A kind of porous release paper and preparation method thereof

Abstract

The invention discloses a porous release paper, which comprises a release paper base paper, a silicone oil layer and an adhesive layer; the adhesive layer is located on the lower surface of the release paper base paper; the silicone oil layer is two layers, which are respectively located on the upper surface of the release paper base paper and the lower surface of the adhesive layer. The porous release paper is provided with micropores, the pore diameter of the micropores is 1 to 2 mm; the pore spacing of the micropores is 2 to 4 mm. The porous release paper prepared by adding composite titanium dioxide in the present invention has good water resistance, oil resistance, light resistance, anti-rolling and anti-bulb effect in a humid environment, is suitable for promotion in the field of release paper, and has broad development prospects.

Description

Technical Field

[0001] The invention relates to the field of release paper, and in particular to a porous release paper and a preparation method thereof. Background Art

[0002] Release paper, also known as isolation paper, anti-sticking paper, and silicone oil paper, is a kind of anti-sticking paper that prevents the adhesion of prepregs and protects the prepregs from contamination. It is made by coating an anti-sticking substance on the base paper. The base paper is generally oil-proof paper, and the anti-sticking substance is generally silicone oil. With the continuous advancement of science and technology, the application of release paper is becoming more and more extensive, such as in the packaging fields of food, chemical industry, electronics, and medical treatment, especially in the food packaging and processing fields such as food liner, steaming, microwave, and freezing. However, if oil-proof paper is used alone to package food, the food is easy to stick to the oil-proof paper. Therefore, it is necessary to coat the oil-proof paper with anti-sticking substances such as silicone oil. Silicone oil is commonly used to coat the surface of food packaging paper to form an anti-sticking layer because of its non-toxic, tasteless, and non-volatile characteristics. Since silicone oil has good high and low temperature resistance, oxidation resistance, good insulation, and no corrosion to metal, this type of release paper is particularly suitable for use as a packaging liner for food processing such as steaming, microwave, and freezing. However, with the increasingly diversified demand for food packaging, the functional requirements for release paper are getting higher and higher. In some special cooking productions, excellent water-proof and oil-proof isolation properties and high temperature resistance are required. However, air permeability has always been a problem in the use of release paper; especially in the use of occasions with more water vapor, a large amount of water vapor penetrates into the release paper, and because the release paper system has good water insolubility, the water vapor will gather in the middle of the release paper interlayer and cannot escape, forming convex bubbles, thereby reducing the strength, water resistance and surface smoothness of the paper, which greatly reduces the performance and service life of the release paper.

[0003] Therefore, there is an urgent need for a release paper that can effectively cope with situations where a large amount of water vapor is likely to be generated. Summary of the invention

[0004] In order to solve the above problems, the first aspect of the present invention provides a porous release paper, the structure of which includes a release paper base paper, a silicone oil layer and an adhesive layer; the adhesive layer is located on the lower surface of the release paper base paper; the silicone oil layer is two layers, respectively located on the upper surface of the release paper base paper and the lower surface of the adhesive layer.

[0005] As a preferred solution, micropores are provided on the porous release paper.

[0006] As a preferred solution, the diameter of the micropores is 1 to 2 mm; the spacing between the micropores is 2 to 4 mm.

[0007] As a preferred solution, the silicone oil layer is formed by spraying silicone oil on the surface of the release paper base paper; the coating amount of the silicone oil is 1.3-1.5 g / m2 .

[0008] As a preferred solution, the viscosity of the silicone oil is 200-240 CPS.

[0009] As a preferred solution, the silicone oil comprises solvent-free silicone, amino silicone oil and modified titanium dioxide.

[0010] As a preferred solution, the weight ratio of the solvent-free silicone, amino silicone oil and modified titanium dioxide is 80-90:5-9:2-5.

[0011] As a preferred solution, the adhesive layer is made by coating glue on the lower surface of the release paper base paper; the glue is PVA glue.

[0012] As a preferred solution, the dry weight of the PVA glue is 0.8-1.0 sgm; the solid content of the PVA glue is 2-5%; and the viscosity of the PVA glue is 4.0-4.5 CPS.

