Method for treating the surface of particles, the thus obtained particles and use thereof
20170066924 · 2017-03-09
Assignee
Inventors
Cpc classification
International classification
C08K3/30
CHEMISTRY; METALLURGY
C09C1/02
CHEMISTRY; METALLURGY
C08K9/08
CHEMISTRY; METALLURGY
Abstract
A method for producing surface-treated particles includes surface treatment of titanium dioxide, barium sulfate, zinc sulfide or lithopone particles, and to mixtures of the particles with alkoxylated siloxanes and phthalate-free plasticizers for improving dispersion in plastics.
Claims
1. Particles comprising: TiO.sub.2, BaSO.sub.4, ZnS or lithopone with a coating comprising at least one compound of formula (I) ##STR00004## in which R is R.sup.1, methyl or hydroxy, R.sup.1 is a polyether group of formula (II):
Z(OC.sub.mH.sub.2m-(n-1)).sub.o[O-(EO.sub.x,PO.sub.y,BO.sub.z)R.sup.3].sub.n(II), in which Z is equal to a branched or unbranched alkylene group having 2 to 4 carbon atoms, m is 2 to 4, n is 1 to 3, o is 0 or 1, EO.sub.x, PO.sub.y, BO.sub.z is an oxyalkykene group, containing oxyethylene (EO), oxypropylene (PO) and/or oxybutylene (BO) units, wherein x, y and z are each 0 and at least one of x, y and z is unequal to 0, R.sup.3 is hydrogen when n=1, or is a hydrocarbon group having 1 to 4 carbon atoms, and with the provision that in R.sup.1 the sum of carbon and oxygen atoms is at least 70, a is 20 to 200, b is 1 to 50, with the provision that when none of the groups R is equal to R.sup.1, b is at least 3, and comprising at least one phthalate-free plasticiser, wherein the at least one compound of formula (I) is present with a proportion of from 0.01 to 2% by weight, and wherein the at least one phthalate-free plasticiser is present with a proportion of from 0.01 to 4.0% by weight, wherein the values in % by weight relate to the weight of the used dried primary particles.
2. The particles according to claim 1, wherein in formula (I): R.sup.1 is a polyether group of formula (II), in which Z is equal to an unbranched alkylene group having 2 to 4 carbon atoms, o is 0, x is 0 to 20, y is 5 to 100, z is 0 to 20.
3. The particles according to claim 1, wherein the numerical ratio of index a to index b in formula (I) is equal to 8 to 18.
4. The particles according to claim 2, wherein the index x is between 0.05 and 1.2 times the sum of indices y+z.
5. The particles according to claim 2, wherein: R is equal to methyl, R.sup.3 is hydrogen, a is 80 to 95, b is 5 to 8, x is 3 to 5, y is 10 to 25, z is 0.
6. The particles according to claim 1, wherein the particles are TiO.sub.2.
7. The particles according to claim 1, having a dust value of at most 30 mg per 100 g of surface-treated particles.
8. The particles according to claim 1, wherein the at least one phthalate-free plasticiser is selected from the group consisting of esters of aliphatic hydrocarbons having 6 to 21 carbon atoms with at least one acid group selected from the group consisting of a carboxyl group, sulfonyl group SO.sub.3H, and sulfinyl group SO.sub.2H, with a monovalent or polyvalent aliphatic alcohol having 6 to 20 carbon atoms or a monovalent or bivalent aromatic alcohol, and esters of aromatic 1,4-(para)dicarboxylic acids or aromatic tricarboxylic acids with a monovalent or polyvalent aliphatic alcohol having 6 to 20 carbon atoms.
9. A method for producing surface-treated particles comprising TiO.sub.2, BaSO.sub.4, ZnS or lithopone, wherein primary particles from TiO.sub.2, BaSO.sub.4, ZnS or lithopone are brought into contact, simultaneously or in succession, with at least one compound of formula (I) ##STR00005## in which R, R.sup.1, a and b have the meanings as recited in claim 1, and with at least one phthalate-free plasticiser or mixtures thereof, wherein the at least one compound of formula (I) is present with a proportion of from 0.01 to 2% by weight, and wherein the at least one phthalate-free plasticiser is present with a proportion of from 0.01 to 4.0% by weight, wherein the values in % by weight relate to the weight of the used dried primary particles.
10. The method for producing surface-treated particles from TiO.sub.2, BaSO.sub.4, ZnS or lithopone according to claim 9, wherein at least one compound of formula (I) ##STR00006## is used, wherein, in formula (I): R.sup.1 is a polyether group of formula (II), in which Z is equal to an unbranched alkylene group having 2 to 4 carbon atoms, o is 0, x is 0 to 20, preferably 3 to 15, y is 5 to 100, preferably 8 to 50, z is 0 to 20.
