High and low temperature resistant thermoplastic thermoplastic vulcanizate (TPV) and application thereof

Abstract

The invention discloses a high and low temperature resistant thermoplastic thermoplastic vulcanizate (TPV) and application thereof. The thermoplastic TPV comprises ethylene propylene diene monomer, polypropylene, a softening agent, an antioxidant, modified fluoroplastic, fluoroplastic master batch, sodium bicarbonate and a cross-linking agent, wherein the modified fluoroplastic is prepared from a modifier, a grafting agent, hydroxyl polyhedral oligomeric silsesquioxane and a fluorine monomer. A grafting agent containing unsaturated double bonds and fluoroplastic are subjected to an addition reaction, triazine and polyhedral oligomeric silsesquioxane functional groups are introduced, and the temperature resistance and mechanical strength of the material are remarkably improved. The TPV provided by the invention has excellent high and low temperature resistance, tensile strength and elongation at break, and good compression set and brittleness temperature performance.

Description

Technical Field

[0001] The present invention relates to the technical field of TPV composite materials, and in particular to a high and low temperature resistant thermoplastic TPV and applications thereof. Background Art

[0002] With the continuous advancement of industrial technology and the development of materials science, TPV has been widely used in many fields such as automobiles, construction, and medical treatment due to its excellent physical properties and processing convenience. TPV is a polymer composite material prepared by dynamic vulcanization technology. It has both the thermoplasticity of plastics and the elasticity of rubber, and can maintain good performance in a wide temperature range.

[0003] However, the performance of existing TPV materials in extreme temperature environments still needs to be improved. Especially under high and low temperature alternating working conditions, the temperature resistance, mechanical strength and aging resistance of traditional TPV materials often cannot meet the increasingly stringent industrial needs. For example, in the fields of sealing strips in the automotive industry and door and window seals in the construction industry, the material needs to maintain the stability of shape and performance at high temperatures, while still maintaining good elasticity and flexibility at low temperatures.

[0004] In addition, the existing preparation methods of TPV materials also have certain limitations. Traditional preparation processes often require complex equipment and multi-step chemical reactions, which not only increases production costs, but also limits the further improvement of material performance. Therefore, developing a new type of high and low temperature resistant thermoplastic TPV material and its preparation method to improve the material's temperature resistance and mechanical strength has become a goal of exploration.

[0005] CN112745653A discloses modified polyphenylene ether and halogen-free flame-retardant TPV, their preparation methods and applications, and compositions for preparing halogen-free flame-retardant TPV, wherein polyphenylene ether, impact-resistant polystyrene, polybutene-1, and oil-filled SEBS are added to an extruder for plasticization and extrusion granulation. The modified polyphenylene ether provided by the invention has high physical and mechanical properties and good flame retardant properties, and the use of the modified polyphenylene ether can improve the mechanical and flame retardant properties of halogen-free flame-retardant TPV. However, the TPV prepared by the invention has a short service life in extreme temperature environments.

[0006] CN111057306A discloses a TPV composition and a preparation method thereof, comprising 30-40 parts of polypropylene, 20-30 parts of EPDM rubber, 20-30 parts of plasticizer, 10-20 parts of filler, 0.2-1 parts of lubricant, 0.2-1 parts of crosslinking agent, 0.5-2 parts of co-crosslinking agent, 0.3-0.5 parts of antioxidant and 1-5 parts of porous adsorbent. In the invention, special additives are added to the formula, so that the prepared TPV composition has high encapsulation bonding strength. However, the mechanical strength of the TPV prepared by the invention is not high. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to improve the high and low temperature resistance and mechanical properties of thermoplastic TPV.

[0008] To achieve the above-mentioned purpose, the present invention provides a high and low temperature resistant thermoplastic TPV, which comprises the following components, in parts by weight: 20-40 parts of EPDM rubber, 30-60 parts of polypropylene, 1-3 parts of softener, 2-5 parts of antioxidant, 10-30 parts of modified fluoroplastic, 10-40 parts of fluoroplastic masterbatch, 1-4 parts of sodium bicarbonate and 1-5 parts of cross-linking agent; the modified fluoroplastic is prepared from a modifier, a grafting agent, a hydroxyl polyhedral cage silsesquioxane and a fluorine monomer.

