CN112608693A

CN112608693A - Release paper and preparation method thereof

Info

Publication number: CN112608693A
Application number: CN202011586638.XA
Authority: CN
Inventors: 李冰洁; 李剑平
Original assignee: JIANGSU NAISI DIGITAL TECHNOLOGY Inc Ltd
Current assignee: JIANGSU NAISI DIGITAL TECHNOLOGY Inc Ltd
Priority date: 2020-12-29
Filing date: 2020-12-29
Publication date: 2021-04-06

Abstract

The invention discloses release paper and a preparation method thereof, and the release paper comprises a base material and a release agent layer, wherein the release agent layer is coated on the front surface of the base material and is prepared from water-soluble resin, powder filler, a release agent, a leveling agent, a defoaming agent, a crosslinking agent, a thickening agent, a pH regulator and deionized water are added into the release agent layer, the coating weight of a wet base of the coating is 30-50 g/square meter, and the thickness of a dry base of the coating is 0.010-0.025 mm; the base material adopts various paper bases such as coated paper, light coated paper, glassine paper, kraft paper and the like. And adjusting the viscosity of the release agent layer coating to be more than 2000 cPa, directly coating the release agent layer coating on the front surface of the base material by using a comma scraper, drying, and performing calendaring treatment to obtain the release paper. The release paper has high glossiness which can reach more than 90-95%, the release force reaches 30-50 g, the product structure is simplified, the production process is simple and convenient, and the release paper has good waterproofness and degradability, is safe and environment-friendly.

Description

Release paper and preparation method thereof

Technical Field

The invention relates to paper, in particular to release paper and a preparation method thereof.

Background

The release paper is an anti-sticking paper which can prevent the adhesive layer from being stuck and can also protect the adhesive layer from being polluted, and is widely used on self-adhesive materials such as electronic product adhesive tapes, automobile foam adhesive tapes, printing, food, medical labels and the like. Silicone release papers and non-silicone release papers are classified by release agent, the most common type of release paper being silicone oil paper using a silicone release agent as a release layer, which is used with tacky materials, especially adhesive tapes.

The classification of the release paper can be classified according to the presence of plastic release paper and the absence of plastic release paper. In the plastic release paper, because the release agent has a certain permeability, if there is no certain barrier, the release agent can penetrate into the paper to cause the problems of poor curing and the like, so plastic coating treatment (commonly called as film coating) needs to be carried out on the paper. The production is mainly divided into two procedures: the first PE film coating (plastic coating), wherein the film coating machine uniformly coats the hot-melt PE on the surface of the paper to form a PE plastic layer; and secondly, coating silicon, wherein the organic silicon oil has the incompatible physical property, namely coating the organic silicon on the surfaces of coiled other materials by adopting a coating machine to form a silicon oil layer, namely obtaining the laminating silicon oil paper. The non-plastic release paper mainly comprises glassine, CCK and other release paper subjected to special treatment.

The advantages and disadvantages of the plastic release paper and the non-plastic release paper are obvious:

1. plastic release paper is available:

(1) the advantages are that: the plastic layer has a certain barrier function, so that the release agent is prevented from permeating into the paper; the plastic layer provides certain dimensional stability of release paper, and prevents drying, rewetting deformation and the like in the gluing process.

(2) The disadvantages are as follows: the production process is complex, two procedures are needed, and the production cost is high; the recyclability of the paper-plastic composite is poor, and the plastic layer is not degradable, so that the environmental pollution is caused; the specification is more than 100 g.

2. No-plastic release paper:

(1) the advantages are that: the production process is simple, only one silicon coating process is needed, and the production cost is low; the paper can be recovered and naturally degraded, and does not cause environmental pollution.

(2) The disadvantages are as follows: the release agent can permeate into the paper without a barrier layer; the size stability is poor, the problem of serious deformation caused by drying and rewetting can occur in the gluing process, and the adjustment process is needed; domestic glassine paper can only produce a fixed quantity of 60-80 g.

In the manufacturing process of the self-adhesive material, before the release paper is compounded with the surface material, the processes of silicon coating and gluing are firstly carried out. Drying in an oven to evaporate a large amount of water in the release paper. If the composite material is compounded with the surface material, the release paper can absorb moisture in the air in the storage and printing processing processes of the finished material, so that the fibers expand, the release paper extends, the surface material is concave, and the whole material deforms. Therefore, the manufactured adhesive sticker material cannot be used, and the quality of the adhesive sticker material can be ensured only by a rewetting process.

The amount of rewet has a direct effect on the flatness of the material:

(1) the amount of rewet is small. As described above, the base paper after final compounding is expected to absorb a large amount of moisture, and the surface paper is recessed, so that normal printing cannot be performed

(2) The amount of rewet is large. Too much moisture regain of the release paper causes the paper fibers to expand, which causes the base paper to stretch. During the storage and printing process of the compounded material, the moisture in the base paper gradually volatilizes to reach the humidity balance with the air. Thus, the base paper is slowly shortened. Shortening of the release paper can cause the entire material to bulge upward, also making printing and processing impossible.

