Forming method for improving hardness of spraying polyurethane foam and polyurethane foam

Abstract

The invention discloses a forming method for improving the hardness of spraying polyurethane foam and the polyurethane foam, and relates to the technical field of polyurethane foam product forming. The forming method for improving the hardness of the spraying polyurethane foam comprises the following steps: putting polyether polyol, a first catalyst, a second catalyst, a foam stabilizer and a foaming agent into a batching kettle, stirring at room temperature, and heating in an oil bath to obtain a white material, the polyether polyol is formed by polymerizing a sorbitol compound serving as a composite initiator and epoxypropane; and mixing the white material with polymethylene polyphenyl isocyanate, and carrying out spray molding. The adopted polyether polyol is high-functionality polyether polyol formed by polymerizing a sorbitol compound serving as a composite initiator and epoxypropane, the polyether polyol reacts with isocyanato in PAPI, a new compound with a net structure can be formed, and therefore the foam hardness and mechanical performance are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane foam product molding, and in particular relates to a molding method for improving the hardness of spray polyurethane foam and polyurethane foam. Background Art

[0002] Polyurethane foam spray foaming molding refers to a molding method in which the raw materials of rigid polyurethane foam are directly sprayed onto the surface of an object and foamed on this surface. Spray foam molding can be sprayed on horizontal surfaces, vertical surfaces, top surfaces, simple or complex surfaces, without the need for molds. Spray foam has no joints, good insulation effect and high production efficiency.

[0003] For cylinders with complex surface structures, spray foaming is used. The density of spray polyurethane foam is low, and the mechanical properties are limited, resulting in low hardness. As a result, the feed amount and turning speed are too fast during the machining process, and large pieces of foam will be torn. In order to ensure the flatness of the machined foam surface, the feed amount and turning speed must be reduced, which makes machining difficult and reduces production efficiency. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a method for improving the hardness of spray polyurethane foam and polyurethane foam. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0005] The present invention provides a method for improving the hardness of spray polyurethane foam, comprising:

[0006] Step 1: placing a polyether polyol, a first catalyst, a second catalyst, a foam stabilizer and a foaming agent in a batching kettle, stirring at room temperature and then heating in an oil bath to obtain a white material, wherein the polyether polyol is a polyether polyol obtained by polymerizing propylene oxide with a sorbitol compound as a composite initiator, and the functionality of the polyether polyol is 6, and the hydroxyl value is 0.00839-0.00875 mol / g;

[0007] Step 2: Mix the white material with polymethylene polyphenyl isocyanate and then spray-form.

[0008] In one embodiment of the present invention, the mass ratio of the polyether polyol, the first catalyst, the second catalyst, the foam stabilizer and the foaming agent is 100:3:1:3:(28-32).

[0009] In one embodiment of the present invention, the stirring treatment time is 1.5-2h.

[0010] In one embodiment of the present invention, the heating temperature of the oil bath is 55-65°C.

[0011] In one embodiment of the present invention, the heating time of the oil bath is 1-2 hours.

[0012] In one embodiment of the present invention, the first catalyst is a triethylenediamine solution with a mass concentration of 33%, and the second catalyst is dibutyltin dilaurate.

[0013] In one embodiment of the present invention, the volume ratio of the white material to the polymethylene polyphenyl isocyanate is 1:1.

[0014] In one embodiment of the present invention, the ambient temperature of the spray molding is 20-35° C., and the ambient humidity does not exceed 70%.

[0015] The present invention provides a polyurethane foam, which is prepared by the molding method for improving the hardness of spray polyurethane foam described in any one of the above embodiments.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The method for improving the hardness of spray polyurethane foam of the present invention adopts a high-functionality polyether polyol which is polymerized with propylene oxide using a sorbitol compound as a composite initiator, and the polyether polyol has a high functionality and a hydroxyl value. The polyether polyol reacts with the isocyanate in polymethylene polyphenyl isocyanate (PAPI) to form a new compound with a network structure, thereby improving the hardness of the foam. Secondly, the foam cell structure of the formed foam is evenly distributed and has good density, thereby improving the dimensional stability and mechanical properties of the foam, thereby improving the foam machining efficiency, reducing the production cost, and improving the production efficiency.

