Butyl Reclaim (GRP BRI 75R) Now Stocked

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J. Allcock & Son’s will now be STOCKING GRP BRI 75R Butyl Reclaim (Formerly BT.999.)

We have decided to take this important step forward in butyl reclaim supply, as there has been a huge increase in demand over the past year and we expect this to continue throughout 2013.

J. Allcock & Son’s, where possible will always try to be your most flexible supplier. We understand the need to deliver a high quality service. After all, what is the point of using a high quality product, if you do not know that you are going to receive it when you need it?

  • GRP BRI 75R is manufactured by Gujarat Reclaim & Rubber Products Ltd., India.
  • GRP BRI 75R is a reclaimed rubber made from Butyl inner tubes, together with reclaiming aids.
  • GRP BRI 75R is PBN free and PAH conformant.

Product Description

  • Colour: Black
  • Form:   “Blanket”

Composition

  • Carbon Black:            32 ± 4%
  • RHC (by difference):  50% min
  • Ash Content:              4 ± 2%
  • Acetone Extract:        9 ± 3%

Properties

  • Specific gravity:                                1.14 ± 0.02
  • Mooney Viscosity at 100°C:             30-45 ML 1+4
  • Hardness Shore A:                           51 ± 3
  • Tensile Strength:                              75 kg cm^-3 min
  • Elongation @ Break:                        480 % min
  • State of refining:                               Superfine

Data sheets for GRP BRI 75R can be found online, in our data sheet library or on the butyl reclaim product page.

J. Allcock & Sons Ltd. also stock GRP NRM 35R (formerly GR.444 Tyre Reclaim) and GRP NRC 25R (formerly RT-SLAB Tyre Reclaim)

J. Allcock & Sons Ltd. are the official UK distributors for Gujarat Reclaim & Rubber Products Ltd.

For any further technical questions on GRP BRI 75R, please feel free to phone or email, and ask for Norman or Luke.

Masterbatch – New Range

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In the past year, we have found an increasing number of customers asking for anti mist / anti fog masterbatch for use in PET and PP plastic. Primarily in the food packaging market.

Anti mist / anti fog  PET/PP masterbatches will prevent condensation forming on the inside of food packaging.

We have therefore been in discussions with suppliers to offer a new range of additive masterbatches. This range will also include anti block masterbatches for PET & PP, we have also found there to be a small market for this type of masterbatch. Anti block masterbatches are an alternative to our Allcosil 435 FG food grade silicone emulsion.

As of 01/01/2013 we can offer the following masterbatch:

  • Non-crystallised PET AB(Anti block)
  • Crystallised PET AB(Anti block)
  • PP AB(Anti block)AF(Antifog)
  • * We are in the process of researching with our new partner a suitable PET Antifog/Antimist – Please still enquire *

If any of our new masterbatch range interests you, we would be happy to arrange 20-kg samples. Our masterbatches could be added at approximately 2%, therefore a 20-kg sample will give you a 1 tonne trial.

Data sheets for our range will be in the Data sheet library and masterbatch products section (found under silicones) in the new year.

J. Allcock & Sons always tries to adapt to customers needs.

Silicone Oil (Polydimethylsiloxane) & Emulsion

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J. Allcock & Sons we have been supplying silicone products (silicone oil, silicone emulsion, silicone grease, and more) to many industries since the 1970′s. Therefore we have decided to explain some of the chemistry behind the two most popular; silicone oil and silicone emulsion. We hope you find it useful.

Silicone Oil

First of all, silicone oil has many different names; silicone fluid, polydimethylsiloxane, dimethicone, dimethylpolysiloxane, dimethyl siloxane, PDMS. J. Allcock & Sons have branded our silicone oil Allcosil 200 (which only adds further to the confusion!)

Technically, we believe that polydimethylsiloxane best describes the oil. Poly (Latin for many), dimethyl (two methyl (CH3) group) siloxane (Silicone and Oxygen).

The chemical structure of polydimethylsiloxane is:

n= number dimethylsiloxane units.