Therefore, the production process of gluing and rewetting has extremely high requirements on the quality of the release paper. Not only is it required to have high strength, but also strict requirements are made in heat resistance, bulk, moisture, and the like. Therefore, the common release paper can be made of the laminating paper, and the general release paper has good flatness and good toughness and meets the basic requirements of the release paper.

The release paper should satisfy: the glue can be stuck, but the two are easy to separate; does not react with or pollute the glue system; when the temperature and the humidity of the environment change, the length and the width of the release paper are kept unchanged so as to prevent the prepreg from wrinkling caused by wrinkling of the release paper; should have sufficient compactness to prevent the penetration of the glue of the transfer gum; the elongation of the release paper after being pulled is consistent with that of the fiber, so that deformation or distortion caused by asynchronous drawing in the gum applying process is prevented; the thickness and the mass per unit area of the device are not easy to be accurately controlled.

In conclusion, the development of a novel release paper material which has the advantages of both plastic release paper and non-plastic release paper has become a research hotspot in the industry of non-setting adhesive materials.

Disclosure of Invention

The invention aims to solve the technical problems and provides release paper and a preparation method thereof.

In order to achieve the technical purpose and achieve the technical requirements, the invention adopts the technical scheme that: a release paper comprises a substrate, and is characterized in that: the front surface of the base material is coated with a release agent layer; the coating has a wet base coating weight of 30-50 g/square meter and a dry base thickness of 0.010-0.025 mm.

Preferably: the release agent layer comprises the following components in parts by weight: 5-15 parts of water-soluble resin, 15-35 parts of powder filler, 20-40 parts of release agent, 0.2-0.8 part of flatting agent, 0.2-1 part of defoaming agent, 1-4 parts of cross-linking agent, 5-10 parts of thickening agent, 0.1-0.6 part of pH regulator and 15-35 parts of deionized water.

Preferably: the base material can adopt coated paper, light coated paper, glassine paper and kraft paper, and the gram weight specification is 60g, 80g, 100g and 120 g.

Preferably: the water-soluble resin is one or a combination of more of water-soluble alkyd resin, amino resin, water-soluble acrylic resin, melamine formaldehyde resin, polyvinyl alcohol, poly N-vinyl pyrrolidone and alkyd resin;

the powder filler is one or a combination of more of titanium dioxide, superfine aluminum silicate, barium sulfate, superfine calcium carbonate, kaolin and talcum powder;

the release agent is one or a combination of more of water-soluble silicone oil, emulsified paraffin, polytetrafluoroethylene emulsion, stearic acid emulsion, higher fatty acid calcium, polyethylene wax type release agent and special wax emulsion;

the leveling agent is one or a combination of more of polyurethane modified polyether association type leveling agent, polyhydroxy alkyl ether, modified composite silicone/special polyether and alkynediol;

the defoaming agent is one or a combination of more of amide type, metal soaps, silicon dioxide, mineral oil, modified silicone and polyether;

the cross-linking agent is one or a combination of more of water-based isocyanate, aziridine, carbodiimide, an organic silicon cross-linking agent and a silane coupling agent;

the thickening agent is one or a combination of more of fatty alcohol-polyoxyethylene ether sulfate, distearate, amine oxide thickening agent, cellulose thickening agent, polyurethane modified polyether associative thickening agent, polyurethane modified polyether thickening agent, modified polyacrylate and acrylic acid alkali thickening agent;

the pH regulator is one or a combination of more of ammonia water, diethanolamine, triethanolamine, sodium bicarbonate and sodium hydroxide.

A preparation method of release paper is characterized by comprising the following steps: the method comprises the following steps:

(1) accurately weighing the raw and auxiliary materials according to the formula;

(2) grinding the dispersion liquid: fully stirring and dispersing the powder filler and 8-12 parts of deionized water into slurry, grinding the slurry for more than 4 hours by using a disc type sand mill, testing the particle size by using a laser particle size distribution instrument, and filtering by using a 300-mesh filter screen to obtain dispersion for later use;

(3) dissolution of water-soluble resin: adding the rest deionized water into a stainless steel pull cylinder with a jacket for heating, slowly adding a pH regulator, reducing the pH value to 7-9, starting a dispersion stirrer, adding water-soluble resin, stirring at a low speed of 200 rpm, and soaking for 1-2 hours for dissolving; heating the jacket until the water temperature reaches 75-85 ℃, gradually increasing the stirring speed to 1500 rpm, and fully stirring for 1-2 hours to completely dissolve the water-soluble resin;

(4) maintaining the rotating speed of 1500 rpm, adding the dispersion liquid in the step (2) into a stainless steel pulling cylinder, and stirring at high speed for more than 30 minutes;

