Sealants are mostly synthetic adhesives, and their main body is polymer. The properties of sealants can be divided into three categories: bulk properties, technological properties and use properties (product properties). The use property (product performance) is self-evident, mainly refers to the comprehensive performance of the sealant forming cementation joint during the cementation process, and the performance depends on the functional requirement of the sealant for building joints.

No matter for building periphery or indoor decoration, whether the window structure or other forms of enclosure and decorative structure, can be regarded as unit, then each unit is produced between joints, most need for building sealant to seal filling.

Reasonable design of building joints, understanding and understanding of building sealants, reasonable material selection and proper construction of building seals are essential for ensuring the success of building joint sealing. The small series collects and collects the common problems encountered in the actual use of sealant, and provides the corresponding solutions.
 

Acid gum

1. acid glue bottle will grow higher after storage for a period of time. It will even appear oil in the bottle. Why?

There are two reasons for this problem, that is, glue and glue bottles.

First, the reason for the glue. Now on the market in addition to a few high-grade acid glue, glue, glue and other acid are different degrees of adding a certain amount of filler and mortar to reduce costs, lower grade, the more amount of filler, filler and will react with the plastic bottle, so that the plastic bottle, bottle body deformation and tall oil; such as high-grade plastic may make the plastic bottle for 6 months before the reaction, lower grade glue may be 6 months after the reaction.

Second, the reason for the bottle. The quality of the rubber bottle itself is also the cause of its growth. The raw materials used in the bottle body are good and bad, and the raw materials are good, so the change trend of the rubber bottle is relatively slow. For example, if the quality bottle is high, it can be stored in high-grade gum for 7-8 months, and still has no response. On the contrary, the use of poor quality bottle can even deform in 2-3 months even if a good adhesive is applied.

2. why is there a thicker or dry glue from the bottom of the bottle at the bottom of the bottle?

This is mainly produced in the process of packaging. Because it takes a certain amount of time from packing to press the lid, although the time is short, it also makes the mortar contact with the air. If the sealant has a lot of curing from the bottom, it is caused by the bottom seal and the tight seal of the bottle. It is the quality control of the packing material.

3. acid gum extrusion process will break off or have small bubbles, why?

This kind of situation is mainly formed by the following two reasons.

One is that the storage temperature is too low: if the gum (especially the low-grade glue) is stored at a lower temperature, a lot of bubbles will be formed. The reason may be that after the low temperature storage, the liquid raw material due to the cold contraction volume to form more bubbles, so it is suggested that the storage temperature should not be less than 0.

Two is the formation of canned process in normal canned, bottled glue tail often has a few small bubbles, in the current mode of operation in which it is difficult to avoid, but also caused a substantial impact on the use will not: if bubbles appear more or dry (big bubble) situation is is caused by improper operation, must be improved and should be avoided. However, this situation also has the probability of occurrence, if less or occasionally there is such a phenomenon, it should be considered as a contingency. Large bubbles should be avoided in operation.

4. why the surface will wrinkle after the acid gum is solidified?

This is mainly due to the too thin adhesive layer when the surface of two substrates is applied. Due to the difference of thermal expansion and shrinkage rate of different materials, the glue with high temperature difference and incomplete solidification will become wrinkled and wrinkled.

Solution: coating the film thick, generally the thickness of the general construction of the film thickness of about 1mm, it is recommended to increase the thickness to (1.5-2) mm.

5. why does some acid glue make aluminum material discolourable after curing?

When the acid glue is solidified, it will release acetic acid, which is corrosiveness to the metal material and can be used on the aluminum material, because the aluminum surface is coated with oxide film or coating, and there is a coating to protect it. So in general, the discoloration of aluminum is not the problem of glue, here involves more construction operation and the quality of the aluminum itself. The quality of aluminum mainly refers to the unqualified coating layer of aluminum coated materials, such as poor adhesion, too thin film and so on, which will affect the color change after sizing. Improper construction will also cause discoloration. If the aluminum is placed in a poorly ventilated environment, the acetic acid released from the glass curing can not be dispersed in time. The local concentration is too high and the time is long. The corrosion of aluminum will make it discolouration.

6. after curing, the adhesive will turn white or yellow. Why?

