Multilayer composite fiber sheet as well as preparation method and application thereof

Abstract

The invention provides a multi-layer composite fiber sheet and a preparation method and application thereof, and belongs to the technical field of high polymer materials.The multi-layer composite fiber sheet is characterized in that at least one butene-propylene copolymer fiber layer (B) is added between at least two high-density polyethylene fiber layers (A) to form an A-B-A sandwich structure; a plurality of bonding points exist between the butene-propylene copolymer and the high-density polyethylene, bonding curing is achieved, the self heat melting phenomenon is avoided, and the multi-layer composite fiber sheet has the good mechanical property, heat resistance, air permeability, opacity and waterproofness.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a multi-layer composite fiber sheet and a preparation method thereof. Background Art

[0002] High-pressure flash spinning is a type of solution spinning. Its fundamental principle is the high-speed phase separation of a polymer solution. The fiber-forming polymer forms a spinning fluid within a high-temperature, high-pressure reaction vessel and is released under atmospheric pressure. The spinning fluid is ejected from the spinneret at high speed under high pressure, experiencing high-speed stretching during this high-speed motion. Due to the sudden drop in pressure, the spinning fluid undergoes high-speed phase separation, causing the low-boiling-point solvent to rapidly expand. This solidifies into continuous nano- and micro-fibers with a cross-linked network structure.

[0003] High-pressure flash spinning primarily uses polyethylene as the raw material. Polyethylene fibers undergo post-processing processes such as compaction and thermal bonding to create polyethylene fiber layers for applications in medical packaging, protective clothing, and other fields. However, polyethylene resin is susceptible to thermal overheating, which can lead to a significant decrease in product performance, including opacity, breathability, and waterproofing. Furthermore, temperatures exceeding the melting point of polyethylene can cause product deformation or melting.

[0004] The existing technology uses high-temperature resistant polypropylene to replace polyethylene for flash spinning. Although it can improve the heat resistance of the product, due to the high melting point of polypropylene, the strength and softness of the product prepared from the polyethylene fiber layer are poor, making it difficult to apply to the field of medical packaging protection. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a multi-layer composite fiber sheet and a preparation method and application thereof.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions: In a first aspect, a multilayer composite fiber sheet is provided, comprising: (A) at least two top fiber layers comprising high-density polyethylene; (B) at least one core fiber layer comprising a butene-propylene copolymer; the core fiber layer is disposed between the at least two top fiber layers;

[0007] The difference between the initial melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is ≤15°C;

[0008] The difference between the peak melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is ≥10°C.

[0009] In some embodiments, the molecular weight distribution coefficient of the butene-propylene copolymer is 3-5.

[0010] In some embodiments, the butene-propylene copolymer has a butene-derived unit content of 12-25 wt%, preferably 15-20 wt%.

[0011] In some embodiments, the butene-propylene copolymer has a melt flow rate of 0.1-10 g / 10 min, preferably 0.2-5 g / 10 min, at 230° C. and 2.16 kg.

[0012] In some embodiments, the high-density polyethylene has a melt flow rate of 0.1-15 g / 10 min, preferably 0.3-2 g / 10 min, at 190° C. and 2.16 kg.

[0013] In some embodiments, the butene-propylene copolymer has an initial melting temperature of ≤150°C and a peak melting temperature of ≥145°C.

[0014] In some embodiments, the high-density polyethylene has a peak melting temperature of 125-140°C, preferably 130-138°C.

[0015] In some embodiments, the density of the high-density polyethylene is 0.940-0.970 g / cm 3 , preferably 0.942-0.958 g / cm 3 .

[0016] In some embodiments, the top fiber layer and the core fiber layer are produced by flash spinning.

[0017] In a second aspect, a method for preparing the multilayer composite fiber sheet is provided, comprising the following steps:

[0018] Spinning solutions of high-density polyethylene and butene-propylene copolymer are prepared respectively, and the spinning solutions are spun to obtain fiber layers respectively. The obtained fiber layers are composited to obtain a multi-layer composite fiber sheet.

[0019] In some embodiments, the method for preparing the multi-layer composite fiber sheet comprises the following steps:

[0020] Adding high-density polyethylene to a first autoclave and a third autoclave containing a solvent, heating and dissolving, to obtain a first mixed solution and a third mixed solution; adding a butene-propylene copolymer to a second autoclave containing a solvent, heating and dissolving, to obtain a second mixed solution;

[0021] Open the high-pressure control valve between the high-pressure autoclave and the low-pressure autoclave to allow the first mixed liquid to flow into the first low-pressure autoclave, the second mixed liquid to flow into the second low-pressure autoclave, and the third mixed liquid to flow into the third low-pressure autoclave. Heat and dissolve to obtain the first spinning solution, the second spinning solution and the third spinning solution respectively; open the low-pressure control valve to reduce the pressure, so that the first spinning solution, the second spinning solution and the third spinning solution are spun respectively and received by the receiving device to form a fiber layer. The obtained fiber layer is cold pressed and hot rolled to obtain a multi-layer composite fiber sheet.

[0022] In some embodiments, the HDPE fiber layer has a gram weight of 5-50 g / m 2 The weight of the butene-propylene copolymer fiber layer is 5-50g / m 2 .

[0023] In some embodiments, the heating and dissolving conditions of the first autoclave, the second autoclave, and the third autoclave are independently: temperature of 150-230° C., pressure of 5-25 MPa, and stirring time of 20-30 min.

[0024] In some embodiments, the heating and dissolving conditions of the first low-pressure autoclave, the second low-pressure autoclave, and the third low-pressure autoclave are independently: pressure of 5-20 MPa, temperature of 150-230° C., and residence time of 15-30 min.

[0025] In some embodiments, the solvent is at least one of 1,2-dichloroethane, dichloromethane, n-pentane, and cyclohexane.

[0026] In some embodiments, the mass percentage concentration of high-density polyethylene in the first mixed solution and the third mixed solution is independently 5-25%.