[0018] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of a method for improving the hardness of spray polyurethane foam provided by an embodiment of the present invention;

[0020] Figure 2 The present invention provides a process flow chart of a method for improving the hardness of spray polyurethane foam molding. DETAILED DESCRIPTION

[0021] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, a method for improving the hardness of spray polyurethane foam and a polyurethane foam proposed by the present invention are described in detail below in combination with the accompanying drawings and specific implementation methods.

[0022] The above and other technical contents, features and effects of the present invention are clearly presented in the following detailed description of the specific implementation modes in conjunction with the accompanying drawings. Through the description of the specific implementation modes, the technical means and effects adopted by the present invention to achieve the predetermined purpose can be more deeply and specifically understood. However, the attached drawings are only for reference and explanation purposes and are not used to limit the technical solutions of the present invention.

[0023] In the first aspect, the embodiment of the present invention provides a method for improving the hardness of spray polyurethane foam. Figure 1 , Figure 1 Schematic diagram of a method for improving the hardness of spray polyurethane foam provided by an embodiment of the present invention, such as Figure 1 As shown, the method for improving the hardness of spray polyurethane foam of this embodiment comprises:

[0024] Step 1: placing a polyether polyol, a first catalyst, a second catalyst, a foam stabilizer and a foaming agent in a batching kettle, stirring at room temperature and then heating in an oil bath to obtain a white material, wherein the polyether polyol is a polyether polyol obtained by polymerizing propylene oxide with a sorbitol compound as a composite initiator, and the functionality of the polyether polyol is 6, and the hydroxyl value is 0.00839-0.00875 mol / g;

[0025] Step 2: Mix the white material with polymethylene polyphenyl isocyanate and then spray-form.

[0026] The method for improving the hardness of spray polyurethane foam in the embodiment of the present invention uses a polyether polyol with high functionality formed by polymerization of propylene oxide with a sorbitol compound as a composite initiator, and the polyether polyol has a high functionality and hydroxyl value. Compared with the polyether polyol initiator currently used for spray foaming, which is ethane, an oily polyether with low functionality and an average theoretical value of 3, the foam rigidity produced is poor. The polyether polyol used in the embodiment of the present invention reacts with the isocyanate in polymethylene polyphenyl isocyanate to form a new compound with a network structure, thereby improving the foam hardness and improving the foam mechanical properties.

[0027] Polyisocyanate and polyether polyol react to form polyurethane. The chemical reaction is expressed as: According to the different needs of polyurethane foam, polyether polyol and isocyanate reaction of different hydroxyl functionalities can be used to generate the reticulated polymer material of different crosslinking densities, thereby obtain different soft and hard foams.In general, the larger the crosslinking density, the harder the polyurethane foam.So in the present embodiment, the polyether polyol adopted is a high-functionality polyether polyol formed by polymerization of propylene oxide with sorbitol compound as a composite initiator, and the polyether polyol has higher functionality and hydroxyl value.The polyether polyol reacts with the isocyanate radical in polymethylene polyphenyl isocyanate (PAPI), and a new compound of a reticulated structure of a certain crosslinking degree can be formed, thereby improving foam hardness, and secondly the foam cell structure of molding is evenly distributed, and has good compactness, thereby improving the dimensional stability and mechanical properties of foam, and then improving the foam machine efficiency, reducing production costs, and improving production efficiency.

[0028] In an optional embodiment, the mass ratio of the polyether polyol, the first catalyst, the second catalyst, the foam stabilizer and the blowing agent is 100:3:1:3:(28-32). Exemplarily, the mass ratio of the polyether polyol, the first catalyst, the second catalyst, the foam stabilizer and the blowing agent can be any selected value of 100:3:1:3:28, 100:3:1:3:29, 100:3:1:3:30, 100:3:1:3:31 or 100:3:1:3:32.

[0029] In an optional embodiment, the stirring treatment time is 1.5-2 hours. Exemplarily, the stirring treatment time can be any selected value of 1.5 hours, 1.8 hours or 2 hours.