[0009] Preferably, the method for preparing the modified fluoroplastic comprises the following steps:

[0010] S1: dissolving the modifier in a solvent, stirring evenly, adding hydroxyl polyhedral cage silsesquioxane, heating to 90-100°C, adding a palladium catalyst, stirring evenly, filtering, washing, drying, and cooling to room temperature to obtain a triazine-POSS nanohybrid material;

[0011] S2: Mix water, dispersant and trifluorotrichloroethane evenly, add grafting agent, introduce inert gas to a pressure of 1-2MPa and maintain for 30-60min, then evacuate to 0.02-0.09MPa, add triazine-POSS nanohybrid material; add fluorine monomer to a pressure of 1-2MPa, heat to 80-100°C, add sodium persulfate, stir at 300-500rpm for 2-6h, and finally obtain modified fluoroplastic.

[0012] More preferably, the method for preparing the modified fluoroplastic comprises the following steps, in parts by weight:

[0013] S1: dissolving 20-50 parts by weight of a modifier in 500-2000 parts of chloroform, stirring at 300-500 rpm for 30-60 min, adding 20-45 parts of a hydroxyl polyhedral cage silsesquioxane, heating to 90-100° C. and stirring for 20-40 min, then adding 0.1-0.4 parts of a palladium catalyst, stirring at 300-500 rpm at 90-100° C. for 7-10 h, filtering, washing, drying at 50-70° C. for 12-24 h, and cooling to room temperature to obtain a triazine-POSS nanohybrid material;

[0014] S2: 50-70 parts of water, 10-20 parts of ammonium perfluorobutylsulfonate and 10-30 parts of trifluorotrichloroethane are mixed at 200-400rpm for 5-10min, 8-15 parts of grafting agent are added, inert gas is introduced to a pressure of 1-2MPa and maintained for 30-60min, then vacuumed to 0.02-0.09MPa, 30-50 parts of triazine-POSS nano hybrid material are added; 80-150 parts of fluorine monomer are added to a pressure of 1-2MPa, the temperature is raised to 80-100°C, 0.1-0.4 parts of sodium persulfate are added, and the mixture is stirred at 300-500rpm for 2-6h to finally obtain modified fluoroplastics.

[0015] Preferably, the modifier is any one of 2,4-diamino-6-isopropenyl-1,3,5-triazine, 6-vinyl-1,3,5-triazine-2,4-diamine and 2,4-diamino-6-phenylvinyl-s-triazine.

[0016] More preferably, the modifier is 2,4-diamino-6-phenylvinyl-s-triazine.

[0017] Preferably, the grafting agent is any one of N-methyl-N,N,N-tripropylene ammonium chloride, dimethyl-bis(2-propylene)ammonium chloride and [(oxiran-2-yl)methyl]bis(propylene-2-en-1-yl)amine.

[0018] Preferably, the dispersant is any one of ammonium perfluorobutylsulfonate and ammonium perfluorohexane-1-sulfonate.

[0019] Preferably, the antioxidant is any one of a bisphenol A antioxidant, a phosphate antioxidant, and an amine antioxidant.

[0020] A method for preparing a high and low temperature resistant thermoplastic TPV comprises the following steps, measured in parts by weight:

[0021] Step 1: 20-40 parts of EPDM rubber, 30-60 parts of polypropylene, 1-3 parts of softener, and 2-5 parts of antioxidant are mixed at 3000 rpm for 10 minutes, kneaded in a kneader, and then extruded and granulated by a screw extruder to obtain a mixture A;

[0022] Step 2: Evenly mix 10-30 parts of modified fluoroplastic, 10-40 parts of fluoroplastic masterbatch, 1-4 parts of sodium bicarbonate and 1-5 parts of cross-linking agent to obtain a mixture B;

[0023] Step 3: Extrude mixture A and mixture B in a mass ratio of (20-50):100, perform vulcanization and foaming, and finally obtain a high and low temperature resistant thermoplastic TPV.

[0024] The present invention also provides an application of high and low temperature resistant thermoplastic TPV in automobiles, wires and cables, and building materials.