Yellow: more cases, yellow glue is caused by the influence of other contact with the glass material, the most is to play in some black glass adhesive rubber (inlaid seal between the glass and aluminum), because some strips of poor quality, make contact with the yellow glass glue and even the glue is no exception. In general, rubber strips discolourate the glass glue. The analysis may be caused by the materials used in the rubber strip, especially the reaction between the filler and the acid glue, which makes the transparent glue discoloration. It is not excluded that the rubber strip can be added to the material that can be precipitated or evaporated, which pollute the glass adhesive strip. White: white glass glue is mainly sealant filler and too much; if the occasional white, often appear some works in the play too thin layer, so that the appropriate increase in the thickness of the glass glue sizing (1.5-3mm), in order to avoid a similar situation.

7. why will the glass glue on the paper will appear some sticky paper, some non sticky paper situation?

Not to stick the paper glass glue, so stick paper and adhesive paper will not affect the actual use; but some characteristics of sticky adhesive paper and paper and glass glue, first paper materials, different texture on the sticky paper impact, such as paper fiber is loose and is easy to wet glass glue paper, then stick the paper secondly; glass glue is also affected, preliminary analysis has a certain relation with the curing speed, such as low curing slow, easy to stick the paper.

8. why are the cured transparent acid gum strips become white after stretching?

Because of the addition of many solid filler in the acid gel, in order to increase the strength, tensile solid filler showed white, so look pale; this is the case in the domestic plastic, because of the differences between the solid filler and the cost of limiting the use of imported glue, but the performance of glass glue and did not affect the actual use.

9. why is the glass glue solidified slowly?

Have a great relationship with the deep curing environment, under normal circumstances, at low temperature, glass glue curing slower in high humidity environment; also curing in a poorly ventilated environment is slow; have different grades of the glass glue curing speed difference, especially the domestic adhesive curing speed lower obviously the difference in the ratio of high-grade plastic, low ambient temperature this difference is especially obvious, so that the domestic low-grade glue donot in the lower temperature (5 DEG C) near the use as far as possible.

10. why will the glass glue shrink after curing?

All sealants shrink after curing, but the shrinkage rate of high grade adhesive and low grade glue is very different. For example, the top grade gum only shrinks 5% after curing, and the lower grade glue may shrink to 30% or more. This is because the low grade gum is added to the filler, and the filler will slowly volatilize in the air, so the more the filler, the greater the shrinkage.

11.Is there a small amount of oil separated from the mouth of the bottle?

This is a normal phenomenon of long-term storage, generally stored in more than 3 months, but in practice the probability of this situation is not very high, because the glass glue oil separation is in long time static circumstances will occur, but due to the sale of cigarettes glue often is in motion, such as transport, handling, sorting warehouse so, quite a stir in time, so more time no delamination. Causes a small amount of oil separation is: products from raw materials and liquid solid material together, because of their different proportion, in the long-term static case will have a sinking phenomenon, but this process is very slow, so does not affect the use and performance of the product, there is the phenomenon of glue.

12. big buckets of gum more acid than sour taste?

The main difference is low grade glue, because the domestic low glue basic material is limited by the cost, which leads to the shorter storage period. In order to improve the storage period, we need to add a variety of additives, the taste is large, but the release is mainly acetic acid, harmless to the body.

13. why do some glass gum tables dry too fast and have no repair time?

This is related to the construction temperature and operation. It is recommended to avoid high temperature during construction and increase the number of trimming. If the original 2 meters long seam is trimmed, it can be changed to 1 meters long glue seam, that is, trimming, which can reduce the adverse effects caused by the fast drying.

14. glue strips on the paper have the phenomenon of oil seepage, why?

The first paper due to its different texture, material and so on, if the paper fiber is loose, so low filler added in glue will penetrate into the pores, produce the phenomenon of oil leakage; but through experimental observation, this situation does not appear in the actual use, the aluminum and glass, no oil leakage phenomenon. But it will not affect the adhesion, strength and other performance.

15. levels of high glue (including imported glue) more non sticky aluminum, why?

