IL27802A - Film-forming thermoplastic polymeric vinyl chloride compositions,and sheet products made therefrom - Google Patents

Description

27802/2 jna o"i yn D» » a Pilm-foraing thermoplastic polymeric vinyl chloride compositions, and sheet products made therefrom -MTEOATHa EDISON The present invention relates to polymeric thermoplastic materials based on polyvinyl chloride; more particularly the present invention relates to polymeric thermoplastic materials endowed with such chemical and physical characteristics as to make their use particularly convenient in form of films (including blown tubular films) in the agricultural field, in the packing field in general and more particularly in the field of bags and containers.

It is known that in conventional vinyl chloride polymer formulations for the manufacture of bags from tubular films obtained by blow-extrusion, the addition of an increasing proportion of *he plasticiser, the filler contents being the same improves the cold-flex -temperature, More particularly, the addition of alkyl diesters of aliphatic polycarboxylic acids gives rise to considerable improvement of the cold-flex temperature, Simultaneously, however, the addition of an increasing proportion of plasticisers leads to a progressive decrease in the value of the tensile strength, a progressive increase of the ultimate percentage elongation and an increase of the deformation of the manufactured article under constant load (creep); therefore, the overall effect of the addition of plasticisers is an improvement in the resistance to mechanical stress of the bags at low temperature coupled unfortunately with an increase in their deformation at higher temperatures, particularly above 10°C. an It is also known that the addition of/increasing proportion of mineral filler, the plasticisers contents being the same, leads to the contrary effect, favouring a progressively containing a high quantity of mineral filler the price of which is lower than that of the polymeric material itself and of the plasticiser itself.

An object of the present invention is to improve the physical-mechanical characteristics, particularly the characteristics of resistance to the breaking at temperatures lower than 10°C and the characteristics of deformation under load at temperatures higher than 10°C9 of thermoplastic polymeric materials based on vinyl chloride polymers containin a high proportion of mineral filler. ¾he invention consists broadl in a vinyl chloride polymer composition containing a mineral filler, preferably in an amount exceeding 5 parts by weight for 100 parts by eight of polymeric material, and a plasticiser comprising; a) at least one alkyl ester of an aliphatic poly-carboxylic acid, and b) at least one ester of an aromatic polycarboxylic acid in which (a) is at least 0$ of the plastifying mixture by weight.

It has been found that vinyl chloride polymer compositions can be formulated according to the invention to give films (including blown tubular films) in which the characteristics of deformation at a temperature higher than 10GC are considerably reduced in comparison with the similar materials which are on the market, while in the meantime the flexibilit (the brittleness at lo temperature) is kept within pre~established limits also in the presence of high quantities of mineral filler. it is therefore possible to attain the surprising result of -improving, the characteristics of deformation under load at a t emperature higher than +10°C and the characteristics of flexibility at low temperatures , which are known to be affected in a completely opposed manner b the same additive (either plasticiser or mineral filler).

It will be understood that, in carrying the invention into effect, conventional additives such as heat and light stabilizers, antioxidants, lubricants, ultra-violet absorbers and dyestuffs may be incorporated ae desired.

The expression vinyl chloride polymer is used herein to mean polymeric materials obtained by the polymerization Of vinyl chloride alone or with other monomers polymerizable therewith, containing at least 7 $ by weight of chemically combined vinyl chloride, as well as the polyblends and graft polymers and copolymers of vinyl chloride.

In the case of vinyl chloride homopolymer it is preferred to use products obtained by polymerization in aqueous suspension, with a molecular weight, determined by measurement of viscosity in cyclohexanone at 0.40 weight/volume and at 25°C, corresponding to a value of the viscosity ranging from 0.30 to 0.75 and with particle . sizes ranging from 150 to 50 microns.

A preferred class of mineral filler includes calcium carbonate, calcium silicate, diatomaceous earth, quartz, silica and alumina, and it may be used in quantities ranging from 5 to 50 and preferably around 20 parts by weight with respect to 100 parts by weight of vinyl chloride polymer. Calcium carbonate is particularly suitable; it may be used in the form of particles covered with mineral waxes, fatty acids, soaps least 0$ has a diameter lower than 5 microns and at least 80 has a diameter lower than 15 microns.