[0030] In this embodiment, the stirring time is controlled to ensure that the materials in the white material are fully mixed.

[0031] In an optional embodiment, the heating temperature of the oil bath is 55-65° C. Exemplarily, the heating temperature of the bath can be any selected value of 55° C., 60° C. or 65° C.

[0032] In an optional embodiment, the heating time of the oil bath is 1-2 hours. Exemplarily, the heating time of the oil bath can be any selected value of 1 hour, 1.5 hours or 2 hours.

[0033] It should be noted that, in this embodiment, the stirring process is performed while heating in an oil bath, and the white material is prepared by heating and stirring in an oil bath in a batching kettle to the use temperature, i.e., 45-50°C, which can ensure the uniformity of the material-liquid mixing temperature.

[0034] In an optional embodiment, the first catalyst is a triethylenediamine solution with a mass concentration of 33%, and the second catalyst is dibutyltin dilaurate.

[0035] In an optional embodiment, the volume ratio of the white material to polymethylene polyphenyl isocyanate (PAPI) is 1: 1. In this embodiment, by controlling the volume ratio of the white material to PAPI to 1: 1, the network molecular structure of the foam can be optimized, which is beneficial to improving the hardness and compression strength of the foam structure, and improving the dimensional stability and temperature resistance.

[0036] In an optional embodiment, the ambient temperature of the spray molding is 20-35° C., and the ambient humidity does not exceed 70%.

[0037] In an optional embodiment, the white material is mixed with polymethylene polyphenyl isocyanate and then sprayed to form the mixture, which may include the following steps:

[0038] First, the white material is placed in the white material tank of the foaming spraying equipment, and the polymethylene polyphenyl isocyanate is placed in the PAPI material tank of the foaming spraying equipment. Then the first material pump is inserted into the white material tank, the second material pump is inserted into the PAPI material tank, and the foaming machine spraying equipment is started, so that the white material and polymethylene polyphenyl isocyanate enter the mixing chamber of the foaming machine spraying equipment under high pressure, and are fully mixed in a volume ratio of 1:1. Finally, the mixed white material and polymethylene polyphenyl isocyanate are sprayed onto the surface of the workpiece using a spray gun to form a foam structure.

[0039] The method for improving the hardness of spray polyurethane foam molding in the embodiment of the present invention adopts a high-functionality polyether polyol formed by polymerization of propylene oxide with a sorbitol compound as a composite initiator, a first catalyst, a second catalyst, a foam stabilizer and a foaming agent as a new foam molding formula system. Compared with the existing foam molding formula system, the foam molded by the present invention has a uniformly distributed pore structure and good density, thereby improving the dimensional stability and mechanical properties of the foam, thereby improving the foam machining efficiency, reducing production costs, and improving production efficiency.

[0040] In a second aspect, an embodiment of the present invention provides a polyurethane foam, which is prepared by the molding method for improving the hardness of spray polyurethane foam provided in the first aspect.

[0041] Regarding the specific molding process of the polyurethane foam and the corresponding beneficial effects, please refer to the relevant content of the method for improving the hardness of spray polyurethane foam provided in the first aspect, which will not be elaborated here.

[0042] For further information, see Figure 2 , Figure 2 is a process flow chart of a method for improving the hardness of spray polyurethane foam provided by an embodiment of the present invention, which is combined with Figure 2The specific embodiments clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In the following examples, the polyether polyol is a polyether polyol with a functionality of 6 and a hydroxyl value of 0.00839 mol / g, which is prepared by polymerization of propylene oxide with a sorbitol compound as a composite initiator. The first catalyst is a triethylenediamine solution with a mass concentration of 33%, and the second catalyst is dibutyltin dilaurate.

[0044] Example 1

[0045] Step 1: Weigh the polyether polyol, the first catalyst, the second catalyst, the foam stabilizer and the foaming agent in a mass ratio of 100:3:1:3:28.

[0046] Step 2: Place the weighed ingredients in a batching kettle and stir evenly at room temperature for 1.5 hours.