(5) gradually adding a release agent, a flatting agent, a defoaming agent and a crosslinking agent, and stirring at a medium speed of 600 revolutions per minute for more than 20 minutes;

(6) finally, increasing the stirring speed to 1500 rpm, slowly adding a thickening agent, adjusting the viscosity of the water-based paint to be more than 2000 cPa, and filtering by a 300-mesh filter screen to obtain a release agent layer paint;

(7) the release agent layer coating passes through online ultrasonic defoaming equipment, is circularly fed to a material tank through a gear pump, is coated on the release agent layer on the front surface of the base material by using a comma scraper, and is conveyed to a bridge type drying oven for drying through a guide roller, wherein the temperature of the drying oven is set to be 120-140 ℃, and the crosslinking and curing of the coating are ensured;

then, performing calendaring treatment by using a super calender to obtain the release paper; the pressure of the super calender is set to be 100-200 kgf/cm 2.

The release paper prepared by the invention has high glossiness which can reach more than 90-95%, the release force reaches 30-50 g, the product structure is simplified, the production process is simple and convenient, and particularly, the release paper has better waterproofness and degradability, is safe and environment-friendly, meets the market demand, fills the market blank, and has good economic and social benefits when being popularized and applied.

Drawings

FIG. 1 is a schematic structural view of the present invention;

in the figure: 1. a release agent layer; 2. a substrate.

Detailed Description

The present invention is further described below.

A release paper and a preparation method thereof are characterized in that: the release paper comprises a base material and a release agent layer, wherein the release agent layer is coated on the front surface of the base material and is prepared from water-soluble resin, powder filler, a release agent, a leveling agent, a defoaming agent, a crosslinking agent, a thickening agent, a pH regulator and deionized water are added, the wet base coating weight of the coating is 30-50 g per square meter, and the dry base thickness of the coating is 0.010-0.025 mm; the base material adopts various base papers such as coated paper, light coated paper, glassine paper, kraft paper and the like, and the gram weight specification comprises four specifications of 60g, 80g, 100g and 120 g. The viscosity of the release agent layer coating is adjusted to be more than 2000 cPa, a comma scraper is used for directly coating the front surface of the base material, the base material is dried by a bridge type oven, and then a supercalender is used for calendaring, so that the release paper disclosed by the invention is obtained. The release paper has high glossiness which can reach more than 90-95%, the release force reaches 30-50 g, the product structure is simplified, the production process is simple and convenient, and the release paper has good waterproofness and degradability, is safe and environment-friendly.

In the concrete implementation, the invention makes deep consideration on the product structure, the coating thickness, the substrate thickness, the release layer coating formula and the preparation process.

A substrate

The plastic release paper has higher general gram weight because the paper surface has paper wool and fiber, so the laminating film must reach a certain amount to ensure no penetration point, and silicone oil cannot penetrate into the paper and cannot be badly peeled. Generally, more than 80 grams of paper base is used, the film spraying amount is 16-20 grams per square meter, the single-side film spraying amount reaches 96-100 grams, and the double-side film spraying amount exceeds 110 grams. The die cutting factory prefers to use the fixed quantity of more than 100g, for example, 120g and 140 g, the domestic glassine with the fixed quantity of 60-80 g can not be used, and only the plastic release paper is used, thereby causing higher cost and material waste.

The base material of the invention can adopt various base papers such as coated paper, light coated paper, glassine paper, kraft paper and the like, and the gram weight specification comprises four specifications of 60g, 80g, 100g and 120 g. After the release agent layer is coated, the total gram weight reaches 70-145 g, and the common specifications of release paper of adhesive tapes and die cutting factories are basically covered.

Second, description of product structure and release agent layer

Consider that: the plastic layer with the plastic release paper has a certain barrier effect, so that the release agent is prevented from permeating into the paper; the plastic layer provides certain dimensional stability for the release paper, and prevents drying, rewetting deformation and the like in the gluing process; however, the production process is complex, two procedures are required, and the production cost is high. The production process of the plastic-free release paper is simple, only one silicon coating process is needed, and the production cost is low; however, the release agent can penetrate into the paper without a barrier layer; the size stability glue layer can have the serious deformation problem due to drying and rewetting in the gluing process, and the adjustment process is needed.

Therefore, the release agent layer is coated on the front surface of the base material and is prepared from water-soluble resin, wherein powder filler, a release agent, a leveling agent, a defoaming agent, a cross-linking agent, a thickening agent, a pH regulator and deionized water are added. The viscosity of the release agent layer coating is adjusted to be more than 2000 cPa, a comma scraper is used for directly coating the release agent layer coating on the front surface of the base material, the release agent layer coating is dried by a bridge type oven, and then the supercalender is used for calendaring.

