CN114874700B - Environment-friendly release agent and preparation method thereof - Google Patents

Abstract

The application discloses an environment-friendly release agent and a preparation method thereof, wherein the environment-friendly release agent is prepared by mixing a component A, a component B and deionized water in a weight ratio of 20: vinyl silicone oil: 20 to 50 percent; hydrogen-containing silicone oil: 0.5 to 10 percent; aqueous polyvinyl alcohol solution: 5 to 20 percent; inhibitor (B): 0.5 to 1.0 percent; a stabilizer: 3 to 8 percent; emulsifier: 0.1 to 3 percent; an anchoring agent: 5 to 10 percent; deionized water: 30 to 50 percent; the stabilizing agent comprises a composition of silica sol and water-soluble chitosan in a weight ratio of (3-5) to 1, and the pH value of the silica sol is 8-10; the component B comprises the following raw materials in percentage by weight: vinyl silicone oil: 20 to 50 percent; catalyst: 1000-2520 ppm; aqueous polyvinyl alcohol solution: 10 to 20 percent; emulsifier: 0.3 to 3 percent; deionized water: 30 to 60 percent. The emulsion type release agent prepared by the method has high storage stability and is not easy to coalesce and settle.

Description

Environment-friendly release agent and preparation method thereof

Technical Field

The application relates to the field of organic silicon release agents, in particular to an environment-friendly release agent and a preparation method thereof.

Background

The organic silicon release agent is a film-forming coating, can form a release film when coated on the surface of a substrate, and has the advantages of protecting an adhesive from pollution, facilitating production and processing, facilitating storage and transportation, maintaining the product physical properties of the adhesive and the like. Therefore, the release agent is widely applied to the adhesive field of labels, adhesive tapes, advertising materials, medical supplies, sanitary supplies, food processing and packaging, express envelopes, electronic die stickers and the like.

The solvent-type organic silicon release agent is divided into an organic solvent type and an emulsion type. Among them, the organic solvent type release agent usually adopts toluene, gasoline and the like as diluents, so that potential safety hazards and environmental pollution problems are easily caused in the production and use processes. The emulsion type release agent has relatively high safety and environmental protection, and accords with the current social development trend.

However, the emulsion type release agent also has a problem of product stability, which is liable to cause coalescence and precipitation during storage.

Disclosure of Invention

In order to improve the stability of a release agent emulsion and ensure the use performance of a product, the application provides an environment-friendly release agent and a preparation method thereof.

In a first aspect, the application provides an environment-friendly release agent, which is obtained by mixing a component A, a component B and deionized water in a weight ratio of 20:

vinyl silicone oil: 20 to 50 percent;

hydrogen-containing silicone oil: 0.5 to 10 percent;

aqueous polyvinyl alcohol solution: 5 to 20 percent;

inhibitor (B): 0.5 to 1.0 percent;

a stabilizer: 3 to 8 percent;

emulsifier: 0.1 to 3 percent;

anchoring agent: 5 to 10 percent;

deionized water: 30 to 50 percent;

the stabilizing agent comprises a composition of silica sol and water-soluble chitosan in a weight ratio of (3-5): 1, and the pH value of the silica sol is 8-10;

the component B comprises the following raw materials in percentage by weight:

vinyl silicone oil: 20 to 50 percent;

catalyst: 1000-5000 ppm;

aqueous polyvinyl alcohol solution: 10 to 20 percent;

emulsifier: 0.3 to 3 percent;

deionized water: 30 to 60 percent.

By adopting the technical scheme, the silica sol can form a three-dimensional network structure in a release agent emulsion system through the action of hydrogen bonds, so that mutual coalescence of emulsion particles is limited, and the effect of improving the stability of the system is achieved. However, the silica sol itself is easy to damage the three-dimensional network structure under the action of external force during long-term storage, and coagulation occurs to destroy the stability of the emulsion system.

