CA1119355A

CA1119355A - Inorganic filler material and polymer composition containing the same

Info

Publication number: CA1119355A
Application number: CA000342751A
Authority: CA
Inventors: Joseph Silberberg; Edward D. Weil
Original assignee: Stauffer Chemical Co
Current assignee: Stauffer Chemical Co
Priority date: 1978-12-29
Filing date: 1979-12-28
Publication date: 1982-03-09
Also published as: JPS5925819B2; BR7908572A; ZA797053B; US4251436A; AU5424179A; AU529071B2; ES8204453A1; JPS5592748A; EP0013142A1; KR830001334A; ES487334A0; KR830001215B1

Abstract

Abstract of the Disclosure An inorganic filler material which has improved compatibility characteristics with certain polymeric substrates is disclosed. This filler material is one which is treated with an effec-tive amount, for such improved compatibility of a composition containing a saturated hydrocarbyl acid phosphate and/or pyrophosphate compound, or an alkali metal or alkaline earth salt thereof.

Description

` 1~193S~ -IMPROVED INORGANIC FILLER MATERIAL
AND POLYMER COMPOSITION CONTAINING THE SAME

Background of the Invention .

Field of the Invention .
The present invention relates to a treated inorganic iller material having improved compatibility characteristics when added to certain polymeric sub-strates and to the filled polymer compositions im-proved by the presence of the treated filler material.

Descri tion of the Prior Art P
Inorganic fillers have been used in certain polymers, for example, thermoplastic polymers, to impart dimensional rigidity and lower costs to the resulting blend of filler and polymer. When the filler is added to such polymers at even low loadings, however, certain of the physical properties of such polymers (e.g., impact strength) begin to become adversely affected. Also, a large amount of extra energy is needed to uniformly disperse the inorganic filler in the polymer. In order to overcome these shortcamings, it has been proposed that either: (1) a polar copoly-mer be added during the polymerization of the poly-, .

~1193~S

~eric material; (2) coupling agents or other additives be added to either the filler, polymer, or filled polymer composition; or (3) the ~illed formu-:Lation be crosslinked (See Handbook of Fillers and Reinforcements for Plastics, edited by H. S. Katz et al., pp. 112 - 115, 1978).
The prior art has taught the addition of various types of coupling agents or other additives to the filler material, polymer, or the composite to improve the compatibility of the filler and polymer for one another. For example, U. S. Patent No. 3,926,873 to I. Aishima et al. advocates the use of aliphatic or aromatic carboxylic acids having from 3 to 11 carbon atoms, one or two ethylenic unsaturations, and one or two carboxyl groups as such a class of additive. A family of titanates, available from Kenrich Petrochemicals, Inc., have also been proposed for use as additives to improve the compatibility of polymer and filler (Handbook of Fillers and Reinforcements for Plastics, supra.;
Modern Plastics, December 1974, p. 68; Modern Plastics Encyclopedia, Vol. 53, No. 10A, October 1976, pp. 161 and 166; and U. S. Patent Nos. 4,094,853 and 4,098,758).
Although the prior art contains a teaching that certain phosphorus-containing compounds can function as coupling agents or adhesion promoters in adhesive systems (see P. E. Cassidy et al., J. Macromol. Sci., Revs. Polymer Technol. Dl(l) 30 pp. 2 and 22 - 23, 1971), it has not been appreciated that compositions containing hydrocarbyl phosphate and/or pyrophosphate compounds and/or their alkali metal or alkaline earth salts can be used to improve 93~

the compatibility of an inorganic filler and polymeric substrate. For example, U. S. Patent No. 3,404,023 to M. E. Schrader et al. teaches the use of diethyl phosphite (rather than a phosphate or pyrophosphate) 5_ to improve the compatibility of glass fibers with a resin substrate. Also, U. S. Patent No. 3,344,107 to R. E. Miller teaches the use of various phosphorus-containing compounds containing reactive alkenyl, acrylic or methacrylic groups (rather than non-reactive saturated hydrocarbyl groups) as couplingagents between a polymer substrate and a mineral re-inforcing agent.
SUMMARY OF THE PRESENT INVENTION