[0027] In some embodiments, the mass percentage concentration of the butene-propylene copolymer in the second mixed liquid is 5-25%.

[0028] In a third aspect, a product is provided, wherein the product contains the multi-layer composite fiber sheet or the multi-layer composite fiber sheet prepared by the preparation method.

[0029] In a fourth aspect, a medical device protective packaging product is provided, wherein the medical device protective packaging product contains the multi-layer composite fiber sheet or the multi-layer composite fiber sheet prepared by the preparation method.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention adds at least one layer of butene-propylene copolymer fiber layer (B) between at least two layers of high-density polyethylene fiber layers (A) to form an "ABA" sandwich structure. There are multiple bonding points between the butene-propylene copolymer and the high-density polyethylene, which are bonded and solidified without self-melting, so that the multi-layer composite fiber sheet has good mechanical properties, heat resistance, air permeability, opacity and waterproofness. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic structural diagram of the flash jet spinning equipment for a layer of fiber of the present invention, wherein: 1 is an autoclave; 2 is a low-pressure autoclave; 3 is a spinneret; 4 is a filament separation baffle; 5 is a high-pressure control valve; 6 is a low-pressure control valve; 7 is a heating jacket for the autoclave; 8 is a heating jacket for the low-pressure autoclave; 9 is a stirrer; and 10 is a control device;

[0032] Figure 2 It is a schematic diagram of the spinning device of the multi-layer composite fiber sheet of the present invention, wherein 11 is the first spinning solution, 12 is the second spinning solution, 13 is the third spinning solution, 14 is the compacting roller, 15 is the receiving device, and 16 is the spinning box. DETAILED DESCRIPTION

[0033] To facilitate understanding of the present invention, the present invention will be described more fully below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0034] As used herein:

[0035] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations 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.

[0036] The conjunction "consisting of" excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed, excluding 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.

[0037] When amount, concentration or other value or parameter are represented with range, preferred range or the range that a series of upper preferred value and lower preferred value limit are expressed, 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, and no matter whether this scope is disclosed separately.For example, when disclosing scope " 1-5 ", described scope should be interpreted as including scope " 1-4 ", " 1-3 ", " 1-2 ", " 1-2 and 4-5 ", " 1-3 and 5 " etc.When numerical range is described in this article, unless otherwise stated, otherwise this scope is intended to include its end value and all integers and fractions within this range.

[0038] In these examples, parts and percentages are by mass unless otherwise indicated.

[0039] "Parts by mass" refers to the basic unit of measurement used to express the mass ratio of multiple components. One part can represent any unit of mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, this means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, we could say that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number representing a multiplication factor). It's important to note that, unlike parts by mass, the sum of the mass of all components is not limited to 100 parts.

[0040] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0041] A multi-layer composite fiber sheet, comprising (A) at least two top fiber layers comprising high-density polyethylene; (B) at least one core fiber layer comprising a butene-propylene copolymer, the core fiber layer being disposed between the at least two top fiber layers;

[0042] The difference between the initial melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is ≤15°C;

[0043] The difference between the peak melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is ≥10°C.

[0044] The present invention adds at least one layer of butene-propylene copolymer fiber layer (B) between at least two layers of high-density polyethylene fiber layers (A) to form an "ABA" sandwich structure. There are multiple bonding points between the butene-propylene copolymer and the high-density polyethylene, which are bonded and solidified without self-melting. This allows the multi-layer composite fiber sheet to have good mechanical properties, heat resistance, air permeability, opacity and waterproofness.

[0045] If the difference between the initial melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is too high, the top layer and the core layer fibers cannot be effectively bonded during the thermal bonding process, resulting in insufficient mechanical properties; if the difference between the peak melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is too low, the top layer and the core layer fibers are prone to excessive bonding during the thermal bonding process, resulting in a decrease in opacity, air permeability and waterproof performance.

[0046] For example, in different embodiments, the butene-propylene copolymer has a butene-derived unit content of 12-25 wt%, for example, but not limited to 12 wt%, 13 wt%, 15 wt%, 17 wt%, 19 wt%, 21 wt%, 23 wt%, 25 wt%; preferably 15-20 wt%.

[0047] For example, in different embodiments, the melt flow rate of the butene-propylene copolymer is determined according to the GB / T3682.1-2018 method, the test conditions are 230°C, 2.16 kg, and the melt flow rate of the butene-propylene copolymer is 0.1-10 g / 10 min, for example, it can be but not limited to 0.1 g / 10 min, 0.3 g / 10 min, 0.5 g / 10 min, 1 g / 10 min, 3 g / 10 min, 4 g / 10 min, 6 g / 10 min, 8 g / 10 min, 9 g / 10 min, 10 g / 10 min; preferably 0.2-5 g / 10 min.

[0048] Applicants have discovered that when the melt flow rate of the butene-propylene copolymer is 0.1-10 g / 10 min (230°C, 2.16 kg), the fibers can be properly stretched during the spinning process, avoiding abnormal phenomena such as discontinuous spinning and the possibility of flying catkins, while also meeting the requirements for mechanical and waterproof properties. Preferably, when the melt flow rate of the butene-propylene copolymer is 0.2-5 g / 10 min (230°C, 2.16 kg), the multi-layer composite fiber sheet exhibits improved waterproofness, opacity, and air permeability.

[0049] For example, in different embodiments, the difference between the initial melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is 1-15°C, for example, but not limited to 1°C, 3°C, 5°C, 7°C, 9°C, 11°C, 13°C, 15°C; preferably 4-11°C;

[0050] For example, in different embodiments, the difference between the peak melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is ≥10°C, for example, 10-22°C, 14-19°C, and specifically can be but not limited to 10°C, 13°C, 15°C, 17°C, 20°C, 22°C.