[0025] Technical conception:

[0026] Fluorine has extremely high thermal stability, and the addition of fluorine can significantly improve the high and low temperature resistance of TPV materials. This enables TPV to maintain its physical and chemical properties over a wider temperature range and is suitable for extreme temperature environments. However, the direct addition of fluorine may not be well compatible with other components in TPV, resulting in uneven material properties. Therefore, through modification, the compatibility of fluorine with other components can be improved, thereby ensuring the uniformity and consistency of the material. In the process of fluoroplastic modification, by using a grafting agent containing an unsaturated double bond, an addition reaction can be carried out with the fluoroplastic, thereby chemically combining triazine and polyhedral cage silsesquioxane functional groups with the fluoroplastic. This combination method effectively prevents the migration of functional groups in TPV composites, thereby ensuring the stability of material properties. The introduction of triazine and polyhedral cage silsesquioxane functional groups has a significant effect on improving the performance of TPV composites. First, these functional groups enhance the high and low temperature resistance of the material, allowing TPV composites to maintain their physical and chemical properties over a wider temperature range. Secondly, the special nano-hybrid cage structure of polyhedral cage silsesquioxane forms cross-links in fluoroplastics, which significantly improves the mechanical properties of TPV composites. The nano-size and rigid structure of polyhedral cage silsesquioxane provide additional support for TPV, enhancing the strength and toughness of the material. In addition, the introduction of triazine rings also provides additional stability and rigidity to TPV composites. This structural enhancement helps to improve the material's resistance to stress, thereby improving the mechanical properties of TPV. In general, by introducing triazine and polyhedral cage silsesquioxane functional groups on fluoroplastics, not only the temperature resistance of TPV composites is improved, but also its mechanical strength and toughness are significantly enhanced.

[0027] In this recipe, the ingredients and their functions are as follows:

[0028] The modifier contains an amine functional group and a triazine functional group, wherein the amine functional group can react with a hydroxyl functional group in a polyhedral cage-type silsesquioxane functional group to form a triazine-POSS nano-hybrid material.

[0029] Polyhedral cage silsesquioxane reacts with modifiers to form nano-hybrid materials, which enhance the material's temperature resistance and mechanical properties. The special nano-hybrid cage structure of polyhedral cage silsesquioxane forms cross-links in fluoroplastics, providing additional support and enhancing the material's strength and toughness.

[0030] The grafting agent contains double bonds that can undergo addition reactions with fluoroplastics, thereby chemically combining triazine functional groups and polyhedral cage-type silsesquioxane functional groups with fluoroplastics. This combination helps to improve the high and low temperature resistance and mechanical strength of the material.

[0031] Beneficial effects of the present invention:

[0032] 1. Compared with the prior art, the present invention significantly improves the high and low temperature resistance of TPV composite materials by introducing triazine and polyhedral cage-type silsesquioxane functional groups into fluoroplastics. This structural enhancement enables TPV composite materials to maintain their physical and chemical properties in a wider temperature range, thereby maintaining good performance in extreme temperature environments.

[0033] 2. Compared with the prior art, the TPV composite material of the present invention has significantly enhanced mechanical properties, including higher tensile strength, elongation at break and lower compression permanent deformation, because the nanometer size and rigid structure of the polyhedral cage silsesquioxane provide additional support for TPV, and the rigid structure of the triazine ring provides additional stability and rigidity for the material, so that the material has better resistance and durability under stress. DETAILED DESCRIPTION

[0034] Parameters for specific chemical substances used, sources.

[0035] (9ci)-4,6-Diethylene-1,3,5-thiazin-2-amine, 1,3,5-Triazin-2-amine, 4,6-diethenyl-, CAS number: 149037-13-8.

[0036] 2,4-diamino-6-isopropenyl-1,3,5-triazine, CAS No.: 3194-71-6.

[0037] 6-ethenyl-1,3,5-triazine-2,4-diamine, CAS No.: 27154-03-6.

[0038] 2,4-Diamino-6-styryl-s-triazine, CAS No.: 7501-72-6.

[0039] 2-Propen-1-aminium, N-methyl-N,N-di-2-propen-1-yl-, chloride (1:1), CAS No.: 26848-70-4.

[0040] Dimethyl-bis(prop-2-enyl)azanium chloride, CAS No.: 847780-23-8.

[0041] [(Oxiran-2-yl)methyl]bis(prop-2-en-1-yl)amine,

[0042] N,N-diallylglycidylamine, CAS number: 16719-00-9.