It has been unexpectedly found that compos-tions containing a titanium-free, saturated hydrocar-byl acid phosphate and/or pyrophosphate compound, and/
or an alkali metal and/or alkaline earth salt thereof, can be applied to an inorganic filler, a polymeric substrate, or the composite to improve the compat-ibility of the filler and polymeric substrate. The improved compatibility of filler and polymeric substrate is demonstrated by such physical effects as: a greater ease of dispersion of the filler material into the polymeric substrate; and certain improved physical properties for the filled polymer composite (e.g., better impact resistance, lower melt viscosity, etc.l.
Thus, in accordance with the present teachings, an inorganic filler material is provided for polymeric substrates with the filler containing an effective amount for improved compatibility with the polymeric substrate of a composition containing the saturated hydrocarbvl acid pyrophosphates, the alkali metal and alkaline earth metal salts thereof, and mixtures thereof.

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1~93~i5 -3a-DESCRIPTION OF PREFERRED EMBODIMENTS
OF THE PRESENT INVENTION
The type of inorganic filler material which can be treated in accordance with the present inven-tion is known to persons of ordinary skill in the art.

~.

~119355 It is a finely divided material having an averageparticle size of from about 0.01 micron to about 100 microns, preferahlY from about 0.03 micron to about 25 microns, so as to be suitable as a filler material for polymeric substrates. The type of inorganic filler which may be used in the practice of the present invention includes such fillers as the metal silicates and carbonates. Representative examples of two silicate materials are milled glass fiber and mica.
One preferred metal carbonate is calcium carbonate.
The present invention, as described above, in~lolves treating the inorganic filler material either before, during,or after admi~ture to the polymerwith an effective amount of a composition containing a satur-ated hydrocarbyl acid phosphate, pyrophosphate and/oralkali metal or alkaline earth metal salt thereof. The composition can contain the phosphate, pyrophosphate or salt in either substantially pure form or as a compat-ible mixture of any of said phosphates, pyrophosphates, or salts, optionally in an appropriate solvent, for ex-ample, an organic solvent, such as one of the chlorin-ated hydrocarbon solvents, or water. The amount of said phosphate, pyrophosphate and/or salt which is added to the filler material will generally range from about 0.05% to about 5%, by weight of the filler ma-terial, preferably from about 0.1% to about 3%, by weight. Representative saturated hydrocarbyl acid phosphate and pyrophosphate compounds which can be pres-ent in the aforementioned compositions and which can be treated with the alkali metal or alkaline earth salt, if desired, in accordance with the present invention include compounds of the formulae:

~119355 (I) O
(RO)nP(OH)3_n where n is either 1 or 2 and R is a saturated hydro-carbyl group which is formed by the removal of a hydrogen atom from a saturated alkyl, aryl, alkaryl, or aryl alkyl group; when n~2 each R can be different;

(II) O O
RO - P - O - P - OR'; and , OH OH

(III) o .. ..
RO - P - O - P - OH
R'O OH

where R and R' are the same or different and either has the same meaning given above for R in formula I.
Mixtures of any of the foregoing are included within the scope of the present invention. The saturated hy-drocarbyl groups include the C4-C40 alkyl groups, preferably the C4-C20 alkyl groups, the phenyl group, the alkyl phenyl, and the phenylalkyl groups. The term "alkyl" as used herein is intended to cover ali-cyclic alkyl groups, alicyclic alkyl groups substi-tuted with non-interfering radicals (e.g., halogen, alkoxy and acyloxy), which do not impart hydrophilic properties to the compound and do not react with any acid phosphate moiety which is present, and cyclo-alkyl groups. The term "phenyl" is intended to cover :