Firstly, the viscosity of the coating of the release agent layer is adjusted to be more than 2000 cPa, and the release agent cannot penetrate into the paper in the coating process to cause the problems of poor curing and the like. And the release agent layer is prepared from water-soluble resin, and can form a layer of film after being dried on the surface of the base material, so that certain dimensional stability of the release paper can be provided, and drying, rewetting deformation and the like in the gluing process can be prevented. Compared with the plastic release paper, the process saves one process and reduces the production cost.

And secondly, after the release agent layer is dried by a bridge type oven to form a film, a super calender is used for calendaring, so that the release agent layer is more compact and has better dimensional stability.

Thirdly, because the surface of the paper has paper wool and fibers, the coating needs to reach a certain amount to ensure that no penetration point exists, the silicone oil cannot penetrate into the paper, and poor stripping is avoided. The wet base coating weight of the release agent layer coating is 30-50 g/square meter or so, and the dry base thickness of the coating is 0.010-0.025 mm.

Third, water soluble resin

The conventional mold release mainly takes an organic silicon mold release as a main material, and takes an organic fluorine mold release and other non-silicon mold release as auxiliary materials. The usage rate of solvent type silicone oil in the organic silicon release agent accounts for more than 60% of the market of the whole release paper, wherein the solvent mainly comprises solvent gasoline, methylbenzene, butanone and the like, has strong volatility, is flammable and explosive, and has certain toxicity. In the production process, the environmental protection and fire fighting pressure of enterprises are increased, and certain harm can be caused to the bodies of staff. Therefore, the invention uses water-soluble resin as a main body to prepare the release agent layer coating from the perspective of the water-based environment-friendly coating.

The water-soluble resin is one or a combination of a plurality of water-soluble alkyd resin, amino resin, water-soluble acrylic resin, polyvinyl alcohol, poly N-vinyl pyrrolidone and alkyd resin.

Synthetic polymer latex has good water resistance, but natural coating adhesives such as starch, polyvinyl alcohol, protein, sodium alginate and the like and surface sizing agents have poor water resistance, and a cross-linking agent is required to enhance the wet friction resistance of coated paper, and particularly for offset printing, the wet friction resistance is an important index.

The amino resin is a general term for resins obtained by condensation-polymerizing amino group-containing compounds such as urea, melamine or benzoguanamine with formaldehyde and alcohols, and important resins include urea-formaldehyde resin (UF), melamine-formaldehyde resin (MF), polyamidopolyamine epichlorohydrin (PAE), and the like. Urea-formaldehyde resins are nonionic and therefore do not adsorb well to negatively charged paper fibers, and therefore, when used as wet strength agents for paper, cannot be added directly to the pulp, but only by impregnation (e.g., surface coating).

The urea-formaldehyde resin is used as a paper wet strength agent, and chemical crosslinking among the resins forms a net structure to wrap around fibers, and the chemical crosslinking can not be hydrolyzed, so that the water absorption expansion of hemicellulose in the paper is prevented, the strength reduction of the paper under a wetting condition is reduced, and the wetting expansion of the fibers is restrained like a net, so that the wet strength of the paper is maintained. Amino resins have a high functionality and a low tendency to self-polymerize and are very effective crosslinkers, especially when crosslinked with polyester resins, providing good flexibility and formability of the paint film. The urea-formaldehyde resin modified by PVA and melamine is adopted, and the experiment shows that: the addition of PVA can reduce the content of free aldehyde in the adhesive and improve the storage stability of the adhesive. The addition of melamine can greatly improve the water resistance of the adhesive and reduce the content of free aldehyde. Melamine formaldehyde resin (MF) is a wet strength agent and a water repellent agent widely used in the Chinese paper industry. Can be directly added into pulp and can obtain good wet strength after thermal drying. Polyamide polyamine epichlorohydrin (PAE) is a cationic polymer which has been used as a moisturizing enhancer for many years, and is limited as a water repellent because of its low solids content and the need for curing under alkaline conditions. Because the PAE resin contains amino, epoxy and azetidinium cations, and the fiber surface has reactive groups such as hydroxyl, aldehyde and carboxyl. The PAE resin molecules and the fiber surface reaction groups generate crosslinking action.

An ethylene acrylic acid copolymer (EAA) is a polymer with thermoplasticity and extremely high adhesiveness, and due to the existence of carboxyl groups and the action of hydrogen bonds, the crystallization of the polymer is inhibited, the linearity of a main chain is destroyed, so that the transparency and the toughness of the EAA are improved, and the melting point and the softening point are reduced. EAA with high AA content and high MI can be dissolved in hot alkaline solution under appropriate reaction conditions to formulate aqueous adhesives for use in apparel garments and the like. The EAA and the starch-based material can be blended to produce the degradable plastic.

Fourthly, release agent

At present, most of the silicone oil is thermosetting silicone oil, and most of the silicone oil is solvent type silicone oil, and the solvent can be volatilized and cured at a certain temperature. Meanwhile, the solvent silicone oil is added with a curing agent and a platinum catalyst, so that the storage stability of the coating is poor, the coating can only be prepared for use at present, and the coating can be cured at normal temperature and discarded after being placed for a long time. The invention adopts the water-based release agent coating, thereby reducing the problems of solvent discharge and normal temperature storage.