Buyers of polydimethylsiloxane will be aware that it is available in a number of different viscosities. The most common being; 100cSt(centistoke), 350cSt and 1000cSt. The number of dimethylsiloxane units depicts the size of the polymer chain which determines the viscosity. The smaller the polymer chain the lower the viscosity (e.g. 100 cSt) , the bigger the polymer chain the higher the viscosity (e.g.1000cSt).

Our one product in the Allcosil 200 range that is slightly different is our lowest viscosity Allcosil 200; 0.65cSt. Allcosil 200/0.65 has only two units, this means that it is not a polymer, but a dimer. The dimer is hexamethyldisiloxane.

The chemical structure of hexamethyldisiloxane is:

File:Hmds.png

It is clear that when you compare it to the polydimethylsiloxane structure that the dimer is very similar to polydimethysiloxane.

The polymer chain length also has an effect on other properties of the oil.

Viscosity, cSt Flashpoint, °C COC Freezing Point,°C Specific Gravity, @ 25°C Surface Tension, mN/m Refractive Index, @ 25°C
0.65 -4 -67 0.760 15.9 1,375
1 40 -85 0.816 17.4 1,382
2 48 -90 0.830 18.1 1,387
3 62 -100 0.900 18.9 1,392
5 136 -100 0.910 19.7 1,397
10 162 -65 0.930 20.1 1,399
20 230 -60 0.950 20.6 1,400
50 280 -55 0.959 20.7 1,402
100 >300 -55 0.965 20.9 1,403
200 >300 -50 0.970 21.0 1,403
300 >300 -50 0.970 21.1 1,403
350 >300 -50 0.970 21.1 1,403
500 >300 -50 0.970 21.1 1,403
1000 >300 -50 0.970 21.2 1,403
5000 >300 -50 0.975 21.4 1,403
10000 >300 -50 0.975 21.5 1,403
12500 >300 -50 0.975 21.5 1,403
30000 >300 -50 0.975 21.5 1,403
60000 >320 -50 0.975 21.5 1,403
100000 >300 -50 0.976 21.5 1,404
300000 >300 -45 0.976 21.5 1,404
1000000 >300 -40 0.976 21.5 1,404

(1000000 cSt, longest polymer chain.)

It is clear from the table showing properties, that after 50cSt, the polymer chain length becomes less important in effecting the properties.

According to the FDA Regulation 21 CFR, certain viscosities are food grade. For more information, please contact us.

Silicone Oils have many uses due to their lubrication, dielectric and water repellent properties.

Silicone Emulsion

Silicone Emulsion contains 3 ingredients; polydimethylsiloxane, emulsifier & water.

The key ingredient is the emulsifier which encapsulates the polydimethylsiloxane oil and holds it in suspension.

A typical emulsifier used in making silicone emulsions is ethoxylated glycol ethers. These emulsifiers have a hydrophobic (dislikes water) and hydrophilic (likes water) part to their structure. The hydrophobic faces the polydimethylsiloxane and the hydrophillic faces the water. This creates a barrier between the water and the polydimethylsiloxane.

Here is a really good picture i found on google. A surfactant (Surface active agent) is just a type of emulsifier.

Unfortunately emulsifiers, due to their chemical make-up, are vulnerable to bacteria. Bacteria can digest certain emulsifiers causing the polydimethylsiloxane to float to the top or disrupt the pH enough for non-digestible emulsifiers to split from the oil. This is called splitting. Splitting in an emulsion can be seen and smelt. The smell comes from the bacterial growth, it usually smells like sour milk.

Emulsions are a key mould realease/lubricant and antifoams for many industries.Our biggest selling emulsion is Allcosil 435 FG, this is sold to the food packaging industry. It is food grade and kosher certified.

 

If you have any questions, please feel free to leave a comment.

Differences between Size Reduction, Reclaiming and Devulcanisation, in the recycling of rubber.

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Differences between Size Reduction, Reclaiming and Devulcanisation in the recycling of rubber.

We have consistently found that the rubber industry confuses itself when discussing recycled rubber. Information has started to become lost and miss-translated; people have stopped collaborating and sharing their knowledge. The purpose of this blog post is to hopefully clear up the difference between the three types; size reduction, reclaiming and devulcanisation. I have already written about both size reduction and reclaiming processes and their advantages, but feel a post about the differences between all three at once,  is worth my time.

