Abstract: The measurement of electrokinetic potential is of importance in paper-making. A measuring cell (12) for a specific potential known as streaming potential of the kind disclosed in EP B1 0 079 726 is now provided with measuring electrodes (40, 42) of a metal which forms a reversible electrochemical reaction with pure water to oxidize the metal. The electrodes (40, 42) used in the measurement mode in the cell have a film comprising an oxide of the metal electrochemically formed thereover. Such electrodes are found to give more stable and consistent measurement than the stainless steel electrodes used previously. Silver, lead, copper and alloys such as lead and silver are preferred. The measuring electrodes (40, 42) are regenerated within the cell (12) through electrochemical reduction to bare metal, followed by oxidation to re-form the film. This is performed with the aid of auxiliary electrodes (60, 62) in the cell. A control system (50) for the measurement and regeneration mode is described.

Abstract: A colour developing composition for use in pressure-sensitive (carbonless) copying paper sets comprises an inorganic pigment extender (e.g. kaolin, talc or calcined kaolin) and a hydrated silica/hydrated alumina composite. The composition is produced by precipitating the hydrated silica/hydrated alumina composite in the presence of the extender by the following steps:a) gradually adding a metal silicate solution to a solution of an aluminium salt which is initially at a pH below 4 until the pH of the resulting mixture is approximately 4, thereby to induce some precipitation and to form a sol;b) gradually adding alkali to said sol to raise the pH to approximately 7, thereby to induce further precipitation and gel the sol or further gel the sol, said gelled sol being a hydrated silica/hydrated alumina composite;c) separating the resulting product from the aqueous medium and washing to remove dissolved salts; andd) drying the washed product and reducing it in particle size.

Abstract: Resin coated photographic base paper having improved stiffness is made by co-extruding a face side resin coating having a first layer of pigmented LDPE and over it a thin layer of a stiff polymer, especially polycarbonate. An intermediate layer of a strongly adhesive polymer may be included to enhance bonding between the first and second layers. The base paper may also have a co-extruded wire side resin coating with a stiff polymer second layer.

Abstract: A solvent composition for use in pressure-sensitive copying papers comprises a mixture of vegetable oil and a mono- or di-functional ester of a fatty acid or other acid composed of a non-aromatic saturated or unsaturated straight or branched hydrocarbon chain and a single terminal carboxyl group.

Abstract: A security paper authenticating system comprises, in combination, a security paper carrying both starch and an iodate salt, typically potassium iodate, and an authenticating composition comprising an acidic solution of an iodide salt, typically potassium iodide, the system being such that on applying the authenticating composition to authentic security paper, as by a pen, brush or stamp pad, iodine is generated and a characteristic starch-iodine coloration is produced. The authenticating composition is preferably aqueous or part-aqueous, and is preferably made acidic by means of a weak organic acid such as tartaric acid. The authenticating composition preferably also contains an antioxidant such as ascorbic acid. The invention extends to the paper and the authenticating composition individually.

Abstract: An air permeable sheet-like structure comprising 5% to 50% by weight of reinforcing fibres, and between about 5 and about 50 millimeters long, and from 50% to 95% by weight of wholly or substantially unconsolidated particulate non-cross-linked elastomeric material, and in which the fibrous and elastomeric components are bonded into an air permeable structure.

Abstract: A method of making a fibrous web containing at least two particulate materials and which includes mixing the dry particulate materials together in a substantially dry condition, using the dry mix to form at least part of an aqueous dispersion of fibres, and draining the dispersion to form a web.

Abstract: A color developing material is produced by:a) gradually adding a metal silicate solution to a solution of an aluminum salt which is initially at a pH below 4 until the pH of the resulting mixture is approximately 4, thereby to induce some precipitation and to form a sol;b) gradually adding alkali to said sol to raise the pH to approximately 7, thereby to induce further precipitation and gel the sol or further gel the sol, said gelled sol being a hydrated silica/hydrated alumina composite;c) separating the gel from the aqueous medium and washing the resulting product to remove dissolved salts; andd) drying the washed product and reducing it in particle size.This color developing material is then formulated into a coating composition, applied to a paper base and dried to produce a color developing record material as used in pressure-sensitive (carbonless) copying pape sets.

Abstract: A chromogenic compound for use in pressure- or heatsensitive record material has the general formula (I):R.sub.1 --CH.dbd.CH--CR.sub.3 (OR.sub.4)--CH.dbd.CH--R.sub.2 (I)in which:R.sub.1 and R.sub.2 are the same or different and each is a group of one of the formulae (II): ##STR1## in which the benzene ring of the group of formula (IIa) is optionally further substituted, and in which:R.sub.10 and R.sub.11 are each independently hydrogen or an optionally-substituted alkyl, aryl or aralkyl group, orR.sub.10 and R.sub.11 together with the nitrogen atom to which they are attached form an optionally-substituted heterocyclic ring, which may include one or more further hetero atoms;R.sub.12, R.sub.13 and R.sub.14 are each independently hydrogen or an optionally-substituted alkyl, aryl or aralkyl group;R.sub.3 is an optionally-substituted aryl group; andR.sub.4 is hydrogen or an optionally-substituted alkyl, aryl or aralkyl group.