[0013] The second aspect of the present invention provides a method for preparing the above-mentioned porous release paper, which comprises the following steps: (1) coating an adhesive layer on the lower surface of the release paper base paper and drying it; (2) spraying a silicone oil layer on the upper surface of the release paper base paper and the lower surface of the adhesive layer, and drying it; (3) punching holes on the dried release paper.

[0014] Beneficial effects:

[0015] 1. In the present invention, modified titanium dioxide with a particle size of 400 to 6000 nm is added to the silicone oil layer on the surface of the release paper, thereby effectively preventing the anti-yellowing ability of the silicone oil layer of the release paper under light, enhancing the density and strength of the silicone oil layer on the surface of the release paper, and further enhancing the water resistance of the release paper.

[0016] 2. In the present invention, a reasonable process layout and coating sequence are adopted, and a PVA glue layer is coated under the release paper base paper to effectively prevent the release paper from curling inwards and effectively improve the mechanical strength of the release paper.

[0017] 3. In the present invention, the air permeability of the release paper is greatly enhanced by perforating the release paper and reasonably controlling the micropore diameter and the spacing between the micropores. The accumulation of water vapor inside the interlayer of the release paper due to the addition of titanium dioxide in the silicone oil layer and the adhesive layer in the release paper is prevented, so that the water vapor can quickly pass through the release paper, and a small amount of water vapor accumulated in the interlayer can also be discharged through the micropores, thereby ultimately preventing the water vapor from being unable to be discharged inside the release paper and forming convex bubbles, and further ensuring the surface smoothness of the release paper. DETAILED DESCRIPTION

[0018] The content of the present invention can be more easily understood by selecting the following detailed description of the preferred implementation method of the present invention and the embodiments included. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present invention belongs. When there is a conflict, the definition in this specification shall prevail.

[0019] As used herein, the term "prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0020] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0021] When amount, concentration or other value or parameter is expressed as range, preferred range or a series of upper preferred value and lower preferred value limit range, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when disclosing range "1 to 5", described range should be interpreted as including range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the range is intended to include its end value and all integers and fractions within the range.

[0022] Singular forms include plural references unless the context clearly indicates otherwise. "Optional" or "either" means that the subsequently described event or incident may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

[0023] Approximate terms in the specification and claims are used to modify quantities, indicating that the present invention is not limited to the specific quantity, but also includes acceptable and modified parts close to the quantity without causing changes in the relevant basic functions. Accordingly, the use of "about", "approximately", etc. to modify a numerical value means that the present invention is not limited to the exact numerical value. In some examples, the approximate terms may correspond to the accuracy of the instrument for measuring the numerical value. In the specification and claims of this application, range limitations can be combined and / or interchanged, and if not otherwise stated, these ranges include all subranges contained therein.

[0024] In addition, the indefinite articles "a" and "an" before the elements or components of the present invention have no restrictions on the quantity requirements (i.e. the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the number is obviously intended to be in the singular form.

[0025] In order to solve the above problems, the first aspect of the present invention provides a porous release paper, the structure of which includes a release paper base paper, a silicone oil layer and an adhesive layer; the adhesive layer is located on the lower surface of the release paper base paper; the silicone oil layer is two layers, respectively located on the upper surface of the release paper base paper and the lower surface of the adhesive layer.

[0026] In some preferred embodiments, micropores are provided on the porous release paper.

[0027] In some preferred embodiments, the diameter of the micropores is 1 to 2 mm; the spacing between the micropores is 2 to 4 mm.

[0028] In some preferred embodiments, the silicone oil layer is formed by spraying silicone oil on the surface of the release paper base paper; the coating amount of the silicone oil is 1.3-1.5 g / m 2 .

[0029] In some preferred embodiments, the silicone oil has a viscosity of 200 to 240 CPS.

[0030] In some preferred embodiments, the silicone oil comprises solvent-free silicone, amino silicone oil and modified titanium dioxide.

[0031] In some preferred embodiments, the weight ratio of the solvent-free silicone, amino silicone oil and modified titanium dioxide is 80-90:5-9:2-5.

[0032] In some preferred embodiments, the modified titanium dioxide is imidazole skeleton modified titanium dioxide.

