Archive for category: Industry News

Polyfunctional acrylates, methacrylate, and other unsaturated monomers are widely used in coatings, adhesives, sealants, elastomers, crosslinked films, cast sand binders, and composite structures. These monomers can be cross-linked by a free radical chain reaction, which requires a substance (e.g., peroxide, peroxide, or nitrogen compounds) capable of producing free radicals that break down to form free radicals when heated or at ambient temperatures in the presence of a class or transition metal accelerator.

Another way to initiate a reaction is to use UV light to break down photosensitive initiators to form free radicals. This method is not yet widely used but is improving. This method provides a very rapid processing process that allows a large number of applications to be carried out because the transition from a liquid reactive composition to a cross-linked solid substance is done essentially at the same time as UV exposure.

The disadvantage of both methods of initiating free radical reactions is that the decomposition of the initiator or photosensitive initiator produces low-molecular weight components that may volatilize during or after the production process, resulting in safety problems for workers, consumers and the environment. For example, these low molecular weight parts are easy to be absorbed by the skin, which has adverse effects on health. Another disadvantage is that acrylic’s free radical reactions are usually inhibited by oxygen, such as the presence of oxygen, which prevents the reaction from progressing completely.

These limitations exist in several major approaches. This problem with the escape of the photoinitiator component during production or subsequent leakage has been solved by the preparation of acrylic monomers/oligomers containing the “indigenous” photoinitiator. This can be achieved by taking a compound (or suitable derivative) known as a photosensitive initiator as the starting material and functionalizing it with an appropriate unsaturated group (e.g., acrylic or methacrylic acid) to produce a new compound with the dual function of a monomer/oligomer and a photosensitive initiator. Or it can be grafted onto a formed oligomer/polymer to produce a higher molecular weight photoinitiator. Regardless of the effectiveness of these methods, they always add additional production processes and costs.

This paper relates to a pressure-sensitive adhesive tape structure that can be used to mask printed circuit boards (PCBs) at high temperatures associated with wave welding operations. This type of adhesive tape consisting of ionic conductive polymeric particulate adhesive has high friction electrostatic resistance and thus can protect electronic components from static electricity formation. In addition, when the adhesive mask tape is removed from the PCB, no adhesive residue will stain the surface of the board.

Process description:

Wave welding is commonly used to permanently attach electronic components to printed circuit boards. During wave welding connections, the various methods used to mask or cover the plate do not want flux in the area. Such masks are known to be obtained using self-adhesive tapes based on high temperature resistant polyimide films coated with silicone-based adhesives. However, the removal of such adhesive strips from the surface of the electronic assembly results in a frictional charge caused by static electricity, which damages sensitive electronic components and leads to contamination of the printed circuit by silicone.

Conductive tape can also be used for masks. Conductive tape does not cause friction charges as easily as tape made of insulating material such as silicone, so the use of conductive tape reduces the failure rate of electronic components during assembly operations.

A variety of different types of conductive strips are known to be available at room temperature using US patents 31049853832,598 and 4749612 describe adhesive strips with a carbon black binder coating that is said to eliminate static charges. Many patents also reveal multilayered ribbon structures in which one, usually buried, layer is conductive.

For example, Japanese publication J63012681-A reveals a strap with an intermediate antistatic polymer layer between the polyolefin substrate and the rubber bonding layer.

European patent EP0422919-A2 discloses a band having a conductive particle or foil layer surrounded by a binder between a polymer film substrate and a silicone binder layer. It is said that the use of a high-temperature film substrate, polyimide, combined with a silicon binder and an adhesive can produce a tape that performs well as a wave welding mask at high temperatures where previous antistatic strips are not applicable. That is, the tape can remain intact in the wave welding groove at a temperature of 250℃ for 5 seconds.

At present, the medical pressure-sensitive adhesive on the market is made by the reaction of monomer, solvent, and initiator. The monomer is acrylic acid, methyl methacrylate, butyl methacrylate, and other acrylates, the solvent is ethyl acetate, and the initiator is peroxide. This medical pressure-sensitive adhesive is irritating to human skin and even produces allergic reactions.

The purpose of this paper is to provide a kind of polyacrylate pressure-sensitive adhesive suitable for all seasons without side effects and its preparation method. Here’s how we did it: butyl acrylate, isooctyl acrylate. Vinyl acetate is the monomer, ethyl acetate is the solvent, and peroxide is the initiator, after purification treatment, by weight percentage polymer composition is: butyl acrylate 50~70% isoctyl acrylate 7~15%, vinyl acetate 15~35%, peroxide is the monomer total 0.4~1.0%, Ethyl acetate 53~65% of the total weight by percentage by weight One component of the polymer: butyl acrylate 70%, isooctyl acrylate 10%, vinyl acetate 20%, peroxide 0.7% of the total monomer, ethyl acetate 55% of the total weight by percentage by weight another component of the polymer: butyl acrylate 60%, Isooctyl acrylate was 9% and vinyl acetate was 30%. Peroxides are 0.76% of the total monomer: and ethyl acetate is 56% of the total weight. Peroxides mainly refer to benzoyl peroxide and azobisisobutyronitrile.