[0051] In the present invention, the peak melting temperature of the high-density polyethylene, and the initial melting temperature and peak melting temperature of the butene-propylene copolymer are obtained by differential scanning calorimetry using the method described in GB / T 19466.3-2004. The initial melting temperature refers to the extrapolated onset temperature in GB / T 19466.3-2004.

[0052] In the present invention, the butene-derived unit content of the butene-propylene copolymer is measured by referring to the method specified in SH / T 800.

[0053] In some embodiments, the molecular weight distribution coefficient of the butene-propylene copolymer is 3-5, for example, but not limited to 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, and 5.

[0054] In the present invention, the molecular weight distribution coefficient of the butene-propylene copolymer is tested using a high-temperature GPC instrument, the solvent is trichlorobenzene, the sample treatment temperature is 160° C., and the treatment time is 120 min.

[0055] The applicant has found that when the molecular weight distribution coefficient of the butene-propylene copolymer is 3-5, the butene-propylene copolymer can be better bonded to the high-density polyethylene fiber during the thermal bonding process, further improving the bonding effect and effectively avoiding the problem of fiber discontinuity.

[0056] In some embodiments, the butene-propylene copolymer has an initial melting temperature of ≤150°C and a peak melting temperature of ≥145°C.

[0057] For example, in different embodiments, the initial melting temperature of the butene-propylene copolymer is 136-150° C., for example, but not limited to, 136° C., 140° C., 145° C., or 150° C.;

[0058] For example, in different embodiments, the peak melting temperature of the butene-propylene copolymer is 145-155°C, for example, but not limited to, 145°C, 148°C, 150°C, 152°C, and 155°C.

[0059] The butene-propylene copolymer of the present invention can be a commercially available product, or can be prepared in-house, for example, by the Spheripol process.

[0060] The butene-propylene copolymer described in the present invention can be prepared by the following method:

[0061] S1: injecting propylene and a catalyst into a polymerization reactor to carry out a prepolymerization reaction to obtain a prepolymer;

[0062] S2: After the prepolymerization reaction, the prepolymer is polymerized with propylene monomer, hydrogen and butene in a loop reactor to obtain a random copolymer;

[0063] S3: The random copolymer produced in the loop reactor is vaporized and then enters the gas phase reactor; in the gas phase reactor, it undergoes copolymerization reaction with butene and propylene to obtain a butene-propylene copolymer.

[0064] The method can be carried out using any catalyst suitable for preparing butene-propylene copolymers. Preferably, the above method is carried out using a Ziegler-Natta catalyst, especially a high-yield Ziegler-Natta catalyst (so-called fourth and fifth generation types, which are different from the so-called second generation Ziegler-Natta catalysts of low yield). Ziegler-Natta catalysts suitable for the present invention comprise a catalyst component, a co-catalyst component and at least one electron donor (internal and / or external electron donor, preferably at least one external donor). Preferably, the catalyst component is a Ti-Mg based catalyst component, and a typical co-catalyst is an Al-alkyl based compound. Preferred external donors are known silane based donors, such as dicyclopentyldimethoxysilane or cyclohexylmethyldimethoxysilane.

[0065] Specifically, the added amount of the catalyst is 0.01-0.08% of the mass of propylene.

[0066] Specifically, in step S1, the prepolymerization reaction temperature is 15-25° C. and the time is 10-20 minutes.

[0067] Specifically, in step S2, the polymerization reaction temperature is 40-110°C, preferably 60-100°C, and especially 80-90°C; the pressure is 20-80 bar, preferably 30-60 bar; and the residence time is 0.5-5h, preferably 0.5-2h.

[0068] Specifically, in step S2, the number of loop reactors is two.

[0069] Specifically, in step S3, the polymerization reaction temperature is 50-130° C., more preferably 80-100° C.; the pressure is 5-50 bar, preferably 15-35 bar; and the residence time is 10-30 min.

[0070] The properties of the butene-propylene copolymer prepared by the above method can be adjusted and controlled by process conditions known to those skilled in the art, such as at least one of the following parameters: temperature, hydrogen flow rate, butene feed, propylene feed, catalyst dosage, residence time, and pressure.

[0071] In some embodiments, the density of the high-density polyethylene is 0.940-0.970 g / cm 3, for example, but not limited to 0.942 g / cm 3 , 0.944g / cm 3 , 0.946g / cm 3 , 0.948g / cm 3 、0.950g / cm 3 , 0.952g / cm 3 、0.954g / cm 3 , 0.956g / cm 3 、0.958g / cm 3 ; preferably 0.942-0.958g / cm 3 .

[0072] In the present invention, the density of high-density polyethylene is measured by referring to the method specified in GB / T 1033.1-2008.

[0073] For example, in different embodiments, the melt flow rate of high-density polyethylene is measured according to the method shown in GB / T3682.1-2018 standard, the test conditions are 190°C, 2.16 kg, and the melt flow rate of high-density polyethylene is 0.1-15 g / 10 min, for example, it can be but not limited to 0.1 g / 10 min, 0.5 g / 10 min, 1 g / 10 min, 3 g / 10 min, 4 g / 10 min, 6 g / 10 min, 8 g / 10 min, 9 g / 10 min, 10 g / 10 min, 13 g / 10 min, 15 g / 10 min; preferably 0.3-2 g / 10 min.

[0074] For example, in different embodiments, the peak melting temperature of the high-density polyethylene is 125-140°C, for example, but not limited to 125°C, 130°C, 135°C, 140°C, preferably 130-138°C.

[0075] As in a different embodiment, the top fiber layer and the core fiber layer are made by flash spinning.

[0076] Both component (A) and component (B) may further include additives commonly used in the polyolefin field, such as antioxidants, light stabilizers, nucleating agents, lubricants, antistatic agents, colorants, fillers, and the like.

[0077] Specifically, the mass of the additive is 0.001-30% of the total mass of the multi-layer composite fiber sheet.