[0043] Antioxidant Irganox 107, BASF.

[0044] Fluoroplastic masterbatch, Product No.: FE 350LC, Solvay.

[0045] EPDM rubber, brand: 3745P, DowDuPont.

[0046] Polypropylene, brand: PPB-M02-V (K8003), Yangzi Petrochemical.

[0047] Palladium catalyst, product number: 96-4650, Beijing Bailingwei Technology Co., Ltd.

[0048] Example 1

[0049] A method for preparing a high and low temperature resistant thermoplastic TPV comprises the following steps:

[0050] Step 1: 30 parts by weight of EPDM rubber, 50 parts by weight of polypropylene, 3 parts by weight of paraffin oil and 5 parts by weight of antioxidant Irganox 107 were mixed at 3000 rpm for 10 min, kneaded in a kneader, and then extruded and granulated by a screw extruder to obtain a mixture A;

[0051] Step 2: 10 parts by weight of modified fluoroplastic, 20 parts by weight of fluoroplastic masterbatch, 2 parts by weight of sodium bicarbonate and 4 parts by weight of benzoyl peroxide were mixed at 3000 rpm for 10 min to obtain a mixture B;

[0052] Step 3: Mixture A and mixture B are passed through a twin-screw extruder at a mass ratio of 40:100, and dynamically vulcanized and foamed at 220°C; finally, a high-elastic TPV composite material is obtained through a pelletizer.

[0053] Wherein, the preparation method of the modified fluoroplastic comprises the following steps:

[0054] S1: 30 parts by weight of 2,4-diamino-6-phenylvinyl-s-triazine were dissolved in 1000 parts by weight of chloroform, and stirred at 300 rpm for 30 min, 30 parts by weight of trisiloxyphenyl cage silsesquioxane were added, and the mixture was heated to 90° C. and stirred at 300 rpm for 20 min, and then 0.2 parts by weight of palladium catalyst were added, and the mixture was stirred at 300 rpm at 90° C. for 7 h, and filtered to obtain a filter residue, which was washed once with water, dried at 50° C. for 12 h, and cooled to 25° C. to obtain a triazine-POSS nanohybrid material;

[0055] S2: 60 parts by weight of water, 18 parts by weight of ammonium perfluorobutylsulfonate and 25 parts by weight of trifluorotrichloroethane were mixed at 200 rpm for 10 min, 10 parts by weight of [(oxirane-2-yl)methyl]bis(propylene-2-ene-1-yl)amine were added, nitrogen was introduced to a pressure of 2 MPa and maintained for 30 min, then vacuumed to 0.07 MPa, 40 parts by weight of triazine-POSS nanohybrid material were added; 100 parts by weight of tetrafluoroethylene monomer were added to a pressure of 2 MPa, the temperature was raised to 100° C., 0.15 parts by weight of sodium persulfate were added, and the mixture was stirred at 300 rpm for 4 h to finally obtain a modified fluoroplastic.

[0056] Example 2

[0057] The difference between Example 2 of the present application and Example 1 is that the [(ethylene oxide-2-yl)methyl]bis(propylene-2-en-1-yl)amine in Example 1 is replaced by N-methyl-N,N,N-tripropylene ammonium chloride.

[0058] Example 3

[0059] The difference between Example 3 of the present application and Example 1 is that the [(oxiran-2-yl)methyl]bis(propylene-2-en-1-yl)amine in Example 1 is replaced by dimethyl-bis(2-propylene)ammonium chloride.

[0060] Example 4

[0061] The difference between Example 4 of the present application and Example 1 is that the 2,4-diamino-6-phenylvinyl-s-triazine in Example 1 is replaced by 2,4-diamino-6-isopropenyl-1,3,5-triazine.

[0062] Example 5

[0063] The difference between Example 5 of the present application and Example 1 is that the 2,4-diamino-6-phenylvinyl-s-triazine in Example 1 is replaced by 6-vinyl-1,3,5-triazine-2,4-diamine.

[0064] Comparative Example 1

[0065] The difference between Comparative Example 1 of the present application and Example 1 is that the [(oxiran-2-yl)methyl]bis(propylene-2-en-1-yl)amine in Example 1 is replaced by diallyl diethylammonium chloride.