The release agent is one or a combination of more of water-soluble silicone oil, emulsified paraffin, polytetrafluoroethylene emulsion, stearic acid emulsion, higher fatty acid calcium, polyethylene wax type release agent and special wax emulsion.

The water soluble silicone oil is also an excellent additive for various coatings, can improve the leveling property of the coatings and enable the coated surfaces to be smooth and bright, and can also be used as a plastic additive, a release agent and the like. The resin has low surface tension, good flexibility and antistatic performance, and good viscosity reduction and leveling performance, is suitable for being added into various resins (polyurethane resin, paint resin, plastic resin and the like), can well improve intermolecular stress of the resins, overcomes the defects of the resins, and obtains new performance.

The emulsified silicone oil has stable chemical property, is non-volatile, is not easy to burn, has no corrosion to metal, and is not easy to gel after being placed in the air for a long time. The emulsified silicone oil also has excellent heat resistance, cold resistance, weather resistance, lubricity, hydrophobicity and low surface tension, is nontoxic and harmless to human bodies, and can be widely used for personal care, food production, fermentation industry and the like.

The polytetrafluoroethylene emulsion has outstanding heat resistance, cold resistance and abrasion resistance, has excellent electrical insulation, is not influenced by temperature and frequency, and has the characteristics of non-adhesion, non-water absorption, non-combustion and the like.

Stearic acid emulsion is emulsion taking stearic acid as main component and is widely used for preparing cosmetics, plastic cold-resistant plasticizer, mold release agent, stabilizer, surfactant, rubber vulcanization accelerator, waterproof agent, polishing agent, metal soap, metal mineral flotation agent, softener, pharmaceuticals and other organic chemicals. In addition, it can be used as solvent for oil-soluble pigment, crayon slip agent, stencil paper polishing agent, and emulsifier for stearin.

The higher fatty acid calcium release agent has excellent lubricating property in the paper coating process and is beneficial to solving the contamination problem in the calendaring process. The lubricant or the release agent is used for offset printing paper and white board paper and is helpful for improving the fluidity of the coating. Dust resistance, stain resistance and paper property of the supercalendering process.

The polyethylene wax type release agent has good demolding effect, and particularly has excellent release effect at high temperature and under high polymers; the dust-proofing agent used in the supercalendering process of the coated gravure paper can exert excellent effect; it also has an effect of improving gloss on the coated paper.

The special wax emulsion has water resistance and shows excellent lubrication, release and re-adhesion.

Fifth, leveling agent

The leveling agent is one or a combination of more of polyurethane modified polyether association type leveling/thickening agents, polyhydroxy alkyl ethers, modified composite silicone/special polyethers and alkynediols.

The polyurethane modified polyether association type leveling/thickening agent has excellent leveling property and thickening property, does not reduce glossiness, has an excellent high-shear viscosity thickening effect, has excellent fluidity and leveling property in a thickening system, is widely applied to various aqueous systems such as emulsion paints and adhesives, improves the viscosity stability and film gloss of aqueous coatings, and reduces the water absorption rate of film forming.

Sixthly, defoaming agent

The defoaming agent is one or a combination of more of amide type, metal soap, hydrophobic silicon dioxide, mineral oil, modified silicone and polyether.

The invention selects the defoamer consisting of mineral oil, polyether, hydrophobic silicon dioxide and other components, has excellent initial defoaming property and continuous defoaming property, and is particularly suitable for the paint which is easy to foam during roller coating. After the release agent is used, residual bubble marks and shrinkage cavities do not exist, the appearance of a coating film is not influenced, and the problem of poor point-shaped and block-shaped non-anti-sticking peeling caused by uneven coating of a release agent layer is solved.

Seventhly, a cross-linking agent

The cross-linking agent is one or a combination of more of blocked water-based isocyanate, aziridine, carbodiimide, an organic silicon cross-linking agent and a silane coupling agent.

The closed water-based isocyanate crosslinking agent can stably coexist with resin containing active groups (hydroxyl, carboxyl, amino, epoxy and the like) for a long time at normal temperature, after a solvent is volatilized, a coating film is subjected to heat treatment, and the latent curing agent releases-NCO groups and reacts with the hydroxyl, carboxyl, amino and other groups on a molecular chain of the film-forming resin to form crosslinking, so that the performances of the film-forming resin such as water resistance, chemical resistance, wear resistance, adhesive force, mechanical and cooking resistance can be obviously improved.

An organosilicon cross-linking agent and a silane coupling agent belong to a novel organosilicon curing agent, and are mainly subjected to cross-linking curing reaction with an organic compound with a hydrophilic group at normal temperature or slightly heated and wet environment, so that the water resistance, solvent resistance, corrosion resistance and high temperature resistance of acrylic acid/polyurethane/epoxy resin are realized; and a series of physical properties such as bonding strength, fastness, hardness, adhesive force and the like are improved.