[0033] In some preferred embodiments, the modified titanium dioxide is homemade, and the steps include the following: (1) mixing succinic anhydride and DMF, adding (3-aminopropyl)triethoxysilane, and heating and stirring at a water bath temperature of 50-60°C for 3-4 hours; (2) then slowly adding the DMF solution containing titanium dioxide into the mixed solution, and continuously stirring and reacting for 2-3 hours to obtain pretreated titanium dioxide; (3) mixing the pretreated titanium dioxide particles with 2-methylimidazole and zinc nitrate and adding ethanol solvent, and ultrasonically polymerizing them under an ultrasonic device of 600-800W for 2-2.5 hours, washing and drying the obtained product to obtain modified titanium dioxide particles.

[0034] In some preferred embodiments, the weight ratio of titanium dioxide, 2-methylimidazole and zinc nitrate is 1:30-35:20-25.

[0035] In some preferred embodiments, the average particle size of the modified titanium dioxide is 400-600 nm.

[0036] In the present application, modified silicon dioxide is added to the silicone oil coating of the silicone oil layer to effectively improve the light resistance and yellowing resistance of the porous release paper and further improve the water resistance of the release paper.

[0037] The applicant speculates that when release paper is exposed to light for a long time, it is prone to aging and yellowing. Generally, adding titanium dioxide can effectively provide light resistance. However, in the present application, the silicone oil layer mainly contains cured silicone oil. The compatibility of titanium dioxide with silicone oil is poor. When added, it is difficult to effectively disperse it in the coating, and it is easy to cause titanium dioxide to agglomerate. However, the applicant modified the imidazole skeleton of titanium dioxide so that titanium dioxide and the imidazole skeleton are coordinated and combined, and titanium dioxide is changed from a strongly hydrophilic particle with four hydroxyl groups on the surface to a lipophilic composite particle with lower surface energy, which greatly enhances the effective dispersion of particles in the silicone oil layer and avoids aggregation.

[0038] At the same time, the applicant also found that the titanium dioxide and the imidazole skeleton in the modified titanium dioxide particles formed an ingenious heterojunction structure, which greatly increased the number of photogenerated carriers loaded on the particle surface, reduced the hole reset, and the composite particles had an obvious visible light wave absorption section in the visible light region, further improving the light resistance and yellowing resistance of the porous release paper. Further, because the modified titanium dioxide becomes an oleophilic composite particle, the porous release paper can effectively perform waterproofing, avoiding the decrease in the water resistance of the release paper caused by the introduction of a large number of hydrophilic groups due to the addition of ordinary titanium dioxide, and especially when the weight ratio of titanium dioxide, 2-methylimidazole and zinc nitrate is 1:30-35:20-25, the uncoordinated metal ions on the surface of the imidazole skeleton can be completely coordinated with the pretreated surface groups during the reaction process, and the skeleton surface attracts a large amount of titanium dioxide, which not only consumes a large number of hydrophilic groups, but also the rough particle surface further improves the water resistance of the porous release paper.

[0039] In some preferred embodiments, the adhesive layer is made by coating glue on the lower surface of the release paper base paper; the glue is PVA glue.

[0040] In some preferred embodiments, the dry weight of the PVA glue is 0.8-1.0 sgm; the solid content of the PVA glue is 2-5%; and the viscosity of the PVA glue is 4.0-4.5 CPS.

[0041] The second aspect of the present invention provides a method for preparing the above-mentioned porous release paper, which comprises the following steps: (1) coating an adhesive layer on the lower surface of the release paper base paper and drying it; (2) spraying a silicone oil layer on the upper surface of the release paper base paper and the lower surface of the adhesive layer, and drying it; (3) punching holes on the dried release paper.

[0042] In some preferred embodiments, the steps of the preparation method of the porous release paper specifically include the following steps: (1) coating a glue layer on the lower surface of the release paper base paper, and vacuum drying at 60-70° C. for 2-5 minutes; (2) preparing solvent-free silicone, amino silicone oil and modified titanium dioxide according to a proportion to prepare solvent-free silicone oil, and coating the solvent-free silicone oil on the upper and lower surfaces of the release paper by spraying, and then passing through a drying oven at a temperature of 70-100° C. and a drying oven air volume of 7000-9000 m / s. 3 / h drying tunnel for 30 to 45 seconds; (3) punching holes on the dried release paper.

