Grafted polyolefin material capable of preventing precipitation and assisting in crosslinking, preparation method therefor and use thereof

Abstract

The present disclosure relates to the field of polymerization aids. Aiming at the problem of crosslinking aids of photovoltaic adhesive films being prone to precipitation, the present disclosure provides a grafted polyolefin material capable of preventing precipitation and assisting in crosslinking, a preparation method therefor, and the use thereof. The grafted polyolefin material comprises the following components: a polyolefin elastomer, a first monomer, and a second monomer, the first monomer being at least one selected from triallyl isocyanurate, triallyl cyanurate, and an acrylate compound containing 2-4 carbon-carbon double bonds, and the second monomer being a dialkoxysilane or trialkoxysilane compound containing a carbon-carbon double bond. In the present disclosure, the polyolefin elastomer is used as a matrix, and the first monomer and the second monomer are added for reaction, so as to obtain a photovoltaic crosslinking aid graft material having a high grafting rate and low crosslinking. The crosslinking aid graft material has no crystal particle impurities, has good transparency, high effectively-grafting rate and small melt index decrease, and further possesses the characteristics suitable for photovoltaic adhesive films, such as high volume resistivity and high transparency.

Description

Anti-precipitation and cross-linking aid polyolefin grafting material, its preparation method and application

[0001] The present application claims priority to the Chinese patent application No. 202411071504.2 filed on August 06, 2024, and titled "Anti-precipitation and cross-linking aid polyolefin grafting material, its preparation method and application", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure relates to the field of polymerization aids, in particular to anti-precipitation and cross-linking aid polyolefin grafting material, its preparation method and application. BACKGROUND

[0003] In recent years, the market share of TOPCon cells has been expanding, and more and more industry leaders have shifted from PERC cell technology to TOPCon cells. As a result, the cell structure and packaging adhesive film have changed. The PID of N-type TOPCon cells mainly occurs on the front side, so the front side needs to use POE adhesive film or EPE adhesive film. However, POE itself is a non-polar material, and its absorption of additives is poor. After a long period of storage, liquid additives may migrate to the surface of the adhesive film (POE adhesive film) or the EVA layer (EPE adhesive film). This may cause the adhesive film to slip between the cell and the glass (POE adhesive film) during use, or the cross-linking degree of the adhesive film to be insufficient and the interlayer peeling force of the E layer and P layer to be low (EPE adhesive film), thereby affecting the yield of module production.

[0004] Patent CN117925142A absorbs oily liquid additives (such as initiators, cross-linking aids, tackifiers) by cyclodextrin cavities with hydrophobicity, removes external moisture after vacuum drying of cyclodextrin hydrogel, retains internal oily additives, and uses them as raw materials for POE resin to make POE adhesive film, which can prevent the precipitation of liquid additives. However, the preparation and vacuum drying process of cyclodextrin hydrogel is relatively complex and time-consuming, in addition, the cost of cyclodextrin material and the cost of vacuum drying equipment and time are relatively high, which increases the overall production cost.

[0005] Patent CN116948560A encapsulates and prevents precipitation of organic additives by high molecular microcapsules. However, microcapsules may break during processing, causing additives to leak, and the application cost of microcapsule technology is relatively high, which may not be suitable for large-scale production.

[0006] Patent CN117186781A uses a longer alkane structure to increase the compatibility of silane with polyolefin elastomer resin, and reduce the risk of silane additive precipitation, but this method only targets silane additives and cannot avoid the precipitation of other additives (such as cross-linking aids). Patent CN115895532A uses a solution grafting method to graft anti-potential induced attenuation monomers onto the molecular chain of polyolefin elastomer, avoiding the precipitation problem of direct blending, but the solution grafting process is quite complex and difficult to produce continuously.

[0007] Therefore, for the precipitation problem of photovoltaic cross-linking aids such as ethoxylated trimethylolpropane triacrylate, triallyl cyanurate, etc. in POE, EPE adhesive film, an economical and effective solution is needed.

[0008] Disclosed content

[0009] The purpose of the present disclosure includes providing an anti-precipitation and cross-linking aid polyolefin grafting material and its preparation method and application. The polyolefin elastomer is used as the matrix, the first monomer and the second monomer are added to obtain a high grafting rate and low cross-linking photovoltaic cross-linking aid grafting material. The cross-linking aid grafting material has no crystal point impurities, good transparency, high effective grafting rate, less melt index drop, and high volume resistivity, high transparency and other characteristics suitable for photovoltaic adhesive film.

[0010] In order to achieve at least one of the above purposes of the present disclosure, the following technical solutions are adopted:

[0011] In a first aspect, the present disclosure provides an anti-precipitation and cross-linking aid polyolefin grafting material, comprising the following components: polyolefin elastomer, first monomer, second monomer; the first monomer is selected from at least one of triallyl isocyanurate, triallyl cyanurate, and acrylate compound containing 2-4 carbon-carbon double bonds, and the second monomer is a dialkoxysilane or trialkoxysilane compound containing carbon-carbon double bond; the mass of the first monomer and the second monomer is 1-10% of the polyolefin elastomer, and the mass ratio of the first monomer to the second monomer is (0.1-50):1.