Eighth, thickening agent

The thickening agent is one or a combination of more of fatty alcohol-polyoxyethylene ether sulfate, PEG-150 distearate, amine oxide thickening agent, cellulose thickening agent, polyurethane modified polyether associative thickening agent, polyurethane modified polyether thickening agent, modified polyacrylic acid sulfonate and acrylic acid alkali thickening agent.

The polyurethane modified polyether association type leveling/thickening agent and the polyurethane modified polyether thickening agent have excellent leveling property and thickening property, do not reduce glossiness, have excellent high-shear viscosity thickening effect, have excellent fluidity and leveling property in a thickening system, are widely applied to various emulsion paints, adhesives and other aqueous systems, improve the viscosity stability and film gloss of aqueous coatings, and reduce the water absorption rate of film forming.

The acrylic acid alkali thickening thickener has good water resistance, can change the thixotropy of the water-based paint, can improve the viscosity under low shearing force, can endow the water-based paint with thixotropy, and can inhibit the cracking phenomenon of a coating film; can also resist the erosion of mould and bacteria and improve the storage stability of the coating product.

Nine pH regulator

The thickener used in the invention is usually added under stirring at the final stage of paint adjustment, is sensitive to the pH value of the paint, and usually needs to reach pH = 8-10. Meanwhile, part of the water-soluble resin can be dissolved in a hot alkaline solution only under appropriate reaction conditions.

Ten-step calendering process

When the release paper is used for transferring back glue, the glue is coated on the front surface of the release paper in a liquid state, and if the glossiness of a paper surface coating is lower, the glue layer after being coated and dried can present the same low glossiness and low light transmittance; especially, when the release paper is used for film adhesive products or adhesive labels such as transparent BOPP, PET, PVC and the like, the adhesive product or adhesive label of the transparent surface material is semitransparent after the lower layer of the release paper is removed, and cannot be used for pasting transparent plastic bottles, glass bottles or high-gloss surface materials, so that the use appearance is greatly influenced. Therefore, it is necessary to consider increasing the glossiness of the release agent layer. After the surface of the paper is coated, the coated layer is dried, and if the smoothness and the glossiness of the coated layer need to be improved again, the coated layer can be calendered by a super calender. The glossiness of the coating on the surface of the paper is about 65-85%, and the glossiness can reach more than 90-95% after calendaring.

A calender is a device for improving the gloss of paper, and calendering is one of glazing processes. The operating mode of a calender is usually a continuous roll press. After being dried by a bridge type oven, the paper is conveyed to a calendering belt between a hot-pressing roller and a pressing roller, and the coating is attached to the surface of the calendering belt to be calendered under the action of temperature and pressure. The calendered coating is gradually cooled to form a bright surface layer. The calender belt is a specially treated stainless steel annular steel belt. The hot-press roller is internally provided with a plurality of groups of far-infrared heating sources to provide heat required in calendering. The pressure of the pressure roller mostly adopts an electric hydraulic pressure regulating system, and the requirement on the pressure in calendering can be accurately met. The calendering speed can be controlled by a speed-regulating driving motor or a slip motor.

Example 1

(1) accurately weighing 7 parts of melamine formaldehyde resin, 1 part of polyvinyl alcohol, 18 parts of titanium dioxide, 35 parts of emulsified silicone oil, 5 parts of higher fatty acid calcium, 0.4 part of polyurethane modified polyether, 0.5 part of mineral oil, polyether and hydrophobic silicon dioxide mixed defoaming agent, 2 parts of water-based isocyanate, 6 parts of acrylic acid alkali thickening thickener, 0.2 part of triethanolamine and 30 parts of deionized water according to a formula;

(2) grinding the dispersion liquid: fully stirring 18 parts of titanium dioxide and 9 parts of deionized water, dispersing into slurry, grinding the slurry for 4.5 hours by using a disc type sand mill, testing the particle size by using a laser particle size distribution instrument, and filtering by using a 300-mesh filter screen to obtain dispersion for later use;

(3) dissolution of water-soluble resin: adding the rest deionized water into a stainless steel pulling cylinder with a jacket for heating, slowly adding 0.2 part of triethanolamine, reducing the pH value to 8, starting a dispersion stirrer, gradually adding 1 part of polyvinyl alcohol and 7 parts of melamine formaldehyde resin, stirring at a low speed of 200 r/min, and soaking for 1.5 hours for dissolving; heating the jacket until the water temperature reaches 78 ℃, gradually increasing the stirring speed to 1500 rpm, and fully stirring for 1 hour to completely dissolve the water-soluble resin;

(4) maintaining the rotating speed of 1500 rpm, adding the dispersion liquid in the step (2) into a stainless steel pulling cylinder, and stirring at a high speed for 35 minutes;

