pulp according to the invention comprises as raw material:

• A) a linear ethylene-α-olefin copolymer resin comprising ethylene and 50 mol% or less of an α-olefin having 3 or more carbon atoms and a melt flow index (ASTM D 1238, 190 ° C) of 0.1 to 1000 g / 10 min., A density of 0.900 to 0.980 g / cm ³ and an average molecular weight distribution (Mw / Mn) according to GPC of 1.5 to 3.5; and or
• B) a homopolymer or copolymer resin which at least one α-olefin having 3 or more carbon atoms and a melt flow index (ASTM D 1238, 230 ° C) from 0.1 to 1000 g / 10 min., a melting point of 120 to 175 ° C and an average molecular weight distribution (Mw / Mn) from 1.5 to 3.5 by GPC; and or
• C) an α-olefin-ethylene copolymer resin, the one α-olefin with 3 or more carbon atoms and 14 mol% or less comprises ethylene and a melt flow index (ASTM D 1238, 230 ° C) from 0.1 to 1000 g / 10 min., A Melting point from 120 to 175 ° C and an average Molecular weight distribution (Mw / Mn) according to GPC from 1.5 to 3.5 has.

The synthetic polyolefin pulp according to the invention is described in detail below.

For the synthetic polyolefin pulp according to the invention polyolefin resins are used as the starting material.

Polyolefin resin

The linear α-olefin-ethylene copolymer resin (A) comprises Ethylene and 50 mol% or less of an α-olefin having 3 or more carbon atoms, preferably 3 to 20 Carbon atoms. The α-olefin (co) polymer resin (B)  comprises at least one α-olefin having 3 or more Carbon atoms, preferably 3 to 10 Carbon atoms. The α-olefin-ethylene copolymer resin (C) comprises an α-olefin having 3 or more carbon atoms, preferably 3 to 20 carbon atoms, and 14 mol% or less ethylene.

The α-olefins with 3 or more carbon atoms in the Resins (A), (B) and (C) close, for example Propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosen.

The linear α-olefin-ethylene copolymer resin (A) (hereinafter also referred to as linear polyethylene resin) contains the α-olefin with 3 or more Carbon atoms in an amount of 50 mol% or less, preferably 0.1 to 10 mol%, and more preferably 1 to 7 mol%. The linear polyethylene resin (A) has a melt flow index (MFI: ASTM D 1238, 190 ° C, load of 2.16 kg) from 0.1 to 1000 g / 10 min., Preferably 1 to 100 g / 10 min. If one linear polyethylene resin (A) with one Melt flow index used can be a synthetic one Pulp are obtained in which the fibers are highly branched are and thus get caught well together.

The linear polyethylene resin (A) has a density (ASTM D 1505) of 0.900 to 0.980, preferably 0.900 to 0.950 g / cm ³ , and includes a so-called linear low-density polyethylene (LLDPE). When a linear polyethylene resin (A) having such a density range is used, a synthetic pulp excellent in heat sealability at low temperatures can be obtained.

The linear polyethylene resin used in the present invention (A) has a molecular weight distribution (Mw / Mn, where Mw is the weight average molecular weight and Mn is the number average molecular weight) from 1.5 to 3.5, preferably 2.0 to 3.0, measured with a GPC Method. If a linear polyethylene resin (A) with a such a narrow range of a medium Molecular weight distribution can be used synthetic pulp whose heat sealing improved Has strength properties can be obtained.

As the α-olefin (co) polymer resin (B) and the α-olefin Ethylene copolymer resin (C) are preferred Propylene homopolymers or propylene-ethylene copolymers used.

The α-olefin copolymer resin (B) and the α-olefin-ethylene Copolymer resin (C) each has a melt flow index (MFR, ASTM D 1238, 230 ° C, load of 2.16 kg) of 0.1 up to 1000 g / 10 min., preferably 1 to 100 g / 10 min. If a resin (B) or a resin (C) with such Melt flow index range can be used synthetic pulp can be obtained in the fibers are heavily branched and therefore work well together get caught.