[0012] As a preferred, the polyolefin elastomer is one or more of the polymers generated by copolymerization of ethylene and any C3-C8 olefin (propylene, butene, pentene, hexene, octene), and the melt index of the polyolefin elastomer is 0.5-45 g / 10 min.

[0013] As a preference, the acrylate compound having 2 to 4 carbon-carbon double bonds is selected from the group consisting of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl) isocyanurate triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated glyceryl triacrylate, propoxylated glyceryl triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, ditrimethylolpropane tetraacrylate, ditrimethylolpropane tetramethacrylate, propoxylated pentaerythritol tetraacrylate, tricyclodecane dimethanol diacrylate, propoxylated neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate, 2-butyl-2-ethyl-l,3-propanediol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate.

[0014] As a preference, the second monomer is selected from at least one of the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentoxysilane, vinyltriphenoxysilane, vinyltribenzoxysilane, vinyltrimethylenedioxy silane, vinyltriethylenedioxy silane, vinylpropionyloxy silane, vinyltriacetyloxy silane, vinyltricarboxysilane or the like vinylsilane or gamma-methacryloxypropyltrimethoxysilane, gamma-methacryloxypropylmethyldimethoxysilane, gamma-acryloxypropyltrimethoxysilane, gamma-methacryloxypropylmethyldimethoxysilane or the like (meth)acryloxy silane.

[0015] As a preference, the first monomer and the second monomer are one electron withdrawing and the other electron donating; the conjugation effect Q value of the second monomer is > 0.2, further preferably 0.2 to 1; the Q value of the first monomer and the second monomer differ by > 0.2, further preferably by > 0.8.

[0016] As a further preference, the first monomer is triallyl isocyanurate and the second monomer is gamma-methacryloxypropylmethyldimethoxysilane.

[0017] Melt grafting is a suitable method due to its simple process and continuous production. The anti-extrusion grafting material is prepared by grafting the co-crosslinking agent into the base resin through melt grafting. However, the co-crosslinking agent (the first monomer of the present disclosure) contains multiple double bonds that can participate in the reaction, which is prone to crosslinking during the grafting process, reducing the flowability and crosslinking effect in the subsequent processing process. Therefore, a method for inhibiting crosslinking during the grafting process is needed. The present disclosure selects a second monomer with opposite electron-attracting (pushing) properties according to the Q, e value of the first monomer, which forms a more stable free radical with the first monomer under the action of the initiator, thereby inhibiting the crosslinking reaction of the first monomer.

[0018] As preferred, the mass ratio of the first monomer and the second monomer is (0.25-10):1.

[0019] As preferred, the anti-extrusion, co-crosslinking polyolefin grafting material is composed of the following components: polyolefin elastomer 91.0-97.5wt%, first monomer 1.0-5.0wt%, second monomer 0.5-4.0wt%, initiator 0.08-0.2wt%, antioxidant 0-0.2wt%; the sum of the amounts of each component is equal to 100%.

[0020] As preferred, the initiator is a peroxide initiator, and further preferably at least one of the following compounds: tert-butyl peroxy isopropyl carbonate, 2,5-dimethyl-2,5-(bis-tert-butyl peroxy) hexane, tert-butyl peroxy-2-ethylhexyl carbonate, 1,1-bis(tert-butyl peroxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amyl peroxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amyl peroxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amyl peroxy)cyclohexane, 1,1-bis(tert-butyl peroxy)cyclohexane, 2,2-bis(tert-butyl peroxy)butane, tert-butyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxy-2-ethylhexyl carbonate, tert-butyl peroxy-3,3,5-trimethylhexanoate.

[0021] As preferred, the antioxidant includes at least one of a hindered phenolic antioxidant, a phosphite antioxidant, and a sulfur ester antioxidant. As further preferred, the antioxidant is selected from at least one of the following: tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester (antioxidant 101), tri[2.4-di-tert-butylphenyl]phosphite (antioxidant 168), tri(nonylphenyl)phosphite, n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; further preferred is tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester.

[0022] The present disclosure also provides a preparation method of the anti-precipitation and cross-linking aid polyolefin grafting material, comprising the following steps: uniformly mixing raw material components, and extruding and granulating at 85-220°C to obtain granules; and homogenizing and drying the granules to obtain the polyolefin grafting material.

[0023] The anti-precipitation and cross-linking aid polyolefin grafting material is used in a photovoltaic adhesive film, and the photovoltaic adhesive film is a POE adhesive film or an EPE adhesive film. The POE layer of the photovoltaic adhesive film comprises the following components: 1-25 wt% of the polyolefin grafting material, 70-98 wt% of a polyolefin elastomer, and 1-5 wt% of an aid; and the aid comprises at least one of a cross-linking agent, a cross-linking aid, a silane coupling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a tackifier, or a pigment.