(5) gradually adding 35 parts of emulsified silicone oil, 5 parts of higher fatty acid calcium, 0.4 part of polyurethane modified polyether, 0.5 part of mineral oil, polyether and hydrophobic silicon dioxide mixed defoaming agent and 2 parts of water-based isocyanate, and stirring at a medium speed of 600 revolutions per minute for 20 minutes;

(6) finally, increasing the stirring speed to 1500 rpm, slowly adding 6 parts of acrylic acid alkali thickening thickener, adjusting the viscosity of the water-based paint to 2200 cPa, and filtering by a 300-mesh filter screen to obtain a release agent layer paint;

(7) the release agent layer coating passes through online ultrasonic defoaming equipment, is circularly fed to a material tank by a gear pump, is coated on the release agent layer on the front surface of the base material by using a comma scraper, and is conveyed to a bridge type drying oven for drying by a guide roller, wherein the temperature of the drying oven is set to be 130 ℃, and the crosslinking and curing of the coating are ensured;

(8) then, performing calendaring treatment by using a super calender to obtain the release paper; the pressure of the supercalender was set to 150kgf/cm 2.

Example 2

(1) accurately weighing raw and auxiliary materials according to a formula, 6 parts of water-soluble acrylic resin (EAA), 15 parts of titanium dioxide, 5 parts of talcum powder, 30 parts of emulsified silicone oil, 10 parts of special wax emulsion, 0.4 part of polyurethane modified polyether, 0.3 part of mineral oil, polyether and hydrophobic silicon dioxide mixed defoaming agent, 1.5 parts of silane coupling agent, 8 parts of modified polyacrylic sulfonate thickener, 0.3 part of ammonia water and 20 parts of deionized water;

(2) grinding the dispersion liquid: fully stirring and dispersing 15 parts of titanium dioxide, 5 parts of talcum powder and 10 parts of deionized water into slurry, grinding the slurry for 4.5 hours by using a disc type sand mill, testing the particle size by using a laser particle size distribution instrument, and filtering by using a 300-mesh filter screen to obtain dispersion for later use;

(3) dissolution of water-soluble resin: adding the rest deionized water into a stainless steel pulling cylinder with jacket heating, adding ammonia water, adjusting pH to about 9, starting a dispersion mixer, adding water-soluble acrylic resin (EAA), stirring at low speed of 200 r/min, soaking for 1.5 hr, and dissolving; heating the jacket until the water temperature reaches 80 ℃, gradually increasing the stirring speed to 1500 rpm, and fully stirring for 1 hour to completely dissolve the water-soluble resin;

(5) gradually adding 30 parts of emulsified silicone oil, 10 parts of special wax emulsion, 0.4 part of polyurethane modified polyether, 0.3 part of mineral oil, polyether and silicon dioxide mixed defoaming agent and 1.5 parts of silane coupling agent, and stirring at a medium speed of 600 revolutions per minute for 30 minutes;

(6) finally, increasing the stirring speed to 1500 rpm, slowly adding 8 parts of modified polyacrylic acid sulfonate thickener, adjusting the viscosity of the water-based paint to 2100 cPa, and filtering by a 300-mesh filter screen to obtain a release agent layer paint;

(7) the release agent layer coating passes through online ultrasonic defoaming equipment, is circularly fed to a material tank by a gear pump, is coated on the release agent layer on the front surface of the base material by using a comma scraper, and is conveyed to a bridge type drying oven for drying by a guide roller, wherein the temperature of the drying oven is set to be 120 ℃, and the crosslinking and curing of the coating are ensured;

(8) then, performing calendaring treatment by using a super calender to obtain the release paper; the pressure of the supercalender was set to 180kgf/cm 2.

Example 3

(1) accurately weighing raw and auxiliary materials according to a formula, 6 parts of water-soluble alkyd resin, 4 parts of amino resin, 18 parts of superfine aluminum silicate, 12 parts of barium sulfate, 20 parts of emulsified silicone oil, 10 parts of polytetrafluoroethylene emulsion, 0.6 part of polyhydroxyalkyl ether, 0.5 part of mineral oil, polyether and hydrophobic silicon dioxide mixed defoaming agent, 2 parts of aziridine, 4 parts of amine oxide, 4 parts of fatty alcohol-polyoxyethylene ether sulfate, 0.3 part of sodium bicarbonate and 30 parts of deionized water;

(2) grinding the dispersion liquid: fully stirring 18 parts of superfine aluminum silicate, 12 parts of barium sulfate and 11 parts of deionized water, dispersing into slurry, grinding the slurry for 4.5 hours by using a disc type sand mill, testing the particle size by using a laser particle size distribution instrument, and filtering by using a 300-mesh filter screen to obtain dispersion for later use;