In order to overcome the problems, the application adjusts the silica sol system to be alkaline and adds water-soluble chitosan, and hydroxyl on the surface of the silica particles can be reacted with OH ^- The reaction makes the surface of the silica particles negatively charged, and the probability of the silica particles being agglomerated is reduced by electrostatic repulsion. The molecular chain of the water-soluble chitosan contains more amino groups, and the amino groups are electropositive in the aqueous solution, so that the aqueous chitosan can be adsorbed on the surface of silicon dioxide particles through electrostatic action on one hand, and chemical bonding is formed through the hydrogen bond action between the amino groups and hydroxyl groups, so that the chitosan molecules generate steric hindrance on the surface of the silicon dioxide particles, the coagulation probability of silica sol is reduced, and the stability of an emulsion system is guaranteed.

In the present application, the aqueous solution of polyvinyl alcohol is a water-soluble polymer obtained by hydrolysis of polyvinyl acetate; the concentration is 4-6%, the viscosity at 25 deg.C is 4-80 cps, the alcoholysis degree is 80-90%, and the molecular weight is 8000-2000000.

Preferably, the anchoring agent is a silane oligomer.

In the technical scheme, the silane oligomer, namely the oligomer obtained by hydrolytic polymerization of the silane coupling agent, has active groups with higher density in molecular chains, can form firmer connection with the base material, and improves the adhesive force of the release agent.

Preferably, the silane oligomer is prepared by the following method:

s1-1, adding a silane coupling agent into methanol, uniformly mixing to obtain a premix, heating the premix to 50-70 ℃, then dripping a mixture of methanol and water, adding an organic acid, adjusting the pH value to 3-5, and hydrolyzing the silane coupling agent to obtain a hydrolysate; wherein the silane coupling agent comprises an aminosilane coupling agent;

s1-2, heating the hydrolysate to 90-100 ℃, and polymerizing for 2-3 h to obtain a prepolymer; and then, continuously heating the prepolymer to 120-130 ℃, carrying out secondary polymerization for 1-2 h, and cooling to room temperature to obtain the silane oligomer.

By adopting the technical scheme, after the silane coupling agent is hydrolyzed, siloxane groups in a molecular chain of the silane coupling agent are converted into silanol groups, and the silanol groups are subjected to condensation reaction to form the oligomer. Compared with common silane coupling agents, the silane coupling agent has stronger connecting performance and enhances the anchoring property of the silane coupling agent on the surface of a base material, especially a nonpolar high polymer material.

In addition, the application preferably adopts an aminosilane coupling agent as a raw material, and utilizes the reactivity of amino groups to further improve the anchoring property of the release agent on the surface of the substrate.

Preferably, the silane coupling agent in the step S1-1 further comprises gamma-methacryloxypropyltrimethoxysilane, and the molar ratio of the aminosilane coupling agent to the gamma-methacryloxypropyltrimethoxysilane is (6-10) to (1-2).

By adopting the technical scheme, the gamma-methacryloxypropyltrimethoxysilane is introduced into a molecular chain of the oligomer, so that the surface energy of the release agent emulsion can be reduced, the spreading of the emulsion on the surface of the base material is promoted, and the curing speed of the release agent emulsion is improved.

Preferably, in the step S1-1, an alkyl acrylate and an initiator are added together with a silane coupling agent, and the molar ratio of the gamma-methacryloxypropyltrimethoxysilane to the alkyl acrylate is (1-2) to (3-8).

Compared with a solvent-free type or organic solvent type release agent, in the process of coating polar substrates such as paper, moisture in the emulsion type release agent is easy to permeate into the substrates, so that the paper substrates have poor phenomena such as folds, warps and the like after being dried. Therefore, the application adds the alkyl acrylate monomer and the initiator, and under the action of the initiator, the methacryloxy group with the unsaturated bond and the alkyl acrylate are copolymerized, and then the alkyl acrylate with hydrophobicity is introduced into the molecular chain of the oligomer.

In conclusion, the oligomer contains a large amount of amino groups, can be quickly bonded with active groups on the surface of a base material, and plays a certain anti-permeability role by utilizing a hydrophobic chain of the oligomer, thereby being beneficial to reducing the bad phenomenon of the paper base material.