11. The method for producing surface-treated particles from TiO.sub.2, BaSO.sub.4, ZnS or lithopone according to claim 9, wherein the at least one phthalate-free plasticiser is selected from the group consisting of esters of aliphatic hydrocarbons having 6 to 21 carbon atoms with at least one acid group selected from the group consisting of a carboxyl group, sulfonyl group SO.sub.3H, and sulfinyl group SO.sub.2H, with a monovalent or polyvalent aliphatic alcohol having 6 to 20 carbon atoms or a monovalent or bivalent aromatic alcohol, and esters of aromatic 1,4-(para)dicarboxylic acids or aromatic tricarboxylic acids with a monovalent or polyvalent aliphatic alcohol having 6 to 20 carbon atoms.
12. Particles from TiO.sub.2, BaSO.sub.4, ZnS or lithopone, obtainable by the method according to claim 9.
13. (canceled)
14. A composition comprising a polymer and/or a plasticiser having particles according to claim 1.
15. The composition according to claim 14, wherein the polymer is a thermoset or thermoplastic.
16. The composition according to claim 14, wherein the composition is a masterbatch, a plastic moulded article, or a plastic film.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0154]
[0155]
EXAMPLES
Example 1
Surface Treatment of Particles
V1: Treatment of TiO.SUB.2 .Particles in Dry Phase
[0156] Starting material for the dry surface treatment of titanium dioxide was a TiO.sub.2 in rutile modification with an inorganic modification of silicon oxide and aluminium oxide directly from the spray dryer discharge. This powder was mixed with the components specified in Table 1 annexed at the end of the description, in the quantities as specified, and was homogenised in a Ldige mixer for 60 seconds. The surface-treated TiO.sub.2 was then ground dry in a steam jet mill with 18 bar steam. Alternatively, the grinding can be carried out by means of a pin mill, air jet mill, roller mill or ball tube mill. Tests were carried out in the following Examples 2-4 with the samples thus produced.
V2: Treatment of TiO.SUB.2 .Particles in Wet Phase
[0157] Starting material for the wet surface treatment of TiO.sub.2 with polyether siloxanes and phthalate-free plasticisers was a TiO2 filter cake after the inorganic modification, wherein the TiO2 was present in the rutile modification and the inorganic modification consisted of silicon dioxide and aluminium oxide. This filter cake was redispersed in water by means of dissolvers, and a polyether siloxane emulsion and phthalate-free plasticiser were added to the suspension. This obtained suspension was spray-dried, and then the spray core was ground dry with the aid of a steam jet mill with 18 bar steam.
V3: Treatment of BaSO.SUB.4 .Particles in Dry Phase
[0158] Starting material for the dry surface treatment of barium sulphate with polyether siloxane and phthalate-free plasticisers was a wet-chemically precipitated barium sulphate (what is known as blanc fixe), which had not yet been ground dry, i.e. was steam jet ground for example. Polyether siloxane and phthalate-free plasticisers were added to this powder, and the mixture was homogenised in a Ldige mixer for 60 seconds. The BaSO.sub.4 wetted with polyether siloxane and phthalate-free plasticiser was then ground dry in a steam jet mill with 10 bar steam. Alternatively, the grinding can be carried out by means of a pin mill, air jet mill, roller mill or ball tube mill.
V4: Treatment of ZnS Particles in Dry Phase
[0159] Starting material for the dry surface treatment of zinc sulphide with polyether siloxane was a wet-chemically precipitated zinc sulphide (what is known as sachtolith), which had not yet been ground dry, i.e. was steam jet ground for example. Polyether siloxane and phthalate-free plasticisers were added to this powder, and the mixture was homogenised in a Ldige mixer for 60 seconds. The ZnS wetted with polyether siloxane and phthalate-free plasticiser was then ground dry in a steam jet mill with 10 bar steam. Alternatively, the grinding can be carried out by means of a pin mill, air jet mill, roller mill or ball tube mill.
V5: Treatment of Lithopone Particles in Dry Phase
[0160] Starting material for the dry surface treatment of lithopone with polyether siloxane was lithopone that had been produced in a wet-chemical precipitation of BaSO.sub.4 and ZnS and which had not yet been ground dry, i.e. was steam jet ground for example. Polyether siloxane and phthalate-free plasticisers were added to this powder, and the mixture was homogenised in a Ldige mixer for 60 seconds. The lithopone wetted with polyether siloxane and phthalate-free plasticiser was then ground dry in a steam jet mill with 10 bar steam. Alternatively, the grinding can be carried out by means of a pin mill, air jet mill, roller mill or ball tube mill.