The α-olefin (co) polymer resin (B) and the α-olefin-ethylene Copolymer resin (C) each have a melting point (DSC- Method) of generally 120 to 175 ° C, preferably 150 to 175 ° C. If a resin (B) or a resin (C) with  such a melting point can be used synthetic pulp with improved Preserve the strength properties of the heat seal become.

The α-olefin (co) polymer resin (B) and the α-olefin-ethylene Copolymer resin (C) has a medium one Molecular weight distribution (Mw / Mn) measured by GPC, generally 1.5 to 3.5, preferably 2.0 to 3.0. If a resin (B) or a resin (C) with such a narrow Average molecular weight distribution range the resulting pulp has one improved heat sealability at much lower Temperatures and high strength of the heat seal.

The polyolefin resins (A), (B) and (C) can be used alone or in Combination as the starting material of the invention synthetic pulp can be used. The same as above described polyolefin resins (A), (B) and (C) can by polymerization or copolymerization of one or several corresponding α-olefins in the presence of so-called metallocene olefin polymerization catalysts with a metallocene catalyst component, such as. B. described in JP-A-6-9724, JP-A-6-136195, JP-A-6-136196 and JP-A-6-207057, made to end polymers with to get the desired properties.

The metallocene olefin polymerization catalyst is formed from a metallocene catalyst component (a), which has a Group IVB transition metal compound is at least one ligand with cyclopentadienyl skeleton; and an organooxyaluminum catalyst component (b); and optionally a finely divided carrier (c), one  organoaluminum catalyst component (d) and / or an ionizable or ionic catalyst component (e).

The transition metal compounds which are preferred as metallocene catalyst components (a) can be represented by the following general formula (I):

MLx (I)

wherein M is a Group IVB transition metal, e.g. B. Zirconium, titanium or hafnium, preferably zirconium; x is the valence of the transition metal M; and L is a with ligand coordinated to the transition metal M, where at least one ligand L is a ligand with a Cyclopentadienyl skeleton and several ligands L each can be the same or different.

Examples of ligands L with a cyclopentadienyl skeleton include Cyclopentadienyl, alkyl substituted Cyclopentadienyl groups, such as methylcyclopentadienyl, Dimethylcyclopentadienyl, trimethylcyclopentadienyl, Tetramethylcyclopentadienyl, pentamethylcyclopentadienyl, Methylethylcyclopentadienyl and hexylcyclopentadienyl, and also indenyl, 4,5,6,7-tetrahydroindenyl and Fluorenyl groups. These groups can e.g. B. with Halogen atoms or trialkylsilyl groups.

When a compound of formula (I) two or more Has ligand L with a cyclopentadienyl skeleton, can use two of the ligands L with cyclopentadienyl skeleton with each other via an alkylene group, such as. B. ethylene, Propylene or isopropylidene, a substituted one  Alkylene group such as diphenylmethylene, silylene or a substituted silylene group, such as dimethylsilylene, Diphenylsilylene or methylphenylsilylene.

Examples of ligands L which do not have a cyclopentadienyl skeleton include hydrocarbon groups having 1 to 12 carbon atoms; Alkoxy groups such as methoxy; Aryloxy groups such as phenoxy; Trialkyl or triaryl substituted silyl groups, such as trimethylsilyl or triphenylsilyl; or SO ₃ R (where R is a hydrocarbon group of 1 to 8 carbon atoms, which may contain substituents such as halogen atoms), halogen atoms or hydrogen atoms.

Examples of hydrocarbon groups from 1 to 12 Carbon atoms close alkyl groups, such as. B. Methyl, cycloalkyl groups, such as. B. cyclopentyl, Aryl groups such as As phenyl, and aralkyl groups, such as. B. Benzyl, a.

Examples of SO ₃ R ligands include p-toluenesulfonate, methanesulfonate and trifluoromethanesulfonate.