Preferably, the aminosilane coupling agent is one or more of gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane, N- (beta-aminoethyl) -gamma-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldiethoxysilane, N- (piperazinylethyl) -3-aminopropylmethyldimethoxysilane, 3-divinyltriaminopropylmethyldimethoxysilane and 3-divinyltriaminopropyltrimethoxysilane.

The technical scheme comprises the monoamino and polyamino silane coupling agents, and the oligomer of the coupling agent has a higher anchoring effect on polar or non-polar base materials, so that the adhesive force of the release agent is effectively ensured.

Preferably, the raw materials of the emulsion type release agent also comprise 0.5-2% of glutaraldehyde.

By adopting the technical scheme, two aldehyde groups contained in the glutaraldehyde can respectively react with amino groups in the chitosan and the silane oligomer in the curing process after the release agent is coated, so that the glutaraldehyde has the function of a cross-linking agent, and the silane oligomer and the chitosan are promoted to be cross-linked to form a film, so that the permeation of water to the inside of paper is reduced. In addition, the silica sol can be quickly crosslinked into a film through hydroxyl groups in the drying process, so that the water resistance of the paper base material is improved, and the adverse phenomena of wrinkles, warping and the like after drying are reduced.

Preferably, the emulsifier is polyether modified silicone oil.

By adopting the technical scheme, the polyether modified silicone oil can obviously reduce the surface energy of the release agent emulsion and improve the spreadability of the release agent emulsion on the base material.

In a second aspect, the application provides a method for preparing an environment-friendly release agent, comprising the following steps:

mixing vinyl silicone oil, hydrogen-containing silicone oil, polyvinyl alcohol aqueous solution, stabilizer, emulsifier, inhibitor and anchoring agent, adding deionized water, and homogenizing after phase inversion is completed to obtain a component A;

mixing vinyl silicone oil, a catalyst, a polyvinyl alcohol aqueous solution and an emulsifier, adding deionized water, and homogenizing after phase inversion is finished to obtain a component B;

and mixing the component A, the component B and deionized water according to the mass ratio of 20.

By adopting the technical scheme, the prepared emulsion type release agent has higher storage stability and is not easy to generate coagulation. The surface of the base material has better spreadability, which is beneficial to improving the film forming speed; meanwhile, the penetration of water in the emulsion into the interior of a base material such as paper can be reduced, and the adverse phenomena of wrinkling, warping and the like of the base material after coating and drying are reduced.

In summary, the present application has the following beneficial effects:

1. in the application, the composition of silica sol and water-soluble chitosan is used as a stabilizer, so that the stability of the emulsion type release agent is effectively improved, and the probability of coalescence and sedimentation in the storage process is reduced.

2. In the application, silane oligomer obtained by hydrolytic polymerization of the aminosilane coupling agent is adopted, so that the anchorage property of the release agent emulsion on the surface of the base material is remarkably improved, and the adhesive force of the release agent emulsion after coating is ensured.

3. According to the preparation method, gamma-methacryloxypropyltrimethoxysilane and alkyl acrylate are added as polymerization raw materials, so that the obtained silane oligomer can effectively inhibit the permeation of aqueous solution to paper base materials, and the adverse phenomena of wrinkling, warping and the like of the paper base materials after the release agent is dried are reduced. Meanwhile, the surface energy of the release agent emulsion can be effectively reduced, and the spreadability of the release agent emulsion is improved. Wrinkles, warpage and the like.

4. According to the application, glutaraldehyde is adopted, and silane oligomer and silica sol are promoted to be crosslinked in the coating and drying process, so that a film layer with a certain hydrophobic and anti-permeability effect is formed on the surface of the substrate, and the probability of undesirable phenomena such as wrinkles and warping of the substrate after the release agent emulsion is coated is remarkably reduced.

Detailed Description

Preparation example of stabilizer

Preparation example 1-1, a stabilizer, was prepared as follows:

adding 1 kg of water-soluble chitosan into 4 kg of silica sol (10 wt%), stirring for 20min, adding ammonia water to adjust the pH value of the solution to 9, and continuing stirring for 20min to obtain the stabilizer. Wherein the water-soluble chitosan is chitosan with deacetylation of 50%.