Example 2
Determination of the Properties of the Surface-Treated Particles
V1: Dust Determination
[0161] 100 g of the substance to be tested were weighed into the fall box (1). The fall box was locked using the lever (2) and suspended in the glass cylinder (3). The test tube (6) was filled with quartz wadding, weighed, and inserted into the glass cylinder (3). The end of the test tube (6) was closed via the gate (4). The other end was connected to a vacuum pump (8) by a vacuum tube via a washing flask (7) filled with quartz wadding. After 5 seconds the fall box (1) was unlocked. The pigment dropped into the glass cylinder and dust formed. After 10 sec the gate (4) was opened. After 20 seconds the vacuum pump was set in operation and exactly 20 l of air were sucked through the glass cylinder. The power of the vacuum pump was 10 l/min. Once the vacuum pump had been switched off, the previously weighed test tube was removed and weighed again. The weight difference was specified as the dust measurement. This determination was carried out twice. The average values of these measurements of the samples are specified in Table 1 (unit: mg/100 g of material).
V2: Powder Flowability
[0162] The powder flowability was determined using an RST-XS ring shear tester. The bulk material sample was filled into the measurement cell and loaded from above via a cap with a force (normal force) of 3.5 kPa. The shear cell rotated slowly (co) during the measurement. The cap was prevented from rotating with the aid of two tie rods. The bulk material sample was subjected to shear deformation. The required force (F.sub.1 and F.sub.2) was measured. The flowability ff.sub.c of the bulk material was determined from the ratio of consolidation stress .sub.1 to bulk material strength .sub.c. The measurement results are presented in Table 1.
[0163] The greater is the flowability ff.sub.c, the better the bulk material flows. The following ranges of different flowability were defined (D. Schulze, Pulver and Schttgter (Powder and Bulk Materials), Springer publishers, 2006, chapter 3.1.4, page 42):
[0164] ff.sub.c less than or equal to 1, not fluent, hardened
[0165] ff.sub.c of greater than 1 to equal to 2, very cohesive (to not fluent)
[0166] ff.sub.c of greater than 2 to equal to 4, cohesive
[0167] ff.sub.c of greater than 4 to equal to 10, slightly fluent
[0168] ff.sub.c greater than 10, freely fluent.
Example 3
Compositions
V1: Masterbatches
[0169] The compositions with thermoplastics are also referred to as masterbatches. These masterbatches can be produced in accordance with the following procedure.
[0170] A dry blend was first produced from the surface-treated pigments (TiO.sub.2) to be tested and polyethylene as an example of a thermoplastic (LDPE: Lupole Purell 1800 SP 15) in a concentration of 50% by weight by weighing both components into a plastic flask and then mixing them for 15 min on a jar rolling mill. The resultant dry blend was then placed into a Brabender metering unit and fed via a screw conveyor to the Leistritz DS Extruder ZSE 18HP twin-screw extruder for processing. Processing to turn the blend into a masterbatch was performed at a rotational speed of 150 revolutions per minute (rpm) and a temperature setting of 150 C. in all zones. The polymer strand was granulated.
[0171] After this procedure, the compositions containing samples 1-5 according to Table 1 were produced.
V2: White Paste
[0172] White pastes were produced as an example for compositions.
[0173] 90 g of dioctyl phthalate (DOP) were weighed into a 250 ml dissolver jar. Under light stirring, 167 g of the surface-treated particles were incorporated in portions using a 3 cm dissolver plate (approximately 5 m/sec) within 3 minutes. The dissolver was started up at 12500 rpm and dispersed for five minutes.
[0174] After this procedure, the compositions containing samples 1-5 according to Table 1 were produced.
Example 4
Testing of the Dispersibility of Surface-Treated Particles
V1: Testing of the Masterbatches in a Pressure Filter Test
[0175] The dispersibility was assessed in a pressure filter test on the basis of the rise in pressure before the filter created during the extrusion of a polymer melt via a screen pack.
[0176] The pressure filter value was determined using a Brabender Plasti-Corder LAB Station single-screw extruder (screw diameter/length: 30 mm/25D). A screen pack from the company FKD with a PZ-Microdur 14 (nominal filter fineness 14 m) and a supporting fabric with a mesh size of 315 m was used.