[0047] Step 3: Turn on the oil bath heating in the batching kettle. The heating temperature of the oil bath is 55°C and heat for 2 hours to make the material temperature in the batching kettle reach the use temperature of 50°C to obtain white material.

[0048] Step 4: Place the white material in the white material tank of the foaming spray equipment, and place the polymethylene polyphenyl isocyanate in the PAPI material tank of the foaming spray equipment.

[0049] Step 5: Insert the white material metering pump into the white material tank, insert the PAPI metering pump into the PAPI material tank, start the foaming machine spraying equipment, and use the metering pump to pump the white material and polymethylene polyphenyl isocyanate into the mixing chamber of the foaming machine spraying equipment in a volume ratio of 1:1 for full mixing.

[0050] Step 6: Compressed air enters the mixing chamber through the air filter. Under the conditions of an ambient temperature of 25°C and an ambient humidity of 70%, the mixed white material and polymethylene polyphenyl isocyanate are sprayed onto the surface of the workpiece through a spray gun to form a foam structure.

[0051] Example 2

[0052] Step 1: Weigh the polyether polyol, the first catalyst, the second catalyst, the foam stabilizer and the foaming agent in a mass ratio of 100:3:1:3:29.

[0053] Step 2: Place the weighed ingredients in a batching kettle and stir evenly at room temperature for 1.5 hours.

[0054] Step 3: Turn on the oil bath heating in the batching kettle. The heating temperature of the oil bath is 55°C and heat for 2 hours to make the material temperature in the batching kettle reach the use temperature of 50°C to obtain white material.

[0055] Step 4: Place the white material in the white material tank of the foaming spray equipment, and place the polymethylene polyphenyl isocyanate in the PAPI material tank of the foaming spray equipment.

[0056] Step 5: Insert the white material metering pump into the white material tank, insert the PAPI metering pump into the PAPI material tank, start the foaming machine spraying equipment, and use the metering pump to pump the white material and polymethylene polyphenyl isocyanate into the mixing chamber of the foaming machine spraying equipment in a volume ratio of 1:1 for full mixing.

[0057] Step 6: Compressed air enters the mixing chamber through the air filter. Under the conditions of an ambient temperature of 25°C and an ambient humidity of 70%, the mixed white material and polymethylene polyphenyl isocyanate are sprayed onto the surface of the workpiece through a spray gun to form a foam structure.

[0058] Example 3

[0059] Step 1: Weigh the polyether polyol, the first catalyst, the second catalyst, the foam stabilizer and the foaming agent in a mass ratio of 100:3:1:3:30.

[0060] Step 2: Place the weighed ingredients in a batching kettle and stir evenly at room temperature for 1.8 hours.

[0061] Step 3: Turn on the oil bath heating of the batching kettle. The heating temperature of the oil bath is 60°C and heat for 1.5 hours to make the temperature of the material in the batching kettle reach the use temperature of 50°C to obtain white material.

[0062] Step 4: Place the white material in the white material tank of the foaming spray equipment, and place the polymethylene polyphenyl isocyanate in the PAPI material tank of the foaming spray equipment.

[0063] Step 5: Insert the white material metering pump into the white material tank, insert the PAPI metering pump into the PAPI material tank, start the foaming machine spraying equipment, and use the metering pump to pump the white material and polymethylene polyphenyl isocyanate into the mixing chamber of the foaming machine spraying equipment in a volume ratio of 1:1 for full mixing.

[0064] Step 6: Compressed air enters the mixing chamber through the air filter. Under the conditions of an ambient temperature of 25°C and an ambient humidity of 70%, the mixed white material and polymethylene polyphenyl isocyanate are sprayed onto the surface of the workpiece through a spray gun to form a foam structure.

[0065] Example 4

[0066] Step 1: Weigh the polyether polyol, the first catalyst, the second catalyst, the foam stabilizer and the foaming agent in a mass ratio of 100:3:1:3:32.

[0067] Step 2: Place the weighed ingredients in a batching kettle and stir evenly at room temperature for 2 hours.