[0024] Preferably, the photovoltaic adhesive film is an EPE adhesive film, and the EPE adhesive film is composed of an EVA layer, the POE layer, and an EVA layer. The EVA layer comprises the following components: 95-99.0 wt% of an EVA resin, and 1.0-5.0 wt% of an aid; and the aid comprises at least one of a cross-linking agent, a cross-linking aid, a silane coupling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a tackifier, or a pigment.

[0025] Compared with the prior art, the present disclosure has the following beneficial effects:

[0026] The present disclosure uses a polyolefin elastomer as a matrix, adds a first monomer and a second monomer, selects a suitable initiator, and controls the ratio of raw materials to obtain a photovoltaic cross-linking aid grafting material with high grafting rate and low cross-linking. The cross-linking aid grafting material has no crystal point impurities, good transparency, high effective grafting rate, small melt index drop, high volume resistivity, and high transparency, and is suitable for photovoltaic adhesive films.

[0027] The anti-precipitation and cross-linking aid adhesive film prepared by the present disclosure has fast vulcanization, high cross-linking degree, high volume resistivity, high light transmittance, and small yellowing value after PCT aging. The aid does not precipitate after long-term storage of the adhesive film, and the peel strength does not attenuate. The present disclosure has obvious gains in long-term storage of the adhesive film, anti-slip of the POE adhesive film, and interlayer peeling of the EPE adhesive film. DETAILED DESCRIPTION

[0028] The embodiments of the present disclosure will be described in detail below with reference to the examples, but those skilled in the art will understand that the following examples are only used to illustrate the present disclosure and should not be regarded as limiting the scope of the present disclosure. If no specific conditions are indicated in the examples, the conventional conditions or the conditions recommended by the manufacturer are used.

[0029] In a first aspect, the present disclosure provides a polyolefin grafting material for preventing precipitation and assisting crosslinking, which is composed of the following components: a polyolefin elastomer 91.0-97.5 wt%, a first monomer 1.0-5.0 wt%, a second monomer 0.5-4.0 wt%, an initiator 0.08-0.2 wt%, and an antioxidant 0-0.2 wt%; the sum of the amounts of the components is equal to 100%.

[0030] The polyolefin elastomer is one or more of polymers obtained by copolymerization of ethylene and any C3-C8 olefin (further preferably propylene, butylene, pentene, hexene, octene), and the melt index of the polyolefin elastomer is 0.5-45 g / 10 min.

[0031] The first monomer is selected from at least one of triallyl isocyanurate, triallyl cyanurate, and an acrylate compound having 2-4 carbon-carbon double bonds, and is further preferably triallyl isocyanurate. Specifically, the acrylate compound having 2-4 carbon-carbon double bonds is selected from the following compounds: trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated glycerol triacrylate, propoxylated glycerol triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, ditrimethylolpropane tetraacrylate, ditrimethylolpropane tetramethacrylate, propoxylated pentaerythritol tetraacrylate, tricyclodecane dimethanol diacrylate, propoxylated neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate.

[0032] The second monomer is a trialkoxysilane compound having a carbon-carbon double bond. Specifically, it is selected from at least one of the following compounds: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentoxysilane, vinyltriphenoxysilane, vinyltribenzoxysilane, vinyltris(trimethylene)oxysilane, vinyltris(ethylene)oxysilane, vinylpropionyloxysilane, vinyltriacetyloxysilane, vinyltricarboxysilane, and the like, or a (meth)acryloxy silane such as γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-acryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane.

[0033] The initiator is a peroxide initiator. Specifically, at least one selected from the group consisting of t-butyl peroxy isopropyl carbonate, 2,5-dimethyl-2,5-(bis-t-butylperoxy)hexane, t-butyl peroxy-2-ethylhexyl carbonate, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-amylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-amylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-amylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, t-butyl peroxy-2-ethylhexyl carbonate, t-amyl peroxy-2-ethylhexyl carbonate, t-butyl peroxy-3,3,5-trimethylhexanoate.

[0034] The antioxidant is at least one selected from the group consisting of hindered phenol antioxidants, phosphite antioxidants, and thioester antioxidants. Specifically, at least one selected from the group consisting of pentaerythritol tetrakis[β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (antioxidant 101), tris[2,4-di-t-butylphenyl]phosphite (antioxidant 168), tris(nonylphenyl)phosphite, n-octadecyl β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; further preferably pentaerythritol tetrakis[β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate].

[0035] As preferred, the first monomer and the second monomer are electron-withdrawing and electron-donating, respectively, i.e., the e values are opposite; the conjugation effect Q value of the second monomer is ≥0.2, further preferably 0.2-1; the Q values of the first monomer and the second monomer differ by ≥0.2, further preferably differ by ≥0.8.