[0043] Example

[0044] The technical solution of the present invention is described in detail below by way of examples, but the protection scope of the present invention is not limited to all the examples described. Unless otherwise specified, the raw materials of the present invention are all commercially available.

[0045] Example 1

[0046] The first aspect of Example 1 provides a porous release paper, the structure of which includes a release paper base paper, a silicone oil layer and an adhesive layer; the adhesive layer is located on the lower surface of the release paper base paper; the silicone oil layer is two layers, respectively located on the upper surface of the release paper base paper and the lower surface of the adhesive layer.

[0047] Embodiment 1 The second aspect provides a method for preparing a porous release paper: (1) coating the lower surface of the release paper base paper with PVA glue to prepare a glue layer, and vacuum drying at 60°C for 5 minutes; (2) preparing solvent-free silicone oil by mixing solvent-free silicone, amino silicone oil and modified titanium dioxide in a weight ratio of 85:5:3, and coating the solvent-free silicone oil on the upper and lower surfaces of the release paper by spraying, and then passing through a drying oven at a temperature of 85°C and a drying oven air volume of 8000m 3 / h drying oven for 35 seconds; (3) performing micro-hole punching on the dried release paper.

[0048] In this embodiment, the release paper base paper is a glassine base paper product sold by Dongguan Hongshun Paper Co., Ltd.

[0049] In this embodiment, the dry weight of the PVA glue is 0.9 sgm; the solid content of the PVA glue is 3%; and the viscosity of the PVA glue is 4.2 CPS.

[0050] In this embodiment, the solvent-free silicone oil prepared by the solvent-free silicone (CAS: 9006-65-9), amino silicone oil and modified titanium dioxide (average particle size 500nm) has a viscosity of 220CPS; the coating amount is 1.4g / m 2 .

[0051] In this embodiment, the diameter of the micropores is 1 mm, and the hole spacing is 2 mm.

[0052] In this embodiment, the modified titanium dioxide is homemade, and the steps include the following steps (in parts by weight): (1) 2 parts of succinic anhydride and 30 parts of DMF are mixed, and 3 parts of (3-aminopropyl) triethoxysilane are added, and heated and stirred at a water bath temperature of 60°C for 3 hours; (2) 20 parts of DMF solution containing 0.5 parts of titanium dioxide are then slowly added to the mixed solution, and the reaction is continued with stirring for 2 hours to obtain pretreated titanium dioxide; (3) 0.5 parts of pretreated titanium dioxide particles are mixed with 16 parts of 2-methylimidazole and 12 parts of zinc nitrate, and 60 parts of ethanol solvent are added, and ultrasonic polymerization is carried out under a 700W ultrasonic device for 2.5 hours. The obtained product is washed and dried to obtain modified titanium dioxide particles.

[0053] In this embodiment: succinic anhydride (CAS: 108-30-5), (3-aminopropyl)triethoxysilane (CAS: 919-30-2), and 2-methylimidazole (CAS: 693-98-1).

[0054] Example 2

[0055] The specific implementation of this embodiment is the same as that of Embodiment 1, except that the weight ratio of solvent-free silicone, amino silicone oil and modified titanium dioxide is 90:9:2.

[0056] Example 3

[0057] The specific implementation of this embodiment is the same as that of Embodiment 1, except that the average particle size of the modified titanium dioxide is 600 nm.

[0058] Comparative Example 1

[0059] The specific implementation of this comparative example is the same as that of Example 1, except that the weight ratio of solvent-free silicone, amino silicone oil and modified titanium dioxide is 90:9:0.5.

[0060] Comparative Example 2

[0061] The specific implementation of this comparative example is the same as that of Example 1, except that the ratio of 2-methylimidazole to zinc nitrate is adjusted so that the fineness of the modified titanium dioxide is 800 nm.

[0062] Comparative Example 3

[0063] The specific implementation of this comparative example is the same as that of Example 1, except that: the amount of 2-methylimidazole is 20 parts and the amount of zinc nitrate is 30 parts.