Because the curing speed is too fast, the slurry does not fully infiltrate the surface of the aluminum material, that is, it can not infiltrate into the micropores of the substrate surface and do not stick. This phenomenon does not affect the normal use of glass gum. There are two main high-grade glass glue, is a large glass curtain wall or curtain wall, glass glue used here only touch the glass, not in contact with other materials, so the aluminum is not sticky Never mind; two is used for Aluminum Alloy glass doors and windows sealing glass glue glass and fill in the Aluminum Alloy between joints, though adhesion of glass glue and Aluminum Alloy is not good, but because of good adhesion, the glass will not fall off, and do not use as sealing load (i.e. donot force), so long as they can adhere to the Aluminum Alloy can play a role in sealing.

16.There is crystallization in the acid gum？

This phenomenon would appear occasionally, is mainly caused by the low temperature storage, because the addition of acid colloid additives have many high freezing point, although AIDS has been integrated into the mortar, but at low temperature for a long time will still become crystal precipitation, so avoid low temperature storage.

17. acid gum turns red?

This phenomenon has only occurred occasionally, mainly due to the instability of raw materials, so the inspection of raw materials must be well controlled.

Neutral glue

Analysis of 1. reasons for blistering

There are many reasons for the foaming of silicone sealant in the construction of silicone sealant. It is very complicated. It is difficult to use a method and a result to determine the cause of foaming. Silicone structural sealants usually finish glue injection in factories, and the environment and operation conditions in factories are quite good, which are easy to meet the external conditions for silicone structural sealants to be solidified. Silicone weatherproof sealants are generally completed at the construction site to complete the injection work. The site environment and operation conditions are poor. The external conditions for silicone weathering gum in curing process are not easy to meet. The effects of climate, environment and operating conditions on the curing quality of silicone weathering adhesives are very important. Therefore, the limitations of the environment and operating conditions for the use of silicone weatherproof adhesives determine the main reasons for the foaming. The following analysis is made on some specific situations.

(1) when in the air injection.

The silicone rubber weatherproof adhesive is generally completed on the site, and the operating conditions are poor. The workers standing on scaffolding above plastic injection, rubber injection uniformity is not easy to master, which is easy to glue in air. After sizing glue scraping the surface pressure, trimming smooth, adhesive seam inside the pad bar are mostly made of polyethylene foam obturator rods in the air inside the glue is not easy to spill, glue dressing compressed air, will produce tension long outward, sealant seam is wide, small thickness, provide high displacement ability of weather resistant glue, hardness is low, not very soft glue before curing. The tensile tension of compressed air brace the seams slowly. This phenomenon is easier to take place in the application of weatherproof adhesive which can provide more than 25% seams displacement ability. On the contrary, there are weathering adhesives with low permissible displacement capacity, which have higher hardness and thicker before the glue is not cured. In the glue inside seam tension long compressed air is not easy to hold foaming glue. Therefore, the more the weatherproof adhesive which can provide high shift capacity, more attention should be paid to the uniformity of glue injection. The general glue injection of vertical glue can apply glue from lower to upper, and can overcome some bubbling phenomena. More important is the proficiency and responsibility of the working operator.

(2) the interface is wet when the glue is injected.

In outdoor work, often encounter rain, especially in the southern summer, almost every day, it s going to rain, if after the rain, wet wet interface directly injecting, such as the sun and glue joint interface bonding material inside temperature, moisture evaporation gum inside seam, the uncured, soft glue long gap foaming polyethylene foam pad, sometimes wet bar will cause foaming glue. So in the construction, we should not blindly ask for progress, when the interface is dry, and then injecting glue can avoid the above situation.

(3) bubble deflation

Glue inside the pad bar are mostly made of polyethylene foam obturator type high foaming stick, when placed in due to improper extrusion, resulting in internal balloon rupture, release the air just after injection will occur when the bubble gum is swollen bulge or appearance, the solution to this situation, one is the foam bar cutting open cut for inside, two is the use of open cell foam stick or vinyl foam with foamed rod, to overcome the above situation. In addition, methanol is released when the alcohol type weather resistant adhesive is cured, and methanol reacts with some foam rods. In this case, the problem is solved by changing the foam rod or the ketoxime type sealant.

(4) the sun is insolate when the glue is not cured.