Listed below are examples of metallocene compounds having the formula (I):

Bis (cyclopentadienyl) zirconium dichloride,
Bis (methylcyclopentadienyl) zirconium dichloride,
Bis (ethylcyclopentadienyl) zirconium dichloride,
Bis (n-propylcyclopentadienyl) zirconium dichloride,
Bis (n-butylcyclopentadienyl) zirconium dichloride,
Bis (n-hexylcyclopentadienyl) zirconium dichloride,
Bis (methyl-n-propylcyclopentadienyl) zirconium dichloride,
Bis (methyl-n-butylcyclopentadienyl) zirconium dichloride,
Bis (dimethyl-n-butylcyclopentadienyl) zirconium dichloride,
Bis (n-butylcyclopentadienyl) zirconium dibromide,
Bis (n-butylcyclopentadienyl) zirconium methoxy chloride,
Bis (n-butylcyclopentadienyl) zirconium ethoxy chloride,
Bis (n-butylcyclopentadienyl) zirconium butoxy chloride,
Bis (n-butylcyclopentadienyl) zirconium ethoxide,
Bis (n-butylcyclopentadienyl) zirconium methyl chloride,
Bis (n-butylcyclopentadienyl) zirconium dimethyl,
Bis (n-butylcyclopentadienyl) zirconium benzyl chloride,
Bis (n-butylcyclopentadienyl) zirconium dibenzyl,
Bis (n-butylcyclopentadienyl) zirconium phenyl chloride, and
Bis (n-butylcyclopentadienyl) zirconium hydride chloride.

In these connections the disubstituted Cyclopentadienyl groups 1,2- and 1,3-substituted Cyclopentadienyl groups, and trisubstituted Cyclopentadienyl groups include 1,2,3- and 1,2,4- substituted cyclopentadienyl groups. Likewise Metallocene compounds can be used in which the Zirconium metal in the above zirconium compounds Titanium or hafnium is replaced.

Particularly preferred among the above-mentioned metallocene compounds:

Bis (n-propylcyclopentadienyl) zirconium dichloride,
Bis (n-butylcyclopentadienyl) zirconium dichloride,
Bis (1-methyl-3-n-propylcyclopentadienyl) zirconium dichloride, and
Bis (1-methyl-3-n-butylcyclopentadienyl) zirconium dichloride.

In the present invention, one or more Metallocene compounds of formula (I) can be used.

As the organooxyaluminum catalyst component (b) aluminoxanes are preferably used. Examples of this include methylaluminoxanes, ethylaluminoxanes and Methylethylaluminoxanes, usually about 3 to each 50 basic units of the formula -Al (R) O- (where R is a Alkyl group). Such aluminoxanes can conventional methods.

The finely divided carrier (c), which is used in the manufacture of the Olefin polymerization catalyst if desired Can be used can be granular or fine inorganic or organic compound with ordinary a particle diameter of e.g. B. about 10 to 300 microns, preferably 20 to 200 microns.

Preferred inorganic carriers are porous oxides, such as SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO and SnO ₂ and mixtures thereof. The inorganic oxides can contain a small amount of carbonates, such as Na ₂ CO ₃ , sulfates, such as Al ₂ (SO ₄ ) ₃ , nitrates, such as KNO ₃ , or oxides, such as LiO ₂ .

Although properties of the inorganic supports can vary depending on their types and processes for their preparation, inorganic supports having a specific surface area of 50 to 1000 m ² / g, more preferably 100 to 700 m ² / g and a volume porosity of 0 are preferred according to the invention , 3 to 2.5 cm ³ / g used.

If necessary, the inorganic carriers can 100 to 1000 ° C, preferably at 150 to 700 ° C, before the Use calcined.

Homopolymers and are as finely divided organic carriers Copolymers of α-olefins with 2 to 14 carbon atoms or homopolymers and copolymers of aliphatic, alicyclic and aromatic vinyl compounds, such as Vinylcyclohexane or styrene can be used.

The organoaluminum catalyst component (d), the if desired in the preparation of the olefin Polymerization catalyst can be used closes z. B. trialkyl aluminum compounds such Trimethyl aluminum, alkenyl aluminum compounds such as Isoprenyl aluminum, dialkyl aluminum halides such as Dimethyl aluminum chloride, alkyl aluminum sesquihalides, such as methyl aluminum sesquihalide, Alkyl aluminum dihalides, such as methyl aluminum dichloride, Alkyl aluminum hydrides such as diethyl aluminum hydride or Mixtures thereof.