This is dedicated to the manufacture of the medical polyacrylate pressure-sensitive adhesive method, the steps are (1) monomer, solvent, and initiator mixing evenly;

(2) Most of the mixture was placed in the drip funnel, and the remaining small part of the mixture was placed in the reactor to fill the reactor with nitrogen to drive out air; After the reactor stirred at reflux temperature for 20~40 minutes, the mixture in the drip funnel was dropped into the continuously stirred reactor within 60~120 minutes.

(3) Then slowly add the solvent containing initiator into the reactor, and continue stirring the reaction at reflux temperature for 20~40 minutes:

(4) Add the solvent slowly in the reactor, continue to stir, and react at reflux temperature for 20~40 minutes, and then at atmospheric pressure, the added solvent is distilled off, and the gel liquid is cooled.

The pressure-sensitive adhesive made above is a colorless or light yellow transparent viscous liquid, with the smell of ester, non-toxic to human skin, has no irritation, and no allergic reaction, and is a good performance of skin external auxiliary materials, main uses: used for skin patch, such as a variety of drug preparations around the adhesive, the fixed adhesive of the ECG electrode, etc.; It is used to make drug-controlled release patches mixed with some drugs. It not only has a good adhesive effect to ensure close contact between drugs and skin but also controls the dose of drugs entering the human body through the skin through the special chemical structure and composition of this pressure-sensitive adhesive, so as to achieve the purpose of zero-order drug release.

Removable pressure-sensitive adhesives are used on a variety of products, including labels, tapes, membranes, etc. so that the product adheres to the substrate and can be easily removed from the substrate without leaving stains or residues. In order to be suitable for such applications, the pressure-sensitive adhesive must have good adhesion with low peel strength and must not show significant growth in adhesion over time. Ideally, the pressure-sensitive adhesive should exhibit such physical properties on a variety of substrates.

Typical commercially available water-based acrylic emulsion pressure-sensitive adhesives cannot be used for outdoor applications. An outdoor application includes a decorative decal film applied to a substrate such as glass. One technique for attaching the decorative decal film to the substrate is to spray water over the adhesive and/or substrate so that the decal film can slide over the substrate for easy positioning.

Unfortunately, in this type of technology, the water-based acrylic emulsion adhesive film turns milky white in contact with water. Another outdoor application includes a protective film applied to a construction project material using an adhesive, where the film is used to protect the structural material until the completion of the construction project. Exposure of protective film-covered building materials to water or high humidity in an outdoor environment often results in a milky white color for water-based acrylic emulsion adhesives. For transparent film surface material,

The whiteness of the water will result in an unsatisfactory appearance.

For a successful water-based acrylic emulsion removable pressure-sensitive adhesive used for decorative or protective film and decal film for outdoor applications, the adhesive will need to demonstrate good water resistance along a good anchorage of the adhesive to the membrane surface material to ensure clean removability from the substrate. The current commercial purchase of water-based acrylic emulsion pressure-sensitive adhesive showing good water whitening resistance is a permanent adhesive, that is, if the surface material is removed will leave adhesive residue on the substrate of those adhesives, the film shows good anchoring properties of the existing removable water-based acrylic emulsion pressure sensitive adhesive also shows water whitening resistance. Therefore, there is still a need for two kinds of water-based acrylic emulsion pressure-sensitive adhesives that show both removability and water-whitening resistance.

Outer-pressed (over-laminating) adhesive membranes have been used to protect printing through heat transfer.

Now, over-laminating adhesive membranes are being used to protect printing surfaces generated through heat transfer printing, inkjet printing, offset printing, relief printing, intaglio printing, and more from water, sun, abrasion, and more. The outer pressed adhesive film generally consists of a surface substrate stripping material in the form of a transparent film and an adhesive layer sandwiched between the two. The stripping material is stripped from the film when used.

Adhesives for outer pressed adhesive films include emulsion, solvent-based, solvent-free, and various adhesives made of rubber-based acrylic, or vinyl ether-based compounds. Of these adhesives, acrylic adhesives are the more suitable to use as this adhesive has excellent weather resistance, peel stability over time, and transparency. In particular, special attention has recently been paid to emulsified acrylic adhesives, which do not contain organic solvents that are harmful to humans and are therefore beneficial to the environment (see for example Japanese patent application delay disclosure Nos2001-240819 and 2002-80809).

But in general, emulsion adhesive and solvent adhesive compared to the obvious in the water white resistance and water resistance viscosity is poor. In addition, if the above acrylic emulsion adhesive is used to produce an outer pressed adhesive film by means of a so-called transfer coating method, in which the adhesive is applied to the stripped material and the transparent film is subsequently laminated to the adhesive, an additive such as a surfactant intended to improve the wettability of the adhesive to the stripped material is added to the adhesive. However, adding additives will cause the water resistance of the adhesive film to decrease. In particular, if the outer pressed adhesive film is laminated onto an inkjet printing surface, there is a problem with ink water when the printing surface is stored in wet conditions.