1~193~

the unsubstituted phenyl group as well as the phenyl group substituted with the aforementioned non-inter-fering substituents.
These compounds are formed by reaction of alco-hols of the formula ROH with a phosphorylating agent such as phosphoric acid, polyphosphoric acid, or phosphoric anhydride. The alkali metal or alkaline earth metal salts of these compositions (which are also intended to be encompassed by the present in-vention) are formed by reacting the compositions witha suitable alkali metal or alkaline earth metal base, such as an alkali metal or alkaline earth metal hy-droxide, carbonate, or bicarbonate.
The treated inorganic filler material can be in-corporated in the desired amount e.g., from about 5~
to about 85%, by weight of the final filler/polymeric substrate combination, to give filled polymeric ma-terials having utility as window frames, structural automobile parts, cabinet components, and the like.
Representative thermoplastic polymers that can be utilized include the polyolefinic polymers (e.g., polyethylene and polypropylene), vinyl polymers (either in rigid, non-plasticized form, in plasti-cized form, or in plastisol form), and the poly-amides (e.g., nylon ll). In utilizing the currentinvention, it has been found desirable to exercise some degree of care in selecting a given filler, given polymer, and given phosphate, pyrophosphate, and/or salt so that the results of the invention are obtained. In general, the use of an acid phosphate and/or pyrophosphate will be most applicable with polar polymers (e.g., polyamide polymers) containing either acidic te.g-, mica) or neutral (e.g., glass) fillers or with non-polar polymers (e.g., polyole-finic polymers) containing basic fillers te.g., metal carbonate fillers). The use of the neutralized alkali metal or alkaline earth salts of the acid phos-phate and/or pyrophosphate compounds will be mostapplicable with either non-polar (e.g., polyolefinic) or slightly polar (e.g., vinyl chloride) polymers when combined with basic fillers (e.g., metal carbon-ate fillers).
The present invention is further illustrated by the following Examples:

.

These Examples set forth selected physical properties for untreated (control) calcium carbonate/
polypropylene blends (Example Nos. 1 and 2), a blend of commercially available fatty acid-treated calcium carbonate and polypropylene (Example No. 3), and a series of blends made in accordance with the present invention (Example Nos. 4 - 10).
The blends of the present invention were made by mixing 60 parts by weight of polypropylene homo-polymer and 40 parts by weight of the selected calcium carbonate sample (3 to 5 micron ground lime-stone) at a temperature of about 400 to 425C. at 50 rpm. in a single screw extruder (20:1 L/D; 2 stage

2:1 compression ratio; 3.81 cm. diameter). Table 2, which is given below, lists the processing, mechanical, toughness, and heat deflection temperature (DTL) characteristics for blends made from the various calcium carbonate fillers that were tested. The test specimens were injection molded at about 370 to 400C., except for those specimens for dart drop impact and color testing which were compression molded at about 400C. In those cases where the calcium carbon-ate is treated, the agent was applied in a twin shellmixer equipped with a high speed intensifier bar from a 20 wt. % solution in methylene chloride, unless otherwise indicated. The Example numbers given below in Table 1 list the respective treatment additives for the calcium carbonate. The acid phsophate~ and pyro-phosphates listed in Table 1 are reaction mixtures of mono- and di- products:

111~3SS
g Example No. CaC03 Treatment 1 None (Control) 2 None (Control)

3 stearate (1~) (Commercial)

4 2-Ethylhexyl acid pyrophos-phate (1~) 2-Ethylhexyl acid pyrophos-phate (2~) 6 Butyl acid phosphate (1~) 7 Octyl acid phosphate (1%) 8 Octyl acid phosphate (1%)*
9 Tridecyl acid phosphate ~1%) 2-Ethylhexyl acid pyrophosphate sodium salt (1%)**
20 * applied neat and not from solution ** appliéd from an aqueous solution. The composition which was applied is available commercially as VICTAWET 35B from Stauffer Chemical Company, Specialty Chemical Division. It is formed by re-acting 2 moles of 2-ethylhexyl alcohol and 1 mole of phosphorus pentoxide and then treating the re-sulting reaction mixture with sodium hydroxide.

~i93S~

TAsLE 1 PROCESSING
Melt Visc.(1) Energy(2) 3 Example No. (poise atl035e~.l) (meter gm minxl0_ ) 1 ~Control) 2100 4.80 2 (Control) 2200 4.34 3 (Commercial) 1900 3.69 4 1900 3.70 1800 3.21 6 1900 3.46 7 1700 3.15 8 1700 3.78 9 1600 2.29 1900 2.95 (1) This test was performed at 200C. on a constant rate extrusion plastometer with a load measuring system.
(2) The energy required to mix the polypropylene/
calcium carbonate samples was determined by graphing the torque values generated by the action of a mixer measuring head (50 rpm at 205C.) versus time for zero to eight minutes on a Plastograph unit for 30 gm. of fluxed polypropylene upon addition of 30 gm. of the selected calcium carbonate. A similar curve was generated for the equivalent volume (37 gm.) of unfilled polypropylene. The area under the second curve was then subtracted from the area under the first curve to give the viscosity values per unit time in units of meter-gm-min. Lower numbers indicate a more easily processable mixture and are de~
sired.