[0064] Comparative Example 4

[0065] The specific implementation of this comparative example is the same as that of Example 1, except that the pore diameter of the micropores is 0.5 and the pore spacing of the micropores is 5 mm.

[0066] Comparative Example 5

[0067] The specific implementation of this comparative example is the same as that of Example 1, except that ordinary P25 type titanium dioxide is used to replace the modified titanium dioxide.

[0068] Performance Evaluation

[0069] Water resistance and oil resistance: The water resistance and oil resistance of the release paper were tested with reference to GB / 1733-1933 standard. Five samples were tested for each comparative example, and the average value of the measured values ​​was recorded in Table 1. After the water resistance test, the blistering on the surface of the release paper was observed, and the observed situation was recorded in Table 2.

[0070] High temperature resistance: The high temperature resistance of the release paper was tested with reference to GB / 1735-2009 standard. Five samples were tested for each comparative example, and the average value of the measured values ​​was recorded in Table 1.

[0071] Light yellowing resistance:

[0072] Yellowing resistance: The porous release papers prepared in all the embodiments and comparative examples were placed on a test platform with sufficient sunlight for 3 months to observe the yellowing phenomenon on their surfaces.

[0073] Table 1

[0074]

[0075]

[0076] Table 2

[0077]

[0078] It can be seen from Examples 1 to 3, Comparative Examples 1 to 5 and Tables 1 and 2 that the porous release paper and the preparation method thereof provided by the present invention have good water resistance, oil resistance, light resistance, anti-rolling and anti-bulb effect in a humid environment, are suitable for promotion in the field of release paper, and have broad development prospects. Among them, Example 1 obtains the best performance index under the factors of the best raw material weight ratio, micropore diameter and pore spacing.

[0079] Finally, it is pointed out that the above-described embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A porous release paper, characterized in that: The structure includes a release paper base paper, a silicone oil layer and an adhesive layer; the adhesive layer is located on the lower surface of the release paper base paper; the silicone oil layer is two layers, respectively located on the upper surface of the release paper base paper and the lower surface of the adhesive layer; The adhesive layer is formed by coating glue on the lower surface of the release paper base paper; the glue is PVA glue, and the dry weight of the PVA glue is 0.9 gsm; the solid content of the PVA glue is 3%; the viscosity of the PVA glue is 4.2 CPS; The silicone oil layer is made by spraying silicone oil on the surface of the release paper base paper; the silicone oil comprises solvent-free silicone, amino silicone oil and modified titanium dioxide; the weight ratio of the solvent-free silicone, amino silicone oil and modified titanium dioxide is 85:5:3; The viscosity of the silicone oil is 220 CPS; the coating amount is 1.4 g / m 2 ; The modified titanium dioxide is homemade, and the steps include the following steps, calculated in parts by weight: (1) 2 parts of succinic anhydride and 30 parts of DMF are mixed, 3 parts of (3-aminopropyl) triethoxysilane are added, and the mixture is heated and stirred at a water bath temperature of 60°C for 3 hours; (2) 20 parts of DMF solution containing 0.5 parts of titanium dioxide are then slowly added to the mixed solution, and the reaction is continued with stirring for 2 hours to obtain pretreated titanium dioxide; (3) 0.5 parts of pretreated titanium dioxide particles are mixed with 16 parts of 2-methylimidazole and 12 parts of zinc nitrate, and 60 parts of ethanol solvent are added, and the mixture is ultrasonically polymerized under a 700W ultrasonic device for 2.5 hours, and the obtained product is washed and dried to obtain modified titanium dioxide particles; The average particle size of the modified titanium dioxide is 500 nm; The porous release paper is provided with micropores; the pore diameter of the micropores is 1 mm; and the pore spacing of the micropores is 2 mm.

2. A method for preparing the porous release paper according to claim 1, characterized in that: The method comprises the following steps: (1) coating an adhesive layer on the lower surface of the release paper base paper and drying the same; (2) spraying a silicone oil layer on the upper surface of the release paper base paper and the lower surface of the adhesive layer and drying the same; and (3) punching holes on the dried release paper.

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