[0078] like Figure 1As shown, the flash jet spinning equipment for producing a layer of fiber of the present invention includes an autoclave 1, a heating jacket 7, a low-pressure autoclave 2, and a heating jacket 8. The autoclave 1 and the low-pressure autoclave 2 are connected and are equipped with a high-pressure control valve 5; an agitator 9 is installed in the autoclave 1; the output pipe of the low-pressure autoclave 2 is connected to the spinneret 3 through the low-pressure control valve 6, and a filament separation baffle 4 is installed at the outlet of the spinneret 3; the heating jackets (including the autoclave heating jacket 7 and the low-pressure autoclave heating jacket 8), the control valves (including the high-pressure control valve 5 and the low-pressure control valve 6), and the agitator 9 are respectively connected to a control device 10;

[0079] The outer wall of the autoclave 1 described in the present invention is heated by an autoclave heating jacket 7 to meet the temperature requirements of the spinning process. An agitator 9 is installed within the autoclave 1 to fully stir the polymer solution. The agitator 9 is connected to a control device 10 and can be adjusted in speed as needed. The autoclave heating jacket 7 is also connected to the control device 10 and can also be adjusted in temperature according to process requirements. These speed and temperature adjustments are conventional. The outer wall of the low-pressure autoclave 2 described in the present invention is heated by a low-pressure autoclave heating jacket 8. The low-pressure autoclave 2 and the low-pressure autoclave heating jacket 8 are also connected to the control device 10 and can also be adjusted in temperature according to process requirements. The autoclave 1 and the low-pressure autoclave 2 are connected and equipped with a high-pressure control valve 5. When the autoclave control valve 5 is opened, the solution in the autoclave 1 can flow from the autoclave 1 into the low-pressure autoclave 2, and the flow rate and flow rate can be controlled by the high-pressure control valve 5. The output pipe of the low-pressure autoclave 2 is connected to a low-pressure control valve 6, which is connected to the spinneret 3. The filament separation baffle 4 is screwed to the spinneret 3. When the low-pressure control valve 6 is opened, the solution can be sprayed out from the low-pressure kettle 2 through the spinneret 3 and the filament baffle 4, and the flow rate and flow velocity can be controlled by the low-pressure control valve 6; the present invention uses at least three sets of parallel flash spinning equipment to prepare the multi-layer composite fiber sheet of the present invention.

[0080] Specifically, the flash jet spinning device for producing a layer of fibers of the present invention adopts the flash jet spinning device for producing ultrafine fibers used in CN 101173374A.

[0081] It should be noted that the products of this application are not limited to the production of the above-mentioned production equipment. Technical personnel in this field can also use other types of flash spraying production equipment to produce products according to actual needs, as long as they can produce products with the same technical characteristics and technical effects.

[0082] In a second aspect, a method for preparing the multilayer composite fiber sheet is provided, comprising the following steps:

[0083] Spinning solutions of high-density polyethylene and butene-propylene copolymer are prepared respectively, and the spinning solutions are spun to obtain fiber layers respectively. The obtained fiber layers are composited to obtain a multi-layer composite fiber sheet.

[0084] In some embodiments, a method for preparing a multilayer composite fiber sheet comprises the following steps: adding high-density polyethylene to a first autoclave and a third autoclave containing a solvent, heating and dissolving the high-density polyethylene to obtain a first mixed solution and a third mixed solution; adding a butene-propylene copolymer to a second autoclave containing a solvent, heating and dissolving the high-density polyethylene to obtain a second mixed solution;

[0085] Opening the high-pressure control valve between the autoclave and the low-pressure autoclave to allow the first mixed solution to flow into the first low-pressure autoclave, the second mixed solution to flow into the second low-pressure autoclave, and the third mixed solution to flow into the third low-pressure autoclave, heating and dissolving to obtain a first spinning solution, a second spinning solution, and a third spinning solution, respectively;

[0086] like Figure 2 As shown, the low-pressure control valve is opened to reduce the pressure, so that the first spinning solution 11, the second spinning solution 12 and the third spinning solution 13 are spun respectively and received into fiber layers by the receiving device 15. The obtained fiber layers are cold-pressed and hot-rolled by the compacting roller 14 to obtain a multi-layer composite fiber sheet.

[0087] In some embodiments, the HDPE fiber layer has a grammage of 5-50 g / m 2 , for example, but not limited to 5g / m 2 , 10g / m 2 , 20g / m 2 , 30g / m 2 , 40g / m 2 , 50g / m 2 .

[0088] In some embodiments, the grammage of the butene-propylene copolymer fiber layer is 5-50 g / m 2 , for example, but not limited to 5g / m 2 , 10g / m 2 , 20g / m 2 , 30g / m 2 , 40g / m 2 , 50g / m 2 .

[0089] In some embodiments, the heating and dissolving conditions of the first autoclave, the second autoclave, and the third autoclave are independently: temperature of 150-230° C., pressure of 5-25 MPa, and stirring time of 20-30 min.

[0090] In some embodiments, the heating and dissolving conditions of the first low-pressure autoclave, the second low-pressure autoclave, and the third low-pressure autoclave are independently: pressure of 5-20 MPa, temperature of 150-230° C., and residence time of 15-30 min.

[0091] In some embodiments, the boiling point of the solvent is ≤100° C.; preferably, the solvent is at least one of 1,2-dichloroethane, dichloromethane, n-pentane, and cyclohexane.

[0092] In some embodiments, the mass percentage concentration of high-density polyethylene in the first mixed solution and the third mixed solution is independently 5-25%; for example, it can be but not limited to 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25%;

[0093] In some embodiments, the mass percentage concentration of the butene-propylene copolymer in the second mixed liquid is 5-25%, for example, but not limited to 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 25%.

[0094] In some embodiments, the hot rolling temperature is 130-150°C, for example, but not limited to, 130°C, 135°C, 140°C, 145°C, or 150°C.

[0095] Specifically, the receiving device is a conductive mesh curtain.

[0096] In a third aspect, a product is provided, wherein the product contains the multi-layer composite fiber sheet or the multi-layer composite fiber sheet prepared by the preparation method.

