Polyvinyl Butyral Resin (PVB) is a solvent Resin synthesized by the acetal reaction of Polyvinyl Alcohol (PVA) and butyraldehyde in contact with coal.
Because Pvb Resin itself contains a lot of hydroxyl groups, it can bridge with some thermosetting resins to improve the properties of chemicals and film hardness.
Because PVB resin has the above excellent characteristics, it is widely used in adhesive safety glass intermediate film of automobile and building, rust cutting primer, baking paint, wood paint, printing ink, adhesive of electronic ceramics and printed circuit board, adhesive between metal and metal, between metal and plastic, modifier of hot-melt adhesive, iron dimension waterproof processing of textile, etc. A variety of new industrial applications are also continuously developed and applied.
The general characteristics of PVB are as follows:
The appearance of polyvinyl butyral (PVB) resin is white spherical porous particles or powder, and its specific gravity is 1:1; However, the filling density is only 0.20 ~ 0.35g/ml.
Thermal properties
The glass transfer temperature (TG) of polyvinyl butyral (PVB) resin ranges from 50 ℃ of low degree of recombination to 90 ℃ of high degree of recombination; The glass transfer temperature can also be adjusted by adding an appropriate amount of Plasticizer to reduce it below 10 ℃.
Mechanical properties
The coating of polyvinyl butyral (PVB) resin has good water resistance, water resistance and oil resistance (it is resistant to aliphatic, mineral, animal and vegetable oils, but not to sesame oil). PVB is widely used in printing inks and coatings because it contains high hydroxyl groups and has good dispersibility to pigments.
In addition, its chemical structure contains both hydrophobic acetal and acetic ACID groups and hydrophilic hydroxyl groups, so PVB has good adhesion to glass, metal, plastic, leather and wood.
Chemical reaction
Any chemical that can react with secondary alcohol will also react with PVB. Therefore, in many applications of PVB, it is often used with thermosetting resin to bridge and harden with the hydroxyl group of PVB, so as to achieve the characteristics of chemical resistance, solvent resistance and water resistance.
Of course, films with different characteristics (such as hardness, toughness, impact resistance, etc.) can be prepared according to different types of thermosetting resin and different mixing ratio with PVB.
Safety properties
This includes recycling waste streams, using renewable energy sources, and reducing the carbon footprint associated with the extraction and processing of titanium ore This includes recycling waste streams, using renewable energy sources, and reducing the carbon footprint associated with the extraction and processing of titanium oretio2 pigment manufacturers. Some companies have even turned to synthetic biology to produce TIO2 pigments through microorganisms, aiming to create a bio-based alternative to traditional mining and chemical synthesis.
The skin of an adult person is, in most places, covered with a relatively thick (∼10 μm) barrier of keratinised dead cells. One of the main questions is still whether TiO2 NPs are able to penetrate into the deeper layers of the skin. The majority of studies suggest that TiO2 NPs, neither uncoated nor coated (SiO2, Al2O3 and SiO2/Al2O3) of different crystalline structures, penetrate normal animal or human skin. However, in most of these studies the exposures were short term (up to 48 h); only few long-term or repeated exposure studies have been published. Wu et al.83 have shown that dermal application of nano-TiO2 of different crystal structures and sizes (4–90 nm) to pig ears for 30 days did not result in penetration of NPs beyond deep epidermis. On the other hand, in the same study the authors reported dermal penetration of TiO2 NPs with subsequent appearance of lesions in multiple organs in hairless mice, that were dermal exposed to nano-TiO2 for 60 days. However, the relevance of this study for human exposure is not conclusive because hairless mice skin has abnormal hair follicles, and mice stratum corneum has higher lipid content than human stratum corneum, which may contribute to different penetration. Recently Sadrieh et al. performed a 4 week dermal exposure to three different TiO2 particles (uncoated submicron-sized, uncoated nano-sized and coated nano-sized) in 5 % sunscreen formulation with minipigs. They found elevated titanium levels in epidermis, dermis and in inguinal lymph nodes, but not in precapsular and submandibular lymph nodes and in liver. With the energy dispersive X-ray spectrometry and transmission electron microscopy (TEM) analysis the authors confirmed presence of few TiO2 particles in dermis and calculated that uncoated nano-sized TiO2 particles observed in dermis represented only 0.00008 % of the total applied amount of TiO2 particles. Based on the same assumptions used by the authors in their calculations it can be calculated that the total number of particles applied was 1.8 × 1013 /cm2 and of these 1.4 x107/cm2 penetrated. The surface area of skin in humans is around 1.8 m2 and for sun protection the cream is applied over whole body, which would mean that 4 week usage of such cream with 5 % TiO2 would result in penetration of totally 2.6 × 1010 particles. Although Sadrieh et al.concluded that there was no significant penetration of TiO2 NPs through intact normal epidermis, the results are not completely confirmative.
105°C volatile matter, %
The FDA has approved its use, but the responsibility of providing safe and pure TiO2 falls on the shoulders of reputable suppliers The FDA has approved its use, but the responsibility of providing safe and pure TiO2 falls on the shoulders of reputable suppliers