Particularly suitable (a) components for the plasticiser are the alkyl esters of citric, isomalic, adipic, sebacic and azelaic acids..-A particularly preferred class is constituted by the alkyl esters of adipic and azelaic acid wherein the alkyl residues, which may be the same or different from each other, have a linear or branched chain of 4 to 13 carbon atoms.

The (a) esters are used in quantities ranging from 40 to 95 parts by weight with respect to 100 parts by weight of the plasticiser mixture.

The best resultsare attained when said component (a) is used in amounts higher than 50 parts by weight in respect to 100 parts by weight of the plasticiser mixture. In the case of dioctyl adipate a preferred plasticiser mixture contains about 4$ by weight of this latter.

Particularly suitable (b) components for the , plasticiser are the alkyl, aryl and alkylaryl esters of phthalic acid and o glycol bis-phthalates wherein the alkyl residues whic may be the same or different from each other, have a linear or a branched chain of 4 to 13, preferably 6 to 10 carbon atoms, the aryl is preferably phenyl and the alkylaryl is preferably benzyl, the glycol in the ease of bis-glycol esters having a linear or branched chain with 2 to 8 carbon atoms.

These (b) esters are used in amounts ranging from 5 to 60: parts by weight with respect to 100 parts by weight of the plasticiser mixture. The best results are attained when said component (b) is used, in amounts lower than 50 parts by weight in res ect to 100 arts b wei ht of the lasticiser mixture.

In the ease of dioctylphthalate a preferred plastlciser mixture contains about 46% of this latter.

The following examples illustrate the present invention.

Example 1 100 parts by weight of a commercial polyvinyl chloride known as SICROI 548 FM ("Sicron" is a Registered Trade Mark) were mixed at room temperature for 5 minutes with the following solid additives: - 20 parts by weight o CaCO^ of the type known on the market as Omya BSH ■=» 5 parts by weight of basic lead phosphite - 0.5 parts by weight of stearic acid.

The mixture thus obtained was brought to 60°C after which the plastifying composition was introduced in quantities ranging from 35 to 60 parts by weight, constituted by mixtures of any two or more of the following compounds, provided that each such mixture contains the dioctyl adipate s ·* dioctyl phthalate (DOP) - butylbenzylphthalate (BB3?) - diisodecylphthalate (DIDP) and - dioctyl adipate (DOA) The mixture thus obtained was masticated at 90°G for 10 minutes, cooled to 40°C and removed from the blender. The "dry-blend" so obtained was then worked on a mill-roll, with the rolls at 150°C, for 8 minutes and the raw sheet thus obtained was sent into a dicer.

In order better to estimate the mechanical characteris" " the mechanical characteristics were carried out.

Such procedure of determination has been chosen in order to have data which were homogeneous and comparable with each other, since they were obtained from isotropic material.

As it is well known, films differently oriented during their formation can have mechanical characteristics depending on their orientation (stretching) and thus display a remarkably different behaviour.

To this purpose the granules prepared as above described, were reworked on a mill-roll at 150°0 for 5 minutes to obtain a sheet of polymeric material from which the test plate was obtained. The type and procedures of preparation varied according to the mechanical property to be determined as follows: a) Plates for obtaining a specimen on which tensile strength (ASTM D-412) and cold-flex temperature (ASTM D-1043) measurements were carried out 75 g» of the polymeric composition as above prepared were introduced into a square mould which was subjected to a pressure of 75 atm. within a vertical plate-press at a temperature of 150°C for a period of 3 minutes; it was then cooled to room temperature. The plate thus obtained had a thickness of 1.5 mm. b) Plates for the measurement of the Shore "A" hardness (ASTM Ρ-Γ706) , , 40 g of the polymeric composition as above prepared were introduced into a square mould which was subjected to a pressure of 75 atm. x^ithin a vertical plate-press at a temperature of 150°C for a period of 4 minutes after which it was cooled to room temperature* The plate had a thickness of 3 mm. < c) Plates for obtaining a specimen on which the measurements of the deformation of the material under constant load (creep) were carried out. (Internal method according to the description contained in ASTM D-674). _ 180 g of the polymeric composition as above prepared, were introduced into a square mould which was subjected at first to a preheating for 2 minutes at 150°C and subsequently within a vertical plate-press at a pressure of 125 atm* at 150°C for 4 minutes; a slow cooling was then carried out to room temperature in order to avoid deformations or stresses in the polymeric material following a sudden lowering of temperature.