Preparation examples 1-2, a stabilizer, were prepared as follows:

adding 1 kg of water-soluble chitosan into 5 kg of silica sol (10 wt%), stirring for 20min, adding ammonia water to adjust the pH value of the solution to 8, and continuing stirring for 30min to obtain the stabilizer. Wherein the water-soluble chitosan is chitosan with 60% deacetylation.

Preparation examples 1 to 3, a stabilizer, were different from preparation example 1 in that water-soluble chitosan was not added to the raw materials, and silica sol was used as the stabilizer.

Preparation examples 1 to 4, a stabilizer, were different from preparation example 1 in that silica sol was not added to the raw materials, and water-soluble chitosan was used as the stabilizer.

Preparation example of anchoring agent

Preparation example 2-1, an anchoring agent, was prepared according to the following steps:

s1-1, 1435g (8 mol) of gamma-aminopropyltrimethoxysilane, 249g (1 mol) of gamma-methacryloxypropyltrimethoxysilane, 336g (4 mol) of methacrylate monomer and ammonium persulfate are added into 400g of methanol, stirred for 10min and heated to 65 ℃; then, a mixture of 300g of methanol and 500g of water is dripped in, acetic acid is added simultaneously, the pH value is adjusted to 4, and the mixture is stirred and reacts for 1 hour to obtain hydrolysate.

S1-2, heating the hydrolysate to 100 ℃, and carrying out polymerization reaction for 2 hours to obtain a prepolymer; and then, continuously heating the prepolymer to 120 ℃, continuously polymerizing for 1.5h, and cooling to room temperature to obtain the silane oligomer.

Preparation example 2-2, an anchoring agent, was prepared according to the following steps:

s1-1, adding 1587g (6 mol) of N- (beta-aminoethyl) -gamma-aminopropyltriethoxysilane, 498g (2 mol) of gamma-methacryloxypropyltrimethoxysilane, 672g (8 mol) of methacrylate monomer and ammonium persulfate into 500g of methanol, stirring for 20min, uniformly mixing, and heating to 60 ℃; then, a mixture of 500g of methanol and 800g of water is dripped in, acetic acid is added simultaneously, the pH value is adjusted to 4, and the mixture is stirred and reacts for 1 hour to obtain hydrolysate.

S1-2, heating the hydrolysate to 100 ℃, and carrying out polymerization reaction for 2 hours to obtain a prepolymer; and then, continuously heating the prepolymer to 120 ℃, continuously polymerizing for 1.5h, and cooling to room temperature to obtain the silane oligomer.

Preparation examples 2 to 3, an anchoring agent, was prepared according to the following steps:

s1-1, adding 1794g (10 mol) of gamma-aminopropyltrimethoxysilane, 249g (1 mol) of gamma-methacryloxypropyltrimethoxysilane and 252g (3 mol) of methacrylate monomer into 500g of methanol, stirring for 20min, heating to 65 ℃ after uniform mixing, adding sodium persulfate, and continuing stirring and mixing for 1h; then, a mixture of 400g of methanol and 300g of water is dropped, acetic acid is added, and the pH value is adjusted to 5, so that the silane coupling agent is fully hydrolyzed to obtain a hydrolysate.

S1-2, heating the hydrolysate to 100 ℃, and carrying out polymerization reaction for 2 hours to obtain a prepolymer; and then, continuously heating the prepolymer to 120 ℃, continuously polymerizing for 1.5h, and cooling to room temperature to obtain the silane oligomer.

Preparation 2-4, an anchoring agent, differs from preparation 2-1 in that, in step S1-1, an equal amount of tridecyl acrylate is used instead of methacrylate.

Preparation 2-5, an anchoring agent, was different from preparation 2-1 in that the same amount of aminosilane coupling was used instead of gamma-methacryloxypropyltrimethoxysilane in step S1-1.

Preparation examples 2-6, an anchoring agent, were different from preparation example 2-1 in that the same amount of aminosilane coupling was used instead of the methacrylate monomer in step S1-1.