First of all, let’s quickly discuss each process:

Size Reduction

Recycled rubber has now become the term most associated with size reduction recycling. This is due to the fact that there has been no chemical process involved in the recycling process. It has been, exactly as named, “Reduced in size”.

There are 3 main types of size reduction recycling; Ambient Grinding, Cryogenic and Wet Paste.

  1. Ambient grinding is grinding/tearing the rubber to the small sizes at room temperature. This is our preferred recycling technique as we firmly believe it gives not only the most economical sized reduced rubber but also the most reusable (due to its shape giving the largest surface area).
  2. Cryogenic is the freezing of scrap rubber using liquid Nitrogen and reducing the size literally by smashing it to pieces. This is less economical due to the amount of liquid nitrogen used per kilo of scrap rubber (1:1 Ratio). The final shape also gives a much smaller surface area as it has flat surfaces, this means less rubber can lock/bond into the rubber compound.
  3. Wet Paste is another grinding technique. This is where the rubber is ground while in water. This can produce finer particles than ambient grinding due to the rubber being in cooled down by the water. Unfortunately this technique is not very economical because the ground rubber almost has an affinity to the water and drying the recycled rubber is extremely hard and costly.

Rubber Reclaim

This is where people start to get confused. Reclaim, Rubber Reclaim, Reclaimed Rubber, as stated is a much more complicated form of recycled rubber, it has been put under a chemical process. In fact, it has been put under a complex thermochemical and mechanical process.

Rubber is first reduced in size and then mixed with oils/reclaiming agents and heat. Without getting into too much detail, this process shortens the polymer chain.

Notes:

  • During the reclaim process small amounts of sulphur cross links may be broken – but not enough to claim it as devulcanisation.
  • For rubbers, such as Nitrile (NBR) which has high chemical and heat resistance, reclaim is not yet possible.

Devulcanisation

Devulcanisation is the rarest of rubber recycling, but probably has the biggest potential. It is the breaking of the sulphur cross links. Breaking these sulphur cross links means that the resulting recycled rubber is almost exactly like the starting rubber compound. The recycled rubber will contain up to 90% of the original properties. This would make it the easiest recycled rubber to reuse.

Unfortunately breaking the sulphur cross links is extremely difficult and not many devulcanisation techniques are available due to economical issues at present. Although Remould.org.uk are getting close.

Differences between Size Reduction, Reclaiming and Devulcanisation:

From the explanations above, the differences are clear.

Chemical Structures:

  • Size reduction has no effect on the chemical structure of the rubber.
  • Reclaiming rubber breaks bonds within the polymer chain (and a small amount of sulphur cross-links) and therefore has an effect on the polymer chain length.
  • Devulcanisation has a small amount of effect on polymer chain length but mostly gives large polymer chains which have no sulphur cross links.

Uses:

  • Size reduction is an additive/cheapener rather than a material for replacing rubber polymer in the rubber compound. The ratio of the original materials in the rubber compound would be the same. Larger, size reduced, rubber (rubber granules) can be used in horse arenas and playground surfaces.
  • Reclaim, unlike size reduction can be used to replace some rubber polymer being added in the rubber compound. In fact, if you really wanted, reclaim could make rubber compound by adding curatives/accelerators, although the quality would be poor.
  • Devulcanisation, similar to reclaim would be able to replace the rubber polymer. In fact, it would probably be able to replace nearly the entire rubber polymer and most of the compound!

Visual:

  • Size reduction of rubber produces, shred (for tyres only), granules and crumb.
  • Reclaim is extruded into blankets on a mill.
  • The best devulcanised rubber would be extruded and would be available like reclaim.

 

I hope this post will shed some light on the confusion between the two different types. If you have any questions feel free to leave a comment and I will get back to you ASAP.

 

Rubber Reclaim

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All kinds of recycled rubber materials are often referred to as “Reclaim”. So much so that you would think it had become a generic term. This is not true. Rubber reclaim, Reclaimed Rubber, or just Reclaim, is a very specific type of material.

