Eraser can erase pencil words, which was first discovered by British scientist Priestley in 1770. Before that, people used bread to erase pencil words.
Priestley's discovery caused a great sensation because it brought great convenience to people. However, the earliest erasers were made of natural rubber. When you erase the words, there is no crumb. It just sticks the pencil tip to the eraser, and the more it is rubbed, the dirtier it gets. Later, when people made erasers, sulfur, oil and other substances were added to make the erasers easy to fall off, and the erased pencil scraps were left on the erasers together with the crumbs, so that the erasers could always be kept clean and the paper would not be stained.
History of Rubber Development 1770, British scientist joseph priestley said, "I saw a substance that is very suitable for erasing pencil handwriting." At that time, the whole of Europe used rubber particles cut into small cubes to erase handwriting. This kind of rubber was called rubber.
Eraser EdwardNaime, another British engineer, is believed to have invented the eraser in 1770. Before that, people used sponges to wipe away handwriting. Naime said that once he happened to pick up an eraser and found it to be very effective, so he began to produce and sell erasers.
The original eraser was inconvenient, because the unprocessed eraser was easy to rot. It was not until 1839 that the inventor CharlesGoodyear discovered that vulcanization could improve the quality of rubber, and the eraser became reliable.
1858 a man in Philadelphia, USA, obtained a patent for embedding an eraser at the end of a pencil, but the patent for this pencil with an eraser was later revoked because it was judged as "just embedding two existing things together, not a new product".
The main function is 1, which can erase pencil marks and correct typos. Now some can erase pen marks.
2. Some erasers are beautiful and can be used as gifts or handicrafts.
3. You can also wipe off the underworld on shoes, cars and other things.
The main types of novel erasers There are many kinds of erasers today, which can meet different needs, including ordinary incense erasers, art erasers such as 2B, 4B and 6B for painting, and plastic erasers. Some pencils have a small eraser at the end. Most of these erasers are pink and the surface is smooth gum. They perform well in most cases, but sometimes they damage the paper. If you push too hard, the eraser still has a chance to break the paper. When erasing handwriting, the eraser will leave a residue on the paper. If it is not cleaned properly, these residues will leave marks on the paper.
Rubber Another kind of rubber is the brown rubber commonly used by artists. It is made of soft and rough rubber. Its design is easy to erase large areas of traces without damaging the paper. But this eraser can't erase handwriting effectively and accurately.
Another eraser commonly used by artists is called soft eraser. It is mainly made of a gray material and rubber with gum. Its strength makes it leave no residue, so its life is longer than other erasers. It eliminates handwriting by "absorbing" graphite. This eraser can not only erase the handwriting (in fact, it can accurately remove the handwriting), but also be used to highlight important parts or make the work more detailed. But it is not good at removing large areas of handwriting, and it will get dirty or even stick to paper if it is overheated.
Soft polyethylene-based eraser has the texture of plastic, and its function is the same as that of ordinary pink eraser. These erasers are softer than pink erasers, so they are unlikely to damage the paper. Polyethylene rubber is generally white.
The raw materials of rubber are rubber or plastic, sulfur, vegetable oil and gravel.
Rubber: A high elastic polymer material with reversible deformation. It is elastic at room temperature, can produce large deformation under the action of small external force, and can recover to its original state after removing external force, and is non-conductive. Rubber is a completely amorphous polymer with a low glass transition temperature (Tg) and a large molecular weight of several hundred thousand.
The word rubber comes from the Indian cau-uchihu, which means "weeping tree". Natural rubber is formed by condensation and drying of latex of rubber tree with three leaves. 1770, British chemist J. priestley discovered that rubber can be used to erase pencil handwriting. At that time, the material used for this purpose was called rubber, which has been used ever since. The molecular chain of rubber can be crosslinked, and the crosslinked rubber has the ability of rapid recovery when deformed by external force, and has good physical and mechanical properties and chemical stability. Rubber is the basic raw material of rubber industry, which is widely used to manufacture rubber products such as tires, hoses, tapes and cables.
Rubber is divided into natural rubber and synthetic rubber according to raw materials. According to the form, it is divided into block raw rubber, latex, liquid rubber and powder rubber. Latex is a colloidal water dispersion of rubber; Liquid rubber is an oligomer of rubber, which is usually a viscous liquid before vulcanization; Powder rubber is made by processing latex into powder, which is convenient for batching and processing. Thermoplastic rubber developed in 1960s was formed by the processing method of thermoplastic without chemical vulcanization. Rubber is divided into general type and special type according to its use.
The concept of plastic raw materials
1, the main component of plastic raw materials is resin.
2. Plastic raw material: it is a kind of material which takes high molecular synthetic resin (polymer) as the main component, permeates various auxiliary materials or additives, has plasticity and fluidity under specific temperature and pressure, can be molded into a certain shape, and keeps the shape unchanged under certain conditions.
Rubber 3. Polymer: refers to pure substances or polymer materials produced during polymerization. Both natural resin and synthetic resin belong to polymer copolymer, referred to as polymer for short.