Silicone gel can not be exposed to the sun before being solidified. Especially after just pouring the glue, it will cause honeycomb bubbles inside the glue joint and cause the external seams to rise, which will be more obvious when the silicone rubber is used. In the hot summer construction, this situation is not easy to overcome. Some bubbling phenomena will be overcome by avoiding the sun exposure when the glue is used. Specific methods: in the morning on the west side or the north side of the building glue, in the afternoon on the east or south side of the building glue. After the glue is injected, the glue has been solidified over a period of time, the surface has been skinned, and when the sun is again insolate, it has a certain resistance, and can overcome some bubbling phenomena.

(5) the surface temperature of the substrate is too high.

When silicone rubber is cured, the temperature of the adhesive can not exceed 50 degrees C. This conclusion has been approved by most of the silicone rubber manufacturers. In the surface temperature more than 50 DEG C glue injection, will cause the glue foaming, the metal plate wall weathering caulking, will encounter the situation. In the hot liter, when the sun is insolate the metal plate, especially the surface temperature of the aluminum plate will reach 80 degrees C, and the glue is very easy to cause the foam to sew. Therefore, the latter half of the afternoon or the cloudy day should be chosen to improve the situation.

(6) the temperature difference between day and night is large and the heat expansion and contraction of the interface is larger.

This situation is easy to appear when the aluminum sheet curtain wall glue is injected. Aluminum material linear expansion coefficient is larger, in the northern area of our country in the spring or autumn larger temperature difference between day and night, and the sun at noon when the surface temperature of direct aluminum, aluminum can be as high as 60 DEG -70 DEG, night temperature dropped to 10 degrees Celsius, aluminum plate, thermal expansion and contraction is larger, the interface displacement is larger, sealant caulking, the actual displacement interface is composed of glue to bear, during the curing process, repeated telescopic displacement too big, will cause the glue foaming, so in plastic injection to avoid direct noon sun the strongest, to improve some of the foaming conditions.

(7) dry climate in northern areas in spring

The silicone sealant should be chemically reacted to an elastic seal with the aid of the moisture in the air. The relationship between the humidity in the air and the curing rate is very close. In North China, the climate is dry in spring, and the curing time is long after silicone sealant is injected. The silicone sealant before curing is easily influenced by external environment and provides opportunities for all kinds of bubbling phenomena.

2. why is the sealant solidified slowly?

The objective conditions of the first sizing have a great influence on the deep curing speed. For example, the construction environment, temperature and humidity have a great influence on the curing speed. When the temperature is too low, most of the humidity will slow down the deep curing. In addition, there is ventilation in the construction site. If the air flow is not smooth, it will also affect deep solidification. In addition, the design of glue joints also has a great influence on deep solidification.

When the glue seam width to depth ratio of inappropriate or too deep, deep curing slower; general deep curing is a bit slow, there is no quality problems in the presence of (such as foaming, not internal solidification etc.) does not affect the actual project, the specimen curing period of the national standard for 21 days, and test and in the actual project sizing is completely equivalent to the thickness, curing time of national standards that need 21 days, and the curing reaction we slow far less than 21 days (more than 5-7 days to reflect slow); also we believe that the sealant curing too fast for long-term use is not very good, because cure too fast is not conducive to the temperature stress caused by the release of the curing process, the existence of hidden dangers. If the curing time of concrete is limited, it will cause stress concentration and crack if it is too fast.
 

3. why does the sealant crack after curing?

The real cracking of rubber strips is very rare after being solidified. Due to too few cases and some objective situations, it is not clear why it is produced. The cracking mainly refers to the degumming of the substrate caused by poor adhesion to the base material, and also called cracking.

There are several reasons for this reason (except inferior glue).

一、The compatibility is not done well or did not do the compatibility test at all, that is, the incompatibility of the glue to the base material leads to the cracking.

二、It is the cause of construction, the substrate surface is not clean or improper construction, such as the solvent is not dry and the construction or cleaning time is too long and polluted.

Most of the reasons for the cracking of sealant after curing are caused by improper construction.

4. after curing, the surface of the adhesive strip is wrinkled and uneven. Why?