The ionizable or ionic catalyst component (s), which can optionally be used in the preparation of the catalyst, includes e.g. B. Lewis acids such as triphenylboron, MgCl ₂ , Al ₂ O ₃ and SiO ₂ -Al ₂ O ₃ as described in U.S. Patent 5,321,106; ionic compounds such as triphenylcarbenium tetrakis (pentafluorophenyl) borate; Carboranes such as dodecaborane, bis-n-butylammonium (1-carbododeca) borate; or mixtures thereof.

The polyolefin resin used as the raw material for the synthetic pulp according to the invention can be used  by polymerization or copolymerization of one or several corresponding α-olefins in the presence of the above mentioned metallocene olefin polymerization catalyst the metallocene catalyst component (a) and the Oxyaluminum organic catalyst component (b) and optionally the finely divided carrier (c), the organoaluminum catalyst component (d) and / or the ionizable or ionic catalyst component (s) be prepared so that the polyolefin resins (A), (B) or (C) can be obtained. The (co) polymerization can be carried out in Gas phase or liquid phase, such as. B. in slurry or in a solution, carried out under suitable conditions become.

In slurry or solution polymerization can be used as Solvent used an inert hydrocarbon , but you can also use the single olefin per se use if it is liquid under the reaction conditions is.

For the polymerization, the metallocene compound (a) is preferably used in an amount, based on the transition metal atom, of 10 ^-8 to 10 ^-3 g atom / l polymerization system, preferably 10 ^-7 to 10 ^-4 g atom / l.

In addition to the oxyaluminum organic catalyst component (c) and the organoaluminum catalyst component (d), both of which are supported on a support (b), can also support unsupported (free) catalyst components (b) and / or (d) with one another in the polymerization system available. In this case the atomic ratio (Al / M) of aluminum atoms (Al) from the free  Catalyst component (b) and / or (d) for Transition metal atom (M) generally in the range of 5 to 30, preferably 10 to 200, more preferably 15 to 150.

The polymerization temperature is usually in the range (for a slurry polymerization) from -50 to 100 ° C, preferably 0 to 90 ° C; for solution polymerization from -50 to 500 ° C, preferably 0 to 400 ° C; and for gas phase polymerization from 0 to 120 ° C, preferably 20 to 100 ° C. The polymerization can be carried out at a pressure of from atmospheric pressure to 100 kg / cm ² , preferably from 2 to 50 kg / cm ² , either batchwise or semi-continuously or continuously. Multi-step polymerization methods can also be used, in which two or more steps are carried out either in the liquid or gas phase or first in the liquid phase and then in the gas phase. In addition, it is also possible to prepolymerize a monomer in the liquid phase in the presence of the catalyst components and then to polymerize it in the gas phase in the presence of the resulting prepolymerized catalyst.

Synthetic polyolefin pulp

The synthetic polyolefin pulp according to the invention can using the polyolefin resins (A) mentioned above, (B) or (C) or their mixtures according to conventional known techniques.

For example, the manufacture of synthetic Polyolefin pulps extensively in the Encyclopedia of  Chemical Technology, 3rd edition, volume 19, pages 420 to 425. One can be cited as an example Method in which a fiber spun from the melt cut short and then smashed, and one Method in which a lightning-like spinning out of solution or emulsion is running, making a fibrous Product is obtained, which is then broken.

The synthetic polyolefin pulp according to the invention is preferably by lightning-like spinning from solution or Emulsion produced. A is particularly preferred Flash spinning process from the emulsion using of polyvinyl alcohol (PVA) as a hydrophilic agent, wherein the PVA preferably in the resulting synthetic Polyolefin pulp in an amount of 0.01 to 10% by weight, based on the total weight of pulp and PVA (or attached).