The plate had a thickness of 1.5 mm, d) Plates for obtaining a specimen on which the measurements of the tear resistance were carried out, (ASTM D 689) g of a mixture as above prepared ¾rere introduced into a square mould which was subjected to a pressure of 75 atm. within a vertical press plate a a temperature of 150°C for a period of 3 minutes; then it was cooled to room temperature. The plate had a thickness of 0.2 mm.

Table 1 gives the data relatin to the mechanical characteristics of polymeric composition prepared as above defined in which one of the components was o^atfliited from the plasticiser mixture, as indicated in the table.

Table 1 Components PVC parts by weight 100 100 100 100 DOP M w -· ■ 12.5 12.5 12.5 BBP ■ " " 12.5 - 12.5 12.5 DIDP " " 12.5 12. - 12.5 DOA " " 12.5 12.5 12.5 -. · Filler: 20 20 20 20 Mechanical Characteristics 2 Modulus Kg/mm 1.65 1.70 1.60 1.75 Tensile strength Eg/cm 2.25 2.30 2.20 2.4 Ultimate elongation - $ 240 230 235 235 Shore "A" Hardness 91 91 89 93 Creep (tf = 0.6 ·5 13.7 12.8 12.4 Tear resistance g/mm a.t+ 23°C 5800 6800 7000 5700 Tear resistance g/mm at.+10°C 3100 3300 3400 2500 Tear resistance g/mm ato°C 1800 1900 2000 1000 Cold-flex temperature at 135.000 p.s.i. °C -11.0 -14.0 -10.0 -1,0 (*) Variation of the deformation under constant load during ten days.

It can be seen that (the amount of mineral filler being the same) the absence in the plastifying composition of DOP, BBP and DIDP, respectively, has little effect on the tear characteristics and also on the cold-flex temperature, whereas the absence of BOA provokes a remarkable decrease of the tear resistance at 0°C and obviously of the cold-flex temperature.

.- - Example 2 She preceding example was repeated but using a plastifying system wherein the quantity of DOA and DOP was 100 parts progressively increased from 0 to 25 gartsiS>r/by weight of polyvinyl chloride. The results thus obtained are reported in the following Table.

Table II Components PVC parts by weight 100 100 100 100 100 100 DOP ·' «» . » 12.5 25 12.5 12.5 12.5 BBP " " tt 12.5 12.5 12.5 12.5 12.5 12.5 DIDP " " " 12.5 12.5 12.5 12.5 12. 12.5 DOA " " " 12.5 12.5 12. 12.5 25 Filler 20 20 20 20 20 20 Mechanical Properties · 2 Modulus Kg/mm 1.65 1.10 0.6 1.75 1.10 0,65 2 Tensile strength Kg3mm 2.25 1,90 1.55 2.40 1.90 1.50 Ultimate elongation $ 240 280 330 235 280 330 Shore WAM Hardness 91 81 73 93 81 72 Creep { = 0.6 Kg/mm2 13.3 21*5 31.6 12.4 21.5 31.5 Tear resistance g/mm at + 23°C 5800 9000 9000 5700 9000 9400 Tear resistance g/mm at + 10°G 3100 6000 7800 2800 6000 7500 Tear resistance g/mm at 0°C 1800 3600 4500 1800 3600 5300 it it t* n, «1Q®G . 1000 2100 3500 1000 2100 5000 Cold-flex temperature (at 135000 psi)°C -11.0 -26 -35 -1. -26 -41.< - It can be seen that an increase from 0 to 25 parts by xieight of DOP and of DOA, the other components being equal, changes the mechanical creep characteristics at room temperature in practically the same wayj on the contrary at a t emperature lower than +10°G the increase of the quantity of DOA improves surprisingly the tear resistance.

