In addition, please see the following post for details, the same question as you.
zhidao.baidu/question/2455099
Question 2: Does the pencil contain lead? number
The early pencils contained lead, but now the main components of pencil refills used by people are graphite and binder, and lead is no longer contained, which is harmless to human body.
Pencil lead can be used as a lubricant because:
1. pencil lead contains graphite, which is smooth. Pencil lead can lubricate rust-proof locks.
2. Graphite has a high melting point. As a lubricant, it is especially suitable for machines working at high temperature. At high temperature, general engine oil will decompose, however, graphite is very stable and continues to play a lubricating role.
Graphite is a scaly solid with metallic luster, which is composed of carbon. Its structure is very stable, and nothing in the human body can destroy it, so pencil lead is nontoxic.
Question 3: Is the lead in the pencil poisonous? The lead in the pencil is nontoxic. The lead in this pencil is not metallic lead.
The main raw materials for making pencil lead are graphite and clay, which are non-toxic; Unless the clay added in it is harmful to human health.
Pencils now contain no lead, but are made of graphite and clay. The reason for this name is its historical evolution. In ancient Greece and Rome, lead bars similar to pencils were made of metallic lead. Most of them are conical, which will leave traces of lead after rubbing with other objects for marking.
Question 4: Does the pencil contain lead? The composition of a pencil is graphite.
Question 5: Why is a pencil called a pencil because it contains no lead? Pencil lead contains no lead, and its main component is graphite.
Because lead has black marks when writing on rocks or walls, people used lead as a tool for drawing and writing in ancient Greece and Rome. In ancient China, it was written on silk and paper. If there is any mistake, correct it with lead powder. Therefore, the word "pencil" does exist in ancient Chinese, but it is different from modern pencils.
/kloc-in the 5th century, graphite ore was discovered. At that time, people didn't know the composition of graphite, so they called it "black lead". Around 1492, the British began to use pens made of graphite, which are called pencils. It was not until 1779 that scientists knew that graphite was a form of carbon. It is made by grinding graphite into powder, mixing it with clay, and then pouring it into two semicircular wooden pipes. In recent years, there are also plastic pens on the market.
In order to meet various needs, graphite and clay in pencil refills can be mixed in different proportions, and the properties and uses of pencil refills are different with different mixing ratios. For example, the refill for sketch should be softer and deeper; The refill for students' homework needs to be harder and lighter in color. When buying a pencil, you should pay attention to the marks on the pen, where H stands for hard, F stands for fast and B stands for thick. According to the information provided by the manufacturer, the order of all kinds of pencils from soft to hard is as follows
HB-B-2B-(*)-9B-F-H-2H-(*)-9H
Where (*) represents the code number between 2B and 9B or 2H and 9H.
Question 6: Does pencil lead contain lead? The 30-point pencil was really made of lead when it was first invented. Now the main component of pencil lead is graphite, not carbon, mixed with clay. The hardness of refills made according to different clay proportions is different. The higher the clay proportion, the higher the hardness.
Question 7: Are there any pencils with extremely low lead content, mainly graphite whose element is C (carbon)?
Question 8: What are the main components of a pencil? Does it contain lead? Pencil lead is graphite and clay, but it contains no lead. Pencil sticks are mainly wood. If the product is of poor quality, the paint on the surface may contain lead. Good quality products are lead-free.
Question 9: Why is a pencil called a pencil because it contains no lead?
1564, a black mineral-graphite was discovered in a place called Rodale. Because graphite can leave traces on paper like lead, and its color is much darker than lead, people call it "black lead".
At that time, shepherds in Barodale often used graphite to mark sheep. Inspired by this, people cut graphite blocks into small strips for writing and painting. Soon, King George II of England simply owned the Barodale graphite mine to the royal family, making it an exclusive product of the royal family. Writing with graphite strips will not only dirty your hands, but also break them easily. 176 1 year, the German chemist Faber first solved this problem. He washed graphite with water to make it into graphite powder, then mixed it with sulfur, antimony and rosin, and then made this mixture into strips, which were much tougher than pure graphite strips and less likely to get his hands dirty. This is the earliest pencil. Until the end of 18, only Britain and Germany could produce this kind of pencil in the world. So, Napoleon? After Bonaparte waged war against neighboring countries, Britain and Germany cut off the supply of pencils to France. So, Napoleon? Bonaparte ordered the French chemist Comte to look for graphite ore in his own country and then make pencils. However, the quality of French graphite ore is poor and its reserves are small. Comte mixed clay with graphite and put it in a kiln for barbecue, which made a good and durable pencil lead in the world at that time. Pencil lead produced by different clay proportions in graphite has different hardness and color. This is the origin of H (hard pencil), B (soft pencil) and HB (pencil with moderate hardness) marked on pencils today. The task of putting a wooden stick coat on a pencil was completed by American craftsman Monroe. He first built a machine that could cut the battens, then carved a slot in the battens, put pencil lead in the slot, and then aligned and glued the two battens together, with pencil lead tightly embedded in the middle. This is the pencil we use today. The pen core made of graphite or colored clay is used as a writing medium and as a writing or painting tool for study, office work, engineering drawing, art, painting, various marks, etc. In ancient Greece and Rome, lead bars similar to pencils were made of lead metal. This kind of pen is mostly made into a cone shape, and lead is rubbed on other objects, leaving traces of lead for marking. /kloc-in the 0/4th century, a similar modern pencil appeared in Europe, and Dutch painters used it to draw on paper. Italians use a mixture of lead and tin to make lead strips, which are used for painting and writing. 1565, German C. Gesner's library made an illustration with a pencil, which recorded that "for drawing and taking notes, people used lead and other mixtures as refills, and then attached wooden handles to draw lines ...". In the same year, Britain began to make the most primitive wooden pencils by hand, with graphite as the refill. 1662, the world's first pencil factory-Shidelou pencil factory was built in Nuremberg, Germany. 176 1 year, F. Custer, a German, founded Faber in Nuremberg. Universal wheel pencil factory uses sulfur, antimony, etc. As a binder, graphite is heated and mixed to make lead core, which makes the pencil manufacturing technology take a big step forward. From 1790 to 1793, N.J. Kant of France used the method of washing graphite for the first time to improve the purity of graphite, and bonded graphite with clay to make a refill. This method is called Kong Defa. Kant pencil factory was established in 1793, which laid the foundation of modern pencil industry. China established the first Dahua pencil factory in Kowloon on 1932. Later, Beiping China Pencil Company and Shanghai China Pencil Factory were successively established, both of which were semi-finished products processing plants. From 65438 to 0934, China Standard Domestic Pencil Factory was established in Shanghai, and self-made lead cores were started to study domestic raw materials to make pencils. After the founding of New China, Harbin, Beijing, Tianjin, Jinan, Dalian, Fuzhou, Shenyang, Bengbu and other cities have successively built large pencil factories with an annual output of1.50 ~ 250 million. Lead core manufacturing, painting, printing and decoration techniques have also been continuously improved, and all-plastic pencils, resin fine lead cores and fine core movable pencils have been developed. New equipment such as rubber sheet binding dryer, automatic painting machine, electric tunnel core-burning furnace, grinding machine and various packaging machines have been developed.
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