[0177] The extruder was heated to a temperature of 200 C. The temperature of the filter equipment was set to 230 C. Once the extruder had been thoroughly flushed with LDPE, the filter receptacle with the screen pack was installed. Once the TiO.sub.2/LDPE masterbatch granulate to be tested had been fed and the pigmented material discharged at the bypass, the melt flow was guided via the screen pack and the computer-assisted acquisition of measurement data was started. The measurement data were recorded until a maximum pressure of 150 bar was reached, or, with a low rise in pressure, for a period of 60 minutes. The throughput was 40 g/min.
[0178] The measurement results are presented below in Table 1.
[0179] The measure for the dispersibility was the pressure filter value (DF), which is calculated in accordance with the following formula:
[0186] The lower is the pressure filter value, the better is the dispersion of the pigment in the polymer. The samples according to the invention had good dispersibility.
V2: Testing of the Masterbatches in the Polymer Flat Films:
[0187] The dispersion behaviour of pigments in polymers was tested on the basis of the number of agglomerates in a flat film.
[0188] The masterbatches according to Example 3 (V1) were extruded in accordance with the following method to form films. The masterbatches were diluted with LDPE granulate (Purell PE 3020H) to a concentration of 10% by weight pigment (TiO.sub.2). The masterbatch and polymer granulate were placed for this purpose in a plastic flask and shaken by hand for minute. The sample was then extruded on a Brabender Plast-Corder LAB Station single-strew extruder (screw diameter/length: 30 mm/25D) at 15 rpm and at a temperature of 190 C. A film approximately 8 cm wide was discharged via a flat film die. The film strand was drawn over a belt conveyor, cooled, and rolled up.
[0189] 5 pieces approximately 50 cm long from the film strand were inspected. The assessment was performed under transmitted light with regard to the number of undispersed agglomerates at two different magnifications (0 times: no magnification; 30 times: at thirty times magnification). Here, the size of the specks, which consist of incompletely dispersed agglomerates, had no influence on the scoring.
[0190] The results were scored in a five-tier system, in which score 1 means no specks, score 2 means isolated specks (there were test areas having 1 to 2 specks, but also test areas with no specks), score 3 means moderate number of specks (all test areas had specks, on average these were present in an amount of less than 5 per test area), score 4 means a lot of specks (all test areas have 5 to 10 specks), and score 5 means a very high number of specks (all test areas have at least 10 specks on average).
[0191] The values in Table 1 below are given as scores counted from 5 test areas. From score 3 the masterbatches are unsuitable for the production of films. The samples according to the invention had good dispersibility.
V3: Testing in Plasticisers
[0192] The granularity of pigments in a white paste under defined dispersion conditions was determined. For this purpose, 3 g of the produced white pastes according to Example 3 (V2) were stirred well in a plastic beaker with the same amount of DOP using a spatula. To determine the fineness the diluted paste was first placed on a Hegman gauge (grindometer), more specifically on a 0 to 100 m Hegman gauge, and then the correspondingly fine samples were placed on a 0 to 25 m Hegman gauge (Erichsen). The visually determined fineness values were noted in m and are presented in Table 1 below. A fineness of more than 20 m indicates poor dispersion.
TABLE-US-00001 TABLE 1 Polyether siloxane according to Food approval ffc values formula I (x) (Indirect Dust mass Pressure filter with or not Food Contact mg/100 g value PE film score (Example 4 v.2) RST-XS according to pursuant to (Example [bar * cm.sup.2/g] without with 30x Fineness ring shear Sample formula I () Plasticiser EU 10/2011) 2) (Example 4 V.1) magnification magnification [m] tester 1 x (0.45%) without yes 40 0.9 1- 1-2 1.5 1.5 plasticiser 2 x (0.45%) 0.2% yes 8 1.09 1-2 1-2 2.2 2.2 Hexamoll DINCH (BASF) 3 (0.45%) without no 37 0.9 1 1-2 1.4 1.4 plasticiser 4 (0.45%) 0.2% no 8 2.5 2 2-3 1.8 1.8 Hexamoll DINCH (BASF) 5 without 0.3% yes 8 18.5 3 3-4 1.3 1.3 polyether Mesamoll TP siloxane LXS 51067 (Lanxess)
[0193] Under consideration of the measured values in Table 1, it can be determined that only the particles according to the invention and the corresponding compositions have good results in the measurement results of the example tests. None of the comparison particles or comparison compositions according to samples 1, 3, 4 or 5 can attain such good measured values in terms of the dust mass, the pressure filter value, the PE film score, or the fineness in plasticiser paste. The particles according to the invention are approved for indirect food contact pursuant to EU 10/2011 and have a low dust value and good dispersibility.