[0097] In a fourth aspect, a medical device protective packaging product is provided, which contains the multi-layer composite fiber sheet or the multi-layer composite fiber sheet prepared by the preparation method; the medical device packaging product includes protective clothing, packaging bags, side-sealed bags, etc.

[0098] The raw materials used in the examples and comparative examples are described below, but are not limited to these materials:

[0099] High-density polyethylene A: melting peak temperature is 134°C, density is 0.955 g / cm 3 , melt flow rate is 0.3g / 10min (test conditions are 190℃, 2.16kg), from Sinopec Maoming Branch, model HHM5502LW;

[0100] High-density polyethylene B: melting peak temperature is 136°C, density is 0.945 g / cm 3 , melt flow rate is 1g / 10min (test conditions are 190℃, 2.16kg), from LyondellBasell, model GF7750M2;

[0101] Butene-propylene copolymer AK is homemade, and its preparation method is as follows:

[0102] S1: injecting propylene and a commercial fifth-generation Ziegler-Natta catalyst into polymerization reactor A to carry out a prepolymerization reaction to obtain a prepolymer; wherein the prepolymerization reaction temperature is 15-25° C. and the reaction time is 10-20 minutes;

[0103] S2: After the prepolymerization reaction, the prepolymer is polymerized with propylene monomer, hydrogen and butene in loop reactor B / C to obtain a random copolymer; wherein the polymerization temperature is 40-110°C, the pressure is 20-80 bar, and the residence time is 0.5-5 hours;

[0104] S3: The random copolymer produced in the loop reactor is vaporized and then enters a gas phase reactor; in the gas phase reactor, it undergoes block copolymerization with butene and propylene to obtain a butene-propylene copolymer; wherein the copolymerization reaction temperature is 50-130°C, the pressure is 5-50 bar, and the residence time is 10-30 minutes;

[0105] The butene-propylene copolymer AK is obtained by adjusting and controlling at least one parameter among temperature, hydrogen flow, butene feed, propylene feed, catalyst dosage, residence time and pressure.

[0106] Butene-propylene copolymer A: butene-derived unit content of 18 wt%, molecular weight distribution of 4.0, melt flow rate of 2 g / 10 min, initial melting temperature of 141°C, and peak melting temperature of 150°C;

[0107] Butene-propylene copolymer B: butene-derived unit content 20 wt%, molecular weight distribution 3.8, melt flow rate 2 g / 10 min, initial melting temperature 138°C, and peak melting temperature 148°C;

[0108] Butene-propylene copolymer C: butene-derived unit content of 15 wt%, molecular weight distribution of 4.1, melt flow rate of 2 g / 10 min, initial melting temperature of 145°C, and peak melting temperature of 153°C;

[0109] Butene-propylene copolymer D: butene-derived unit content of 12 wt%, molecular weight distribution of 4.5, melt flow rate of 2 g / 10 min, initial melting temperature of 148°C, and peak melting temperature of 155°C;

[0110] Butene-propylene copolymer E: butene-derived unit content 25 wt%, molecular weight distribution 3.7, melt flow rate 2 g / 10 min, initial melting temperature 136°C, and peak melting temperature 146°C;

[0111] Butene-propylene copolymer F: butene-derived unit content of 18 wt%, molecular weight distribution of 3.9, melt flow rate of 0.2 g / 10 min, initial melting temperature of 141°C, and peak melting temperature of 151°C;

[0112] Butene-propylene copolymer G: butene-derived unit content of 18 wt%, molecular weight distribution of 4.1, melt flow rate of 5 g / 10 min, initial melting temperature of 140°C, and peak melting temperature of 150°C;

[0113] Butene-propylene copolymer H: butene-derived unit content of 18 wt%, molecular weight distribution of 3.8, melt flow rate of 10 g / 10 min, initial melting temperature of 139°C, and peak melting temperature of 148°C;

[0114] Butene-propylene copolymer I: butene-derived unit content of 18 wt%, molecular weight distribution of 4.3, melt flow rate of 0.1 g / 10 min, initial melting temperature of 141°C, and peak melting temperature of 152°C;

[0115] Butene-propylene copolymer J: butene-derived unit content 10 wt%, molecular weight distribution 3.6, melt flow rate 2 g / 10 min, initial melting temperature 154°C, and peak melting temperature 160°C;

[0116] Butene-propylene copolymer K: the butene-derived unit content is 28 wt%, the molecular weight distribution is 4.9, the melt flow rate is 2 g / 10 min, the initial melting temperature is 134° C., and the melting peak temperature is 143° C.

[0117] Example 1

[0118] This embodiment provides a multilayer composite fiber sheet, comprising (A) two top fiber layers, which include high-density polyethylene A; (B) a core fiber layer, which includes butene-propylene copolymer A; the core fiber layer is arranged between the two top fiber layers; wherein the top fiber layer has a gram weight of 20g / m 2 The core fiber layer has a gram weight of 30g / m 2 .

[0119] The method for preparing the multilayer composite fiber sheet of this embodiment includes the following steps:

[0120] High-density polyethylene A was added to a first autoclave and a third autoclave containing dichloromethane, and heated to dissolve to obtain a first mixed solution and a third mixed solution; butene-propylene copolymer A was added to a second autoclave containing dichloromethane, and heated to dissolve to obtain a second mixed solution; the heating and dissolving conditions in the first, second, and third autoclaves were all: temperature 190° C., pressure 15 MPa, and stirring time 25 minutes; the mass percentage concentration of high-density polyethylene A in the first and third mixed solutions was 15 wt%, and the mass percentage concentration of butene-propylene copolymer in the second mixed solution was 15 wt%;

[0121] The high-pressure control valve between the autoclave and the low-pressure autoclave was opened to allow the first mixed solution to flow into the first low-pressure autoclave, the second mixed solution to flow into the second low-pressure autoclave, and the third mixed solution to flow into the third low-pressure autoclave, and the mixture was heated and dissolved to obtain a first spinning solution, a second spinning solution, and a third spinning solution, respectively. The heating and dissolving conditions of the first low-pressure autoclave, the second low-pressure autoclave, and the third low-pressure autoclave were independently: a pressure of 8 MPa, a temperature of 190° C., and a residence time of 20 min.

