What is petroleum resin

From a certain perspective, petroleum resin concentrates on the advantages of various compounding agents such as reinforcing agents, softeners, plasticizers, and tackifiers. It has the following advantages:

  1. Compared with natural resin, the entire production process of petroleum resin takes petroleum cracking as the starting point and cracking by-products as raw materials, so it does not occupy land, and the raw materials are abundant and the production potential is large.
  2. Comprehensive performance, multi-functional characteristics, can provide various functions such as reinforcement, softening, viscosity-increasing and plasticizing by adjusting the synthesis technology to meet the requirements of rubber stopper processing and product performance.

Petroleum resin manufacturing process

A resinous substance obtained by polymerization using a fraction obtained by petroleum cracking or copolymerized with an aldehyde or an aromatic hydrocarbon compound is collectively referred to as a petroleum resin. The light tar obtained by cracking in a petrochemical plant is used as a basic raw material, and a fraction of 130 to 170 ° C is cut off. After reacting these fractions with alumina or boron trioxide, polymerization is carried out under the catalysis of chloroethyl ether, and the catalyst is removed by adding lime water, washed with water, reduced pressure, and distilled to obtain a solid petroleum resin product.

Belt bias tire structure

The structure of the tire is divided into two categories: skew and meridian. Currently, the meridian structure is the mainstream, which is well known.
However, few people know that in addition to the above two types of tire structures, there have been tires of the third type of structure, namely “beltedbiastyre”, which is also known as “semi-meridian tire” because The carcass is a skewed structure, and the same as the bias tire. However, the carcass layer is hooped with a belt layer, which is the same as the radial tire. It can be said to be a hybrid structure. The figure below shows the three structures of the tire.
The belt bias tires once occupied some markets in the United States in the 1960s and 1970s. At that time, several American big tire companies had advocated and put the product on the market. At the beginning, because its performance is better than the bias tire, it has also been welcomed by users, and the real reason is the following two points:

1 The manufacturing equipment (special molding equipment) of radial tires and the equipment of the bias tires are very different and cannot be used universally. To produce radial tires, a lot of money must be invested to replace the equipment, and the old equipment that has been replaced becomes a pile of scrap iron.

Three types of rubber tires

2 The United States has always been a leader in tire manufacturing technology. The implementation of the meridianization is tantamount to self-identification as others (because the radial tires are first introduced in Europe), and they can’t get through. Therefore, the power icon is new and not unique.

Because of the incompatibility of radial tires in various aspects, the belt has been out of the historical stage for more than 20 years and has become a historical term. However, from the perspective of respecting historical facts, it should be recorded.

The role of shape memory rubber

Shape memory refers to the phenomenon that an object with a certain original shape is deformed after being deformed under external conditions, and then restored to the original shape under external conditions (for example, heating). For example, titanium-nickel alloy is a shape memory material widely used in technology and medical fields.

Rubber as a polymeric elastomer also has a specific shape memory function, but is quite different from the shape memory function of the alloy. It is based on the characteristic mechanical properties of rubber – elasticity, that is, the elasticity as the main content of memory. Elasticity is a property unique to rubber and not available in other materials. That is to say, under certain conditions, the elasticity is temporarily closed and frozen, and when necessary, the frozen is released by heating.

Crystallize to restore elasticity. This performance switching with an elastic-rigid-elastic process is the mechanism of the rubber shape memory function. For example, vinyl silicone rubber can be used as a shape memory material, and the above mechanism is used to prepare a heat shrinkable packaging material, which is an example of the earliest successful application of rubber.

(1) Performance requirements for materials

Shape memory rubber relies mainly on elasticity to achieve shape memory. It is necessary to obtain two components having elasticity and rigidity by blending or copolymerization by a specific process. Materials should have the following properties:

1 Easy to form thermoplastic;
2 under the action of external force (generally heating), deformation to rigidity;
3 After cooling, it can be locked in a rigid state;
4 When heated again, the locked rigid state can be released and restored (returned) to the elastic state.

(2) Requirements for materials

From a material perspective, shape memory rubber should have the following structure and function:
1 Both rigid and flexible segments, the former provides flexibility;
2 can form a network structure through physical or chemical crosslinking;
3 It should be locked in the crystalline state at normal temperature.
According to the above requirements, the shape memory rubber should have the characteristics of two phases (elastic amorphous phase and rigid crystalline phase). This structure is obtained by blending. The EPDM/PP blend is a typical shape memory rubber. Due to the wide variety of shape memory rubber products and their different properties, specific applications must be considered when selecting materials.