It refers to vulcanised (cured) waste or scrap that has been rendered fit for re-use by a complicated thermochemical process.

The waste rubber is granulated quite small to release and facilitate the removal of any metal and fabric that may be present. It is then subject to a combination of heat, pressure and chemical softening / plasticising  agents  for a period of time in a large retort. After discharge, the treated waste is refined to remove any nibs or hard bits of unprocessed material. This is done by extruder sieving and/or a refining mill. The later is like a normal rubber processing mill, but with short, stubby rolls with a pronounced camber and high friction ratio. The material passes repeatedly through the mill and the coarse “bits” are pushed out to the sides of the mill nip (the wider part, due to the camber) and fall out into catchment trays at each side. The good, refined material is taken off the mill as a paper thin sheet and wound up on itself to make thick slab. The material from the sides can be used to make lower grade, coarser “tailings” reclaim.

Basic properties

The reclaim still contains the same amount of rubber hydrocarbon, carbon black, fillers and process aids that were in the original rubber compound, plus the extra softeners that were added. The process has NOT broken the sulphur cross-links, but has broken the polymer chains down into shorter lengths, radiating out from the cross-links. In effect looking like a “star fish” shape.

This produces a new raw material that has the same basic chemical make up as the original, but is :-

  • Softer
  • More pliable
  • Easier to process
  • Will act as a process aid in new compounds
  • “Shape retaining” due to the new 3D structure
  • Capable of being re-vulcanised (requires the addition of sulphur / accelerators or similar). With no further additions it will produce a cured sheet and this is used as one of the basic quality control tests to check hardness, tensile strength, etc of the reclaim itself.

Why should you use it?

For the compounder:-

From a purely technical point of view, it is a raw material that should not be ignored. If you need to formulate a good quality NR or SBR black compound, the addition of tyre reclaim will not add anything that is probably not already there i.e. there will be no compatibility problems.

If you are going to make a cheap, low quality commercial black compound, the sky’s the limit. You can add as much reclaim as you want. (as mentioned above – reclaim alone, plus sulphur and accelerator can be cured just like a full compound. The physical properties are not very high, but they are there, unlike a cheap filler which can only reduce the properties).

If you need to improve the processability, the addition of extra oil or softeners will often leave the uncured compound “limp” and sticky. Reclaim will overcome the problem – it has already been softened and it really will help processing – particularly extrusion and calendering – its 3D structure makes the resultant compound almost thixotropic, retaining its shape when static, but immediately softening when worked (processed).

For the accountant:-

If the original costing has been done correctly, an allowance will have been made for any legitimate waste that the process will generate (trimmings, flash, moulding sprue and runners, short ends etc) and this will have been included in the raw material cost.  However, the use of a proportion of reclaim may enable some of that cost to be recovered.

The improved processing and flow rate may well shorten mixing cycles, extrusion and calendar times, moulding blank preparation, etc.  All with attendant cost savings.

Remember – the higher the current raw polymer costs – the more economical is the use of reclaim.

How do you use it?

A good quality tyre reclaim will have approximately :-

Rubber Content             50%

Ash Content                    7%                 (mainly as zinc oxide + mineral filler)

Carbon Black                27%

Oil + process aids         16%

  • SG will be about 1.14
  • It will cure fully and bond into the compound (it cannot separate at a later date)

So ….. don’t just simply add some reclaim. Take out some of the rubber and replace it with double the quantity of reclaim. Overall, the rubber hydrocarbon content will stay the same. Cure properties will not be noticeably different, physical properties will reduce very slightly (in proportion to the amount of reclaim added), processability and flow rate will improve.

Rubber Crumb / Granules

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The process of making rubber goods produces a certain amount of waste. Some of this will be legitimate, such as flash, sprue, runners, etc, and some (almost inevitably) will be due to rejects and other problems. As long as the waste is cured (vulcanised) it can usually be recycled by size reduction into usable materials again. The ideal situation is when the producer segregates and saves the waste and it is then recycled and used back into their product.