The synthetic material according to the invention preferably has Polyolefin pulp an average fiber length of 0.1 to 10 mm and a drainage of 700 ml or less according to the Canadian Standard Freeness (CSF).

Field of application of synthetic polyolefin pulp

The synthetic polyolefin pulp according to the invention can alone or in combination with natural and / or other synthetic pulps and / or fiber material for the production of various synthetic papers or paper webs are used. Paper making or paper web formation can be done by conventional techniques be carried out. The papers or paper webs that made up  a simple or mixed pulp, can be used as such for various purposes or otherwise with other papers or paper webs be laminated.

The synthetic polyolefin pulp according to the invention can particularly suitable for the production of heat sealable Papers such as B. for tea bags and Desiccant bags can be used. Furthermore can the synthetic polyolefin pulp according to the invention in dry milled form z. B. as a runner Preventive agent for coating materials, as Sealant, sealant and thickener additive can be used for adhesives. The inventive synthetic polyolefin pulp can be mixed with natural pulps, like pulp, can be mixed to make it water repellent To produce paper webs which, for. B. as label papers, Tissue paper, paper towels and paper wipes can be used. For the production of synthetic Papers, e.g. B. usable as form liner papers , the synthetic pulp according to the invention can also can be mixed with other synthetic pulps.

In addition, the synthetic pulp according to the invention to be mixed with other pulverized pulps Paper webs and mats for absorbing liquids, such as water, oils, solvents and urine. Further uses for the inventive synthetic pulp close z. B. dry binder for woven or open fibers, wire and cable coatings, Insulation papers, book cover papers, liquid absorbent and retaining articles, such as Battery separators, cement products such as fiber cements,  Gas and liquid filters, masks, ceramic papers, Shaped cardboards such. B. cardboard container, sterilizing Paper bags, wallpaper, reinforcing materials for cushioning floor coverings, reinforcing fibers for Wall materials, tile cement, filter aids, etc., on.

Heat sealable paper

As described above, the inventive synthetic polyolefin pulp particularly suitable for Manufacture of heat seal papers, e.g. B. for tea bags and Desiccant bags can be used.

Heat seal papers are well known and can be made from Mixtures of a cellulose pulp and a synthetic Pulp or by a combined processing of Papers made separately from both pulps were manufactured. The Papermaking conditions such as B. that Mixing ratio of cellulose pulp to synthetic Pulp and the respective basic weights can be suitable in Depending on the intended use and the desired properties of the resulting Heat seal paper can be selected.

Effect of the invention

The heat-sealable pulp according to the invention uses a special polyolefin resin as raw material, so it Make heat-sealable papers and films available  can, which at a temperature around the melting point of the Base material resin can be heat sealed and which have excellent heat seal strength exhibit.

Examples

The present invention is now becoming larger Verbosity with reference to the following examples explained.

Properties of the synthetic pulps and those in the Examples and comparative examples obtained Synthetic papers were made using the following methods certainly:

Medium fiber length

The fiber length was measured using a measuring device for the medium fiber length type FS-200 manufactured by Cayani Co., Finland. The mean fiber length is called Weight average specified.

Canadian Standard Freeness (freeness)

Measured according to JIS P-8121

Heat seal strength Heat sealing method

A heat sealable paper was heat sealed with a heat seal tester manufactured by Tester Sangyo Co. under the following conditions:

Seal rod width: 0.5 mm
Seal pressure: 2.0 kgf / cm ²
Sealing time: 1.0 sec.
Sealing temperature: 120 ° C, 125 ° C, 130 ° C, 135 ° C, 140 ° C, 145 ° C and 150 ° C, with the temperature of the upper and lower rod being the same

Measurement of the heat seal strength

A tensile test was measured on the sample obtained above using a tensile tester operating at constant speed:

Shape of the sample: 15 mm wide, 100 mm long
Peeling speed: 100 mm / min
Temperature: 23 ° C

Reference example 1 Preparation of the olefin polymerization catalyst

6.3 g of silica, which has been dried at 250 ° C for 10 hours was suspended in 100 l of toluene. The suspension was cooled to 0 ° C and then 41 l of a toluene solution of Methylaluminoxane (Al: 0.96 mol / l) over 1 hour added dropwise while the temperature in the system at 0 ° C was held. The reaction was then at 0 ° C for 60 hours  executed and then the temperature over 1.5 Hours to 95 ° C and at this temperature 4 Hours continued. The temperature was then raised to 60 ° C lowered and the supernatant removed by decanting, so that a solid was obtained.