Abstract: Pressure- or heat-sensitive record material utilizes a chromogenic material of the formula (I) (Ia or Ib): ##STR1## in which: one of A.sub.1 and A.sub.3 is an optionally-substituted carbocyclic aryl group and the other of A.sub.1 and A.sub.3 is either an optionally-substituted aryl group which is the same as or different from A.sub.1, or an optionally-substituted nitrogen-containing aromatic heterocyclic group, with the proviso that if both A.sub.1 and A.sub.3 are aryl groups, then at least one of A.sub.1 and A.sub.3 has a substituted amino or -N-heterocyclic substituent in the 4- position (relative to the bond joining A.sub.1 or A.sub.3 respectively to the remainder of the molecule);A.sub.2 is hydrogen or an optionally-substituted aryl, alkyl or aralkyl group; andA.sub.4 is hydrogen or an optionally-substituted alkyl, aryl or aralkyl group.

Abstract: A security paper authenticating system comprises, in combination, a security paper carrying both starch and an iodate salt, typically potassium iodate, and an authenticating composition comprising an acidic solution of an iodide salt, typically potassium iodide, the system being such that on applying the authenticating composition to authentic security paper, as by a pen, brush or stamp pad, iodine is generated and a characteristic starch-iodine coloration is produced. The authenticating composition is preferably aqueous or part-aqueous, and is preferably made acidic by means of a weak organic acid such as tartaric acid. The authenticating composition preferably also contains an antioxidant such as ascorbic acid. The invention extends to the paper and the authenticating composition individually.

Abstract: A process for preparing a permeable sheet of glass fibre reinforced thermoplastic material for moulding into a shaped product which includes binding thereto a surface layer of particulate material which is compatible with or inert to the thermoplastic content of said sheet and which acts to improve the surface finish thereof when the sheet is subsequently heated and chill moulded under pressure.

Abstract: An extracted and isolated soy protein polymer is used for prevention of premature coloration in CFB pressure-sensitive copying paper which is neutral- or alkaline-sized with an alkyl ketene dimer and which utilizes an acid clay color developer composition. The soy protein polymer may be carried by the base paper, e.g. as a result of size press or size bath application, or may be present in the microcapsule coating.

Abstract: A subcoat of plastic pigment particles and a binder is provided beneath the microcapsule coating of otherwise conventional pressure-sensitive copying paper of the CB or CFB type. The plastic pigment particles may be hollow or solid. Inorganic pigment particles are preferably also present in the subcoat. The binder may be a mixture of styrene/butadiene latex and polyvinyl alcohol. The subcoat typically has a coatweight of 3 to 6 g m.sup.-2. The presence of the plastic pigment subcoat improves copying intensity, or permits a desired given copy intensity to be obtained at a lower microcapsule coatweight.

Abstract: A chromogenic compound for use in pressure- or heat-sensitive record material has the general formula (I):R.sub.1 --CH.dbd.CH--CR.sub.3 (OR.sub.4)--CH.dbd.CH--R.sub.2 (I)in which: R.sub.1 and R.sub.2 are the same or different and each is a group of one of the formula (II): ##STR1## in which the benzene ring of the group of formula (IIa) is optionally further substituted, and in which: R.sub.10 and R.sub.11 are each independently hydrogen or an optionally-substituted alkyl, aryl or aralkyl group, or R.sub.10 and R.sub.11 together with the nitrogen atom to which they are attached form an optionally-substituted heterocyclic ring, which may include one or more further hetero atoms; R.sub.12, and R.sub.13 and R.sub.14 are each independently hydrogen or an optionally-substituted alkyl, aryl or aralkyl group; R.sub.3 is an optionally-substituted aryl group; and R.sub.4 is hydrogen or an optionally-substituted alkyl, aryl or aralkyl group.

Abstract: Acid sized carbonless base paper incorporating a sulphate based filler, particularly calcium sulphate, is less base reactive than otherwise similar paper made using conventional clay (kaolin) fillers. Carbonless paper, particularly CB paper, made from such base is less susceptible to undesired discoloration arising from base reactivity.

Abstract: A watermarked paper sheet for use in a xerographic ion deposition or magnetographic printing process, in which the sheet has print receiving and reverse sides, the print receiving side of the sheet having a surface resistivity of between 5.times.10.sup.10 and 5.times.10.sup.12 ohms per square and a Bendsten roughness of not more than 300 milliliters, and the reverse side being formed with a watermark.

Abstract: Pressure-sensitive copying paper of particular suitability for the production of business forms sets by xerographic photocopying processes (including laser printing processes) carries, as loadings within the thickness of the paper:(a) inorganic color developer material; and(b) microcapsules containing a substantially colorless chromogenic material;and is characterized in that it has:(i) a mean Bendsten roughness on its top side up to 880 ml.min.sup.-1 ;(ii) a mean Bendsten porosity of up to about 200 ml.min.sup.-1 ; and(iii) an ex-mill moisture content of not more than about 5.5%, based on the total weight of the paper.The use of paper as defined above minimises jamming and other problems commonly encountered when attempting to produce business forms sets from pressure-sensitive copying papers by xerographic photocopying processes.

Abstract: Thermally sensitive record material (thermal paper) using 2,2-bis(4-hydroxyphenyl)-4-methylpentane as co-reactant with conventional electron donating chromogenic compounds and a combination of a long chain fatty acid amide was melting between 80.degree. and 140.degree. C. and a sensitizer melting between 60.degree. and 120.degree. C. and selected from diaryl ethers, acetoacetic anilides, phenyl hydroxynaphthoates, aryl or aralkyl substituted biphenyls and diaryl carbonates have high thermal sensitivity and good background whiteness.

Abstract: In a papermachine coating or size press section a rope system is provided for feeding the web through the machine either initially or after a break. In an abrasive environment continuously running ropes can lead to excessive wear on the ropes. In the present invention a rope system for a papermachine has means independent of a papermachine for driving the ropes which may be stationary when not in use. The driving capacity of the rope system is such that during simultaneous operation of both the rope system and the coating or size press section, the rope system can operate at speeds greater than the section.