Production of shaped articles

Abstract

Disclosed are electrically conducting shaped articles and also a process for producing same from granular and/or fibrous substrates.

Claims

1. A process for producing a shaped article from a substrate, the process comprising: applying an aqueous dispersion PG to the substrate to form a treated substrate, wherein the aqueous dispersion PG is obtained from a) an aqueous polymer dispersion comprising a dispersion polymer which has a glass transition temperature Tg, and b) an aqueous graphene dispersion, wherein the weight fraction of graphene is 0.01 and 20 parts by weight per 100 parts by weight of the dispersion polymer (solids/solids), and drying the treated substrate at a drying temperature T>Tg to form the shaped article, wherein the substrate is a granular substrate, a fibrous substrate, or both.

2. The process according to claim 1, wherein the weight fraction of graphene is 0.5 and 10 parts by weight per 100 parts by weight of the dispersion polymer.

3. The process according to claim 1, wherein the dispersion polymer has a glass transition temperature of 15 C. and 60 C.

4. The process according to claim 1, wherein 1 g and 100 g of binder defined as a summed total amount of the dispersion polymer and graphene solids is present per 100 g of the substrate after the applying.

5. The process according to claim 1, wherein the drying temperature T satisfies TTg+5 C.

6. The process according to claim 1, wherein the substrate is a fiber web.

7. The process according to claim 1, further comprising: shaping the treated substrate after the applying of the aqueous dispersion PG.

8. The process according to claim 1, wherein the shaped article has a greater electrical conductivity than an electrical conductivity of the substrate prior to the applying.

9. The process according to claim 1, wherein the dispersion polymer comprises: 50 and 99.9 wt % of at least one selected from the group consisting of esters of acrylic acids with alkanols of 1 to 12 carbon atoms, esters of methacrylic acids with alkanols of 1 to 12 carbon atoms, and styrene in polymerized form, or 40 and 99.9 wt % of styrene, butatdiene, or both in polymerized form, or 50 and 99.9 wt % of vinyl chloride, vinylidene chloride, or both in polymerized form, or 40 and 99.9 wt % of at least one selected from the group consisting of vinyl acetate, vinyl propionate, and ethylene in polymerized form.

10. The process according to claim 9, wherein the dispersion polymer further comprises: 0.1 and 5 wt % of at least one selected from the group consisting of a 3 to 6 carbon atom ,-monoethylenically unsaturated monocarboxylic acid, an amide thereof, a 3 to 6 carbon atom ,-monoethylenically unsaturated dicarboxylic acid, and an amide thereof in polymerized form.

11. The process according to claim 1, wherein the dispersion polymer comprises: 10.0 and 20.0 wt % of n-butyl acrylate in polymerized form, 0 and 5.0 wt % of N-methylolacrylamide in polymerized form, 45.0 and 60.0 wt % of ethyl acrylate in polymerized form, 0 and 5.0 wt % of acrylamide, methacrylamide, or both in polymerized form, and 20 and 40.0 wt % of acrylonitrile, methacrylonitrile, or both in polymerized form.

12. The process according to claim 1, wherein the substrate is a glass fiber web and the shaped article has a specific conductivity of at least 1.010.sup.3 S/cm.

13. The process according to claim 1, wherein the substrate is a glass fiber web and the shaped article has a resistance of less than 7.010.sup.4 ohms.

Description

EXAMPLES

(1) The aqueous polymer dispersion used was a 51 wt % aqueous polymer dispersion whose polymer was constructed from 18 wt % of n-butyl acrylate, 50 wt % of ethyl acrylate, 25 wt % of acrylonitrile, 4 wt % of acrylamide and 3 wt % of N-methylolacrylamide in polymerized form and had a glass transition temperature of 30 C. (midpoint temperature of ASTM D 3418-12, as determined by differential scanning calorimetry; heating rate 20 K/min) and the average corpuscle size of which was 310 nm (as determined to ISO standard 13 321; cumulant z-average).

(2) To produce the graphene-containing aqueous polymer dispersion, 24.525 parts by weight of deionized water, 0.225 part by weight of Tamol NN 9401 (sales product of BASF SE) and 0.168 part by weight of graphene were initially charged in a mixing vessel at room temperature (20 to 25 C.) and the graphene was dispersed by 10-minute ultrasonication (UP 400 S H 7 ultrasonicator) with cooling. This was followed by adding 5.082 parts by weight of the aforementioned aqueous polymer dispersion and the mixture obtained was mixed homogeneous. The mixture obtained was adjusted to a total solids content of 3.7 wt % by diluting with deionized water. The mixture obtained is hereinafter referred to as binder liquor B1.

(3) The aforementioned aqueous polymer dispersion itself was also diluted to a solids content of 3.7 wt % with deionized water. The dilute aqueous polymer dispersion obtained is hereinafter referred to as binder liquor V.