The resulting solid was washed twice with toluene washed and then resuspended in 125 l of toluene. To the 15 l of a toluene solution of bis (n- butylcyclopentadienyl) zirconium dichloride (Zr: 42.7 mmol / l) added dropwise at 30 ° C in the course of 30 minutes and the Reaction continued at 30 ° C for 2 hours. The supernatant was removed and the residue twice with hexane washed so that a solid catalyst containing 6.2 mg Zirconium per gram was obtained.

Preparation of the prepolymerized catalyst

8.5 kg of the solid catalyst obtained above was added 300 l of hexane, which contained 14 mol of triisobutyl aluminum, given, and ethylene at 35 ° C for 7 hours prepolymerized so that a prepolymerized Catalyst with 3 g of polyethylene per gram of solid catalyst was obtained.

Making a linear low density Polyethylene resin

In a continuous fluid bed polymerizer, ethylene and 1-hexene were copolymerized in the presence of the prepolymerized catalyst obtained above. The resulting linear low density polyethylene resin contained 3.0 mol% 1-hexene and had a density of 0.920 g / cm ³ , an MFR of 4.0 g / 10 min. and an Mw / Mn of 2.0. This linear low density polyethylene resin was used in Example 1.

Reference example 2 Preparation of an olefin polymerization catalyst

In a stream of nitrogen, 10 moles of one became commercially available available anhydrous magnesium chloride in 50 l dehydrated and purified hexane suspended and 60 mol of ethanol over a period of 1 hour with stirring added dropwise and then the mixture Room temperature implemented for 1 hour. Then 27 mol Diethyl aluminum chloride to the mixture at room temperature added dropwise and then stirred for 1 hour.

100 mol of titanium tetrachloride were then added to the mixture given and the temperature of the system increased to 70 ° C and at this temperature the reaction for 3 hours with stirring carried out. The resulting solid was through Decanted separated, repeated with purified hexane washed and suspended in hexane.

Making a linear low density Polyethylene resin

In a 200 liter continuous polymerization apparatus, ethylene and 4-methyl-1-pentene were copolymerized in the presence of the catalyst obtained above. The resulting linear, low density polyethylene resin contained 3.2 mol% 4-methyl-1-pentene and had a density of 0.920 g / cm ³ , an MFR of 4.0 g / 10 min. and an Mw / Mn of 3.8. This linear low density polyethylene was used in Comparative Example 1.

Reference example 3 Preparation of the olefin polymerization catalyst

A solid catalyst was prepared in the same way as in Reference Example 1 prepared, except that bis (1-methyl 3-n-butylcyclopentadienyl) zirconium dichloride instead of Bis (n-butylcyclopentadienyl) zirconium dichloride used has been.

Preparation of the prepolymerized catalyst

A prepolymerized catalyst was made in the same way as prepared in Reference Example 1, except that the solid catalyst obtained above was used.

Manufacture of linear low density polyethylene resins

Three linear low density polyethylene resins were used on the produced in the same way as in reference example 1, except that the gas composition of the monomers was varied that the resins with that in each case in table 1 MFR, density and Mw / Mn were obtained. The resulting resins were used in Examples 2-4 used.  

The properties of those in Reference Examples 1 to 3 linear low density polyethylene resins obtained summarized in Table 1.

example 1

In a stirred 300 l autoclave with an insert 10 l of n-hexane (23 ° C), 10 l of water (23 ° C), 1000 g linear low density polyethylene resin according to Reference example 1 and 20 g of polyvinyl alcohol (PVA, Degree of saponification: 99%, viscosity of a 4% aqueous Solution (20 ° C): 4.6 to 6.0 cps, trade name Gosenol N-05, available from Nihon Gosei Kagaku Co.). The Mixture was stirred at 900 rpm. to 145 ° C heated and then further at this temperature 30 Stirred minutes and thus obtained a suspension.