lli93~

TABLE 2 (Cont'd.) MECHANICALS

Example Flex.Str.(3) Flex.Mod.(3)Tensile Ultimate No. (MPa) (GPa) Str.(4) Elongation(4) (MPa) %
1 51.2 2.97 25.2 70 2 49.7 2.83 24.5102 3 49.1 2.92 24.3194 4 47.2 2.70 24.1111 47.0 2.56 23.2118 6 51.0 2.98 25.1 82 7 48.0 2.68 24.1132 8 47.5 2.61 23.8113 9 47.6 2.60 24.1122 46.1 2.50 23.6182 (3) tested in accordance with ASTM D-790, Method I, Procedure B. '7':
i (4) tested in general accordance with ASTM D-638 except that the specimens were 1.27 cm. wide and 0.30 cm. thick. The gage length was 7.0 cm. and the crosshead speed was 5.08 cm./min~
, C~5512 , ~1~935~
~ 12 -TAsLE 2 (Cont'd.) Reversed Falling IzodNotch(6) Dart Example Impact (5)Impact Impact No.(J/m) (J/m) (J) 1 21 171 1.6 2 21 235 1.6 3 27 363 3.2 4 21 203 2.0 21 235 2.3 6 21 246 1.6 7 21 326 2.5 8 21 208 2.0 ~ 21 267 2.7 15 10 32 326 3.2

(5) tested in accordance with ASTM D-256, Method A, 0.3175 cm. thick specimens.

(6) tested in accordance with ASTM D-256, Method E, 0.3175 cm. thick specimens.

(7) test performed on 0.135 cm. thick sheets on a 2.2 cm. inner diame~er support ring using a 1.8 kgO dart having a tip of 0.75 cm. radius by varying the height from which the dart falls.
The listed value is the energy at which 50~ of the dart drops reslllt in fracture.

~119355 The significance of the test data described in Table 2 may be summarized as follows:
1. The processing data illustrate that acid alkyl phosphate and pyrophosphate treatments of Example Nos. 4 - 10 result in a generally equal or better melt viscosity and ease of blending than either the untreated or commercially stearate treated material (Example Nos. 1 - 3). Generally, a longer alkyl chain length in the acid alkyl phosphate or pyrophosphate 10 yields better processing properties.
2. The data relating to mechanical proper-ties illustrate that as one increases the alkyl chain length in the alkyl acid phosphate or pyrophosphate, a slight, but not serious, decrease in the strength of 15 the material is noted. Treatment with butyl acid phosphate gives a product having physical properties that closely correspond to those produced by the specimens cGntaining the untreated calcium carbonate filler.
3. The impact strength of the specimens are generally improved by treatment with the acid alkyl phosphates and pyrophosphates.

~1935S

ExAMæLEs 11 - 16 These Examples illustrate the preparation of composites of nylon 11 with a variety of fillers (at the 25~, by weight level) both with and without a small amount of didecyl acid phosphate.
Examples 11 and 12 show nylon ll/mica (375 mesh muscovite) composites, with Example 11 being a control run, and Example 12 showing the present in-vention with use of a didecyl acid phosphate additive.
Examples 13 and 14 show use of nylon 11/milled glass fiber composites, with Example 13 being a control run, and Example 14 showing the present in-vention with use of a didecyl acid phosphate additive.
Examples 15 and 16 are presented for com-parison purposes and show nylon 11/calcium carbonate composites. The presence of didecyl acid phosphate in Example 16 does not result in improved compat-ibility for the blend as compared to Control Example 15.
The various composites of nylon 1~ filler (either mica, milled glass fiber, or calcium carbon-ate) were prepared in accordance with the general process shown in Examples 1 - 10 with the didecyl acid phosphate being present in Example Nos. 12, 14 and 16 at 2%, by weight of the filler. The physical property data for these composites is as follows.
Those runs which carry the asterisk are in accordance with the present invention.