[0036] In a second aspect, the present disclosure provides a preparation method of the above-mentioned anti-precipitation and cross-linking-assisted polyolefin grafting material, comprising the following steps:

[0037] (1) Preparation of polyolefin modified resin granules: the components of the polyolefin elastomer, the initiator, the first monomer, the second monomer, and the antioxidant are proportioned and mixed uniformly in a high-mixing device, and then granulated in a twin-screw extruder at 85-220°C to obtain granules;

[0038] (2) The extruded granules are homogenized by a homogenizing barrel and dehumidified and dried to obtain the polyolefin grafting material.

[0039] In a third aspect, the present disclosure provides the use of the anti-precipitation and cross-linking-assisted polyolefin grafting material in a photovoltaic module.

[0040] (1) POE photovoltaic adhesive film. The POE photovoltaic adhesive film comprises the following components: 1-25 wt% of the polyolefin grafting material, 70-98 wt% of the polyolefin elastomer, and 1-5 wt% of the auxiliary agent; the sum of the amounts of the components is equal to 100%. The auxiliary agent includes at least one of a crosslinking agent, a co-crosslinking agent, a silane coupling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a tackifier, and a pigment.

[0041] (2) EPE photovoltaic adhesive film. The EPE adhesive film is composed of an EVA layer, a POE layer, and an EVA layer from top to bottom. The POE layer is the same as the POE photovoltaic adhesive film in (1). The EVA layer comprises the following components: 95-99.0 wt% of EVA resin and 1.0-5.0 wt% of auxiliary agent; the sum of the amounts of the components is equal to 100%. The auxiliary agent includes at least one of a crosslinking agent, a co-crosslinking agent, a silane coupling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a tackifier, or a pigment. The POE layer and the EVA layer are added to a co-extrusion device for melt co-extrusion. After cooling and shaping through a casting device, the edges are cut and rolled to obtain the EPE photovoltaic adhesive film.

[0042] Example 1

[0043] A polyolefin grafting material for preventing precipitation and assisting crosslinking, which is composed of the following components by mass: 94.8 parts of polyolefin elastomer, ethylene-1-butene copolymer (trade name LF675) with a melt index of 14 g / 10 min; 3 parts of a first monomer, triallyl isocyanurate; 2 parts of a second monomer, γ-methacryloyloxypropyl methyl dimethoxy silane; 0.1 part of an initiator, 2,5-dimethyl-2,5-(bis-tert-butyl peroxy) hexane; and 0.1 part of an antioxidant, tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester.

[0044] A method for preparing a polyolefin grafting material for preventing precipitation and assisting crosslinking, which comprises the following steps: the above raw material components are proportionally put into a high-mixing device and uniformly mixed, the processing temperature is set to 210°C, and a twin-screw extruder is used for granulation to obtain granules. The extruded granules are homogenized by a homogenizing barrel and dried by dehumidification to obtain the polyolefin grafting material.

[0045] A preparation method of a POE photovoltaic adhesive film, the steps are as follows: 13wt% of the above-mentioned polyolefin grafting material, 84wt% of polyolefin elastomer (brand LF675) and 3wt% of other additives, other additives are 0.8wt% of peroxide-2-ethylhexyl tert-amyl carbonate, 0.5wt% of triallyl isocyanurate, 0.5wt% of trimethylolpropane trimethacrylate, 0.7wt% of vinyl trimethoxysilane, 0.1wt% of 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid n-octadecyl ester, 0.1wt% of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (ultraviolet absorber 770) and 0.3wt% of 2-hydroxy-4-n-octyloxybenzophenone are uniformly mixed, melt extruded and then cooled, shaped and wound to obtain the POE photovoltaic adhesive film.

[0046] A preparation method of an EPE photovoltaic adhesive film, the steps are as follows:

[0047] (1) Preparation of POE resin layer: 13wt% of the above-mentioned polyolefin grafting material, 84wt% of polyolefin elastomer (brand LF675) and 3wt% of other additives, other additives are 0.8wt% of peroxide-2-ethylhexyl tert-amyl carbonate, 0.5wt% of triallyl isocyanurate, 0.5wt% of trimethylolpropane trimethacrylate, 0.7wt% of vinyl trimethoxysilane, 0.1wt% of 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid n-octadecyl ester, 0.1wt% of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (ultraviolet absorber 770) and 0.3wt% of 2-hydroxy-4-n-octyloxybenzophenone are uniformly mixed, melt extruded and then cooled, shaped and wound to obtain the POE resin layer.

[0048] (2) Preparation of EVA resin layer: 97wt% of EVA resin and 3wt% of other additives, other additives including at least one or more of crosslinking agent, crosslinking aid, silane coupling agent, antioxidant, ultraviolet absorber, light stabilizer, tackifier or pigment, are uniformly mixed, melt extruded and then cooled, shaped and wound to obtain the EVA resin layer.

