Polyisobutylene in the tackifying masterbatch

Let’s first learn about polyisobutylene: Polyisobutylene (PIB) is a polymer obtained through the cationic polymerization of isobutylene, with molecular weights ranging from several hundred to several million. It is a typical saturated linear polymer. The main molecular chain contains no double bonds nor long side chains; its structural unit is -（CH2-C(CH3)2）-, which lacks asymmetric carbon atoms, and these structural units are connected in a regular head-to-tail sequence. The development of polyisobutylene in our country started relatively late; research and development began in the 1980s. Initially, it was researched and produced by Lanhua Refinery and Jinzhou Refinery as a raw material for barium salts used as detergents and dispersants in internal combustion engine oils. Its raw material for production is the C4 fraction, and AlCl3 as a catalyst with a 1.5-aluminum ratio is used; the molecular weight of the resulting product ranges from 1000 to 3000. In the early 1980s, Lanhua Refinery and Jinzhou Refinery built production facilities with capacities of 500 t/year and 300 t/year respectively. Jinzhou Refinery also produces a lubricant viscosity index improver with a molecular weight of 40,000, marketed under the name T603. Daqing Petrochemical Complex has also carried out research on polyisobutylene, producing polyisobutylene with a molecular weight of 20,000–40,000. The raw material used is mixed C4, with a toluene-AlCl3 system catalyst. The polyisobutylene produced by these 3 manufacturers in 1977 was all light yellow in color, making it unsuitable for use in white products. Moreover, the products with a molecular weight of over 20,000 still contained diluent oils; they were not pure polyisobutylene products. As a result, their production and development were restricted. In 1988, the Jihua Research Institute began research on colorless high-molecular-weight polyisobutylene in order to localize the viscosity index improver (imported from Japan) used in the white oil exported by the Jihua Oils Factory, and completed pilot tests. Subsequently, colorless low-molecular-weight polyisobutylene was developed, and a 100 t/a pilot plant for oligoisobutylene was established to meet the demand for rodent glue produced in collaboration between Dalian Rat Poison Factory and Japanese Mitsui Disinfection Co., Ltd. The project passed the technical appraisal in Jilin Province in 1995. That same year, the Jihua Research Institute built China’s first 200t/a production facility for colorless polyisobutylene; the key technical parameters of the products reached international advanced levels, allowing them to fully replace imported products and filling a gap in the domestic market. The molecular weight range is between 30,000 and 100,000. Depending on the raw materials used for polymerization, polymers produced from pure isobutylene (≥99%) are called polyisobutylene. Those made from a mixed light C4 fraction containing isobutylene, other olefins (1-butene, cis-2-butene, and trans-2-butene), and alkanes (n-butane, isobutane) are commonly referred to as polybutylene, as their polyisobutylene macromolecular chains contain small amounts of n-butylene structural units (≤5%). Commercial polybutylene and polyisobutylene with the same molecular weight have essentially the same structure and properties. Due to chain transfer and chain termination reactions, the ends of polyisobutylene chains typically contain unsaturated double bonds. Based on the chemical structure of the terminal double bonds, polyisobutylene can be divided into ordinary polyisobutylene and reactive polyisobutylene. Ordinary polyisobutylene contains less than 15% terminal α-olefins; its other structures consist mainly of β-olefins and internal olefins ； Reactive polyisobutylene refers to polyisobutylene in which the content of terminal α-olefin structures accounts for over 70%; commercially available reactive polyisobutylene typically has an α-olefin structure content of more than 80%. Polyisobutylene possesses the chemical properties of saturated hydrocarbons, with its side-chain methyl groups arranged in a highly symmetrical manner; it is a polymer with unique properties. The aggregate state and properties of polyisobutylene depend on its molecular weight and molecular weight distribution; when the viscosity-average molecular weight is in the range of 70,000 to 90,000, polyisobutylene undergoes a transition from a viscous liquid to an elastic solid. Generally, based on the molecular weight of polyisobutylene, it is classified into the following series: low-molecular-weight polyisobutylene (number average molecular weight = 200–10000) ； Medium molecular weight polyisobutylene (number average molecular weight = 20,000–45,000) ； High molecular weight polyisobutylene (number average molecular weight = 75,000–600,000) ； Ultra-high molecular weight polyisobutylene (number-average molecular weight greater than 760,000).