1~19355 PROCESSING PROPERTIES
Extrusion Com- (1) Melt Viscos-DTL pounding Torque ity (2) Example No. C. (meter-grams) (poiseat103sec) 12* 131 4700 4130 14* 48 3000 2820 , (1) these numbers are directly related to the partic-ular extrusion conditions that were utilized and, therefore, have significance on a relative basis only.
(2) this test was performed at 215 C. on a constant rate extrusion plastometer with a load measuring system.

-3~;~

MECHANICAL PROPERTIES - WET
Tensile Str.( ) Flexural Mod.
_ample No.(MPa) (GPa) 11 495 3.13 12* 507 3.43 13 303 1.28 14* 301 1.30 353 1.25 16 334 1.30 MECHANICAL PROPERTIES - DRY
Tensile Str.( ) Flexural Mod.
Example No. (MPa) (GPa) 11 537 3.29 12* 557 3.60 13 371 1.50 14* 352 1.46 397 1.54 16 385 1.43 (3) 24 hour soak in distilled water at 50C., followed by equilibration at 24C. and 50% relative humidity.
(4) tested in general accordance with ASTM
D-638, except that the specimens were 0.32 cm. wide and thick. The gage length was 1.42 cm. and the crosshead speed was 1.27 cm./min.

~ .

This Example illustrates the lowered pro-cessing force (equilibrium torque) required to form a composite of low density polyethylene and calcium carbonate containing 1%, by weight of the calcium carbonate, of tridecyl acid phosphate (Example 18) as compared to a control composite of low density polyethylene and calcium carbonate (Example 17).
The equilibrium torque for these compos-ites was determined by graphing the torque values generate~ by the action of a mixer measuring head (50 rpm at 205C.) on a Plastograph unit for 30 gm.
of fluxed, low density polyethylene upon addition of 30 gm of the selected calcium carbonate (either alone or in combination with the 1% of tridecyl acid phosphate). The torque value after equil-ibrium is attained in the system is the "equil-ibrium torque".
The results are as follows:

Example No.Equilibrium Torque (meter-grams) 17 (control) 1360 These Examples illustrate the use of the present invention to reduce the viscosity of vinyl chloride plastisol/calcium carbonate mixtures (Examples 20 and 21) as compared to a control mixture (Example 19). A plastisol formulation was formed by mixing in a planetary mixer 100 parts by weight of emulsion grade polyvinyl chloride (SCC-20 from Stauffer Chemical Company), 60 parts by weight of dioctyl phthalate, 5.0 parts by weight of epoxidized octyl phthalate (Drapex 4.4 from Argus Chemical)and 2 parts by weight of barium-cadmium stabilizer (Argus 565A, from Argus Chemicall. In Examples 20 and 21 were added 50 parts by weight of calcium carbonate filler which had been treated with 1%, by weight of the filler, of tridecyl acid phosphate, and the 2-ethylhexyl acid phosphate sodium salt used in Example 10, respectively. Untreated calcium carbon- -ate filler was used in Example 19. The Brookfield viscosities (No. 6 spindle) at 2 rpm/20rpm were as follows after 1 and 7 days. The values are in poise with lower values indicating a more desired, less viscous mixture:

BROOKFIELD VISCOSITY (2rpm/20rpm) (In polse) Example No. 1 day 7 days 19 (control)705/325 700/340 -- 11193~5 , . . .