[0049] (3) Compound: the POE resin layer prepared in step (1) and the EVA resin layer prepared in step (2) are added to a co-extrusion device for melt co-extrusion, and then cooled, shaped and cut through the edge to obtain the EPE photovoltaic adhesive film with a three-layer layered structure, from top to bottom, the EVA resin layer with a thickness of 100μm, the POE resin layer with a thickness of 250μm and the EVA resin layer with a thickness of 100μm.

[0050] Example 2

[0051] A kind of anti-precipitation, crosslinking aid polyolefin grafting material, it is made of the following components by mass fraction:91 parts of polyolefin elastomer, ethylene-1-butene copolymer (brand LF675) with melt index of 14 g / 10 min;4.72 parts of first monomer, triallyl isocyanurate;4 parts of second monomer, γ-methacryloyloxypropyl methyl dimethoxy silane;0.08 parts of initiator, 2,5-dimethyl-2,5-(bis tert-butyl peroxy) hexane;0.2 parts of antioxidant, tetra [β-(3,5-di tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester.

[0052] A kind of anti-precipitation, crosslinking aid polyolefin grafting material, it is made of the following components by mass fraction:91 parts of polyolefin elastomer, ethylene-1-butene copolymer (brand LF675) with melt index of 14 g / 10 min;4.72 parts of first monomer, triallyl isocyanurate;4 parts of second monomer, γ-methacryloyloxypropyl methyl dimethoxy silane;0.08 parts of initiator, 2,5-dimethyl-2,5-(bis tert-butyl peroxy) hexane;0.2 parts of antioxidant, tetra [β-(3,5-di tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester.

[0053] A kind of POE photovoltaic adhesive film preparation method, steps as follows: 13wt% above-mentioned polyolefin grafting material, 84wt% polyolefin elastomer (brand LF675) and 3wt% other auxiliary agent, other auxiliary agent is 0.8wt% peroxide-2-ethylhexyl tert-amyl carbonate, 0.5wt% triallyl isocyanurate, 0.5wt% trimethylolpropane trimethyl acrylate, 0.7wt% vinyl trimethoxysilane, 0.1wt% 3-(3,5-di tert-butyl-4-hydroxyphenyl) propionic acid n-octadecyl ester, 0.1wt% bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (ultraviolet absorber 770) and 0.3wt% 2-hydroxy-4-n-octyloxy benzophenone, are mixed uniformly melt extrusion after cooling and shaping are wound and obtained POE photovoltaic adhesive film.

[0054] A kind of EPE photovoltaic adhesive film preparation method, steps as follows:

[0055] (1) preparation POE resin layer: 13wt% above-mentioned polyolefin grafting material, 84wt% polyolefin elastomer (brand LF675) and 3wt% other auxiliary agent, other auxiliary agent is 0.8wt% peroxide-2-ethylhexyl tert-amyl carbonate, 0.5wt% triallyl isocyanurate, 0.5wt% trimethylolpropane trimethyl acrylate, 0.7wt% vinyl trimethoxysilane, 0.1wt% 3-(3,5-di tert-butyl-4-hydroxyphenyl) propionic acid n-octadecyl ester, 0.1wt% bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (ultraviolet absorber 770) and 0.3wt% 2-hydroxy-4-n-octyloxy benzophenone, are mixed uniformly melt extrusion after cooling and shaping are wound and obtained POE resin layer.

[0056] (2) Preparation of EVA resin layer: 97wt% EVA resin and 3wt% other additives, other additives including at least one or more of crosslinking agent, crosslinking aid, silane coupling agent, antioxidant, ultraviolet absorber, light stabilizer, tackifier or pigment, are mixed uniformly, melt extruded and then cooled and shaped to obtain the EVA resin layer.

[0057] (3) Compound: the POE resin layer prepared in step (1) and the EVA resin layer prepared in step (2) are added to a co-extrusion device for melt co-extrusion, and after cooling and shaping through a casting device, the edges are cut and rolled to obtain a three-layer layered EPE photovoltaic adhesive film, from top to bottom, 100μm thick EVA resin layer, 250μm thick POE resin layer, 100μm thick EVA resin layer.

[0058] Example 3

[0059] A polyolefin grafting material for preventing precipitation and assisting crosslinking, which is composed of the following components by mass: 97.5 parts of polyolefin elastomer, ethylene-1-butene copolymer (brand LF675) with a melt index of 14g / 10min; 1.5 parts of first monomer, triallyl isocyanurate; 0.8 parts of second monomer, γ-methacryloyloxypropylmethyldimethoxysilane; 0.2 parts of initiator, 2,5-dimethyl-2,5-(bis-tert-butylperoxy)hexane.

[0060] A method for preparing a polyolefin grafting material for preventing precipitation and assisting crosslinking, which comprises the following steps: the above raw material components are put into a high-mixing device in proportion, mixed uniformly, the processing temperature is set to 210℃, and a twin-screw extruder is used for granulation to obtain granules, the extruded granules are homogenized by a homogenizing barrel and dried by dehumidification to obtain the polyolefin grafting material.