Example 3 Three polymeric compositions were prepared as described in Example 1, using 100 parts of polyvinyl chloride together with normal additives using a plastifying system constituted by 45.5 by weight of DOP and by 54· $ by weight of DOA but in the presence of different quantities of mineral filler (CaGO^).

The results attained with regard to the mechanical characteristics are reported in the following table III. gable III Components • (a) (h) Co) PTC parts by weight 100 100 100 DOP " « 20 20 20 DOA " " 24 24 24 Filler (GaCO^) " 0 20 40 Mechanical properties Modulus (Kg/mm2) 1 1.1 l.; Tensile strength (Kg/mm ) 1.90 1.75 1.6i Ultimate elongation % 300 280 250, Shore "A" Hardness 80 83 84 Creepy o.g Kg/mm2 24 19 17 Tear resistance g/mm at + 23°C 8000 9000 8000 " » at + 10°G 6500 6500 4000 . '? » at 0°G 4300 4300 1800 Gold-flex temperature °C 26 -25 -24 From the above-reported data it can be seen that, the type and the quantities of the used plastifier being equal, an increase of the quantity of mineral filler involves a worsening of the tear resistance at temperatures equal or lower than + 10°Cj simultaneously there is* already at room temperature* a decrease in the value of the tensile strength and of the ultimate elongation and furthermore a reduction of the deformation under a constant load.

In consideration of the strong variation of the value of the tearasg resistance at Q°C, by passing from 20 to 40 parts of filler, it is preferred, except in special cases, not to exceed 20 parts by weight of mineral filler in respect to 100 parts by weight of polymeric material♦ Example 4 By operating as in Example 1 two polymeric compositions having different plastifying compositions and different quantities of mineral filler were prepared* The composition A) was typical of PVC bags with good general performances? the composition ) , see under point (b) in table III, which, as above stated, is endowed xith a complex of very good properties.

The results attained as regards the mechanical characteristics of the two materials in the form of plates having the thickness of 1.5 mm (and of 0.2 mm for the measurement of tear resistance) are summarized in the following Table IV: Table IV Components (A) (B) PVC parts by weight 100 100 DOP " " " 26 20 BBP " " " 15 - DOA " « " 10 24 CaG05 " " " 40 20 (a) (b) Mechanical characteristics 2 Modulus Kg/ram 0.9 : 1.1 Tensile strength Kg/mm 1.5 Ί.75 Elongation $ 240 280 Shore "A" Hardness 79 83 Creep c" = 0.6 Kg/mm Alg ¾ 23 19 Tear resistance at + 23°C 7000 9000 M " at f 10°G 4000 6500 " " at + 0°C 2000 4300 Cold-flex temperature °C - 25 - 25 In the following Table V the data are reported relating td the mechanical characteristics of films obtained through blow°extrusion (thickness of 0.2 mm) obtained from two materials A) and B). a) ASTM D 882 transversally 1.-1.2 1.1-1,3 longitudinally 1.8-2 2.2-,2.4 ASTM D 882 transveisaLly longitudinally g/mm Tear resistance at + 23 C ASTM D 689 \ transversally g/mm 10.000 10.000 longitudinally g/mm 5000 7000 At + icre transversally 6000 8000 longitudinally 2500 4000 At 0°C g/mm transversally 3500 500Q g/mm Finally, starting from the blown tubular films, two series of bags were prepared with the polymeric materials A) and B) . " ·'■ These bags were filled with 50 kg of ammonium sulfate, were conditioned at 0°G for a period of 2 weeks, then they were subjected to falling tests from a given height in such a way that the fall takes place sideways, along the greater side in order to establish the mechanical resistance of the tubular bags b the percentage of bags broken by the fall.

TABLE VI Materials ' A) B) Bag size - cm 50 x 82 50 x 82 50 x 82 50 x 82 Height of fall - cm 100 160 100 160 Test temperature - °C 0° 0° 0° 0° Breaking o 60 100 20 60 From the Tables IV, V, VI , it can be seen that by: a) reduction of the filler quantity b) reduction of the plasticiser quantity c) enrichment in DOA of the plasticiser mixture the surprisin result of improving simultaneously the deformation under constant loan both of the material and of the bag made therefrom and the tensile strength and tear resistance at low temperature is obtained.