[0122] like Figure 2 As shown, the low-pressure control valve is opened to reduce the pressure, so that the first spinning solution 11, the second spinning solution 12 and the third spinning solution 13 are spun respectively and received into fiber layers by the receiving device 15. In this embodiment, the receiving device 15 is a conductive mesh curtain. The obtained fiber layer is cold-pressed by the compacting roller 14, and then hot-rolled at a temperature of 140°C to obtain a multi-layer composite fiber sheet.

[0123] Example 2

[0124] This embodiment provides a multilayer composite fiber sheet, comprising (A) two top fiber layers, each comprising high-density polyethylene B; (B) a core fiber layer, each comprising a butene-propylene copolymer A; the core fiber layer is disposed between the two top fiber layers; wherein the top fiber layer has a grammage of 25 g / m 2 The core fiber layer has a gram weight of 25g / m 2 .

[0125] The method for preparing the multilayer composite fiber sheet of this embodiment includes the following steps:

[0126] High-density polyethylene B was added to a first autoclave and a third autoclave containing dichloromethane, and heated to dissolve to obtain a first mixed solution and a third mixed solution; butene-propylene copolymer A was added to a second autoclave containing dichloromethane, and heated to dissolve to obtain a second mixed solution; the conditions for heating and dissolving in the first autoclave were: temperature 150° C., pressure 25 MPa, and stirring time 25 min; the conditions for heating and dissolving in the second autoclave were: temperature 230° C., pressure 10 MPa, and stirring time 25 min; the conditions for heating and dissolving in the third autoclave were: temperature 150° C., pressure 25 MPa, and stirring time 25 min; the mass percentage concentration of high-density polyethylene B in the first mixed solution was 10 wt %, the mass percentage concentration of high-density polyethylene B in the third mixed solution was 20 wt %, and the mass percentage concentration of butene-propylene copolymer in the second mixed solution was 10 wt %;

[0127] The high-pressure control valve between the autoclave and the low-pressure autoclave was opened to allow the first mixed liquid to flow into the first low-pressure autoclave, the second mixed liquid to flow into the second low-pressure autoclave, and the third mixed liquid to flow into the third low-pressure autoclave, and the mixture was heated and dissolved to obtain a first spinning solution, a second spinning solution, and a third spinning solution, respectively. The conditions for heating and dissolving in the first low-pressure autoclave were: temperature 150° C., pressure 10 MPa, and stirring time 25 min; the conditions for heating and dissolving in the second low-pressure autoclave were: temperature 230° C., pressure 5 MPa, and stirring time 25 min; and the conditions for heating and dissolving in the third low-pressure autoclave were: temperature 150° C., pressure 10 MPa, and stirring time 25 min.

[0128] like Figure 2 As shown, the low-pressure control valve is opened to reduce the pressure, so that the first spinning solution 11, the second spinning solution 12 and the third spinning solution 13 are spun respectively and received into fiber layers by the receiving device 15. In this embodiment, the receiving device 15 is a conductive mesh curtain. The obtained fiber layer is cold-pressed by the compacting roller 14, and then hot-rolled at a temperature of 140°C to obtain a multi-layer composite fiber sheet.

[0129] Example 3

[0130] This embodiment provides a multilayer composite fiber sheet, comprising (A) two top fiber layers, each comprising high-density polyethylene A; (B) a core fiber layer, each comprising a butene-propylene copolymer B; the core fiber layer is disposed between the two top fiber layers; wherein the top fiber layer has a grammage of 20 g / m 2 The core fiber layer has a gram weight of 30g / m 2 .

[0131] The only difference between the method for preparing the multilayer composite fiber sheet of this embodiment and the method for preparing the multilayer composite fiber sheet of Example 1 is that butene-propylene copolymer B is used instead of butene-propylene copolymer A, and the other steps and parameters remain unchanged.

[0132] Example 4

[0133] This embodiment provides a multilayer composite fiber sheet, comprising (A) two top fiber layers, each comprising high-density polyethylene A; (B) a core fiber layer, each comprising a butene-propylene copolymer C; the core fiber layer is disposed between the two top fiber layers; wherein the top fiber layer has a gram weight of 20 g / m 2 The core fiber layer has a gram weight of 30g / m 2 .

[0134] The only difference between the method for preparing the multilayer composite fiber sheet of this embodiment and the method for preparing the multilayer composite fiber sheet of Example 1 is that butene-propylene copolymer C is used instead of butene-propylene copolymer A, and the other steps and parameters remain unchanged.

[0135] Example 5

[0136] This embodiment provides a multilayer composite fiber sheet, comprising (A) two top fiber layers comprising high-density polyethylene A; (B) a core fiber layer comprising butene-propylene copolymer D; the core fiber layer is disposed between the two top fiber layers; wherein the top fiber layer has a gram weight of 20 g / m 2 The core fiber layer has a gram weight of 30g / m 2 .

[0137] The only difference between the method for preparing the multilayer composite fiber sheet of this embodiment and the method for preparing the multilayer composite fiber sheet of Example 1 is that butene-propylene copolymer D is used instead of butene-propylene copolymer A, and the other steps and parameters remain unchanged.

[0138] Example 6

[0139] This embodiment provides a multilayer composite fiber sheet, comprising (A) two top fiber layers comprising high-density polyethylene A; (B) a core fiber layer comprising butene-propylene copolymer E; the core fiber layer is disposed between the two top fiber layers; wherein the top fiber layer has a gram weight of 20 g / m 2 The core fiber layer has a gram weight of 30g / m 2 .