(3) Use

Shape memory rubbers are used in a variety of applications, such as electrical pipe connections, wire bundles, cable termination coatings, and roller outer coatings. Also used for medical purposes, such as splint fixing, strip fixing, etc. In addition, it is also widely used in daily necessities such as sealing packaging materials.

(4) Advantages and disadvantages

Rubber as a shape memory material has many advantages, such as light weight, insulation, and no rust.
The cost is low and it can be colored. These are all lacking in other shape memory materials. But there are also shortcomings, their shape memory is one-way, can only run once in one direction, but can not do the opposite. In other words, the memory function can only be used once, but not like the titanium alloy.

What is magnetic rubber

Magnetic rubber is a general term for magnetic elastomer materials. It is made of raw rubber, magnetic powder (magnetic filler) and other additives. Magnetic properties are the basic properties of magnetic rubber. Under the action of external magnetic field, magnetic rubber exhibits different magnetic grades, among which the magnetic properties have high practical value.

Since the rubber itself is not magnetic, its magnetic properties come from a large amount of filled magnetic powder (2 to 8 times the mass of the raw rubber). Therefore, magnetic powder is indispensable for the manufacture of magnetic rubber. According to the composition, the magnetic additive can be divided into two major categories: metal magnetic powder and ferrite powder, collectively referred to as magnetic powder. Metal magnetic powder includes iron cobalt powder, etc. Iron cobalt powder is the most widely used. Metal magnetic powder is less used because of its high price and difficulty in adding. Currently used are ferrite powders, which are compounds of iron oxide and certain divalent metals. Even if it is a ferrite magnetic powder, the final magnetic strength differs depending on the crystal form, particle size and uniformity.

The manufacturing process of magnetic rubber is similar to other products. In formula design, we must first determine the type, particle size and amount of magnetic powder. Next, the rubber type should be determined according to the requirements of use. For example, natural rubber should be used for wear resistance. Before or after vulcanization in the process, it is necessary to add a magnetization process that is not available in the manufacture of other products, so as to give the product the advantage of magnetization before permanent magnetic vulcanization. The direction of the external magnetic field is unchanged, and the rubber network is smooth; the magnetization after vulcanization The passability is poor, but the operation is more convenient. In short, each has its own merits.
Magnetic characterizations include magnetic intensities, residual magnetic inductivity, and magnetic energy products. Magnetic induction is the most common. Its unit of measure is Gaussian (GS).

The traditional use of magnetic rubber is represented by the Kumen sealing strip of the refrigerator, but with the development of high technology and household appliances entering thousands of households, the application of magnetic rubber is also changing with each passing day. Applications include refrigerator seals and computer memory devices. TV audio and video, teaching aids, toys and medical equipment.

Several new concepts related to the design of rubber shoes II

(2) shock absorption foot protection

When people are exercising or walking, they need to wear shoes and socks to protect them. Because the shoes are in direct contact with the ground, the functions of the foot protection are heavier, and it is necessary to prevent the sharp objects and the thorns from being cut, and to prevent external impact. For professional sports shoes, it is necessary to withstand severe shocks and shocks. Especially for some sports that have a strong impact on the ground and high landing height, such as football, basketball and pole vault, the protective function of the shoes is more important.

The air cushion introduced in the energy return section also has a shock absorption function. In addition, some special rubber shoes for labor protection are provided with metal parts at the toe area to prevent injuries to the toes and insteps when heavy objects are hit. It can be seen from the above that the foot protection function of the rubber shoes is mainly achieved by two measures: one is to use the buffering and shock absorption of the gas to soften the steel; the other is to use the rigid body (steel head) to harden the hard.

(3) Torque correction

The concept aims to correct the common problem of walking and skewing through the design and modification of the shoes, thereby reducing the fatigue caused by poor posture and increasing the ease of progress. Most people instinctively become more or less in the walking foot (individually different).

In the 1980s, some rubber shoes companies raised the concept of “torque correction” and proposed a “correction system” accordingly. The system is positioned in the groove between the fore and aft palms (called the torsion groove). A longitudinal strip bar (called a torsion bar) is placed in the center of the groove, and the front and rear parts of the sole are penetrated to make the piece integrated, and the torsion force is limited to a small range, and the torsion deviation amplitude is also significantly reduced, to a large extent. Corrected the phenomenon of partial twist.