[0061] A method for preparing a POE photovoltaic adhesive film, which comprises the following steps: 13wt% of the above polyolefin grafting material, 84wt% of polyolefin elastomer (brand LF675) and 3wt% of other additives, other additives being 0.8wt% of tert-amyl peroxy-2-ethylhexyl carbonate, 0.5wt% of triallyl isocyanurate, 0.5wt% of trimethylolpropane trimethacrylate, 0.7wt% of vinyltrimethoxysilane, 0.1wt% of n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.1wt% of bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate (ultraviolet absorber 770) and 0.3wt% of 2-hydroxy-4-n-octyloxybenzophenone, are mixed uniformly, melt extruded and then cooled and shaped to obtain the POE photovoltaic adhesive film.

[0062] A method for preparing an EPE photovoltaic adhesive film, which comprises the following steps:

[0063] (1) Preparation of POE resin layer: 13 wt% of the above polyolefin grafting material, 84 wt% of polyolefin elastomer (brand LF675) and 3 wt% of other additives, other additives are 0.8 wt% of peroxide-2-ethylhexyl tert-amyl carbonate, 0.5 wt% of triallyl isocyanurate, 0.5 wt% of trimethylolpropane trimethacrylate, 0.7 wt% of vinyl trimethoxysilane, 0.1 wt% of 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate n-octadecanol, 0.1 wt% of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (ultraviolet absorber 770) and 0.3 wt% of 2-hydroxy-4-n-octyloxybenzophenone, are mixed uniformly, melt extruded and then cooled, shaped and wound to obtain the POE resin layer.

[0064] (2) Preparation of EVA resin layer: 97 wt% of EVA resin and 3 wt% of other additives, other additives including at least one or more of crosslinking agent, crosslinking aid, silane coupling agent, antioxidant, ultraviolet absorber, light stabilizer, tackifier or pigment, are mixed uniformly, melt extruded and then cooled, shaped and wound to obtain the EVA resin layer.

[0065] (3) Compound: the POE resin layer prepared in step (1) and the EVA resin layer prepared in step (2) are added to a co-extrusion device for melt co-extrusion, and then cooled, shaped by a casting device and cut to obtain a three-layer layered EPE photovoltaic adhesive film, from top to bottom, 100 μm thick EVA resin layer, 250 μm thick POE resin layer, 100 μm thick EVA resin layer.

[0066] Example 4

[0067] The difference from Example 1 is that the first monomer is propoxylated pentaerythritol tetraacrylate.

[0068] Example 5

[0069] The difference from Example 1 is that the second monomer is vinyl trimethylenedioxy silane.

[0070] Example 6

[0071] The difference from Example 1 is that the first monomer is propoxylated trimethylolpropane triacrylate.

[0072] Example 7

[0073] The difference from Example 1 is that the second monomer is vinyl tributoxy silane.

[0074] Example 8

[0075] The difference from Example 1 is that the first monomer is trimethylolpropane tetraacrylate.

[0076] Example 9

[0077] The difference from Example 1 is that the second monomer is vinyl triethylene di-oxy silane.

[0078] Comparative Example 1

[0079] The difference from Example 1 is that no second monomer is added, and the missing amount is made up with polyolefin elastomer. Details are as follows:

[0080] A polyolefin grafting material for preventing precipitation and assisting crosslinking, which is composed of the following components in mass parts: 96.8 parts of polyolefin elastomer, ethylene-1-butene copolymer (brand LF675) with a melt index of 14 g / 10 min; 3 parts of first monomer, triallyl isocyanurate; 0.1 part of initiator, 2,5-dimethyl-2,5-(bis-tert-butyl peroxy) hexane; 0.1 part of antioxidant, tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester.

[0081] A method for preparing a polyolefin grafting material for preventing precipitation and assisting crosslinking, the steps are as follows: the above raw material components are put into a high mixing device in proportion, the processing temperature is set to 210°C, and a twin-screw extruder is used for granulation to obtain granules, and the extruded granules are homogenized, dehumidified and dried in a homogenizing barrel to obtain the polyolefin grafting material.

[0082] A method for preparing a POE photovoltaic adhesive film, the steps are as follows: 13wt% of the above polyolefin grafting material, 84wt% of polyolefin elastomer (brand LF675) and 3wt% of other additives, the other additives are 0.8wt% of tert-amyl peroxy-2-ethylhexyl carbonate, 0.5wt% of triallyl isocyanurate, 0.5wt% of trimethylolpropane trimethacrylate, 0.7wt% of vinyl trimethoxysilane, 0.1wt% of 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propyl n-octadecyl ester, 0.1wt% of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (ultraviolet absorber 770) and 0.3wt% of 2-hydroxy-4-n-octyloxy benzophenone, are mixed uniformly, melt-extruded and then cooled and shaped to obtain a POE photovoltaic adhesive film.