[0066] Comparative Example 2

[0067] The difference between Comparative Example 2 of the present application and Example 1 is that the 2,4-diamino-6-phenylvinyl-s-triazine in Example 1 is replaced by (9ci)-4,6-diethylene-1,3,5-thiazin-2-amine.

[0068] Test Example 1

[0069] Tensile strength and elongation at break: tested in accordance with GB / T 528-2009 “Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber”.

[0070] Hot air aging: Test in accordance with GB / T 7141-2008 "Test methods for thermal aging of plastics".

[0071] Compression set: Tested in accordance with GB / T 1040.1-2018 "Determination of tensile properties of plastics Part 1: General principles".

[0072] Brittle temperature: Tested in accordance with GB / T 1682-2014 "Single specimen method for determination of low temperature brittleness of vulcanized rubber". See Table 1 for test results:

[0073] Table 1 Mechanical and temperature resistance test results

[0074]

[0075]

[0076] Comparing the tabular data in Examples 1-3 and Comparative Example 1, it is found that the mechanical properties of the high and low temperature resistant thermoplastic TPV prepared in Example 1 are the best. The possible reason is that different grafting agents are used. In the present invention, triazine and polyhedral cage-type silsesquioxane functional groups are introduced into the molecular chain of fluoroplastics through the reaction of the grafting agent with the fluorinated monomer and the triazine-POSS nano-hybrid material, thereby improving the compatibility of the dispersed phase of other raw materials such as silicone rubber and fluoroplastics. Compared with the grafting agents in Examples 1-3 and Comparative Example 1, the grafting agent in Example 1 contains epoxy groups in addition to the double bonds involved in the reaction. The epoxy group can react with the amino group contained in the modifier and the hydroxyl group contained in the polyhedral cage-type silsesquioxane functional group, which increases the crosslinking density of the TPV material. Higher crosslinking density generally means better mechanical properties, including higher strength and toughness. The epoxy group further reacts as a compatibilizer to improve the compatibility between different polymer components, which is beneficial to improving the stability of the TPV material. The grafting agent used in Examples 2-3 and Comparative Example 1 does not contain an epoxy group, so the cross-linking density of the prepared TPV material is lower, so the mechanical performance is worse, and the service life is lower when encountering a high and low temperature environment. At low temperatures, the triazine-POSS nano hybrid material and the rigid structure help to maintain the flexibility and anti-embrittlement ability of the material, thereby improving the low temperature resistance of TPV. Therefore, the high and low temperature resistance of the TPV material prepared in Example 1 is better.

[0077] Comparing the tabular data in Example 1, Example 4-5 and Comparative Example 1, it is found that the mechanical properties of the high and low temperature resistant thermoplastic TPV prepared in Example 1 are the best. The possible reason is that different modifiers are used. In addition to containing an amino functional group that can react with the hydroxyl group in the polyhedral cage-type silsesquioxane, the modifier in Example 1 also contains a rigid benzene ring structure. The rigid structure of the benzene ring plays a role in strengthening the internal skeleton of the material in TPV, improving the rigidity and strength of the material. At the same time, the stability and rigidity of the benzene ring help to maintain the shape and structure of the TPV at high temperatures, thereby improving the heat resistance of the material, so that the TPV material can still maintain good stability in a high temperature environment, showing excellent high temperature resistance. In Examples 4-5 and Comparative Example 2, because the modifier used only contains an amino functional group and does not contain a rigid large benzene ring structure, the mechanical properties of the prepared TPV material are worse.

Claims

1. A high and low temperature resistant thermoplastic TPV, characterized in that: The invention comprises the following components in parts by weight: 20-40 parts of EPDM rubber, 30-60 parts of polypropylene, 1-3 parts of softener, 2-5 parts of antioxidant, 10-30 parts of modified fluoroplastic, 10-40 parts of fluoroplastic masterbatch, 1-4 parts of sodium bicarbonate and 1-5 parts of crosslinking agent; the modified fluoroplastic is prepared from the modifier, grafting agent, hydroxyl polyhedral cage silsesquioxane and fluorine monomer.