The autoclave was equipped with a nozzle with a diameter of 3 mm and a length of 20 mm, through which the resulting suspension in a drum under a Nitrogen atmosphere and at a reduced pressure of -400 mmHg was injected where the solvent rapidly evaporated (flash evaporation), leaving a fibrous Product came into being.

Using the resulting fibrous product became an aqueous slurry with a concentration of 10 g / l in a container and in one disc-like refiner with a diameter of approx. 30.5 cm smashed so that a synthetic polyethylene pulp obtained with the properties shown in Table 2 has been.  

The synthetic polyethylene pulp obtained above and a cellulose pulp with a weight ratio of 1: 1 (2.1875 g each) were stirred together and mixed with 2 liters of water in a JIS pulper for 10 minutes to obtain an aqueous slurry. This slurry was placed in a Fourdrinier paper machine, and the wet paper formed was then dried in a rotary dryer having a surface temperature of 100 ° C to obtain 25 cm x 25 cm heat seal paper with a basis weight of 70 g / m ² . The heat seal strength of the resulting heat seal paper was determined by the measurement method described above and is shown in Table 3.

Comparative Example 1

A synthetic polyethylene pulp was made on the same Made as in Example 1, except that in Linear polyethylene resin obtained in Reference Example 2 was used. Then a heat seal paper was placed on the made the same way with this pulp. The Properties of the synthetic pulp and the The heat seal strength of the heat seal paper is in the Tables 2 and 3 shown.

Examples 2 to 4

A synthetic polyethylene pulp was made on the same Made as in Example 1, except that each of the  three linear polyethylene resins, which according to Reference Example 3 were obtained was used. Then became a heat seal paper the same way with everyone resulting pulp produced. The characteristics of the synthetic pulps and the heat seal strength of the Heat seal papers are shown in Tables 2 and 3 specified.

Table 1

Properties of the polyethylene resins used as raw material

Table 2

Properties of synthetic pulps

Table 3

Heat seal strength of the heat seal papers

Claims (4)

1. Synthetic polyethylene pulp, comprising as raw material:

• A) a linear ethylene-α-olefin copolymer resin comprising ethylene and 50 mol% or less of an α-olefin having 3 or more carbon atoms and a melt flow index (ASTM D 1238, 190 ° C) of 0.1 to 1000 g / 10 min., A density of 0.900 to 0.980 g / cm ³ and an average molecular weight distribution (Mw / Mn) according to GPC of 1.5 to 3.5; and or
• B) a homopolymer or copolymer resin which comprises at least one α-olefin having 3 or more carbon atoms and a melt flow index (ASTM D 1238, 230 ° C.) of 0.1 to 1000 g / 10 min., A melting point of 120 to 175 ° C and has an average molecular weight distribution (Mw / Mn) according to GPC from 1.5 to 3.5; and or
• C) an α-olefin-ethylene copolymer resin comprising an α-olefin having 3 or more carbon atoms and 14 mol% or less ethylene and a melt flow index (ASTM D 1238, 230 ° C) of 0.1 to 1000 g / 10 min., Has a melting point of 120 to 175 ° C and an average molecular weight distribution (Mw / Mn) according to GPC of 1.5 to 3.5, with the proviso that component (A) is mandatory.

2. Synthetic polyethylene pulp according to claim 1, characterized in that the  linear ethylene-α-olefin copolymer resin (A), the α-olefin homopolymer or copolymer resin (B) or that α-olefin-ethylene copolymer resin (C) using a metallocene catalyst is produced. 3. Synthetic polyethylene pulp according to claim 1 or 2, also comprising a polyvinyl alcohol in an amount of 0.01 to 10 wt .-%, based on the Total weight of the synthetic pulp and Polyvinyl alcohol. 4. Synthetic polyolefin pulp according to one of the Claims 1 to 3 with an average Fiber length from 0.1 to 10 mm.