Preparation 2-7, an anchoring agent, was different from preparation 2-1 in that in step S1-1, gamma-methacryloxypropyltrimethoxysilane was used in an equal amount in place of gamma-aminopropyltrimethoxysilane.

Examples

Example 1, an environment-friendly release agent was prepared as follows:

40wt% of vinyl-terminated vinyl silicone oil with the vinyl mass fraction of 1.2%, 3wt% of hydrogen-containing silicone oil with the hydrogen base mass fraction of 0.6%, 8wt% of polyvinyl alcohol aqueous solution with the viscosity of 40cps and the alcoholysis degree of 88% and the molecular weight of 100000-120000, 5wt% of stabilizer prepared in preparation example 1-1, 0.5wt% of polyether modified silicone oil (trademark 7123), 0.5wt% of 3-methyl-1-butyn-3-ol, 6.0wt% of anchoring agent prepared in preparation example 2-1, and 1.0wt% of glutaraldehyde are added into a high-speed dispersion machine to be uniformly dispersed, 37wt% of deionized water is slowly added, and the mixture is transferred into a high-pressure homogenizer for 30MPa and 3 times after phase inversion is finished to obtain a component A;

adding 35wt% of vinyl-terminated vinyl silicone oil with the viscosity of 500cps and the vinyl mass fraction of 1.2%, 3000ppm of a capsule type platinum catalyst, 15wt% of polyvinyl alcohol aqueous solution with the viscosity of 40cps and the alcoholysis degree of 88%, and the molecular weight of 120000, and 0.5wt% of polyether modified silicone oil (the trademark 7123) into a high-speed dispersion machine at the same time for uniform dispersion, then slowly adding 49.5wt% of deionized water, and transferring into a high-pressure homogenizer for 3 times at 30MPa after finishing phase inversion to obtain a component B;

and mixing the component A, the component B and deionized water according to a mass ratio of 20.

The emulsion type release agent is taken to be coated on 50u of transparent PET film in a scraping way, the coating weight is 0.3-0.4 g/inch, and the coating is obtained after curing at 90 ℃.

Example 2, an environment-friendly release agent was prepared as follows:

23.5wt% of vinyl-terminated vinyl silicone oil with 1.2% of vinyl mass fraction, 0.9wt% of hydrogen-containing silicone oil with 1.0% of hydrogen base mass fraction, 18wt% of polyvinyl alcohol aqueous solution with viscosity of 40cps, alcoholysis degree of 88%, molecular weight of 100000-120000, 9wt% of stabilizer prepared in preparation example 1-2, 3wt% of polyether modified silicone oil (trademark 7123), 0.5wt% of 3-methyl-1-butyne-3-ol, 5.0wt% of anchoring agent prepared in preparation example 2-2 and 0.5wt% of glutaraldehyde are added into a high-speed dispersion machine to be uniformly dispersed, then 33.5wt% of deionized water is slowly added, and the mixture is transferred into a high-pressure homogenizer for 30MPa and 3 times after phase inversion is finished to obtain component A;

50wt% of vinyl-terminated vinyl silicone oil with the mass fraction of 1.2% of vinyl, 1000ppm of capsule type platinum catalyst, 10wt% of polyvinyl alcohol aqueous solution with the viscosity of 40cps and the alcoholysis degree of 88% and the molecular weight of 120000 and 1.0wt% of polyether modified silicone oil (trademark 7123) are added into a high-speed dispersion machine to be uniformly dispersed, then 39wt% of deionized water is slowly added, and the mixture is transferred into a high-pressure homogenizer for 3 times under 30MPa after the phase inversion is finished, so that a component B is obtained;

and mixing the component A, the component B and deionized water according to a mass ratio of 20.

The emulsion type release agent is taken to be coated on 50u of transparent PET film by scraping, the coating weight is 0.3-0.4 g/inch, and the coating is obtained after curing at 90 ℃.