(4) Performance Testing

(5) To produce bonded fiber webs, the base web used was a glass fiber web (28.5 cm in length and 27 cm in width) with a basis weight of 53 g/m.sup.2 from Whatman International Ltd, Springfield Mill, James Whatman Way, Maidstone, Kent ME14 2LE England.

(6) To apply the aqueous binder liquors (impregnation), the glass fiber webs were passed in the longitudinal direction, on an endless PES foramanous belt, at a belt speed of 2.0 m per minute, through respectively the aforementioned 3.7 wt % aqueous binder liquors B1 and V. The aqueous binder liquors were subsequently sucked off to adjust the wet pickup to 286 g/m.sup.2 (corresponding to 10.6 g/m.sup.2 of binder reckoned as solids). The impregnated glass fiber webs thus obtained were dried/cured in a Mathis oven on a plastics mesh as support at 180 C. in a maximal hot air stream for 3 minutes. After cooling down to room temperature, test strips measuring 24050 mm were cut out in the fiber longitudinal direction. The test strips obtained were subsequently conditioned for 24 hours at 23+ C. and 50% relative humidity (standard conditions) in a conditioning room. The glass fiber web test strips obtained are hereinbelow referred to as test strips B1 and V, in correspondence with the employed binder liquors B1 and V.

(7) Determination of Dry Breaking Strength

(8) Dry breaking strength was determined at room temperature on a Z005 tensile tester from Zwick-Roell. Test strips B1 and V were clamped vertically into a tensioning device such that the free clamped length was 200 mm. Thereafter, the clamped test strips were pulled apart in the opposite direction at a speed of 10 mm per minute until the test strips broke. Dry breaking strength is reported in newtons per 50 mm after standardization to 64 g/m.sup.2. The higher the force needed to break the strips, the better the corresponding breaking strength. Five measurements were carried out in each case. The values reported in table 1 each represent the average value of these measurements.

(9) Determination of Wet Breaking Strength

(10) To determine their wet breaking strength, the test strips were kept in deionized water at 80 C. for 15 minutes and thereafter excess water was dabbed off with a woven cotton fabric. Wet breaking strength was determined on a Z005 tensile tester from Zwick-Roell. Test strips B1 and V were clamped vertically into a tensioning device such that the free clamped length was 200 mm. Thereafter, the clamped test strips were pulled apart in the opposite direction at a speed of 10 mm per minute until the test strips broke. The higher the force needed to break the strips, the better the corresponding breaking strength. Five separate measurements were carried out in each case. The values reported in table 1 each represent the average value of these measurements.

(11) Determination of Hot Breaking Strength

(12) Hot breaking strength was determined on a Z010 tensile tester from Zwick-Roell whose tensioning device was located in a heatable chamber. Test strips B1 and V were clamped vertically in the preheated chamber at 180 C. into a tensioning device such that the free clamped length was 100 mm. After 1 minute waiting time at 180 C. the clamped test strips were pulled apart in the opposite direction at a speed of 25 mm per minute until the test strips broke. The higher the force needed to break the strips, the better the corresponding breaking strength. Five separate measurements were carried out in each case. The values reported in table 1 each represent the average value of these measurements.

(13) TABLE-US-00001 TABLE 1 Breaking strength dry, wet and hot V B1 [data in N/5 cm, Test strip weight corrected to 64 g/m.sup.2] dry breaking strength 62.0 62.2 wet breaking strength 9.6 10.7 hot breaking strength 21.6 32.4

(14) Determination of Flexural Stiffness

(15) The aforementioned glass fiber webs bonded with binder liquors B1 and V and cooled down were die cut to cut out in each case 10 test strips 7030 mm in the machine and cross directions of the web. The test strips obtained were then stored under standard conditions for 24 hours.

(16) Flexural strength was determined using a type Z 2.5 tester from Zwick-Roell. The aforementioned test strips were clamped into the sample holder and flexed with a measured length of 10 mm over the edge of the force sensor at a speed of 6 per second up to a deformation of 30 while the maximum force applied was determined (in mN). The test was carried out in the machine and cross directions for each of 5 test specimens. The higher the maximum force needed, the better the corresponding flexural stiffness. The values reported in table 2 represent the average value of the respective 5 individual measurements.

(17) TABLE-US-00002 TABLE 2 Flexural stiffnesses in machine and cross directions Test strip V B1 flexural stiffness [data in mN] in MD 107 114 in XD 86 93

(18) Electrical Properties of Graphene-Containing Glass Fiber Web

(19) A 28.527 cm glass fiber web impregnated with binder liquor B1, dried and cured was subjected to a determination of the sheet resistance using a Loresta GP instrument from Mitsubishi and an ESP probe.

(20) To this end, the sheet resistance and the corresponding layer thicknesses were determined at five different places (center and also top center, bottom center, center right and center left, each 2 cm from the edge) of the impregnated 28.527 cm glass fiber web and used to determine the averaged sheet resistance and the average value of the specific conductivity. In fact, the averaged sheet resistance was found to be 6.810.sup.4 ohms and the average value found for the specific conductivity was 1.110.sup.3 S/cm.