(3) dissolution of water-soluble resin: dissolution of water-soluble resin: adding the rest deionized water into a stainless steel pulling cylinder with a jacket for heating, slowly adding 0.3 part of sodium bicarbonate, reducing the pH value to 7-8, gradually adding 6 parts of water-soluble alkyd resin and 4 parts of amino resin, stirring at low speed of 200 r/min, and soaking for 1.5 hours for dissolving; heating the jacket until the water temperature reaches 82 ℃, gradually increasing the stirring speed to 1500 rpm, and fully stirring for 1 hour to completely dissolve the water-soluble resin;

(5) gradually adding 20 parts of emulsified silicone oil, 10 parts of polytetrafluoroethylene emulsion, 0.6 part of polyhydroxy alkyl ether, 0.5 part of mineral oil, polyether and hydrophobic silicon dioxide mixed defoaming agent and 2 parts of aziridine, and stirring at the medium speed of 600 revolutions per minute for 35 minutes;

(6) finally, increasing the stirring speed to 1500 rpm, slowly adding 4 parts of amine oxide and 5 parts of fatty alcohol-polyoxyethylene ether sulfate, adjusting the viscosity of the water-based paint to be more than 2300 cPa, and filtering by a 300-mesh filter screen to obtain a release agent layer paint;

(7) the release agent layer coating passes through online ultrasonic defoaming equipment, is circularly fed to a material tank by a gear pump, is coated on the release agent layer on the front surface of the base material by using a comma scraper, and is conveyed to a bridge type drying oven for drying by a guide roller, wherein the temperature of the drying oven is set to be 140 ℃, and the crosslinking and curing of the coating are ensured;

(8) then, performing calendaring treatment by using a super calender to obtain the release paper; the pressure of the supercalender was set to 120kgf/cm 2.

The above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, but not intended to limit the scope of the present invention, and all equivalent technical solutions also belong to the scope of the present invention, and the scope of the present invention should be defined by the claims.

Claims

1. A release paper, comprising a substrate (2), characterized in that: the front surface of the base material (2) is coated with a release agent layer (1); the coating has a wet base coating weight of 30-50 g/square meter and a dry base thickness of 0.010-0.025 mm.

2. The release paper according to claim 1, wherein: the release agent layer (1) comprises the following components in parts by weight: 5-15 parts of water-soluble resin, 15-35 parts of powder filler, 20-40 parts of release agent, 0.2-0.8 part of flatting agent, 0.2-1 part of defoaming agent, 1-4 parts of cross-linking agent, 5-10 parts of thickening agent, 0.1-0.6 part of pH regulator and 15-35 parts of deionized water.

3. The release paper according to claim 1, wherein: the base material can adopt coated paper, light coated paper, glassine paper and kraft paper, and the gram weight specification is 60g, 80g, 100g and 120 g.

4. The release paper according to claim 2, wherein: the water-soluble resin is one or a combination of more of water-soluble alkyd resin, amino resin, water-soluble acrylic resin, melamine formaldehyde resin, polyvinyl alcohol, poly N-vinyl pyrrolidone and alkyd resin;

5. A preparation method of release paper is characterized by comprising the following steps: the method comprises the following steps:

accurately weighing the raw and auxiliary materials according to the formula;

grinding the dispersion liquid: fully stirring and dispersing the powder filler and 8-12 parts of deionized water into slurry, grinding the slurry for more than 4 hours by using a disc type sand mill, testing the particle size by using a laser particle size distribution instrument, and filtering by using a 300-mesh filter screen to obtain dispersion for later use;

dissolution of water-soluble resin: adding the rest deionized water into a stainless steel pull cylinder with a jacket for heating, slowly adding a pH regulator, reducing the pH value to 7-9, starting a dispersion stirrer, adding water-soluble resin, stirring at a low speed of 200 rpm, and soaking for 1-2 hours for dissolving; heating the jacket until the water temperature reaches 75-85 ℃, gradually increasing the stirring speed to 1500 rpm, and fully stirring for 1-2 hours to completely dissolve the water-soluble resin;

maintaining the rotating speed of 1500 rpm, adding the dispersion liquid in the step (2) into a stainless steel pulling cylinder, and stirring at high speed for more than 30 minutes;

gradually adding a release agent, a flatting agent, a defoaming agent and a crosslinking agent, and stirring at a medium speed of 600 revolutions per minute for more than 20 minutes;

finally, increasing the stirring speed to 1500 rpm, slowly adding a thickening agent, adjusting the viscosity of the water-based paint to be more than 2000 cPa, and filtering by a 300-mesh filter screen to obtain a release agent layer paint;

the release agent layer coating passes through online ultrasonic defoaming equipment, is circularly fed to a material tank through a gear pump, is coated on the release agent layer on the front surface of the base material by using a comma scraper, and is conveyed to a bridge type drying oven for drying through a guide roller, wherein the temperature of the drying oven is set to be 120-140 ℃, and the crosslinking and curing of the coating are ensured;