Example 3, an environment-friendly release agent was prepared as follows:

45wt% of vinyl-terminated vinyl silicone oil with 1.2% of vinyl mass fraction, 6wt% of hydrogen-containing silicone oil with 1.0% of hydrogen base mass fraction, 5wt% of polyvinyl alcohol aqueous solution with viscosity of 40cps and alcoholysis degree of 88%, molecular weight of 100000-120000, 5wt% of stabilizer prepared in preparation example 1-1, 1.0wt% of polyether modified silicone oil (trademark 7123), 1.0wt% of 3-methyl-1-butyn-3-ol, 5.0wt% of anchoring agent prepared in preparation example 2-3 and 2.0wt% of glutaraldehyde are simultaneously added into a high-speed dispersion machine for uniform dispersion, then 30wt% of deionized water is slowly added, and the mixture is transferred into a high-pressure homogenizer for 3 times under 30MPa after phase inversion is completed to obtain a component A;

25wt% of vinyl-terminated vinyl silicone oil with 1.2% of vinyl mass fraction, 5000ppm of capsule platinum catalyst, 20wt% of polyvinyl alcohol aqueous solution with viscosity of 40cps and alcoholysis degree of 88% and molecular weight of 120000, and 3.0wt% of polyether modified silicone oil (No. 7123) are added into a high-speed dispersion machine to be uniformly dispersed, then 52wt% of deionized water is slowly added, and the mixture is transferred into a high-pressure homogenizer for 3 times under 30MPa after phase inversion is finished to obtain a component B;

and mixing the component A, the component B and deionized water according to a mass ratio of 20.

The emulsion type release agent is taken to be coated on 50u of transparent PET film in a scraping way, the coating weight is 0.3-0.4 g/inch, and the coating is obtained after curing at 90 ℃.

Example 4, an environment-friendly release agent, was different from example 1 in that the anchoring agent prepared in preparation example 2-1 was replaced with the anchoring agent prepared in preparation example 2-4 in the same amount in the starting material of component A.

Example 5, an environmental friendly release agent, was different from example 1 in that the anchor agent obtained in preparation example 2-1 was replaced with the anchor agent obtained in preparation example 2-5 in the same amount in the raw materials of component A.

Example 6, an environment-friendly release agent, was different from example 1 in that the anchoring agent prepared in preparation example 2-1 was replaced with the anchoring agent prepared in preparation example 2-6 in the same amount in the starting material of component A.

Example 7, an environment-friendly release agent, was different from example 1 in that the anchor agent obtained in preparation example 2-1 was replaced with the anchor agent obtained in preparation example 2-7 in the same amount in the raw materials of component A.

Example 8, an environment-friendly release agent, was different from example 1 in that the same amount of gamma-aminopropyltrimethoxysilane was used in the raw material of the component A instead of the anchoring agent prepared in preparation example 2-1.

Example 9, an environment-friendly release agent, was different from example 1 in that in the raw materials of the A-component, an equal amount of vinyltriethoxysilane was used instead of the anchoring agent prepared in preparation example 2-1.

Example 10, an environment-friendly release agent, is different from example 1 in that glutaraldehyde is not added to the raw materials of component a.

Comparative example

Comparative example 1, an environment-friendly release agent, was different from example 1 in that the stabilizers prepared in preparation examples 1 to 1 were replaced with the same amount of the stabilizer prepared in preparation examples 1 to 3 in the starting material of component A.

Comparative example 2, an environment-friendly release agent, was different from example 1 in that the same amount of the stabilizer prepared in preparation examples 1 to 4 was used instead of the stabilizer prepared in preparation examples 1 to 1 in the raw materials of component A.

Comparative example 3, an environment-friendly release agent, was different from example 2 in that an equal amount of waterborne alkyd resin (trade name YG-AK 337) was used instead of the stabilizer prepared in preparation example 1-1 in the raw materials of component A.

Performance test

Test 1: and (4) testing the stability of the emulsion type release agent.

Filling the emulsion type release agent sample into an ampoule bottle (25 g/bottle) at room temperature, sealing by using an alcohol blast lamp, and storing in a constant-temperature oven (54 cm 2 ℃) for 14 days to obtain the layering condition and the water precipitation rate; the water separation rate was accurate to 0.5%, and the test results are shown in table 1.