[0140] The only difference between the method for preparing the multilayer composite fiber sheet of this embodiment and the method for preparing the multilayer composite fiber sheet of Example 1 is that butene-propylene copolymer E is used instead of butene-propylene copolymer A, and the other steps and parameters remain unchanged.

[0141] Example 7

[0142] This embodiment provides a multilayer composite fiber sheet, comprising (A) two top fiber layers comprising high-density polyethylene A; (B) a core fiber layer comprising a butene-propylene copolymer F; the core fiber layer is disposed between the two top fiber layers; wherein the top fiber layer has a gram weight of 20 g / m 2 The core fiber layer has a gram weight of 30g / m 2 .

[0143] The only difference between the method for preparing the multilayer composite fiber sheet of this embodiment and the method for preparing the multilayer composite fiber sheet of Example 1 is that butene-propylene copolymer F is used instead of butene-propylene copolymer A, and the other steps and parameters remain unchanged.

[0144] Example 8

[0145] This embodiment provides a multilayer composite fiber sheet, comprising (A) two top fiber layers comprising high-density polyethylene A; (B) a core fiber layer comprising a butene-propylene copolymer G; the core fiber layer is disposed between the two top fiber layers; wherein the top fiber layer has a gram weight of 20 g / m 2 The core fiber layer has a gram weight of 30g / m 2 .

[0146] The only difference between the method for preparing the multilayer composite fiber sheet of this embodiment and the method for preparing the multilayer composite fiber sheet of Example 1 is that butene-propylene copolymer G is used instead of butene-propylene copolymer A, and the other steps and parameters remain unchanged.

[0147] Example 9

[0148] This embodiment provides a multilayer composite fiber sheet, comprising (A) two top fiber layers comprising high-density polyethylene A; (B) a core fiber layer comprising a butene-propylene copolymer H; the core fiber layer is disposed between the two top fiber layers; wherein the top fiber layer has a gram weight of 20 g / m 2 The core fiber layer has a gram weight of 30g / m 2 .

[0149] The only difference between the method for preparing the multilayer composite fiber sheet of this embodiment and the method for preparing the multilayer composite fiber sheet of Example 1 is that butene-propylene copolymer H is used instead of butene-propylene copolymer A, and the other steps and parameters remain unchanged.

[0150] Example 10

[0151] This embodiment provides a multilayer composite fiber sheet, comprising (A) two top fiber layers comprising high-density polyethylene A; (B) a core fiber layer comprising butene-propylene copolymer I; the core fiber layer is disposed between the two top fiber layers; wherein the top fiber layer has a gram weight of 20 g / m 2 The core fiber layer has a gram weight of 30g / m2 .

[0152] The only difference between the method for preparing the multilayer composite fiber sheet of this embodiment and the method for preparing the multilayer composite fiber sheet of Example 1 is that butene-propylene copolymer I is used instead of butene-propylene copolymer A, and the other steps and parameters remain unchanged.

[0153] Comparative Example 1

[0154] This comparative example provides a multilayer composite fiber sheet, comprising (A) two top fiber layers comprising high-density polyethylene A; (B) a core fiber layer comprising butene-propylene copolymer J; the core fiber layer is disposed between the two top fiber layers; wherein the top fiber layer has a gram weight of 20 g / m 2 The core fiber layer has a gram weight of 30g / m 2 .

[0155] The only difference between the preparation method of the multilayer composite fiber sheet of this comparative example and the preparation method of the multilayer composite fiber sheet of Example 1 is that butene-propylene copolymer J is used instead of butene-propylene copolymer A, and the other steps and parameters remain unchanged.

[0156] Comparative Example 2

[0157] This comparative example provides a multilayer composite fiber sheet, comprising (A) two top fiber layers comprising high-density polyethylene A; (B) a core fiber layer comprising a butene-propylene copolymer K; the core fiber layer is disposed between the two top fiber layers; wherein the top fiber layer has a gram weight of 20 g / m 2 The core fiber layer has a gram weight of 30g / m 2 .

[0158] The only difference between the preparation method of the multilayer composite fiber sheet of this comparative example and the preparation method of the multilayer composite fiber sheet of Example 1 is that the butene-propylene copolymer K is used instead of the butene-propylene copolymer A, and the other steps and parameters remain unchanged.

[0159] Comparative Example 3

[0160] This comparative example provides a multi-layer composite fiber sheet, which includes high-density polyethylene A. The weight of the multi-layer composite fiber sheet is 70g / m 2 .

[0161] The only difference between the preparation method of the flash-blown fiber in this comparative example and the preparation method of the multi-layer composite fiber sheet in Example 1 is that high-density polyethylene A is used instead of butene-propylene copolymer A, and the other steps and parameters remain unchanged.

[0162] Performance Testing

[0163] The multilayer composite fiber sheets obtained in the examples and comparative examples were subjected to performance tests, and the test methods were as follows:

[0164] (1) Hydrostatic pressure: refer to ISO 811 standard method and take the average value of 10 samples;

[0165] (2) Opacity: refer to ISO 2471 standard method and take the average value of 10 samples;

[0166] (3) Air permeability: refer to the Gurley method in ISO 5636 standard and take the average value of 10 samples. The smaller the air permeability (s), the better the air permeability.

[0167] (4) Tensile strength: Refer to ISO 13934-1 standard method, test the transverse and longitudinal tensile strength, and take the average value of 5 samples;

[0168] (5) Heat resistance: Simulate the high-pressure steam sterilization conditions, slightly adjust the temperature and time, and keep other conditions unchanged. Set the temperature to 130°C and the time to 30 min and 60 min. Place the multi-layer composite fiber sheet under the above two conditions and observe whether the multi-layer composite fiber sheet shows any changes such as softening and deformation.

[0169] The test results are shown in Table 1.

[0170] Table 1

[0171]

[0172]

[0173] From the experimental data in Table 1, it can be seen that the hydrostatic pressure of the multilayer composite fiber sheet of the present invention is ≥160 cmH2O, the opacity is ≥93%, the air permeability is ≤10s, and the appearance does not change after high-pressure steam sterilization at 130°C for 60 minutes.