[0083] A method for preparing an EPE photovoltaic adhesive film, the steps are as follows:

[0084] (1) Preparation of POE resin layer: 13wt% of the above polyolefin grafting material, 84wt% of polyolefin elastomer (brand LF675) and 3wt% of other additives, other additives are 0.8wt% of peroxide-2-ethylhexyl tert-amyl carbonate, 0.5wt% of triallyl isocyanurate, 0.5wt% of trimethylolpropane trimethacrylate, 0.7wt% of vinyl trimethoxysilane, 0.1wt% of 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate n-octadecanol, 0.1wt% of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (ultraviolet absorber 770) and 0.3wt% of 2-hydroxy-4-n-octyloxybenzophenone, are mixed uniformly, melt extruded and cooled to shape and wound to obtain the POE resin layer.

[0085] (2) Preparation of EVA resin layer: 97wt% of EVA resin and 3wt% of other additives, other additives including at least one or more of crosslinking agent, crosslinking aid, silane coupling agent, antioxidant, ultraviolet absorber, light stabilizer, tackifier or pigment, are mixed uniformly, melt extruded and cooled to shape and wound to obtain the EVA resin layer.

[0086] (3) Compound: the POE resin layer prepared in step (1) and the EVA resin layer prepared in step (2) are added to a co-extrusion device for melt co-extrusion, and after cooling and shaping through a casting device, the edges are cut and wound to obtain a three-layer layered EPE photovoltaic adhesive film, from top to bottom, in order, 100μm thick EVA resin layer, 250μm thick POE resin layer, 100μm thick EVA resin layer.

[0087] Comparative Example 2

[0088] The difference from Example 1 is that no polyolefin grafting material is added.

[0089] Comparative Example 3

[0090] The difference from Example 1 is that the amount of the first monomer and the second monomer is 0.5wt% and 5.0wt%, respectively.

[0091] Performance test

[0092] The POE photovoltaic adhesive film prepared in each example and comparative example is detected for the maximum static friction coefficient according to GB / T 10006-2021 standard, and the results are shown in Table 1.

[0093] Table 1

[0094] The EPE photovoltaic adhesive films prepared from each of the examples and the comparative examples were subjected to performance tests, and the results are shown in Table 2. The test methods are as follows: ①transmittance: tested according to the method described in GB / T 29848-2018 "Ethylene-vinyl acetate copolymer (EVA) adhesive film for photovoltaic module encapsulation"; ②crosslinking degree: tested according to the method described in GB / T 29848-2018 "Ethylene-vinyl acetate copolymer (EVA) adhesive film for photovoltaic module encapsulation"; ③peeling force test: tested according to the method described in GB / T 29848-2018 "Ethylene-vinyl acetate copolymer (EVA) adhesive film for photovoltaic module encapsulation".

[0095] Table 2

[0096] As can be seen from Tables 1 and 2, compared with Comparative Example 2, the photovoltaic adhesive film prepared by adding the polyolefin grafting material of the present disclosure to the adhesive film prepared in each of the examples has excellent transmittance and anti-precipitation performance.

[0097] The components of the polyolefin grafting material are critical. Compared with Example 1:

[0098] (1) Comparative Example 1 does not add a second monomer. Because the first monomer contains multiple double bonds that can participate in the reaction, crosslinking is easy to initiate during the grafting process, which can weaken the flowability and crosslinking effect in the subsequent processing process. Therefore, Example 1 adds a second monomer to form a more stable free radical with the second monomer, thereby inhibiting the crosslinking reaction of the first monomer.

[0099] (2) The amount of the first monomer and the second monomer in Comparative Example 3 is not within the preferred range, resulting in that the crosslinking degree and the grafting rate of the prepared polyolefin grafting material are not within the ideal range, and finally the anti-precipitation effect of the adhesive film is not good.

[0100] (3) Examples 4-9 selected the first monomer and the second monomer, and the anti-precipitation effect of the adhesive film is not as good as

[0101] In the embodiment 1, the difference between the Q value and the e value of the first monomer and the second monomer is the largest, and the Q value difference is more than 0.8. The triallyl isocyanurate of the first monomer in the embodiment 1 has a higher reaction activity of the triallyl structure, and can effectively react with the active sites in the polymer at a lower temperature, thereby increasing the crosslinking rate and the crosslinking degree; the second monomer γ-methacryloyloxypropylmethyldimethoxysilane has a stronger conjugation effect and is easier to form stable free radicals, and its electron-withdrawing effect is easy to copolymerize with the electron-donating first monomer. The Q value and the e value of the monomer can be inferred according to the chemical structure. In the triallyl isocyanurate, -CH2-N directly connected with the carbon-carbon double bond has a more obvious electron-donating property, and the e value is smaller; and in the γ-methacryloyloxypropylmethyldimethoxysilane, the ester group directly connected with the carbon-carbon double bond has a conjugation property and exhibits electron-withdrawing, and thus the Q value and the e value are both larger. In the embodiment 8, the first monomer is selected as an acrylate monomer, and the Q value and the e value of the second monomer γ-methacryloyloxypropylmethyldimethoxysilane are close to those of the acrylate monomer, the Q value difference is 0.2-0.8, and the anti-precipitation effect is not as good as that of the embodiment 1.