Test 2: emulsion release agent test 2ml of emulsion release agent was dropped on the surface of the PET substrate, and its wet spreading range was visually observed and characterized by the maximum diameter of the wet range (mm), and the test results are shown in table 1.

Test 3: anchoring test of emulsion type Release agent

The adhesion of the coatings obtained in examples 1 to 10 and comparative examples 1 to 3 described above was tested using the cross-hatch test (cross-hatch distance 2 mm) according to the provisions of GB/T9286-1998. The test results are from 0 to 5 grades, and the lower the grade number, the higher the adhesion and the better the anchorage, and the test results are shown in table 1.

Test 4: emulsion type release agent permeability test

The emulsion type release agent is taken to be coated on 50u of transparent base paper by a scraping way, the coating weight is 0.3-0.4 g/inch, and the coating is obtained after curing at 90 ℃. Observing the wrinkling and warping conditions of the coated base paper, and classifying the wrinkling and warping conditions into four grades of no wrinkling and warping, slight wrinkling and warping, obvious wrinkling and warping and serious wrinkling and warping according to the severity; the test results are shown in table 1.

TABLE 1 test results

And (3) analyzing test results:

(1) It can be seen from the combination of examples 1 to 10 and comparative examples 1 to 3 and table 1 that the storage stability of the emulsion type release agent is effectively improved by using the composition of silica sol and water-soluble chitosan with the pH of 8 to 10 as the stabilizer, and the best stabilization effect cannot be achieved by the absence of any one of the raw materials. The reason may be that the silica sol can form a three-dimensional network structure in a release agent emulsion system through the action of hydrogen bonds, so that mutual coalescence of emulsion particles is limited, and the effect of improving the stability of the system is achieved.

Meanwhile, under the alkaline condition, hydroxyl on the surface of the silica particles in the silica sol can be reacted with OH ^- And reacting to ensure that the surface of the silica sol is negatively charged, and reducing the probability of coalescence and sedimentation of the silica sol through electrostatic repulsion. The molecular chain of the water-soluble chitosan contains more amino groups, and the water-soluble chitosan is electropositive in aqueous solution, so that the chitosan in the aqueous solution can be adsorbed on the surface of the silicon dioxide particles through electrostatic action on one hand, and forms chemical bonding through the hydrogen bond action between amino and hydroxyl, so that the chitosan molecules generate steric hindrance on the surface of the silicon dioxide particles, the coagulation probability of silica sol is reduced, and the stability of an emulsion system is ensured.

(2) By combining examples 1 to 3 and examples 4 to 7 with table 1, it can be seen that the anchoring force (adhesion) of the emulsion release agent on the surface of the substrate is significantly improved by using the silane oligomer prepared by using the aminosilane coupling agent as the anchoring agent. The reason for this may be that the silane oligomer, i.e., the oligomer obtained by hydrolytic polymerization of the silane coupling agent, has a higher density of active groups in its molecular chain, and can form a firmer linking action with the substrate, thereby improving the coating strength of the release agent. Particularly, the amino group has stronger activity and can form a hydrogen bond with the active group on the surface of the base material, thereby enhancing the anchoring force.

Furthermore, gamma-methacryloxypropyltrimethoxysilane, alkyl acrylate and an initiator are added into the raw materials of the silane oligomer, so that the permeation of water into the base material in the emulsion is effectively reduced, and the wetting and spreading performance of the emulsion is improved. The reason for this may be that after gamma-methacryloxypropyltrimethoxysilane is introduced into the molecular chain of the oligomer, the surface energy of the emulsion can be reduced, and the wetting and spreading of the emulsion on the surface of the substrate can be promoted. Under the action of an initiator, the gamma-methacryloxypropyltrimethoxysilane and unsaturated bonds in the alkyl acrylate can be copolymerized, so that the alkyl acrylate with hydrophobicity is introduced into oligomer molecules. So that the oligomer attached to the substrate has a hydrophobic barrier property, thereby reducing the permeation of water into the interior of the substrate in the emulsion, and further reducing the fraction defective of the substrate after coating and drying.