4. Plastic has good insulation performance against electricity, heat and sound: excellent electrical insulation, arc resistance, heat preservation, sound insulation, sound absorption, shock absorption and noise reduction.
Most of the raw materials of plastics are extracted from some oils, and some of the most familiar PC materials are extracted from petroleum, and PC materials have a gasoline smell when burning; ABS is extracted from coal, and it will smoke when burned. POM is extracted from natural gas, which will have a very smelly gas smell when burned.
Characteristics of general plastic raw materials:
A, plastic raw materials expand when heated, and the linear expansion coefficient is much larger than that of metal;
B, the hardness of general plastic raw materials is one order of magnitude lower than that of metal;
When rubber C and plastic raw materials are heated for a long time, their mechanical properties will obviously decrease.
D, general plastic raw materials will be permanently deformed under long-term stress at room temperature and under stress lower than its yield strength;
E, plastic raw materials are sensitive to notch damage;
F, the mechanical properties of plastic raw materials are usually much lower than those of metals, but the specific strength and specific modulus of some composite materials are higher than those of metals. If the product design is reasonable, it will have more advantages;
G. Generally, the mechanical properties of reinforced plastic materials are anisotropic;
H, some plastic raw materials will absorb moisture and cause changes in size and performance;
I. Some plastics are flammable;
J, the fatigue data of plastic raw materials are still very few at present, which should be considered according to the use requirements.
Classification of plastic raw materials:
Plastic raw materials are mainly divided into thermoplastics and thermosetting plastics according to the molecular structure of synthetic resin; For thermoplastics, it refers to plastics that are still plastic after repeated heating: there are mainly common raw materials such as PE/PP/PVC/PS/ABS/PMMA/POM/PC/PA. Thermosetting plastics mainly refer to plastics that are hardened by heating synthetic resins, such as some phenolic plastics and amino plastics, which are not commonly used.
From the scope of application, there are mainly general plastics such as PE/PP/PVC/PS. Commonly used are engineering plastics such as ABS/POM/PC/PA. In addition, there are some special plastics, such as high temperature resistance, humidity resistance, corrosion resistance and other plastics modified for special purposes.
Material utilization and color treatment:
Rubber 1, most plastic raw materials can be recycled, but because the recycled plastic (nozzle material) is more brittle than ordinary raw materials, it can only be used with new materials (raw materials), and the maximum proportion cannot exceed 25%. The principle is to take the standards required by customers as the standard. Various types of plastic materials should not be confused in production, because their melting points and injection pressures are different.
2. Because plastic products should be colored, plastic raw materials can be divided into: granular materials, toner materials, colored seed materials, and recently, liquid is added to colored plastic raw materials. The raw material for granulation is that the pigment has been mixed into the raw material, and each plastic material has been colored, so the color of the molded product is stable and uniform. The toner material and the color seed material use color seeds or color powder mixed raw materials, which has low cost and does not need to store a large amount of colored raw materials. But the color is unstable, so it is difficult to control the uniformity in production.
Working principle The working principle is that rubber molecules are easy to interact with other substances, and rubber itself is soft and does not damage paper. In daily life, even if the same words are written, everyone can tell which one is written by a pencil and which one is written by a pen. And the words written by pencil and pen must be erased with different erasers.
Eraser writes with a pencil, and the handwriting only stays on the surface of the paper and does not go deep into the inside of the paper, but the pen is different. When writing with a pen, the handwriting will penetrate into the fibers of the paper and dye the paper ink.
When you erase the handwriting of a pencil with an eraser, it is actually the eraser that absorbs the handwriting written on paper (composed of pencil powder). As long as you wipe it with an eraser, the pencil handwriting disappears along the "footprint" of the eraser, that is, the adsorption force of the eraser on pencil powder is greater than that of paper on pencil powder. When writing with a pen, if you want to erase the handwriting on the surface of the paper and the inside of the paper a little deeper (ink enters the paper), you have to mix hard fine powder into the rubber. This kind of eraser works just like filing things with a file, but erasing the traces of pencils with an eraser is a phenomenon caused by friction.
Clever way to remove the shoe prints on the car Many car owners are always worried about the shoe prints on the car door. Although the shallow interior looks good, there are always shoe prints that are accidentally erased by themselves or passengers. I've tried all kinds of cleaners myself, and the shallowness is ok, but some obvious traces are difficult to remove. Many car owners also spent a lot of money to go to the car beauty center for special cleaning. Not only did the effect not be satisfactory, but new shoe prints appeared a few days later.
For the shoe prints on the door panel, the eraser has a magical cleaning effect. Even stubborn shoe prints will disappear without a trace with a brush, and there is no corrosion at all. The price is only1100 of detergent, and it is small in size and does not take up space.
If sparks often appear on the switches of electric spark lamps and appliances. You can cut off the power supply and disassemble the switch. There will be black spots on the copper sheet in the switch. You can use an eraser to wipe a few times in the black place of the copper sheet to eliminate the electric spark.