2. The high and low temperature resistant thermoplastic TPV according to claim 1, characterized in that: The preparation method of the modified fluoroplastic comprises the following steps: S1: dissolving the modifier in a solvent, stirring evenly, adding hydroxyl polyhedral cage silsesquioxane, heating to 90-100°C, adding a palladium catalyst, stirring evenly, filtering, washing, drying, and cooling to room temperature to obtain a triazine-POSS nanohybrid material; S2: Mix water, dispersant and trifluorotrichloroethane evenly, add grafting agent, introduce inert gas to a pressure of 1-2MPa and maintain for 30-60min, then evacuate to 0.02-0.09MPa, and add triazine-POSS nanohybrid material; Fluorine monomer is introduced to a pressure of 1-2 MPa, the temperature is raised to 80-100°C, sodium persulfate is added, and the mixture is stirred at 300-500 rpm for 2-6 hours to finally obtain modified fluoroplastics.

3. The high and low temperature resistant thermoplastic TPV according to claim 2, characterized in that: The preparation method of the modified fluoroplastic comprises the following steps, calculated in parts by weight: S1: dissolving 20-50 parts of the modifier in 500-2000 parts of chloroform, stirring at 300-500 rpm for 30-60 min, adding 20-45 parts of hydroxyl polyhedral cage silsesquioxane, heating to 90-100° C. and stirring for 20-40 min, then adding 0.1-0.4 parts of palladium catalyst, stirring at 300-500 rpm at 90-100° C. for 7-10 h, filtering, washing, drying at 50-70° C. for 12-24 h, and cooling to room temperature to obtain triazine-POSS nanohybrid material; S2: 50-70 parts of water, 10-20 parts of ammonium perfluorobutylsulfonate and 10-30 parts of trifluorotrichloroethane are mixed at 200-400rpm for 5-10min, 8-15 parts of grafting agent are added, inert gas is introduced to a pressure of 1-2MPa and maintained for 30-60min, then vacuumed to 0.02-0.09MPa, 30-50 parts of triazine-POSS nano hybrid material are added; 80-150 parts of fluorine monomer are added to a pressure of 1-2MPa, the temperature is raised to 80-100°C, 0.1-0.4 parts of sodium persulfate are added, and the mixture is stirred at 300-500rpm for 2-6h to finally obtain modified fluoroplastics.

4. The high and low temperature resistant thermoplastic TPV according to claim 1, characterized in that: The modifier is any one of 2,4-diamino-6-isopropenyl-1,3,5-triazine, 6-vinyl-1,3,5-triazine-2,4-diamine and 2,4-diamino-6-phenylvinyl-s-triazine.

5. The high and low temperature resistant thermoplastic TPV according to claim 4, characterized in that: The modifier is 2,4-diamino-6-phenylvinyl-s-triazine.

6. The high and low temperature resistant thermoplastic TPV according to claim 1, characterized in that: The grafting agent is any one of N-methyl-N,N,N-tripropylene ammonium chloride, dimethyl-bis(2-propylene)ammonium chloride and [(oxiran-2-yl)methyl]bis(propylene-2-en-1-yl)amine.

7. The high and low temperature resistant thermoplastic TPV according to claim 1, characterized in that: The dispersant is any one of ammonium perfluorobutylsulfonate and ammonium perfluorohexane-1-sulfonate.

8. The high and low temperature resistant thermoplastic TPV according to claim 1, characterized in that: The antioxidant is any one of bisphenol A type antioxidant, phosphate antioxidant and amine antioxidant.

9. The method for preparing a high and low temperature resistant thermoplastic TPV according to any one of claims 1 to 8, characterized in that: The method comprises the following steps, in parts by weight: Step 1: 20-40 parts of EPDM rubber, 30-60 parts of polypropylene, 1-3 parts of softener, and 2-5 parts of antioxidant are mixed at 3000 rpm for 10 minutes, kneaded in a kneader, and then extruded and granulated by a screw extruder to obtain a mixture A; Step 2: Evenly mix 10-30 parts of modified fluoroplastic, 10-40 parts of fluoroplastic masterbatch, 1-4 parts of sodium bicarbonate and 1-5 parts of cross-linking agent to obtain mixture B; Step 3: Extrude mixture A and mixture B in a mass ratio of (20-50):100, perform vulcanization and foaming, and finally obtain a high and low temperature resistant thermoplastic TPV.

10. Application of the high and low temperature resistant thermoplastic TPV according to any one of claims 1 to 8 in automobiles, wires and cables, and building materials.

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