[0174] By comparing Example 1, Examples 3-6 and Comparative Examples 1-2, it can be seen that when the difference between the initial melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is greater than 15°C, or the difference between the peak melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is less than 10°C, the hydrostatic pressure of the obtained multi-layer composite fiber sheet is less than 160 cmH2O, the opacity is less than 93%, and the appearance is deformed after high-pressure steam sterilization at a temperature of 130°C for 60 minutes, indicating that when the difference between the initial melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is greater than 15°C, or the difference between the peak melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is less than 10°C, the waterproof performance, opacity and heat resistance of the multi-layer composite fiber sheet will be significantly reduced.

[0175] By comparing Example 1 with Examples 7-10, it can be seen that when the melt flow rate of the butene-propylene copolymer is 0.2-5 g / 10 min, the hydrostatic pressure of the obtained multi-layer composite fiber sheet is ≥180 cmH2O and the opacity is ≥95%, indicating that when the melt flow rate of the butene-propylene copolymer is 0.2-5 g / 10 min, the waterproof performance and opacity of the multi-layer composite fiber sheet are better.

[0176] By comparing Example 1 and Comparative Example 3, it can be seen that the multi-layer composite fiber sheet containing only high-density polyethylene has a hydrostatic pressure of 127 cmH2O, an opacity of 90.5%, and an air permeability of 17s. After high-pressure steam sterilization at a temperature of 130°C for 60 minutes, the appearance is severely deformed, indicating that the present invention adds a core fiber layer containing butene-propylene copolymer to the multi-layer composite fiber sheet, so that the multi-layer composite fiber sheet has good mechanical properties, heat resistance, air permeability, opacity and waterproofness.

[0177] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A multi-layer composite fiber sheet, characterized in that: The invention comprises (A) at least two top fiber layers comprising high-density polyethylene; (B) at least one core fiber layer comprising a butene-propylene copolymer; the core fiber layer being disposed between the at least two top fiber layers; The difference between the initial melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is ≤15°C; The difference between the peak melting temperature of the butene-propylene copolymer and the peak melting temperature of the high-density polyethylene is ≥10°C.

2. The multilayer composite fiber sheet according to claim 1, wherein The molecular weight distribution coefficient of the butene-propylene copolymer is 3-5.

3. The multi-layer composite fiber sheet according to claim 1, wherein The butene-propylene copolymer has a butene-derived unit content of 12-25 wt%, preferably 15-20 wt%; And / or, the butene-propylene copolymer has a melt flow rate of 0.1-10 g / 10 min, preferably 0.2-5 g / 10 min, at 230° C. and 2.16 kg.

4. The multi-layer composite fiber sheet according to claim 1, wherein The butene-propylene copolymer has an initial melting temperature of ≤150°C and a peak melting temperature of ≥145°C.

5. The multi-layer composite fiber sheet according to claim 1, wherein The density of the high-density polyethylene is 0.940-0.970 g / cm 3 , preferably 0.942-0.958 g / cm 3 ; and / or, the high-density polyethylene has a peak melting temperature of 125-140° C., preferably 130-138° C.; And / or, the top fiber layer and the core fiber layer are produced by flash spinning.

6. A method for preparing the multilayer composite fiber sheet according to any one of claims 1 to 5, characterized in that: The following steps are involved: Spinning solutions of high-density polyethylene and butene-propylene copolymer are prepared respectively, and the spinning solutions are spun to obtain fiber layers respectively. The obtained fiber layers are composited to obtain a multi-layer composite fiber sheet.

7. The method for preparing a multi-layer composite fiber sheet according to claim 6, wherein: The following steps are involved: Adding high-density polyethylene to a first autoclave and a third autoclave containing a solvent, heating and dissolving, to obtain a first mixed solution and a third mixed solution; adding a butene-propylene copolymer to a second autoclave containing a solvent, heating and dissolving, to obtain a second mixed solution; Opening the high-pressure control valve between the autoclave and the low-pressure autoclave to allow the first mixed solution to flow into the first low-pressure autoclave, the second mixed solution to flow into the second low-pressure autoclave, and the third mixed solution to flow into the third low-pressure autoclave, heating and dissolving to obtain a first spinning solution, a second spinning solution, and a third spinning solution, respectively; The low-pressure control valve is opened to reduce the pressure, so that the first spinning solution, the second spinning solution and the third spinning solution are spun respectively and received into fiber layers by a receiving device. The obtained fiber layers are cold pressed and hot rolled to obtain a multi-layer composite fiber sheet.

8. The method for preparing a multi-layer composite fiber sheet according to claim 7, wherein: The heating and dissolving conditions of the first autoclave, the second autoclave and the third autoclave are independently: temperature of 150-230°C, pressure of 5-25 MPa, and stirring time of 20-30 min; And / or, the heating and dissolving conditions of the first low-pressure kettle, the second low-pressure kettle and the third low-pressure kettle are independently: pressure of 5-20 MPa, temperature of 150-230° C., and residence time of 15-30 min; and / or, the solvent is at least one of 1,2-dichloroethane, dichloromethane, n-pentane, and cyclohexane; And / or, the mass percentage concentration of high-density polyethylene in the first mixed solution and the third mixed solution is independently 5-25%; And / or, the mass percentage concentration of the butene-propylene copolymer in the second mixed liquid is 5-25%.

9. A product, characterized in that The product contains the multi-layer composite fiber sheet according to any one of claims 1 to 5 or the multi-layer composite fiber sheet prepared by the preparation method according to any one of claims 6 to 8.

10. A medical device protective packaging product, characterized in that: The medical device protective packaging product contains the multi-layer composite fiber sheet according to any one of claims 1 to 5 or the multi-layer composite fiber sheet prepared by the preparation method according to any one of claims 6 to 8.

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