This Example illustrates the use of a neutralized alkyl acid phosphate coupling agent in rigid vinyl/calcium carbonate composites (Example 23), the comparative use of an alkyl acid phosphate in a similar composite (Example 24), and a control rigid vinyl/calcium carbonate composite without any phosphate additive (Example 22).
~he rigid vinyl composition comprised 100 ' parts by weight of suspension grade polyvinyl chloride resin (SCC-676 from Stauffer Chemical Company), 3 parts by weight of acrylic process aid (K-120N from Rohm and Haas), 3 parts by weight of tin stabilizer (Thermolite 31 from M and T Chemicals), 1 part by weight of calcium stearate lubricant, 0.5 parts by weight of montan wax lubricant (Wax E from American ~`
Hoechst), and 0.1 part by weight of polyethylene lubricant (PE 629A, from Allied Chemical). To each of the formulations was added 50 parts by weignt of milled calciu~ carbonate,with the samples in Examples 23 and 24 also containing 1%, by weight of the filler, of the 2-ethylhexyl acid phosphate sodium salt of Example 10 and tridecyl acid phosphate, respectively.
The equilibrium torque values (79 gm. total, 200C., 60 rpm, and as defined in Example 18) and dart drop values for the compositions were as follows:
Equilibrium Torque Dart drop Impact( ) Example No. (meter-gram) (J) 22 (control) 3040 4.3 23* 2840 5.6 24 3600 2.7 * Present invention.

3~;5 (l)Test performed on 0.159 cm. thick sheets on a 2.2 cm. inner diameter support ring using a 1.8 kg.
dart having a tip of 0.75 cm. radius by varying the height from which the dart falls. The listed value is the energy at which 50~ of the dart drops result in fracture.

_ _ These Examples illustrate the use of an aryl acid phosphate coupling agent to enhance the dispersion of the respective materials used to form a polypropylene/
calcium carbonate composite (Example 26) and the com-parative use of untreated calcium carbonate and poly-propylene to form a composite (Example 25).
Polypropylene homopolymer (30 gm.) was fluxed for 5 minutes in a Brabender Plasticorder apparatus followed by addition of 30 gm. of calcium carbonate (3-S microns, average particle size) which had either been untreated (Example 25) or which had been treated with 1~, by weight of the calcium carbonate, of octyl-phenyl acid phosphate. The fluxing conditions insidethe apparatus were 200C. and 60 rpm. The Table given below lists the torque (in meter-grams) at suc-cessive intervals during the fluxing process with the time intervals being measured from the addition of the filler. Lower numbers are desired as indicative of a more easily processable mixture:
TORQUE (meter-grams) after Example No~ 0 min. 5 min. _ min. 15 min.

The foregoing Examples illustrate certain pre-ferred embodiments of the present invention and should therefore not be construed in a limiting sense.
The scope of protection which is sought is set forth in the claims which follow.

Claims

We Claim:

1. An inorganic filler material for polymeric substrates, said filler containing an effective amount for improved compatibility with the polymeric substrate of a composition containing the saturated hydrocarbyl acid pyrophosphates, the alkali metal and alkaline earth metal salts thereof, and mixtures thereof.

2. A filler material as claimed in claim 1 wherein the saturated hydrocarbyl acid pyrophosphate compound has a formula selected from the group con-sisting of:

and where R and R' are independently a C4-C40 alkyl group, a phenyl group, a C4-C40 alkyl phenyl group, or a phenyl C4-C40 alkyl group.

3. A filler material as claimed in claim 2 wherein R is independently a C4-C20 alkyl group or a phenyl group.

4. A filler material as claimed in claim 1 wherein said material contains from about 0.05% to about 5%, by weight of the compound.

5. A filler material as claimed in claim 4 wherein the amount of said compound is from about 0.1%
to about 3%, by weight of said filler material.

6. A filler material as claimed in either claim 4 or 5 having an average particle size range of from about 0.01 to about 100 microns.

7. A filler material as claimed in claim 2 wherein the saturated hydrocarbyl acid pyrophosphate is 2-ethylhexyl acid pyrophosphate.

8. A filler material as claimed in either claim 1 or 2 which is selected from the group consisting of the metal silicates and carbonates.

9. A filler material as claimed in either claim 1 or 2 which is selected from the group consisting of glass, calcium, carbonate and mica.

10. A polymeric substrate which contains from about 5% to about 85% by weight, of the filler material and compound of either claim 1 or 2.

11. A polyolefin substrate which contains from about 5% to about 85% by weight, of the filler material and compound of either claim 1 or 2.

12. A polyamide substrate which contains from about 5% to about 85% by weight, of the filler material and compound of either claim 1 or 2.

13. A vinyl chloride polymer substrate which contains from about 5% to about 85% by weight, of the filler material and compound of either claim 1 or 2.