The incoming waste is identified and checked and is then progressively broken down in size by passing it through very high energy cutters and granulators. The granulators have a removable, perforated “basket” as the base and this can be changed as required. The full range of sizes runs from 2.5 to 30mm. The common, usual sizes would be 4 or 6mm, and larger chunks would “whirl” around inside, passing through the cutters again and again, until they were small enough to fall through the basket. Vibrating sieve units separate or grade the output. High strength magnets are used at every possible flow point to ensure that any residual metal particles are removed. The product may need multiple passes and will then be bagged (25kg or “big bags”).

At this stage the material is known as “granules” and has a ready outlet in safety surfacing and the like.  It is used in the same way as the stone “chips” in tarmac. A typical specification would be 6 – 2 mm rubber granules – that means that no particle will be larger than 6mm and anything smaller than 2mm will have been removed (i.e. no dust) – that would be used as Base Layer for a surface. Another grade would be 4 – 1mm (on a similar basis) and would be used for the Top Coat  i.e. the visible surface. The sizes can be varied as required and the material used could be Tyre Rubber, EPDM, Nitrile etc. This type of material has a relatively low added value.

Rubber Crumb

This is where the real value of this type of recycling can be found.

The waste rubber is first granulated to about 4mm and then passed to a series of rotary grinding machines. Again, magnets are used at every possible place to remove any particles of residual metal (mainly from the original tyre construction). Once started, the process continues automatically – the powder is fed to sealed sieve units where the only exits are:

  • Correct sized material to the bagging units
  • Oversize material, which has not passed through the sieve, is automatically returned to the system and is reground until it is the correct size.

The actual sieves can readily be changed to make a wide range of particle sizes, and unlike some processes, our stated sieve size means the largest possible size the crumb can be – not the average.

Basic properties

In essence, the true basic properties of the material are the same as the properties of the waste material used to make the crumb or granules. However, the real properties that we are interested in are as follows:-

  1. A relatively inert material of known and controlled particle size (no oversize or dust)
  2. A material that is compatible with the type of rubber compound it is going back into.
  3. A material with a jagged, partially activated, very high surface area that will chemically bond into the rubber article when it is cured (vulcanised)  -   (crumb particles cannot be seen on the surface of the cured article, nor can they be “prised out” – crumb is used as an anti-tack dusted onto the surface of tyre sidewall veneer compound, that disappears completely when the tyre is cured).
  4. A material that is very cost effective, environmentally sound and technically viable

(Note: For very high tech applications (FKM etc) the compounder / producer can have peace of mind knowing that the only chemical materials in the crumb are exactly the same as in the product they are making – no compatibility or contamination issues.  That is of course, as long as they make use of our bespoke service, where they supply THEIR waste material, and we use it (and nothing else) to make THEIR own crumb.)

Why should you use it?

For the compounder:-

a)     The low initial cost and the possible value recovery aspects will make you popular

b)     The technical aspects can be extremely useful –

In small additions of 5 to 10 phr (parts per hundred of rubber)

  • It can reduce air trapping
  • It can reduce “laking” on the surface of “flat” mouldings
  • It can improve hot tear strength
  • It can reduce flow, or excessive “creep” in the uncured rubber

In larger additions – above 10 phr, to as much as you like – see i.

  • Physical properties will fall in relation to the amount of crumb added. If there are no physical requirements – cheap ladder feet, wheel barrow tyres, sleeping policemen  etc, over 50% of the total weight can easily be added.
  • As a cheap filler it is a low S.G., readily compatible blend of hydrocarbons and mineral material.  In very high additions it may be necessary to increase the amount of sulphur / accelerators slightly.

For the accountant:-

a)     It is low price material in the first place.  The word “cheap” conjurers up the wrong idea.

b)     Taken in conjunction with a robust system of internal waste collection and segregation – which is then passed onwards to the recycler – hopefully to be returned as “house” crumb – the economic advantage is completely maximised :-

  •  A useful, low cost raw material put back in stock
  •  Value recovery of internal waste and scrap
  •  Elimination of waste rubber disposal costs

How do you use it ?

Just like any other rubber filler.  If large amounts are used it will be better to add it after the addition of any oils, plasticisers or process aids.  It can have a tendency to absorb the oils resulting in slightly higher hardness than expected.