[0102] Although the present disclosure has been illustrated and described with respect to specific embodiments, it is realized that many other changes and modifications can be made to the present disclosure without departing from the spirit and scope of the present disclosure. Therefore, it is meant to include all such changes and modifications within the scope of the appended claims. Industrial applicability

[0103] The present disclosure provides a kind of anti-precipitation, crosslinking aid polyolefin grafting material and its preparation method and application, with polyolefin elastomer as matrix, first monomer, second monomer are added, select suitable initiator, control the proportion of each raw material to obtain high grafting rate, low crosslinking photovoltaic crosslinking aid grafting material, crosslinking aid grafting material has no crystal point impurity, good transparency, effective grafting rate is high, melt index drops little, simultaneously with high volume resistivity, high transparency and other characteristics suitable for photovoltaic adhesive film.

Claims

1. A polyolefin grafting material for preventing precipitation and assisting crosslinking, characterized in that, The composition comprises the following components: polyolefin elastomer, first monomer, second monomer; the first monomer is selected from at least one of triallyl isocyanurate, triallyl cyanurate, and acrylate compound containing 2-4 carbon-carbon double bonds, the second monomer is dialkoxy silane or trialkoxy silane compound containing carbon-carbon double bond; the mass of the first monomer and the second monomer is 1-10% of the polyolefin elastomer, and the mass ratio of the first monomer to the second monomer is (0.1-50):

1.

2. The anti-flooding, co-crosslinking polyolefin grafting material according to claim 1, characterized in that, The polyolefin elastomer is one or more of polymers generated by copolymerization of ethylene and any C3-C8 olefin, and the melt index of the polyolefin elastomer is 0.5-45 g / 10 min.

3. The anti-flooding, co-crosslinking polyolefin grafting material according to claim 1, characterized in that, The acrylate compound containing 2-4 carbon-carbon double bonds is selected from the following compounds: trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl) isocyanurate triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated glycerol triacrylate, propoxylated glycerol triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, ditrimethylolpropane tetraacrylate, ditrimethylolpropane tetramethacrylate, propoxylated pentaerythritol tetraacrylate, tricyclodecane dimethanol diacrylate, propoxylated neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate.

4. The anti-flooding, co-crosslinking polyolefin grafting material according to claim 1 or 2 or 3, characterized in that, The second monomer is selected from at least one of the following compounds: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentoxysilane, vinyltriphenoxysilane, vinyltribenzoxysilane, vinyltris(trimethylene) dioxy silane, vinyltris(ethylene) dioxy silane, vinylpropionyloxy silane, vinyltriacetyloxy silane, vinyltricarboxy silane, or γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, and the like (meth)acryloxy silane.

5. The anti-flooding, co-crosslinking polyolefin grafting material according to claim 1, characterized in that, The mass ratio of the first monomer to the second monomer is (0.25-10):

1.

6. The anti-flooding, co-crosslinking polyolefin grafting material according to claim 1 or 5, characterized in that, The anti-precipitation and cross-linking aid polyolefin grafting material is composed of the following components: polyolefin elastomer 91.0-97.5 wt%, first monomer 1.0-5.0 wt%, second monomer 0.5-4.0 wt%, initiator 0.08-0.2 wt%, and antioxidant 0-0.2 wt%; the sum of the amounts of the components is equal to 100%.

7. The anti-flooding, co-crosslinking polyolefin grafting material according to claim 1, characterized in that, The initiator is a peroxide initiator; the antioxidant includes at least one of hindered phenol antioxidant, phosphite antioxidant, and sulfur ester antioxidant.

8. Process for the preparation of the anti-extruding, co-crosslinking aid polyolefin grafting material according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: mixing raw material components, and extruding and granulating at 85-220 DEG C to obtain granules; and homogenizing and drying the granules to obtain polyolefin grafting material.

9. Use of the anti-extruding, co-crosslinking polyolefin grafting agent according to any one of claims 1 to 7 in photovoltaic encapsulants, characterized in that, The POE layer of the photovoltaic adhesive film comprises the following components: 1-25 wt% of the polyolefin grafting material, 70-98 wt% of polyolefin elastomer, and 1-5 wt% of auxiliary agent; the auxiliary agent comprises at least one of crosslinking agent, auxiliary crosslinking agent, silane coupling agent, antioxidant, ultraviolet absorber, light stabilizer, tackifier, pigment, and the like.

10. Use according to claim 9, characterized in that, The photovoltaic adhesive film is an EPE adhesive film, which is composed of EVA layers and the POE layer; the EVA layer comprises the following components: 95-99.0 wt% of EVA resin, and 1.0-5.0 wt% of auxiliary agent; the auxiliary agent comprises at least one of crosslinking agent, auxiliary crosslinking agent, silane coupling agent, antioxidant, ultraviolet absorber, light stabilizer, tackifier, pigment, and the like.

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