(3) It can be seen from the combination of examples 1 to 3 and examples 8 to 9 and from table 1 that the anchoring force of the release agent cannot be effectively improved by using the conventional silane coupling agent, as compared with using the silane oligomer.

(4) By combining examples 1 to 3 and example 10 with table 1, it can be seen that the glutaraldehyde crosslinking agent is added to the raw material of the release agent, so that the permeation of water into the base material such as paper in the emulsion is remarkably reduced, and the probability of undesirable phenomena such as wrinkling and warping of the paper after coating and drying is reduced. The reason for this may be that two aldehyde groups contained in glutaraldehyde can react with amino groups in chitosan and silane oligomer to act as a cross-linking agent, which promotes the silane oligomer and chitosan to cross-link into a film, thereby playing a role in water-proof isolation and reducing the permeation of water into the paper. In addition, the silica sol can be crosslinked to form a film by hydroxyl groups on the surface during drying, thereby further improving the water resistance of the paper substrate.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims (4)

1. The environment-friendly release agent is characterized by being prepared by mixing a component A, a component B and deionized water in a weight ratio of 20:

vinyl silicone oil: 20 to 50 percent;

hydrogen-containing silicone oil: 0.5 to 10 percent;

aqueous polyvinyl alcohol solution: 5 to 20 percent;

inhibitor (B): 0.5 to 1.0 percent;

a stabilizer: 3 to 8 percent;

emulsifier: 0.1 to 3 percent;

anchoring agent: 5 to 10 percent;

glutaraldehyde: 0.5 to 2 percent;

deionized water: 30 to 50 percent;

the stabilizing agent comprises a composition of silica sol and water-soluble chitosan in a weight ratio of (3-5): 1, and the pH value of the silica sol is 8-10;

the component B comprises the following raw materials in percentage by weight:

vinyl silicone oil: 20 to 50 percent;

catalyst: 1000-5000 ppm;

aqueous polyvinyl alcohol solution: 10 to 20 percent;

emulsifier: 0.3 to 3 percent;

deionized water: 30 to 60 percent.

The anchoring agent is silane oligomer and is prepared according to the following method:

s1-1, adding a silane coupling agent, alkyl acrylate and an initiator into methanol, uniformly mixing to obtain a premix, heating the premix to 50-70 ℃, then dripping a mixture of methanol and water, adding an organic acid, adjusting the pH value to 3-5, and hydrolyzing the silane coupling agent to obtain a hydrolysate; wherein the silane coupling agent comprises aminosilane coupling agent and gamma-methacryloxypropyl trimethoxy silane, and the molar ratio of the aminosilane coupling agent to the gamma-methacryloxypropyl trimethoxy silane to the alkyl acrylate is (6-10) to (1-2) to (3-8);

s1-2, heating the hydrolysate to 90-100 ℃, and polymerizing for 2-3 h to obtain a prepolymer; and then, continuously heating the prepolymer to 120-130 ℃, carrying out secondary polymerization for 1-2 h, and cooling to room temperature to obtain the silane oligomer.

2. The environment-friendly release agent as claimed in claim 1, wherein the aminosilane coupling agent is one or more selected from gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane, N- (beta-aminoethyl) -gamma-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldiethoxysilane, N- (piperazinylethyl) -3-aminopropylmethyldimethoxysilane, 3-divinyltriaminopropylmethyldimethoxysilane and 3-divinyltriaminopropyltrimethoxysilane.

3. The environment-friendly release agent as claimed in claim 1, wherein the emulsifier is polyether modified silicone oil.

4. The method for preparing the environment-friendly release agent according to any one of claims 1 to 3, characterized by comprising the following steps:

mixing vinyl silicone oil, hydrogen-containing silicone oil, polyvinyl alcohol aqueous solution, stabilizer, glutaraldehyde, inhibitor and anchoring agent, adding deionized water, and homogenizing after phase inversion is finished to obtain a component A;

mixing vinyl silicone oil, a catalyst, a polyvinyl alcohol aqueous solution and an emulsifier, adding deionized water, and homogenizing after phase inversion is finished to obtain a component B;

and mixing the component A, the component B and deionized water according to the mass ratio of 20.