In faet, at temperatures higher than 10°C, the dimensional stability was improved since the "creep" was reduced, and at the same time, the behaviour, at temperatures lower than ° EXAMPLE 5 Example 2 was repeated but using dioetyl azelate instead of dioctyladipate. The quantity of dioctylazelate and dioctyladipate was progressively increased from 0 to parts by weight in respect to 100 parts by weight of polyvinyl chloride* The results thus obtained are reported in the following table VII.

TABLE VII Components FVC parts by weight 100 100 100 100 100 100 DOP w 12.5 25 12.5 12.5 12.5 BBP " " 12.5 12.5 12. 12.5 12.5 12.5 DIDP " rt 12.5 12.5 12. 12.5 12.5 12.5 DOAz 11 n (*) 12.5 12,5 12.5 - 12.5 25 Filler (CaCO^) " 20 20 20 20 20 20 Mechanical Properties Modulus Eg/mm 1.70 1.15 0.70 1.75 1.15 0.70 Tensile strength Kg/mm 2.30 1.95 1.60 2.40 1.95 1.55 Ultimate Elongation 250 290 345 235 290 345 Shore "A" Hardness 92 82 74 93 82 73 2 Creep (tf == 0.6 Kg/mm ) 14.4 22.6 32.7 12.4 22.6 32.7 Tear resistance g/mm at + 23°0 6000 9500 9500 5700 950010000 Tear resistance g/mm at lOOC 3250 6300 8200 2800 6300 7900 Tear resistance g/mm at 0°C 2000 3900 4900 1800 3900 5600 Cold flex temperature (at 135000 psl)°C -10.0 -25 -34 *1.5 -27 -42.0 DOAz a= dioetyl azelate Comparison of the data of Table Vil shows that by increasing the amount of BOP and of DOAz from 0 to 25 parts by weight, the other components being equal, the mechanical and creep properties at room temperature suffer practically the same variations : on the contrary at a temperature lower than + 10°C the increase of the quantity of DOAz surprisingly improves the tear resistance. 27802/2

Claims (7)

CLAIMS polymeric

1. ilm - forming/thermoplas ic vinyl chloride compositions containing from 5 to 50 parts by weight of mineral filler for 100 parts of polymer and a plasticizer mixture comprising: a) at least one aliphatic dialkyl ester of iso-malic, citric, adipic,; sebacic or azelaic acid whose alkyl groups are the same or different and have a linear or branched chain of 4 to 13 carbon atoms, in an amount of at least 40 by weight of the plasticizer mixture; and b) at least one alkyl, aryl* or alk laryl ester of phthalic acid or of"a glycol bis-phthalate, where the alkyl groups are the same or different and have a linear or branched chain with 4 to 13 preferably 6 to 10 carbon atoms, the aryl is preferably phenyl and the alkylaryl is preferably benzyl, and the glycol in the case of a bis-phthalate has a linear or branched . chain with 2 to 8 carbon atoms·

2. Thermoplastic compositions according to Claim 1 containing calcium carbonate, calcium silicate, diatpmaceous earth, quartz, silica and/or alumina as a mineral filler in an amount of from 5 to 50 parts by weight for 100 parts of the vinyl chloride polymer.

3. Thermoplastic compositions according to Claim 2, wherei the filler comprises calcium carbonate of such particle size that 50$ has a diameter lower than 5 microns and at least 80% has a diameter lower than 15 microns, the particles preferably having a coating of mineral wax, fatty acid or soap. 27802/2 - 19 -

4. Thermoplastic compositions according to Claim 1, 2 or 3.» wherein the ester (a) is dioctyladipate and the ester (b) is dioctylphthalate , the ester (a) being used in an amount of about 54$ by weight of the plasticiser mixture.

5., Thermoplastic compositions according to Claim 1, substantially as described in any of the foregoing Examples.

6. Films (including tubular films) when obtained from the thermoplastic compositions according to any of Claims 1 to 5.

7. Bags, welded or glued containers, when obtained from the thermoplastic compositions according to any of Claims 1 to 5* PCiCB