This joint sizing more in vertical, which causes should be the initial sizing, mortar on the surface wetting speed is slow, the initial adhesion is poor, resulting in weight due to sealant formed by dropping wrinkle, uneven phenomenon; suggestions in the construction of the construction within the scope allowed to extend the dressing time. At the same time, change the dressing operation, use a scraper from the bottom up glue trimming trimming; also need to pay attention not to over extrusion, otherwise easily lead to deformation of rod liner foam, after foam stick will be gradually restored, resulting in the overall muster sealant.

5.Why do porcelain white sealants have the phenomenon of turning yellow and turning red?

Occasionally, this phenomenon occurs. The analysis may be caused by the unstable quality of the auxiliaries, or the contamination of the attachments or other materials contacted with the cured rubber strip.

6. why does the neutral transparent glue (ketoxime type) become yellow or even red after curing?

Ketoxime transparent glue (including light curing adhesive) in about twenty days will turn yellow in different degrees, and with the increase of time, yellow would have exacerbated the trend, here ketoxime yellow transparent plastic is not individual manufacturers problems existed in the whole industry but a product of the problem, including foreign manufacturers. The analysis may be due to the addition of the coupling agent with the amino group.

Although the yellowing is inherent defects now, but curing of yellowing has great influence, first of all, ketoxime type transparent glue and glue and not acid alcohol glue of peaceful coexistence, it and the other two kinds of glue together in less than three days, ketoxime type transparent glue will become serious yellow. In addition, putting the cured ketoxime type transparent glue in the dark and damp corner will also cause it to turn yellow until red.

7. why sealant is not good for some building materials (such as aluminum, aluminum plastic plate, type steel, etc.) adhesion?

This phenomenon uses two sentences to explain the  diversity of building materials and the instability of sealants.

First of all, the diversity of building materials: now there are many kinds of building materials in the market, such as aluminum, there are spraying aluminum and anodic aluminum oxide. Spraying aluminum and electrophoresis, and other fluorocarbon coating, surface properties are different, so need to experiment to know the pros and cons of adhesion, and PVC (polyvinyl chloride) as raw materials in general PVC, while also adding plasticizer and filler, but now many manufacturers, the material is not the same, so there are great the uncertainty.

Besides, the instability of sealants: as chemical products, many factors that affect quality cannot be directly observed. Therefore, we recommend that compatibility tests should be done before construction.

8. why are weather resistant adhesives so fast that the time of repair is insufficient?

Weather resistant adhesive surface dry time in 30-40 minutes, for a normal construction is not short, but in the construction of the environment change (such as high temperature) when dry will become faster, so there will be less than the same dressing, in temperature reduced, dry and prolonged, so to take into account the high temperature of the table dry time table is moderate, stem will be very long in the environment temperature is lower, which will make the tack free time longer, which affects the project acceptance. So in order to reduce the effect of dry fast, it can be improved by adjusting the number of trimming.
 

9. why does the sealant find the uneven color and other uneven conditions after the sealant extrusion?

This kind of phenomenon is mainly caused by pollution in the process of production or packaging, and it is the problem of production quality control.

10. why do you sometimes find a small number of brittle solid solids near the bottom of the sealant bottle?

This is a phenomenon that the product basically exists now. The reason is because the bottom cover and seal the bottle is not very close, there is a small amount of lead to curing and curing with near plastic contact will form a solid and brittle and hard, this phenomenon does not occur in contact with other materials, but also does not appear any quality problems.

11. why are there particles in the sealant?

If there are large particles or larger rubber in the sealant, it is a control problem in the process of production, and can be solved by strengthening management and strengthening control.

If there are small particles in the sealant, it needs to be treated differently. There are two main cases:

One is the powder particles, because all are required to join in the rubber reinforcing filler, the most commonly used for calcium carbonate and silica, are solid substances, and solid and liquid mixture, the solid particles are small, the surface can easily form aggregates, thus it is very difficult to completely dispersed in the liquid, forming some small particle. Judgment is the powder particles is the basis of small particles inside the rubber hand rolled out, after still, if not in the powder particles; the actual use of sizing although you can see that there are small particles, but the gum itself is leveling, leveling and surface can slowly cover some small particles but, sizing belongs to super close observation, if the construction after the farther view (about a foot distance) is hard to find a lot of particles.