问题 问答题 简答题

简述覆膜及覆膜的基本要求?

答案

参考答案:

腹膜就是将塑料膜涂上粘合剂,将其与纸为承印物的印刷品,经橡皮滚筒和加热滚筒加压粘合在一起,形成纸塑合一的产品。

基本要求:

1、厚度-薄膜的厚度直接关系到透光度、折光度、腹膜牢度、机械强度等方面。根据薄膜自负性能和使用目的,薄膜厚度在0.01mm~~0.02mm之间比较合适。

2、表面张力--用于覆膜的薄腹须经过电晕处理,或采用其他方法处理,使其表面张力大到4pa,以便有较好的湿润性和和粘合性能。

3、透明度--为了保证被薄膜的印刷品具有最佳清晰度,薄膜的透明度越高越好

4、耐光性--耐光性指塑料薄膜在光线长时间照射下变色的程度,用于覆膜的薄膜应具有良好的耐光性。

5、机械性能--塑料薄膜在覆膜工艺操作中要经受机械力的作用,因此必须使薄膜具备一定的机械强度和柔韧特性。

6、几何尺寸稳定性--塑料薄膜的几何尺寸不稳定,伸缩率过大,不但在覆膜操作时会出现麻烦,而且还会使产品产生皱纹、卷曲等严重质量问题。几何尺寸稳定,表明吸湿蹦胀系数、热膨胀系数、热变形系数、抗寒性等技术指标也比较稳定。

7、化学稳定性-塑料薄膜在工艺操作中要和一些溶剂、粘合剂以及印刷品的油墨接触,因此要求它必须不受化学物质的影响,具有一定的化学稳定性。

8、外观--应膜面平整,无凹凸不平及皱纹,无气泡、针孔及麻点,膜面应无灰尘、无杂质、无油斑等杂物,而且必须厚薄均匀。作为覆膜的主要原料,还要成本低。

阅读理解

A professor I have worked pretty closely with has been diagnosed with Stage 4 cancer. It has been devastating(悲惨的) for his family and heartbreaking for his students.

What made him extraordinary was not only that he was a rising star. He had only recently collected the highest honors for young researchers at the White House. We truly admire him—as someone put it, ‘He always has a smile and a kind word for everyone.” It is very hard to find someone who is extremely intelligent should be so nice a human being.

I decided that we needed him to know our attitude and also how we are all praying for his recovery. I bought him a simple card which read, ‘Healing thoughts and wishes coming your way.” I met all the students he worked closely with and got them to sign on it. Each student in his laboratory signed and also added a message. ‘We love you so much”, ‘We miss you! We need you back here—recover soon”… These were some of the messages that were written. Most of the students were really glad we were doing this and said it was a very good idea to give it to him.

He is still undergoing intense treatment, and along with his family is trying his best to stay optimistic and hopeful. I didn’t see a trace of self-pity or sadness when I met him last week. Instead, he paid attention to every word of my presentation and asked me several questions related to my work. I was amazed at how much he gave his 100% on that day in spite of being in pain because of chemotherapy( 化疗),he did not know if he even had another month to live. “I am trying to focus on staying positive, hoping to be back this summer,” he said.

Needless to say, I saw an expression of joy and hope on his face as he opened the card. He said he was truly touched to see the messages from the students he worked closely with.

There is one thing I learnt from last week: It is so important to tell people how much they mean to us and what an inspiration they are before it becomes too late. My professor, in spite of being too sick to teach classes, has managed to continue being a great teacher, introducing his last valuable message to us.

小题1:The professor was admired because _______.

A.he was very intelligent

B.he had won many honors

C.he had noble personalities

D.he was very determined小题2:What do the underlined words “our attitude” in paragraph 3 refer to?

A.Our worry about his health.

B.Our pray for his health.

C.Our admiration for him.

D.Our pity for him.小题3: When the writer visited the professor at hospital, what surprised him was that the professor ________.

A.was suffering form great pain

B.was still very confident

C.didn’t know he would die soon

D.still cared for others小题4: Of the following statements, the writer may agree that _________.

A.the professor loves his job very much

B.few students supported the writer’s decision at first

C.the professor will go back to teach this summer

D.the professor often feels sorry for himself小题5:According to the last paragraph, what did the author learn?

A.One should remain optimistic all the time.

B.It is important to let people know about their importance.

C.Teachers should have a positive influence on their students.

D.It is never too late to make a right decision.

单项选择题