[0068] Step 3: Turn on the oil bath heating in the batching kettle. The heating temperature of the oil bath is 65°C and heat for 1 hour so that the temperature of the material in the batching kettle reaches the use temperature of 50°C to obtain a white material.

[0069] Step 4: Place the white material in the white material tank of the foaming spray equipment, and place the polymethylene polyphenyl isocyanate in the PAPI material tank of the foaming spray equipment.

[0070] Step 5: Insert the white material metering pump into the white material tank, insert the PAPI metering pump into the PAPI material tank, start the foaming machine spraying equipment, and use the metering pump to pump the white material and polymethylene polyphenyl isocyanate into the mixing chamber of the foaming machine spraying equipment in a volume ratio of 1:1 for full mixing.

[0071] Step 6: Compressed air enters the mixing chamber through the air filter. Under the conditions of an ambient temperature of 25°C and an ambient humidity of 70%, the mixed white material and polymethylene polyphenyl isocyanate are sprayed onto the surface of the workpiece through a spray gun to form a foam structure.

[0072] Comparative Example 1 to Comparative Example 4

[0073] The foam structure was prepared according to the method of Example 1, except that the polyether polyol was a low-functionality polyether polyol with a functionality of 3 using ethane as an initiator. In Comparative Examples 1 to 4, the mass ratios of the polyether polyol, the first catalyst, the second catalyst, the foam stabilizer and the foaming agent were 100:3:1:3:28, 100:3:1:3:29, 100:3:1:3:30 and 100:3:1:3:32, respectively.

[0074] The performance parameters of the polyurethane foams obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were tested. The test results are shown in Table 1. It can be seen from Table 1 that the performance of the polyurethane foam prepared with high-functionality polyether polyols is significantly better than that of the polyurethane foam prepared with low-functionality polyether polyols.

[0075] Table 1

[0076]

[0077]

[0078] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant is intended to cover non-exclusive inclusion, so that the article or device including a series of elements includes not only those elements, but also other elements that are not explicitly listed. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the article or device including the elements. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The orientation or position relationship indicated by "up", "down", "left", "right", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0079] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for improving the hardness of spray polyurethane foam, characterized in that: include: Step 1: placing a polyether polyol, a first catalyst, a second catalyst, a foam stabilizer and a foaming agent in a batching kettle, stirring at room temperature and then heating in an oil bath to obtain a white material, wherein the polyether polyol is a polyether polyol obtained by polymerizing propylene oxide with a sorbitol compound as a composite initiator, and the functionality of the polyether polyol is 6, and the hydroxyl value is 0.00839-0.00875 mol / g; Step 2: Mix the white material with polymethylene polyphenyl isocyanate and then spray-form.

2. The method for improving the hardness of spray polyurethane foam according to claim 1, characterized in that: The mass ratio of the polyether polyol, the first catalyst, the second catalyst, the foam stabilizer and the foaming agent is 100:3:1:3:(28-32).

3. The method for improving the hardness of spray polyurethane foam according to claim 1, characterized in that: The stirring time is 1.5-2h.

4. The method for improving the hardness of spray polyurethane foam according to claim 1, characterized in that: The heating temperature of the oil bath is 55-65°C.

5. The method for improving the hardness of spray polyurethane foam according to claim 1, characterized in that: The heating time of the oil bath is 1-2h.

6. The method for improving the hardness of spray polyurethane foam according to claim 1, characterized in that: The first catalyst is a triethylenediamine solution with a mass concentration of 33%, and the second catalyst is dibutyltin dilaurate.

7. The method for improving the hardness of spray polyurethane foam according to claim 1, characterized in that: The volume ratio of the white material to the polymethylene polyphenyl isocyanate is 1:

1.

8. The method for improving the hardness of spray polyurethane foam according to claim 1, characterized in that: The ambient temperature of the spray molding is 20-35° C., and the ambient humidity does not exceed 70%.

9. A polyurethane foam, characterized in that: The polyurethane foam is prepared by the method for improving the hardness of spray polyurethane foam according to any one of claims 1 to 8.

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