This post was last edited by ljtjbx on 2015-9-8 09:07. Viscosity-enhancing masterbatches can be produced by mixing low-molecular-weight PIB with an appropriate amount of medium-molecular-weight PIB. The renowned masterbatch manufacturer, French company Polymold, uses BASF’s PIB as a raw material to produce viscosity-enhancing masterbatches. BASF polyisobutylene has the narrowest molecular weight distribution among all polyisobutylene/polybutylene products. At the same time, as it is the only company to use pure isobutylene as the polymerization raw material, its levels of monomer, oligomer, and impurities are also the lowest among all similar products. These properties ensure the high-temperature stability of the tackifying masterbatch; there is no extrusion of material at high temperatures (no precipitation of monomers or oligomers), the shelf life is significantly extended, and as a result, the performance of the final film products remains stable. The three most commonly used molecular weight grades of low-molecular-weight polyisobutylene are those with molecular weights of 1000, 1300, and 2400.

http://www.polytechs.fr/msmedias/telechargements/ft-anglais/PW60.pdf But the product description provided by the French company Polytechs states that a high-molecular-weight PIB is used; please refer to the link above.

PW 60 is a concentrate of high molecular weight Polyisobutylene tackifier in Linear Low Density Polyethylene. It refers to the concentrated, high-molecular-weight polyisobutylene tackifier in LLDPE. What exactly does this concentrated high molecular weight mean? The specification doesn’t mention its molecular weight? What does MO139-700* refer to? You really can consult the manufacturer regarding the specifications of PW60.

This post was last edited by ljtjbx on 2015-9-8 09:47. Translate your PW60 specification sheet: PW60 is a tackifying masterbatch that uses linear low-density polyethylene as a carrier and contains about 60% high-molecular-weight polyisobutylene; it appears as flowable dry granules. Used to produce LLDPE and LDPE wrapping film. Physical properties: Appearance – opaque dry particles with a slight amount of powder. Composition: PIB (polyisobutylene) 60% – 63%. MO139-700*. Density (g/cm3): 0.912; MO13-700*: Bulk density of approximately 0.50; MO28-700*. Applications: PW60 is used to produce stretch-wrapped films made from LLDPE, LDPE, or other types of polyolefins, for use in applications such as pallet packaging, silage packaging, and food packaging. The PW60 can be used for both blow molding and cast molding. The resin used together with PW60 must not contain any slip agents or opening agents, and its density must not exceed 0.923, as this can affect the proper precipitation of the tackifier. The precipitation time required to achieve good thickening properties is 24–72 hours. When producing stretch wrap for tray packaging, for single-layer blown film, 8% PW60 needs to be added to LLDPE (or mixed resin). For single-layer cast films, 3%-4% of PW60 needs to be added. On multi-layer film production lines, PW60 is usually added only to the surface layer, with the amount added depending on the layer being used and its thickness. The food contact properties of PW60 comply with the FDA regulations permitting use in food contact applications (such as 21CFR 177.1520 and 177.1430), as well as with the EC regulation 90/128/EEC. Packaging and Storage: The product is standardly packaged in bags of 25 kg each; a total of 1375 kg is packed in shrink film on a pallet. Storage conditions should be in a cool place (below 30°C), away from direct sunlight and heavy pressure.

MO139-XXX is the code for Bolid Company’s internal testing method. In practice, 2400 is used domestically; this actually represents a low molecular weight. However, the company’s website states that high molecular weight PIB is used. I think in this industry it has become customary to refer to anything with a molecular weight greater than 1000 as high molecular weight. But it’s not clear whether Baolide really uses high molecular weight materials; foreigners always come up with some rather strange solutions when it comes to products of this kind.

You can consult the manufacturer. Sometimes foreigners update their formulas very quickly; they are quite advanced in research in this area. The classification and use of high and low molecular weights still depend on the performance of the product.